Image Sensor Pixel Edge Geometry for Low-Noise Miniaturization
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Solution Overview
Problem
Highly integrated image sensors with miniaturized pixel sizes face challenges in maintaining stable electrical characteristics and low-luminance resolution, particularly in ensuring noise reduction and optimal voltage levels.
Innovation Solution
The image sensor design incorporates a substrate with a pixel region featuring a unique edge portion structure, including a local round edge with a greater radius of curvature than other edge portions, and a gate electrode configuration with a lateral and vertical gate portion, integrated with a round inner corner, to enhance channel area and limit voltage, thereby improving noise characteristics and electrical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If image sensors are highly integrated and pixel size is reduced, then productivity and integration density are improved, but noise characteristics and electrical stability deteriorate
Solution Approach 1:
The patent applies local quality by creating a local round edge portion with a greater radius of curvature at a specific location on the active region, rather than uniform edge treatment. This localized geometric modification targets the area near the drain region to improve noise characteristics without affecting the entire pixel structure, thus maintaining high integration density while improving electrical stability in critical areas.
Solution Approach 2:
The patent transitions from a two-dimensional planar gate structure to a three-dimensional structure by adding a vertical gate portion that extends along the sidewall of the active region. This dimensional change increases the effective channel area and improves electrical characteristics without increasing the planar footprint, thereby maintaining high integration density while improving reliability.
2Area of stationary object
If pixel size is miniaturized, then integration density is improved, but low-luminance resolution and electrical properties deteriorate
Solution Approach 1:
The patent compensates for reduced pixel area by extending the gate electrode into the vertical dimension along the sidewall of the active region. This creates an additional channel area that improves electrical properties and low-luminance resolution without increasing the planar pixel size, thus maintaining high integration density while improving measurement precision.
Solution Approach 2:
The patent modifies the geometric parameters of the active region by introducing a local round edge portion with a specific radius of curvature. This parameter change optimizes the electric field distribution and carrier transport, improving electrical properties and low-luminance resolution in miniaturized pixels without sacrificing integration density.
3Reliability
If channel area is increased to improve electrical properties, then device complexity increases
Solution Approach 1:
The patent increases channel area by utilizing the vertical sidewall dimension rather than expanding the planar area. The vertical gate portion extends along the sidewall of the active region, creating additional channel length in the vertical dimension. This approach improves electrical properties without requiring more complex multi-layer or three-dimensional stacked structures, thus avoiding excessive device complexity.
Data Source
AI summary
Provided are an image sensor and an electronic system including the same. An image sensor includes a substrate having a pixel region in which an active region is defined, a gate electrode on the active region, and a source region and a drain region formed in the active region on both sides of the gate electrode, wherein the active region includes an edge portion extending along an outline of a top surface thereof, the edge portion including a local round edge portion having a first radius of curvature that is greater than a second radius of curvature of other portions of the edge portion, and a distance from the local round edge portion to the drain region is less than a distance from the local round edge portion to the source region, wherein the gate electrode includes a round inner corner portion facing the local round edge portion.