Conical Cleaning Brush for Semiconductor Wafer Slippage
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Solution Overview
Problem
Conventional cylindrical brushes experience slippage when engaging rotating semiconductor wafers due to mismatched linear speeds between the brush and the substrate, leading to inefficiencies in cleaning larger substrates.
Innovation Solution
A conically-shaped brush with a hollow bore and varying cross-sectional areas along its length, ensuring that the linear speed of points on the brush matches the linear speed of adjacent points on the substrate, reducing slippage by maintaining a consistent velocity difference within ±10%.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a cylindrical brush is used to clean a rotating substrate, then the brush structure is simple and easy to manufacture, but slippage occurs between the brush and substrate due to mismatched linear speeds
Solution Approach 1:
The brush is changed from a cylindrical shape with constant diameter to a conical shape with varying diameter. This parameter change in the brush geometry allows different radial positions to have different linear speeds, enabling synchronization with the substrate's rotational motion and eliminating slippage.
Solution Approach 2:
The symmetric cylindrical brush is replaced with an asymmetric conical brush. The conical shape creates an asymmetric distribution of linear speeds across the brush surface, which matches the asymmetric velocity profile of points on the rotating substrate, thereby improving engagement stability.
2Ease of operation
If a cylindrical brush rotates at constant speed, then the rotational control is simple, but the linear speed of brush points does not match the varying linear speed of substrate points
Solution Approach 1:
The brush geometry parameter (diameter) is changed from constant to variable along the radial direction. This allows the linear speed parameter (which depends on both rotational speed and radius) to vary across the brush surface, matching the varying linear speed of substrate points while maintaining simple constant rotational control.
3Area of stationary object
If the brush contacts the entire substrate diameter, then the cleaning coverage is complete, but slippage increases for larger substrates
Solution Approach 1:
Different parts of the brush are given different properties through the conical shape. The varying diameter creates local differences in linear speed across the brush surface, allowing each local contact point to match the speed of its corresponding substrate point, thereby maintaining engagement stability across the entire large substrate area.
Data Source
AI summary
A cleaning device for cleaning a substrate is provided. In one aspect, the cleaning device includes a brush including a first end, a second end opposed to the first end, an outer surface, and a hollow bore defined in the brush about a central axis of the brush. The brush defines a first cross-sectional area near the first end and a second cross-sectional area near the second end. Both the first and second cross-sectional areas are generally perpendicular to the central axis and the second cross-sectional area is greater than the first cross-sectional area.