Plasma Etching Selectivity Using Hydrofluoroether Gas
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Solution Overview
Problem
Existing plasma etching methods face challenges in achieving high etching selectivity and rate for silicon oxide relative to silicon nitride and organic materials without using oxygen and hydrogen, as these gases pose safety concerns and are difficult to control for optimal etching conditions.
Innovation Solution
A plasma etching method utilizing a hydrofluoroether, specifically represented by the formula CmF2m+1-O-CH2-R, where R is a hydrogen atom or fluoroalkyl group, in combination with a rare gas, to selectively etch silicon oxide, silicon nitride, and organic materials, achieving high selectivity and rate without requiring oxygen and hydrogen.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If oxygen and hydrogen gases are used to control CFx amount and etching selectivity, then etching selectivity can be improved, but safety concerns and difficulty in controlling etching conditions worsen
Solution Approach 1:
The patent changes the chemical composition parameters of the process gas by using hydrofluoroether compounds (CmF2m+1-O-CH2-R where m=1-3) instead of traditional oxygen-hydrogen gas mixtures. This parameter change allows control of CFx amount and etching selectivity through the molecular structure of the hydrofluoroether itself, eliminating safety concerns associated with hydrogen gas while maintaining precise control over etching conditions
Solution Approach 2:
The patent replaces hazardous oxygen and hydrogen gases with hydrofluoroether compounds that serve as both the etching agent and the source of controlled CFx radicals. This substitution eliminates the need for separate oxygen and hydrogen gas supplies, simplifying the system and removing safety hazards while maintaining etching control
2Device complexity
If fluorocarbon or hydrofluorocarbon is used alone as process gas, then simplicity is improved, but polymerized film formation prevents etching progression
Solution Approach 1:
The patent changes the chemical parameters by using specifically structured hydrofluoroether compounds (CmF2m+1-O-CH2-R) that have controlled fluorine content and molecular weight. These parameter changes allow the gas to produce appropriate CFx radical concentrations that etch silicon oxide effectively without forming excessive polymerized films that would block etching progression
Solution Approach 2:
The patent uses hydrofluoroether compounds that combine carbon, fluorine, hydrogen, and oxygen in specific ratios and structures. This composite molecular structure provides both the fluorine needed for silicon oxide etching and the right level of polymerization control, achieving etching progression without the problems of pure fluorocarbon or hydrofluorocarbon systems
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 method enables high etching selectivity and rate for silicon oxide relative to silicon nitride and organic materials, enhancing productivity by avoiding the use of hazardous gases and improving control over etching conditions.
Implementation Method 1
A plasma etching method implemented under plasma conditions using a process gas
Data Source
AI summary
The present invention is a plasma etching method that is implemented under plasma conditions using a process gas, wherein at least one gas selected from a hydrofluoroether represented by a formula (I) is used as the process gas, wherein R represents a hydrogen atom or a fluoroalkyl group represented by CnF2n+1, and m and n represent integers that satisfy 1≤m≤3 and 3≤(m+n)≤4. This plasma etching method enables The etching rate of a silicon oxide film decreases, and the productivity achieved by the etching process deteriorates when a plurality of non-processing targets (e.g., silicon nitride, silicon, and organic film) are formed on the substrate, and conditions whereby a high selectivity ratio is achieved with respect to each material, are selected. This plasma etching method can implement high etching selectivity with respect to silicon nitride, silicon, and an organic material while achieving a sufficiently high etching rate without using oxygen and hydrogen when etching silicon oxide. CmF2m+1-O-CH2-R (I)