Image Sensor Refractive Index Gradient for Light Confinement
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Solution Overview
Problem
The reduction in pixel cell size in image sensing devices leads to energy dispersal of incident light between adjacent pixels, causing malfunctions and reduced sensitivity.
Innovation Solution
Incorporating an electromagnetic wave guiding element with a higher refractive index than the surrounding layers, which focuses light onto the photo-sensing elements without dispersing it into adjacent pixels, and optionally including anti-current leakage and anti-reflection layers to enhance performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the size of pixel cells is reduced, then the photosensitivity of the image sensor is improved, but the energy of incident light disperses into adjacent pixels causing malfunction
Solution Approach 1:
The patent introduces an electromagnetic wave guiding element as an intermediary structure between adjacent pixel cells. This guiding element has a refractive index higher than both the passive layer and color pattern, creating a refractive index difference of at least 0.2. This intermediary structure acts as a barrier that prevents light energy from dispersing into adjacent pixels while allowing the pixel cells to maintain reduced size for improved photosensitivity
Solution Approach 2:
The patent changes the refractive index parameter of the electromagnetic wave guiding element to be higher than the surrounding layers (passive layer and color pattern) by at least 0.2. This parameter change creates optical confinement that prevents light dispersal into adjacent pixels, enabling the pixel cells to be reduced in size without suffering from cross-pixel interference
2Measurement precision
If the size of pixel cells is reduced, then the resolution of the image sensor is improved, but the sensitivity of pixel cells is reduced due to energy dispersal
Solution Approach 1:
The electromagnetic wave guiding element serves as a mediator that confines light energy within each pixel cell. By having a higher refractive index than the surrounding passive layer and color pattern (difference ≥ 0.2), it prevents energy dispersal into adjacent pixels, thereby maintaining sensitivity even as pixel cell size is reduced for improved resolution
Solution Approach 2:
The patent applies local quality by creating regions with different refractive indices - the electromagnetic wave guiding element has a locally higher refractive index compared to the passive layer and color pattern. This local variation in optical properties creates confinement zones that maintain light energy within each pixel cell, preserving sensitivity while enabling higher resolution through smaller pixel dimensions
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
Ensures the functionality and sensitivity of pixel cells even with reduced pixel sizes by preventing light dispersal and refracting, thereby improving image sensing device performance.
Implementation Method 1
An electromagnetic wave guiding element is disposed in at least one of the color pattern and the passive layer, wherein the electromagnetic wave guiding element has a third refractive index, and the third refractive index is greater than the first refractive index or the second refractive index
Data Source
AI summary
An image sensing device includes: a semiconductor substrate with a photo-sensing element; a passive layer disposed over the semiconductor substrate, having a first refractive index; a color pattern disposed over the passive layer, wherein the color pattern aligns to the photo-sensing element and has a color selected from the group consisting of red (R), green (G), blue (B), and white (W), and a second refractive index; and an electromagnetic wave guiding element disposed in at least one of the color pattern and the passive layer, having a third refractive index, and the third refractive index is greater than the first refractive index or the second refractive index, and a first difference between the third refractive index and the first refractive index is at least 0.2, and a second difference between the third refractive index and the second refractive index is at least 0.2.