Self-Extracting Wafer Edge Grips for Controlled Release
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Solution Overview
Problem
Existing edge grip wafer handlers in semiconductor processing suffer from unpredictable release and damage due to excessive or insufficient friction, especially with thin or flexible wafers, and require a steeper wedge angle for rotation, leading to potential wafer damage and improper release.
Innovation Solution
A self-extracting wedge clamp system with spring-loaded sliding cams that apply pressure to the wafer circumference for secure grip and controlled release, using a cam travel path and servo motor-driven camming mechanism to ensure precise positioning and release.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a passive self-releasing wedge clamp with approximately 75° wedge angle is used, then the wedge clamp will not exert undue friction and will be self-releasing, but the angle is insufficient to retain an inverted or rotated wafer and may cause self-release at undesired times
Solution Approach 1:
The system performs preliminary action by actively controlling the wedge clamp engagement and release timing through the robotic system, rather than relying on passive self-release. The cam mechanism is pre-positioned to ensure proper engagement sequence, and the robotic control system anticipates the need for release before it occurs naturally, allowing for reliable retention during inversion/rotation while ensuring release at the desired moment.
2Reliability
If a steeper wedge clamp angle and deeper wedge base are used for rotating wrist end effector, then the rotation will not improperly self-release a wafer, but undue friction is exerted at the desired timing of release, causing lack of desired release and potential wafer damage
Solution Approach 1:
The system replaces the purely mechanical passive wedge clamp release mechanism with a controlled cam-based extraction system. Instead of relying on wedge angle geometry alone to control both retention and release, the cam mechanism provides a controlled extraction path that reduces friction during release. The robotic system controls the timing and manner of extraction, substituting uncontrolled mechanical self-release with a controlled process that minimizes harmful friction effects.
3Force
If edge clamps cover a portion of the outer circumference of the wafer, then the wafer can be gripped securely, but the clamps or tooling may cause snags on the wafer and consequently damage the wafer
Solution Approach 1:
The cam mechanism acts as an intermediary between the gripping system and the wafer edge during release. Instead of the wedge clamp directly contacting and potentially snagging the wafer, the cam provides a controlled extraction interface that guides the wafer edge smoothly out of the clamp. This intermediary mechanism reduces direct friction and snagging risks while maintaining secure gripping during transport.
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
Enhances wafer handling by providing consistent, controlled release and improved positioning, reducing damage and ensuring accurate placement during processing and transfer.
Implementation Method 1
Each of at least one of the distal and the proximal wedge clamps comprises: a spring; a cam loaded on the spring
Implementation Method 2
a contraction of the inner jaws and a consequent arms camming of the outer arms applies pressure to a circumferential edge of the semiconductor wafer
Data Source
Figure 1
Figure 2
Figure 3A~3B
AI summary
An apparatus, system and method for a wedge clamp suitable to provide self extracting grips for an end effector suitable to hold semiconductor wafers, or other substrates such as rectangular panels. The apparatus, system and method may include two inner jaws at least mechanically associated with a robotic base; two outer arms associated with the inner jaws via at least one arms cam; and a plurality of wedge clamps. Each of the wedge clamps may comprise: a spring; a cam loaded on the spring; and a cam travel path into which the cam is slidably associated. A contraction of the inner jaws and a consequent arms camming of the outer arms applies pressure to a circumferential edge of the semiconductor wafer such that the circumferential edge depresses each of the cams along its respective cam travel path and against its respective one of the springs. The jaws close may synchronously about a center point of the substrate, thereby keeping it centered.