Resist Underlayer Film Composition for Semiconductor Etching
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Solution Overview
Problem
The miniaturization of semiconductor devices poses challenges in achieving sufficient exposure process latitude and depth of focus, leading to difficulties in forming resist films with adequate thickness for etching, while also requiring materials that exhibit etching resistance and reduce outgas generation during the multilayer resist process.
Innovation Solution
A resist underlayer film-forming composition comprising a polymer with a specific structural unit and solvent, which provides excellent etching resistance, filling capability on non-planar substrates, and reduced outgas generation, achieved by controlling the molecular weight and dispersity of the polymer within specific ranges, and optionally including an acid generator and crosslinking agent.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the thickness of the resist film is reduced to improve resolution and compensate for exposure process latitude shortage, then resolution is improved, but the resist film thickness becomes insufficient for etching the processing target film
Solution Approach 1:
The invention divides the single resist film structure into two separate layers: a thin resist film (50-200 nm) for achieving high-resolution patterning and a thicker resist underlayer film (200-500 nm) for providing sufficient etching resistance. This segmentation allows each layer to optimize its thickness for its specific function, resolving the contradiction between resolution and etching capability
Solution Approach 2:
The invention transitions from a single-dimensional (single-layer) resist structure to a two-dimensional (multi-layer) resist structure by introducing a resist underlayer film beneath the main resist film. This dimensional change enables independent optimization of thickness for each layer, allowing the top layer to be thin for resolution while the bottom layer provides thickness for etching
2Strength
If a resist underlayer film-forming composition containing polymer with side-chain alkynyloxy group is used to achieve etching resistance, then etching resistance is improved, but outgas generation increases causing contamination of the production system
Solution Approach 1:
The invention changes the molecular weight parameter of the polymer from high (conventional) to low (3000-10000 polystyrene-reduced weight average molecular weight). This parameter change reduces outgas generation and contamination while maintaining etching resistance through the multi-layer structure design
Solution Approach 2:
The invention uses a composite material system consisting of low molecular weight polymer (etching resistance component) and specific solvent (volatility control component). This composite approach achieves etching resistance while minimizing outgas generation through careful material selection and composition optimization
3Manufacturing precision
If the aspect ratio is increased to achieve higher filling capability in depressions, then filling capability is improved, but in-plane depression distribution becomes non-uniform making planarization difficult
Solution Approach 1:
The invention changes the viscosity parameter of the resist underlayer film-forming composition by selecting specific low molecular weight polymers and solvents with appropriate boiling points. This viscosity optimization enables the composition to flow into and fill deep depressions uniformly across the substrate surface, achieving both high filling capability and planarization
Data Source
AI summary
A resist underlayer film-forming composition includes a polymer including a structural unit shown by a formula (1), and having a polystyrene-reduced weight average molecular weight of from 3000 to 10000, and a solvent. Each of R3 to R8 independently represents a group shown by a formula (2), a hydrogen atom, a hydroxyl group, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, an alkoxycarbonyl group having 2 to 10 carbon atoms, an aryl group having 6 to 14 carbon atoms, or a glycidyl ether group having 3 to 6 carbon atoms, wherein at least one of R3 to R8 represents the group shown by the formula (2).