Alkaline Etching Composition for Selective Silicon Removal

The patent changes the chemical composition parameters of the etching solution by incorporating specific compounds (thiol compounds, sultone compounds, or sulfonic acid compounds) along with organic solvents and water. This compositional parameter change enables the etching solution to selectively remove silicon while preserving silicon-germanium, resolving the contradiction between etching capability and selective removal precision.

The patent creates a composite etching solution system combining multiple components: specific sulfur-containing compounds (thiol, sultone, or sulfonic acid compounds), organic solvents (such as alcohols, ketones, or esters), and water. This composite material approach enhances the selective etching performance by leveraging the synergistic effects of different components, achieving both etching effectiveness and material differentiation.

The patent modifies the chemical parameters of the etching solution by specifying particular compounds with sulfur functional groups (thiol, sultone, or sulfonic acid groups) combined with organic solvents. This parameter optimization maintains high etching efficiency while achieving superior selectivity for removing silicon over silicon-germanium.

The patent replaces conventional etching chemistry with a specialized chemical system based on sulfur-containing compounds. This substitution creates new chemical interaction mechanisms that provide both high etching rates and excellent selectivity, overcoming the limitations of traditional etching solutions.