CH2F2 Plasma Etching of Silicon and Oxide Films
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Solution Overview
Problem
Existing etching methods for semiconductor integrated circuit manufacturing fail to achieve sufficient mask selectivity when using resist or organic films as masks for etching silicon films in multi-layered structures, and struggle to etch silicon films under thick silicon oxide layers effectively.
Innovation Solution
The use of an etching gas containing CH2F2, which allows for the integration of etching silicon films and silicon oxide films in multi-layered structures by employing a resist or organic film as a mask, enabling precise control and selectivity through plasma etching in a parallel plate type plasma etching apparatus.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If HBr gas or HF3 gas is used as etching gas, then silicon film can be etched, but mask selectivity deteriorates because resist film or organic film is also etched
Solution Approach 1:
The patent changes the chemical composition parameters of the etching gas from conventional HBr or HF3 to a mixed gas containing CF4, CHF3, and C2F6 in specific proportions. This parameter change enables differential etching where silicon is etched at high speed while resist and organic masks remain protected, thereby resolving the contradiction between etching productivity and mask selectivity.
2Reliability
If separate etching apparatuses are used for silicon oxide film and silicon film, then each film can be etched with appropriate gas, but process complexity increases and integral etching becomes difficult
Solution Approach 1:
The patent develops a universal etching gas composition that can etch both silicon oxide films and silicon films with high precision in a single etching apparatus. The mixed gas of CF4, CHF3, and C2F6 provides differentially selective etching for multiple materials, eliminating the need for separate specialized apparatuses and simplifying the overall manufacturing process while maintaining high etching quality.
3Reliability
If thick silicon oxide film is present on silicon film, then insulation is improved, but etching of underlying silicon film becomes difficult without specialized apparatus
Solution Approach 1:
The patent applies preliminary action by first etching the thick silicon oxide film with the mixed gas to create an opening path, then continuing with the same gas composition to etch the underlying silicon film. This preliminary etching of the oxide layer enables subsequent access to and etching of the silicon film without requiring a separate specialized apparatus, thereby maintaining both insulation performance and etching 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 approach provides sufficient mask selectivity and allows for the integral etching of silicon and silicon oxide films, even under thick silicon oxide layers, by maintaining a significant difference in etching rates between the mask and the silicon films, ensuring accurate and efficient processing.
Implementation Method 1
plasma etching in a parallel plate type plasma etching apparatus
Implementation Method 2
etching gas containing a CH2F2 gas
Data Source
AI summary
Provided is an etching method capable of etching even a silicon film that is included in a multi-layered structure by using a resist film or an organic film as a mask, and also capable of integrally etching the silicon film and a silicon oxide film disposed under the silicon film. The etching method which etches the multi-layered structure including the silicon oxide film and the silicon film formed on the silicon oxide film, includes: integrally etching the silicon film and the silicon oxide film included in the multi-layered structure by using a resist film or an organic film as an etching mask and using an etching gas containing a CH2F2 gas as an etching gas, when the silicon film and the silicon oxide film in the multi-layered structure are etched.