TiAlC Selective Etching Using Near-Atmospheric Plasma Radicals
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Solution Overview
Problem
Existing etching methods for titanium aluminum carbide (TiAlC) materials face challenges in achieving high selectivity and isotropy, particularly in the context of 3D semiconductor device manufacturing, where isotropic etching with high processing-dimension controllability is required, and current plasma etching technologies using chlorine/bromine/iodine gases are corrosive and toxic.
Innovation Solution
A near atmospheric pressure plasma enhanced atomic layer etching (ALE-nAPP) method using vapor injection of liquid sources, such as Ar gas/evaporated liquid mixtures, generates high-density radicals for isotropic etching, allowing for selective removal of TiAlC films with high selectivity and controllability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If wet etching using H2O2 mixtures is applied to remove metal layers, then metal removability is improved, but lateral etching of metal films under the patterning mask increases and metal gate on masked devices is damaged
Solution Approach 1:
The patent changes the etching method from wet to dry plasma etching, and further to near atmospheric pressure plasma etching, fundamentally altering the process parameters to achieve both high metal removability and precise lateral etching control through the unique properties of near atmospheric pressure plasma
Solution Approach 2:
The patent utilizes the phase transition characteristics of plasma from low pressure to near atmospheric pressure, leveraging the enhanced radical density and different reaction kinetics at near atmospheric pressure to achieve superior etching performance with controlled anisotropy
2Productivity
If chlorine/bromine/iodine plasmas are used for plasma etching, then etching capability is improved, but system setup complexity and safety requirements increase due to corrosive and toxic properties
Solution Approach 1:
The patent employs inexpensive, non-toxic, non-corrosive gases (such as oxygen, nitrogen, or mixed gases) that can be safely handled and disposed of, replacing the expensive and hazardous chlorine/bromine/iodine plasmas while maintaining effective etching capability through near atmospheric pressure plasma chemistry
Solution Approach 2:
The patent converts the potential harm of using common, safe gases at near atmospheric pressure into a benefit by achieving enhanced radical density and improved etching performance that rivals or exceeds traditional plasma methods without the associated safety and complexity issues
3Productivity
If fluorine plasma is used for plasma etching, then etching capability is improved, but additional ligand-exchange steps are required because AlF3 is a non-volatile product
Solution Approach 1:
The patent changes the plasma chemistry from fluorine-based to near atmospheric pressure plasma using alternative gases, fundamentally altering the reaction products to be volatile and eliminate the need for additional ligand-exchange steps while maintaining effective etching capability
4Manufacturing precision
If pattern miniaturization is pursued, then device density is improved, but pattern collapse occurs due to surface tension of rinse liquid
Solution Approach 1:
The patent replaces the wet rinse process with dry plasma etching and near atmospheric pressure plasma treatment, eliminating the mechanical force of liquid surface tension that causes pattern collapse while maintaining effective material removal through plasma chemistry
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 ALE-nAPP method enables high-selectivity and isotropic etching of TiAlC films, producing volatile products and minimizing damage to underlying structures, thus enhancing the precision and reliability of 3D semiconductor device fabrication.
Implementation Method 1
near atmospheric pressure plasma enhanced atomic layer etching (ALE-nAPP) method using vapor injection of liquid sources
Implementation Method 2
vapor injection of liquid sources, such as Ar gas/evaporated liquid mixtures
Implementation Method 3
vacuum-heating the treated material to remove the surface reaction layer that is formed on a surface of the titanium aluminum carbide film
Data Source
AI summary
A method for selective removal of a titanium aluminum carbide film against titanium aluminum nitride films by using near atmospheric pressure plasma that is a rich non-halogen radical source to produce various radicals (e.g. NH, H, CHx, N, Ar, OH, O) from Ar and liquid vapor for film surface modification. The modified layer is able to form volatile products that can be easily removed by heating.