CN110541191A - Method for producing single crystal silicon, epitaxial silicon wafer, and single crystal silicon substrate - Google Patents
Method for producing single crystal silicon, epitaxial silicon wafer, and single crystal silicon substrate Download PDFInfo
- Publication number
- CN110541191A CN110541191A CN201910458568.0A CN201910458568A CN110541191A CN 110541191 A CN110541191 A CN 110541191A CN 201910458568 A CN201910458568 A CN 201910458568A CN 110541191 A CN110541191 A CN 110541191A
- Authority
- CN
- China
- Prior art keywords
- crystal
- single crystal
- nitrogen
- crystal silicon
- raw material
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 title claims abstract description 93
- 229910052710 silicon Inorganic materials 0.000 title claims abstract description 93
- 239000010703 silicon Substances 0.000 title claims abstract description 93
- 239000000758 substrate Substances 0.000 title claims abstract description 82
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 42
- 229910021421 monocrystalline silicon Inorganic materials 0.000 title claims description 116
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims abstract description 347
- 239000013078 crystal Substances 0.000 claims abstract description 179
- 229910052757 nitrogen Inorganic materials 0.000 claims abstract description 179
- 238000000034 method Methods 0.000 claims abstract description 78
- 230000002093 peripheral effect Effects 0.000 claims abstract description 34
- 238000005204 segregation Methods 0.000 claims abstract description 20
- 230000007547 defect Effects 0.000 claims description 114
- 239000002994 raw material Substances 0.000 claims description 93
- 239000007788 liquid Substances 0.000 claims description 66
- 238000010438 heat treatment Methods 0.000 claims description 34
- 239000010453 quartz Substances 0.000 claims description 13
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N silicon dioxide Inorganic materials O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 13
- 230000008569 process Effects 0.000 abstract description 30
- 238000005247 gettering Methods 0.000 abstract description 25
- 238000001556 precipitation Methods 0.000 abstract description 12
- 229910021419 crystalline silicon Inorganic materials 0.000 abstract description 5
- 235000012431 wafers Nutrition 0.000 description 85
- 230000000052 comparative effect Effects 0.000 description 65
- 230000012010 growth Effects 0.000 description 33
- 238000009826 distribution Methods 0.000 description 28
- 230000007423 decrease Effects 0.000 description 14
- 238000011156 evaluation Methods 0.000 description 13
- 230000008859 change Effects 0.000 description 11
- 239000007789 gas Substances 0.000 description 11
- 230000015572 biosynthetic process Effects 0.000 description 9
- 239000000155 melt Substances 0.000 description 8
- 230000003247 decreasing effect Effects 0.000 description 7
- 238000010586 diagram Methods 0.000 description 7
- 238000009792 diffusion process Methods 0.000 description 7
- 230000000694 effects Effects 0.000 description 7
- 239000000047 product Substances 0.000 description 6
- 238000000790 scattering method Methods 0.000 description 6
- 230000003111 delayed effect Effects 0.000 description 5
- 239000010410 layer Substances 0.000 description 5
- 230000007935 neutral effect Effects 0.000 description 5
- 230000005855 radiation Effects 0.000 description 5
- 230000009467 reduction Effects 0.000 description 5
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 4
- 229910002804 graphite Inorganic materials 0.000 description 4
- 239000010439 graphite Substances 0.000 description 4
- 239000012535 impurity Substances 0.000 description 4
- 238000002844 melting Methods 0.000 description 4
- 239000002184 metal Substances 0.000 description 4
- 229910052751 metal Inorganic materials 0.000 description 4
- OHVLMTFVQDZYHP-UHFFFAOYSA-N 1-(2,4,6,7-tetrahydrotriazolo[4,5-c]pyridin-5-yl)-2-[4-[2-[[3-(trifluoromethoxy)phenyl]methylamino]pyrimidin-5-yl]piperazin-1-yl]ethanone Chemical compound N1N=NC=2CN(CCC=21)C(CN1CCN(CC1)C=1C=NC(=NC=1)NCC1=CC(=CC=C1)OC(F)(F)F)=O OHVLMTFVQDZYHP-UHFFFAOYSA-N 0.000 description 3
- KZEVSDGEBAJOTK-UHFFFAOYSA-N 1-(2,4,6,7-tetrahydrotriazolo[4,5-c]pyridin-5-yl)-2-[5-[2-[[3-(trifluoromethoxy)phenyl]methylamino]pyrimidin-5-yl]-1,3,4-oxadiazol-2-yl]ethanone Chemical compound N1N=NC=2CN(CCC=21)C(CC=1OC(=NN=1)C=1C=NC(=NC=1)NCC1=CC(=CC=C1)OC(F)(F)F)=O KZEVSDGEBAJOTK-UHFFFAOYSA-N 0.000 description 3
- LDXJRKWFNNFDSA-UHFFFAOYSA-N 2-(2,4,6,7-tetrahydrotriazolo[4,5-c]pyridin-5-yl)-1-[4-[2-[[3-(trifluoromethoxy)phenyl]methylamino]pyrimidin-5-yl]piperazin-1-yl]ethanone Chemical compound C1CN(CC2=NNN=C21)CC(=O)N3CCN(CC3)C4=CN=C(N=C4)NCC5=CC(=CC=C5)OC(F)(F)F LDXJRKWFNNFDSA-UHFFFAOYSA-N 0.000 description 3
- JQMFQLVAJGZSQS-UHFFFAOYSA-N 2-[4-[2-(2,3-dihydro-1H-inden-2-ylamino)pyrimidin-5-yl]piperazin-1-yl]-N-(2-oxo-3H-1,3-benzoxazol-6-yl)acetamide Chemical compound C1C(CC2=CC=CC=C12)NC1=NC=C(C=N1)N1CCN(CC1)CC(=O)NC1=CC2=C(NC(O2)=O)C=C1 JQMFQLVAJGZSQS-UHFFFAOYSA-N 0.000 description 3
- DFGKGUXTPFWHIX-UHFFFAOYSA-N 6-[2-[4-[2-(2,3-dihydro-1H-inden-2-ylamino)pyrimidin-5-yl]piperazin-1-yl]acetyl]-3H-1,3-benzoxazol-2-one Chemical compound C1C(CC2=CC=CC=C12)NC1=NC=C(C=N1)N1CCN(CC1)CC(=O)C1=CC2=C(NC(O2)=O)C=C1 DFGKGUXTPFWHIX-UHFFFAOYSA-N 0.000 description 3
- 230000006872 improvement Effects 0.000 description 3
- 230000008018 melting Effects 0.000 description 3
- 239000004065 semiconductor Substances 0.000 description 3
- WZFUQSJFWNHZHM-UHFFFAOYSA-N 2-[4-[2-(2,3-dihydro-1H-inden-2-ylamino)pyrimidin-5-yl]piperazin-1-yl]-1-(2,4,6,7-tetrahydrotriazolo[4,5-c]pyridin-5-yl)ethanone Chemical compound C1C(CC2=CC=CC=C12)NC1=NC=C(C=N1)N1CCN(CC1)CC(=O)N1CC2=C(CC1)NN=N2 WZFUQSJFWNHZHM-UHFFFAOYSA-N 0.000 description 2
- YJLUBHOZZTYQIP-UHFFFAOYSA-N 2-[5-[2-(2,3-dihydro-1H-inden-2-ylamino)pyrimidin-5-yl]-1,3,4-oxadiazol-2-yl]-1-(2,4,6,7-tetrahydrotriazolo[4,5-c]pyridin-5-yl)ethanone Chemical compound C1C(CC2=CC=CC=C12)NC1=NC=C(C=N1)C1=NN=C(O1)CC(=O)N1CC2=C(CC1)NN=N2 YJLUBHOZZTYQIP-UHFFFAOYSA-N 0.000 description 2
- YLZOPXRUQYQQID-UHFFFAOYSA-N 3-(2,4,6,7-tetrahydrotriazolo[4,5-c]pyridin-5-yl)-1-[4-[2-[[3-(trifluoromethoxy)phenyl]methylamino]pyrimidin-5-yl]piperazin-1-yl]propan-1-one Chemical compound N1N=NC=2CN(CCC=21)CCC(=O)N1CCN(CC1)C=1C=NC(=NC=1)NCC1=CC(=CC=C1)OC(F)(F)F YLZOPXRUQYQQID-UHFFFAOYSA-N 0.000 description 2
- CONKBQPVFMXDOV-QHCPKHFHSA-N 6-[(5S)-5-[[4-[2-(2,3-dihydro-1H-inden-2-ylamino)pyrimidin-5-yl]piperazin-1-yl]methyl]-2-oxo-1,3-oxazolidin-3-yl]-3H-1,3-benzoxazol-2-one Chemical compound C1C(CC2=CC=CC=C12)NC1=NC=C(C=N1)N1CCN(CC1)C[C@H]1CN(C(O1)=O)C1=CC2=C(NC(O2)=O)C=C1 CONKBQPVFMXDOV-QHCPKHFHSA-N 0.000 description 2
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 2
- 150000002829 nitrogen Chemical class 0.000 description 2
- 230000003647 oxidation Effects 0.000 description 2
- 238000007254 oxidation reaction Methods 0.000 description 2
- 230000001590 oxidative effect Effects 0.000 description 2
- 238000007711 solidification Methods 0.000 description 2
- 230000008023 solidification Effects 0.000 description 2
- 230000007704 transition Effects 0.000 description 2
- 238000011282 treatment Methods 0.000 description 2
- 230000003313 weakening effect Effects 0.000 description 2
- HMUNWXXNJPVALC-UHFFFAOYSA-N 1-[4-[2-(2,3-dihydro-1H-inden-2-ylamino)pyrimidin-5-yl]piperazin-1-yl]-2-(2,4,6,7-tetrahydrotriazolo[4,5-c]pyridin-5-yl)ethanone Chemical compound C1C(CC2=CC=CC=C12)NC1=NC=C(C=N1)N1CCN(CC1)C(CN1CC2=C(CC1)NN=N2)=O HMUNWXXNJPVALC-UHFFFAOYSA-N 0.000 description 1
- 238000004220 aggregation Methods 0.000 description 1
- 230000002776 aggregation Effects 0.000 description 1
- 229910052786 argon Inorganic materials 0.000 description 1
- 125000004429 atom Chemical group 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 230000002542 deteriorative effect Effects 0.000 description 1
- 239000002019 doping agent Substances 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 238000010348 incorporation Methods 0.000 description 1
- 239000011261 inert gas Substances 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 230000021332 multicellular organism growth Effects 0.000 description 1
- 125000004433 nitrogen atom Chemical group N* 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 229910021420 polycrystalline silicon Inorganic materials 0.000 description 1
- 238000012805 post-processing Methods 0.000 description 1
- 239000002244 precipitate Substances 0.000 description 1
- 238000001314 profilometry Methods 0.000 description 1
- 230000001737 promoting effect Effects 0.000 description 1
- 238000010926 purge Methods 0.000 description 1
- 230000002040 relaxant effect Effects 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 238000004904 shortening Methods 0.000 description 1
- 230000001629 suppression Effects 0.000 description 1
- 239000002344 surface layer Substances 0.000 description 1
- 238000012546 transfer Methods 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C30—CRYSTAL GROWTH
- C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
- C30B15/00—Single-crystal growth by pulling from a melt, e.g. Czochralski method
- C30B15/02—Single-crystal growth by pulling from a melt, e.g. Czochralski method adding crystallising materials or reactants forming it in situ to the melt
- C30B15/04—Single-crystal growth by pulling from a melt, e.g. Czochralski method adding crystallising materials or reactants forming it in situ to the melt adding doping materials, e.g. for n-p-junction
-
- C—CHEMISTRY; METALLURGY
- C30—CRYSTAL GROWTH
- C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
- C30B15/00—Single-crystal growth by pulling from a melt, e.g. Czochralski method
- C30B15/20—Controlling or regulating
-
- C—CHEMISTRY; METALLURGY
- C30—CRYSTAL GROWTH
- C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
- C30B29/00—Single crystals or homogeneous polycrystalline material with defined structure characterised by the material or by their shape
- C30B29/02—Elements
- C30B29/06—Silicon
-
- C—CHEMISTRY; METALLURGY
- C30—CRYSTAL GROWTH
- C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
- C30B33/00—After-treatment of single crystals or homogeneous polycrystalline material with defined structure
- C30B33/02—Heat treatment
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
- H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
- H01L21/02104—Forming layers
- H01L21/02107—Forming insulating materials on a substrate
- H01L21/02109—Forming insulating materials on a substrate characterised by the type of layer, e.g. type of material, porous/non-porous, pre-cursors, mixtures or laminates
- H01L21/02112—Forming insulating materials on a substrate characterised by the type of layer, e.g. type of material, porous/non-porous, pre-cursors, mixtures or laminates characterised by the material of the layer
- H01L21/02123—Forming insulating materials on a substrate characterised by the type of layer, e.g. type of material, porous/non-porous, pre-cursors, mixtures or laminates characterised by the material of the layer the material containing silicon
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
- H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
- H01L21/02104—Forming layers
- H01L21/02365—Forming inorganic semiconducting materials on a substrate
- H01L21/02518—Deposited layers
- H01L21/02587—Structure
- H01L21/0259—Microstructure
- H01L21/02598—Microstructure monocrystalline
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
- H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
- H01L21/04—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer
- H01L21/18—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer the devices having semiconductor bodies comprising elements of Group IV of the Periodic Table or AIIIBV compounds with or without impurities, e.g. doping materials
- H01L21/30—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26
- H01L21/324—Thermal treatment for modifying the properties of semiconductor bodies, e.g. annealing, sintering
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L22/00—Testing or measuring during manufacture or treatment; Reliability measurements, i.e. testing of parts without further processing to modify the parts as such; Structural arrangements therefor
- H01L22/10—Measuring as part of the manufacturing process
- H01L22/12—Measuring as part of the manufacturing process for structural parameters, e.g. thickness, line width, refractive index, temperature, warp, bond strength, defects, optical inspection, electrical measurement of structural dimensions, metallurgic measurement of diffusions
Landscapes
- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Crystallography & Structural Chemistry (AREA)
- Metallurgy (AREA)
- Materials Engineering (AREA)
- Organic Chemistry (AREA)
- Manufacturing & Machinery (AREA)
- Computer Hardware Design (AREA)
- Microelectronics & Electronic Packaging (AREA)
- Power Engineering (AREA)
- Physics & Mathematics (AREA)
- Condensed Matter Physics & Semiconductors (AREA)
- General Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Crystals, And After-Treatments Of Crystals (AREA)
Abstract
The technical problem is as follows: provided is a method for manufacturing a silicon single crystal, which can form a sufficient BMD even in a device process flow at a low temperature/in a short time at the top and can manufacture a wafer having a high gettering capability with a high yield, in a low/defect-free crystalline silicon substrate and an epitaxial silicon wafer in which precipitation is promoted by nitrogen doping. The solution is as follows: a method for producing a silicon single crystal, characterized by growing a silicon single crystal by pulling the silicon single crystal under a condition that the entire crystal surface is an N-region by the Czochralski method, doping nitrogen with a nitrogen concentration of 2X 1013atoms/cm3 or more and 3.2X 1014atoms/cm3 or less, setting a ratio of a temperature gradient Gc in a crystal center portion and a temperature gradient Ge in a crystal peripheral portion of the silicon single crystal in a pulling axis direction to Ge/Gc > 1, and gradually increasing Ge/Gc in accordance with an increase in nitrogen concentration caused by segregation at the time of pulling the silicon single crystal.
Description
Technical Field
The present invention relates to a method for manufacturing a silicon single crystal, an epitaxial silicon wafer, and a silicon single crystal substrate.
Background
In recent years, there are two major problems in semiconductor devices (Logic, NAND, DRAM, and the like) that are miniaturized.
One of them is that extremely small defects near the wafer surface can also be a factor of device failure, and therefore it is necessary to manufacture a high-quality wafer having few or no defects near the surface as a device operating region.
On the other hand, due to the influence of the low temperature/short time of the process flow, it is difficult to form BMDs (Bulk Micro defects) which are gettering sites of impurity metals that can be sufficiently formed in the device process flow in the past, and this causes a reduction in the device yield.
As a means for satisfying the requirements for defects in the vicinity of the wafer surface in the former, there are: a low/defect-free crystalline single Crystal silicon substrate manufactured in a V-rich region having COP (Crystal Originated Particle defect) caused by holes, an R-OSF region in a ring shape generating oxidation induced stacking fault defects upon thermal oxidation, an N (Neutral: Neutral) region not containing any one of dislocation loops or dislocation clusters caused by intergranular silicon; or an epitaxial silicon wafer or an annealed wafer in which a defect-free layer is formed on a substrate.
Among them, annealed wafers have problems that a post-treatment time required for forming a defect-free layer is long, it is not suitable for mass supply, and the cost is liable to become high.
Epitaxial silicon wafers can form defect-free layers in a relatively short post-treatment time, but additional costs are incurred if compared to low/defect-free crystalline single crystal silicon substrates.
In addition, in epitaxial silicon wafers, in order to offset the additional cost of post-processing, it is common to use high-productivity V-rich crystals that grow crystals at a higher rate than low/defect-free crystals.
In order to increase BMD as a gettering site of an impurity metal, nitrogen doping is known to be effective. However, in the nitrogen-doped V-rich crystal, there are some problems of a decrease in BMD density due to the R-OSF region, EP defect, and EP defect due to the plate-like or rod-like COP when doping is performed at a high nitrogen atom concentration in the outer peripheral portion of the wafer.
In order to avoid these problems, there is a method of growing crystals to be coarser than the product diameter and removing the portion located at the R-OSF by barrel grinding, but this method consumes grinding loss, grinding cost, and time. In addition, as another method, there is a method using a crystal of an N-region not containing R-OSF, but it is difficult to obtain a crystal doped with nitrogen, having a good yield, and not containing R-OSF.
Next, the influence of the latter low-temperature/short-time process flow accompanied by miniaturization will be described.
In the operation of the MOSFET (source/drain current), it is necessary to secure a necessary amount of capacitance of the gate insulating film (dielectric constant of the insulating film × gate area/thickness of the insulating film). Therefore, in the progress of miniaturization of semiconductor devices, the gate insulating film is made thinner to compensate for the portion where the gate length is shortened and the gate area is reduced.
therefore, in a semiconductor device in recent years, the gate insulating film is extremely thin to about 0.5nm of EOT (equivalent oxide film thickness), and uniformity of the gate insulating film is an important factor with respect to reliability of device operation. Therefore, by reducing the temperature and shortening the time of various heat treatments in the device process, the film thickness and quality of the gate insulating film can be made uniform.
However, as a disadvantage of lowering the temperature/time of the device process flow, the BMD formation is less in the device process flow at a low temperature/time, the gettering capability with respect to the impurity metal is reduced, and the device yield is lowered, compared to the BMD which is a gettering site of the impurity metal and is sufficiently formed in the substrate in the device process flow in the related art.
Because of such problems, the following wafers are required: it is easier to form BMD in a top low-temperature/short-time device process flow than before, and high gettering capability can be obtained in a low-temperature/short-time device process flow.
In order to form a sufficient BMD in a device process flow at a low temperature and in a short time, as shown in patent document 1, it is known that a method of increasing thermally stable (large-sized) precipitation nuclei before the device process flow is effective by suppressing the aggregation of holes by nitrogen doping and promoting the formation of precipitation nuclei resulting from excess holes remaining.
However, in an epitaxial silicon wafer using the nitrogen-doped V-rich crystal described above as a substrate, there are problems of a decrease in BMD density and EP defects due to the R-OSF region in the outer peripheral portion of the wafer, and EP defects due to the plate-like or rod-like COP when the wafer is doped with nitrogen at a high concentration.
Documents of the prior art
Patent document
Patent document 1: japanese patent laid-open No. 2001-139396
Patent document 2: japanese patent laid-open No. 2000-53497
Patent document 3: japanese patent laid-open publication No. Hei 11-79889
Patent document 4: japanese patent laid-open publication No. 2000-178099
Patent document 5: WO2002/000969
Patent document 6: japanese patent laid-open No. 2000-16897
Patent document 7: japanese patent laid-open No. 2000-159595
Patent document 8: japanese patent laid-open No. 2008-66357
patent document 9: japanese patent laid-open No. 2007-70132
Patent document 10: japanese patent laid-open publication No. 2016-13957
Disclosure of Invention
Technical problem to be solved
The present invention has been made in view of the above problems, and an object of the present invention is to provide a method for manufacturing a silicon single crystal, which can form a sufficient BMD even in a device process flow at a low temperature and in a short time at the tip and can manufacture a wafer having a high gettering capability with a high yield, in a low/defect-free crystalline silicon substrate in which precipitation (BMD formation) is promoted by nitrogen doping and an epitaxial silicon wafer in which the low/defect-free crystalline silicon substrate is used as a substrate.
(II) technical scheme
in order to solve the above-described problems, the present invention provides a method for growing a silicon single crystal by pulling the silicon single crystal under a condition that the entire crystal surface is an N-region by the czochralski method, wherein the silicon single crystal is grown by doping nitrogen at a nitrogen concentration of 2 × 1013atoms/cm3 or more and 3.2 × 1014atoms/cm3 or less, the ratio of the temperature gradient Gc at the crystal center portion and the temperature gradient Ge at the crystal peripheral portion (crystal outer peripheral portion) in the pulling axis direction of the silicon single crystal is Ge/Gc > 1, and the Ge/Gc is gradually increased in accordance with an increase in the nitrogen concentration due to segregation at the time of pulling the silicon single crystal.
In such a method for manufacturing single crystal silicon, nitrogen is doped at a high concentration to increase thermally stable large-sized precipitation nuclei, thereby realizing a high BMD forming ability (gettering ability) even in a low-temperature and short-time device process flow, and correcting/adjusting a defect distribution change caused by the high concentration of nitrogen due to segregation during crystal growth, thereby manufacturing single crystal silicon in which the R-OSF region is avoided even in a wide nitrogen concentration range over the entire crystal length.
In this case, it is preferable that the Ge/Gc is adjusted by controlling any one of or a combination of two or more of a spacing between a heat shield disposed directly above the raw material melt in the quartz crucible and a liquid surface of the raw material melt, a position of a heater disposed so as to surround the quartz crucible with respect to the liquid surface of the raw material melt, a reduction in magnetic field strength of a magnetic field applying device disposed outside a main chamber of the apparatus for producing single-crystal silicon, and a reduction in position of the magnetic field applying device.
In such a method for adjusting Ge/Gc, the manufacturing apparatus is not greatly changed, and therefore Ge/Gc can be easily adjusted.
In this case, when the Ge/Gc is adjusted by controlling the distance between the heat shield and the liquid surface of the raw material melt, it is preferable that the distance D 'between the heat shield and the liquid surface of the raw material melt when doping nitrogen is changed to a value corresponding to the nitrogen concentration and determined from D'/D being 0.94 — nitrogen concentration/(2.41 × 1015), when the distance between the heat shield and the liquid surface of the raw material melt when doping nitrogen is D under the condition that the entire crystal surface is N-region when doping nitrogen is not performed.
In such a method for adjusting Ge/Gc, the distance between the heat shield and the liquid surface of the raw material melt can be adjusted in accordance with the nitrogen concentration easily and accurately, and thus Ge/Gc can be adjusted more easily.
In this case, it is preferable that the Ge/Gc is adjusted by setting the distance between the heat shield and the liquid surface of the raw material melt to the determined D ' when the determined D ' is larger than 20mm, the distance between the heat shield and the liquid surface of the raw material melt to 20mm when the determined D ' is 20mm or less, and the Ge/Gc is adjusted by lowering one of or a combination of two or more of the position of the heater disposed so as to surround the quartz crucible with respect to the liquid surface of the raw material melt, the strength of the magnetic field applying device disposed outside the main chamber of the apparatus for producing single-crystal silicon, and the position of the magnetic field applying device.
In the method for manufacturing single-crystal silicon, since the distance between the heat shield and the liquid surface of the raw material melt is not excessively reduced, the heat shield does not hinder the lifting of the single-crystal silicon, and single-crystal silicon can be manufactured.
The present invention also provides an epitaxial silicon wafer, comprising an epitaxial layer on a single crystal silicon substrate having an N-region in the entire crystal plane, wherein the single crystal silicon substrate is doped with nitrogen at a nitrogen concentration of 2X 1013atoms/cm3 or more and 3.2X 1014atoms/cm3 or less, the number of defects having a size of 28nm or more is 2/piece or less on average over the entire substrate in a single crystal silicon ingot having a size of 10cm or more, and the density of BMD having an average size of 45nm or more, which is detected after heat treatment at 800 ℃ for 3hr and 1000 ℃ for 2hr, is 1X 108/cm3 or more.
In the case of such an epitaxial silicon wafer, there is no decrease in BMD density and no EP defect due to the R-OSF region, and no EP defect due to the plate-like or rod-like COP when nitrogen is doped at a high concentration.
The present invention also provides a silicon single crystal substrate having a mirror-polished surface, wherein the entire crystal plane is an N-region, wherein nitrogen is doped at a nitrogen concentration of 2 × 1013atoms/cm3 or more and 3.2 × 1014atoms/cm3 or less, wherein the yield of TDDB characteristics is 90% or more, the number of defects having a size of 45nm or more is 2/sheet or less on average over the entire substrate in a silicon single crystal ingot having a size of 10cm or more, and wherein the density of BMDs having an average size of 45nm or more detected after heat treatment at 800 ℃ for 3hr and 1000 ℃ for 2hr is 1 × 108/cm3 or more.
In the case of such a single crystal silicon substrate, there is no decrease in BMD density due to the R-OSF region, and the TDDB characteristics are good.
(III) advantageous effects
In the method for manufacturing a silicon single crystal according to the present invention, nitrogen is doped at a high concentration, thereby increasing thermally stable large-sized precipitation nuclei, realizing a high BMD forming ability (gettering ability) even in a low-temperature/short-time device process flow, and correcting/adjusting a defect distribution variation due to the high concentration of nitrogen caused by segregation during crystal growth, thereby manufacturing a silicon single crystal in which the R-OSF region is avoided even in a wide nitrogen concentration range in the entire crystal length.
In addition, the epitaxial silicon wafer of the present invention does not cause a decrease in BMD density and EP defects due to the R-OSF region, and also does not cause EP defects due to plate-like or rod-like COPs obtained by doping nitrogen at a high concentration. In addition, in the single crystal silicon substrate of the present invention, there is no decrease in BMD density due to the R-OSF region, and the TDDB characteristics are good.
Drawings
Fig. 1 is a diagram showing an example of an apparatus for manufacturing a silicon single crystal by the czochralski method, which can be used in the present invention.
Fig. 2 is a defect distribution diagram in the pulling axis direction of single crystal silicon with the radial position of the single crystal silicon as the abscissa in the case where single crystal silicon is produced under the pulling conditions of comparative example 1, comparative example 2, and example 1.
Fig. 3 is an EP defect distribution diagram showing the results of defect evaluation of the epitaxial wafer in comparative example 3.
Fig. 4 is an EP defect distribution diagram showing the results of defect evaluation of the epitaxial wafer in comparative example 4.
fig. 5 is an EP defect distribution diagram showing the results of defect evaluation of the epitaxial wafer in example 2.
Fig. 6 is a graph showing the TDDB characteristic evaluation results of the single crystal silicon substrate in comparative example 5.
Fig. 7 is a graph showing the TDDB characteristic evaluation results of the single crystal silicon substrate in comparative example 6.
Fig. 8 is a graph showing the TDDB characteristic evaluation results of the single crystal silicon substrate in example 3.
Detailed Description
The present invention will be described in detail below with reference to the accompanying drawings as an example of an embodiment, but the present invention is not limited thereto.
The present inventors have also described a method for producing a silicon single crystal, an epitaxial silicon wafer, and a silicon single crystal substrate according to the present invention, in conjunction with the contents of research and experiments before the present inventors found the present invention.
As described above, in an epitaxial silicon wafer using a nitrogen-doped V-rich crystal as a substrate, there are some problems of a BMD density decrease and an EP defect due to an R-OSF region in the outer peripheral portion of the wafer, and an EP defect due to a plate-like or rod-like COP when nitrogen doping is performed at a high concentration.
In contrast, the inventors of the present application have considered that if a low/defect-free crystalline single crystal silicon substrate manufactured in a nitrogen-doped n (neutral) region or an epitaxial silicon wafer using the low/defect-free crystalline single crystal silicon substrate as described in patent document 2 is used as a substrate, the problem of a decrease in BMD density due to an R-OSF region can be solved, and the low/defect-free requirements of thermally stable (large-sized) precipitation nuclei due to the increase in nitrogen doping and the device operating region in the surface layer of the wafer can be satisfied at the same time.
However, based on such an idea, the inventors of the present application have made earnest studies to solve the problem that when a low/defect-free crystal is produced in an N-region by the czochralski method by doping nitrogen, it is difficult to avoid the R-OSF region over the entire length in the crystal growth axis direction, and the yield in one crystal is extremely low.
Specifically, even if a growth method is used in which an R-OSF region is avoided and an N-region is collected at a high yield over the entire length in the crystal growth axis in the production of a low/defect-free crystal in an N-region not doped with nitrogen (patent documents 3 to 7), a low/defect-free crystal in an N-region in which an R-OSF is avoided can be produced only in a range in which the nitrogen concentration is low in the entire length in the crystal growth axis when doped with nitrogen.
As shown in patent document 8 relating to the production of low/defect-free crystals in the N-region doped with nitrogen, in a nitrogen concentration of 3 × 1013atoms/cm3 or less which is excellent in TDDB characteristics and can provide wafers with a small variation in BMD density, thermally stable (large-sized) precipitation nuclei are not sufficiently increased before the device process flow, and the requirement of high BMD density (gettering capability) in the device process flow for a low temperature at the top and a short time is not satisfied.
In addition, the following problems arise: if the nitrogen concentration is sufficiently set to a high concentration of 3 × 1013atoms/cm3 or more in order to increase thermally stable (large-sized) precipitation nuclei before the device process flow, even if the difference between the temperature gradient Gc at the crystal center and the temperature gradient Ge at the crystal periphery is made to be Δ G-Gc ≦ 5 ℃/cm as described in patent document 2, an R-OSF region is easily generated at the wafer periphery even if the pull rate is adjusted in accordance with the nitrogen concentration change due to segregation during crystal growth as described in patent document 9, and if the crystal growth rate is reduced in order to avoid the R-OSF region, the number of BMDs at the wafer center is reduced to cause non-uniformity of the BMD density (gettering capability) in the plane, or if the case is, a dislocation loop is present at the wafer center, I-rich regions of dislocation clusters.
As a result of earnest studies for solving these problems, the inventors of the present application have found that, in the production of a low/defect-free crystal in an N-region doped with nitrogen, a defect region changes in the peripheral portion of the crystal (outer peripheral portion of the crystal) depending on the nitrogen concentration.
Next, the change of the defect region in the peripheral portion of the crystal corresponding to the nitrogen concentration will be specifically described.
As described in patent document 10, a change in defect distribution due to a factor other than the thermal environment of the crystal can be understood as being caused by outward diffusion of point defects. In the peripheral portion of the crystal, the influence of outward diffusion of point defects such as interstitial silicon and holes becomes large, and outward diffusion of holes has an effect of reducing the concentration of residual holes in the peripheral portion of the crystal. However, if nitrogen is doped at a high concentration, outward diffusion of holes can be suppressed by forming pairs of nitrogen and holes (NV pairs).
Therefore, in the case of doping with nitrogen, the higher the nitrogen concentration, the higher the residual hole concentration in the peripheral portion of the crystal, and the defect region in the peripheral portion of the crystal is shifted toward the R-OSF region side, as compared with the case of not doping with nitrogen.
The inventors of the present application have found that when a low/defect-free crystal in an N-region is produced by doping nitrogen, an R-OSF region is easily generated in the wafer peripheral portion, and if the crystal growth rate is lowered in order to avoid the R-OSF region, BMD in the wafer central portion is reduced to cause non-uniformity of BMD density (gettering capability) in the plane, or if the case may be, a problem of an I-rich region having dislocation loops and dislocation clusters in the wafer central portion, and the influence of suppressing the outward diffusion of holes is observed from a nitrogen concentration of 2 × 1013atoms/cm3, and if the nitrogen concentration is 3 × 1013atoms/cm3 or more, the crystal yield is significantly increased.
the present invention has been made by earnest studies by the inventors of the present application as described above, and has been accomplished by finding that, in a low/defect-free crystalline silicon substrate manufactured from a nitrogen-doped N-region and an epitaxial silicon wafer using the low/defect-free crystalline silicon substrate as a substrate, by performing crystal growth of a single crystal silicon taking into consideration the influence of segregation of nitrogen, and by using the grown single crystal silicon to manufacture the single crystal silicon substrate and the epitaxial silicon wafer using the single crystal silicon substrate as a substrate, the problems caused by the R-OSF region can be completely eliminated, and the low/defect-free requirements for increasing the thermally stable (relatively large-sized) precipitation nuclei generated by nitrogen doping and the wafer surface device operating region can be satisfied at the same time, thereby achieving the present invention.
First, a method for growing a silicon single crystal according to the present invention will be described in detail.
The present invention is a method for growing a silicon single crystal by pulling the silicon single crystal under a condition that the entire crystal surface is an N-region by the Czochralski method, wherein when the silicon single crystal is grown, nitrogen is doped at a nitrogen concentration of 2X 1013atoms/cm3 or more and 3.2X 1014atoms/cm3 or less so that the ratio of the temperature gradient Gc in the crystal center portion and the temperature gradient Ge in the crystal peripheral portion in the pulling axis direction of the silicon single crystal is Ge/Gc > 1, and Ge/Gc is gradually increased in accordance with an increase in the nitrogen concentration due to segregation at the time of pulling the silicon single crystal. Here, the crystal peripheral portion is appropriately determined in a region having a diameter of about 1/3 or less from the outer peripheral end of the single crystal silicon.
In the method for manufacturing a silicon single crystal, nitrogen is doped at a high concentration, so that thermally stable large-sized precipitation nuclei can be increased, thereby realizing a high BMD forming ability (gettering ability) even in a low-temperature and short-time device process flow, and a change in defect distribution due to the high concentration of nitrogen caused by segregation during crystal growth can be corrected and adjusted, thereby manufacturing a silicon single crystal in which the R-OSF region is avoided even in a wide nitrogen concentration range over the entire crystal length.
further, by using the single crystal silicon manufactured by the method for manufacturing single crystal silicon of the present invention, in a single crystal silicon substrate and an epitaxial silicon wafer using the single crystal silicon substrate, defects caused by an R-OSF region due to high nitrogen concentration doping are eliminated, and a wafer having high BMD formation capability (gettering capability) can be obtained with high yield even in a device process flow at low temperature and in a short time.
When the temperature distribution during crystal growth is adjusted so as to obtain an N-region over the entire crystal length and the entire surface without doping nitrogen, if the nitrogen doping amount is made to be a nitrogen concentration smaller than 2X 1013atoms/cm3, the defect distribution is slightly affected, and the TDDB characteristics in the state of being a single crystal silicon substrate or the occurrence of EP defects on an epitaxial silicon wafer using a single crystal silicon substrate hardly causes problems.
However, if the nitrogen concentration reaches 3X 1013atoms/cm3, the influence on the defect distribution is observed, and the TDDB characteristics in the state of the single crystal silicon substrate starts to deteriorate and EP defects on the epitaxial silicon wafer using the single crystal silicon substrate start to occur. As shown in patent document 9, even if the pull rate is adjusted in accordance with the nitrogen concentration (the pull rate is adjusted in accordance with an increase in the nitrogen concentration by delaying the pull rate), a sufficient BMD density is not obtained in the heat treatment at a low temperature and in a short time as used in the top device process flow at the nitrogen concentration.
When the nitrogen concentration is 3 × 1013atoms/cm3 or more, it is effective to obtain a sufficient BMD density in a low-temperature/short-time heat treatment such as a top device process flow, but the defect distribution changes greatly particularly in the peripheral portion of the crystal, and TDDB characteristics in a state of being a single-crystal silicon substrate further deteriorate, and EP defects are generated on an epitaxial silicon wafer seriously. In this nitrogen concentration range, the adjustment of the delayed pull rate with respect to the increase of the nitrogen concentration in patent document 9 cannot sufficiently improve, and if the delayed pull rate is so high that the TDDB characteristic in the case of a single crystal silicon wafer at the crystal outer peripheral portion or the occurrence of EP defects on an epitaxial silicon wafer can be improved, the BMD at the wafer central portion decreases to cause unevenness in the BMD density (gettering capability) in the plane, and in some cases, an I-rich region having dislocation loops or dislocation clusters at the wafer central portion is formed, and EP defects are generated at the central portion.
More preferably, although a sufficient BMD density is obtained in a heat treatment at a low temperature and in a short time such as a top device process flow in a nitrogen concentration of 6 × 1013atoms/cm3 or more, the defect distribution changes more greatly particularly in the peripheral portion of the crystal, the TDDB characteristic in a state of being a single crystal silicon substrate deteriorates, and EP defects are more likely to occur in an epitaxial silicon wafer using the single crystal silicon substrate. In this nitrogen concentration range, the delay in the adjustment of the pulling rate with respect to the increase in the nitrogen concentration in patent document 9 cannot be sufficiently improved, and if the pulling rate is delayed until the TDDB characteristic in a state of being a single crystal silicon substrate at the peripheral portion of the crystal can be improved and the degree of generation of EP defects on an epitaxial silicon wafer using a single crystal silicon substrate, the entire N-region cannot be maintained early, and an I-rich region having dislocation loops and dislocation clusters at the central portion of the wafer becomes an I-rich region, and EP defects occur at the central portion originating from the I-rich region.
In the method for producing a silicon single crystal according to the present invention, a wafer can be obtained which has good TDDB characteristics when a silicon single crystal substrate produced using a silicon single crystal produced before the optimum nitrogen concentration of 3.2 × 1014atoms/cm3 for obtaining a sufficient BMD density in a low-temperature/short-time heat treatment such as a top device process flow is used, and which does not cause EP defects in a state in which the silicon single crystal substrate is used as an epitaxial silicon wafer.
In the present invention, a silicon single crystal manufacturing apparatus 14 such as that shown in fig. 1 is used, and silicon single crystal can be grown by pulling the silicon single crystal by the czochralski method under the condition that the entire crystal surface is an N-region. Although such a single crystal silicon manufacturing apparatus is described with reference to fig. 1, the single crystal manufacturing apparatus that can be used in the present invention is not limited to this.
The apparatus for manufacturing single crystal silicon 14 shown in fig. 1 is constituted by a main chamber 1 and a pulling chamber 2 communicating with the main chamber 1 in appearance. A graphite crucible 6 and a quartz crucible 5 are provided inside the main chamber 1. A heater 7 is provided so as to surround the graphite crucible 6 and the quartz crucible 5, and the raw material polycrystalline silicon stored in the quartz crucible 5 is melted by the heater 7 to become the raw material melt 4. Further, a heat insulating member 8 is provided to prevent radiant heat from the heater 7 from affecting the main chamber 1 and the like.
The heat shield 12 is disposed at a predetermined interval above the melt surface of the raw material melt 4 so as to face the melt surface and blocks radiant heat from the melt surface of the raw material melt 4. After the seed crystal is immersed in the crucible, the rod-shaped single crystal rod 3 is lifted from the raw material melt 4. The crucible can be moved up and down along the crystal growth axis, and the height of the melt surface of the raw material melt 4 can be kept substantially constant by moving the crucible up so as to compensate for the lowered portion of the liquid surface of the raw material melt 4 that decreases as the single crystal grows.
During the single crystal growth, inert gas such as argon is introduced as purge gas from the gas inlet 10, passes between the single crystal rod 3 and the gas rectifying cylinder 11, passes between the heat shield 12 and the melt surface of the raw material melt 4, and is discharged from the gas outlet 9. The pressure in the chamber during pulling is controlled by controlling the flow rate of the introduced gas and the amount of the gas discharged by the pump and the valve.
In addition, when the crystal is grown by the CZ method, the magnetic field may be applied by the magnetic field applying device 13.
The reason why the temperature gradient Gc of the crystal center portion and the temperature gradient Ge of the crystal peripheral portion in the pulling axis direction of the single-crystal silicon can be made Ge/Gc > 1 and the Ge/Gc can be gradually increased in accordance with the increase in the nitrogen concentration due to segregation during pulling of the single-crystal silicon will be described.
As the nitrogen concentration increases by segregation, the formation of NV pairs increases, and the diffusion of voids (vacacy) outward from the outer surface of the crystal decreases, and the concentration of residual vacacy around the crystal increases, so that the vicinity of the crystal shifts to a defect region where vacacy predominates.
In a state where the defect region around the crystal is shifted to the Vacancy dominant side by the segregation of nitrogen, the non-uniformity of the BMD distribution or the shift of the defect region on the outer peripheral portion from the N-region to the R-OSF region is caused by the residual Vacancy concentration around the crystal being higher than the residual Vacancy concentration from the center to R/2 (where R is the radius of the silicon single crystal) of the crystal.
In order to avoid this, it is effective to adjust the amount of vacacy taken into the solid-liquid interface in advance so that the residual vacacy is increased in the vicinity of the crystal due to the influence of NV on the formation.
That is, the amount of vacacy taken in the periphery of the crystal is reduced as compared with the amount of vacacy taken in the portion other than the periphery of the crystal in the solid-liquid interface.
As for the incorporation of point defects during the growth of single-crystal silicon, Voronkov (Japanese: ボ ロ ン コ フ) theory is widely known, and the point defect concentration is determined depending on the ratio V/G of the growth rate V of single-crystal silicon to the temperature gradient G in the vicinity of the interface.
The larger the V/G, the higher the Vacanty concentration at the solid-liquid interface, and the smaller the V/G, the higher the Interstical-Si concentration at the solid-liquid interface.
Therefore, according to the vornkov theory, the residual Vacancy due to the influence of NV on the formation of the crystal is set so that V/Ge around the crystal becomes smaller than V/Gc at the center in advance in the portion where the number of crystals increases. Namely, V/Gc > V/Ge.
In stable single crystal growth, the growth rate V on the plane perpendicular to the crystal growth axis direction is the same from the crystal center to the crystal periphery, and therefore 1/Gc > 1/Ge and Ge/Gc > 1 are effective, and as the nitrogen concentration increases, the residual Vacancy can be offset so that Ge/Gc gradually increases in the portion where the amount of residual Vacancy increases in the crystal periphery due to the influence of NV on the formation. In this case, if Ge/Gc is 1.2 or less, the entire surface of the wafer can be more reliably free of defects, which is preferable.
The Ge/Gc is preferably adjusted by controlling any one of or a combination of two or more of the distance between the heat shield 12 disposed directly above the raw material melt in the quartz crucible 5 and the liquid surface of the raw material melt, the position of the heater 7 disposed so as to surround the quartz crucible 5 being lowered with respect to the liquid surface of the raw material melt, the reduction of the magnetic field strength of the magnetic field applying device 13 disposed outside the main chamber 1 of the apparatus for producing single-crystal silicon, and the lowering of the position of the magnetic field applying device 13. In such a method for adjusting Ge/Gc, the manufacturing apparatus is not greatly changed, and therefore Ge/Gc can be easily adjusted.
The reason why the Ge/Gc becomes large by such a Ge/Gc adjusting method will be described.
Among the methods of increasing Ge/Gc, there are two methods of increasing Ge and decreasing Gc.
In order to increase Ge, it is effective to reduce heat radiation (heat supply by radiation) toward the side surface portion of the crystal in the upper portion of the solid-liquid interface. As specific methods thereof, there are: a method of reducing the distance between the heat shield 12 directly above the raw material melt 4 and the liquid surface of the raw material melt 4 and insulating a part of heat radiation from the heater 7 for heating of a heat source disposed outside the graphite crucible 6; a method of reducing heat radiation toward the upper part of the solid-liquid interface by arranging the heater 7 for heating the heat source at a low position with respect to the liquid surface of the raw material melt 4.
Although Ge slightly changes due to heat conduction of gas in the furnace and convection heat transfer by gas flow, control by heat radiation is important in the environment of manufacturing single crystal silicon by the CZ method mainly in a high-temperature environment having a melting point of 1420 ℃.
the Gc is reduced by lowering the height of the solid-liquid interface (melting point isotherm) and relaxing the temperature gradient with the upper part of the solid-liquid interface, thereby reducing the suppression of convection of the melt at the lower part of the crystal growth interface by the magnetic field and facilitating the removal of the latent heat of solidification generated during the crystal growth by convection. If the latent heat of solidification can be removed by convection, the height of the solid-liquid interface is lowered by heat balance as compared with the case where it is not. At this time, the melting point isotherm of the outermost periphery of the crystal is always connected to the surface of the raw material melt 4, and thus Gc is selectively decreased.
As a method of reducing the convection of the melt at the lower portion of the crystal growth interface by the magnetic field, there is a method of reducing the magnetic field strength while keeping the magnetic field at the same position. In addition, when the magnetic field strength is fixed, there is a method of separating the magnetic field position from the surface position of the raw material melt 4. When both the magnetic field position and the magnetic field strength can be changed, a method of weakening the magnetic field strength and a method of changing the magnetic field position may be combined.
As a method of reducing the height of the solid-liquid interface, the solid-liquid interface can be reduced even if crystal rotation is weakened, but since the dopant concentration and the oxygen concentration in the surface are not uniform, a method of weakening the magnetic field strength in the solid-liquid interface portion is preferable.
Further, when adjusting Ge/Gc by controlling the distance between the heat shield 12 and the liquid surface of the raw material molten liquid 4, it is preferable that the distance between the heat shield 12 and the liquid surface of the raw material molten liquid 4 under the condition that the entire crystal surface is N-region when not doped with nitrogen is D, and the distance between the heat shield 12 and the liquid surface of the raw material molten liquid 4 when doped with nitrogen is changed so as to correspond to the nitrogen concentration and be D 'obtained by setting D'/D to 0.94 — nitrogen concentration/(2.41 × 1015).
In this method of adjusting Ge/Gc, the Ge/Gc can be adjusted by adjusting the distance between the heat shield 12 and the liquid surface of the raw material melt 4 in accordance with the nitrogen concentration, and therefore, the Ge/Gc can be adjusted more easily and accurately.
How to derive the relational expression of D' is described below.
First, as the interval D between the heat shield 12 and the melt immediately above the raw material melt 4 in which N-regions are obtained over the entire surface, in the case where nitrogen is not doped, the conditions other than nitrogen are the same as those in the case where nitrogen is doped at a nitrogen concentration of 2 to 2.2X 1013, 3 to 3.2X 1013, 6 to 6.2X 1013, 1 to 1.2X 1014, 1.5 to 1.7X 1014, 2.2 to 2.4X 1014, 3 to 3.2X 1014atoms/cm3, respectively, so that the pulling rate is gradually decreased in the straight growth and a sample parallel to the crystal growth axis is cut out from the obtained single crystal silicon ingot so that the defect region V-rich, R-OSF region, Nv region, Ni region, and I-rich region are included in the single crystal silicon ingot, and heat treatment is performed at 800 ℃ for 4hr and 1000 ℃ for 16hr in a humid oxidizing atmosphere, and changes in defect distribution based on each nitrogen concentration were investigated using X-ray surface morphology measurement (XRT).
Secondly, the distance between the heat shield 12 directly above the raw material melt 4 and the liquid surface of the raw material melt 4 is changed for each nitrogen concentration, and the distance D' between the heat shield 12 directly above the raw material melt 4 and the liquid surface of the raw material melt 4 is obtained, which provides the same N-region distribution as that obtained in the case of not doping nitrogen.
Thirdly, a relational expression of a change in the ratio of the distance D 'between the heat shield 12 and the liquid surface of the raw material melt 4 with respect to the nitrogen concentration to the distance D is obtained by a least square method, and D'/D is 0.94-nitrogen concentration/(2.41 × 1015).
Preferably, when the determined D ' is larger than 20mm, Ge/Gc is adjusted by setting the distance between the heat shield 12 and the liquid surface of the raw material melt 4 to the determined D ', and when the determined D ' is 20mm or less, the distance between the heat shield 12 and the liquid surface of the raw material melt 4 is set to 20mm, and the Ge/Gc is adjusted by lowering the position of the heater 7 disposed so as to surround the quartz crucible 5 with respect to the liquid surface of the raw material melt 4, by reducing the magnetic field strength of the magnetic field applying device 13 disposed outside the main chamber 1 of the apparatus for producing single-crystal silicon, and by lowering the position of the magnetic field applying device 13.
In the method for manufacturing single-crystal silicon, when the distance between the heat shield 12 and the liquid surface of the raw material melt 4 is as small as 20mm or less, the single-crystal silicon can be manufactured without being hindered from being lifted up by, for example, the heat shield 12 coming into contact with the raw material melt 4.
According to the method of the present invention described above, there is provided an epitaxial silicon wafer characterized by having an epitaxial layer on a single crystal silicon substrate having an N-region in the entire crystal plane, doping the single crystal silicon substrate with nitrogen at a nitrogen concentration of 2 × 1013atoms/cm3 or more and 3.2 × 1014atoms/cm3 or less, wherein the average number of defects having a size of 28nm or more is 2/piece or less (0/piece or more and 2/piece or less) over the entire substrate in a single crystal silicon ingot having a size of 10cm or more, and wherein the density of BMDs having an average size of 45nm or more detected after heat treatment of 3hr at 800 ℃ and 2hr at 1000 ℃ is 1 × 108/cm3 or more. In this case, if the BMD density is 1X 1010/cm3 or less, the BMD density is moderate, and there is no problem such as wafer warpage, and the like, so that it is preferable.
In the case of such an epitaxial silicon wafer, there is no decrease in BMD density and no EP defect due to the R-OSF region, and no EP defect due to the plate-like or rod-like COP caused by the high-concentration nitrogen doping. Further, by performing the heat treatment at 800 ℃ for 3hr and 1000 ℃ for 2hr, an epitaxial silicon wafer having a sufficient BMD density and uniform in-plane BMD quality can be formed.
Further, the method of the present invention can provide a silicon single crystal substrate having a mirror-polished surface, wherein the entire crystal plane is an N-region, nitrogen is doped at a nitrogen concentration of 2 × 1013atoms/cm3 or more and 3.2 × 1014atoms/cm3 or less, the yield of TDDB characteristics is 90% or more, the number of defects having a size of 45nm or more is 2/sheet or less (0/sheet or more and 2/sheet or less) on average over the entire substrate in a silicon single crystal ingot having a size of 10cm or more, and the density of BMDs having an average size of 45nm or more, which are detected after heat treatment at 800 ℃ for 3hr and 1000 ℃ for 2hr, is 1 × 108/cm3 or more. In this case, if the BMD density is 1X 1010/cm3 or less, the BMD density is moderate, and there is no problem such as wafer warpage.
In the case of such a single crystal silicon substrate, there is no decrease in BMD density due to the R-OSF region, and the TDDB characteristics are good. Further, by performing heat treatment at 800 ℃ for 3hr and 1000 ℃ for 2hr, a single crystal silicon substrate having a sufficient BMD density and uniform in-plane BMD quality can be formed.
[ examples ] A method for producing a compound
The present invention will be specifically described below with reference to examples and comparative examples, but the present invention is not limited thereto.
Comparative example 1
410kg of raw material was melted in a 32-inch (812.8mm) crucible without doping nitrogen, and crystal production of 300mm in diameter was carried out under application of a magnetic field of 4000G. At this time, the interval (50mm) between the heat shield and the raw material melt directly above the raw material melt, the position of the heater, and the position of the magnetic field applying device were adjusted in advance, and the temperature distribution during crystal growth was adjusted so that an n (neutral) region was obtained over the entire crystal length. Under these conditions, the pulling rate was gradually decreased during the straight body growth, and a sample parallel to the crystal growth axis direction was cut out from the obtained single crystal silicon ingot so that the defect region V-rich, R-OSF region, Nv region, Ni region, and I-rich region (each region from V-rich to I-rich) were included in the single crystal silicon ingot, and heat treatment was performed at 800 ℃ for 4hr and at 1000 ℃ for 16hr under a humid oxidizing atmosphere, and the defect distribution was evaluated by XRT (X-ray profilometry).
Comparative example 2
A single crystal silicon ingot was produced by doping nitrogen at the same interval (50mm) between the heat shield and the raw material melt as in comparative example 1, immediately above the raw material melt, at the heater position, at the magnetic field position, and at the magnetic field strength, and gradually decreasing the pulling rate during the straight growth, thereby producing a defect distribution evaluation silicon ingot including regions from V-rich to I-rich in the silicon single crystal ingot. Single crystal silicon ingots were produced with a nitrogen concentration of 2X 1013atoms/cm3 level (nitrogen concentration in single crystal silicon ingot 2X 1013atoms/cm3), 3X 1013atoms/cm3 level (nitrogen concentration in single crystal silicon ingot 3X 1013atoms/cm3), 6X 1013atoms/cm3 level (nitrogen concentration in single crystal silicon ingot 6X 1013atoms/cm3), and 3X 1014atoms/cm3 level (nitrogen concentration in single crystal silicon ingot 3X 1014-3.2X 1014atoms/cm3), and the defect distribution at each nitrogen concentration was evaluated in the same manner as in comparative example 1.
(example 1)
The same procedure as in comparative example 2 was carried out, except that the distance between the heat shield directly above the raw material melt and the liquid surface of the raw material melt was changed to D 'determined from D'/D being 0.94-nitrogen concentration/2.41 × 1015. By changing the distance between the heat shield directly above the raw material melt and the liquid surface of the raw material melt in this manner, the temperature gradient Gc in the crystal center and the temperature gradient Ge in the crystal peripheral portion in the pulling axis direction of the single-crystal silicon are set to Ge/Gc > 1, and Ge/Gc is gradually increased in accordance with the increase in the nitrogen concentration due to segregation during pulling of the single-crystal silicon. Here, D is 50 mm. The distance between the heat shield directly above the raw material melt and the liquid surface of the raw material melt was adjusted to 46.6mm (D'/D is 0.932) at a level of 2X 1013atoms/cm3 (nitrogen concentration in the single crystal silicon ingot is 2-2.2X 1013atoms/cm3), d 'is 46.3mm (D'/D is 0.926) at a level of 3X 1013atoms/cm3 (nitrogen concentration in the silicon single crystal ingot is 3-3.2X 1013atoms/cm3), d 'is 45.8mm (D'/D is 0.916) at the level of 6X 1013atoms/cm3 (the nitrogen concentration in the silicon single crystal ingot is 6-6.2X 1013atoms/cm3), a single crystal silicon ingot was produced at a level of 3X 1014atoms/cm3 (nitrogen concentration in the single crystal silicon ingot was 3-3.2X 1014atoms/cm3) with D 'of 40.8mm (D'/D of 0.816), the defect distribution was evaluated by adjusting the distance between the heat shield directly above the raw material melt and the liquid surface of the raw material melt at each nitrogen concentration. The change of the distance between the heat shield directly above the raw material melt and the liquid surface of the raw material melt is performed by changing the height position of the crucible.
Fig. 2 shows a defect distribution diagram in the pulling axis direction of single crystal silicon with the radial position of the single crystal silicon as the abscissa in the case where the single crystal silicon is produced under the pulling conditions of comparative example 1, comparative example 2, and example 1.
In comparative example 1, the defect distribution of comparative example 2 doped with nitrogen was such that, in the levels of 2 × 1013atoms/cm3, 3 × 1013atoms/cm3, 6 × 1013atoms/cm3 and 3 × 1014atoms/cm3, respectively, as the nitrogen concentration increased, the outward diffusion of the holes (vacacy) during crystal growth decreased due to the formation of pairs of nitrogen and holes (NV pairs), and therefore the defect region on the outer peripheral side of the crystal shifted to the dominant side of vacacy (high V/G side) and changed to a distribution in which the R — OSF region relaxed in the outer peripheral portion.
In such a defect distribution, when a wafer is fabricated, a large number of defect regions having significantly different residual vacacy concentrations are mixed in the surface (R — OSF region + R/2 in the outer peripheral portion to Nv region in the central portion, Nv region + R/2 in the outer peripheral portion to Ni region in the central portion, R — OSF region + R/2 in the outer peripheral portion to Nv region + Ni region in the central portion), and even if all of the defect regions are the same in the surface, the residual vacacy in the outer periphery of the wafer increases. Therefore, the BMD (bulk Micro defect) density in the wafer surface after the heat treatment at 800 ℃ for 3hr and 1000 ℃ for 2hr greatly differs, which is a factor of the reduction of the device yield due to the insufficient gettering capability in the low BMD region in the wafer surface.
On the other hand, in example 1 of the present invention, since the defect distribution change accompanying the increase of the nitrogen concentration (the defect region on the outer peripheral side of the crystal is shifted to the vacacy dominant side and the R — OSF region changes to the relaxed distribution in the outer peripheral portion) is corrected, and the entire surface of the wafer can be made uniform when the wafer is manufactured, the BMD density in the wafer surface after the heat treatment at a low temperature for a short time, for example, 3hr at 800 ℃ and 2hr at 1000 ℃ can be controlled to be uniform. Further, the device yield and the wafer yield were good, even when the TDDB characteristics in the state of the single crystal silicon substrate due to the presence of the R-OSF region in a mixed state were prevented from deteriorating, and the EP defect was prevented when the produced single crystal silicon substrate was used as a substrate for an epitaxial silicon wafer.
Further, the present invention is very effective in obtaining a product with a high yield from the entire length of a long crystal because nitrogen gradually increases in concentration as the crystal grows by the segregation phenomenon (equilibrium segregation coefficient 7X 10-4) during the crystal growth.
[ Change in yield of epitaxial silicon wafer (transition in quality of single silicon crystal) ]
next, the effect obtained when the present invention is applied to actual product manufacturing will be described in detail by taking the yield of an epitaxial wafer as an example.
Comparative example 3
410kg of the raw material was melted in a 32-inch (812.8mm) crucible, and crystal production of 300mm diameter was carried out under application of 4000G magnetic field. Three crystals each having a nitrogen concentration of 2X 1013atoms/cm3 (comparative example 3-2) and a nitrogen concentration of 1X 1014-3.2X 1014atoms/cm3 (comparative example 3-3) were produced in the straight product collecting section under the conditions that the distance between the heat shield directly above the raw material melt and the liquid surface of the raw material melt was 50mm and the position of the heater and the position of the magnetic field applying device during crystal growth were adjusted so that an N-region was obtained over the entire crystal length in the case of no nitrogen doping, and that the nitrogen concentration was 2X 1013atoms/cm3 and 3 (comparative example 3-3) were obtained, and a single crystal silicon substrate was produced from the obtained crystals and used as a substrate for an epitaxial silicon wafer, thereby producing an epitaxial silicon wafer. For the defect evaluation of the epitaxial silicon wafer, the defect of 28nm or more was evaluated in the Oblique mode using SP3 manufactured by KLA Tencor. The epitaxial wafer thus produced was subjected to a heat treatment at 800 ℃ for 3 hours and 1000 ℃ for 2 hours, and then the BMD density of 30nm or more was measured by an infrared scattering method.
Comparative example 4
An epitaxial silicon wafer was produced in the same manner as in comparative example 3-2 (comparative example 4-1) and comparative example 3-3 (comparative example 4-2) except that the distance between the heat shield directly above the raw material melt and the liquid surface of the raw material melt was kept at 50mm, and the pulling rate was adjusted in accordance with the nitrogen concentration (adjustment was made with the pulling rate delayed with respect to the increase in the nitrogen concentration) as shown in patent document 9, and defect evaluation was performed in the same manner as in comparative example 3. The epitaxial wafer thus produced was subjected to a heat treatment at 800 ℃ for 3 hours and 1000 ℃ for 2 hours, and then the BMD density of 30nm or more was measured by an infrared scattering method.
(example 2)
The distance D ' between the heat shield directly above the raw material melt and the liquid surface of the raw material melt was set to D ' determined from the D '/D being 0.94-nitrogen concentration/(2.41X 1015). Example 2-1 an epitaxial wafer was produced and defect evaluation was performed in the same manner as in comparative example 4-2 except that the distance between the heat shield directly above the raw material melt and the liquid surface of the raw material melt was adjusted from 46.6mm to 45.8mm at a nitrogen concentration of 2 × 1013-6 × 1013atoms/cm3 in order to cancel the influence of nitrogen segregation during crystal growth, in order to change the nitrogen concentration under segregation caused by the nitrogen binding to the Tail side from the side of the crystal cone, and example 2-2 was the same as comparative example 4-1 except that the distance between the heat shield directly above the raw material melt and the liquid surface of the raw material melt was adjusted from 44.9mm to 40.3mm at a nitrogen concentration of 1 × 1014-3.2 × 1014atoms/cm3, and comparative example 4-2 was used. The epitaxial wafer thus produced was subjected to a heat treatment at 800 ℃ for 3 hours and 1000 ℃ for 2 hours, and then the BMD density of 30nm or more was measured by an infrared scattering method. By changing the distance between the heat shield directly above the raw material melt and the liquid surface of the raw material melt in this manner, the temperature gradient Gc in the crystal center and the temperature gradient Ge in the crystal peripheral portion in the pulling axis direction of the single-crystal silicon are set to Ge/Gc > 1, and Ge/Gc is gradually increased in accordance with the increase in the nitrogen concentration due to segregation at the time of pulling the single-crystal silicon.
Fig. 3, 4 and 5 are EP defect distribution diagrams showing the results of defect evaluation of the epitaxial wafers in comparative example 3, comparative example 4 and example 2, respectively. In the top-end devices with high process flow cost, even if there are several defects on average in one wafer, the resulting faulty chips become a big problem.
In comparative example 3, although the generation of EP defects did not substantially cause any problem until the nitrogen concentration was 2X 1013atoms/cm3, the generation of EP defects was observed when the nitrogen concentration was sufficiently high, i.e., 3X 1013atoms/cm3, in order to increase thermally stable (large-sized) precipitation nuclei. In addition, when the nitrogen concentration is higher than 3X 1013atoms/cm3 or more, EP defects increase with the increase of the nitrogen concentration, and the nitrogen concentration cannot be used in the top device with high process flow cost. In comparative examples 3-1, 3-2 and 3-3, the BMD densities of the epitaxial silicon wafers after the heat treatment at 800 ℃ for 3hr and 1000 ℃ for 2hr were 1 to 3X 107, 1 to 2X 108 and 2.5 to 15X 108/cm3, respectively. When the nitrogen concentration is 2X 1013atoms/cm3 or more, the BMD density of the top device, which is considered to have sufficient gettering ability and has an average size of 45nm or more, can be 1X 108 or more.
In comparative example 4, the improvement effect was observed by decreasing the pull rate with respect to the increase in the nitrogen concentration, but in order to obtain a sufficient BMD density in the low-temperature/short-time heat treatment used in the top device process flow, EP defects began to increase from the more preferable nitrogen concentration of 6 × 1013atoms/cm3 or more, and the level suitable for use in the top device was not reached when the nitrogen was 1 × 1014atoms/cm3 or more. Further, when the pull rate is further lowered, if the heat treatment is performed at 800 ℃ for 3hr and 1000 ℃ for 2hr, BMD at the wafer center portion decreases, so that variation in BMD density (gettering capability) in the plane occurs, and an I-rich region having dislocation loops and dislocation clusters at the wafer center portion is formed, and an EP defect occurs at the center portion, and therefore, the EP defect cannot be completely suppressed by adjusting the pull rate with respect to the nitrogen concentration alone. In comparative examples 4-1 and 4-2, the BMD densities of the epitaxial silicon wafers after the heat treatment at 800 ℃ for 3hr and at 1000 ℃ for 2hr were 1 to 2X 108 and 2.5 to 15X 108/cm3, respectively. When the nitrogen concentration is 2X 1013atoms/cm3 or more, the BMD density of the top device, which is considered to have sufficient gettering ability and has an average size of 45nm or more, can be 1X 108 or more.
In contrast, in example 2, the EP defects were suppressed to a satisfactory level until the nitrogen concentration was 3.2X 1014atoms/cm 3. As a result, defects of 28nm or more were at an extremely favorable defect level of 2 defects/sheet or less on average over the entire substrate in a single crystal silicon ingot of 10cm or more, and epitaxial silicon wafers having fewer defects than comparative examples 3 and 4 were obtained. In addition, the BMD density of the epitaxial silicon wafer after the heat treatment at 800 ℃ for 3hr and 1000 ℃ for 2hr was 1 to 2X 108/cm3 in example 2-1, 2.5 to 5X 108/cm3 in example 2-2, and 1X 108/cm3 or more in the average size of 45nm or more, which is considered to have sufficient gettering capability in the top device, when the nitrogen concentration was 2X 1013atoms/cm3 or more. Further, since EP defects due to precipitates are generated at a nitrogen concentration of 3.5X 1014atoms/cm3, it is desirable that the nitrogen concentration is 3.2X 1014atoms/cm3 or less.
Thus, according to the present invention, an epitaxial silicon wafer having a good EP defect level can be produced over the entire crystal length with a very high yield even under a high nitrogen concentration condition where a high gettering capability can be expected in a top low temperature/short time device process flow.
[ Change in yield of silicon single crystal substrate (transition in quality of single silicon crystal) ]
Next, the effect obtained when the present invention is applied to actual product production will be described in detail by taking the yield of a single crystal silicon substrate as an example.
Comparative example 5
410kg of the raw material was melted in a 32-inch (812.8mm) crucible, and crystal production of 300mm diameter was carried out under application of 4000G magnetic field. Three crystals were produced in the straight product collecting section without doping nitrogen (comparative example 5-1), with a nitrogen concentration of 2 × 1013-6 atoms/cm3 (comparative example 5-2), and a nitrogen concentration of 1 × 1014-3.2 × 1014atoms/cm3 (comparative example 5-3) under the condition that the distance between the heat shield directly above the raw material melt and the liquid surface of the raw material melt was 50mm, and the heater position and the position of the magnetic field applying device during crystal growth were adjusted so that an n (neutral) region was obtained over the entire crystal length in the case of no doping of nitrogen, and a single crystal silicon substrate was produced from the obtained crystals, and TDDB characteristics were evaluated. In addition, in order to evaluate defects of the silicon single crystal substrate, SP3 manufactured by KLA Tencor was used, and defects of 45nm or more were evaluated in the Oblique mode. The produced single crystal silicon substrate was subjected to heat treatment at 800 ℃ for 3hr and 1000 ℃ for 2hr, and then the BMD density of 30nm or more was measured by an infrared scattering method.
Comparative example 6
The TDDB characteristics and defects of the single crystal silicon substrate produced in the same manner as in comparative example 5 were evaluated in the same manner as in comparative example 5-2 (comparative example 6-1) and comparative example 5-3 (comparative example 6-2), except that the distance between the heat shield directly above the raw material melt and the liquid surface of the raw material melt was kept at 50mm, and the pull-up speed was adjusted in accordance with the nitrogen concentration (adjustment of the pull-up speed is delayed with respect to increase of the nitrogen concentration) as shown in patent document 9. The produced single crystal silicon substrate was subjected to heat treatment at 800 ℃ for 3hr and 1000 ℃ for 2hr, and then the BMD density of 30nm or more was measured by an infrared scattering method.
(example 3)
The distance between the heat shield directly above the raw material melt and the liquid surface of the raw material melt was set to D 'determined from D'/D being 0.94-nitrogen concentration/(2.41X 1015). Example 3-1 a silicon single crystal substrate was produced and TDDB characteristics and defects were evaluated in the same manner as in comparative example 6-2 except that the distance between the heat shield directly above the raw material melt and the liquid surface of the raw material melt was adjusted from 46.6mm to 45.8mm at a nitrogen concentration of 2 × 1013-6 × 1013atoms/cm3 in order to offset the influence of nitrogen segregation during crystal growth, in addition to adjusting the distance between the heat shield directly above the raw material melt and the liquid surface of the raw material melt from D '46.6 mm to 45.8mm at a nitrogen concentration of 1 × 1014-3.2 × 1014atoms/cm3 in example 3-2, and from D' 44.9mm to 40.3 mm. The produced single crystal silicon substrate was subjected to heat treatment at 800 ℃ for 3hr and 1000 ℃ for 2hr, and then the BMD density of 30nm or more was measured by an infrared scattering method. By changing the distance between the heat shield directly above the raw material melt and the liquid surface of the raw material melt in this manner, the temperature gradient Gc in the crystal center and the temperature gradient Ge in the crystal peripheral portion in the pulling axis direction of the single-crystal silicon are Ge/Gc > 1, and Ge/Gc is gradually increased in accordance with the increase in the nitrogen concentration due to segregation at the time of pulling the single-crystal silicon.
Fig. 6, 7 and 8 are graphs showing the TDDB characteristic evaluation results of the single crystal silicon substrates in comparative example 5, comparative example 6 and example 3, respectively.
In fig. 6, 7 and 8, the gray cells are at TDDB fault. The TDDB fault defect has a correlation with the EP defect source, and is the same result as the evaluation of the EP defect of comparative example 3, comparative example 4, and example 2 (fig. 3, 4, and 5). In comparative example 5, at a nitrogen concentration of 3X 1013atoms/cm3 or more, the TDDB failure gradually increased as the nitrogen concentration increased. The yield of TDDB characteristics in comparative example 5 was 99.7 to 99.3, 99.3 to 69.2, and 50.7 to 14.7% in comparative example 5-1, comparative example 5-2, and comparative example 5-3, respectively. In comparative examples 5-1, 5-2 and 5-3, defects of 45nm or more were 1-2, 1.8-158 and 73-1250 defects per sheet on average over the entire substrate in a single crystal silicon ingot of 10cm or more. In comparative examples 5-1, 5-2 and 5-3, the BMD densities of the single-crystal silicon substrates after the heat treatment at 800 ℃ for 3hr and at 1000 ℃ for 2hr were 1 to 3X 107, 1 to 2X 108 and 2.5 to 15X 108/cm3, respectively. When the nitrogen concentration is 2X 1013atoms/cm3 or more, the BMD density of the top device, which is considered to have sufficient gettering ability and has an average size of 45nm or more, can be 1X 108 or more.
In comparative example 6, similar to the tendency of the EP defect, the improvement effect was observed with respect to comparative example 5, but the improvement was not complete, and the TDDB failure increased from the nitrogen concentration of 6 × 1013atoms/cm3 or more and became worse. The yield of TDDB characteristics in comparative example 6 was 99.7-87.3 and 69.9-51.7% in comparative example 6-1 and comparative example 6-2, respectively. In comparative examples 6-1 and 6-2, defects of 45nm or more were 1 to 57 defects and 160 and 364 defects on average over the entire substrate in a single crystal silicon ingot of 10cm or more. In comparative examples 6-1 and 6-2, the BMD densities of the single crystal silicon substrates after the heat treatment at 800 ℃ for 3hr and at 1000 ℃ for 2hr were 1 to 2X 108 and 2.5 to 15X 108/cm3, respectively. When the nitrogen concentration is 2X 1013atoms/cm3 or more, the BMD density of the top device, which is considered to have sufficient gettering ability and has an average size of 45nm or more, can be 1X 108 or more.
In contrast, in example 3, the TDDB failure could be suppressed until the nitrogen concentration was 3.2X 1014atoms/cm 3. The yield of TDDB characteristics in example 3 was 99.7 to 99.3% in each of examples 3-1 and 3-2, with the nitrogen concentration being in the range of 2 to 3.2X 1014atoms/cm 3. In examples 3-1 and 3-2, defects of 45nm or more were 1 to 1.9 and 1.2 to 2 defects per wafer on average over the entire substrate in a single crystal silicon ingot of 10cm or more. In addition, BMD densities of the single crystal silicon substrates after the heat treatment at 800 ℃ for 3hr and at 1000 ℃ for 2hr in examples 3-1 and 3-2 were 1 to 2X 108 and 2.5 to 15X 108/cm3, respectively. When the nitrogen concentration is 2X 1013atoms/cm3 or more, the BMD density of the top device, which is considered to have sufficient gettering ability and has an average size of 45nm or more, can be 1X 108 or more.
As described above, according to the present invention, even under a high nitrogen concentration condition where a high gettering capability can be expected in a low-temperature/short-time device process flow at the top end, a single crystal silicon substrate having a good defect level without an increase in TDDB failure can be manufactured over the entire length of a crystal with a very high yield.
As described above, according to the present invention, it is possible to obtain a wafer which has an optimum nitrogen concentration of 3X 1013atoms/cm3 to 3.2X 1014atoms/cm3, has good TDDB properties in a state of being a single crystal silicon substrate, and does not cause EP defects on an epitaxial silicon wafer in order to obtain a sufficient BMD density in a low temperature/short time heat treatment such as a top device process flow.
The present invention is not limited to the above embodiments. The above-described embodiments are merely illustrative, and any embodiments having substantially the same configuration as the technical idea described in the claims of the present invention and achieving the same operational effects are included in the technical scope of the present invention.
Description of the reference numerals
1-a main chamber; 2-a pulling chamber; 3-a single crystal rod; 4-melting the raw materials; 5-quartz crucible; 6-a graphite crucible; 7-a heater; 8-a heat insulating member; 9-gas outflow; 10-a gas inlet; 11-a gas rectification cylinder; 12-a thermal shield; 13-a magnetic field applying means; 14-apparatus for producing single crystal silicon.
Claims (6)
1. a method for producing a silicon single crystal, characterized by growing a silicon single crystal by pulling the crystal under a condition that the entire crystal surface is an N-region by the Czochralski method,
when the single crystal silicon is grown, nitrogen is doped at a nitrogen concentration of 2X 1013atoms/cm3 or more and 3.2X 1014atoms/cm3 or less,
The ratio of the temperature gradient Gc of the crystal center portion in the pulling axis direction of the single-crystal silicon to the temperature gradient Ge of the crystal peripheral portion is such that Ge/Gc > 1,
The Ge/Gc is gradually increased in accordance with an increase in nitrogen concentration caused by segregation at the time of pulling the single-crystal silicon.
2. The method of manufacturing single-crystal silicon according to claim 1,
The Ge/Gc is adjusted by controlling any one of or a combination of two or more of controlling an interval between a heat shield disposed directly above the raw material melt in the quartz crucible and a liquid surface of the raw material melt, lowering a position of a heater disposed so as to surround the quartz crucible with respect to the liquid surface of the raw material melt, reducing a magnetic field strength of a magnetic field applying device disposed outside a main chamber of the apparatus for producing single-crystal silicon, and lowering a position of the magnetic field applying device.
3. The method of manufacturing single-crystal silicon according to claim 2,
When the Ge/Gc is adjusted by controlling the distance between the heat shield and the liquid surface of the raw material melt, the distance between the heat shield and the liquid surface of the raw material melt when the crystal is not doped with nitrogen under the condition that the entire crystal surface is in the N-region is set to D, and the distance between the heat shield and the liquid surface of the raw material melt when the crystal is doped with nitrogen is changed so as to correspond to the nitrogen concentration and be D 'obtained from D'/D being 0.94-nitrogen concentration/(2.41X 1015).
4. The method of manufacturing single-crystal silicon according to claim 3,
When the calculated D ' is larger than 20mm, the Ge/Gc is adjusted by setting the distance between the heat shield and the liquid surface of the raw material melt to the calculated D ', and when the calculated D ' is 20mm or less, the distance between the heat shield and the liquid surface of the raw material melt is 20mm, and further, the Ge/Gc is adjusted by lowering one or a combination of two or more of the position of a heater disposed so as to surround the quartz crucible with respect to the liquid surface of the raw material melt, the strength of a magnetic field applying device disposed outside a main chamber of the apparatus for producing single-crystal silicon, and the position of the magnetic field applying device.
5. An epitaxial silicon wafer is characterized in that an epitaxial layer is provided on a single crystal silicon substrate having an N-region as the entire crystal plane,
The single crystal silicon substrate is doped with nitrogen at a nitrogen concentration of 2X 1013atoms/cm3 or more and 3.2X 1014atoms/cm3 or less,
The number of defects having a size of 28nm or more is 2/sheet or less on average over the entire substrate in a single crystal silicon ingot having a size of 10cm or more, and the density of BMD having an average size of 45nm or more, which is measured after a heat treatment performed at 800 ℃ for 3hr and at 1000 ℃ for 2hr, is 1X 108/cm3 or more.
6. A single-crystal silicon substrate characterized by having a mirror-polished surface and having an N-region as the entire crystal plane,
Doping nitrogen with a nitrogen concentration of 2X 1013atoms/cm3 or more and 3.2X 1014atoms/cm3 or less,
The yield of TDDB characteristics is 90% or more, the number of defects having a size of 45nm or more is 2/sheet or less on average over the entire substrate in a single crystal silicon ingot having a size of 10cm or more, and the density of BMD having an average size of 45nm or more, which is measured after a heat treatment at 800 ℃ for 3hr and 1000 ℃ for 2hr, is 1X 108/cm3 or more.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2018102016A JP6927150B2 (en) | 2018-05-29 | 2018-05-29 | Method for manufacturing silicon single crystal |
| JP2018-102016 | 2018-05-29 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN110541191A true CN110541191A (en) | 2019-12-06 |
| CN110541191B CN110541191B (en) | 2022-08-09 |
Family
ID=68709593
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201910458568.0A Active CN110541191B (en) | 2018-05-29 | 2019-05-29 | Method for producing single crystal silicon, epitaxial silicon wafer, and single crystal silicon substrate |
Country Status (3)
| Country | Link |
|---|---|
| JP (1) | JP6927150B2 (en) |
| KR (1) | KR20190135913A (en) |
| CN (1) | CN110541191B (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113862791A (en) * | 2021-09-28 | 2021-12-31 | 西安奕斯伟材料科技有限公司 | Crystal pulling furnace for pulling monocrystalline silicon rod |
| CN113897671A (en) * | 2021-09-30 | 2022-01-07 | 西安奕斯伟材料科技有限公司 | Preparation method of nitrogen-doped single crystal silicon rod and nitrogen-doped single crystal silicon rod |
| CN115404539A (en) * | 2022-08-30 | 2022-11-29 | 西安奕斯伟材料科技有限公司 | Method for pulling single crystal silicon rod by Czochralski method, single crystal silicon rod, silicon wafer and epitaxial silicon wafer |
| CN115574722A (en) * | 2022-11-04 | 2023-01-06 | 中国计量科学研究院 | Self-tracing interference type displacement sensor |
Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2002015253A1 (en) * | 2000-08-11 | 2002-02-21 | Shin-Etsu Handotai Co., Ltd. | Method of producing silicon wafer |
| US20020081440A1 (en) * | 2000-12-20 | 2002-06-27 | Sumitomo Metal Industries, Ltd. | Silicon wafer and epitaxial silicon wafer utilizing same |
| WO2008029579A1 (en) * | 2006-09-05 | 2008-03-13 | Shin-Etsu Handotai Co., Ltd. | Silicon single-crystal wafer and process for producing the same |
| CN101198727A (en) * | 2005-06-20 | 2008-06-11 | 胜高股份有限公司 | Method for growing silicon single crystal and method for manufacturing silicon wafer |
| JP2015107898A (en) * | 2013-12-05 | 2015-06-11 | 株式会社Sumco | Method of raising silicon single crystal |
Family Cites Families (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH1179889A (en) | 1997-07-09 | 1999-03-23 | Shin Etsu Handotai Co Ltd | Production of and production unit for silicon single crystal with few crystal defect, and silicon single crystal and silicon wafer produced thereby |
| JP2000016897A (en) | 1998-07-03 | 2000-01-18 | Sumitomo Metal Ind Ltd | Production of high quality silicon single crystal |
| JP3692812B2 (en) | 1998-06-04 | 2005-09-07 | 信越半導体株式会社 | Nitrogen-doped low-defect silicon single crystal wafer and manufacturing method thereof |
| JP4358333B2 (en) | 1998-11-20 | 2009-11-04 | Ｓｕｍｃｏ Ｔｅｃｈｘｉｖ株式会社 | Method for producing silicon single crystal |
| JP3601328B2 (en) | 1998-12-14 | 2004-12-15 | 信越半導体株式会社 | Method for producing silicon single crystal and silicon single crystal and silicon wafer produced by this method |
| JP3787472B2 (en) | 1999-11-12 | 2006-06-21 | 信越半導体株式会社 | Silicon wafer, method for manufacturing the same, and method for evaluating silicon wafer |
| JP4102988B2 (en) | 2000-06-26 | 2008-06-18 | 信越半導体株式会社 | Method for producing silicon wafer and epitaxial wafer, and epitaxial wafer |
| JP4715402B2 (en) | 2005-09-05 | 2011-07-06 | 株式会社Ｓｕｍｃｏ | Single crystal silicon wafer manufacturing method, single crystal silicon wafer, and wafer inspection method |
| JP6135611B2 (en) | 2014-07-03 | 2017-05-31 | 信越半導体株式会社 | Point defect concentration calculation method, Grown-in defect calculation method, Grown-in defect in-plane distribution calculation method, and silicon single crystal manufacturing method using them |
-
2018
- 2018-05-29 JP JP2018102016A patent/JP6927150B2/en active Active
-
2019
- 2019-04-18 KR KR1020190045181A patent/KR20190135913A/en not_active Application Discontinuation
- 2019-05-29 CN CN201910458568.0A patent/CN110541191B/en active Active
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2002015253A1 (en) * | 2000-08-11 | 2002-02-21 | Shin-Etsu Handotai Co., Ltd. | Method of producing silicon wafer |
| US20020081440A1 (en) * | 2000-12-20 | 2002-06-27 | Sumitomo Metal Industries, Ltd. | Silicon wafer and epitaxial silicon wafer utilizing same |
| CN101198727A (en) * | 2005-06-20 | 2008-06-11 | 胜高股份有限公司 | Method for growing silicon single crystal and method for manufacturing silicon wafer |
| WO2008029579A1 (en) * | 2006-09-05 | 2008-03-13 | Shin-Etsu Handotai Co., Ltd. | Silicon single-crystal wafer and process for producing the same |
| JP2015107898A (en) * | 2013-12-05 | 2015-06-11 | 株式会社Sumco | Method of raising silicon single crystal |
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113862791A (en) * | 2021-09-28 | 2021-12-31 | 西安奕斯伟材料科技有限公司 | Crystal pulling furnace for pulling monocrystalline silicon rod |
| CN113897671A (en) * | 2021-09-30 | 2022-01-07 | 西安奕斯伟材料科技有限公司 | Preparation method of nitrogen-doped single crystal silicon rod and nitrogen-doped single crystal silicon rod |
| WO2023051694A1 (en) * | 2021-09-30 | 2023-04-06 | 西安奕斯伟材料科技有限公司 | Preparation method for nitrogen-doped monocrystalline silicon rod and nitrogen-doped monocrystalline silicon rod |
| CN115404539A (en) * | 2022-08-30 | 2022-11-29 | 西安奕斯伟材料科技有限公司 | Method for pulling single crystal silicon rod by Czochralski method, single crystal silicon rod, silicon wafer and epitaxial silicon wafer |
| CN115574722A (en) * | 2022-11-04 | 2023-01-06 | 中国计量科学研究院 | Self-tracing interference type displacement sensor |
| CN115574722B (en) * | 2022-11-04 | 2024-03-29 | 中国计量科学研究院 | Self-tracing interference type displacement sensor |
Also Published As
| Publication number | Publication date |
|---|---|
| KR20190135913A (en) | 2019-12-09 |
| JP2019206451A (en) | 2019-12-05 |
| CN110541191B (en) | 2022-08-09 |
| JP6927150B2 (en) | 2021-08-25 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN110541191B (en) | Method for producing single crystal silicon, epitaxial silicon wafer, and single crystal silicon substrate | |
| US8211228B2 (en) | Method for producing single crystal and a method for producing annealed wafer | |
| US20230295835A1 (en) | N-type silicon single crystal production method, n-type silicon single crystal ingot, silicon wafer, and epitaxial silicon wafer | |
| WO2006117939A1 (en) | Method for producing silicon wafer | |
| JPH10152395A (en) | Production of silicon single crystal | |
| JP2007194232A (en) | Process for producing silicon single crystal wafer | |
| JP2012246218A (en) | Silicon single crystal wafer, and method for producing silicon single crystal | |
| CN110629283A (en) | Silicon single crystal growth method | |
| KR20020019025A (en) | Silicon wafer and method for producing silicon single crystal | |
| JP2010184839A (en) | Silicon single crystal and method of manufacturing the same | |
| KR101847481B1 (en) | Silicon epitaxial wafer and method for producing same | |
| US11377755B2 (en) | N-type silicon single crystal production method, n-type silicon single crystal ingot, silicon wafer, and epitaxial silicon wafer | |
| JP4196602B2 (en) | Epitaxial growth silicon wafer, epitaxial wafer, and manufacturing method thereof | |
| JP4151474B2 (en) | Method for producing single crystal and single crystal | |
| JP4467096B2 (en) | Silicon single crystal manufacturing method and semiconductor forming wafer | |
| JP2009274888A (en) | Production method of silicon single crystal, and silicon single crystal wafer | |
| JP4231275B2 (en) | Silicon wafer manufacturing method, manufacturing apparatus thereof, and silicon wafer | |
| JP3719088B2 (en) | Single crystal growth method | |
| JP4089137B2 (en) | Method for producing silicon single crystal and method for producing epitaxial wafer | |
| JP4293188B2 (en) | Single crystal manufacturing method and silicon single crystal wafer | |
| JP4080657B2 (en) | Method for producing silicon single crystal ingot | |
| JP4688984B2 (en) | Silicon wafer and crystal growth method | |
| JP4360208B2 (en) | Method for producing silicon single crystal | |
| JP7272343B2 (en) | Method for producing n-type silicon single crystal | |
| TWI420005B (en) | Method of manufacturing single crystal ingot and wafer manufactured by thereby |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |