CN119495559A - Gallium antimonide polished wafer surface defect control process method - Google Patents
Gallium antimonide polished wafer surface defect control process method Download PDFInfo
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Abstract
The invention discloses a gallium antimonide polished wafer surface defect control process method, which relates to a wafer polishing technology, and comprises the steps of optimizing a crystal round-rolling circle process, and controlling the feed amount and the crystal moving rate of the crystal round-rolling circle to obtain a surface with compact crystal structure and good finish; the wafer edge polishing process comprises the steps of designing a crystal chamfering process, optimizing the number of grinding wheels, the number of chamfering turns and feeding speed of the grinding wheels in different states, designing the main positioning fillet radius of a wafer, changing the previous main edge sharp angle into a fillet so as to ensure that the main edge fillet can bear the action of external force and the problems of falling off, slag falling and the like are avoided, designing the gallium antimonide wafer edge end face polishing technology so as to obtain a compact, bright and non-chamfering track of an edge structure, optimizing three polishing processes of the gallium antimonide wafer, controlling the process of the system, stabilizing the structure of the wafer edge, greatly reducing the falling off of the wafer edge, reducing the final polishing 'dark scratch' of the wafer from 60% to 10%, and greatly improving the final polishing once-through rate.
Description
Technical Field
The invention belongs to the technical field of wafer polishing, and particularly relates to a gallium antimonide polished wafer surface defect control process method.
Background
III-V compound semiconductor materials are of great interest due to their advantages in optoelectronic device applications. Antimonide infrared electric devices show great application prospects in the fields of infrared imaging, medical diagnosis, resource exploration, gas detection, optical communication, thermophotovoltaics and the like by virtue of excellent performances, and become a current research hot spot. Gallium antimonide (GaSb) is taken as a typical III-V compound semiconductor material, the forbidden bandwidth is 0.725 eV, the lattice constant is 6.0959A, the gallium antimonide (GaSb) is matched with the III-V compound material with the lattice constant being 6.1A and ternary and quaternary antimony-containing compounds thereof, the wavelength range can be covered from near infrared to far infrared, and the gallium antimonide (GaSb) is an ideal substrate material for preparing antimonide infrared photoelectric devices. The GaSb single crystal wafer has direct influence on the performance of antimonide infrared electric devices, and the improvement of the device performance requires that the single crystal wafer has large size, lower defect density and better surface quality. In recent years, the development of antimonide infrared photoelectric technology is rapid, and especially the development and application of antimonide II type superlattice infrared focal plane detection technology greatly drive the development of GaSb materials, and more mechanisms and enterprises are also put into the research, development and production of GaSb single crystals.
The gallium antimonide single crystal wafer production mainly realizes the preparation of high-quality surfaces through processing technologies such as polishing, cleaning and the like. The GaSb material has higher chemical activity, is easy to oxidize, has higher requirements on surface preparation technology, and has higher processing difficulty than GaAs, inP and other materials. Along with the development of the device epitaxial process, the requirement on the surface performance of the monocrystalline wafer is more and more severe, and the preparation of the high-quality surface becomes the key of the development of the GaSb monocrystalline wafer. In order to meet the growth requirements of epitaxial materials, the surface of a single crystal wafer is required to have lower roughness, lower surface residual impurities and defects, lower surface oxide layer thickness and the like.
The traditional gallium antimonide wafer polishing method is chemical mechanical polishing, and the chemical mechanical polishing mechanism is that the material removal of the wafer surface is realized by combining chemical oxidation and mechanical grinding. In the chemical mechanical polishing process, a softening layer with lower hardness is generated on the surface of the wafer due to chemical oxidation, and meanwhile, the softening layer is removed through a mechanical grinding effect. Typical chemical-mechanical polishing is accomplished using nanoscale silica or alumina polishing slurries and processes that match the different polisher equipment.
The main defects on the surface of the existing large-diameter gallium antimonide chemical mechanical polishing sheet are dark scratch defects, particles and the like, the dark scratch defects are smaller, about a few microns, and can be observed under a 200-time microscope when different angles are changed under a strong light, and the dark scratch defects directly affect the later-stage epitaxy, so that the yield of detector devices is improved.
Coarse polishing and medium polishing of gallium antimonide wafers are influenced by polishing cloth and polishing agent, scratches and scratches which are visible macroscopically are easy to generate, and the distribution of the scratches and the scratches is crossed, straight lines and arcs are all about 10 microns or more. The scratch and scratch of the middle polishing can be removed through final fine polishing, but a macroscopic defect of dark scratch with a size of a few microns and different lengths is found in the fine polishing, and the defect is generated sometimes, the position and the length of the defect are all deteriorated differently, so that the once-through rate of the gallium antimonide wafer is directly influenced.
We analyzed the locations where "dark marks" were generated on the wafer surface after a large number of fine throws, the lengths, and found that the dark mark locations were changing, and the lengths were different in size. The shape of the wafer edge before chamfering and the wafer edge after fine polishing are observed under a microscope of 50-200 times, and the shape of the wafer edge is changed again, and the wafer edge after fine polishing has a plurality of small micron-nano-scale notches, so that the end face is uneven. The elimination method is adopted to eliminate the influence of polishing agent, liquid, cloth, particles and other factors, and finally the 'dark scratch' defect generated on the crystal surface by focusing is related to the generation of falling objects at the edge of the wafer.
Disclosure of Invention
In order to reduce the occurrence of falling objects at the edge of a wafer and reduce the occurrence of dark scratch influence of the falling objects on the surface of the wafer, the invention provides a gallium antimonide polished wafer surface defect control process method. The invention realizes the progress of the processing technology through two-step technological innovation and a plurality of-step technological optimization modes, and develops a novel gallium antimonide wafer surface defect control technological method, so that dark scratch is obviously reduced and lightened.
The technical scheme provided by the invention is that the gallium antimonide polished wafer surface defect control process method comprises the following steps:
s1, rolling an outer circle of a crystal;
S2, chamfering the wafer, namely designing the angle of an R angle of a grinding wheel according to the thickness of the wafer, determining the depth of an A1 and A2 surface, increasing the radius of the round angle of the left and right sides of the main and auxiliary positioning sides by more than 3 times on the basis of the prior art, changing the radius of the round angle of the left and right sides of the main and auxiliary positioning sides from the round angle to the round angle, improving the capability of bearing external force impact in the wafer polishing, reducing the risks of edge knocking, edge falling and slag falling of the left and right sides of the main positioning side of the wafer, carrying out rough chamfering by adopting a grinding wheel with the mesh number of more than or equal to 1800 meshes, controlling the feeding amount of the grinding wheel to be 0.2-0.4mm/min, carrying out fine chamfering by adopting a grinding wheel with the mesh number of more than or equal to 6000 meshes, controlling the feeding amount of the grinding wheel to be 0.2-0.4mm/min, checking under a fluorescent lamp after the fine chamfering, and detecting that the edge of the wafer is uniform without edge collapse and notch being qualified under a20 times profilometer microscope, and detecting that the accuracy of the A1 and the A2 surface and the R angle and the design value are qualified within a reasonable range;
s3, wafer chamfering chemical corrosion;
S4, mechanically polishing the wafer chamfer, namely, on domestic 6B single-sided polishing machine equipment, adopting grinding liquid with the grain diameter less than or equal to 100nm, adding an oxidant into the grinding liquid to prepare polishing liquid with the PH more than or equal to 8, placing black damping polishing cloth with the hardness less than or equal to 40 on a polishing machine turntable, vertically arranging the wafer in a manner of manually fixing the wafer, polishing the vertically arranged wafer on the polishing cloth, and carrying out chemical mechanical polishing on the chamfer of the gallium antimonide wafer for 60-120S in a manner of manually rotating the wafer, wherein the flow rate of the polishing liquid is 100-200 ml/min;
s5, polishing the wafer, wherein the polishing comprises rough polishing, medium polishing and fine polishing;
s6, cleaning the wafer;
s7, spin-drying the wafer;
s8, checking a wafer;
s9, storing the wafer.
In the further technical scheme, in S1, grinding wheels with the mesh number of more than or equal to 800 meshes are selected, the feed rate of the grinding wheels is less than or equal to 0.5mm/min, and the moving speed of crystals is less than or equal to 3mm/min.
The further technological scheme is that the solution with pH value of 5-6 is prepared with mineral acid solution, buffering agent and high purity water with resistivity of 18 megaohm, the chamfered wafer edge is chemically corroded at 18-24 deg.c for 20-30s, and the wafer edge is washed with high purity water and spun dry, and the wafer edge has no obvious adsorbed matter, grains and burrs and is no longer qualified.
The further technical scheme is as follows:
In S5, coarse polishing, wherein the hardness of the selected polishing cloth is less than or equal to 80, the grain diameter of the selected polishing liquid grinding liquid is less than or equal to 150nm, the PH value is 7-12, the polishing liquid grinding liquid is added with an oxidant to prepare polishing liquid with the PH value of 8-12, a wafer is fixed on a non-wax pad, the polishing upper disc pressure is less than or equal to 200g/cm 2, the rotating speed of a main disc is 40-80r/min, the flow rate of the polishing liquid is less than or equal to 400ml/min, the polishing removal amount is controlled to be 30-40 microns, and after coarse polishing, no obvious scratch, saw mark and the like are observed under a fluorescent lamp and then the polishing is carried out;
The hardness of the selected polishing cloth is less than or equal to 60, the grain diameter of the selected polishing liquid grinding liquid is less than or equal to 100nm, the PH value is more than or equal to 8, the polishing liquid with the PH value of 9-10 is prepared after an oxidant is added into the polishing liquid grinding liquid, the wafer is fixed on a non-wax pad, the polishing upper disc pressure is less than or equal to 150g/cm 2, the main disc rotating speed is 40-60r/min, the flow rate of the polishing liquid is 300-400ml/min, the polishing removal amount is less than or equal to 20 microns, after the polishing, no obvious scratch, saw lines and the like are observed under a strong light, and then the polishing enters the fine polishing;
The polishing method comprises the steps of fine polishing, wherein the hardness of selected polishing cloth is less than or equal to 40, the compression elasticity is 50-90, the opening diameter is more than or equal to 200 meshes, polishing liquid which is mainly used as an oxidant is selected, the PH value of the polishing liquid is 4-8, wafers are fixed on a wax-free pad, the polishing upper disc pressure is less than or equal to 100g/cm 2, the main disc rotating speed is 40-60r/min, the polishing liquid flow is 300-400ml/min, the polishing removal amount is less than or equal to 10 microns, and no obvious scratches, bright scratches, dark scratches, NG, liquid medicine and the like enter cleaning after fine polishing is observed under a strong light.
In the further technical scheme, in S6, the lower disc is rapidly flushed after the wafer is polished, the pressure of water guns on two sides of the main disc is more than or equal to 1.5kg, megasonic waves assist the high-purity water gun to flush the surface in a comprehensive coverage way in different directions, the flowing direction is consistent, and the phenomena of flushing reflux and the like cannot occur.
The further technical scheme is that under a 40W power strong light lamp and under a 20 times of microscope, whether dark scratch, dirty points, dark points, medicinal liquid, medicinal dirt and other defects exist on the surface of the wafer or not is checked from different angles.
The further technical proposal is that the wafer storage room is hundred-grade environment, the room temperature is controlled at 18-22 ℃ and the humidity is controlled at less than or equal to 60%
Compared with the prior art, the invention has the beneficial effects that:
1. Firstly, the crystal circle rolling process is optimized, the crystal surface with a fine and compact structure is obtained, the number of grinding wheels selected in the process is more than or equal to 800 meshes, the feeding amount of the grinding wheels is about 10 times slower than the previous crystal circle rolling speed, the moving speed of the crystal is 5-8 times slower than the previous crystal circle rolling speed, the obtained crystal surface has no tool mark and no grinding wheel grinding track, the crystal surface is fine and smooth, and the stress of the crystal is effectively released.
2. The process for chamfering the edge of the gallium antimonide wafer is optimally designed, a better chamfering end face is obtained, a soft grinding wheel structure for chamfering the gallium antimonide wafer is firstly formulated, the mesh number is adjusted, the feed rate, the moving speed and the like are adjusted in the process, and the smoothness of the edge of the wafer is ensured.
3. The main positioning edge and the right and left fillet radius of the wafer are mostly sharp angles, and the sharp angles are easy to collide with corners and drop slag when being impacted by external force in the prior art.
4. According to the invention, the gallium antimonide edge chamfer wafer is subjected to chemical corrosion of inorganic acid or ammonia water series, so that the compact structure of the wafer edge is ensured, a loose layer is not provided, the edge is ensured not to fall off slag and fall off, and the generation of dark scratch on the finish polishing surface is reduced.
5. The invention designs the chemical mechanical polishing of the edge end face of the wafer to obtain the high end face with shallow damaged layer and smooth finish, so as to prevent the occurrence of dark scratch caused by slag falling of the edge of the wafer due to the influence of external force, and simultaneously control the front surface and the like which are easy to be back-diffused when various substances are epitaxial due to the rough edge.
6. The invention optimizes the wafer polishing process, selects proper polishing pressure, filters polishing liquid for multiple times, balances chemical removal and mechanical removal force, adjusts the flow and the rotating speed of the polishing liquid so as to effectively control the edge drop of the wafer, easily generate the problem of 'dark scratch' on the surface of the wafer, and effectively improves the once-through rate of the wafer.
Drawings
FIG. 1 is a view of the surface of a crystal rolled with an outer circle and chemically etched in accordance with the present invention.
Figure 2 is a wafer bevel edge prior to the optimization process of the present invention.
Figure 3 is a wafer bevel edge after the optimization process of the present invention.
FIG. 4 shows the right and left sharp angles of the main locating edge before the optimization process of the invention.
Fig. 5 shows the right and left sharp angles of the main positioning edge after the optimization process of the invention.
Fig. 6 is a microscope 10 x 10 "dark scribe" length prior to the optimization process of the present invention.
Fig. 7 is a view of a microscope 10 x 10 "dark scribe" width prior to the optimization process of the present invention.
Fig. 8 shows microscope 10 x 10, with no "dark marks" on the wafer surface after the optimization process of the present invention.
Detailed Description
In order that those skilled in the art will better understand the present invention, a technical solution in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in which it is apparent that the described embodiments are only some embodiments of the present invention, not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the present invention without making any inventive effort, shall fall within the scope of the present invention.
The embodiment discloses a gallium antimonide polished wafer surface defect control process method, which comprises the following steps:
1. The process of rolling the outer circle of the crystal is optimized.
The mode hardness of the gallium antimonide material is 1.5 and softer than gallium arsenide and indium phosphide, so that the process of rolling the outer circle of the crystal is optimized. The number of the selected grinding wheels is more than or equal to 800 meshes, the feeding amount of the grinding wheels is about 10 times slower than the prior crystal rolling circle speed, the moving speed of the crystal is 5-8 times slower than the prior crystal, and the obtained crystal has no tool mark, no grinding track of the grinding wheels, is finer and finer, has compact structure and effectively releases the stress of the crystal.
2. The wafer chamfering process is optimized.
Typically, semiconductor silicon, gallium arsenide and indium phosphide wafers are chamfered into R-shape or T-shape, and most of the wafers are R-shape, the radius of the R-shape is considered according to the final thickness of the wafer, and the angle of the R angle of the grinding wheel is designed according to the thickness of the wafer to determine the depth of the A1 and A2 planes. R-shaped chamfer angles are selected.
The wafer chamfering process is divided into rough chamfering and fine chamfering, the number of grinding wheels is different, the process is optimized, the grinding wheels with the number of meshes larger than or equal to 1800 are adopted for rough chamfering, the feeding amount in the chamfering process is controlled to be 0.2-0.4mm/min, and the number of chamfering turns is larger than or equal to 2. Adopting a grinding wheel with the granularity of more than or equal to 6000 meshes to carry out fine chamfering, controlling the feed amount to be 0.2-0.4mm/min, and controlling the number of chamfering turns to be more than or equal to 2. After the fine chamfering is finished, checking that the edge of the wafer has no edge breakage and notch under a fluorescent lamp, and obtaining the qualified wafer with uniform edge and good roughness. And detecting the A1 and A2 surface amplitude under a 20-time profiler microscope, wherein the error between the R angle precision and the design value is qualified in a reasonable range. Because we optimize the technology, change the rough chamfering grinding wheel from 800 meshes in the past to be more than or equal to 1800 meshes, change the fine grinding wheel from 4000 meshes in the past to be more than or equal to 6000 meshes, the chamfering process slows down the feed amount, increases the number of rounds of chamfering, has small edge roughness, has a better structure and is not easy to fall off the end face of the broken slag.
3. The size of the left and right fillet radius of the main locating edge and the auxiliary locating edge is innovatively designed.
At present, the radius of the round angle of the wafer main positioning edge is set to be less than or equal to 3mm, the shape of the round angle is mostly a sharp angle, when the main positioning edge and the auxiliary positioning edge are considered to be the sharp angle, the external impact force born by the round angle is smaller, the problem that the edge is easy to fall off is solved, the round angle radius of the wafer main positioning edge and the auxiliary positioning edge is enlarged to be more than 3 times, the corner is changed into a round angle from the previous sharp angle, and the problems of knocking edges, falling slag and the like are greatly reduced.
4. Chemical corrosion is optimized, and the loose layer at the edge of the wafer is removed.
In general, after chamfering, the wafer is chemically etched to remove an edge damage layer and a loose layer, and a new process method is optimized, and the wafer is etched by using an acidic and alkaline solution which is stable and has a relatively slow chemical reaction speed, so that the wafer with low edge roughness and a relatively smooth surface can be obtained.
Specifically, inorganic acid solution with concentration of more than or equal to 10% and buffering agent are adopted, 18 megaohm high-purity water is added to prepare chemical etching solution, the PH value of the chemical etching solution is 5-6, the wafer edge after chamfering is chemically etched for about 20-30S in an environment of 18-24 ℃, and then the wafer edge is spin-dried after being washed by the high-purity water. Thereby removing residues, particles, metal impurities, etc. on the wafer surface and edge. After spin-drying, the wafer surface is observed by naked eyes under a fluorescent lamp, the edge is brighter, no obvious adsorbate, particles, burrs and the like are generated, and the obtained wafer edge surface has finer finish than before corrosion.
5. Optimizing the polishing of the wafer end face and improving the wafer finish.
The wafer edge polishing can increase the compactness of a crystal structure, control the problems of residue and easy falling of the end face of the wafer edge, at present, only large-diameter silicon is used for edge chemical mechanical polishing, but other materials are not started, and the chemical mechanical polishing is adopted to polish the edge of the gallium antimonide wafer, so that a polished end face with better smoothness is obtained.
Specifically, on domestic 6B single-sided polishing machine equipment, grinding liquid (silicon dioxide colloid solution, pH value is more than or equal to 9) with particle size less than or equal to 100nm is adopted, oxidant (hydrogen peroxide, sodium dichloroisocyanurate, sodium bicarbonate, tartaric acid and organic acid.) is added to prepare polishing liquid, the pH value is more than or equal to 8, domestic polishing cloth is black damping cloth, the hardness is less than or equal to 40, wafers are vertically arranged in a manner of manually fixing the wafer end faces, the rotating speed of a main disc of the polishing machine is less than or equal to 5r/min, the flow rate of the polishing liquid is 100-200ml/min, the chemical mechanical polishing is carried out on the gallium antimonide wafer end faces for 60S-120S, high-purity water is washed cleanly, and single-piece spin drying and dehydration are carried out. And observing the edge end face under a fluorescent lamp, wherein the end face is uniform, shiny and fine, and the product is qualified. And observing the chamfer track left by the chamfer with smooth, bright and no chamfer edge on the end face of the photo under a 20-time microscope. The chemical mechanical polishing of the wafer edge provides a basis for wafer polishing, edge falling prevention is provided, the polishing of the large-diameter silicon wafer edge is fully realized, but the polishing of the gallium antimonide wafer edge is not realized (mainly because gallium antimonide is soft, fragile and too high in polishing difficulty, and the polishing method of the silicon wafer edge is not suitable for gallium antimonide).
6. The wafer polishing process is optimized.
The wafer polishing process is optimized, and three SEEDFAM-32G single-sided polishing machines of the same model are used for respectively carrying out rough, medium and fine chemical mechanical polishing on 2-inch 12-piece/disc and 3-inch 5-piece/disc gallium antimonide wafers.
The polishing cloth used for rough polishing is colorless white cloth with proper hardness, the hardness is less than or equal to 80, the polishing grinding liquid (silicon relatively bulk solution PH value is 7-12, the grain diameter is less than or equal to 150 nm) and oxidant (sodium dichloroisocyanurate, sodium phosphate, sodium pyrophosphate and organic acid.) are added, the PH value is controlled between 8-12, a wafer is fixed on a non-wax pad, the polishing upper disc pressure is less than or equal to 200g/cm 2, the main disc rotating speed is 40-80r/min, the flow is less than or equal to 400ml/min, the polishing removal amount is 30-40 microns, and the polishing is carried out after no obvious scratch, saw lines and the like are observed under a fluorescent lamp.
The polishing cloth used for polishing the gallium antimonide wafer is a black damping cloth with the hardness less than or equal to 60, the pH value of a silicon dioxide colloid solution with the grain diameter less than or equal to 100nm is more than or equal to 8, an oxidant (hydrogen peroxide, sodium dichloroisocyanurate, sodium phosphate, sodium pyrophosphate, organic acid and inorganic acid.) is added to form the polishing solution, the pH value is controlled between 9 and 10, the wafer is fixed on a non-wax pad, the polishing solution is supplied by a peristaltic pump, two filter cores less than or equal to 0.5 micron are serially filtered and are shunted to a main disc at 300-400 ml/cm through a latex tube, the pressure of a polishing disc on the upper disc is less than or equal to 150g/cm 2, the rotating speed of the main disc is 40-60r/min, the polishing removal amount is less than or equal to 20 microns, no obvious scratch exists after observation under a strong light, and the polishing solution enters a fine polishing.
Finally, the polishing agent is prepared from black damping cloth with the hardness less than or equal to 40, the compression elasticity rate of 50-90%, the opening diameter of more than or equal to 200 meshes, the main components of polishing liquid are oxidants (hydrogen peroxide, potassium hypochlorite, sodium dichloroisocyanurate, organic acid, inorganic acid, sodium hypochlorite and tartaric acid), the PH value of the polishing agent is 4-8, a wafer is fixed on a wax-free pad, the polishing liquid is supplied by a peristaltic pump, a plurality of filter cores less than or equal to 0.3 micrometers are serially filtered and distributed on a main disc by a latex tube at 300-400 ml/min, the pressure of the upper disc polishing disc is less than or equal to 100g/cm 2, the rotating speed of the main disc is 40-60r/min, the polishing removal amount is less than or equal to 10 micrometers, and no obvious scratches, bright scratches, dark scratches, NG, liquid medicine and the like enter cleaning under a strong light.
After polishing, the wafer surface is quickly lifted up, and the high-purity water with megasonic assistance and water pressure more than or equal to 1.5KG is flushed by double guns, so that a stable process is obtained.
7. And (5) cleaning the wafer.
The wafer bottom plate after fine polishing is rapidly flushed, the pressure of water guns on two sides of a main plate is more than or equal to 1.5KG, megasonic waves assist the high-purity water guns in different directions, the comprehensive coverage flushing surface is less than or equal to 30S, the flowing water directions are consistent, and the phenomenon of flushing reflux and the like cannot occur.
8. And (5) checking the wafer.
And checking whether defects such as dark scratch, dirty points, dark points, liquid medicine, medicine dirt and the like exist on the surface of the wafer from different angles under a 40W power strong light and under a 20-time microscope.
9. And storing the wafer.
The wafer storage room is hundred-grade environment, the room temperature is controlled at 18-22 ℃, and the humidity is controlled at less than or equal to 60%.
In summary, the invention firstly optimizes the crystal round-rolling circle process, controls the feed quantity of the crystal round-rolling circle and the crystal moving speed to obtain the surface with compact crystal structure and good finish, designs the crystal round-rolling process, optimizes the number of grinding wheels for round-rolling and the feed speed of the round-rolling circle under different states, analyzes the influence of the round-rolling radius of the main and auxiliary positioning edges of the wafer on the shape of the round-rolling circle of the main and auxiliary edges, designs the round-rolling radius of the main positioning edge of the wafer, changes the previous sharp angle of the main edge into the round-rolling circle, thereby ensuring that the round-rolling circle of the main edge can bear the action of external force and the problems of falling, slag falling and the like, analyzes the edge polishing of the large-diameter silicon wafer to reduce various particles and residues which are easy to stay at the edge, and the like.
Claims (7)
1. The gallium antimonide polished wafer surface defect control process method is characterized by comprising the following steps:
s1, rolling an outer circle of a crystal;
S2, chamfering the wafer, namely designing the angle of the R angle of the grinding wheel according to the thickness of the wafer, and determining the depth of the A1 and A2 surface widths; the method comprises the steps of increasing the radius of a round angle of a main locating side and a secondary locating side by more than 3 times on the basis of the current, changing the radius of the round angle of the main locating side and the secondary locating side from a sharp angle to a round angle, carrying out rough chamfering by adopting a grinding wheel with the mesh number of more than or equal to 1800 meshes, controlling the feeding amount of the grinding wheel to be 0.2-0.4mm/min, carrying out fine chamfering by adopting a grinding wheel with the mesh number of more than or equal to 6000 meshes, after the fine chamfering, checking under a fluorescent lamp, ensuring that the edge of a wafer is uniform, and ensuring that no edge and no notch are qualified, and detecting that errors between the surface widths A1 and A2 and R angle precision and a design value are qualified in a reasonable range under a 20-time profilometer microscope;
s3, wafer chamfering chemical corrosion;
S4, mechanically polishing the wafer chamfer, namely, on domestic 6B single-sided polishing machine equipment, adopting grinding liquid with the grain diameter less than or equal to 100nm, adding an oxidant into the grinding liquid to prepare polishing liquid with the PH more than or equal to 8, placing black damping polishing cloth with the hardness less than or equal to 40 on a polishing machine turntable, vertically arranging the wafer in a manner of manually fixing the wafer, polishing the vertically arranged wafer on the polishing cloth, and carrying out chemical mechanical polishing on the chamfer of the gallium antimonide wafer for 60-120S in a manner of manually rotating the wafer, wherein the flow rate of the polishing liquid is 100-200 ml/min;
s5, polishing the wafer, wherein the polishing comprises rough polishing, medium polishing and fine polishing;
s6, cleaning the wafer;
s7, spin-drying the wafer;
s8, checking a wafer;
s9, storing the wafer.
2. The process for controlling surface defects of gallium antimonide polished wafers according to claim 1, wherein in S1, grinding wheels with the mesh number of more than or equal to 800 mesh are selected, the feed rate of the grinding wheels is less than or equal to 0.5mm/min, and the movement rate of crystals is less than or equal to 3mm/min.
3. The process for controlling surface defects of a gallium antimonide polished wafer according to claim 1, wherein a solution with a pH value of 5-6 is prepared by adopting an inorganic acid solution, a buffer and high-purity water with a resistivity of 18 megaohms, the wafer edge after chamfering is chemically corroded for 20-30s at 18-24 ℃, then the wafer edge is washed and dried by high-purity water, and no obvious adsorbate, particles and burrs at the wafer edge are qualified by naked eye observation under a fluorescent lamp.
4. The process for controlling surface defects of gallium antimonide polished wafers according to claim 1, wherein the process comprises the steps of:
In S5, coarse polishing, wherein the hardness of the selected polishing cloth is less than or equal to 80, the grain diameter of the selected polishing liquid grinding liquid is less than or equal to 150nm, the PH value is 7-12, the polishing liquid grinding liquid is added with an oxidant to prepare polishing liquid with the PH value of 8-12, a wafer is fixed on a non-wax pad, the polishing upper disc pressure is less than or equal to 200g/cm 2, the rotating speed of a main disc is 40-80r/min, the flow rate of the polishing liquid is less than or equal to 400ml/min, the polishing removal amount is controlled to be 30-40 microns, and after coarse polishing, no obvious scratch, saw mark and the like are observed under a fluorescent lamp and then the polishing is carried out;
The hardness of the selected polishing cloth is less than or equal to 60, the grain diameter of the selected polishing liquid grinding liquid is less than or equal to 100nm, the PH value is more than or equal to 8, the polishing liquid with the PH value of 9-10 is prepared after an oxidant is added into the polishing liquid grinding liquid, the wafer is fixed on a non-wax pad, the polishing upper disc pressure is less than or equal to 150g/cm 2, the main disc rotating speed is 40-60r/min, the flow rate of the polishing liquid is 300-400ml/min, the polishing removal amount is less than or equal to 20 microns, after the polishing, no obvious scratch, saw lines and the like are observed under a strong light, and then the polishing enters the fine polishing;
The polishing method comprises the steps of fine polishing, wherein the hardness of selected polishing cloth is less than or equal to 40, the compression elasticity is 50-90, the opening diameter is more than or equal to 200 meshes, polishing liquid which is mainly used as an oxidant is selected, the PH value of the polishing liquid is 4-8, wafers are fixed on a wax-free pad, the polishing upper disc pressure is less than or equal to 100g/cm 2, the main disc rotating speed is 40-60r/min, the polishing liquid flow is 300-400ml/min, the polishing removal amount is less than or equal to 10 microns, and no obvious scratches, bright scratches, dark scratches, NG, liquid medicine and the like enter cleaning after fine polishing is observed under a strong light.
5. The process for controlling surface defects of a gallium antimonide polished wafer according to claim 1, wherein in S6, the lower disc is rapidly flushed after the wafer is polished, the pressure of water guns on two sides of a main disc is more than or equal to 1.5kg, megasonic waves assist a high-purity water gun to flush the surface in different directions in a comprehensive coverage manner for less than or equal to 30S, the flowing direction is consistent, and the phenomenon of flushing reflux and the like cannot occur.
6. The method for controlling surface defects of a gallium antimonide polished wafer according to claim 1, wherein in S8, whether defects such as dark marks, dirty points, dark points, liquid medicine, medicine dirt and the like exist on the surface of the wafer is checked from different angles under a 40W power strong light and under a 20-fold microscope.
7. The process for controlling surface defects of gallium antimonide polished wafers according to claim 1, wherein in S9, the wafer storage room is a hundred-grade environment, the room temperature is controlled at 18-22 ℃, and the humidity is controlled at less than or equal to 60%.
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