Amorphous Tungsten Silicide Hard Mask for Plasma Etching
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional hard masks made of tungsten silicide are prone to quick etching during plasma etching due to crystal grain boundaries, and increasing their thickness leads to film stress and warping, necessitating a more resistant material.
Innovation Solution
An amorphous hard mask composed of tungsten and silicon with specific concentration ratios (35-65% W and 50-50% W and 50-50% Si) is formed using a chemical vapor deposition method or sputtering, eliminating crystal grain boundaries and enhancing resistance to plasma etching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the thickness of the hard mask is increased to maintain the hard mask until the end of plasma etching, then the resistance to plasma etching is improved, but the target object warps due to the film stress of the hard mask
Solution Approach 1:
The invention changes the compositional parameters of the hard mask by controlling the tungsten to silicon ratio within specific ranges (W:Si = 1:4 to 4:1 atomic ratio). This parameter change creates a material with optimized etch resistance that achieves the required protection without needing excessive thickness, thereby preventing film stress-induced warping of the target object.
Solution Approach 2:
The invention uses a composite material system combining tungsten and silicon in specific proportions to create a hard mask with balanced properties. The composite structure leverages the high etch resistance of tungsten while incorporating silicon to modulate the overall film stress and compositional characteristics, achieving both protection and dimensional stability.
2Reliability
If a tungsten silicide film is used as a hard mask, then the material is suitable for plasma etching of silicon-containing films, but the film is etched quickly at crystal grain boundaries
Solution Approach 1:
The invention changes the compositional parameters by controlling the tungsten to silicon atomic ratio within 1:4 to 4:1, which optimizes the material's etch resistance. This parameter optimization ensures uniform etch protection across the film, eliminating the vulnerability at crystal grain boundaries while maintaining suitability for silicon-containing film etching.
3Shape
If the hard mask is made thinner to prevent warping, then the film stress is reduced, but the resistance to plasma etching decreases
Solution Approach 1:
The invention changes the material composition parameters (W:Si atomic ratio of 1:4 to 4:1) to achieve superior etch resistance per unit thickness. This allows the hard mask to be thinner while maintaining adequate protection, thereby reducing film stress and preventing warping without sacrificing etch resistance.
Solution Approach 2:
The composite tungsten-silicon material system provides enhanced specific etch resistance that allows reduced thickness. The synergistic combination of tungsten's protective properties and silicon's stress-modulating properties enables a thinner film design that maintains both structural integrity and etch protection.
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 amorphous hard mask exhibits improved resistance to plasma etching and can be selectively removed post-etching, reducing film stress and maintaining structural integrity.
Implementation Method 1
forming a hard mask containing tungsten and silicon, which is an amorphous film, on the silicon-containing film by sputtering using the film forming apparatus
Data Source
AI summary
In one embodiment, this hard mask for plasma etching is formed on a silicon-containing film. The hard mask is an amorphous film, and contains tungsten and silicon. The ratio of the concentration of tungsten and the concentration of silicon in the surface of the hard mask can be within the range between a ratio specifying that the concentration of tungsten is 35 at % and the concentration of silicon is 65 at % and a ratio specifying that the concentration of tungsten is 50 at % and the concentration of silicon is 50 at %.