Wet Etching Solution for Dummy Gate Electrode Removal
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Solution Overview
Problem
As semiconductor devices approach sub-10 nm process nodes, challenges arise in integrating high-density components while maintaining device integrity and efficiency, particularly in the formation and removal of gate electrodes and source/drain regions, which can lead to damage and reduced process windows due to the low selectivity of etchants.
Innovation Solution
A method involving the formation of a dummy gate electrode over semiconductor fins, followed by its removal using a wet etching solution comprising a strong alkali, a weak alkali, and an oxidizer, which helps in protecting source/drain regions by forming a protective oxide layer, allowing controlled etching of the dummy gate electrode while minimizing damage to the surrounding materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional etchants are used to remove dummy gate electrode, then etching process is simple, but selectivity is low causing damage to source/drain regions
Solution Approach 1:
The patent modifies the chemical composition parameters of the etching solution by incorporating multiple alkalis (cesium hydroxide and potassium hydroxide) with specific concentration ratios, along with organic additives like tetrahydrofuran and isopropanol. This parameter optimization achieves high selectivity between dummy gate electrode and source/drain regions, preventing damage while maintaining processability
Solution Approach 2:
The etching solution employs a composite chemical system combining inorganic bases (CsOH, KOH) with organic solvents (THF, isopropanol) and additional additives. This composite formulation synergistically enhances etching selectivity and control, resolving the contradiction between simple processing and high reliability
2Productivity
If minimum feature size is reduced to increase integration density, then more components can be integrated, but device integrity and process window are compromised
Solution Approach 1:
The patent optimizes etching solution parameters including CsOH concentration (20-40%), KOH concentration (10-30%), and additive ratios to achieve precise control at sub-10 nm nodes. This parameter tuning maintains device integrity while enabling higher integration density through reduced minimum feature sizes
Solution Approach 2:
The patent replaces conventional single-alkali etching mechanisms with a multi-alkali chemical system that provides superior selectivity and control. This chemical mechanism substitution enables reliable patterning at smaller feature sizes, supporting increased productivity without sacrificing device integrity
3Reliability
If etching selectivity is increased to protect source/drain regions, then device damage is reduced, but etching process becomes more complex
Solution Approach 1:
The patent achieves high selectivity through optimized parameter combinations: CsOH 20-40%, KOH 10-30%, THF 5-20%, and isopropanol 5-20%. Despite the multi-component formulation, the process maintains ease of manufacture through standard semiconductor fabrication techniques and readily available chemicals
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 enables efficient removal of the dummy gate electrode with controlled etching rates and reduced damage to source/drain regions, maintaining device integrity and expanding the process window, thus facilitating the integration of high-density components in semiconductor devices.
Implementation Method 1
removing the dummy gate electrode from over the semiconductor fin with a wet etching solution
Implementation Method 2
an oxidizer within the solvent... protecting source/drain regions by forming a protective oxide layer
Implementation Method 3
the etchants of the wet etching solution may diffuse through the first spacers and the dummy gate dielectric
Data Source
AI summary
An etchant is utilized to remove a semiconductor material. In some embodiments an oxidizer is added to the etchant in order to react with surrounding semiconductor material and form a protective layer. The protective layer is utilized to help prevent damage that could occur from the other components within the etchant.