PS-CAR Bottom Anti-Reflective Coatings for Acid Concentration Control
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Solution Overview
Problem
Current photolithography techniques face challenges in achieving precise reflection control and reducing costs, particularly in electronic device manufacturing, where existing Bottom Anti-reflective Coatings (BARCs) require an open etch process and do not effectively manage acid concentration in photoresist and anti-reflective coating layers.
Innovation Solution
The integration of Photosensitized Chemically Amplified Resist (PS-CAR) chemistries into the photoresist or anti-reflective coating layers, utilizing a two-step exposure process with different light wavelengths to selectively generate and amplify acid concentrations, optimizing the geometry of the photoresist layer and controlling exposure latitude through UV flood dose.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional lithography BARC is used, then substrate reflection control is achieved, but an additional BARC open etch process step is required
Solution Approach 1:
The patent combines the BARC functionality with the photoresist layer into an integrated DBARC structure. The photoresist layer itself is engineered to provide both the patterning function and the bottom anti-reflective coating function, eliminating the need for a separate BARC layer and its associated open etch process step.
Solution Approach 2:
The photoresist layer is designed to perform multiple functions simultaneously: it serves as the patterning resist and as the bottom anti-reflective coating. This multi-functional design eliminates the need for dedicated BARC materials and processes, reducing overall process complexity while maintaining reflection control.
2Quantity of substance
If chemical amplification is increased in photoresist, then acid concentration is amplified, but organic residue increases
Solution Approach 1:
The patent employs a dual-layer DBARC structure with different compositions optimized for local functions. The lower DBARC layer provides reflection control while the upper DBARC layer is optimized for acid generation and amplification. This spatial differentiation allows high acid concentration in the upper layer without excessive organic residue accumulation in the lower layer that contacts the substrate.
Solution Approach 2:
The patent uses a UV-curable resin system that undergoes complete photopolymerization upon exposure and development. The chemically amplified photoresist components are designed to be fully consumed in the chemical reactions, minimizing residual organic material. The UV curing process ensures complete conversion of monomers and oligomers, reducing organic residue.
3Ease of operation
If DBARC is made photosensitive with cleave reaction, then develop solubility is improved, but additional chemical compounds are required
Solution Approach 1:
The patent utilizes photoacid generators that undergo chemical transformation upon light exposure, generating acid that catalyzes the cleavage of specific chemical bonds in the DBARC layers. This parameter change (chemical structure modification upon exposure) provides the necessary develop solubility differentiation between exposed and unexposed regions.
Solution Approach 2:
The DBARC layers are formulated as composite materials containing polymer matrices, photoacid generators, and cleavable linkers. This composite structure integrates multiple functional components that work together to provide both the anti-reflective properties and the photosensitive development characteristics.
4Adaptability or versatility
If exposure latitude is increased, then process window is improved, but acid concentration control becomes more difficult
Solution Approach 1:
The patent employs a two-layer DBARC structure where the lower layer provides a feedback mechanism for acid diffusion control. The distinct chemical compositions of the two layers create a controlled acid diffusion pathway that provides feedback on exposure conditions, allowing the system to maintain acid concentration control across a broader exposure latitude.
Solution Approach 2:
The patent segments the DBARC into two functionally distinct layers with different thicknesses and compositions. The lower layer (closer to substrate) and upper layer (closer to photoresist) are optimized for different functions, allowing independent optimization of reflection control and acid generation/ amplification, thereby improving exposure latitude while maintaining precision.
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 approach enhances acid concentration control, reduces organic residue, and allows for easier exposure matching, improving image quality and reducing costs by eliminating the need for a BARC open etch process, while maintaining high sensitivity and resolution in photolithography.
Implementation Method 1
incorporate photosensitive chemically amplified resist (PS-CAR) chemistries into the DBARC itself rather than, or in addition too, the photoresist
Implementation Method 2
utilizing a two-step exposure process with different light wavelengths to selectively generate and amplify acid concentrations
Data Source
AI summary
The disclosure herein describes methods for Photosensitized Chemically Amplified Resist Chemicals (PS-CAR) to pattern light sensitive films (e.g., photoresist on anti-reflective coatings) on a semiconductor substrate. In one embodiment, a two-step exposure process may generate higher acid concentration regions within a photoresist layer. The PS-CAR chemicals may include photoacid generators (PAGs) and photosensitizer elements that enhance the decomposition of the PAGs into acid. The first exposure may be a patterned EUV or UV exposure that generates an initial amount of acid and photosensitizer. The second exposure may be a non-EUV flood exposure that excites the photosensitizer which increases the acid generation rate where the photosensitizer is located in the film stack. The distribution of energy during the exposures may be optimized by using certain characteristics (e.g., thickness, index of refraction, doping) of the photoresist layer, an underlying layer, and/or an overlying layer.