Substrate Polishing Brush Speed Control for Uniform Material Removal
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Solution Overview
Problem
Existing substrate polishing techniques often result in uneven polishing, leading to defocusing and defects such as burrs, embedment, and scratches on the back surface of semiconductor wafers, which are difficult to remove and can adversely affect subsequent processes.
Innovation Solution
A substrate processing apparatus that includes a substrate holding unit, a rotation driving unit, a polishing brush, and a controller to control the rotation speed and movement speed of the polishing brush in a radial direction, ensuring equal tangential speed and number of rotations across different radial ranges, thereby achieving uniform polishing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If constant rotation speed and constant polishing brush moving speed are used, then the polishing process is simple to control, but the polishing amount becomes uneven across different radial regions
Solution Approach 1:
The patent applies dynamics by making the rotation speed and polishing brush moving speed variable rather than constant. The rotation driving unit and polishing brush moving unit dynamically adjust their speeds based on the radial position, creating a dynamic control system that compensates for the varying polishing conditions across different regions of the substrate.
Solution Approach 2:
The patent changes the parameters of rotation speed and moving speed as functions of radial position. Specifically, the rotation speed decreases as the radius increases, and the moving speed also decreases with increasing radius. This parameter change ensures that the polishing amount per unit area becomes uniform across the entire substrate surface.
2Productivity
If high rotation speed is used to increase productivity, then polishing efficiency improves, but scratches and defects increase in specific regions
Solution Approach 1:
The patent applies local quality by making the polishing conditions location-dependent. Different regions of the substrate receive different rotation speeds and moving speeds tailored to their specific radial positions. This ensures that high productivity is achieved in regions where it is safe, while surface quality is protected in regions prone to scratches and defects.
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
This approach ensures a uniform polishing amount across the entire substrate surface, reducing the occurrence of scratches and defects, and improving the uniformity of the polishing process.
Implementation Method 1
a polishing brush configured to polish a target surface of the substrate to be polished
Data Source
AI summary
A substrate processing method includes polishing a target surface of a substrate to be polished by moving a polishing brush in a horizontal direction while pressing the polishing brush against the polishing target surface of the substrate which rotates in a horizontal posture around a vertical axis. The polishing is performed while varying a rotation speed of the substrate and a moving speed of the polishing brush such that the rotation speed of the substrate decreases stepwise or continuously and the moving speed of the polishing brush in a radial direction of the substrate decreases stepwise or continuously as a distance from a center of rotation of the substrate measured in the radial direction of the substrate to a center of the polishing brush increases.