Silicon Layer Etching with Amine Gas for Smooth Rectangular Recesses
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Solution Overview
Problem
Existing etching methods for silicon layers result in low rectangularity and increased roughness of the recesses due to differential etching rates and by-product formation, particularly at the interface between silicon and silicon germanium layers.
Innovation Solution
Utilizing a combination of fluorine gas and trimethylamine gas as etching gases to uniformly etch silicon layers, suppressing the influence of germanium diffusion and controlling by-product formation, thereby enhancing recess rectangularity and smoothness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional etching methods are used to etch silicon layers, then etching can be performed, but the rectangularity of recesses is low and roughness increases due to differential etching rates and by-product formation
Solution Approach 1:
The patent changes the chemical parameters of the etching process by using a mixed gas atmosphere comprising fluorine-containing gas and amine gas in specific proportions (amine gas 5-50 sccm, fluorine-containing gas 50-500 sccm). This parameter change modifies the etching chemistry to suppress by-product formation and achieve uniform etching rates, thereby improving rectangularity and reducing roughness without sacrificing etching speed
Solution Approach 2:
The patent employs a composite gas system combining fluorine-containing gas (which provides high etching speed) and amine gas (which suppresses by-product formation and improves uniformity). This composite approach leverages the complementary strengths of both gases: the fluorine component enables rapid silicon removal while the amine component prevents differential etching and by-product accumulation, achieving both high speed and high precision
2Productivity
If high etching rates are achieved, then productivity increases, but uniformity of etching across the silicon layer surface decreases
Solution Approach 1:
The patent optimizes the flow rate parameters of the mixed gas system to achieve a balance between etching speed and uniformity. By controlling the amine gas flow at 5-50 sccm and fluorine-containing gas at 50-500 sccm, the process maintains high etching rates while the amine component ensures uniform distribution of etching action across the silicon layer surface, preventing localized roughness and maintaining rectangularity
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 achieves higher etching rates with improved rectangularity and reduced roughness of silicon layers, ensuring uniform etching across the silicon layer surface.
Implementation Method 1
etching a silicon layer by supplying a halogen-containing gas and an amine gas
Implementation Method 2
suppressing the influence of germanium diffusion and controlling by-product formation
Data Source
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AI summary
An etching method includes etching a silicon layer by supplying a halogen-containing gas and an amine gas to a substrate including the silicon layer formed on a surface of the substrate.