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CN-121976286-A - Method for controlling large-size monocrystalline silicon OISF by diameter amplification method

CN121976286ACN 121976286 ACN121976286 ACN 121976286ACN-121976286-A

Abstract

A method for controlling large-size monocrystalline silicon OISF by a diameter amplification method comprises the steps of pulling a monocrystalline silicon rod to 70-75% of a preset total length to obtain a straight pull Duan Jingbang, amplifying the diameter of the monocrystalline silicon rod from the diameter of the straight pull Duan Jingbang to a target diameter by adopting a shouldering process to obtain a defect control section crystal rod, wherein the difference between the target diameter of the shouldering process and the diameter of the crystal rod of the straight pull section is a diameter amplification layer to be ground, the diameter amplification amount corresponding to the diameter amplification layer is delta D, delta D is more than or equal to 2d+C, C is the allowance of the grinding process, D is the maximum depth of an OISF defect ring, and grinding and removing the diameter amplification layer of the defect control section crystal rod to obtain the monocrystalline silicon rod without OISF. According to the invention, the OISF defect ring is actively moved to the outer edge of the crystal bar through diameter amplification, and finally, the diameter amplification part containing the OISF defect ring is thoroughly removed through a grinding process, so that the eradication of the OISF defect ring at the middle and rear sections of the crystal bar is realized from the physical aspect.

Inventors

  • FAN JIXIANG
  • Ma Wuxiang
  • SHAO QI
  • HU XIAOLIANG

Assignees

  • 麦斯克电子材料股份有限公司

Dates

Publication Date
20260505
Application Date
20260403

Claims (10)

  1. 1. A method for controlling large-size monocrystalline silicon OISF by a diameter amplification method, comprising: Pulling the monocrystalline silicon rod to 70-75% of the preset total length by adopting a Czochralski method to obtain a Czochralski Duan Jingbang; Amplifying the diameter of a monocrystalline silicon rod from the diameter of a Czochralski Duan Jingbang to a target diameter by adopting a shouldering process, carrying out equal-diameter growth after each shouldering, and carrying out ending treatment after all shouldering is completed to obtain a defect control section crystal rod, wherein the difference between the target diameter of each shouldering process and the diameter of the Czochralski section crystal rod is a diameter amplification layer needing grinding, the diameter amplification amount corresponding to the diameter amplification layer is delta D, delta D is more than or equal to 2d+C, C is the grinding process allowance, and D is the maximum depth of an OISF defect ring; and grinding and removing the diameter amplification layer of the crystal bar at the defect control section to obtain the OISF-free monocrystalline silicon bar.
  2. 2. The method for controlling the OISF of large-size monocrystalline silicon by using a diameter amplification method according to claim 1, wherein the method for obtaining the maximum depth of the OISF defect ring is as follows: Pulling the monocrystalline silicon sample crystal bar to 70-75% of the preset total length by adopting a Czochralski method to obtain a Czochralski Duan Yangpin crystal bar; amplifying the diameter of a monocrystalline silicon sample crystal bar from the diameter of a Czochralski Duan Yangpin crystal bar to the target diameter of the sample by adopting a shouldering process, carrying out equal-diameter growth after shouldering each time, and carrying out ending treatment after all shouldering is completed to obtain a defect control section sample crystal bar; and sampling the sample crystal bar of the defect control section in multiple regions along the length direction of the sample crystal bar of the monocrystalline silicon, and respectively detecting the radial depths of OISF defect rings of different regions to obtain the maximum depths of OISF defect rings of different regions.
  3. 3. The method for controlling the OISF of large-size single crystal silicon by using the diameter amplification method according to claim 2, wherein the diameter of the OISF defect ring in any area of the sample crystal rod of the defect control section is set to be D in the process of obtaining the maximum depth of the OISF defect ring, the diameter of the area on the sample crystal rod of the defect control section is set to be D ', when D (D ' -D)/2 is detected, the sample crystal rod of the single crystal silicon is pulled again and the pulling speed of the equal-diameter growth is reduced, and the process is repeated for a plurality of times, so that D < (D ' -D)/2.
  4. 4. The method for controlling large-sized single crystal silicon OISF according to claim 2, wherein the defect control segment sample ingot is sampled while being divided into a plurality of regions, each 80-120mm of the defect control segment sample ingot is divided and sampled along the length direction thereof.
  5. 5. The method for controlling the OISF of large-sized single crystal silicon by diameter amplification according to claim 2, wherein the radial depth of the OISF defect ring is detected by microscopic examination.
  6. 6. The method for controlling large-size monocrystalline silicon OISF by diameter amplification method as set forth in claim 2, wherein the maximum depths of OISF defect rings in different areas on the sample ingot of the defect control section are compared, the maximum value is used as the full-section maximum OISF ring depth dmax, the defect control section ingot is continuously pulled on the basis of the Czochralski section ingot by adopting a one-time shouldering process, and the DeltaD is more than or equal to 2 dmax+C.
  7. 7. The method for controlling large-size monocrystalline silicon OISF according to claim 6, wherein the one-time shouldering process is performed under conditions of decreasing the pulling rate and adjusting the crucible rotation, the pulling rate is decreased from 49 mm/h to 35mm/h, and the crucible rotation is increased from 10rpm to 12rpm.
  8. 8. The method for controlling large-size monocrystalline silicon OISF by diameter amplification method as defined in claim 1, wherein grinding process allowance of Czochralski Duan Jingbang is ground and removed to obtain finished monocrystalline silicon rod.
  9. 9. The method for controlling the OISF of large-sized single crystal silicon according to claim 1, wherein the diameter of the large-sized single crystal silicon rod is 200mm to 300mm.
  10. 10. The method for controlling the OISF of large-size monocrystalline silicon by using the diameter amplification method according to claim 1, wherein the process of the Czochralski method comprises seeding, shouldering, shoulder turning and isodiametric reduction, the shouldering process is to continue shouldering and isodiametric reduction on the basis of the Czochralski method, the process condition of the shouldering process is that the pulling speed is reduced from 49 mm/h to 35mm/h, and the crucible rotation is increased from 10rpm to 12rpm.

Description

Method for controlling large-size monocrystalline silicon OISF by diameter amplification method Technical Field The invention relates to the technical field of semiconductor material preparation, in particular to a method for controlling large-size monocrystalline silicon OISF by a diameter amplification method. Background Czochralski silicon is a base material for integrated circuit fabrication, and its crystal integrity directly determines the electrical performance, reliability, and fabrication yield of the chip. Oxidation Induced Stacking Fault (OISF) is a common secondary defect in czochralski silicon, and can proliferate and extend in the device oxidation process, resulting in serious problems of PN junction leakage, reduced gate oxide integrity, device failure, and the like. In large-scale production of large-size monocrystalline silicon, OISF defects are mainly concentrated in the middle and rear sections of the crystal bar (the area accounting for 75% -100% of the total length), the ratio of the finished product rate of the whole bar to the output rate of high-end wafers is obviously reduced, and the OISF defects are annularly covered on the periphery of the crystal bar and are also called OISF defect rings. The OISF defect causes are complex, on one hand, the causes are related to instability of a thermal field, melt is reduced in the later stage of crystal growth, the liquid level is reduced, the temperature and the temperature gradient (G) distribution of the thermal field are changed drastically, the V/G critical condition for maintaining perfect crystal growth is destroyed, on the other hand, impurities are separated and condensed, the impurities such as oxygen and carbon are continuously condensed towards the tail part of the melt in the growth process, the nucleation probability of the OISF is improved, and in addition, the thermal stress generated by dead weight mechanical stress and uneven cooling is superposed at the tail part due to the increase of the length of the crystal rod, so that the generation and expansion of the OISF defect are further promoted. The main means for controlling OISF in the current industry is mainly hardware modification scheme, including optimizing thermal field structures such as heater configuration and heat insulation assembly layout, applying magnetic field crystal pulling (MCZ), and the like. The equipment modification cost of the method is high, the research and development period is long, and one thermal field configuration is always only optimal for specific products, so that the process flexibility is lacking. In addition, in the existing main means for controlling OISF, defect generation is mainly inhibited, and it is difficult to thoroughly eliminate the defect. The chinese patent publication No. CN121344750a discloses a method for reducing the OISF of large-sized czochralski silicon by reducing the rotation speed of the crucible and the reduction of the heating power in the latter period of shouldering to form a predetermined vacancy-type point defect region in advance, then increasing the rotation speed of the crucible and increasing the reduction of the heating power in the former period of isodiametric, and dynamically switching from "low crucible turn + vacancy type" to "high crucible turn + low power" in the former period of isodiametric in the latter period of shouldering to drive the vacancy-type point defect to move toward the V/I boundary and even from the gap-type side, so as to form a clean region without OISF nuclei in the crystal. However, the scheme can promote the change of the defect type in the melt by adjusting the crucible rotation and the power, and is difficult to effectively remove OIS defects in the crystal bar, especially in the middle and rear sections of the crystal bar. Disclosure of Invention In order to effectively remove OISF at the middle and rear sections of Czochralski silicon, the invention provides a method for controlling OISF of large-size monocrystalline silicon by a diameter amplification method. The method comprises the steps of pulling a single crystal silicon rod to 70-75% of a preset total length by adopting a Czochralski method to obtain a Czochralski Duan Jingbang, amplifying the diameter of the single crystal silicon rod from the diameter of Czochralski Duan Jingbang to a target diameter by adopting a shouldering process, carrying out equal diameter growth after shouldering each time, and carrying out ending treatment after all shouldering is finished to obtain a defect control section crystal rod, wherein the difference between the target diameter of the shouldering process and the diameter of the crystal rod of the Czochralski section is a diameter amplification layer needing to be ground, the diameter amplification increment corresponding to the diameter amplification layer is DeltaD, deltaD is more than or equal to 2d+C, C is the grinding process allowance, D is the maximum depth of an OISF defect rin