Angled Etching for Semiconductor Feature Smoothing
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Solution Overview
Problem
Semiconductor fabrication processes face challenges in reducing line edge roughness (LER) and line width roughness (LWR) while maintaining critical dimension (CD) uniformity, as traditional lithography techniques often result in unacceptable variations leading to performance degradation and increased processing time.
Innovation Solution
A directional etching method using non-zero tilt and optionally non-zero twist angles is employed, where an etching species is directed at the semiconductor workpiece, adjusting angles and flow rates to reduce LER and LWR with minimal impact on CD, utilizing either sputtering or chemically reactive species.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If an implant process is performed to modify the outer layer for preferential etching, then the line edge roughness and line width roughness are reduced, but the processing time increases and throughput decreases
Solution Approach 1:
The patent merges the smoothing function into the primary etching process itself by using oblique ion incidence during the etch. This combines what would traditionally be separate steps (etching and smoothing) into a single process, maintaining LER/LWR reduction benefits while eliminating the need for additional implant or etch steps, thus preserving throughput
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 method effectively reduces LER and LWR by at least 15% with minimal change to the critical dimension, potentially up to 40% reduction, while maintaining throughput by simplifying the processing steps into a single etching process.
Implementation Method 1
the etching species may sputter material from the features
Implementation Method 2
the etching species may be a chemically reactive species
Data Source
AI summary
Methods of processing a feature on a semiconductor workpiece are disclosed. The method is performed after features have been created on the workpiece. An etching species may be directed toward the workpiece at a non-zero tilt angle. In certain embodiments, the tilt angle may be 30° or more. Further, the etching species may also be directed with a non-zero twist angle. In certain embodiments, the etching species may sputter material from the features, while in other embodiments, the etching species may be a chemically reactive species. By adjusting the tilt and twist angles, as well as the flow rate of the etching species and the exposure time, the LER and LWR of a feature may be reduced with minimal impact of the CD of the feature.