Sidewall Image Transfer for Low Aspect Ratio Patterns
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Solution Overview
Problem
Conventional sidewall image transfer processes for patterning thin films on substrates with low aspect ratios (0.5 to 2.5) suffer from corner rounding and edge roughness, leading to errors in critical dimension (CD) and line edge roughness (LER), compromising pattern transfer integrity.
Innovation Solution
A method involving conformal deposition of a material layer over a patterned substrate, followed by selective deposition of a second material layer on the sidewalls, partial plasma etching to expose the top surface, and subsequent etching to retain the material layer on sidewalls, ensuring precise pattern transfer with improved CD and LER maintenance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional sidewall image transfer process is used for low aspect ratio patterns, then the patterning process can be completed, but corner rounding and edge roughness occur leading to CD and LER errors
Solution Approach 1:
The patent applies preliminary action by performing a tailored deposition process that selectively increases material thickness on sidewall regions before the main etching process. This pre-positioning of additional material on the sidewalls compensates for the corner rounding that will occur during subsequent etching, ensuring that the final pattern maintains accurate critical dimensions and reduced line edge roughness
Solution Approach 2:
The patent implements local quality by using a tailored process recipe that selectively deposits additional material only on specific regions (sidewalls) of the pattern structure. The deposition process targets areas with low material thickness and increases thickness preferentially on sidewall regions, creating non-uniform local thickness distribution that compensates for anticipated etching-induced corner rounding in those specific locations
2Measurement precision
If material layer thickness is reduced to print sub-50 nm features, then resolution is improved, but aspect ratio decreases to 0.5-2.5 causing pattern transfer integrity loss
Solution Approach 1:
The patent applies parameter changes by modifying the deposition process parameters (tailored process recipe) to selectively control material thickness distribution. The process changes the deposition rate or other parameters dynamically during deposition to increase thickness on sidewall regions while maintaining thin overall layer thickness, enabling sub-50 nm feature printing while preserving pattern transfer integrity through localized thickness adjustment
Solution Approach 2:
The patent uses preliminary action by pre-depositing additional material on sidewall regions before the etching process. This preliminary thickening of sidewall regions compensates for the low aspect ratio condition, ensuring that when etching occurs, the pattern transfer maintains integrity despite the thin material layer thickness required for sub-50 nm resolution
3Stability of the object's composition
If conformal deposition is applied over resist mandrel pattern, then coverage is improved, but corner rounding on non-mandrel side causes roughness and CD error
Solution Approach 1:
The patent implements local quality by transitioning from uniform conformal deposition to localized selective deposition. The tailored process recipe directs additional material preferentially to sidewall regions where corner rounding occurs, rather than uniformly increasing thickness everywhere. This creates local thickness variations that compensate for corner rounding in specific areas while maintaining appropriate coverage elsewhere
Solution Approach 2:
The patent converts the harmful effect of corner rounding into a benefit by using the tailored deposition process to intentionally add material to sidewall regions. The corner rounding that would normally cause CD error is compensated for by pre-positioning extra material on sidewalls, transforming the potential defect into a corrective mechanism that maintains critical dimension accuracy
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 enhances pattern transfer integrity by reducing corner rounding and edge roughness, maintaining accurate critical dimensions and line edge roughness within acceptable ranges, even for low aspect ratio patterns.
Implementation Method 1
partially removing said material layer using a plasma etching process
Implementation Method 2
conformally depositing a material layer over said pattern
Data Source
AI summary
A method for patterning a substrate is described. The patterning method may include conformally depositing a material layer over a pattern according to a conformal deposition process, selectively depositing a second material layer on an exposed surface of the material layer according to a selected deposition process recipe; partially removing the material layer using a plasma etching process to expose a top surface of the pattern, open a portion of the material layer at a bottom region between adjacent features of the pattern, and retain a remaining portion of the material layer on sidewalls of the pattern; and removing the pattern using one or more etching processes to leave a final pattern comprising the remaining portion of the material layer and the second layer.