Polymer Backbone Acid Generator Stability in Lithography
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Solution Overview
Problem
The challenge is to produce a polymer with an acid generator bound to its backbone, specifically an onium salt having polymerizable olefin, that maintains stability during polymerization, preventing acid diffusion and ensuring consistent resolution performance in resist materials, while avoiding decomposition of acid labile groups or crosslinking reactions.
Innovation Solution
The polymerization of monomers in a solution containing a non-polymerizable compound with a nitrogen atom and an acid labile group helps to neutralize any generated acid, preventing deprotection or crosslinking reactions, and using specific illumination conditions to minimize photo-decomposition, ensuring the polymer's stability and performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If onium salt having polymerizable olefin is decomposed during polymerization to generate acid, then acid diffusion is suppressed and resolution is improved, but deprotection of acid labile groups occurs causing unexposed region dissolution
Solution Approach 1:
The patent applies preliminary action by adding a basic compound to the polymerization solution before polymerization begins. This basic compound pre-neutralizes any acid that may be generated during polymerization, preventing deprotection of acid labile groups on the polymer backbone. The basic compound is present in advance to counteract the harmful acid effect before it can cause unwanted deprotection reactions.
Solution Approach 2:
The basic compound acts as an intermediary substance between the acid generator (onium salt) and the acid labile groups on the polymer. It mediates the interaction by neutralizing the acid generated from onium salt decomposition, preventing direct contact between the acid and the acid labile groups that would otherwise cause deprotection and pattern formation failure.
2Manufacturing precision
If accelerating voltage of electron gun is increased to reduce pattern rule, then resolution and dimensional control are improved, but sensitivity of resist film decreases
Solution Approach 1:
The patent applies self-service by incorporating the acid generator directly into the polymer backbone structure itself. The polymer contains recurring units with onium salts that generate acid upon exposure, eliminating the need for separate acid diffusion from external sources. This self-contained acid generation mechanism ensures that even at high accelerating voltages where electron scattering is reduced, the resist maintains sufficient sensitivity through localized acid production at the exposure sites.
3Area of moving object
If feature size is reduced to increase integration density, then storage capacity is improved, but acid diffusion causes image blur
Solution Approach 1:
The patent applies segmentation by dividing the acid generation function into individual onium salt units distributed along the polymer backbone. Each onium salt unit generates acid locally at its specific position upon exposure, preventing long-range acid diffusion that would cause image blur. This segmented acid generation approach maintains sharp image boundaries even at reduced feature sizes, enabling higher integration density without sacrificing resolution.
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
This method produces a polymer that suppresses acid diffusion and minimizes edge roughness, providing consistent performance and long-term storage stability for resist materials, suitable for semiconductor lithography and other applications.
Implementation Method 1
If the onium salt having polymerizable olefin is decomposed during polymerization, it generates an acid, with which deprotection of the acid labile group on the acid labile group-bearing recurring unit takes place.
Implementation Method 2
Effective means for preventing photo-decomposition of the onium salt during polymerization includes shielding of the reactor from light
Data Source
AI summary
A polymer comprising recurring units having an acid generator bound to the backbone, and recurring units having an optionally acid labile group-substituted carboxyl group and/or recurring units having an optionally acid labile group-substituted hydroxyl group is obtained by polymerizing corresponding monomers in a solution of a non-polymerizable compound containing a nitrogen atom to which an acid labile group is bound. This prevents deprotection reaction of the acid labile group in the case of positive resist-forming polymer or crosslinking reaction in the case of negative resist-forming polymer.