Piezoelectric Focus Ring Actuator for Ion Sheath Alignment
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Solution Overview
Problem
In plasma processing apparatuses, the decreasing thickness of the focus ring leads to an inclination of the ion sheath, causing ions to be tilted when reaching the substrate edge, necessitating a method to correct the ion direction to vertical.
Innovation Solution
A substrate support assembly with piezoelectric elements between the supporting table and focus ring, allowing adjustable thickness to maintain impedance balance and correct the focus ring's vertical position, ensuring ions are vertically incident on the substrate edge.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the focus ring is moved upward to correct ion traveling direction, then the ion direction is corrected to vertical, but the impedance between the supporting table and the focus ring changes
Solution Approach 1:
The patent employs piezoelectric elements that can dynamically adjust the vertical position of the focus ring in real-time during plasma processing. These elements allow continuous thickness adjustment to maintain both ion direction accuracy and impedance stability, transforming a static structure into a dynamically controllable system that adapts to changing processing conditions
Solution Approach 2:
The patent changes the physical parameter of the piezoelectric element thickness to control the focus ring position. By adjusting the thickness of the piezoelectric elements, the system can simultaneously maintain proper ion incident angles and stable impedance characteristics, resolving the contradiction between directional accuracy and electrical stability
2Length of moving object
If the focus ring thickness decreases during processing, then the sheath position lowers, but the ion traveling direction becomes tilted
Solution Approach 1:
The patent applies piezoelectric elements in advance to the focus ring structure, enabling pre-positioning and real-time compensation before and during plasma processing. This preliminary action allows the system to counteract the tilting effect before it significantly impacts processing quality, maintaining vertical ion incidence despite focus ring thinning
Solution Approach 2:
The piezoelectric elements act as an intermediary mechanism between the focus ring and the supporting table. This intermediary component compensates for the focus ring thickness reduction by providing adjustable mechanical support, thereby maintaining the correct ion incident angle without requiring direct modification of the focus ring structure
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 effectively suppresses impedance changes between the supporting table and focus ring, ensuring ions are vertically directed onto the substrate edge, improving plasma processing accuracy.
Implementation Method 1
one or more piezoelectric elements disposed between the supporting table and the focus ring
Data Source
AI summary
A substrate support assembly includes a supporting table and one or more piezoelectric elements disposed between the supporting table and a focus ring. The supporting table has an upper surface, and the upper surface includes a first region on which a substrate is mounted and a second region on which the focus ring is disposed, the second region extending in a circumferential direction at an outer side of the first region. The one or more piezoelectric elements are disposed between the focus ring and the second region to be in direct or indirect contact with the focus ring and the second region. Changes in thicknesses of the one or more piezoelectric elements cause a change in a vertical position of the focus, and the thicknesses of the one or more piezoelectric elements are adjustable to suppress a generation of a gap between the focus ring and the second region.