Symmetric RF Return Path Liner for Plasma Etching
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Solution Overview
Problem
Conventional plasma processing chambers face challenges in achieving uniform etching due to asymmetry in RF power delivery, leading to non-uniform etching and reduced device yields, especially as semiconductor feature sizes shrink and substrate sizes increase.
Innovation Solution
A chamber liner with a tubular shape and strategically placed dummy openings and flexible straps provides a symmetrical RF power return path, improving gas conductance and ensuring uniform RF power distribution during plasma processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional chamber liners are used, then the chamber structure is simple, but RF power delivery becomes asymmetric leading to non-uniform etching
Solution Approach 1:
The patent applies asymmetry by introducing dummy openings in the chamber liner to counterbalance the asymmetry created by functional openings (substrate access, gas inlets, etc.). This creates a symmetric RF return path that compensates for the inherent asymmetry in plasma processing chamber components, thereby improving RF power distribution uniformity and etching consistency across the substrate surface.
2Ease of operation
If functional openings are added to the chamber liner, then substrate access and gas flow are enabled, but RF power return path becomes asymmetric
Solution Approach 1:
The patent introduces dummy openings positioned strategically to counterbalance the asymmetry introduced by functional openings. These dummy openings do not serve functional purposes but create a symmetric RF return path that ensures uniform RF power distribution, thereby resolving the contradiction between operational functionality and RF power uniformity.
3Manufacturing precision
If the chamber liner is made symmetric, then RF power return path is uniform, but functional access to substrate is reduced
Solution Approach 1:
The patent combines asymmetric functional openings (for substrate access, gas flow, etc.) with symmetric dummy openings. The dummy openings are strategically placed to create a symmetric RF return path that compensates for the asymmetry of functional openings, thereby maintaining both operational functionality and RF power distribution uniformity simultaneously.
4Productivity
If substrate size is increased to facilitate production, then device production capacity increases, but etch non-uniformity becomes more severe
Solution Approach 1:
The patent addresses etch non-uniformity on large substrates by introducing dummy openings that create a symmetric RF return path. This symmetry ensures uniform RF power distribution across the entire substrate surface, enabling consistent etching performance even as substrate size increases to accommodate higher production capacity.
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 enhances azimuthal uniformity and plasma confinement, resulting in improved etching uniformity and increased device yields by ensuring even RF power distribution and optimized gas flow within the plasma processing chamber.
Implementation Method 1
Plurality of straps are connected to the bottom of the tubular shaped wall of the inner liner. The plurality of straps are electrically coupled to a ground ring defined within the chamber to provide an RF power return path during the plasma processing.
Data Source
AI summary
An apparatus and system for plasma processing a substrate using RF power includes a chamber having walls for housing an electrostatic chuck (ESC) and a top electrode. The top electrode is oriented opposite the ESC to define a processing region. An inner line with a tubular shaped wall is defined within and is spaced apart from the walls of the chamber and is oriented to surround the processing region. The tubular shaped wall extends a height between a top and a bottom. The tubular shaped wall has functional openings for substrate access and facilities access and dummy openings oriented to define symmetry for selected ones of the functional openings. A plurality of straps are connected to the bottom of the tubular shaped wall of the inner liner and are electrically coupled to a ground ring within the chamber to provide an RF power return path during plasma processing.