Selective Titanium Nitride Etching Using Remote Plasma
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Solution Overview
Problem
There is a lack of effective dry etch processes for selectively removing titanium nitride relative to other materials in semiconductor substrates, which is essential for intricate patterned material layers in integrated circuits.
Innovation Solution
A remote plasma etch process using a chlorine-containing precursor is employed, where plasma effluents react with titanium nitride, selectively removing it while minimizing the etching of other materials, with an ion suppressor controlling ionic species to enhance selectivity and reduce plasma damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional dry etch processes are used, then etching speed is maintained, but selectivity towards titanium nitride is insufficient
Solution Approach 1:
The patent changes the chemical parameters of the etch process by using a chlorine-containing precursor in a remote plasma configuration, which fundamentally alters the etch chemistry to achieve high selectivity for titanium nitride removal while maintaining acceptable etch rates
Solution Approach 2:
The patent introduces a remote plasma region as an intermediary between the gas source and substrate, where plasma effluents are generated and then transported to the substrate processing region. This intermediary plasma zone enables selective chemical reactions without direct plasma contact, achieving both selectivity and controlled etching
2Productivity
If plasma is applied to remove material, then etching efficiency is improved, but plasma damage and sputtering increase
Solution Approach 1:
The patent segments the plasma generation and substrate processing into separate regions. The plasma is generated remotely in a dedicated plasma region, and only the beneficial plasma effluents (ions, radicals, excited species) are transported to the substrate processing region through a showerhead, separating the harmful direct plasma contact from the useful chemical etching action
Solution Approach 2:
The showerhead acts as an intermediary device that transports plasma effluents from the plasma generation region to the substrate processing region. This intermediary structure allows the beneficial reactive species to reach the substrate for selective etching while preventing direct plasma contact that would cause excessive sputtering and damage
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 process achieves high selectivity of titanium nitride etching over other materials, with etch selectivity ratios exceeding 100:1, and reduces plasma damage by using neutral and radical species, allowing for precise removal without significant sputtering or surface distortion.
Implementation Method 1
A remote plasma etch formed from a chlorine-containing precursor. Plasma effluents from the remote plasma are flowed into a substrate processing region where the plasma effluents react with the titanium nitride.
Implementation Method 2
The plasma effluents react with exposed surfaces and selectively remove titanium nitride while very slowly removing the other exposed materials.
Implementation Method 3
The substrate processing region may also contain a plasma to facilitate breaking through any titanium oxide layer present on the titanium nitride. The plasma in the substrate processing region may be gently biased relative to the substrate to enhance removal rate of the titanium oxide layer.
Data Source
AI summary
Methods are described herein for selectively etching titanium nitride relative to dielectric films, which may include, for example, alternative metals and metal oxides lacking in titanium and/or silicon-containing films (e.g. silicon oxide, silicon carbon nitride and low-K dielectric films). The methods include a remote plasma etch formed from a chlorine-containing precursor. Plasma effluents from the remote plasma are flowed into a substrate processing region where the plasma effluents react with the titanium nitride. The plasma effluents react with exposed surfaces and selectively remove titanium nitride while very slowly removing the other exposed materials. The substrate processing region may also contain a plasma to facilitate breaking through any titanium oxide layer present on the titanium nitride. The plasma in the substrate processing region may be gently biased relative to the substrate to enhance removal rate of the titanium oxide layer.