Plasma Etching Gas Composition for Recess Shape and Selectivity
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Solution Overview
Problem
Existing etching methods face challenges in forming recesses with favorable shapes due to dimensional shrinkage (loading) and inefficient etching selection ratios, particularly when etching regions with different materials.
Innovation Solution
An etching method using a processing gas with a high flow rate of tungsten-containing gas, such as tungsten hexafluoride, to etch a second region while forming a protective layer on a first region, reducing deposits and maintaining the shape of recesses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional etching methods are used with standard processing gas compositions, then etching can be performed on different material regions, but dimensional shrinkage (loading) occurs in large recesses and etching selection ratios are inefficient
Solution Approach 1:
The patent changes the chemical composition parameters of the processing gas by introducing tungsten-containing gas (WF6, WCl6, or WBr6) and setting its flow rate to the highest among all gases except inert gas. This parameter change modifies the plasma chemistry to reduce deposits and improve etching selectivity, directly resolving the contradiction between dimensional accuracy and etching efficiency
Solution Approach 2:
The tungsten-containing gas acts as an intermediary substance that mediates the etching process. It forms a protective layer on the first region (mask material) while enabling selective etching of the second region, thereby improving both dimensional control and etching selection ratio without sacrificing productivity
2Productivity
If etching is performed on large recesses with conventional methods, then material removal is achieved, but dimensional shrinkage (loading) causes unfavorable recess shapes
Solution Approach 1:
The patent converts the potentially harmful effect of plasma deposition into a beneficial protective layer on the mask region. The tungsten-containing gas creates deposits that protect the first region from etching while allowing efficient removal of the second region material, thus maintaining recess shape fidelity during high-rate etching
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 effectively suppresses dimensional shrinkage of large recesses and improves etching selection ratios, ensuring recesses with favorable shapes and vertical sidewalls are formed.
Implementation Method 1
etching the second region with a plasma generated from a processing gas containing a tungsten-containing gas
Data Source
AI summary
An etching method includes preparing a substrate including a first region containing a first material and a second region containing a second material different from the first material; and etching the second region with a plasma generated from a processing gas containing a tungsten-containing gas. In the etching, a flow rate of the tungsten-containing gas is the largest among all gases contained in the processing gas except for an inert gas.