Wafer Lift Ring System for Thermal Uniformity and Arcing Prevention
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Solution Overview
Problem
Existing substrate lift systems in substrate processing systems are complex, expensive, and complicate thermal uniformity control due to the presence of lift pins within the substrate support, which also risk arcing and hollow cathode discharge.
Innovation Solution
A lift ring system surrounding the substrate support is introduced, with lift pins positioned outside the support, allowing for adjustable height control to facilitate substrate transfer and processing without affecting thermal uniformity or causing arcing, and featuring a segmented design for easy robot access.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If lift pins are arranged within the substrate support, then substrate transfer function is achieved, but thermal uniformity control is complicated and risk of arcing increases
Solution Approach 1:
The lift pins are extracted from the substrate support structure and repositioned to surround the substrate support from the exterior. This separation eliminates the harmful effects of having conductive lift pins within the support structure, preventing arcing and maintaining thermal uniformity while preserving the substrate transfer function.
Solution Approach 2:
The lift mechanism is segmented into multiple lift pins arranged in a circular pattern around the substrate support. This segmentation allows the substrate to be lifted uniformly from multiple points simultaneously, ensuring stable transfer while keeping each individual lift pin outside the support structure to avoid thermal and electrical interference.
2Object-affected harmful factors
If lift pins are positioned outside the substrate support, then thermal uniformity is maintained and arcing is prevented, but substrate transfer accessibility may be reduced
Solution Approach 1:
The lift pins are made dynamically controllable, allowing selective raising and lowering. During substrate transfer, the lift pins can be raised to provide clearance for robot access. During processing, they are lowered to support the substrate at the appropriate height, thus maintaining both accessibility and operational functionality.
Solution Approach 2:
The lift pins are raised in advance before substrate transfer operations to clear the path for the robot. This preliminary action ensures that the robot can access the substrate without obstruction, while the lift pins remain positioned outside the support structure to maintain thermal uniformity and prevent arcing.
3Ease of operation
If segmented lift ring design is used, then robot access is improved and maintenance is simplified, but device complexity increases
Solution Approach 1:
The lift ring is segmented into multiple independent lift pins rather than being a continuous structure. This segmentation allows the robot to access the substrate from different angles and simplifies maintenance, as individual lift pins can be inspected or replaced without affecting the entire structure. The modular design actually reduces complexity compared to a monolithic lift ring.
Solution Approach 2:
The segmented lift ring design serves multiple functions: it provides substrate support, enables robot access through selective positioning, facilitates maintenance of individual components, and maintains thermal uniformity. This multi-functionality justifies the structural design while avoiding unnecessary complexity.
Data Source
AI summary
A substrate support includes an inner portion arranged to support a substrate, a lift ring surrounding the inner portion, the lift ring arranged to support an outer edge of the substrate, and a controller configured to control an actuator to adjust a height of the lift ring relative to the inner portion by selectively raising and lowering at least one of the lift ring and the inner portion of the substrate support. To adjust the height of the lift ring, the controller selectively adjusts the height of the lift ring to a transfer height for transfer of the substrate to the lift ring and retrieval of the substrate from the lift ring, and adjusts the height of the lift ring to a processing height for processing of the substrate.