SiGe Etching Composition for Selective Removal in SiGe/Si Stacks
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional aqueous etching solutions for silicon-germanium alloys lack selectivity over silicon and compatibility with SiO2, leading to inefficient removal of sacrificial layers in GAA MOSFET fabrication, resulting in reduced control over the etching process and material damage.
Innovation Solution
An etching solution comprising water, an oxidizer, a fluoride ion source, a polyfunctional acid, a corrosion inhibiting surfactant, a silane silicon oxide etch inhibitor, and optionally a water-miscible organic solvent, which enhances the selectivity of silicon-germanium over silicon and silicon oxide while minimizing etch rates of SiO2.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional aqueous etching solutions (H2O2/CH3COOH) are used for SiGe etching, then selectivity over Si is improved, but compatibility with SiO2 deteriorates due to high SiO2 etch rates
Solution Approach 1:
The patent modifies the chemical composition parameters of the etching solution by introducing a silane-based SiO2 etch inhibitor and adjusting the oxidizer-to-organic-solvent ratio. This changes the etching kinetics to achieve high SiGe etch rates while suppressing SiO2 etching, resolving the contradiction between SiGe selectivity and SiO2 compatibility
Solution Approach 2:
The silane-based SiO2 etch inhibitor acts as an intermediary substance that selectively adsorbs onto SiO2 surfaces, forming a protective layer that prevents the oxidizer from attacking SiO2. This mediator allows the etching solution to maintain high SiGe etch rates while protecting SiO2 layers from damage
2Manufacturing precision
If H2O2/CH3COOH solution is used for SiGe etching, then smoothness is improved, but effectiveness on vertical stacks deteriorates
Solution Approach 1:
The patent adjusts the viscosity and surface tension parameters of the etching solution by incorporating water-miscible organic solvents in optimized proportions. This modification enables the solution to penetrate vertical stack structures effectively while maintaining smooth etching surfaces, resolving the contradiction between smoothness and vertical stack etching effectiveness
3Productivity
If conventional etching solutions are used, then SiGe etching proceeds, but control over the etching process deteriorates leading to material damage
Solution Approach 1:
The etching solution incorporates components that provide self-regulating feedback mechanisms. The silane-based SiO2 etch inhibitor dynamically adjusts its protective effect based on local SiO2 exposure, while the corrosion-inhibiting surfactant modulates the etching rate in real-time, preventing runaway etching and material damage while maintaining high productivity
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 solution achieves high selectivity of silicon-germanium over silicon and silicon oxide, allowing for precise removal of sacrificial layers with minimal damage to surrounding materials, thereby improving the control and efficiency of the etching process in GAA MOSFET fabrication.
Implementation Method 1
Conventional wet chemical etching solutions for etching SiGe alloys typically employ an oxidizer and an oxide removal agent.
Implementation Method 2
HF for silicon oxide etching
Data Source
AI summary
The disclosed and claimed subject matter pertains to an etching solution including (i) water, (ii) at least one oxidizer, (iii) at least one fluoride ion source, (iv) at least one polyfunctional acid; (v) at least one corrosion inhibiting surfactant, (vi) at least one silane silicon oxide etch inhibitor and (vii) optionally at least one water-miscible organic solvent. The solutions are useful for the selective removal of silicon-germanium over poly silicon from a microelectronic device having such material(s) thereon during its manufacture.