Solid-State Imaging Waveguide Light Shielding Noise Reduction
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Solution Overview
Problem
Existing solid-state imaging apparatuses face noise issues due to light entering the charge accumulation unit, which is not effectively addressed by the positional relationship between the optical waveguide and light-shielding portions, leading to image distortion and reduced sensitivity.
Innovation Solution
A solid-state imaging apparatus with a specific design where the waveguide guides light into the photoelectric conversion unit, and a light-shielding portion covers the charge accumulation unit with an opening for light output, ensuring the waveguide's output portion is positioned further from the photoelectric conversion unit than the light-shielding portion's lower end, thereby preventing light from entering the charge accumulation unit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the waveguide is positioned close to the photoelectric conversion unit to guide light effectively, then light sensitivity is improved, but light may enter the charge accumulation unit causing noise
Solution Approach 1:
A light-shielding portion is introduced as an intermediary element between the waveguide and the charge accumulation unit. This shielding structure blocks light that leaks from the waveguide before it can enter the charge accumulation unit, thereby preventing noise while maintaining the waveguide's proximity to the photoelectric conversion unit for effective light guidance
Solution Approach 2:
The light-shielding portion is segmented into multiple regions: a first light-shielding portion covering the charge accumulation unit, a second light-shielding portion covering the control electrode, and a third light-shielding portion covering part of the photoelectric conversion unit. This segmentation allows precise control of light paths to different functional regions
2Object-affected harmful factors
If the light-shielding portion covers the charge accumulation unit completely to prevent noise, then noise is reduced, but light from the waveguide cannot reach the photoelectric conversion unit
Solution Approach 1:
The light-shielding portion is designed with spatially varying properties: it provides complete shielding over the charge accumulation unit to prevent noise, while including openings or reduced shielding in regions where light must reach the photoelectric conversion unit. This local differentiation of shielding quality allows simultaneous noise prevention and light guidance
3Productivity
If the waveguide output portion is positioned close to the photoelectric conversion unit for efficient light transfer, then light sensitivity improves, but the risk of light entering the charge accumulation unit increases
Solution Approach 1:
The light-shielding portion acts as a mediator that enables the waveguide output to be positioned close to the photoelectric conversion unit for efficient light transfer, while simultaneously blocking light leakage paths to the charge accumulation unit. The shielding structure creates a controlled light environment that permits high-efficiency light coupling without the harmful side effect
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 enhances light sensitivity by preventing noise in the charge accumulation unit, reducing image distortion, and improving the overall imaging performance by ensuring light is focused on the photoelectric conversion unit while shielding the charge accumulation unit.
Implementation Method 1
a waveguide 31 configured to guide the incident light into the photoelectric conversion unit (1)
Implementation Method 2
a photoelectric conversion unit configured to generate a signal charge by photoelectric conversion of incident light
Data Source
AI summary
Provided is a solid-state imaging apparatus, including pixels each including: a photoelectric conversion unit; a charge accumulation unit; a transistor including a control electrode; a waveguide; and a light-shielding portion. The waveguide includes an incident portion and an output portion, the light-shielding portion includes a first portion that covers the control electrode of the transistor and a second portion that covers a part of the photoelectric conversion unit, the output portion and the photoelectric conversion unit are arranged with an interval therebetween, the interval between the output portion and the photoelectric conversion unit is larger than an interval between a lower end of the second portion of the light-shielding portion and the photoelectric conversion unit, and the interval between the output portion and the photoelectric conversion unit is smaller than an interval between an upper end of the second portion of the light-shielding portion and the photoelectric conversion unit.