Cryogenic Etching Process for Silicon Oxide Films
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Solution Overview
Problem
Hydrocarbon-based gases used in etching silicon-containing films can lead to mask clogging and surface roughening, degrading etching profiles, especially when used in high aspect ratio structures due to their depositing nature.
Innovation Solution
An etching process method involving a plasma processing apparatus that generates plasma using a hydrocarbon gas with at least 3 carbon atoms in a cryogenic environment, with controlled dual frequency high-frequency power supplies to maintain substrate temperature below −35°C, preventing mask clogging and enhancing mask selectivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If hydrocarbon-based gas is used to etch silicon-containing film, then mask selectivity is increased, but particles may adhere to mask opening and clog it
Solution Approach 1:
The patent changes the temperature parameter to cryogenic conditions (less than or equal to -35°C) to suppress the depositing nature of hydrocarbon-based gas, preventing particle adhesion and mask opening clogging while maintaining mask selectivity
Solution Approach 2:
The patent uses a composite gas system combining hydrocarbon-based gas (for mask selectivity) with oxygen-containing gas (to suppress deposition), achieving both high mask selectivity and prevention of mask opening clogging
2Reliability
If hydrocarbon-based gas is used to etch silicon-containing film, then mask selectivity is increased, but mask surface may roughen
Solution Approach 1:
The patent changes the temperature parameter to cryogenic conditions (less than or equal to -35°C) to suppress the depositing nature of hydrocarbon-based gas, preventing mask surface roughening while maintaining mask selectivity and etching profile quality
Solution Approach 2:
The patent uses a composite gas system combining hydrocarbon-based gas (for mask selectivity) with oxygen-containing gas (to suppress deposition), achieving both high mask selectivity and maintenance of smooth mask surface and etching profile
3Reliability
If amount of hydrocarbon-based gas is increased, then mask selectivity is improved, but particles may adhere and clog mask opening
Solution Approach 1:
The patent changes the temperature parameter to cryogenic conditions (less than or equal to -35°C) to suppress the depositing nature of hydrocarbon-based gas, allowing increased gas amount for high mask selectivity without particle adhesion and mask opening clogging
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 achieves desired mask selectivity and maintains a desirable etching profile by suppressing surface roughening and clogging, ensuring effective etching of silicon oxide and laminated silicon-containing films.
Implementation Method 1
generating a plasma by adding a hydrocarbon gas containing at least 3 carbon atoms to an etching gas containing carbon, hydrogen, and fluorine
Implementation Method 2
in an cryogenic temperature environment where a substrate temperature is controlled to be less than or equal to −35° C.
Data Source
AI summary
An etching process method is provided that includes outputting a first high frequency power of a first frequency from a first high frequency power supply, and outputting a second high frequency power of a second frequency, which is lower than the first high frequency, from a second high frequency power supply in an cryogenic temperature environment where a substrate temperature is controlled to be less than or equal to −35° C.; generating a plasma by adding a hydrocarbon gas containing at least 3 carbon atoms to an etching gas containing carbon, hydrogen, and fluorine; and etching a silicon oxide film or a laminated film made up of laminated layers of silicon-containing films having different compositions using the generated plasma.