A back surface protection method for a cadmium zinc telluride / cadmium telluride wafer

Abstract

The application belongs to the technical field of compound semiconductor material crystal protection, and discloses a back surface protection method for a CdZnTe / CdTe wafer. The method aims to solve the problem that the back surface of the brittle semiconductor wafer is easily in contact with equipment during the front surface pixelization process, which causes scratches and further affects the performance of the detector. The method comprises the following steps: pasting a layer of debondable protective adhesive film on the back surface of the wafer; then performing processes such as front surface photoetching and electrode deposition; after the processes are completed, the debonding property of the adhesive film is activated by heating, ultraviolet irradiation or energization, so that the adhesive force of the adhesive film is greatly reduced or disappears; finally, the adhesive film is peeled off, and the back surface of the wafer is cleaned. The protective adhesive film can be pyrolytic, UV debondable or electrochemical, can stably adhere and provide physical isolation during the process, and can be removed cleanly and with low stress after the process. The method can effectively prevent the back surface of the wafer from being scratched, avoid the residual of the adhesive, and help improve the production yield and electrical performance consistency of the final device.

Description

Technical Field

[0001] This invention belongs to the field of crystal protection technology for compound semiconductor materials, and discloses a method for back-side protection of cadmium zinc telluride / cadmium telluride wafers. Background Technology

[0002] Cadmium zinc telluride (CdZnTe, CZT) and cadmium telluride (CdTe), as group II-VI compound semiconductor materials, have become key materials in high-performance X-ray and gamma-ray detectors, space astronomical observations, medical imaging, and security inspection equipment due to their high resistivity, high carrier mobility lifetime product, wide bandgap, and good room-temperature operating characteristics. In these applications, it is typically necessary to fabricate a finely pixelated electrode array on the front side of the wafer to form independent detection units. This process mainly relies on precise microelectronic fabrication techniques such as photolithography and thin-film deposition.

[0003] In standard pixelation processes, wafers are vacuum-adsorbed onto a stage (suction cup) of equipment such as spin coaters, exposure machines, or hot plates, and may undergo heating and cooling processes. During this process, the back side of the wafer (i.e., the non-patterned side) inevitably comes into direct contact and friction with the surface of the equipment, which is made of metal, ceramic, or polymer. However, CZT and CdTe materials are relatively low in hardness and brittle, and their surfaces (especially the polished back side) are extremely sensitive to mechanical stress. Even tiny scratches or stress defects can introduce additional charge carrier trapping centers inside the crystal, leading to decreased charge collection efficiency, deteriorated energy resolution, and increased leakage current, ultimately severely affecting detector performance and imaging quality. Therefore, the integrity of the wafer's back side is crucial to the yield and performance of the final device.

[0004] Currently, in the semiconductor manufacturing field, temporary bonding adhesives or protective tapes are typically used to protect the back side of traditional silicon-based wafers during specific process steps. However, applying these conventional protection methods directly to CZT / CdTe wafers presents a series of unique challenges: 1. Chemical compatibility issues: CZT / CdTe materials are sensitive to many organic solvents and chemicals. The pressure-sensitive adhesive used in conventional protective tapes may remain on the surface after processing and is difficult to completely remove through standard cleaning steps. Adhesive residue can contaminate the wafer surface, affecting subsequent ohmic contacts or packaging processes.

[0005] 2. Insufficient resistance to process conditions: The pixelation process may involve high baking temperatures (such as photoresist hardening), vacuum environments, and physical vapor deposition (PVD) steps. Under these conditions, ordinary protective tapes may experience softening of the adhesive layer, adhesive overflow, carbonization, or a sharp increase in stickiness, leading to difficulty in peeling or more residue.

[0006] 3. Inability to achieve non-destructive peeling: If the mechanical force applied during the peeling of the protective layer is too large after the process is completed, it is very easy to cause new cracks or hidden damage to the brittle CZT / CdTe wafer, which will also impair the device performance.

[0007] In summary, the existing technology lacks a back-side protection method specifically designed for the characteristics of CZT / CdTe wafers. This method needs to meet the following requirements: reliably physically isolate the back of the wafer from the equipment during the process, withstand relevant temperature, vacuum, and chemical environments; and be easily, thoroughly, and with low stress removed after the process, without introducing any form of contamination or damage. Summary of the Invention

[0008] To address the issues in the background art where the back side of cadmium zinc telluride / cadmium telluride wafers is easily scratched during pixelation processes, and where traditional protection methods suffer from adhesive residue, poor process compatibility, and peel stress damage, this invention provides a reliable, residue-free, and highly process-adaptable method for de-adhesive protection of the back side of cadmium zinc telluride / cadmium telluride wafers. This method involves applying a thermal / optical / electrolytic adhesive protective film to the back side of the wafer and activating de-adhesive peeling after the process, achieving physical isolation and non-destructive adhesive removal of the back side of the wafer throughout the entire manufacturing process, effectively improving the yield and performance consistency of detector devices.

[0009] To achieve the above objectives, the present invention includes the following technical solutions: A method for back-side protection of cadmium zinc telluride / cadmium telluride wafers, comprising the following steps: (1) Provide a zinc zinc cadmium wafer or a cadmium telluride wafer, and clean and surface treat its back side; (2) A layer of removable protective film with a thickness of 10~200 μm is attached to the back of the wafer so that the film completely covers the back of the wafer. (3) On the front side of the wafer covered with the protective film, a pixelated electrode fabrication process is performed, the process including at least photoresist coating, patterned exposure, development and metal electrode deposition; (4) The protective film is de-adhesively treated by at least one of heat, ultraviolet light or electric current, so that its adhesion to the back of the wafer is lost or reduced to less than 0.2 N / cm; (5) Peel the debonded protective film off the back of the wafer, and clean and dry the back of the wafer to complete the protection process.

[0010] Furthermore, in the above-mentioned back-side protection method, the cleaning and surface treatment in step (1) includes: sequentially using organic solvent, acidic or alkaline cleaning solution, and deionized water to perform ultrasonic cleaning on the back side of the wafer, and then drying it with nitrogen gas.

[0011] Furthermore, in the above-mentioned back protection method, the detackable protective film in step (2) is a thermally detackable adhesive tape, and the detack treatment in step (4) includes heating at a temperature of 50℃ to 250℃ for 10 seconds to 10 minutes.

[0012] Furthermore, in the aforementioned back protection method, the heating temperature is 100℃~200℃, and the heating time is 30 seconds~5 minutes.

[0013] Furthermore, in the above-mentioned back protection method, the removable protective film mentioned in step (2) is a UV removable adhesive tape, and the de-adhesion treatment in step (4) includes irradiation with ultraviolet light with a wavelength of 365 nm to 400 nm and an irradiation energy of 100 to 1000 mJ / cm. 2 The irradiation time is 10 seconds to 2 minutes.

[0014] Furthermore, in the above-mentioned back protection method, the de-adhesive protective film mentioned in step (2) is an electrolytic adhesive tape, and the de-adhesive treatment in step (4) includes applying a DC voltage of 6 V to 12 V for a power-on time of 1 second to 60 seconds.

[0015] Furthermore, in the above-mentioned back-side protection method, the cleaning in step (5) includes immersing the wafer in an organic solvent at 60°C to 90°C and ultrasonically treating it for 1 to 15 minutes. The organic solvent is selected from one or more combinations of N-methylpyrrolidone, acetone, and isopropanol.

[0016] This invention discloses a semiconductor wafer with a temporary protective structure prepared by the above method, comprising: Cadmium zinc telluride or cadmium telluride wafer substrate; A removable protective adhesive film completely covering the back side of the wafer substrate; and a pixelated metal electrode pattern formed on the front side of the wafer substrate.

[0017] The present invention also discloses the application of the above-mentioned semiconductor wafer with temporary protective structure in the fabrication of radiation detector devices or imaging sensor devices.

[0018] The present invention also discloses a de-adhesive protective film assembly specifically for the back protection method described in the present invention, comprising: a flexible substrate, and a de-adhesive layer coated on the flexible substrate; the de-adhesive layer has an initial adhesion force of 2 to 10 N / cm to cadmium zinc telluride or cadmium telluride wafers in an unactivated state, and its adhesion force decreases to less than 0.2 N / cm after being activated by at least one of heat, ultraviolet light or electrical stimulation.

[0019] Compared with the prior art, the present invention has the following outstanding advantages: 1. Effective protection: By forming a stable physical isolation layer on the back of the wafer, it can effectively prevent direct contact between the wafer and the equipment surface during process flow, adsorption and heating, significantly reducing the risk of mechanical damage such as scratches and indentations on the back.

[0020] 2. Clean Removal: The special removable adhesive film used loses its adhesiveness after activation, allowing it to be easily and completely peeled off from the wafer surface. This avoids the problem of stubborn residue caused by traditional tapes, ensuring the cleanliness of the back side.

[0021] 3. Good process compatibility: The selected protective film can withstand the heat baking, solvent contact and vacuum environment commonly encountered in the pixelation process, and maintain stable adhesion throughout the entire process cycle without spontaneously falling off or contaminating the process chamber.

[0022] 4. Improve device performance: By protecting the integrity of the back side of the wafer and avoiding secondary damage and contamination during the removal process, it helps to reduce the dark current of the fabricated detector and improve the uniformity of its charge collection efficiency, thereby improving the overall performance and reliability of the device.

[0023] 5. Simple operation and suitable for production: The coating and debonding process is simple, requiring no complex and expensive equipment. It is easy to integrate into existing production lines, suitable for batch wafer processing, and has good prospects for industrial application. Attached Figure Description

[0024] Figure 1 It demonstrates the temporary structure of the entire wafer during the pixelation process; Figure 2 A schematic diagram of the pixelation process for cadmium zinc telluride and cadmium telluride wafers; Figure 3 For comparison of the surface finish of the wafers in Test Example 1; The components include: 1. Adhesives, such as UV / thermal / electrolytic adhesives; 2. Cadmium zinc telluride / cadmium telluride; 3. Photoresist; and 4. Electrodes. Detailed Implementation

[0025] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0026] Please see Figure 1 and Figure 2 . Figure 1 This is a schematic diagram of the cross-sectional structure of the wafer after protection using this method. Figure 2 A complete process flow diagram based on UV-cured adhesive release film is shown. The following embodiments will be described in conjunction with the accompanying drawings.

[0027] Example 1 Pyrolytic adhesive film protection method This embodiment provides a back protection method using pyrolytic adhesive tape, the specific steps of which are as follows: 1) Wafer pretreatment: Take a 15.5mm×18mm×2mm double-sided polished cadmium zinc telluride (CZT) wafer, and ultrasonically clean it in wax removal solution, alkaline cleaning solution and isopropanol for 10 minutes in sequence. After rinsing with deionized water, blow it dry with high-purity nitrogen. Passivate it in a mixture of 10% ammonium fluoride and hydrogen peroxide for 10 minutes. After rinsing with deionized water, blow it dry with high-purity nitrogen.

[0028] 2) Applying a protective film: Using a film applicator, apply a 50μm thick layer of pyrolytic adhesive tape (Revalpha model) to the back of the wafer. TM (Nitto Denko), ensuring the tape completely covers the back of the chip without any air bubbles.

[0029] 3) Front-side pixelation process: The wafer with a protective film is fixed face up on a spin coater, and a negative photoresist (model ROL7133) is spin-coated. After soft baking, it is patterned and exposed in a photolithography machine. After development, a pixel array pattern is formed. Subsequently, it is placed in a magnetron sputtering device to deposit a 34nm thick platinum electrode on the front side of the wafer.

[0030] 4) Thermal debonding treatment: The wafer with completed electrode deposition is placed on a hot plate and heated in an air atmosphere at 150°C for 2 minutes. At this time, the adhesion of the thermal debonding tape decreases from the initial 5 N / cm to close to 0 N / cm.

[0031] 5) Peeling and post-processing: Easily peel off the adhesive tape on the back with tweezers. The back of the wafer is as bright as new, with no visible adhesive residue. Immerse the wafer in N-methylpyrrolidone (NMP) at 75°C and gently agitate for 1 minute. Then rinse with isopropanol and deionized water and dry with nitrogen.

[0032] Results: Inspection revealed no new scratches on the back of the wafer. Testing of the fabricated detector unit showed a charge collection efficiency uniformity of 98.5%, indicating effective back-side protection without introducing damage or contamination.

[0033] Example 2 UV adhesive film protection method This embodiment provides a back protection method using UV adhesive tape, the specific steps of which are as follows: 1) Wafer pretreatment: Take a cadmium telluride (CdTe) wafer and clean it in the same way as in Example 1.

[0034] 2) Applying a protective film: Apply a layer of UV release tape (model ULTRON® System) with a thickness of 80μm to the back of the wafer. This tape is sensitive to ultraviolet light with a wavelength of 365-400nm.

[0035] 3) Front-side pixelation process: The same photolithography and electrode (gold electrode in this case) deposition process as in Example 1 is performed. Throughout the process, the back side of the wafer is in contact with the vacuum chuck, hot plate, etc.

[0036] 4) UV debonding treatment: Place the wafer in a UV debonding machine and irradiate it for 30 seconds at a wavelength of 365nm and an intensity of 500 mJ / cm2.

[0037] 5) Peeling and Post-processing: After irradiation, the adhesive of the tape almost disappeared. After easy peeling, there was no adhesive residue on the back of the wafer. Subsequent cleaning steps were the same as in Example 1.

[0038] Results: The back side of the wafer remained intact. This method is particularly suitable for heat-sensitive process routes, avoiding high-temperature steps.

[0039] Example 3 Electrolytic adhesive film protection method This embodiment provides a back protection method using electrolytic adhesive tape, the specific steps of which are as follows: 1) Wafer pretreatment and film application: Take a CZT wafer, clean it, and then apply a special electrolytic adhesive tape to its back. This tape consists of a conductive polymer adhesive layer and a flexible substrate.

[0040] 2) Front pixelation process: complete front photolithography and electrode deposition.

[0041] 3) Electrolytic bonding treatment: Connect the positive and negative terminals of a DC power supply to specific conductive contacts of the electrolytic adhesive tape, apply a 10V DC voltage, and hold for 20 seconds. The electrochemical reaction causes a sharp decrease in the cohesive strength of the adhesive layer.

[0042] 4) Peeling: After power is off, the tape can be easily picked up from the edge of the chip and completely peeled off.

[0043] Results: The peeling process is fast and involves minimal stress, making it ideal for ultra-thin or fragile wafers. No damage was found on the back side.

[0044] Comparative Example 1 Use ordinary pressure-sensitive tape for protection. Using CZT wafers of the same specifications as in Example 1, ordinary polyimide high-temperature tape (Kapton® tape) was applied to the back. After completing the same front-side pixelation process, an attempt was made to peel it off. It was found that the tape was still very sticky, and after forcibly peeling it off, a large amount of visible adhesive residue was left on the back of the wafer, and some of the residue had solidified. It was difficult to remove the residue by soaking it in a strong solvent for a long time and wiping it vigorously. This process could easily cause secondary scratches on the wafer surface.

[0045] Comparative Example 2 Spin-coated photoresist was used as a protective layer. A layer of positive photoresist (model AZ1500) approximately 10 μm thick is manually applied to the back of the CZT wafer and cured at high temperature (110°C, 10 minutes) to attempt to form a protective layer. After the process is complete, the positive photoresist on the back of the CZT wafer can be removed during a stripping process (NMP stripping). This process is not only cumbersome and has low mass production feasibility, but also poses a potential chemical corrosion risk to the surface of CZT / CT materials due to the strong chemical solvents. Furthermore, the waste liquid generated is costly to treat, which is inconsistent with the trend of green manufacturing.

[0046] Comparative Example 3 No back protection CZT wafers undergo a complete front-side pixelation process without any back-side protection. After the process, observation under an optical microscope revealed multiple obvious linear scratches and dot-like indentations on the back of the wafers. When these wafers were fabricated into detectors and tested, their dark current was significantly higher than that of the protected samples, and the performance fluctuations (non-uniformity) between different pixels increased by more than 15%.

[0047] Test Example 1 Backside protection effect and macroscopic surface quality test Objective: To verify the protective effect of the method of the present invention against macroscopic scratches and contamination on the back of the wafer after simulating real-world processes.

[0048] method: 1. Sample preparation for testing: Six identical cadmium zinc telluride (CZT) wafers were selected and divided into three groups: The present invention group (A1, A2) adopts the back protection method of Example 1 (pyrolytic adhesive film).

[0049] Comparative Example 1 (B1, B2): Backside protection was performed using ordinary high-temperature tape (such as Kapton tape).

[0050] Comparative Example 2 (C1, C2): No back protection.

[0051] 2. Simulated Processing: All wafers undergo a simulated standard front-side pixelation process, including three adsorption / release cycles on the spin coater chuck, baking on a 180°C hot plate for 5 minutes, and placement in a vacuum coating chamber for 30 minutes.

[0052] 3. Protective Layer Removal and Post-treatment: After the process, the present invention group unbonded and peeled off the adhesive film according to the method, and then cleaned with acetone, isopropanol and deionized water. Comparative Example 1 group attempted to directly peel off ordinary tape and clean it with the same solvent. Comparative Example 2 group was cleaned directly.

[0053] 4. Macroscopic detection and evaluation: Visual and magnifying glass inspection: Under sufficient light and with a 20x magnifying glass, two operators independently inspect the entire back of the chip.

[0054] Evaluation items: 1) Scratches: Record the number of observable linear scratches or pits.

[0055] 2) Adhesive residue: Assess whether there is any visible or perceptible sticky residue on the back.

[0056] 3) Surface gloss change: Compared with a raw wafer that has only undergone passivation treatment, evaluate whether there is a significant change in the gloss of the back side (hazing).

[0057] Results: See Table 1. Figure 3 .

[0058] Conclusion: The method of this invention effectively prevents macroscopic scratches on the back of the wafer during the manufacturing process, and leaves no visible or tactile adhesive residue after removing the protective layer, perfectly preserving the original surface gloss and cleanliness of the back. Ordinary adhesive tapes, due to their excessive stickiness and inability to withstand process conditions, are difficult to remove and cause severe contamination; while unprotected wafers suffer direct and severe mechanical damage. This proves that the physical isolation and clean removal capabilities provided by this invention are completely effective on a macroscopic scale.

[0059] Test Example 2 Test on the impact of protection process on the basic electrical performance of the detector Objective: To evaluate whether the key electrical performance of the detector prepared by the back protection method of the present invention is superior to that of devices prepared by unprotected or conventional protection methods.

[0060] method: Device fabrication: Nine cadmium telluride (CdTe) wafers with similar resistivity were selected and divided into three groups of three wafers each.

[0061] Group E (Invention): The back side protection is performed using the scheme of Example 2 (UV de-adhesive film), followed by the pixelation process of the front platinum electrode, de-adhesion peeling and cleaning.

[0062] Group F (Traditional Protection): The back side protection was carried out using the Comparative Example 2 (spin-coating and curing photoresist) scheme. After completing the same front side process, the protective layer was removed with a strong stripping solution and the area was cleaned.

[0063] Group G (No Protection): Directly performs front pixelation process, without any back protection.

[0064] Complete device fabrication: Deposit full gold electrodes on the back of all wafers to form the final planar detector device.

[0065] Electrical performance tests (conducted under the same test environment): Dark current: At room temperature, a -100V bias voltage is applied to each device, and the leakage current value is measured after stabilization.

[0066] Response uniformity: using a stable 55 The entire effective area of ​​the device was irradiated with an Fe radiation source (5.9 keV X-rays), and the output pulse amplitude of all pixels was recorded using a multichannel analyzer. The standard deviation of the average amplitude of all pixels was calculated to evaluate the spatial uniformity of the device response.

[0067] Results: See Table 2.

[0068] Conclusion: The detector device fabricated using the back-side protection method of this invention exhibits significantly lower dark current than devices fabricated using traditional protection and unprotected methods, and also demonstrates the best response uniformity. This indicates that the method of this invention protects the wafer from physical damage while avoiding the negative impacts of chemical residues or stress damage on lattice integrity and electrical performance, thereby directly leading to a comprehensive improvement in the final device performance.

[0069] Test Example 3 Protective film process stability and debonding reliability testing Objective: To verify, under actual process conditions, whether the protective film will peel off, contaminate the process chamber, and whether the debonding function remains reliable.

[0070] method: 1. Stability test: Three CZT wafers coated with the pyrolytic adhesive film described in this invention, along with three blank silicon wafers without the film, are placed into an actual magnetron sputtering coating apparatus.

[0071] Run a complete platinum electrode deposition process (approximately 60 minutes, vacuum level ~10⁻³ Pa, substrate temperature ~80℃).

[0072] After the process is completed, check: a) whether the protective film has bubbles, curling edges or peeling off; b) whether there is an abnormal increase in particles or gel-like contaminants on the inner wall of the process chamber and on the carrier; c) compare the metal deposition quality on the front side of the blank silicon wafer to assess whether the film venting affects the coating uniformity.

[0073] 2. Reliability test of de-adhesion function: The CZT wafer with coating after the above coating process is removed.

[0074] Perform the de-adhesion process according to its design (heat in a 150℃ oven for 2 minutes).

[0075] Assessment: a) After unbonding, can the adhesive film be easily and completely peeled off with tweezers? b) After peeling off, is the back of the wafer and the adhesive film itself clean, without any tears or delamination?

[0076] result: 1) Stability Results: The adhesive films on all three wafers remained flat and without peeling. No abnormal contamination was found during the process chamber cleanliness check. The platinum film on the blank silicon wafer was uniform and bright, showing no difference from normal operation, indicating that the adhesive film has good stability under vacuum and moderate temperature, and does not affect normal process operation.

[0077] 2) Debonding reliability results: The adhesive films on all three wafers successfully debonded after heating and could be easily and completely peeled off. After peeling, the back side of the wafer was clean, and the adhesive film itself remained intact.

[0078] 3) Conclusion: The debonded protective film selected in this invention can withstand the actual vacuum coating process environment without failing or becoming a source of contamination. After completing the key processes, its debonding function remains reliable, achieving the preset goal of clean and complete peeling. This proves that the solution has high feasibility and reliability in production practice.

[0079] It is worth noting that the above description of the embodiments focuses on illustrating the technical solution of the present invention, rather than precisely defining its scope of protection. Those skilled in the art should understand that appropriate adjustments and optimizations can be made based on the technical details disclosed in the embodiments of the present invention, or equivalent substitutions can be implemented for individual or even all technical elements. Such adjustments and substitutions will not deviate from the core essence of the technical solution of the present invention and should be included within the technical protection scope of the embodiments of the present invention. In short, the protection of the present invention should not be limited to the concrete presentation of the above embodiments, but broadly covers all equivalent changes and improvements that do not depart from its basic concept. In summary, the protection definition of the present invention should be based on the statement of the claims, and the above embodiments are only used as a reference guide for understanding the present invention.

Claims

1. A method for back-side protection of cadmium zinc telluride / cadmium telluride wafers, characterized in that, Includes the following steps: (1) Provide a zinc zinc cadmium wafer or a cadmium telluride wafer, and clean and surface treat its back side; (2) A layer of removable protective film with a thickness of 10~200 μm is attached to the back of the wafer so that the film completely covers the back of the wafer. (3) On the front side of the wafer covered with the protective film, a pixelated electrode fabrication process is performed, the process including at least photoresist coating, patterned exposure, development and metal electrode deposition; (4) The protective film is de-adhesively treated by at least one of heat, ultraviolet light or electric current, so that its adhesion to the back of the wafer is lost or reduced to less than 0.2 N / cm; (5) Peel the debonded protective film off the back of the wafer, and clean and dry the back of the wafer to complete the protection process.

2. The method according to claim 1, characterized in that, The cleaning and surface treatment described in step (1) includes: ultrasonically cleaning the back of the wafer in sequence with organic solvent, acidic or alkaline cleaning solution, and deionized water, and then drying it with nitrogen gas.

3. The method according to claim 1, characterized in that, The detackable protective film mentioned in step (2) is a thermally detackable adhesive tape, and the detack treatment in step (4) includes heating at a temperature of 50℃ to 250℃ for 10 seconds to 10 minutes.

4. The method according to claim 3, characterized in that, The heating temperature is 100℃~200℃, and the heating time is 30 seconds~5 minutes.

5. The method according to claim 1, characterized in that, The de-adhesive protective film mentioned in step (2) is a UV de-adhesive tape, and the de-adhesive treatment in step (4) includes irradiation with ultraviolet light with a wavelength of 365 nm to 400 nm and an irradiation energy of 100 to 1000 mJ / cm. 2 The irradiation time is 10 seconds to 2 minutes.

6. The method according to claim 1, characterized in that, The de-adhesive protective film mentioned in step (2) is an electrolytic adhesive tape. The de-adhesive treatment in step (4) includes applying a DC voltage of 6 V to 12 V for a duration of 1 second to 60 seconds.

7. The method according to claim 1, characterized in that, The cleaning in step (5) includes immersing the wafer in an organic solvent at 60°C to 90°C and ultrasonically treating it for 1 to 15 minutes. The organic solvent is selected from one or more combinations of N-methylpyrrolidone, acetone, and isopropanol.

8. A semiconductor wafer with a temporary protective structure prepared by the method according to any one of claims 1 to 7, characterized in that, include: Cadmium zinc telluride or cadmium telluride wafer substrate; A removable protective adhesive film that completely covers the back side of the wafer substrate; as well as Pixelated metal electrode patterns formed on the front side of the wafer substrate.

9. The application of a semiconductor wafer with a temporary protective structure as described in claim 8 in the fabrication of a radiation detector or imaging sensor.

10. A removable protective film assembly specifically for the back protection method of claim 1, characterized in that, include: A flexible substrate, and an adhesive layer coated on the flexible substrate; the adhesive layer has an initial adhesion force of 2 to 10 N / cm to cadmium zinc telluride or cadmium telluride wafers in an unactivated state, and its adhesion force decreases to less than 0.2 N / cm after being activated by at least one of heat, ultraviolet light or electrical stimulation.

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