Sulfur Fluorocarbon Etching Gas for Selective SiO2 Over Low-k
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Solution Overview
Problem
Existing dry etching technologies face challenges in selectively etching silicon oxide films over low dielectric constant materials like SiON, SiCN, and SiOC, often causing damage to these films due to ion penetration and UV light exposure during the process.
Innovation Solution
A dry etching gas composition comprising a sulfur-containing fluorocarbon compound, such as 2,2,3,3,4,4,5,5-octafluorotetrahydrothiophene, is used in combination with oxygen-containing and inert gases to create a plasma that selectively etches silicon oxide films while minimizing damage to low dielectric constant materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If existing FC gases or HFC gases are used for dry etching, then the etching process can be performed, but selective etching of silicon oxide film over low dielectric constant materials cannot be achieved
Solution Approach 1:
The patent changes the chemical composition parameters of the etching gas by introducing sulfur-containing fluorocarbon compounds (specifically C4F8S and C3F6S) with controlled concentrations (1-100 vol%, preferably 10-50 vol%). This chemical parameter change enables selective etching of SiO2 over low-k materials by modifying the plasma chemistry to be more selective to silicon oxide while minimizing damage to carbon-containing silicon-based films.
2Productivity
If conventional dry etching is performed on low dielectric constant materials, then etching can proceed, but damage to the low-k film occurs due to ion penetration and UV light
Solution Approach 1:
The patent converts the potentially harmful effects of plasma exposure into beneficial selectivity by using sulfur-containing fluorocarbon compounds. The sulfur species in the plasma react preferentially with silicon oxide to form volatile sulfur compounds, while the fluorocarbon components provide protective polymerization on the low-k material surfaces. This transforms the plasma's inherent damaging capability into a selective etching mechanism that protects low-k materials while effectively removing silicon oxide.
Solution Approach 2:
The etching gas uses composite chemistry combining sulfur-containing fluorocarbon compounds with oxygen-containing compounds (O2, O3, CO, CO2, NO, NO2, SO2, or SO3). This composite gas composition creates a plasma environment where multiple chemical reactions occur simultaneously: sulfur species provide selectivity for SiO2 etching, fluorocarbon species provide protective films on low-k materials, and oxygen species enhance the etching chemistry. The synergistic interaction of these components resolves the contradiction between etching efficiency and material protection.
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 sulfur-containing etching gas composition achieves high selectivity and accuracy in etching silicon oxide films over low-k materials, reducing damage and enhancing etching rates, thereby improving the processing of complex semiconductor structures.
Implementation Method 1
etching is performed by generating a plasma of the etching gas composition according to any of (1) to (5) to form S-containing ions or active species
Data Source
AI summary
Provided is a novel etching gas composition that comprises a sulfur-containing compound and that can selectively etch SiO2 over low dielectric constant materials (low-k materials; SiON, SiCN, SiOCN, SiOC). A dry etching gas composition comprises a saturated and cyclic sulfur-containing fluorocarbon compound that is represented by general formula (1) of CxFySz where x, y, and z are 2≤x≤5, y≤2x, and 1≤z≤2.