JP6162578B2 - Wafer dividing method - Google Patents

Description

  The present invention relates to a wafer dividing method in which a wafer having an annular convex portion formed on the outer periphery of the back surface of a wafer is divided into individual devices.

  In recent years, it has been required to reduce the thickness of a wafer, for example, 50 μm or less, in order to achieve a reduction in weight and size of electrical equipment. Such a thinly formed wafer has a reduced rigidity and is difficult to handle due to warpage, and may be damaged during transportation. Therefore, a grinding method has been proposed in which only the back surface corresponding to the device region where the device of the wafer is formed is ground to form a reinforcing annular convex portion on the back surface corresponding to the outer peripheral surplus region surrounding the device region. (For example, refer to Patent Document 1).

  There has been proposed a method of removing an annular protrusion from a wafer before dividing the wafer on which the annular protrusion is formed along the planned dividing line (see, for example, Patent Document 2). In the method described in Patent Document 2, an interface between a circular concave portion formed by back surface grinding and an annular convex portion surrounding the circular concave portion is cut into a circle by a cutting blade, and the annular convex portion is separated from the wafer. Then, the wafer is divided into individual devices by cutting with a cutting blade along the division line from the surface side of the wafer.

JP 2007-173487 A JP 2007-19379 A

  However, in the method described in Patent Document 2, since the interface between the circular concave portion and the annular convex portion is cut into a circle by the cutting blade, a device cannot be formed in the vicinity of the circular cutting region. For this reason, as compared with a normal wafer having no annular convex portion, the device region has to be narrowed by the amount that a circular cutting region is formed.

  The present invention has been made in view of these points, and an object of the present invention is to provide a wafer dividing method capable of dividing a wafer into individual devices without narrowing the device region.

  The wafer dividing method of the present invention has a device region formed by dividing a plurality of devices on the front surface on a predetermined division line and an outer peripheral surplus region surrounding the device region, and a recess is formed on the back surface corresponding to the device region. A wafer dividing method for dividing a wafer having an annular convex portion on the outer peripheral portion into a plurality of devices along a planned dividing line, and having an adhesive layer on the upper surface and having a diameter larger than the outer diameter of the wafer A support member preparing step for preparing a support member having a rigid plate adhered to the center of the adhesive sheet and having a diameter smaller than the inner diameter of the concave portion of the wafer, and a support member by exposing the rigid plate on the flat stage. The liquid resin that is cured by external stimulus is supplied onto the rigid plate, and the stage and wafer are pressed against each other with the concave portion of the wafer facing the liquid resin. Then, while inserting the rigid plate into the recess, spread the liquid resin in the gap between the recess and the rigid plate and spread it to the upper surface of the adhesive sheet, cure it by applying external stimulus, and stick the support member to the wafer After the sticking process and the wafer sticking process, the front side of the wafer is exposed and the adhesive sheet side is held on the holding table, and the wafer is cut along the planned dividing line while cutting the cutting blade partway into the liquid resin. A dividing step of dividing the device region into a plurality of devices, and a peeling step of peeling the liquid resin, the annular protrusion, and the support member from the plurality of devices after the dividing step is performed.

  According to this configuration, the support member is attached to the back surface of the wafer, and the resin enters the concave portion of the wafer together with the rigid plate, so that the entire back surface of the wafer can be supported on the holding table via the support member. . Therefore, it is not necessary to remove the annular protrusion from the wafer in advance, and in the same way as with a normal wafer that does not have an annular protrusion, the wafer can be cut into individual devices by cutting along the planned dividing line with a cutting blade. Can be divided. Since the device is not cut into a circle along the interface between the concave portion and the annular convex portion, the device region is not narrowed by the circular cutting region, and a device region having the same width as a normal wafer is provided. Can do. This is particularly effective for small chips and large-diameter wafers.

  According to the present invention, before the wafer is divided, the support member is attached to the back surface of the wafer so that the resin enters the concave portion of the wafer together with the rigid plate. Can be divided into good devices.

It is a perspective view of the wafer which concerns on this Embodiment. It is a figure which shows an example of the back surface grinding process of the wafer which concerns on this Embodiment. It is a figure which shows an example of the support member preparation process which concerns on this Embodiment. It is a figure which shows an example of the wafer sticking process which concerns on this Embodiment. It is a figure which shows an example of the division | segmentation process which concerns on this Embodiment. It is a figure which shows an example of the peeling process which concerns on this Embodiment.

  Hereinafter, a wafer dividing method according to the present embodiment will be described with reference to the accompanying drawings. The wafer dividing method according to the present embodiment is carried out on a so-called TAIKO wafer that is formed by grinding only the inner periphery of the wafer, leaving only the outer peripheral portion of the back surface of the wafer. First, a process for forming a TAIKO wafer will be briefly described with reference to FIGS. FIG. 1 is a perspective view of a wafer according to the present embodiment. FIG. 2 is a diagram illustrating an example of a wafer back grinding process according to the present embodiment.

  As shown in FIG. 1, the wafer W is formed in a substantially disk shape, and is partitioned into a plurality of regions by grid-like division planned lines (not shown) arranged on the surface 11. In the center of the wafer W, a device D is formed in each region partitioned by the division lines. The surface 11 of the wafer W is divided into a device region A1 where a plurality of devices D are formed and an outer peripheral surplus region A2 surrounding the device region A1. A notch 14 indicating a crystal orientation is formed on the outer edge 13 of the wafer W. The wafer W is carried into the grinding device 21 (see FIG. 2) with the grinding tape 18 attached to the surface 11.

  As shown in FIGS. 1 and 2, in the grinding device 21, the front surface 11 side of the wafer W is held on the holding table 22 via the grinding tape 18 with the back surface 12 of the wafer W facing upward. Then, the grinding wheel 23 of the grinding device 21 approaches the holding table 22 while rotating around the Z axis, and the grinding wheel 23 and the back surface 12 of the wafer W are in rotational contact with each other, whereby the wafer W is ground. At this time, only the back side of the device region A1 on the front surface 11 of the back surface 12 of the wafer W is ground. Thereby, on the back surface 12 of the wafer W, a circular concave portion 15 is formed in a region corresponding to the device region A1, and an annular convex portion 16 is formed in a region corresponding to the outer peripheral surplus region A2.

  In this way, only the central portion of the wafer W is thinned by the concave portion 15, and the rigidity of the wafer W is enhanced by the annular convex portion 16 surrounding the concave portion 15. Therefore, the device region A1 of the wafer W is thinned, and the warpage of the wafer W is suppressed by the annular convex portion 16, and damage during transportation is prevented. The ground wafer W is transported toward a subsequent process in a state where the grinding tape 18 is peeled off from the surface 11. The wafer W may be a semiconductor wafer such as silicon or gallium arsenide, or a ceramic, glass, or sapphire optical device wafer.

  By the way, when the wafer W is divided along the planned division line of the front surface 11 and the concave portion 15 is formed on the back surface 12 of the wafer W, the back surface 12 side of the wafer W cannot be held on the table. For this reason, the rear surface 12 of the wafer W is usually flattened by separating the annular convex portion 16 from the wafer W or filling the concave portion 15 with only resin. However, when the wafer W is cut into a circular shape and the annular convex portion 16 is separated, the device region A1 must be narrowed by an amount corresponding to the provision of the circular cutting region between the concave portion 15 and the annular convex portion 16. Further, when the recess 15 of the wafer W is filled only with the resin, it is necessary to planarize the resin surface, and the wafer W may be damaged due to shrinkage during resin curing.

  Therefore, in the method for dividing the wafer W according to the present embodiment, the support member 25 (see FIG. 3) is provided on the back surface 12 side of the wafer W instead of separating the annular convex portion 16 of the wafer W or filling the concave portion 15 with only resin. ) Is attached, and the wafer W is divided into individual devices D. In the wafer W dividing method according to the present embodiment, the wafer W is divided into individual devices D through a support member preparation step, a wafer sticking step, a dividing step, and a peeling step. In the support member preparation step, a support member 25 is prepared in which a rigid plate 27 having a diameter smaller than the inner diameter of the recess 15 of the wafer W is attached to the center of the adhesive sheet 26 having a diameter larger than the outer diameter of the wafer W (see FIG. 3).

  In the wafer sticking step, the liquid resin 36 is supplied onto the rigid plate 27 of the support member 25, and the rigid plate 27 is inserted into the concave portion 15 of the wafer W, so that the liquid resin 36 is spread to reach the adhesive sheet 26. Then, the liquid resin 36 is cured, and the support member 25 is adhered to the back surface 12 of the wafer W (see FIG. 4). In the dividing step, the wafer W held on the holding table 41 via the support member 25 is cut along the dividing line on the surface 11 side by the cutting blade 42 and divided into a plurality of devices D (FIG. 5). reference). In the peeling process, the liquid resin 36, the annular protrusion 16, and the support member 25 are peeled from the plurality of devices D (see FIG. 6).

  Hereinafter, the method for dividing the wafer W according to the present embodiment will be described in detail with reference to FIGS. FIG. 3 shows an example of a support member preparation process, FIG. 4 shows a wafer sticking process, FIG. 5 shows a dividing process, and FIG. 6 shows an example of a peeling process.

  As shown in FIG. 3, a support member preparation step is first performed. In the support member preparation step, an adhesive sheet 26 having a diameter larger than the outer diameter of the wafer W and a rigid plate 27 having a diameter smaller than the inner diameter of the recess 15 of the wafer W are prepared. The adhesive sheet 26 is formed into a sheet shape with PET (polyethylene terephthalate) or the like, and an adhesive layer is provided on the upper surface. The rigid plate 27 is made of a material that transmits ultraviolet rays, such as glass, and is formed in a plate shape whose upper and lower surfaces are flat. And the support member 25 is formed by sticking the rigid board 27 to the center of the upper surface of the adhesive sheet 26 so that air bubbles do not enter between the adhesive sheet 26 and the rigid board 27. The support member preparation step may be performed manually by an operator or may be performed by a manufacturing apparatus (not shown) for the support member 25.

  As shown in FIG. 4, a wafer sticking process is implemented after a support member preparation process. As shown in FIG. 4A, in the wafer sticking step, the support member 25 is placed on the stage 31 of the wafer sticking apparatus (not shown) with the adhesive sheet 26 facing down, and the flat stage 31 is rigid. A plate 27 is exposed. Above the support member 25, the front surface 11 of the wafer W is held by a press machine 32 of the wafer sticking apparatus, and the concave portion 15 on the back surface 12 side of the wafer W is directed downward. For this reason, the concave portion 15 of the wafer W held by the press machine 32 and the rigid plate 27 of the support member 25 on the stage 31 face each other in the vertical direction.

  The upper surface of the stage 31 is composed of a flat translucent plate 33, and an ultraviolet irradiator 34 that irradiates ultraviolet rays from the stage 31 through the translucent plate 33 is provided inside the stage 31. In this state, a liquid resin 36 that is cured by an external stimulus is supplied onto the rigid plate 27. In the present embodiment, as the liquid resin 36, a resin that is cured by ultraviolet rays and is softened by the heat of warm air (for example, 80 ° C. or more) is used.

  Next, as shown in FIG. 4B, the press machine 32 is brought close to the stage 31, and the wafer W held by the press machine 32 is pressed against the support member 25 on the stage 31. At this time, when the rigid plate 27 of the support member 25 enters the recess 15 of the wafer W, the liquid resin 36 is spread in the gap between the recess 15 and the rigid plate 27. When the liquid resin 36 reaches the upper surface of the adhesive sheet 26 and the liquid resin 36 protrudes from the outer edge 13 of the wafer W, the descent of the press machine 32 is stopped. At this time, since the rigid plate 27 is adhered to the adhesive sheet 26, the liquid resin 36 does not enter between the adhesive sheet 26 and the rigid plate 27, and the lower surface 28 of the support member 25 is kept flat. .

  Then, ultraviolet light is irradiated from the ultraviolet irradiator 34, and external stimulus is applied to the liquid resin 36 by the ultraviolet light transmitted through the translucent plate 33, the adhesive sheet 26 and the rigid plate 27, and the support member 25 is attached to the wafer W Is done. At this time, since the liquid resin 36 protrudes from between the annular convex portion 16 (R-shaped lower portion) of the wafer W and the upper surface of the adhesive sheet 26, the holding force from the outer edge 13 of the wafer W is also strengthened by the hardening of the liquid resin 36. Has been. As described above, since the liquid resin 36 spreads on the basis of the flat stage 31, a flat surface parallel to the surface 11 of the wafer W is formed on the lower surface 28 of the support member 25.

  In this case, compared to a configuration in which the recess 15 of the wafer W is filled with only the liquid resin 36, the supply amount of the liquid resin 36 is suppressed by the amount of the rigid plate 27 in the recess 15 of the wafer W. . Therefore, the influence by the shrinkage at the time of hardening of the liquid resin 36 is suppressed, and the wafer W is not damaged by the shrinkage of the liquid resin 36.

  As shown in FIG. 5, a dividing step is performed after the wafer attaching step. In the dividing step, the wafer W is held via the support member 25 on the holding table 41 of the cutting apparatus (not shown) so that the surface 11 side of the wafer W is exposed. The cutting blade 42 is aligned with the division line on the outer side in the radial direction of the wafer W, and is lowered to a height at which the liquid resin 36 can be cut halfway at this position. Then, the wafer W on the holding table 41 is cut and fed to the cutting blade 42 that rotates at a high speed, whereby the wafer W is cut along the division line.

  When the wafer W is cut along one division line, the cutting blade 42 is aligned with the adjacent division line and cut. This operation is repeated and the wafer W is cut along all the division lines in one direction. After cutting along all the division lines in one direction of the wafer W, the holding table 41 is rotated by 90 degrees, and similarly along the division lines in the other direction orthogonal to the division line in one direction. The wafer W is cut. As a result, only the device region A1 thinned by the recess 15 is fully cut along the division planned line, and the wafer W is divided into a plurality of devices D.

  In this dividing step, even when the recess 15 is formed on the back surface 12 of the wafer W, the support member 25 is attached to the back surface 12 side of the wafer W, so that the wafer W is supported by the holding table 41 as a whole. Is done. For this reason, it is not necessary to remove the annular convex portion 16 from the wafer W or to flatten the back surface 12 side of the wafer W. Therefore, the wafer W can be divided into individual devices D by cutting along the planned dividing line by the cutting blade 42 as in the case of the normal wafer W that does not have the annular protrusion 16 on the outer periphery of the wafer W. it can.

  As shown in FIG. 6, a peeling process is performed after the dividing process. As shown in FIG. 6A, in the peeling process, the wafer W is placed on the stage 45 via the support member 25. When the warm air is blown toward the device D from the warm air injector 46 provided above the stage 45, the cured liquid resin 36 is softened by the warm air. Thereby, the holding force of the liquid resin 36 is weakened, and the device D is easily peeled from the support member 25. Since the warm air is blown from above, the holding force of the liquid resin 36 on the rigid plate 27 is weakened, but the holding force of the liquid resin 36 that protrudes from the side of the rigid plate 27 and the outer edge 13 of the wafer W onto the adhesive sheet 26. Is becoming difficult to weaken.

  Next, as shown in FIG. 6B, the expanded tape 48 is attached to the surface 11 of the device D. Since the holding force of the liquid resin 36 is weakened, the device D is held on the expanded tape 48 stronger than the liquid resin 36. Then, the expanding tape 48 is pulled up from the end, whereby the plurality of devices D are peeled from the liquid resin 36. At this time, since the outer edge 13 of the annular protrusion 16 is formed in an R shape, it is held in a wider range by the liquid resin 36 protruding from the outer edge 13 than the expanded tape 48. Further, since the holding force of the lower liquid resin 36 is not easily lowered by the hot air, the annular convex portion 16 of the wafer W is left on the support member 25 when the device D is peeled off.

  In this way, the liquid resin 36, the annular convex portion 16, and the support member 25 are peeled from the plurality of devices D. Next, as shown in FIG. 6C, a ring frame 47 is attached to the outer periphery of the expanding tape 48 and carried into an expanding device (not shown), and the expansion of the expanding tape 48 widens the intervals between the plurality of devices D. Then, the plurality of devices D are peeled from the expanded tape 48 by a picker (not shown).

  In the peeling step, as shown in FIG. 6A, instead of the configuration in which the holding force of the liquid resin 36 is reduced by hot air, the holding force of the liquid resin 36 is reduced by hot water as shown in FIG. 6D. Is also possible. In this case, the support member 25 with the device D is immersed in the warm water in the container 49, and the liquid resin 36 is swelled by the warm water (for example, 80 ° C. or more), thereby peeling the liquid resin 36 from the plurality of devices D. It is easy.

  As described above, according to the wafer W dividing method according to the present embodiment, the support member 25 is adhered to the back surface 12 of the wafer W, and the resin enters the recess 15 of the wafer W together with the rigid plate 27. The entire back surface 12 of the wafer W can be supported on the holding table via the support member 25. Therefore, it is not necessary to remove the annular convex portion 16 from the wafer W in advance, and the wafer is cut by the cutting blade 42 along the planned dividing line in the same manner as the normal wafer W without the annular convex portion 16. W can be divided into individual devices D. Since the device is not cut into a circle along the interface between the concave portion 15 and the annular convex portion 16, the device region A1 is not narrowed by the circular cutting region, and the device has the same size as the normal wafer W. Region A1 can be provided. This is particularly effective for small chips and large-diameter wafers W.

  In addition, this invention is not limited to the said embodiment, It can change and implement variously. In the above-described embodiment, the size, shape, and the like illustrated in the accompanying drawings are not limited to this, and can be appropriately changed within a range in which the effect of the present invention is exhibited. In addition, various modifications can be made without departing from the scope of the object of the present invention.

  In the above-described method for dividing the wafer W, the liquid resin 36 is cured by ultraviolet rays and the holding force of the liquid resin 36 is decreased by hot air and hot water. However, the present invention is not limited to this structure. The liquid resin 36 may be a resin that is cured by an external stimulus, and may be, for example, a thermosetting resin that is thermoset. The term “external stimulus” as used herein refers to stimuli caused by at least one of radiation, electron beam, electric field, chemical reaction and the like as well as ultraviolet rays and heat. In the case where a resin that is cured by ultraviolet rays is not used as the liquid resin 36, the rigid plate 27 is not limited to a material that transmits ultraviolet rays. Further, as the liquid resin 36, a resin that can be peeled off without applying warm air or warm water may be used.

  As described above, the present invention has an effect that the wafer can be divided into individual devices without narrowing the device region, and in particular, an annular convex portion is formed on the outer periphery of the back surface of the wafer. This method is useful for a wafer dividing method for dividing a wafer into individual devices.

DESCRIPTION OF SYMBOLS 11 Wafer surface 12 Wafer back surface 15 Concave part 16 Annular convex part 25 Support member 26 Adhesive sheet 27 Rigid board 31 Stage 36 Liquid resin 41 Holding table 42 Cutting blade A1 Device area A2 Outer peripheral area D Device W Wafer

Claims (1)

A device area formed by dividing a plurality of devices into division lines on the front surface and an outer peripheral surplus area surrounding the device area. A concave portion is formed on the back surface corresponding to the device area, and an annular convex portion is formed on the outer peripheral portion. A wafer dividing method for dividing a wafer provided with a plurality of devices along the division line.
Support member preparation for preparing a support member having an adhesive layer on the upper surface and a rigid plate having a diameter smaller than the inner diameter of the concave portion of the wafer and flat on both sides in the center of the adhesive sheet having a diameter larger than the outer diameter of the wafer Process,
The rigid plate is exposed on a flat stage, the adhesive sheet side of the support member is placed, a liquid resin that is cured by an external stimulus is supplied onto the rigid plate, and the concave portion of the wafer is placed in the liquid state. The stage and the wafer are pressed against each other while facing the resin, and the liquid resin is spread in the gap between the recess and the rigid plate while inserting the rigid plate into the recess to reach the upper surface of the adhesive sheet. A wafer sticking process in which the support member is stuck to the wafer,
After the wafer adhering step, the front surface side of the wafer is exposed and the adhesive sheet side is held on a holding table, and the wafer is cut along the planned dividing line while cutting a cutting blade partway through the liquid resin. A dividing step of dividing the device region into a plurality of devices;
A peeling step of peeling the liquid resin, the annular convex portion and the support member from the plurality of devices after performing the dividing step;
A wafer dividing method comprising:

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