Wet Etching Chemistry for Selective Silicon Oxide Removal
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing wet etching methods struggle to achieve high selectivity in etching silicon oxide films with different moisture contents and suppress etching of metal films, particularly in semiconductor manufacturing processes.
Innovation Solution
A substrate processing method using an etching liquid composed of sulfuric acid, hydrogen peroxide, and hydrofluoric acid in an anhydrous organic solvent, which suppresses moisture content, enhances etching selectivity of silicon oxide films and reduces etching of metal films.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If HF concentration is increased to about 5% to increase etching selectivity of the SiO2 film with respect to the SiN film, then etching selectivity is improved, but non-selective etching occurs affecting the metal film
Solution Approach 1:
The patent changes the chemical composition parameters of the etching liquid by using a mixed solvent system (first organic solvent and second organic solvent) instead of conventional single solvents or aqueous solutions. This parameter change enables simultaneous achievement of high etching selectivity for SiO2 films and suppression of harmful etching on metal films, resolving the technical contradiction between improving selectivity and avoiding non-selective etching.
2Manufacturing precision
If conventional etching liquids are used to etch the first silicon oxide film, then etching process is simple, but selectivity between the first silicon oxide film and metal film is insufficient
Solution Approach 1:
The patent employs a composite etching liquid system comprising multiple organic solvents (first and second organic solvents) with specific physical property differences. This composite approach enables high selectivity between the first silicon oxide film and metal film while maintaining a relatively simple two-solvent formulation, thus resolving the contradiction between improving manufacturing precision and avoiding excessive device complexity.
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 high etching selectivity of BPSG film with respect to TEOS film and low etching rate of tungsten film, meeting the required conditions of etching rate ratios and minimizing polymer residue.
Implementation Method 1
performing an etching while increasing etching selectivity of the first silicon oxide film with respect to the second silicon oxide film and the metal film by supplying an etching liquid
Implementation Method 2
The substrate processing method includes performing an etching while increasing etching selectivity of the first silicon oxide film with respect to the second silicon oxide film and the metal film by supplying an etching liquid, which is prepared by diluting sulfuric acid, hydrogen peroxide and hydrofluoric acid in an anhydrous organic solvent
Data Source
AI summary
A technique enabling wet etching of a first silicon oxide film with high selectivity with respect to a metal film and a second silicon oxide film is provided. A substrate processing method of wet-etching a substrate having a stacked structure including a metal film, a first silicon oxide film, and a second silicon oxide film having a moisture content lower than that of the first silicon oxide film is provided. The substrate processing method includes performing an etching while increasing etching selectivity of the first silicon oxide film with respect to the second silicon oxide film and the metal film by supplying an etching liquid, which is prepared by diluting sulfuric acid, hydrogen peroxide and hydrofluoric acid in an anhydrous organic solvent, to the substrate such that the metal film, the first silicon oxide film, and the second silicon oxide film are simultaneously exposed to the etching liquid.