Ring-Shaped Silicon Seed Ingot Growth Control
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Solution Overview
Problem
Current silicon ingot casting technologies inefficiently use silicon material, require significant machining to shape ingots into desired forms, and are prone to contamination due to crucible coatings, leading to wasted material and reduced throughput.
Innovation Solution
A system and method for casting near net shape ingots using a ring-shaped silicon seed with controlled rotational speed and feed rate, differential heat addition, and precise dopant application, which eliminates the need for crucibles and minimizes contamination by growing ingots directly on a seed with camera feedback for diameter and meniscus angle control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If traditional crucible-based directional solidification is used to grow silicon ingots, then ingots can be produced, but significant machining is required to shape them into desired forms, resulting in wasted material
Solution Approach 1:
The patent applies preliminary action by pre-shaping the silicon seed into the desired final geometry (e.g., ring-shaped for chamber components) before the ingot growth process begins. The seed is prepared with the exact shape needed, and liquid silicon is fed onto this pre-shaped seed during directional solidification. This ensures the ingot grows into the target shape directly, eliminating the need for subsequent machining and preventing material waste.
Solution Approach 2:
The patent employs parameter changes by controlling the shape parameters of the silicon seed (dimensions, geometry, cross-sectional area) to match the desired final part shape. By varying the seed's geometric parameters and maintaining them throughout the growth process, the ingot inherits this shape, achieving near-net-shape production without extensive material removal.
2Ease of operation
If crucible coatings are applied to prevent sticking and enable ingot release, then ingot release is improved, but contamination of the ingot occurs
Solution Approach 1:
The patent applies the extraction principle by removing the crucible and its coatings from the system entirely. Instead of using a crucible to hold and release the ingot, the pre-shaped silicon seed serves as both the template and the release mechanism. The seed is suspended in the liquid silicon bath without contact with crucible walls, eliminating the source of contamination while still enabling easy ingot release through seed manipulation.
Solution Approach 2:
The patent uses the pre-shaped silicon seed as an intermediary between the liquid silicon and the final ingot product. The seed acts as a template that defines the ingot's shape and serves as a non-contaminating interface for heat transfer and solidification. This intermediary eliminates the need for crucible coatings while maintaining control over the ingot formation and release processes.
3Reliability
If sequential melting, stabilization, freezing, and annealing are performed in the same hotzone/crucible, then complete processing is achieved, but system complexity increases and throughput is reduced
Solution Approach 1:
The patent applies segmentation by dividing the processing sequence into distinct spatial zones rather than performing all operations sequentially in a single crucible. The system includes a melting zone where solid silicon is melted, a growth zone where the ingot solidifies on the seed, and separate control zones for each process step. This spatial segmentation allows parallel or rapid sequential processing, reducing cycle time and increasing throughput while maintaining complete processing.
Solution Approach 2:
The patent transitions from temporal sequencing (performing operations one after another in time) to spatial distribution (performing operations simultaneously in different locations). By arranging melting, solidification, and control functions in different spatial zones along the vertical axis of the apparatus, the system achieves complete processing without the time penalties of sequential operations in a single crucible, thereby improving throughput.
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 enables efficient silicon material utilization, reduces machining needs, minimizes contamination, and increases throughput by growing ingots that closely match the final part shape, resulting in higher yield and lower costs.
Implementation Method 1
melted silicon at a feed rate to form an ingot
Implementation Method 2
the pedestal is configured to rotate at a rotational speed
Implementation Method 3
a heater associated with the crucible configured to melt the pieces of solid silicon
Implementation Method 4
the controller receives the feedback from a camera directed to the meniscus of the ingot
Data Source
AI summary
A system comprises a silicon seed arranged on a pedestal, where the silicon seed is ring shaped and is configured to receive melted silicon at a feed rate to form an ingot, and where the pedestal is configured to rotate at a rotational speed. A controller is configured to, while the silicon seed receives the melted silicon and while the ingot is forming: receive feedback regarding a diameter of the ingot and regarding an angle of a meniscus of the ingot, and control the rotational speed of the pedestal and the feed rate of the melted silicon based on the feedback to control the diameter of the ingot and the angle of the meniscus of the ingot.