TW201944479A - Double-side polishing apparatus for a workpiece - Google Patents

Abstract

The present invention provides a double-side polishing apparatus for a workpiece, which is capable of performing double-side polishing of a wafer while measuring the thickness of the workpiece with high precision for a longer period of time than conventional techniques. In the double-side polishing apparatus 1 of the present invention, the upper fixed plate 2 or the lower fixed plate is provided with one or more through holes 10 penetrating from the upper surface of the upper fixed plate 2 or the lower fixed plate to the lower surface. A hole 11 is provided on the polishing pad 7 at a position corresponding to the through hole 10. The double-side polishing apparatus 1 further includes a workpiece thickness measuring device that measures the thickness of the workpiece W in the double-side polishing of the workpiece W. Each of the one or more through holes 10 is inserted into the solid window member 13, and the window member 13 is composed of a tubular portion 14 and a flange portion 15 having a diameter larger than the diameter of the through hole 10. The side surface 14a of the tubular portion 14 is provided with an annular recessed portion 14b. When the annular recessed portion 14b is placed with an O-ring 16, the tubular portion 14 is inserted into the through-hole 10 from the side of the polishing pad 7.

Description

Grinding device for both sides of workpiece

The present invention relates to a two-side grinding device for a workpiece.

A typical example of a workpiece that provides polishing, that is, in the manufacture of semiconductor wafers such as silicon wafers, in order to obtain higher precision wafer flatness quality or surface roughness quality, two sides of the surface are usually polished at the same time. step.

Especially in recent years, due to the miniaturization of semiconductor elements and the increase in the diameter of semiconductor wafers, the flatness of semiconductor wafers during exposure has been gradually demanded. Under such a background, polishing is terminated at an appropriate time. very important.

Under such a background, Patent Document 1 describes a double-sided polishing device 100. As shown in FIG. 1, the upper platen 91 (or lower platen) is provided with a through hole 92, and can be passed through from a measurement mechanism (not shown). The hole 92 immediately measures the thickness of the wafer W during polishing.

In the above-mentioned two-side polishing apparatus 100, a polishing pad 94 having a hole 93 having a diameter d3 larger than the diameter d1 of the through hole 92 at a position corresponding to the through hole 92 is provided on the polishing surface of the upper and lower plate; The diameter d1 of 92 is larger than the diameter d2 of the hole 93 of the polishing cloth 94, and the window material 95 has a thickness smaller than that of the polishing cloth 94. The window material 95 is fixed to the upper platen 91 (or lower platen) by the adhesive layer 96.

Prior art document Patent document 1: Japanese Patent No. 4654275

However, in the double-sided polishing device 100 of Patent Document 1, the abrasive layer splashes and contacts the adhesive layer 96 during polishing, and the adhesive layer 96 is dissolved in the abrasive material, and the abrasive material may flow into the through hole 92. If the abrasive material flows into the through-hole 92, the upper surface of the window material 95 will be fogged and the accuracy of the thickness measurement of the wafer W will deteriorate. As described above, since the abrasive flows into the through hole 92, it is difficult to perform polishing on both sides of the wafer W while measuring the thickness of the wafer W with high accuracy for a long period of time.

The present invention is intended to solve the above-mentioned problems, and an object thereof is to provide a double-sided grinding device for a workpiece, capable of grinding both sides of the workpiece while measuring the thickness of the workpiece with high accuracy for a long period of time.

In order to solve the above-mentioned problems, the gist architecture of the present invention is as follows. [1] A two-side grinding device for a workpiece, comprising: a rotating platen having an upper platen and a lower platen; a sun gear provided at a center portion of the rotating platen; an internal gear provided at an outer peripheral portion of the rotating platen; A carrying plate is provided between the upper platen and the lower platen, and is provided with one or more holding holes for holding a workpiece, wherein the upper platen or the lower platen is provided with an upper plate from the upper platen or the lower platen. One or more through holes penetrating the surface to the lower surface, and a hole is provided on the polishing pad at a position corresponding to the through hole. The two-sided polishing device further includes a workpiece thickness measuring device, which can penetrate through the two-sided polishing of the workpiece. The one or more through-holes and holes are used to measure the thickness of the workpiece. Each of the one or more through-holes is inserted into a solid window material. The window material is formed by a cylinder portion and a diameter larger than the through-hole. The cylindrical portion is provided with a ring-shaped concave portion on the side surface. The cylindrical portion is inserted into the through hole from the polishing pad side when the ring-shaped concave portion is configured with an O-ring.

[2] In the double-sided grinding device described in [1], the cylindrical portion has a protrusion longer than the thickness of the upper plate or the lower plate and protruding from the through hole, and the protrusion is fixed by a member It is fixed on the upper surface of the upper platen or the lower surface of the lower platen.

[3] In the double-sided grinding device described in [1] or [2], the bottom of the side wall of the upper plate that defines the through hole or the bottom wall of the lower plate that defines the through hole A recess is provided at the top, and a flange portion of the window material is fitted into the recess.

[4] In the double-sided polishing device described in any one of [1] to [3], the polishing pad covers an outer peripheral portion of the flange portion.

According to the present invention, it is possible to perform both-side grinding of a workpiece while measuring the thickness of the workpiece with high accuracy for a long period of time.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. Fig. 2 shows an example of a double-side polishing apparatus for a workpiece according to the present invention. The double-sided polishing device 1 shown in this figure includes a rotary fixed plate 4, a sun gear 5, and an internal gear 6. The rotary platen 4 includes an upper platen 2 and a lower platen 3 facing the upper platen 2. The sun gear 5 is provided at a center of rotation of the rotary fixed plate 4. The internal gear 6 is provided in an annular shape on the outer peripheral portion of the rotary platen 4. As shown in FIG. 2, the facing surfaces of the upper and lower rotating platens 4, that is, the lower surface (abrading surface) of the upper platen 2 and the upper surface (abrading surface) of the lower platen 3 are each attached with a polishing pad 7.

As shown in FIG. 2, this device 1 includes a load plate 9 disposed between the upper platen 2 and the lower platen 3. This load plate 9 includes one or more holding holes 8 for holding a workpiece W. In addition, in the example shown in the figure, the device 1 has only the carrier plate 9, but may also have a plurality of carrier plates 9. In the example shown in the figure, a workpiece (wafer in this embodiment) is held in the holding hole 8.

Here, this device 1 can rotate the sun gear 5 and the internal gear 6 to make the carrier plate 9 revolve and rotate in a planetary motion. That is, while the abrasive particles are being supplied, the carrier plate 9 is moved in a planetary manner, and the upper platen 2 and the lower platen 3 are relatively rotated to the carrier plate 9 to thereby cause the polishing pads attached to the upper and lower rotating platens 4 to rotate. 7 and the both sides of the wafer W held by the holding holes 8 held on the carrier plate 9 are slid, and both sides of the wafer W can be polished at the same time.

As shown in FIG. 2, in the device 1 of this embodiment, the upper platen 2 is provided with one or more through holes 10 penetrating from the upper surface of the upper platen 2 to the lower surface (polished surface). In the example shown in the figure, one through hole 10 is provided at a position near the center of the passing wafer W. In this example, the through-holes 10 are provided in the upper platen 2, but may be provided in the lower platen 3, or one or more through-holes 10 may be provided in any of the upper platen 2 and the lower platen 3. In the example shown in FIG. 2, one through hole 10 is provided, but a plurality of through holes 10 may be provided on the same circumference of the upper platen 2. Here, as shown in FIG. 2, the polishing pad 7 attached to the upper platen 2 may be penetrated through the hole 11 at a position corresponding to the through hole 10 so as to penetrate from the upper surface of the upper platen 2 to the polishing pad. 7 State of the lower surface.

In addition, a workpiece thickness measuring device 12 is provided above this through hole 10, and during polishing of both sides of the wafer W, the thickness of the wafer W can be measured immediately through the through hole 10 and the hole 11. The workpiece thickness measuring device 12 can be, for example, a wavelength-variable infrared laser measuring device. With such a measuring device, the interference between the reflected light on the surface of the wafer W and the reflected light on the inside can be evaluated, and the thickness of the wafer W can be measured.

Then, in the double-sided polishing device 1 of the present invention, each of the through holes 10 is inserted into a solid window material 13. As shown in FIG. 3, this window material 13 is composed of a cylindrical portion 14 and a flange portion 15 having a larger diameter than the diameter of the through hole 10. The cylindrical portion 14 and the flange portion 15 are integrally formed. In addition, an annular recessed portion 14 b is provided on a side surface 14 a of the cylindrical portion 14. In a state where the annular recessed portion 14 b is provided with an O-ring 16, the cylindrical portion 14 is inserted into the through-hole 10 from the polishing pad 7 side, and the O-ring 16 Sealing is performed between the through hole 10 and the cylindrical portion 14. The window material 13 is fixed to the upper platen 2 (or the lower platen 3) by an adhesive layer (for example, double-sided tape) 17.

With such a window material 13, even if the next layer 17 dissolves and the abrasive particles flow into the through hole 10, since the cylindrical portion 14 of the window material 13 is inserted into the through hole 10, the abrasive material must flow into the through hole 10 and the side surface 14a of the cylindrical portion 14 must And rising between the upper set 2 (or lower set 3). However, since the O-ring 16 is disposed in the annular recessed portion 14 b of the cylindrical shape 14, even if the abrasive particles reach the O-ring, they cannot reach the upper surface 14 c of the cylindrical portion 14.

In this way, it is possible to prevent the accuracy of the thickness measurement of the wafer W from being deteriorated due to the inflow of the abrasive particles into the through-hole 10, and it is possible to perform both-side polishing of the workpiece W while measuring the thickness of the workpiece W with high accuracy over a longer period of time than conventional techniques.

In addition, as shown in FIG. 4, the cylindrical portion 14 of the window material 13 may have a protruding portion 14 d which is longer than the upper plate 2 (or the lower plate 3) and protrudes from the through hole 10. A fixed member (for example, a nut) 18 is fixed to the upper surface 2 a of the upper platen 2 (the lower surface of the lower platen 3). Accordingly, the window material 13 can be strongly fixed to the upper platen 2 (or the lower platen 3), and the inflow of the abrasive particles into the through hole 10 can be further suppressed. In this case, unlike the window material 13 shown in FIG. 3, the bonding layer 17 is not necessary.

In the double-side polishing apparatus 1 of the present invention, as shown in FIG. 5, it is preferable to provide a recessed portion 2 b at the bottom of the side wall of the upper plate 2 (or the top of the side wall of the lower plate) that defines the through hole 10. With such a structure, if the abrasive particles are to flow into the through-hole 10, it is necessary to pass between the side surface 15a of the flange 15 and the side wall dividing the recessed portion 2b compared to the structure shown in FIG. Inflow. In particular, the depth of the recessed portion 2b of the upper platen 2 is equal to the thickness of the flange portion 15 plus the thickness of the adhesive layer 17, the lower surface 15b of the flange portion 15 and the lower surface 2c of the upper platen 2 (or the lower platen) The upper surface of 3) is preferably arranged on the same plane. Thereby, the window material 13 is arrange | positioned more stably, and both surfaces can be polished favorably.

As shown in FIG. 6, the polishing pad 7 preferably covers the outer peripheral portion 15 c of the flange portion 15. Therefore, in order for the abrasive particles to flow into the through-hole 10, compared with the structure shown in FIG. It is possible to further suppress the inflow of abrasive particles.
[Example]

Described (conventional Example 1) shown in FIG polishing both surfaces of the first device 100 in Patent Document 1, the silicon wafer measurement ^- thickness (diameter:: 300mm, conductivity type P, P ⁺⁺⁾ of. Specifically, the upper platen 2 separates the wafer W and is disposed above, and the wafer thickness measuring device 12 is disposed at a position about 1 m from the surface of the silicon wafer.

Near-infrared light (wavelength: 1310 nm) is irradiated to the surface of the silicon wafer W from the wafer thickness measuring device 12, and the reflection intensity caused by interference of the reflected light from the surface of the silicon wafer W and the inside reflected light passes through the silicon wafer. The interference fringe period obtained from the optical path difference information of the thickness of W is subjected to a fast Fourier transform (FFT) to calculate the thickness of the silicon wafer W. At this time, the thickness is measured at about 10,000 locations in the central portion of the silicon wafer W. As the window material 13, a material immediately after processing (that is, service life = 0 minutes) is used. The calculated thickness is shown in Table 1.

[Table 1]

(Conventional Example 2) In the same manner as in Conventional Example 1, the thickness of the silicon wafer W was measured. Among them, as the window material 13, a material that has been subjected to double-side grinding for 10,000 minutes (that is, service life = 10,000 minutes) is used. The other conditions are exactly the same as those in the conventional example 1. The results obtained are shown in Table 1.

(Conventional Example 3) The thickness of the silicon wafer W was measured in the same manner as in the conventional example 1. Among them, as the window material 13, a material that has been subjected to double-sided grinding for 40,000 minutes (that is, a service life = 40,000 points) is used. The other conditions are exactly the same as those in the conventional example 1. The results obtained are shown in Table 1.

(Inventive Example 1) As in Conventional Example 1, the thickness of the silicon wafer W was measured. Among them, the double-side polishing apparatus 1 of the present invention shown in FIG. 2 and FIG. 3 is used. The other conditions are exactly the same as those in the conventional example 1. The results obtained are shown in Table 1.

(Inventive Example 2) In the same manner as in Conventional Example 2, the thickness of the silicon wafer W was measured. Among them, the double-side polishing apparatus 1 of the present invention shown in FIG. 2 and FIG. 3 is used. The other conditions are exactly the same as those in the conventional example 2. The results obtained are shown in Table 1.

(Invention Example 3) In the same manner as in Conventional Example 3, the thickness of the silicon wafer W was measured. Among them, the double-side polishing apparatus 1 of the present invention shown in FIG. 2 and FIG. 3 is used. The other conditions are exactly the same as in the conventional example 3. The results obtained are shown in Table 1.

> Evaluation of Wafer Thickness>
As can be seen from Table 1, as compared to the conventional examples 1 to 3, compared with the conventional example 1 with a service life = 0 minutes, the measured value of the wafer thickness also increases with the increase of the polishing time. In Examples 1 to 3, the measured value of the thickness of the wafer hardly changed even when the polishing time was increased compared to the invention example 1 with a service life of 0 minutes. As described above, according to the present invention, it can be understood that both sides of the workpiece can be polished while measuring the thickness of the workpiece with high accuracy over a longer period of time than the conventional technique.
[Possibility of industrial use]

According to the present invention, both sides of the workpiece can be polished while measuring the thickness of the workpiece with high accuracy for a long period of time, and therefore, it is very useful in the semiconductor wafer manufacturing industry.

1‧‧‧ Double-side grinding device

2‧‧‧ Upper Order

2a‧‧‧upper surface

2b‧‧‧ recess

2c‧‧‧ lower surface

3‧‧‧ lower order

4‧‧‧ rotating plate

5‧‧‧ sun gear

6‧‧‧ Internal gear

7‧‧‧ Abrasive pad

8‧‧‧ holding hole

9‧‧‧ bearing plate

10‧‧‧through hole

11‧‧‧hole

12‧‧‧Workpiece thickness measuring device

13‧‧‧Window

14‧‧‧ tube

14a‧‧‧side

14b‧‧‧ annular recess

14c‧‧‧ Top surface

14d‧‧‧ protrusion

15‧‧‧ flange

15a‧‧‧side

15b‧‧‧ lower surface

15c‧‧‧ Peripheral

16‧‧‧O ring

17‧‧‧ Adjacent layer

18‧‧‧Fixed components

W‧‧‧ Workpiece (wafer)

FIG. 1 shows the main parts of a conventional double-sided grinding apparatus for a workpiece.

Fig. 2 shows an example of a double-side polishing apparatus for a workpiece according to the present invention.

FIG. 3 shows the main parts of the double-sided polishing apparatus shown in FIG. 2.

FIG. 4 is a main part of another example of the double-sided polishing apparatus for a workpiece of the present invention.

Fig. 5 is a main part of a preferred example of a double-side polishing apparatus for a workpiece according to the present invention.

Fig. 6 is a main part of another preferred example of the double-sided grinding apparatus for a workpiece according to the present invention.

Claims (5)

A two-sided grinding device includes: Rotating plate with upper plate and lower plate; A sun gear provided at the center of the rotating fixed plate; An internal gear provided on an outer peripheral portion of the rotary fixed plate; The supporting plate is provided between the upper and lower fixing plates, and is provided with one or more holding holes for holding a workpiece, The upper platen or the lower platen is provided with one or more through holes penetrating from the upper surface of the upper platen or the lower platen to the lower surface. The polishing pad is provided with a hole at a position corresponding to the through hole, The double-sided grinding device further includes a workpiece thickness measuring device, which can measure the thickness of the workpiece through the one or more through holes and holes during the double-sided grinding of the workpiece. A solid window material is inserted into each of the one or more through holes, and the window material is composed of a tube portion and a flange portion having a larger diameter than the diameter of the through hole. The side of the tube portion is provided with An annular recessed portion, in which the cylindrical portion is inserted into the through hole from the polishing pad side in a state where an O-ring is arranged. The two-side grinding device according to item 1 of the scope of patent application, wherein the cylindrical portion has a protrusion longer than the thickness of the upper plate or the lower plate and protruding from the through hole, and the protrusion is fixed by a member It is fixed on the upper surface of the upper platen or the lower surface of the lower platen. The two-side polishing device according to item 1 of the scope of patent application, wherein a recess is provided at the bottom of the side wall of the upper plate that defines the through hole, or at the top of the side wall of the lower plate that defines the through hole. The flange portion of the window material is fitted into the concave portion. The two-side polishing device as described in the second item of the patent application scope, wherein a recess is provided at the bottom of the side wall of the upper plate that defines the through hole, or at the top of the side wall of the lower plate that defines the through hole. The flange portion of the window material is fitted into the concave portion. The two-sided polishing device according to any one of claims 1 to 4, wherein the polishing pad covers an outer peripheral portion of the flange portion.