Plasma Etching Silicon Nitride Using Iodine Heptafluoride
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Solution Overview
Problem
Current plasma etching methods for silicon nitride films in semiconductor manufacturing have a limited etching rate, necessitating a more efficient process to enhance the etching rate and selectivity over silicon oxide films.
Innovation Solution
A plasma etching method using iodine heptafluoride gas to create plasma for etching silicon nitride films, which can be performed simultaneously with silicon oxide films, with a controlled process pressure and bias power to achieve a higher etching rate ratio of silicon nitride to silicon oxide films, typically between 2 and 70.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional etching gas (SF6) is used for plasma etching of silicon nitride film, then the etching process can be performed, but the etching rate is limited and insufficient for high productivity requirements
Solution Approach 1:
The patent changes the chemical composition parameter of the etching gas from conventional SF6 to IF7 (iodine heptafluoride). This parameter change results in a significant increase in etching rate for silicon nitride film while maintaining controlled selectivity against silicon oxide film, thereby resolving the contradiction between productivity and material consumption efficiency
2Productivity
If higher etching rate is achieved for silicon nitride film, then productivity improves, but selectivity control over silicon oxide film becomes more difficult
Solution Approach 1:
By changing the etching gas from SF6 to IF7, the patent achieves a specific parameter change in chemical reactivity that provides both high etching rate for silicon nitride and controlled selectivity. The IF7 gas exhibits optimal chemical affinity that simultaneously satisfies high productivity and precise selectivity control requirements
Solution Approach 2:
The patent implements process parameter optimization including pressure control (1-100 Pa range) and power control to achieve feedback optimization of the etching process. This allows real-time adjustment to maintain the desired selectivity ratio between silicon nitride and silicon oxide etching rates
3Productivity
If conventional plasma etching methods are used, then the process is established and reliable, but the etching rate cannot meet the demand for faster semiconductor manufacturing
Solution Approach 1:
The patent introduces IF7 gas as a new parameter in the etching process while systematically optimizing accompanying parameters such as pressure (1-100 Pa) and power input. This controlled parameter change approach maintains process reliability through systematic optimization while achieving the desired increase in etching rate for high 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 significantly increases the etching rate and selectivity of silicon nitride films over silicon oxide films, enabling efficient removal in semiconductor processes like shallow trench isolation and potentially replacing wet etching methods.
Implementation Method 1
etching a silicon nitride film formed on a substrate using plasma obtained by converting an etching gas containing iodine heptafluoride into plasma
Data Source
AI summary
There is provided a plasma etching method having a high etching rate of a silicon nitride film. A plasma etching method includes an etching step of etching a silicon nitride film formed on a substrate (20) using plasma obtained by converting an etching gas containing iodine heptafluoride into plasma.