Boron Carbide Sintered Focus Ring for Uniform Plasma Etching
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Solution Overview
Problem
Plasma processing apparatuses face challenges with non-uniform plasma distribution and reduced etching resistance due to increased plasma power, leading to degraded microelectronic component quality and frequent replacement of focus rings.
Innovation Solution
A sintered body composed of boron carbide with specific grain size and composition, including a volume ratio of grains between 30 μm and 60 μm at 50-70% and thermal conductivity of 23-42 W/mK, is developed to enhance plasma etching resistance and uniformity, manufactured through a process involving thermal treatment and sintering of a raw material composition including boron carbide and a carbon-based material.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If plasma power is increased to improve processing efficiency, then etching speed increases, but plasma distribution uniformity deteriorates and focus ring etching resistance decreases
Solution Approach 1:
The patent changes the material parameters of the focus ring by controlling the grain size distribution of boron carbide (50-70% of grains between 30-60 μm) and adjusting carbon content (30-43 wt%), which improves etching resistance while maintaining plasma distribution uniformity even at high power
Solution Approach 2:
The patent uses composite boron carbide material with specific grain size distribution and carbon content to create a focus ring that combines high etching resistance with good thermal conductivity (23-42 W/mK), resolving the contradiction between productivity and manufacturing precision
2Productivity
If plasma power is increased to improve processing efficiency, then etching speed increases, but focus ring durability decreases due to increased etching rate
Solution Approach 1:
The patent achieves an etching rate of 1.8% or less by optimizing boron carbide grain size distribution (50-70% in 30-60 μm range) and carbon content (30-43 wt%), significantly improving focus ring durability while maintaining high productivity
Solution Approach 2:
The controlled grain size distribution creates a microstructure that provides both mechanical strength and resistance to plasma etching, extending focus ring service life under high power conditions
3Reliability
If focus ring material is changed to improve etching resistance, then plasma etching resistance increases, but thermal conductivity may deteriorate affecting plasma uniformity
Solution Approach 1:
The patent optimizes the balance between etching resistance and thermal conductivity by controlling boron carbide grain size (50-70% between 30-60 μm) and carbon content (30-43 wt%), achieving both high etching resistance and adequate thermal conductivity (23-42 W/mK) for plasma 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
The sintered body achieves improved plasma etching resistance, reduced etching rate, and enhanced durability, inhibiting particle generation and maintaining plasma uniformity, thereby extending the replacement frequency of parts in plasma processing apparatuses.
Implementation Method 1
The sintered body may have a thermal conductivity at 25° C. of 23 W/mK or more and 42 W/mK or less
Implementation Method 2
Electrons accelerated by an electric field between the upper and lower electrodes, electrons emitted from the electrodes, or heated electrons ionically collide with molecules of a processing gas, which results in production of plasma from the processing gas
Data Source
AI summary
The sintered body including boron carbide, wherein the sintered body includes a zone, in which a volume ratio of grains having a grain size of greater than 30 μm and 60 μm or less is in a range of 50% to 70% based on a total volume of grains, as observed on a surface of the sintered body, is disclosed.