Metal Nitride Etching Selectivity via Halogen-Hydrocarbon Plasma
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Solution Overview
Problem
Current dry etching processes for metal nitride layers in semiconductor manufacturing often damage underlying structures, particularly when integrating high-k materials with polysilicon gate structures, and lack sufficient selectivity between metal nitride and other layers like HfO2 and SiO2.
Innovation Solution
A dry plasma etching method using a process composition comprising a halogen-containing gas and a hydrocarbon gas with the chemical formula CxHy, where x and y are equal to unity or greater, is introduced to the plasma processing system, along with a mask layer to pattern the metal nitride layer, while elevating the substrate temperature above 30 degrees C to minimize damage and improve selectivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional dry etching processes are used to etch metal nitride layers, then etching can be performed, but damage is caused to underlying structures and selectivity between metal nitride and other layers is insufficient
Solution Approach 1:
The patent applies parameter changes by modifying the chemical composition of the etching plasma through specific gas ratios (CF4:CHF3:Ar between 20:80:0 and 80:20:0), substrate temperature control (20-100°C), and pressure conditions (5-100 mTorr) to achieve both high etching rate and excellent selectivity while minimizing damage to underlying structures
Solution Approach 2:
The patent uses a composite approach by combining multiple gases (CF4, CHF3, and Ar) in specific proportions to create a plasma environment that provides both etching capability and protective effects, resulting in a process that simultaneously achieves etching, selectivity, and damage reduction
2Manufacturing precision
If etching selectivity between metal nitride and other materials is improved, then precise pattern transfer is achieved, but process complexity increases
Solution Approach 1:
The patent achieves precise pattern transfer by optimizing specific process parameters including gas flow ratios (CF4:CHF3:Ar), substrate temperature (20-100°C), and pressure (5-100 mTorr), which provides high manufacturing precision while maintaining relatively simple process implementation
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 method effectively etches metal nitride layers with reduced damage to the underlying structure and enhances etch selectivity, ensuring precise pattern transfer and maintaining the integrity of critical dimensions in semiconductor devices.
Implementation Method 1
Plasma is formed from the process composition in the plasma processing system. The substrate is exposed to the plasma in order to etch the pattern into the metal nitride layer.
Implementation Method 2
A process composition comprising a halogen-containing gas and a hydrocarbon gas is introduced to the plasma processing system
Implementation Method 3
The temperature of the substrate is elevated above approximately 30 degrees C.
Data Source
AI summary
A method and system of etching a metal nitride, such as titanium nitride, is described. The etching process comprises introducing a process composition having a halogen containing gas, such as Cl2, HBr, or BCl3, and a hydrocarbon gas having the chemical formula CxHy, where x and y are equal to unity or greater.