Solid-State Image Pickup Device Wavelength Shift Suppression
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Solution Overview
Problem
Conventional image pickup devices face challenges in suppressing transmission wavelength shifts due to the complex design requirements of multilayer film filters, especially in devices with varying incident angles of light, such as small camera modules.
Innovation Solution
A solid-state image pickup device with a multilayer film filter structure comprising layers with different refractive indices, where the effective refractive index of the third layer is adjusted across its surface to gradually increase with the incident angle, using a mixture of dielectrics with different refractive indexes, embedded in a base material, to minimize wavelength shifts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a multilayer film filter is used to control transmission wavelength, then wavelength selectivity is improved, but transmission wavelength shift occurs due to varying incident angles
Solution Approach 1:
The patent applies local quality by creating a position-dependent effective refractive index in the third layer. The ratio of high-refractive-index to low-refractive-index dielectric materials varies across the layer thickness, with the high-refractive-index material concentrated more toward the light incident surface. This gradient structure compensates for incident angle variations locally, maintaining consistent transmission wavelength across different regions of the filter.
2Reliability
If a fine structure with different interference characteristic is added under the multilayer film filter, then transmission wavelength peak shift is suppressed, but the laminated structure becomes complicated
Solution Approach 1:
The patent merges the wavelength stabilization function into the existing third layer of the multilayer film filter by creating a position-dependent effective refractive index through mixed dielectric materials. This eliminates the need for separate fine structures or additional layers, achieving wavelength stability while maintaining structural simplicity.
3Reliability
If the ratio of mixture of two types of dielectrics is adjusted across the surface of the third layer, then effective refractive index varies to suppress wavelength shift, but manufacturing precision requirements increase
Solution Approach 1:
The patent changes the physical parameter of effective refractive index by varying the mixture ratio of two dielectric materials with different refractive indices. By adjusting this material composition parameter across the third layer, the patent achieves wavelength stabilization without requiring complex structural modifications, though it does demand precise control of material mixing ratios during manufacturing.
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
This design effectively suppresses transmission wavelength shifts across different incident angles, allowing for higher image quality capture in smaller camera modules without complex design complications.
Implementation Method 1
it has been considered to use a multilayer film filter capable of steeply transmitting only light having a target wavelength using the optical interference effect of a multilayer film having different dielectric constants
Implementation Method 2
the third layer is formed such that at least two types of dielectrics having different refractive indexes mixedly exist and an effective refractive index is determined according to a ratio of the mixture
Data Source
AI summary
Provided is a solid-state image pickup device and a method of manufacture, and an electronic device capable of suppressing occurrence of a transmission wavelength shift with a simpler design. The solid-state image pickup device includes a multilayer film filter having a laminated structure in which a transmission wavelength adjustment layer is sandwiched between a first multilayer film layer and a second multilayer film layer. The transmission wavelength adjustment layer is formed such that at least two types of dielectrics having different refractive indexes mixedly exist, and an effective refractive index is determined according to a ratio of the mixture. The effective refractive index of the transmission wavelength adjustment layer gradually increases from a chip central portion in which an incident angle of light emitted onto the multilayer film filter is small toward a chip end portion in which the incident angle of light is large.