Plasma Confinement Ring Assembly with Spacer Sleeves
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Solution Overview
Problem
Plasma processing chambers face issues with polymer deposition on internal surfaces, leading to contamination of semiconductor substrates due to the rubbing of moving parts during the vertical movement of confinement rings, which generates particles and affects process reliability.
Innovation Solution
A plasma confinement ring assembly design that includes an upper ring, a lower ring, hangers, hanger caps, optional spacer sleeves, and washers, where the spacer sleeves are dimensioned to avoid rubbing against the inner surface, and an optional middle ring with thermal breaks to maintain plasma-exposed surfaces at high temperatures, reducing polymer deposition and particle generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the lower ring is moved vertically towards the upper ring during wafer processing, then plasma confinement is improved, but particle contamination increases due to rubbing between moving parts
Solution Approach 1:
The patent removes the lower ring from direct contact with the substrate support, extracting it from the source of particle generation. The lower ring is suspended by hangers that eliminate rubbing contacts, thereby removing the mechanism that generated particles while preserving plasma confinement functionality.
Solution Approach 2:
The patent introduces hangers as intermediary elements between the lower ring and substrate support. These hangers serve as mediators that enable vertical movement and plasma confinement while eliminating direct rubbing contacts that caused particle contamination.
2Object-affected harmful factors
If spacer sleeves are added to prevent rubbing during lifting, then particle generation is reduced, but device complexity increases
Solution Approach 1:
The spacer sleeves are simple, inexpensive components that prevent rubbing and particle generation. Although they add some complexity to the assembly, their simple cylindrical design with minimal machining requirements makes them cost-effective and easy to replace if needed.
3Object-generated harmful factors
If the middle ring with thermal breaks is added, then polymer deposition is reduced, but manufacturing complexity increases
Solution Approach 1:
The middle ring is segmented with thermal breaks that divide the ring structure into sections. This segmentation creates thermal isolation zones that prevent polymer deposition by disrupting heat transfer pathways, while the segmented design remains manufacturable using standard machining processes.
Solution Approach 2:
The thermal breaks create local variations in thermal properties within the middle ring. By introducing thermal isolation zones at specific locations, the design targets polymer deposition prevention at critical surfaces without requiring complete redesign of the entire 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 design effectively reduces particulate contamination by minimizing rubbing between moving parts and maintaining plasma-exposed surfaces at high temperatures, thereby preventing polymer deposition and ensuring cleaner chamber surfaces for repeatable process results.
Implementation Method 1
The optional spacer sleeves are dimensioned to avoid rubbing against the inner surface of the hanger bore during lifting of the lower ring
Implementation Method 2
an optional middle ring with thermal breaks to maintain plasma-exposed surfaces at high temperatures, reducing polymer deposition
Implementation Method 3
power is supplied to one or both electrodes to activate the process gas and produce the plasma to process the substrate
Data Source
AI summary
A plasma confinement ring assembly with a single movable lower ring can be used for controlling wafer area pressure in a capacitively coupled plasma reaction chamber wherein a wafer is supported on a lower electrode assembly and process gas is introduced into the chamber by an upper showerhead electrode assembly. The assembly includes an upper ring, the lower ring, hangers, hanger caps, spacer sleeves and washers. The lower ring is supported by the hangers and is movable towards the upper ring when the washers come into contact with the lower electrode assembly during adjustment of the gap between the upper and lower electrodes. The hanger caps engage upper ends of the hangers and fit in upper portions of hanger bores in the upper ring. The spacer sleeves surround lower sections of the hangers and fit within lower portions of the hanger bores. The washers fit between enlarged heads of the hangers and a lower surface of the lower ring. The spacer sleeves are dimensioned to avoid rubbing against the inner surfaces of the hanger bores during lifting of the lower ring.