Chamfering Apparatus for Silicon Wafer Edge Anisotropy
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Solution Overview
Problem
Conventional methods for chamfering silicon wafers fail to achieve the required precision in cross-sectional shape dimensions, leading to variations that exceed ±25 µm, which is a challenge for advanced node production, especially due to crystal orientation-dependent etching anisotropy causing non-uniformity in the chamfered portion after etching.
Innovation Solution
A chamfering apparatus that uses a chamfering grindstone with numerical control to adjust the relative position of the wafer and grindstone based on the circumferential position, allowing for non-uniform chamfering that compensates for etching anisotropy, resulting in a more uniform cross-sectional shape after etching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional uniform chamfering method is used, then the chamfering process is simple, but the cross-sectional shape dimensions vary by ±40 µm to ±50 µm due to etching anisotropy
Solution Approach 1:
The invention applies different chamfering amounts at different circumferential positions around the wafer edge. The chamfering amount is locally adjusted based on the crystal orientation at each position, with greater chamfering applied to regions that will experience more etching. This local differentiation compensates for etching anisotropy and achieves uniform cross-sectional dimensions after etching.
Solution Approach 2:
The invention performs preliminary chamfering adjustments before the etching process. By pre-calculating and applying compensatory chamfering amounts based on known crystal orientation and etching characteristics, the system prepares the wafer edge in advance to counteract the anticipated non-uniform etching, resulting in uniform final dimensions.
2Measurement precision
If measurement is performed at only four points, then the measurement process is fast, but the precision and representativeness of chamfer uniformity assessment is insufficient
Solution Approach 1:
The invention divides the wafer edge into multiple measurement points (9 or more points at 40° intervals) around the circumference. This segmentation allows comprehensive assessment of chamfer uniformity at different crystal orientations, providing statistically significant data to evaluate whether the chamfering process achieved the required precision.
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 significantly reduces variations in the cross-sectional shape dimensions of the chamfered portion to ±10 µm or less, meeting the stringent requirements for high-precision silicon wafers, particularly for the 32 nm node, by accounting for and mitigating the effects of crystal orientation-dependent etching.
Implementation Method 1
a chamfering grindstone chamfering an outer edge of a silicon wafer held by the holder
Implementation Method 2
crystal orientation-dependent etching anisotropy causing non-uniformity in the chamfered portion after etching
Data Source
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AI summary
The invention is directed to a chamfering apparatus for a silicon wafer to chamfer outer edge of a silicon wafer by using a chamfering grindstone, the chamfering apparatus including at least: a holder holding and rotating a silicon wafer; a chamfering grindstone chamfering the outer edge of the silicon wafer held by the holder; and a control apparatus for controlling a chamfered shape by controlling a relative position of the outer edge of the silicon wafer and the chamfering grindstone by numerical control, wherein the control apparatus controls and changes the relative position of the outer edge of the silicon wafer and the chamfering grindstone at the time of chamfering depending on the circumferential position of the silicon wafer held by the holder, a production method, and an etched silicon wafer. This provides a silicon wafer chamfering apparatus, production method and an etched silicon wafer that can suppress variations in the cross-sectional shape dimensions of a chamfered portion after an etching process.