C-Shaped Confinement Ring for Plasma Chamber Pressure Control
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Solution Overview
Problem
In plasma processing chambers, maintaining optimal chamber pressure is crucial to prevent etch stop or plasma extinguishment, yet existing systems face challenges in effectively controlling pressure and confining plasma, especially in medium density chambers like parallel plate plasma processing chambers.
Innovation Solution
A confinement ring with an extended plasma confinement zone is introduced, featuring an upper annular wall, vertical sidewall, and lower annular wall with radially extending slots to manage pressure and plasma confinement between the upper and lower electrodes, enhancing plasma stability and gas exhaust.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If chamber pressure is increased to sustain plasma, then plasma generation is improved, but etch stop occurs
Solution Approach 1:
The confinement ring is divided into multiple functional segments: an upper confinement surface for plasma containment, a lower confinement surface with slots for gas exhaust, and a C-shaped configuration that segments the chamber volume. This segmentation allows different regions to perform different functions - plasma generation and containment in the upper region, and gas removal in the lower region - enabling simultaneous maintenance of plasma and prevention of etch stop.
Solution Approach 2:
The confinement ring introduces local quality variations through its C-shaped geometry and slot distribution. The upper surface provides a smooth confinement zone for plasma stability, while the lower surface incorporates slots at specific locations to enhance gas exhaust. This local differentiation allows the system to maintain plasma in certain zones while actively removing gas in other zones, resolving the contradiction between plasma sustenance and etch rate maintenance.
2Productivity
If chamber pressure is decreased to prevent etch stop, then etch rate is maintained, but plasma extinguishment occurs
Solution Approach 1:
The confinement ring acts as an intermediary structure between the plasma generation zone and the chamber wall. It provides a controlled interface that allows plasma to be sustained close to the substrate while facilitating gas removal through its slots. This intermediary structure enables the system to operate at lower pressures without plasma extinguishment by providing a localized environment that supports plasma stability.
Solution Approach 2:
The C-shaped confinement ring introduces a new spatial dimension for plasma control. By extending vertically and incorporating both upper and lower confinement surfaces, it creates a three-dimensional plasma confinement zone that enhances plasma stability without requiring high chamber pressure. The vertical extension and slot configuration provide additional degrees of freedom for controlling plasma behavior at lower pressures.
3Reliability
If conventional confinement structures are used, then device complexity is low, but plasma confinement effectiveness is insufficient
Solution Approach 1:
The confinement ring is designed as a multi-functional component that simultaneously performs plasma confinement, gas exhaust, and structural support functions. The C-shaped structure provides both upper and lower confinement surfaces, while the integrated slots handle gas removal. This multi-functionality reduces the need for separate components, maintaining relatively simple device architecture while achieving effective plasma confinement.
Solution Approach 2:
The C-shaped confinement ring is positioned within the existing chamber structure, nesting between the substrate support and chamber wall. This nested configuration allows the confinement ring to utilize the existing chamber geometry, minimizing additional structural complexity. The ring fits into the available space without requiring major modifications to the chamber design, achieving enhanced plasma confinement with minimal increase in device complexity.
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 maintains optimal chamber pressure and confines plasma, preventing etch stop and plasma extinguishment, thereby improving the accuracy and repeatability of substrate processing in plasma processing chambers.
Implementation Method 1
inner surfaces of the confinement ring provide an extended plasma confinement zone surrounding a gap between an upper electrode and a lower electrode
Implementation Method 2
the slots being evenly spaced at radial positions offset by no more than 2°
Data Source
AI summary
Described herein is a confinement ring useful as a component of a capacitively-coupled plasma processing chamber. Inner surfaces of the confinement ring provide an extended plasma confinement zone surrounding a gap between an upper electrode and a lower electrode on which a semiconductor substrate is supported during plasma processing in the chamber.