Wafer Chuck Assembly With Active Centering and Vacuum Status Detection
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Solution Overview
Problem
Existing wafer chucks fail to actively center wafers during edge bevel removal (EBR) processes, leading to poor results due to wafer slipping, chemical rebound, and unreliable detection, which can damage chuck components and cause further errors.
Innovation Solution
A wafer chuck assembly with a centering hub and cams that actively center the wafer using rotational movement, combined with vacuum pads for secure grip and detection, ensuring accurate placement and minimizing chemical splash-back.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If friction pads or passive centering means are used in existing chucks, then the structure is simple, but the wafer cannot be actively centered leading to poor EBR results
Solution Approach 1:
The patent implements an active centering mechanism where the chuck hub can rotate relative to the centering hub during wafer centering operations. This dynamic capability allows the system to actively adjust and center the wafer position, transforming the static passive centering means into a dynamic active centering system that achieves uniform EBR results.
Solution Approach 2:
The system performs wafer centering as a preliminary action before the EBR process. The chuck rotates the wafer to a centered position on the vacuum chuck, ensuring proper alignment before chemical application. This preliminary centering action prevents poor EBR results that would occur without proper positioning.
2Manufacturing precision
If VAP surfaces are used for wafer support during EBR, then the support structure is stable, but chemical rebound occurs leading to poor EBR results
Solution Approach 1:
The patent removes the VAP (Vertical Alignment Pin) surfaces from the wafer support structure during EBR operations. By eliminating these peripheral support surfaces, the system prevents chemical rebound that occurs when etchants bounce off the VAP surfaces. The wafer is supported only by the vacuum chuck surface, which does not cause rebound issues.
3Manufacturing precision
If conventional chuck supports are used, then the grip structure is simple, but wafers can slip during rotation causing poor centering
Solution Approach 1:
The patent employs a vacuum chuck system that uses vacuum pressure to grip the wafer securely during rotation and centering operations. The vacuum force prevents the wafer from slipping on the chuck supports, ensuring accurate centering and positioning throughout the process.
4Reliability
If external sensors are used for wafer presence detection, then the detection system is simple, but detection reliability is low due to water droplet splash-back
Solution Approach 1:
The system uses the vacuum chuck's own vacuum pressure as the detection mechanism. By monitoring the vacuum pressure level, the system can detect wafer presence and proper seating without requiring separate external sensors that would be vulnerable to water droplet splash-back. The vacuum system serves both the gripping function and the detection function.
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 provides precise wafer centering, reducing damage to chuck components and improving EBR quality by eliminating splash-back surfaces and enhancing grip forces, allowing for higher processing speeds and reduced deformities.
Implementation Method 1
a vacuum pad disposed on at least one of the plurality of chuck arms, the vacuum pad to support and clamp the wafer in the chuck assembly
Implementation Method 2
a centering hub and cams that actively center the wafer using rotational movement
Implementation Method 3
control means for detecting a torque of the chuck motor and correlating the detected chuck motor torque with a centered position of a wafer held in the chuck assembly
Data Source
AI summary
Some examples provide a vacuum wafer chuck assembly for supporting a wafer. An example chuck assembly comprises a chuck hub and a centering hub disposed within the chuck hub. Chuck arms are mounted to the chuck hub, with each chuck arm extending radially between a proximal end adjacent the chuck hub, and a distal end remote therefrom. At least one vacuum pad is provided for supporting the wafer during a wafer centering or wafer processing operation. A vacuum sensor detects a presence or absence of a vacuum pressure at the vacuum pad during the wafer centering or processing operation, a detection indicative of a presence or absence of the wafer in the chuck assembly, or a presence of a defective wafer.