Conductive Edge Ring RF Coupling for Uniform Plasma Etching
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Solution Overview
Problem
Maintaining uniform plasma etch profiles and reducing etch tilt angles at the peripheral regions of semiconductor substrates is challenging due to variations in process parameters and RF power applications, leading to non-uniform etching and increased waste.
Innovation Solution
The implementation of an annular dielectric ring structure with an electrically conductive coating on its backside, which extends the RF-powered area beyond the substrate edge, stabilizes the plasma sheath and reduces etch tilt angles by optimizing RF power coupling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If RF power is applied to the substrate support to maintain plasma, then plasma density is improved, but etch tilt increases at peripheral regions
Solution Approach 1:
The patent applies different electrical properties to different regions of the substrate support. The annular dielectric ring structure with conductive coating creates localized RF power coupling zones that differ from the central substrate region. This allows independent control of plasma conditions at the periphery versus the center, specifically addressing etch tilt at edge regions while maintaining overall plasma density.
Solution Approach 2:
The annular dielectric ring structure acts as an intermediary element between the substrate support and the plasma. It mediates the RF power distribution by providing a controlled interface that extends the RF-powered area beyond the substrate edge, thereby stabilizing the plasma sheath and reducing etch tilt without directly altering the substrate support itself.
2Manufacturing precision
If RF-powered area is extended beyond substrate edge to reduce etch tilt, then etch uniformity is improved, but device complexity increases
Solution Approach 1:
The annular dielectric ring structure is nested within or integrated with the existing substrate support assembly. This nested configuration allows the RF power extension functionality to be incorporated within the existing device footprint without requiring complete redesign of the substrate support system, thereby reducing the impact on device complexity.
Solution Approach 2:
The annular ring structure combines dielectric material with conductive coating to create a composite structure that provides both electrical insulation and RF power coupling capabilities. This composite approach enables the extension of RF-powered area while maintaining electrical isolation where needed, achieving improved etch uniformity without proportionally increasing device complexity.
3Adaptability or versatility
If process conditions are changed during etch to adapt to plasma variations, then plasma adaptability is improved, but etch uniformity deteriorates
Solution Approach 1:
The annular dielectric ring structure with conductive coating is pre-configured to provide stable RF power coupling and plasma sheath stabilization before the etch process begins. This preliminary structural arrangement ensures consistent plasma conditions throughout the etch process, preventing the need for mid-process condition changes that would compromise etch uniformity.
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 enhances etch uniformity and reduces micro-masking, allowing for improved control of etch processes across a wide range of RF power frequencies and reduces substrate waste.
Implementation Method 1
the RF power couples to the electrically conductive coating
Implementation Method 2
stabilizes the plasma sheath and reduces etch tilt angles by optimizing RF power coupling
Data Source
Figure 1(A)~2(B)
Figure 3(A)~4(B)
Figure 5(A)~5(B)
AI summary
According to the present invention there is provided a plasma etching apparatus for etching a semiconductor substrate. The plasma etching apparatus comprises: a plasma chamber; a plasma generation device for sustaining a plasma within the plasma chamber; a substrate support disposed within the plasma chamber for supporting the semiconductor substrate, the substrate support comprising an electrically conductive structure; a power supply for providing an RF electrical signal having an RF power to the electrically conductive structure; and an annular dielectric ring structure comprising a backside surface, the backside surface comprising an electrically conductive coating; wherein the electrically conductive structure is spaced apart from and extends under the electrically conductive coating so that when RF power is provided to the electrically conductive structure the RF power couples to the electrically conductive coating. The invention also relates to associated methods.