Linear Bearing Spacer Design for High-Temperature Vacuum Transport
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Solution Overview
Problem
Semiconductor processing equipment faces challenges in maintaining reliable operation in thermally elevated vacuum environments due to the degradation of lubricants and increased mechanical contact sensitivity, leading to reduced service life and production losses.
Innovation Solution
A substrate transport apparatus with a bearing configuration that includes rolling load bearing elements and undersized spacer elements, minimizing friction and vibration, allowing for extended maintenance-free operation in temperatures up to 700°C and reducing mechanical contact with semiconductor substrates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If rolling elements with lubricants are used in vacuum environment at elevated temperatures, then reliable operation is achieved at lower temperatures, but service life is significantly reduced at temperatures above 150°C due to lubricant evaporation
Solution Approach 1:
The patent removes the lubricant component from the bearing system entirely, extracting the harmful element that evaporates at elevated temperatures. This creates a lubricant-free bearing design that eliminates the service interval requirement while maintaining reliable operation in vacuum environments at temperatures up to 700°C
Solution Approach 2:
The patent replaces the mechanical lubrication system with a dry friction-based rolling element bearing design. The rolling elements operate without lubricant, using purely mechanical contact between the rolling elements and raceways, which eliminates the temperature-dependent lubricant evaporation problem
2Duration of action of stationary object
If rolling elements are serviced to extend service intervals, then maintenance frequency is reduced, but mechanical contact sensitivity increases causing thin film fracture and wafer defects
Solution Approach 1:
The patent extracts the lubricant component that necessitates periodic servicing, creating a lubricant-free bearing that requires no maintenance intervals. This eliminates the need to service rolling elements, thereby avoiding the mechanical contact and vibration that occurs during servicing operations
Solution Approach 2:
The bearing design is self-sufficient without requiring external lubrication or maintenance. The rolling elements operate autonomously without lubricant, eliminating the service interval requirement and the associated mechanical contact harm to semiconductor substrates
3Ease of operation
If traditional bearings with lubricants are used, then initial operation is smooth, but production losses occur due to service interruptions and requalification after maintenance
Solution Approach 1:
The lubricant-free bearing design enables continuous operation without service interruptions. The bearing maintains reliable operation throughout its entire service life without requiring maintenance, eliminating production losses associated with service interruptions and requalification processes
Solution Approach 2:
The bearing is designed to be maintenance-free and self-sufficient, operating continuously without external intervention. This eliminates service interruptions and the associated productivity losses from stopping equipment, servicing bearings, and requalifying processes
Data Source
AI summary
A vacuum substrate transport apparatus including a frame, a drive section having a drive axis, at least one arm, having an end effector for holding a substrate, having at least one degree of freedom axis effecting extension and retraction, and a bearing defining a guideway that defines the axis, the bearing including at least one rolling load bearing element disposed in a bearing case, interfacing between a bearing raceway and bearing rail to support arm loads, and effecting sliding of the case along the rail, and at least one rolling, substantially non-load bearing, spacer element disposed in the case, intervening between each of the load bearing elements, wherein the spacer element is a sacrificial buffer material compatible with sustained substantially unrestricted service commensurate with a predetermined service duty of the apparatus in a vacuum environment at temperatures over 260° C. for a specified predetermined service period.