CN-115931863-B - Method and system for detecting defects in monocrystalline silicon rod

CN115931863BCN 115931863 BCN115931863 BCN 115931863BCN-115931863-B

Abstract

The embodiment of the invention discloses a method and a system for detecting defects in a monocrystalline silicon rod, wherein the method comprises the steps of cutting a P-band region of the monocrystalline silicon rod to prepare a silicon wafer to be detected, carrying out acid corrosion on the silicon wafer to be detected to thin the surface thickness of the silicon wafer to be detected so as to remove a damaged layer on the surface of the silicon wafer to be detected, corroding the thinned silicon wafer to be detected by adopting a Saike corrosive liquid so as to enable the defects in the silicon wafer to be detected to be revealed, detecting the defects in the silicon wafer to be detected, and judging the defects to be NDP defects when the characteristics of the defects meet set conditions.

Inventors

TONG JIAXI
Request for anonymity

Assignees

西安奕斯伟材料科技有限公司
西安奕斯伟硅片技术有限公司

Dates

Publication Date: 20260512
Application Date: 20221213

Claims (9)

1. A method for detecting defects in a single crystal silicon rod, the method comprising: Cutting from the P-band region of the monocrystalline silicon rod to prepare a silicon wafer to be tested; performing acid corrosion on the silicon wafer to be tested to thin the surface thickness of the silicon wafer to be tested so as to remove a damaged layer on the surface of the silicon wafer to be tested; corroding the thinned silicon wafer to be tested by adopting a Saike corrosive liquid so that defects in the silicon wafer to be tested are revealed; detecting the defects in the silicon wafer to be detected, judging the silicon wafer to be NDP defects when the characteristics of the defects meet the set conditions, Detecting the defect in the silicon wafer to be detected, and judging the silicon wafer to be an NDP defect when the characteristics of the defect meet the set conditions, wherein the method comprises the following steps: when the defect aggregation with high density and symmetrical patterns appears on the surface of the silicon wafer to be detected, judging that the defect is an NDP defect if the characteristics of the defect simultaneously meet the following three conditions: The distribution of the defects is disc-shaped, or annular, or a combination of disc-shaped and annular; the appearance of the defect is a black round hole, the center of the defect presents metallic luster, and no special-shaped bright spots exist; The density of the defects is greater than 100ea/cm2.
2. The method according to claim 1, wherein the performing acid etching on the silicon wafer to be tested to thin the surface thickness of the silicon wafer to be tested to remove the damaged layer on the surface of the silicon wafer to be tested comprises: and (3) carrying out acid corrosion treatment on the silicon wafer to be tested by adopting a corrosion solution formed by mixing 29% -49% of HF solution and 40% -70% of HNO 3 solution according to the volume ratio of 1:10-2:5, so that the surface thickness of the silicon wafer to be tested is corroded and thinned by more than 150 mu m.
3. The detection method according to claim 2, wherein the continuous corrosion time of the acid corrosion is 1 min-2 min, and the corrosion rate is controlled to be 100 μm/min-150 μm/min.
4. The method according to claim 1, wherein the etching the thinned silicon wafer to be tested with a raceae etchant to make defects in the silicon wafer to be tested manifest comprises: And (3) carrying out corrosion treatment on the thinned silicon wafer to be tested by adopting a Siraceae corrosion solution formed by mixing 29% -49% of HF solution and 60% -100% of K 2 CrO 4 solution according to a volume ratio of 1:5-1:2, so that the surface thickness of the silicon wafer to be tested is corroded and thinned again by more than 20 mu m, and the defects are displayed.
5. The method according to claim 4, wherein the corrosion duration of the Saike corrosion liquid is 5min-20min, and the corrosion rate is controlled to be 1 μm/min-1.4 μm/min.
6. The method according to claim 1, wherein detecting the defect in the silicon wafer to be detected, and determining that the defect is an NDP defect when the feature of the defect satisfies a set condition, further comprises: Placing the thinned silicon wafer to be tested under a visual detection device for visual detection, and observing whether defect aggregation with high density and symmetrical patterns appears on the surface of the silicon wafer to be tested; When defect aggregation with high density and symmetrical patterns appears on the surface of the silicon wafer to be detected, detecting the distribution, morphology and density of the defects by using a microscope.
7. The method according to claim 1, wherein the NDP defect has a diameter size of 5 μm to 12 μm.
8. A system for detecting defects in a single crystal silicon rod, the system comprising: The cutting device is used for cutting from the P-band region of the monocrystalline silicon rod to prepare a silicon wafer to be tested; The acid corrosion device is used for carrying out acid corrosion on the silicon wafer to be tested so as to thin the surface thickness of the silicon wafer to be tested and remove a damaged layer on the surface of the silicon wafer to be tested; The Saike corrosion device is used for corroding the thinned silicon wafer to be tested by adopting Saike corrosion liquid so that defects in the silicon wafer to be tested are revealed; A detection device for detecting the defect in the silicon wafer to be detected, judging the silicon wafer to be NDP defect when the characteristic of the defect meets the set condition, The detection device is further used for judging that the defect is an NDP defect if the characteristics of the defect simultaneously meet the following three conditions when the defect aggregation with high density and symmetrical patterns appears on the surface of the silicon wafer to be detected: The distribution of the defects is disc-shaped, or annular, or a combination of disc-shaped and annular; the appearance of the defect is a black round hole, the center of the defect presents metallic luster, and no special-shaped bright spots exist; The density of the defects is greater than 100ea/cm2.
9. The detection system of claim 8, wherein the detection device comprises a visual detection device and a microscopic detection device, wherein, The visual inspection device is used for observing whether defect aggregation with high density and symmetrical patterns appears on the surface of the silicon wafer to be tested; The microscopic detection device is used for detecting the distribution, the morphology and the density of the defects by using a microscope when the defects with high density and symmetrical patterns are gathered on the surface of the silicon wafer to be detected.

Description

Method and system for detecting defects in monocrystalline silicon rod Technical Field The embodiment of the invention relates to the technical field of silicon wafer defect detection, in particular to a method and a system for detecting defects in a monocrystalline silicon rod. Background Single crystal silicon rods produced by the Magnetic-field Czochralski Method (MCZ) often have a variety of crystal defects, which are generally classified into vacancy defects and interstitial defects according to the principle of defect formation. After the crystal pulling process is completed, preferential etching is generally performed to determine whether the single crystal silicon rod has Flow pattern defects (Flow PATTERN DEFECT, FPD) and large dislocation recesses (Large Dislocation Pit, LDP) defects, which are also important criteria for determining whether the single crystal silicon rod is free of crystal originated particles (COP (Crystal Original Particle) free). With the gradual development of crystal pulling technology and the increasingly strict requirements of silicon wafers on bulk micro defects (Bulk Micro Defects, BMD), the quantity of BMD is controlled by doping nitrogen-containing silicon wafers (SiN) in the crystal pulling process, so that the internal gettering capability of the silicon wafers is controlled, which is a common production mode in epitaxial products. In this process, it was found that with the increase of nitrogen content in the single crystal silicon rod, a new defect different from FPD and LDP occurs in the P-band region where FPD and LDP do not occur, and the defect occurs at a position where the pull rate is high and the nitrogen concentration is high, and also affects the performance of the silicon wafer, such as PN junction leakage, short circuit of trench capacitor, or insulation failure. Therefore, the defect must be detected and identified in the single crystal silicon rod to avoid outflow of the silicon wafer containing the defect. Disclosure of Invention In view of the foregoing, it is desirable to provide a method and a system for detecting defects in a single crystal silicon rod, which can identify Nitrogen generation defects (Nitrogen DEFECT PITS, NDP) in the detection stage of the single crystal silicon rod, and avoid the possibility of outflow of bad silicon wafers. The technical scheme of the embodiment of the invention is realized as follows: in a first aspect, an embodiment of the present invention provides a method for detecting a defect in a single crystal silicon rod, where the method includes: Cutting from the P-band region of the monocrystalline silicon rod to prepare a silicon wafer to be tested; performing acid corrosion on the silicon wafer to be tested to thin the surface thickness of the silicon wafer to be tested so as to remove a damaged layer on the surface of the silicon wafer to be tested; corroding the thinned silicon wafer to be tested by adopting a Saike corrosive liquid so that defects in the silicon wafer to be tested are revealed; Detecting defects in the silicon wafer to be detected, and judging the silicon wafer to be NDP defects when the characteristics of the defects meet set conditions. In a second aspect, an embodiment of the present invention provides a system for detecting a defect in a single crystal silicon rod, the system comprising: The cutting device is used for cutting from the P-band region of the monocrystalline silicon rod to prepare a silicon wafer to be tested; The acid corrosion device is used for carrying out acid corrosion on the silicon wafer to be tested so as to thin the surface thickness of the silicon wafer to be tested and remove a damaged layer on the surface of the silicon wafer to be tested; The Saike corrosion device is used for corroding the thinned silicon wafer to be tested by adopting Saike corrosion liquid so that defects in the silicon wafer to be tested are revealed; And the detection device is used for detecting defects in the silicon wafer to be detected, and judging the silicon wafer to be NDP defects when the characteristics of the defects meet set conditions. The embodiment of the invention provides a method and a system for detecting defects in a monocrystalline silicon rod, wherein after the monocrystalline silicon rod is cut to obtain a silicon wafer to be detected for acid corrosion, a Siemens corrosion solution is adopted to corrode the silicon wafer to be detected again to enable the defects in the silicon wafer to be detected to be displayed, so that the defects in the silicon wafer to be detected are detected, and NDP defects in the monocrystalline silicon rod can be determined when the characteristics displayed by the defects in the silicon wafer to be detected meet set judging conditions. The detection method provided by the embodiment of the invention can be used for determining the performance characteristics of the NDP defects, detecting the NDP defects in the nitrogen-doped monocrystalline