Negative Photosensitive Resin for Backside-Illuminated CMOS Sensors
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Solution Overview
Problem
Conventional materials for solid-state image sensing devices face challenges in achieving high refractive index and transparency while maintaining sensitivity, resolution, and solvent resistance, often requiring complex etching processes and suffering from transparency loss or patterning issues.
Innovation Solution
A negative photosensitive resin composition comprising metallic compound particles, a polysiloxane compound, a compound with an α,β-unsaturated carboxylate ester structure, and a photopolymerization initiator, further including a maleimide compound, which allows for high refractive index, transparency, and rectangular cross-section pattern formation without additional post-exposure processes and etching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If inorganic film is deposited by CVD and processed by dry etching, then device sensitivity can be improved, but manufacturing complexity increases and achieving optimal refractive index (1.65 to 2.00) becomes difficult
Solution Approach 1:
The patent replaces the mechanical/physical process of CVD deposition and dry etching with a chemical photoresist process. The resin composition undergoes photo polymerization upon UV irradiation, allowing pattern formation through chemical crosslinking rather than physical deposition and etching, thereby simplifying the manufacturing process while maintaining device sensitivity
Solution Approach 2:
The patent achieves the optimal refractive index range (1.65 to 2.00) by carefully selecting and combining specific resin components including polysiloxane compounds, metallic compound particles, and compounds with unsaturated carboxylate ester structures, adjusting the chemical composition parameters to achieve the desired optical properties
2Temperature
If particles of metallic compounds are added to improve refractive index, then lens optical performance improves, but transparency is lost due to coloring during curing
Solution Approach 1:
The patent creates a composite material system combining metallic compound particles (for high refractive index) with specifically selected resin components that prevent coloring during curing. The resin composition includes compounds with unsaturated carboxylate ester structures and polysiloxane compounds that form a transparent matrix, allowing the metallic particles to enhance refractive index without compromising transparency
Solution Approach 2:
The patent applies different functional components in specific combinations: metallic compound particles are distributed throughout the resin to provide localized refractive index enhancement, while the resin matrix maintains transparency. The maleimide compound is specifically positioned to prevent coloring at critical interfaces during the curing process
3Measurement precision
If negative photosensitive resin composition is used for pattern formation, then resolution and sensitivity improve, but additional post-exposure processes and etching are required
Solution Approach 1:
The patent combines multiple functions into a single photoresist layer: the negative photosensitive resin composition simultaneously provides high-resolution pattern formation, self-etching capability through alkaline aqueous solution solubility, and eliminates the need for separate post-exposure and etching processes. The photo polymerization and development steps consolidate what would otherwise be multiple sequential operations
4Shape
If conventional photoresist materials are used, then pattern formation is achieved, but solvent resistance and transparency cannot be simultaneously maintained
Solution Approach 1:
The patent develops a composite photoresist material where transparent resin components (polysiloxane compounds, compounds with unsaturated carboxylate ester structures) are combined with photopolymerization initiators and maleimide compounds. This composite structure maintains high transparency while achieving complete photo polymerization for excellent solvent resistance and stable pattern formation
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 high sensitivity, resolution, and solvent resistance with simplified production, avoiding wiring deterioration and maintaining transparency and refractive index, enabling efficient light collection and pattern formation.
Implementation Method 1
a photopolymerization initiator, the composition further comprising a compound containing maleimide group
Implementation Method 2
negative photosensitive resin composition which is soluble in an alkaline aqueous solution after being exposed to UV to visible light
Data Source
AI summary
The present invention provides a negative photosensitive resin composition including the following (a) to (d): (a) metallic compound particles, (b) a polysiloxane compound, (c) a compound having at least 1 group containing an α,β-unsaturated carboxylate ester structure, and (d) a photopolymerization initiator, the composition also including (e) a compound containing maleimide group.