Dynamic Bias Frequency Control for High Aspect Ratio Etching
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Solution Overview
Problem
Existing etching methods face challenges in forming patterns with high aspect ratios, leading to shape abnormalities such as bowing and tapering, which affect the accuracy and quality of the etched patterns.
Innovation Solution
An etching method that involves providing a substrate with an underlying layer and an etching target film, generating plasma, and supplying RF bias power at a first frequency to form a recess, then changing the bias power frequency based on the aspect ratio of the recess to control its shape and ensure the underlying layer is exposed, allowing continuous etching until completion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a single frequency bias power is supplied to etch the etching target film, then the etching process is simple and fast, but the pattern shape abnormality (bowing and tapering) increases
Solution Approach 1:
The patent applies dynamics by changing the frequency of bias power during the etching process. The frequency is dynamically adjusted based on the aspect ratio of the recess being formed: a first frequency is used when the aspect ratio is below a threshold, and a second frequency is used when the aspect ratio exceeds the threshold. This dynamic frequency adjustment allows the etching process to adapt to changing geometric conditions, preventing shape abnormalities while maintaining etching progress.
Solution Approach 2:
The patent implements parameter changes by modifying the frequency parameter of the bias power supply during etching. When the aspect ratio of the recess reaches a predetermined threshold, the system switches from a first frequency to a second frequency. This parameter change enables control over the etching profile, preventing bowing and tapering effects that occur with constant frequency, thereby improving pattern shape accuracy without sacrificing productivity.
2Manufacturing precision
If the bias power frequency is changed during etching, then the pattern shape accuracy improves, but the etching process complexity increases
Solution Approach 1:
The patent employs feedback control by continuously monitoring the aspect ratio of the recess during etching and using this information to adjust the bias power frequency. The aspect ratio calculation based on recess depth and width serves as feedback that triggers frequency switching. This feedback mechanism ensures accurate pattern formation while keeping the control logic relatively simple: monitor aspect ratio, compare to threshold, and switch frequency accordingly.
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 improves the shape abnormality of patterns by dynamically adjusting the RF bias power frequency, preventing deviations in the opening dimension and aspect ratio, thus enhancing the accuracy and quality of etched patterns.
Implementation Method 1
generating plasma from a processing gas
Implementation Method 2
supplies a radio frequency (RF) bias power for attracting ions to a stage on which a substrate is disposed, to accelerate an etching in a depth direction
Data Source
AI summary
An etching method includes: steps a), b), c), and d). Step a) provides a substrate having an underlying layer and an etching target film formed on the underlying layer, on a stage. Step b) generates plasma from a processing gas. Step c) supplies a bias power having a first frequency to the stage to etch the etching target film, thereby forming a recess. Step d) changes a frequency of the bias power to a second frequency different from the first frequency according to an aspect ratio of the recess after step c), to further etch the etching target film. After a generation of the plasma, the etching target film is continuously etched during a time period until the underlying layer is exposed.