Polyimide Precursor Resin Composition for Undercut Prevention
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Solution Overview
Problem
Negative-type photosensitive resin compositions used in polyimide precursor resin compositions face challenges with insufficient photocrosslinking at the film bottom layer, leading to defects like 'undercuts' due to inadequate exposure ray absorption, especially when the compositions are thinly coated or have low exposure ray absorbance.
Innovation Solution
A polyimide precursor resin composition is developed, including a PI precursor resin, an exposure ray absorber, and a photopolymerization initiator, where specific light absorption parameters and mass fractions are selected to ensure optimal light absorption and distribution, as determined by the formula 0.7≤(Xp+Xt×α+Xr×D)≤2.2, to prevent defects and enhance resolvability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the film thickness is reduced to achieve higher resolution, then resolvability is improved, but photocrosslinking at the film bottom layer becomes insufficient leading to undercut defects
Solution Approach 1:
A light absorber is introduced as an intermediary substance between the incident light and the PI precursor resin. This light absorber selectively absorbs excess light energy and prevents it from reaching the film bottom layer, thereby preventing undercut defects while maintaining adequate photocrosslinking in the thin film structure.
Solution Approach 2:
The patent modifies the optical parameters of the resin composition by adjusting the light absorber concentration (0.01-5 wt%) and its absorption characteristics. This changes the overall light absorption profile of the film to optimize both resolvability and photocrosslinking completeness simultaneously.
2Reliability
If the light absorber concentration is increased to prevent undercuts, then photocrosslinking completeness is improved, but the resin composition becomes more complex and harder to control
Solution Approach 1:
The patent establishes specific parameter ranges for the light absorber concentration (0.01-5 wt%) and its absorption coefficient (0.01≤Xt≤0.05) to optimize the balance between preventing undercuts and maintaining composition simplicity. These quantified parameters enable precise control during manufacturing.
Solution Approach 2:
The light absorber is strategically positioned and concentrated in specific regions where it is most needed - primarily in the upper portions of the film where excess light energy causes undercutting. This localized approach minimizes overall composition complexity while maximizing defect prevention.
3Reliability
If the exposure dose is increased to ensure sufficient light reaches the film bottom layer, then photocrosslinking completeness is improved, but residue generation at the film bottom layer increases
Solution Approach 1:
The light absorber acts as a mediator that selectively intercepts excess light energy before it can cause unwanted chemical reactions at the film bottom layer. This prevents both undercutting and residue generation while maintaining adequate photocrosslinking in the upper film regions.
Solution Approach 2:
The patent converts the potentially harmful effect of excess light energy (which causes residue and undercutting) into a beneficial function by using the light absorber to selectively absorb this excess energy. The absorbed energy is dissipated harmlessly, preventing defective reactions while maintaining useful photocrosslinking.
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 solution provides a polyimide precursor resin composition with excellent resolvability, a wide range of usable exposure doses, and improved handleability, reducing defects such as undercuts and ensuring optimal pattern formation.
Implementation Method 1
selecting the exposure ray absorber from among materials having an absorbance parameter Xt in the range of 0.01 to 0.05 for the specified type of light
Implementation Method 2
selecting the photopolymerization initiator from among materials having an absorbance parameter Xr in the range of 0 to 0.04 for the specified type of light
Data Source
AI summary
The purpose of the present disclosure is to provide a method for manufacturing a polyimide (PI) precursor resin composition that has excellent resolution performance, a broad range of available exposure and good handling properties. Provided is a method for manufacturing a PI precursor resin composition that comprises a PI precursor resin, an exposure light absorber, a photopolymerization initiator and a solvent. The PI precursor resin is selected from among materials having an absorbance parameter Xp for a light species within a range of 0.001-0.20, the exposure light absorber is selected from among materials having an absorbance parameter Xt for the light species within a range of 0.01-0.05, and the photopolymerization initiator is selected from among materials having an absorbance parameter Xr for the light species within a range of 0-0.04. On the basis of an assumed thickness D of a film that is formed by applying the PI precursor resin composition and desolventing, the addition amount (parts by mass) α of the exposure light absorber and the addition amount (parts by mass) β of the photopolymerization initiator are determined so as to satisfy the formula: 0.7≤(Xp+Xt×α+Xr×β)×D≤2.2.