CN102534751A - Casting zone melting gas doping method for preparing zone-melted silicon single crystal - Google Patents
Casting zone melting gas doping method for preparing zone-melted silicon single crystal Download PDFInfo
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- CN102534751A CN102534751A CN2012100597545A CN201210059754A CN102534751A CN 102534751 A CN102534751 A CN 102534751A CN 2012100597545 A CN2012100597545 A CN 2012100597545A CN 201210059754 A CN201210059754 A CN 201210059754A CN 102534751 A CN102534751 A CN 102534751A
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Abstract
The invention relates to a casting zone melting gas doping method for preparing a zone-melted silicon single crystal. The method comprises the following steps of: preparing polycrystalline silicon by a casting method, performing square cutting on the polycrystalline silicon, barreling, slotting, and starting conical machining; pulling the crystal by a zone melting gas doping method by taking the machined polycrystalline silicon rod as the raw material of the zone-melted silicon single crystal, introducing a certain amount of dopant gas at the beginning of crystal pulling, and stopping introducing the dopant gas; and if the target concentration of a dopant of the zone-melted silicon single crystal is c0, controlling the average concentration of the dopant of the polycrystalline silicon to be c0, wherein k is the segregation coefficient of the dopant. The concentration of the dopant of the polycrystalline rod is uniform, and gas doping is not required to be performed at a retention stage, so the concentration uniformity of a silicon melt is extremely high, and the radial resistivity uniformity of the zone-melted single crystal is effectively improved. Compared with a neutron transmutation doping (NTD) method, the method is low in cost and short in production period; and compared with the zone melting gas doping method and a Czochralski zone melting method, the method has the advantage that: the radial resistivity uniformity is effectively improved.
Description
Technical field
The present invention relates to a kind of preparation method of zone-melted silicon single crystal, particularly a kind of molten gas of casting region for preparing zone-melted silicon single crystal is mixed method.
Background technology
At present, the technology of production extrinsic region silicon crystal mainly contains in the prior art: NTD method, the molten gas in district are mixed three kinds of method and vertical pulling and zone melting process.One of which, the zone-melted silicon single crystal resistivity evenness that NTD neutron irradiation method is produced is the highest, but cost is bigger, and the production cycle is long.Its two, the molten gas in district is mixed method in process of production, through feeding doping gas zone-melted silicon single crystal is mixed.Doping gas (phosphine or borine) is the hydrogenate of solid dopant phosphorus or boron, and decomposes is hydrogen and corresponding solid dopant during high temperature.When gas is mixed farad system zone-melted silicon single crystal, feed doping gas to furnace chamber, near the high temperature punishment melting zone of doping gas is separated, and plays the doping purpose thereby the doping agent that decomposition generates enters into silicon melt, and the hydrogen of generation then is dispersed in the furnace chamber.Here it is, and the molten gas in district is mixed the adulterated principle of method.
Doping gas is incorporated into doping agent in the silicon melt through gas liquid film, and then behind the silicon melt solidification and crystallization, successfully doping agent is mixed in the silicon single-crystal.Can know that through the doping agent mobile route concentration of dopant of bath surface is higher, and the inner concentration of dopant of melt is lower.And because in the zone melting method, the volume of silicon melt is less, a little less than the convection current, to the stirring action of doping agent very a little less than, finally cause in the zone-melted silicon single crystal dopant distribution uneven, this also is to cause the radially uneven one of the main reasons of resistivity of zone-melted silicon single crystal.
Its three, vertical pulling and zone melting process at first adopts vertical pulling method to draw the policrystalline silicon rod, doping agent was incorporated in the polycrystalline silicon rod through conventional doping way in the vertical pulling stage.Along with the continuous solidification and crystallization of silicon melt, receive the influence of segregation effect, concentration of dopant is also increasingly high in the silicon melt, and the silicon crystal resistivity of solidifying is also more and more lower.Again because silicon crystal bar center heat radiation is slow, the edge rapid heat dissipation, thereby its solid-liquid interface is last spill, in polycrystalline silicon rod, can form the constant resistance rate face of spill like this, and resistivity reduces gradually.
Zone-melted silicon single crystal draws the stage at zone melting method, if the polycrystalline silicon rod head is downward, on the change material interface of polycrystalline silicon rod, the silicon melt resistivity of fusing is comparatively approaching, and the silicon melt resistivity that then provides for silicon monocrystal growth is comparatively even.But because the axial resistivity of polycrystalline silicon rod itself is inhomogeneous, add the influence of segregation effect, the axial resistivity gradient of the zone-melted silicon single crystal of drawing is very big.Equally, zone-melted silicon single crystal center heat radiation is slow, the edge rapid heat dissipation, and its solid-liquid interface is spill down, so the constant resistance rate face of zone-melted silicon single crystal is spill down.Bigger axial resistivity gradient causes silicon chip center resistivity and edge resistivity to differ bigger, thereby greatly reduces the radially resistivity evenness of zone-melted silicon single crystal.
Draw the stage at zone melting method; If the polycrystalline silicon rod head upwards; Because the influence of the axial resistivity distribution of policrystalline silicon itself and the influence of segregation phenomena though the axial resistivity distribution of the zone-melted silicon single crystal that is drawn makes moderate progress when more downward than head, still can not be effectively controlled.Secondly polycrystalline silicon rod melts the silicon melt of fusing at the interface, and its resistivity difference is bigger, can not obtain under effective melt convection effect, and melt resistivity is comparatively inhomogeneous, has finally also reduced the radially resistivity evenness of zone-melted silicon single crystal.
All there is weak point in the method existing process method in sum, awaits improving.
Summary of the invention
The object of the invention is exactly for overcoming the deficiency of prior art, the radially method of resistivity evenness of a kind of effective raising zone-melted silicon single crystal being provided.
The present invention realizes through such technical scheme: a kind of molten gas of casting region for preparing zone-melted silicon single crystal is mixed method; It is characterized in that, adopt casting to prepare polysilicon, afterwards polysilicon is carried out butt, barreling, slots and open the circular cone machining; With processing after polycrystalline silicon rod as the zone-melted silicon single crystal raw material; Adopt the Qu Rongqi method of mixing to carry out crystal pulling, and when the beginning crystal pulling, feed quantitative doping gas, doping gas can be phosphine or borine.When doping gas was phosphine, concentration of dopant reached value c0/k=1.7 * 10 in the silicon melt
14Atom/cm
3To 6.5 * 10
21Atom/cm
3Promptly stop to feed doping gas after the scope; When doping gas was borine, concentration of dopant reached value c0/k=7.6 * 10 in the silicon melt
13To 1.6 * 10
21Atom/cm
3Promptly stop to feed doping gas after the scope; If the doping agent mean intensity value that zone melting single-crystal silicon dopant aimed concn is c0 then controls policrystalline silicon is c0, k is the doping agent segregation coefficient; Said method comprises the steps:
A) adopt casting to prepare polysilicon, then polysilicon is carried out butt, barreling, slots and open the circular cone machining;
B) be raw material with the polycrystalline silicon rod that makes after the machining, adopt the Qu Rongqi method of mixing to carry out crystal pulling, through prior art, control polycrystalline silicon rod xsect concentration of dopant is starting point concentration c0; When crystal pulling is melted in the district, begin to feed quantitative doping gas from expanding the shoulder stage, mix technology through existing gas, the concentration value of doping agent reaches in the maintenance stage makes silicon melt: c0/k stops to feed doping gas afterwards;
C) the maintenance stage, suppose that crystalline volume is V0, the new melt volume that then flows into is V0; The silicon melt constant volume is constant, and concentration of dopant is c0 in the crystalline silicon single-crystal, and then silicon melt doping agent reduction is c0*V0; And the doping agent that increases newly is c0*V0, and the doping agent total amount is constant, and is final; The silicon melt concentration of dopant maintains c0/k, makes the concentration of silicon single-crystal also be stabilized in this target value of c0;
The zone-melted silicon single crystal for preparing according to above-mentioned steps axially and radially resistivity evenness reaches RRV＜8%.
The invention has the beneficial effects as follows: because the concentration of dopant of polycrystalline charge bar of the present invention is comparatively even, and the maintenance stage need not to carry out gas and mix, then silicon melt concentration homogeneity is very high, has effectively improved the radially homogeneity of resistivity of zone melting single-crystal; Compare the method with NTD, cost is lower, and the production cycle is shorter; Compare with vertical pulling and zone melting process with the molten gas method of mixing in district, radially resistivity evenness has obtained effective raising.
Description of drawings
Fig. 1, mix the method synoptic diagram for the molten gas of casting region;
Fig. 2, prepare the polycrystalline synoptic diagram for casting;
Fig. 3, be polysilicon cutting mode synoptic diagram.
Among the figure: 1 is the polycrystalline charge bar, and 2 is silicon melt, and 3 is zone melting single-crystal, and 4 are polycrystalline fusing face.
Embodiment
To shown in Figure 3, adopt casting to prepare polysilicon like Fig. 1, afterwards polysilicon carried out butt, barreling, slot and open the circular cone machining, as the zone-melted silicon single crystal raw material, adopt the Qu Rongqi method of mixing to carry out crystal pulling with the polycrystalline silicon rod after the processing,
As shown in Figure 2, solid-liquid interface is approximately the plane during owing to the polycrystalline ingot casting, so same planar silicon polycrystalline concentration of dopant is consistent.After carrying out butt according to the method for Fig. 3, the axis resistivity of each polycrystalline rod all is consistent.
Behind seeding, the drawing-down neck; Reduce lower shaft speed and begin to expand shoulder, in expanding the shoulder process and isometrical maintenance initial stage feeding impurity gas, make that concentration of dopant is c0/k in the silicon melt with the lower shaft rotating speed; Stop to feed doping gas after the isometrical maintenance, can guarantee that like this silicon single-crystal concentration of dopant is c0.
According to above-mentioned explanation, can realize scheme of the present invention in conjunction with art technology.
Claims (1)
1. the molten gas of casting region for preparing zone-melted silicon single crystal is mixed method; It is characterized in that, adopt casting to prepare polysilicon, afterwards polysilicon is carried out butt, barreling, slots and open the circular cone machining; With processing after polycrystalline silicon rod as the zone-melted silicon single crystal raw material; Adopt the Qu Rongqi method of mixing to carry out crystal pulling, and when the beginning crystal pulling, feed quantitative doping gas, doping gas can be phosphine or borine; When doping gas was phosphine, concentration of dopant reached value c0/k=1.7 * 10 in the silicon melt
14Atom/cm
3To 6.5 * 10
21Atom/cm
3Promptly stop to feed doping gas after the scope; When doping gas was borine, concentration of dopant reached value c0/k=7.6 * 10 in the silicon melt
13To 1.6 * 10
21Atom/cm
3Promptly stop to feed doping gas after the scope; If the doping agent mean intensity value that zone melting single-crystal silicon dopant aimed concn is c0 then controls policrystalline silicon is c0, k is the doping agent segregation coefficient; Said method comprises the steps:
A) adopt casting to prepare polysilicon, then polysilicon is carried out butt, barreling, slots and open the circular cone machining;
B) be raw material with the polycrystalline silicon rod that makes after the machining, adopt the Qu Rongqi method of mixing to carry out crystal pulling, through prior art, control polycrystalline silicon rod xsect concentration of dopant is starting point concentration c0; When crystal pulling is melted in the district, begin to feed quantitative doping gas from expanding the shoulder stage, mix technology through existing gas, the concentration value of doping agent reaches in the maintenance stage makes silicon melt: c0/k stops to feed doping gas afterwards;
C) the maintenance stage, suppose that crystalline volume is V0, the new melt volume that then flows into is V0; The silicon melt constant volume is constant, and concentration of dopant is c0 in the crystalline silicon single-crystal, and then silicon melt doping agent reduction is c0*V0; And the doping agent that increases newly is c0*V0, and the doping agent total amount is constant, and is final; The silicon melt concentration of dopant maintains c0/k, makes the concentration of silicon single-crystal also be stabilized in this target value of c0;
The zone-melted silicon single crystal for preparing according to above-mentioned steps axially and radially resistivity evenness reaches RRV＜8%.
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| CN111270300A (en) * | 2018-12-04 | 2020-06-12 | 有研半导体材料有限公司 | Preparation method of gas-phase doped zone-melting silicon single crystal |
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|---|---|---|---|---|
| US20090309069A1 (en) * | 2006-09-29 | 2009-12-17 | Shinji Togawa | Silicon single crystal manufacturing method, silicon single crystal, silicon wafer, apparatus for controlling manufacture of silicon single crystal, and program |
| CN102304757A (en) * | 2011-10-11 | 2012-01-04 | 天津市环欧半导体材料技术有限公司 | Method for preparing 6-inch P-type solar silicon single crystals through Czochralski method and zone melting method |
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Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20090309069A1 (en) * | 2006-09-29 | 2009-12-17 | Shinji Togawa | Silicon single crystal manufacturing method, silicon single crystal, silicon wafer, apparatus for controlling manufacture of silicon single crystal, and program |
| CN102304757A (en) * | 2011-10-11 | 2012-01-04 | 天津市环欧半导体材料技术有限公司 | Method for preparing 6-inch P-type solar silicon single crystals through Czochralski method and zone melting method |
Non-Patent Citations (2)
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| 中国大百科全书总编辑委员会: "《中国大百科全书 矿冶》", 30 September 2002, article "区熔法单晶", pages: 227 * |
| 刘洪飞 等: "气相掺杂FZ单晶电阻率的控制", 《半导体技术》, vol. 33, 31 December 2008 (2008-12-31) * |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111270300A (en) * | 2018-12-04 | 2020-06-12 | 有研半导体材料有限公司 | Preparation method of gas-phase doped zone-melting silicon single crystal |
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Application publication date: 20120704 |