Positive Lift-Off Resist Composition for Reverse-Taper Resolution
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Solution Overview
Problem
Existing positive type lift-off resist compositions face challenges such as insufficient resolution, difficulty in forming suitable resist pattern shapes, low sensitivity, inadequate heat resistance, and poor control over solubility and developer dissolution.
Innovation Solution
A positive type lift-off resist composition comprising a polymer (A) with specific repeating units, a photoacid generator (B), and a solvent (C), where the polymer (A) has a c Log P value of 2.76 to 3.35 and includes repeating units represented by formulae (A-1) to (A-4), and the composition optionally contains a dissolution rate modifier (D) represented by formula (D-1).
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If a positive type resist composition is used to form a reverse tapered shape, then the resist pattern shape suitable for lift-off can be formed, but sufficient resolution cannot be obtained
Solution Approach 1:
The patent applies parameter changes by carefully controlling the c Log P value of the polymer within a specific range (2.76 to 3.35) and limiting the dissolution rate modifier content to 0-1.0 mass parts per 100 mass parts of polymer. This precise parameter control enables the positive type resist to form reverse tapered shapes with sufficient resolution, resolving the contradiction between shape formation and resolution.
2Reliability
If a positive type resist composition is used, then the resist pattern can be formed, but the sensitivity of the resist composition is insufficient
Solution Approach 1:
The patent improves sensitivity while maintaining reliable resist pattern formation by optimizing the polymer's c Log P parameter within the range of 2.76 to 3.35 and controlling the dissolution rate modifier content at 0-1.0 mass parts per 100 mass parts of polymer. These parameter optimizations enhance the resist's response to exposure without compromising pattern formation reliability.
3Reliability
If a positive type resist composition is used, then the resist pattern can be formed, but the heat resistance of the resist pattern is insufficient
Solution Approach 1:
The patent enhances heat resistance while maintaining resist pattern formation reliability through parameter optimization. By controlling the polymer's c Log P value within 2.76 to 3.35 and limiting dissolution rate modifier content to 0-1.0 mass parts per 100 mass parts of polymer, the resist pattern achieves improved thermal stability suitable for subsequent processing steps.
4Shape
If a dissolution rate modifier is added to form a reverse tapered shape, then the resist pattern shape can be improved, but the solubility control and developer dissolution become difficult
Solution Approach 1:
The patent simplifies solubility control by strictly limiting the dissolution rate modifier content to 0-1.0 mass parts per 100 mass parts of polymer. This minimal addition, combined with the polymer's optimized c Log P value (2.76 to 3.35), achieves reverse tapered shape formation without creating complex solubility control issues or developer dissolution problems.
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 composition achieves sufficient resolution, forms resist pattern shapes suitable for lift-off, enhances sensitivity, improves heat resistance, and precisely controls solubility and developer dissolution, allowing for effective lift-off processes without the need for dissolution rate modifiers, cross-linking agents, or plasticizers.
Implementation Method 1
a photoacid generator (B)
Data Source
AI summary
A positive type lift-off resist composition includes a polymer (A) having a structure as defined herein and a c Log P of 2.76 to 3.35, a photoacid generator (B) and a solvent (C).