Solid-State Imaging Device Metal Aperture Wavelength Selection
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Solution Overview
Problem
Conventional solid-state imaging devices face challenges in maintaining high sensitivity and preventing color mixing due to high aspect ratios and optical color mixing caused by thick color filters and increased distances between microlenses and photodiodes in miniature pixel structures.
Innovation Solution
A solid-state imaging device with a metal layer on the light incident plane side that generates a potential gradient to collect signal charges, eliminating the need for color filters and allowing for adjustable wavelength selection, thereby reducing aspect ratios and preventing color mixing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a thick color filter is used to achieve good color separation, then color separation is improved, but the aspect ratio increases and sensitivity decreases
Solution Approach 1:
The patent extracts the color filtering function from the traditional thick color filter and implements it through the aperture shape of the metal layer. The metal layer's aperture acts as a spatial filter that separates wavelengths without requiring thick filtering material, thus achieving color separation while maintaining a low aspect ratio.
Solution Approach 2:
The patent replaces the mechanical/thick-filter approach with an electromagnetic field-based solution. By using the aperture shape and metal layer configuration to create wavelength-dependent light transmission, the system substitutes the need for thick physical filters with a more efficient optical field manipulation approach.
2Measurement precision
If pixel size is reduced to achieve higher resolution, then resolution is improved, but the light receiving area decreases and sensitivity drops
Solution Approach 1:
The patent changes the parameters of the metal layer, specifically the aperture shape and size, to optimize light transmission. By carefully controlling these parameters, the system achieves wavelength-selective transmission that maintains sensitivity even in miniaturized pixels, allowing high resolution without sacrificing light reception capability.
3Device complexity
If the distance between microlens and photodiode is increased due to pixel miniaturization, then pixel integration is improved, but optical color mixing occurs
Solution Approach 1:
The patent introduces the metal layer with its aperture structure as an intermediary between the microlens and photodiode. This intermediary structure filters light by wavelength through its aperture shape, preventing color mixing while allowing the microlens to be positioned at an optimal distance for pixel integration.
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 enhances sensitivity and color separation by allowing for efficient light collection and wavelength selection, reducing optical color mixing and vignetting, and improving aperture ratios without the need for conventional color filters.
Implementation Method 1
a metal layer which is formed on a light incident plane side of the light absorbing layer and has an aperture to transmit, into the light absorbing layer, light of a wavelength range depending on a shape of the aperture; a driver to apply a voltage to the metal layer to generate, in the light absorbing layer, a potential gradient to collect the signal charges
Implementation Method 2
unit pixels having photodiodes are arranged in an array on a silicon semiconductor substrate... a microlens provided above a photodiode collects light from an object and the photodiode receives the collected light
Implementation Method 3
a microlens provided above a photodiode collects light from an object and the photodiode receives the collected light
Implementation Method 4
a color filter is provided between the photodiode of each pixel and a microlens. This color filter transmits only the light of a desired wavelength range among incident light from an object
Data Source
AI summary
A solid-state imaging device according to the present invention includes pixels which are arranged two-dimensionally and each of which includes: a light absorbing layer that converts light into signal charges; a signal read circuit to read out the signal charges, the signal read circuit being formed on a side opposite to a light incident plane side of the light absorbing layer; a metal layer that is formed on the light incident plane side of the light absorbing layer, the metal layer having an aperture to transmit, into the light absorbing layer, light of a wavelength range depending on a shape of the aperture, a driving circuit that applies a voltage to the metal layer to generate, in the light absorbing layer, a potential gradient to collect the signal charges.