JP4308344B2 - Double-side polishing equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a double-side polishing apparatus.
Conventionally, as a double-side polishing apparatus, an external gear (hereinafter referred to as an “external gear”) and an internal gear (hereinafter referred to as an “internal gear”) are rotated at different angular velocities to process a material (hereinafter referred to as “workpiece”). The upper surface plate and the lower surface plate having the polishing surfaces arranged on the upper and lower sides of the carrier are rotated and revolved while sandwiching the workpiece from above and below and relative to the workpiece. There is one using a planetary gear mechanism that moves to and polishes. This double-sided polishing machine is used as a lapping machine (lapping machine) or a polishing machine, which has high accuracy and can polish both sides simultaneously, so that the processing time is short, and thin objects such as silicon wafers that are used as semiconductor chip materials can be polished. Suitable for
[0002]
[Prior art]
A configuration of a polishing apparatus using a conventional planetary gear mechanism will be described with reference to FIG.
112 is an upper surface plate and 114 is a lower surface plate. A polishing cloth (cross) is attached to each surface, and a polishing surface is formed by the polishing cloth. 116 is an external gear, and 118 is an internal gear. Reference numeral 120 denotes a carrier. The workpiece 121 is held in a through hole formed in the carrier 120, and the external gear 116 and the internal gear 118 are engaged with each other to rotate.
The upper surface plate 112 is connected to an upper surface plate turner 112a, and a gear 112c is provided at the tip of a shaft 112b suspended from the upper surface plate turner 112a. The gear 112c meshes with the idle gear 112d, and the idle gear 112d meshes with the gear 112e. The gear 112e is provided coaxially with the spindle 126 so as to rotate integrally with the spindle 126. The lower surface plate 114 is connected to a gear 114 b provided coaxially with the spindle 126 via a gear 114 a provided coaxially with the lower surface plate 114. The external gear 116 is connected to a transmission gear 116 b provided coaxially with the spindle 126 via a gear 116 a provided coaxially with the external gear 116. The internal gear 118 is connected to a transmission gear 118 b provided coaxially with the spindle 126 via a gear 118 a provided coaxially with the internal gear 118. That is, this polishing apparatus is a so-called 4-way drive system in which the external gear 116, the internal gear 118, the upper surface plate and the lower surface plates 112, 114 are rotationally driven by one drive device.
The spindle 126 is connected to a variable speed reducer 132. The variable speed reducer 132 is connected to a motor 134 via a belt 136, and controls the rotational speed of the spindle 126.
[0003]
According to the polishing apparatus using this planetary gear mechanism, for example, the rotation ratio between the gear 116a and the transmission gear 116b and the transmission with the gear 118a so that the angular speed of the internal gear 118 is larger than the angular speed of the external gear 116. When the rotation ratios of the gears 118b are set, the carrier 120 meshed between the external gear 116 and the internal gear 118 has the same direction as the rotation direction of the internal gear 118 (for example, “counterclockwise”). Revolves and rotates clockwise. Similarly, the lower surface plate 114 rotates counterclockwise, but the upper surface plate 112 rotates clockwise because of the idle gear 112d.
Depending on the polishing conditions, the rotation direction and rotation speed of the carrier 120 can be changed by setting the angular speeds of the external gear 116 and the internal gear 118.
[0004]
Further, a liquid abrasive containing abrasive grains or the like is supplied to the front and back polishing surfaces of the workpiece 121, and the workpiece 121 is suitably polished by the action of the liquid abrasive. In the polishing of a silicon wafer, a polishing agent (commonly referred to as “slurry”) in which abrasive grains are dispersed in an alkaline polishing liquid is usually supplied between the silicon wafer and the polishing surface of a polishing platen for polishing. The
As a method of supplying the liquid abrasive, the liquid abrasive is dropped from above using a pump power and gravity through an abrasive supply hole provided through the upper surface plate 112 in the vertical direction. It is generally made to supply. The liquid abrasive discharged from the abrasive supply hole is supplied to a polishing section where the polishing surface of the upper surface plate 112 and the workpiece 121 come into contact with each other to polish the workpiece 121 and between adjacent carriers 120. , And flows onto the polishing surface of the lower surface plate 114, and the polishing surface of the lower surface plate 114 and the work 121 come into contact with each other and are supplied to a polishing unit for polishing the work 121.
[0005]
FIG. 12 is a plan view for explaining an arrangement example of the carriers 120 according to the polishing apparatus of FIG. 11, and there is a gap A between adjacent carriers 120. The gap A is present in a sufficiently wide area at both the inner diameter portion and the outer diameter portion, and the liquid abrasive is suitably supplied also onto the polishing surface of the lower surface plate 114. As described above, the liquid abrasive is sufficiently supplied to both surfaces of the workpiece 121 by a simple supply means from above.
According to this polishing apparatus, since the liquid abrasive can be suitably supplied and the carrier 120 can be moved in a complicated manner, polishing unevenness can be prevented and the workpiece 121 (for example, a silicon wafer) can be uniformly polished. Therefore, the flatness of the workpiece can be improved. Moreover, since both surfaces of the workpiece 121 can be polished simultaneously, the polishing efficiency can be improved.
[0006]
However, since the double-side polishing apparatus using the conventional planetary gear mechanism has a structure in which the carrier 120 moves between the external gear 116 and the internal gear 118, it can cope with the recent increase in size of the workpiece 121 such as a silicon wafer. Hateful. That is, it is impossible to make the diameter of the carrier 120 larger than the radius of the surface plate, and the polished surface of the surface plate cannot be used efficiently.
Moreover, in the double-side polishing apparatus using the conventional planetary gear mechanism, it is a complicated gear mechanism, and it is difficult to increase the size, and in order to manufacture a large apparatus, problems in materials, processing, arrangement space, etc. Cost increases in various aspects.
[0007]
Therefore, the applicant of the present application has developed the following double-side polishing apparatus as background art.
In other words, the double-side polishing apparatus sandwiches a carrier, which is a thin plate and has a through-hole, and a wafer, which is a plate-like work placed in the through-hole of the carrier, from above and below, and is relative to the wafer. A double-side polishing apparatus comprising an upper surface plate and a lower surface plate having a polishing surface to be moved and polished in a circular manner, wherein the carrier moves in a circular motion in a plane parallel to the surface of the carrier via a carrier holder. And a carrier turning motion mechanism for turning the wafer held between the upper surface plate and the lower surface plate in the through hole. The upper surface plate and the lower surface plate are provided so as to rotate (rotate).
[0008]
Then, in order to supply the liquid abrasive to the polishing portion where the polishing surfaces of the upper surface plate and the lower surface plate come into contact with the wafer and polish the wafer, a liquid abrasive (slurry) is used as shown in FIG. It is falling naturally. Reference numeral 39 denotes a slurry ring, which is formed in a ring-like groove shape so as to store the slurry pumped up by a liquid abrasive supply device (not shown). Reference numeral 39a denotes a supply pipe, which is provided as a pipe line that connects the slurry ring 39 and the abrasive supply hole 14b provided in the upper surface plate 14. The slurry naturally falls through the supply pipe 39a, is discharged from the abrasive supply hole 14b, and is supplied to the polishing section.
Reference numeral 72 denotes a spline shaft, which rotates the upper surface plate 14 so as to be movable up and down. Reference numeral 76 denotes a fixed plate, which is fixed to the lower end of the spline shaft 72. Fixed to the fixed plate 76 are lower ends of a plurality of airbags 77 and a plurality of oscillating bearings 78 for bearing the suspension shaft 79 so as to oscillate. Reference numeral 80 denotes a movable plate which is provided not to be fixed to the spline shaft 72 but capable of moving up and down. The outer peripheral portion is the slurry ring 39, and the upper end and the lower end of the airbag 77 are connected to the upper surface plate 14. The upper end of the fixed suspension shaft 79 is fixed. Therefore, if the airbag 77 is pressurized, a force in the direction of lifting the upper surface plate 14 can be obtained, and the pressure load applied to the wafer by the upper surface plate 14 can be controlled. Further, by the action of the rocking bearing 78, the polishing surface of the upper surface plate 14 can be tilted by following the polishing surface of the lower surface plate 16 (see FIG. 1).
[0009]
[Problems to be solved by the invention]
However, in the above-described double-side polishing apparatus of the background art, the carrier 12 covers the lower surface plate 16 entirely, and when the liquid abrasive is supplied from the abrasive supply hole 14b of the upper surface plate 14, the liquid There was a problem that the abrasive accumulated on the upper side of the carrier 12 and did not flow downward, and was not sufficiently supplied to the polishing surface of the lower surface plate 16.
That is, the amount of supply is sufficient to the extent that the slurry leaks out and is supplied to the polishing surface of the lower surface plate 16 from a slight gap between the inner peripheral surface of the through hole holding the workpiece and the outer peripheral surface of the workpiece. There wasn't.
On the other hand, as shown in FIG. 1 or FIG. 3, when the communication hole 15 for allowing the slurry to pass through is provided in the carrier 12, there is a certain effect. However, since the distance between each polishing surface and the surface of the carrier 12 is very narrow, it flows only where it easily flows, and it is difficult to supply a slurry with a sufficient flow rate over the entire surface. In particular, it was difficult to supply the slurry near the center of each surface plate.
As described above, the slurry is not suitably supplied to the polishing section, thereby causing temperature variation on the polishing surface of each surface plate. This is because when the supply flow rate of the slurry is not sufficient, the polishing heat due to the friction between the workpiece and the polishing surface cannot be suitably cooled. When temperature variation occurs on the polished surface in this way, the polishing conditions differ depending on each part of the workpiece, and as a result, the polishing accuracy of the workpiece is reduced.
[0010]
Accordingly, an object of the present invention is a double-side polishing apparatus including a carrier that moves in a circular motion that does not rotate. Polishing accuracy is improved by enabling supply of a liquid abrasive at a flow rate.
[0011]
[Means for Solving the Problems]
  In order to achieve the above object, the present invention comprises the following arrangement.
  That is, the present inventionA double-side polishing apparatus that polishes both surfaces of a workpiece disposed in a through hole of a carrier sandwiched between an upper surface plate and a lower surface plate by each polishing surface of the upper surface plate and the lower surface plate. , Make the carrier move in a circular motion so as not to rotateCarrier turning motion mechanism and upper surface plateAn upper and lower pipe for supplying an abrasive provided in a hollow rotating shaft that rotates in a predetermined direction, a temperature sensor provided near each of a plurality of abrasive supply holes formed in the upper surface plate, and A branch pipe provided on the upper surface of the upper surface plate and supplying the abrasive supplied by the upper and lower pipes to each of the abrasive supply holes, and an output signal of the temperature sensor are input, and the abrasive supply holes Sending a command signal to a flow rate changing mechanism that changes the flow rate of the abrasive supplied to each so as to equalize the temperature of the polishing surfaceSequencer for controlling the abrasive flow rateAnd comprising.
[0012]
  Also,The flow rate changing mechanism is a pressure supply device including a tank for storing an abrasive and a pump for pumping the abrasive, and the pressure supply device is connected to each of the branch pipes via a distributor.It is characterized by that.
  Alternatively, the flow rate changing mechanism is an automatic flow rate control valve provided in each of the branch pipes.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 is an exploded perspective view schematically showing an embodiment of the basic configuration of the double-side polishing apparatus of the present invention, and FIG. 2 shows the positional relationship of each configuration when the embodiment of FIG. 1 is operating. It is a sectional side view shown.
The present embodiment is a double-side polishing apparatus for polishing a silicon wafer 10 which is a plate-like workpiece, and is provided in a carrier 12 having a thin flat plate provided with a through hole 12a and disposed in the through hole of the carrier 12. An upper surface plate 14 and a lower surface plate 16 are provided that sandwich the wafer 10 from above and below and move relative to the wafer 10 for polishing. A polishing cloth called a cloth is attached to each surface of the upper surface plate 14 and the lower surface plate 16, and the polishing surfaces 14a and 16a are formed by the polishing cloth. Further, the upper surface plate 14 and the lower surface plate 16 of this embodiment are driven to rotate around an axis parallel to the direction orthogonal to the surface of the carrier 12.
The wafer 10 is circular and is loosely fitted in the circular through-hole 12a, and has a size that can rotate freely in the through-hole 12a.
The carrier 12 is generally formed of, for example, a glass epoxy plate and is set to have a thickness of about 0 or 7 mm with respect to a wafer 10 having a thickness of 0 or 8 mm.
[0017]
Reference numeral 20 denotes a carrier swivel movement mechanism that moves the carrier 12 in a plane parallel to the surface of the carrier 12 and is held between the upper surface plate 14 and the lower surface plate 16 in the through hole 12a. It is an example of the exercise | movement mechanism which exercises.
The carrier turning motion mechanism 20 in this embodiment causes the carrier 12 to make a circular motion that does not rotate in a plane parallel to the surface of the carrier 12, and is held in the through-hole 12 a so as to hold the upper surface plate 14 and the lower surface plate 16. The wafer 10 sandwiched by is rotated. That is, when the thickness of the carrier 12 is not considered, the carrier 12 is caused to perform a circular motion that does not rotate within the same plane as the surface of the carrier 12.
A specific configuration of the carrier turning motion mechanism 20 will be described below.
[0018]
A carrier holder 22 is formed in a ring shape and holds the carrier 12.
Here, the connecting means 50 for connecting the carrier 12 and the carrier holder 22 will be described. FIG. 3 is an explanatory view (a) is a plan view and (b) is a cross-sectional view) illustrating an example of the entire form of the carrier 12 and the carrier holder 22, and FIG. It is a principal part expanded sectional view.
The linking means 50 holds the carrier 12 by linking it to the carrier holder 22 so that the carrier 12 does not rotate and absorbs expansion due to thermal expansion of the carrier 12.
In the linking means 50 of this embodiment, as shown in FIG. 4, a pin 23 provided on the carrier holder 22 side, and an extension direction due to thermal expansion of the carrier 12 to the carrier 12 to be loosely fitted to the pin 23 (this embodiment) In the example, a hole 12b is formed with a clearance provided in the radial direction of the circular carrier 12. The clearance of the hole 12b may be suitably provided at least in the direction of absorbing the elongation due to the thermal expansion of the carrier 12, and may be formed, for example, as a long hole.
[0019]
Further, in this embodiment, the carrier 12 is formed so that a clearance is generated between the carrier 12 and the inner peripheral surface 22a of the carrier holder 22 so that the carrier 12 can slide suitably when thermally expanded. That is, the outer diameter of the carrier 12 is smaller than the inner diameter of the inner peripheral surface 22a by a predetermined size.
As described above, the hole 12b of the carrier 12 provided with a clearance in consideration of the thermal expansion of the carrier 12 is directly set by fitting into the pin 23 of the carrier holder 22.
Thus, by providing the connecting means 50 for absorbing the elongation due to the thermal expansion of the carrier 12, the carrier 12 can be suitably connected to the carrier holder 22 in a state of being prevented from rotating with a simple configuration.
Thereby, the elongation of the carrier 12 can be suitably released and absorbed, and the deformation of the carrier 12 can be prevented. Further, since the carrier 12 is configured to be fitted by being fitted to the carrier holder 22, the work at the time of loading is simplified.
[0020]
Next, the height adjustment function of the carrier 12 provided in the carrier holder 22 will be described.
Reference numeral 23 a denotes a flange portion, which is integrally provided in a washer shape in the middle portion of the pin 23. The flange portion 23a is provided on the carrier holder 22 side and serves as a support portion that directly supports the carrier 12 so as to hold it. A screw portion 23b is provided below the flange portion 23a of the pin 23 so that the pin 23 can be attached to the lower step portion 22b of the carrier holder 22. The height of the flange portion 23a can be adjusted by adjusting the degree of screwing of the screw portion 23b to the lower step portion 22b of the carrier holder 22. By providing the flange portion 23a in this manner, the carrier 12 can be appropriately held by the carrier holder 22 by suitably adjusting the height position of the carrier 12.
[0021]
That is, by adjusting the height of the flange portion 23a, it is possible to suitably cope with a change in conditions such as when the polishing cloth 16a of the lower surface plate 16 is consumed and thinned, and the surface of the polishing cloth 16a of the lower surface plate 16 is almost the same. At the same height, the carrier 12 can be suitably held so as not to bend. Therefore, the carrier 12 can be suitably held horizontally, and polishing cracks of the wafer 10 and deterioration of the polishing accuracy can be prevented.
Further, the outer peripheral surface of the carrier 12 is partially received by the surface of the flange portion 23a, and the sliding due to the expansion and contraction of the carrier 12 can be suitably supported. That is, since the contact area between the outer peripheral surface (lower surface) of the carrier 12 and the upper surface on the carrier holder 22 side can be reduced, the sliding frictional resistance can be reduced, and the carrier 12 can slide suitably. Thereby, the expansion and contraction force due to heat or the like of the carrier 12 is preferably released, and the occurrence of distortion of the carrier 12 can be prevented.
[0022]
In the above-described embodiment, the support height of the carrier 12 is adjusted by adjusting the height of the flange portion 23a of the pin 23. However, the present invention is not limited to this, and the carrier 12 is set to a predetermined value. The structure is not particularly limited as long as it is a suitable means that can support the height of the film.
For example, a mechanism for raising and lowering the carrier holder 22 itself and providing a support for supporting the carrier 12 may be basically the upper surface of the lower step 22 b of the carrier holder 22. Of course, the upper surface of the lower step portion 22b may be provided with unevenness in order to improve slipperiness.
[0023]
Next, another connecting means according to the present invention will be described with reference to FIG. FIG. 5A is a plan view, and FIG. 5B is a cross-sectional view.
As is apparent from the figure, this embodiment differs from the previous embodiment only in the connecting means 50, which includes an internal gear-like engaged portion 52 provided on the carrier holder 22 side, It has an external gear-like engaging portion 42 provided on the carrier 12 side so as to engage the engaged portion 52 with play. That is, the gear provided on the outer periphery of the carrier 12 and the gear provided on the inner periphery of the ring-shaped carrier holder 22 are engaged with each other with play. This also allows the carrier 12 to be suitably linked to the carrier holder 22 with a simple configuration. Then, the same effect as in the above embodiment can be obtained.
[0024]
Next, based on FIG.1 and FIG.2, the Example concerning each structure of the carrier turning motion mechanism 20 is demonstrated.
Reference numeral 24 denotes a crank member, which has a shaft axis 24 a on the holder side that is parallel to the axis L of the upper surface plate 14 and the lower surface plate 16 and is pivotally attached to the carrier holder 22, and a shaft center on the shaft 24 a on the holder side. Are parallel to each other, and a base-side shaft 24b is attached to the base 30 (see FIG. 2) at a predetermined distance. That is, it is formed to have the same function as the crank arm of the crank mechanism.
In the present embodiment, the crank member 24 is disposed at four positions between the base body 30 and the carrier holder 22, supports the carrier holder 22, and rotates the holder-side shaft 24 a around the base-side shaft 24 b. Thus, the carrier holder 22 is caused to perform a circular motion that does not rotate with respect to the base body 30. The holder-side shaft 24 a is rotatably inserted into a bearing portion 22 c provided so as to protrude from the outer peripheral surface of the carrier holder 22. As a result, the carrier 12 rotates eccentrically from the axis L of the upper surface plate 14 and the lower surface plate 16 (circular motion that does not rotate). The radius of the turning circular motion is the same as the distance between the holder-side shaft 24a and the base-side shaft 24b (the distance of the eccentricity M), and all the points of the carrier 12 are drawn in the locus of the same small circle. Become.
[0025]
Reference numeral 28 denotes a timing chain, which is wound around sprockets 25 (four in this embodiment) fixed coaxially to the base shaft 24b of each crank member 24. The timing chain 28 and the four sprockets 25 constitute a synchronizing means that links and synchronizes the four base body side shafts 24b so that the four crank members 24 are synchronously moved in a circular motion. This synchronization means has a simple configuration and can move the carrier 12 in a suitable and stable manner. As a result, the polishing accuracy can be improved, and the flatness of the wafer can be improved. The synchronizing means is not limited to the present embodiment, and it is needless to say that a timing belt or a gear may be used.
Reference numeral 32 denotes a motor (for example, a geared motor or a servo motor), and reference numeral 34 denotes an output gear fixed to the output shaft. The output gear 34 meshes with a gear 26 that is coaxially fixed to the shaft 24 b on the base body side of the crank member 24. As a result, a rotation drive device is configured to rotate the crank member 24 about the base-side shaft 24b.
[0026]
In addition, as a rotation drive device, the some motor (for example, electric motor) arrange | positioned corresponding to each crank member 24 can also be utilized. If it is an electric motor, the plurality of crank members 24 can be synchronously moved and the carrier 12 can be smoothly moved by being electrically synchronized.
In the present embodiment, the case where four crank members 24 are arranged has been described. However, the present invention is not limited to this, and the carrier holder 22 can be suitably supported if there are at least three crank members 24. .
Furthermore, if the moving body of the XY table that can obtain a two-dimensional motion by synthesizing two orthogonal linear motions and the carrier holder 22 can be integrated and moved, one crank member 24 can be moved. By driving, the carrier holder 22 can be circularly moved without rotating. That is, by being guided by guides extending on two orthogonal axes of the XY table, the moving body does not rotate, and the movement of the moving body is changed to the movement of the carrier holder 22 (circular movement not rotating). It can be suitably used.
Further, the XY table itself may be provided with driving means without using the crank member 24 at all. That is, by using an X-axis and Y-axis drive mechanism composed of a combination of a servo motor and a ball screw or a servo motor and a timing chain that directly drive the X-axis and Y-axis members, The integrated carrier holder 22 may be moved (a circular motion that does not rotate). In this case, at least two motors are used, but by controlling the motors, various two-dimensional motions that do not rotate can be obtained in addition to the swiveling circular motions, and the motions can be polished. Available to:
[0027]
Reference numeral 36 denotes a lower surface plate rotating motor, which is a power device for rotating the lower surface plate 16. For example, a geared motor or a servo motor can be used, and its output shaft may be directly connected to the rotating shaft of the lower surface plate 16.
Reference numeral 38 denotes power means for rotating the upper surface plate, which rotates the upper surface plate 14. As in the case of the lower platen rotation motor 36, an electric motor or the like that provides rotational power may be used as appropriate.
If the lower surface plate rotation motor 36 and the upper surface plate rotation power means 38 can freely change the rotation direction and the rotation speed, they can flexibly respond to various polishing specifications.
In this double-side polishing apparatus, the wafer 10 disposed in the through-hole 12a of the carrier 12 is sandwiched between the upper surface plate 14 and the lower surface plate 16 as shown in FIG. . At this time, the force with which the wafer 10 is pinched is mainly due to the pressurizing means provided on the upper surface plate 14 side (see FIG. 10). For example, air pressure is used, the maximum pressure is the weight of the upper surface plate 14, and the pressure applied to the wafer 10 by the upper surface plate 14 is an air bag system that acts to reduce the pressure by increasing the air pressure. May be adjusted. In this airbag system, the pressure can be adjusted suitably and easily by controlling the air pressure. In addition to the pressurizing means, an elevating device 40 for elevating and lowering the upper surface plate 14 is provided on the upper surface plate 14 side, and operates when the wafer 10 is supplied and discharged.
[0028]
As shown in FIG. 1, reference numeral 62 denotes a roller, which is an example of a vibration preventing means that abuts on the upper surface plate 14 and prevents the upper surface plate 14 from shaking in a direction parallel to the surface of the carrier 12. is there. The roller 62 is rotatably mounted on a guide roller body (not shown) provided in the vicinity of the upper surface plate 14 on the base 30 so as to abut on the outer periphery 14c of the upper surface plate 14 as appropriate. The plurality of rollers 62 sandwich the upper surface plate 14 during the polishing process, thereby restricting the movement of the upper surface plate 14 in the direction parallel to the surface of the carrier 12 and preventing vibration.
[0029]
Next, a means for supplying a liquid abrasive will be described with reference to FIGS.
The upper surface plate 14 is in contact with the polishing surface 14 a of the upper surface plate 14 and the wafer 10, and a polishing agent supply hole 14 b that supplies slurry (liquid polishing agent) to a polishing portion that polishes the wafer 10. Is provided.
The abrasive supply hole 14b may be appropriately provided in such a size that the liquid abrasive can be sufficiently and uniformly supplied to the polishing portion of the wafer 10 and does not adversely affect the polishing. The number is not particularly limited. In this embodiment, a total of 21 abrasive supply holes 14b are arranged in a matrix so that the holes 14b are uniformly distributed on the upper surface plate 14, and each is provided with a small diameter. The abrasive supply hole 14b of this embodiment is provided through the upper surface plate 14 in the vertical direction.
Although not shown in FIG. 3, a tube or the like is connected to the upper end of the abrasive supply hole 14b as shown in FIG. 10, and the liquid abrasive pumped up by a pump or the like is appropriately distributed and supplied. It is provided to be.
[0030]
Then, the liquid abrasive supplied from the abrasive supply hole 14b is passed through the carrier 12 so that the polishing surface 16a of the lower surface plate (lower surface plate 16) and the wafer 10 come into contact with each other, and the wafer 10 is removed. A communication hole 15 for supplying a liquid polishing liquid to the polishing portion to be polished is provided.
The communication hole 15 may be provided in an appropriate form at a position that does not affect the strength of the carrier 12, and the size, shape, or number thereof is not limited. In the embodiment shown in FIG. 3, a total of five circular communication holes 15 are formed in the center of the carrier 12 and between the through holes 12 a adjacent to each other in the circumferential direction of the carrier 12.
[0031]
According to the carrier 12, the liquid polishing liquid can be suitably supplied to both surfaces of the wafer 10 to be polished, and can be preferably polished. That is, the liquid polishing liquid can flow down from the communication hole 15, which is a hole formed in the carrier 12, and can preferably flow into the back surface of the wafer 10 (the surface in contact with the polishing surface 16 a). For this reason, polishing conditions can be made uniform and both surfaces of the wafer 10 can be polished with high accuracy.
The liquid polishing liquid supplied onto the polishing surface 16a sequentially overflows and is discharged from the polishing surface 16a in the outer peripheral direction, as in the case of the conventional double-side polishing apparatus, and further recovered and circulated as appropriate. .
[0032]
Next, based on FIGS. 6-9, the Example of the abrasive | polishing agent supply means which is the characteristic structure of this invention is described. FIG. 6 is a cross-sectional view illustrating the abrasive supply means provided on the lower surface plate. FIG. 7 is a cross-sectional view for explaining the abrasive supply means provided on the upper surface plate. 8 and 9 are explanatory views for explaining an abrasive supply means provided on the upper surface plate and provided with a plurality of systems of slurry (liquid abrasive) supply paths. In addition, about the structure same as the Example demonstrated above, the same code | symbol is attached | subjected and description is abbreviate | omitted.
[0033]
  In FIG.The polished surface 16aIn order to supply a liquid abrasive (slurry) to the polishing part that contacts the wafer 10 and polishes the wafer 10, the slurry fed by pressure is discharged from the abrasive supply hole 16b provided in the lower surface plate 16 An abrasive supply means is shown.
  Reference numeral 85 denotes a pressure supply device that pumps the slurry, and includes a tank that stores the slurry, a pump that pumps the slurry, and the like.
  Reference numeral 86 denotes a communication path, which is arranged in the vertical direction on the axis of the hollow rotation shaft 36a for rotating the lower platen 16 and communicates with the abrasive supply hole 16b, the upper and lower tubes 86a and the pressure supply device 85. Are constituted by a horizontal pipe 86b and a pipe joint. Through this communication path 86, the slurry pressurized to a high pressure is sent and discharged from the abrasive supply hole 16b.
  According to this abrasive supply means, a slurry having a sufficient flow rate can be forcibly and suitably supplied (pumped) to the polishing section, and in particular,Polished surface 16aCool down properly,Polished surface 16aThe surface temperature can be made uniform.
  The slurry discharged from the abrasive supply hole 16b provided in the central portion of the lower surface plate 16 is received by the polishing surface 16a of the lower surface plate 16, and suitably flows from the central portion to the outer periphery by centrifugal force. For this reason, although there is only one abrasive supply hole 16b, a sufficiently large amount of slurry can be suitably supplied to the entire polishing section.
[0034]
  In FIG.Polished surface 14aIn order to supply a liquid polishing agent (slurry) to a polishing portion where the wafer 10 comes into contact with and polishes the wafer 10, the slurry fed by pressure is supplied from an abrasive supply hole 14 b provided in the upper surface plate 14. An abrasive supply means for discharging is shown.
  85a is a pressure supply device that pumps the slurry, and includes a tank that stores the slurry, a pump that pumps the slurry, and the like.
  Reference numeral 87 denotes a communication path, and an upper and lower pipe 87a that is arranged in the vertical direction on the axial center of the hollow rotation shaft 38a that rotates the upper surface plate 14 and communicates with the pressure feeding device 85a, and an abrasive that branches off from the upper and lower pipe 87a. A branch pipe 87b communicating with the supply hole 14b, a pipe joint, and the like are included. Through this communication path 87, the slurry pressurized to a high pressure is sent and discharged from the abrasive supply hole 14b.
  According to this abrasive supply means, a slurry having a sufficient flow rate can be forcibly and suitably supplied (pumped) to the polishing section, and in particular,Polished surface 14aCool down properly,Polished surface 14aThe surface temperature can be made uniform.
  Of course, the abrasive supply means shown in FIG. 6 and the abrasive supply means shown in FIG. 7 may be used simultaneously.Polished surface 14aThe surface temperature can be made more uniform.
[0035]
Next, as in the embodiment of FIG. 6 and FIG. 7, the operation and effect in the case where a slurry having a sufficient flow rate can be supplied to the polishing unit by pumping the slurry will be described based on comparative experiments.
When supplying 0.5 liters of slurry per minute to the polishing unit and when supplying 3.0 liters of slurry per minute to the polishing unit, each wafer polishing process is 60 minutes, The polishing process (300 minutes in total) was continuously performed. The conditions other than the slurry flow rate are the same.
8 measurement points are set at different positions in the radial direction of the surface (polishing surface) of the lower surface plate 16, and the surface temperature of each measurement point is set every 60 minutes including the time of starting the polishing process (0 minutes). Measured. And it compared about the average value of the surface temperature at the time of the measurement of each time, and the variation in the surface temperature between each measurement point in each time of the measurement.
In addition, for each wafer processed in each polishing process, eight measurement points are set at different positions in the radial direction of the wafer, and the thickness of each measurement point is measured to determine the thickness of the wafer. Comparison was made for variation.
[0036]
The experimental results will be described below.
First, the surface temperature of the lower surface plate 16 will be described.
When supplying 0.5 liters per minute, the average temperature was about 22 degrees Celsius at the start of polishing (0 minutes), but rose to about 34 degrees Celsius when 300 minutes passed. About 12 degrees centigrade occurred in Celsius. In addition, the maximum variation in temperature between each measurement point at each measurement time was about 5 degrees Celsius, and the average was about 3 degrees Celsius.
On the other hand, when 3.0 liters per minute is supplied, the average temperature is about 28 degrees Celsius throughout the entire measurement (difference within 1 degree), and each measurement is performed at each measurement. The maximum temperature variation between the points was about 1.5 degrees Celsius and 1 degree or less on average.
[0037]
Next, the thickness variation of the polished wafer will be described.
When 0.5 liter per minute was supplied, the maximum variation was 2.2 μm and the average was 1.3 μm.
On the other hand, when 3.0 liters per minute was supplied, the maximum variation was 0.8 μm and the average was 0.6 μm. That is, it was possible to obtain a polishing accuracy more than double that of 0.5 liters per minute.
As described above, when 3.0 liters per minute was supplied, the polishing surface could be maintained at a uniform temperature, and the wafer could be planarized with extremely high accuracy.
That is, by increasing the supply amount of the slurry, it is possible to prevent the surface temperature of the polishing surfaces 14a and 16a (the temperature of the polishing cloth surface) of each of the surface plates 14 and 16 from increasing and the surface temperature of the polishing surfaces 14a and 16a. The variation in the size can be reduced. Thus, by maintaining the polishing conditions relating to the surface temperatures of the polishing surfaces 14a and 16a to be uniform, the polishing accuracy of the wafer can be significantly improved.
[0038]
Next, based on FIG.8 and FIG.9, the abrasive | polishing agent supply means provided with the supply path | route of several lines of slurry is demonstrated. In both of the embodiments, the abrasive supply holes 14b are provided at a plurality of different positions in the radial direction of the upper surface plate 14, and the slurry supply holes 14b correspond to the plurality of abrasive supply holes 14b. Are provided in multiple systems.
In the embodiment of FIG. 8, a plurality of supply passages 98a, 98b, and 98c constituted by a plurality of pressure supply devices 88a, 88b, and 88c, a distributor 89 provided on the rotation shaft, and a pipe line passing through the rotation shaft. Then, the slurry is discharged from each abrasive supply hole 14b. The distributor 89 is a well-known technique that supplies a sealed fluid in a rotating member.
Reference numeral 97 denotes a sequencer, which receives signals from temperature sensors 99a, 99b, 99c disposed in the vicinity of the respective abrasive supply holes 14b, and sends command signals to the plurality of pressure supply devices 88a, 88b, 88c. As a result, feedback control is performed on the flow rate of the slurry flowing through the supply paths 98a, 98b and 98c and discharged from the abrasive supply holes 14b, and the polishing surfaces 14a and 16a are cooled to keep the surface temperature constant. To maintain.
[0039]
That is, each of the pressure supply devices 88a, 88b, and 88c is provided with a tank that adjusts the temperature of the slurry and a pump that can vary the flow rate of the slurry to be pressure-fed.
Therefore, by controlling each of the pressure supply devices 88a, 88b, 88c with the sequencer 97, the amount of slurry supplied to the abrasive supply holes 14b in the vicinity of the portion where the polishing heat of the polishing surfaces 14a, 16a is generated a lot. Or a low temperature slurry can be supplied. Thereby, it can cool suitably according to the heating condition of each site | part of polishing surface 14a, 16a, the surface temperature can be equalized over the whole surface, and the grinding | polishing precision of a wafer can be improved significantly.
[0040]
Further, in the present embodiment of FIG. 9, a plurality of supply paths that are branched from the pressure supply device 88d and configured by a plurality of automatic flow control valves 83a, 83b, 83c, a distributor 89, and a pipe line passing through the rotation shaft. Slurry is discharged from each abrasive supply hole 14b through 98a, 98b, and 98c.
A sequencer 97 receives signals from temperature sensors 99a, 99b, and 99c disposed in the vicinity of each abrasive supply hole 14b, and sends command signals to the plurality of automatic flow control valves 83a, 83b, and 83c. . Thereby, the flow rate of the slurry flowing through the supply paths 98a, 98b, 98c and discharged from the abrasive supply holes 14b is controlled by the plurality of automatic flow control valves 83a, 83b, 83c, and the polishing surface 14a, 16a is cooled to keep its surface temperature constant.
[0041]
Thus, by controlling each automatic flow control valve 83a, 83b, 83c with the sequencer 97, the slurry supply hole 14b in the vicinity of the site where a large amount of polishing heat is generated on the polishing surfaces 14a, 16a is transferred to the slurry. If the supply amount is increased, it can be suitably cooled according to the heating condition of each part of the polishing surfaces 14a and 16a, and the surface temperature can be made uniform over the entire surface. Therefore, the polishing accuracy of the wafer can be remarkably improved.
It should be noted that the exchange of signals between the sequencer 97, the temperature sensor, the pressure supply device, or the automatic flow control valve may be performed by wiring as in the present embodiment or may be performed wirelessly. .
Moreover, the pressure for pumping the slurry is 2 to 3 kg / cm.²However, the pressure may be further increased.
In the above embodiment, the case where a plurality of slurry supply paths are provided on the upper platen 14 has been described. However, the present invention is not limited to this, and the lower platen 16 may be provided.
[0042]
Next, an example of how to use the double-side polishing apparatus according to the present invention will be described.
First, the case where the upper surface plate 14 and the lower surface plate 16 are rotated in the opposite direction with the same absolute value of the rotation speed without moving the carrier 12 will be described. That is, as shown in FIG. 1, for example, the upper surface plate 14 rotates clockwise and the lower surface plate 16 rotates counterclockwise. In this case, since frictional force acts in exactly the opposite direction, the kinetic forces cancel each other, and theoretically, both surfaces are polished while the wafer 10 is stopped. In this case, however, the peripheral speed of the upper surface plate 14 and the lower surface plate 16 increases toward the outer periphery. Accordingly, polishing is promoted at a portion farther from the portion corresponding to the axis L of the upper surface plate 14 and the lower surface plate 16 of the wafer 10, and the wafer 10 is not uniformly polished.
[0043]
Next, the polishing action by causing the carrier 12 to perform a circular motion that does not rotate by the motion mechanism having the above-described configuration will be described.
If only the circular motion of the carrier 12 that does not rotate without considering the rotation of the upper surface plate 14 and the lower surface plate 16 is considered, the circular motion that does not rotate is completely different at all points of the moving member (carrier 12). The same exercise will be done. This is a kind of oscillating motion in the sense that all the points have the same motion, and it can be considered that the locus of the oscillating motion is a circle.
Therefore, if the wafer 10 is swung through the carrier 12 that does not rotate and moves in a circular motion, both surfaces of the wafer 10 are uniformly polished if the action is limited to this motion.
[0044]
When the rotational motion of the upper surface plate 14 and the lower surface plate 16 and the circular motion of the carrier 12 that does not rotate simultaneously are operated simultaneously, the wafer 10 is held rotatably in the through hole 12a. When the absolute values of the rotational speeds of the upper surface plate 14 and the lower surface plate 16 are different (when the rotational speed of the other surface plate is increased with respect to one surface plate), the wafer 10 has a higher rotational speed. Rotate in the direction of rotation of the side platen. That is, the wafer 10 rotates in a predetermined direction.
As the wafer 10 rotates in this way, the peripheral speed of the upper surface plate 14 and the lower surface plate 16 increases toward the outer periphery, but the influence can be eliminated and the wafer 10 is uniformly polished. it can.
In addition, in order to polish both surfaces of the wafer 10 uniformly, the rotational speeds of the upper surface plate 14 and the lower surface plate 16 may be controlled so that one of them alternately increases.
[0045]
Next, another example of how to use the double-side polishing apparatus according to the present invention will be described.
In the above embodiment, a case where a plurality of through holes 12a are provided and a plurality of workpieces (wafers 10) are simultaneously polished has been described. However, the present invention is not limited to this. For example, the carrier 12 has a large workpiece. Only one through hole 12a to be held can be provided and used as a polishing apparatus for polishing both surfaces of the large workpiece. In addition, as a large sized workpiece | work, there exists a workpiece | work, such as a rectangular glass plate used for a liquid crystal, or a wafer (circular shape) processed with a sheet.
In this case, the large workpiece is disposed almost entirely from the center of the carrier 12 to the vicinity of the periphery thereof. At this time, if polishing is performed mainly using circular motion that does not rotate by the carrier 12, and the rotational speeds of the upper surface plate 14 and the lower surface plate 16 are made slow enough to prevent uneven polishing, the entire surface of the workpiece is uniform. And it can grind suitably. That is, in the upper surface plate 14 and the lower surface plate 16, the polishing action increases toward the outer periphery due to the difference in peripheral speed, but if the rotational speed is very slow compared to the circular motion of the carrier 12 that does not rotate, the polishing action is directly affected. Can be hardly involved. Then, rotating the upper surface plate 14 and the lower surface plate 16 constantly updates the surface plate surface in contact with the workpiece, and in order to improve the polishing action, such as supplying a liquid abrasive to the entire surface of the workpiece on average. It can contribute indirectly and favorably.
[0046]
Although the polishing apparatus has been described in the above embodiment, it is needless to say that the present invention can be suitably applied to a wrapping apparatus.
As described above, the present invention has been variously described with reference to preferred embodiments. However, the present invention is not limited to these embodiments, and it is needless to say that many modifications can be made without departing from the spirit of the invention. That is.
[0047]
【The invention's effect】
According to the double-side polishing apparatus of the present invention, the upper surface plate and the lower surface plate are brought into contact with the polishing surfaces of the upper surface plate and the lower surface plate by the polishing agent supply means so that the liquid polishing agent is supplied to the polishing portion for polishing the work. The liquid abrasive that has been pumped is discharged from the abrasive supply hole provided in the plate and / or the lower surface plate.
According to this, in a double-side polishing apparatus provided with a carrier that moves in a circular motion that does not rotate, it becomes possible to supply a liquid abrasive at a sufficient flow rate to the polishing section, and the surface temperature of the polishing surface is made uniform. Since it can be maintained, the polishing accuracy can be improved.
[Brief description of the drawings]
FIG. 1 is an exploded perspective view of an embodiment of a double-side polishing apparatus according to the present invention.
FIG. 2 is a side sectional view of the embodiment of FIG.
FIGS. 3A and 3B are a plan view and a cross-sectional view showing the entire carrier and carrier holder of the embodiment of FIG.
FIG. 4 is a cross-sectional view for explaining a main part of the connecting means according to the present invention.
FIGS. 5A and 5B are a plan view and a sectional view showing another embodiment of the connecting means according to the present invention. FIGS.
FIG. 6 is a cross-sectional view for explaining one embodiment of an abrasive supply means according to the present invention.
FIG. 7 is a cross-sectional view for explaining another embodiment of the abrasive supply means according to the present invention.
FIG. 8 is an explanatory view for explaining an embodiment of an abrasive supply means having a plurality of paths.
FIG. 9 is an explanatory view for explaining another embodiment of an abrasive supply means having a plurality of paths.
FIG. 10 is a cross-sectional view illustrating a polishing agent supply unit of the background art.
FIG. 11 is a cross-sectional view illustrating a conventional technique.
FIG. 12 is a plan view for explaining the arrangement of carriers according to the prior art.
[Explanation of symbols]
10 wafers
12 Carrier
12a through hole
12b hole
14 Top plate
14a Polished surface
14b Abrasive supply hole
15 communication hole
16 Lower surface plate
16a Polished surface
20 Carrier turning mechanism
22 Carrier holder
23 pins
24 Crank member
24a Holder side shaft
24b Base side shaft
28 Timing Chain
30 substrate
32 motor
40 Upper platen lifting device
85 Pressure feed means
85a Pressure feeding means
86 communication path
87 Communication passage
88a, 88b, 88c Pressure feeding means
88d Pressure supply means
89 Distributor
97 Sequencer
98a, 98b, 98c Supply path
99a, 99b, 99c Temperature sensor

Claims (3)

A double-side polishing apparatus that polishes both surfaces of a workpiece disposed in a through hole of a carrier sandwiched between an upper surface plate and a lower surface plate by each polishing surface of the upper surface plate and the lower surface plate. ,
A carrier swivel movement mechanism that performs a circular movement that does not rotate the carrier so as to swivel the workpiece ;
Upper and lower pipes for supplying an abrasive provided in a hollow rotary shaft for rotating the upper surface plate in a predetermined direction;
A temperature sensor provided in the vicinity of each of a plurality of abrasive supply holes formed in the upper surface plate;
A branch pipe that is provided on the upper surface of the upper surface plate and supplies the abrasive supplied by the upper and lower pipes to each of the abrasive supply holes;
The temperature sensor output signal is inputted, and a command signal is sent to a flow rate changing mechanism for changing the flow rate of the abrasive supplied to each of the abrasive supply holes, so that the temperature of the polishing surface is made uniform. A double-side polishing apparatus comprising a sequencer for controlling the flow rate of the agent. The pressure supply mechanism includes a tank for storing an abrasive and a pump for pumping the abrasive, and the pressure supply is connected to each of the branch pipes via a distributor. Double-side polishing equipment. The double-side polishing apparatus according to claim 1, wherein the flow rate changing mechanism is an automatic flow rate control valve provided in each of the branch pipes.

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