Treatment method of silicon sample for inert gas melting infrared absorption method
By adding mixed acid corrosion liquid and alkali corrosion in batches, the oxide layer on the surface of the silicon sample was completely removed, solving the problem of inaccurate measurement in the prior art and achieving higher measurement accuracy.
Patent Information
- Application Number
- CN202510588979.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-05-08
- Publication Date
- 2025-07-25
AI Technical Summary
In the prior art, when measuring the oxygen content of semiconductor materials by inert gas melt infrared absorption method, the surface oxide layer of the silicon sample is not thoroughly treated, resulting in inaccurate measurement results.
The mixed acid corrosion solution (different volume ratios of nitric acid, hydrofluoric acid and glacial acetic acid) was added in batches, combined with alkali corrosion, the reaction rate was controlled, and the oxide layer on the surface of the silicon sample was completely removed.
The accuracy of measuring the oxygen content of semiconductor materials by inert gas melt infrared absorption method is improved, and the measurement error is reduced.
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Figure CN120369424A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of silicon wafer detection, and specifically to a method for processing silicon samples used in the inert gas fusion infrared absorption method. Background Art
[0002] The oxygen content is an important parameter of semiconductor materials and devices. This parameter directly reflects the quality of semiconductor materials and the characteristics of devices. Moreover, the requirements for the oxygen content of heavily doped single-crystalline silicon wafers and silicon wafers used in high-power devices are getting higher and higher. Therefore, obtaining an accurate value of this parameter is of great significance for the manufacture of semiconductor devices.
[0003] Currently, the inert gas fusion infrared absorption method is mostly used to measure the oxygen content of semiconductor materials. Specifically, under high-temperature conditions, a silicon sample is melted in a graphite crucible in an inert atmosphere. The O element in the silicon sample escapes from the melt under high-temperature conditions and reacts with the carbon element in the graphite crucible, and is released in the form of CO. The CO is converted into CO2 by a copper oxide furnace. Finally, it is carried by a carrier gas and enters an infrared detector for detection after passing through a filtering, dust-removing and water-removing device. And in the prior art, the method for processing silicon sample blocks used in the inert gas fusion infrared absorption method is to dilute analytical grade hydrofluoric acid with a mass fraction of 49% with pure water. The oxide layer on the sample surface is removed with the etching solution, and then rinsed with pure water. This etching method has a slow reaction rate with the silicon surface oxide layer and cannot completely remove the oxide layer on the silicon sample surface, resulting in a large error in the measured oxygen content by the above method and inaccurate results. Summary of the Invention
[0004] In order to solve the problem of incomplete treatment of the oxide layer on the surface of silicon samples in the prior art, the present invention provides a method for processing silicon samples used in the inert gas fusion infrared absorption method, which can completely remove the oxide layer on the surface of silicon samples and improve the accuracy of measuring the oxygen content of semiconductor materials by the inert gas fusion infrared absorption method.
[0005] To achieve the above object, the specific solution adopted by the present invention is: a method for processing silicon samples used in the inert gas fusion infrared absorption method. After the silicon sample block is polished, pretreated and surface-etched, it is rinsed and dried to obtain a silicon sample. The surface etching of the silicon sample block includes acid etching and alkali etching. The process of acid etching is as follows: a mixed acid etching solution is obtained by mixing a nitric acid aqueous solution, a hydrofluoric acid aqueous solution and glacial acetic acid in a volume ratio of 10-9:2-3:3-4. The mixed acid etching solution is divided into two parts according to a volume ratio of 4:3 to 4. One part of the mixed acid etching solution and the silicon sample block are placed in a reactor and reacted for 8 to 10 minutes until a large number of bubbles begin to appear on the liquid surface, and at the same time, more smoke is generated on the liquid surface. Then, the other part of the mixed acid etching solution is added to the reactor to change the reaction path in the reactor, thereby controlling the reaction rate in the reactor.
[0006] As an optimized solution for the method of treating silicon samples used in the above-mentioned inert gas fusion infrared absorption method: A mixed acid etching solution is obtained by mixing nitric acid aqueous solution, hydrofluoric acid aqueous solution, and glacial acetic acid in a volume ratio of 10:3:4.
[0007] As another optimized solution for the method of treating silicon samples used in the above-mentioned inert gas fusion infrared absorption method: The mixed acid etching solution is divided into two parts according to a volume ratio of 4:4. 11. As another optimized solution for the method of treating silicon samples used in the above-mentioned inert gas fusion infrared absorption method: The mass fraction of nitric acid in the nitric acid aqueous solution is 69 - 70%. 12. As another optimized solution for the method of treating silicon samples used in the above-mentioned inert gas fusion infrared absorption method: The mass fraction of hydrofluoric acid in the hydrofluoric acid aqueous solution is 40 - 49%.
[0008] As another optimized solution for the method of treating silicon samples used in the above-mentioned inert gas fusion infrared absorption method: The alkali etching process is as follows: After the acid-etched silicon sample block is placed in a 1.5% - 2% KOH aqueous solution and reacted for 1 - 2 minutes, it is washed with pure water.
[0009] As another optimized solution for the method of treating silicon samples used in the above-mentioned inert gas fusion infrared absorption method: The polishing process of the silicon sample block is as follows: A polishing solution is obtained by mixing nitric acid aqueous solution, hydrofluoric acid aqueous solution, and glacial acetic acid in a volume ratio of 10 - 9:2 - 3:3 - 4, and the silicon sample block is polished with the polishing solution.
[0010] As another optimized solution for the method of treating silicon samples used in the above-mentioned inert gas fusion infrared absorption method: The pretreatment process of the silicon sample block is as follows: The polished silicon sample block is immersed in absolute ethanol for 1 - 2 minutes and then dried by blowing.
[0011] As another optimized solution for the method of treating silicon samples used in the above-mentioned inert gas fusion infrared absorption method: The etched silicon sample block is ultrasonically cleaned for 20 - 30 minutes.
[0012] As another optimized solution for the method of treating silicon samples used in the above-mentioned inert gas fusion infrared absorption method: The rinsed silicon sample block is dried by blowing with nitrogen.
[0013] Compared with the prior art, the present invention has the following beneficial effects:
[0014] The present invention provides a method for processing silicon samples used in the inert gas fusion infrared absorption method. After the silicon sample block is polished and pretreated, acid etching and alkali etching are carried out. During the acid etching process, the mixed acid etching solution is added to the reactor in two portions. The mixed acid etching solution added for the second time changes the reaction path in the reactor, thereby reducing the reaction rate in the reactor and achieving the effect of thoroughly removing the oxide layer on the surface of the silicon sample block. Specifically, the proportion of different components in the mixed acid affects the reaction rate. By adding a new mixed acid, the proportion of the reactants can be adjusted to make it more conducive to controlling the reaction rate. Therefore, during the reaction between the silicon wafer and the mixed acid, a new mixed acid is added, and the temperature and reaction rate of the reaction solution are closely monitored to ensure that the reaction rate is within a controllable range. Thus, the purpose of thoroughly removing the oxide layer on the surface of the silicon wafer is achieved. Description of the Drawings
[0015] Figure 1 It is a schematic diagram of the regression summary report of the deviation of the oxygen content test results between GFA test and FTIR test;
[0016] Figure 2 It is a schematic diagram of the regression model selection report of the oxygen content test results between GFA test and FTIR test;
[0017] Figure 3 It is a schematic diagram of the regression diagnosis report of the oxygen content test results between GFA test and FTIR test;
[0018] Figure 4 It is a schematic diagram of the regression prediction report of the oxygen content test results between GFA test and FTIR test. Detailed Embodiments
[0019] The technical solutions of the present invention will be further elaborated in detail below in conjunction with specific embodiments. For the parts not detailedly recorded and disclosed in the following embodiments of the present invention, they should all be understood as the prior art known or should be known to those skilled in the art, such as how to polish the silicon sample block with a polishing solution.
[0020] A method for processing silicon samples used in the inert gas fusion infrared absorption method. After the silicon sample block is polished, pretreated and surface-etched, it is rinsed and dried to obtain a silicon sample, which specifically includes the following steps:
[0021] Cutting the silicon sample block, cutting the silicon sample block at a specific position of the single crystal sample to be measured so that the silicon sample block meets the size requirements of the inert gas fusion infrared absorption method equipment.
[0022] Polishing the silicon sample block, mixing nitric acid aqueous solution, hydrofluoric acid aqueous solution and glacial acetic acid in a volume ratio of 10 - 9:2 - 3:3 - 4 to obtain a polishing solution, and polishing the silicon sample block with the polishing solution to make the surface of the silicon sample block mirror-like.
[0023] Pretreatment of silicon sample block: Immerse the polished silicon sample block in absolute alcohol for 1 - 2 minutes and then blow it dry.
[0024] Surface corrosion of silicon sample block: The surface corrosion of silicon sample block includes acid corrosion and alkali corrosion. The process of acid corrosion is as follows: A mixed acid corrosion solution is obtained by mixing nitric acid aqueous solution, hydrofluoric acid aqueous solution and glacial acetic acid in a volume ratio of 10 - 9:2 - 3:3 - 4. The mass fraction of nitric acid in the nitric acid aqueous solution is 69 - 70%, and the mass fraction of hydrofluoric acid in the hydrofluoric acid aqueous solution is 40 - 49%. The mixed acid corrosion solution is divided into two parts according to a volume ratio of 4:3 - 4. Place a part of the mixed acid corrosion solution and the silicon sample block in a reactor and react for 8 to 10 minutes until a large number of bubbles start to appear on the liquid surface and more smoke is generated on the liquid surface. Then, add the other part of the mixed acid corrosion solution into the reactor to change the reaction path in the reactor, thereby controlling the reaction rate in the reactor. Stir once per minute during the acid corrosion process. During the reaction between the first - added mixed acid corrosion solution and the silicon sample block, as the reaction proceeds, the reaction between the two becomes more and more intense, generating a large amount of gas and by - products. This by - product covers the surface of the oxide layer, hindering the contact between the mixed acid corrosion solution and the oxide layer, thereby causing uneven surface corrosion of the silicon sample block and incomplete removal of the oxide layer on the surface. Therefore, the secondary addition of the mixed acid corrosion solution can change the reaction path in the reactor, thereby reducing the reaction rate in the reactor. It can not only completely remove the oxide layer, but also make the corrosion more uniform, and at the same time avoid the secondary oxidation of the silicon sample block. After the corrosion is completed, inject pure water into the reactor for rinsing.
[0025] The process of alkali corrosion is as follows: Place the silicon sample block after acid corrosion in a 1.5% - 2% KOH aqueous solution and react for 1 - 2 minutes, then wash it with pure water to further remove the oxide layer on the surface of the silicon sample block and neutralize the mixed acid remaining on the surface of the silicon sample block, avoiding the secondary oxidation caused by the contact of the remaining mixed acid on the sample surface with air.
[0026] Use tetrafluoro tweezers to clamp the corroded silicon sample block into a tetrafluoro blue and place it in an ultrasonic bath for ultrasonic cleaning for 20 - 30 minutes. The rinsed silicon sample block is dried with nitrogen to obtain a silicon sample, and the silicon sample is stored in a box filled with nitrogen.
[0027] Example 1
[0028] A method for treating a silicon sample for inert gas fusion infrared absorption method, specifically including the following steps:
[0029] Cutting of silicon sample block: Cut a silicon sample block at a specific position of the single - crystal sample to be measured so that the silicon sample block meets the size requirements of the inert gas fusion infrared absorption method equipment.
[0030] Polish the silicon sample block. Mix nitric acid aqueous solution, hydrofluoric acid aqueous solution and glacial acetic acid in a volume ratio of 10:3:4 to obtain a polishing solution, and use the polishing solution to polish the silicon sample block to make the surface of the silicon sample block mirror-like.
[0031] Pre-treat the silicon sample block. Immerse the polished silicon sample block in absolute alcohol for 1 - 2 minutes and then blow it dry.
[0032] Corrode the surface of the silicon sample block. The surface corrosion of the silicon sample block includes acid corrosion and alkali corrosion. The process of acid corrosion is as follows: Mix nitric acid aqueous solution, hydrofluoric acid aqueous solution and glacial acetic acid in a volume ratio of 10:3:4 to obtain a mixed acid corrosion solution. The mass fraction of nitric acid in the nitric acid aqueous solution is 69 - 70%; the mass fraction of hydrofluoric acid in the hydrofluoric acid aqueous solution is 40 - 49%; divide the mixed acid corrosion solution into two parts according to a volume ratio of 4:3. Place a part of the mixed acid corrosion solution and the silicon sample block in a reactor and react for 8 to 10 minutes until a large number of bubbles begin to appear on the liquid surface and more smoke is generated on the liquid surface. Then add the other part of the mixed acid corrosion solution into the reactor to change the reaction path in the reactor, thereby controlling the reaction rate in the reactor. Stir once per minute during the acid corrosion process.
[0033] The process of alkali corrosion is as follows: Place the silicon sample block after acid corrosion in a 1.5% KOH aqueous solution and react for 1 - 2 minutes, then wash it with pure water.
[0034] Use Teflon tweezers to clamp the corroded silicon sample block into a Teflon blue and place it in an ultrasonic bath for ultrasonic cleaning for 30 minutes. Blow dry the rinsed silicon sample block with nitrogen to obtain a silicon sample, and store the silicon sample in a box filled with nitrogen.
[0035] Example 2
[0036] A method for treating a silicon sample for inert gas fusion infrared absorption method, specifically including the following steps:
[0037] Cut the silicon sample block. Cut the silicon sample block at a specific position of the single crystal sample to be measured so that the silicon sample block meets the size requirements of the inert gas fusion infrared absorption method equipment.
[0038] Polish the silicon sample block. Mix nitric acid aqueous solution, hydrofluoric acid aqueous solution and glacial acetic acid in a volume ratio of 9:2:3 to obtain a polishing solution, and use the polishing solution to polish the silicon sample block to make the surface of the silicon sample block mirror-like.
[0039] Pre-treat the silicon sample block. Immerse the polished silicon sample block in absolute alcohol for 1 - 2 minutes and then blow it dry.
[0040] The surface of the silicon sample block is corroded. The surface corrosion of the silicon sample block includes acid corrosion and alkali corrosion. The process of acid corrosion is as follows: A mixed acid corrosion solution is obtained by mixing a nitric acid aqueous solution, a hydrofluoric acid aqueous solution, and glacial acetic acid in a volume ratio of 9:2:3. The mass fraction of nitric acid in the nitric acid aqueous solution is 69-70%; the mass fraction of hydrofluoric acid in the hydrofluoric acid aqueous solution is 40-49%; the mixed acid corrosion solution is divided into two parts according to a volume ratio of 4:4. One part of the mixed acid corrosion solution and the silicon sample block are placed in a reactor and reacted for 8 to 10 minutes until a large number of bubbles begin to appear on the liquid surface, and at the same time, more smoke is generated on the liquid surface. Then, the other part of the mixed acid corrosion solution is added to the reactor to change the reaction path in the reactor, thereby controlling the reaction rate in the reactor. During the acid corrosion process, it is stirred once per minute.
[0041] The process of alkali corrosion is as follows: After the silicon sample block corroded by acid is placed in a 2% KOH aqueous solution and reacted for 1-2 minutes, it is washed with pure water.
[0042] The corroded silicon sample block is clamped into a Teflon blue with Teflon forceps and placed in an ultrasonic bath for ultrasonic cleaning for 20 minutes. The rinsed silicon sample block is dried with nitrogen to obtain a silicon sample, and the silicon sample is stored in a box filled with nitrogen.
[0043] Example 3
[0044] A method for treating a silicon sample for the inert gas fusion infrared absorption method, specifically including the following steps:
[0045] Cutting the silicon sample block, a silicon sample block is cut at a specific position of the single crystal sample to be measured so that the silicon sample block meets the size requirements of the inert gas fusion infrared absorption method equipment.
[0046] Polishing the silicon sample block, a polishing solution is obtained by mixing a nitric acid aqueous solution, a hydrofluoric acid aqueous solution, and glacial acetic acid in a volume ratio of 9.5:2.5:3.5. The silicon sample block is polished with the polishing solution to make the surface of the silicon sample block mirror-like.
[0047] Pretreating the silicon sample block, the polished silicon sample block is immersed in absolute ethanol for 1-2 minutes and then dried.
[0048] The surface of the silicon sample block is corroded. The surface corrosion of the silicon sample block includes acid corrosion and alkali corrosion. The process of acid corrosion is as follows: A mixed acid corrosion solution is obtained by mixing a nitric acid aqueous solution, a hydrofluoric acid aqueous solution, and glacial acetic acid in a volume ratio of 9.5:2.5:3.5. The mass fraction of nitric acid in the nitric acid aqueous solution is 69-70%; the mass fraction of hydrofluoric acid in the hydrofluoric acid aqueous solution is 40-49%; the mixed acid corrosion solution is divided into two parts according to a volume ratio of 4:3.5. One part of the mixed acid corrosion solution and the silicon sample block are placed in a reactor and reacted for 8 to 10 minutes until a large number of bubbles begin to appear on the liquid surface, and at the same time, more smoke is generated on the liquid surface. Then, the other part of the mixed acid corrosion solution is added to the reactor to change the reaction path in the reactor, thereby controlling the reaction rate in the reactor. During the acid corrosion process, it is stirred once per minute.
[0049] The process of alkali corrosion is as follows: After the silicon sample block corroded by acid is placed in a 1.5%-2% KOH aqueous solution and reacted for 1-2 minutes, it is washed with pure water.
[0050] The corroded silicon sample block is clamped into a Teflon blue with Teflon forceps and placed in an ultrasonic bath for ultrasonic cleaning for 25 minutes. The rinsed silicon sample block is dried with nitrogen to obtain a silicon sample, and the silicon sample is stored in a box filled with nitrogen.
[0051] <Verification 1>
[0052] Eleven silicon wafers with different oxygen contents to be tested are selected. The eleven silicon wafers are numbered as test piece 1, test piece 2, test piece 3, test piece 4, test piece 5, test piece 6, test piece 7, test piece 8, test piece 9, test piece 10, and test piece 11. The oxygen contents of the eleven test pieces are tested by the infrared test method (FTIR) specified in GB / T 1557. The results are: 9.4 ppma, 15.38 ppma, 16.83 ppma, 16.04 ppma, 14.45 ppma, 10.62 ppma, 14.21 ppma, 12.39 ppma, 10.7 ppma, 9.97 ppma, 8.40 ppma. Sampling is carried out at the center position of each silicon wafer to be tested, and 6 silicon sample blocks of the same size are taken from each silicon wafer to be tested. The silicon sample blocks are divided into 6 groups and numbered as shown in Table 1. After the 6 groups of silicon sample blocks are polished and pretreated, surface corrosion, rinsing, and drying are carried out to obtain silicon samples. The corrosion processes of each group of silicon sample blocks are shown in Table 2 and Table 3, respectively, as follows:
[0053] For the corrosion of the first group of silicon sample blocks, a mixed acid corrosion solution is obtained by mixing a nitric acid aqueous solution, a hydrofluoric acid aqueous solution, and glacial acetic acid in a volume ratio of 10:3:4. The mass fraction of nitric acid in the nitric acid aqueous solution is 69-70%; the mass fraction of hydrofluoric acid in the hydrofluoric acid aqueous solution is 40-49%; the mixed acid corrosion solution and the silicon sample block are placed in a reactor and reacted for 9-10 minutes, and it is stirred once per minute.
[0054] Etching of the second group of silicon specimens. A mixed acid etchant is obtained by mixing nitric acid aqueous solution, hydrofluoric acid aqueous solution and glacial acetic acid in a volume ratio of 10:3:4. The mass fraction of nitric acid in the nitric acid aqueous solution is 69-70%; the mass fraction of hydrofluoric acid in the hydrofluoric acid aqueous solution is 40-49%; the mixed acid etchant and the silicon specimens are placed in a reactor and reacted for 11-12 minutes, with stirring once per minute.
[0055] Etching of the third group of silicon specimens. A mixed acid etchant is obtained by mixing nitric acid aqueous solution, hydrofluoric acid aqueous solution and glacial acetic acid in a volume ratio of 10:3:4. The mass fraction of nitric acid in the nitric acid aqueous solution is 69-70%; the mass fraction of hydrofluoric acid in the hydrofluoric acid aqueous solution is 40-49%; the mixed acid etchant and the silicon specimens are placed in a reactor and reacted for 14-15 minutes, with stirring once per minute.
[0056] Etching of the fourth group of silicon specimens. A mixed acid etchant is obtained by mixing nitric acid aqueous solution, hydrofluoric acid aqueous solution and glacial acetic acid in a volume ratio of 10:3:4. The mass fraction of nitric acid in the nitric acid aqueous solution is 69-70%; the mass fraction of hydrofluoric acid in the hydrofluoric acid aqueous solution is 40-49%; the mixed acid etchant is divided into two parts by a volume ratio of 1:1. After reacting a part of the mixed acid etchant and the silicon specimens in a reactor for 5-6 minutes, the other part of the mixed acid etchant is added to the reactor and reacted for 5-6 minutes, with stirring once per minute.
[0057] Etching of the fifth group of silicon specimens. A mixed acid etchant is obtained by mixing nitric acid aqueous solution, hydrofluoric acid aqueous solution and glacial acetic acid in a volume ratio of 10:3:4. The mass fraction of nitric acid in the nitric acid aqueous solution is 69-70%; the mass fraction of hydrofluoric acid in the hydrofluoric acid aqueous solution is 40-49%; the mixed acid etchant is divided into two parts by a volume ratio of 1:1. After reacting a part of the mixed acid etchant and the silicon specimens in a reactor for 9-10 minutes, the other part of the mixed acid etchant is added to the reactor and reacted for 5-6 minutes, with stirring once per minute.
[0059] Table 1 Numbers of 6 groups of silicon specimens
[0060] Table 2 Surface etching processes of the first group, the second group and the third group of silicon specimens
[0061] Table 3 Surface etching processes of the fourth group, the fifth group and the sixth group of silicon specimens
[0062] The oxygen content of each group of silicon samples is measured by inert gas fusion-infrared absorption method (hereinafter referred to as GFA), and the results are shown in Table 4 and Table 5.
[0063] Table 4 Test results of silicon samples in groups 1, 2 and 3
[0064] Table 5 Test results of silicon samples in groups 4, 5 and 6
[0065] Analysis of results: The first group of silicon samples were reacted with mixed acid etching solution for 10 minutes, and the deviation between GFA test and FTIR was within 2.89ppma. The second group of silicon samples were reacted with mixed acid etching solution for 12 minutes, and the deviation between GFA test and FTIR was within 1.96ppma. The third group of silicon samples were corroded with mixed acid etching solution for 15 minutes, and the deviation between GFA and FTIR was 3.55ppma. As time goes by, the reaction in the reactor is too violent, the violent reaction causes an increase in bubbles, and the surface of the silicon samples comes into contact with the air, causing secondary oxidation.
[0066] After the silicon samples of the fourth group were corroded with mixed acid solution for 6 minutes, the same volume of mixed acid solution was added and corroded for another 5 minutes. The deviation between GFA and FTIR was within 4.39ppma. After the silicon samples of the fifth group were corroded with mixed acid solution for 10 minutes, the same volume of mixed acid solution was added and corroded for another 5 minutes. The deviation between GFA and FTIR was within 1.66ppma. After the silicon samples of the sixth group were corroded with mixed acid solution for 10 minutes, the same volume of mixed acid solution was added and corroded for another 5 minutes, and then washed with 1.5% KOH for 2 minutes. The deviation between GFA and FTIR was within 0.57ppma. This shows that the addition of mixed acid solution in batches combined with alkaline corrosion can completely remove the silicon samples to avoid the oxide layer and improve the accuracy of the test results. The GFA test results of the sixth group are perfectly positively correlated with the FTIR test results, with a correlation coefficient of R: 0.99. The specific data analysis is as follows: Figure 1 , Figure 2 , Figure 3 and Figure 4 shown.
[0067] <Verification 2>
[0068] Select 11 silicon wafers to be tested with different oxygen contents. The 11 silicon wafers are numbered as Test Wafer 12, Test Wafer 13, Test Wafer 14, Test Wafer 15, Test Wafer 16, Test Wafer 17, Test Wafer 18, Test Wafer 19, Test Wafer 20, Test Wafer 21 and Test Wafer 22. Use the infrared test method (FTIR) specified in GB / T 1557 to test the oxygen contents of the 11 wafers to be tested. The results are: 8.4 ppma, 17.73 ppma, 16.13 ppma, 15.38 ppma, 14.89 ppma, 13.78 ppma, 12.78 ppma, 12.68 ppma, 11.75 ppma, 9.56 ppma and 8.12 ppma. Take samples at the central position of each silicon wafer to be tested, and take out 2 silicon sample blocks of the same size from each silicon wafer to be tested. The silicon sample blocks are divided into 2 groups for numbering, as shown in Table 6 specifically. After polishing and pre-treating the 2 groups of silicon sample blocks, perform surface corrosion, rinsing and drying to obtain silicon samples.
[0069] Table 6 Numbering of 2 groups of silicon sample blocks
[0070] The surface corrosion process of the silicon sample blocks in the 7th group and the 8th group is the same as that of the silicon sample blocks in the 6th group. Perform GFA tests on the silicon samples obtained from the 7th group and the 8th group. The results are shown in Table 7.
[0071] Table 7 Test results of the silicon samples in the 7th group and the 8th group
[0072] From the above results, it can be seen that adding the mixed acid etching solution in batches and combining it with alkali etching can completely remove the silicon sample blocks to avoid the oxide layer, improve the accuracy of the test results, and make the deviation of the GFA test results from the true oxygen content value stable within 1 ppma.
[0073] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be obvious to those skilled in the art. The general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to these embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.
Claims
1. A method for treating silicon samples used in the inert gas fusion-infrared absorption method. After the silicon sample blocks are polished, pretreated, and surface-etched, they are rinsed and dried to obtain silicon samples, which is characterized in that: The surface corrosion of the silicon sample block includes acid corrosion and alkali corrosion. The process of acid corrosion is as follows: A mixed acid corrosion solution is obtained by mixing a nitric acid aqueous solution, a hydrofluoric acid aqueous solution, and glacial acetic acid in a volume ratio of 10 - 9:2 - 3:3 - 4. The mixed acid corrosion solution is divided into two parts according to a volume ratio of 4:3 - 4. One part of the mixed acid corrosion solution and the silicon sample block are placed in a reactor and reacted for 8 to 10 minutes until a large number of bubbles begin to appear on the liquid surface, and at the same time, more smoke is generated on the liquid surface. Then, the other part of the mixed acid corrosion solution is added to the reactor to change the reaction path in the reactor, thereby controlling the reaction rate in the reactor.
2. The processing method of silicon sample for inert gas fusion-infrared absorption method according to claim 1, characterized in that: A mixed acid corrosion solution is obtained by mixing a nitric acid aqueous solution, a hydrofluoric acid aqueous solution, and glacial acetic acid in a volume ratio of 10:3:
4.
3. The processing method of silicon sample for inert gas fusion-infrared absorption method according to claim 1, characterized in that: The mixed acid corrosion solution is divided into two parts according to a volume ratio of 4:
4.
4. The processing method of silicon sample for inert gas fusion-infrared absorption method according to claim 1, characterized in that: The mass fraction of nitric acid in the nitric acid aqueous solution is 69 - 70%.
5. The treatment method of silicon sample for inert gas fusion-infrared absorption method according to claim 1, characterized in that: The mass fraction of hydrofluoric acid in the hydrofluoric acid aqueous solution is 40 - 49%.
6. The processing method of silicon sample for inert gas fusion-infrared absorption method according to claim 1, characterized in that: The process of alkali corrosion is as follows: After the acid - corroded silicon sample block is placed in a 1.5% - 2% KOH aqueous solution and reacted for 1 - 2 minutes, it is washed with pure water.
7. The processing method of silicon sample for inert gas fusion-infrared absorption method according to claim 1, characterized in that: The process of polishing the silicon sample block is as follows: A polishing solution is obtained by mixing a nitric acid aqueous solution, a hydrofluoric acid aqueous solution, and glacial acetic acid in a volume ratio of 10 - 9:2 - 3:3 - 4. The silicon sample block is polished with the polishing solution.
8. The processing method of silicon sample for inert gas fusion-infrared absorption method according to claim 1, characterized in that: The pretreatment process of the silicon sample block is as follows: The polished silicon sample block is soaked in absolute alcohol for 1 - 2 minutes and then dried.
9. The treatment method of silicon sample for inert gas fusion-infrared absorption method according to claim 1, characterized in that: The corroded silicon sample block is ultrasonically cleaned for 20 - 30 minutes.
10. The processing method of silicon sample for inert gas fusion-infrared absorption method according to claim 1, characterized in that: The rinsed silicon sample block is dried with nitrogen.