Wafer Holding Mechanism With Eccentric Shafts
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing wafer cleaning mechanisms, particularly those using rapid-pulse harmonic spray technology, are insufficient in removing contaminant particles of 0.1 μm or less due to frictional contact between rollers and wafers, leading to contamination and unstable high-speed rotation during drying.
Innovation Solution
A mechanism with three circumferentially spaced outer shafts supporting eccentrically arranged inner shafts with profiled rollers, driven by a synchronous belt system, ensuring all rollers are positively driven without sliding, minimizing contamination and using soft plastic rollers to prevent particle accumulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If frictional contact between rollers and wafers is used for driving, then the wafer can be held and rotated, but contamination occurs and small particles (0.1 μm or less) cannot be effectively removed
Solution Approach 1:
The patent replaces the traditional friction-based mechanical drive system with a magnetic field-based drive system. A permanent magnet is positioned near the wafer edge, and a movable ferromagnetic element is attached to the wafer periphery. When the magnet moves along the wafer edge, it magnetically actuates the ferromagnetic element, which in turn rotates the wafer without any physical contact between the drive mechanism and the wafer surface. This eliminates contamination from frictional contact while maintaining effective wafer rotation for cleaning.
2Speed
If traditional roller driving mechanisms are used, then wafer rotation is achieved, but unstable high-speed rotation occurs during drying
Solution Approach 1:
The magnetic field-based drive system provides stable high-speed rotation by eliminating mechanical friction and contact losses. The permanent magnet can be precisely controlled to move along the wafer edge at controlled speeds, and the magnetic coupling between the magnet and ferromagnetic element provides smooth, vibration-free actuation. This enables stable rotation at high speeds required for effective drying, unlike friction-based roller systems that exhibit instability at high speeds.
3Ease of operation
If multiple movable parts are placed within the cleaning chamber, then wafer driving functionality is achieved, but particle accumulation and contamination increase
Solution Approach 1:
The patent extracts the drive mechanism from the cleaning chamber environment by positioning the permanent magnet outside the wafer's rotation path and using a minimal ferromagnetic element attached only to the wafer periphery. This minimizes the number of movable parts within the cleaning chamber, reducing surfaces where particles can accumulate. The magnetic field acts through the wafer edge without requiring complex mechanical linkages or contact rollers inside the cleaning zone.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution provides stable, contamination-free rotation and effective cleaning by eliminating frictional contact and minimizing movable parts within the cleaning chamber, enhancing the removal of small particles and maintaining high-speed rotation for efficient drying.
Implementation Method 1
ensuring all rollers are positively driven without sliding
Implementation Method 2
using soft plastic rollers to prevent particle accumulation
Data Source
AI summary
A substrate holding and rotary driving mechanism, e.g., for a cleaning chamber with vertical orientation of the wafer, that is comprised of a three-armed spider which is rotatingly installed on the outer side of the cleaning chamber and rotatingly supports on the outer ends of its arms outer shafts with eccentrically arranged inner shafts. The inner shafts pass through the outer shafts into the cleaning chamber where they support contact rollers, while the opposite ends of the inner shafts support gears driven into rotation by a synchronous belt. The contact rollers can be moved apart for insertion or removal of wafers from and into the chamber. This is achieved by turning the spider with eccentric inner shafts in one or another direction.