Carbosilane Polymer Anti-Reflective Coatings for Lithography
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Solution Overview
Problem
Current anti-reflective coatings for semiconductor devices face challenges in achieving optimal optical properties, thermal, and mechanical durability, particularly in reducing off-normal reflection effects and standing wave variations during lithographic processes, which are critical for fabricating features smaller than 0.5 μm.
Innovation Solution
Development of novel silicon-based compositions, specifically hybrid organic/inorganic silicon polymer materials with chromophore side groups attached to silicon atoms, which are synthesized using organo-silane precursors and polymerized to form carbosilane/siloxane polymers, allowing for tailored refractive index and absorption coefficients to suit specific exposure wavelengths and device requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional anti-reflective coatings are used, then optical properties can be achieved, but thermal and mechanical durability is insufficient
Solution Approach 1:
The patent employs hybrid organic-inorganic carbosilane polymer compositions that combine the thermal stability of inorganic silicon-based materials with the mechanical flexibility and optical tunability of organic polymers. This composite structure achieves both durability and optical performance requirements simultaneously
Solution Approach 2:
The invention modifies the chemical composition and molecular structure of the polymer materials by varying silicon content, cross-linking density, and chromophore groups to precisely control refractive index, absorption coefficient, and mechanical properties for different lithographic applications
2Manufacturing precision
If anti-reflective coatings are designed for optimal optical properties, then line width control improves, but mechanical strength decreases
Solution Approach 1:
The patent introduces cross-linking at specific locations within the polymer matrix to reinforce mechanical strength only where needed, while maintaining the optical properties in the bulk material. This localized structural modification preserves optical performance while enhancing durability
Solution Approach 2:
The polymer structure is divided into distinct functional segments: chromophore groups for optical control, silicon-based backbone for mechanical strength, and cross-linking points for localized reinforcement. This segmentation allows independent optimization of each property
3Object-generated harmful factors
If the refractive index is matched for destructive interference, then reflection is suppressed, but film thickness control becomes critical
Solution Approach 1:
The patent utilizes the tunable refractive index of carbosilane polymers to optimize the product of refractive index and film thickness (n×d) for destructive interference conditions. By adjusting polymer composition, the required film thickness can be optimized to balance reflection suppression with manufacturing tolerances
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 new compositions provide enhanced mechanical and thermal properties, improved line width control, and tailored optical properties, effectively reducing reflections and variations in pattern dimensions, enabling the fabrication of smaller semiconductor features with improved precision.
Implementation Method 1
The light-waves used in the exposure propagate through the photoresist film down to the substrate, and are reflected back up through the photoresist. This causes off-normal reflection effects and standing wave effects.
Implementation Method 2
anti-reflection coatings can be used to dampen the reflections. The reflections are suppressed either by attenuating the light that passes through the ARC, or by matching the index of refraction of the ARC to the resist system at the exposure wavelength employed such that destructive interference of the light passing through the ARC occurs.
Implementation Method 3
These compositions are synthesized by using organo-silane precursors where at least one chromophore sidegroup is directly attached to a silicon atom. The silicon atom of the monomeric precursor also contains one or more hydrolysable groups and it can be further polymerized to form a carbosilane/organo-siloxane polymer
Data Source
AI summary
A silicon polymer material, which has a silicon polymer backbone with chromophore groups attached directly to at least a part of the silicon atoms, the polymer further exhibiting carbosilane bonds. The film forming composition and resulting coating properties can be tailored to suit the specific exposure wavelength and device fabrication and design requirements. By using two different chromophores the refractive index and the absorption co-efficient can be efficiently tuned. By varying the proportion of carbosilane bonds, and a desired Si-content of the anti-reflective coating composition can be obtained.