Sulfur Dioxide Etch Chemistry for Trimmed Feature Profile Control
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Solution Overview
Problem
Conventional semiconductor fabrication processes face challenges in achieving precise critical dimensions due to rough and non-uniform trimmed feature profiles, leading to errors in structure formation, especially as critical dimensions decrease.
Innovation Solution
The use of a sulfur dioxide etch chemistry combined with a halogen-based compound to form trimmed features with reduced feature width roughness, space width roughness, and irregular cross-sectional profiles, such as slanted or tapered profiles, resulting in more reliable pattern transfer to the base material with precision at small dimensions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional trimming chemistries are used to reduce feature width, then the critical dimension is reduced, but the trimmed features exhibit rough and non-uniform profiles with peaks and valleys
Solution Approach 1:
The patent changes the chemical composition parameters of the trimming etchant by incorporating sulfur dioxide (SO2) as a key component alongside oxygen and halogen-based compounds. This chemical parameter change fundamentally alters the etching mechanism to produce smoother sidewalls and more uniform trimmed feature profiles while maintaining the ability to achieve small critical dimensions.
Solution Approach 2:
The patent uses a composite etching chemistry comprising multiple components: sulfur dioxide (SO2), oxygen (O2), and halogen-based compounds (such as CF4, NF3, SF6, ClF3, HBr, BCl3). This composite chemistry combines the benefits of each component to achieve both precise dimensional control and smooth feature profiles, resolving the contradiction between size reduction and profile quality.
2Manufacturing precision
If conventional trimming chemistries are used to reduce feature width, then the critical dimension is reduced, but the trimmed features exhibit non-planarized top surfaces and slanted profiles
Solution Approach 1:
The patent modifies the etching process parameters by controlling the ratios and flow rates of SO2, O2, and halogen-based compounds. By optimizing these parameters, the process achieves vertical sidewalls and planarized top surfaces while maintaining small critical dimensions, eliminating the slanted and tapered profiles associated with conventional chemistries.
Solution Approach 2:
The sulfur dioxide-based chemistry provides different etching characteristics at different locations on the feature: it removes material laterally to reduce width while simultaneously maintaining vertical sidewalls and planar top surfaces. This localized control of etching quality resolves the profile uniformity issue.
3Ease of manufacture
If photolithography is used to define initial patterns, then patterning is achieved, but the initial feature width is not small enough to accommodate desired critical dimensions
Solution Approach 1:
The patent applies a preliminary trimming action using the SO2-based etching chemistry to the photolithographically formed initial features. This preliminary etching step precisely reduces the feature width from the photolithography-defined dimension (40-50 nm) to the desired critical dimension (20-30 nm) while maintaining profile quality.
Solution Approach 2:
The patent replaces reliance on purely mechanical/physical photolithography limitations with a chemical etching process. The SO2-based chemistry provides a mechanism to achieve dimensions smaller than what conventional photolithography can directly pattern, substituting chemical precision for optical resolution limits.
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 approach enables the formation of trimmed features with less feature width roughness, space width roughness, and height loss, achieving a desired critical dimension with improved profile alignment and reduced imperfections, enhancing the precision of pattern transfer to the base material.
Implementation Method 1
The patterning material is exposed to a plasma to widen the trenches. The plasma comprises sulfur dioxide and at least one of a fluorine-based compound, a chlorine-based compound, and a bromine-based compound.
Implementation Method 2
utilize sulfur dioxide and a halogen-based compound, which enable formation of a pattern of trimmed features
Data Source
AI summary
Methods of forming a semiconductor device structure and sulfur dioxide etch chemistries. The methods and chemistries, which may be plasma chemistries, include use of sulfur dioxide and a halogen-based compound to form a trimmed pattern of a patterning material, such as a resist material, at a critical dimension with low feature width roughness, with low space width roughness, without excessive height loss, and without substantial irregularities in the elevational profile, as compared to trimmed features formed using conventional chemistries and trimming methods.