JP2016105515A - Cutting method of semiconductor substrate and cutting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cutting method of a semiconductor substrate capable of efficiently obtaining chips of stable quality and a cutting device.SOLUTION: The method includes: a grinding step of developing a micro crack extending from a modified area while uniformly sucking a surface of a wafer on which the modified area is formed inside with laser to a table and grinding a rear surface of the wafer to remove the modified area; a polishing step of polishing a wafer to be a mirror surface after the modified area is removed; and a cutting step of cutting the wafer after the mirror polishing.SELECTED DRAWING: Figure 15

Description

  The present invention relates to a semiconductor substrate cleaving method and cleaving apparatus for cutting a semiconductor substrate into chips.

  In Patent Document 1, a semiconductor substrate placed with the back surface facing upward is irradiated with a laser to form a modified region inside the substrate, an expand tape is attached to the back surface of the semiconductor substrate, and a knife is applied from above the expand tape. It describes that a semiconductor substrate is cut into chips by applying an edge and dividing the substrate with the modified region as a base point.

  Further, Patent Document 1 discloses that a semiconductor substrate placed with the back surface facing upward is irradiated with laser to form a modified region inside the substrate, and then the substrate is ground and thinned. It is described that the substrate is divided based on the modified region by attaching the tape and extending the expanded tape.

  In Patent Document 2, a semiconductor substrate placed with the back surface facing upward is irradiated with a laser to form a modified region inside the substrate, thereby generating a crack in the thickness direction of the semiconductor substrate, and It describes that a semiconductor substrate is cut into chips by exposing cracks to the back surface by grinding and chemical etching. Patent Document 2 discloses that a natural stress or a relatively small force, for example, an artificial force or a thermal stress is generated by applying a temperature difference to the substrate, thereby causing a crack in the thickness direction from the modified region. It is described that it occurs.

Japanese Patent No. 3624909 Japanese Patent No. 3762409

  In the invention described in Patent Document 1, the substrate is cracked by applying an external force locally with a knife edge. In order to apply the external force locally, bending stress or shear stress is applied to the substrate. However, it is difficult to distribute bending stress and shear stress uniformly over the entire surface of the substrate. For example, when bending stress or shear stress is applied to the substrate, the stress is concentrated at some weak point, and the necessary minimum stress cannot be uniformly applied to a desired portion efficiently.

  Therefore, there is a problem in that the substrate breaks and the substrate breaks even in the chip when the crack does not proceed slowly. In addition, when cutting a portion of the substrate by applying stress locally in order, for example, when collecting a large number of chips from a single substrate, there are a large number of cutting lines. There is a problem that productivity is greatly reduced.

  In addition, when the substrate is cracked by applying an external force, if the substrate is not processed thinly, there is a problem that a very large stress is required when the wafer is cracked.

  In particular, when the substrate thickness is sufficiently thick with respect to the modified depth of laser processing, even if an external force is applied, it is not always possible to cleave the substrate cleanly and perpendicularly to the substrate due to the influence of the abrupt external force. Therefore, it may be necessary to irradiate several laser pulses in multiple stages in the thickness direction of the substrate.

  Further, in the inventions described in Patent Documents 1 and 2, the modified region formed inside the substrate by the laser irradiation finally remains in the chip cross section. Therefore, dust may be generated from the modified region of the chip cross section. In addition, as a result of the chip cross-sectional portion being locally crushed, the crushed cross section may be a trigger to break the chip. As a result, there is a problem that the bending strength of the chip is reduced.

  In the invention described in Patent Document 2, it is described that cracks naturally occur in the thickness direction from the modified region, but there are cases where cracks do not necessarily occur naturally when they crack naturally. In order to inevitably obtain the stable effect of cracking, it is sometimes necessary to take arbitrary measures, and if it breaks naturally, it does not fall under arbitrary measures.

  In addition, as a relatively small force, it is conceivable to generate a thermal stress by giving a temperature difference to generate a crack in the thickness direction from the modified region. In this case, there is a problem that it is very difficult to give a uniform thermal gradient in the plane of the substrate. That is, even if a thermal gradient is artificially applied, heat is dispersed in the substrate so as to alleviate the partial thermal gradient by heat conduction. Therefore, there is a very difficult problem in how to constantly form a stable thermal gradient (stable temperature difference) enough to cut a certain substrate.

  In the invention described in Patent Document 2, the semiconductor substrate is ground and then chemically etched on the back surface. However, after grinding, the ground surface is left with grinding streaks due to fixed abrasive grains and accompanied by minute cracks. Is formed, and the work-affected layer remains. When the surface is chemically etched, a portion having a large lattice strain such as a microcrack is selectively etched. Therefore, micro cracks are promoted and become large cracks. For this reason, there is a problem that not only the cutting start region but also a small crack formed by grinding and etching sometimes breaks, and it is difficult to perform stable cutting.

  Further, since the unevenness of the substrate surface is promoted by etching, the substrate surface is not mirror-finished. For this reason, since the unevenness remains in the divided chips, it can be considered to be broken from a large unevenness portion, that is, a micro crack, and there is a problem that the bending strength of the chip is lowered.

  Further, when the etching solution is applied to the modified portion that has been laser processed, the modified portion is once melted and recrystallized, so that a large grain boundary is formed.

  When an etching solution acts on such a grain boundary portion, etching proceeds so that silicon grains are peeled off from the grain boundary.

  Specifically, as the polishing process, it is described in the cited document p.12_1 line that the grinding process and chemical etching are performed on the back surface. In the case of chemical etching, even if it is left as it is, the chemical etching solution penetrates into the cracks and has the effect of dissolving the cracks.

  In particular, when the crack has advanced to the surface of the substrate, the etching solution permeates between the chip and the film adhering the chip, thereby causing a problem of peeling the chip from the film.

  Even if the crack does not run to the surface of the substrate, the etching proceeds along the crack. Especially when etching in a thin state after grinding, the etching solution penetrates into the crack by capillary action, deepens the micro crack while melting the crack tip, and further enters a new etching solution there Become. In this case, if the etching solution acts in the vicinity of the device surface, the vicinity of the device surface is melted, and etching may proceed to the inside of the element. Even if there is no problem at that time, the etching solution left on the wall surface of the wafer may enter the inside of the device and cause a defect thereafter. Therefore, while removing the processing distortion on the wafer surface, it may further promote cracks and induce secondary problems.

  Further, in such a case, as a result, the crack may be advanced to the surface, and an etching solution may partially enter between the chip and the film, and the chip may be peeled off during processing. In particular, when grinding progresses after grinding, cracks tend to progress with a slight external force, and chip peeling occurs when the cracks reach the surface. It must be processed so that it does not progress further.

  Patent Document 2 describes that a crack is generated from the modified region by grinding the back surface of the substrate, but Patent Document 2 does not describe a method for fixing the substrate when grinding the substrate. . When the outer periphery of the substrate is supported by fitting the substrate into a retainer or the like as shown in FIG. 21 or when only a part of the substrate is adsorbed as shown in FIG. Since it is not restrained, in such a case, even if the back surface of the substrate is ground, cracks do not occur from the modified region.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a semiconductor substrate cleaving method and cleaving apparatus that can efficiently obtain a stable quality chip.

  In order to achieve the above object, the method for cleaving a semiconductor substrate according to the first aspect of the present invention is a cleaving method for cleaving a wafer having a modified region formed therein with a laser beam. A grinding step of adhering to a table and grinding the back surface of the wafer to remove the modified region while causing micro cracks extending from the modified region to propagate in the wafer depth direction, and the modified region by the grinding After the removal, the polishing step of polishing the wafer to make a mirror surface, and the cleaving step of cutting the wafer after the mirroring.

  The method for cleaving a semiconductor substrate according to a second aspect of the present invention is the first aspect, wherein the grinding step is ground using a polishing grindstone, and the polishing step is polished using a polishing cloth.

  A cleaving apparatus for a semiconductor substrate according to a third aspect of the present invention is a cleaving apparatus for cleaving a wafer having a modified region formed therein with a laser beam, wherein the surface of the wafer is uniformly adsorbed on a table, Grinding means for developing microcracks extending from the modified region in the wafer depth direction while grinding the back surface to remove the modified region, and after the modified region is removed by the grinding, the wafer Polishing means for polishing the wafer into a mirror surface and cleaving means for cleaving the wafer after the mirror surface.

  The semiconductor substrate cleaving apparatus according to a fourth aspect of the present invention, in the third aspect, performs grinding by the grinding means and polishing by the polishing means on the same table.

  The present invention also includes the following technical ideas.

  That is, according to one aspect of the present invention, laser light is incident from the back surface along the step of attaching a back grind tape to the front surface of the wafer, and the cutting line of the wafer having the back grind tape attached to the front surface. Forming a modified region within the wafer to form micropores in the modified region; and a surface of the wafer on which the modified region has been formed in the modified region forming step. An adsorption process for adsorbing substantially the entire surface to each table independently and uniformly, and removing the modified area by grinding the wafer having substantially the entire surface adsorbed on the table in the adsorption process from the back surface, A grinding step for causing micropores to propagate in the thickness direction of the wafer, and a step for chemically and mechanically polishing the wafer in which the micropores have propagated in the thickness direction of the wafer in the grinding step. A step of attaching an expanded tape to the back surface of the wafer mechanically polished; and the wafer having the expanded tape attached to the back surface is pressed with a pressing member via the expand tape. A cleaving step of cleaving, and a dividing and separating step of dividing the cleaved wafer into a plurality of chips by stretching the expanded tape.

  According to the above aspect, the protective back grind tape is attached to the surface of the wafer by the mechanism for attaching the tape. After the back grind tape is pasted, a laser beam is incident from the back surface of the wafer along the cutting line to form a modified region in the wafer, thereby forming micropores in the modified region. The wafer is ground from the back surface in a state where the entire surface of the wafer on which the modified region has been formed is adsorbed uniformly and uniformly on the surface of the substrate, and the modified region is removed.

  At this time, due to the grinding heat generated by the grinding, the wafer surface being ground is thermally expanded in the radial direction and tends to spread. However, on the other hand, the wafer tends to be prevented from spreading due to expansion by a wafer vacuum chuck having a large heat capacity.

  As a result, the wafer surface expands due to thermal expansion, while the back surface of the wafer being chucked does not expand due to the vacuum chuck and tries to maintain the state as it is. As a result, the modified region formed inside the wafer acts so as to further expand the modified region in accordance with the difference in expansion between the front surface and the back surface of the wafer, and further cracks progress. The modified region is irradiated with laser light and once melted and recrystallized, so that the crystal grains are large and fragile. When such a modified region appears on the side surface of a future chip, dust is generated from the side surface of the chip, and large crystal grains may be chipped from the side surface of the chip. However, since the microcracked part that has developed from the modified region is a pure crystal surface, even if this surface appears on the future chip side surface, dust is generated from the chip side surface or chipped as large crystal grains. There is no such thing.

  In this way, the wafer is removed while being ground by the grinding process, and the micropores are developed in the thickness direction of the wafer to remove the modified region. Next, in order to make the work-affected layer formed by grinding and the developed micropores stand out, chemical mechanical polishing is performed on the entire wafer surface (detailed later) to completely remove the work-affected layer. To do. As a result, only the minute holes remain on the surface, and the remaining region becomes a complete mirror surface with no processing distortion.

  Then, an expanded film is stuck by the mechanism which sticks a tape with respect to the back surface of the wafer which is not yet broken. Subsequently, one cutting line is cleaved by a pressing member provided in a mechanism for attaching a tape positioned parallel to the cutting line. After all of one cutting line is cleaved, the wafer is rotated 90 degrees and the other cutting line is cleaved. Then, the back grind tape is peeled off from the cleaved wafer, the expanded film is expanded, and the chips are separated. Thereby, it is possible to prevent the modified region formed by the laser beam from remaining in the cross section of the chip. Therefore, it is possible to prevent a problem that the chip is broken or generate dust from the cross section of the chip and efficiently obtain a chip having a stable quality.

  Further, since the wafer is divided after the back surface of the ground wafer is subjected to chemical mechanical polishing, the bending strength of the chip can be increased. Here, the chemical mechanical polishing is largely distinguished from the etching process in the polishing process shown in the cited document 2.

  First, the chemical solution in the present invention is different from the etchant of the cited document 2. The etching solution in the cited document 2 has an action of dissolving the substrate naturally by the action of the solution on the substrate surface, that is, etching. Thereby, even in the portion where the crack is generated, the etching solution penetrates and the surroundings are naturally etched, so that the modified layer formed by the laser is further enlarged. Further, in the case of the conventional etching solution, as described above, the etching solution penetrates too much into the cracks to cause the cracks to progress, and finally penetrates to the portion between the chip and the film. As a result, the etching solution may flow to the chip surface, and the chip surface may be eroded by the etching solution, so that each chip device may not function.

  In contrast, the abrasive (slurry) used in the chemical mechanical polishing of the present invention has no etching action under static conditions. That is, even if only the abrasive is supplied to the wafer, the etching does not proceed at all, and the wafer surface is simply modified. For this reason, even if the abrasive enters the crack in the cutting line of the wafer, the surrounding silicon is not melted, so that the crack does not further develop.

  As a result, cracks may develop in the polishing process, ie, the etching process in the cited document 2, but in the polishing process of the present invention, the wafer is not etched at all even if it is left with an abrasive, so that the cracks hardly progress. do not do. As a result, the conventional problem that the abrasive penetrates and peels the chip from the film on its own, or the abrasive wraps around the chip surface and erodes the chip, causing the chip device to fail. There is no.

  Here, the mechanism of chemical mechanical polishing is as follows. That is, in polishing, the polishing agent is first supplied to the wafer, which only chemically modifies the wafer surface. Next, since the modified surface is soft, the abrasive grains contained in the slurry act on the wafer surface in this state, so the wafer surface can be efficiently removed even with a very small stress. is there.

  For example, a silica-based slurry is used in the process of removing silicon. When a silica-based slurry is used, the following reaction occurs on the wafer surface.

[Equation 1]
Si (-OH) + SiOH = SiO2 + H2O
That is, the wafer surface immediately after polishing usually contains Si atoms. This Si atom is hydrated on the surface in water, and —OH is present on the surface of the Si atom. The OH groups attached to the surface of the Si substrate are combined with the silica sol SiOH present in the liquid and the SiOH present on the silica particle surface.

  However, this alone does not advance the etching. As a result, a polishing pad containing a large amount of silica particles in this state is moved relative to the substrate, and the silica particles act on the substrate surface under a certain momentum. It is mechanically removed while the chemical reaction proceeds under the environment and pressure environment.

  At this time, the effect of further developing the crack does not work due to the silica sol or silica particles that have penetrated the crack. This is because the polishing pad does not enter the crack, so that the mechanical action does not work and consequently no chemical removal action occurs.

  As a result, the process-affected layer on the substrate surface generated during grinding is supplied with a chemical slurry containing silica sol and silica particles, and a mechanical frictional action is applied when the polishing pad comes into contact with the substrate. Along with this, only the substrate surface is removed by chemical mechanical polishing (Toshiro Dohi: edited by Semiconductor CMP Technology (Industry Research Committee) (2001) p. 40-42).

  As a result, most of the work-affected layer on the wafer surface is removed. The formed wafer surface is a mirror surface. The principle of this mirror surface is as follows when compared with the chemical etching disclosed in Cited Document 2.

  In the case of chemical etching, as described above, lattice strain and crystal defects are selectively etched in a crystal such as silicon. For this reason, etch pits are formed, or large pits occur along the crystal grain boundaries, which cannot be avoided in principle.

  On the other hand, in the case of chemical mechanical polishing, as described above, the chemical removal action does not work unless the mechanical action works. The mechanical action, in this case the rubbing of the wafer surface with the polishing pad, will occur with equal probability on all substrate surfaces, regardless of the crystalline state of the substrate surface. . Therefore, since all the surfaces are uniformly removed regardless of the crystal state, the chemical action is exerted, so that the surface is uniform and free of crystal defects and becomes a mirror surface. Here, even if it is called a mirror surface, it is ambiguous from a relative viewpoint. Therefore, in this specification, it is defined as a mirror surface obtained by chemical mechanical polishing.

  By performing such chemical mechanical polishing, an ideal mirror surface state can be obtained, which is greatly different from the cited document 2, and erosion due to penetration of the etching solution between the chip and the film can be prevented.

  In addition, after chemical mechanical polishing, the chip is not yet completely broken. It only leaves the micropores that have developed from the modified layer on the surface portion after partial chemical mechanical polishing. The modified layer has already been removed by the previous grinding process.

  When the state of leaving the microvoids that have advanced from the modified layer is formed in a surface state that has been subjected to grinding and etching as shown in, for example, cited document 2, micropores that have advanced from the modified layer; It becomes impossible to clearly distinguish the unevenness promoted by the etching process after grinding. Therefore, when the chip is cleaved, the chip does not necessarily break from the minute holes, and in some cases, the ground grinding trace may be broken from the uneven portion further promoted by etching.

  When the surface is subjected to chemical mechanical polishing as in the present invention, the processed wafer surface has almost no unevenness, and only the minute holes that have advanced from the modified layer remain. Therefore, when the cleaving process is performed in this state, cracks further develop from the minute holes and cleave.

  Thus, in the method of the present invention, even after grinding and chemical mechanical polishing, the micropores become large and cracks develop, but the substrate is not completely divided. If cracks develop during grinding or chemical mechanical polishing and the substrate is completely divided, the chips on the outer periphery of the wafer cannot withstand the shear stress during grinding and polishing and are peeled off from the adsorption table. There is a problem that causes chipping.

  However, in the present invention, cracks develop even after grinding and polishing, but they are not completely divided. In order to further develop a crack from a state where it is not completely divided and to completely break it, a step of further breaking is required. In the cleaving step, after an expanded tape is attached to the back surface of the wafer, the pressing member is pressed through the tape to locally apply bending stress to the wafer. This makes it possible to efficiently cleave starting from a crack developed by grinding.

  Here, when the expanded tape is not attached, the wafer is directly pressed by the pressing member, and when the wafer is cleaved, the vibration of the crack is propagated in the wafer surface. The propagated vibration may be incidentally broken by other parts of the cutting line or may be broken by parts other than the cutting line.

  However, by applying the expanded tape and applying stress by the pressing member through the tape, the tape absorbs vibrations of cracks when the wafer is cleaved, so that no extra vibration is generated. Further, since the expanded tape is stuck in a stretched state without any wrinkles or offset, a constant tension is constantly applied to the wafer, and the wafer is constrained. If the wafer is constrained when the wafer is cleaved, the bending deformation of various parts of the wafer is restricted, and the pressing force of the pressing member is bent against the cracked part that is a weak part inside the wafer. Instead, it concentrates as a shearing stress. Thereby, only the part which is originally cut is efficiently cut, and the part other than the cutting line is in a protected state and is not broken.

  In particular, when tape is applied to both surfaces of the wafer, the vibration of cracking is completely contained and the bending of the wafer is further restricted, so that efficient cleaving is possible.

  Another aspect of the present invention includes a step of attaching a back grind tape to the front surface of the wafer, and a laser beam incident from the back surface along the cutting line of the wafer on which the back grind tape is attached to the front surface. By forming a modified region inside the wafer, a modified region forming step for forming micropores in the modified region, and a surface of the wafer on which the modified region is formed in the modified region forming step The process of adsorbing the substantially entire surface uniformly and independently to the table in each area, and grinding and removing to the part before the modified area formed inside the wafer by entering the laser beam with the wafer adsorbed Then, a first grinding step for causing micro cracks extending from the modified region to propagate in the depth direction of the substrate, a second grinding step for grinding and removing the modified region formed inside the wafer, and the wafer surface are modified. While performing chemical mechanical polishing using a chemical slurry and a polishing pad, the work-affected layer introduced in the first and second grinding steps is removed to leave the surface while leaving a microcrack extending from the modified region. The step of mirror-finishing, the step of sticking an expanded tape to the back surface of the wafer whose surface is mirror-finished, and the wafer having the expand tape stuck to the back surface are pressed with a pressing member via the expand tape. The cleaving step of cleaving the wafer, and the dividing / separating step of dividing the cleaved wafer into a plurality of chips by stretching the expanded tape.

  According to the above aspect, the modified region is formed at a deep position inside the wafer in the initial stage, and is initially formed in the modified region by performing removal processing while generating grinding heat in the first grinding step. It is possible to propagate the crack to a deeper position on the wafer.

  However, in the first grinding process, when the laser-modified region is ground and removed with the same capacity as the unmodified region, the modified region has a large grain boundary, so that large crystal grains may be lost. Along with these crystal grains, even more fatal cracks may develop. Therefore, in the first grinding step, it is preferable to perform grinding to a portion before the modified region where the crystallinity is constant.

  In the second grinding step, the region modified mainly by the laser is ground. At this time, the grinding wheel also has a high count, that is, a grinding wheel having a finer particle size than the first grinding process is used, and fatal cracks and defects derived from the modified region compared to the first grinding process. Gently grind so that it doesn't trigger. The second grinding process is only a modified region, and the grinding rate is set to a low condition even when compared with the first grinding process, and the fine grinding is performed.

  Then, after the laser modified region is removed, chemical mechanical polishing is finally performed. In chemical mechanical polishing, a chemical solution for modifying a wafer is supplied, and a polishing pad such as a polymer or nonwoven fabric is pressed against the wafer to perform chemical and mechanical polishing.

  If chemical mechanical polishing is performed on the modified region, large crystal grains may be lost in the modified region. In chemical mechanical polishing, a polishing pad such as a nonwoven fabric or polyurethane foam is used. Therefore, when crystal grains dropped off on the surface of the pad, scratches are generated due to the crystal grains constantly dropped during polishing. In such a case, it is necessary to remove the work-affected layer in the grinding process and achieve a mirror finish, and the polished surface is full of scratches.

  For this reason, in the state of being introduced into the chemical mechanical polishing process, the modified layer introduced by the laser in the second grinding process must be completely removed.

  In the present invention, a modified layer is formed by laser light along the cutting line, the back grind tape is attached to the front surface, and the wafer having the expanded tape attached to the back surface is attached to the upper surface of the elastic body. A mode in which the table is rotated so that the pressing member is parallel to the cutting line, and the pressing member is pressed against the wafer and rolled to cleave the cutting line is preferable. .

  According to the above aspect, when the wafer is cleaved, the back grind tape is attached to the front surface, and the wafer on which the modified layer is formed by the laser beam incident from the back surface is applied to the tape after the back surface is ground and polished. Thus, the expanded tape is attached to the back surface.

  The wafer having the back grind tape and the expanded tape attached on both sides is placed on a table having an elastic body attached to the upper surface. Subsequently, a pressing member provided in a mechanism for attaching the tape is positioned in parallel with the cutting line, and is pressed and rolled to break one cutting line.

  After all of one cutting line is cleaved, the wafer is rotated 90 degrees and the other cutting line is cleaved. The cleaved wafer is then moved to a device for peeling the back grind tape, and the back grind tape is peeled off. The wafer from which the back grind tape has been peeled is then moved to the expanding apparatus, and the expanding tape is expanded to separate the chips. As a result, the cleaving is reliably and efficiently performed, and the cleaving can be continuously performed without adversely affecting the subsequent wafer even if the cleaving is continuously performed.

  In the present invention, it is preferable that the pressing member has a radius smaller than the interval between the cutting lines.

  According to the said aspect, the radius of a press member is formed so that it may become a radius smaller than the space | interval of the cutting line formed in the wafer to press. Since the radius is smaller than the interval between the cutting lines, the pressing member does not press the plurality of cutting lines at a time and the stress is not dispersed. As a result, stress can be concentrated and acted on one cutting line, so that cleaving can be performed efficiently and reliably.

  In the present invention, it is preferable that the elastic body has grooves, holes, or irregularities formed at intervals equal to or smaller than the size of the chip formed on the wafer.

  According to the above aspect, the elastic body on which the wafer is placed is subjected to groove processing, hole processing, or uneven processing on the surface. The elastic body is preferably an elastic body having a small compression set and no void so that the initial elastic modulus and the change in the elastic coefficient after several uses are small. By forming grooves, holes, or irregularities on the elastic body at intervals equal to or smaller than the size of the chip formed on the wafer, the wafer can be locally deformed, and cleaving can be performed efficiently and reliably.

  In the present invention, when the back grind tape or the expanded tape is stuck, the sticking roller is rolled and stuck in a direction intersecting with the cutting line formed in a lattice shape. Embodiments are preferred.

  According to the above aspect, when the back grind tape or the expanded tape is attached to the front surface and the back surface of the wafer, the table on which the wafer is placed is rotated about 45 degrees to form a cutting line formed in a lattice shape. On the other hand, after pressing the sticking roller in a direction that is inclined and intersects, the roll is rolled to stick the tape.

  If the cutting line is cleaved by the pressing force of the tape sticking roller, it becomes difficult to apply the tape with high accuracy due to bubbles entering the sticking surface or collapse of the chip direction. By moving the tape adhering roller so as to be inclined with respect to the cutting line, the cleaving can be performed efficiently and without adversely affecting the subsequent processes.

  According to still another aspect of the present invention, laser dicing means for forming a modified region inside the wafer by entering laser light along the cutting line from the back surface of the wafer, and grinding the wafer from the back surface to improve the modification. A semiconductor substrate cutting apparatus comprising: a grinding unit that removes a quality region; a transport unit that transports the wafer from the laser dicing unit to the grinding unit; and a cleaving unit that divides the wafer along a cutting line. The cleaving means includes a table on which an elastic body for placing the wafer is provided, and a pressing member that presses the wafer along a cutting line and is rolled. And

  According to the above aspect, the semiconductor substrate cutting apparatus includes the rotatable table provided with the elastic body having a small compression set and no void. Above the table, there is provided a pressing member for cleaving the wafer by pressing the wafer and rolling the modified layer formed by the laser beam along the cutting line. In the vicinity of the pressing member, a sticking roller that presses the tape to the wafer and rolls to stick the film to the wafer is provided.

  Thereby, it is possible to prevent the modified region formed by the laser beam from remaining in the cross section of the chip. Therefore, it is possible to prevent problems such as cracking of the chip or generation of dust from the cross section of the chip, it is possible to efficiently obtain a stable quality chip, and it is possible to reliably and efficiently perform cleaving.

  In the present invention, it is preferable that the pressing member is formed to have a radius smaller than the interval between the cutting lines.

  According to the said aspect, the radius of a press member is formed so that it may become a radius smaller than the space | interval of the cutting line formed in the wafer to press. As a result, stress can be concentrated and acted on one cutting line, so that cleaving can be performed efficiently and reliably.

  In the present invention, it is preferable that the elastic body has grooves, holes, or irregularities formed at intervals equal to or less than the interval between the cutting lines of the wafer on which the cutting lines are formed in a lattice shape.

  According to the above aspect, the elastic body on which the wafer is placed is subjected to groove processing, hole processing, or uneven processing on the surface. As a result, the wafer can be locally deformed, and the cleaving can be reliably and efficiently performed.

  In the present invention, when the pressing member rolls on the wafer, the table rotates so that the pressing member inclines and intersects with the cutting line formed in a lattice shape. The aspect which adjusts the position of is preferable.

  According to the above aspect, when the back grind tape or the expanded tape is attached to the front surface and the back surface of the wafer, the table on which the wafer is placed is rotated about 45 degrees to form a cutting line formed in a lattice shape. On the other hand, after pressing the sticking roller in a direction that is inclined and intersects, the roll is rolled to stick the tape. Thereby, the trouble at the time of tape sticking is eliminated, the cleaving can be performed efficiently and reliably, and the subsequent process is not adversely affected.

  According to the present invention, cleaving can be performed reliably and efficiently, and stable quality chips can be obtained efficiently.

The figure which shows the external appearance structure of the laser dicing apparatus 1 Conceptual configuration diagram showing configuration of driving means of laser dicing apparatus 1 The top view showing the structure of the drive means of the laser dicing apparatus 1 The figure which shows the external appearance structure of the grinding device 2 Partial enlarged view of grinding device 2 Partial enlarged view of grinding device 2 Schematic diagram of polishing stage of grinding machine 2 It is a figure which shows the detail of the chuck | zipper of the grinding device 2, (a) is a top view, (b) is sectional drawing, (c) is a partial enlarged view. Side view of the tape applicator 3 The perspective view which showed the sticking method of a film The perspective view which showed the state by which the film was stuck on the wafer front surface and the back surface Perspective view showing the state of cleaving Side sectional view showing the state of cleaving Side sectional view showing the state of the pressed elastic body Flow diagram showing a wafer cleaving method according to the present invention The figure explaining the grinding removal process It is a figure explaining the crack progress in a grinding removal process, (a) is a schematic diagram at the time of grinding, (b) is a state on the back surface of wafer W, (c) is a state on the surface of wafer W, (d) is a state of wafer W Cross section The figure explaining the surface state of the wafer W back surface after a grinding removal process Diagram showing conditions for crack growth evaluation Figure showing the evaluation results of crack growth evaluation Diagram showing the fixed state during conventional substrate grinding Diagram showing the fixed state during conventional substrate grinding

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

  The present invention includes a laser dicing device 1, a grinding device 2, a tape applicator 3, a transport device (not shown) for transporting a wafer processed by the laser dicing device 1 to the grinding device 2 or the tape applicator, This is performed by a cutting device composed of an expanding device that separates the wafer cut by the tape applying device 3.

<About device configuration>
(1) Laser Dicing Device 1 FIG. 1 is a diagram showing an overview configuration of the laser dicing device 1. As shown in the figure, the laser dicing apparatus 1 according to the present embodiment mainly includes a wafer moving unit 11, a laser head 40 including a laser optical unit 20 and an observation optical unit 30, a control unit 50, and the like. .

  The wafer moving unit 11 includes an adsorption stage 13 that adsorbs and holds the wafer W, and an XYZθ table 12 that is provided on the main body base 16 of the laser dicing apparatus 1 and that precisely moves the adsorption stage 13 in the XYZθ direction. The wafer moving unit 11 moves the wafer W precisely in the XYZθ direction in the figure.

  The wafer W is placed on the suction stage 13 so that a back grind tape (hereinafter referred to as BG tape) B having an adhesive material is stuck on the surface on which the device is formed by the tape sticking device 3 to be described later, and the back surface faces upward. The

  Note that the wafer W may be placed on the suction stage 13 in a state where a dicing sheet having an adhesive material is attached to one surface and the wafer W is integrated with the frame via the dicing sheet. In this case, it is mounted on the suction stage 13 so that the surface faces upward.

  The laser optical unit 20 includes a laser oscillator 21, a collimating lens 22, a half mirror 23, a condensation lens (condensing lens) 24, a driving unit 25 that minutely moves the laser light parallel to the wafer W, and the like. Laser light oscillated from the laser oscillator 21 is condensed inside the wafer W through an optical system such as a collimating lens 22, a half mirror 23, and a condensation lens 24. The Z direction position of the condensing point is adjusted by the Z direction fine movement of the condensation lens 24 by the Z fine movement means 27 described later.

  The conditions of the laser light are as follows: the light source is a semiconductor laser pumped Nd: YAG laser, the wavelength is 1064 nm, the laser light spot cross-sectional area is 3.14 × 10 −8 cm 2, the oscillation mode is a Q switch pulse, the repetition frequency is 100 kHz, Is 30 ns, the output is 20 μJ / pulse, the laser beam quality is TEM00, and the polarization characteristic is linearly polarized light. The condition of the condensation lens 24 is that the magnification is 50 times, N.I. A. Is 0.55, and the transmittance with respect to the wavelength of the laser beam is 60%.

  The observation optical unit 30 includes an observation light source 31, a collimator lens 32, a half mirror 33, a condensation lens 34, a CCD camera 35 as an observation means, an image processing unit 38, a television monitor 36, and the like.

  In the observation optical unit 30, the illumination light emitted from the observation light source 31 irradiates the surface of the wafer W through an optical system such as a collimator lens 32, a half mirror 33, and a condensation lens 24. Reflected light from the surface of the wafer W enters the CCD camera 35 as observation means via the condensation lens 24, the half mirrors 23 and 33, and the condensation lens 34, and a surface image of the wafer W is captured.

  This imaged data is input to the image processing unit 38, used for alignment of the wafer W, and is displayed on the television monitor 36 through the control unit 50.

  The control unit 50 includes a CPU, a memory, an input / output circuit unit, and the like, and controls the operation of each unit of the laser dicing apparatus 1.

  The laser dicing apparatus 1 includes a wafer cassette elevator (not shown), wafer transfer means, an operation plate, an indicator lamp, and the like.

  The wafer cassette elevator moves a cassette in which wafers are stored up and down to position it at a transfer position. The transfer means transfers the wafer between the cassette and the suction stage 13.

  On the operation plate, switches for operating each part of the dicing device 10 and a display device are attached. The indicator lamp displays an operation status such as processing end, emergency stop, etc. during processing of the dicing apparatus 10.

  FIG. 2 is a conceptual diagram illustrating details of the driving means 25. The driving means 25 includes a lens frame 26 that holds the condensation lens 24, a Z fine movement means 27 that is attached to the upper surface of the lens frame 26 and moves the lens frame 26 in the Z direction in the drawing, and a holding frame 28 that holds the Z fine movement means 27. , PZ1, PZ2, etc., which are linear fine movement means for minutely moving the holding frame 28 in parallel with the wafer W.

  The Z fine movement means 27 uses a piezoelectric element that expands and contracts when a voltage is applied. Due to the expansion and contraction of the piezoelectric element, the condensation lens 24 is finely fed in the Z direction, and the position of the laser beam condensing point in the Z direction is precisely positioned.

  The holding frame 28 is supported by two pairs of parallel springs composed of four piano wires (not shown), is movable in the XY directions, and is restricted from moving in the Z direction. Note that the support method of the holding frame 28 is not limited to this. For example, the holding frame 28 may be sandwiched vertically by a plurality of balls to restrain the movement in the Z direction and support the movement in the XY directions.

  For the linear fine movement means PZ1 and PZ2, a piezoelectric element is used similarly to the Z fine movement means 27, one end is fixed to the case main body of the laser head 40, and the other end is in contact with the side surface of the holding frame 28.

  FIG. 3 is a plan view of the driving means 25. As shown in FIG. 3, two linear fine movement means PZ 1 and PZ 2 are arranged in the X direction, one end of which is fixed to the case main body of the laser head 40 and the other end is in contact with the side surface of the holding frame 28. . Therefore, by controlling the applied voltage, the condensation lens 24 can be finely fed back and forth in the X direction, and the laser beam can be finely fed back and forth in the X direction or oscillated.

  A piezoelectric element may be used for one of the linear fine movement means PZ1 and PZ2, and the other may be an elastic member such as a spring material. Also, three linear fine movement means may be arranged on the circumference.

  Laser light L is emitted from the laser oscillator 21, and the laser light L is irradiated inside the wafer W via an optical system such as a collimating lens 22, a half mirror 23, a condensation lens 24, and the like. The position of the condensing point of the irradiated laser beam L in the Z direction is accurately adjusted to a predetermined position inside the wafer by adjusting the position of the wafer W in the Z direction by the XYZθ table 12 and controlling the position of the condensation lens 24 by the Z fine movement means 27. Is set.

  In this state, the XYZθ table 12 is processed and fed in the X direction, which is the dicing direction, and the condensation lens 24 is reciprocally moved by the linear fine movement means PZ1 and PZ2 provided in the laser head 40. The modified region K is vibrated in the X direction or in an arbitrary XY direction in parallel, and the condensing point of the laser beam L is minutely oscillated inside the wafer. Thereby, one line of the modified region K by multiphoton absorption is formed inside the wafer W along the cutting line of the wafer W.

  In addition, you may add the vibration of the Z direction by the Z fine movement means 27 as needed. In addition, the laser beam L is repeatedly reciprocated in the X direction, which is the processing direction, and the wafer W is sent in the X direction, so that the laser beam L is repeatedly irradiated in a returning state like a perforation. Also good.

  When one line of the reformed region is formed along the cutting line, the XYZθ table 12 is indexed and fed by one pitch in the Y direction, and the reformed region is similarly formed on the next line.

  When the modified region is formed along all the cutting lines parallel to the X direction, the XYZθ table 12 is rotated by 90 °, and the modified region is formed in the same manner for all the lines orthogonal to the previous line.

(2) About Grinding Device 2 FIG. 4 is a perspective view showing a general configuration of the grinding device 2. The main body 112 of the grinding apparatus 2 is provided with an alignment stage 116, a rough grinding stage 118, a fine grinding stage 120, a polishing stage 122, a polishing cloth cleaning stage 123, a polishing cloth dressing stage 127, and a wafer cleaning stage 124.

  As shown in FIG. 5, the rough grinding stage 118, the fine grinding stage 120, and the polishing stage 122 are partitioned by a partition plate 125 (not shown in FIG. 4), and the processing liquid used in each stage 118, 120, 122 is adjacent. It is prevented from splashing on the stage.

  As shown in FIG. 5, the partition plate 125 is fixed to the index table 134 and is formed in a cross shape so as to partition the four chucks 132, 136, 138, 140 installed on the index table 134. .

  The rough grinding stage 118 is a stage for performing rough grinding, and is surrounded by the side surface of the main body 112, the top plate 128, and the partition plate 125 as shown in FIG. The fine grinding stage 120 is a stage that performs fine grinding, and is surrounded by the side surface of the main body 112, the top plate 129, and the partition plate 125, similarly to the rough grinding stage 118. Brushes (not shown) are disposed on the upper surface and side surfaces of the partition plate 125 to isolate the rough grinding stage 118 and the fine grinding stage 120 from the outside. The top plates 128 and 129 have through holes 128A and 129A through which the heads of the respective stages are inserted.

  The polishing stage 122 performs chemical mechanical polishing, and is covered with a casing 126 having a top plate 126A as shown in FIG. 5 in order to isolate it from other stages. The top plate 126A has a through hole 126C through which the head of each stage is inserted.

  As shown in FIG. 6, a brush 126B is attached to the side surface of the casing 126 through which the partition plate 125 passes. When the chuck 140 is located at the processing position, the brush 126B is attached to the upper surface 125A of the partition plate 125 and the brush 126B. The side 125B is contacted. As a result, when the chuck 140 is located at the processing position, it is held in a substantially airtight state by the casing 126, the partition plate 125, and the brush 126B.

  Since the polishing stage 122 performs chemical mechanical polishing, the polishing liquid contains a chemical abrasive. When a grinding process liquid is mixed in such a polishing process liquid, the concentration of the chemical abrasive is lowered, resulting in a problem that the processing time becomes longer. By maintaining the polishing stage 122 in a substantially confidential state, it is possible to prevent the grinding fluid and processing waste used in the precision grinding stage 120 from entering the polishing stage 122, and the polishing fluid used in the polishing stage 122. Can be prevented from scattering from the polishing stage 122. Therefore, it is possible to prevent a processing failure caused by mixing of both processing liquids.

  FIG. 7 is a structural diagram of the polishing stage 122. In the polishing stage 122, polishing is performed by the polishing cloth 156 and the slurry supplied from the polishing cloth 156, and the work-affected layer generated on the back surface of the wafer W is removed by rough polishing and fine polishing. The work-affected layer is a general term for streaks and work strains (crystals are altered) generated by grinding.

  The polishing cloth 156 of the polishing stage 122 is attached to the polishing head 161 connected to the output shaft 160 of the motor 158. Guide blocks 162 and 162 constituting a linear guide are provided on the side surface of the motor 158, and the guide blocks 162 and 162 are engaged with a guide rail 166 provided on the side surface of the support plate 164 so as to be movable up and down. Has been. Therefore, the polishing pad 156 is attached to the support plate 164 together with the motor 158 so as to be movable up and down.

  The support plate 164 is provided at the tip of the arm 168 arranged horizontally. A base end portion of the arm 168 is connected to an output shaft 174 of a motor 172 disposed in the casing 170. Therefore, when the motor 172 is driven, the arm 168 can rotate around the output shaft 174. As a result, the polishing cloth 56 is polished (see the solid line in FIG. 3), the polishing cloth cleaning stage 123 is in the polishing cloth cleaning position (see the two-dot chain line in FIG. 3), and the polishing cloth dressing stage 127 is in the dress position. Can be moved within. When the polishing cloth 156 is moved to the polishing cloth cleaning position, the polishing cloth cleaning stage 123 cleans the surface of the polishing cloth 156 and removes polishing dust and the like adhering to the surface. Examples of the polishing cloth 156 include polyurethane foam and polishing cloth. The polishing cloth cleaning stage 123 is provided with a removing member such as a brush for removing polishing debris. This removal member is rotationally driven when the polishing cloth 156 is cleaned, and the polishing cloth 156 is also rotationally driven by the motor 158. The abrasive cloth dressing stage 127 is made of the same material as the abrasive cloth 156, for example, polyurethane foam.

  Guide blocks 176 and 176 constituting linear motion guides are provided on the side surface of the casing 170, and the guide blocks 176 and 176 are movable up and down on a guide rail 180 provided on a side surface of the housing 178 for the screw feeder. Is engaged. A nut member 179 protrudes from the side surface of the casing 170. The nut member 179 is screwed into a screw rod 181 of a screw feeding device disposed in the housing 178 through an opening (not shown) formed in the housing 178. The output shaft 184 of the motor 182 is connected to the upper end of the screw rod 181. Therefore, when the motor 182 is driven and the screw rod 181 is rotated, the casing 70 is moved up and down by the feeding action of the screw feeding device and the straight movement action of the guide block 176 and the guide rail 180. As a result, the polishing pad 156 is greatly moved in the vertical direction, and the interval between the polishing head 161 and the wafer W is set to a predetermined interval.

  The piston 188 of the air cylinder device 186 is connected to the upper surface of the motor 158 through the through hole 169 of the arm 168. The air cylinder device 186 is connected to a regulator 190 that controls the internal pressure P of the cylinder. Therefore, when the internal pressure P is controlled by the regulator 190, the pressing force (pressure contact force) of the polishing pad 156 against the wafer W can be controlled.

  In the present embodiment, the polishing cloth 156 is applied as the polishing body. However, the present invention is not limited to this. For example, if the work-affected layer can be removed, for example, grinding wheel or abrasive gel electrophoresis may be performed. You may apply. When applying a grinding wheel or electrophoresis of abrasive grains, it is preferable to perform quantitative polishing.

  Returning to the description of FIG. The alignment stage 116 is a stage for aligning the wafer W transferred from the laser dicing apparatus 1 by a transfer apparatus (not shown) at a predetermined position. The wafer W aligned by the alignment stage 116 is sucked and held by a transfer robot (not shown), then transferred toward the empty chuck 132, and sucked and held on the suction surface of the chuck 132.

  The chuck 132 is installed on the index table 134, and chucks 136, 138, and 140 having the same function are installed on the circumference around the rotation shaft 135 of the index table 134 at an interval of 90 degrees. . A spindle (not shown) of a motor (not shown) is connected to the rotating shaft 135.

  The chuck 136 is positioned on the rough grinding stage 118 in FIG. 4, and the attracted wafer W is roughly ground here. The chuck 138 is positioned on the precision grinding stage 120 in FIG. 4, and the sucked wafer W is finish-ground (fine grinding, spark out) here. The chuck 140 is positioned on the polishing stage 122 in FIG. 4, and the adsorbed wafer W is polished here, and the work-affected layer generated by grinding and the variation in the thickness of the wafer W are removed.

  Here, the chucks 132, 136, 138, and 140 will be described. Since the chucks 136, 138, and 140 have the same configuration as the chuck 132, the chuck 132 will be described, and the description of the chucks 136, 138, and 140 will be omitted.

  8A and 8B are diagrams showing details of the chuck 132, wherein FIG. 8A is a plan view of the chuck 132, FIG. 8B is a cross-sectional view taken along line AA ′ in FIG. 8A, and FIG. FIG.

  The chuck 132 is configured by fitting a mounting table 132a formed of a porous material (for example, porous ceramics) into a chuck body 132b formed of a dense body. A suction hole 132c is formed on the lower side of the chuck body 132b where the mounting table 132a is fitted for vacuum suction. Note that the chuck 132 is preferably formed of a material having low thermal conductivity.

  As shown in FIG. 8C, the wafer W is placed on the mounting table 132a via the BG tape B. As shown in FIG. 8C, the mounting table 132a is formed so that a part of the outer periphery of the wafer W protrudes from the mounting table 132a when the wafer W is mounted on the mounting table 132a. Is about 1.5 mm. The wafer W used in the present embodiment has a diameter of about 12 inches and a thickness t of about 775 μm.

  As shown in FIGS. 8A and 8B, the suction hole 132c is disposed so as to cover substantially the entire area of the mounting table 132a. A fluid coupling (not shown) is connected to the suction hole 132c, and a suction pump (not shown) connected to the fluid coupling sucks air. Therefore, substantially the entire surface of the wafer W is firmly vacuum-sucked on the surface of the mounting table 132a. Thus, the wafer W and the mounting table 132a can be brought into close contact with each other without causing positional displacement.

  As shown in FIG. 7, the chucks 132, 136, 138, 140 are respectively connected to the spindle 194 and the motor 192 on their lower surfaces, and are rotated by the driving force of these motors 192. The motor 192 is supported on the index table 134 via a support member 193. Thus, every time the chucks 132, 136, 138, 140 are moved by the motor 137, the spindle 194 is separated from the chucks 132, 136, 138, 140, or the chucks 132, 136 are attached to the spindle 194 installed at the next movement position. 138 and 140 can be saved.

  A piston 119 of the cylinder device 117 is connected to the lower part of the motor 192. When the piston 119 is extended, the piston 119 is inserted into and connected to a recess (not shown) formed in the lower part of the chucks 132, 136, 138, and 140. The chucks 132, 136, 138, and 140 are moved upward from the index table 134 by the continuous extending operation of the piston 119, and are positioned at the grinding positions by the grindstones 146 and 154.

  The control unit 100 includes a CPU, a memory, an input / output circuit unit, and the like, and controls the operation of each unit of the grinding apparatus 2.

  The thickness of the wafer W attracted and held by the chuck 132 is measured by a pair of measurement gauges (not shown) connected to the control unit 100. Each of these measurement gauges has a contact, and the contact is in contact with the upper surface (back surface) of the wafer W, and the other contact is in contact with the upper surface of the chuck 132. These measurement gauges can detect the thickness of the wafer W as a difference between in-process gauge readings with the upper surface of the chuck 132 as a reference point. In addition, you may implement the thickness measurement by a measurement gauge in-line. The method for measuring the thickness of the wafer W is not limited to this.

  The index table 134 is rotated 90 degrees in the direction of arrow R in FIG. 4 by the control unit 100, whereby the wafer W whose thickness has been measured is positioned on the rough grinding stage 118, and the wafer is moved by the cup-type grindstone 146 of the rough grinding stage 118. The back surface of W is roughly ground. As shown in FIG. 4, the cup-type grindstone 146 is connected to an output shaft (not shown) of the motor 148 and is attached to the grindstone feeder 152 via a support casing 150 of the motor 148. The grindstone feeder 152 moves the cup-type grindstone 146 up and down together with the motor 148, and the cup-type grindstone 146 is pressed against the back surface of the wafer W by this downward movement. Thereby, the rough grinding of the back surface of the wafer W is performed. The control unit 100 sets the downward movement amount of the cup-type grindstone 146 and controls the motor 148. The downward movement amount of the cup-type grindstone 46, that is, the grinding amount by the cup-type grindstone 146, is set based on the reference position of the cup-type grindstone 146 registered in advance and the thickness of the wafer W detected by the measurement gauge. Is done. Further, the control unit 100 controls the rotational speed of the cup-type grindstone 146 by controlling the rotational speed of the motor 148.

  The thickness of the wafer W whose back surface has been coarsely ground by the rough grinding stage 118 is measured by a measurement gauge (not shown) connected to the control unit 100 after the cup-type grindstone 146 moves away from the wafer W. The index table 134 is rotated 90 degrees in the direction of arrow R in FIG. 4 by the control unit 100, so that the wafer W whose thickness has been measured is positioned on the fine grinding stage 120, and is finely adjusted by the cup-type grindstone 154 of the fine grinding stage 120. Grinded and sparked out. Since the structure of the fine grinding stage 120 is the same as that of the rough grinding stage 118, the description thereof is omitted here. The amount of grinding by the cup-type grindstone 154 is set by the control unit 100, and the processing movement amount and the rotation speed of the cup-type grindstone 154 are controlled by the control unit 100.

  The thickness of the wafer W whose back surface has been precisely ground by the precision grinding stage 120 is measured by a measurement gauge (not shown) connected to the control unit 100 after the cup-type grindstone 154 moves away from the wafer W. When the index table 134 is rotated 90 degrees in the direction of arrow R in FIG. 4 by the controller 100, the wafer W whose thickness has been measured is positioned on the polishing stage 122, and chemical mechanical polishing is performed by the polishing cloth 156 of the polishing stage 122. The back surface of the wafer W is mirror-finished. The vertical movement distance of the polishing pad 156 is set by the control unit 100, and the position of the polishing pad 156 is controlled by controlling the motor 182 by the control unit 100. Further, the control unit 100 controls the rotation speed of the motor 158, that is, the rotation speed of the polishing pad 156.

  The wafer W polished by the polishing stage 122 is rotated by the control unit 100 and the arm 168 is rotated, and after the polishing cloth 156 is retracted from the upper position of the wafer W, a hand (not shown) of a robot (not shown). Is sucked and held and transferred to the wafer cleaning stage 124. As the wafer cleaning stage 124, a stage having a rinse cleaning function and a spin drying function is applied. Since the damaged layer is removed, the polished wafer W is not easily damaged. Therefore, the wafer W is not damaged during transfer by the robot and cleaning in the wafer cleaning stage 124.

  The wafer W that has been cleaned and dried by the wafer cleaning stage 124 is sucked and held by a hand (not shown) of a robot (not shown) and stored in a predetermined shelf of a cassette (not shown).

(3) About Tape Applicator 3 FIG. 9 is a side view showing the configuration of the tape applicator 3. The BG tape B or the expanded tape E is attached to the wafer W by the tape applicator 3. Further, the wafer W ground and polished by the grinding device 2 is cleaved by the tape applying device 3.

  The tape applicator 3 includes a table 211 that is rotatably provided by a driving device (not shown). An elastic body 212 on which the wafer W is placed is attached to the upper surface of the table 211.

  A supply reel 213 and a sticking roller 214 are provided above the table 211 so that the BG tape B or the expanded tape E fed out from the supply reel 213 is wound around the take-up reel 217 via the guide rollers 215 and 216. It has become.

  A pressing member 218 that cleaves the wafer W is provided in the vicinity of the sticking roller 214 (for example, above the outer periphery of the table 211).

  The bonding of the BG tape B is performed by the bonding roller 214 with the wafer W placed on the elastic body 212 on the table 211.

  The sticking roller 214 is formed of an elastic body that is softer than the elastic body 212. The BG tape B or the expanded tape E on the wafer W has, for example, an ultraviolet curable adhesive on the sticking surface, and rolls laterally while pressing the sticking roller 214 downward as shown in FIG. By adhering, the wafer W is attached. After the BG tape B or the expanded tape E is attached to the wafer W, unnecessary portions are cut by a cutter (not shown), and the remaining BG tape B or the expanded tape E is wound on the take-up reel 217. It is done.

  When affixing the BG tape B or the expanded tape E, a cutting line S as a cutting line for dividing the chip C is arranged in parallel to the sticking roller 214 as shown in FIG. By rotating the table 211 by 45 degrees, the wafer W is arranged so that the cutting line S intersects with the sticking roller 214 as shown in FIG. 10B. The wafer W is mounted on the frame F via the expanded tape E as shown in FIG.

  This prevents the wafer W from being cut along the cutting line S by the pressure of the sticking roller 214 while the BG tape B or the expanded tape E is stuck to the wafer W. If the wafer W is cleaved while the BG tape B or the expanded tape E is attached, bubbles may enter between the wafer W and the BG tape B or the expanded tape E, and the direction of the chip C may be shifted. Therefore, it becomes difficult to attach the BG tape B or the expanded tape E to the entire wafer W with high accuracy.

  The pressure applied to the sticking roller 214 is dispersed by inclining and intersecting the cutting line S formed in a lattice shape, and these problems are avoided. In addition, since the BG tape B or the expanded tape E is attached with high accuracy, it is easy to peel off by peeling in the same direction as that when sticking, and the problem that the chip C is stuck and lifted is also caused. It becomes possible to prevent.

  In the cleaving of the wafer W, an elastic body 212 is provided on the upper surface of the wafer W so that the pressing member 218 is parallel to one of the cutting lines S which is a cutting line formed in a lattice shape as shown in FIG. Placed on the table 211. In this state, the pressing member 218 is pressed against the wafer W and rolled, and the wafer W is cleaved along one cutting line S. After the cutting of one cutting line S, the table 211 on which the wafer W is placed is rotated 90 degrees by a driving means (not shown) so that the other cutting line S and the pressing member 218 are arranged in parallel. The wafer W is cleaved along the cutting line S.

  The elastic body 212 attached to the upper surface of the table 211 is an elastic body having a small compression set and no gap, and has a lattice shape or an interval less than the size of the chip C formed on the wafer W as shown in FIG. Grooves 212a, 212a,... Arranged in parallel are formed. As a material of the elastic body 212, for example, SBR (styrene butadiene rubber), NBR (nitrile butadiene rubber), or the like can be suitably used. The groove 212a may have a hole shape or an uneven shape.

  For example, when a sponge-like elastic body 212B shown in FIG. 14A in which a large number of small gaps are formed is used for cleaving the wafer W, the permanent compression is caused by the gap becoming smaller or the gap becoming flat. Distortion occurs. For this reason, when the elastic body 212B is repeatedly used, the elastic modulus gradually changes due to deformation, and stable cleaving cannot be performed.

  Further, as shown in FIG. 14B, in the elastic body 212C having no grooves, holes, irregularities, etc., when a part of the elastic body is pushed in, the volume is constant, so that the portion around the pushed in is raised. It will be. In this case, even if an attempt is made to crush by pressing locally to sink the wafer, the stress is dispersed and it becomes difficult to cleave efficiently.

  On the other hand, as shown in FIG. 14 (c), the elastic body 212 has a room for lateral deformation due to the groove 212a with respect to pressing from above, so that a uniform deformation occurs, and the cutting line for which cutting is desired. Stress concentrates on S, and cleaving can be performed efficiently and reliably.

  As shown in FIG. 13, the pressing member 218 is formed so that the radius r is smaller than the interval l of the cutting line S in which the modified region K is formed. Further, the pressing member 218 is formed of a material that is equivalent to or harder than the sticking roller 214 shown in FIG.

  When the radius r is smaller than the interval l, the pressing member 218 does not press the other cutting line S when pressing one cutting line S. As a result, stress concentrates on the cutting line S that is desired to be cleaved, so that cleaving can be performed efficiently and reliably.

  In the cleaving of the wafer W, since the BG tape B or the expanded tape E is stuck to each surface of the wafer W, when cleaving one cutting line S and then cleaving the adjacent cutting line S, the BG tape B Alternatively, the chip interval is not greatly expanded in the cutting line S that is already cleaved by the position being restricted by the expanded tape E. As a result, local stress of the pressing member 218 is not dispersed due to not only the vertical deformation caused by the elastic body 212 but also the horizontal deformation caused by the gap between the chips C being greatly widened, and the stress is concentrated. Can be cleaved efficiently and reliably.

  Further, by sticking the BG tape B or the expanded tape E2 to the front surface and the back surface, debris generated when the wafer W is cleaved does not adhere to the elastic body 212, and the next wafer W is bonded to the elastic body. Even if it is placed on 212, there is no adverse effect caused by debris.

(4) About Expanding Device Next, an expanding device (not shown) will be described. As the expanding apparatus, a conventional normal expanding apparatus can be used. For example, an expanding apparatus having the following configuration disclosed in Japanese Patent Application Laid-Open No. 2007-173587 can be used.

  That is, the peripheral edge of the expanded tape E is fixed to the frame-shaped frame F. A ring member is in contact with the lower surface of the inner portion of the peripheral portion of the expanded tape E. The outer peripheral edge of the upper surface of this ring member is smoothly rounded. A force is applied to the frame F in the downward direction, and the frame F is pushed down. As a result, the dicing tape is expanded, and the interval between the chips is widened. At this time, since the outer peripheral edge of the upper surface of the ring member is smoothly rounded, the expanded tape E is expanded smoothly.

  As a mechanism for pushing down the frame F, various known linear motion devices can be employed. For example, a linear motion device composed of a cylinder member (by hydraulic pressure, pneumatic pressure, etc.), a motor and a screw (a combination of a male screw as a shaft and a female screw as a bearing) can be employed.

<Semiconductor substrate cutting method>
Next, a method for cutting the semiconductor substrate will be described. FIG. 15 is a flowchart showing a process flow of a semiconductor substrate cutting method.

(1) Laser modification process (step S1)
The BG tape B is attached to the wafer W on the surface side on which a circuit pattern or the like is formed (step S1).

  The BG tape B is attached to the wafer W by the tape applicator 3. When sticking the BG tape B, as shown in FIG. 5A, a wafer W in which a cutting line S as a cutting line for dividing the chip C is arranged in parallel to the sticking roller 214, By rotating the table 11 by 45 degrees, as shown in FIG. 10B, the cutting line S is disposed so as to intersect with the sticking roller 214 at an inclination. Thereby, the wafer W is not cleaved along the cutting line S by the pressure of the sticking roller 214 while the BG tape B is stuck to the wafer W.

(2) Laser modification process (step S2)
The wafer W with the BG tape B attached to the front surface is placed on the suction stage 13 of the laser dicing apparatus 1 so that the back surface faces upward. The following processing is performed by the laser dicing apparatus 1 and controlled by the control unit 50.

  When the laser light L is emitted from the laser oscillator 21, the laser light L is irradiated to the inside of the wafer W via an optical system such as the collimating lens 22, the half mirror 23, and the condensation lens 24, and is modified to the inside of the wafer W. A quality region K is formed.

  In the present embodiment, since the finally generated chip has a thickness of about 50 μm, the laser beam is irradiated from the surface of the wafer W to a depth of about 60 μm to about 80 μm. In order to efficiently break the surface (device surface) of the wafer W, the laser modified region is formed at a relatively deep position near the reference surface, which is a surface located on the back surface side by the thickness of the chip C from the surface of the wafer W. This is because it needs to be formed.

  The controller 50 scans the surface of the wafer W with the pulsed laser beam L for processing in parallel, and forms a plurality of discontinuous modified regions K. Inside the reformed region K, microvoids (hereinafter referred to as cracks) are formed. Hereinafter, a region in which a plurality of discontinuous modified regions K,... Are formed side by side is referred to as a modified layer.

  When the modified layer is formed along all the cutting lines S shown in FIG. 10, the process of step S2 is ended.

(3) Grinding removal process (step S3)
When the modified region K is formed along the cutting line S by the laser modification process (step S2), the wafer W is transferred from the laser dicing apparatus 1 to the grinding apparatus 2 by a transfer device (not shown). The following processing is performed by the grinding apparatus 2 and controlled by the control unit 100.

  The transferred wafer W is placed on a chuck 132 (eg, chucks 136, 148, 140 are also acceptable) with the back surface of the wafer W on the upper side, that is, the BG tape B attached to the front surface of the wafer W on the lower side. The entire surface is vacuum-adsorbed to the chuck 132.

  The index table 134 is rotated around the rotation shaft 135 to bring the chuck 132 into the rough grinding stage 118, and the wafer W is roughly ground.

  Rough grinding is performed by rotating the chuck 132 and rotating the cup-type grindstone 146. In the present embodiment, for example, Vitrified # 325 manufactured by Tokyo Seimitsu is used as the cup-type grindstone 146, and the rotational speed of the cup-type grindstone 146 is approximately 3000 rpm.

  After the rough grinding, the index table 134 is rotated around the rotation shaft 135 to bring the chuck 132 into the precision grinding stage 120, the chuck 132 is rotated, and the cup-type grindstone 154 is rotated to precisely grind the wafer W. In the present embodiment, for example, resin # 2000 manufactured by Tokyo Seimitsu is used as the cup-type grindstone 154, and the rotational speed of the cup-type grindstone 154 is approximately 2400 rpm.

  In the present embodiment, as shown in FIG. 16, rough grinding and fine grinding are combined to perform grinding to the target surface, that is, from the surface of the wafer W to a depth of approximately 50 μm. In this embodiment, approximately 700 μm is ground by rough polishing, and approximately 30 to 40 μm is ground by fine grinding. However, it is not strictly determined, and the times of rough grinding and fine grinding are substantially the same. The grinding amount may be determined so that

  Therefore, as shown in FIG. 16, the modified layer is removed by the grinding process, and the modified region K by the laser beam does not remain in the cross section of the chip C which is the final product. Therefore, it can be avoided that the modified layer is crushed from the cross section of the chip, the chip C is broken from the crushed portion, and dust is generated from the crushed portion.

  In the present embodiment, the grinding and removing step includes a crack propagation step in which the crack in the modified layer is propagated in the thickness direction of the wafer W. FIGS. 17A and 17B are diagrams for explaining a mechanism in which cracks progress, wherein FIG. 17A is a schematic diagram during grinding, FIG. 17B is a state of the back surface of the wafer W, FIG. 17C is a state of the surface of the wafer W, and FIG. It is sectional drawing of the wafer W at the time of grinding.

  By grinding, the ground surface shown in FIG. 17A, that is, the back surface of the wafer W is expanded by grinding heat as shown in FIG. On the other hand, the surface opposite to the grinding surface, that is, the surface of the wafer W, is almost entirely adsorbed by a vacuum chuck under reduced pressure as shown in FIG. 17 (c), so that the positional deviation due to thermal expansion does not occur. Is physically constrained to displacement

  That is, as shown in FIG. 17D, the back surface (grinding surface) of the wafer W tends to spread in the outer peripheral direction due to thermal expansion (displacement due to thermal expansion) when it is disk-shaped (displacement due to thermal expansion). The suction surface is constrained so that each point in the wafer surface to be spread is not physically displaced. Therefore, distortion occurs in the wafer, and cracks propagate in the thickness direction of the wafer W due to the internal distortion. This internal strain works equally between the portion that expands due to thermal expansion and each point in the wafer surface that is physically constrained. Crack propagation due to internal strain is most efficient at the initial stage of grinding, ie, during rough grinding, where the amount of grinding is the largest and the frictional force is increased, that is, the frictional heat is increased.

  The laser modified region is formed at a relatively deep position close to the thickness of the chip. Therefore, the distance from the ground surface to the laser modified layer is relatively long at the beginning of grinding, but the target surface from the modified layer is relatively close to the extent of crack propagation. Therefore, in order to propagate cracks, it is preferable to promote thermal expansion of the wafer W by grinding heat at the initial stage of rough grinding.

  Even if grinding is performed under conditions for thermally expanding the wafer W, that is, conditions for generating a large amount of frictional heat (for example, reducing the amount of grinding fluid), the shearing stress of grinding is immediately exerted on the modified layer. Not a thing. In the present embodiment, the crack does not propagate due to the shear stress due to grinding, but the thermal expansion due to the grinding heat is the dominant element of the crack propagation.

  When cracks are propagated due to internal strain, cracks can be propagated uniformly at each point in the wafer W plane, regardless of the rigidity variation in the wafer W plane. . Therefore, it is possible to prevent stress from being concentrated on a portion having low rigidity due to the presence of defects in the surface of the wafer W as in the case of applying artificial stress.

  In addition, when an external force is applied artificially, stress concentrates on a weak portion of the material, so that it is difficult to control the cracks to uniformly and slowly progress, and the wafer is completely cleaved. On the other hand, in the case of the progress of the crack due to the internal strain in the present embodiment, it is possible to cause the crack to be advanced slightly because it is the internal strain due to the degree of thermal expansion. That is, a crack can be propagated between the target surface and the surface of the wafer W. Therefore, it becomes possible to divide efficiently in the wafer cleaving process (step S6) described later.

  The internal strain due to thermal expansion of the wafer W is distinguished from so-called thermal stress caused by a temperature difference. Although the thermal stress is generated in proportion to the temperature gradient, in the present embodiment, the generated heat escapes to the chucks 132, 136, 138, and 140, so that no thermal stress is generated.

(4) Chemical mechanical polishing process (step S4)
This process is performed by the grinding apparatus 2 and controlled by the control unit 100.

  After the fine grinding, the index table 134 is rotated around the rotation shaft 135, the chuck 132 is carried into the polishing stage 122, chemical mechanical polishing is performed by the polishing cloth 156 of the polishing stage 122, and in the grinding removal step (step S3). The work-affected layer formed on the back surface of the wafer W is removed, and the back surface of the wafer W is mirror-finished.

  In the present embodiment, a polyurethane-impregnated non-woven cloth (for example, TS200L manufactured by Tokyo Seimitsu) is used as the polishing cloth 156, colloidal silica is used as the slurry, and the rotational speed of the polishing cloth 156 is approximately 300 rpm.

  As a result of the grinding removal process (step S3), the back surface of the wafer W has a large number of irregularities as shown in FIG. In the case of polishing by chemical etching, the surface shape is maintained as it is, so that there is a possibility that cracks are generated from the recesses, and the surface is not mirror-finished. On the other hand, in this embodiment, since chemical mechanical polishing is used, the processing distortion caused by the processing is removed, and the surface irregularities are removed to make a mirror surface.

  That is, in order to improve the quality of the final chip C, two processes, a grinding removal process using a grindstone and a chemical mechanical polishing process using free abrasive grains containing a chemical liquid using a polishing cloth, are indispensable. .

(5) Expanding tape application process (step S5)
The expanded tape E is attached to the back surface of the wafer W on which the chemical mechanical polishing step (step S4) has been performed. Expandable tape is a type of elastic tape that can be stretched.

  The expansion tape E is attached to the wafer W by the tape application device 3 in the same manner as the attachment of the BG tape B in step S1. When sticking the expanded tape E, the cutting line S is arranged in parallel to the sticking roller 214 as shown in FIG. As shown in FIG. 10 (b), the wafer W being arranged is arranged so that the cutting line S is inclined and intersects with the sticking roller 214.

  Thereby, the wafer W is not cleaved along the cutting line S by the pressure of the sticking roller 14 while the expand tape E is stuck to the wafer W.

(6) Wafer cleaving process (step S6)
The wafer W is divided into individual chips C by pressing the pressing member 218 against the wafer W to which the expanded tape E is attached and cleaving the wafer W along the cutting line S.

  In the cleaving of the wafer W, an elastic body 212 is provided on the upper surface of the wafer W so that the pressing member 218 is parallel to one of the cutting lines S which is a cutting line formed in a lattice shape as shown in FIG. Placed on the table 211. In this state, the pressing member 218 is pressed against the wafer W and rolled, and the wafer W is cleaved along one cutting line S. After the cutting of one cutting line S, the table 211 on which the wafer W is placed is rotated 90 degrees by a driving means (not shown) so that the other cutting line S and the pressing member 218 are arranged in parallel. The wafer W is cleaved along the cutting line S.

  The elastic body 212 attached to the upper surface of the table 211 is an elastic body having a small compression set and no gap, and has a lattice shape or an interval less than the size of the chip C formed on the wafer W as shown in FIG. Grooves 212a, 212a,... Arranged in parallel are formed. Accordingly, as shown in FIG. 14C, the elastic body 212 has a room for lateral deformation due to the groove 212a with respect to the pressure from above, so that the uniform deformation occurs and the cutting line S that is desired to be cut off. The stress concentrates on the surface and can be cleaved efficiently and reliably.

  As shown in FIG. 13, the pressing member 218 is formed so that the radius r is smaller than the interval l of the cutting line S in which the modified region K is formed, so that the pressing member 18 has one cutting line S. When pressing, the other cutting line S is not pressed. As a result, stress concentrates on the cutting line S that is desired to be cleaved, so that cleaving can be performed efficiently and reliably.

  In cleaving the wafer W, the BG tape B and the expanded tape E are attached to the front and back surfaces. Therefore, when cleaving one cutting line S and then cleaving the adjacent cutting line S, the BG tape B and the expanding tape The chip interval is not greatly expanded in the cutting line S that has already been cleaved because the position is restricted by E. As a result, local stress of the pressing member 218 is not dispersed due to not only the vertical deformation caused by the elastic body 212 but also the horizontal deformation caused by the gap between the chips C being greatly widened, and the stress is concentrated. Can be cleaved efficiently and reliably.

  Further, by attaching the BG tape B and the expanded tape E to the front surface and the back surface, debris generated when the wafer W is cleaved do not adhere to the elastic body 212, and the next wafer W is bonded to the elastic body. Even if it is placed on 212, there is no adverse effect caused by debris.

(7) Wafer separation step (step S7)
The BG tape B is peeled off from the cleaved wafer W, the expanded tape E is expanded, and the interval between the chips C is widened.

  The BG tape B is peeled off by various methods such as irradiating the BG tape B with ultraviolet rays or heating it with a film peeling device (not shown). At the time of peeling, the BG tape B is peeled off in a direction intersecting with the cutting line S in an inclined manner, similarly to the sticking of the surface protecting film in Step S2 and the sticking of the expanded film in Step 5. Thereby, it can prevent that the chip | tip C adheres to the film T and lifts at the time of peeling.

  After the BG tape B is peeled off, the wafer W is placed on an expanded table (not shown) with the expanded tape E as an expanded film down, and the frame F is pushed down or the frame F is fixed and the table is raised. As a result, the expanded tape E is stretched to widen the interval between the chips C.

  The expanded wafer W is picked up from the expanded tape E for each chip C and conveyed to various subsequent processes.

<< Evaluation of crack growth by polishing >>
Next, crack growth evaluation by polishing in the grinding removal step (step S3) will be described with reference to FIGS. The polishing method, the dividing / separating method, and the conditions thereof are basically as described in steps S10 to S18. FIG. 19 is a diagram showing the conditions for crack growth evaluation, and FIG. 20 is a diagram showing the evaluation results for crack growth evaluation.

  In (A), (B), and (C) of FIG. 19, the horizontal axis is common and each position corresponds to each other, and indicates the polishing time (s). The vertical axis of (A) in FIG. 19 shows the cutting speed (polishing rate) (μm / s), the vertical axis of (B) shows ON / OFF of water supply to the grinding wheel during polishing, (C) The vertical axis indicates the temperature (° C.) of the back surface of the wafer W during polishing.

  As shown in FIG. 19A, a total of 710 μm of rough polishing was performed while changing the polishing rate, and then 13 μm (not shown) of fine polishing was performed, followed by 2 μm of chemical mechanical polishing (not shown). In the case of a wafer, as shown in FIG. 19B, an interruption period of water supply to the grindstone or the wafer was provided during the rough polishing. Water supply was stopped after elapse of t1 seconds after the start of polishing, and water supply was resumed after elapse of t2 seconds after the start of polishing. Water supply was performed at a flow rate of 10 L / min. Then, the said step S5, S6, S7 process was performed, the wafer was cleaved, and the cleaved state was observed and evaluated. The results are summarized in FIG. 20, where the case where the chip did not crack or generate dust and was cracked satisfactorily was marked as ◯, and that where the chip cracked or dusted was marked as x.

  As shown in FIG. 19C, the back surface temperature of the wafer W starts to rise rapidly after t1 seconds have elapsed since the start of polishing when the water supply was stopped, and decreases immediately after t2 seconds have elapsed since the start of polishing when the water supply was resumed. Began to do.

  As shown in FIG. 20, when the back surface temperature of the wafer W became 70 ° C. or higher by polishing, the wafer was cleaved satisfactorily. This is presumably because cracks formed by the laser progressed due to the heat of polishing.

  Therefore, the grinding apparatus according to the present invention includes a means for measuring the temperature of the wafer, a means for turning on / off water supply to the grindstone or the wafer during grinding, and the wafer temperature at a predetermined value after a predetermined time has elapsed since the start of grinding. And a means for controlling the water supply to the wafer to be turned off. Thereby, the crack formed with the laser can be advanced and the wafer can be cleaved satisfactorily.

  As described above, according to the present embodiment, since the crack in the modified region formed by the laser beam can be propagated by grinding, the modified component formed by the laser beam on the cross section of the chip C. It is possible to prevent the area from remaining. For this reason, it is possible to prevent a problem that the chip C is broken or dust is generated from the cross section of the chip C. Therefore, a stable quality chip can be obtained efficiently. Further, the stress of the pressing member is concentrated on the wafer cutting line, and the cleaving can be reliably and efficiently performed. Further, no contamination at the time of cleaving is left on the elastic body on which the wafer is placed, and even if cleaving is continuously performed, the wafer is not adversely affected.

(Appendix)
As can be understood from the description of the embodiment described in detail above, the present specification includes disclosure of various technical ideas including the invention described below.

  (Supplementary Note 1) The method for cleaving a semiconductor substrate according to the first aspect of the present invention is a cleaving method for cleaving a wafer having a modified region formed therein with laser light, wherein the wafer surface is made uniform and independent in each region. Then, the step of adsorbing to the table and the back surface of the wafer while grinding the wafer are ground and removed, micro cracks extending from the modified region are propagated in the depth direction of the wafer, and the modified region is ground and removed. After the grinding step, after the grinding step, perform chemical mechanical polishing, remove the work-affected layer introduced in the grinding step to make a mirror surface, and after the mirroring, an expanded tape is applied to the mirror-polished polishing surface. And a cleaving step of cleaving the wafer.

  (Supplementary Note 2) The method for cleaving a semiconductor substrate according to the second aspect of the present invention is the first aspect, wherein the modified layer is formed by laser light along the cutting line, the back grind tape is adhered to the surface, and the back surface The wafer with the expanded tape attached thereto is placed on a table having an elastic body attached to the upper surface, the table is rotated so that the pressing member is parallel to the cutting line, and the pressing member is moved to the wafer. The cutting line is cleaved by pressing and rolling.

  (Additional remark 3) The cleaving method of the semiconductor substrate which concerns on the 3rd aspect of this invention is a 2nd aspect. WHEREIN: The said press member is formed in the radius smaller than the space | interval of the said cutting line.

  (Additional remark 4) The cleaving method of the semiconductor substrate which concerns on the 4th aspect of this invention is a 2nd aspect or a 3rd aspect. WHEREIN: A groove | channel, a hole, Or unevenness is formed.

  (Additional remark 5) The cleaving method of the semiconductor substrate which concerns on the 5th aspect of this invention WHEREIN: When sticking the said back grind tape or the said expand tape in any one aspect of a 2nd aspect-a 4th aspect, A sticking roller rolls and sticks in the direction which inclines and cross | intersects with respect to the said cutting line formed in grid | lattice form.

  DESCRIPTION OF SYMBOLS 1 ... Laser dicing apparatus, 2 ... Grinding apparatus, 3 ... Tape sticking apparatus, 11 ... Wafer moving part, 13 ... Adsorption stage, 20 ... Laser optical part, 30 ... Observation optical part, 40 ... Laser head, 50 ... Control part, DESCRIPTION OF SYMBOLS 118 ... Rough grinding stage, 120 ... Fine grinding stage, 122 ... Polishing stage, 132, 136, 138, 140 ... Chuck, 146, 154 ... Cup type grindstone, 156 ... Polishing cloth, 211 ... Table, 212 ... Elastic body, 212a ... groove, 213 ... supply reel, 214 ... sticking roller, 215,216 ... guide roller, 217 ... winding reel, 218 ... pressing member, B ... BG tape, C ... chip, E ... expanded tape, F ... frame, K ... reforming region, L ... laser beam, S ... cutting line, W ... work

Claims (4)

In the cleaving method for cleaving a wafer in which a modified region is formed with laser light inside,
Grinding step that uniformly adsorbs the surface of the wafer to a table, grinds the back surface of the wafer and removes the modified region, and propagates microcracks extending from the modified region in the wafer depth direction;
After the modified region is removed by the grinding, a polishing step for polishing the wafer to make a mirror surface;
After the mirror surface, a cleaving step for cleaving the wafer,
A method for cleaving a semiconductor substrate.   The method for cleaving a semiconductor substrate according to claim 1, wherein the grinding step is performed using a grinding wheel, and the polishing step is performed using a polishing cloth. In a cleaving device that cleaves a wafer in which a modified region is formed with laser light inside,
Grinding means for uniformly adsorbing the front surface of the wafer to a table, grinding the back surface of the wafer to remove the modified region, and developing microcracks extending from the modified region in the wafer depth direction;
After the modified region is removed by the grinding, polishing means for polishing the wafer to make a mirror surface;
Cleaving means for cleaving the wafer after the mirroring;
A semiconductor substrate cleaving apparatus.   4. The semiconductor substrate cleaving apparatus according to claim 3, wherein the grinding by the grinding means and the polishing by the polishing means are performed on the same table.

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