CN1108400C - Method for removing heavy metal impurity from monocrystal silicon - Google Patents

Method for removing heavy metal impurity from monocrystal silicon Download PDF

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Publication number
CN1108400C
CN1108400C CN 99117832 CN99117832A CN1108400C CN 1108400 C CN1108400 C CN 1108400C CN 99117832 CN99117832 CN 99117832 CN 99117832 A CN99117832 A CN 99117832A CN 1108400 C CN1108400 C CN 1108400C
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China
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crystal
silicon single
metal melt
metal
heavy metal
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Expired - Fee Related
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CN 99117832
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CN1285422A (en
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季振国
樊瑞新
阙端麟
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Zhejiang University ZJU
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Zhejiang University ZJU
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Publication of CN1108400C publication Critical patent/CN1108400C/en
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Abstract

The present invention discloses a method for removing heavy metal impurities from a silicon monocrystal. On the basis of the characteristic that the dissolubility of harmful heavy metal of iron, copper, gold, etc. in metal melt is far larger than the dissolubility in the silicon monocrystal, the silicon monocrystal is immersed in one of or the combined metal melt of tin, gallium, aluminium, indium or lead with high pure which do not affect the service life of a silicon monocrystal current carrier to make the harmful heavy metal impurities in the silicon monocrystal diffuse to the metal melt so as to realize the purpose of thoroughly removing the heavy metal impurities from the silicon monocrystal. The method has the advantages of simple device and convenient operation.

Description

Remove the method for beavy metal impurity in the silicon single-crystal
The present invention relates to remove the method for beavy metal impurity in the silicon single-crystal semiconductor material.
At present the method that beavy metal impurities such as the iron that influences silicon single-crystal carrier lifetime, copper, gold are driven away from silicon single-crystal mainly contain intrinsic gettering and outside two kinds of getterings, intrinsic gettering is to utilize the defective of oxygen precipitation and generation thereof to absorb metallic impurity, thereby forms the clean area that a beavy metal impurity atomic percent has descended greatly at silicon chip surface.Outer gettering has back side phosphorous diffusion, the back side to sandblast, backside laser is damaged, back side ion implantation damage, back side silicon-nitrogen compound deposition, back side polysilicon deposition etc.These two kinds of methods all are that the defective of utilizing the silicon chip inside or the silicon chip back side to form is absorbed the metallic impurity of silicon chip surface workspace (making the zone of device), but the metallic impurity of being absorbed are still stayed in the silicon chip.Therefore the impurity of being absorbed might (as pyroprocessing) reenter in the workspace of device by diffusion in later process.
In view of above-mentioned, the purpose of this invention is to provide a kind of easy, reliable, the method that can thoroughly remove beavy metal impurity in the silicon single-crystal.
Technical solution of the present invention is: silicon single-crystal is immersed fusing silicon single-crystal carrier lifetime is not had in the high purity tin of influence or gallium or aluminium or indium or plumbous or their metal melt of combination, utilize in the silicon single-crystal solubleness of harmful heavy metal in metal melt much larger than the characteristics of solubleness in silicon single-crystal, make harmful heavy metal diffusion of contaminants in the silicon single-crystal in metal melt, and realize thoroughly removing the purpose of beavy metal impurity.
Concrete operations comprise the steps:
1) place crucible to be fused into metal melt highly purified tin or gallium or aluminium or indium or lead metal or their combination.
2) silicon single-crystal is preheated to the temperature close with metal melt, immerses then in the metal melt, the harmful heavy metal impurity of silicon single-crystal will be by diffusing into metal melt.
3) decon finishes, and takes out silicon single-crystal from metal melt.
Usually, in metal melt, dissolve, can take before silicon single-crystal is immersed metal melt, in metal melt, add earlier silicon, with the saturated metal melt of silicon in order to prevent silicon single-crystal.
Below in conjunction with accompanying drawing, be that example is described in detail the present invention with tin.
The fusing point of tin is 292 ℃, and boiling point is 2270 ℃, so the tin existence that is in a liquid state between 292 ℃~2270 ℃.At first high-purity tin is placed crucible 1 to be fused into tin 2, use the saturated molten tin of silicon then, immerse in the molten tin after again silicon single-crystal 3 being preheating to the temperature close with molten tin, and keep molten tin it not to be solidified at a certain proper temperature, at this moment, harmful heavy metal impurity in the silicon single-crystal will arrive the silicon single-crystal surface by diffusion, enter into molten tin at last.The gettering required time is determined according to the size of foreign matter content and silicon single-crystal, after the harmful heavy metal impurity in the silicon single-crystal is absorbed by molten tin, takes out silicon single-crystal from molten tin, and removes the tin of remained on surface.
Usually, for avoiding staiing, body of heater can be vacuumized and feeds gases such as hydrogen or nitrogen.
Because method of the present invention is that the harmful heavy metal impurity that will clear out in the silicon single-crystal is dissolved in metal melt, and no longer remain on the silicon single-crystal, so can avoid removed impurity in later process, to come back to workspace, this method is easy to be more reliable than traditional impurity absorption method, and it is more thorough to remove impurity.

Claims (2)

1. the method for beavy metal impurity in the removal silicon single-crystal is characterized in that comprising following operation steps:
1) place crucible to be fused into metal melt highly purified tin or gallium or aluminium or indium or lead metal or their combination;
2) silicon single-crystal is preheated to the temperature close with metal melt, immerses then in the metal melt, the harmful heavy metal impurity of silicon Dan Pin will be by diffusing into metal melt;
3) decon finishes, and takes out silicon single-crystal from metal melt.
2. by the method for beavy metal impurity in the described removal silicon single-crystal of claim 1, it is characterized in that before silicon single-crystal is immersed metal melt, earlier with the saturated metal melt of silicon.
CN 99117832 1999-08-23 1999-08-23 Method for removing heavy metal impurity from monocrystal silicon Expired - Fee Related CN1108400C (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN 99117832 CN1108400C (en) 1999-08-23 1999-08-23 Method for removing heavy metal impurity from monocrystal silicon

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN 99117832 CN1108400C (en) 1999-08-23 1999-08-23 Method for removing heavy metal impurity from monocrystal silicon

Publications (2)

Publication Number Publication Date
CN1285422A CN1285422A (en) 2001-02-28
CN1108400C true CN1108400C (en) 2003-05-14

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CN 99117832 Expired - Fee Related CN1108400C (en) 1999-08-23 1999-08-23 Method for removing heavy metal impurity from monocrystal silicon

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Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101759188B (en) * 2010-01-19 2012-01-25 浙江大学 Method for purifying metallic silicon by using aluminum melt
CN108796606B (en) * 2018-07-07 2020-11-03 玉环市几偶孵化器有限公司 Solar-grade polycrystalline silicon preparation device

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CN1285422A (en) 2001-02-28

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