CN117415681A - Polishing method for small-size aluminum nitride wafer - Google Patents
Polishing method for small-size aluminum nitride wafer Download PDFInfo
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- CN117415681A CN117415681A CN202311488693.9A CN202311488693A CN117415681A CN 117415681 A CN117415681 A CN 117415681A CN 202311488693 A CN202311488693 A CN 202311488693A CN 117415681 A CN117415681 A CN 117415681A
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- 238000005498 polishing Methods 0.000 title claims abstract description 118
- PMHQVHHXPFUNSP-UHFFFAOYSA-M copper(1+);methylsulfanylmethane;bromide Chemical compound Br[Cu].CSC PMHQVHHXPFUNSP-UHFFFAOYSA-M 0.000 title claims abstract description 71
- 238000000034 method Methods 0.000 title claims abstract description 35
- 235000012431 wafers Nutrition 0.000 claims abstract description 191
- 239000000919 ceramic Substances 0.000 claims abstract description 76
- 238000007517 polishing process Methods 0.000 claims abstract description 15
- 229910052594 sapphire Inorganic materials 0.000 claims abstract description 8
- 239000010980 sapphire Substances 0.000 claims abstract description 8
- 229910010271 silicon carbide Inorganic materials 0.000 claims abstract description 4
- HBMJWWWQQXIZIP-UHFFFAOYSA-N silicon carbide Chemical compound [Si+]#[C-] HBMJWWWQQXIZIP-UHFFFAOYSA-N 0.000 claims abstract description 4
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 claims description 29
- 229910052802 copper Inorganic materials 0.000 claims description 29
- 239000010949 copper Substances 0.000 claims description 29
- 239000007788 liquid Substances 0.000 claims description 20
- 229910003460 diamond Inorganic materials 0.000 claims description 13
- 239000010432 diamond Substances 0.000 claims description 13
- 229920002635 polyurethane Polymers 0.000 claims description 10
- 239000004814 polyurethane Substances 0.000 claims description 10
- 238000010438 heat treatment Methods 0.000 claims description 9
- 239000012188 paraffin wax Substances 0.000 claims description 9
- RMAQACBXLXPBSY-UHFFFAOYSA-N silicic acid Chemical compound O[Si](O)(O)O RMAQACBXLXPBSY-UHFFFAOYSA-N 0.000 claims description 9
- 229910052580 B4C Inorganic materials 0.000 claims description 8
- INAHAJYZKVIDIZ-UHFFFAOYSA-N boron carbide Chemical compound B12B3B4C32B41 INAHAJYZKVIDIZ-UHFFFAOYSA-N 0.000 claims description 8
- 239000006061 abrasive grain Substances 0.000 claims 1
- 239000013078 crystal Substances 0.000 abstract description 6
- 239000004065 semiconductor Substances 0.000 abstract description 3
- 238000010586 diagram Methods 0.000 description 10
- 230000003746 surface roughness Effects 0.000 description 10
- 238000002474 experimental method Methods 0.000 description 8
- 239000002245 particle Substances 0.000 description 7
- 230000000052 comparative effect Effects 0.000 description 5
- 238000005520 cutting process Methods 0.000 description 4
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 239000000463 material Substances 0.000 description 3
- 239000000126 substance Substances 0.000 description 3
- 238000006467 substitution reaction Methods 0.000 description 2
- 239000000758 substrate Substances 0.000 description 2
- PIGFYZPCRLYGLF-UHFFFAOYSA-N Aluminum nitride Chemical compound [Al]#N PIGFYZPCRLYGLF-UHFFFAOYSA-N 0.000 description 1
- 239000008119 colloidal silica Substances 0.000 description 1
- 230000001419 dependent effect Effects 0.000 description 1
- 239000000377 silicon dioxide Substances 0.000 description 1
- 235000012239 silicon dioxide Nutrition 0.000 description 1
- 239000002002 slurry Substances 0.000 description 1
Classifications
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B24—GRINDING; POLISHING
- B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
- B24B1/00—Processes of grinding or polishing; Use of auxiliary equipment in connection with such processes
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B24—GRINDING; POLISHING
- B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
- B24B41/00—Component parts such as frames, beds, carriages, headstocks
- B24B41/06—Work supports, e.g. adjustable steadies
- B24B41/067—Work supports, e.g. adjustable steadies radially supporting workpieces
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B24—GRINDING; POLISHING
- B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
- B24B7/00—Machines or devices designed for grinding plane surfaces on work, including polishing plane glass surfaces; Accessories therefor
- B24B7/20—Machines or devices designed for grinding plane surfaces on work, including polishing plane glass surfaces; Accessories therefor characterised by a special design with respect to properties of the material of non-metallic articles to be ground
- B24B7/22—Machines or devices designed for grinding plane surfaces on work, including polishing plane glass surfaces; Accessories therefor characterised by a special design with respect to properties of the material of non-metallic articles to be ground for grinding inorganic material, e.g. stone, ceramics, porcelain
- B24B7/228—Machines or devices designed for grinding plane surfaces on work, including polishing plane glass surfaces; Accessories therefor characterised by a special design with respect to properties of the material of non-metallic articles to be ground for grinding inorganic material, e.g. stone, ceramics, porcelain for grinding thin, brittle parts, e.g. semiconductors, wafers
Abstract
The invention belongs to the technical field of semiconductor processing, and particularly relates to a polishing method of a small-size aluminum nitride wafer. In the polishing method, when the small-size aluminum nitride wafer to be processed is less than 3, sapphire or silicon carbide is adopted as an auxiliary piece, and the sapphire or the silicon carbide and the small-size aluminum nitride wafer are placed on a ceramic disc together for polishing; for a ceramic disk having a diameter of 4 inches, the total surface area of the wafer to be processed is 11.4-45.6cm 2 Corresponding to a circular area of 1.5-3 inches in diameter, at which point the corresponding polishing pressure is 300g/cm 2 ～700g/cm 2 The rotation speed of the large disc is 40 rpm-70 rpm. The method is used for polishing the wafer with the size smaller than one inch, and solves the problems that the crystal face TTV is difficult to control and the removal amount is difficult to control due to the fact that the clamp is inclined easily due to the small size in the polishing process of the small-size wafer; at the same timeThe polishing device is used for polishing a plurality of small-size wafers at the same time, so that the polishing efficiency of the plurality of wafers is remarkably improved; the processed wafer has high integrity, and the occurrence of fracturing phenomenon is greatly reduced.
Description
Technical Field
The invention belongs to the technical field of semiconductor processing, and particularly relates to a polishing method of a small-size aluminum nitride wafer.
Background
Aluminum nitride (AlN) is an extremely important ultra-wide band-gap semiconductor material, is an optimal substrate material for ultraviolet/deep ultraviolet LEDs and ultraviolet LDs, and is an ideal substrate material for high-power and high-frequency electronic devices. To achieve its excellent properties, a wafer with a perfect surface must be obtained through a proper processing step. The processing process of the aluminum nitride wafer comprises the following steps: a cutting process of cutting the ingot into wafers using diamond wires; the grinding process is to remove the linear cutting mark on the surface of the cutting sheet and level; and removing the damaged layer and scratches left by grinding the surface of the wafer in the polishing process. In wafer processing, the polishing technique is particularly critical, and the quality of the wafer surface is highly dependent on the effect of the polishing.
The AlN wafer polishing process in the prior art mainly comprises the following steps: an AlN wafer leveled with boron carbide was polished with a diamond slurry of grain size from 6 μm to 1 μm to produce an optically smooth surface. Finally, a CMP process was performed with colloidal silica (ph=9-13) to prepare a surface. The grain size of the silicon dioxide is 50-100nm, and the pressure applied on the surface of the AlN wafer is 100-500g/cm 2 Between them. The large disc speed was maintained at 100rpm.
Polishing can obtain a wafer with a smooth and flat surface, but in order to meet the actual requirements, it is sometimes required to polish aluminum nitride wafers with certain special sizes, such as smaller sizes, and polishing equipment and polishing methods in the prior art are used for polishing small-size wafers, so that the problem that the contact surface of the wafer is small due to the fact that the clamp is large because the size of the wafer is too small, inclination is caused, and crystal plane TTV and removal amount are difficult to control, or polishing efficiency is low is caused. Therefore, there is a need to develop a polishing method that enables a small-sized aluminum nitride wafer to obtain a smooth surface of high quality.
Disclosure of Invention
The invention aims to provide a polishing method of a small-size aluminum nitride wafer, which solves the problems that the crystal surface TTV is difficult to control and the removal amount is difficult to control due to the fact that the clamp is inclined easily due to small size in the polishing process of the small-size aluminum nitride wafer, and can effectively shorten the processing time.
The small-sized wafer as used herein refers to a circular wafer having a diameter of 1 inch or less or a square wafer having a side length of 1 inch or less.
In order to achieve the above purpose, the invention adopts the following technical scheme:
a method of polishing a small-sized aluminum nitride wafer, comprising the steps of:
step S1, if the number of small-size aluminum nitride wafers is less than 3, selecting sapphire or silicon carbide as an auxiliary wafer, and jointly using the small-size aluminum nitride wafers and the auxiliary wafer as wafers to be processed, so that the number of the wafers to be processed is at least 3, the thickness difference between the wafers to be processed is not more than 5 mu m, and the auxiliary wafer is a small-size wafer; grinding the small-size aluminum nitride wafer by using boron carbide;
s2, placing the wafer to be processed and the ceramic disc on a heating table for preheating; then, adhering wafers to be processed to the edge of a ceramic disc at equal intervals by using paraffin, and adhering the 1 or 2 small-sized aluminum nitride wafers to the center of the ceramic disc if more than 5 wafers to be processed have only 1 or 2 small-sized aluminum nitride wafers, and adhering other auxiliary wafers to the edge of the ceramic disc at equal intervals;
s3, sucking the ceramic disc in the step S2 on a clamp, placing the ceramic disc on a copper disc, and dripping diamond liquid to perform copper polishing on the wafer;
and S4, placing the copper polished wafer on a polyurethane polishing pad, and dropwise adding polishing liquid to polish the copper polished wafer.
Preferably, the preheating temperature in the step S2 is 100-130 ℃, and the flatness of the ceramic disc is 1-3 mu m.
Preferably, after the paraffin is melted by heating in step S2, the wafer to be processed is stuck on a ceramic plate, and then pressurized with a weight and cooled to room temperature.
Preferably, the diamond liquid abrasive particles in step S3 have a particle size1-6 μm, polishing pressure 100g/cm 2 ～300g/cm 2 The rotation speed of the large disc is 20 rpm-40 rpm.
Preferably, the polishing solution in step S4 is a silica sol polishing solution.
Preferably, the ceramic disk and the fixture have a diameter of 4 inches, and the total surface area of the wafer to be processed in step S1 is 11.4-45.6cm 2 Corresponding to a circular area of 1.5 inches to 3 inches in diameter.
The total surface area of the wafer to be processed refers to the sum of the areas of the single-side surfaces of the wafer to be processed. If the total area of the surface of the wafer to be processed is smaller, the wafer has larger risks of fracturing, falling and tilting, and if the surface area of the single wafer to be processed is too large, the air bubbles are discharged in the process of bonding the wafer, and the polishing difficulty of the edge of the wafer is larger.
It is further preferable that the center of the wafer to be processed in step S2 is 1 to 3.5cm from the edge of the ceramic disk.
Further preferably, the polishing pressure in step S4 is 300g/cm 2 ～700g/cm 2 The rotation speed of the large disc is 40 rpm-70 rpm.
Still more preferably, the total surface area of the wafer to be processed is 11.4-20cm 2 The polishing pressure in the step S4 is 300-500 g/cm 2 The rotation speed of the large disc is 40-50 rpm.
Still more preferably, the total surface area of the wafer to be processed is 20-30cm 2 The polishing pressure in the step S4 is 500-600 g/cm 2 The rotation speed of the large disc is 50-60 rpm.
The polishing method is chemical mechanical polishing, the chemical action and the mechanical action are strong, the problem that the wafer removal amount is too large and the crystal face quality is poor can be caused by sticking a single wafer on the ceramic disc, and the wafer removal rate can be slowed down and the crystal face quality can be improved by sticking the wafer by adopting the method of the step S2.
The copper polishing and polyurethane polishing can rapidly obtain small-size wafers with high flatness and low surface roughness.
Compared with the prior art, the invention has the following advantages:
(1) The method can be used for polishing wafers with the size smaller than one inch, and solves the problems that the crystal face TTV is difficult to control and the removal amount is difficult to control due to the fact that the clamp is inclined easily due to the small size in the polishing process of small-size wafers.
(2) The method can be used for simultaneously polishing a plurality of small-size wafers, and the polishing efficiency of the wafers is remarkably improved.
(3) The wafer processed by the method has high integrity, and the occurrence of fracturing phenomenon is greatly reduced.
Drawings
FIG. 1 is a diagram showing the bonding position of an aluminum nitride wafer on a ceramic disk in example 1 of the present invention;
FIG. 2 is a diagram showing the bonding position of an aluminum nitride wafer on a ceramic disk in example 2 of the present invention;
FIG. 3 is a diagram showing the bonding position of an aluminum nitride wafer on a ceramic disk in example 3 of the present invention;
FIG. 4 is a diagram showing the bonding position of an aluminum nitride wafer on a ceramic disk in example 4 of the present invention;
FIG. 5 is a diagram showing the bonding position of aluminum nitride square sheets on ceramic disks in example 5 of the present invention;
FIG. 6 is a graph showing the bonding position of aluminum nitride square sheets on ceramic disks in comparative example 1 of the present invention;
FIG. 7 is a physical diagram of the polished aluminum nitride; (a) Wafer physical map after polishing by the methods of example 4 and example 5; (b) Wafer physical image after monolithic polishing using the methods described in comparative examples 2 and 3;
fig. 8 is a microscopic view of the surface of a wafer after polishing by the method provided by the present invention.
Detailed Description
The invention will be further described with reference to specific embodiments, and advantages and features of the invention will become apparent from the description. The embodiments are merely exemplary and do not limit the scope of the invention in any way. It will be understood by those skilled in the art that various changes and substitutions of details and forms of the technical solution of the present invention may be made without departing from the spirit and scope of the present invention, but these changes and substitutions fall within the scope of the present invention.
Example 1
A method of polishing a small-sized aluminum nitride wafer, comprising the steps of:
s1, polishing 3 aluminum nitride square sheets with the side length of 20mm multiplied by 20mm after grinding by using boron carbide as wafers to be processed, placing the wafers to be processed and a ceramic disc together with the thickness difference of less than or equal to 5 mu m on a heating table for preheating at 110 ℃, wherein the flatness of the ceramic disc is 1-3 mu m;
s2, uniformly adhering wafers to be processed to the edge of a ceramic disc by using molten paraffin at equal intervals, as shown in FIG. 1, wherein FIG. 1 shows a schematic diagram of a bonding method of aluminum nitride square sheets of 20mm multiplied by 20mm on a 4-inch ceramic disc, 3 aluminum nitride wafers of 20mm multiplied by 20mm are uniformly adhered to the edge of the ceramic disc, and the distance between the centers of the aluminum nitride wafers and the edge of the ceramic disc is 2cm; the sum of the areas is 12 square centimeters, and the weight is pressurized and cooled to room temperature;
s3, sucking the ceramic disc stuck with the wafer to be processed on a clamp, placing the ceramic disc on a copper disc, dripping diamond liquid into the ceramic disc to perform copper polishing on the wafer, wherein the grain size of abrasive particles in the grinding liquid is 3 mu m, and the polishing pressure is 100g/cm 2 -200g/cm 2 The rotating speed of the large disc is 20 rpm-40 rpm;
s4, placing the copper polished wafer on a polyurethane polishing pad, and dropwise adding polishing solution to polish, wherein the polishing solution is silica sol polishing solution, and the polishing pressure is 300g/cm 2 ～500g/cm 2 The rotation speed of the large disc is 40 rpm-50 rpm.
The above experiment was repeated 30 times, the breakage rate of the polished wafer was less than 10%, and the surface roughness was less than 0.5nm.
Example 2
A method of polishing a small-sized aluminum nitride wafer, comprising the steps of:
s1, polishing 12 aluminum nitride square sheets with the size of 10mm multiplied by 10mm after grinding by using boron carbide as wafers to be processed, placing the wafers to be processed and a ceramic disc together with the thickness difference of less than or equal to 5 mu m on a heating table for preheating at 110 ℃, wherein the flatness of the ceramic disc is 1-3 mu m;
s2, uniformly adhering wafers to be processed to the edge of a ceramic disc by using molten paraffin at equal intervals, as shown in FIG. 2, wherein FIG. 2 shows a schematic diagram of a method for adhering a square aluminum nitride wafer with the thickness of 10mm multiplied by 10mm to a 4-inch ceramic disc, 12 aluminum nitride wafers with the thickness of 10mm multiplied by 10mm are uniformly adhered to the edge of the ceramic disc, and the distance between the centers of the aluminum nitride wafers and the edge of the ceramic disc is 1cm; the sum of the areas is 12 square centimeters, and the weight is pressurized and cooled to room temperature;
s3, sucking the ceramic disc stuck with the wafer to be processed on a clamp, placing the ceramic disc on a copper disc, dripping diamond liquid into the ceramic disc to perform copper polishing on the wafer, wherein the grain size of abrasive particles in the grinding liquid is 3 mu m, and the polishing pressure is 100g/cm 2 -200g/cm 2 The rotating speed of the large disc is 20 rpm-40 rpm;
s4, placing the copper polished wafer on a polyurethane polishing pad, and dropwise adding polishing solution to polish, wherein the polishing solution is silica sol polishing solution, and the polishing pressure is 300g/cm 2 ～500g/cm 2 The rotation speed of the large disc is 40 rpm-50 rpm.
The above experiment was repeated 30 times, the breakage rate of the polished wafer was less than 10%, and the surface roughness thereof could reach a level of less than 0.5nm.
Example 3
A method of polishing a small-sized aluminum nitride wafer, comprising the steps of:
s1, polishing 4 pieces of boron carbide polished aluminum nitride wafers with the diameter of 1 inch and the thickness difference of less than or equal to 5 mu m as wafers to be processed, placing the 4 pieces of aluminum nitride wafers and a ceramic disc together in a heating table for preheating at 110 ℃, wherein the flatness of the ceramic disc is 1-3 mu m;
s2, adhering wafers to be processed to the edge of a ceramic disc at equal intervals by using molten paraffin, wherein as shown in FIG. 3, a schematic diagram of a method for adhering 4 aluminum nitride wafers with 1 inch to the 4 inch ceramic disc is demonstrated, the distance between the center of each aluminum nitride wafer and the edge of the ceramic disc is 2cm, the sum of the areas is 20.3 square centimeters, and a weight is pressed and cooled to room temperature;
s3, sucking the ceramic disc stuck with the wafer to be processed on a clamp, placing the ceramic disc on a copper disc, dripping diamond liquid into the ceramic disc to perform copper polishing on the wafer, wherein the grain size of abrasive particles in the grinding liquid is 3 mu m, and the polishing pressure is 100g/cm 2 -200g/cm 2 The rotating speed of the large disc is 20 rpm-40 rpm;
s4, placing the copper polished wafer on a polyurethane polishing pad, and dropwise adding polishing solution to polish, wherein the polishing solution is silica sol polishing solution, and the polishing pressure is 500g/cm 2 ～600g/cm 2 The rotation speed of the large disc is 50 rpm-60 rpm.
The above experiment was repeated 30 times, the breakage rate of the polished wafer was less than 10%, and the surface roughness was less than 0.5nm.
Example 4
A method of polishing a small-sized aluminum nitride wafer, comprising the steps of:
s1, polishing a single piece of the 1-inch aluminum nitride wafer subjected to boron carbide grinding, placing a sapphire square piece with the thickness difference of less than or equal to 5 mu m and 4 pieces of 20mm multiplied by 20mm, the 1 piece of aluminum nitride wafer and a ceramic disc together into a heating table for preheating, wherein the preheating temperature is 110 ℃, and the flatness of the ceramic disc is 1-3 mu m;
s2, only 1 aluminum nitride wafer is used as a wafer to be processed, the aluminum nitride wafer is adhered to the center of a ceramic disc, 4 sapphire wafers with equal thickness are adhered to the edge of the ceramic disc at equal intervals to serve as auxiliary wafers, the center of each auxiliary wafer is 2cm away from the edge of the ceramic disc, the total area of each auxiliary wafer is 21.06 square centimeters, and the ceramic disc is pressurized and cooled to room temperature;
s3, sucking the ceramic disc stuck with the wafer to be processed on a clamp, placing the ceramic disc on a copper disc, dripping diamond liquid into the ceramic disc to perform copper polishing on the wafer, wherein the grain size of abrasive particles in the grinding liquid is 3 mu m, and the polishing pressure is 100g/cm 2 -200g/cm 2 The rotating speed of the large disc is 20 rpm-40 rpm;
s4, placing the copper polished wafer on a polyurethane polishing pad, and dropwise adding polishing solution to polish, wherein the polishing solution is silica sol polishing solution, and the polishing pressure is 500g/cm 2 ～600g/cm 2 The rotation speed of the large disc is 50 rpm-60 rpm.
An actual view of the polished aluminum nitride wafer is shown in fig. 7 (a).
The above experiment was repeated 30 times, the breakage rate of the polished wafer was less than 10%, and the surface roughness was less than 0.7nm.
Example 5
A method of polishing a small-sized aluminum nitride wafer, comprising the steps of:
s1, polishing a single aluminum nitride square sheet with the thickness of 10mm multiplied by 10mm after grinding by boron carbide, placing 4 sapphire wafers with the thickness difference of less than or equal to 5 mu m and a ceramic disc on a heating table for preheating at 110 ℃, wherein the flatness of the ceramic disc is 1-3 mu m;
s2, only 1 aluminum nitride wafer is used as a wafer to be processed, the wafer is adhered to the center of a ceramic disc, 4 sapphire wafers with equal thickness are adhered to the edge of the ceramic disc at equal intervals to be used as auxiliary wafers, as shown in FIG. 5, the total area of FIG. 5 is 21.26 square centimeters, and the ceramic disc is cooled to room temperature under pressure;
s3, sucking the ceramic disc stuck with the wafer to be processed on a clamp, placing the ceramic disc on a copper disc, dripping diamond liquid into the ceramic disc to perform copper polishing on the wafer, wherein the grain size of abrasive particles in the grinding liquid is 3 mu m, and the polishing pressure is 100g/cm 2 -200g/cm 2 The rotating speed of the large disc is 20 rpm-40 rpm;
s4, placing the copper polished wafer on a polyurethane polishing pad, and dropwise adding polishing solution to polish, wherein the polishing solution is silica sol polishing solution, and the polishing pressure is 500g/cm 2 ～600g/cm 2 The rotation speed of the large disc is 50 rpm-60 rpm.
A physical diagram of the polished aluminum nitride square sheet is shown in FIG. 7 (a).
The above experiment was repeated 30 times, the breakage rate of the polished wafer was less than 10%, and the surface roughness was less than 0.7nm.
Comparative example 1
A polishing method of a small-sized aluminum nitride wafer is different from that of example 2 in that step S2, a plurality of wafers are adhered to the center of a ceramic disk or unevenly adhered to the edge of the wafer with paraffin, as shown in fig. 6; step S3, copper polishing is carried out on a copper plate by using a diamond liquid with the diameter of 3 mu m, and the polishing pressure is 100g/cm 2 -200g/cm 2 The rotating speed of the large disc is 20 rpm-40 rpm; step S4, polishing on a polyurethane polishing pad by utilizing silica sol, wherein the polishing pressure is 300g/cm 2 ～500g/cm 2 The rotation speed of the large disc is 40 rpm-50 rpm.
The above experiment was repeated 30 times, the breakage rate of the polished wafer was higher than 20%, and the surface roughness was greater than 1nm. The experimental result shows that if a plurality of wafers are unevenly stuck on the edge of the ceramic disc, the breakage rate of the polished wafers is not very high, but the polishing effects of different areas of the wafers are different due to uneven stress of the wafers, and the surface roughness is higher.
Comparative example 2
A polishing method of a small-sized aluminum nitride wafer is different from that of example 4 in that no auxiliary sheet is used, and in step S2, a single wafer is stuck to the center of a ceramic disk with paraffin alone and then copper polishing and polishing are performed; step S3, copper polishing is carried out on a copper plate by using a diamond liquid with the diameter of 3 mu m, and the polishing pressure is 100g/cm 2 -200g/cm 2 The rotating speed of the large disc is 20 rpm-40 rpm; step S4, polishing on a polyurethane polishing pad by utilizing silica sol, wherein the polishing pressure is 500g/cm 2 ～600g/cm 2 The rotation speed of the large disc is 50 rpm-60 rpm. The wafer real estate after polishing is shown in fig. 7 (b) as an aluminum nitride wafer.
The experiment was repeated 30 times, the breakage rate of the polished wafer was higher than 40%, and the surface roughness was less than 0.7nm. The experimental result shows that the single wafer is stuck to the center of the ceramic disc without supporting auxiliary sheets to distribute polishing pressure, and the polished wafer has high breakage rate due to overlarge pressure. Although the roughness of the wafer is low, the removal amount is not controllable.
Comparative example 3
A polishing method of a small-sized aluminum nitride wafer is different from example 5 in that the polishing pressure in step S4 is 400-500g/cm 2 The rotation speed of the large disc is 60-70rmp. The wafer after polishing is shown in physical form in the aluminum nitride square in FIG. 7 (b).
The above experiment was repeated 30 times, the breakage rate of the polished wafer was higher than 20%, and the surface roughness was greater than 1nm. It can be seen from the experimental results that the chemical action and the mechanical action in the polishing process are not balanced due to the fact that the corresponding polishing pressure and the corresponding polishing rotating speed are not set, the polishing effect is reduced, the rotating speed is low, pressurization is needed, the rotating speed is needed to be increased, the mechanical action is increased, and the breakage rate of the wafer is increased due to the fact that the rotating speed and the high pressure are high.
Claims (10)
1. A method of polishing a small-sized aluminum nitride wafer, comprising the steps of:
step S1, if the number of small-size aluminum nitride wafers is less than 3, selecting sapphire or silicon carbide as an auxiliary wafer, and jointly using the small-size aluminum nitride wafers and the auxiliary wafer as wafers to be processed, so that the number of the wafers to be processed is at least 3, the thickness difference between the wafers to be processed is not more than 5 mu m, and the auxiliary wafer is a small-size wafer; grinding the small-size aluminum nitride wafer by using boron carbide;
s2, placing the wafer to be processed and the ceramic disc on a heating table for preheating; then, adhering wafers to be processed to the edge of a ceramic disc at equal intervals by using paraffin, and adhering the 1 or 2 small-sized aluminum nitride wafers to the center of the ceramic disc if more than 5 wafers to be processed have only 1 or 2 small-sized aluminum nitride wafers, and adhering other auxiliary wafers to the edge of the ceramic disc at equal intervals;
s3, sucking the ceramic disc in the step S2 on a clamp, placing the ceramic disc on a copper disc, and dripping diamond liquid to perform copper polishing on the wafer;
and S4, placing the copper polished wafer on a polyurethane polishing pad, and dropwise adding polishing liquid to polish the copper polished wafer.
2. The method of polishing small-sized aluminum nitride wafer according to claim 1, wherein the preheating temperature in step S2 is 100 ℃ to 130 ℃ and the flatness of the ceramic disc is 1 μm to 3 μm.
3. The polishing method of small-sized aluminum nitride wafer according to claim 1, wherein after the paraffin is melted by heating in step S2, the wafer to be processed is stuck on a ceramic plate, and then pressurized with a weight and cooled to room temperature.
4. The method for polishing small-sized aluminum nitride wafer according to claim 1, wherein the diamond liquid abrasive grains in step S3 have a grain size of 1 to 6 μm and a polishing pressure of 100g/cm 2 ～300g/cm 2 The rotation speed of the large disc is 20 rpm-40 rpm.
5. The method of claim 1, wherein the polishing liquid in step S4 is a silica sol polishing liquid.
6. The method for polishing small-sized aluminum nitride wafer according to claim 1, wherein the ceramic disk and jig have a diameter of 4 inches, and the total surface area of the wafer to be processed in step S1 is 11.4-45.6cm 2 Corresponding to a circular area of 1.5 inches to 3 inches in diameter.
7. The method of polishing small-sized aluminum nitride wafer according to claim 6, wherein the center of the wafer to be processed in step S2 is 1 to 3.5cm from the edge of the ceramic disk.
8. The method for polishing small-sized aluminum nitride wafer according to claim 6, wherein the polishing pressure in step S4 is 300g/cm 2 ～700g/cm 2 The rotation speed of the large disc is 40 rpm-70 rpm.
9. The method for polishing small-sized aluminum nitride wafer according to claim 8, wherein when the total surface area of the wafer to be processed is 11.4 to 20cm 2 The polishing pressure in the step S4 is 300-500 g/cm 2 The rotation speed of the large disc is 40-50 rpm.
10. The method for polishing small-sized aluminum nitride wafer according to claim 8, wherein when the total surface area of the wafer to be processed is 20-30cm 2 The polishing pressure in the step S4 is 500-600 g/cm 2 The rotation speed of the large disc is 50-60 rpm.
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| CN202311488693.9A CN117415681A (en) | 2023-11-09 | 2023-11-09 | Polishing method for small-size aluminum nitride wafer |
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| CN202311488693.9A CN117415681A (en) | 2023-11-09 | 2023-11-09 | Polishing method for small-size aluminum nitride wafer |
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| CN202311488693.9A Pending CN117415681A (en) | 2023-11-09 | 2023-11-09 | Polishing method for small-size aluminum nitride wafer |
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| Country | Link |
|---|---|
| CN (1) | CN117415681A (en) |
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2023
- 2023-11-09 CN CN202311488693.9A patent/CN117415681A/en active Pending
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