Double-sided grinding device

Abstract

This invention discloses a double-sided polishing apparatus comprising an upper platform and a lower platform. The upper platform has a plurality of through-holes between its rotation center and periphery, and a polishing cloth is provided on the polishing surface of the upper platform opposite the lower platform. The polishing cloth has holes at positions corresponding to the through-holes, each hole having a diameter greater than or equal to the diameter of the through-hole. A hollow resin plug is inserted into each of the through-holes on the upper platform. The upper surface of the hollow plug has a window material, and the hollow plug has a plug through-hole. Furthermore, the double-sided polishing apparatus includes a wafer thickness measuring mechanism at the upper part of the upper platform. This wafer thickness measuring mechanism can optically measure the thickness of the wafer in real time during polishing via the plug through-hole. This provides a double-sided polishing apparatus that exhibits excellent thickness measurement accuracy and eliminates concerns about metal impurities, scratches, and particles.

Description

Technical Field

[0001] This invention relates to a two-sided grinding apparatus having a thickness measuring mechanism for a wafer being processed. Prior Technology

[0002] In the two-sided wafer grinding process, real-time wafer thickness measurement is required in order to minimize the deviation of the processed thickness from the target wafer thickness.

[0003] Figure 8 shows a schematic side view of a previous example of a double-sided grinding apparatus. Figure 9 shows a schematic enlarged cross-sectional view of section IX of the double-sided grinding apparatus shown in Figure 8.

[0004] The two-sided polishing apparatus 10 shown in Figures 8 and 9 is a four-function two-sided polishing apparatus, comprising: an upper platform 2, a lower platform 3, a sun gear 8, and an internal gear 9. Furthermore, an polishing cloth 4A is provided on the polishing surface 2A of the upper platform 2 facing the lower platform 3. An polishing cloth 4B is provided on the surface of the lower platform 3 facing the upper platform 2. Additionally, the two-sided polishing apparatus 10 further includes a wafer thickness measuring mechanism 7 on the upper part of the upper platform 2.

[0005] In a prior art example of a two-sided polishing step using the two-sided polishing apparatus 10 shown in Figures 8 and 9, as shown in Figures 8 and 9, an infrared laser L is irradiated onto the wafer W being polished via the platform through-hole 21 of the upper platform 2 from the wafer thickness measuring mechanism 7, and the thickness is monitored by optical reflection interferometry, while the polishing ends when the wafer W reaches an arbitrary thickness.

[0006] In the double-sided grinding apparatus 10 of the previous example shown in Figures 8 and 9, in order to prevent the slurry from coming into contact with the liquid on the metal part of the platform or from water splashing during high-pressure cleaning, a plastic window material (film) 6 is attached to the lower end of the platform through hole 21 (on the grinding surface 2A side) through an adhesive layer 61.

[0007] Other methods and / or apparatuses for monitoring the thickness of wafer W during grinding have been proposed.

[0008] For example, Patent Document 1 describes an optical measurement method in which the surface of a single-sided grinding device is measured optically, and the surface condition of the object being ground is measured by means of a pin member, which allows the measuring light to pass through the measuring hole and is made of a nearly transparent material.

[0009] Patent document 2 describes a method in which an infrared laser is transmitted through a slurry supply hole on an upper platform to measure the thickness of a wafer during grinding in a double-sided grinding apparatus. The upper platform has a plastic window material installed on the grinding cloth side.

[0010] Patent document 3 describes a measurement method in which a quartz material is used as the sensor holder for the slurry supply hole of the upper platform in a double-sided grinding apparatus, thereby reducing the thickness error caused by the heating of the upper platform during grinding.

[0011] Patent document 4 describes a method in which a laser is irradiated from a slurry supply hole on the upper platform in a double-sided grinding apparatus and the reflected light is detected. The data is corrected by using the correlation between the resistivity and thickness of the wafer, thereby measuring the wafer thickness during grinding with high accuracy.

[0012] Patent document 5 describes a grinding machine in which the shape of the workpiece is measured by a shape measuring device through a measuring hole formed on the upper platform in a double-sided grinding device, and the shape of the workpiece is stored in memory and displayed in chronological order during grinding.

[0013] [Previous Technical Documents] (Patent Documents) Patent Document 1: Japanese Patent Application Publication No. 2002-170800 Patent Document 2: Japanese Patent Application Publication No. 2010-030019 Patent Document 3: Japanese Patent Application Publication No. 2011-134823 Patent Document 4: Japanese Patent Application Publication No. 2017-011099 Patent Document 5: Japanese Patent Application Publication No. 2019-181657 Summary of the Invention

[0014] (The problem the invention aims to solve) In the double-sided grinding apparatus shown in Figures 8 and 9, because there is a window material 6 on the grinding surface 2A side of the upper platform 2, the window material 6 may sometimes be damaged due to contact between the workpiece, i.e., the wafer W, and the window material 6, thus becoming a factor in the occurrence of scratches and / or particles. In terms of thickness measurement accuracy, it may also be affected by the accumulation of scratches and / or dirt in the window material 6 or the deformation of the window material 6 due to pressure from the grinding slurry, resulting in insufficient accuracy.

[0015] Although attaching the window material 6 only to the non-abrasive surface, i.e., the upper surface 2B, can eliminate the above problems, there is a concern about the presence of metal impurities because the platform metal part is in contact with the liquid slurry inside the platform through-hole 21. Furthermore, since the slurry fixed inside the platform through-hole 21 can become a factor in the formation of scratches and / or particles, it needs to be cleaned regularly. However, cleaning the platform through-hole 21 is labor-intensive and time-consuming, which can lead to a deterioration in productivity due to equipment downtime.

[0016] This invention was made to solve the above-mentioned problems, and aims to provide a double-sided grinding device that can demonstrate excellent thickness measurement accuracy and eliminate concerns about metal impurities, scratches and particles.

[0017] (Methods used to solve problems) To solve the above problems, the present invention provides a double-sided grinding apparatus having an upper platform and a lower platform, wherein: In the aforementioned upper platform, a plurality of platform through holes are provided between the rotation center and the periphery, and an abrasive cloth is provided on the abrasive surface of the aforementioned platform facing the aforementioned lower platform; In the aforementioned abrasive cloth, a hole is provided at a position corresponding to the aforementioned plurality of platform through holes, and the hole has a diameter larger than or equal to the diameter of the aforementioned platform through holes; A hollow resin plug is inserted into each of the aforementioned through holes on the aforementioned upper platform. The upper surface of the hollow plug is provided with window material, and the hollow plug has a through hole plug. The aforementioned two-sided grinding apparatus is further equipped with a wafer thickness measuring mechanism on the upper part of the aforementioned upper platform. The wafer thickness measuring mechanism can optically measure the thickness of the aforementioned wafer in real time during grinding through the aforementioned plug through hole.

[0018] In the double-sided grinding apparatus of the present invention, by inserting a hollow resin plug into the through hole of the platform, there is no need to worry about metal contamination even if the platform material is metal. Therefore, it is not necessary to adhere window material to the part in contact with the slurry during the grinding process at the lower end of the upper platform. Furthermore, in the double-sided grinding apparatus of the present invention, the window material is provided on the upper surface of the hollow plug, that is, on the surface opposite to the grinding surface, thus eliminating the risk of window material damage and improving the accuracy of thickness measurement.

[0019] Furthermore, since the hollow plug is easy to disassemble, the grinding device on both sides can continue to operate even during cleaning by replacing the spare plug, thus minimizing the reduction in productivity.

[0020] That is, the double-sided grinding apparatus according to the present invention can demonstrate excellent thickness measurement accuracy and eliminate concerns about metal impurities, scratches and particles.

[0021] For example, the aforementioned wafer thickness measurement mechanism can be equipped with a variable wavelength infrared laser device that can emit laser light at a wavelength that is optically transmitted to the aforementioned wafer.

[0022] As a wafer thickness measurement device, a variable wavelength infrared laser device can be used, but is not limited to this.

[0023] At this point, the aforementioned window material is preferably designed to allow the aforementioned laser light to pass through.

[0024] If the window material is one that allows laser light from a variable wavelength infrared laser device to pass through, the interference caused by the window material on thickness measurement can be reduced, thus improving the accuracy of wafer thickness measurement.

[0025] Furthermore, at this time, the aforementioned through hole of the aforementioned hollow plug is preferably 1.5 mm larger than the diameter of the aforementioned laser beam.

[0026] If the diameter of the through hole of the hollow plug is 1.5 mm or more larger than the diameter of the laser beam used for wafer measurement, the influence of slurry or water droplets adhering to the through hole can be suppressed, and wafer thickness measurement can be performed with high accuracy.

[0027] The aforementioned hollow plug preferably has a flange portion, which is attached to the aforementioned window material, and the outer diameter of the aforementioned flange portion is larger than the diameter of the aforementioned platform through hole of the aforementioned upper platform.

[0028] If a double-sided grinding device with a hollow plug is used, and the hollow plug has such a flange, it can stably maintain the state of the hollow plug being inserted into the platform through hole of the upper platform, and can eliminate the risk of the hollow plug falling onto the grinding surface.

[0029] The aforementioned hollow plug is preferably fixed to the aforementioned platform through hole of the aforementioned upper platform by means of an O-ring made of synthetic rubber.

[0030] This allows the hollow plug to be fixed to the platform through hole by means of an O-ring, which not only stabilizes the hollow plug when it is inserted into the platform through hole of the upper platform, but also effectively prevents the upper platform from coming into contact with the liquid slurry.

[0031] (The benefits of the invention) As described above, the double-sided grinding apparatus according to the present invention can demonstrate excellent thickness measurement accuracy and eliminate concerns about metal impurities, scratches, and particles. Simple Explanation of the Diagram

[0032] Figure 1 is a schematic side view showing an example of the double-sided grinding apparatus of the present invention. Figure 2 is an enlarged schematic cross-sectional view of part II of the double-sided grinding device shown in Figure 1. Figure 3 is a schematic plan view showing the relationship between the through-hole of the hollow plug in the double-sided grinding device shown in Figure 1 and the laser beam. Figure 4 is a graph showing the evolution of wafer thickness during wafer processing in the embodiment. Figure 5 is a graph showing the evolution of wafer thickness during wafer processing in the comparative example. Figure 6 is a graph showing the evolution of thickness during continuous processing of 150 batches in the example. Figure 7 is a graph showing the evolution of thickness during continuous processing of 150 batches in the comparative example. Figure 8 is a schematic side view of an example of a prior art double-sided grinding apparatus. Figure 9 is an enlarged schematic cross-sectional view of the IX section of the double-sided grinding device shown in Figure 8. Implementation

[0033] As mentioned above, there is a requirement to develop a double-sided grinding device that can demonstrate excellent thickness measurement accuracy and eliminate concerns about metal impurities, scratches, and particles.

[0034] Through repeated and in-depth research into the above-mentioned problems, the inventors discovered that a double-sided grinding device with an optical wafer thickness measurement mechanism, having a window material attachment surface on the upper surface, inserting a resin hollow plug with a through hole into each of the through holes of the upper platform, and setting a window material on the upper surface of the hollow plug, can exhibit excellent thickness measurement accuracy and eliminate concerns about metal impurities, scratches, and particles, thus completing the present invention.

[0035] That is, the present invention is a double-sided grinding device having an upper platform and a lower platform, wherein: In the aforementioned upper platform, a plurality of platform through holes are provided between the rotation center and the periphery, and an abrasive cloth is provided on the abrasive surface of the aforementioned platform facing the aforementioned lower platform; In the aforementioned abrasive cloth, a hole is provided at a position corresponding to the aforementioned plurality of platform through holes, and the hole has a diameter larger than or equal to the diameter of the aforementioned platform through holes; A hollow resin plug is inserted into each of the aforementioned through holes on the aforementioned upper platform. The upper surface of the hollow plug is provided with window material, and the hollow plug has a through hole plug. The aforementioned two-sided grinding apparatus is further equipped with a wafer thickness measuring mechanism on the upper part of the aforementioned upper platform. The wafer thickness measuring mechanism can optically measure the thickness of the aforementioned wafer in real time during grinding through the aforementioned plug through hole.

[0036] Hereinafter, the present invention will be described in detail with reference to the drawings, but the present invention is not limited to these embodiments.

[0037] Figure 1 shows a schematic side view of an example of the double-sided polishing apparatus of the present invention. Figure 2 shows a schematic enlarged cross-sectional view of part II of the double-sided polishing apparatus shown in Figure 1.

[0038] The two-sided polishing apparatus 1 shown in Figures 1 and 2 is a two-sided polishing apparatus for a wafer W having an upper platform 2 and a lower platform 3.

[0039] Between the rotation center 22 and the periphery 23 of the upper platform 2, a plurality of platform through holes 21 are provided. The platform through holes 21 extend from the grinding surface 2A to the upper surface 2B through the upper platform 2. Figure 1 shows two platform through holes 21 as representatives, but the number of platform through holes 21 is not limited to two. Furthermore, the position of the platform through holes 21 is not limited to the position shown in Figure 1.

[0040] On the grinding surface 2A of the upper platform 2 facing the lower platform 3, there is a grinding cloth 4A. In the grinding cloth 4A, there is a hole 41 at a position corresponding to the plurality of platform through holes 21 of the upper platform, and the hole 41 has a diameter larger than the diameter of the platform through hole 21.

[0041] In the double-sided grinding apparatus 1, a resin-made hollow plug 5 is inserted into each of the platform through holes 21 of the upper platform 2. As shown in Figure 2, the hollow plug 5 has a window material 6 on its upper surface 52. On the other hand, in this example, as shown in Figure 2, there is no window material on the grinding surface 2A side, that is, the lower surface. Furthermore, the hollow plug 5 has a plug through hole 51.

[0042] The double-sided grinding apparatus 1 further includes a wafer thickness measuring mechanism 7 on the upper platform 2. The wafer thickness measuring mechanism 7 can optically measure the thickness of the wafer W in real time during grinding via a through-hole 51.

[0043] In this double-sided grinding apparatus 1, by inserting a resin hollow plug 5 into the platform through hole 21, there is no need to worry about metal contamination even if the platform material is metal. Therefore, it is not necessary to adhere the window material 6 to the part that comes into contact with the slurry during the grinding process at the lower end of the upper platform 2. Furthermore, in the double-sided grinding apparatus 1, since the window material 6 is placed on the upper surface 52 of the hollow plug 5, that is, the non-grinding surface opposite to the grinding surface 2A, the risk of damage to the window material 6 can be eliminated, and the accuracy of thickness measurement can be improved.

[0044] Furthermore, since the hollow plug 5 is easily removable, the two-sided grinding device 1 can continue to operate during cleaning by exchanging the pre-filled plug, thus minimizing the reduction in productivity.

[0045] That is, the double-sided grinding apparatus 1 according to the present invention can demonstrate excellent thickness measurement accuracy and eliminate concerns about metal impurities, scratches and particles.

[0046] The grinding object of the double-sided grinding apparatus 1 of the present invention, namely the wafer W, is typically a silicon wafer, especially a semiconductor silicon wafer. However, the grinding object of the double-sided grinding apparatus 1 of the present invention, namely the wafer W, is not limited to silicon wafers.

[0047] The double-sided grinding apparatus 1 shown in Figures 1 and 2 will be described in more detail below.

[0048] The example of the two-sided grinding device 1 shown in Figures 1 and 2 is, more specifically, a four-function two-sided grinding device, and has: an upper platform 2, a lower platform 3, a sun gear 8, and an internal gear 9, each with a drive unit.

[0049] Abrasive cloth 4B is provided on the surface of the lower platform 3 facing the upper platform 2.

[0050] The abrasive cloths (abrasive pads) 4A and 4B respectively set on the upper platform 2 and the lower platform 3 can be, for example, commercially available polyurethane foam pads or rigid non-woven fabric pads, but are not limited to these.

[0051] As shown in Figure 2, the hollow plug 5 includes a flange portion 53 and a shaft portion 54 extending from the flange portion 53. The upper surface 52 of the hollow plug 5, which is provided with window material 6, is the upper surface of the flange portion 53. The shaft portion 54 is held within the platform through hole 21.

[0052] As shown in Figure 2, the outer diameter of the flange portion 53 is preferably larger than the diameter of the platform through hole 21 of the upper platform 2. In this way, the flange portion 53 of the hollow plug 5 functions as a stop portion, thus stably maintaining the hollow plug 5 inserted into the platform through hole 21 of the upper platform 2, and eliminating the risk of the hollow plug 5 falling onto the grinding surface.

[0053] In the examples shown in Figures 1 and 2, the hollow plug 5 is fixed to the platform through hole 21 of the upper platform 2 by means of O-rings 55 and 56 made of synthetic rubber. One O-ring 55 is installed in the portion of the shaft 54 ​​of the hollow plug 5 near the flange 53. The other O-ring 56 is installed in the portion of the shaft 54 ​​of the hollow plug 5 near the front end 54A.

[0054] By using O-rings 55 and 56 made of synthetic rubber to fix the hollow plug 5 in the platform through hole 21, it is possible not only to stably maintain the hollow plug 5 inserted into the platform through hole 21 of the upper platform 2, but also to effectively prevent the upper platform 2 from coming into contact with the liquid slurry.

[0055] As shown in Figure 2, the through hole 51 extends from the upper surface 52 to the front end 54A of the shaft portion 54 through the hollow plug 5.

[0056] The wafer thickness measuring mechanism 7 is configured to optically measure the thickness of the wafer W in real time during polishing via a through-hole 51. In the example of Figure 1, the wafer thickness measuring mechanism 7 includes: a light source that irradiates laser light L onto the wafer W during polishing; a light receiving unit that receives reflected light from the wafer W; and a calculation unit that calculates the wafer thickness from the reflected light.

[0057] As a light source, a variable wavelength infrared laser device can be used, which can emit laser light L of a wavelength that is optically transmitted through the wafer, but is not limited to this.

[0058] The window material 6 is attached to the upper surface 52 of the hollow plug 5 through the adhesive layer 61.

[0059] Window material 6 is preferably designed to allow transmission of laser light L from a variable wavelength infrared laser device.

[0060] If the window material 6 is a material that allows laser light L from a variable wavelength infrared laser device to pass through, then the interference caused by the window material 6 to the thickness measurement can be reduced, thus improving the accuracy of the thickness measurement of the wafer W.

[0061] Window material 6, for example, can be a thin film that transmits laser light L.

[0062] As shown in Figure 1, the incident light toward the wafer W and the reflected light from the wafer W (together represented by the laser light L, indicated by the dashed line) pass through the plug through hole 51 of the hollow plug 5 inserted into the platform through hole 21 provided on the upper platform 2.

[0063] Figure 3 is a schematic plan view showing the relationship between the through hole 51 of the plug 5 in the double-sided grinding device 1 and the laser light L when viewed from the top surface 52.

[0064] As shown in Figure 3, the through hole 51 of the hollow plug 5 has a larger diameter than the aperture of the laser beam L.

[0065] For example, if the diameter of the through-hole 51 of the hollow plug 5 is 1.5 mm or more larger than the diameter of the laser beam L used for wafer thickness measurement, the influence of slurry or water droplets adhering to the through-hole 51 can be suppressed, and wafer thickness measurement can be performed with high accuracy. There is no particular upper limit to the diameter of the through-hole 51 of the hollow plug 5 relative to the diameter of the laser beam L used for wafer thickness measurement. For example, the diameter of the through-hole 51 of the hollow plug 5 can be made to be 1.5 mm or more but less than 30 mm larger than the diameter of the laser beam L used for wafer thickness measurement.

[0066] [Example] The present invention will be specifically described below using examples and comparative examples, but the present invention is not limited to these examples.

[0067] (Example) In this embodiment, the two-sided polishing apparatus 1 shown in Figures 1 and 2, configured according to the following conditions, is used to polish the two sides of the wafer W according to the following conditions.

[0068] (Comparative Example) In the comparative example, the two-sided polishing apparatus 10 shown in Figures 8 and 9, configured according to the following conditions, is used to polish the two sides of the wafer W according to the following conditions.

[0069] ◇Common features of the embodiments and comparative examples As wafer W, a P-type silicon single crystal wafer with a diameter of 300mm and a typical resistance of 10Ω is used. The upper platform 2 of the double-sided grinding device has 10 platform through holes 21 with a diameter of 15 mm on the circumference of the fulcrum of the rotation center 22. The abrasive cloths 4A and 4B, respectively located on the upper platform 2 and the lower platform 3, are both made of carbamate foam. The abrasive slurry used contains silica sol particles and has a pH adjusted to the range of 10.0 to 11.0. As the thickness measuring mechanism 7, a variable wavelength infrared laser with a laser aperture of 3mm, a wavelength of 1300mm, and a power of 10mW or more is used. As the window material 6, a disc-shaped film with a diameter of 30 mm is used, which is cut from a TORAY PET (polyethylene terephthalate) film (200 μm thick) with an aperture 15 mm larger than the aperture of the platform through hole 21 of the upper platform 2. The film is attached to the outer periphery of the window material 6 as an adhesive layer 61 with double-sided adhesive tape (Sumitomo 3M442JS3, 110 μm thick) and attached to the upper surface 52 of the hollow plug 5 (Figure 2; Example) or the polished surface 2A of the upper platform 2 (Figure 9; Comparative Example).

[0070] ◇Example A hollow plug 5 made of polyoxymethylene (POM) resin (with a plug through hole 51 diameter of 5mm, a window material 6 attachment surface 52 diameter of 30mm, and a platform insertion part 54 outer diameter of 14.8mm) is inserted into the platform through hole 21 of the upper platform 2 and fixed with O-rings 55 and 56 made of synthetic rubber. The aforementioned window material 6 is attached to the outer periphery of the attachment portion on the upper surface 52 of the hollow plug 5. For the abrasive cloth 4A attached to the upper platform 2, a hole 41 with the same size and diameter of 15mm is made at the same position as the platform through hole 21 of the upper platform 2.

[0071] ◇Comparative Example For the abrasive cloth 4A attached to the upper platform 2, a hole 41 with a diameter of 30mm is made at the same position as the platform through hole 21 of the upper platform 2, which is 15mm larger than the platform through hole 21. As shown in Figure 9, the window material 6 is attached at the location of the hole 41 in the abrasive cloth 4A.

[0072] ◇Wafer thickness measurement results during processing The thickness measurement evolution of five wafers in a batch from the beginning to the end of the grinding process of wafer W is compared. The results are shown in Figures 4 and 5. The grinding rate is calculated from the monitored wafer thickness, and grinding ends when the specified finishing thickness is reached. This grinding rate is updated with each wafer thickness measurement. In other words, the more thickness measurements taken, the closer the rate will be to the actual grinding rate; therefore, a higher number of measurements can be expected to improve the accuracy of the wafer thickness after processing. As shown in Figures 4 and 5, when comparing the thickness measurements in a batch, there are 169 points in the comparative example, compared to 535 points in the embodiment. This is because, in the comparative example, the window material 6 on the grinding surface 2A side of the upper platform 2 has scratches or damage caused by contact with the workpiece, i.e., the wafer W, or is affected by the adhesion of slurry and water droplets, or the accumulation of dirt. In contrast, the embodiment does not have the window material 6 on the grinding surface 2A side of the upper platform 2, therefore there are no scratches or damage caused by contact with the workpiece, i.e., the wafer W, and there is no adhesion of slurry and water droplets or the accumulation of dirt on the window material 6 on the opposite side of the grinding surface 2A of the upper platform 2. That is, the number of measurement points was found to be higher in the embodiment than in the comparative example.

[0073] ◇Wafer thickness measurement results after processing Figures 4 and 5 show the evolution of wafer thickness within a batch. As another evaluation, the evolution of post-processed wafer thickness (average of five wafers per batch), target thickness, and the difference between post-processed wafer thickness and target thickness is compared for 150 consecutive batches. The results are shown in Figures 6 and 7. For measuring the thickness of processed wafers, the KLA WaferSight2 flatness measuring instrument was used. The smaller the difference between the processed wafer thickness and the target thickness, the better the thickness measurement accuracy. If we compare the proportion of batches with a difference of less than 0.2 μm as a benchmark, the proportion in the comparative example is 76.0%, while in the example it is 98.0%, showing an improvement.

[0074] Furthermore, in the double-sided grinding apparatus 1 of the embodiment, the hollow plug 5 can be easily disassembled during cleaning and replacement, thus minimizing the disruption of operation during cleaning and replacement of the hollow plug 5. As a result, it is possible to maintain productivity while removing the source of scratches or particles.

[0075] Furthermore, in the embodiment, even after processing 150 batches consecutively, no damage to the window material 6 was confirmed.

[0076] These results demonstrate that the double-sided grinding apparatus according to the present invention can exhibit excellent thickness measurement accuracy and eliminate concerns about metal impurities, scratches, and particles.

[0077] Furthermore, the present invention is not limited to the embodiments described above. The embodiments described above are illustrative examples; any invention having a substantially identical structure and function to the technical concept described in the claims of the present invention is included within the scope of the present invention.

[0078] 1: Double-sided grinding device 2: Go to the platform 2A: Grinding surface 2B: Top surface 3: Lower Platform 4A: Abrasive cloth 4B: Abrasive cloth 5: Hollow plug 6: Window materials 7: Wafer thickness measurement mechanism 8: Sun Gear 9: Internal gear 10: Double-sided grinding device 21: Platform through hole 22: Center of Rotation 23: Zhou Yuan 41: Kong 51: Plug the through hole 52: Upper surface 53: Flange portion 54A: Shaft 55: O-ring 56: O-ring 61: Adhesive layer L: Laser light W: Wafer

[0079] Domestic storage information (please note in order of storage institution, date, and number) none Overseas storage information (please note in the order of storage country, institution, date, and number) none

Claims

1. A wafer double-sided polishing apparatus, comprising an upper platform and a lower platform, wherein: In the aforementioned upper platform, a plurality of platform through holes are provided between the rotation center and the periphery, and an abrasive cloth is provided on the grinding surface of the aforementioned upper platform opposite to the aforementioned lower platform; in the aforementioned abrasive cloth, a hole is provided at a position corresponding to the aforementioned plurality of platform through holes, and the hole has a diameter larger than or equal to the diameter of the aforementioned platform through holes; a hollow resin plug is inserted into each of the aforementioned through holes of the aforementioned upper platform, the upper surface of the hollow plug is provided with a window material and the lower surface of the aforementioned grinding surface is not provided with a window material, and the hollow plug has a plug through hole; furthermore, the aforementioned two-sided grinding device is provided with a wafer thickness measuring mechanism at the upper part of the aforementioned upper platform, and the wafer thickness measuring mechanism can optically measure the thickness of the aforementioned wafer in real time during grinding through the aforementioned plug through hole.

2. The double-sided grinding apparatus as described in claim 1, wherein: The aforementioned wafer thickness measurement mechanism includes a variable wavelength infrared laser device that emits laser light at a wavelength that is optically transmitted relative to the aforementioned wafer.

3. The double-sided grinding apparatus as described in claim 2, wherein: The aforementioned window material allows the aforementioned laser light to pass through.

4. The double-sided grinding apparatus as described in claim 2, wherein: The aforementioned through-hole of the hollow plug has a diameter that is at least 1.5 mm larger than the diameter of the aforementioned laser beam.

5. The double-sided grinding apparatus as described in claim 3, wherein: The aforementioned through-hole of the hollow plug has a diameter that is at least 1.5 mm larger than the diameter of the aforementioned laser beam.

6. The double-sided grinding apparatus as described in any one of claims 1 to 5, wherein: The aforementioned hollow plug has a flange portion, which is attached to the aforementioned window material, and the outer diameter of the aforementioned flange portion is larger than the diameter of the aforementioned platform through hole of the aforementioned upper platform.

7. The double-sided grinding apparatus as described in any one of claims 1 to 5, wherein: The aforementioned hollow plug is fixed to the aforementioned platform through hole of the aforementioned upper platform by means of an O-ring made of synthetic rubber.

8. The double-sided grinding apparatus as described in claim 6, wherein: The aforementioned hollow plug is fixed to the aforementioned platform through hole of the aforementioned upper platform by means of an O-ring made of synthetic rubber.

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