A surface polishing and cleaning method for indium antimonide based on gradient pressure slow release and dynamic chemical regulation

Abstract

This invention discloses a surface polishing and cleaning method for indium antimonide based on gradient pressure release and dynamic chemical regulation. The steps include: waxing, primary rough polishing, secondary rough polishing, semi-fine polishing, wafer removal and wax removal, fine polishing, pre-cleaning, and cleaning. This method introduces a gradient pressure release strategy in the multi-stage polishing process, combined with dynamic chemical regulation of an organic acid and sodium salt system, to achieve progressive stress release and selective surface etching during polishing. In the fine polishing stage, an adsorption pad is used to stabilize the wafer, avoiding organic contamination introduced by traditional waxing. Combined with subsequent synergistic cleaning and surface passivation processes, an integrated polishing-cleaning-passivation synergistic process is formed. This invention can obtain a high-quality indium antimonide surface with a surface roughness Ra≤0.15nm, oxide layer thickness controlled within 1.2±0.3nm, no scratches, and ultra-cleanliness, significantly improving substrate surface quality and epitaxial growth compatibility.

Description

Technical Field

[0001] This invention belongs to the field of antimony compounds, and particularly relates to a surface polishing and cleaning method for indium antimonide based on gradient pressure slow release and dynamic chemical regulation. Background Technology

[0002] Indium antimonide (InSb), a typical III-V group narrow bandgap semiconductor, possesses extremely high electron mobility and excellent mid-wave infrared photoelectric response characteristics, making it a key material for third-generation infrared focal plane array detectors, high-speed magnetoresistive sensors, and cutting-edge quantum devices. The performance parameters of these high-performance devices, such as quantum efficiency, dark current, and carrier lifetime, are extremely sensitive to the surface quality of the epitaxial layer and substrate. Atomically flat, low-damage, stoichiometrically accurate, and contamination-free surface states are required to construct high-quality heterojunctions, reduce interface state density, and achieve the desired device performance. However, obtaining an ideal InSb surface faces challenges due to its intrinsic physicochemical properties: the material has low hardness and high brittleness, and traditional machining easily introduces scratches, microcracks, and deep lattice damage. Simultaneously, In and Sb are readily oxidized in air, forming a non-stoichiometric, defect-rich natural oxide layer. This oxide layer is structurally unstable and has poor electrical properties, becoming a major source of interface states and recombination centers.

[0003] To address these issues, this invention proposes an integrated process combining gradient pressure release, dynamic chemical regulation, and synergistic cleaning and passivation to fundamentally solve the problems of stress damage, chemical residue, and surface degradation in indium antimonide surface treatment. The core of this method lies in introducing a gradient pressure release strategy during the polishing stage. This involves optimizing the polishing pad parameters and matching the polishing process with the material properties; dynamically controlling the pH using an organic acid-sodium salt system; and selecting an adsorption pad for fine polishing to avoid the introduction of organic contaminants. The cleaning stage utilizes a sulfuric acid and SC1 solution with strong decontamination capabilities and minimal surface corrosion, thoroughly cleaning while minimizing surface roughness degradation. This integrated process aims to provide a reliable and repeatable foundation for the fabrication of high-performance InSb-based devices. Summary of the Invention

[0004] The purpose of this invention is to provide a polishing and cleaning method that achieves ultra-smooth, damage-free, low-stress, and intrinsically clean indium antimonide surfaces. This method gradually releases mechanical stress through a gradient pressure release strategy, optimizes the surface microstructure by combining dynamic chemical regulation of an organic acid-sodium salt system, and finally ensures surface chemical cleanliness and stability through synergistic cleaning and passivation processes.

[0005] To address the above problems, this invention provides a surface polishing and cleaning method for indium antimonide based on gradient pressure release and dynamic chemical regulation, comprising the following steps:

[0006] S1. Apply wax to the indium antimonide wafer using a semi-automatic waxing machine and attach it to the ceramic plate. Remove any residual wax from the surface after waxing.

[0007] S2, the wafer undergoes a rough polishing process;

[0008] S3, the wafer undergoes a second rough polishing;

[0009] S4, the wafer is semi-polished and then spun dry;

[0010] S5, the wafer is removed and dewaxed;

[0011] S6, the wafer is adsorbed with an adsorption pad for fine polishing;

[0012] S7, pre-cleaning the chip;

[0013] S8, clean the chip, and then spin dry;

[0014] S9, the processing is complete, and a high-quality surface state is obtained.

[0015] In the rough polishing stage, a gradient pressure release strategy is adopted, which gradually reduces the polishing pressure through two rough polishing stages to release surface stress. In the semi-fine polishing and fine polishing stages, an organic acid and sodium salt composite system is introduced for dynamic chemical regulation to achieve selective etching of surface micro-protrusions and inhibition of metal ion complexation. In the fine polishing stage, an adsorption pad is used to adsorb and fix the wafer to avoid organic contamination. After polishing, synergistic cleaning and surface passivation treatment are performed to form an integrated polishing-cleaning-passivation process.

[0016] The surface polishing and cleaning method for indium antimonide based on gradient pressure release and dynamic chemical regulation according to claim 1 is characterized in that the pressure of the first coarse polishing is 120-180 g / cm²; the pressure of the second coarse polishing is 100-120 g / cm²; the pressure of the semi-fine polishing is 80-120 g / cm²; and the pressure of the fine polishing is 50-80 g / cm².

[0017] Furthermore, the polishing solution contains 0.5%–1.5% silica micro powder, 0.2%–20% sodium hypochlorite solution, and 0.1%–3% organic acid; the pH value of the polishing solution is controlled between 5 and 8; the organic acid includes at least one of citric acid and malic acid.

[0018] Furthermore, the surface of the adsorption pad is smooth, and the pore depth is 100-200μm less than the wafer thickness. The wafers used for fine polishing must be clean, tidy, and free of contamination.

[0019] Furthermore, the pre-cleaning uses isopropanol and a low-temperature SC1 solution; the main cleaning is performed in a Class 100 clean environment using a combination of SC1 and a low-temperature sulfuric acid solution. During pre-cleaning, SC1 is prepared at a ratio of ammonium hydroxide:hydrogen peroxide:deionized water of 2:5:8; during main cleaning, SC1 is prepared at a ratio of ammonium hydroxide:hydrogen peroxide:deionized water of 0.5:2:10.

[0020] Furthermore, all tools and containers that come into contact with the wafer during the cleaning process are subjected to ultrasonic cleaning and high-purity nitrogen purging.

[0021] The above-mentioned technical solution of the present invention has the following beneficial technical effects: it can obtain excellent thickness deviation, and the thickness deviation of 3-inch and 4-inch wafers can be controlled below 5µm; it can effectively remove scratches and damage defects generated during polishing, solving the current difficulties and pain points of slow removal rate and long processing time in the industry, and greatly improving processing efficiency; it can prevent oxidation after processing and achieve ultra-clean surface, thus obtaining a clean surface with extremely low roughness. Attached Figure Description

[0022] Figure 1 The flowchart shows a surface polishing and cleaning method for indium antimonide based on gradient pressure release and dynamic chemical regulation.

[0023] Figure 2 This is a three-dimensional image showing the flatness of an indium antimonide surface after processing using this method based on gradient pressure release and dynamic chemical regulation.

[0024] Figure 3 The image shows the surface roughness after processing using the indium antimonide surface polishing and cleaning method based on gradient pressure release and dynamic chemical regulation.

[0025] Figure 4 This image shows the surface defects detected under a dark field using an Olympus microscope with a 10*50 lens after processing with an indium antimonide surface polishing and cleaning method based on gradient pressure release and dynamic chemical regulation.

[0026] Figure 5 Images of the surface oxide layer after processing using this indium antimonide surface polishing and cleaning method based on gradient pressure release and dynamic chemical regulation;

[0027] Figure 6 This is a roughness comparison diagram between the embodiments and comparative examples of the present invention. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments and the accompanying drawings. It should be understood that these descriptions are merely exemplary and not intended to limit the scope of the invention. Furthermore, descriptions of well-known structures and techniques are omitted in the following description to avoid unnecessarily obscuring the concept of the invention.

[0029] like Figure 1 As shown, a surface polishing and cleaning method for indium antimonide based on gradient pressure release and dynamic chemical regulation is provided, including the following steps:

[0030] S1. Apply wax to the indium antimonide wafer using a semi-automatic waxing machine and attach it to the ceramic plate. Remove any residual wax from the surface after waxing.

[0031] S2, the wafer undergoes a rough polishing process;

[0032] S3, the wafer undergoes a second rough polishing;

[0033] S4, the wafer is semi-polished and then spun dry;

[0034] S5, the wafer is removed and dewaxed;

[0035] S6, the wafer is adsorbed with an adsorption pad for fine polishing;

[0036] S7, pre-cleaning the chip;

[0037] S8, clean the chip, and then spin dry;

[0038] S9, the processing is complete, and a high-quality surface state is obtained.

[0039] In the specific embodiment, six 3-inch N-type single-sided indium antimonide wafers with a diameter of 76.2±0.4mm and a thickness of 600±25um were selected from the mature crystal growth process CZ method. The thickness after the grinding process was 660±5um.

[0040] S1 uses a semi-automatic waxing machine to evenly attach 6 indium antimonide wafers onto a ceramic disk with a diameter of 305mm. After the ceramic disk cools to room temperature, the wax residue on the wafers and the surface of the ceramic disk is wiped clean and ready for use.

[0041] In step S2, a black damping cloth with a hardness of Asker C 63, density of 0.37 g / cm³, compression set of 500 μm, pile length of 830 μm, and average pore diameter of 70 μm was selected for the initial coarse polishing. The polishing solution was an aqueous suspension containing 3% silica micropowder with a particle size of 120 nm and 0.7% inorganic acid. The inorganic acid was selected as 37% pure hydrochloric acid with a pH of 2.0 after mixing. The flow rate was 600 ml / min, the polishing pressure was controlled at 160 g / cm², the rotation speed was set at 110 rpm, and the polishing time was 15 minutes.

[0042] In step S3, the secondary coarse polishing uses black damping cloth with a hardness of Asker C 60, density of 0.32 g / cm³, compression deformation of 200 μm, pile length of 500 μm, and average pore diameter of 60 μm. The polishing solution is an aqueous suspension containing 2% silica micropowder with a particle size of 110 nm and 0.5% inorganic acid. The inorganic acid is selected as 37% pure hydrochloric acid with a pH of 1.9 after mixing. The flow rate is 500 ml / min, the polishing pressure is controlled at 120 g / cm², the rotation speed is set at 90 rpm, and the polishing time is 5 minutes.

[0043] In step S4, the semi-finish polishing process uses black damping cloth with a hardness of Asker C 62, density of 0.32 g / cm³, compression set of 190 μm, pile length of 550 μm, and average pore size of 40 μm. The polishing solution is an aqueous suspension containing 1% silica micropowder with a particle size of 40 nm, 0.4% inorganic acid (selected as 37% pure hydrochloric acid), a pH value between 2 after mixing, a flow rate of 600 ml / min, a polishing pressure of 100 g / cm², a rotation speed of 90 rpm, and a polishing time of 10 minutes.

[0044] After the semi-polishing in step S5, the ceramic disc is heated, the wafer is removed, and placed in a cleaning agent for dewaxing. The dewaxing agent is prepared at a volume ratio of 1:10 between the stock solution and deionized water, heated to 60-80℃, and dewaxed for 3 minutes.

[0045] In step S6, black damping cloth with Asker C 62 hardness, 0.32 g / cm³ density, 190 μm compression set, 600 μm pile length, and 30 μm average pore diameter is selected for fine polishing. The polishing solution is an aqueous suspension containing 0.7% silica micropowder (30 nm particle size), 20% sodium hypochlorite solution, 0.4% sodium citrate, 0.3% malic acid, and 0.2% citric acid. After mixing, the pH value is 6.5, the flow rate is 600 ml / min, the polishing pressure is controlled at 70 g / cm², the rotation speed is set at 100 rpm, and the polishing time is 10 minutes. An adsorption pad is used as an adsorption tool to stabilize the wafer for polishing. The adsorption pad has a smooth surface, and the pore depth is selected to be 150 μm less than the wafer thickness.

[0046] In step S7, the pre-cleaning process uses isopropanol and SC1 solution commonly used in the semiconductor industry. The solution is soaked in isopropanol for 30 seconds. SC1 is prepared with ammonium hydroxide, hydrogen peroxide and deionized water in a ratio of 2:5:8, and the temperature is controlled at 4°C. The soaking time is 5 minutes.

[0047] In step S8, a combination solution of SC1 and sulfuric acid is selected for cleaning. The wafer is placed in the SC1 solution for 30 seconds. The SC1 solution is prepared with ammonium hydroxide, hydrogen peroxide, and deionized water at a volume ratio of 0.5:2:10, and the temperature is controlled at 2°C. Then, it is rinsed with deionized water for 60 seconds, spun dry, and placed in a sulfuric acid solution with a 3-second agitation. The sulfuric acid solution is prepared with water at a volume ratio of 1:20. Finally, it is rinsed with deionized water for 70 seconds, spun dry, and packaged. The entire process must be completed in a Class 100 clean environment. All pipes, containers, and tools that come into contact with the wafer are ultrasonically cleaned and purged with high-purity nitrogen.

[0048] Step S9 completes the processing, yielding a high-quality surface state.

[0049] After the above implementation case, the flatness 3D diagram is shown in the figure. Figure 2 As shown. The surface roughness was tested using AFM, and the results are as follows. Figure 3 As shown. Surface defects were examined using a microscope, and the results are as follows. Figure 4 As shown. The surface roughness Ra of the 3-4 inch indium antimonide wafer is ≤0.15nm, the oxide layer thickness is 1.2±0.3nm, the surface is free of visible scratches and particulate contamination, and the thickness deviation is ≤5μm. Figure 5 As shown.

[0050] Comparative Example 1 employed a traditional constant-pressure polishing method (without gradient pressure release). The process involved: a single rough polishing cycle with a constant pressure of 180 g / cm² for 20 minutes; semi-fine and fine polishing cycles with pressures maintained at 120 g / cm² without gradual pressure reduction; a conventional silica suspension (pH≈2) was used as the polishing slurry, without the addition of organic acids or sodium salts; traditional waxing was used to fix the wafer during the fine polishing stage; and the cleaning process consisted only of rinsing with deionized water followed by immersion in SC1 at room temperature. The results led to a surface roughness Ra≥0.3 nm with micro-scratches, uneven oxide layer thickness averaging greater than 2.5 nm, significant residual organic matter and particulate contamination on the surface, high interface state density after epitaxial growth, and unstable device performance.

[0051] Comparative Example 2 employed a polishing method without dynamic chemical control. Although a gradient pressure strategy (160→120→100→70 g / cm²) was used, the polishing solution was merely a silica suspension, without the addition of organic acids or sodium salts, and the pH value was not adjusted. An adsorption pad was used in the fine polishing stage, and the cleaning process was the same as in this invention. The results showed that the surface roughness Ra was approximately 0.2 nm, which was better than that of Comparative Example 1. However, slight metal ion residues were present on the surface, the oxide layer thickness was 1.8 ± 0.5 nm, slight etching unevenness was observed in some areas, and a small number of defects remained at the epitaxial layer interface.

[0052] Comparative Example 3 employed a non-synergistic cleaning and passivation process. Although gradient pressure and an organic acid-sodium salt system were used, and a fine-polishing adsorption pad was used for fixation, cleaning consisted only of room-temperature SC1 immersion followed by deionized water rinsing; a low-temperature SC1 and sulfuric acid combination cleaning was not performed, and no passivation treatment was performed. The results showed that the surface roughness Ra ≤ 0.15 nm and the oxide layer thickness was 1.5 ± 0.4 nm, but trace particles and organic matter residues still existed on the surface. After 24 hours of storage, the surface oxide layer thickened significantly, requiring additional treatment before epitaxial growth, which affected process consistency.

[0053] The embodiments of the present invention and comparative examples 1-3 are shown in the table below:

[0054] Table 1

[0055]

[0056] like Figure 6 The figures show a roughness comparison between the embodiments and comparative examples of the present invention. In the figures, (a) represents the roughness of the embodiment of the present invention, (b) represents the roughness of comparative example 1, (c) represents the roughness of comparative example 2, and (d) represents the roughness of comparative example 3. The surface polishing and cleaning method for indium antimonide based on gradient pressure slow release and dynamic chemical regulation of the present invention can effectively remove scratches and damage defects generated during the polishing process, prevent oxidation after processing, and achieve ultra-clean surface, thereby obtaining a clean surface with extremely low roughness.

[0057] It should be understood that the specific embodiments described above are merely illustrative or explanatory of the principles of the invention and do not constitute a limitation thereof. Therefore, any modifications, equivalent substitutions, improvements, etc., made without departing from the spirit and scope of the invention should be included within the protection scope of the invention. Furthermore, the appended claims are intended to cover all variations and modifications falling within the scope and boundaries of the appended claims, or equivalent forms of such scope and boundaries.

Claims

1. A surface polishing and cleaning method for indium antimonide based on gradient pressure slow release and dynamic chemical regulation, characterized in that, Includes the following steps: S1. Apply wax to the indium antimonide wafer using a semi-automatic waxing machine and attach it to the ceramic plate. Remove any residual wax from the surface after waxing. S2, the wafer undergoes a rough polishing process; S3, the wafer undergoes a second rough polishing; S4, the wafer is semi-polished and then spun dry; S5, the wafer is removed and dewaxed; S6, the wafer is adsorbed with an adsorption pad for fine polishing; S7, pre-cleaning the chip; S8, clean the chip, and then spin dry; S9, the processing is complete, and a high-quality surface state is obtained.

2. The method for polishing and cleaning indium antimonide surface based on gradient pressure slow release and dynamic chemical regulation according to claim 1, characterized in that, The pressure for the first coarse polishing is 120–180 g / cm²; the pressure for the second coarse polishing is 100–120 g / cm²; the pressure for the semi-fine polishing is 80–120 g / cm²; and the pressure for the fine polishing is 50–80 g / cm².

3. The surface polishing and cleaning method for indium antimonide based on gradient pressure slow release and dynamic chemical regulation according to claim 1, characterized in that, The polishing solution contains 0.5%–1.5% silica micro powder, 0.2%–20% sodium hypochlorite solution, and 0.1%–3% organic acid; the pH value of the polishing solution is controlled between 5 and 8; the organic acid includes at least one of citric acid and malic acid.

4. The surface polishing and cleaning method for indium antimonide based on gradient pressure slow release and dynamic chemical regulation according to claim 1, characterized in that, The surface of the adsorption pad is smooth, and the pore depth is 100-200μm less than the thickness of the wafer. The wafers used for fine polishing must be clean, tidy and free of contamination.

5. The surface polishing and cleaning method for indium antimonide based on gradient pressure slow release and dynamic chemical regulation according to claim 1, characterized in that, The pre-cleaning process uses isopropanol and a low-temperature SC1 solution; the main cleaning process is carried out in a Class 100 clean environment using a combination of SC1 and a low-temperature sulfuric acid solution.

6. The surface polishing and cleaning method for indium antimonide based on gradient pressure slow release and dynamic chemical regulation according to claim 5, characterized in that, During the cleaning process, all tools and containers that come into contact with the wafer are subjected to ultrasonic cleaning and high-purity nitrogen purging.

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