Ruthenium Hard Mask for Etch Resistance and Selective Removal
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Solution Overview
Problem
As critical dimensions on substrates shrink, existing patterning techniques face challenges in achieving the appropriate balance of etch resistance, removability, and thickness for hard mask layers, particularly in small geometry structures, due to aspect ratio dependent etch issues and compatibility with other materials.
Innovation Solution
A ruthenium hard mask material is used, which provides etch resistance to common plasma chemistries and can be easily removed using oxygen plasma, allowing for thin film deposition over oxides and nitrides, thereby minimizing aspect ratio effects and maintaining pattern integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional hard mask materials (silicon oxide, silicon nitride, titanium) are used, then etch resistance is provided, but thickness must be increased which creates aspect ratio dependent etch issues
Solution Approach 1:
The patent changes the material composition parameter from traditional hard mask materials (silicon oxide, silicon nitride, titanium) to ruthenium, which fundamentally alters the etch resistance characteristics. Ruthenium provides superior etch resistance that allows the hard mask layer to be much thinner while maintaining adequate protection during etching processes, thereby resolving the contradiction between etch resistance and thickness.
2Length of stationary object
If thin hard mask layers are used to minimize aspect ratio effects, then aspect ratio dependency is reduced, but etch resistance is insufficient
Solution Approach 1:
By changing the material parameter to ruthenium, the patent achieves a material that provides high etch resistance at reduced thicknesses. Ruthenium's inherent properties allow thin layers (sufficiently thin to minimize aspect ratio effects) to maintain adequate etch resistance, resolving the contradiction between thickness and etch resistance.
3Manufacturing precision
If hard mask layer thickness is increased to improve etch resistance, then pattern transfer fidelity improves, but removal becomes more difficult
Solution Approach 1:
The patent changes the material parameter to ruthenium, which has selective etchability - it resists etching during pattern transfer but can be selectively removed using oxygen plasma. This allows thin ruthenium layers to provide sufficient pattern transfer fidelity while remaining easily removable, resolving the contradiction between pattern transfer fidelity and removal ease.
4Adaptability or versatility
If conventional hard mask materials are used, then process compatibility is maintained, but selectivity to various etches and removability becomes challenging
Solution Approach 1:
The patent changes the material parameter to ruthenium, which exhibits selective behavior: it resists etching by plasma chemistries used for nitrides, oxides, and anti-reflective coating materials, yet can be selectively removed by oxygen plasma. This selective etch resistance and controlled removability resolves the contradiction between process compatibility and selectivity/removability.
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 ruthenium hard mask layer offers high selectivity and minimal impact on surrounding layers during etching and removal, effectively addressing the challenges of shrinking critical dimensions and aspect ratio dependent etch issues, while maintaining the integrity of small geometry structures.
Implementation Method 1
Ruthenium provides a hard mask material that is etch resistant to many of the plasma chemistries typically used for processing substrate patterning layers
Implementation Method 2
ruthenium may be easily removed through the use of an oxygen (O2) plasma
Implementation Method 3
ruthenium may be easily removed through the use of an oxygen (O2) plasma
Implementation Method 4
ruthenium may be deposited as a thin planar 10 nm order film over oxides and nitrides and may be deposited as a planar layer
Data Source
AI summary
A process is provided in which a hard mask material comprising ruthenium is used. Ruthenium provides a hard mask material that is etch resistant to many of the plasma chemistries typically used for processing substrate patterning layers, including layers such as, for example, nitrides, oxides, anti-reflective coating (ARC) materials, etc. Further, ruthenium may be removed by plasma chemistries that do not remove nitrides, oxides, ARC materials, etc. For example, ruthenium may be easily removed through the use of an oxygen (O2) plasma. Further, ruthenium may be deposited as a thin planar 10 nm order film over oxides and nitrides and may be deposited as a planar layer.