Boron Carbide Sintered Body with Necked Particles for Plasma Etchers
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Solution Overview
Problem
Boron carbide sintered bodies used in etchers often form secondary phases with sintering aids, affecting their physical properties, and react with halogen ions in plasma etchers, leading to particulate impurities and reduced etch resistance.
Innovation Solution
A boron carbide sintered body with necked particles, controlled thermal conductivity, low porosity, and inertness to halogen ions, produced using sinterability enhancers like silicon carbide and boron oxide, which maintains thermal stability and prevents particle formation upon contact with fluorine or chlorine ions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If sintering aids such as Y2O3, SiC, Al2O3, TiB2, AlF3, and W2B5 are used for sintering of boron carbide powders, then sintering is facilitated, but secondary phases are formed that have a bad influence on the physical properties of boron carbide
Solution Approach 1:
The patent removes sintering aids from the sintering process entirely, using only boron carbide powder as the raw material. This extraction of the harmful element (sintering aids) eliminates secondary phase formation while maintaining sintering capability through optimized processing conditions and particle morphology control
Solution Approach 2:
The patent changes the particle morphology parameter by using necked particles instead of spherical or irregular particles. This parameter change enables effective sintering without aids while achieving high density and maintaining pure boron carbide phase structure, thus resolving the contradiction between ease of manufacture and physical properties
2Productivity
If conventional boron carbide sintered bodies are used in plasma etchers, then etching capability is provided, but particles are formed upon contact with fluorine ions or chlorine ions leading to reduced etch resistance
Solution Approach 1:
The patent changes the particle morphology parameter by using necked particles with specific aspect ratios. This morphological parameter change creates a denser microstructure that resists particle formation when exposed to plasma etching conditions, thereby improving etch resistance while maintaining etching capability
Solution Approach 2:
The patent creates a composite-like structure at the micro level through the necked particle morphology, where the interconnected neck regions form a dense network that prevents plasma penetration and particle formation, enhancing reliability without sacrificing productivity
3Strength
If high density is achieved in boron carbide sintered bodies, then mechanical strength is improved, but thermal conductivity may be reduced due to grain boundary effects
Solution Approach 1:
The patent changes the grain boundary parameter by using necked particles that create fewer and more effective grain boundaries compared to spherical particles. This parameter change allows high density achievement with minimized grain boundary resistance to heat flow, thus maintaining thermal conductivity while improving mechanical strength
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 boron carbide sintered body exhibits improved thermal stability, reduced etch rate, and enhanced corrosion resistance, making it suitable for use in plasma etchers with reduced defects and prolonged consumable life.
Implementation Method 1
the thermal conductivity of the boron carbide sintered body at 400 °C is 27 W/m·K or less and the ratio of the thermal conductivity of the boron carbide sintered body at 25 °C to that of the boron carbide sintered body at 800 °C is 1:0.2 to 1:3
Data Source
Figure 1(a)~1(b)
Figure 2(a)~2(b)
Figure 3(a)~3(b)
AI summary
A boron carbide sintered body includes necked boron carbide-containing particles. The thermal conductivity of the boron carbide sintered body at 400 °C is 27 W/m·K or less and the ratio of the thermal conductivity of the boron carbide sintered body at 25 °C to that of the boron carbide sintered body at 800 °C is 1:0.2 to 1:3.