Acid-Amplifying Overcoat for Photoselective Antispacer Patterning
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Solution Overview
Problem
Current photoselective antispacer technologies face challenges in generating sufficient acid concentration within an overcoat while minimizing unwanted acid generation in the photoresist mandrel, leading to a narrow process window and potential mandrel dissolution.
Innovation Solution
Incorporating both photo-acid generator (PAG) and acid amplifier (AA) in the overcoat formulation allows for minimal exposure dose to initiate autocatalytic decomposition of AA molecules, generating large quantities of acid for controlled acid diffusion and preventing photoresist mandrel dissolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If conventional photoselective antispacer technology is used to generate acid in the overcoat, then acid concentration can be increased, but unwanted acid generation in the photoresist mandrel occurs leading to mandrel dissolution
Solution Approach 1:
The patent introduces an acid amplifier (AA) as an intermediary substance in the overcoat that converts initially generated acid into additional acid through autocatalytic decomposition. This mediator allows the system to achieve high acid concentration in the overcoat while controlling the timing and location of acid generation, preventing premature mandrel dissolution
Solution Approach 2:
The acid amplifier is pre-installed in the overcoat formulation before exposure. Upon exposure to actinic radiation, the PAG generates initial acid that triggers the preliminary decomposition of AA molecules, creating a reservoir of additional acid that diffuses into the mandrel in a controlled manner, rather than generating all acid at once
2Quantity of substance
If high exposure dose is used to generate sufficient acid in the overcoat, then acid concentration increases, but process window narrows and mandrel dissolution risk increases
Solution Approach 1:
The patent changes the chemical parameters of the overcoat formulation by incorporating an acid amplifier with specific decomposition characteristics. This parameter change allows the system to achieve nonlinear acid generation - a small initial acid input from low-dose exposure triggers a large autocatalytic response from the AA, expanding the process window by decoupling exposure dose from final acid concentration
3Reliability
If minimal exposure dose is used to prevent mandrel dissolution, then mandrel stability is maintained, but insufficient acid is generated for effective antispacer patterning
Solution Approach 1:
The acid amplifier system is self-amplifying through autocatalysis. The initial acid from minimal exposure dose serves the dual purpose of stabilizing the mandrel (by being insufficient to cause dissolution) and simultaneously triggering the AA decomposition that generates the required acid concentration for patterning. The system serves itself by converting a sub-threshold acid input into a supra-threshold acid output through the self-catalytic decomposition of the amplifier
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 approach enables efficient antispacer patterning with low-dose exposure, maximizing acid production in the overcoat and minimizing unwanted reactions in the mandrel, thereby improving the process window and feature resolution.
Implementation Method 1
exposing the first overcoat material to an ultraviolet (UV) irradiation to generate first acid from the PAG
Implementation Method 2
the first acid decomposes the AA to generate second acid, and a total amount of the second acid generated from the decomposition of the AA being greater than a total amount of first acid generated from the PAG
Implementation Method 3
The method includes diffusing the second acid into a portion of the patterned photoresist layer, where the diffused second acid changes a solubility of the portion such that the portion becomes soluble in a developing solution
Data Source
AI summary
An embodiment method of processing a substrate includes the patterning a photoresist layer formed over the substrate using a photolithographic technique, and spin coating a first overcoat material over the patterned photoresist layer, where the first overcoat material includes a photo-acid generator (PAG) and an acid amplifier (AA). The method includes exposing the first overcoat material to an ultraviolet (UV) irradiation to generate first acid from the PAG, where the first acid decomposes the AA to generate second acid, and a total amount of the second acid generated from the decomposition of the AA being greater than a total amount of first acid generated from the PAG. The method includes diffusing the second acid into a portion of the patterned photoresist layer, where the diffused second acid changes a solubility of the portion such that the portion becomes soluble in a developing solution.