A cleaning process for indium antimonide wafers

Abstract

The application belongs to the field of semiconductor substrate manufacturing, and discloses a cleaning process of indium antimonide wafer, which comprises the following steps: soaking the polished and waxed wafer in hot concentrated sulfuric acid and cold concentrated sulfuric acid in sequence; cleaning the wafer in S1 cleaning solution, wherein the S1 cleaning solution is a mixture of sulfuric acid, hydrogen peroxide and water; cleaning the wafer in S2 cleaning solution, wherein the S2 cleaning solution is a mixture of hydrofluoric acid and / or hydrochloric acid and water; cleaning the wafer in S3 cleaning solution, wherein the S3 cleaning solution is a mixture of phosphoric acid and / or sulfuric acid and / or sulfurous acid and water; and drying. The cleaning process can improve the yield of products and reduce the production cost.

Description

Technical Field

[0001] This invention belongs to the field of semiconductor substrate manufacturing and relates to a cleaning process for indium antimonide wafers. Background Technology

[0002] Indium antimonide (InSb) is one of the earliest and most thoroughly studied group III-V semiconductor materials. Its crystals are silvery and brittle, exhibiting a zincblende structure with a lattice constant of 6.48 Å. It is a direct bandgap material with a narrow bandgap of 0.18 eV and a high electron mobility of 7800 cm⁻¹. 2 Indium antimonide (IUS) has a melting point of 525°C. Compared to other group III-V compounds, it is easier to purify and grow into single crystals, making it a popular choice for solid-state theoretical studies of group III-V compounds.

[0003] The production process from indium antimonide crystals to indium antimonide wafer substrates involves a series of complex processing steps. Among these, cleaning the indium antimonide wafer is one of the most critical processes. After cleaning, the surface quality of the indium antimonide wafer directly affects the performance of indium antimonide-based devices. In addition to ensuring that the performance quality of the substrate material meets customer requirements, the surface quality of the wafer substrate must also meet the customer's usage requirements.

[0004] The commonly used cleaning process in the industry is as follows: (1) Use a wax remover to remove the wax from the polished indium antimonide wafer after the waxing process; (2) Use hot and cold sulfuric acid to quickly clean and remove larger organic particles and metal compounds from the wafer surface; (3) Rinse with deionized water to remove residual acid; (4) Clean with a mixed solution of 30%~35% hydrogen peroxide and 28%~35% ammonia to remove some heavy metals and inorganic impurities from the wafer surface; (5) After quickly rinsing the wafer surface with deionized water, spin dry and inspect for any chemical residues and mechanical damage before packaging and shipping.

[0005] However, the commonly used cleaning process for indium antimonide mentioned above will corrode the wafer surface, resulting in a large number of particles and excessive roughness on the wafer surface. It will also form a thick oxide film on the wafer surface. At the same time, uncontrollable white fog defects will be generated on the wafer surface, causing the surface impurity content to exceed the standard and fail to meet the requirements, resulting in a low overall yield and high production cost. Summary of the Invention

[0006] To address the aforementioned problems in the existing technology, the present invention aims to provide a cleaning process for indium antimonide wafers with high yield and low production cost. This cleaning process ensures the cleanliness of the wafer surface, while not damaging the roughness of the wafer after polishing, reducing the oxide layer thickness, controlling surface haze, and effectively controlling the surface impurity content.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A cleaning process for indium antimonide wafers includes the following steps: (1) The polished and wax-removed wafers were successively immersed in hot concentrated sulfuric acid and cold concentrated sulfuric acid; (2) The wafer processed in step (1) is placed in S1 cleaning solution for cleaning treatment, wherein S1 cleaning solution is a mixture of sulfuric acid, hydrogen peroxide and water; (3) The wafer processed in step (2) is placed in S2 cleaning solution for cleaning treatment, wherein the S2 cleaning solution is a mixture of hydrofluoric acid and / or hydrochloric acid and water; (4) The wafer processed in step (3) is placed in S3 cleaning solution for cleaning treatment, wherein S3 cleaning solution is a mixture of phosphoric acid and / or sulfuric acid and / or sulfurous acid and water; (5) Dry the wafer after step (4).

[0008] The cleaning process of the present invention creatively introduces S1 cleaning solution, S2 cleaning solution and S3 cleaning solution to clean indium antimonide wafers: Step (1) Use concentrated sulfuric acid to remove organic matter on the crystal surface; Step (2) Use a mixture of sulfuric acid, hydrogen peroxide and water to further remove organic matter; In Step (3), hydrofluoric acid is a weak acid, but has extremely strong corrosiveness. After dilution, it removes silicon dioxide on the wafer surface and reduces the oxide layer thickness; Step (4) Set the cleaning solution to further remove silicon dioxide on the wafer surface; Step (5) Dry the wafer.

[0009] Furthermore, in step (1): Hot concentrated sulfuric acid treatment process: soaking for 10~30s; temperature 50~70℃; sulfuric acid mass concentration 70~98%.

[0010] Furthermore, in step (1): Cold concentrated sulfuric acid treatment process: soaking for 10~30s; temperature 30~45℃; sulfuric acid mass concentration 70~98%.

[0011] Further, in step (2) and step (3), the volume ratio of sulfuric acid, hydrogen peroxide and water in the S1 cleaning solution is 1~10:10~20:25~35; the mass concentration of sulfuric acid used for preparation is ≥70%; the mass concentration of hydrogen peroxide used for preparation is ≥30.0%; the cleaning temperature is 20~30℃; and the cleaning time is 10~30s.

[0012] Further preferred is that the mass concentration of sulfuric acid used in the preparation is 70%~98%; and the mass concentration of hydrogen peroxide used in the preparation is 30.0~32.0%.

[0013] Further, in step (3), the volume ratio of hydrofluoric acid and / or hydrochloric acid to water in the S2 cleaning solution is 1~5:6~12; the mass concentration of hydrofluoric acid used for preparation is ≥48.8%; the mass concentration of hydrochloric acid used for preparation is ≥36.0%; and the cleaning time is 40~60s.

[0014] Further preferred is that the mass concentration of hydrofluoric acid used for preparation is 48.8~49.2%; and the mass concentration of hydrochloric acid used for preparation is 36.0~38.0%.

[0015] Further, in step (4), the volume ratio of phosphoric acid and / or sulfuric acid and / or sulfurous acid and water in the S3 cleaning solution is 1~3:5~10; the mass concentration of phosphoric acid used for preparation is ≥85.0%; the mass concentration of sulfuric acid used for preparation is 70%~98%; and the cleaning treatment time is 30~60s.

[0016] Furthermore, in steps (2) to (4), the cleaning temperature is below 25°C.

[0017] Furthermore, a water rinsing process is set between steps (1) and (2), between steps (2) and (3), between steps (3) and (4), and between steps (4) and (5).

[0018] A further preferred method for the rinsing process is as follows: the wafer is placed in a water tank, and a water gun is used to rinse the water tank to maintain an overflow state; the overflow water volume is 10~60L / min.

[0019] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) The cleaning process of the present invention, by introducing cleaning solutions S1, S2, and S3, can effectively remove metal compound ions, organic particles, heavy metals, and inorganic impurities from the surface of indium antimonide wafer substrates, ensuring the cleanliness of the wafer surface. At the same time, the cleaning process does not damage the roughness of the wafer after polishing, can reduce the oxide layer thickness, control the surface haze, and effectively control the surface impurity content. This achieves the optimization and improvement of substrate surface quality, meeting the customer's purpose.

[0020] (2) The cleaning process of the present invention can improve the product yield and reduce production costs. Detailed Implementation

[0021] To facilitate understanding of the present invention, the present invention will be described more fully and in detail below with reference to preferred embodiments in the specification, but the scope of protection of the present invention is not limited to the following specific embodiments.

[0022] Unless otherwise defined, all technical terms used herein have the same meaning as commonly understood by those skilled in the art. The technical terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the scope of the invention.

[0023] The component concentrations used in the various embodiments and comparative examples of this invention are as follows: Hydrogen peroxide (hydrogen peroxide solution), with a mass concentration of 30.0%; Sulfuric acid, with a mass concentration of 96%; Hydrofluoric acid, with a mass concentration of 48.8%; Phosphoric acid, with a mass concentration of 85.0%.

[0024] Example 1 This embodiment discloses a cleaning process for indium antimonide wafers, including the following steps: (1) Select 10 3-inch indium antimonide wafers that have been polished and waxed using the waxing process, and immerse them in sulfuric acid at 65°C for 5 seconds; immerse them in sulfuric acid at 40°C for 3 seconds; place them in a water tank, and simultaneously use a water gun to rinse the water bowl to keep the water overflowing. Cleaning time: 40 seconds.

[0025] (2) The wafer after step (1) is placed in S1 cleaning solution for cleaning treatment. The volume ratio of sulfuric acid, hydrogen peroxide and water is 10:10:30. The cleaning treatment temperature is 25℃ and the cleaning treatment time is 20s. During the cleaning process, the wafer is rotated continuously to make the wafer surface uniformly coated with liquid. Then the wafer is rinsed with a water gun to keep the water bowl in an overflow state and the rinsing time is 40s.

[0026] (3) The wafer processed in step (2) is placed in S2 cleaning solution for cleaning. The volume ratio of hydrofluoric acid to water in S2 cleaning solution is 4:6. The cleaning time is 45s. The cleaning temperature is 25℃. During the cleaning process, the wafer is rotated continuously to ensure that the wafer surface is evenly coated with liquid. Then the wafer is placed in a rinsing tank for rinsing for 30s.

[0027] (4) The wafer after step (3) is placed in S3 cleaning solution for cleaning. The volume ratio of phosphoric acid to water in S3 cleaning solution is 3:7. The cleaning time is 30s and the cleaning temperature is 25℃. During the cleaning process, the wafer is rotated continuously to make the wafer surface uniformly coated with liquid. Then the wafer is rinsed with a water gun to keep the water bowl in an overflow state. The rinsing time is 30s.

[0028] (5) After each wafer is cleaned and dried, it is placed in a cartridge box that has been dried with nitrogen. After passing the inspection, it can be packaged and shipped.

[0029] Comparative Example 1 This comparative example discloses a cleaning process for indium antimonide wafers, including the following steps: (1) Select nine 3-inch indium antimonide wafers that have been polished and waxed using the waxing process, immerse them in hot sulfuric acid at 65°C for 5 seconds, and immerse them in cold sulfuric acid at room temperature for 3 seconds.

[0030] (2) Place the chip processed in step (1) into a water bowl and simultaneously rinse the water bowl with a water gun to keep the water overflowing. Cleaning time: 45s.

[0031] (3) Use citric acid with a mass concentration of 99.8% and soak it in a mixed solution of citric acid and deionized water with a volume ratio of 1:30 for 30 seconds. During the soaking process, rotate the wafer clamp continuously to make the wafer surface evenly coated with liquid and rinse it with a water gun. The cleaning temperature is 4℃ and the cleaning time is 30 seconds.

[0032] (4) Use ammonia water with a mass concentration of 28%, soak in a mixed solution of ammonia water and hydrogen peroxide with a volume ratio of 3:7 for 30 seconds, rinse with a water gun, clean at room temperature, and clean for 30 seconds.

[0033] (5) Soak in a mixed solution of sulfuric acid and deionized water in a volume ratio of 1:40 for 45 seconds at room temperature.

[0034] (6) After cleaning, spin dry and place in a cartridge box that has been dried with nitrogen. After passing inspection, it can be packaged and shipped.

[0035] Examples 2-5 To verify the cleaning effect, Examples 2-5 were consistent with Example 1.

[0036] Comparative Examples 2-5 To compare the cleaning effects, Comparative Examples 2-5 were kept consistent with Comparative Example 1.

[0037] The cleaned wafers from Examples 1-5 and Comparative Examples 1-5 were tested, and the results are shown in Table 1. The specific test process is as follows: Two cleaned indium antimonide wafer substrates were randomly selected from each experimental group. The number of bright spots and the Haze value within the 0.15μm filter range on the indium antimonide wafer substrate were detected using a Tencor machine. The average value of each experimental group was taken.

[0038] Two cleaned indium antimonide wafer substrates were randomly selected from each experimental group. The thickness of the oxide layer on the indium antimonide wafer substrate was measured using an ellipsometry, and the average value was taken for each experimental group.

[0039] Two cleaned indium antimonide wafer substrates were randomly selected from each experimental group, and the silicon content on the indium antimonide wafer substrates was tested by TOF-SIMS surface analysis. The average value of each experimental group was taken.

[0040] The criterion for judging the yield rate is: check the surface of each wafer with a strong light to see if there are scratches, damage, chemicals, etc.

[0041] Table 1 It can be seen that the indium antimonide wafer cleaning process of this application can effectively improve the cleaning effect on the wafer surface.

[0042] The above are merely preferred embodiments of the present invention and are not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of the present invention.

Claims

1. A cleaning process for indium antimonide wafers, characterized in that, Includes the following steps: (1) The polished and dewaxed wafers were sequentially immersed in hot concentrated sulfuric acid and cold concentrated sulfuric acid. The hot concentrated sulfuric acid treatment process was as follows: immersion for 10~30s; temperature 50~70℃; sulfuric acid mass concentration of 70~98%; the cold concentrated sulfuric acid treatment process was as follows: immersion for 10~30s; temperature 30~45℃; sulfuric acid mass concentration of 70~98%. (2) The wafer processed in step (1) is placed in S1 cleaning solution for cleaning treatment, wherein S1 cleaning solution is a mixture of sulfuric acid, hydrogen peroxide and water; (3) The wafer processed in step (2) is placed in S2 cleaning solution for cleaning treatment. The S2 cleaning solution is a mixture of hydrofluoric acid and / or hydrochloric acid and water. The volume ratio of hydrofluoric acid and / or hydrochloric acid and water in the S2 cleaning solution is 1~5:6~12. The mass concentration of hydrofluoric acid used for preparation is ≥48.8%. The cleaning treatment time is 40~60s. (4) The wafer processed in step (3) is placed in S3 cleaning solution for cleaning treatment. The S3 cleaning solution is a mixture of phosphoric acid and / or sulfuric acid and / or sulfurous acid and water. The volume ratio of phosphoric acid and / or sulfuric acid and / or sulfurous acid and water in the S3 cleaning solution is 1~3:5~10. The mass concentration of phosphoric acid used for preparation is ≥85.0%. The cleaning treatment time is 30~60s. (5) Dry the wafer after step (4); In steps (2) to (4), the cleaning temperature is below 25°C.

2. The cleaning process as described in claim 1, characterized in that, In step (2), the volume ratio of sulfuric acid, hydrogen peroxide, and water in the S1 cleaning solution is 1~10:10~20:25~35; the mass concentration of sulfuric acid used for preparation is ≥70%; the mass concentration of hydrogen peroxide used for preparation is ≥30.0%; the cleaning temperature is 20~30℃; and the cleaning time is 10~30s.

3. The cleaning process as described in claim 1 or 2, characterized in that, A water rinsing process is set between steps (1) and (2), between steps (2) and (3), between steps (3) and (4), and between steps (4) and (5).

4. The cleaning process as described in claim 3, characterized in that, The rinsing process is as follows: place the wafer in a water tank and use a water gun to rinse the water tank while maintaining an overflow state; the overflow water volume is 20~60L / min.

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