Quartz Crucible Corner Infrared Control for Silicon Crystal Purity
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The challenge is to achieve a quartz glass crucible that can consistently produce silicon single crystals with low oxygen concentration and uniform oxygen distribution during the Czochralski method, as existing crucibles face issues with oxygen contamination and uneven oxygen concentration along the crystal growth direction.
Innovation Solution
A quartz glass crucible design featuring a cylindrical side wall, a bottom portion, and a corner portion with a transparent layer and a bubble layer, where the infrared transmissivity of the corner portion is controlled to suppress temperature rise and oxygen supply, and the thickness and bubble content are optimized to maintain stable temperature and oxygen distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a quartz glass crucible is used for pulling up silicon single crystal by CZ method, then the silicon raw material can be heated and melted, but the inner surface of the crucible comes into contact with silicon melt and is gradually eroded, causing oxygen contamination in the silicon single crystal
Solution Approach 1:
The crucible wall is designed with non-uniform thickness, where the corner portion has a specific thickness range (5-15mm) that is different from other parts. This local variation in thickness creates appropriate infrared transmissivity characteristics to suppress temperature rise and oxygen supply at the corner portion while maintaining overall crucible stability.
Solution Approach 2:
The invention changes the physical parameter of infrared transmissivity by controlling the wall thickness at the corner portion. By adjusting the thickness to 5-15mm, the infrared transmissivity is optimized to reduce temperature rise at the corner, thereby suppressing oxygen dissolution into the silicon melt and reducing oxygen concentration in the final crystal.
2Object-generated harmful factors
If the infrared transmissivity of the corner portion is reduced to suppress temperature rise and oxygen supply, then oxygen concentration is reduced, but the temperature distribution stability may be affected
Solution Approach 1:
The corner portion is designed with specific thickness (5-15mm) to create appropriate infrared transmissivity locally, while other parts of the crucible maintain different thickness characteristics. This localized optimization reduces oxygen supply at the corner without excessively affecting overall temperature distribution stability.
Solution Approach 2:
Instead of uniformly reducing infrared transmissivity throughout the entire crucible wall, the invention applies partial action by reducing it only at the corner portion where oxygen contamination is most severe. This selective approach suppresses oxygen concentration while maintaining temperature distribution stability in other critical areas.
3Object-generated harmful factors
If the wall thickness at the corner portion is increased to control infrared transmissivity, then oxygen concentration is suppressed, but the device complexity and manufacturing difficulty increase
Solution Approach 1:
The crucible features non-uniform wall thickness with the corner portion having a specific thickness range (5-15mm) that is different from other parts. This local variation achieves oxygen suppression without requiring complex multi-layer structures or additional components.
Solution Approach 2:
The invention optimizes the wall thickness parameter at the corner portion to 5-15mm, which provides appropriate infrared transmissivity to suppress oxygen concentration. This single parameter adjustment achieves the desired effect without introducing significant structural complexity.
4Temperature
If the infrared transmissivity varies significantly along the wall surface from bottom to top, then local temperature control is improved, but the oxygen concentration distribution uniformity in the crystal deteriorates
Solution Approach 1:
The crucible wall thickness is designed to vary along the wall surface, with the corner portion having a specific thickness (5-15mm) that is different from other parts. This local variation creates appropriate infrared transmissivity to control temperature at the corner while maintaining overall temperature distribution that ensures uniform oxygen concentration in the crystal.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This design effectively reduces oxygen contamination in silicon single crystals and ensures a stable oxygen concentration distribution along the crystal growth direction, enabling the production of high-quality silicon single crystals with low oxygen content.
Implementation Method 1
a bubble layer which is made of quartz glass containing a large number of bubbles and is formed outside the transparent layer, in which a ratio of an infrared transmissivity of the corner portion at a maximum thickness position of the corner portion to an infrared transmissivity of the side wall portion is 0.3 or more and 0.99 or less
Data Source
AI summary
A quartz glass crucible 1 having a cylindrical side wall portion 10a, a bottom portion 10b, and a corner portion 10c connecting the side wall portion 10a and the bottom portion 10b to each other includes a transparent layer 11 made of quartz glass, and a bubble layer 12 made of quartz glass and formed outside the transparent layer 11. A ratio of an infrared transmittance of the corner portion 10c at a maximum thickness position of the corner portion 10c to an infrared transmittance of the side wall portion 10a is 0.3 or more and 0.99 or less, and an absolute value of a rate of change in infrared transmittance in a height direction along a wall surface of the crucible from a center of the bottom portion 10b toward an upper end of the side wall portion 10a is 3%/cm or less.