Low-Impurity Resin Jigs for Polysilicon Handling
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Solution Overview
Problem
The surface impurity concentration of polycrystalline silicon materials used in producing single crystalline silicon tends to increase during production steps, despite initial surface cleanliness achieved through chemical etching, leading to contamination issues.
Innovation Solution
A resin material with specific low impurity concentrations, such as phosphorus, arsenic, and aluminum, is used to create jigs like vinyl bags and gloves that handle and process polycrystalline silicon, maintaining cleanliness and preventing contamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If chemical etching is used to reduce surface impurity concentration, then surface cleanliness is improved, but surface impurity concentration increases again during subsequent handling steps
Solution Approach 1:
The resin material is pre-treated to have extremely low impurity concentrations (P: 50 pptw or less, As: 2 pptw or less, B: 20 pptw or less, Al: 10 pptw or less) before contact with polycrystalline silicon. This preliminary preparation prevents contamination from occurring during subsequent handling operations, addressing the re-contamination problem after chemical etching.
Solution Approach 2:
The resin material acts as an intermediary between handling equipment and polycrystalline silicon. By using resin-based gloves, bags, and containers as intermediaries, direct contact between silicon and potential contamination sources is prevented, maintaining surface cleanliness throughout the handling process.
2Manufacturing precision
If high purity resin materials are used to prevent contamination, then surface cleanliness is maintained, but production cost increases
Solution Approach 1:
The patent specifies precise impurity concentration parameters for the resin material (P: 50 pptw or less, As: 2 pptw or less, B: 20 pptw or less, Al: 10 pptw or less) rather than requiring complete purity. This parameter-based approach allows for cost-effective production while achieving the necessary cleanliness levels for polycrystalline silicon handling.
Solution Approach 2:
The invention employs disposable resin-based handling items (gloves, bags, containers) that are inexpensive enough to be used once and discarded. This approach prevents contamination without requiring expensive reusable equipment that would need frequent cleaning and maintenance, thereby controlling production costs.
Data Source
AI summary
According to the present invention, a resin material that has the following surface concentration of impurities is consistently used in production of polycrystalline silicon. Values obtained from quantitative analysis by ICP-mass spectrometry using a 1 wt % nitric acid aqueous solution as an extraction liquid are: a phosphorous (P) concentration of 50 pptw or less; an arsenic (As) concentration of 2 pptw or less; a boron (B) concentration of 20 pptw or less; an aluminum (Al) concentration of 10 pptw or less; a total concentration of 6 elements of iron (Fe), chromium (Cr), nickel (Ni), copper (Cu), sodium (Na), and zinc (Zn) of 80 pptw or less; a total concentration of 10 elements of lithium (Li), potassium (K), calcium (Ca), titanium (Ti), manganese (Mn), cobalt (Co), molybdenum (Mo), tin (Sn), tungsten (W), and lead (Pb) of 100 pptw or less.