Segmented Substrate Support Bushing for Lift Pin Guidance
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Solution Overview
Problem
Conventional substrate support bushings and lift pins in deposition chambers tend to bend, tilt, and suffer from film deposition, leading to frequent damage and replacement, causing downtime due to choking during substrate transfer processes.
Innovation Solution
A substrate support bushing with an elongated housing and a longitudinal bore featuring passageway slots along its entire length to guide the lift pin, allowing axial movement and preventing film deposition, combined with a cross hole for gas venting and cleaning, which reduces the likelihood of pin breakage and extends the service life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If conventional bushings are used to house lift pins in deposition chambers, then the lift pins can be extended through the support pedestal to facilitate substrate transfer, but the lift pins tend to bend or tilt in the bushing after repetitive loading and unloading, and film deposition occurs on the inside of the bushing causing the lift pins to choke and break
Solution Approach 1:
The bushing is divided into multiple segments or sections that can move independently relative to each other along the lift pin. This segmentation allows the bushing to flex and accommodate the lift pin's movement without binding, preventing the choking and breakage that occurs in conventional solid bushings. The segmented structure maintains guidance while allowing necessary axial and radial movements.
Solution Approach 2:
The bushing transitions from a static, rigid structure to a dynamic structure that can adapt its shape and position. The segmented sections can move relative to each other in response to the lift pin's axial movement and radial expansion/contraction during operation. This dynamic behavior prevents film deposition choking and reduces mechanical stress on the lift pin.
2Productivity
If the bushing is exposed to process gases during substrate processing, then film deposition can occur on the substrate, but film deposition also inadvertently occurs on the inside of the bushing causing the lift pins to choke
Solution Approach 1:
The harmful effect of film deposition on the bushing interior is eliminated by removing the continuous internal surface that collects deposits. The segmented design creates gaps between sections that prevent film accumulation from choking the lift pin movement. Any deposited material falls into the gaps between segments rather than building up on a continuous surface.
Solution Approach 2:
The bushing structure incorporates a porous or gap-filled design where the spaces between segmented sections allow process gases to pass through without depositing film on continuous surfaces. The gaps act as traps for any deposited material, preventing it from accumulating on critical movement surfaces.
3Ease of operation
If the lift pin moves axially through the bore to space the substrate from the support pedestal, then substrate transfer is enabled, but the lift pin bends or tilts in the bushing after repetitive loading and unloading
Solution Approach 1:
The bushing is segmented into multiple movable sections that can independently adjust their position to accommodate the lift pin's axial movement. This segmentation allows the bushing to maintain proper alignment guidance while flexing to prevent bending and tilting of the lift pin during repetitive operations.
Solution Approach 2:
The bushing's physical parameters (shape, position, spacing between segments) change dynamically in response to the lift pin's movement. The segments can expand, contract, or shift position to maintain optimal clearance and alignment, preventing the lift pin from bending or tilting during axial movement and substrate transfer operations.
Data Source
AI summary
In one embodiment, a substrate support bushing for a lift pin used in a semiconductor processing chamber is provided. The bushing includes an elongated housing sized to guide the lift pin in a substrate support pedestal. The housing has a longitudinal bore formed through the housing. The housing includes at least one passageway slot extending and open to substantially the entire length of the bore. In another embodiment, a method for transferring a substrate from a substrate support pedestal is provided. The method includes displacing a lift pin through a central bore toward a substrate disposed on a substrate support pedestal. The bore has at least one slot extending substantially along and open to the central bore. The method further includes spacing the substrate from the substrate support pedestal on the lift pin.