Wafer Support Plate Roughness and Diameter for Heat Treatment Stability
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Solution Overview
Problem
Conventional heat treating apparatuses for semiconductor wafers experience slips due to both damage from protrusions and excessive adhesive force caused by overly smooth support surfaces, leading to wafer warping and defects during high-temperature processing.
Innovation Solution
A heat treating apparatus with a support plate that has a surface roughness of 1 μm to 1,000 μm and a diameter of 63 to 73% of the wafer's diameter, made from silicon carbide or silicon, with a surface hardness equal to or greater than the wafer, and optionally coated with silicon oxide, silicon carbide, or silicon nitride, to minimize substrate displacement and prevent slips.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the wafer is supported at only three points, then the support structure is simple, but the wafer experiences warping and slips due to concentrated stress
Solution Approach 1:
The support structure is segmented from three discrete support grooves into a continuous support plate with distributed contact points. This segmentation distributes the wafer weight across multiple locations, preventing concentrated stress and warping while maintaining structural simplicity.
Solution Approach 2:
The support transitions from a one-dimensional groove structure to a two-dimensional plate structure. This dimensional change increases the support contact area with the wafer, distributing stress more evenly and preventing warping without significantly increasing structural complexity.
2Area of stationary object
If the support plate diameter is small, then the device is compact, but the wafer experiences excessive displacement and warping
Solution Approach 1:
The support plate diameter is optimized to 63-73% of the wafer diameter, which is the optimal parameter range that provides sufficient support area to minimize wafer displacement and warping while keeping the overall device compact and manageable.
Data Source
AI summary
To prevent both slips caused by damage from projections, and slips caused by adhesive force occurring due to excessive smoothing.The heat treating apparatus includes a processing chamber for heat treating wafers and a boat for supporting the wafers in the processing chamber. The boat further includes a wafer holder in contact with the wafer and a main body for supporting the wafer holder. The wafer holder diameter is 63 to 73 percent of the wafer diameter, and the surface roughness Ra of the portion of the wafer holder in contact with the wafer is set from 1 μm to 1,000 μm. The wafer can be supported so that the amount of wafer displacement is minimal and both slips due to damage from projections on the wafer holder surface, and slips due to the adhesive force occurring because of excessive smoothing can be prevented in that state.