Plasma Etching Bias Control for High-Aspect-Ratio Recesses
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Solution Overview
Problem
Existing plasma etching methods struggle to efficiently form recesses with high aspect ratios in substrates due to uncontrolled ion energy and flux, leading to suboptimal etching rates.
Innovation Solution
The method involves modifying the bias frequency or pulse duty ratio of the electrical bias supplied to the substrate support to maintain a consistent ion energy flux, using a plasma processing apparatus with a bias power supply to control ion energy and flux during etching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional plasma etching is used to form recesses with high aspect ratios, then the etching process can be performed, but the etching rate is insufficient and the process is inefficient
Solution Approach 1:
The patent applies dynamics by making the bias frequency variable over time rather than constant. The bias frequency is dynamically adjusted during the etching process to optimize ion energy and flux at different stages, thereby improving both etching rate and recess formation quality simultaneously
Solution Approach 2:
The patent changes physical parameters of the electrical bias, specifically the bias frequency and pulse duty ratio, to control ion energy and flux. By modifying these parameters during the etching process, the method achieves enhanced etching rate while maintaining precise control over recess formation
2Productivity
If ion energy and flux are not controlled, then the etching process is simple, but the etching rate is insufficient for high aspect ratio recesses
Solution Approach 1:
The patent modifies parameters of the electrical bias (bias frequency and pulse duty ratio) to control ion energy and flux. This parameter adjustment enables enhanced etching rate for high aspect ratio recesses while using the existing bias power supply capabilities
Solution Approach 2:
The patent employs periodic pulsed electrical bias with variable pulse duty ratios to control ion bombardment. This periodic action allows optimization of ion energy and flux delivery, improving etching efficiency without requiring continuous high-power bias
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 the etching rate for forming recesses with high aspect ratios by optimizing ion energy and flux, thereby improving the efficiency of the etching process.
Implementation Method 1
an electrical bias is supplied to the substrate support, to attract ions from the plasma into the substrate
Implementation Method 2
etching the substrate with plasma generated in the chamber, thereby forming a recess in the substrate
Data Source
AI summary
An etching method includes providing a substrate on a substrate support in a chamber of a plasma processing apparatus. The etching method further includes etching the substrate with plasma generated in the chamber, thereby forming a recess in the substrate. In the etching, an electrical bias is supplied to the substrate support, to attract ions from the plasma into the substrate. In the etching, at least one of a bias frequency, which is a reciprocal of a time length of a waveform cycle of the electrical bias, and a pulse duty ratio of a pulsed electrical bias is modified to maintain an ion energy flux to the substrate.