CN115070512A - Double-polishing process and device for germanium wafer and germanium wafer - Google Patents
Double-polishing process and device for germanium wafer and germanium wafer Download PDFInfo
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- CN115070512A CN115070512A CN202210244203.XA CN202210244203A CN115070512A CN 115070512 A CN115070512 A CN 115070512A CN 202210244203 A CN202210244203 A CN 202210244203A CN 115070512 A CN115070512 A CN 115070512A
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Images
Classifications
-
- 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
- B24B29/00—Machines or devices for polishing surfaces on work by means of tools made of soft or flexible material with or without the application of solid or liquid polishing agents
- B24B29/02—Machines or devices for polishing surfaces on work by means of tools made of soft or flexible material with or without the application of solid or liquid polishing agents designed for particular workpieces
Abstract
The application discloses two processes, device and germanium wafer of throwing of germanium wafer for carry out two-sided polishing to the germanium wafer simultaneously, wherein, include: the first rough polishing procedure adopts first rough polishing liquid and first polishing cloth; the second rough polishing procedure adopts second rough polishing liquid and first polishing cloth; the first fine polishing process adopts first fine polishing solution and second polishing cloth; the second fine polishing process adopts second fine polishing solution and second polishing cloth; the relationship of the rotating speed in each process is as follows: the first rough polishing procedure is more than the second rough polishing procedure and more than the first fine polishing procedure and more than the second fine polishing procedure; the hardness of the first polishing cloth is greater than that of the second polishing cloth; the polishing temperature in each procedure is 35-40 ℃. According to the double-polishing process of the germanium wafer, the combination mode of twice rough polishing and twice fine polishing is adopted, matching between chemical polishing and mechanical polishing is achieved by matching different parameters, rapid polishing of the germanium wafer is achieved, and good quality of the polished surface is obtained.
Description
Technical Field
The present application relates generally to the field of germanium wafer technology, and more particularly to a double-polishing process and apparatus for a germanium wafer, and a germanium wafer.
Background
Germanium is an off-white metal, glossy and hard, belongs to the carbon family, has obvious non-metallic properties, has stable chemical properties, and does not react with air or water vapor at normal temperature. The content of germanium in the earth crust is about 0.0007%, which is one of the most dispersed elements in the earth crust, and there is almost no more concentrated germanium ore, which is widely used in the fields of electronics, optics, chemical engineering, biomedicine, energy and other high and new technologies.
Polishing of germanium wafers is an important part of the process and directly affects the optical properties of the product. However, the roughness of the polished wafer is high, the processing efficiency is low, most domestic enterprises can only polish the single surface of the part, and the problems of low processing efficiency, poor surface quality and flatness and the like exist.
Disclosure of Invention
In view of the above-mentioned defects or shortcomings in the prior art, it is desirable to provide a double polishing process and apparatus for a germanium wafer, and a germanium wafer, which can adopt double-side polishing, reduce the surface roughness of the polished wafer, and improve the processing efficiency.
In a first aspect, the present application provides a double polishing process for a germanium wafer for simultaneously double-side polishing the germanium wafer, including:
a first rough polishing process, wherein a first rough polishing solution and a first polishing cloth are adopted;
a second rough polishing process, wherein a second rough polishing solution and a first polishing cloth are adopted;
a first fine polishing process, wherein a first fine polishing solution and a second polishing cloth are adopted;
a second fine polishing step, wherein a second fine polishing solution and a second polishing cloth are adopted;
the pH values of the first rough polishing solution and the second rough polishing solution are alkaline; the pH values of the first fine polishing solution and the second fine polishing solution are acidic; the relationship of the rotating speed in each process is as follows: the first rough polishing procedure is more than the second rough polishing procedure and more than the first fine polishing procedure and more than the second fine polishing procedure; the hardness of the first polishing cloth is greater than that of the second polishing cloth; the polishing temperature in each procedure is 35-40 ℃.
Optionally, the first rough polishing solution includes: the abrasive material 0, an oxidizing agent and an alkaline pH regulator, wherein the alkaline pH regulator is organic alkali; the pH value of the first rough polishing solution is 8-11.
Optionally, the second rough polishing solution includes: the polishing solution comprises a No. 0 abrasive, an oxidizing agent and an alkaline pH regulator, wherein the alkaline pH regulator comprises organic amine alkali and diammonium hydrogen phosphate, and the pH value of the second rough polishing solution is 8-11.
Optionally, the concentration relationship of abrasive 0 in the first rough polishing solution and the second rough polishing solution is as follows: the first rough polishing solution is less than the second rough polishing solution.
Optionally, the first fine polishing solution includes: the abrasive material comprises a No. 1 abrasive material and an acidic pH regulator, wherein the acidic pH regulator is organic acid; the pH value of the first fine polishing solution is 4-6.
Optionally, the second fine polishing solution includes: the abrasive material No. 2 and the acidic pH regulator are organic acids; the pH value of the second fine polishing solution is 4-6.
Optionally, the grain size relationship of the abrasive in each polishing solution is as follows: abrasive No. 0 > abrasive No. 1 > abrasive No. 2.
Optionally, the first polishing cloth is polyurethane or the polyurethane is filled with cerium oxide, and the second polishing cloth is a fiber composite.
In a second aspect, the present application provides a double polishing apparatus for a germanium wafer, for performing a double polishing process for the germanium wafer as described in any one of the above, comprising:
the polishing device comprises an upper disc and a lower disc, wherein polishing cloth is fixedly arranged on the upper disc and the lower disc; the upper disc is provided with an opening for spraying polishing solution;
and the planetary wheel disc is positioned between the upper disc and the lower disc, and is provided with a through hole for accommodating a germanium wafer.
In a third aspect, the present application provides a germanium wafer, which is prepared by using the double-polishing process of the germanium wafer as described in any one of the above.
The technical scheme provided by the embodiment of the application can have the following beneficial effects:
according to the double-polishing process of the germanium wafer, the combination mode of twice rough polishing and twice fine polishing is adopted, matching between chemical polishing and mechanical polishing is achieved by matching different parameters, rapid polishing of the germanium wafer is achieved, and good quality of the polished surface is obtained.
Drawings
Other features, objects and advantages of the present application will become more apparent upon reading of the detailed description of non-limiting embodiments made with reference to the following drawings:
fig. 1 is a flow chart of a double-polishing process for a germanium wafer according to an embodiment of the present application;
fig. 2 is a schematic structural diagram of a double-polishing apparatus for a germanium wafer according to an embodiment of the present application;
fig. 3 is a schematic structural diagram of a pinion disk according to an embodiment of the present application.
Detailed Description
The present application will be described in further detail with reference to the following drawings and examples. It is to be understood that the specific embodiments described herein are merely illustrative of the invention and are not to be construed as limiting the invention. It should be noted that, for convenience of description, only the portions related to the present invention are shown in the drawings.
It should be noted that the embodiments and features of the embodiments in the present application may be combined with each other without conflict. The present application will be described in detail below with reference to the embodiments with reference to the attached drawings.
Chemical Mechanical Polishing (CMP) is a processing technique that combines chemical etching with mechanical removal to obtain a bright "mirror" with local surface flatness and extremely low surface roughness on a wafer, and has the advantages of high processing efficiency, low production cost, and the like. During polishing, the germanium wafer surface is oxidized into soluble oxide by the oxidant in the polishing liquid, and the soft corrosion layer on the wafer surface is removed by the relative motion among the polishing pad, the wafer and the abrasive under the action of mechanical pressure.
The photoelectronic wafer is polished on both sides to obtain high machining efficiency and excellent machined surface smoothness and finish, and during polishing, the part is set inside the planetary wheel sheet and driven by the central and edge gears to rotate and the upper and lower discs and the planetary wheel sheet rotate relatively.
The path of motion is more complex because the part is "floating" between the planet wheel plate and the disc. The technology has the greatest advantages that the processing efficiency is high, the processing of the upper surface and the lower surface of a part can be simultaneously finished at one time, and the polishing disc is easy to have a larger size (such as the caliber of 1m or more), so that a plurality of parts can be processed simultaneously. In addition, since the parts are not subjected to bonding stress, the size of the polishing disk is generally much larger than that of the parts, and relatively high flatness and parallelism are easily obtained.
Because the texture of the germanium crystal is soft, scratches are easy to scratch even if the germanium crystal is polished on one side, and how to obtain higher surface quality becomes the key of double-side polishing of the germanium wafer. In the method, the germanium wafer processing technology is optimized through deep system research on a double-sided polishing process mechanism and polishing process parameters, so that the polishing efficiency is improved, and the production cost is reduced. In the research, it was found that the key to the double-side polishing technique was how to obtain a higher surface quality, and the factors affecting the surface quality included:
the composition, particle size and pH of the polishing solution;
the material, hardness and structure of the polishing cloth;
polishing process parameters (polishing pressure, rotation speed, polishing temperature, etc.).
Referring in detail to fig. 1, the present application provides a double polishing process for a germanium wafer for simultaneous double-side polishing of the germanium wafer, comprising:
a first rough polishing process, wherein a first rough polishing solution and a first polishing cloth are adopted;
a second rough polishing process, wherein a second rough polishing solution and a first polishing cloth are adopted;
a first fine polishing process, wherein a first fine polishing solution and a second polishing cloth are adopted;
a second fine polishing step, wherein a second fine polishing solution and a second polishing cloth are adopted;
the pH values of the first fine polishing solution and the second fine polishing solution are acidic; the relationship of the rotating speed in each process is as follows: the first rough polishing procedure is more than the second rough polishing procedure and more than the first fine polishing procedure and more than the second fine polishing procedure; the hardness of the first polishing cloth is greater than that of the second polishing cloth; the polishing temperature in each procedure is 35-40 ℃.
In the embodiment of the application, a combination mode of two times of rough polishing and two times of fine polishing is adopted, and different parameters are matched to realize matching between chemical polishing and mechanical polishing, so that the rapid polishing of the germanium wafer is realized, and better quality of the fine polished surface is obtained.
In the first rough polishing procedure, the pH value of the first rough polishing solution is alkaline; the first rough polishing solution comprises: the abrasive material 0, an oxidizing agent and an alkaline pH regulator, wherein the alkaline pH regulator is organic alkali; the pH value of the first rough polishing solution is 8-11. The first polishing cloth is made of polyurethane or polyurethane material filled with cerium oxide. In the first rough polishing process, the rotating speed is 20-30 rpm.
In the specific setting, the abrasive is white corundum micropowder hydrosol and the oxidant is hydrogen peroxide; the organic base is one or more of triethanolamine, hydroxyethyl ethylenediamine, tetramethylammonium hydroxide and triethylamine, and in the embodiment of the application, the particle size of the abrasive 0 is 50-130 nm. The concentration of the first crude polishing solution is calculated by weight percent: 25-30% of No. 0 abrasive; 0.5 to 2.0 percent of oxidant; 0.5 to 2.0 percent of alkaline pH regulator.
In the embodiments of the present application, the polishing solution may further include other components, such as a surfactant and/or a chelating agent, and the like, which is not limited in the present application. The chelating agent is 8-hydroxyquinoline; the surfactant is selected from nonionic surfactants, such as: FA/OI type surfactants, JFC, OII-7((C1OH21-C6H4-O-CH2CH2O)7-H), etc.
In the first rough polishing stage, when the first polishing solution is used for polishing, chemical removal effect is generated on the germanium wafer, germanium and an oxidant generate oxidation effect, and soluble germanium hydroxide water solution is generated through further action in an alkaline environment, so that the chemical formula is shown as follows.
In mechanical polishing, the germanium wafer surface is actually polished by an abrasive, the microstructure with roughness formed on the wafer surface is subjected to plastic deformation or brittle failure through the action of the abrasive, a polishing cloth with low rotation speed, low abrasive concentration and high hardness is adopted in the mechanical aspect of the first rough polishing stage so as to combine with the chemical etching action, and the setting of the combination temperature enables the first rough polishing process to rapidly remove the larger microstructure on the wafer surface.
The lower rotating speed is adopted, so that the polishing cloth can be stably contacted with the abrasive, the polishing cloth is contacted with the abrasive at an overlarge surface rotating speed to generate vibration and the like, the abrasive generates scratches, ravines and the like on the flat surface of the workpiece to aggravate the surface irregularity of the workpiece, and in addition, the material can be prevented from being broken or brittle failure and the like in the surface layer of the workpiece. The polishing cloth with higher hardness can increase the mechanical polishing force, and can increase the pressure of the abrasive in the polishing solution and the polishing force.
In the second rough polishing process, the pH of the second rough polishing solution is alkaline, and the second rough polishing solution includes: the polishing solution comprises a No. 0 abrasive, an oxidizing agent and an alkaline pH regulator, wherein the alkaline pH regulator comprises organic amine alkali and diammonium hydrogen phosphate, and the pH value of the second rough polishing solution is 8-11. In the second rough polishing process, the rotating speed is 30-40 rpm.
In the second rough polishing process, the polishing solution and the germanium surface are subjected to chemical action, such as the chemical formulas (1) and (2), and the polishing speed of the germanium wafer is further increased by adjusting the stability of pH in the second rough polishing stage.
In the embodiment of the application, the organic amine alkali is used as the pH regulator, so that the pollution of metal particles in the inorganic alkali to the surface of the germanium wafer can be effectively avoided; the diammonium hydrogen phosphate is used as a pH maintaining function, so that when the pH value is reduced due to the consumption of organic amine alkali in the polishing process, the stability and the balance of the alkaline pH value are maintained through the hydrolysis and ionization functions of the diammonium hydrogen phosphate, and the polishing effect is improved. For example, organic amine bases: the content ratio of the diammonium hydrogen phosphate is (2-5) to 1.
The concentration of the second rough polishing solution is as follows by weight percent: 30-45% of No. 0 abrasive; 0.5 to 2.0 percent of oxidant; 0.5 to 2.0 percent of organic amine alkali; 0.1 to 1.0 percent of diammonium hydrogen phosphate.
In the embodiment of the present application, the first polishing cloth is made of polyurethane or the polyurethane is filled with cerium oxide. It should be noted that, in the present application, the polyurethane polishing cloth filled with cerium oxide is adopted, and the hardness is increased, and at the same time, the chemical polishing performance of the polishing cloth can also be increased.
By including cerium oxide in the first polishing cloth, the chemical action of the surface of the germanium wafer is involved in the first rough polishing step and/or the second rough polishing step.
2(CeO 2 ) - +(GeO) 2+ →Ce 2 O 3 ·GeO 2 (5)
Firstly, germanium and cerium oxide are oxidized to generate intermediate product (GeO) 2+ And (CeO) 2 ) - Then, the two intermediate products continue to chemically react, Ce 2 O 3 And GeO 2 The mixture of (a) is in an amorphous form and is very soft and thus can be easily removed by abrasive particles on the abrasive disc, thereby achieving a polishing effect on the germanium wafer.
In an embodiment of the present application, the concentration relationship of abrasive 0 in the first rough polishing solution and the second rough polishing solution is: the first rough polishing solution is less than the second rough polishing solution.
In the polishing process, the large-size microstructures on the surface of the wafer can be quickly removed along with the completion of the first rough polishing stage, the small-size microstructures are required to be quickly removed in the second rough polishing stage to reduce the roughness of the surface of the wafer, and in the second rough polishing stage, the large-size microstructures are removed to increase the contact area between the abrasive and the workpiece. Pits and ridges with sharp edges on the surface of the rough-polished workpiece are not completely removed. In the embodiment of the application, the rapid rough polishing is realized by simultaneously increasing the physical grinding effect and the chemical grinding effect.
In the first finish polishing step, the first finish polishing liquid includes: the abrasive material comprises a No. 1 abrasive material and an acidic pH regulator, wherein the acidic pH regulator is organic acid; the pH value of the first fine polishing solution is 4-6. In the first fine polishing process, the rotating speed is 40-50 rpm.
Illustratively, the particle size of the No. 1 fine abrasive is 20 to 50 nm. The concentration of the first fine polishing solution is as follows by weight percent: 30-45% of No. 1 abrasive; 0.5 to 2.0 percent of acid pH regulator.
In the first fine polishing process, the rotating speed is increased relative to the rotating speed in the rough polishing stage, the mechanical polishing speed and the polishing precision are improved, and the acid polishing solution is adopted in the stage, so that the alkaline residue on the surface of the workpiece in the rough polishing stage can be neutralized, and the excessive corrosion of the alkaline residue on the surface of the polished crystal in the first stage is prevented. In the embodiment of the present application, the chemical polishing effect is achieved by oxidizing germanium and oxygen, as shown in chemical formulas (6) to (7), and removing the oxide after the reaction by the action of the abrasive and the polishing cloth.
It should be noted that in the examples of the present application, the reaction product Ge (OH) is used 4 Is poorly soluble in water, and therefore, it is necessary to remove the reaction product by the mechanical action of the frictional force of the second polishing cloth with the abrasive in the first finish polishing stage. The fiber composite material used in the second polishing cloth in the embodiment of the present application may be superfine animal fiber, plant fiber, or synthetic fiber material, etc., and the present application does not limit this.
After the germanium wafer is subjected to two-step rough polishing, the grain size of abrasive grains is large, the distance between the abrasive grains is large, the surface of a grinding disc is rough, the cutting depth of each abrasive grain is increased, the roughness value of a corresponding processed germanium sheet is large, but the processing efficiency is high, namely the removal rate of the material is high. In the first fine polishing step, the abrasive grains are slightly smaller in size, and the pits and peaks left in the rough machining step are gradually ground away. And by combining chemical and mechanical actions, after the first fine polishing process, relatively round groove marks and protrusions can be formed on the surface of the workpiece.
Preferably, the grain size relationship of the abrasive in each polishing solution is as follows: abrasive No. 0 > abrasive No. 1 > abrasive No. 2. Illustratively, the particle size of the No. 0 abrasive is 50-130 nm; the grain diameter of the No. 1 fine abrasive is 20-50 nm; the grain diameter of the No. 2 fine abrasive is 0.1-20 nm.
The No. 1 abrasive is one or more of white corundum, alumina, diamond and silicon dioxide. The No. 2 abrasive is one or more of white corundum, alumina, diamond and silicon dioxide. In the embodiments of the present application, the polishing solution may further include other components, such as a surfactant and/or a chelating agent, and the like, which is not limited in the present application. The chelating agent is 8-hydroxyquinoline; the surfactant is selected from nonionic surfactants, such as: FA/OI type surfactants, JFC, etc.
In the second fine polishing step, the second fine polishing liquid includes: the abrasive material No. 2 and the acidic pH regulator are organic acids; the pH value of the second fine polishing solution is 4-6. And the concentration of the No. 2 grinding material in the second fine polishing solution is greater than that of the No. 1 grinding material in the first fine polishing solution. In the second fine polishing process, the rotating speed is 50-60 rpm.
Illustratively, the size of the No. 2 fine abrasive is 0.1 to 20 nm. The concentration of the second fine polishing solution is calculated by weight percent: 40-50% of No. 1 abrasive; 0.5 to 2.0 percent of acid pH regulator.
In the present embodiment, the second polishing slurry continues to chemically interact with the surface of the germanium wafer, as described in equations (6) - (7) above. The precision of mechanical polishing is improved by adopting the fine grinding material with higher concentration in the second fine polishing procedure, meanwhile, the polishing cloth made of the fiber composite material with lower hardness is adopted, reaction products are removed through the grinding effect, and the effect of chemical grinding in the fine polishing stage is weakened, and the physical grinding effect matched with the chemical grinding effect is weakened at the same time, so that the roughness of the surface of the workpiece is further reduced. According to the experimental result that the machined surface roughness of the workpiece changes along with the granularity of the abrasive particles, the surface roughness value of the germanium wafer becomes smaller along with the thinning of the granularity of the abrasive particles.
In the second fine polishing process, the surface of the workpiece is further polished by matching the grinding material with smaller granularity at a higher rotating speed, so that an excellent workpiece surface is obtained. After the second fine polishing process, the surface quality of the workpiece can be improved, the mechanical property of the wafer can be improved, the phenomenon of breakage is not easy to occur, and surface defects such as pits and cracks are not easy to generate.
It should be noted that, in the embodiment of the present application, the adopted rotation speed is increased in each process step, and in a specific setting, the constant rotation speed may be used at each stage, and of course, the rotation speed may be gradually increased in each process step, or the rotation speed is increased in a stepwise manner in each process step, which is not limited in the present application. By adopting the mode of gradually increasing the rotating speed in each procedure, the matching of chemistry and mechanical polishing can be realized, and the better polishing effect is improved. In the initial stage of the process, the chemical speed is slow, the rotating speed can be relatively slow, and along with the acceleration of the chemical speed, the rotating speed can be relatively fast, so that the matching between the chemical speed and the rotating speed is improved, and the polishing rate is increased.
In the application embodiment, the number of revolutions per stage is not limited, and in different embodiments, the number of revolutions per stage is appropriately adjusted according to the degree of grinding and the area of the germanium wafer, and when the application is performed, the total number of revolutions per stage of the double polishing process is positively correlated with the grain size of the germanium wafer, for example, when the grain size of the germanium wafer is 7mm to 10mm, the total number of revolutions is preferably 1000 to 1500 revolutions; when the grain diameter of the germanium wafer is 40mm to 50mm, the total rotation number is preferably 6000 to 8000 turns.
It should be noted that, in the embodiments of the present application, operations such as cleaning a wafer may be further included between the processes. The influence of residual abrasive, polishing solution and the like in the previous step on the next step of polishing is prevented, and naturally, during the setting, cleaning can be selectively added between two processes, such as the second rough polishing process and the first fine polishing process. This is not limited by the present application.
Example one
A. First rough polishing process
White corundum polishing solution with the granularity of 80nm is adopted, the concentration of grinding materials (white corundum micro-powder particles in the polishing solution) is 20%, 1.0% of oxidant by mass fraction and 1.0% of organic alkali by mass fraction are added; the pH of the polishing solution was 10.
A first polishing cloth was used.
The polishing temperature is 37 ℃; the polishing pressure is 50 Pa; the rotating speed is 25 rpm; the polishing time was 5 min.
B. Second rough polishing step
Adopting white corundum polishing solution with the granularity of 80nm, wherein the concentration of an abrasive (white corundum micro-powder particles in the polishing solution) is 35%, and adding 2% by mass of an oxidant, 2.0% by mass of organic amine alkali and 0.5% by mass of diammonium hydrogen phosphate; the pH of the polishing solution was 10.
A first polishing cloth is used.
The polishing temperature is 37 ℃; the polishing pressure is 50 Pa; the rotating speed is 35 rpm; the polishing time was 8 min.
C. First fine polishing step
Adopting diamond polishing solution with the granularity of 30nm, wherein the concentration of an abrasive (diamond micro-powder particles in the polishing solution) is 35 percent, and adding organic acid with the mass fraction of 1 percent; the pH of the polishing solution was 5.
A second polishing cloth was used.
The polishing temperature is 37 ℃; the polishing pressure is 50 Pa; the rotating speed is 45 rpm; the polishing time was 5 min.
D. Second fine polishing step
Adopting diamond polishing solution with the granularity of 10nm, wherein the concentration of an abrasive (diamond micro-powder particles in the polishing solution) is 50 percent, and adding organic acid with the mass fraction of 1 percent; the pH of the polishing solution was 5.
A second polishing cloth was used.
The polishing temperature is 37 ℃; the polishing pressure is 50 Pa; the rotating speed is 55 rpm; the polishing time was 8 min.
Example two
A. First rough polishing step
Adopting white corundum polishing solution with the granularity of 80nm, wherein the concentration of an abrasive (white corundum micro-powder particles in the polishing solution) is 30%, and adding an oxidant with the mass fraction of 2% and an organic base with the mass fraction of 2%; the pH of the polishing solution was 11.
A first polishing cloth was used.
The polishing temperature is 37 ℃; the polishing pressure is 50 Pa; the rotating speed is 30 rpm; the polishing time was 5 min.
B. Second rough polishing step
White corundum polishing solution with the granularity of 80nm is adopted, the concentration of grinding materials (white corundum micro-powder particles in the polishing solution) is 45%, wherein 2% of oxidant, 2% of organic amine alkali and 1% of diammonium hydrogen phosphate are added; the pH of the polishing solution was 11.
A first polishing cloth was used.
The polishing temperature is 37 ℃; the polishing pressure is 50 Pa; the rotating speed is 40 rpm; the polishing time was 8 min.
C. First fine polishing step
Adopting diamond polishing solution with the granularity of 30nm, wherein the concentration of an abrasive (diamond micro-powder particles in the polishing solution) is 40 percent, and adding organic acid with the mass fraction of 2 percent; the pH of the polishing solution was 4.
A second polishing cloth was used.
The polishing temperature is 37 ℃; the polishing pressure is 50 Pa; the rotating speed is 50 rpm; the polishing time was 5 min.
D. Second fine polishing step
Adopting diamond polishing solution with the granularity of 1nm, wherein the concentration of an abrasive (diamond micro-powder particles in the polishing solution) is 50 percent, and adding organic acid with the mass fraction of 2 percent; the pH value of the polishing solution is 4;
adopting a second polishing cloth;
the polishing temperature is 37 ℃; the polishing pressure is 50 Pa; the rotating speed is 60 rpm; the polishing time is 8 min;
the surface roughness of the polished germanium wafers in the two examples was measured by microscope, and the roughness in the range of 10 μm by 10 μm obtained from the experiment in each example is shown in table 1, and it can be seen from table 1 that the chemical mechanical polishing method provided by the present invention can obtain a lower roughness of the polished surface.
TABLE 1
| Group of | Surface roughness (Ra, unit nm) |
| Example one | 0.523 |
| Example two | 0.458 |
As shown in fig. 2-3, the present application provides a double-polishing apparatus for a germanium wafer, for performing a double-polishing process for the germanium wafer as described in any one of the above, comprising:
the polishing device comprises an upper disc 1 and a lower disc 2, wherein polishing cloth 9 is fixedly arranged on the upper disc 1 and the lower disc 2; the upper plate 1 is provided with an opening 8 for spraying polishing liquid.
And the planetary wheel disc 3 is positioned between the upper disc 1 and the lower disc 2, and a through hole 7 for accommodating a germanium wafer 4 is formed in the planetary wheel disc 3.
The germanium wafer 4 is arranged on the planetary wheel disc 3 through the mounting block 5, the germanium wafer 4 can be conveniently placed in and taken out, and the planetary wheel disc 3 is provided with the mounting hole 6 for fixing the mounting block 5. When in use, a plurality of mounting holes 6 are formed in each planetary gear 3 and used for fixing the mounting block 5, and the through holes 7 in the mounting block 5 can comprise different types, so that the germanium wafers 4 in different types can be polished conveniently. When polishing, different germanium wafers 4 can be polished only by adjusting the mounting block 5, the mounting is simple, the operation is convenient, and the processing speed is improved.
In the embodiment of the application, because a four-step polishing mode is adopted and different polishing solutions and polishing cloths are adopted, four double polishing devices can be adopted during setting, but the application is not limited to the four double polishing devices, one or more double polishing devices can be adopted and combined with cleaning equipment, and selection can be performed during application.
When applied, for example, include:
1) the external and internal impurities of the machine are cleaned by disposable water to achieve the purpose of cleaning.
2) And putting the workpiece to be polished into the planetary wheel.
3) Starting the equipment and injecting the polishing solution.
4) And performing double-sided polishing, namely performing a first rough polishing process, a second rough polishing process, a first fine polishing process and a second fine polishing process according to the method provided in the embodiment of the application.
5) And after finishing polishing, cleaning the workpiece.
The application provides a germanium wafer which is characterized by being prepared by adopting the double-polishing process of the germanium wafer.
It is to be understood that the terms "length," "width," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," and the like are used in an orientation or positional relationship indicated in the drawings for convenience in describing the invention and to simplify the description, and are not intended to indicate or imply that the device or element so referred to must be in a particular orientation, constructed or operated in a particular orientation, and is not to be construed as limiting the invention.
Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the present invention, "a plurality" means two or more unless specifically defined otherwise.
Unless defined otherwise, technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. Terms such as "disposed" and the like, as used herein, may refer to one element being directly attached to another element or one element being attached to another element through intervening elements. Features described herein in one embodiment may be applied to another embodiment, either alone or in combination with other features, unless the feature is otherwise inapplicable or otherwise stated in the other embodiment.
The present invention has been described in terms of the above embodiments, but it should be understood that the above embodiments are for purposes of illustration and description only and are not intended to limit the invention to the scope of the described embodiments. It will be appreciated by those skilled in the art that many variations and modifications may be made to the teachings of the invention, which fall within the scope of the invention as claimed.
Claims (10)
1. A double polishing process for a germanium wafer for simultaneous double side polishing of the germanium wafer, comprising:
a first rough polishing process, wherein a first rough polishing solution and a first polishing cloth are adopted;
a second rough polishing process, wherein a second rough polishing solution and a first polishing cloth are adopted;
a first fine polishing process, wherein a first fine polishing solution and a second polishing cloth are adopted;
a second fine polishing step, wherein a second fine polishing solution and a second polishing cloth are adopted;
the relationship of the rotating speed in each process is as follows: the first rough polishing procedure is more than the second rough polishing procedure and more than the first fine polishing procedure and more than the second fine polishing procedure; the hardness of the first polishing cloth is greater than that of the second polishing cloth; the polishing temperature in each procedure is 35-40 ℃.
2. The double polishing process of a germanium wafer as claimed in claim 1, wherein the pH of the first and second rough polishing solutions is alkaline, the first rough polishing solution comprising: the abrasive material 0, an oxidizing agent and an alkaline pH regulator, wherein the alkaline pH regulator is organic alkali; the pH value of the first rough polishing solution is 8-11.
3. The double polishing process for a germanium wafer of claim 2, wherein the second rough polishing solution comprises: the polishing solution comprises a No. 0 abrasive, an oxidizing agent and an alkaline pH regulator, wherein the alkaline pH regulator comprises organic amine alkali and diammonium hydrogen phosphate, and the pH value of the second rough polishing solution is 8-11.
4. The double polishing process for a germanium wafer according to claim 3, wherein the concentration relationship of abrasive 0 in the first rough polishing solution and the second rough polishing solution is as follows: the first rough polishing solution is less than the second rough polishing solution.
5. The double polishing process of a germanium wafer of claim 3, wherein the first fine polishing solution and the second fine polishing solution have an acidic pH, the first fine polishing solution comprising: the abrasive material comprises a No. 1 abrasive material and an acidic pH regulator, wherein the acidic pH regulator is organic acid; the pH value of the first fine polishing solution is 4-6.
6. The double polishing process for a germanium wafer of claim 5, wherein the second fine polishing solution comprises: the abrasive material No. 2 and the acidic pH regulator are organic acids; the pH value of the second fine polishing solution is 4-6.
7. The double polishing process for a germanium wafer as claimed in claim 6, wherein the grain size relationship of the abrasive in each polishing solution is: abrasive No. 0 > abrasive No. 1 > abrasive No. 2.
8. The double polishing process for a germanium wafer as claimed in claim 1, wherein the first polishing cloth is polyurethane or polyurethane filled with cerium oxide, and the second polishing cloth is a fiber composite.
9. A double-polishing apparatus for a germanium wafer, for performing a double-polishing process of the germanium wafer as claimed in any one of claims 1 to 8, comprising:
the polishing device comprises an upper disc and a lower disc, wherein polishing cloth is fixedly arranged on the upper disc and the lower disc; the upper disc is provided with an opening for spraying polishing solution;
and the planetary wheel disc is positioned between the upper disc and the lower disc, and is provided with a through hole for accommodating a germanium wafer.
10. A germanium wafer, prepared by the double-polishing process of the germanium wafer as claimed in any one of claims 1 to 8.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210244203.XA CN115070512B (en) | 2022-03-11 | Double-polishing process and device for germanium wafer and germanium wafer |
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| Application Number | Priority Date | Filing Date | Title |
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| CN202210244203.XA CN115070512B (en) | 2022-03-11 | Double-polishing process and device for germanium wafer and germanium wafer |
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