Method for verifying test precision of machine by adopting reverse pollution

Abstract

The invention relates to a method for verifying the test precision of a machine by adopting reverse pollution, which belongs to the technical field of machine precision detection, and comprises the following operation steps: 1, adopting a VPD machine to generate HF steam to carry out meteorological corrosion on the surface of a silicon wafer; and 2, scanning and collecting metal stains on the surface of the silicon wafer by a scanning head of the VPD machine, and then drying the silicon wafer on the VPD machine. And 3, placing the silicon wafer subjected to surface cleaning on a ceramic heating plate. And 4, uniformly dripping the standard solution on the surface of the silicon wafer. And 5, drying the solution at low temperature. And 6, testing the reverse pollution solution collected by VPD by using ICP-MS. The mixed corrosive liquid prepared by the VPD machine table is used for removing metal impurities and oxide films on the surface of a sample, so that the cleanliness of an experimental silicon wafer is ensured, the influence of external metal pollution is eliminated, the whole process of recovering and testing the corrosive liquid is automatically completed by the machine table, and the precision and accuracy of test data are ensured.

Description

Technical Field

[0001] The present invention relates to the technical field of machine accuracy detection, and in particular to a method for verifying machine test accuracy by using reverse contamination. Background Art

[0002] At present, the size of integrated circuit devices is shrinking, and the degree of integration is becoming higher and higher. Any tiny process defect will cause the integrated circuit to fail, so the requirements for the development and management of production and processing technology and various process parameters of raw materials are becoming higher and higher. Silicon wafers are one of the important raw materials in the manufacturing process of integrated circuits. Metal impurities in silicon wafers will affect the performance and reliability of devices, and have a significant impact on the yield of components and the performance of integrated circuits. Therefore, the control of various metal impurities in silicon wafers is extremely strict, and various institutions have always attached great importance to the detection of metal elements in the production and processing of silicon wafers.

[0003] Metal elements are commonly found in the silicon wafer processing process, and the study of the chemical behavior of various metal elements in silicon wafers has always been a key topic of concern for relevant scholars and experts. Alkali metals and alkaline earth metals (Li.Na.K.Ca.Mg.) and other transition metals and heavy metals (Fe, Cr, Ni, Cu,) pollution can shorten the life of components or increase the current during operation, leading to device failure.

[0004] Therefore, the importance of detection is becoming increasingly prominent. Semiconductor material detection is a technology that analyzes and tests the characteristic parameters of semiconductor materials. Due to the wide variety of materials, complex processing technology, various forms, and high technical difficulty in the production process, we need to accurately measure the characteristic parameters of semiconductor materials, truly reflect the quality situation, and master the generation process of its key parameters, so as to guide the update and iteration of R&D technology. 50% of the yield loss in the semiconductor industry is caused by cleaning reagents and trace element contamination inside the material. Therefore, it is extremely important to accurately detect the content of each element, and it puts forward higher requirements for pollution control of the operating environment and operators. Summary of the invention

[0005] The present invention mainly solves the deficiencies in the prior art and provides a method for verifying the test accuracy of a machine by using reverse contamination. The method uses a mixed etching solution configured by a VPD machine to remove metal impurities and oxide films on the surface of the sample, thereby ensuring the cleanliness of the experimental silicon wafer and removing the influence of exogenous metal contamination. The recovery and testing of the etching solution are also automatically completed by the machine throughout the process, thereby ensuring the precision and accuracy of the test data.

[0006] The above technical problems of the present invention are mainly solved by the following technical solutions: A method for verifying the test accuracy of a machine by using reverse contamination, wherein the equipment and tools used include an element detection machine, a vacuum suction pen, a ceramic heating plate, a VPD machine, a corrosion solution and a 20ppt reverse contamination standard solution.

[0007] The verification method includes the following steps: Step 1: Clean the surface of the silicon wafer and use a VPD machine to generate HF vapor to perform meteorological corrosion on the surface of the silicon wafer, changing the surface of the silicon wafer from hydrophilic to hydrophobic.

[0008] Step 2: The VPD machine scanning head then scans and collects metal contamination on the surface of the silicon wafer. The scanning head needs to scan and collect metal impurities on the entire surface of the silicon wafer. After completing the collection of metal impurities, the etching liquid is properly discarded, and then the silicon wafer is dried on the VPD machine.

[0009] Step 3: Place the cleaned silicon wafer on the ceramic heating plate and use a vacuum pen to transfer it. Be careful not to let foreign matter touch the cleaned surface of the silicon wafer during the transfer process.

[0010] Step 4: Use a pipette to absorb 20ppt standard solution, the total volume absorbed is 1ml, and then drop the standard solution evenly on the surface of the silicon wafer. The droplets should be as small as possible, the number of droplets should be as large as possible, and they should be evenly dropped on the entire surface of the silicon wafer.

[0011] Step 5: When the solution is dried at low temperature, the temperature of the heating plate is set to 25 degrees Celsius. The temperature of the hot plate should be uniform to avoid excessive local temperature differences on the silicon wafer.

[0012] Step 6: Use ICP-MS to test the back-contaminated solution collected by VPD.

[0013] Preferably, the element detection machine ICP-MS model is ICP-MS-8900, and its detection accuracy should be at the ppt level. The instrument status should be confirmed before using the machine, the calibration curve linearity should be above 0.995, and blank samples should be tested in advance to confirm that the machine is not contaminated.

[0014] As a preferred choice, the ceramic heating plate and the VPD machine use IAS Expert. The etching liquid is mainly made of high-purity HF and H2O2 in a certain ratio. The configuration is automatically completed by the VPD machine to reduce unnecessary pollution caused by corresponding human factors.

[0015] Preferably, the HF used requires that the metal element is ≤10ppt, and the H2O2 used requires that the metal element impurities are ≤10ppt; the H2O2 used to prepare the etching solution is 35% concentration hydrogen peroxide produced by Domo Chemical.

[0016] Preferably, in order to reduce the influence of external metal impurities on the detection precision and accuracy, the water used in the detection process is ultrapure water with a resistivity of ≥18MΩ.cm.

[0017] Preferably, after the solution is dried at low temperature, when no droplets are visible on the surface of the silicon wafer, the silicon wafer is transferred to a wafer box with a vacuum pen, and the metal on the surface is collected by VPD. The VPD operation process is automatically performed by the machine without human operation throughout the process, ensuring the cleanliness of the metal collection process.

[0018] Preferably, inductively coupled plasma mass spectrometry, i.e., ICP-MS, is used. The testing principle of ICP-MS is to ionize the elements in the sample through a high-temperature plasma heat source, and analyze and detect the elements to be tested by a mass spectrometer after sorting; the sample to be tested is appropriately pretreated into a liquid, and the sample to be tested is brought into a high-frequency radio frequency signal in the form of an aerosol of an aqueous solution through an argon gas flow to realize the ionization of the elements in the inductive coil plasma source.

[0019] Preferably, after the elements in the sample are ionized into monovalent positive ions, they are screened and analyzed and compared multiple times by the mass spectrometer, and the content of the element to be tested and its isotope ratio can be obtained by counting and calculation; by testing with mixed standard solutions, ICP-MS can achieve simultaneous testing of multiple elements and simultaneous analysis of multiple element test results in a single test of the same sample; at the same time, the element sorting and screening analysis processes of the ICP-MS test are completed in a closed environment, and the data has high repeatability and accuracy.

[0020] The present invention can achieve the following effects: The present invention provides a method for verifying the test accuracy of a machine by using reverse contamination. Compared with the prior art, the mixed etching solution configured by the VPD machine is used to remove metal impurities and oxide films on the surface of the sample, thereby ensuring the cleanliness of the experimental silicon wafer and removing the influence of exogenous metal contamination. The recovery and testing of the etching solution are also automatically completed by the machine throughout the process, thereby ensuring the precision and accuracy of the test data. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a process flow chart of the present invention. DETAILED DESCRIPTION

[0022] The technical solution of the invention is further specifically described below through embodiments and in conjunction with the accompanying drawings.

[0023] Example: Figure 1 As shown, a method of using reverse contamination to verify the test accuracy of a machine is shown. The equipment and tools used include an element detection machine, a vacuum suction pen, a ceramic heating plate, a VPD machine, a corrosion solution and a 20ppt reverse contamination standard solution.

[0024] The element detection machine ICP-MS machine model is ICP-MS-8900, and its detection accuracy must be at the ppt level. The instrument status must be confirmed before using the machine, and the calibration curve linearity must be above 0.995. A blank sample must be tested in advance to confirm that the machine is not contaminated.

[0025] Ceramic heating plate, VPD machine uses IAS Expert, the etching liquid is mainly made of high-purity HF and H2O2 in a certain ratio, and its configuration is automatically completed by the VPD machine to reduce unnecessary pollution caused by corresponding human factors. The HF used requires metal elements ≤10ppt, and the H2O2 used requires metal element impurities ≤10ppt; the H2O2 used to configure the etching liquid is 35% concentration of hydrogen peroxide from Tama Chemical. In order to reduce the impact of external metal impurities on the detection precision and accuracy, the water used in the detection process is ultrapure water with a resistivity of ≥18MΩ.cm.

[0026] The verification method includes the following steps: Step 1: Clean the surface of the silicon wafer and use a VPD machine to generate HF vapor to perform meteorological corrosion on the surface of the silicon wafer, changing the surface of the silicon wafer from hydrophilic to hydrophobic.

[0027] Step 2: The VPD machine scanning head then scans and collects metal contamination on the surface of the silicon wafer. The scanning head needs to scan and collect metal impurities on the entire surface of the silicon wafer. After completing the collection of metal impurities, the etching liquid is properly discarded, and then the silicon wafer is dried on the VPD machine.

[0028] Step 3: Place the silicon wafer with cleaned surface on the ceramic heating plate. Use a vacuum pen to transfer it. Be careful not to let foreign matter touch the cleaned surface of the silicon wafer during the transfer process.

[0029] Step 4: Use a pipette to absorb 20ppt standard solution, the total volume absorbed is 1ml, and then drop the standard solution evenly on the surface of the silicon wafer. The droplets should be as small as possible, the number of droplets should be as large as possible, and they should be evenly dropped on the entire surface of the silicon wafer.

[0030] Step 5: When the solution is dried at low temperature, the temperature of the heating plate is set to 25 degrees Celsius. The temperature of the hot plate should be uniform to avoid excessive local temperature differences on the silicon wafer.

[0031] After the solution is dried at low temperature, when the droplets on the surface of the silicon wafer are no longer visible, the silicon wafer is transferred to a wafer box with a vacuum suction pen, and the metal on the surface is collected using VPD. The VPD operation process is automatically performed by the machine, without any human operation, to ensure the cleanliness of the metal collection process.

[0032] Step 6: Use ICP-MS to test the back-contaminated solution collected by VPD.

[0033] ICP-MS stands for Inductively Coupled Plasma Mass Spectrometry.

[0034] Inductively coupled plasma mass spectrometry is abbreviated as ICP-MS. The testing principle of ICP-MS is to ionize the elements in the sample through a high-temperature plasma heat source, and use a mass spectrometer to analyze and detect the elements after sorting; the sample to be tested is properly pretreated into a liquid, and the sample to be tested is brought into the high-frequency radio frequency signal in the form of an aerosol of an aqueous solution through an argon flow to achieve ionization of the elements in the inductive coil plasma source.

[0035] After the elements in the sample are ionized into monovalent positive ions, they are screened and analyzed and compared multiple times by the mass spectrometer. The content of the element to be tested and its isotope ratio can be obtained through counting and calculation. Through the detection of mixed standard solutions, ICP-MS can realize the simultaneous testing of multiple elements and the simultaneous analysis of multiple element detection results in a single detection of the same sample. At the same time, the element sorting and screening analysis processes of ICP-MS tests are completed in a closed environment, and the data has high repeatability and accuracy.

[0036] In summary, the method of using reverse contamination to verify the test accuracy of the machine uses the mixed etching solution configured by the VPD machine to remove metal impurities and oxide films on the surface of the sample, ensuring the cleanliness of the experimental silicon wafer and removing the influence of exogenous metal contamination. The recovery and testing of the etching solution are also automatically completed by the machine, ensuring the precision and accuracy of the test data.

[0037] The above description is only a specific embodiment of the present invention, but the structural features of the present invention are not limited thereto. Any changes or modifications made by any technician in the field of the present invention are included in the patent scope of the present invention.

Claims

1. A method for verifying the test accuracy of a machine using reverse contamination, characterized in that: The equipment and tools used include element detection machine, vacuum suction pen, ceramic heating plate, VPD machine, etching solution and 20ppt reverse contamination standard solution; The verification method includes the following steps: Step 1: Clean the surface of the silicon wafer and use the VPD machine to generate HF vapor to perform meteorological corrosion on the surface of the silicon wafer, so that the surface of the silicon wafer changes from hydrophilic to hydrophobic; Step 2: The VPD machine scanning head then scans and collects metal contamination on the surface of the silicon wafer. The scanning head needs to scan and collect metal impurities on the entire surface of the silicon wafer. After the metal impurities are collected, the etching liquid is properly scrapped, and then the silicon wafer is dried on the VPD machine; Step 3: Place the cleaned silicon wafer on the ceramic heating plate. Use a vacuum pen to transfer the wafer. Be careful not to let foreign matter touch the cleaned surface of the wafer. Step 4: Use a pipette to absorb 20ppt standard solution, the total volume absorbed is 1ml, and then drop the standard solution evenly on the surface of the silicon wafer. The droplets should be as small as possible, the number of droplets should be as large as possible, and they should be evenly dropped on the entire surface of the silicon wafer; Step 5: When the solution is dried at low temperature, the temperature of the heating plate is set to 25 degrees Celsius. The temperature of the hot plate should be uniform to avoid excessive temperature differences in the silicon wafer. Step 6: Use ICP-MS to test the back-contaminated solution collected by VPD.

2. The method for verifying the test accuracy of a machine by using reverse contamination according to claim 1, characterized in that: The element detection machine ICP-MS machine model is ICP-MS-8900, and its detection accuracy must be at the ppt level. The instrument status must be confirmed before using the machine, and the calibration curve linearity must be above 0.

995. A blank sample must be tested in advance to confirm that the machine is not contaminated.

3. The method for verifying the test accuracy of a machine by using reverse contamination according to claim 1, characterized in that: Ceramic heating plate, VPD machine uses IAS Expert, the etching liquid is mainly made of high-purity HF and H2O2 in a certain ratio, and its configuration is automatically completed by the VPD machine to reduce unnecessary pollution caused by corresponding human factors.

4. The method for verifying the test accuracy of a machine by using reverse contamination according to claim 3, characterized in that: The HF used requires that the metal element is ≤10ppt, and the H2O2 used requires that the metal element impurities are ≤10ppt; the H2O2 used to prepare the etching solution is 35% concentration hydrogen peroxide produced by Domo Chemical.

5. The method for verifying the test accuracy of a machine by using reverse contamination according to claim 3, characterized in that: In order to reduce the impact of external metal impurities on detection precision and accuracy, the water used in the detection process is ultrapure water with a resistivity of ≥18MΩ.cm.

6. The method for verifying the test accuracy of a machine by using reverse contamination according to claim 1, characterized in that: After the solution is dried at low temperature, when the droplets on the surface of the silicon wafer are no longer visible, the silicon wafer is transferred to a wafer box with a vacuum suction pen, and the metal on the surface is collected using VPD. The VPD operation process is automatically performed by the machine, without any human operation, to ensure the cleanliness of the metal collection process.

7. The method for verifying the test accuracy of a machine by using reverse contamination according to claim 1, characterized in that: Inductively coupled plasma mass spectrometry is ICP-MS. The testing principle of ICP-MS is to ionize the elements in the sample through a high-temperature plasma heat source, and use a mass spectrometer to analyze and detect the elements after sorting; the sample to be tested is properly pretreated into a liquid, and the sample to be tested is brought into the high-frequency radio frequency signal in the form of an aerosol of an aqueous solution through an argon flow to achieve ionization of the elements in the inductive coil plasma source.

8. The method for verifying the test accuracy of a machine by using reverse contamination according to claim 7, characterized in that: After the elements in the sample are ionized into monovalent positive ions, they are screened and analyzed and compared multiple times by the mass spectrometer. The content of the element to be tested and its isotope ratio can be obtained through counting and calculation. Through the detection of mixed standard solutions, ICP-MS can realize the simultaneous testing of multiple elements and the simultaneous analysis of multiple element detection results in a single detection of the same sample. At the same time, the element sorting and screening analysis processes of ICP-MS tests are completed in a closed environment, and the data has high repeatability and accuracy.

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