Back-Illuminated CMOS Pixel Shielding for Color Mixing Control
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Solution Overview
Problem
Existing solid-state imaging devices struggle to effectively prevent color mixing due to light diffracted or reflected below the inter-pixel light shielding portions, which hinders the achievement of higher-resolution image taking.
Innovation Solution
The proposed imaging element incorporates a photoelectric conversion portion in a semiconductor substrate for each pixel, an element isolation portion to separate adjacent pixels, and an inter-pixel light shielding portion disposed between the semiconductor substrate and the filter layer. The inter-pixel light shielding portion is strategically positioned with a tip end surface width larger than the interval between the light receiving surface and the tip end surface, enhancing light shielding effectiveness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If an inter-pixel light shielding portion is provided between pixels, then color mixing between adjacent pixels is reduced, but light diffraction and reflection below the shielding portion still causes color mixing
Solution Approach 1:
The patent extends the light shielding function from a single horizontal layer to a three-dimensional structure by adding a light shielding portion that protrudes into the semiconductor substrate from the front surface. This vertical extension creates multiple shielding planes that block light paths in different spatial dimensions, preventing both direct and diffracted light from causing color mixing.
Solution Approach 2:
The light shielding portion is nested within the pixel structure by protruding into the semiconductor substrate from the front surface. This nested configuration allows the shielding portion to be integrated into the existing pixel architecture while effectively blocking light paths that would otherwise cause color mixing between adjacent pixels.
2Object-affected harmful factors
If the interval between the light receiving surface and the tip end surface of the inter-pixel light shielding portion is large, then light blocking effectiveness is improved, but the width of the tip end surface must be sufficiently large to maintain structural integrity
Solution Approach 1:
The patent optimizes the dimensional parameters of the light shielding portion by setting the interval between the light receiving surface and the tip end surface to be less than the width of the tip end surface. This parameter relationship ensures that the shielding portion is sufficiently wide to block light effectively while maintaining structural integrity and manufacturability.
3Measurement precision
If higher-resolution image taking is achieved, then image quality is improved, but color mixing due to light diffraction and reflection must be prevented
Solution Approach 1:
The light shielding portion protruding into the semiconductor substrate acts as a preliminary barrier that intercepts and blocks light before it can diffract or reflect and reach adjacent pixels. By preventing the harmful light paths in advance, the patent enables higher-resolution imaging without color mixing interference.
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 configuration significantly reduces color mixing by effectively attenuating light that could otherwise leak between pixels, thereby enabling higher-resolution image capture.
Implementation Method 1
an inter-pixel light shielding portion that is disposed between the pixels in a layer that is provided between the semiconductor substrate and the filter layer so as to be separated from a light receiving surface of the semiconductor substrate by a predetermined interval
Implementation Method 2
a photoelectric conversion portion that is provided in a semiconductor substrate for each of pixels and performs photoelectric conversion on light that enters through a filter layer
Data Source
AI summary
The present disclosure relates to an imaging element and an electronic apparatus configured to achieve higher-resolution image taking. The imaging element includes: a photoelectric conversion portion provided in a semiconductor substrate for each pixel that performs photoelectric conversion on light that enters through a filter layer; an element isolation portion configured to separate the photoelectric conversion portions of adjacent pixels; and an inter-pixel light shielding portion disposed between the pixels in a layer and provided between the semiconductor substrate and the filter layer and separated from a light receiving surface of the semiconductor substrate by a predetermined interval. Moreover, an interval between the light receiving surface of the semiconductor substrate and a tip end surface of the inter-pixel light shielding portion is smaller than a width of the tip end surface of the inter-pixel light shielding portion. The present technology is applicable to back-illuminated CMOS image sensors, for example.