Single Crystal Blank Grinding for Seed Crystal Reuse
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Solution Overview
Problem
The high cost and one-time use of seed crystals in growing single crystals for semiconductor and optical devices lead to inefficient production, as these crystals are not reusable and result in varying quality, especially when producing small batches or single wafers, and the shift to materials like silicon carbide further increases expenses.
Innovation Solution
A method and apparatus for processing single crystal blanks that allow the seed crystal to be reused by grinding only the grown single crystal to the desired shape and size, while maintaining the seed crystal's dimensions and quality, using peripheral surface grinding and potentially additional steps like laser beam focusing for wafer production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the single crystal blank is ground to the desired shape and size, then the manufacturing quality is improved, but the seed crystal is damaged and cannot be reused
Solution Approach 1:
The single crystal blank is divided into two distinct parts: the seed crystal and the grown single crystal. The grinding process is applied only to the grown single crystal portion, while the seed crystal portion is protected and left intact. This segmentation allows selective processing that preserves the seed crystal for reuse while still achieving the desired shape and size for the final product.
Solution Approach 2:
Different parts of the single crystal blank are treated differently during the grinding process. The grown single crystal region is ground to the precise shape and size requirements, while the seed crystal region is excluded from grinding to maintain its integrity and reusability. This local differentiation of processing quality enables both precision manufacturing and resource conservation.
2Reliability
If a new seed crystal is used for each wafer production, then the quality consistency is improved, but the production cost increases
Solution Approach 1:
Instead of discarding the seed crystal after a single use, the process recovers and reuses the seed crystal for multiple production cycles. The seed crystal is carefully preserved during the grinding and processing of the grown single crystal, then reused to generate new single crystal blanks. This recovery approach maintains quality consistency while significantly improving production efficiency and reducing costs.
3Manufacturing precision
If the seed crystal is ground along with the grown single crystal, then the manufacturing quality is improved, but the seed crystal quality is degraded
Solution Approach 1:
The processing system segments the single crystal blank into a seed crystal portion and a grown single crystal portion, applying different processing intensities to each. The grown single crystal receives full grinding treatment for high surface quality, while the seed crystal portion is protected from grinding to maintain its superior crystal quality and structural integrity for reuse.
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 approach reduces manufacturing costs by reusing high-quality seed crystals, ensuring consistent production quality, and allowing for the production of multiple wafers from a single seed crystal, thereby improving efficiency and reducing the need for new seed crystals.
Implementation Method 1
a peripheral surface grinding step of grinding a peripheral surface of the single crystal blank at least partially along the longitudinal axis
Implementation Method 2
the method may further comprise a wafer producing step of producing a wafer from the single crystal blank, the wafer having a predetermined thickness along (in the direction of) the longitudinal axis
Data Source
AI summary
The disclosed method is for processing a single crystal. The single crystal has a first end, a second end and a longitudinal axis between said first end and said second end. The single crystal comprises a seed crystal, wherein the seed crystal extends at least partially along the longitudinal axis. The method comprises a peripheral surface grinding step of grinding a peripheral surface of the single crystal at least partially along the longitudinal axis. The peripheral surface of the single crystal is ground up to a first distance to the longitudinal axis at least partially along a portion of the longitudinal axis excluding the seed crystal, wherein the first distance is preferably less than an extension of the seed crystal to the longitudinal axis.