Resist Composition Acid Diffusion Control
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Solution Overview
Problem
As feature sizes in LSIs continue to shrink, acid diffusion in chemically amplified resist compositions becomes a significant issue, leading to image blurs and a tradeoff between sensitivity, resolution, and edge roughness, where suppressing acid diffusion reduces sensitivity and contrast.
Innovation Solution
A resist composition featuring a base polymer with repeat units having a sulfonic acid anion bonded to a polymer backbone and a sulfonium cation with specific hydrocarbylcarbonyl or hydrocarbyloxycarbonyl groups, which enhances decomposition efficiency, suppresses acid diffusion, and improves affinity to alkaline developers, resulting in high sensitivity, low acid diffusion, and improved line width roughness (LWR) and critical dimension uniformity (CDU).
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If acid diffusion is suppressed by reducing temperature and/or time of post exposure bake, then resolution is improved, but sensitivity and contrast are drastically reduced
Solution Approach 1:
The patent changes the chemical parameters of the acid generator by introducing a sulfonium salt with specific structural features (phenyldibenzothiophenium cation with ring distortion) that alters the acid diffusion characteristics while maintaining generation efficiency, thereby resolving the tradeoff between resolution and sensitivity
Solution Approach 2:
The patent creates a composite acid generator system combining the sulfonium salt with specific anions (perfluoroalkylsulfonate, trifluoromethanesulfonate, or nonafluorobutanesulfonate) to achieve synergistic effects that simultaneously improve resolution through suppressed acid diffusion and maintain sensitivity through high decomposition efficiency
2Manufacturing precision
If an acid generator capable of generating bulky acid is added to suppress acid diffusion, then resolution is improved, but decomposition efficiency and acid diffusion controlling ability are reduced
Solution Approach 1:
The patent optimizes the molecular structure parameters of the sulfonium salt by introducing ring distortion in the phenyldibenzothiophenium cation, which enhances both the bulkiness for acid diffusion control and the decomposition efficiency through strained ring structure that facilitates photochemical reaction
3Area of moving object
If feature size is reduced, then integration density is improved, but image blurs due to acid diffusion increase
Solution Approach 1:
The patent changes the physical-chemical parameters of the acid generation process by using a sulfonium salt that generates bulkier acid with controlled diffusion, enabling maintaining image sharpness at reduced feature sizes and thus achieving higher integration density without sacrificing patterning quality
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 resist composition achieves high sensitivity, excellent resolution, and a wide process margin with improved LWR and CDU, effectively addressing the challenges of acid diffusion and sensitivity in advanced lithography processes.
Implementation Method 1
use of a base polymer comprising repeat units having a salt structure consisting of a sulfonic acid anion bonded to a polymer backbone and a sulfonium cation having a specific structure having a hydrocarbylcarbonyl group or a hydrocarbyloxycarbonyl group provides high decomposition efficiency by exposure
Implementation Method 2
suppress acid diffusion
Data Source
AI summary
A resist composition comprising a base polymer comprising repeat units having a salt structure consisting of a sulfonic acid anion bonded to a polymer backbone and a sulfonium cation having formula (1).