Focus Ring Carbide Coating for Stable Plasma Edge Uniformity
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Solution Overview
Problem
The degradation and consumption of focus rings in plasma processing systems lead to non-uniform plasma distribution at the edges of substrates, resulting in reduced die yield and the need for time-consuming equipment downtime for replacement.
Innovation Solution
In-situ coating of focus rings with a metal carbide layer formed during plasma etching processes, using refractory metals like tungsten, to enhance wear resistance and durability, maintaining plasma uniformity without frequent chamber openings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a focus ring is used to improve plasma distribution uniformity, then plasma uniformity is improved, but the focus ring degrades and is consumed over operation cycles
Solution Approach 1:
The focus ring is constructed as a composite structure with a bulk material (e.g., silicon) and a surface layer comprising a refractory metal (e.g., tungsten, molybdenum). This composite configuration allows the refractory metal surface layer to resist plasma etching and degradation, while the bulk material maintains the structural integrity and plasma distribution uniformity function.
Solution Approach 2:
The invention changes the material parameters of the focus ring surface by introducing a refractory metal surface layer with high melting point and plasma resistance. This parameter change (material composition) enables the focus ring to withstand plasma exposure without significant degradation, extending its operational lifetime while maintaining plasma uniformity.
2Manufacturing precision
If the focus ring is replaced frequently to maintain plasma uniformity, then plasma uniformity is maintained, but equipment downtime increases
Solution Approach 1:
The refractory metal surface layer is applied in advance to the focus ring before it enters service. This preliminary protective action ensures that the focus ring is pre-equipped with plasma resistance, eliminating the need for frequent replacements and reducing equipment downtime while maintaining plasma uniformity throughout extended operation cycles.
3Reliability
If the focus ring material is made more resistant to plasma etching, then durability is improved, but the initial cost and complexity of the component increases
Solution Approach 1:
The focus ring is segmented into two functional parts: a bulk material that provides structural support and plasma distribution uniformity, and a surface layer that provides plasma resistance. This segmentation allows each part to be optimized independently, with the surface layer being the only portion requiring advanced refractory metal materials, thereby limiting the increase in complexity to just the surface treatment.
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
Extends the lifetime of focus rings, reduces equipment downtime, and improves die yield by maintaining plasma uniformity and etch consistency, with potential extensions in mean time between wet cleanings.
Implementation Method 1
coating a carbide layer over the surface layer of the focus ring, the coating including exposing the focus ring to a plasma generated from the process gas in the plasma etch chamber
Implementation Method 2
etching the substrate, the etching including exposing the substrate to the plasma
Data Source
AI summary
A method of etching a substrate includes loading the substrate into a plasma etch chamber, the plasma etch chamber including a focus ring surrounding the substrate, the focus ring including a bulk material and a surface layer, the surface layer including a refractory metal; flowing a process gas including fluorine and carbon into the plasma etch chamber; coating a carbide layer over the surface layer of the focus ring, the coating including exposing the focus ring to a plasma generated from the process gas in the plasma etch chamber, the carbide layer including a carbide of the refractory metal; and etching the substrate, the etching including exposing the substrate to the plasma.