Wafer Holding Rollers With Synchronized Eccentric Shaft Control
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Solution Overview
Problem
Existing substrate holding apparatuses face challenges in stabilizing the rotation of substrates due to phase synchronization issues and vibration propagation among eccentric shafts, leading to unstable substrate holding and processing inefficiencies.
Innovation Solution
The apparatus incorporates eccentric shafts with movable and reference shafts, actuated by electric motors and controlled by an operation controller to ensure synchronized rotation and minimize vibration, using a non-contact distance sensor to monitor and adjust movement, and a diaphragm-based actuator to prevent sliding resistance and excessive load on the substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple eccentric shafts are used to rotate the substrate while making circular motion, then processing efficiency is improved, but vibration propagation occurs among shafts causing unstable substrate holding
Solution Approach 1:
The patent divides the support structure into separate support plates for each eccentric shaft, isolating the shafts from common vibration. Each shaft is mounted on its own dedicated support plate, preventing vibration propagation between shafts while maintaining the multi-shaft configuration needed for efficient substrate processing
Solution Approach 2:
The patent introduces an actuator as an intermediary mechanism to independently control the position of each eccentric shaft. This allows precise phase synchronization of the shafts while preventing direct mechanical coupling that would cause vibration transmission, enabling stable substrate holding during high-speed circular motion
2Reliability
If phase synchronization of eccentric shafts is achieved, then stable substrate rotation is improved, but complex control mechanisms are required
Solution Approach 1:
The patent employs actuators that can independently and autonomously adjust the position of each eccentric shaft based on control signals. This self-adjusting capability enables automatic phase synchronization without requiring complex mechanical linkages or synchronization mechanisms, simplifying the overall control system while maintaining reliable phase coordination
3Ease of operation
If rollers are used to contact substrate periphery, then substrate rotation is achieved, but processing tool access is restricted
Solution Approach 1:
The patent implements circular motion of the substrate in addition to its rotation about its own axis. This adds a spatial dimension to substrate movement, allowing the substrate to traverse the processing tool's working area in a circular path while rollers maintain rotational control, thereby enabling full surface access without compromising rotation control
Data Source
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AI summary
A substrate holding apparatus which can stably hold a substrate, such as a wafer, while causing the substrate to make a circular motion and rotating the substrate about its axis is disclosed. The substrate holding apparatus includes: rollers; electric motors configured to rotate the rollers; eccentric shafts arranged around a central axis; and actuators. The eccentric shafts include movable shafts and reference shafts, the actuators are coupled to the movable shafts, respectively, and the actuators are configured to move the movable shafts in a direction closer to the reference shafts and in a direction away from the reference shafts.