Photoresist Copolymer Additive for Etch-Resistant Fine Patterns
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Solution Overview
Problem
As semiconductor circuits become smaller and more complex, there is a challenge in maintaining etch selectivity and preventing pattern defects such as leaning and collapse during the etching process, especially with decreasing photoresist pattern sizes and increasing aspect ratios.
Innovation Solution
A photoresist composition incorporating a chemically amplified polymer, a photoacid generator, and a copolymer additive with Group-14 elements, which forms a surface self-segregation layer to enhance etch selectivity and resist pattern stability, using a solvent and specific repeating units to improve lithography processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If photoresist pattern size is decreased to meet smaller semiconductor circuits, then device integration density is improved, but etch selectivity deteriorates and pattern defects increase
Solution Approach 1:
The patent applies local quality by creating a surface self-segregation layer with distinct chemical composition at the photoresist surface. The copolymer additive containing Group-14 elements (Si, Ge, Sn) segregates to the surface, providing localized etch resistance where it is most needed, while the bulk photoresist maintains its original properties for pattern formation.
Solution Approach 2:
The patent uses composite materials by incorporating a copolymer additive with specific repeating units containing Group-14 elements into the photoresist composition. This creates a composite system where the copolymer segments provide etch selectivity enhancement while the base photoresist polymer maintains patterning functionality.
2Length of stationary object
If photoresist pattern thickness is increased to improve etch selectivity, then etch resistance is improved, but aspect ratio increases causing pattern collapse
Solution Approach 1:
The surface self-segregation layer provides localized etch protection at the photoresist surface without requiring increased pattern thickness. This maintains favorable aspect ratios while achieving the necessary etch selectivity through surface-specific chemical composition rather than bulk thickness enhancement.
3Reliability
If copolymer additive concentration is increased to enhance etch selectivity, then etch resistance is improved, but manufacturing complexity increases
Solution Approach 1:
The patent optimizes the concentration parameter of the copolymer additive to achieve sufficient etch selectivity enhancement. By carefully selecting the additive concentration range, the patent balances etch resistance improvement with manufacturing simplicity, avoiding excessive complexity while achieving the desired performance.
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 composition ensures improved etch selectivity and reliability in forming integrated circuit devices by reducing pattern defects and enhancing etch resistance, even with reduced photoresist pattern sizes.
Implementation Method 1
pre-treating the photoresist film such that the copolymer additive moves to an exposed surface side of the photoresist film to form a surface self-segregation layer
Implementation Method 2
exposing a partial region of the pre-treated photoresist film to light, and forming a photoresist pattern including the surface self-segregation layer, in a non-light-exposed region of the photoresist film
Data Source
AI summary
Provided is a photoresist composition including a chemically amplified polymer, a photoacid generator (PAG), a copolymer additive including a Group-14 element, and a solvent, wherein the copolymer additive includes repeating units satisfyingwhere R1 and R2 are each a hydrogen atom (H) or a C1-C3 alkyl group, Ya is a substituted or unsubstituted C1-C20 bivalent linear hydrocarbon group, a substituted or unsubstituted C1-C20 bivalent cyclic hydrocarbon group, a substituted or unsubstituted C7-C20 bivalent alkylaryl group, or a carbonyl group, Rm is a protecting group including at least one Group-14 element, Rf is a group including a plurality of fluorine atoms (F), a is 0 or 1, and m/(m+n) and n/(m+n) are each 0.05 to 0.95.