HgCdTe minority carrier lifetime test processing method

Abstract

The invention discloses a tellurium-cadmium-mercury minority carrier lifetime test processing method, and relates to the technical field of chip testing, and the method specifically comprises the following steps: S1, pretreatment: carrying out first cleaning to remove impurities and smudginess existing on the surface of a to-be-tested chip, the material of the chip to be tested takes tellurium-zinc-cadmium as a substrate, and a layer of tellurium-cadmium-mercury film is formed on the substrate through liquid-phase vertical epitaxy. According to the tellurium-cadmium-mercury minority carrier lifetime test processing method provided by the invention, the to-be-tested chip is processed through cleaning, chemical polishing, passivation and other processes, so that the film thickness of the tellurium-cadmium-mercury film on the to-be-tested chip is 9 [mu] m, the tellurium-cadmium-mercury minority carrier lifetime on the chip is detected, and the minority carrier lifetime detection accuracy is improved.

Description

Technical Field

[0001] The invention relates to the technical field of chip testing, and in particular to a mercury cadmium telluride minority carrier lifetime testing processing method. Background Art

[0002] In p-type semiconductors, the concentration of electrons is less than that of holes, and electrons are called minority carriers. In n-type semiconductors, holes are minority carriers. The minority carrier lifetime is an important parameter of semiconductor materials and a basic parameter for evaluating the quality of semiconductor materials.

[0003] In the invention patent application with publication number: CN116641128A, publication date: 2023-08-25, and titled "Minority Carrier Lifetime Determination Method, Crystal Pulling Method, and Silicon Wafer for Solar Cells", the present invention discloses a minority carrier lifetime determination method, a crystal pulling method, and a silicon wafer for solar cells, which relates to the field of crystal growth technology, to provide a technical solution for improving the efficiency of silicon wafers on the same furnace by determining the minority carrier data of silicon rods pre-pulled on the same furnace. The minority carrier lifetime determination method includes: obtaining a minority carrier lifetime curve of a silicon wafer sample; establishing a minority carrier lifetime calculation model based on the minority carrier lifetime curve of the silicon wafer sample and a minority carrier lifetime simulation model; wherein the silicon wafer sample and the pre-pulled silicon rod are prepared by the same furnace; based on the minority carrier lifetime calculation model, determining the minority carrier lifetime data at different positions of the pre-pulled silicon rod.

[0004] At present, minority carrier lifetime testers are mostly used to test the minority carrier lifetime of silicon wafers. The minority carrier lifetime test methods and standards for HgCdTe materials have not yet been clarified, resulting in the inability to conduct corresponding quality control evaluations during the production process. However, different test methods may have certain requirements for the shape, size, and surface quality of the sample. This may limit the testing of certain specific types or special samples. Although the equipment is easy to operate, it is still difficult to fully utilize its functions and obtain accurate test results for specific samples. Summary of the invention

[0005] The object of the present invention is to provide a method for testing the HgCdTe minority carrier lifetime to solve the above-mentioned deficiencies in the prior art.

[0006] In order to achieve the above object, the present invention provides the following technical solutions:

[0007] A method for testing the lifetime of HgCdTe minority carriers, the method specifically comprising the following steps:

[0008] S1: Pretreatment: The first cleaning is to remove impurities and dirt on the surface of the chip to be tested, wherein the material of the chip to be tested is a layer of mercury cadmium telluride film grown on cadmium zinc telluride by liquid phase vertical epitaxy with cadmium zinc telluride as the substrate;

[0009] The first cleaning step in step S1 specifically includes the following sub-steps:

[0010] S11: at 80° C., soak the chip in a 99.9% trichloroethylene solution for 30 minutes; then soak it in a 50%-90% N-methylpyrrolidone solution for 5-10 minutes; and finally soak it in a 99.9% trichloroethylene solution for 3-5 minutes, wherein the concentration of N-methylpyrrolidone is preferably 90%;

[0011] S12: Rinse: rinse twice with 99.0% anhydrous ethanol, each time for 3-5 minutes;

[0012] S13: After cleaning, take out the chip, blow dry it and inspect it under a microscope.

[0013] S2: removing the oxide layer, which includes S21 etching step and S22 polishing step;

[0014] The S21 corrosion step includes the following sub-steps:

[0015] S211: The chip is immersed in deionized water for 5 minutes;

[0016] S212: placing the chip on a flower basket, and then placing the flower basket in a mixture of 99.9% methanol and 0.1-0.3% bromine water for etching, rotating the flower basket once per second during the etching process, rotating it in the opposite direction after 5 seconds in the same way, and removing the flower basket after etching for 10 seconds to stop etching; wherein, the volume ratio of the mixture of 99.9% methanol and 0.1-0.3% bromine water is 250:1, and the concentration of bromine water is preferably 0.2%;

[0017] S213: immediately placing the etched chip in a 99.9% methanol solution, rotating the chip clockwise and counterclockwise for one circle, and then cleaning the front and back sides of the chip respectively, and then placing the chip in a 99.9% methanol solution for three times for cleaning;

[0018] S214: After cleaning, take out the chip, blow dry it and inspect it under a microscope.

[0019] S22 polishing step, specifically includes the following sub-steps:

[0020] S221: Calculate the polishing time t for each piece according to the film thickness of the incoming piece, t=(THK-9.0) / 5.5*60s, and subtract 5-10s from the polishing time of the first piece of each batch; wherein the film thickness of the epitaxial HgCdTe film on CdZnTe is preferably 9μm.

[0021] S222: Prepare chemical polishing liquid: 0.2% bromine methanol solution. The mixed liquid includes bromine water, 99.9% methanol and 99.0% ethylene glycol. The volume ratio of each component is 1:125:375. Before chemical polishing, rinse the chemical polishing pad with 99.9% methanol for 10 minutes, and then rinse with 99.5% dichlorofluoroethane for 5 minutes.

[0022] S223: transferring the chip to the fixture groove soaked with 99.9% methanol, soaking the chip surface with 99.9% methanol again, using 0.2% bromine methanol solution as the polishing liquid, with a dripping speed of 20 ml / min and a polishing speed of 40 r / min to start the polishing, so that the film thickness of the epitaxial mercury cadmium telluride film on the cadmium zinc telluride chip is 9 μm;

[0023] S224: After the chemical polishing is completed, the residual mixed solution on the surface of the chip is immediately rinsed off with 99.9% methanol, and then rinsed in 99.9% methanol for 6-8 times;

[0024] S225: Spray wash with 99.00% anhydrous ethanol for 1-2 minutes, then blow dry with nitrogen for microscopic examination.

[0025] S3: passivation, forming a CdTe and ZnS composite passivation layer on the surface of the test chip;

[0026] It includes the following sub-steps:

[0027] S31 Preparation steps: Debug the coating equipment, the parameters are: vacuum degree: 5E-6bar; ignition pressure: CdTe-40mTorr, ZnS-40mTorr; Bais power: ZnS-50W, and the model of the coating equipment is Weikai, HY019E.

[0028] S32 sputtering steps: film layer: CdTe and ZnS composite passivation layer; film thickness: the thickness of CdTe and ZnS are

[0029] Temperature: CdTe-70℃, ZnS-50℃; Power: CdTe-200W, ZnS-400W; Ar flow: CdTe-57sccm, ZnS-47sccm; Duration: CdTe-2700s, ZnS-1994s; Auxiliary deposition of ZnS-120s.

[0030] S4: Test the minority carrier lifetime; evenly apply silicone grease on the back of the chip and put it into the minority carrier lifetime tester and then evacuate the vacuum. Set the parameters of the minority carrier lifetime tester to a scanning resolution of 0.5 mm, a microwave frequency of 10 Hz-10.5 GHz, and a wavelength of 904 nm, and test the minority carrier lifetime of the chip.

[0031] S5: Remove the silicone grease and wipe the silicone grease on the back of the chip with 99.0% anhydrous ethanol;

[0032] S6: removing the passivation layer, which includes the following sub-steps;

[0033] S61: Fix the chip to be corroded on the cleaning machine for cleaning. After cleaning, rinse it quickly with acetone, then soak it in anhydrous ethanol twice, each time for 5 minutes, and finally rinse it with deionized water for 10 minutes;

[0034] S62: placing the cleaned chip into a 37% hydrochloric acid solution, rotating the flower basket once per second during the etching process, and rotating in the opposite direction in the same way after 5 seconds; taking out the flower basket after etching for 45 seconds to stop etching;

[0035] S63: Immediately put the chip after etching into deionized water for cleaning 4 times, one circle clockwise and one circle counterclockwise respectively, and then wash the front and back sides of the chip with deionized water four times in sequence; then rinse with deionized water for 10 minutes, and finally rinse with anhydrous ethanol twice in sequence;

[0036] S64: After cleaning, take out the chip, blow dry it and inspect it under a microscope.

[0037] S7: Second cleaning, which includes the following sub-steps;

[0038] S71: At 80°C: soak the chip in a 99.9% trichloroethylene solution for 30 minutes; then soak it in a 50%-90% N-methylpyrrolidone solution for 5-10 minutes; and finally soak it in a 99.9% trichloroethylene solution for 3-5 minutes, wherein the concentration of N-methylpyrrolidone is preferably 90%;

[0039] S72: Rinse: rinse twice with 99.0% anhydrous ethanol, each time for 3-5 minutes;

[0040] S73: After cleaning, take out the chip, blow dry it and inspect it under a microscope.

[0041] S8: Tape out.

[0042] In the above technical scheme, the present invention provides a method for testing the mercury cadmium telluride minority carrier lifetime, which processes the chip to be tested through processes such as cleaning, polishing and passivation, so that the thickness of the mercury cadmium telluride film on the chip to be tested is 9μm, thereby realizing the detection and processing of the mercury cadmium telluride minority carrier lifetime on the chip, thereby improving the accuracy of minority carrier lifetime detection.

[0043] It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the disclosure.

[0044] This application document provides an overview of various implementations or examples of the technology described in the present disclosure, and is not a comprehensive disclosure of the entire scope or all features of the disclosed technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For ordinary technicians in this field, other drawings can also be obtained based on these drawings.

[0046] Figure 1-2 An annotated schematic diagram of the minority carrier lifetime test principle provided by an embodiment of the present invention;

[0047] Figure 3 A schematic diagram of a structure in which the accuracy of minority carrier lifetime test provided by an embodiment of the present invention is 98%;

[0048] Figure 4 A schematic diagram of a structure in which the accuracy of minority carrier lifetime test provided by an embodiment of the present invention is 93-94%;

[0049] Figure 5 A schematic diagram of a structure in which the accuracy of minority carrier lifetime testing provided by an embodiment of the present invention is 87%. DETAILED DESCRIPTION

[0050] In order to make the purpose, technical solution and advantages of the embodiments of the present disclosure clearer, the technical solution of the embodiments of the present disclosure will be clearly and completely described below in conjunction with the drawings of the embodiments of the present disclosure. Obviously, the described embodiments are part of the embodiments of the present disclosure, not all of the embodiments. Based on the described embodiments of the present disclosure, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present disclosure.

[0051] Embodiment 1:

[0052] A method for testing the minority carrier lifetime of mercury cadmium telluride, the method specifically comprising the following steps:

[0053] S1: Pretreatment: The first cleaning is to remove impurities and dirt on the surface of the chip to be tested, wherein the material of the chip to be tested is a layer of mercury cadmium telluride film grown on cadmium zinc telluride by liquid phase vertical epitaxy with cadmium zinc telluride as the substrate;

[0054] The first cleaning step in step S1 specifically includes the following sub-steps:

[0055] S11: At 80°C, soak the chip in a 99.9% trichloroethylene solution for 30 minutes; then soak it in 80% N-methylpyrrolidone for 10 minutes; and finally soak it in 99.9% trichloroethylene for 3 minutes;

[0056] S12: Rinse: rinse twice with 99.0% anhydrous ethanol, each time for 3-5 minutes;

[0057] S13: After cleaning, take out the chip, blow dry it and inspect it under a microscope.

[0058] S2: removing the oxide layer, which includes S21 etching step and S22 polishing step;

[0059] The S21 corrosion step includes the following sub-steps:

[0060] S211: The chip is immersed in deionized water for 5 minutes;

[0061] S212: placing the chip on the flower basket, and then placing the flower basket in a mixture of 250 ml of 99.9% methanol and 1 ml of 0.1% bromine water for etching. During the etching process, the flower basket is rotated once per second. After 5 seconds, it is rotated in the opposite direction in the same way. After etching for 10 seconds, the flower basket is removed and the etching is stopped.

[0062] S213: immediately placing the etched chip in a 99.9% methanol solution, rotating the chip clockwise and counterclockwise for one circle, and then cleaning the front and back sides of the chip respectively, and then placing the chip in a 99.9% methanol solution for three times for cleaning;

[0063] S214: After cleaning, take out the chip, blow dry it and inspect it under a microscope.

[0064] S22 polishing step, specifically includes the following sub-steps:

[0065] S221: Calculate the polishing time t for each piece according to the film thickness of the incoming piece, t = (THK-9.0) / 5.5*60s, and subtract 5-10s from the polishing time of the first piece of each batch;

[0066] S222: Prepare chemical polishing liquid: 0.2% bromine methanol solution, the mixed liquid includes 0.2% bromine water, 99.9% methanol and 99.0% ethylene glycol, the volume ratio of each component is 1:125:375, for example, 0.8ml of 0.2% bromine water, 300ml of 99.9% methanol and 100ml of 99.0% ethylene glycol are mixed thoroughly, and before chemical polishing, the chemical polishing pad is rinsed with 99.9% methanol for 10 minutes, and then rinsed with 99.5% dichlorofluoroethane for 5 minutes;

[0067] S223: transferring the chip to the fixture groove soaked with 99.9% methanol, soaking the chip surface with 99.9% methanol again, using 0.2% bromine methanol solution as the polishing liquid, with a dripping speed of 20 ml / min and a polishing speed of 40 r / min to start the polishing, so that the film thickness of the epitaxial mercury cadmium telluride film on the cadmium zinc telluride chip is 9 μm;

[0068] S224: After the chemical polishing is completed, the residual mixed solution on the surface of the chip is immediately rinsed off with 99.9% methanol, and then rinsed in 99.9% methanol for 6 times;

[0069] S225: Spray wash with 99.00% anhydrous ethanol for 1 min, then blow dry with nitrogen for microscopic examination.

[0070] S3: passivation, forming a CdTe and ZnS composite passivation layer on the surface of the test chip;

[0071] It includes the following sub-steps:

[0072] S31 preparation steps: debug the coating equipment, the parameters are: vacuum degree: 5E-6bar; ignition pressure: CdTe-40mTorr, ZnS-40mTorr; Bais power: ZnS-50W, the model of the coating equipment is Weikai, HY019E;

[0073] S32 sputtering steps: film layer: CdTe and ZnS composite passivation layer; film thickness: the thickness of CdTe and ZnS are

[0074] Temperature: CdTe-70℃, ZnS-50℃; Power: CdTe-200W, ZnS-400W; Ar flow: CdTe-57sccm, ZnS-47sccm; Duration: CdTe-2700s, ZnS-1994s; Auxiliary deposition of ZnS-120s.

[0075] S4: Test the minority carrier lifetime; evenly apply silicone grease on the back of the chip and put it into the minority carrier lifetime tester and then evacuate the vacuum. Set the parameters of the minority carrier lifetime tester to a scanning resolution of 0.5 mm, a microwave frequency of 10 Hz, and a wavelength of 904 nm, and test the minority carrier lifetime of the chip.

[0076] S5: Remove the silicone grease and wipe the silicone grease on the back of the chip with 99.0% anhydrous ethanol.

[0077] S6: removing the passivation layer, which includes the following sub-steps;

[0078] S61: Fix the chip to be corroded on the cleaning machine for cleaning. After cleaning, rinse it quickly with acetone, then soak it in anhydrous ethanol twice, each time for 5 minutes, and finally rinse it with deionized water for 10 minutes;

[0079] S62: placing the cleaned chip into a 37% hydrochloric acid solution, rotating the flower basket once per second during the etching process, and rotating in the opposite direction in the same way after 5 seconds; taking out the flower basket after etching for 45 seconds to stop etching;

[0080] S63: Immediately put the chip after etching into deionized water for cleaning 4 times, one circle clockwise and one circle counterclockwise respectively, and then wash the front and back sides of the chip with deionized water four times in sequence; then rinse with deionized water for 10 minutes, and finally rinse with anhydrous ethanol twice in sequence;

[0081] S64: After cleaning, take out the chip, blow dry it and inspect it under a microscope.

[0082] S7: Second cleaning, which includes the following sub-steps;

[0083] S71: At 80°C, soak the chip in 99.9% trichloroethylene solution for 30 minutes; then soak it in 80% N-methylpyrrolidone for 10 minutes; and finally soak it in 99.9% trichloroethylene for 3 minutes;

[0084] S72: Rinse: rinse twice with 99.0% anhydrous ethanol, 3 minutes each time;

[0085] S73: After cleaning, take out the chip, blow dry it and inspect it under a microscope.

[0086] S8: Tape out.

[0087] Embodiment 2:

[0088] A method for testing the lifetime of HgCdTe minority carriers, the method specifically comprising the following steps:

[0089] S1: Pretreatment: The first cleaning is to remove impurities and dirt on the surface of the chip to be tested, wherein the material of the chip to be tested is a layer of mercury cadmium telluride film grown on cadmium zinc telluride by liquid phase vertical epitaxy with cadmium zinc telluride as the substrate;

[0090] The first cleaning step in step S1 specifically includes the following sub-steps:

[0091] S11: At 80°C, soak the chip in a 99.9% trichloroethylene solution for 30 minutes; then soak it in 85% N-methylpyrrolidone for 7 minutes; and finally soak it in 99.9% trichloroethylene for 4 minutes;

[0092] S12: Rinse: rinse twice with 99.0% anhydrous ethanol, each time for 3-5 minutes;

[0093] S13: After cleaning, take out the chip, blow dry it and inspect it under a microscope.

[0094] S2: removing the oxide layer, which includes S21 etching step and S22 polishing step;

[0095] The S21 corrosion step includes the following sub-steps:

[0096] S211: The chip is immersed in deionized water for 5 minutes;

[0097] S212: placing the chip on the flower basket, and then placing the flower basket in a mixture of 250 ml of 99.9% methanol and 1 ml of 0.15% bromine water for etching. During the etching process, the flower basket is rotated once per second. After 5 seconds, it is rotated in the opposite direction in the same way. After etching for 10 seconds, the flower basket is taken out and the etching is stopped.

[0098] S213: immediately placing the etched chip in a 99.9% methanol solution, rotating the chip clockwise and counterclockwise for one circle, and then cleaning the front and back sides of the chip respectively, and then placing the chip in a 99.9% methanol solution for three times for cleaning;

[0099] S214: After cleaning, take out the chip, blow dry it and inspect it under a microscope.

[0100] S22 polishing step, specifically includes the following sub-steps:

[0101] S221: Calculate the polishing time t of each piece according to the film thickness of the incoming piece, t = (THK-9.0) / 5.5*60s, and subtract 5-10s from the polishing time of the first piece of each batch; the film thickness of the epitaxial HgCdTe film on CdZnTe is 9μm;

[0102] S222: Preparation of chemical polishing liquid: Preparation of chemical polishing liquid: 0.2% bromine methanol solution, the mixed liquid includes 0.2% bromine water, 99.9% methanol and 99.0% ethylene glycol, the volume ratio of each component is 1:125:375, for example, 0.8ml of 0.2% bromine water, 300ml of 99.9% methanol and 100ml of 99.0% ethylene glycol are mixed thoroughly, and the chemical polishing pad is rinsed with 99.9% methanol for 10 minutes before the start of chemical polishing, and then rinsed with 99.5% dichlorofluoroethane for 5 minutes;

[0103] S223: transferring the chip to the fixture groove soaked with 99.9% methanol, soaking the chip surface with 99.9% methanol again, using 0.2% bromine methanol solution as the polishing liquid, with a dripping speed of 20 ml / min and a polishing speed of 40 r / min to start the polishing, so that the film thickness of the epitaxial mercury cadmium telluride film on the cadmium zinc telluride chip is 9 μm;

[0104] S224: After the chemical polishing is completed, the residual mixed solution on the surface of the chip is immediately rinsed off with 99.9% methanol, and then rinsed in 99.9% methanol for 7 times;

[0105] S225: Spray wash with 99.00% anhydrous ethanol for 1.5 min, then blow dry with nitrogen for microscopic examination.

[0106] S3: passivation, forming a CdTe and ZnS composite passivation layer on the surface of the test chip;

[0107] It includes the following sub-steps:

[0108] S31 preparation steps: debug the coating equipment, the parameters are: vacuum degree: 5E-6bar; ignition pressure: CdTe-40mTorr, ZnS-40mTorr; Bais power: ZnS-50W, the model of the coating equipment is Weikai, HY019E;

[0109] S32 sputtering steps: film layer: CdTe and ZnS composite passivation layer; film thickness: the thickness of CdTe and ZnS are

[0110] Temperature: CdTe-70℃, ZnS-50℃; Power: CdTe-200W, ZnS-400W; Ar flow: CdTe-57sccm, ZnS-47sccm; Duration: CdTe-2700s, ZnS-1994s; Auxiliary deposition of ZnS-120s.

[0111] S4: Test the minority carrier lifetime; evenly apply silicone grease on the back of the chip and put it into the minority carrier lifetime tester and then evacuate the vacuum. Set the parameters of the minority carrier lifetime tester to a scanning resolution of 0.5 mm, a microwave frequency of 10.3 GHz, and a wavelength of 904 nm, and test the minority carrier lifetime of the chip.

[0112] S5: Remove the silicone grease and wipe the silicone grease on the back of the chip with 99.0% anhydrous ethanol.

[0113] S6: removing the passivation layer, which includes the following sub-steps;

[0114] S61: Fix the chip to be corroded on the cleaning machine for cleaning. After cleaning, rinse it quickly with acetone, then soak it in anhydrous ethanol twice, each time for 5 minutes, and finally rinse it with deionized water for 10 minutes;

[0115] S62: placing the cleaned chip into a 37% hydrochloric acid solution, rotating the flower basket once per second during the etching process, and rotating in the opposite direction in the same way after 5 seconds; taking out the flower basket after etching for 45 seconds to stop etching;

[0116] S63: Immediately put the chip after etching into deionized water for cleaning 4 times, one circle clockwise and one circle counterclockwise respectively, and then wash the front and back sides of the chip with deionized water four times in sequence; then rinse with deionized water for 10 minutes, and finally rinse with anhydrous ethanol twice in sequence;

[0117] S64: After cleaning, take out the chip, blow dry it and inspect it under a microscope.

[0118] S7: Second cleaning, which includes the following sub-steps;

[0119] S71: At 80°C, soak the chip in 99.9% trichloroethylene solution for 30 minutes; then soak it in 85% N-methylpyrrolidone for 7 minutes; and finally soak it in 99.9% trichloroethylene for 4 minutes;

[0120] S72: Rinse: rinse twice with 99.0% anhydrous ethanol, 4 minutes each time;

[0121] S73: After cleaning, take out the chip, blow dry it and inspect it under a microscope.

[0122] S8: Tape out.

[0123] Embodiment three:

[0124] A method for testing the minority carrier lifetime of mercury cadmium telluride, the method specifically comprising the following steps:

[0125] S1: Pretreatment: The first cleaning is to remove impurities and dirt on the surface of the chip to be tested, wherein the material of the chip to be tested is a layer of mercury cadmium telluride film grown on cadmium zinc telluride by liquid phase vertical epitaxy with cadmium zinc telluride as the substrate;

[0126] The first cleaning step in step S1 specifically includes the following sub-steps:

[0127] S11: At 80°C, soak the chip in a 99.9% trichloroethylene solution for 30 minutes; then soak it in 90% N-methylpyrrolidone for 5 minutes; and finally soak it in 99.9% trichloroethylene for 5 minutes;

[0128] S12: Rinse: rinse twice with 99.0% anhydrous ethanol, each time for 3-5 minutes;

[0129] S13: After cleaning, take out the chip, blow dry it and inspect it under a microscope.

[0130] S2: removing the oxide layer, which includes S21 etching step and S22 polishing step;

[0131] The S21 corrosion step includes the following sub-steps:

[0132] S211: The chip is immersed in deionized water for 5 minutes;

[0133] S212: placing the chip on the flower basket, and then placing the flower basket in a mixture of 250 ml of 99.9% methanol and 1 ml of 0.2% bromine water for etching. During the etching process, the flower basket is rotated once per second. After 5 seconds, it is rotated in the opposite direction in the same way. After etching for 10 seconds, the flower basket is taken out and the etching is stopped.

[0134] S213: immediately placing the etched chip in a 99.9% methanol solution, rotating the chip clockwise and counterclockwise for one circle, and then cleaning the front and back sides of the chip respectively, and then placing the chip in a 99.9% methanol solution for three times for cleaning;

[0135] S214: After cleaning, take out the chip, blow dry it and inspect it under a microscope.

[0136] S22 polishing step, specifically includes the following sub-steps:

[0137] S221: Calculate the polishing time t for each piece according to the film thickness of the incoming piece, t = (THK-9.0) / 5.5*60s, and subtract 5-10s from the polishing time of the first piece of each batch;

[0138] S222: Prepare chemical polishing liquid: 0.2% bromine methanol solution, the mixed liquid includes 0.2% bromine water, 99.9% methanol and 99.0% ethylene glycol, the volume ratio of each component is 1:125:375, for example, 0.8ml of 0.2% bromine water, 300ml of 99.9% methanol and 100ml of 99.0% ethylene glycol are mixed thoroughly, and before chemical polishing, the chemical polishing pad is rinsed with 99.9% methanol for 10 minutes, and then rinsed with 99.5% dichlorofluoroethane for 5 minutes;

[0139] S223: transferring the chip to the fixture groove soaked with 99.9% methanol, soaking the chip surface with 99.9% methanol again, using 0.2% bromine methanol solution as the polishing liquid, with a dripping speed of 20 ml / min and a polishing speed of 40 r / min to start the polishing, so that the film thickness of the epitaxial mercury cadmium telluride film on the cadmium zinc telluride chip is 9 μm;

[0140] S224: After the chemical polishing is completed, the residual mixed solution on the surface of the chip is immediately rinsed off with 99.9% methanol, and then rinsed in 99.9% methanol for 8 times;

[0141] S225: Spray wash with 99.00% anhydrous ethanol for 2 minutes, then blow dry with nitrogen for microscopic examination.

[0142] S3: passivation, forming a CdTe and ZnS composite passivation layer on the surface of the test chip;

[0143] It includes the following steps:

[0144] S31 preparation steps: debug the coating equipment, the parameters are: vacuum degree: 5E-6bar; ignition pressure: CdTe-40mTorr, ZnS-40mTorr; Bais power: ZnS-50W, the model of the coating equipment is Weikai, HY019E;

[0145] S32 sputtering steps: film layer: CdTe and ZnS composite passivation layer; film thickness: the thickness of CdTe and ZnS are

[0146] Temperature: CdTe-70℃, ZnS-50℃; Power: CdTe-200W, ZnS-400W; Ar flow: CdTe-57sccm, ZnS-47sccm; Duration: CdTe-2700s, ZnS-1994s; Auxiliary deposition of ZnS-120s.

[0147] S4: Test the minority carrier lifetime; evenly apply silicone grease on the back of the chip and put it into the minority carrier lifetime tester and then evacuate the vacuum. Set the parameters of the minority carrier lifetime tester to a scanning resolution of 0.5 mm, a microwave frequency of 10.5 GHz, and a wavelength of 904 nm, and test the minority carrier lifetime of the chip.

[0148] S5: Remove the silicone grease and wipe the silicone grease on the back of the chip with 99.0% anhydrous ethanol.

[0149] S6: removing the passivation layer, which includes the following sub-steps;

[0150] S61: Fix the chip to be corroded on the cleaning machine for cleaning. After cleaning, rinse it quickly with acetone, then soak it in anhydrous ethanol twice, each time for 5 minutes, and finally rinse it with deionized water for 10 minutes;

[0151] S62: placing the cleaned chip into a 37% hydrochloric acid solution, rotating the flower basket once per second during the etching process, and rotating in the opposite direction in the same way after 5 seconds; taking out the flower basket after etching for 45 seconds to stop etching;

[0152] S63: Immediately put the chip after etching into deionized water for cleaning 4 times, one circle clockwise and one circle counterclockwise respectively, and then wash the front and back sides of the chip with deionized water four times in sequence; then rinse with deionized water for 10 minutes, and finally rinse with anhydrous ethanol twice in sequence;

[0153] S64: After cleaning, take out the chip, blow dry it and inspect it under a microscope.

[0154] S7: Second cleaning, which includes the following sub-steps;

[0155] S71: At 80°C: soak the chip in 99.9% trichloroethylene solution for 30 minutes; then soak it in 90% N-methylpyrrolidone for 5 minutes; and finally soak it in 99.9% trichloroethylene for 5 minutes;

[0156] S72: Rinse: rinse twice with 99.0% anhydrous ethanol, 5 minutes each time;

[0157] S73: After cleaning, take out the chip, blow dry it and inspect it under a microscope.

[0158] S8: Tape out.

[0159] The above description is only by way of illustration of certain exemplary embodiments of the present invention. It is undoubted that those skilled in the art can modify the described embodiments in various ways without departing from the spirit and scope of the present invention. Therefore, the above drawings and descriptions are illustrative in nature and should not be construed as limiting the scope of protection of the claims of the present invention.

Claims

1. A method for testing the minority carrier lifetime of mercury cadmium telluride, characterized in that: The method specifically comprises the following steps: S1: Pretreatment: The first cleaning to remove impurities and dirt on the surface of the chip to be tested; S2: removing the oxide layer, which includes S21 etching step and S22 polishing step; S22 polishing step, specifically includes the following sub-steps: S221: Calculate the polishing time t for each piece according to the film thickness of the incoming piece, t = (THK-9.0) / 5.5*60s, and subtract 5-10s from the polishing time of the first piece of each batch; S222: Prepare chemical polishing liquid: 0.2% bromine methanol solution, the mixed liquid includes bromine water, 99.9% methanol and 99.0% ethylene glycol, the volume ratio of each component is 1:125:375, before the chemical polishing begins, rinse the chemical polishing pad with 99.9% methanol for 10 minutes, and then rinse with 99.5% dichlorofluoroethane for 5 minutes; S223: Transfer the chip to the fixture groove soaked with 99.9% methanol, soak the chip surface with 99.9% methanol again, use 0.2% bromine methanol solution as the polishing liquid, drip at a speed of 20ml / min, and start polishing at a speed of 40r / min, so that; S224: After the chemical polishing is completed, the residual mixed solution on the surface of the chip is immediately rinsed off with 99.9% methanol, and then rinsed in 99.9% methanol for 6-8 times; S225: Spray with 99.00% anhydrous ethanol for 1-2 minutes, then blow dry with nitrogen for microscopic examination; S3: passivation, forming a CdTe and ZnS composite passivation layer on the surface of the test chip; It includes the following sub-steps: S31 preparation steps: debug the coating equipment, the parameters are: vacuum degree: 5E-6bar; ignition pressure: CdTe-40mTorr, ZnS-40mTorr; Bais power: ZnS-50W; S32 sputtering steps: film layer: CdTe and ZnS composite passivation layer; film thickness: the thickness of CdTe and ZnS are Temperature: CdTe-70℃, ZnS-50℃; Power: CdTe-200W, ZnS-400W; Ar flow: CdTe-57sccm, ZnS-47sccm; Duration: CdTe-2700s, ZnS-1994s; Auxiliary deposition ZnS-120s; S4: Test minority carrier lifetime; S5: Remove the silicone grease and wipe the silicone grease on the back of the chip with 99.0% anhydrous ethanol; S6: removing the passivation layer; S7: second cleaning; S8: Tape out.

2. The method for testing the HgCdTe minority carrier lifetime according to claim 1, characterized in that: The first cleaning step in step S1 specifically includes the following sub-steps: S11: At 80°C: soak the chip in a 99.9% trichloroethylene solution for 30 minutes; then soak it in 50%-90% N-methylpyrrolidone for 5-10 minutes; and finally soak it in 99.9% trichloroethylene for 3-5 minutes; S12: Rinse: rinse twice with 99.0% anhydrous ethanol, each time for 3-5 minutes; S13: After cleaning, take out the chip, blow dry it and inspect it under a microscope.

3. The method for testing the HgCdTe minority carrier lifetime according to claim 1, characterized in that: The S21 corrosion step includes the following sub-steps: S211: The chip is immersed in deionized water for 5 minutes; S212: placing the chip on the flower basket, and then placing the flower basket in a mixture of 99.9% methanol and 0.1-0.3% bromine water for etching. During the etching process, the flower basket is rotated once per second. After 5 seconds, it is rotated in the opposite direction in the same way. After etching for 10 seconds, the flower basket is removed and the etching is stopped. S213: immediately placing the etched chip in a 99.9% methanol solution, rotating the chip clockwise and counterclockwise for one circle, and then cleaning the front and back sides of the chip respectively, and then placing the chip in a 99.9% methanol solution for three times for cleaning; S214: After cleaning, take out the chip, blow dry it and inspect it under a microscope.

4. The method for testing the HgCdTe minority carrier lifetime according to claim 3, characterized in that: The volume ratio of the mixed solution of 99.9% methanol and 0.1-0.3% bromine water in step S212 is 250:1, and the concentration of bromine water is preferably 0.2%.

5. The method for testing the HgCdTe minority carrier lifetime according to claim 1, characterized in that: In step S4, the reverse side of the chip is evenly coated with silicone grease and placed in a minority carrier lifetime tester and then evacuated. The parameters of the minority carrier lifetime tester are set to a scanning resolution of 0.5 mm, a microwave frequency of 10 Hz-10.5 GHz, and a wavelength of 904 nm, and the minority carrier lifetime of the chip is tested.

6. The method for testing the HgCdTe minority carrier lifetime according to claim 1, characterized in that: The step of removing the passivation layer in S6 includes the following sub-steps: S61: Fix the chip to be corroded on the cleaning machine for cleaning. After cleaning, rinse it quickly with acetone, then soak it in anhydrous ethanol twice, each time for 5 minutes, and finally rinse it with deionized water for 10 minutes; S62: placing the cleaned chip into a 37% hydrochloric acid solution, rotating the flower basket once per second during the etching process, and rotating in the opposite direction in the same way after 5 seconds; taking out the flower basket after etching for 45 seconds to stop etching; S63: Immediately put the chip after etching into deionized water for cleaning 4 times, one circle clockwise and one circle counterclockwise respectively, and then wash the front and back sides of the chip with deionized water four times in sequence; then rinse with deionized water for 10 minutes, and finally rinse with anhydrous ethanol twice in sequence; S64: After cleaning, take out the chip, blow dry it and inspect it under a microscope.

7. The method for testing the HgCdTe minority carrier lifetime according to claim 2, characterized in that: The second cleaning step of S7 includes the following steps: S71: At 80°C: soak the chip in 99.9% trichloroethylene solution for 30 minutes; then soak it in 50%-90% N-methylpyrrolidone for 5-10 minutes; finally soak it in 99.9% trichloroethylene for 3-5 minutes; S72: Rinse: rinse twice with 99.0% anhydrous ethanol, each time for 3-5 minutes; S73: After cleaning, take out the chip, blow dry it and inspect it under a microscope.

8. The method for testing the HgCdTe minority carrier lifetime according to claim 7, characterized in that: The concentration of N-methylpyrrolidone in steps S11 and S71 is preferably 90%.

9. The method for testing the HgCdTe minority carrier lifetime according to claim 1, characterized in that: The material of the chip to be tested is a cadmium zinc telluride substrate on which a layer of mercury cadmium telluride film is grown by liquid phase vertical epitaxy.

10. The method for testing the HgCdTe minority carrier lifetime according to claim 9, characterized in that: In the step S223, the thickness of the epitaxial HgCdTe film on CdZnTe is preferably 9 μm.

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