SiCN Etching Solution for High Selectivity Without Si Roughening
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Solution Overview
Problem
Current etching solutions fail to provide a sufficient etching rate for SiCN while selectively etching it compared to Si, and often result in surface roughness of Si, limiting their use in semiconductor manufacturing.
Innovation Solution
An etching solution containing a fluorine-containing compound, acid, and water, with specific concentration ranges of fluoride ions and acid, is used to selectively etch SiCN, maintaining a high etching rate for SiCN and preventing surface roughness of Si.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional etching solutions are used to increase etching rate, then SiCN etching improves, but surface roughness of Si occurs
Solution Approach 1:
The etching solution exhibits local quality by selectively reacting with SiCN while leaving Si unaffected. The fluorine-containing compounds and phosphoric acid combination creates a chemically selective environment that etches SiCN at high rate while maintaining Si surface integrity, achieving both high productivity and manufacturing precision.
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 solution achieves a high etching rate for SiCN with improved selectivity over Si, while maintaining the surface integrity of Si, effectively addressing the limitations of prior art.
Implementation Method 1
A phosphoric acid aqueous solution is commonly used for etching SiN. However, unlike SiN, SiCN is hardly etched with a phosphoric acid aqueous solution. This is probably due to the difference in polarity between the Si—C bond and the Si—N bond.
Implementation Method 2
the polarization of the Si—C bond is smaller than that of the Si—N bond, and thus it is conceivable that an electrophilic addition reaction with an acid is less likely to occur and the etching of SiCN hardly proceeds.
Implementation Method 3
the present inventors have found that further addition of a fluorine compound to an acid, such as a phosphoric acid aqueous solution and/or sulfuric acid, which has been used for etching SiN in the art, can greatly improve the etching rate of SiCN with little change in the etching rate of Si
Data Source
AI summary
Provided is an etching solution for SiCN, the etching solution containing a fluorine-containing compound, an acid, and water, wherein a fluoride ion concentration is 0.3 mol/kg or more and 9 mol/kg or less, and a concentration of the acid is 55 mass % or more and 90 mass % or less.