Inorganic Multilayer Interference Filter for Solid-State Imaging
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Solution Overview
Problem
Conventional solid-state imaging devices experience color-mixing due to oblique light incidence, which cannot be effectively prevented with existing color filters, as reducing film thickness leads to sensitivity reduction and uniformity issues with organic pigment particles.
Innovation Solution
A solid-state imaging device using a multilayer interference filter composed of inorganic materials, disposed within the aperture of a light shielding film, which reduces the distance between the color filter and photoelectric converter, preventing color-mixing and allowing for thinner film thicknesses while maintaining sensitivity and heat resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the film thickness of color filters is reduced to prevent color-mixing from oblique light, then color-mixing is prevented, but sensitivity reduction and color irregularities occur due to non-uniform pigment particle distribution
Solution Approach 1:
The invention changes the material parameter of the color filter from organic pigment particles to inorganic materials (such as silicon oxide, silicon nitride, or titanium oxide). This material substitution enables the color filter to achieve sufficient optical filtering performance at reduced thickness (0.5-2.0 μm) without suffering from pigment particle distribution issues, thereby preventing color-mixing while maintaining sensitivity and color uniformity.
Solution Approach 2:
The invention uses inorganic materials (silicon oxide, silicon nitride, titanium oxide) to form the color filter layer, creating a composite structure that combines the light-blocking properties of these materials with the underlying semiconductor substrate. This composite approach provides both the necessary optical filtering and structural integrity at reduced thickness, eliminating color-mixing without sacrificing reliability.
2Length of stationary object
If the film thickness of color filters is reduced, then the distance between color filter and photoelectric converter is reduced preventing color-mixing, but the color filter becomes impractical due to pigment particle distribution issues
Solution Approach 1:
The invention changes the material composition parameter from organic pigments to inorganic materials, enabling the color filter to be manufactured at practical thicknesses (0.5-2.0 μm) using standard semiconductor fabrication processes. This material change eliminates pigment particle distribution problems while maintaining ease of manufacture through proven inorganic film deposition techniques.
3Ease of manufacture
If conventional organic color filters are used, then color filtering is achieved, but color-mixing occurs due to oblique light paths in thick filters
Solution Approach 1:
The invention changes the material parameter from organic to inorganic, which fundamentally alters the optical properties of the color filter. Inorganic materials provide superior light-blocking performance per unit thickness, allowing the filter to be made thinner (0.5-2.0 μm) while maintaining effective color separation. This eliminates oblique light paths causing color-mixing while preserving ease of manufacture through standard semiconductor processes.
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 effectively prevents color-mixing due to oblique light, reduces device thickness, and simplifies manufacturing by integrating the color filter with semiconductor processes, enhancing sensitivity and cost-effectiveness.
Implementation Method 1
a color filter which is composed of an inorganic material and operable to transmit a specific wavelength component of incident light
Implementation Method 2
a photoelectric converter operable to generate an electrical signal according to a quantity of light transmitted by the color filter
Data Source
AI summary
Photoelectric converters are arranged two-dimensionally in a semiconductor substrate. A planarizing layer, a light shielding film, a further planarizing layer and condenser lenses are formed sequentially on the semiconductor substrate and the photoelectric converters. The light shielding film has apertures at positions corresponding to the photoelectric conversion devices. Multilayer interference filters that transmit either a red, green or blue wavelength component of light are disposed in the apertures.