KR20170011428A - Fabrication method of high definition quartz crucible with low bubble density - Google Patents
Fabrication method of high definition quartz crucible with low bubble density Download PDFInfo
- Publication number
- KR20170011428A KR20170011428A KR1020150104045A KR20150104045A KR20170011428A KR 20170011428 A KR20170011428 A KR 20170011428A KR 1020150104045 A KR1020150104045 A KR 1020150104045A KR 20150104045 A KR20150104045 A KR 20150104045A KR 20170011428 A KR20170011428 A KR 20170011428A
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- KR
- South Korea
- Prior art keywords
- quartz crucible
- quartz
- bubble density
- transparent layer
- single crystal
- Prior art date
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Classifications
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- 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
- C30B15/10—Crucibles or containers for supporting the melt
- C30B15/12—Double crucible methods
-
- 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
- C30B15/10—Crucibles or containers for supporting the melt
-
- 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
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- 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 at least one potential-jump barrier or surface barrier, e.g. PN junction, depletion layer or carrier concentration layer
- H01L21/18—Manufacture or treatment of semiconductor devices or of parts thereof the devices having at least one potential-jump barrier or surface barrier, e.g. PN junction, depletion layer or carrier concentration layer the devices having semiconductor bodies comprising elements of Group IV of the Periodic System or AIIIBV compounds with or without impurities, e.g. doping materials
- H01L21/22—Diffusion of impurity materials, e.g. doping materials, electrode materials, into or out of a semiconductor body, or between semiconductor regions; Interactions between two or more impurities; Redistribution of impurities
Abstract
Optimization of melting process, optimization of graphite mold, injection of inert gas during melting process in manufacturing of high-quality quartz crucible with less than 1% bubble density of transparent layer in quartz crucible used in silicon and single crystal silicon for solar cell production A high quality quartz crucible is realized by charging inert gas.
Description
Silicon wafers, which can be said to be the backbone of the semiconductor industry, are made of silicon single crystals. Monocrystalline silicon (Si single crystal) is produced by heating and melting in a Czochralski puller by filling high purity polycrystalline silicon with raw material, quartz crucible. Since the growth of a single crystal by the Czochralski method does not directly touch the quartz crucible, there are few restrictions such as reaction and shrinkage due to the crucible, and single crystals can be grown with arbitrary crystal orientation and a large single crystal can be reproducibly produced. In addition, the production of silicon single crystal by the Czochralski method applied to existing solar light uses a quartz crucible as a silicon single crystal growth reaction vessel. A high-purity quartz crucible is an optimal material for maintaining a high purity of molten silicon in the production of a silicon single crystal. The performance of the quartz crucible has a direct influence on the crystal formation of the single crystal silicon ingot. When the surface of the quartz crucible is exposed to a failure, the crystallization layer of the surface layer is peeled off. As a result, adhesion to the ingot during impression (production) causes a decrease in yield of the single crystal ingot. The quartz crucible should be manufactured to prevent the occurrence of the run-off, and should have the following two characteristics.
1) Suppression of bubble generation
2) High purity of inner surface
High purity quartz powder raw materials must be used for high purity surface of quartz crucible and strict manufacturing process control is required. As described above, quartz crucibles are an indispensable part in the production of silicon monocrystals for semiconductors and solar cells, which are the existing markets. Quartz crucibles can be produced by molding high purity quartz sand through melting.
The process by which the quartz crucible affects the growth process of the silicon single crystal is described as follows.
1) Charging polycrystalline silicon as a raw material into a quartz crucible and increasing the temperature of the growth device to Si melting temperature, the following reaction proceeds.
SiO 2 (quartz crucible) = Si (melts into melt) + 2O
Si (in the melt) + O = SiO
In other words, quartz crucible reacts with Si melt and reacts again and reacts in the form of SiO, Si, O in the Si melt. 1% of the oxygen present in the melt is bonded to the Si single crystal and 99% It will come out. In addition, the quartz crucible becomes a cristobalite surface called a brownish ring through a high temperature reaction. When the crystallized surface flows into a part of the Si melt and flows into the melt interface of the Si single crystal in which the grain is growing, It is the first factor that hinders growth. In order to suppress this process, the Ba coating should be optimized on the surface of the quartz crucible and the bubble must be minimized in the quartz crucible's transparent layer (the quartz crucible consists of a transparent layer and opaque layer) The surface area of the quartz crucible is widened during the reaction with the melt, thereby promoting the reaction. As a result, a larger amount of O (oxygen) is introduced into the Si melt, which has a significant influence on the characteristics of the Si single crystal. In addition, when a large amount of bubbles are formed, a large amount of quartz crucible particles are introduced into the Si melt during the reaction with the Si melt, which has a serious effect on the yield of single crystal growth.
Conventional techniques for reducing the bubble density of the quartz crucible are as follows.
1) Vacuum is used in the process of forming the transparent layer.
2) High purity quartz sand (quartz sand) is used.
Conventional techniques have used a method of increasing the degree of vacuum to reduce the density of bubbles in the quartz crucible transparent layer and a method of using high quality quartz sand raw material in the quartz crucible as the transparent layer. However, there are limitations in lowering the density of bubbles in this way, and there is a limit to the cost of manufacturing cost when using expensive quartz sand as a raw material. In the present invention, the following manufacturing process is applied to manufacture a quartz crucible having significantly reduced bubble density while using the conventional IOTA-CG model of Unimin and NC4A model of Quartz Corp.
The present invention proposes a method for manufacturing a high-quality quartz crucible by optimizing a melting process, optimizing a graphite mold design, and introducing an inert gas in the production of a quartz crucible having a low bubble density
In the present invention, a high-quality quartz crucible was manufactured through the following technical approach.
1. Optimize the quartz crucible fusion process.
(1) Optimization of applied voltage and current
(2) Optimization of vacuum process by melting process and optimization of graphite mold structure
(3) Removal of moisture through baking of quartz sand by applying low applied voltage at the beginning of melting
- The moisture present in the quartz sand is a factor in the formation of the bubble density in the quartz crucible.
(4) After Baking, the application voltage is raised to form a thin transparent layer on the quartz sand surface, and then the melting voltage is increased to the steady state.
2. Minimize the density of bubbles in quartz crucibles.
(1) Optimization of related process of power and bubble density at melting
⑵ Optimization of melt power and quartz sand supply method
- Minimize bubble density through harmonization with high power melting and spray supply method
(3) Systematization of bubble density analysis method in quartz crucible transparent layer
⑷ Reduction of bubble density through improvement of vacuum mold structure
3. Optimization of inert gas process
(1) The inert gas is used to minimize the inflow of the reaction gas into the quartz crucible and to suppress the expansion of the bubbles present in the quartz crucible transparent layer at a process temperature of ~ 1,400 ° C during the growth of the Si single crystal, To prevent bubble problems. (This is a concept that suppresses the expansion of bubbles due to the use of an inert gas, which causes expansion of the bubbles due to expansion of the gas at high temperatures, depending on the gas components in the bubbles existing in the quartz crucible transparent layer.
(2) Minimizing the density of bubbles through optimization of the type of inert gas and process
⑶ Hydrogen
⑷ Argon
⑸ Helium
⑹ hydrogen + argon
⑺ hydrogen + helium
⑻ Argon + helium
4. Ba coating process optimization
(1) Optimization of Ba concentration
⑵ Optimization of Ba coating thickness
(3) Ba coating process temperature optimization
(4) Ba coating uniformization
The present invention relates to a method for reducing the bubble density of a transparent layer of a quartz crucible, which is an indispensable consumable for producing a silicon monocrystal ingot, and is a method for improving the quality of a transparent layer of a quartz crucible, It is possible to improve the growth yield of silicon single crystal by suggesting a method of preventing the SiO 2 peeling layer caused by a large bubble from flowing into the melt at the surface of the quartz crucible and inhibiting the yield of the silicon single crystal production.
FIG. 1 is a view for explaining a melting process of a high-quality quartz crucible having a low bubble density according to the present invention; FIG.
FIG. 2 is a view for explaining the structure of a high-quality quartz crucible having a low bubble density according to the present invention; FIG.
FIG. 3 is a view for explaining a quartz crucible melting process using an inert gas such as hydrogen, argon, helium, etc.
FIG. 4 shows a manufacturing process of a high-quality quartz crucible.
FIG. 5 is a bubble density analysis data in a transparent layer of a quartz crucible manufactured by a conventional technique.
FIG. 6 is a bubble density analysis data of a high-quality quartz crucible with a bubble density of 1% or less proposed in the present invention.
The process for producing a low-density, high-quality quartz crucible of the present invention is as follows.
1. Forming process
- Charge high purity quartz sand into the graphite mold inside the melting vessel.
- At this time, the graphite mold is loaded with quartz sand while rotating, and the thickness and diameter of the quartz crucible are determined in the molding process.
2. Fusion process
- Transparent layer manufacturing process: The quartz sand is melted through the arc melting of ~ 3500 degrees through the carbon electrode while keeping the vacuum in the graphite mold to make a transparent layer of 3 mm or more on the inner surface of the quartz crucible.
- Opaque layer manufacturing process: Vacuum is released to graphite mold and arc melting is continued through the carbon electrode to make opaque layer of quartz crucible excluding 3 mm or more transparent layer on the inner surface of quartz crucible. The crucial process is to minimize the bubble density of the transparent layer of the quartz crucible by selecting the quartz sand, designing the graphite mold, and optimizing the melting process.
1)
50 kW of power is applied to remove the OH groups present in the quartz sand after the molding process. At this time, the vacuum is maintained at 150 torr or less.
2)
The power is increased to 500KW to implement the transparent layer manufacturing process.
The inert gas such as hydrogen, argon, and helium is allowed to flow while maintaining the vacuum below 150 torr.
3)
The opaque layer manufacturing process is carried out while maintaining a power of 500 KW.
At this time, the vacuum is maintained at 600 to 700 torr.
3. Inspection
- Inspect diameter, thickness, black spot, white spot etc. of quartz crucible after melting process.
4. Surface treatment
- After the melting process, the outer wall of the quartz crucible is surface-treated through a sand blast process.
5. Cutting process
6. Inspection
- Inspect the quartz crucible for weight, diameter, thickness, black spot, white spot, R-gap, etc.
7. Etching and cleaning
- Final etching and cleaning of the quartz crucible is carried out.
8. Inspection
- The bubble density and the thickness of the transparent layer of the quartz crucible are analyzed by non-contact method (optical method).
Run the black spot and white spot check again.
9. Ba coating process (Ba coating)
- The Ba coating process is performed to minimize the reaction between the silicon melt and the quartz crucible during the growth of silicon single crystals. At this time, Ba concentration, thickness, reaction temperature (200 ~ 300 degrees) are optimized.
10. Package
The bubble density characteristics of the transparent layer of the quartz crucible manufactured through this process were ~ 1% as shown in FIG. On the other hand, the transparent layer bubble density characteristic of the quartz crucible manufactured by the conventional technique shows ~ 2.77% in the curved surface portion as shown in FIG. 5. This means that the quartz crucible manufacturing process of the present invention is very effective in reducing the density of bubbles.
(1) Quartz crucible transparent layer (2) Quartz crucible opaque layer (3) Graphite mold
(4) Rotary shafts (5) Vacuum exhaust pipes in molds (6) Power supplies (7) Arc electrodes
(8) Arc (9) Inert gas supply pipe (10) Inert gas
Claims (3)
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| KR1020150104045A KR20170011428A (en) | 2015-07-23 | 2015-07-23 | Fabrication method of high definition quartz crucible with low bubble density |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| KR1020150104045A KR20170011428A (en) | 2015-07-23 | 2015-07-23 | Fabrication method of high definition quartz crucible with low bubble density |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| KR20170011428A true KR20170011428A (en) | 2017-02-02 |
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| Application Number | Title | Priority Date | Filing Date |
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| KR1020150104045A KR20170011428A (en) | 2015-07-23 | 2015-07-23 | Fabrication method of high definition quartz crucible with low bubble density |
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| KR (1) | KR20170011428A (en) |
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2015
- 2015-07-23 KR KR1020150104045A patent/KR20170011428A/en not_active Application Discontinuation
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