Negative-tone Resist Pattern Formation via Alkali Soluble Base
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Solution Overview
Problem
Current lithography techniques face challenges in forming high-resolution resist patterns, especially for extremely small patterns where optical strength is weak, leading to deteriorated resolution, and the negative-tone developing process is inferior to positive-tone processes in terms of environment, apparatus, and cost.
Innovation Solution
A method is developed to form a negative-tone resist pattern using a resist composition with a base component that exhibits increased solubility in an alkali developing solution, where the exposed portions remain and unexposed portions are dissolved by an alkali developing solution, involving exposure, baking, and alkali development steps to enhance resolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If negative-tone developing process is used, then resist pattern can be formed, but environmental burden and cost increase compared to positive-tone processes
Solution Approach 1:
The patent inverts the conventional negative-tone developing mechanism by using an alkali-soluble base component that remains in exposed portions rather than unexposed portions. This inversion allows the use of environmentally friendly alkali developing solutions instead of harmful organic solvents, thereby reducing environmental burden and cost while maintaining resist pattern formation capability
Solution Approach 2:
The patent changes the chemical parameter of the developing solution from organic solvents to alkali developing solutions, and changes the solubility behavior of the base component from acid-soluble to alkali-soluble. This parameter change enables the use of environmentally friendly alkali solutions while achieving negative-tone development, thus resolving the contradiction between pattern formation capability and environmental burden
2Manufacturing precision
If exposure light wavelength is shortened to improve resolution, then pattern miniaturization is achieved, but optical strength becomes weak in extremely small patterns
Solution Approach 1:
The patent changes the chemical composition parameters of the resist material by incorporating a base component with specific alkali solubility characteristics and acid-base reaction properties. This chemical parameter change enhances the resist's response to exposure, improving optical strength and enabling high-resolution patterning even at short wavelengths where optical strength would otherwise be weak
3Reliability
If base component exhibits increased solubility in alkali developing solution, then negative-tone pattern formation is enabled, but control over dissolution behavior becomes challenging
Solution Approach 1:
The patent introduces an acid component as an intermediary that mediates between the base component and the alkali developing solution. The acid component controls the dissolution behavior by reacting with the base component in unexposed portions, preventing premature dissolution and enabling precise negative-tone pattern formation while simplifying the overall dissolution control mechanism
Solution Approach 2:
The patent applies preliminary action by pre-coating the resist composition containing the base component and acid component onto the substrate before exposure. This preliminary preparation ensures that the acid-base reaction is ready to occur upon exposure, enabling controlled dissolution behavior during subsequent alkali development without requiring complex real-time control mechanisms
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 enables the formation of high-resolution resist patterns with improved optical strength and reduced environmental and cost burdens, effectively addressing the limitations of existing negative-tone developing processes.
Implementation Method 1
a photo-base generator component that generates a base upon exposure
Implementation Method 2
a base component that exhibits increased solubility in an alkali developing solution
Implementation Method 3
the unexposed portions are dissolved by an alkali developing solution
Data Source
AI summary
A method of forming a resist pattern, including forming a resist film on a substrate using a resist composition comprising a base component that exhibits increased solubility in an alkali developing solution and a photo-base generator component; exposing the resist film; baking the exposed resist film, such that, at an exposed portion thereof, the base generated from the photo-base generator component upon the exposure and an acid provided to the resist film are neutralized, and at an unexposed portion of the resist film, the solubility of the base component in an alkali developing solution is increased by the acid provided to the resist film; and subjecting the resist film to alkali development, thereby forming a negative-tone resist pattern in which the unexposed portion of the resist film has been dissolved and removed.