Method for manufacturing carrier plate for double-side polishing device, double-side polishing method for workpiece, and carrier plate for double-side polishing device

Abstract

This method for manufacturing a carrier plate for a double-side polishing device includes a thickness adjustment step for polishing the carrier plate for a double-side polishing device, before a holding-hole for holding a workpiece is formed therein, to adjust the thickness of the carrier plate to a prescribed thickness. In this double-side polishing method for a workpiece, double-side polishing of the workpiece is performed using a carrier plate that has been subjected to a holding-hole formation step after a thickness adjustment step. In this carrier plate for a double-side polishing device, at least one holding-hole for holding a workpiece is formed and the thickness of the carrier plate is roughly constant across the entire surface.

Description

Method for manufacturing carrier plate for double-sided polishing apparatus, method for polishing double-sided workpiece, and carrier plate for double-sided polishing apparatus

[0001] The present invention relates to a method for manufacturing a carrier plate for a double-sided polishing apparatus, a method for polishing both sides of a workpiece, and a carrier plate for a double-sided polishing apparatus.

[0002] For example, when polishing both sides of a workpiece such as a semiconductor wafer, it is common to polish the workpiece until it and the carrier plate have approximately the same thickness (fixed-size polishing) in order to control the amount of roll-off of the workpiece caused by the viscoelasticity of the polishing pad and the polishing action of the polishing slurry.

[0003] In fixed-size polishing, the accuracy of the thickness of the carrier plate used for double-sided polishing is an important factor in determining the flatness of the workpiece after double-sided polishing, so the thickness of the carrier plate used for double-sided polishing is adjusted by polishing it (for example, Patent Document 1).

[0004] Japanese Patent Application Laid-Open No. 2018-101696

[0005] However, it has been found that even when a carrier plate with adjusted thickness is used, the outer periphery of the workpiece after double-side polishing may roll off from the desired state, such as a fixed size state.

[0006] An object of the present invention is to provide a method for manufacturing a carrier plate for a double-sided polishing apparatus, a method for polishing a workpiece on both sides, and a carrier plate for a double-sided polishing apparatus, which are capable of accurately controlling the shape of the workpiece after double-sided polishing.

[0007] The present inventors conducted extensive research to determine the cause of the fact that even when a carrier plate with an adjusted thickness is used, the workpiece after double-side polishing may roll off from a desired state such as a fixed size state. As a result, it was found that when the carrier plate is polished to adjust its thickness, roll-off due to polishing occurs in the peripheral areas of the holding holes that hold the workpiece, and when double-side polishing of the workpiece is performed using a carrier plate in which this roll-off has occurred, the result of double-side polishing of the workpiece does not result in a desired state such as fixed size polishing, and the workpiece after double-side polishing rolls off from a desired state.

[0008] The present invention was made based on the above findings, and its main features are as follows: (1) A method for manufacturing a carrier plate for a double-sided polishing apparatus, comprising a thickness adjustment step of polishing a carrier plate for a double-sided polishing apparatus before forming holding holes for holding workpieces, and adjusting the carrier plate to a predetermined thickness.

[0009] (2) A method for manufacturing a carrier plate for a double-sided polishing apparatus described in (1), further comprising a holding hole forming process for forming one or more holding holes for holding the workpiece in the carrier plate having the thickness adjusted by the thickness adjustment process.

[0010] (3) The method for manufacturing a carrier plate for a double-side polishing apparatus according to (1) or (2), wherein the carrier plate is made of resin.

[0011] (4) A method for polishing both sides of a workpiece, characterized in that a thickness adjustment process is performed in which a carrier plate for a double-sided polishing apparatus is polished and adjusted to a predetermined thickness before forming holding holes for holding the workpiece, and then a holding hole forming process is performed in which one or more holding holes for holding the workpiece are formed in the carrier plate having the thickness adjusted by the thickness adjustment process, and after the thickness adjustment process, double-sided polishing of the workpiece is performed using the carrier plate that has been subjected to the holding hole forming process.

[0012] (5) The method for polishing both sides of a workpiece according to (4), wherein the carrier plate is made of resin.

[0013] (6) A carrier plate for a double-side polishing apparatus, characterized in that one or more holding holes for holding a workpiece are formed and the thickness is substantially constant over the entire surface.

[0014] According to the present invention, it is possible to provide a method for manufacturing a carrier plate for a double-sided polishing apparatus, a method for polishing a workpiece on both sides, and a carrier plate for a double-sided polishing apparatus, which can accurately control the shape of the workpiece after double-sided polishing.

[0015] FIG. 1 is a conventional flow diagram from preparation of a carrier plate to double-sided polishing of a workpiece. FIG. 2 is a flow diagram from preparation of a carrier plate to double-sided polishing of a workpiece according to the present disclosure. FIG. 3 is a diagram showing an example of a workpiece double-sided polishing device used for a workpiece double-sided polishing method and carrier plate thickness adjustment according to an embodiment of the present invention. FIG. 4 is a diagram showing the shape of a carrier plate after thickness adjustment. FIG. 5 is a diagram showing the relationship between the distance from the outer periphery of a holding hole and the thickness of a carrier plate. FIG. 6 is a diagram showing the outer periphery shape of a silicon wafer after polishing. FIG. 7 is a diagram showing the measurement results of ESFQR_Max (Length 30 mm, outer periphery exclusion region 1 mm) of a silicon wafer after polishing.

[0016] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0017] 1A is a flow diagram showing a conventional process from preparing a carrier plate to polishing both sides of a workpiece. As shown in FIG. 1A, the conventional process involves preparing a carrier plate 100 for a double-sided polishing apparatus, forming one or more holding holes 101 for holding a workpiece in the carrier plate 100, and then polishing the carrier plate 100 for the double-sided polishing apparatus after forming the holding holes 101 for holding the workpiece. Then, double-sided polishing of a workpiece (wafer) is performed using the carrier plate 100 for the double-sided polishing apparatus (in which the holding holes 101 have been formed and polished).

[0018] <Method for manufacturing a carrier plate for a double-sided polishing apparatus> Fig. 1B is a flow diagram from preparation of a carrier plate to double-sided polishing of workpieces in the present disclosure. In a method for manufacturing a carrier plate for a double-sided polishing apparatus according to one embodiment of the present invention, as shown in Fig. 1B, first, a carrier plate for a double-sided polishing apparatus (hereinafter also simply referred to as carrier plate) 10 is prepared. In consideration of ease of processing, the carrier plate 10 is preferably made of resin.

[0019] Next, the carrier plate 10 is polished to a predetermined thickness before the formation of the holding holes 11 for holding the workpieces (wafers in this example) (thickness adjustment step). This thickness adjustment step will be described below by way of example. Figure 2 is a diagram showing an example of a workpiece double-side polishing method according to one embodiment of the present invention and a workpiece double-side polishing device used for adjusting the thickness of the carrier plate.

[0020] 2, this double-sided polishing apparatus 1 includes a rotating platen 4 having an upper platen 2 and an opposing lower platen 3, a sun gear 5 provided at the rotation center of the rotating platen 4, and an internal gear 6 provided in an annular shape on the outer periphery of the rotating platen 4. As shown in Fig. 2, polishing pads 7 are affixed to the opposing surfaces of the upper and lower rotating platens 4, i.e., the lower surface side, which is the polishing surface of the upper platen 2, and the upper surface side, which is the polishing surface of the lower platen 3.

[0021] In addition, the double-sided polishing apparatus 1 includes one carrier plate 10 in the illustrated example, which is provided between the upper surface plate 2 and the lower surface plate 3. Although the double-sided polishing apparatus 1 includes only one carrier plate 10 in the illustrated example, it may include multiple carrier plates 10.

[0022] The double-sided polishing machine 1 is a planetary gear type double-sided polishing machine that can cause the carrier plate 10 to perform planetary motion, which includes orbital motion and rotational motion, by rotating the sun gear 5 and the internal gear 6.

[0023] In the thickness adjustment process for adjusting the thickness of the carrier plate 10, the carrier plate 10 is made to perform planetary motion while supplying polishing slurry, and at the same time the upper surface plate 2 and the lower surface plate 3 are rotated relative to the carrier plate 10, thereby sliding the polishing pads 7 attached to the upper and lower rotating surface plates 4 against the carrier plate 10, thereby adjusting the thickness of the carrier plate 10.

[0024] Next, one or more holding holes 11 for holding workpieces are formed in the carrier plate 10 having the thickness adjusted in the thickness adjusting step (holding hole forming step). The holding holes can be formed by any known mechanical grinding process or laser cutting process. The effects of the method for manufacturing a carrier plate for a double-side polishing apparatus according to this embodiment will be described below.

[0025] The method for manufacturing a carrier plate for a double-sided polishing apparatus according to this embodiment includes a thickness adjustment step in which the carrier plate 10 for the double-sided polishing apparatus is polished to a predetermined thickness before the formation of the holding holes 11 for holding workpieces. As described above, if a holding hole formation step is subsequently performed in which one or more holding holes 11 for holding workpieces are formed in the carrier plate 10 having the thickness adjusted in the thickness adjustment step, the holding holes 11 are not formed at the time of the carrier plate thickness adjustment step, and therefore, roll-off near the holding holes 11 does not occur due to polishing of the carrier plate 10. Therefore, double-sided polishing of workpieces can be performed using a carrier plate 10 in which roll-off near the holding holes 11 does not occur, thereby preventing undesired roll-off from occurring in the workpiece after double-sided polishing. As described above, the method for manufacturing a carrier plate for a double-sided polishing apparatus according to this embodiment allows for accurate control of the shape of the workpiece after double-sided polishing.

[0026] <Method for polishing both sides of a workpiece> Next, a method for polishing both sides of a workpiece according to one embodiment of the present invention will be described. The method for polishing both sides of a workpiece according to this embodiment can be performed using, for example, a double-sided polishing machine 1 as shown in FIG.

[0027] When polishing a workpiece, the workpiece is held in the holding holes 11, and both sides of the workpiece held in the holding holes 11 of the carrier plate 10 are slid against the polishing pads 7 attached to the upper and lower rotary surface plates 4, so that both sides of the workpiece can be polished simultaneously. The workpiece can be, for example, a wafer, and in particular, a silicon wafer.

[0028] The double-side polishing method of this embodiment includes a thickness adjustment process in which a carrier plate for a double-side polishing apparatus is polished to a predetermined thickness before the formation of holding holes for holding workpieces. Then, a holding hole forming process is performed in which one or more holding holes 11 for holding workpieces are formed in the carrier plate 10 having the thickness adjusted in the thickness adjustment process. That is, after the thickness adjustment process, double-side polishing of the workpiece is performed using the carrier plate 10 that has undergone the holding hole forming process. According to the double-side polishing method of this embodiment, the holding holes 11 have not yet been formed at the time of the carrier plate thickness adjustment process, so that roll-off does not occur near the holding holes 11 due to polishing of the carrier plate 10. Therefore, double-side polishing of the workpiece can be performed using a carrier plate 10 that does not have roll-off near the holding holes 11, thereby preventing undesired roll-off from occurring in the workpiece after double-side polishing. As described above, the double-side polishing method of this embodiment allows for accurate control of the shape of the workpiece after double-side polishing.

[0029] In the double-side polishing method for a workpiece, the carrier plate is preferably made of resin.

[0030] <Carrier Plate> The carrier plate 10 for a double-side polishing apparatus according to one embodiment of the present invention has one or more holding holes 11 formed therein for holding workpieces. As will be shown in the examples described later, the thickness of the carrier plate is substantially constant over the entire surface.

[0031] In order to confirm the effects of the present invention, the shapes of the carrier plates and the shapes of the silicon wafers after polishing were compared between a conventional example in which the thickness of the carrier plate was adjusted according to the conventional flow shown in Figure 1A and an inventive example in which the thickness of the carrier plate was adjusted according to the flow of the present disclosure shown in Figure 1B. A general resin carrier plate was used, and a general double-side polishing machine was also used.

[0032] A laser displacement meter (manufactured by KYENCE Corporation) model SI-F10 was used as a carrier cross-section measuring device, and WaferSight (manufactured by KLA Corporation) was used to measure the wafer processing results.

[0033] 3 is a diagram showing the shape of the carrier plate after thickness adjustment. As shown in Fig. 3, in the conventional example, roll-off occurred near the retaining hole, but in the inventive example, roll-off did not occur near the retaining hole. In Fig. 3, the horizontal axis represents the distance (mm) when the center of the retaining hole is set to 0, and the vertical axis represents the change in thickness (µm) of the carrier plate when the thickness of the carrier plate at a position 5 mm outside the retaining hole from the outer periphery of the retaining hole is set to 0.

[0034] Figure 4 shows the relationship between the distance from the outer periphery of the retaining hole and the thickness of the carrier plate. As shown in Figure 4, measurements were taken in the 8 direction around the outer periphery of the retaining hole of the carrier plate. As shown in Figure 4, in the conventional example, a steep sagging occurred approximately 1 mm from the outer periphery of the retaining hole of the carrier plate (indicated by "A"), but such sagging did not occur in the inventive example. Furthermore, in the conventional example, a slope occurred toward the retaining hole, and a gentle sagging also occurred approximately 5 mm from the outer periphery of the retaining hole of the carrier plate (indicated by "B"), but such sagging did not occur in the inventive example. The carrier plate of the inventive example had a substantially constant thickness across its entire surface. In Figure 4, the vertical axis represents the change in thickness (μm) of the carrier plate when the thickness of the carrier plate at a position 5 mm outside the retaining hole from the outer periphery of the retaining hole is set to 0.

[0035] 5 is a diagram showing the outer peripheral shape of the silicon wafer after polishing. As shown in Fig. 5, in the conventional example, a steep sagging occurred at the outer peripheral portion of the silicon wafer, but in the example of the present invention, the sagging was smaller.

[0036] 6 is a diagram showing the measurement results of ESFQR_Max (length 30 mm, outer peripheral exclusion region 1 mm) of a silicon wafer after polishing. The measurement results are shown at a vertical axis length of 30 mm and a position 1 mm from the outer periphery. As shown in FIG. 6, it can be seen that the flatness of the outer periphery of the silicon wafer in the invention example is improved compared to the conventional example.

[0037] (Contribution to SDGs) Conventionally, when adjusting the thickness of a carrier plate, holding holes were formed, and dummy members (dummy wafers) were filled into the holding holes and double-sided polishing was performed. In order to precisely adjust the thickness of the carrier plate, strict control of the thickness of the dummy members was also required, resulting in frequent replacement of the dummy members. According to the present disclosure, when adjusting the thickness of the carrier plate, holding holes are not formed, and therefore dummy members are not required. In this way, according to the present disclosure, the use of dummy members is eliminated, contributing to reducing environmental impact.

[0038] 1: double-sided polishing machine, 2: upper surface plate, 3: lower surface plate, 4: rotating surface plate, 5: sun gear, 6: internal gear, 7: polishing pad, 10: carrier plate for double-sided polishing machine, 11: holding hole, 100: carrier plate for double-sided polishing machine, 101: holding hole

Claims

1. A method for manufacturing a carrier plate for a double-sided polishing device, characterized by including a thickness adjustment process in which a carrier plate for a double-sided polishing device is polished and adjusted to a predetermined thickness before forming holding holes for holding workpieces.

2. A method for manufacturing a carrier plate for a double-sided polishing apparatus as described in claim 1, further comprising a holding hole forming process for forming one or more holding holes for holding the workpiece in the carrier plate having the thickness adjusted by the thickness adjustment process.

3. The method for manufacturing a carrier plate for a double-sided polishing apparatus according to claim 1 or 2, wherein the carrier plate is made of resin.

4. A method for polishing both sides of a workpiece, comprising: a thickness adjustment process in which a carrier plate for a double-sided polishing apparatus is polished and adjusted to a predetermined thickness before forming holding holes for holding the workpiece; and a holding hole forming process in which one or more holding holes for holding the workpiece are formed in the carrier plate having the thickness adjusted by the thickness adjustment process; and after the thickness adjustment process, double-sided polishing of the workpiece is performed using the carrier plate that has been subjected to the holding hole forming process.

5. A method for polishing both sides of a workpiece as described in claim 4, wherein the carrier plate is made of resin.

6. A carrier plate for a double-sided polishing apparatus, characterized in that it has one or more holding holes for holding workpieces and has a substantially constant thickness over its entire surface.

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