Method for distinguishing surface OISF and in-vivo OISF of silicon wafer

Abstract

The invention relates to a method for distinguishing surface OISF and in-vivo OISF of a silicon wafer, which belongs to the technical field of silicon wafer detection and comprises the following operation steps of: 1, cleaning and pretreating the silicon wafer; and 2, annealing under nitrogen. And 3, carrying out heat treatment in a wet oxygen environment to form the OISF. And 4, carrying out first corrosion treatment on the silicon wafer after heat treatment. And 5, detecting the corroded silicon wafer by using an optical microscope, and observing and recording the distribution position and density of the OISF on the surface of the silicon wafer. And 6, carrying out second corrosion treatment. And 7, detecting the corroded silicon wafer by using an optical microscope, and observing and recording the distribution position and density of the OISF on the surface of the silicon wafer. And 8, evaluating the quality of the silicon wafer according to the two OISF detection results. The method has the advantages of simplicity in operation and reliable detection performance, and solves the problem of judging whether the OISF is generated in a single crystal growth process or introduced in a processing process.

Description

Technical Field

[0001] The present invention relates to the technical field of silicon wafer detection, and in particular to a method for distinguishing OISF on the surface of a silicon wafer and OISF in a body. Background Art

[0002] Thermal oxidation of silicon wafers often causes the formation of stacking faults (OISF, oxidation stacking faults) in the surface area of ​​the silicon wafer. The periodic and mutually parallel stacking layers in the crystal structure have a fixed order; if the stacking layers deviate from the original inherent order and the periodicity changes, it is considered that a stacking fault has occurred.

[0003] During thermal oxidation, interstitial atoms are generated at the silicon dioxide interface. These interstitial atoms diffuse to the tensile stress or lattice defects (nucleation centers) to form OISF and grow. Oxidation-induced stacking faults (OISFs) form recombination-generation centers and scattering centers for carriers, and may also cause leakage channels, other defect nucleation centers and other undesirable phenomena, which have a great impact on the performance of semiconductor devices.

[0004] In semiconductor manufacturing, the quality of silicon wafers directly affects the performance and reliability of devices. OISF, as a common defect in silicon wafers, has a significant impact on the electrical performance and stability of devices. However, conventional OISF detection technology cannot effectively distinguish between surface OISF and internal OISF, nor can it accurately determine whether OISF is caused by problems in the single crystal growth process or introduced during the processing process. Therefore, a detection method that can accurately distinguish between these two types of OISF is urgently needed. Summary of the invention

[0005] The present invention mainly solves the deficiencies in the prior art and provides a method for distinguishing OISF on the surface of a silicon wafer from OISF in the body. The method has the advantages of simple operation and reliable detection performance, and solves the problem of judging whether OISF is generated during the growth of a single crystal or introduced during the processing. The method is easy to implement in the manufacturing process, which helps to improve the quality of silicon wafers and the performance of devices. It provides strong support for optimizing the manufacturing process.

[0006] The above technical problems of the present invention are mainly solved by the following technical solutions: A method for distinguishing OISF on a silicon wafer surface and OISF in vivo, comprising the following steps: Step 1: Select the silicon wafer to be tested, clean and pre-treat it, and remove pollutants and impurities on the surface of the silicon wafer.

[0007] Step 2: Place the pre-treated silicon wafer in a heat treatment device and anneal it under nitrogen to form a DZ area near the surface of the silicon wafer. The formation of the DZ area helps to distinguish between surface OISF and in-body OISF.

[0008] Step 3: Place the annealed silicon wafer in a heat treatment device and perform heat treatment in a wet oxygen environment to form an OISF.

[0009] Step 4: The heat-treated silicon wafer is subjected to the first etching treatment to remove the oxide layer on the surface of the silicon wafer and expose the potential OISF.

[0010] Step 5: Use an optical microscope to inspect the silicon wafer after etching, and observe and record the distribution position and density of OISF on the surface of the silicon wafer. The OISF observed at this time is the OISF formed on the surface.

[0011] Step 6: Perform a second corrosion treatment.

[0012] Step 7: Use an optical microscope to inspect the silicon wafer after corrosion treatment, observe and record the distribution position and density of OISF on the surface of the silicon wafer. The increased OISF at this time is the in-vivo OISF.

[0013] Step 8: Evaluate the quality of the silicon wafer based on the two OISF test results.

[0014] Preferably, a cleaning solution is prepared by mixing ethanol, acetone, sodium silicate and deionized water to clean the silicon wafer; the mass percentage concentration of ethanol is 5-6%, the mass percentage concentration of acetone is 8-10%, the mass percentage concentration of sodium silicate is 4-6%, and the balance is deionized water.

[0015] Preferably, the temperature of the silicon wafer cleaning solution is 44-52° C., and the silicon wafer washing time is 9-13 minutes.

[0016] Preferably, when annealing is performed under nitrogen, the annealing is performed at a temperature of 780° C. for 3 hours, and then the annealing is performed at a temperature of 1000° C. for 16 hours.

[0017] Preferably, the heat treatment temperature is 1100° C. and the time is 2 hours.

[0018] Preferably, the first corrosion treatment uses corrosion liquid immersion for 3 minutes, and the corrosion amount does not exceed the depth of the DZ layer; the second corrosion treatment uses corrosion liquid immersion for 10 minutes, so that the corrosion amount exceeds the depth of the DZ layer and reaches the internal defect layer; the DZ layer depth reference is 5um.

[0019] Preferably, for silicon wafers with more OISF on the surface, the number of OISF is reduced by optimizing the processing process; for silicon wafers with more OISF in the body, the number of OISF is controlled by improving the single crystal growth process.

[0020] The present invention can achieve the following effects: The present invention provides a method for distinguishing OISF on the surface of silicon wafers and OISF in the body, which solves the problem of judging whether OISF is generated during the growth of single crystals or introduced during the processing. It is easy to implement in the manufacturing process, which helps to improve the quality of silicon wafers and the performance of devices. It provides strong support for optimizing the manufacturing process. DETAILED DESCRIPTION

[0021] The technical solution of the invention is further specifically described below through embodiments.

[0022] Embodiment: A method for distinguishing OISF on a silicon wafer surface from OISF in vivo comprises the following steps: Step 1: Select the silicon wafer to be tested and perform cleaning and pretreatment.

[0023] The silicon wafer is cleaned by mixing ethanol, acetone, sodium silicate and deionized water to prepare a cleaning solution; the mass percentage concentration of ethanol is 5.5%, the mass percentage concentration of acetone is 9%, the mass percentage concentration of sodium silicate is 5%, and the balance is deionized water. When washing the silicon wafer, the temperature of the silicon wafer cleaning solution is 48°C, and the washing time of the silicon wafer is 11 minutes.

[0024] Step 2: Place the pre-treated silicon wafer in a heat treatment device and anneal it under nitrogen to form a DZ zone near the surface of the silicon wafer. When annealing under nitrogen, anneal at 780°C for 3 hours and then anneal at 1000°C for 16 hours.

[0025] Step 3: Place the annealed silicon wafer in a heat treatment device and perform heat treatment in a wet oxygen environment to form OISF. The heat treatment temperature is 1100°C and the time is 2 hours.

[0026] Step 4: The heat-treated silicon wafer is subjected to the first etching treatment to remove the oxide layer on the surface of the silicon wafer and expose the potential OISF. The first etching treatment uses the etching solution to immerse for 3 minutes, and the etching amount does not exceed the depth of the DZ layer, and the DZ layer depth benchmark is 5um.

[0027] Step 5: Use an optical microscope to inspect the silicon wafer after corrosion treatment, and observe and record the distribution position and density of OISF on the surface of the silicon wafer.

[0028] Step 6: Carry out the second corrosion treatment. The second corrosion treatment uses the corrosion liquid to immerse for 10 minutes, so that the corrosion amount exceeds the depth of the DZ layer and reaches the defect layer in the body. The depth of the DZ layer is 5um.

[0029] Step 7: Use an optical microscope to inspect the silicon wafer after corrosion treatment, and observe and record the distribution position and density of OISF on the surface of the silicon wafer.

[0030] Step 8: Evaluate the quality of silicon wafers based on the results of the two OISF tests. For silicon wafers with more surface OISF, reduce their number by optimizing the processing process; for silicon wafers with more internal OISF, control their number by improving the single crystal growth process.

[0031] In summary, this method for distinguishing OISF on the surface of silicon wafers from OISF in the body has the advantages of simple operation and reliable detection performance, and solves the problem of judging whether OISF is generated during the growth of single crystals or introduced during the processing. It is easy to implement in the manufacturing process, which helps to improve the quality of silicon wafers and the performance of devices. It provides strong support for optimizing the manufacturing process.

[0032] 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 distinguishing OISF on a silicon wafer surface from OISF in vivo, characterized in that The steps are as follows: Step 1: Select the silicon wafer to be tested, and perform cleaning and pretreatment; Step 2: Place the pre-treated silicon wafer in a heat treatment device and anneal it under nitrogen, thereby forming a DZ zone near the surface of the silicon wafer; Step 3: Place the annealed silicon wafer in a heat treatment device and perform heat treatment in a wet oxygen environment to form an OISF; Step 4: The heat-treated silicon wafer is subjected to the first etching treatment to remove the oxide layer on the surface of the silicon wafer and expose the potential OISF; Step 5: Use an optical microscope to inspect the silicon wafer after corrosion treatment, and observe and record the distribution position and density of OISF on the surface of the silicon wafer; Step 6: Perform the second corrosion treatment; Step 7: Use an optical microscope to inspect the silicon wafer after corrosion treatment, and observe and record the distribution position and density of OISF on the surface of the silicon wafer; Step 8: Evaluate the quality of the silicon wafer based on the two OISF test results.

2. The method for distinguishing OISF on a silicon wafer surface from OISF in vivo according to claim 1, characterized in that: A cleaning solution is prepared by mixing ethanol, acetone, sodium silicate and deionized water to clean silicon wafers; the mass percentage concentration of ethanol is 5-6%, the mass percentage concentration of acetone is 8-10%, the mass percentage concentration of sodium silicate is 4-6%, and the balance is deionized water.

3. The method for distinguishing OISF on a silicon wafer surface from OISF in vivo according to claim 2, characterized in that: When washing silicon wafers, the temperature of the silicon wafer cleaning solution is 44 to 52°C, and the time for washing the silicon wafers is 9 to 13 minutes.

4. The method of distinguishing OISF on a silicon wafer surface from OISF in vivo according to claim 1, characterized in that: When annealing is performed under nitrogen, the annealing is performed at a temperature of 780° C. for 3 hours and then at a temperature of 1000° C. for 16 hours.

5. The method for distinguishing OISF on a silicon wafer surface from OISF in vivo according to claim 1, characterized in that: The heat treatment temperature was 1100° C. and the time was 2 hours.

6. The method of distinguishing OISF on a silicon wafer surface from OISF in vivo according to claim 1, characterized in that: The first corrosion treatment uses the corrosion liquid to immerse for 3 minutes, and the corrosion amount does not exceed the depth of the DZ layer; the second corrosion treatment uses the corrosion liquid to immerse for 10 minutes, so that the corrosion amount exceeds the depth of the DZ layer and reaches the defective layer in the body; the DZ layer depth reference is 5um.

7. The method of distinguishing OISF on a silicon wafer surface from OISF in vivo according to claim 1, characterized in that: For silicon wafers with more surface OISF, the number can be reduced by optimizing the processing process; For silicon wafers with more OISF in the body, the number can be controlled by improving the single crystal growth process.