TW202344342A - Double-sided polishing device - Google Patents

Abstract

The present invention is a double-sided polishing device for a wafer and has an upper platen and a lower platen, said double-sided polishing device being characterized in that: the upper platen is provided with a plurality of platen through holes between the rotational center and the peripheral edge thereof; a polishing cloth is provided to a polishing surface on the upper platen which faces the lower platen; holes having a diameter equal to or larger than the diameter of the platen through holes are provided in the polishing cloth at positions corresponding to the plurality of platen through holes; a resin hollow plug having a window material on the upper surface thereof and having a plug through hole is inserted into each of the platen through holes in the upper platen; and a wafer thickness measuring mechanism that is capable of optically measuring, through the plug through holes, the thickness of the wafer in real time during polishing is further provided above the upper platen. It is thus possible to provide a double-sided polishing device that exhibits excellent thickness measurement accuracy and that can eliminate concerns about metal impurities, flaws, and particles.

Description

Double side grinding device

The invention relates to a double-sided grinding device, which has a thickness measuring mechanism for a wafer being processed.

In the double-side grinding step of the wafer, real-time wafer thickness measurement is required in order to minimize the deviation of the post-processing thickness from the target wafer thickness.

Fig. 8 shows a schematic side view of a previous example of the double-sided polishing device. Moreover, Fig. 9 shows a schematic enlarged cross-sectional view of the IX portion of the double-sided polishing device shown in Fig. 8 .

The double-sided grinding device 10 shown in FIGS. 8 and 9 is a four-function double-sided grinding device and includes an upper platform 2 , a lower platform 3 , a sun gear 8 and an internal gear 9 . Furthermore, a polishing cloth 4A is provided on the polishing surface 2A of the upper platform 2 facing the lower platform 3 . A polishing cloth 4B is provided on the surface of the lower platform 3 that faces the upper platform 2 . Furthermore, the double-side polishing apparatus 10 further includes a wafer thickness measuring mechanism 7 on the upper part of the upper platform 2 .

In the double-side polishing step of an example of the prior art using the double-side polishing device 10 shown in Figures 8 and 9, as shown in Figures 8 and 9, one side passes from the wafer thickness measuring mechanism 7 through the upper platform 2 The platform through hole 21 irradiates the infrared laser L to the wafer W being polished, monitors the thickness using light reflection interferometry, and ends polishing when the wafer W reaches a desired thickness.

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

In addition, various methods and/or devices for monitoring the thickness of the wafer W during polishing have been proposed.

For example, Patent Document 1 describes an optical measurement method in which the surface state of the object to be polished is measured via a plug member that transmits measurement light. Measuring holes and formed of almost transparent material.

Patent Document 2 describes a method of measuring the thickness of a wafer during polishing by transmitting an infrared laser through a slurry supply hole of an upper platform equipped with a plastic window on the polishing cloth side of a double-sided polishing device. material.

Patent Document 3 describes a measurement method in which a quartz material is used for the sensor holder of the slurry supply hole of the upper platform in a double-sided polishing device, thereby reducing thickness errors caused by heating of the upper platform during polishing.

Patent Document 4 describes a method in which a laser is irradiated from the slurry supply hole of the upper platform in a double-sided polishing device, the reflected light is detected, and the data is corrected using the correlation between the resistivity and thickness of the wafer, thereby Highly accurate measurement of wafer thickness during grinding.

Patent Document 5 describes a grinding machine. In a double-sided grinding device, a shape measuring device measures the shape of a workpiece from a measurement hole formed in an upper platform, memorizes the shape into a memory, and displays the shape in chronological order. The shape of the workpiece being ground.

[Prior technical literature] (patent document) 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

(The problem that the invention aims to solve) In the double-sided polishing device shown in Figures 8 and 9, since there is a window 6 on the polishing surface 2A side of the upper stage 2, the window 6 may be damaged due to contact between the workpiece, that is, the wafer W and the window 6. Damage may cause scars and/or particles. As for the thickness measurement accuracy, it will also be affected by accumulated scratches and/or dirt in the window material 6 or the window material 6 being compressed and deformed by the abrasive slurry, resulting in insufficient accuracy.

Although attaching the window material 6 only to the non-polished surface, that is, the upper surface 2B side, can eliminate the above problems, there is a concern that metal impurities will be contained in the platform through hole 21 because the platform metal part is in contact with the liquid of the slurry. In addition, since the slurry fixed in the platform through-hole 21 will cause scratches and/or particles, it needs to be cleaned regularly. However, cleaning the platform through-hole 21 is labor-intensive and time-consuming, so it may cause damage due to device stoppage. Productivity deteriorates.

The present invention was completed to solve the above 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.

(means used to solve problems) In order to solve the above problems, the present invention provides a double-sided grinding device with 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 a grinding cloth is provided on the grinding surface of the aforementioned platform that is opposite to the aforementioned lower platform; In the above-mentioned polishing cloth, holes are provided at positions corresponding to the plurality of platform through-holes, and the holes have a diameter larger than the diameter of the above-mentioned platform through-holes; A resin-made hollow plug is inserted into each of the through holes of the upper platform, the upper surface of the hollow plug is provided with a window material, and the hollow plug has a plug through hole; and, The above-mentioned double-sided grinding device is further equipped with a wafer thickness measuring mechanism on the upper part of the above-mentioned upper platform. The wafer thickness measuring mechanism can optically measure the thickness of the above-mentioned wafer in real time during grinding through the above-mentioned plug through-hole.

In the double-sided grinding device of the present invention, by inserting a resin-made hollow plug into the platform through-hole, there is no need to worry about metal contamination even if the platform material is metal. Therefore, there is no need to stick the part in contact with the slurry during the grinding process of the lower end of the upper platform. Window materials. Furthermore, in the double-sided grinding device of the present invention, a window is provided on the upper surface of the hollow plug, that is, the surface opposite to the grinding surface. Therefore, the risk of window damage can be eliminated, and the accuracy of thickness measurement can be improved. .

In addition, since the hollow plug is easily detachable, the double-sided polishing device can be continuously operated by replacing the preliminary plug even during cleaning, so the decrease in productivity can be suppressed to a minimum.

That is, according to the double-sided grinding device of the present invention, it can show excellent thickness measurement accuracy and eliminate concerns about metal impurities, scratches, and particles.

For example, the wafer thickness measuring mechanism may be equipped with a variable wavelength infrared laser device that can emit laser light with a wavelength that is optically transmitted by the wafer.

As the wafer thickness measuring mechanism, for example, a variable wavelength infrared laser device can be used, but it is not limited thereto.

At this time, it is preferable that the window material transmits the laser light.

If the window material is a material that transmits the laser light from the variable wavelength infrared laser device, the interference caused by the window material on the thickness measurement can be reduced, thereby improving the accuracy of the wafer thickness measurement.

In addition, at this time, it is preferable that the plug through hole of the hollow plug has a diameter that is 1.5 mm or more larger than the diameter of the laser light.

If the diameter of the plug penetration hole of the hollow plug is 1.5 mm or more larger than the diameter of the laser used for wafer measurement, the influence of slurry or water droplets adhering to the plug penetration hole can be suppressed, and high accuracy can be achieved. Wafer thickness measurement.

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

If it is a double-sided grinding device with a hollow plug and the hollow plug has such a flange portion, the state in which the hollow plug is inserted into the platform through hole of the upper platform can be stably maintained, and the risk of the hollow plug falling to the grinding surface can be eliminated.

The hollow plug is preferably fixed to the platform through-hole of the upper platform via an O-ring made of synthetic rubber.

In this way, the hollow plug is fixed to the platform through hole through the O-ring, which not only stably maintains the state in which the hollow plug is inserted into the platform through hole of the upper platform, but also effectively prevents liquid contact between the upper platform and the slurry.

(The effect of the invention) As described above, the double-sided grinding device according to the present invention can demonstrate excellent thickness measurement accuracy and eliminate concerns about metal impurities, scratches, and particles.

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

As a result of repeated and in-depth research on the above-mentioned problems, the inventors found that a double-sided polishing device equipped with an optical wafer thickness measuring mechanism has a window material attachment surface on the upper surface, and a resin-made hollow with a plug through hole. By inserting the plug into each of the platform through-holes of the upper platform and providing a window material on the upper surface of the hollow plug, it is possible to achieve excellent thickness measurement accuracy and eliminate worries about metal impurities, scratches and particles, thus completing this invention.

That is, the present invention is a double-sided grinding device with 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 a grinding cloth is provided on the grinding surface of the aforementioned platform that is opposite to the aforementioned lower platform; In the above-mentioned polishing cloth, holes are provided at positions corresponding to the plurality of platform through-holes, and the holes have a diameter larger than the diameter of the above-mentioned platform through-holes; A resin-made hollow plug is inserted into each of the through holes of the upper platform, the upper surface of the hollow plug is provided with a window material, and the hollow plug has a plug through hole; and, The above-mentioned double-sided grinding device is further equipped with a wafer thickness measuring mechanism on the upper part of the above-mentioned upper platform. The wafer thickness measuring mechanism can optically measure the thickness of the above-mentioned wafer in real time during grinding through the above-mentioned plug through-hole.

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

Fig. 1 shows a schematic side view of an example of the double-side polishing device of the present invention. In addition, Fig. 2 shows a schematic enlarged cross-sectional view of part II of the double-sided polishing device shown in Fig. 1 .

The double-side polishing device 1 shown in FIGS. 1 and 2 is a double-side polishing device for a wafer W having an upper platform 2 and a lower platform 3 .

A plurality of platform through holes 21 are provided between the rotation center 22 and the peripheral edge 23 of the upper platform 2 . The platform through hole 21 penetrates the upper platform 2 from the grinding surface 2A to the upper surface 2B. Figure 1 shows two platform through holes 21 as representatives, but the number of the platform through holes 21 is not limited to two. In addition, the position of the platform through hole 21 is not limited to the position shown in FIG. 1 .

A polishing cloth 4A is provided on the polishing surface 2A of the upper platform 2 facing the lower platform 3 . This polishing cloth 4A is provided with holes 41 at positions corresponding to the plurality of table through holes 21 of the upper table, and the holes 41 have a diameter larger than the diameter of the table through holes 21 .

In the double-sided polishing device 1 , a resin-made hollow plug 5 is inserted into each of the plate through holes 21 of the upper plate 2 . As shown in FIG. 2 , the hollow plug 5 is provided with a window material 6 on the upper surface 52 . On the other hand, in this example, as shown in Figure 2, there is no window material on the polishing surface 2A side, that is, on the lower surface. Furthermore, the hollow plug 5 has a plug penetration hole 51 .

The double-side grinding device 1 is further equipped with a wafer thickness measuring mechanism 7 on the upper part of the upper platform 2 . The wafer thickness measuring mechanism 7 can instantly optically measure the thickness of the wafer W during grinding through the plug through hole 51 .

In such a double-sided polishing device 1, by inserting the resin hollow plug 5 into the table through hole 21, there is no need to worry about metal contamination even if the table material is metal, so there is no need to polish the lower end of the upper table 2 The part in contact with the slurry is glued to the window material 6. In addition, in the double-sided polishing device 1, the window material 6 is provided on the upper surface 52 of the hollow plug 5, that is, the non-polished surface opposite to the polishing surface 2A. Therefore, the risk of damage to the window material 6 can be eliminated, and it is possible to Improve thickness measurement accuracy.

In addition, since the hollow plug 5 is easily removable, by replacing the preliminary plug during cleaning, the double-sided grinding device 1 can continue to operate, thereby minimizing a decrease in productivity.

That is, according to the double-sided grinding device 1 of the present invention, it can show excellent thickness measurement accuracy and eliminate worries about metal impurities, scratches, and particles.

The wafer W to be polished by the double-side polishing device 1 of the present invention is typically a silicon wafer, especially a semiconductor silicon wafer. However, the wafer W to be polished by the double-side polishing device 1 of the present invention is not limited to the silicon wafer.

Hereinafter, the double-sided polishing device 1 of the example shown in FIGS. 1 and 2 will be described in more detail.

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

A polishing cloth 4B is provided on the surface of the lower platform 3 opposite to the upper platform 2 .

As the polishing cloths (polishing pads) 4A and 4B provided on the upper platform 2 and the lower platform 3 respectively, for example, commercially available polyurethane foam pads or hard nonwoven pads can be used, but are not limited to these.

As shown in FIG. 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 on which the window material 6 is provided is the upper surface of the flange portion 53 . The shaft portion 54 is held in the platform through hole 21 .

As shown in FIG. 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 . Thereby, the flange portion 53 of the hollow plug 5 functions as a stopper, so that the state in which the hollow plug 5 is inserted into the platform through hole 21 of the upper platform 2 can be stably maintained, and the hollow plug 5 can be prevented from falling to the grinding surface. face risks.

In the examples shown in Figures 1 and 2, the hollow plug 5 is fixed in the platform through hole 21 of the upper platform 2 through O-rings 55 and 56 made of synthetic rubber. One O-ring 55 is attached to a portion of the shaft portion 54 of the hollow plug 5 close to the flange portion 53 . The other O-ring 56 is attached to a portion of the shaft portion 54 of the hollow plug 5 close to the front end portion 54A.

In this way, the hollow plug 5 is fixed in the platform through hole 21 by the synthetic rubber O-rings 55 and 56, which can not only stably maintain the state of the hollow plug 5 inserted into the platform through hole 21 of the upper platform 2, but also stabilize the hollow plug 5 in the platform through hole 21. It can effectively prevent the upper platform 2 from being in liquid contact with the slurry.

As shown in FIG. 2 , the plug penetration hole 51 penetrates the hollow plug 5 from the upper surface 52 to the front end 54A of the shaft portion 54 .

The wafer thickness measuring mechanism 7 is configured to optically and instantly measure the thickness of the wafer W during polishing via the plug through hole 51 . In the example of FIG. 1 , the wafer thickness measuring mechanism 7 includes: a light source that irradiates the wafer W being polished with laser light L; a light receiving unit that receives reflected light from the wafer W; and a calculation unit that self-reflects. Simply calculate the wafer thickness.

As the light source, a variable wavelength infrared laser device can be used, which can emit laser light L of a wavelength that optically transmits the wafer, but is not limited thereto.

The window material 6 is attached to the upper surface 52 of the hollow plug 5 via the adhesive layer 61 .

The window material 6 preferably transmits the laser light L from the variable wavelength infrared laser device.

If the window material 6 is a material that transmits the laser light L from the variable wavelength infrared laser device, the interference caused by the window material 6 on the thickness measurement can be reduced, and therefore the accuracy of the thickness measurement of the wafer W can be further improved.

The window material 6 may be, for example, a film transmissive to laser light L.

As shown in FIG. 1 , the incident light toward the wafer W and the reflected light from the wafer W (together as laser light L and represented by a dotted line) are inserted into the platform through hole 21 provided in the upper platform 2 The plug penetration hole 51 of the hollow plug 5 is formed.

FIG. 3 is a schematic plan view showing the relationship between the plug through hole 51 and the laser light L when the hollow plug 5 in the double-sided polishing device 1 of this example is viewed from the upper surface 52 .

As shown in FIG. 3 , the plug penetration hole 51 of the hollow plug 5 has a larger diameter than the diameter of the laser light L.

For example, if the diameter of the plug through hole 51 of the hollow plug 5 is larger than the diameter of the laser light L used for wafer thickness measurement by more than 1.5 mm, the influence of slurry, water droplets, etc. attached to the plug through hole 51 can be suppressed. , and perform wafer thickness measurement with high accuracy. The upper limit of the diameter of the plug through hole 51 of the hollow plug 5 relative to the diameter of the laser light L for wafer thickness measurement is not particularly limited. For example, the diameter of the plug through hole 51 of the hollow plug 5 can be made smaller than the diameter of the laser light L for wafer thickness measurement. The diameter of laser light L is larger than 1.5mm and below 30mm.

[Example] Hereinafter, the present invention will be specifically described using Examples and Comparative Examples, but the present invention is not limited to these Examples.

(Example) In the Example, the double-side polishing apparatus 1 shown in FIGS. 1 and 2 configured under the following conditions was used to perform double-side polishing of the wafer W under the following conditions.

(Comparative example) In the comparative example, the double-side polishing apparatus 10 shown in FIGS. 8 and 9 configured under the following conditions was used to perform double-side polishing of the wafer W under the following conditions.

◇Common points between the examples and comparative examples ． As the wafer W, a P-type silicon single crystal wafer with a diameter of 300 mm and a normal resistance of 10Ω was used. ． As the upper table 2 of the double-sided polishing device, one having ten table through holes 21 with a diameter of 15 mm on the circumference with the rotation center 22 as a fulcrum was used. ． As the polishing cloths 4A and 4B provided on the upper platform 2 and the lower platform 3 respectively, urethane foam polishing cloths are used. As the polishing slurry, one containing silica sol abrasive particles and having a pH adjusted to a range of 10.0 to 11.0 is used. ． As the thickness measuring mechanism 7, a variable wavelength infrared laser having a laser diameter of 3 mm, a wavelength of 1300 mm, and a power of 10 mW or more is used. ． As the window material 6, a 30 mm diameter piece cut from a PET (polyethylene terephthalate) film (thickness 200 μm) made by TORAY so that the diameter is 15 mm larger than the diameter of the platform through hole 21 of the upper platform 2 is used. disc shaped film. A film of double-sided tape (Sumitomo 3M442JS3, thickness 110 μm) as the adhesive layer 61 is attached along the outer periphery of the window material 6 of the PET film, and is attached to the upper surface 52 of the hollow plug 5 (Fig. 2; Example) or The polished surface 2A of the upper platform 2 (Fig. 9; Comparative Example).

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

◇Comparative example ． For the polishing cloth 4A attached to the upper platform 2, a hole 41 with a diameter of 30 mm, which is 15 mm larger than the platform through hole 21, is drilled at the same position as the platform through hole 21 of the upper platform 2. ． As shown in FIG. 9 , the window material 6 is attached to the position of the hole 41 of the polishing cloth 4A.

◇Measurement results of wafer thickness during processing ． The evolution of thickness measurements from the beginning to the end of grinding of wafer W was compared in a batch of five wafers. The results are shown in Figure 4 and Figure 5 respectively. ． The polishing rate is calculated from the monitored wafer thickness and polishing is terminated when the specified finishing thickness is reached. This polishing rate is updated each time the wafer thickness is measured. In other words, the more thickness measurements are taken, the closer it is to the true polishing rate. Therefore, those who take more measurements can expect an improvement in the accuracy of the processed wafer thickness. ． As shown in Figures 4 and 5, if the number of thickness measurements in a batch is compared, there are 169 points in the comparative example, whereas there are 535 points in the example. This is because in the comparative example, the window material 6 on the polishing surface 2A side of the upper stage 2 has scratches, damage and deformation caused by contact with the workpiece, that is, the wafer W, or is subject to adhesion and dirt from slurry and water droplets. In contrast to the influence of accumulation, in the embodiment, there is no window 6 on the polishing surface 2A side of the upper platform 2, so there is no scratch or damage or deformation caused by contact with the workpiece, that is, the wafer W, and the upper platform is The polished surface 2A of 2 is not affected by the adhesion of slurry and water droplets or the accumulation of dirt on the window material 6 on the opposite side. That is, in the Example, it was confirmed that the number of measurement points was improved compared to the Comparative Example.

◇Measurement results of wafer thickness after processing ． The results shown in Figures 4 and 5 are the evolution of wafer thickness within a batch. As an additional evaluation, the wafer thickness after continuous processing of 150 batches (an average of five wafers in a batch) and the target thickness and the evolution of the difference in post-processed wafer thickness relative to the target thickness. The results are shown in Figures 6 and 7. ． For thickness measurement of processed wafers, the flatness measuring instrument WaferSight2 manufactured by KLA is used. ． The smaller the difference between the processed wafer thickness and the target thickness, the better the thickness measurement accuracy. When comparing the proportion of batches with a difference of 0.2 μm or less as a basis, it was 76.0% in the comparative example and 98.0% in the example. An improvement can be seen.

In addition, in the double-sided polishing device 1 of the embodiment, the hollow plug 5 can be easily detached during cleaning and replacement, so that the operation stoppage of the hollow plug 5 during cleaning and replacement can be suppressed to a minimum. As a result, it is possible to eliminate the sources of scratches and particles while maintaining productivity.

Moreover, in the Example, even after 150 batches of continuous processing, no damage to the window material 6 was confirmed.

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

In addition, the present invention is not limited to the above-described embodiment. The above-mentioned embodiments are examples, and anything that has substantially the same structure as the technical ideas described in the patent application scope of the present invention and performs the same functions is included in the technical scope of the present invention.

1:Double-sided grinding device 2: Go to the platform 2A: Grinding surface 2B: Upper surface 3: Get off the platform 4A:Abrasive cloth 4B: Polishing 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:Rotation center 23: Zhou Yuan 41:hole 51: Plug through hole 52: Upper surface 53:Flange part 54A: Shaft 55:O-ring 56:O-ring 61:Adhesive layer L:Laser light W:wafer

Fig. 1 is a schematic side view showing an example of the double-side polishing device of the present invention. Fig. 2 is an enlarged schematic cross-sectional view of part II of the double-sided polishing device shown in Fig. 1. FIG. 3 is a schematic plan view showing the relationship between the plug through hole of the hollow plug and laser light in the double-sided polishing device shown in FIG. 1 . FIG. 4 is a graph showing the evolution of wafer thickness during wafer processing in the embodiment. FIG. 5 is a graph showing the evolution of wafer thickness during wafer processing in a comparative example. Fig. 6 is a graph showing the evolution of the thickness during continuous processing of 150 batches in the Example. Fig. 7 is a graph showing the evolution of thickness during continuous processing of 150 batches in a comparative example. FIG. 8 is a schematic side view showing an example of a conventional double-side polishing device. Fig. 9 is an enlarged schematic cross-sectional view of portion IX of the double-sided polishing device shown in Fig. 8.

Domestic storage information (please note in order of storage institution, date and number) without Overseas storage information (please note in order of storage country, institution, date, and number) without

1:Double-sided grinding device

2: Go to the platform

2A: Grinding surface

2B: Upper surface

3: Get off the platform

4A:Abrasive cloth

4B: Polishing 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:Rotation center

23: Zhou Yuan

41:hole

L:Laser light

W:wafer

Claims (8)

A double-sided grinding device has 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 a grinding cloth is provided on the grinding surface of the aforementioned platform that is opposite to the aforementioned lower platform; In the above-mentioned polishing cloth, holes are provided at positions corresponding to the plurality of platform through-holes, and the holes have a diameter larger than the diameter of the above-mentioned platform through-holes; A resin-made hollow plug is inserted into each of the through holes of the upper platform. The hollow plug has a window material on its upper surface and has no window material on the grinding surface side, that is, its lower surface. The hollow plug has a plug. through holes; and, The above-mentioned double-sided grinding device is further equipped with a wafer thickness measuring mechanism on the upper part of the above-mentioned upper platform. The wafer thickness measuring mechanism can optically measure the thickness of the above-mentioned wafer in real time during grinding through the above-mentioned plug through-hole. The double-sided grinding device as claimed in claim 1, wherein: The wafer thickness measuring mechanism is equipped with a variable wavelength infrared laser device, and the variable wavelength infrared laser device can emit laser light with a wavelength that is optically transmitted by the wafer. The double-sided grinding device as claimed in claim 2, wherein: The window material transmits the laser light. The double-sided grinding device as claimed in claim 2, wherein: The plug through hole of the hollow plug has a diameter larger than the diameter of the laser light by 1.5 mm or more. The double-sided grinding device as claimed in claim 3, wherein: The plug through hole of the hollow plug has a diameter larger than the diameter of the laser light by 1.5 mm or more. The double-sided grinding device according to any one of claims 1 to 5, wherein: The hollow plug has a flange portion attached to the window material, and the outer diameter of the flange portion is larger than the diameter of the platform through hole of the upper platform. The double-sided grinding device according to any one of claims 1 to 5, wherein: The hollow plug is fixed to the platform through hole of the upper platform through an O-ring made of synthetic rubber. The double-sided grinding device as claimed in claim 6, wherein: The hollow plug is fixed to the platform through hole of the upper platform through an O-ring made of synthetic rubber.