PAG-Free Positive Chemically Amplified Resist for PEB-Free Lithography
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Solution Overview
Problem
Existing photoresist compositions face challenges in achieving cost-effectiveness, high resolution, and throughput in the manufacture of integrated circuits and displays, particularly due to issues with sloped profiles, T-topping defects, and sensitivity to airborne base contamination in chemically amplified resists, which require a post-exposure bake step.
Innovation Solution
A hybrid resist composition combining Novolak/diazonaphthoquinone and chemically amplified systems without a photoacid generator (PAG), using acetal-protected phenolic resins and 2,1,5-diazonaphthoquinonesulfonate compounds that deprotect during exposure, eliminating the need for a post-exposure bake and reducing sensitivity to contaminants.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If chemically amplified photoresist with high activation energy protecting groups is used to achieve high resolution, then manufacturing precision is improved, but productivity deteriorates due to required post-exposure bake step
Solution Approach 1:
The patent changes the activation energy parameter of the protecting group from high to low, enabling the resist to be developed without post-exposure bake. This parameter change resolves the contradiction by maintaining resolution while eliminating the time-consuming PEB step, thereby improving throughput.
Solution Approach 2:
The protecting group is designed to undergo acid-catalyzed cleavage at low activation energy during the exposure step itself, performing the deprotection action preliminarily before development. This eliminates the need for separate post-exposure bake step, resolving the productivity issue while maintaining precision.
2Manufacturing precision
If chemically amplified photoresist with high activation energy protecting group is used to achieve good resolution, then manufacturing precision is improved, but reliability deteriorates due to sensitivity to airborne base contamination
Solution Approach 1:
The patent changes the activation energy parameter to low values, which fundamentally alters the chemical behavior of the protecting group. This enables the resist to be less sensitive to airborne base contamination while maintaining resolution, resolving the reliability issue.
3Ease of manufacture
If conventional Novolak/diazonaphthoquinone resist is used to reduce cost, then ease of manufacture is improved, but manufacturing precision deteriorates due to sloped profiles in thick films
Solution Approach 1:
The patent creates a composite resist system combining Novolak resin with low activation energy protecting groups and diazonaphthoquinone photoacid generator. This composite material achieves both cost-effectiveness from Novolak and improved profile quality from the optimized chemical system, resolving the contradiction.
4Manufacturing precision
If post-exposure bake step is added to remove high activation energy protecting groups, then manufacturing precision is improved, but loss of time increases
Solution Approach 1:
The patent changes the activation energy parameter from high to low, which fundamentally alters the kinetics of protecting group cleavage. This enables complete deprotection to occur during exposure without requiring additional post-exposure bake time, resolving both precision and time loss issues.
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 hybrid resist composition provides straight wall profiles in thick films and high resolution in thin films without PAG, enhancing device yield and throughput while avoiding T-topping defects and reducing processing time.
Implementation Method 1
the catalytic acid is formed by photo-decomposition of photo-acid generator (PAG) component
Implementation Method 2
a base soluble resin, usually a phenolic resin or (meth)acrylate resin, is released in areas of the resist exposed to radiation, rendering it aqueous base developable, by an acid catalyzed cleavage of protecting groups on these resins
Data Source
AI summary
A resist composition which has as components a phenolic resin component, a photoactive 2,1,5-diazonaphthoquinonesulfonate component (PAC), a solvent component and that does not contain a photo acid generator (PAG). The PAC is a free PAC, a coupled PAC (PACb) or a combination thereof that includes a substituted or unsubstituted 2,1,5-DNQ material or compound onto which a substituted or unsubstituted 2,1,5-DNQ material is appended that, when UV exposed, do not form sulfonic acid. The phenolic resin component is a Novolak derivative in which some or all the free hydroxy groups are protected with an acid cleavable acetal moiety which can include a PACb moiety. A method whereby this composition is used in either thick or thin film photoresist device manufacturing methodologies.