Base-Reactive Photoacid Generators for Sub-Quarter Micron Lithography
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Solution Overview
Problem
Current photoresist compositions face challenges in achieving highly resolved images of sub-micron dimensions due to slow base-promoted dissociation rates of existing photoacid generator compounds, leading to defects and reduced exposure latitude and increased mask error factors.
Innovation Solution
Development of novel photoacid generator compounds with base-reactive moieties that react upon treatment with aqueous alkaline developers, specifically designed to improve lithographic performance by providing fast base-promoted dissolution rates and enhanced hydrophilicity, allowing for the formation of sub-quarter micron relief images.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If conventional photoacid generator compounds are used, then the photoresist composition can be formulated with standard components, but the base-promoted dissociation rate is slow leading to reduced lithographic performance
Solution Approach 1:
The patent modifies the chemical structure of photoacid generator compounds by incorporating base-reactive moieties (such as ester groups, carbonate groups, carbamate groups, or carboxylic acid groups) that undergo rapid base-promoted dissociation. This structural parameter change enables the PAG to quickly release acid upon exposure and subsequent base treatment, achieving fast dissociation rates that improve lithographic performance including reduced mask error factor and enhanced exposure latitude
Solution Approach 2:
The patent creates composite photoacid generator molecules that combine a photolabile group (such as sulfonium or iodonium salt) with base-reactive moieties. This composite structure allows the molecule to perform dual functions: generating acid upon photoexposure and rapidly dissociating upon base treatment, thereby resolving the contradiction between standard formulation and high-speed dissociation performance
2Manufacturing precision
If photoresist compositions are designed for sub-micron resolution, then image quality improves, but defects increase due to slow PAG dissolution rates
Solution Approach 1:
By incorporating base-reactive moieties into the PAG structure, the patent achieves rapid base-promoted dissociation that prevents defect formation during development. This parameter change in dissociation rate ensures that the photoresist cleanly transitions between exposed and unexposed states, enabling sub-micron resolution without the defectivity that plagues conventional systems
Solution Approach 2:
The base-reactive moiety acts as an intermediary that mediates between the photogenerated acid and the aqueous alkaline developer. This intermediary group facilitates rapid and complete dissolution of the exposed photoresist regions, preventing the partial dissolution and defect formation that occur with conventional PAGs that dissolve too slowly
3Adaptability or versatility
If conventional PAGs are used, then the photoresist formulation is simpler, but exposure latitude is reduced and mask error factor increases
Solution Approach 1:
The patent employs composite PAG molecules that integrate photolabile groups with base-reactive moieties. This composite design provides broad exposure latitude and low mask error factor while maintaining reasonable molecular complexity through the use of well-established chemical building blocks that can be combined in modular fashion
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 photoacid generator compounds enable the creation of highly resolved images with reduced defects, improved exposure latitude, and lower mask error factors, as demonstrated by their ability to produce sub-0.2 or sub-0.1 micron dimension patterns with improved lithographic performance compared to conventional photoresists.
Implementation Method 1
the coating is exposed through a patterned photomask to a source of activating energy such as ultraviolet light to form a latent image in the photoresist coating
Implementation Method 2
the base-reactive moiety will react upon treatment with aqueous alkaline developer compositions, such as 0.26N tetramethylammonium hydroxide aqueous developer compositions
Data Source
AI summary
This invention relates to new photoacid generator compounds and photoresist compositions that comprise such compounds. In particular, the invention relates to photoacid generator compounds that comprise base-cleavable groups.