Polycrystalline Silicon Surface Contamination Detection via Reference Rod Comparison
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Solution Overview
Problem
Current methods for quality control of polycrystalline silicon do not effectively account for surface contamination that occurs during processing, storage, transport, cleaning, and packaging, as they primarily focus on bulk contamination analysis.
Innovation Solution
A process involving two polycrystalline silicon rods, where one is analyzed immediately after deposition and the other is processed through various systems to determine surface contamination by measuring differences in contaminant levels post-processing, using FTIR and photoluminescence to differentiate between bulk and surface contaminants.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional quality control methods are used that focus on bulk contamination analysis, then bulk contamination can be detected, but surface contamination during processing cannot be accurately determined
Solution Approach 1:
The invention segments the contamination analysis into two distinct components: bulk contamination and surface contamination. By using a reference rod that undergoes the complete processing sequence and comparing it with a control rod, the method isolates surface contamination as a separate measurable quantity, enabling accurate determination of surface-specific contaminant levels without being confounded by bulk contamination.
Solution Approach 2:
The reference rod serves as an intermediary that carries information about surface contamination throughout the processing sequence. By subjecting this intermediary to the same processing steps as the product rods and then comparing its contamination profile with the control rod, the method uses the reference rod as a mediator to indirectly measure surface contamination that would otherwise be inaccessible.
2Ease of manufacture
If polysilicon rods are processed through cleaning, storage, and packaging systems, then they are prepared for use, but surface contamination increases during these processing steps
Solution Approach 1:
The invention performs preliminary action by subjecting the reference rod to the complete processing sequence (cleaning, storage, packaging) before analysis. This allows the surface contamination introduced during these necessary manufacturing steps to be pre-captured and measured in the reference rod, which then serves as a baseline for comparing product rods and quantifying the contamination impact of each processing step.
Solution Approach 2:
The method establishes a feedback loop where the reference rod provides continuous information about contamination levels introduced during processing. By comparing product rods against the reference rod at various stages, the system generates feedback about the contamination impact of specific processing steps, enabling optimization of cleaning, storage, and packaging procedures to minimize surface contamination while maintaining ease of manufacture.
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
Enables accurate determination and monitoring of surface contamination during processing steps, allowing for optimization of production processes and ensuring higher quality control of polysilicon products.
Implementation Method 1
converting the first and second polycrystalline silicon rods to monocrystalline material
Implementation Method 2
doping contaminants by photoluminescence
Implementation Method 3
carbon contaminations by Fourier transform infrared spectroscopy
Data Source
AI summary
The invention provides a process for determining surface contamination of polycrystalline silicon, including the steps of: a) providing two polycrystalline silicon rods by deposition in a Siemens reactor; b) determining contaminants in the first of the two rods immediately after the deposition; c) conducting the second rod through one or more systems in which polycrystalline silicon rods are processed further to give rod pieces or polysilicon fragments, optionally cleaned, stored or packed; d) then determining contaminants in the second rod; wherein the difference in the contaminants determined in the first and second rods gives surface contamination of polycrystalline silicon resulting from systems and the system environment.