A chemical mechanical polishing method for the side and edge of a bulk semiconductor

Abstract

The present application relates to a kind of chemical mechanical polishing method for bulk semiconductor side and edge.The method specifically includes the following steps: the bulk semiconductor to be polished is firmly clamped in fixture, and at least one fixture is connected with polishing disc;The included angle of fixture and polishing disc is adjusted to side polishing state or edge polishing state;Coarse polishing liquid is introduced into the polisher, and the side or edge of bulk semiconductor is mechanically coarsely polished;Fine polishing liquid is introduced into the polisher, and the side or edge of bulk semiconductor is chemically mechanically finely polished;Bulk semiconductor is removed, and the above operation is repeated, and the other side and edge of bulk semiconductor are chemically mechanically polished.Compared with prior art, the present application can realize the synchronous chemical mechanical polishing of the side and edge of multiple bulk semiconductor samples.

Description

Technical Field

[0001] This invention relates to the field of semiconductor materials technology, and in particular to a chemical mechanical polishing method for the sides and edges of bulk semiconductors. Background Technology

[0002] Silicon carbide, gallium nitride, and silicon-based bulk substrates are core materials for power electronic devices, while perovskite, cadmium telluride, and cadmium zinc telluride are key substrates in the fields of photovoltaics and infrared detection. The polishing quality of the sides and edges of these bulk semiconductors directly determines the performance and yield of the devices.

[0003] Chemical mechanical polishing (CMP) is a core process for achieving precision machining of semiconductor materials, but existing technologies have many shortcomings in polishing these materials, as follows: (1) Low polishing efficiency: Existing side polishing technology is mostly single-piece polishing mode. For perovskite photovoltaic substrates and cadmium zinc telluride detection substrates that need to be prepared on a large scale, only one sample can be processed per batch. The equipment utilization rate is low and cannot meet the requirements of industrial batch processing.

[0004] (2) Manual polishing leads to product quality control issues and limits the applicability of the process: Hard bulk semiconductors such as silicon carbide and gallium nitride are brittle and prone to chipping, while soft and brittle bulk semiconductors such as perovskite, cadmium telluride, and cadmium zinc telluride are prone to microcracks and crystal damage. These defects all require manual polishing. This method is not only labor-intensive and inefficient, but also prone to irregular polishing angles and depths, resulting in excessive surface roughness of silicon substrates. It also cannot simultaneously adapt to the processing characteristics of hard and soft and brittle semiconductors, significantly reducing the yield of various bulk semiconductor products and limiting the material applicability of the polishing process.

[0005] (3) Insufficient adaptability and durability of traditional fixtures: Polishing fixtures are mostly made of metal, which are prone to corrosion and rust in acidic (such as perovskite polishing oxalic acid system) or alkaline (such as gallium nitride polishing ammonia water system) environments, which will contaminate the polishing liquid and semiconductor surface. In addition, metal fixtures are bulky, making it difficult to clamp fragile materials such as zinc cadmium telluride and their service life is also short.

[0006] (4) Single polishing process has performance defects: Although mechanical polishing has a fast removal rate, it will cause serious surface scratches to silicon carbide and silicon substrates; when using simple chemical mechanical polishing, the oxidant in the polishing liquid will soak the perovskite grain boundary and the shallow cadmium telluride layer for a long time, causing diffusion pollution and damaging the photoelectric properties of the material.

[0007] (5) High cost of polishing slurry: Traditional polishing uses polishing slurry to spray the entire polishing pad. For gallium nitride and zinc cadmium telluride samples of different sizes, the entire polishing pad needs to be wetted. A large amount of polishing slurry is wasted in non-processing areas, which increases the cost of industrial processing.

[0008] CN117245457A discloses a substrate polishing method that employs a combination of mechanical polishing and chemical mechanical polishing to mechanically polish the substrate edges to a roughness of less than 10 nm. This is followed by coarse and fine polishing using acidic or alkaline polishing slurries to ensure an edge surface roughness of less than 0.1 nm, removing damaged layers and defects. However, this method is only suitable for single-edge processing of circular wafers and cannot simultaneously process all sides and edges of bulk semiconductors in batches. The full-area spray polishing slurry results in significant material waste, and the metal fixtures are prone to contaminating the soft and brittle zinc zinc cadmium telluride crystals. Therefore, it still cannot achieve integrated, low-damage batch polishing of the sides and edges of multiple bulk semiconductors.

[0009] CN113172483A discloses a method and apparatus for center-supply chemical mechanical polishing (CMP) of semiconductor materials. This method employs a center-supply CMP approach, controlling the polishing slurry pressure and tool load, and combining bonded abrasives, small grinding heads, and disc-type hydrodynamic polishing technology to achieve thinning, semi-precision polishing, and ultra-precision polishing of semiconductor workpieces. Bonded abrasive polishing pads, porous materials without abrasives, and hydrodynamic polishing discs are used respectively, and the liquid film pressure and velocity distribution are adjusted to remove material. However, this approach is only suitable for polishing the front surface of wafers, lacking angle adjustment fixtures for edge-oriented polishing. Insufficient edge polishing slurry supply and poor removal uniformity, coupled with the lack of a buffer clamping structure, easily cause zinc-cadmium telluride (CdTe) to fracture. It still cannot achieve simultaneous batch polishing of multiple sides and edges of bulk semiconductors.

[0010] Therefore, given the technical challenges of chemical mechanical polishing (CMP) of the sides and edges of bulk semiconductors such as silicon carbide, gallium nitride, silicon-based bulk substrates, perovskite, cadmium telluride, and cadmium zinc telluride, there is an urgent need to develop novel CMP methods for the sides and edges of bulk semiconductors. Summary of the Invention

[0011] The purpose of this invention is to overcome at least one of the defects of the prior art and provide a chemical mechanical polishing method for the sides and edges of bulk semiconductors.

[0012] The objective of this invention can be achieved through the following technical solutions: This invention provides a chemical mechanical polishing method for the sides and edges of bulk semiconductors, specifically including the following steps: S1: Securely clamp the block semiconductor to be polished in the fixture, and connect at least one fixture to the polishing disk; S2: Adjust the angle between the fixture and the polishing pad to the side polishing state or the edge polishing state; S3: Introduce the coarse polishing slurry into the polishing machine to mechanically coarsely polish the sides or edges of the bulk semiconductor; S4: Introduce fine polishing slurry into the polishing machine to perform chemical mechanical polishing on the sides or edges of the bulk semiconductor; S5: Remove the bulk semiconductor and repeat the operations of S1 to S4 to perform chemical mechanical polishing on the other sides and edges of the bulk semiconductor.

[0013] Further, in step S1, the fixture specifically includes a housing, a first limiting piece and a second limiting piece disposed inside the housing, and a polishing liquid hose disposed on the outer wall of the housing.

[0014] Furthermore, the housing is made of acid and alkali resistant materials such as polyvinyl fluoride, which can be adapted to acidic and alkaline polishing environments, solving the problem of corrosion and rust in traditional metal clamps. It is also lightweight, flexible in operation, and can meet the clamping needs of various block semiconductors, extending the service life of the clamps and reducing equipment maintenance costs.

[0015] Furthermore, the first limiting piece is connected to the top surface of the housing via an adjustable screw to limit the top of the bulk semiconductor.

[0016] Furthermore, the second limiting piece is connected to one side wall of the housing via an adjustable screw to limit the corresponding side of the bulk semiconductor.

[0017] Furthermore, rubber gaskets are connected to the first limiting plate, the second limiting plate, and the other side wall of the housing that contacts the bulk semiconductor. The cushioning design of the fluororubber gaskets can effectively prevent chipping of hard and brittle materials such as silicon carbide and gallium nitride, as well as the generation of microcracks in soft and brittle perovskite materials.

[0018] Furthermore, polishing fluid hoses are provided on both outer walls of the housing.

[0019] Furthermore, the polishing fluid hose is secured by several protruding slots on the housing.

[0020] Furthermore, one end of the polishing fluid hose is connected to the polishing fluid spray control system of the polishing machine.

[0021] Furthermore, in step S1, the clamp is connected to the positioning frame on the polishing disc via an angle adjustment screw to adjust the angle between the clamp and the polishing disc.

[0022] Furthermore, in the side polishing state, the angle between the fixture and the polishing disc is 180°.

[0023] Furthermore, in the edge polishing state, the angle between the fixture and the polishing disc is 30-60°.

[0024] Furthermore, in step S1, the fixtures are evenly distributed on the polishing disc.

[0025] Furthermore, in the side-polished state, the height difference Δh of the exposed block semiconductor samples in each fixture is ≤0.5mm.

[0026] Furthermore, in the edge polishing state, the rotation angle difference Δθ between each fixture is ≤5°.

[0027] Furthermore, in step S3, the coarse polishing liquid is an aqueous solution of abrasive particles, and the concentration of abrasive particles is 5-15 wt%.

[0028] Furthermore, the abrasive particles are one or more of aluminum oxide, silicon dioxide, diamond, magnesium oxide, and cerium oxide.

[0029] Furthermore, the particle size of the abrasive particles ranges from 1 to 5 μm.

[0030] Furthermore, in step S3, the polishing pressure of the mechanical rough polishing is 80-120 g / cm. 2 .

[0031] Furthermore, in step S3, the mechanical coarse polishing disc rotates at a speed of 50-100 r / min.

[0032] Furthermore, in step S3, the mechanical rough polishing time is 15-30 minutes.

[0033] Further, in step S4, the fine polishing liquid is composed of the following raw materials in the following mass percentages: 6-12wt% abrasive particles, 0.4-2wt% hydrogen peroxide, 0.5-1.5wt% sodium hypochlorite, 0.3-1wt% dispersant, and 0.4-1.2wt% complexing agent.

[0034] Furthermore, the abrasive particles are one or more of aluminum oxide, silicon dioxide, diamond, magnesium oxide, and cerium oxide, and the particle size range of the abrasive particles is 1-5 μm.

[0035] Furthermore, the dispersant is one or more of polyethylene glycol, polyvinylpyrrolidone, sodium citrate, and Triton TX-100.

[0036] Furthermore, the complexing agent is one or more of malic acid, citric acid, tartaric acid, and lactic acid.

[0037] Furthermore, the fine polishing solution has two pH types: acidic and alkaline. The pH value can be adjusted to 4-6 or 8-10 respectively using a weak acid or weak alkaline solution.

[0038] Furthermore, the weak base is ammonia or sodium carbonate.

[0039] Furthermore, in step S4, the polishing pressure of the chemical mechanical polishing is 80-120 g / cm. 2 .

[0040] Furthermore, in step S4, the rotation speed of the polishing disc in the chemical mechanical polishing process is 50-100 r / min.

[0041] Furthermore, in step S4, the polishing time for the chemical mechanical polishing is 2-5 minutes.

[0042] Compared with the prior art, the present invention has the following technical advantages: (1) This invention uses a specially designed fixture to simultaneously polish multiple block semiconductor samples in a single operation, breaking through the limitations of the traditional single-piece polishing mode and significantly improving the efficiency of industrial processing of materials such as silicon carbide and perovskite. Furthermore, by changing the angle between the fixture and the polishing disc, selective polishing of the material's sides or edges can be achieved. This invention further utilizes a two-step process of mechanical polishing and short-time chemical mechanical polishing to ensure the material removal rate and avoid the shallow surface diffusion contamination of cadmium telluride and cadmium zinc telluride caused by prolonged immersion in oxidants. At the same time, it allows the silicon substrate to obtain excellent surface flatness, effectively improving product yield and the optoelectronic and mechanical properties of the material.

[0043] (2) The fixture of the present invention is made of polyvinyl fluoride in one piece to form the fixture shell, and is equipped with fluororubber gasket to achieve buffer clamping. At the same time, the position of the limiting plate is adjusted by the internal hex screw to adapt to block semiconductor samples of different sizes. The angle between the fixture and the positioning frame is adjusted by the cross screw to meet the different angle requirements of side and edge polishing.

[0044] (3) The present invention achieves synchronous clamping of multiple block semiconductors through a fixture, strictly controls the difference in exposed sample height Δh ≤ 0.5 mm during side polishing and the difference in fixture rotation angle Δθ ≤ 5° during edge polishing, and ensures polishing uniformity.

[0045] (4) In this invention, a coarse polishing solution prepared with alumina abrasive and deionized water is first used for mechanical polishing. Then, an oxidant and complexing agent are added to the coarse polishing solution to prepare a fine polishing solution. The chemical mechanical polishing time is controlled within 5 minutes, taking into account both the material removal rate and the surface quality.

[0046] (5) The present invention uses the fluororubber hose that comes with the fixture to spray the polishing liquid only on the sample to be processed area, without wetting the entire polishing pad, effectively avoiding waste of polishing liquid and significantly saving the consumable cost of polishing materials such as silicon carbide and gallium nitride; at the same time, connecting to the polishing machine spray control system can realize the automated supply of polishing liquid. Attached Figure Description

[0047] Figure 1 This is a schematic diagram of the fixture of the present invention.

[0048] Figure 2 This is a schematic diagram of the side polishing process of the present invention.

[0049] Figure 3 This is a schematic diagram of the edge polishing process during the present invention.

[0050] Figure 4 This is a schematic diagram of the present invention when multiple clamps are used.

[0051] Figure 5 This is a schematic diagram illustrating the polishing process of the present invention.

[0052] Figure 6 This is a comparison image of the side surface of the sample before and after polishing in an application example of the present invention.

[0053] Explanation of markings in the diagram: 1-Bulk semiconductor; 2-Clamp, 2.1-Housing, 2.2-First limiting piece, 2.3-Second limiting piece, 2.4-Polishing fluid hose, 2.5-Adjustable screw, 2.6-Rubber gasket; 3-Polishing disc, 3.1-Positioning bracket; 4- Angle adjustment screw. Detailed Implementation

[0054] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. These embodiments are based on the technical solution of the present invention and provide detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments.

[0055] In this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicating orientation or positional relationships, are based on the orientation or positional relationships shown in the accompanying drawings and are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention; the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance; furthermore, unless otherwise explicitly specified and limited, the terms "installed," "connected," and "linked" should be interpreted broadly, for example, they can be fixed connections, detachable connections, or integral connections; they can be mechanical connections or electrical connections; they can be direct connections or indirect connections through an intermediate medium; they can be internal connections between two elements. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0056] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0057] To address the technical challenges of chemical mechanical polishing of the sides and edges of bulk semiconductors such as silicon carbide, gallium nitride, silicon-based bulk substrates, perovskite, cadmium telluride, and cadmium zinc telluride, this invention aims to solve the following problems: (1) Solve the problem of low efficiency when adapting the existing single-wafer polishing mode to various types of bulk semiconductors, realize the synchronous polishing of multiple samples, and improve the efficiency of industrial processing.

[0058] (2) Solve the quality defects such as silicon carbide edge chipping, perovskite microcracks, and cadmium telluride crystal damage caused by manual grinding and polishing. At the same time, break through the limitations of existing processes that cannot take into account both hard and soft brittle semiconductor processing, realize automated and standardized polishing of bulk semiconductors with different characteristics, ensure the processing accuracy and yield of various materials, and make the polishing method have a wider range of material compatibility.

[0059] (3) Solve the problems of poor corrosion resistance and inconvenient operation of traditional metal clamps in acidic and alkaline polishing environments, and provide polishing clamps that are suitable for various block semiconductor clamping needs, are lightweight, easy to operate and have a long service life.

[0060] (4) Solve the problem of surface scratches caused by single polishing process, reduce the problem of oxidant diffusion pollution, optimize polishing process to take into account material removal rate and surface flatness, and ensure the optoelectronic and mechanical properties of semiconductor materials.

[0061] (5) Solve the problem of polishing slurry waste, realize the precise supply of polishing slurry in various block semiconductor processing areas, and reduce industrial processing costs.

[0062] The above implementation methods will be described in more detail below with reference to specific embodiments.

[0063] Unless otherwise specified, the reagents, methods, instruments, and equipment used in this invention are conventional in the art. Unless otherwise specified, the reagents and materials used in the following examples are all commercially available.

[0064] Example 1: This embodiment provides a chemical mechanical polishing method for the sides and edges of bulk semiconductors, which specifically includes the following steps: S1: Securely clamp the block semiconductor 1 to be polished in the fixture 2, and connect at least one fixture 2 to the polishing disk 3.

[0065] S2: Adjust the angle between the fixture 2 and the polishing disc 3 to the side polishing state or the edge polishing state.

[0066] S3: Introduce the coarse polishing slurry into the polishing machine to mechanically coarsely polish the sides or edges of the bulk semiconductor 1.

[0067] S4: Introduce the fine polishing slurry into the polishing machine to perform chemical mechanical polishing on the sides or edges of the bulk semiconductor 1.

[0068] S5: Remove the bulk semiconductor 1 and repeat the operations of S1 to S4 to perform chemical mechanical polishing on the other sides and edges of the bulk semiconductor 1.

[0069] In steps S1 to S2, the specific structure of the fixture 2 in this embodiment is as follows: The fixture 2 includes a housing 2.1, a first limiting plate 2.2, a second limiting plate 2.3, a polishing fluid hose 2.4, an adjustable screw 2.5, and a rubber gasket 2.6.

[0070] The first limiting piece 2.2 and the second limiting piece 2.3 are disposed inside the housing 2.1. The first limiting piece 2.2 is connected to the top surface of the housing 2.1 via an adjustable screw 2.5, and is used to limit the top of the bulk semiconductor 1; the second limiting piece 2.3 is connected to one side wall of the housing 2.1 via an adjustable screw 2.5, and is used to limit the corresponding side of the bulk semiconductor 1. Rubber gaskets 2.6 are connected to the first limiting piece 2.2, the second limiting piece 2.3, and the side of the other side wall of the housing 2.1 that contacts the bulk semiconductor 1.

[0071] Polishing fluid hoses 2.4 are provided on both outer walls of the housing 2.1. The polishing fluid hoses 2.4 are fixed by several protruding slots on the housing 2.1. One end of the polishing fluid hoses 2.4 is connected to the polishing fluid spray control system of the polishing machine.

[0072] The clamp 2 is connected to the positioning bracket 3.1 on the polishing disc 3 via the angle adjusting screw 4, so as to adjust the angle between the clamp 2 and the polishing disc 3. In the side polishing state, the angle between the clamp 2 and the polishing disc 3 is 180°; in the edge polishing state, the angle between the clamp 2 and the polishing disc 3 is 45°.

[0073] When there are multiple fixtures 2, the multiple fixtures 2 are evenly distributed on the polishing disk 3. In the side polishing state, the height difference Δh of the exposed block semiconductor 1 sample in each fixture 2 is ≤0.5 mm; in the edge polishing state, the rotation angle difference Δθ of each fixture 2 is ≤5°.

[0074] In step S3, the coarse polishing slurry is an aqueous solution of abrasive particles with a concentration of 5-15 wt%. The particle size of the abrasive particles ranges from 1-5 μm, and the abrasive particles are one or more of aluminum oxide, silicon dioxide, diamond, magnesium oxide, and cerium oxide, preferably aluminum oxide. The polishing pressure for mechanical coarse polishing is 80-120 g / cm³. 2 Preferably 100 g / cm2 The polishing disc rotation speed is 50-100 r / min, preferably 80 r / min; the polishing time is 15-30 minutes, preferably 20 minutes.

[0075] In step S4, the fine polishing slurry is composed of the following raw materials in the following mass percentages: 6-12 wt% abrasive particles, 0.4-2 wt% hydrogen peroxide, 0.5-1.5 wt% sodium hypochlorite, 0.3-1 wt% dispersant, and 0.4-1.2 wt% complexing agent. The abrasive particles have a particle size range of 1-5 μm and are one or more of aluminum oxide, silicon dioxide, diamond, magnesium oxide, and cerium oxide, preferably aluminum oxide. The dispersant is one or more of polyethylene glycol, polyvinylpyrrolidone, sodium citrate, and Triton TX-100, preferably polyethylene glycol. The complexing agent is one or more of malic acid, citric acid, tartaric acid, and lactic acid, preferably malic acid. The pH of the fine polishing solution is 4.5-10.0. A slightly acidic pH of 4.5-6.0 is adjusted solely by malic acid, while a neutral or slightly alkaline pH of 6.0-10.0 is adjusted by adding ammonia or sodium carbonate. For alkaline processing of zinc telluride and cadmium phosphate, a pH of 5.0-9.0 is preferred. The polishing pressure for chemical mechanical polishing is 80-120 g / cm³. 2 Preferably 100g / cm 2 The polishing disc rotation speed is 50-100 r / min, preferably 80 r / min; the polishing time is 2-5 minutes, preferably 5 minutes.

[0076] Example 2: This embodiment provides a fixture for holding a bulk semiconductor 1 during chemical mechanical polishing, as well as a specific chemical mechanical polishing method.

[0077] The fixture 2 used in the polishing method of this embodiment is made of acid and alkali resistant material. Its outer shell is made of polyvinyl fluoride through a one-piece molding process, and the whole is inverted C-shaped. The fixture 2 is equipped with two polyvinyl fluoride limiting plates (i.e., the first limiting plate 2.2 and the second limiting plate 2.3) on the top and right sides. The two limiting plates are fixed by two threaded hexagonal screws (i.e., adjusting screws 2.5). The position of the limiting plates can be flexibly adjusted by turning the screws to adapt to the different sizes of block semiconductor 1 samples.

[0078] Meanwhile, rubber pads 2.6 are adhered to the left side of the inner side of the fixture 2 housing, the lower side of the upper limiting plate, and the left side of the right limiting plate. These pads can achieve buffered contact between the block semiconductor 1 and the fixture 2, avoiding mechanical damage during sample clamping.

[0079] In addition, a fluororubber hose is installed on each of the left and right sides of the fixture 2 housing as a polishing fluid delivery channel (i.e., polishing fluid hose 2.4). The hose is fixed to the housing of the fixture 2 by two protruding slots on each side, and the upper end of the hose is connected to the polishing fluid spray control system of the polishing machine to achieve precise delivery of polishing fluid.

[0080] A positioning frame 3.1 is installed on the upper part of the fixture 2 housing. The positioning frame 3.1 is connected to the fixture 2 by a threaded Phillips head screw (i.e., angle adjustment screw 4). Tightening the screw can adjust the angle between the fixture 2 and the positioning frame 3.1. The positioning frame 3.1 is directly connected to the polishing disc 3 and is a component of the polishing disc 3. The fixture 2 can be separated from the polishing disc 3 by removing the Phillips head screw.

[0081] Based on the above fixture, the chemical mechanical polishing method of this embodiment includes the following steps: (1) Sample pretreatment and clamping: Before polishing, the bulk semiconductor sample 1 must be cleaned to remove surface dust and oil. Then, the sample is neatly placed in the fixture 2, with one or more samples depending on the polishing requirements. Adjust the two hexagonal screws on the upper limiting plate to ensure that the inner side of the sample is in close contact with the upper limiting plate, and that the lower edge of the sample extends 1-2 mm beyond the fixture housing. Then, adjust the right limiting plate and tighten the two right limiting screws until the sample is securely clamped and will not fall off when lifted naturally.

[0082] (2) Assembly of the fixture and polishing disc: Connect the fixture 2 containing the sample to the positioning frame 3.1 using Phillips head screws. After adjusting the angle between the fixture 2 and the positioning frame 3.1, tighten the screws to ensure a tight and secure connection. For side polishing, adjust the angle between the fixture 2 and the polishing disc 3 to 180° (e.g., ...). Figure 2 As shown); during edge polishing, rotate the fixture 2 and polishing disc 3 to a preset angle (e.g., as shown). Figure 3 (As shown). If multiple clamps 2 are held on the polishing disc 3, it is necessary to ensure that the clamps 2 are evenly distributed (e.g., Figure 4 As shown), the height difference Δh of the exposed sample in each fixture 2 during side polishing should be ≤0.5 mm, and the rotation angle difference Δθ between different fixtures 2 should be ≤5° during edge polishing. After assembly, connect the fluororubber hose to the polishing liquid spraying system hose of the polishing machine, and turn on the vacuum pump to make the polishing disc 3 and the polishing head adhere tightly (as shown). Figure 5 As shown in the figure, complete the overall assembly of the sample and fixture 2, and after stabilization, turn on the polishing machine to start working.

[0083] (3) Polishing process implementation: The polishing process in this embodiment is divided into two stages: mechanical polishing and chemical mechanical polishing. ① Mechanical polishing stage: A coarse polishing solution is prepared by mixing abrasive particles and deionized water. The mass ratio of the two is adjusted according to the characteristics of the sample. After preparation, the solution is stirred thoroughly and continuously. The coarse polishing solution is introduced into the polishing machine. According to the hardness, size, quantity and surface condition of the sample, the appropriate polishing pressure and time are set to complete the coarse polishing.

[0084] ② Chemical mechanical polishing stage: After rough polishing, chemical mechanical polishing is carried out. Abrasive, oxidant and complexing agent are selected according to the characteristics of the sample, and the polishing solution is adjusted to a suitable pH value with a pH adjuster. The prepared fine polishing solution is introduced into the polishing machine, using the same pressure as rough polishing, and the polishing time is controlled within 5 minutes to complete the fine polishing.

[0085] (4) Follow-up processing: After fine polishing, remove clamp 2, loosen the screws on the right-side limiting plate, and take out the sample; adjust the clamping direction of the sample, and repeat the above operation to achieve polishing of other sides and edges of the sample.

[0086] Application example: This application example uses a bulk cadmium zinc telluride (CdZnTe, CZT) semiconductor with dimensions of 11mm × 11mm × 3mm as the polishing target. The surface exhibits chipping defects caused by cutting (chipping depth approximately 0.2mm), and the initial side surface roughness Ra is 2.0μm. Chemical mechanical polishing is required for its sides and edges. The specific implementation steps are as follows: I. Sample Pretreatment and Fixture Assembly The zinc cadmium telluride sample was cleaned in steps: first, it was ultrasonically cleaned in acetone for 3 minutes to remove organic oil stains on the surface; then, it was ultrasonically cleaned in anhydrous ethanol for 3 minutes to further remove residual impurities; finally, it was ultrasonically cleaned with deionized water for 5 minutes to rinse off any solvent residue on the surface, and then the sample surface was dried with nitrogen.

[0087] After drying, place the zinc cadmium telluride samples vertically in the PVC clamp, with a total of 5 samples. Adjust the two hexagonal screws on the top of the clamp to ensure that the inside of the sample is in close contact with the upper PVC limiting plate, and that the lower edge of the sample extends 1.2 mm beyond the clamp housing. Tighten the two limiting screws on the right side until the sample is securely clamped and does not fall off when lifted naturally.

[0088] Connect the fixture and the positioning frame with cross screws, and adjust the angle between the fixture and the polishing disc: adjust to 180° when polishing the side and preset to 45° when polishing the edge; the five fixtures are evenly distributed on the polishing disc to ensure that the height difference of the exposed sample is Δh=0.4mm and the rotation angle difference between the fixtures is Δθ=4° when polishing the edge.

[0089] Connect the fluororubber hoses on both sides of the fixture to the polishing liquid spray control system of the polishing machine, turn on the vacuum pump to make the polishing disc and polishing head adhere tightly, and complete the assembly.

[0090] II. Preparation of Polishing Fluid Rough polishing slurry: Alumina abrasive particles with a particle size of 3μm are mixed with deionized water at a mass ratio of 1:10. After preparation, the mixture is stirred continuously for 20 minutes at a speed of 300r / min using a magnetic stirrer to ensure that the abrasive particles are evenly dispersed.

[0091] Fine polishing slurry: Based on the coarse polishing slurry, 1 part hydrogen peroxide (30wt%) and 0.5 parts sodium hypochlorite are added by mass ratio as oxidants. Simultaneously, appropriate amounts of polyethylene glycol are added as dispersants and malic acid as complexing agents. The acidic range is adjusted by malic acid, while the neutral and weakly alkaline ranges are adjusted by ammonia water, covering an overall range of 4.5-10.0. In this embodiment, a weakly acidic condition is used for the zinc cadmium telluride slurry, adjusting the pH to 5.0 and stirring thoroughly before use. The final concentrations of each component in the fine polishing slurry are approximately: 8wt% abrasive particles, 0.3wt% hydrogen peroxide, 0.5wt% sodium hypochlorite, 1.5wt% polyethylene glycol, and 1wt% malic acid.

[0092] III. Mechanical Polishing Stage The coarse polishing slurry was introduced into the polishing machine, and the polishing pressure was set to 100 g / cm. 2 The polishing disc rotates at 80 r / min and the polishing time is 20 minutes to complete the mechanical rough polishing of the zinc cadmium telluride sample, removing surface chipping defects and most of the unprocessed layer.

[0093] IV. Chemical-Mechanical Polishing Stage After coarse polishing, switch to fine polishing solution and maintain a polishing pressure of 100g / cm. 2 The polishing disc speed is kept constant at 80 r / min, and the polishing time is controlled at 3 minutes to complete the chemical mechanical polishing and achieve precise flatness of the sample surface.

[0094] V. Follow-up Processing After fine polishing, turn off the polishing machine and vacuum pump, remove the clamp and loosen the right limit screw, and take out the zinc cadmium telluride sample; adjust the clamping direction of the sample, repeat the above steps, and complete the polishing treatment of the remaining 3 sides and 4 edges of the sample.

[0095] like Figure 6 As shown, the final side roughness Ra of the zinc cadmium telluride sample was reduced to 0.015 μm, the scratches were significantly removed, the edge polishing angle deviation was ≤0.3°, and there was no oxidant diffusion pollution or surface scratch defects.

[0096] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A chemical mechanical polishing method for the sides and edges of bulk semiconductors, characterized in that, Specifically, the following steps are included: S1: Securely clamp the block semiconductor (1) to be polished in the fixture (2) and connect at least one fixture (2) to the polishing disk (3); S2: Adjust the angle between the fixture (2) and the polishing disc (3) to the side polishing state or the edge polishing state; S3: Introduce the coarse polishing slurry into the polishing machine to mechanically coarse polish the sides or edges of the bulk semiconductor (1); S4: Introduce fine polishing slurry into the polishing machine to perform chemical mechanical fine polishing on the sides or edges of the bulk semiconductor (1); S5: Remove the bulk semiconductor (1) and repeat the operations of S1 to S4 to perform chemical mechanical polishing on the other sides and edges of the bulk semiconductor (1).

2. The chemical mechanical polishing method for the sides and edges of a bulk semiconductor according to claim 1, characterized in that, In step S1, the fixture (2) specifically includes a housing (2.1), a first limiting piece (2.2) and a second limiting piece (2.3) disposed inside the housing (2.1), and a polishing liquid hose (2.4) disposed on the outer wall of the housing (2.1). The first limiting piece (2.2) is connected to the top surface of the housing (2.1) by an adjustable screw (2.5) to limit the top of the block semiconductor (1); The second limiting piece (2.3) is connected to one side wall of the housing (2.1) via an adjustable screw (2.5) to limit the corresponding side of the block semiconductor (1).

3. The chemical mechanical polishing method for the sides and edges of a bulk semiconductor according to claim 2, characterized in that, Rubber pads (2.6) are connected to the other side wall of the first limiting piece (2.2), the second limiting piece (2.3), and the side of the housing (2.1) that contacts the block semiconductor (1).

4. The chemical mechanical polishing method for the sides and edges of a bulk semiconductor according to claim 2, characterized in that, The outer walls on both sides of the housing (2.1) are provided with polishing fluid hoses (2.4). The polishing fluid hose (2.4) is fixed by several protruding slots in the housing (2.1); One end of the polishing fluid hose (2.4) is connected to the polishing fluid spray control system of the polishing machine.

5. The chemical mechanical polishing method for the sides and edges of a bulk semiconductor according to claim 1, characterized in that, In step S1, the clamp (2) is connected to the positioning frame (3.1) on the polishing disc (3) by the angle adjustment screw (4) to adjust the angle between the clamp (2) and the polishing disc (3); When the side is polished, the angle between the fixture (2) and the polishing disc (3) is 180°. When the edge is polished, the angle between the fixture (2) and the polishing disc (3) is 30-60°.

6. The chemical mechanical polishing method for the sides and edges of a bulk semiconductor according to claim 1, characterized in that, In step S1, the fixtures (2) are evenly distributed on the polishing disc (3); When the side is polished, the height difference Δh of the exposed bulk semiconductor (1) sample in each fixture (2) is ≤0.5 mm; When the edges are polished, the difference in rotation angle Δθ between each fixture (2) is ≤5°.

7. The chemical mechanical polishing method for the sides and edges of a bulk semiconductor according to claim 1, characterized in that, In step S3, the coarse polishing liquid is an aqueous solution of abrasive particles, and the concentration of the abrasive particles is 5-15 wt%. The abrasive particles are one or more of aluminum oxide, silicon dioxide, diamond, magnesium oxide, and cerium oxide. The particle size of the abrasive particles ranges from 1 to 5 μm.

8. The chemical mechanical polishing method for the sides and edges of a bulk semiconductor according to claim 1, characterized in that, In step S3, the polishing pressure of the mechanical rough polishing is 80-120 g / cm. 2 The polishing disc rotates at 50-100 rpm, and the polishing time is 15-30 minutes.

9. The chemical mechanical polishing method for the sides and edges of a bulk semiconductor according to claim 1, characterized in that, In step S4, the fine polishing slurry is composed of the following raw materials in the following mass percentages: 6-12 wt% abrasive particles, 0.4-2 wt% hydrogen peroxide, 0.5-1.5 wt% sodium hypochlorite, 0.3-1 wt% dispersant, and 0.4-1.2 wt% complexing agent; The abrasive particles are one or more of aluminum oxide, silicon dioxide, diamond, magnesium oxide, and cerium oxide, and the particle size range of the abrasive particles is 1-5 μm. The dispersant is one or more of polyethylene glycol, polyvinylpyrrolidone, sodium citrate, and Triton TX-100; The complexing agent is one or more of malic acid, citric acid, tartaric acid, and lactic acid; The fine polishing solution has two pH types: acidic and alkaline. The pH value can be adjusted to 4-6 or 8-10 using a weak acid or weak alkaline solution, respectively.

10. The chemical mechanical polishing method for the sides and edges of a bulk semiconductor according to claim 1, characterized in that, In step S4, the polishing pressure of the chemical mechanical polishing is 80-120 g / cm. 2 The polishing disc rotates at 50-100 rpm, and the polishing time is 2-5 minutes.

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