Selective Etching of CVD Silicon Oxide Films Using HF and Alcohol Gas
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Solution Overview
Problem
Current methods using HF and NH3 gases struggle to etch CVD-based SiO2 films and native oxide films at a sufficient selection ratio with respect to thermally-oxidized films and SiN films in semiconductor manufacturing.
Innovation Solution
An etching method involving the use of HF gas and alcohol gas or water vapor is employed within a chamber to selectively etch CVD-based SiO2 films and native oxide films, while minimizing etching of thermally-oxidized films and SiN films, without generating plasma.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If HF gas and NH3 gas are used for etching, then the etching process can be performed chemically without plasma, but the selection ratio with respect to thermally-oxidized film and SiN film is insufficient
Solution Approach 1:
The patent changes the chemical parameters of the etching gas by replacing NH3 with alcohol (such as isopropyl alcohol). This parameter change fundamentally alters the etching chemistry to achieve high selection ratio etching of CVD-SiO2 and native oxide while minimizing etching of thermally-oxidized SiO2 and SiN films
Solution Approach 2:
The alcohol gas acts as an intermediary substance that enables selective etching. The alcohol molecules interact with the oxide surfaces to facilitate differential etching rates, serving as a chemical mediator between the HF gas and the various oxide films to achieve the desired selectivity
2Manufacturing precision
If HF gas and NH3 gas are used, then chemical etching can be achieved, but it is difficult to etch native oxide film while preserving thermally-oxidized film and SiN film
Solution Approach 1:
The patent modifies the chemical composition parameter by substituting NH3 with alcohol gas, which fundamentally changes the etching mechanism to achieve high selectivity for native oxide removal while protecting thermally-oxidized films and SiN films from unintended etching
Solution Approach 2:
The etching process achieves local quality differentiation by creating vastly different etching rates for different oxide types. The alcohol-HF gas mixture creates a chemical environment that selectively attacks native oxide while being much less effective on thermally-oxidized SiO2 and SiN films, achieving spatially selective etching based on material type
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 approach allows for high selection ratio etching of CVD-based SiO2 films and native oxide films relative to thermally-oxidized films and SiN films, enhancing the precision and efficiency of the etching process.
Implementation Method 1
supplying an HF gas and an alcohol gas or water vapor into the chamber to selectively etch the first silicon oxide film with respect to the second silicon oxide film and the silicon nitride film
Implementation Method 2
a method called chemical oxide removal (COR) in which chemical etching is performed without generating plasma within a chamber
Data Source
AI summary
An etching method includes disposing a target substrate within a chamber. The target substrate has a first silicon oxide film formed on a surface of the target substrate by a chemical vapor deposition method or an atomic layer deposition method, a second silicon oxide film that includes a thermally-oxidized film and a silicon nitride film. The second silicon oxide film and the silicon nitride are formed adjacent to the first silicon oxide film. The etching method further includes supplying an HF gas and an alcohol gas or water vapor into the chamber to selectively etch the first silicon oxide film with respect to the second silicon oxide film and the silicon nitride film.