Method for distinguishing between surface oisf and bulk oisf of a silicon wafer

Abstract

The present application relates to a kind of methods for distinguishing the surface OISF and the bulk OISF of silicon wafer, the technical field of the silicon wafer detection, comprising the following operating steps: first, the silicon wafer is washed and pretreated.Second, annealing is carried out under nitrogen.Third, heat treatment is carried out in wet oxygen environment, and OISF is formed.Fourth, the silicon wafer after heat treatment is subjected to first etching treatment.Fifth, optical microscope is used to detect the silicon wafer after etching treatment, and the distribution position and density of OISF on the surface of silicon wafer are observed and recorded.Sixth, second etching treatment is carried out.Seven, optical microscope is used to detect the silicon wafer after etching treatment, and the distribution position and density of OISF on the surface of silicon wafer are observed and recorded.Eighth, according to the detection result of twice OISF, the quality of silicon wafer is evaluated.The present application has the advantages of simple operation and reliable detection performance, and solves the problem of judging whether OISF is generated in single crystal growth process or introduced in processing process.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of silicon wafer detection, and particularly relates to a method for distinguishing surface OISF and internal OISF of a silicon wafer. BACKGROUND

[0002] Thermal oxidation of a silicon wafer often causes the formation of stacking faults (OISF, oxidation-induced stacking faults) in the surface region of the silicon wafer. In a crystal structure, periodic stacking layers parallel to each other have a fixed order; if the stacking layers deviate from the original inherent order and change periodically, it is considered that stacking faults are generated.

[0003] During thermal oxidation, interstitial atoms are generated at the silicon dioxide interface, and these interstitial atoms diffuse to tensile stress or lattice defects (nucleation centers) to form and grow OISF. Oxidation-induced stacking faults (OISF) form recombination-generation centers and scattering centers for carriers, and can 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 a silicon wafer directly affects the performance and reliability of a device. OISF, as a common defect in a silicon wafer, has an important influence on the electrical performance and stability of a device. However, conventional OISF detection techniques cannot effectively distinguish between surface OISF and internal OISF, nor can they accurately determine whether OISF is caused by problems in the single crystal growth process or introduced in the processing process. Therefore, there is an urgent need for a detection method that can accurately distinguish between the two types of OISF. SUMMARY

[0005] The present application mainly solves the problems in the prior art, and provides a method for distinguishing between surface OISF and internal OISF of a silicon wafer, which has the advantages of simple operation and reliable detection performance, and solves the problem of determining whether OISF is caused by the single crystal growth process or introduced in the processing process. It is easy to implement in the manufacturing process, and helps to improve the quality of the silicon wafer and the performance of the device. It provides strong support for optimizing the manufacturing process.

[0006] The above technical problems of the present application are mainly solved by the following technical scheme:

[0007] A method for distinguishing between surface OISF and internal OISF of a silicon wafer, comprising the following operation steps:

[0008] Step 1: Select a silicon wafer to be detected, and perform cleaning and pretreatment. Remove contaminants and impurities on the surface of the silicon wafer.

[0009] Second step: Put the pretreated silicon wafer into a heat treatment device, and perform annealing under nitrogen, so as to form a DZ zone in the region close to the surface of the silicon wafer. Thus, the DZ zone is formed in the region close to the surface of the silicon wafer, and the formation of the DZ zone helps to distinguish the surface OISF and the bulk OISF.

[0010] Third step: Put the annealed silicon wafer into a heat treatment device, and perform heat treatment under a wet oxygen environment to form OISF.

[0011] Fourth step: Perform first etching treatment on the heat-treated silicon wafer to remove the oxide layer on the surface of the silicon wafer and expose the potential OISF.

[0012] Fifth step: Perform detection on the etched silicon wafer by an optical microscope, and observe and record the distribution position and density of OISF on the surface of the silicon wafer. At this time, the observed OISF is the surface-formed OISF.

[0013] Sixth step: Perform second etching treatment.

[0014] Seventh step: Perform detection on the etched silicon wafer by an optical microscope, and observe and record the distribution position and density of OISF on the surface of the silicon wafer. At this time, the increased OISF is the bulk OISF.

[0015] Eighth step: Evaluate the quality of the silicon wafer according to the detection results of the two OISFs.

[0016] As preferred, the cleaning solution is prepared by mixing ethanol, acetone, sodium silicate and deionized water, and the silicon wafer is cleaned; 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 rest is deionized water.

[0017] As preferred, the temperature of the silicon wafer cleaning solution is 44-52°C when the silicon wafer is washed, and the time for washing the silicon wafer is 9-13 minutes.

[0018] As preferred, when annealing is performed under nitrogen, the temperature is 780°C for holding annealing for 3 hours, and then the temperature is 1000°C for holding annealing for 16 hours.

[0019] As preferred, the temperature of heat treatment is 1100°C, and the time is 2 hours.

[0020] As preferred, the first etching treatment adopts etching liquid immersion for 3 minutes, and the etching amount does not exceed the depth of the DZ layer; the second etching treatment adopts etching liquid immersion for 10 minutes, so that the etching amount exceeds the depth of the DZ layer and reaches the bulk defect layer; the depth of the DZ layer is 5um.

[0021] As a preference, for the silicon wafer with more surface OISF, the quantity thereof is reduced by optimizing the processing procedure; for the silicon wafer with more internal OISF, the quantity thereof is controlled by improving the single crystal growth process.

[0022] The present application can achieve the following effects:

[0023] The present application provides a method for distinguishing the surface OISF and internal OISF of the silicon wafer, which has the advantages of simple operation and reliable detection performance compared with the prior art, and solves the problem of judging whether the OISF is generated in the single crystal growth process or introduced in the processing procedure. The method is easy to implement in the manufacturing process, and is helpful to improve the quality of the silicon wafer and the performance of the device. The present application provides strong support for optimizing the manufacturing process. DETAILED DESCRIPTION

[0024] The technical solutions of the present application will be further described in detail through the following examples.

[0025] Example: A method for distinguishing the surface OISF and internal OISF of the silicon wafer, comprising the following operation steps:

[0026] Step 1: Select the silicon wafer to be detected, and perform cleaning and pretreatment.

[0027] The cleaning solution is prepared by mixing ethanol, acetone, sodium silicate and deionized water, and the silicon wafer is cleaned by the 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 rest is deionized water. The temperature of the silicon wafer cleaning solution is 48℃ when the silicon wafer is washed, and the time for washing the silicon wafer is 11 minutes.

[0028] Step 2: Place the pretreated silicon wafer in a heat treatment equipment, and perform annealing under nitrogen to form a DZ zone in the region close to the surface of the silicon wafer. When annealing under nitrogen, the temperature is 780℃ for holding annealing for 3 hours, and then the temperature is 1000℃ for holding annealing for 16 hours.

[0029] Step 3: Place the annealed silicon wafer in a heat treatment equipment, and perform heat treatment under a wet oxygen environment to form OISF. The heat treatment temperature is 1100℃, and the time is 2 hours.

[0030] Step 4: Perform first etching treatment on the heat-treated silicon wafer to remove the oxide layer on the surface of the silicon wafer and expose the potential OISF. The first etching treatment adopts etching liquid immersion for 3 minutes, and the etching amount is not more than the depth of the DZ layer, and the depth of the DZ layer is 5um.

[0031] Step 5: Detect the etched silicon wafer by an optical microscope, and observe and record the distribution position and density of the OISF on the surface of the silicon wafer.

[0032] Step 6: Second etching treatment is performed. The second etching treatment is performed by immersing the wafer in etching liquid for 10 minutes, so that the etching amount exceeds the depth of the DZ layer and reaches the internal defect layer. The depth of the DZ layer is 5um.

[0033] Step 7: The wafer after the etching treatment is detected by optical microscope, and the distribution position and density of OISF on the wafer surface are observed and recorded.

[0034] Step 8: The quality of the wafer is evaluated according to the detection results of the two OISF. For the wafer with more surface OISF, the number of the OISF is reduced by optimizing the processing process; for the wafer with more internal OISF, the number of the OISF is controlled by improving the single crystal growth process.

[0035] In summary, the method for distinguishing the surface OISF and the internal OISF has the advantages of simple operation and reliable detection performance, and solves the problem of judging whether the OISF is generated in the single crystal growth process or introduced in the processing process. It is easy to realize in the manufacturing process, and is helpful to improve the quality of the wafer and the performance of the device. It provides strong support for optimizing the manufacturing process.

[0036] The above only describes the specific embodiments of the present application, but the structural features of the present application are not limited to this. Any changes or modifications made by those skilled in the art in the field of the present application are covered by the patent scope of the present application.

Claims

1. A method of distinguishing between surface OISF and bulk OISF of a silicon wafer, characterized by The method comprises the following steps: Step 1: select the silicon wafer to be detected, and perform cleaning and pretreatment; The cleaning solution is prepared by mixing ethanol, acetone, sodium silicate and deionized water, and the silicon wafer is cleaned; 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 rest is deionized water; Step 2: place the pretreated silicon wafer in a heat treatment equipment and perform annealing under nitrogen, so as to form a DZ zone in the region close to the surface of the silicon wafer; When annealing under nitrogen, the temperature is 780℃ for 3 hours, and then the temperature is 1000℃ for 16 hours; Step 3: place the annealed silicon wafer in a heat treatment equipment and perform heat treatment under a wet oxygen environment to form OISF; Step 4: perform first etching treatment on the heat-treated silicon wafer to remove the oxide layer on the surface of the silicon wafer and expose the potential OISF; the first etching treatment adopts etching liquid immersion for 3 minutes, and the etching amount does not exceed the DZ layer depth; Step 5: detect the etched silicon wafer by an optical microscope, and observe and record the distribution position and density of OISF on the surface of the silicon wafer; Step 6: perform second etching treatment; the second etching treatment adopts etching liquid immersion for 10 minutes, so that the etching amount exceeds the DZ layer depth and reaches the bulk defect layer; the DZ layer depth reference is 5um; Step 7: detect the etched silicon wafer by an optical microscope, 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 according to the detection results of the two OISFs.

2. The method of distinguishing between a wafer surface OISF and a bulk OISF according to claim 1, wherein: The temperature of the silicon wafer cleaning solution is 44-52℃ when washing the silicon wafer, and the time for washing the silicon wafer is 9-13 minutes.

3. The method of distinguishing between a wafer surface OISF and a bulk OISF according to claim 1, wherein: The temperature of the heat treatment is 1100℃, and the time is 2 hours.

4. The method of distinguishing between a wafer surface OISF and a bulk OISF according to claim 1, wherein: For the silicon wafer with more surface OISF, the number thereof is reduced by optimizing the processing process; For the silicon wafer with more bulk OISF, the number thereof is controlled by improving the single crystal growth process.