Feed Tool Plate Segmentation for Thermal Stress in Crystal Pullers
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Solution Overview
Problem
Existing feed tools used in crystal pullers for producing single crystal silicon ingots are prone to thermal stress and material deterioration due to temperature fluctuations and reactivity with silicon, leading to inefficiencies and contamination during the Czochralski process.
Innovation Solution
A feed tool design featuring a cylinder with an annular ledge and a plate comprising separate sections that can move laterally to accommodate thermal expansion, combined with a silicon-carbide coating to prevent adhesion and damage from silicon contact, ensuring effective shielding and durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the feed tool is made from materials that are resistant to silicon contact, then the tool's durability is improved, but the complexity of material selection and coating application increases
Solution Approach 1:
The feed tool employs a composite structure combining graphite base material with silicon-carbide coating. This composite approach provides both thermal stability from the graphite and silicon resistance from the coating layer, resolving the contradiction between durability and material selection complexity by integrating multiple material properties into a single engineered solution.
Solution Approach 2:
The silicon-carbide coating acts as an intermediary layer between the graphite tool body and the molten silicon. This intermediate protective layer prevents direct contact between silicon and the tool material, thereby improving durability while keeping the base material simple (graphite).
2Reliability
If the plate sections are made separate and movable to accommodate thermal expansion, then the tool's ability to withstand thermal stress is improved, but the structural complexity increases
Solution Approach 1:
The plate is divided into multiple separate sections that can move independently relative to each other. This segmentation allows each section to expand and contract freely in response to thermal stress without generating excessive forces, thereby improving thermal stress resistance while maintaining a relatively simple overall structure.
Solution Approach 2:
The plate sections are designed to be movable rather than rigidly fixed, allowing dynamic adjustment during thermal cycles. This dynamic capability enables the structure to adapt to temperature changes, improving thermal stress resistance without requiring complex active control systems.
3Object-generated harmful factors
If the cylinder diameter is reduced at the annular ledge to prevent silicon contact, then contamination is reduced, but the shielding effectiveness may be compromised
Solution Approach 1:
The cylinder features a local diameter reduction at the annular ledge, creating a step that prevents silicon contact at this specific location. This localized geometric modification addresses contamination concerns without requiring a complete redesign of the entire cylinder, thereby maintaining shielding effectiveness elsewhere.
Solution Approach 2:
The design converts the potential harm of silicon contact into a benefit by using the silicon-carbide coating's silicon-resistant properties. The coating transforms what would be a harmful interaction (silicon adhesion) into a beneficial protective function, allowing the tool to maintain close proximity to molten silicon without contamination.
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
The solution enhances the durability and performance of the feed tool by mitigating thermal stress and preventing contamination, allowing for efficient production of single crystal silicon ingots while maintaining tool integrity and reducing silicon adhesion.
Implementation Method 1
combined with a silicon-carbide coating to prevent adhesion and damage from silicon contact
Implementation Method 2
a plate comprising separate sections that can move laterally to accommodate thermal expansion
Data Source
AI summary
A crystal puller for melting silicon and forming a single crystal ingot and a feed tool for shielding a portion of the crystal puller during charging of the crystal puller are disclosed herein. The crystal puller includes a crucible for containing molten silicon. The feed tool includes a cylinder and a plate. The cylinder has an inner surface and an annular ledge formed in a portion of the inner surface. The cylinder has a diameter at the annular ledge that is less than a diameter of the cylinder at the inner surface. The plate is positioned on the annular ledge and includes a first section separate from a second section. The first section and the second section are operable to move laterally with respect to each other. The plate has a central opening formed in at least one of the first section and the second section.