Silicon Ingot Puller Screening with Small-Rod Oxygen Testing
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Solution Overview
Problem
Existing ingot puller apparatus designs exhibit wide variability in their ability to produce low oxygen content silicon ingots, making it difficult to determine which apparatus is best suited for producing silicon ingots with oxygen concentrations below 5.0 ppma, which is required for certain semiconductor applications.
Innovation Solution
A method involving the growth of a sample rod with a diameter less than 50 mm from a silicon melt, processing it into a segment, and measuring its oxygen content using Fourier-transform infrared spectroscopy to characterize the oxygen capability of the ingot puller apparatus, allowing for the selection of the appropriate apparatus for producing low oxygen content ingots.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a full-sized product ingot is pulled to characterize oxygen capability of ingot puller apparatus, then the oxygen capability can be determined, but the charge consumption is high and productivity is reduced
Solution Approach 1:
The patent divides the characterization process into segments: instead of pulling a full-sized product ingot, only a small sample rod (diameter less than 50 mm, typically 10-30 mm) is pulled first to characterize the apparatus. This segmented approach allows oxygen capability assessment using minimal charge (a few kilograms instead of tons), while the sample rod provides sufficient data to predict full ingot oxygen content through established correlation methods.
Solution Approach 2:
The patent performs preliminary characterization by pulling a small sample rod before committing to full product ingot production. This preliminary action enables early determination of apparatus oxygen capability, allowing operators to identify suitable apparatus for low-oxygen applications before consuming large amounts of charge, thereby preventing wasted production cycles on unsuitable equipment.
2Measurement precision
If multiple ingot puller apparatus are tested with full product ingots to determine oxygen capability, then the best apparatus can be identified, but the time consumption and productivity loss are significant
Solution Approach 1:
The characterization process is segmented into rapid small-scale sample rod pulling followed by oxygen analysis. Each apparatus is evaluated using only a small sample rod (taking hours instead of days), and the results are correlated to predict full ingot performance. This segmentation reduces the time required to evaluate multiple apparatus from weeks to days or hours.
Solution Approach 2:
The patent replaces the traditional mechanical approach of growing full ingots for characterization with a combination of small-scale mechanical pulling followed by analytical instrumentation (Fourier-transform infrared spectroscopy or secondary ion mass spectrometry). This substitution of heavy mechanical characterization with analytical measurement dramatically reduces the time and charge required for apparatus evaluation.
3Productivity
If unsuitable ingot puller apparatus are used for low oxygen content ingot production, then production can proceed, but the oxygen content specification cannot be met resulting in wasted charge and reduced throughput
Solution Approach 1:
The patent performs preliminary oxygen capability characterization using small sample rods before initiating full product ingot production. This preliminary assessment ensures that only apparatus capable of meeting the oxygen content specification (less than 5.0 ppma) are selected for production, eliminating the risk of producing non-compliant ingots and ensuring reliable specification compliance while maintaining high throughput.
Solution Approach 2:
The patent implements a feedback mechanism where oxygen content measurements from sample rods are used to determine apparatus suitability. The measured oxygen content in sample rods provides feedback about the apparatus's oxygen capability, which then guides the decision of whether to proceed with full product ingot production on that apparatus, ensuring that only suitable equipment is used for low-oxygen applications.
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 method efficiently identifies suitable ingot puller apparatus for low oxygen content ingot production, reducing waste and increasing throughput by ensuring only apparatus capable of producing low oxygen ingots are used, while minimizing the amount of charge required for characterization.
Implementation Method 1
The solid silicon is heated to cause a silicon melt to form in the crucible
Implementation Method 2
A sample rod is pulled from the melt
Implementation Method 3
The sample rod segment is analyzed with a Fourier-transform infrared spectrometer. An oxygen content of the sample rod segment is measured
Data Source
AI summary
Methods for producing a product ingot from a silicon melt held within a crucible are disclosed. The methods involve evaluating one or more ingot puller apparatus to determine if the apparatus is capable of producing low oxygen content silicon product ingots. A sample rod is pulled from the silicon melt and the oxygen content of the sample rod is measured.