Conformal Anti-Reflective Coating for IC Topography
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Solution Overview
Problem
Current Bottom Anti-Reflective Coatings (BARCs) used in integrated circuit fabrication are non-conformal, leading to aggressive dry etching that damages underlying topography, and developable BARCs face issues with compatibility and incomplete development, making it challenging to maintain dimension control and perform uniform ion implantation.
Innovation Solution
A conformal and thin anti-reflective film is formed using molecular layer deposition, composed of organic compounds bound to inorganic compounds, which absorbs light in the 150-500 nm range, allowing for uniform etching and ion implantation without damaging the substrate topography.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If spin-coating is used to deposit BARC, then the deposition process is simple and fast, but the BARC layer is non-conformal leading to variation in implant dose and aggressive etching that damages topography
Solution Approach 1:
The patent replaces the mechanical spin-coating process with a chemical vapor deposition process (PECVD or APCVD). This substitution allows for conformal deposition through controlled chemical reactions on the substrate surface, achieving uniform thickness even on complex topographies while maintaining production efficiency through scalable batch processing.
Solution Approach 2:
The patent changes the deposition parameters by controlling temperature, pressure, and gas flow rates in the CVD process. By optimizing these parameters, the process achieves conformal coverage with uniform thickness, solving the non-conformal issue of spin-coating while maintaining high productivity through efficient deposition rates.
2Ease of manufacture
If aggressive dry etching is used to remove BARC, then complete BARC removal is achieved, but the underlying topography is partially attacked and damaged
Solution Approach 1:
The patent creates a BARC layer with locally optimized properties - the conformal structure ensures uniform etch rate across different areas, while the specific composition provides selective etchability. This allows mild etching conditions to remove the BARC completely without attacking the underlying topography, as the etch process can be tuned to target only the BARC material.
Solution Approach 2:
The patent uses a composite BARC structure deposited by CVD that combines materials with complementary properties. The composite nature provides both the necessary anti-reflective functionality and controlled etch selectivity, enabling complete removal under mild conditions that protect the underlying topography from damage.
3Device complexity
If developable BARC is used to eliminate dry etching, then the BARC can be removed during resist development, but there is lack of compatibility with overlying resist, higher development speed in dense areas, and incomplete BARC development
Solution Approach 1:
The patent modifies the chemical composition and cross-linking density parameters of the BARC material to achieve the desired properties. By controlling these parameters, the BARC becomes sufficiently resistant to standard resist developers (ensuring compatibility) while maintaining uniform etch selectivity and preventing the iso-dense bias effects that plague developable BARC systems.
Solution Approach 2:
The patent employs a composite material system where the BARC layer combines polymer matrix with inorganic cross-linking agents or nanoparticles. This composite structure provides the necessary mechanical integrity, chemical resistance to developers, and controlled etchability, while eliminating the development uniformity issues of conventional developable BARC materials.
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 conformal anti-reflective film enables defect-free structure preparation during ion implantation or etching, ensuring homogeneous ion implantation and reducing the risk of topography damage, while also providing adequate anti-reflective properties at low thickness, facilitating improved ion implantation processes.
Implementation Method 1
The anti-reflective film may be formed of a compound selected from the group consisting of: (i) an organic compound chemically bound to an inorganic compound, where one of the organic compound and the inorganic compound is bound to the substrate and where the organic compound absorbs light at at least one wavelength selected in the range 150-500 nm
Implementation Method 2
providing an anti-reflective film conformally over the substrate using a molecular layer deposition step
Data Source
AI summary
In one aspect, a method is disclosed that includes providing a substrate having a topography that comprises a relief and providing an anti-reflective film conformally over the substrate using a molecular layer deposition step. The anti-reflective film may be formed of a compound selected from the group consisting of: (i) an organic compound chemically bound to an inorganic compound, where one of the organic compound and the inorganic compound is bound to the substrate and where the organic compound absorbs light at at least one wavelength selected in the range 150-500 nm, or (ii) a monodisperse organic compound absorbing light at at least one wavelength selected in the range 150-500 nm. The method further includes providing a photoresist layer on the anti-reflective film.