Light Receiving Element Layout to Block Transistor-Emitted False Signals
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Solution Overview
Problem
The generation of false signals due to near-infrared light emission from amplifier transistors in light receiving elements, particularly those using indium gallium arsenide for near-infrared sensitivity, leads to noise in signal reading circuits.
Innovation Solution
A light receiving element design that includes a metal junction covering the in-pixel transistors, such as amplifier transistors, from the light incident side surface, preventing emitted light from entering the photoelectric conversion layer and thus reducing false signal generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If InGaAs photoelectric conversion layer with high near-infrared sensitivity is used, then light sensitivity is improved, but false signal generation from transistor emitted light increases
Solution Approach 1:
The patent converts the harmful near-infrared light emitted by transistors into a beneficial shielding mechanism by using a metal junction to reflect this light away from the photoelectric conversion layer. The same high sensitivity that causes the problem is leveraged by implementing a reflective barrier that redirects the harmful light, transforming the harmful interaction into a controlled optical path management solution.
Solution Approach 2:
The metal junction serves as an intermediary element between the transistor and the photoelectric conversion layer. It intercepts the near-infrared light emitted by the transistor before it can reach the sensitive InGaAs layer, acting as a mediating structure that prevents direct interaction between the harmful light source and the sensitive detector.
2Adaptability or versatility
If in-pixel transistors are placed on the opposite side of the photoelectric conversion layer, then circuit functionality is improved, but light emission from transistors can enter the photoelectric conversion layer
Solution Approach 1:
The patent addresses the spatial arrangement problem by introducing a new dimensional solution - placing the metal junction at an intermediate position between the transistor and the photoelectric conversion layer. This creates a three-dimensional spatial management system where the metal junction acts as a vertical barrier, effectively separating the light paths and preventing interference while maintaining the beneficial back-illuminated structure.
3Reliability
If metal junction is introduced to cover the in-pixel transistor, then false signal prevention is improved, but device complexity increases
Solution Approach 1:
The metal junction is designed to serve multiple functions simultaneously: it provides electrical connection between layers, acts as a reflective barrier for near-infrared light, and serves as a structural support element. By combining these functions into a single component, the patent achieves false signal prevention without proportionally increasing device complexity, as the metal junction performs multiple roles that would otherwise require separate elements.
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 design effectively prevents the generation of false signals by reflecting emitted light from the transistors, enhancing signal integrity and reducing noise in the light receiving element.
Implementation Method 1
a photoelectric conversion layer that photoelectrically converts incident light
Implementation Method 2
the metal junction reflecting any emitted light away from the photoelectric conversion layer
Data Source
AI summary
Provided are a light receiving element and an electronic apparatus that prevent generation of a false signal due to light emission caused by a circuit. The light receiving element includes a plurality of pixels. Each of the plurality of pixels includes: a photoelectric conversion layer that photoelectrically converts incident light; a signal reading circuit including an in-pixel transistor that is provided on a side opposite to a light incident side surface of the photoelectric conversion layer, amplifies signal charge generated by the photoelectric conversion layer, and reads the signal charge out of a pixel array; and a metal junction that bonds the photoelectric conversion layer and the signal reading circuit. The metal junction covers the in-pixel transistor when viewed from the light incident side surface of the photoelectric conversion layer.