TiAlC Plasma Etching With TiN Selectivity and Low Underlayer Damage
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing etching methods for titanium aluminum carbide (TiAlC) films in semiconductor manufacturing cause damage to untargeted materials due to low selectivity and etch rates, particularly when using halogen-containing gases, leading to lateral etching and underlayer damage.
Innovation Solution
A non-halogen plasma etching method using a mixture of N2 and H2 gases with controlled ion bombardment and heating, supplemented by small amounts of oxygen, to achieve selective and controlled etching of TiAlC over TiN films.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If halogen-containing gases are used for etching TiAlC films, then etching speed is improved, but lateral etching and damage to untargeted materials increase
Solution Approach 1:
The patent changes the chemical composition parameters of the etching gas from halogen-containing gases to a non-halogen mixture of N2, H2, and O2. This parameter change maintains etching capability while eliminating the harmful lateral etching effects associated with halogen gases, thus resolving the contradiction between etching speed and damage to untargeted materials.
Solution Approach 2:
The patent converts the typically harmful oxidative environment into a beneficial tool for selective etching. By carefully controlling the O2 concentration (1-10%), the oxidation reactions enable selective removal of TiAlC while protecting TiN underlying layers, transforming what would normally be a non-selective damaging process into a highly selective etching mechanism.
2Productivity
If wet etching using H2O2 mixtures is applied to remove TiAlC films, then etching capability is achieved, but selectivity against other materials decreases and treatment time increases
Solution Approach 1:
The patent replaces the wet chemical etching system with a plasma-based dry etching system. This substitution provides better control over the etching process through physical plasma reactions, achieving both the necessary etching capability and the required selectivity against other materials like TiN, TaN, HfO2, and Si.
Solution Approach 2:
The patent changes the etching environment from liquid wet etching to gaseous plasma etching, and further optimizes by controlling O2 concentration in the plasma. This parameter change enables selective etching of TiAlC while maintaining integrity of other materials, resolving the selectivity issue inherent in wet etching methods.
3Manufacturing precision
If oxygen concentration is increased in N2/H2 plasma to improve selectivity, then selectivity against TiN increases, but etching rate of TiAlC decreases
Solution Approach 1:
The patent applies dynamic control of oxygen concentration during the etching process. By adjusting the O2 level in real-time based on process requirements, the system can optimize between selectivity and etching rate, achieving high selectivity (over 10:1 against TiN) while maintaining practical etching speeds through controlled plasma conditions.
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 provides high selectivity and controlled etching of TiAlC films with reduced lateral etching and underlayer damage, enabling precise fabrication of advanced semiconductor structures.
Implementation Method 1
A non-halogen plasma etching method using a mixture of N2 and H2 gases with controlled ion bombardment and heating
Implementation Method 2
controlled ion bombardment and heating
Implementation Method 3
ion-induced or heating-induced removal of surface modified layers
Implementation Method 4
surface modification may be controlled by treating surface with those ions and radicals, as excited species and photons. The modified layer consists of metal compounds that contain nitrogen, carbon, and hydrogen.
Implementation Method 5
treating surface with those ions and radicals, as excited species and photons
Implementation Method 6
The etching mechanisms can be described by selective removal of volatile products containing NH and CN on metal carbides
Implementation Method 7
selective suppression via nitridation on metal nitrides
Data Source
AI summary
A continuous or cyclic etching method for etching a metal carbide over a metal nitride is disclosed. The etching method includes the following steps: supplying plasma that is generated from a gas mixture that contains N2 and H2 and does not contain halogen gases including fluorine, chlorine, bromine, and iodine to a surface of metal carbide on at least a part of the surface, to modify the surface of metal carbide, and removing the modified surface on metal carbide by ion irradiation or by heating.