Vacuum End Effector with Knife-Edge Supports for Wafer Handling
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Solution Overview
Problem
Conventional robotic vacuum chuck end effectors cause backside contamination and damage to semiconductor wafers due to particulate transfer and difficulty in achieving a low leak rate vacuum seal, especially with warped or imperfectly aligned wafers, and edge grip end effectors are complex and unsuitable for thin wafers.
Innovation Solution
A low-profile vacuum end effector with self-aligning, replaceable workpiece supports featuring a circular knife-like edge for minimal contact and a gimbal joint for effective vacuum sealing, accommodating distorted wafer surfaces and allowing easy replacement of supports.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If conventional vacuum chuck end effectors are used, then wafer transfer is achieved, but particulate contamination and damage occur on the wafer backside
Solution Approach 1:
The patent employs a thin film membrane as the vacuum sealing surface that can conform to warped wafer surfaces. This flexible membrane creates a vacuum seal without requiring rigid contact surfaces, thereby preventing particulate contamination and damage to the wafer backside while maintaining reliable vacuum attachment.
Solution Approach 2:
The end effector design segments the vacuum sealing function from the structural support function. The thin film membrane provides the sealing surface while the underlying structure provides support, allowing the sealing surface to be extremely thin and flexible without compromising structural integrity.
2Object-affected harmful factors
If edge grip end effectors are used, then particulate contamination is minimized, but device complexity increases and they are unsuitable for thin wafers
Solution Approach 1:
The patent extracts only the essential function of edge support from complex edge grip mechanisms. By using simple protruding features that provide minimal support while the vacuum membrane provides the primary attachment, the design achieves low particulate contamination without the complexity of actuated protrusions or multiple components.
Solution Approach 2:
The patent changes the parameter of contact area from the large contact areas of conventional chucks to the minimal contact of edge support features combined with distributed vacuum pressure. This parameter change enables handling of thin wafers with minimal mechanical interference while maintaining grip reliability.
3Reliability
If full vacuum pressure is applied to thin wafers, then secure attachment is achieved, but wafer warping and deformation occur
Solution Approach 1:
The flexible membrane distributes vacuum pressure evenly across the wafer surface, preventing localized high stress that causes warping. The membrane's flexibility allows it to conform to slight surface variations without requiring excessive vacuum force, thereby maintaining attachment reliability while preserving wafer flatness.
Solution Approach 2:
The thin film membrane acts as a cushioning element between the vacuum source and the wafer. This cushioning layer prevents direct transmission of high vacuum forces that could deform thin wafers, while still maintaining effective attachment through distributed pressure.
4Ease of repair
If replaceable workpiece supports are implemented, then maintenance ease is improved, but device complexity increases
Solution Approach 1:
The patent segments the replaceable membrane from the permanent end effector body. The membrane can be independently removed and replaced without affecting the structural components, providing easy maintenance while keeping the overall device structure simple and robust.
Solution Approach 2:
The thin film membrane is designed as a low-cost, replaceable component that can be easily replaced when worn or contaminated. This disposable approach to the sealing surface simplifies maintenance procedures while keeping the expensive structural components permanent and reusable.
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 minimizes particulate transfer, ensures reliable vacuum sealing, and reduces deformation stress on fragile wafers, while being suitable for a wide range of support materials and easy maintenance, accommodating various wafer profiles and thicknesses.
Implementation Method 1
A vacuum source provides a vacuum pressure differential across the membrane sufficient to hold the workpiece against the workpiece supports
Data Source
AI summary
The present invention comprises a vacuum end effector having workpiece supports that work in conjunction with distorted workpiece surfaces. In one embodiment, each workpiece support has the ability to gimbal and conform the workpiece surface in contact with an outer edge of the support. Each workpiece support preferably provides a knife-like contact edge to minimize the contact area between the support and the workpiece while still providing an effective vacuum area to hold the wafer securely on the support. In another embodiment, each workpiece support is replaceable without having to remove the end effector from the robot assembly.