Plasma Etching Mixed Gas Control for High Aspect Ratio Trenches
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Solution Overview
Problem
As the aspect ratio of deep holes or trenches in three-dimensional semiconductor devices increases, the etching rate decreases, leading to tapered shapes and prolonged processing times, which negatively impact plasma processing throughput.
Innovation Solution
A plasma processing method using a mixed gas of hydrogen bromide, fluoromethane, and nitrogen, or chlorine, to etch stacked films of silicon oxide and polycrystalline silicon or silicon nitride, promoting a vertical cross-sectional shape and maintaining etch rate efficiency even at high aspect ratios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional etching methods are used to etch deep holes or trenches with increasing aspect ratio, then the etching process can proceed, but the etching rate decreases and tapered shapes are formed
Solution Approach 1:
The patent applies parameter changes by carefully controlling the substrate temperature within a specific range (-50°C to 50°C) and adjusting the mixed gas composition (hydrogen bromide, hydrofluorocarbon, and nitrogen element-containing gases in specific ratios) to maintain high etching rates while achieving high aspect ratios without tapering
Solution Approach 2:
The patent uses a composite gas mixture consisting of hydrogen bromide, hydrofluorocarbon, and nitrogen element-containing gases. This composite approach creates a synergistic effect where each gas component contributes different properties: hydrogen bromide provides anisotropic etching, hydrofluorocarbon enhances etching rate, and nitrogen element-containing gases help control the etching profile, collectively achieving both high aspect ratio and high etching rate
2Manufacturing precision
If conventional etching methods are used to etch deep holes or trenches with increasing aspect ratio, then the etching process can proceed, but the processing time increases exponentially
Solution Approach 1:
By optimizing the substrate temperature parameter within -50°C to 50°C and adjusting the mixed gas composition ratios, the patent achieves a processing condition where high aspect ratios can be obtained without exponential increase in processing time, maintaining efficient throughput
3Ease of manufacture
If conventional etching methods are used, then existing processes can be maintained, but tapered shapes are formed which affect device performance
Solution Approach 1:
The patent controls substrate temperature within -50°C to 50°C and adjusts the mixed gas composition to achieve vertical sidewalls and prevent tapering, while maintaining compatibility with existing semiconductor manufacturing processes
Solution Approach 2:
The composite gas mixture of hydrogen bromide, hydrofluorocarbon, and nitrogen element-containing gases works synergistically to produce vertical cross-sectional shapes in etched structures, eliminating tapering while remaining compatible with standard manufacturing workflows
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
The method prevents a decrease in etch rate and improves processing throughput by forming a compound on the surface of the stacked film, allowing for reliable etching of deep holes or trenches with vertical cross-sectional shapes, even at high aspect ratios.
Implementation Method 1
a first stacked film formed by alternately stacking a silicon oxide film and polycrystalline silicon, or a second stacked film formed by alternately stacking a silicon oxide film and a silicon nitride film, is etched by using a plasma
Implementation Method 2
The first stacked film or the second stacked film is etched by using a mixed gas of a hydrogen bromide gas, a hydrofluorocarbon gas and a nitrogen element-containing gas
Data Source
AI summary
In order to implement a plasma etching method for improving a tapered shape, a plasma processing apparatus includes: a processing chamber in which a sample is subjected to plasma processing; a first radio frequency power source that supplies radio frequency power for generating a plasma; a sample stage on which the sample is placed; a second radio frequency power source that supplies radio frequency power to the sample stage; and a control unit that controls the first radio frequency power source and the second radio frequency power source so as to etch a stacked film formed by alternately stacking a silicon oxide film and a polycrystalline silicon, or a stacked film formed by alternately stacking a silicon oxide film and a silicon nitride film, by using a plasma generated by a mixed gas of a hydrogen bromide gas, a hydrofluorocarbon gas and a nitrogen element-containing gas.