Acid-Labile Resist Polymer for High-Aspect-Ratio Patterning
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Solution Overview
Problem
As LSIs advance toward higher integration and higher processing speed, miniaturization of pattern rule is progressing, and there are demands for a patterning process that prevents pattern collapse and deformation without relying on shrinkage of exposed portions.
Innovation Solution
A patterning process using a resist material containing a polymer with a carboxy group protected by an acid-labile group, forming a resist film, exposing and heating it, and then developing by dry etching, where the polymer includes specific repeating units to enhance etching selectivity and prevent pattern collapse.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If aqueous alkaline development is used, then dissolution contrast is improved, but pattern collapse occurs due to stress during spin-drying
Solution Approach 1:
The patent replaces the mechanical spin-drying process with a thermal drying process using an infrared irradiation device. This substitution eliminates the centrifugal stress that causes pattern collapse while maintaining effective solvent removal through heating and evaporation.
Solution Approach 2:
The patent utilizes phase transition of water from liquid to vapor through infrared heating. The infrared irradiation directly heats the resist film, causing rapid evaporation of the aqueous developer and rinsing liquid, thereby removing capillary stress without mechanical force.
2Manufacturing precision
If acid diffusion is suppressed to improve resolution, then dimensional accuracy is improved, but sensitivity is reduced
Solution Approach 1:
The patent introduces a gradient structure in acid concentration within the resist film. By controlling acid diffusion locally through specific polymer composition and PEB conditions, the patent achieves high dissolution contrast in exposed regions while maintaining overall sensitivity through controlled acid generation throughout the film.
Solution Approach 2:
The patent optimizes the PEB temperature and time parameters to control acid diffusion distance. By carefully selecting PEB conditions (temperature and time), the patent achieves the right balance between sufficient acid-catalyzed deprotection for sensitivity and limited acid diffusion for resolution.
3Object-affected harmful factors
If rinsing liquid surface tension is reduced to prevent pattern collapse, then stress during spin-drying is reduced, but throughput is reduced due to special chamber requirements
Solution Approach 1:
The patent replaces the mechanical spin-drying process with thermal drying using infrared irradiation. This eliminates the need for modified spin-drying chambers or surfactant-containing rinsing liquids, maintaining standard equipment and high throughput while preventing pattern collapse through stress-free drying.
Solution Approach 2:
The patent uses infrared-induced phase transition of water from liquid to vapor for drying. This thermal evaporation process removes the need for mechanical spin-drying and associated capillary stress, enabling pattern collapse prevention without special chamber modifications.
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 process enables the formation of a fine pattern with a high aspect ratio without pattern collapse by enhancing the etching rate difference between exposed and unexposed portions, utilizing the polymer's acid-labile group deprotection and main-chain decomposition.
Implementation Method 1
a carboxy group bonded to a polymer main chain is protected with an acid-labile group; the polymer has one or both of repeating units represented by the following general formulae (a1) and (a2)
Implementation Method 2
utilizing the polymer's acid-labile group deprotection and main-chain decomposition
Data Source
AI summary
The present invention is a patterning process including: providing a resist material containing a polymer in which a carboxy group bonded to a polymer main chain is protected with an acid-labile group; forming a resist film by using the resist material; and subjecting the resist film to exposure and heating, and then to development by dry etching to form a pattern, where the polymer has one or both of repeating units represented by the following general formulae (a1) and (a2). This can provide a patterning process according to which a fine pattern can be formed with a high aspect ratio and without pattern collapse occurring.