Selective Ta/Ti Plasma Etching for High-Aspect-Ratio Features
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Solution Overview
Problem
Conventional etching processes face challenges in selectively removing tantalum and titanium materials from semiconductor substrates without damaging delicate structures or causing pattern deformation, especially in high aspect ratio features and small spaces, due to issues with wet etching like galvanic corrosion and limited penetration, and dry etching's potential for substrate damage from ion bombardment.
Innovation Solution
The method involves flowing a fluorine-containing precursor and a hydrogen-containing precursor into a remote plasma region, forming plasma effluents that are then directed into a substrate processing chamber to selectively etch tantalum or titanium materials relative to silicon-containing or metal materials, while maintaining controlled plasma power, temperature, and pressure conditions to minimize substrate damage and enhance etching selectivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If wet etching is used to remove tantalum or titanium materials, then etching selectivity is improved, but pattern deformation and limited penetration into constrained trenches occur
Solution Approach 1:
The patent replaces wet chemical etching with a plasma-based etching process. The plasma process uses reactive species and ion bombardment to remove materials, substituting the chemical dissolution mechanism with a physical-chemical process that provides better anisotropy and penetration into high aspect ratio features while maintaining selectivity through controlled chemistry.
Solution Approach 2:
The patent modifies the etching process parameters by using a plasma process with controlled power, pressure, and gas composition. The plasma process parameters (RF power, pressure, gas flow rates) are optimized to achieve both high selectivity for tantalum/titium removal and minimal pattern deformation, resolving the contradiction between selectivity and shape preservation.
2Length of moving object
If dry etching with local plasma is used to penetrate constrained trenches, then penetration capability is improved, but substrate damage from electric arcs occurs
Solution Approach 1:
The patent introduces a carefully controlled plasma environment as an intermediary between the etching chemistry and the substrate. The plasma provides reactive species for material removal while the controlled conditions (low pressure, optimized power) prevent direct arc discharge damage to the substrate, acting as a mediator that enables penetration without harm.
Solution Approach 2:
The patent uses controlled ion bombardment in the plasma process where ion impact is sufficient to enable penetration into constrained trenches but controlled to avoid excessive damage. The ion flux is optimized to provide just enough physical sputtering and chemical reaction activation without causing significant substrate damage or pattern deformation.
3Productivity
If plasma power is increased to improve etching rate, then productivity is improved, but substrate damage increases
Solution Approach 1:
The patent optimizes the plasma power parameter along with other parameters (pressure, gas composition, flow rates) to achieve an optimal operating point. The plasma power is set to provide sufficient etching rate while maintaining conditions that prevent excessive ion bombardment damage, balancing productivity and substrate integrity through multi-parameter optimization.
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 allows for a dry etching process that protects substrate features, achieves selective removal of tantalum and titanium materials, and improves etching efficiency in high aspect ratio and small dimension features, overcoming limitations of conventional wet and dry etching techniques.
Implementation Method 1
forming a plasma of the fluorine-containing precursor and the hydrogen-containing precursor to produce plasma effluents
Implementation Method 2
contacting the substrate with the plasma effluents. The methods may include removing the tantalum or titanium material selectively to the silicon-containing material or the metal
Data Source
AI summary
Exemplary etching methods may include flowing a fluorine-containing precursor and a hydrogen-containing precursor into a remote plasma region of a semiconductor processing chamber. The hydrogen-containing precursor may be flowed at a flow rate of at least 2:1 relative to the flow rate of the fluorine-containing precursor. The methods may include forming a plasma of the fluorine-containing precursor and the hydrogen-containing precursor to produce plasma effluents. The methods may include flowing the plasma effluents into a substrate processing region housing a substrate. The substrate may include an exposed region of a tantalum or titanium material and an exposed region of a silicon-containing material or a metal. The methods may include contacting the substrate with the plasma effluents. The methods may include removing the tantalum or titanium material selectively to the silicon-containing material or the metal.