Image Sensor Pixel Layout for Parasitic Light Blocking
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Solution Overview
Problem
Imaging devices face deteriorated parasitic light sensitivity due to leakage, which affects the quality of captured images.
Innovation Solution
An imaging device is designed with a semiconductor substrate featuring a photoelectric conversion section, a charge-holding section, and a light-blocking section extending in the in-plane direction between these sections, along with a light-condensing optical system that focuses incident light on the geometric center of the light-blocking section, preventing parasitic light from entering the charge-holding section.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a light-blocking section is provided between the photoelectric conversion section and the charge-holding section, then parasitic light sensitivity is reduced, but light utilization efficiency deteriorates
Solution Approach 1:
The light-blocking section is positioned to block light only in the specific region where it would cause parasitic sensitivity (between the photoelectric conversion section and charge-holding section), while allowing light to reach the photoelectric conversion section effectively. This localized blocking approach addresses the harmful light leakage without compromising overall light utilization.
Solution Approach 2:
The light-blocking section acts as an intermediary element that selectively intercepts light paths. It serves as a mediator between the photoelectric conversion section and charge-holding section, preventing unwanted light from reaching the charge-holding section while maintaining the functional relationship between other components.
2Object-affected harmful factors
If the light-blocking section is extended in the in-plane direction, then light blocking performance is improved, but device area increases
Solution Approach 1:
The light-blocking section extends primarily in the vertical direction (from the first surface toward the second surface of the semiconductor substrate) rather than occupying large in-plane area. By utilizing the vertical dimension for light blocking, the design achieves effective light blocking performance without significantly increasing the device footprint in the horizontal plane.
Solution Approach 2:
The light-blocking section is segmented into multiple portions: a first light-blocking portion extending from the first surface, and a second light-blocking portion extending from the second surface. These segments work together to block light paths without requiring a single large continuous structure, thereby reducing the overall device area while maintaining blocking effectiveness.
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 effectively reduces noise caused by parasitic light, improving parasitic light sensitivity and oblique incidence characteristics, while allowing for miniaturization and enhanced image-plane phase difference characteristics.
Implementation Method 1
a light-condensing optical system provided on the side of the first surface and condensing incident light on a substantial geometric center of the first light-blocking section in a plan view
Implementation Method 2
a photoelectric conversion section provided on a side of the first surface inside the semiconductor substrate and generating electric charge corresponding to an amount of light reception by photoelectric conversion
Data Source
AI summary
An imaging device of an embodiment of the disclosure includes: a semiconductor substrate in which multiple sensor pixels are arranged in array, the semiconductor substrate having a first surface serving as a light incident surface and a second surface opposed thereto; a photoelectric conversion section provided on a side of the first surface inside the semiconductor substrate and generating electric charge corresponding to a light reception amount by photoelectric conversion; a charge-holding section provided on a side of the second surface inside the semiconductor substrate and holding the electric charge transferred from the photoelectric conversion section; a first light-blocking section extending in an in-plane direction of the semiconductor substrate between the photoelectric conversion section and the charge-holding section; and a light-condensing optical system provided on the side of the first surface and condensing incident light on a substantial geometric center of the first light-blocking section in a plan view.