Grind Wheel Ring Geometry for Low Edge-Roll SiC Wafer Grinding
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Solution Overview
Problem
Grinding processes for silicon carbide semiconductor wafers face challenges such as excessive tool wear, heat generation, crack formation, and non-uniform material removal leading to edge roll and reduced usable surface area due to the abrasive and brittle nature of silicon carbide.
Innovation Solution
A grind wheel design with a grinding ring having a radius less than or equal to the wafer radius and an effective gap ratio of 0.8 or less between grinding teeth, along with a continuous abrasive ring, reduces edge roll by minimizing tooth contact with the wafer edge, enhancing surface area utilization and tool longevity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If traditional grind wheels with larger grinding rings are used, then material removal efficiency is improved, but edge roll increases and usable surface area decreases
Solution Approach 1:
The grind wheel is designed with a smaller grinding ring radius that is less than or equal to the wafer radius, creating a localized grinding zone that avoids excessive contact with the wafer edge. This local quality approach concentrates material removal in the central region while minimizing edge roll, thus maintaining both productivity and manufacturing precision
Solution Approach 2:
The grinding process is segmented by using multiple grind wheels with different configurations (different radii, tooth arrangements, and gap ratios) for different stages of wafer processing. This segmentation allows optimization of each stage - coarse grinding for material removal and fine grinding for edge roll reduction - thereby resolving the contradiction between productivity and precision
2Duration of action of stationary object
If grind wheels with larger tooth gaps are used, then tool wear is reduced, but manufacturing precision deteriorates due to increased edge roll
Solution Approach 1:
The effective gap ratio between grinding teeth is optimized to 0.8 or less, representing a specific parameter change from traditional designs. This parameter optimization balances tooth contact frequency with material removal uniformity, reducing edge roll while maintaining acceptable tool wear characteristics through the smaller grinding ring design
Solution Approach 2:
The grind wheel design incorporates dynamic considerations by optimizing the relationship between tooth pitch, gap ratio, and rotational speed. The smaller grinding ring with reduced effective gap ratio creates a more dynamic interaction between teeth and wafer surface, distributing contact forces more evenly and reducing both edge roll and localized tool wear
3Productivity
If silicon carbide wafers are ground with conventional methods, then material removal is achieved, but heat generation and crack formation occur due to the abrasive and brittle nature of silicon carbide
Solution Approach 1:
The grinding process uses partial action by employing a smaller grinding ring that contacts only a portion of the wafer surface at any given time. This reduces the total heat generation in any localized area and allows better heat dissipation, preventing thermal damage and crack formation while maintaining overall material removal productivity through continuous processing
Solution Approach 2:
The grinding action is segmented into multiple passes and zones, with the smaller grinding ring creating distributed contact points rather than continuous broad contact. This segmentation reduces peak heat generation and minimizes thermal stress concentration, thereby preventing crack formation in the brittle silicon carbide material while maintaining material removal efficiency
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 design reduces edge roll, increases usable surface area, and decreases tool consumption, thereby improving the quality and efficiency of silicon carbide wafer processing.
Implementation Method 1
The grind wheel has a plurality of grinding teeth arranged in a grinding ring on the grind wheel... providing a surface of the semiconductor workpiece against a grinding ring on a grind wheel... implementing a grinding operation on the semiconductor workpiece
Data Source
AI summary
Grinding systems and methods for semiconductor workpieces are provided. In one example, a grinding system includes a workpiece support operable to support a semiconductor workpiece and rotate the semiconductor workpiece about a first axis. The grinding system further includes a grind wheel operable to rotate about a second axis. The grind wheel has a plurality of grinding teeth arranged in a grinding ring on the grind wheel. A radius of the grinding ring is less than or equal to a radius of the semiconductor workpiece (e.g., such that an effective gap ratio between grinding teeth on the grind wheel are reduced).