SiGe Etching Composition for High Selectivity Over Silicon
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Solution Overview
Problem
Current methods for selectively etching silicon-germanium (SiGe) layers from microelectronic device substrates suffer from low SiGe/Si selectivity and slow etch rates, making it difficult to remove SiGe layers without attacking silicon layers.
Innovation Solution
A composition comprising 5-15% oxidizing agent, 5-20% fluoride ion source, and 0.001-3% acetylenic hydroxy compound derivatives is used to selectively etch SiGe layers, significantly reducing the etch rate of silicon layers while maintaining a high etch rate for SiGe layers, achieving selectivity ratios above 500:1.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional etching solutions are used to remove SiGe layers, then the SiGe etch rate is maintained, but the SiGe/Si selectivity is too low causing silicon layers to be attacked
Solution Approach 1:
The patent modifies the chemical composition parameters of the etching solution by incorporating specific organic compounds (carboxylic acids, phenols, or their derivatives) alongside traditional inorganic etchants. This parameter change in solution chemistry selectively suppresses the etching of silicon layers while preserving the etching capability for silicon-germanium layers, achieving high selectivity without sacrificing etch rate
Solution Approach 2:
The organic compounds (carboxylic acids, phenols, or their derivatives) act as intermediary substances that mediate between the etchant and the silicon layers. These intermediaries selectively adsorb or react with silicon surfaces to form protective complexes, preventing direct etching of silicon while allowing SiGe etching to proceed at normal rates, thus resolving the selectivity-etch rate contradiction
2Productivity
If etching conditions are optimized for high SiGe etch rate, then productivity increases, but silicon layers are compromised due to low selectivity
Solution Approach 1:
The patent converts the harmful effect of aggressive etching (which normally damages silicon layers) into a beneficial selective process. By introducing organic compounds that selectively interact with silicon surfaces, the previously harmful high-rate etching becomes beneficial - it rapidly removes SiGe layers while the organic intermediaries protect silicon layers from damage, transforming a harmful process into a controlled selective etching method
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 composition allows for controlled and selective etching of SiGe layers without significantly compromising silicon layers, enabling efficient removal of SiGe layers with high selectivity and rate, even for thin layers, while maintaining low etch rates for silicon layers.
Implementation Method 1
5 to 15% by weight of an oxidizing agent
Implementation Method 2
5 to 20% by weight of an etchant comprising a source of fluoride ions
Data Source
AI summary
Disclosed herein is a composition for selectively etching a layer including a silicon germanium alloy (SiGe) in the presence of a layer including silicon, the composition including:(a) 5 to 15% by weight of an oxidizing agent;(b) 5 to 20% by weight of an etchant comprising a source of fluoride ions;(c) 0.001 to 3% by weight of a first selectivity enhancer of formula S1 and(d) water.