Crosslinkable EUV Photoresist for Resolution and Roughness Control
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Solution Overview
Problem
As critical dimensions in semiconductor integrated circuits shrink, the ability of photoresists to perfectly replicate photomask features is challenged by image blur due to photoacid diffusion, leading to reduced resolution and increased line width roughness.
Innovation Solution
Development of crosslinkable photoresist polymers with halogenated functional groups that covalently bond to polymer sidechains, increasing glass transition temperatures to restrict photoacid diffusion and enhance dimensional stability, thereby improving pattern quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If photoresist layer is used for lithography, then pattern transfer is enabled, but photoacid diffusion causes image blur reducing resolution
Solution Approach 1:
The patent changes the chemical parameters of the photoresist polymer by incorporating halogenated functional groups (fluorinated or chlorinated alkylene groups) into the polymer backbone. This chemical modification increases the glass transition temperature and reduces photoacid diffusion, directly resolving the resolution limitation caused by photoacid diffusion.
Solution Approach 2:
The patent uses composite polymer structures combining halogenated functional groups with specific aromatic rings (naphthalene, anthracene, phenanthrene) and linker groups. This composite material approach creates a photoresist with enhanced dimensional stability and reduced photoacid diffusion while maintaining lithographic performance.
2Productivity
If geometry size is decreased, then functional density increases, but manufacturing complexity increases
Solution Approach 1:
By changing the physical-chemical parameters of the photoresist (increasing glass transition temperature through halogenation), the patent enables reliable patterning at smaller geometry sizes without proportionally increasing processing complexity. The material improvement allows standard lithography processes to achieve higher functional density.
3Manufacturing precision
If polymer glass transition temperature is increased, then photoacid diffusion is restricted, but polymer synthesis complexity increases
Solution Approach 1:
The patent applies local quality by introducing halogenated functional groups at specific positions within the polymer structure (in the backbone or as side chains) rather than uniformly throughout. This targeted modification achieves the desired glass transition temperature increase while maintaining reasonable polymer synthesis feasibility.
Solution Approach 2:
The patent systematically varies parameters such as the type of aromatic ring (naphthalene, anthracene, phenanthrene), the length of alkylene linkers (L1-L6), and the degree of halogenation to optimize glass transition temperature. This parameter optimization approach balances dimensional stability with polymer synthesis complexity.
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 solution provides higher resolution and reduced line width roughness, enhancing the yield and reliability of semiconductor devices by improving resist pattern quality.
Implementation Method 1
exposing the photoresist layer to an extreme ultraviolet (EUV) radiation, heating the photoresist layer, during which the polymer reacts with the crosslinker to form a crosslinked polymer in exposed regions of the photoresist layer
Implementation Method 2
crosslinkable photoresist polymers with halogenated functional groups that increase glass transition temperatures, restricting photoacid diffusion and improving dimensional stability
Data Source
AI summary
A method for forming a semiconductor device includes forming a photoresist layer over a substrate, exposing the photoresist layer to radiation to form a pattern therein, and selectively removing portions of the photoresist layer that are not exposed to the radiation to form a patterned photoresist layer. The photoresist layer comprises a fluorine-containing polymer, a crosslinker and a photoactive compound.