Silicon Oxide Etching Profile Control via Hydrofluorocarbon Plasma
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Solution Overview
Problem
Existing etching methods for silicon oxide films using CH2F2 gas at low temperatures do not effectively control the deposition of reaction products on a mask film, making it difficult to manage the etching profile.
Innovation Solution
An etching method that generates plasma from a gas mixture including hydrogen and fluorine-containing gases, such as hydrofluorocarbon gases like CH2F2, with a higher sticking coefficient than CF4, allowing for controlled deposition of radicals on the mask film to adjust the etching profile.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional etching gases (CF4, CH2F2) are used for etching silicon oxide films, then etching can be performed, but the deposition position of reaction products on the mask film cannot be controlled, making it difficult to manage the etching profile
Solution Approach 1:
The patent changes the chemical composition parameters of the etching gas by introducing hydrofluorocarbon gases (CHF3, CH2F2, CH3F) with different carbon and hydrogen content ratios. This parameter change enables control over the sticking coefficient of reaction products, thereby controlling where they deposit on the mask film and achieving precise etching profile management
Solution Approach 2:
The patent uses composite gas mixtures combining fluorocarbon gases (CF4) with hydrofluorocarbon gases (CHF3, CH2F2, CH3F) in specific ratios. This composite approach allows simultaneous achievement of high etch rate and controlled reaction product deposition, resolving the contradiction between etching efficiency and profile control
2Reliability
If low temperature etching is used to maintain mask selectivity, then mask selectivity is improved, but etch rate decreases
Solution Approach 1:
The patent changes the gas composition parameters to include hydrofluorocarbon gases with specific carbon-to-hydrogen ratios. This enables maintaining low temperature conditions for high mask selectivity while the unique chemical properties of these gases sustain high etch rates through enhanced reaction efficiency
Solution Approach 2:
The composite gas mixture of CF4 and hydrofluorocarbon gases (CHF3, CH2F2, or CH3F) creates a synergistic effect where the fluorocarbon component provides high mask selectivity at low temperatures while the hydrofluorocarbon component maintains high etch rate, resolving the trade-off between reliability and productivity
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
This method enables precise control over the etching profile of the opening in the mask film, achieving higher mask selectivity and maintaining a high etch rate even at low temperatures, thereby improving the etching process efficiency.
Implementation Method 1
generating a plasma from a gas including a hydrogen-containing gas and a fluorine-containing gas using a high frequency power for plasma generation
Implementation Method 2
etching the silicon oxide film using the generated plasma
Implementation Method 3
the sticking coefficient of radicals generated from the hydrofluorocarbon gas is higher than the sticking coefficient of radicals generated from carbon tetrafluoride (CF4)
Data Source
AI summary
An etching method for etching a silicon oxide film is provided that includes generating a plasma from a gas including a hydrogen-containing gas and a fluorine-containing gas using a high frequency power for plasma generation, and etching the silicon oxide film using the generated plasma. The fluorine-containing gas includes a hydrofluorocarbon gas, and the sticking coefficient of radicals generated from the hydrofluorocarbon gas is higher than the sticking coefficient of radicals generated from carbon tetrafluoride (CF4).