Bellows Lift Pin Assembly for Arc-Free Electrostatic Chucks
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Solution Overview
Problem
In plasma processing chambers, arcing can occur through lift pin holes in electrostatic chucks, damaging substrate support components.
Innovation Solution
A lift pin mechanism with a bellows assembly is introduced, where the bellows assembly includes an upper bellows flange, a bellows, and a bellows guide assembly. This configuration allows for axial movement of the lift pin, maintaining it at high voltage potential and eliminating line of sight between the substrate and ground through lift pin holes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If lift pin holes are formed through the electrostatic chuck to accommodate lift pins, then substrates can be raised and lowered onto the support surface, but arcing can occur through the lift pin holes damaging the substrate support components
Solution Approach 1:
The bellows assembly serves as an intermediary component between the lift pin and the electrostatic chuck. It provides electrical isolation while allowing mechanical movement, preventing arcing from reaching the substrate support components. The bellows acts as a mediator that decouples the electrical and mechanical functions in the lift pin assembly.
Solution Approach 2:
The bellows assembly creates an electrically isolated environment around the lift pin shaft. By enclosing the shaft in a sealed bellows structure that maintains electrical potential, it creates an 'inert' electrical environment that prevents harmful arcing interactions with grounded components.
2Ease of operation
If the lift pin is made axially movable to raise and lower substrates, then substrate positioning is enabled, but the lift pin may come into contact with ground through lift pin holes causing arcing
Solution Approach 1:
The bellows assembly acts as an intermediary that maintains electrical isolation during axial movement. It allows the lift pin to move vertically for substrate positioning while simultaneously preventing electrical contact with ground, mediating between mechanical mobility and electrical safety.
Solution Approach 2:
The bellows assembly uses a flexible sealed structure that can accommodate axial movement of the lift pin while maintaining electrical isolation. The flexible shell design allows motion without compromising the electrical barrier, enabling both positioning and arcing prevention.
3Reliability
If a bellows assembly is introduced to prevent arcing and maintain high voltage potential, then reliability is improved, but device complexity increases
Solution Approach 1:
The bellows assembly performs multiple functions simultaneously: it provides electrical isolation to prevent arcing, allows axial movement for substrate positioning, and maintains the lift pin at high voltage potential. By consolidating these functions into a single component, the overall device complexity is managed despite the added reliability features.
Solution Approach 2:
The invention merges the electrical isolation function, mechanical movement function, and high voltage maintenance function into a single integrated bellows assembly. This consolidation reduces the number of separate components needed, thereby limiting the increase in device complexity while achieving improved reliability.
Data Source
AI summary
Methods and apparatus for a lift pin mechanism for substrate processing chambers are provided herein. In some embodiments, the lift pin mechanism includes a lift pin comprising a shaft with a top end, a bottom end, and a coupling end at the bottom end; a bellows assembly disposed about the shaft. The bellows assembly includes an upper bellows flange having an opening for axial movement of the shaft; a bellows having a first end coupled to a lower surface of the upper bellows flange such that the shaft extends into a central volume surrounded by the bellows; and a bellows guide assembly coupled to a second end of the bellows to seal the central volume. The shaft is coupled to the bellows guide assembly at the coupling end. The bellows guide assembly is axially movable to move the lift pin with respect to the upper bellows flange.