Surface treatment method of germanium ingot

Abstract

A method for treating the surface of a germanium ingot comprises the following steps: wiping the inorganic impurities on the surface of the germanium ingot clean, placing the germanium ingot into a support frame, placing the support frame and the germanium ingot into a first tank containing deionized water and ultrasonically cleaning them; then, moving the support frame and the germanium ingot into a second tank containing trichloroethane and ultrasonically cleaning them; then, moving the support frame and the germanium ingot into a third tank containing acetone and ultrasonically cleaning them; then, moving the support frame and the germanium ingot into a fourth tank containing methanol and ultrasonically cleaning them; then, moving the support frame and the germanium ingot into a fifth tank containing deionized water and ultrasonically cleaning them; then, moving the support frame and the germanium ingot into a sixth tank containing an acid etching solution for etching; then, taking the support frame and the germanium ingot out of the sixth tank, rinsing the germanium ingot with deionized water, then rinsing the germanium ingot with methanol, then immersing the germanium ingot in a container containing methanol, and then placing the germanium ingot immersed in methanol and the container into a clean bench for storage. In this way, organic matter on the surface of the germanium ingot can be removed.

Description

Technical Field

[0001] The present disclosure relates to the field of germanium materials, and more specifically to a method for surface treatment of germanium ingots. Background Art

[0002] In the process of purifying germanium ingots to prepare germanium crystals, the surface of the germanium ingots is treated to improve the purity of the purified germanium crystals.

[0003] Chinese patent application publication number CN102206859A published on October 5, 2011 discloses a process and special equipment for preparing ultra-high purity germanium single crystals, in which the polycrystalline ingot cleaning process is: first ultrasonic cleaning with pure water, then chemical cleaning, and finally rinsing with pure water, dehydrating by methanol elution and drying with nitrogen.

[0004] Chinese patent application publication number CN109321976A published on February 12, 2019 discloses a method and equipment for preparing 13N ultra-high purity germanium single crystals, wherein the cleaning process of the metal germanium material is: first soak in a soaking solution (HNO3:HF=3:1 (volume ratio)), then rinse with pure water, then soak in a cleaning solution (HCL:H2O2:H2O=1:1:4 (volume ratio)), then rinse with pure water, and finally dehydrate by methanol elution and dry with a bathroom lamp.

[0005] The cleaning of the germanium ingot / germanium material in the above patent document only removes the oxide on the surface of the germanium ingot, but does not remove the organic matter on the surface of the germanium ingot. In the production process of the germanium ingot, it is inevitable that organic matter will remain on the surface of the germanium ingot. These organic matters include cutting fluid residues, grease, lubricating oil, paraffin, oily dirt, fiber, organic matter from hand sweat, etc. Summary of the invention

[0006] In view of the problems existing in the background technology, the purpose of the present disclosure is to provide a surface treatment method for a germanium ingot, which can remove organic matter on the surface of the germanium ingot and thus help to improve the purity of the purified germanium crystal.

[0007] Thus, in some embodiments, a method for treating the surface of a germanium ingot comprises the following steps: S1, wiping off inorganic impurities on the surface of the germanium ingot, placing the germanium ingot in a support frame, placing the support frame together with the germanium ingot in a first tank filled with deionized water and immersing the germanium ingot in the deionized water, and using deionized water and ultrasound to clean the surface of the germanium ingot in the first tank; S2, after step S1 is completed, moving the support frame together with the germanium ingot from the first tank into a second tank filled with trichloroethane and immersing the germanium ingot in trichloroethane, and using trichloroethane and ultrasound to clean the surface of the germanium ingot in the second tank; S3, after step S2 is completed, moving the support frame together with the germanium ingot from the second tank into a third tank filled with acetone and immersing the germanium ingot in acetone, and using acetone and ultrasound to clean the surface of the germanium ingot in the third tank; S4, after step S3 is completed, placing the support frame The support frame together with the germanium ingot is moved from the third tank into the fourth tank filled with methanol and the methanol is used to immerse the germanium ingot, and the surface of the germanium ingot is cleaned with methanol and ultrasound in the fourth tank; S5, after the completion of step S4, the support frame together with the germanium ingot is moved from the fourth tank into the fifth tank filled with deionized water and the deionized water is used to immerse the germanium ingot, and the surface of the germanium ingot is cleaned with deionized water and ultrasound in the fifth tank; S6, after the completion of step S5, the support frame together with the germanium ingot is moved from the fifth tank into the sixth tank filled with acid etching solution for surface etching; S7, after the completion of step S6, the support frame together with the germanium ingot is taken out from the sixth tank, the germanium ingot is rinsed with deionized water, and then the germanium ingot is rinsed with methanol to remove the deionized water, and then the germanium ingot is immersed in a container filled with methanol, and then the germanium ingot immersed in methanol and the container are placed in a clean bench for storage.

[0008] In some embodiments, step S1 selects at least one of the following features: in step S1, inorganic impurities on the surface of the germanium ingot are wiped clean with a dust-free cloth of grade 100 or above wetted with deionized water; in step S1, the first tank is a PE tank; in step S1, ultrasonic cleaning is performed for 5-10 minutes.

[0009] In some embodiments, step S2 selects at least one of the following features: in step S2, a person wearing a Class 100 clean glove holds the support frame by hand and moves the support frame together with the germanium ingot from the first tank into a second tank filled with trichloroethane, and the second tank is located in a fume hood; in step S2, the second tank is a PE tank; in step S2, ultrasonic cleaning is performed for 5-10 minutes.

[0010] In some embodiments, step S3 selects at least one of the following features: in step S3, a person wearing a class 100 clean glove holds the support frame by hand and moves the support frame together with the germanium ingot from the second tank into a third tank filled with acetone, and the third tank is located in a fume hood; in step S3, the third tank is a PE tank; in step S3, ultrasonic cleaning is performed for 5-10 minutes.

[0011] In some embodiments, step S4 selects at least one of the following features: in step S4, a person wearing a class 100 clean glove holds the support frame by hand and moves the support frame together with the germanium ingot from the third tank to a fourth tank containing methanol, and the fourth tank is located in a fume hood; in step S4, the fourth tank is a PE tank; in step S4, ultrasonic cleaning is performed for 5-10 minutes.

[0012] In some embodiments, step S5 selects at least one of the following features: in step S5, a person wearing a class 100 clean glove holds the support frame by hand and moves the support frame together with the germanium ingot from the fourth tank into the fifth tank filled with deionized water; in step S5, the fifth tank is a PE tank; in step S5, ultrasonic cleaning is performed for 5-10 minutes.

[0013] In some embodiments, step S6 selects at least one of the following features: in step S6, a person wearing a Class 100 clean glove holds the support frame by hand and moves the support frame together with the germanium ingot from the fifth tank to the sixth tank containing acid etching solution, and the sixth tank is located in the fume hood; the sixth tank is a PE tank; in step S6, the acid etching solution is composed of nitric acid and hydrofluoric acid, and the volume ratio is HNO3:HF=(5-6):1; in step S6, the surface is corroded for 5-10 minutes.

[0014] In some embodiments, step S7 selects at least one of the following features: in step S7, a person wearing a Class 100 clean glove holds the support frame by hand to take the support frame together with the germanium ingot out of the sixth tank; in step S7, the germanium ingot on the support frame is rinsed with deionized water for 10-15 minutes; then the germanium ingot on the support frame is rinsed with methanol to remove the deionized water, and then the germanium ingot on the support frame is transferred to a PE container with methanol using a PE clamp, and then the germanium ingot immersed in methanol and the PE container are placed in a Class 100 clean bench for storage.

[0015] In some embodiments, the method for treating the surface of a germanium ingot further includes the step: S8, taking out the germanium ingot from a container containing methanol before loading it into a furnace for purification, and loading it into a furnace for purification after the methanol on the surface of the germanium ingot has evaporated.

[0016] In some embodiments, step S8 selects at least one of the following features: in step S8, the germanium ingot is taken out of the container containing methanol using a PE clamp; in step S8, the methanol on the surface of the germanium ingot is blown dry using high-purity nitrogen; the purity of the high-purity nitrogen is 7N.

[0017] The beneficial effects of the present disclosure are as follows: in step S1, inorganic impurities (such as metal particles, dust, etc.) on the surface of the germanium ingot are physically removed by wiping; in step S2, trichloroethane has a strong dissolving ability when used as a solvent, and can effectively remove organic matter on the surface of the germanium ingot. Due to the low surface tension and high penetration ability of trichloroethane, coupled with the effect of ultrasound, trichloroethane can effectively penetrate into the gaps on the surface of the germanium ingot, and effectively remove organic matter in the gaps on the surface of the germanium ingot; in step S3, acetone can effectively remove trichloroethane and residual Organic matter; in step S4, methanol can effectively remove the acetone remaining on the germanium ingot, preventing the acetone from reacting with the acid etching solution in the subsequent step S6. Similarly, in step S5, methanol is removed by deionized water to prevent methanol from reacting with the acid etching solution in the subsequent step S6; in step S7, the germanium ingot is immersed in a container filled with methanol after etching and before loading into the furnace in the later-described step S8, which can isolate the pollution from particles and organic matter in the air and avoid pollution during the transfer process to step S8. Methanol has a strong dehydration ability and can prevent the germanium ingot from oxidation. Therefore, the surface treatment method of the germanium ingot disclosed in the present invention can remove organic matter on the surface of the germanium ingot, thereby helping to improve the purity of the purified germanium ingot. DETAILED DESCRIPTION

[0018] [Surface treatment method of germanium ingot]

[0019] The surface treatment method of a germanium ingot according to the present disclosure comprises the steps of:

[0020] S1, wiping off inorganic impurities on the surface of the germanium ingot, placing the germanium ingot in a support frame, placing the support frame and the germanium ingot in a first tank filled with deionized water so that the deionized water immerses the germanium ingot, and cleaning the surface of the germanium ingot in the first tank with deionized water and ultrasound;

[0021] S2, after step S1 is completed, the support frame together with the germanium ingot is moved from the first tank into a second tank filled with trichloroethane and the trichloroethane is immersed in the germanium ingot, and the surface of the germanium ingot is cleaned in the second tank using trichloroethane and ultrasound;

[0022] S3, after step S2 is completed, the support frame together with the germanium ingot is moved from the second tank into a third tank containing acetone and the acetone is immersed in the germanium ingot, and the surface of the germanium ingot is cleaned in the third tank using acetone and ultrasound;

[0023] S4, after step S3 is completed, the support frame together with the germanium ingot is moved from the third tank into a fourth tank containing methanol and the methanol is immersed in the germanium ingot, and the surface of the germanium ingot is cleaned in the fourth tank using methanol and ultrasound;

[0024] S5, after step S4 is completed, the support frame together with the germanium ingot is moved from the fourth tank into the fifth tank filled with deionized water so that the deionized water immerses the germanium ingot, and the surface of the germanium ingot is cleaned in the fifth tank using deionized water and ultrasound;

[0025] S6, after step S5 is completed, the support frame together with the germanium ingot is moved from the fifth tank to a sixth tank containing an acid etching solution for surface etching;

[0026] S7, after step S6 is completed, the support frame together with the germanium ingot is taken out from the sixth tank, the germanium ingot is rinsed with deionized water, and then the germanium ingot is rinsed with methanol to remove the deionized water, and then the germanium ingot is immersed in a container containing methanol, and then the germanium ingot immersed in methanol and the container are placed in a clean bench for storage.

[0027] In the surface treatment method of germanium ingot disclosed in the present invention, in step S1, inorganic impurities (such as metal particles, dust, etc.) on the surface of the germanium ingot are physically removed by wiping. In step S2, since trichloroethane has a strong dissolving power when used as a solvent, organic matter on the surface of the germanium ingot can be effectively removed. Due to the low surface tension and high permeability of trichloroethane, coupled with the ultrasonic effect, trichloroethane can effectively penetrate into the gaps on the surface of the germanium ingot, and effectively remove organic matter in the gaps on the surface of the germanium ingot. In step S3, acetone can effectively remove trichloroethane and residual organic matter remaining on the germanium ingot. In step S4, methanol can effectively remove acetone remaining on the germanium ingot to prevent acetone from reacting with the acid etching solution in the subsequent step S6. Similarly, in step S5, methanol is removed by deionized water to prevent methanol from reacting with the acid etching solution in the subsequent step S6. In step S7, after etching and before loading into the furnace in step S8 described later, the germanium ingot is immersed in a container containing methanol, which can isolate the pollution from particles and organic matter in the air and avoid pollution during the transfer process to step S8. Methanol has a strong dehydration ability and can prevent the germanium ingot from oxidation. In summary, the surface treatment method of the germanium ingot disclosed in the present invention can remove organic matter on the surface of the germanium ingot, thereby helping to improve the purity of the purified germanium ingot.

[0028] In one embodiment, in step S1, deionized water may be used to wet a dust-free cloth of grade 100 or higher to wipe away inorganic impurities on the surface of the germanium ingot. The dust-free cloth of grade 100 or higher can be used to remove inorganic impurities on the surface of the germanium ingot while preventing the dust-free cloth from introducing impurities.

[0029] In step S1, the first tank may be a PE (polyethylene) tank, which can avoid the introduction of impurities.

[0030] In step S1, the ultrasonic cleaning may be performed for 5-10 minutes.

[0031] In one embodiment, in step S2, a person wearing a Class 100 clean glove holds the support frame by hand and moves the support frame together with the germanium ingot from the first tank to the second tank containing trichloroethane, and the second tank is located in a fume hood. Similarly, the use of Class 100 clean gloves avoids the introduction of impurities. Because trichloroethane is easy to evaporate and toxic, the ventilation of the fume hood can improve the safety of the operator's working environment.

[0032] Likewise, in step S2, the second tank may be a PE tank, thereby being able to avoid the introduction of impurities.

[0033] Likewise, in step S2, ultrasonic cleaning may be performed for 5-10 minutes.

[0034] In one embodiment, in step S3, a person wearing a Class 100 clean glove holds the support frame by hand and moves the support frame together with the germanium ingot from the second tank to the third tank containing acetone, and the third tank is located in a fume hood. Similarly, the use of Class 100 clean gloves avoids the introduction of impurities. Similarly, because acetone is easy to evaporate and toxic, the ventilation of the fume hood can improve the safety of the operator's working environment.

[0035] Likewise, in step S3, the third tank may be a PE tank, thereby being able to avoid the introduction of impurities.

[0036] Likewise, in step S3, ultrasonic cleaning may be performed for 5-10 minutes.

[0037] In one embodiment, in step S4, a person wearing a Class 100 clean glove holds the support frame with his hand and moves the support frame together with the germanium ingot from the third tank to the fourth tank containing methanol, and the fourth tank is located in a fume hood. Similarly, the use of Class 100 clean gloves avoids the introduction of impurities. Similarly, because methanol is easy to evaporate and toxic, the ventilation of the fume hood can improve the safety of the operator's working environment.

[0038] Likewise, in step S4, the fourth tank may be a PE tank, thereby being able to avoid the introduction of impurities.

[0039] Likewise, in step S4, ultrasonic cleaning may be performed for 5-10 minutes.

[0040] In one embodiment, in step S5, a person wearing a Class 100 clean glove holds the support frame by hand and moves the support frame and the germanium ingot from the fourth tank to the fifth tank containing deionized water. Similarly, the use of Class 100 clean gloves avoids the introduction of impurities. At this time, the fifth tank does not need to be located in a fume hood.

[0041] Likewise, in step S5, the fifth tank may be a PE tank, thereby being able to avoid the introduction of impurities.

[0042] Likewise, in step S5, ultrasonic cleaning may be performed for 5-10 minutes.

[0043] In one embodiment, in step S6, a person wearing a Class 100 clean glove holds the support frame by hand and moves the support frame together with the germanium ingot from the fifth tank into the sixth tank containing the acid etching solution, and the sixth tank is located in a fume hood. Similarly, the use of Class 100 clean gloves avoids the introduction of impurities. Similarly, because the acid etching solution is easy to evaporate and toxic, the ventilation of the fume hood can improve the safety of the operator's working environment.

[0044] Likewise, the sixth tank may be a PE tank, thereby being able to avoid the introduction of impurities.

[0045] In step S6, the surface corrosion may be performed for 5-10 minutes.

[0046] In step S6, the acid etching solution may be composed of nitric acid and hydrofluoric acid. In one embodiment, the volume ratio is HNO3:HF=(5-6):1.

[0047] In one embodiment, in step S7, a person wearing a Class 100 clean glove holds the support frame by hand and takes the support frame together with the germanium ingot out of the sixth tank. Similarly, the use of Class 100 clean gloves avoids the introduction of impurities.

[0048] Further, in step S7, the germanium ingot on the support frame is rinsed with deionized water for 10-15 minutes; then the germanium ingot on the support frame is rinsed with methanol to remove the deionized water, and then the germanium ingot on the support frame is transferred to a PE container with methanol using a PE clamp, and then the germanium ingot immersed in methanol and the PE container are placed in a Class 100 clean bench for storage. The PE clamp can avoid the introduction of impurities. Similarly, the PE container can avoid the introduction of impurities.

[0049] In one embodiment, the method for treating the surface of a germanium ingot further comprises the step: S8, taking out the germanium ingot from a container containing methanol before charging to a furnace for purification, and charging to a furnace for purification after the methanol on the surface of the germanium ingot has evaporated. Further, in step S8, the germanium ingot is taken out of the container containing methanol using a PE clamp. The PE clamp can avoid the introduction of impurities. In step S8, the methanol on the surface of the germanium ingot can be blown dry with high-purity nitrogen. The purity of the high-purity nitrogen is, for example, 7N. In step S8, the purification can be zone melting purification.

[0050] [test]

[0051] Example 1

[0052] The surface treatment method of germanium ingot comprises the steps of:

[0053] S1, wet a Class 100 dust-free cloth with deionized water to wipe off inorganic impurities on the surface of the germanium ingot, put the germanium ingot into a support frame, put the support frame and the germanium ingot into a first tank made of PE material filled with deionized water and immerse the germanium ingot in the deionized water, and clean the surface of the germanium ingot with deionized water and ultrasound in the first tank for 10 minutes;

[0054] S2, after step S1 is completed, a person wearing a Class 100 clean glove holds the support frame with his hand and moves the support frame and the germanium ingot from the first tank into a second tank made of PE material and located in a fume hood and filled with trichloroethane, and immerses the germanium ingot in trichloroethane, and cleans the surface of the germanium ingot in the second tank with trichloroethane and ultrasound for 10 minutes;

[0055] S3, after step S2 is completed, a person wearing a Class 100 clean glove holds the support frame by hand and moves the support frame together with the germanium ingot from the second tank into a third tank made of PE material and containing acetone in a fume hood, and immerses the germanium ingot in acetone. In the third tank, the surface of the germanium ingot is cleaned for 10 minutes using acetone and ultrasound;

[0056] S4, after step S3 is completed, a person wearing a Class 100 clean glove holds the support frame with his hand and moves the support frame and the germanium ingot from the third tank into a fourth tank made of PE material and located in a fume hood and filled with methanol, and immerses the germanium ingot in methanol. In the fourth tank, the surface of the germanium ingot is cleaned for 10 minutes using methanol and ultrasound;

[0057] S5, after step S4 is completed, a person wearing a Class 100 clean glove holds the support frame with his hand and moves the support frame together with the germanium ingot from the fourth tank into the fifth tank filled with deionized water so that the deionized water immerses the germanium ingot, and cleans the surface of the germanium ingot with deionized water and ultrasound in the fifth tank for 5-10 minutes;

[0058] S6, after step S5 is completed, a person wearing a Class 100 clean glove holds the support frame with his hand and moves the support frame together with the germanium ingot from the fifth tank into the sixth tank of PE material in the fume hood filled with acid etching solution for surface etching for 10 minutes. The acid etching solution is composed of nitric acid and hydrofluoric acid, and the volume ratio is HNO3:HF=5:1;

[0059] S7, after step S6 is completed, a person wearing a Class 100 clean glove holds the support frame by hand to take the support frame together with the germanium ingot out of the sixth tank, rinses the germanium ingot on the support frame with deionized water for 15 minutes, then rinses the germanium ingot on the support frame with methanol to remove the deionized water, then uses a PE clip to transfer the germanium ingot on the support frame and immerses it in a PE material container containing methanol, and then puts the germanium ingot immersed in methanol together with the container into a Class 100 clean bench for storage;

[0060] S8, before loading into the furnace for purification, take out the germanium ingot from the container containing methanol with a PE clamp, blow dry the methanol on the surface of the germanium ingot with high-purity nitrogen with a purity of 7N, and then load into the furnace for zone melting purification.

[0061] Comparative Example 1

[0062] Except that steps S2-S5 are not adopted, the rest is the same as that of embodiment 1.

[0063] Comparative Example 2

[0064] Except that in step S2, the second tank made of PE material contains trichlorotrifluoroethane, the rest is the same as in Example 1.

[0065] Comparative Example 3

[0066] Except that the fourth tank made of PE material contains ethanol in step S4, the rest is the same as in Example 1.

[0067] Comparative Example 4

[0068] Except that the second tank made of PE material in step S2 contains trichlorotrifluoroethane and the fourth tank made of PE material in step S4 contains ethanol, the rest is the same as in embodiment 1.

[0069] Comparative Example 5

[0070] Except that in step S7 , the PE container containing methanol is not used to immerse the germanium ingot, the rest is the same as in Example 1.

[0071] Comparative Example 6

[0072] Except that a PE container filled with ethanol is used to immerse the germanium ingot in step S7, the rest is the same as in Example 1.

[0073] Comparative Example 7

[0074] Except that in step S7, the germanium ingot on the support frame is transferred manually by wearing class 100 clean gloves, the rest is the same as in Example 1.

[0075] In Example 1 and Comparative Examples 1-7, in step S1, the germanium ingot is germanium polycrystal from the same batch, and the test is performed after the zone melting performed in step S8 is completed. The test process is as follows: the polycrystalline germanium ingot that has undergone 30-40 zone meltings is placed in a room with a constant temperature of 23°C until the polycrystalline germanium ingot cools to 23°C; the resistivity of the germanium ingot is detected by a two-needle resistivity meter, and the resistivity greater than 50Ω*m is a preliminary qualified segment. Take germanium sheets with a thickness of 1.5-2mm at the head and tail of the preliminary qualified segment; grind and etch the germanium sheet to 1-1.5mm; cut the etched germanium sheet into (10-15)*(10-15)*(1-1.5)mm 3Then, tin particles are pressed on the four corners of the germanium sheet and annealed to form a good ohmic contact. Then, IV test is performed. If there is no problem, low-temperature Hall test is performed. If the carrier concentration is less than 2e11cm -3 , it is qualified; otherwise, it is unqualified, and the germanium slice needs to be cut 3-5cm from the middle of the preliminary qualified section until the carrier concentration is less than 2e11cm -3 The test results are listed in Table 1.

[0076] Note that in Table 1, the purity and carrier concentration are corresponding, such as the carrier concentration corresponding to purity 13N is 2e9-2e10cm -3 , the carrier concentration corresponding to the purity of 12N is 2e10-2e11cm -3 The Hall detection equipment is HL9900 from Toho Technology of the United States.

[0077] In Table 1, the proportion (weight) of purity greater than or equal to 12N is the carrier concentration less than 2e11cm after the Hall detection in step 8. -3 The weight of the germanium ingot after zone melting and purification (if the germanium slices cut and tested also meet the carrier concentration of less than 2e11cm -3 , including the cut and tested germanium slices) to the weight ratio of the germanium ingot before step 1. In Example 1 and Comparative Examples 1-7, the germanium ingot before step 1 was 5 kg.

[0078] Table 1 Test results of Example 1 and Comparative Examples 1-7

[0079]

[0080]

[0081] Compared with the comparative example 1 which does not adopt steps S2-S5, the proportion of purity greater than or equal to 12N obtained in Example 1 is doubled by adopting steps S2-S5. This indicates that Example 1 adopts steps S2-S5 to effectively remove organic matter on the surface of the germanium ingot, thereby helping to improve the purity of the germanium crystal obtained by purification.

[0082] Compared with Comparative Example 2 in which trichlorotrifluoroethane is contained in the second tank of PE material in step S2, in Example 1 in which trichloroethane is contained in the second tank of PE material in step S2, the absolute value of the proportion of purity greater than or equal to 12N obtained in Example 1 is increased by 15%, which indicates that trichloroethane is much better than trichlorotrifluoroethane in removing organic matter. This is because the germanium ingot is uneven and has many gaps on the surface. Due to the low surface tension and high penetration ability of trichloroethane, it can effectively penetrate into the gaps on the surface of the germanium ingot and effectively remove organic matter in the gaps on the surface of the germanium ingot.

[0083] Compared with Comparative Example 3, in which the fourth tank of the PE material in step S4 contains ethanol, in Example 1, in which the fourth tank of the PE material in step S4 contains methanol, the absolute value of the proportion of purity greater than or equal to 12N obtained in Example 1 is increased by 10%, which shows that the effect of removing acetone by using methanol in step S4 is better than that of removing acetone by using ethanol. This is also reflected in the results of Comparative Examples 2 and 4.

[0084] Compared with Comparative Example 5 in which the germanium ingot is not immersed in a PE container filled with methanol in step S7, Example 1 uses a PE container filled with methanol to immerse the germanium ingot in step S7, which does not introduce particles and organic pollutants in the air and the germanium ingot is unlikely to be oxidized.

[0085] Compared with Comparative Example 6 in which the germanium ingot is immersed in a PE material container filled with ethanol in step S7, the effect of immersing the germanium ingot in Example 1 in which the germanium ingot is immersed in a PE material container filled with methanol in step S7 is better.

[0086] Compared with Comparative Example 7, in step S7, the germanium ingot on the support frame is transferred manually by wearing Class 100 clean gloves, while Example 1 has a better effect of transferring the germanium ingot on the support frame by using PE clips.

Claims

1. A method for surface treatment of a germanium ingot, characterized in that: Includes steps: S1, wiping off inorganic impurities on the surface of the germanium ingot, placing the germanium ingot in a support frame, placing the support frame and the germanium ingot in a first tank filled with deionized water so that the deionized water immerses the germanium ingot, and cleaning the surface of the germanium ingot in the first tank with deionized water and ultrasound; S2, after step S1 is completed, the support frame together with the germanium ingot is moved from the first tank into a second tank filled with trichloroethane and the trichloroethane is immersed in the germanium ingot, and the surface of the germanium ingot is cleaned in the second tank using trichloroethane and ultrasound; S3, after step S2 is completed, the support frame together with the germanium ingot is moved from the second tank into a third tank containing acetone and the acetone is immersed in the germanium ingot, and the surface of the germanium ingot is cleaned in the third tank using acetone and ultrasound; S4, after step S3 is completed, the support frame together with the germanium ingot is moved from the third tank into a fourth tank containing methanol and the methanol is immersed in the germanium ingot, and the surface of the germanium ingot is cleaned in the fourth tank using methanol and ultrasound; S5, after step S4 is completed, the support frame together with the germanium ingot is moved from the fourth tank into the fifth tank filled with deionized water so that the deionized water immerses the germanium ingot, and the surface of the germanium ingot is cleaned in the fifth tank using deionized water and ultrasound; S6, after step S5 is completed, the support frame together with the germanium ingot is moved from the fifth tank to the sixth tank containing an acid etching solution for surface etching, wherein the acid etching solution is composed of nitric acid and hydrofluoric acid, and the volume ratio is HNO3:HF=5:1; S7, after step S6 is completed, the support frame together with the germanium ingot is taken out from the sixth tank, the germanium ingot is rinsed with deionized water, and then the germanium ingot is rinsed with methanol to remove the deionized water, and then the germanium ingot is immersed in a container containing methanol with a PE clamp, and then the germanium ingot immersed in methanol and the container are placed in a clean bench for storage; in, In step S1, a dust-free cloth with a grade of 100 or higher is wetted with deionized water to wipe away inorganic impurities on the surface of the germanium ingot; In step S1, the first slot is a PE slot; In step S1, ultrasonic cleaning is performed for 10 min; In step S2, a person wearing a Class 100 clean glove holds the support frame by hand and moves the support frame together with the germanium ingot from the first tank into the second tank containing trichloroethane, and the second tank is located in a fume hood; In step S2, the second slot is a PE slot; In step S2, ultrasonic cleaning is performed for 10 minutes; In step S3, a person wearing a Class 100 clean glove holds the support frame by hand and moves the support frame together with the germanium ingot from the second tank into a third tank containing acetone, and the third tank is located in a fume hood; In step S3, the third slot is a PE slot; In step S3, ultrasonic cleaning is performed for 10 minutes; In step S4, a person wearing a Class 100 clean glove holds the support frame by hand and moves the support frame together with the germanium ingot from the third tank into the fourth tank containing methanol, and the fourth tank is located in a fume hood; In step S4, the fourth slot is a PE slot; In step S4, ultrasonic cleaning is performed for 10 minutes; In step S5, a person wearing a Class 100 clean glove holds the support frame by hand and moves the support frame together with the germanium ingot from the fourth tank into the fifth tank filled with deionized water; In step S5, the fifth slot is a PE slot; In step S5, ultrasonic cleaning is performed for 5-10 minutes; In step S6, a person wearing a Class 100 clean glove holds the support frame by hand and moves the support frame together with the germanium ingot from the fifth tank into the sixth tank containing the acid etching solution, and the sixth tank is located in the fume hood; The sixth slot is the PE slot; In step S6, the surface is corroded for 10 min; In step S7, a person wearing a Class 100 clean glove holds the support frame by hand and takes the support frame together with the germanium ingot out of the sixth tank; In step S7, the germanium ingot on the support frame is rinsed with deionized water for 15 minutes; then, the germanium ingot on the support frame is rinsed with methanol to remove the deionized water, and then the germanium ingot on the support frame is transferred to a PE container containing methanol using a PE clamp, and then the germanium ingot immersed in methanol and the PE container are placed in a Class 100 clean bench for storage; The method for surface treatment of germanium ingot also includes the steps of: S8, taking out the germanium ingot from the container containing methanol before loading it into the furnace for purification, and loading it into the furnace for purification after the methanol on the surface of the germanium ingot evaporates completely; in, In step S8, the germanium ingot is taken out from the container containing methanol using a PE clamp; In step S8, high-purity nitrogen is used to blow away the methanol on the surface of the germanium ingot; In step S8, the purity of the high-purity nitrogen is 7N; In step S8, the purification is zone melting purification, and the proportion of purity greater than or equal to 12N after zone melting purification is 50% by weight.

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