Solid-State Image Pickup Device Noise Reduction via Simultaneous Waveguide Formation
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Solution Overview
Problem
Solid-state image pickup devices face issues due to differences in dark current, parasitic capacitance, and damage extent between light-receiving and light-shielding areas, leading to increased noise between pixels.
Innovation Solution
A solid-state image pickup device design with a semiconductor substrate, photoelectric conversion units, and interconnect layers, where the waveguide members in both areas are formed simultaneously using the same process to ensure uniform structure and reduce noise, and a light-shielding member is used to block light from the second photoelectric conversion unit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If separate processes are used to form optical waveguides in light-receiving and light-shielding areas, then the optical waveguide can be optimized for each area, but the structural difference between areas increases dark current and noise
Solution Approach 1:
The patent combines the formation of optical waveguides in both light-receiving and light-shielding areas into a single simultaneous process step. This ensures identical structural characteristics for waveguides in both areas, eliminating the structural differences that cause dark current variations and noise between pixels.
Solution Approach 2:
The patent creates a universal optical waveguide structure that serves both light-receiving pixels and light-shielding pixels. The same waveguide formation process and identical structural design are applied to both areas, making the waveguide structure universal across different functional regions and preventing noise generation from structural asymmetry.
2Reliability
If different interconnect structures are used in light-receiving and light-shielding areas, then area-specific electrical characteristics can be achieved, but parasitic capacitance differences increase noise
Solution Approach 1:
The patent merges the interconnect structure formation in light-receiving and light-shielding areas into a unified process. Identical interconnect structures are formed simultaneously in both areas, ensuring equal parasitic capacitance values and eliminating noise caused by capacitance differences between pixel types.
3Manufacturing precision
If different manufacturing processes are applied to light-receiving and light-shielding areas, then area-specific optimization is possible, but process-induced damage varies and increases noise
Solution Approach 1:
The patent combines multiple formation steps into unified simultaneous processes. Optical waveguides and interconnect structures are formed in both light-receiving and light-shielding areas during the same manufacturing steps, ensuring identical process conditions and minimizing variations in process-induced damage that could generate noise.
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 approach reduces noise differences between light-receiving and light-shielding areas, enhancing image quality by equalizing the extent of damage and structure between the two regions.
Implementation Method 1
a light-shielding member disposed on an opposite side of the third member from the semiconductor substrate, the light-shielding member being configured to block at least part of light entering the second photoelectric conversion unit
Implementation Method 2
Solid-state image pickup devices have recently been proposed which include an optical waveguide in order to increase the quantity of light incident on a photoelectric conversion unit
Data Source
AI summary
A solid-state image pickup device includes a semiconductor substrate in which photoelectric conversion units are arranged. An insulator is disposed on the semiconductor substrate. The insulator has holes associated with the respective photoelectric conversion units. Members are arranged in the respective holes. A light-shielding member is disposed on the opposite side of one of the members from the semiconductor substrate, such that only the associated photoelectric conversion unit is shielded from light. In the solid-state image pickup device, the holes are simultaneously formed and the members are simultaneously formed.