A surface processing method for large-size cadmium zinc telluride substrate

Abstract

The application discloses a large-size CdZnTe substrate surface processing method, comprising the following steps: obtaining a cut CdZnTe wafer, polishing a first surface of the CdZnTe wafer until the cutting fluctuation on the first surface is removed to obtain a first wafer; thinning a second surface of the CdZnTe wafer, and then mechanically polishing the second surface to obtain a second wafer; taking the second wafer off the thinning carrier, performing X-ray diffraction appearance testing, obtaining an X-ray diffraction appearance graph corresponding to the second wafer, selecting a region with uniform contrast on the X-ray diffraction appearance graph, and marking the corresponding position of the second wafer; according to the marking of the corresponding position of the second wafer, the second wafer is cut into a regular-shaped CdZnTe substrate; the CdZnTe substrate is placed on a polishing carrier for substrate polishing processing, the polished CdZnTe substrate is protected by gluing, and after being taken off the polishing carrier, the CdZnTe substrate is cleaned to obtain a processed CdZnTe substrate.

Description

Technical Field

[0001] This application relates to the field of semiconductor material processing technology, and in particular to a method for surface processing of large-size cadmium zinc telluride substrates. Background Technology

[0002] Single-crystal zinc telluride (CdT) is the optimal substrate material for fabricating high-performance mercury cadmium telluride (HCTM) infrared focal plane array detectors. Large-size CdT substrates not only meet the development requirements of high-resolution, large-area HCTM infrared detectors, but are also one of the most effective means to improve the efficiency of HCTM epitaxy and front-end fabrication. By improving the processing technology of large-size CdT substrates, it is possible to support the research and production of larger batches of second- and third-generation HCTM infrared detectors.

[0003] The processing of cadmium zinc telluride (CZT) wafers typically involves chamfering, grinding, polishing, and cleaning. As the diameter of CZT crystals increases, and the wafer size after slicing reaches 50mm × 50mm or larger, a grinding process is required to remove surface irregularities and damaged layers from the substrate in order to obtain a better surface profile and lay the foundation for subsequent polishing. However, regardless of whether chamfering is performed before grinding or during the grinding process itself, the risk of fragmentation in large-size CZT wafers is high, resulting in a low yield and material waste. Furthermore, the surface flatness of the wafer after processing is difficult to control, which in turn affects subsequent epitaxial and device interconnection processes.

[0004] In view of this, how to provide a high-efficiency surface processing method for large-size zinc-cadmium telluride substrates with low fragmentation rate and good flatness, and avoid damage or cracks to the cut crystals during the cutting process, thereby reducing substrate loss, has become an urgent technical problem to be solved. Summary of the Invention

[0005] This application provides a method for surface processing of large-size zinc cadmium telluride substrates, which solves the problem of substrate loss caused by damage or cracks to the cut crystals during the current cutting process.

[0006] In a first aspect of this application, a method for surface processing of a large-size cadmium zinc telluride substrate is provided, comprising:

[0007] Obtain the cut cadmium zinc telluride wafer, place the cadmium zinc telluride wafer on a polishing carrier with the first surface facing upwards, and polish the first surface until the cutting undulations on the first surface are removed to obtain the first wafer;

[0008] With the second surface facing upwards, the first wafer is removed from the polishing substrate and placed on the thinning substrate. The second surface is then thinned, and the second surface of the cadmium zinc telluride wafer is mechanically polished to obtain the second wafer. The thickness of the second wafer meets the preset thickness condition, and the flatness of the second wafer meets the preset flatness condition.

[0009] The second wafer is removed from the thinned substrate and subjected to X-ray diffraction pattern testing to obtain the X-ray diffraction pattern corresponding to the second wafer. A region with uniform contrast on the X-ray diffraction pattern is selected and marked at the corresponding position on the second wafer.

[0010] According to the markings at the corresponding positions of the second wafer, the second wafer is cut into a regular-shaped cadmium zinc telluride substrate;

[0011] The zinc-cadmium telluride substrate is placed on a polishing carrier for substrate polishing. After polishing, the zinc-cadmium telluride substrate is coated with adhesive for protection. After being removed from the polishing carrier, the zinc-cadmium telluride substrate is cleaned to obtain the processed zinc-cadmium telluride substrate.

[0012] In one optional embodiment, placing the cadmium zinc telluride wafer on a polishing carrier and polishing the first surface until the cutting undulations on the first surface are removed to obtain the first wafer includes:

[0013] The zinc zinc cadmium wafer is attached to a polishing substrate using a die-attach wax, and the first surface is polished using a first polishing liquid until the cutting undulations on the surface of the first surface are removed to obtain a first wafer. The first polishing liquid is a diamond polishing liquid with a particle size range within a first particle size threshold range.

[0014] In one optional embodiment, the step of thinning the second surface and then mechanically polishing the second surface of the cadmium zinc telluride wafer to obtain a second wafer includes:

[0015] The second surface is thinned using a grinding wheel thinning machine, and then the second surface of the cadmium zinc telluride wafer is mechanically polished using a first polishing slurry to obtain a second wafer. The first polishing slurry is a diamond polishing slurry with a particle size range within a first particle size threshold range.

[0016] In one optional embodiment, the step of placing the cadmium zinc telluride substrate on a polishing carrier for substrate polishing includes:

[0017] The zinc zinc cadmium substrate is placed on a polishing carrier and mechanically polished using a second polishing slurry to obtain a first zinc zinc cadmium substrate, wherein the second polishing slurry is a diamond polishing slurry with a particle size range within a second particle size threshold range;

[0018] The first zinc-cadmium telluride substrate is chemically and mechanically polished using a third polishing slurry to obtain a second zinc-cadmium telluride substrate. The third polishing slurry is a silica sol polishing slurry with a particle size range within the third particle size threshold range, and oxidants and dispersants are added, the pH value is adjusted to the target pH threshold range, and the polishing pressure is within the preset polishing pressure threshold range.

[0019] In one optional embodiment, after removing the cadmium zinc telluride substrate from the polishing carrier, cleaning the substrate to obtain the processed cadmium zinc telluride substrate includes:

[0020] After being removed from the polishing substrate, the first side of the zinc cadmium telluride substrate was cleaned with petroleum ether, and the second side of the zinc cadmium telluride substrate was cleaned with petroleum ether, acetone and anhydrous ethanol in sequence. The substrate surface was then dried with dry nitrogen gas to obtain the processed zinc cadmium telluride substrate.

[0021] This application provides a method for surface processing of a large-size cadmium zinc telluride (CZN) substrate, comprising: first, obtaining a diced CZN wafer; placing the CZN wafer on a polishing substrate with its first surface facing upwards; polishing the first surface until the dicing undulations on the first surface are removed to obtain a first wafer; then, removing the first wafer from the polishing substrate with its second surface facing upwards; placing it on a thinning substrate; thinning the second surface; and then mechanically polishing the second surface of the CZN wafer to obtain a second wafer, wherein the thickness of the second wafer meets a preset thickness condition, and the flatness of the second wafer meets a preset flatness condition; Next, the second wafer is removed from the thinning carrier and subjected to X-ray diffraction pattern testing to obtain the corresponding X-ray diffraction pattern of the second wafer. A region with uniform contrast on the X-ray diffraction pattern is selected and marked at the corresponding position on the second wafer. Next, according to the marking at the corresponding position on the second wafer, the second wafer is cut into a regular-shaped cadmium zinc telluride substrate. Finally, the cadmium zinc telluride substrate is placed on a polishing carrier for substrate polishing. After polishing, the cadmium zinc telluride substrate is coated with adhesive for protection. After being removed from the polishing carrier, the cadmium zinc telluride substrate is cleaned to obtain the processed cadmium zinc telluride substrate.

[0022] The surface processing method for large-size zinc cadmium telluride substrates provided in the embodiments of this application has the following advantages: (1) It is suitable for processing large-size wafers and substrates with high processing efficiency; (2) It is suitable for processing irregularly shaped wafers; (3) The surface flatness of the substrate after processing is better while maintaining the original roughness and original surface quality; (4) The processing fragmentation rate is low.

[0023] The above description is merely an overview of the technical solution of this application. In order to better understand the technical means of this application and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this application more obvious and understandable, specific embodiments of this application are given below. Attached Figure Description

[0024] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the scope of this application. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings:

[0025] Figure 1 A schematic flowchart illustrating a method for surface processing of a large-size cadmium zinc telluride substrate provided in this application embodiment;

[0026] Figure 2 This is a block diagram illustrating a method for surface processing of a large-size cadmium zinc telluride substrate, as provided in an embodiment of this application. Detailed Implementation

[0027] Exemplary embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.

[0028] During the high-speed cutting of cadmium zinc telluride (CZN) crystals, damage or cracks may occur in the cut wafers. The main purpose of subsequent processing is to remove these damages and cracks. However, as the substrate size increases, the processing time for large-sized CZN substrates is long. Furthermore, during processing, due to increased grinding pressure, large abrasive grains are prone to causing cracks and cleavage in certain areas of the wafer surface under high pressure, resulting in substrate loss.

[0029] Furthermore, if only small-particle abrasive polishing is used to remove cutting damage, the processing time is not only long, but the wear and tear on the polishing pad is also increased. Because the polishing pad used in double-sided polishing is a soft polishing pad, the deformation of the polishing pad during polishing is not conducive to the surface flatness of the wafer after polishing. Moreover, after double-sided grinding, the amount of material removed in the double-sided polishing step is large (generally greater than 30μm), which further degrades the surface flatness of the wafer and cannot meet the requirements for subsequent use.

[0030] In order to overcome the above problems, this application provides a method for processing large-size cadmium zinc telluride substrates with high efficiency, low fragmentation rate, and good flatness when processing substrates with a substrate size of 50mm×50mm or larger.

[0031] See Figure 1 , Figure 1 This is a schematic flowchart illustrating a method for surface processing of a large-size cadmium zinc telluride substrate, as provided in an embodiment of this application. Figure 1 As shown, the specific steps include:

[0032] Step S102: Obtain the cut cadmium zinc telluride wafer, place the cadmium zinc telluride wafer on a polishing carrier with the first surface facing upwards, and polish the first surface until the cutting undulations on the first surface are removed to obtain the first wafer.

[0033] Step S104: With the second surface facing upwards, remove the first wafer from the polishing substrate and place it on the thinning substrate. Thin the second surface and then mechanically polish the second surface of the cadmium zinc telluride wafer to obtain the second wafer. The thickness of the second wafer meets the preset thickness condition, and the flatness of the second wafer meets the preset flatness condition.

[0034] Step S106: Remove the second wafer from the thinned substrate and perform X-ray diffraction pattern testing to obtain the X-ray diffraction pattern corresponding to the second wafer. Select the region with uniform contrast on the X-ray diffraction pattern and mark it at the corresponding position on the second wafer.

[0035] Step S108: According to the markings at the corresponding positions of the second wafer, the second wafer is cut into a regular-shaped cadmium zinc telluride substrate.

[0036] Step S110: Place the zinc-cadmium telluride substrate on a polishing carrier for substrate polishing. After polishing, apply adhesive to protect the zinc-cadmium telluride substrate. After removing it from the polishing carrier, clean the zinc-cadmium telluride substrate to obtain the processed zinc-cadmium telluride substrate.

[0037] In this embodiment of the application, the step of placing the cadmium zinc telluride wafer on a polishing carrier and polishing the first surface until the cutting undulations on the surface of the first surface are removed to obtain the first wafer includes:

[0038] The zinc zinc cadmium wafer is attached to a polishing substrate using a die-attach wax, and the first surface is polished using a first polishing liquid until the cutting undulations on the surface of the first surface are removed to obtain a first wafer. The first polishing liquid is a diamond polishing liquid with a particle size range within a first particle size threshold range.

[0039] In this embodiment of the application, the step of thinning the second surface and then mechanically polishing the second surface of the cadmium zinc telluride wafer to obtain the second wafer includes:

[0040] The second surface is thinned using a grinding wheel thinning machine, and then the second surface of the cadmium zinc telluride wafer is mechanically polished using a first polishing slurry to obtain a second wafer. The first polishing slurry is a diamond polishing slurry with a particle size range within a first particle size threshold range.

[0041] In this embodiment of the application, the step of placing the cadmium zinc telluride substrate on a polishing carrier for substrate polishing includes:

[0042] The zinc zinc cadmium substrate is placed on a polishing carrier and mechanically polished using a second polishing slurry to obtain a first zinc zinc cadmium substrate, wherein the second polishing slurry is a diamond polishing slurry with a particle size range within a second particle size threshold range;

[0043] The first zinc-cadmium telluride substrate is chemically and mechanically polished using a third polishing slurry to obtain a second zinc-cadmium telluride substrate. The third polishing slurry is a silica sol polishing slurry with a particle size range within the third particle size threshold range, and oxidants and dispersants are added, the pH value is adjusted to the target pH threshold range, and the polishing pressure is within the preset polishing pressure threshold range.

[0044] In this embodiment of the application, the step of cleaning the cadmium zinc telluride substrate after removing it from the polishing carrier to obtain the processed cadmium zinc telluride substrate includes:

[0045] After being removed from the polishing substrate, the first side of the zinc cadmium telluride substrate was cleaned with petroleum ether, and the second side of the zinc cadmium telluride substrate was cleaned with petroleum ether, acetone and anhydrous ethanol in sequence. The substrate surface was then dried with dry nitrogen gas to obtain the processed zinc cadmium telluride substrate.

[0046] This application provides a processing method for large-size cadmium zinc telluride substrates, including A-side polishing, B-side thinning, X-ray diffraction morphology testing, dicing, substrate polishing, wafer removal, and cleaning. See [link to relevant documentation]. Figure 2 , Figure 2 This is a block diagram illustrating a method for surface processing of a large-size cadmium zinc telluride substrate, as provided in an embodiment of this application.

[0047] Compared to the conventional method of double-sided grinding – double-sided polishing – X-ray diffraction morphology testing – dicing – substrate polishing – wafer removal – cleaning, this application's embodiments abandon the double-sided grinding and double-sided polishing steps, replacing them with abrasive wheel thinning and single-sided polishing. Abrasive wheel thinning is a method of material removal using bonded abrasives. Compared to grinding with free abrasives, it avoids the problem of increased pressure in local areas of the wafer caused by abrasive agglomeration, which can lead to wafer cracks or even wafer breakage. Due to the growth of cadmium zinc telluride crystals, the resulting single wafers are irregular. In double-sided grinding and double-sided polishing, the wafer will collide with the edge of the abrasive wheel hole multiple times, which can easily cause edge chipping. Excessive stress can directly cause wafer cleavage. However, using abrasive wheel thinning and single-sided polishing processes can avoid the above problems during wafer surface removal. In addition, due to the increase in wafer size, the number of wafers processed in a single double-sided grinding and double-sided polishing process is reduced, and the processing efficiency of abrasive wheel thinning is comparable to that of single-sided polishing. Finally, by employing these two processes, the deterioration of wafer surface flatness caused by double-sided polishing can be avoided.

[0048] Specifically, in this embodiment, the polishing of surface A includes: taking... <111> or <211> After the crystal orientation cutting of the cadmium zinc telluride wafer is completed, the A-side is adhered to the polishing substrate using a die-attachment wax and then polished using a diamond polishing slurry with a particle size of (0.25-5) μm. Polishing is carried out until the cutting undulations are completely removed, resulting in a smooth and bright surface.

[0049] The B-side thinning process includes: removing the wafer with the A-side polished from the polishing carrier, attaching it to the thinning carrier with the B-side facing out using die-attachment wax, and using a grinding wheel thinning machine to thin the B-side of the wafer to a target thickness 40–80 μm higher than the final substrate thickness. The flatness of the thinning carrier must be better than 5 μm.

[0050] If cracking occurs during the thinning process, the cracking phenomenon can be improved by increasing the thickness of the substrate.

[0051] After the abrasive wheel is used to thin the substrate, mechanical polishing is performed. The polishing fluid is diamond polishing fluid with a particle size of (0.25-5) μm. The target thickness after thinning is 30-70 μm higher than the target thickness of the final substrate. Polishing is performed until a smooth and bright surface is obtained.

[0052] The implementation of X-ray diffraction morphology testing includes: removing the B-side thinned cadmium zinc telluride wafer from the thinning carrier, performing X-ray diffraction morphology testing, obtaining the X-ray diffraction morphology image of the entire wafer, selecting areas with uniform contrast, and marking the corresponding positions on the wafer.

[0053] The dicing process involves dicing the cadmium zinc telluride wafer into a cadmium zinc telluride substrate of a regular shape according to the markings on the wafer.

[0054] The substrate polishing process includes: attaching the diced cadmium zinc telluride substrate to a polishing carrier using a substrate adhesive wax; first, performing mechanical polishing using a diamond polishing slurry with a particle size no larger than 3 μm, aiming for a polishing thickness 10 μm greater than the final substrate target thickness; then, performing chemical mechanical polishing, again aiming for the final substrate thickness target, using a silica sol polishing slurry with a particle size of 50–120 nm, adding oxidants and dispersants, and adjusting the pH to 4–5; and maintaining a polishing pressure of 70 g / cm². 2 ~130g / cm 2 set up.

[0055] The wafer removal and cleaning process includes: applying a protective coating to the polished substrate, removing the substrate from the polished wafer, cleaning the substrate A side with petroleum ether, cleaning the substrate B side with petroleum ether, acetone and anhydrous ethanol in sequence, and drying the substrate surface with dry nitrogen gas.

[0056] Compared to the conventional method of chamfering – double-sided grinding – double-sided polishing – X-ray diffraction morphology testing – scribing – substrate polishing – wafer removal and cleaning, the results of processing five 80mm×80mm substrates were compared, as shown in the table below:

[0057] Table 1. Relevant test results after two processing methods

[0058] conventional methods Method of the present invention Fragmentation rate 40％ 0％ Processing efficiency 1 tablet / day Approximately 1.3 tablets / day average roughness 0.33nm~0.56nm 0.31nm~0.51nm Surface flatness 3.58μm~6.24μm 1.96μm~3.87μm Double crystal diffraction full width at half maximum (FWHM) 12–18 arcsec 10–17 arcsec

[0059] The method of the present invention significantly reduces the fragmentation rate compared with conventional methods when the substrate surface quality is comparable (i.e., the average roughness of the substrate surface and the half-width of the double crystal diffraction peak are comparable), and greatly improves the processing efficiency and the flatness of the substrate surface after processing.

[0060] In addition, this application also provides two embodiments.

[0061] Example 1: Take <111> The crystal orientation-oriented cadmium zinc telluride wafers can be diced to produce 80mm × 80mm cadmium zinc telluride substrates with a thickness of 1500μm to 1650μm, with a final processing target thickness of 900μm to 1250μm. Processing is carried out according to steps (1) to (6) above. Large-size substrates processed using this method exhibit good surface flatness and roughness. The surface flatness of the substrate was measured to be 1.9μm using an optical profilometer. Roughness was measured at three randomly selected points on the substrate surface using a white light interferometer, with results of 0.33nm, 0.38nm, and 0.38nm, respectively.

[0062] Example 2: Taking <211> The crystal orientation-oriented cadmium zinc telluride wafers can be diced to produce 60mm × 60mm cadmium zinc telluride substrates with a thickness of 1300μm to 1400μm, and a final target thickness of 800μm to 1050μm. The wafers are processed according to steps (1) to (6) above. The large-size substrates processed using this method exhibit good surface flatness and roughness. The surface flatness of the substrate was measured to be 1.8μm using an optical profilometer. Roughness was measured at three randomly selected points on the substrate surface using an optical profilometer, with results of 0.51nm, 0.49nm, and 0.53nm, respectively.

[0063] The substrates processed in the above two embodiments can be used as epitaxial substrates. Therefore, the embodiments of this application can be used as a method for processing large-size wafers.

[0064] The beneficial effects that can be achieved by applying the embodiments of this application are: (1) it is suitable for processing large-size wafers and substrates with high processing efficiency; (2) it is suitable for processing irregularly shaped wafers; (3) after processing, the substrate maintains its original roughness and surface quality while having good surface flatness; (4) the processing breakage rate is low.

[0065] The various embodiments in this specification are described in a progressive manner. Similar or identical parts between embodiments can be referred to interchangeably. Each embodiment focuses on describing the differences from other embodiments. In particular, the apparatus for processing large-size cadmium zinc telluride substrates is basically similar to the embodiments for processing large-size cadmium zinc telluride substrates, so the description is relatively simple. Relevant details can be found in the descriptions of the embodiments for processing large-size cadmium zinc telluride substrates.

[0066] It should be noted that the above description describes specific embodiments of this specification. Other embodiments are within the scope of the appended claims. In some cases, the actions or steps recorded in the claims can be performed in a different order than that shown in the embodiments and still achieve the desired results. Furthermore, the processes depicted in the drawings do not necessarily require a specific or sequential order to achieve the desired results. In some embodiments, multitasking and parallel processing are also possible or may be advantageous. Secondly, those skilled in the art should also understand that the embodiments described in the specification are preferred embodiments, and the actions and modules involved are not necessarily essential to the embodiments of this specification.

[0067] In the above embodiments, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0068] The preferred embodiments disclosed above are merely illustrative of this specification. The optional embodiments do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. Clearly, many modifications and variations can be made based on the embodiments described herein. These embodiments are selected and specifically described in this specification to better explain the principles and practical applications of the embodiments, thereby enabling those skilled in the art to better understand and utilize this specification. This specification is limited only by the claims and their full scope and equivalents.

Claims

1. A method for surface processing of large-size cadmium zinc telluride substrates, characterized in that, include: Obtain the cut cadmium zinc telluride wafer, place the cadmium zinc telluride wafer on a polishing carrier with the first surface facing upwards, and polish the first surface until the cutting undulations on the first surface are removed to obtain the first wafer; With the second surface facing upwards, the first wafer is removed from the polishing substrate and placed on the thinning substrate. The second surface is then thinned, and the second surface of the cadmium zinc telluride wafer is mechanically polished to obtain the second wafer. The thickness of the second wafer meets the preset thickness condition, and the flatness of the second wafer meets the preset flatness condition. The second wafer was removed from the thinned substrate and subjected to X-ray diffraction pattern testing to obtain the X-ray diffraction pattern corresponding to the second wafer. A region with uniform contrast on the X-ray diffraction pattern was selected and marked at the corresponding position on the second wafer. According to the markings at the corresponding positions of the second wafer, the second wafer is cut into a regular-shaped cadmium zinc telluride substrate; The zinc-cadmium telluride substrate is placed on a polishing carrier for substrate polishing. After polishing, the zinc-cadmium telluride substrate is coated with adhesive for protection. After being removed from the polishing carrier, the zinc-cadmium telluride substrate is cleaned to obtain the processed zinc-cadmium telluride substrate. The step of placing the cadmium zinc telluride wafer on a polishing carrier and polishing the first surface until the cutting undulations on the first surface are removed to obtain the first wafer includes: The zinc zinc cadmium wafer is attached to a polishing substrate using a die-attach wax, and the first surface is polished using a first polishing liquid until the cutting undulations on the surface of the first surface are removed to obtain a first wafer. The first polishing liquid is a diamond polishing liquid with a particle size range within a first particle size threshold range. The process of thinning the second surface and then mechanically polishing the second surface of the cadmium zinc telluride wafer to obtain a second wafer includes: The second surface is thinned using a grinding wheel thinning machine, and then the second surface of the cadmium zinc telluride wafer is mechanically polished using a first polishing slurry to obtain a second wafer. The target thickness after thinning is 30-70 μm higher than the target thickness of the final substrate. The first polishing slurry is a diamond polishing slurry with a particle size range within the first particle size threshold range.

2. The method according to claim 1, characterized in that, The step of placing the cadmium zinc telluride substrate on a polishing carrier for substrate polishing includes: The zinc zinc cadmium substrate is placed on a polishing carrier and mechanically polished using a second polishing slurry to obtain a first zinc zinc cadmium substrate, wherein the second polishing slurry is a diamond polishing slurry with a particle size range within a second particle size threshold range; The first zinc-cadmium telluride substrate is chemically and mechanically polished using a third polishing slurry to obtain a second zinc-cadmium telluride substrate. The third polishing slurry is a silica sol polishing slurry with a particle size range within the third particle size threshold range, and oxidants and dispersants are added, the pH value is adjusted to the target pH threshold range, and the polishing pressure is within the preset polishing pressure threshold range.

3. The method according to claim 1, characterized in that, After being removed from the polishing carrier, the zinc-cadmium telluride substrate is cleaned to obtain the processed zinc-cadmium telluride substrate, including: After being removed from the polishing substrate, the first side of the zinc cadmium telluride substrate was cleaned with petroleum ether, and the second side of the zinc cadmium telluride substrate was cleaned with petroleum ether, acetone and anhydrous ethanol in sequence. The substrate surface was then dried with dry nitrogen gas to obtain the processed zinc cadmium telluride substrate.

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