Process Shield Anode-Cathode Ratio Plasma Contamination
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Solution Overview
Problem
Plasma process chambers face contamination and re-sputtering issues due to the erosion of the plasma-facing surface of the process shield and the limited anode-to-cathode surface area ratio, especially when the target and substrate are closer, leading to unwanted particle generation and material re-deposition.
Innovation Solution
The introduction of a process kit with a process shield having an increased anode-to-cathode surface area ratio of 2 or greater, featuring an annular body design with grooves and a coolant ring to enhance the anode surface area and reduce contamination, along with a cover ring to prevent plasma leaks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the target and substrate are placed closer together to improve processing efficiency, then productivity increases, but contamination and re-sputtering issues worsen due to erosion of the process shield
Solution Approach 1:
The process shield is designed with a multi-segmented inner surface that extends in multiple directions (downward, radially outward, radially inward) rather than a simple planar configuration. This three-dimensional geometric expansion increases the effective anode surface area without increasing the target-to-substrate spacing, thus maintaining high productivity while reducing contamination through improved plasma confinement.
Solution Approach 2:
The inner surface of the process shield is divided into multiple segments (first through eighth segments) that extend in alternating radial and vertical directions. This segmentation creates a stepped, multi-faceted surface that significantly increases the total surface area available for plasma interaction, thereby reducing erosion-related contamination while maintaining compact chamber geometry.
2Reliability
If the anode surface area is increased to reduce contamination, then the anode-to-cathode ratio improves, but the device complexity increases due to the multi-segmented shield design
Solution Approach 1:
The process shield's inner surface is segmented into multiple facets (first through eighth segments) that can be manufactured as integrated features of a single annular body. While the geometric complexity increases to achieve the multi-segmented configuration, the segmentation is achieved through conventional manufacturing methods, balancing the improved anode-to-cathode ratio with reasonable manufacturing 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
This configuration effectively reduces contamination and re-sputtering issues by increasing the anode surface area without altering the target-to-substrate spacing, thereby improving the plasma processing efficiency and preventing unwanted material deposition.
Implementation Method 1
a coolant ring configured to flow a coolant therein coupled to the upper portion of the process shield
Implementation Method 2
RF power is provided to the plasma process chamber to create a plasma in a processing volume disposed between the target and the substrate support. Process kits generally include a process shield for protecting chamber walls from unwanted deposition and to confine the plasma.
Implementation Method 3
The target provides a source of material for sputtering onto the substrate during processing
Data Source
AI summary
Embodiments of process kits for use in plasma process chambers are provided herein. In some embodiments, a process kit for use in a process chamber includes an annular body having an upper portion and a lower portion extending downward and radially inward from the upper portion, wherein the annular body includes an inner surface having a first segment that extends downward, a second segment that extends radially outward from the first segment, a third segment that extends downward from the second segment, a fourth segment that extends radially outward from the third segment, a fifth segment that extends downward from the fourth segment, a sixth segment that extends radially inward from the fifth segment, a seventh segment that extends downward from the sixth segment, and an eighth segment that extends radially inward from the seventh segment.