Dummy Gate Electrode Removal via Sequential Wet Etching
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Solution Overview
Problem
Current semiconductor manufacturing methods face challenges in reliably removing dummy gate electrodes without damaging the underlying gate insulation film or semiconductor substrate, leading to reduced transistor reliability and yield due to issues with dry etching and the formation of heterogeneous surface layers during wet etching.
Innovation Solution
A method involving sequential wet etching steps using APM and aqueous ammonia to selectively remove the dummy gate electrode, ensuring precise removal of the gate electrode while minimizing damage to the underlying structures, thereby improving etching selectivity and reducing residue formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If dry etching is used to remove the dummy gate electrode, then the etching speed is fast, but the gate insulation film is damaged
Solution Approach 1:
The patent replaces dry etching (physical/chemical vapor process) with wet etching using aqueous ammonia solution. This substitution eliminates plasma damage to the gate insulation film while maintaining effective removal of the dummy gate electrode through chemical dissolution.
Solution Approach 2:
The patent changes the etching method from dry to wet, and specifically uses aqueous ammonia solution with controlled temperature (60-80°C) and concentration parameters to achieve selective removal of the dummy gate electrode without damaging the gate insulation film.
2Reliability
If wet etching is used to remove the dummy gate electrode, then the gate insulation film is protected, but heterogeneous surface layers are formed
Solution Approach 1:
The patent optimizes wet etching parameters including temperature (60-80°C), etching time (5-30 minutes), and aqueous ammonia concentration to control the etching rate and prevent formation of heterogeneous surface layers, ensuring uniform removal of the dummy gate electrode.
Solution Approach 2:
The patent performs preliminary cleaning of the dummy gate electrode surface before etching to remove organic contaminants and oxide layers that could cause heterogeneous surface formation during the etching process.
3Device complexity
If a single etching step is used to remove the dummy gate electrode, then the process is simple, but etching residue remains
Solution Approach 1:
The patent divides the etching process into multiple sequential steps: first etching with aqueous ammonia to remove the dummy gate electrode, then performing a second etching step to remove any remaining residue. This segmentation ensures complete removal while maintaining process simplicity.
Solution Approach 2:
The patent uses continuous agitation or circulation of the aqueous ammonia solution during etching to maintain consistent etching action throughout the process, preventing localized residue formation and ensuring uniform removal of the dummy gate electrode.
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
This approach enhances the reliability and yield of semiconductor devices by effectively removing the dummy gate electrode without damaging the gate insulation film or semiconductor substrate, reducing the risk of etching residue and improving the manufacturing process efficiency.
Implementation Method 1
a step of wet etching the surface of the dummy gate electrode by APM
Implementation Method 2
a step of removing the dummy gate electrode by wet etching using aqueous ammonia
Implementation Method 3
a step of wet etching the surface of the dummy gate electrode by an acidic first chemical
Data Source
AI summary
The reliability of a semiconductor device is improved. A first gate electrode of a dummy gate electrode including silicon is formed over a semiconductor substrate. Then, by an ion implantation method, a semiconductor region for source or drain of MISFET is formed in the semiconductor substrate. Then, over the semiconductor substrate, an insulation film is formed in such a manner as to cover the first gate electrode. Then, the insulation film is polished to expose the first gate electrode. Then, the surface of the first gate electrode is wet etched by APM. then, the first gate electrode is removed by wet etching using aqueous ammonia. Thereafter, a gate electrode for MISFET is formed in a region from which the first gate electrode has been removed.