Urea-Modified Photosensitive Polyimide for Copper Relief Patterning
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Solution Overview
Problem
The diversification of package mounting techniques in semiconductor devices has led to issues with resolution deterioration in photosensitive resin compositions and decreased adhesion between copper wiring and polyimide layers due to shifts in focus depth and lower curing temperatures, which are necessary for high-resolution and high-speed applications.
Innovation Solution
A negative photosensitive resin composition is developed, combining a polyimide precursor with a side chain having a urea structure and a photopolymerization initiator, allowing for high-resolution pattern formation on copper wiring with satisfactory adhesion, even at low curing temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the curing temperature is reduced to maintain focus depth for high-resolution patterning, then the resolution is improved, but the imidization rate and adhesion to copper wiring decrease
Solution Approach 1:
The patent introduces a urea structure into the polyimide precursor side chain, which fundamentally changes the chemical composition and thermal properties of the resin. This compositional parameter change enables the material to achieve sufficient imidization and maintain copper adhesion at lower curing temperatures (150-250°C) that are necessary for high-resolution patterning, thus resolving the contradiction between resolution and adhesion
Solution Approach 2:
The patent creates a composite photosensitive resin system by combining the polyimide precursor with the urea structure with a photopolymerization initiator. This composite material approach allows the resin to undergo both photopolymerization for pattern formation and thermal imidization for curing, achieving high resolution and good adhesion simultaneously at reduced temperatures
2Adaptability or versatility
If multiple layers of rewiring are formed on diversified supports, then the adaptability to different mounting techniques is improved, but the focus depth shifts and resolution deteriorates
Solution Approach 1:
The urea-containing polyimide precursor changes the thermal and rheological parameters of the photosensitive resin, enabling it to maintain stable focus depth during exposure even when applied on multiple layers and diversified supports. This allows high-resolution patterning to be achieved regardless of the number of rewiring layers or support type
Solution Approach 2:
The patent develops a universal photosensitive resin composition that can be applied to various mounting techniques (flip-chip, FOWLP, wire bonding) and support types. The resin's improved thermal properties and adhesion characteristics make it universally applicable across different semiconductor packaging applications while maintaining high resolution
3Reliability
If a negative photosensitive resin composition is used to form relief patterns on copper wiring, then the adhesion is improved, but the imidization is insufficient at low curing temperatures
Solution Approach 1:
The introduction of the urea structure into the polyimide precursor fundamentally changes the thermal imidization behavior of the resin. The urea groups facilitate imidization at lower temperatures, enabling the resin to achieve sufficient imidization rate (as evidenced by appropriate color change and solubility changes) at curing temperatures of 150-250°C, thereby resolving the contradiction between adhesion and imidization completeness
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 enables high-resolution relief patterns with improved adhesion to copper wiring, suitable for high-speed semiconductor applications, by ensuring sufficient imidization at low curing temperatures and reducing peeling during the reflow process.
Implementation Method 1
A negative photosensitive resin composition comprising: (A) a polyimide precursor having a structural unit represented by the following general formula (1), and (B) a photopolymerization initiator
Implementation Method 2
those provided in the form of a photosensitive polyimide precursor composition can be used to easily form a heat-resistant relief pattern film by a thermal imidization treatment due to coating, exposure, development and curing of the composition
Data Source
AI summary
Provided are: a negative photosensitive resin composition with which high resolution properties are exhibited when a relief pattern is formed on copper wiring, imidization adequately progresses even when the curing temperature is low, and a cured relief pattern having good adhesion to copper wiring can be manufactured; and a method for manufacturing a cured relief pattern using the negative photosensitive resin composition. This negative photosensitive resin composition contains (A) a polyimide precursor including specific structural units which are represented by general formula (1) and which have a univalent organic group having a urea structure, and (B) a photopolymerization initiator.