Phenolic Copolymers for Sub-Quarter Micron Lithography
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Solution Overview
Problem
Current photoresists face challenges in forming highly resolved sub-half micron and sub-quarter micron features, particularly when exposed to short wavelengths like 248 nm, which is essential for advanced circuit patterns and device performance.
Innovation Solution
Development of new phenolic copolymers with photoacid-labile groups and phenolic units spaced from the polymer backbone, specifically using polymerized acrylate moieties, to enhance photoimaging capabilities and facilitate chemically-amplified positive-acting resists.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If current photoresist compositions are used, then existing lithographic processing is maintained, but formation of highly resolved sub-half micron and sub-quarter micron features is insufficient
Solution Approach 1:
The patent modifies the chemical structure of phenolic polymers by spacing phenolic groups from the polymer backbone through methylene bridges or other spacers, and by incorporating photoacid-labile groups. These parameter changes in molecular structure enable the resin to respond more effectively to short wavelength radiation (248 nm), thereby improving feature resolution and image quality without sacrificing reliability
Solution Approach 2:
The invention creates composite photoresist formulations by combining modified phenolic polymers with photoacid generators and other resist components. This composite approach allows the system to achieve both high resolution for sub-quarter micron features and reliable performance at short wavelengths by synergistic interaction of components
2Productivity
If short wavelength radiation (248 nm) is used for exposure, then smaller circuit features can be formed, but current photoresists do not yield well-resolved images
Solution Approach 1:
The patent changes the optical and chemical parameters of the photoresist by incorporating phenolic groups spaced from the polymer backbone and photoacid-labile groups. These modifications enable the resist to absorb and respond to short wavelength (248 nm) radiation more effectively, producing well-resolved images that maintain high circuit density while achieving the required manufacturing precision for sub-0.25 μm features
3Stability of the object's composition
If phenolic groups are directly attached to polymer backbone, then polymer stability is maintained, but photoacid-labile group effectiveness is reduced
Solution Approach 1:
The patent segments the phenolic polymer structure by introducing spacer units (methylene bridges, ethylene bridges, or other spacers) between the polymer backbone and the phenolic groups. This segmentation serves two functions: it maintains the stability of the polymer backbone while positioning the phenolic groups and photoacid-labile groups at optimal distances and orientations to enhance their responsiveness to photogenerated acid, thereby improving manufacturing precision
Solution Approach 2:
The spacer units act as intermediaries between the polymer backbone and the phenolic/photoacid-labile groups. These intermediary structures allow the backbone to maintain its stabilizing function while enabling the pendant groups to effectively participate in photoacid-induced reactions, resolving the contradiction between stability and responsiveness
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
These polymers enable the formation of highly resolved relief images with line widths of 0.25 microns or less, improving circuit density and device performance by effectively responding to short wavelength exposure, such as 248 nm radiation.
Implementation Method 1
Exposure to activating radiation provides a photoinduced chemical transformation of the photoresist coating
Implementation Method 2
The photomask has areas that are opaque to activating radiation and other areas that are transparent to activating radiation
Data Source
AI summary
The present invention relates to new polymers that contain phenolic groups spaced from a polymer backbone and photoacid-labile group. Preferred polymers of the invention are useful as a component of chemically-amplified positive-acting resists.