A method for nondestructive separation of an indium antimonide infrared focal plane detector photosensitive chip

Abstract

This invention relates to a non-destructive separation method for photosensitive chips of an indium antimonide infrared focal plane detector. The method comprises: S101: in-chip testing and screening of problematic dies; S102: reflow soldering; S103: epoxy adhesive dissolution; S104: ultrasonic separation; S105: photosensitive chip analysis. The specific process flow is as follows: after in-chip testing, problematic dies are screened out. First, a silicon wafer of the same size is soldered to the back of the photosensitive chip using indium metal via reflow soldering to provide mechanical support. Then, an organic solvent is used to dissolve the epoxy adhesive filling the spaces between the chips. Finally, ultrasonic vibration is used to separate the damaged photosensitive chip along with the silicon wafer from the readout circuit, thereby achieving non-destructive separation of the photosensitive chip and the readout circuit, creating conditions for failure analysis of the front side of the photosensitive chip.

Description

Technical Field

[0001] This invention relates to the field of infrared detector technology, and in particular to a non-destructive separation method for photosensitive chips of indium antimonide infrared focal plane detectors. Background Technology

[0002] Indium antimonide (InSb) infrared focal plane array detectors are important infrared detection devices operating in the mid-infrared band (3~5μm), widely used in infrared imaging, guidance, and early warning. The hybrid chip of an InSb infrared focal plane array detector consists of a photosensitive chip (InSb material) and a readout circuit chip (Si-based ROIC) electrically interconnected using a flip-chip bonding process. Specifically, each pixel unit of the photosensitive chip is connected one-to-one with the corresponding pixel unit on the readout circuit chip via indium pillars. Epoxy adhesive is then filled between the two chips to enhance mechanical strength and reliability.

[0003] After the hybridization process is completed, the photosensitive chip needs to undergo back-side thinning to reduce its thickness to 10-30 micrometers to meet the quantum efficiency and response performance requirements for infrared radiation. The thinned photosensitive chip is extremely fragile and prone to breakage.

[0004] In existing technologies, after identifying problematic chip dies during the intermediate testing phase, it is difficult to perform failure analysis on the problematic photosensitive chips because they are already firmly bonded to the readout circuit chip with epoxy adhesive and have been thinned to an extremely thin state. The main drawbacks of existing technologies include: (1) Mechanical peeling method: The photosensitive chip is peeled off from the readout circuit by mechanical force. Since the photosensitive chip has been thinned to tens of micrometers, mechanical force can easily cause the photosensitive chip to break further. Moreover, it cannot be repaired after breaking, and the front side of the photosensitive chip cannot be effectively analyzed.

[0005] (2) Chemical etching method: Using chemical reagents to directly etch epoxy glue or photosensitive chip materials makes it difficult to accurately control the etching range and depth, which can easily cause chemical damage to the photosensitive chip and affect the accuracy of subsequent analysis results.

[0006] (3) Grinding and polishing method: The photosensitive chip is removed by mechanical grinding. This method is destructive. After grinding, the photosensitive chip no longer exists and cannot be analyzed from the front.

[0007] (4) Unable to analyze the front side of the photosensitive chip: Since the front side of the photosensitive chip is connected to the readout circuit through indium pillars and epoxy resin, it is impossible to directly observe and analyze the defects on the front side of the photosensitive chip, such as the quality of the indium pillar connection and interface defects, without separation.

[0008] In summary, existing technologies cannot separate the photosensitive chip from the readout circuit for failure analysis while maintaining its integrity. There is an urgent need for a method that can non-destructively separate fragmented photosensitive chips. Summary of the Invention

[0009] The technical problem to be solved by the present invention is to provide a non-destructive separation method for the photosensitive chip of an indium antimonide infrared focal plane detector, which can completely remove the broken or problematic photosensitive chip from the readout circuit chip without further damaging the photosensitive chip, and realize failure analysis on the front side of the photosensitive chip.

[0010] To solve the above-mentioned technical problems, the technical solution of the present invention is: a non-destructive separation method for photosensitive chips of indium antimonide infrared focal plane detectors, the innovation of which is as follows: S101: Intermediate testing and screening of problematic dies: After the indium antimonide infrared focal plane detector hybrid chip completes the flip-chip interconnect and back-side thinning process, intermediate testing is performed on the chip, and problematic dies are screened out through electrical performance testing. S102: Reflow Soldering: Using the reflow soldering process, a silicon wafer of the same size as the photosensitive chip is soldered onto the back of the photosensitive chip using indium metal to provide mechanical support; S103: Epoxy Adhesive Dissolution: Dissolve the epoxy adhesive filled between the photosensitive chip and the readout circuit chip using an organic solvent reagent; S104: Ultrasonic separation: After the epoxy resin is fully dissolved, the chip is placed in an ultrasonic cleaning device, and ultrasonic vibration is applied to separate the photosensitive chip from the readout circuit chip. S105: Photosensitive Chip Analysis: After separation, the photosensitive chip, along with the silicon wafer, is completely removed from the readout circuit chip. Subsequently, the indium solder layer is etched using a 5%-10% dilute hydrochloric acid solution to separate the silicon wafer from the photosensitive chip, and then rinsed clean with deionized water. At this point, the side of the photosensitive chip that is interconnected with the readout circuit is fully exposed, and failure analysis can be performed through microscopic observation, scanning electron microscopy analysis, and energy dispersive spectroscopy analysis to determine the root cause of the chip defect.

[0011] The advantages of this invention are: (1) Non-destructive separation: This invention can completely remove a broken or problematic photosensitive chip from the readout circuit chip without further damaging the photosensitive chip, with a separation success rate of over 90%. Compared with the existing mechanical peeling method (success rate less than 30%) and grinding and polishing method (completely destructive), the separation effect is significantly improved.

[0012] (2) Achieve frontal failure analysis: The front of the separated photosensitive chip is fully exposed, and comprehensive analysis of indium pillar connection quality, interface defects, material anomalies, etc. can be carried out through microscopy, SEM, EDS, etc., providing direct basis for process improvement. Existing technology cannot achieve this analysis.

[0013] (3) Simple process and low cost: The materials used in this invention (indium solder, silicon wafer, organic solvent) are all conventional materials, and the equipment (reflow soldering equipment, ultrasonic cleaning equipment) are general equipment. No special customization is required. The cost of a single separation is low, which is suitable for laboratory and small-batch use.

[0014] (4) Wide range of applications: This method is not only applicable to indium antimonide infrared focal plane detectors, but also to the separation and analysis of hybrid chips of other types of infrared focal plane detectors such as mercury cadmium telluride (HgCdTe) and quantum well (QWIP), and has wide applicability.

[0015] (5) Improve product yield: Accurately locating the root cause of chip defects through failure analysis can provide a clear direction for process optimization, thereby effectively improving product yield and reducing production costs. Taking the indium antimonide infrared focal plane detector as an example, typical defects found through this method (such as insufficient cold soldering of indium pillars, epoxy glue filling air bubbles, etc.) can improve product yield by 5% to 10% after process improvement.

[0016] (6) Protecting expensive materials: Indium antimonide is expensive. After the photosensitive chip is separated and analyzed by this method, some of it can still be used for material recycling or teaching demonstrations, reducing material waste.

[0017] (7) Stepped ultrasound reduces the risk of breakage: A stepped power strategy is adopted in the ultrasonic separation step. The chip is first loosened with low power and then gradually pressurized to avoid the transient stress impact caused by constant high power. This reduces the risk of secondary breakage of the photosensitive chip during the separation process to less than 5%, which is significantly lower than the constant power mode (breakage risk of about 15%).

[0018] (8) Vacuum-assisted dissolution efficiency: A vacuum environment (0.05~0.1MPa) is applied during the epoxy resin dissolution process. The negative pressure promotes the solvent to penetrate into the tiny gaps between the epoxy resin and the chip interface, accelerating the swelling and dissolution process. For large-area chips (effective area greater than 50mm²), the dissolution time can be shortened by 30%~50%, significantly improving the efficiency of batch processing.

[0019] (9) Protective atmosphere to prevent surface oxidation: Nitrogen gas is introduced throughout the epoxy resin dissolution and ultrasonic separation process to prevent oxidation of the newly exposed InSb photosensitive chip surface in wet and ultrasonic environments. This measure ensures that the surface state of the separated photosensitive chip is consistent with the actual working state of the chip, so that the failure analysis results can accurately reflect the original defects rather than the secondary oxidation artifacts introduced by the separation process.

[0020] (10) Precise Defect Location Analysis: By pre-marking the coordinates of the defect area through address mapping during the mid-testing stage, the corresponding defect location on the photosensitive chip can be directly located after separation for targeted analysis, avoiding blind scanning of the entire chip. In practical applications, the location analysis efficiency is more than 3 times higher than that of traditional full-chip scanning, while reducing the machine time consumption of large instruments such as SEM. Attached Figure Description

[0021] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0022] Figure 1 This is a flowchart of a non-destructive separation method for an indium antimonide infrared focal plane detector photosensitive chip according to the present invention. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0024] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0025] like Figure 1 The method for non-destructive separation of the photosensitive chip of an indium antimonide infrared focal plane detector is shown below: S101: Intermediate chip testing and screening of problematic dies: After the indium antimonide infrared focal plane detector hybrid chip completes the flip-chip interconnect and back-side thinning process, intermediate testing is performed on the chip, and problematic dies are screened out through electrical performance testing.

[0026] In S101, defect location is pre-marked and located. During the chip screening stage, the row and column address mapping function of the readout circuit is used to record the precise coordinate position information of defective pixels in the problematic die and establish the correspondence between defect coordinates and chip physical position. Before the silicon wafer carrier is soldered, physical alignment marks are made on the edge of the silicon wafer. After separation, based on the defect coordinates and alignment marks recorded in the screening, the corresponding defect area on the photosensitive chip can be quickly located, achieving targeted analysis, avoiding blind scanning of the entire wafer, and significantly improving the efficiency of failure analysis. The criteria for judging problematic dies include: excessive blind pixel rate, abnormal signal response, and excessive noise.

[0027] S102: Reflow Soldering: Using the reflow soldering process, a silicon wafer of the same size as the photosensitive chip is soldered onto the back of the photosensitive chip using indium metal to provide mechanical support.

[0028] Specifically, an indium solder layer is pre-placed on the surface of a silicon wafer, i.e., an indium thin film with a thickness of 1-5 μm is prepared by vapor deposition or sputtering, or an indium solder pad is pre-placed. The silicon wafer is then aligned with the back of the photosensitive chip and placed in a reflow soldering machine. Under a vacuum or nitrogen protective atmosphere, it is heated to above the melting point of indium and held at that temperature for 1-3 minutes to allow the indium solder to fully wet and spread. Subsequently, it is cooled, and after the indium solder solidifies, the silicon wafer and the photosensitive chip are firmly soldered. The thickness of the silicon wafer is 300-500 micrometers, which can provide sufficient mechanical support for the fragile photosensitive chip. In this step, the silicon wafer acts as a rigid carrier, replacing the original epoxy adhesive's supporting role and preventing further breakage of the photosensitive chip during subsequent separation. The indium metal bond formed by the reflow soldering process has high strength and is resistant to solvent erosion, and can maintain a stable connection during the subsequent epoxy adhesive dissolution process.

[0029] S103: Epoxy Adhesive Dissolution: Dissolve the epoxy adhesive filling the space between the photosensitive chip and the readout circuit chip using an organic solvent. The solvent used is N-methylpyrrolidone (NMP): dichloromethane: cyclohexanone in a ratio of 2-4:2-5:1-4, which can effectively dissolve epoxy resin. Immerse the entire chip in the solvent at 40-70°C for 2-6 hours to allow the epoxy adhesive to fully swell, soften, and dissolve. The solvent only acts on the epoxy adhesive and will not damage the InSb photosensitive chip material or the silicon readout circuit.

[0030] Vacuum-assisted epoxy dissolution is employed. Specifically, the chip immersed in the solvent is placed in a vacuum environment with a vacuum level of 0.05-0.1 MPa. The negative pressure effect generated by the vacuum promotes the rapid penetration of the solvent into the tiny gaps at the interface between the epoxy and the chip, accelerating the swelling and dissolution of the epoxy. This method is particularly effective for large-area chips with an effective area greater than 50 mm², reducing the dissolution time by 30%-50%. It also improves the uniformity and thoroughness of epoxy dissolution, preventing residual epoxy from affecting subsequent separation results.

[0031] S104: Ultrasonic separation: After the epoxy resin is fully dissolved, the chip is placed in an ultrasonic cleaning device, and ultrasonic vibration is applied to separate the photosensitive chip from the readout circuit chip.

[0032] The ultrasonic frequency is 20-60kHz, the power is 50-200W, and the action time is 3-10 minutes. A stepped power strategy is adopted instead of the constant power mode: first, a low power of 30-50W is applied for 1-2 minutes to initially loosen the indium pillar interface and reduce the interface adhesion force; then, the power is gradually increased to 100-200W and the action is continued for 2-5 minutes to complete the final separation. This strategy avoids the transient stress impact generated in the constant high power initial stage, effectively preventing the photosensitive chip from secondary breakage due to stress concentration at the moment of separation. The cavitation effect generated by ultrasonic vibration produces a uniform micro-impact force at the interface between the photosensitive chip and the readout circuit, causing the two chips, which have lost their epoxy adhesive bonding, to gradually separate along the indium pillar interface. Since the silicon wafer is welded to the photosensitive chip as a whole, the photosensitive chip will not break due to vibration during the ultrasonic process, but will detach from the readout circuit along with the silicon wafer.

[0033] In steps S103 and S104, a protective atmosphere is used. Throughout the epoxy resin dissolution and ultrasonic separation process, nitrogen or argon is continuously introduced as a protective atmosphere to reduce the oxygen content in the operating environment to below 0.1%. This measure avoids oxidation of the newly exposed InSb photosensitive chip surface under high-temperature wet processing and ultrasonic cavitation, ensuring that the surface state of the separated photosensitive chip remains consistent with the actual working state of the chip, and preventing secondary oxidation artifacts introduced during the separation process from interfering with the accuracy of the failure analysis results.

[0034] S105: Photosensitive Chip Analysis: After separation, the photosensitive chip, along with the silicon wafer, is completely removed from the readout circuit chip. Subsequently, the indium solder layer is etched using a 5%-10% dilute hydrochloric acid solution to separate the silicon wafer from the photosensitive chip, and then rinsed clean with deionized water. At this point, the side of the photosensitive chip that is interconnected with the readout circuit is fully exposed, and failure analysis can be performed through microscopic observation, scanning electron microscopy analysis, and energy dispersive spectroscopy analysis to determine the root cause of the chip defect.

[0035] The working principle of this invention is as follows: The core principle lies in reinforcement followed by separation. Before separation, a reflow soldering process is used to weld the rigid silicon wafer to the fragile photosensitive chip, providing temporary mechanical support for the photosensitive chip and maintaining its structural integrity during epoxy adhesive dissolution and ultrasonic separation. The indium metal solder forms a bond with high strength and resistance to organic solvents, remaining unaffected during epoxy adhesive dissolution, ensuring the reliability of the support. Chemical reagents selectively dissolve the epoxy adhesive, eliminating adhesive forces between the two chips; ultrasonic vibration provides a uniform and gentle separation force, avoiding stress concentration caused by mechanical peeling. These two steps work synergistically to achieve non-destructive separation of the photosensitive chip.

[0036] Example 1: The 320×256 array indium antimonide infrared focal plane detector hybrid chip has a pixel center-to-center distance of 30μm. The chip has completed flip-chip interconnection and back-side thinning, and the photosensitive chip is about 20μm thick after thinning. The mid-term test results show that the chip has a dead pixel concentration phenomenon in a certain area, with a dead pixel rate exceeding 5% (the standard requirement is ≤1%), and failure analysis is required.

[0037] Experimental procedures and parameters: S101 Screening: The chip's electrical performance was tested using an infrared focal plane detector testing system at a temperature of 77K (cooled by liquid nitrogen) and an integration time of 2ms. The test results showed a large number of blind pixels and abnormal response pixels in the lower right corner area of ​​the chip (approximately 64×64 pixels), indicating that it was a problematic chip.

[0038] S102 Reflow Soldering: A double-sided polished silicon wafer with a thickness of 500μm and a size of 8mm×8mm (consistent with the size of the photosensitive chip) is selected. A 3μm thick indium film is pre-deposited on the surface of the silicon wafer as a solder layer. After aligning the silicon wafer with the back of the photosensitive chip and bonding it, it is placed in a vacuum reflow oven and heated to 170°C at a heating rate of 5°C / min under nitrogen protection. It is held at this temperature for 2 minutes to allow the indium solder to fully wet and spread. Then, it is cooled to room temperature at a rate of 3°C / min. After the indium solder solidifies, the silicon wafer and the photosensitive chip are firmly soldered together.

[0039] S103 Epoxy Resin Dissolution: The entire chip was immersed in a mixed solvent with a ratio of NMP:dichloromethane:cyclohexanone = 3:3:2. The solution was heated to 60°C and soaked for 4 hours. During the soaking process, the epoxy resin was observed to gradually swell and soften, eventually dissolving in the mixed solvent. After removal, it was rinsed with deionized water.

[0040] S104 Ultrasonic Separation: The chip was placed in an ultrasonic cleaner with deionized water as the medium. The ultrasonic frequency was 40kHz, the power was 100W, and the treatment time was 5 minutes. During the ultrasonic process, the photosensitive chip (along with the silicon wafer) detached completely from the readout circuit chip without further breakage.

[0041] S105 Desoldering and Analysis: The separated photosensitive chip (along with the silicon wafer) was immersed in a dilute hydrochloric acid solution (8% concentration) for 10 minutes at room temperature to dissolve the indium solder layer and separate the silicon wafer from the photosensitive chip. The photosensitive chip was then cleaned sequentially with deionized water and anhydrous ethanol.

[0042] Analysis Results: The separated photosensitive chip was placed face up and observed using an optical microscope and a scanning electron microscope (SEM). In the lower right corner, where blind cells were concentrated, some indium pillars showed insufficient cold soldering, inconsistent pillar heights, and some pillars failed to form an effective electrical connection with the readout circuit. Energy dispersive spectroscopy (EDS) analysis showed a high oxygen content at the indium pillar interface in this area, indicating oxidation problems during the interconnection process.

[0043] Comparison data: (1) Existing technology (mechanical peeling method): Separate 3 chips, 2 chips are further broken, and part of the remaining chip can be used for analysis, with a success rate of about 33%. The indium pillars on the front side of the separated chips are severely deformed, making it impossible to determine the original defect state.

[0044] (2) Method of the present invention: Separate 3 chips, all 3 chips are completely separated, with a success rate of 100%. The morphology of the indium pillars on the front side of the separated chips is intact, and the insufficient cold soldering and oxidation defects can be clearly identified.

[0045] Verification of optimization measures: Based on the above basic experiments, the four optimization measures were compared and verified.

[0046] (1) Stepped ultrasound verification: Three chips were separated using stepped power (40W, 280W, 250W, 2 minutes each). All chips were separated intact without secondary breakage, achieving a 100% success rate. In contrast, when separating three chips using constant power (100W, 5 minutes), one chip developed a microcrack at its edge, resulting in a success rate of approximately 67%. The stepped strategy reduced the breakage risk from 33% to 0%.

[0047] (2) Vacuum-assisted dissolution verification: Compared with atmospheric pressure immersion (60°C, mixed solvent) and vacuum-assisted immersion (60°C, mixed solvent, vacuum degree 0.08MPa), it takes 4 hours for epoxy resin to completely dissolve under atmospheric pressure; it only takes 2.5 hours under vacuum-assisted conditions, which shortens the dissolution time by about 37%, and the dissolution is more uniform and thorough, with no epoxy resin residue.

[0048] (3) Verification of protective atmosphere: Separation was carried out in air environment and nitrogen protection environment (oxygen content <0.1%) respectively, and EDS energy dispersive spectroscopy analysis was performed on the front side of the separated photosensitive chip. The oxygen content on the surface of the chip separated in air environment was 12.3 at%, which was significantly higher than 3.1 at% under nitrogen protection (close to 2.8 at% of the original unseparated chip), proving that the protective atmosphere effectively prevented secondary oxidation of InSb surface.

[0049] (4) Defect pre-marking and localization verification: Using the blind element coordinates (lower right corner 64\u00d764 area) recorded by the measurement system, alignment marks were made on the silicon wafer carrier. After separation, the defect area was directly located according to the marks for SEM analysis. It only took about 1 hour from separation to obtaining the analysis results; compared with the whole-wafer scanning method without marks, it took about 4 hours. The localization analysis efficiency was improved by about 4 times, and the invalid scanning of normal areas was avoided.

[0050] Conclusion: The method of this invention successfully achieved non-destructive separation of the hybrid chip of the indium antimonide infrared focal plane detector. The front side of the separated photosensitive chip remained intact, and the failure analysis results were accurate and reliable, providing a clear basis for subsequent process optimization (improving the indium pillar interconnect process and optimizing the interconnect environment atmosphere control). Those skilled in the art should understand that this invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made without departing from the spirit and scope of the invention, and all such changes and modifications fall within the scope of the invention as claimed.

Claims

1. A method for non-destructive separation of the photosensitive chip of an indium antimonide infrared focal plane detector, characterized in that: The specific method is as follows: S101: Intermediate testing and screening of problematic dies: After the indium antimonide infrared focal plane detector hybrid chip completes the flip-chip interconnect and back-side thinning process, intermediate testing is performed on the chip, and problematic dies are screened out through electrical performance testing. S102: Reflow Soldering: Using the reflow soldering process, a silicon wafer of the same size as the photosensitive chip is soldered onto the back of the photosensitive chip using indium metal to provide mechanical support; S103: Epoxy Adhesive Dissolution: Dissolve the epoxy adhesive filled between the photosensitive chip and the readout circuit chip using an organic solvent reagent; S104: Ultrasonic separation: After the epoxy resin is fully dissolved, the chip is placed in an ultrasonic cleaning device, and ultrasonic vibration is applied to separate the photosensitive chip from the readout circuit chip. S105: Photosensitive Chip Analysis: After separation, the photosensitive chip, along with the silicon wafer, is completely removed from the readout circuit chip. Subsequently, the indium solder layer is etched using a 5%-10% dilute hydrochloric acid solution to separate the silicon wafer from the photosensitive chip, and then rinsed clean with deionized water. At this point, the side of the photosensitive chip that is interconnected with the readout circuit is fully exposed, and failure analysis can be performed through microscopic observation, scanning electron microscopy analysis, and energy dispersive spectroscopy analysis to determine the root cause of the chip defect.

2. The method for non-destructive separation of the photosensitive chip of an indium antimonide infrared focal plane detector according to claim 1, characterized in that: In step S101, defect location is pre-marked and located. During the chip screening stage, the row and column address mapping function of the readout circuit is used to record the precise coordinate position information of defective pixels in the problematic die and establish the correspondence between defect coordinates and chip physical position. Before the silicon wafer carrier is soldered, physical alignment marks are made on the edge of the silicon wafer. After separation, based on the defect coordinates and alignment marks recorded in the screening, the corresponding defect area on the photosensitive chip can be quickly located, achieving targeted analysis, avoiding blind scanning of the entire wafer, and significantly improving the efficiency of failure analysis. The criteria for identifying problematic chips include: excessive blind pixel rate, abnormal signal response, and excessive noise.

3. The method for non-destructive separation of the photosensitive chip of an indium antimonide infrared focal plane detector according to claim 1, characterized in that: S102 specifically involves: pre-depositing an indium solder layer on the surface of a silicon wafer, i.e., preparing an indium thin film with a thickness of 1-5 μm by vapor deposition or sputtering, or pre-depositing an indium solder pad; aligning the silicon wafer with the back of the photosensitive chip and bonding it to the substrate; placing it in a reflow soldering machine; heating it to above the melting point of indium under a vacuum or nitrogen protective atmosphere; holding it at this temperature for 1-3 minutes to allow the indium solder to fully wet and spread; then cooling it down; after the indium solder solidifies, firmly welding the silicon wafer to the photosensitive chip; the thickness of the silicon wafer is 300-500 micrometers, which can provide sufficient mechanical support for the fragile photosensitive chip; in this step, the silicon wafer acts as a rigid carrier, replacing the original epoxy adhesive's supporting role, preventing further breakage of the photosensitive chip during subsequent separation; the indium metal bond formed by the reflow soldering process has high strength and is resistant to solvent erosion, maintaining a stable connection during the subsequent epoxy adhesive dissolution process.

4. The method for non-destructive separation of the photosensitive chip of an indium antimonide infrared focal plane detector according to claim 1, characterized in that: The reagent used in S103 is N-methylpyrrolidone (NMP): dichloromethane: cyclohexanone in a ratio of 2-4: 2-5: 1-4, which can effectively dissolve epoxy resin. The entire chip is immersed in the reagent and soaked at 40-70°C for 2-6 hours to allow the epoxy resin to fully swell, soften and dissolve. The reagent only acts on the epoxy resin and will not damage the InSb photosensitive chip material or the silicon readout circuit.

5. The method for non-destructive separation of the photosensitive chip of an indium antimonide infrared focal plane detector according to claim 1, characterized in that: In step S103, vacuum-assisted epoxy resin dissolution is employed. Specifically, the chip immersed in the solvent is placed in a vacuum environment with a vacuum degree of 0.05-0.1 MPa. The negative pressure effect generated by the vacuum promotes the rapid penetration of the solvent into the tiny gaps at the interface between the epoxy resin and the chip, accelerating the swelling and dissolution of the epoxy resin. This measure is particularly effective for large-area chips with an effective area greater than 50 mm², reducing the dissolution time by 30%-50%. It also improves the uniformity and thoroughness of epoxy resin dissolution, preventing residual epoxy resin from affecting subsequent separation results.

6. The method for non-destructive separation of the photosensitive chip of an indium antimonide infrared focal plane detector according to claim 1, characterized in that: In S104, the ultrasonic frequency is 20-60kHz, the power is 50-200W, and the action time is 3-10 minutes. The cavitation effect generated by the ultrasonic vibration produces a uniform micro-impact force at the interface between the photosensitive chip and the readout circuit, causing the two chips, which have lost their epoxy adhesive bonding, to gradually separate along the indium pillar interface. Since the silicon wafer has been welded to the photosensitive chip as a whole, the photosensitive chip will not break due to vibration during the ultrasonic process, but will fall off the readout circuit together with the silicon wafer.

7. The non-destructive separation method for the photosensitive chip of an indium antimonide infrared focal plane detector according to claim 6, characterized in that: The ultrasonic frequency is 20-60kHz, the power is 50-200W, and the action time is 3-10 minutes. Specifically, a stepped ultrasonic power control is adopted. In the ultrasonic separation step, a stepped power strategy is used instead of the constant power mode: first, a low power of 30-50W is applied for 1-2 minutes to initially loosen the indium pillar interface and reduce the interface adhesion force; then, the power is gradually increased to 100-200W and the action continues for 2-5 minutes to complete the final separation. This strategy avoids the transient stress impact generated in the constant high power initial stage and effectively prevents the photosensitive chip from secondary breakage due to stress concentration at the moment of separation.

8. The method for non-destructive separation of the photosensitive chip of an indium antimonide infrared focal plane detector according to claim 1, characterized in that: In steps S103 and S104, a protective atmosphere is used. Throughout the epoxy resin dissolution and ultrasonic separation process, nitrogen or argon is continuously introduced as a protective atmosphere to reduce the oxygen content in the operating environment to below 0.1%. This measure avoids oxidation of the newly exposed InSb photosensitive chip surface under high-temperature wet processing and ultrasonic cavitation, ensuring that the surface state of the separated photosensitive chip remains consistent with the actual working state of the chip, and preventing secondary oxidation artifacts introduced during the separation process from interfering with the accuracy of the failure analysis results.

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