Round Groove Gripper for Semiconductor Wafer Stability
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Solution Overview
Problem
Conventional semiconductor wafer shape measuring apparatuses face issues with deformation and reproducibility due to stress concentration when the gripper is inclined, leading to inconsistent measurement values and reduced correlativity between apparatuses.
Innovation Solution
A strip-like gripper with a round shape and a groove along its side surface is used to hold the semiconductor wafer, allowing stable gripping even when inclined, with the groove's curvature radius larger than the wafer's edge, and made from synthetic resin to minimize stress and prevent deformation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a strip-like gripper with a linear side is used to hold the wafer, then the wafer can be pressed to prevent coming off during rotation, but the gripper cannot be stably held when inclined and stress concentration occurs
Solution Approach 1:
The gripper is designed with a round shape instead of a linear shape, and the groove that contacts the wafer edge has a curved cross-section. This curvature allows the gripper to maintain stable contact with the wafer even when inclined, distributing stress evenly and preventing the sensitivity to inclination angles that plagues linear designs.
2Reliability
If the gripper applies fixed stress to press the wafer, then the wafer is prevented from coming off during rotation, but the wafer shape is deformed
Solution Approach 1:
The gripper applies pressure locally through a groove that contacts only the edge of the wafer, rather than pressing across the entire wafer surface. This localized contact prevents deformation of the wafer body while still providing sufficient retention force to prevent the wafer from coming off during rotation.
Solution Approach 2:
The curved cross-section of the groove distributes the contact stress along the wafer edge, preventing concentration of force at a single point. This curvature allows the gripper to hold the wafer securely while minimizing deformation, as the rounded contact interface naturally distributes the applied stress.
3Ease of manufacture
If the gripper is set with slight inclination due to flexure adjustment width, then the gripper can be installed with tolerance, but the holding positions are not at intervals of 120 degrees and reproducibility deteriorates
Solution Approach 1:
The round shape of the gripper and the curved groove design make the holding mechanism insensitive to small inclination angles. Even when the gripper is slightly inclined due to flexure adjustment tolerance, the curved surfaces maintain proper contact with the wafer edge, ensuring that holding positions remain effectively at 120-degree intervals and preserving measurement reproducibility.
Data Source
AI summary
The present invention provides a strip-like holding gripper which holds a semiconductor wafer when measuring a shape of the semiconductor wafer, wherein a side where the semiconductor wafer is held has a round shape, a groove which holds an edge of the semiconductor wafer along a side surface of the round shape portion is provided on the side surface, and the groove comes into contact with the edge of the semiconductor wafer from a periphery of the wafer to hold the semiconductor wafer. As a result, it is possible to provide the gripper, which can stably hold the wafer in a fixed state even if the gripper is inclined when holding the wafer, a holding method, and a shape measuring apparatus.