Organochloride Silicon Etching for High-Aspect Recessed Features
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Solution Overview
Problem
The semiconductor industry faces challenges in etching recessed features in silicon-containing materials with high aspect ratios, experiencing issues such as twisting, non-circularity, aspect-ratio dependent etch rate, bowing, insufficient mask selectivity, and low etch rate, which are often balanced with tradeoffs that worsen other problems.
Innovation Solution
A method involving an etch gas comprising an organochloride source, a carbon source, and a hydrogen source, maintained at low temperatures, is used to etch recessed features in silicon-containing layers, which reduces twisting, non-circularity, and bowing while maintaining a high etch rate and selectivity to the mask.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional etching methods are used for high aspect ratio features, then etching can proceed, but twisting, non-circularity, and bowing occur
Solution Approach 1:
The patent changes the chemical parameters of the etching process by introducing an organochloride source (such as C2Cl6 or C2Cl4) into the etch gas composition. This chemical parameter change modifies the etching chemistry to reduce sidewall interactions that cause twisting and bowing, while maintaining anisotropic etching for vertical feature formation. The specific parameter change is the addition of organochloride compounds to the etch gas mixture.
2Productivity
If etching rate is increased for productivity, then manufacturing efficiency improves, but aspect-ratio dependent etch rate variations worsen
Solution Approach 1:
The patent modifies the etching chemistry by adding an organochloride source to the etch gas composition, which changes the reaction kinetics and transport properties. This chemical parameter change enables maintaining high etch rates while reducing aspect-ratio dependent variations through improved plasma chemistry and reduced sidewall passivation effects.
3Reliability
If mask selectivity is increased to protect mask layers, then mask integrity is maintained, but etch rate to the silicon containing layer decreases
Solution Approach 1:
The patent changes the chemical composition of the etch gas by incorporating an organochloride source, which modifies the etching selectivity characteristics. This chemical parameter adjustment enhances mask protection through altered plasma chemistry while maintaining effective etching of the silicon containing layer, resolving the tradeoff between mask selectivity and etch rate.
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 etches recessed features with minimal twisting and non-circularity, acceptable aspect-ratio dependent etch rate, and sufficient etch rate, achieving high selectivity and reduced bowing, suitable for high aspect ratio features in semiconductor devices like vertical NAND devices.
Implementation Method 1
The etch gas is formed into a plasma. The stack is exposed to the plasma to etch recessed features into the stack.
Data Source
AI summary
A method of etching recessed features in a stack with a silicon containing layer over a wafer on a substrate support is provided. The substrate support is maintained at a temperature below about 30° C. An etch ga, comprising an organochloride source selected from the group consisting of carbon tetrachloride (CCl4), CxHyClz (where x>0 and z>0), and combinations thereof, a carbon source, a fluorine source, and a hydrogen source is flowed. The etch gas is formed into a plasma. The stack is exposed to the plasma to etch recessed features into the stack.