Phase Detection Pixel Electrode Layout for Higher Light Sensitivity
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Solution Overview
Problem
The existing solid-state imaging devices face limitations in improving light detection sensitivity due to light shielding films and unnecessary charge generation, which also restrict miniaturization, as they require additional mechanisms for charge discharge and result in reduced sensitivity and noise.
Innovation Solution
The design includes a substrate with a pixel array unit comprising normal pixels, phase difference detection pixels, and adjacent pixels, where the lower electrode of the adjacent pixel extends to cover the phase difference detection pixel area, enhancing sensitivity without the need for additional charge discharge mechanisms and allowing for miniaturization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a light shielding film is provided to block light in phase difference detection pixels, then asymmetric sensitivity with respect to incident angle is achieved, but light detection sensitivity is reduced and light incident on the pixel is not sufficiently utilized
Solution Approach 1:
The patent removes the light shielding film from the phase difference detection pixel structure. Instead of blocking light with a film, the invention uses the asymmetric electrode configuration to achieve phase difference detection while allowing full light utilization, thereby resolving the contradiction between detection accuracy and light sensitivity
Solution Approach 2:
The patent merges the functions of light reception and phase difference detection into a single pixel structure without requiring separate light shielding mechanisms. The lower electrode configuration serves both to create asymmetric sensitivity for phase difference detection and to allow full light utilization, combining multiple functions without compromise
2Reliability
If a discharge mechanism is provided to handle unnecessary charge in phase difference detection pixels, then noise generation is avoided, but device area increases and miniaturization is limited
Solution Approach 1:
The patent merges the charge discharge function into the existing lower electrode structure of adjacent pixels. The lower electrode of the adjacent pixel serves dual purposes: as a standard electrode for image generation and as a discharge path for unnecessary charge from phase difference detection pixels, eliminating the need for separate discharge mechanisms and enabling miniaturization
Solution Approach 2:
The lower electrode of the adjacent pixel is designed to perform multiple functions: it acts as a charge collection electrode for normal image generation and simultaneously serves as a discharge path for unnecessary charge generated in phase difference detection pixels. This multi-functionality reduces overall device complexity and area
3Loss of energy
If the lower electrode of adjacent pixel extends to cover phase difference detection pixel area, then light detection sensitivity is improved and miniaturization is enabled, but electrode configuration complexity increases
Solution Approach 1:
The patent segments the lower electrode structure into distinct regions: separate lower electrodes for normal pixels and an extended lower electrode for adjacent pixels that covers both the adjacent pixel area and the phase difference detection pixel area. This segmentation allows each electrode to serve its specific function while maintaining overall system simplicity
Solution Approach 2:
Instead of providing separate discharge mechanisms for each phase difference detection pixel, the invention inverts the approach by using the adjacent pixel's lower electrode to serve the discharge function. This reverse thinking simplifies the overall electrode configuration while achieving the desired functionality
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 improves light detection sensitivity while enabling pixel miniaturization by fully utilizing incident light and avoiding unnecessary charge issues, thus enhancing the accuracy and efficiency of phase difference detection.
Implementation Method 1
each of the normal pixel, the phase difference detection pixel, and the adjacent pixel has a photoelectric conversion film
Data Source
AI summary
Provided is a solid-state imaging device including a substrate having a pixel array unit sectioned into a matrix, a plurality of normal pixels, a plurality of phase difference detection pixels, and a plurality of adjacent pixels adjacent to the phase difference detection pixels, each provided in each of the plurality of sections. Further, each of the normal pixel, the phase difference detection pixel, and the adjacent pixel has a photoelectric conversion film, and an upper electrode and a lower electrode that sandwich the photoelectric conversion film in a thickness direction of the photoelectric conversion film. Furthermore, the lower electrode, in the adjacent pixel, extends from the section in which the adjacent pixel is provided to cover the section in which the phase difference detection pixel adjacent to the adjacent pixel is provided, when viewed from above the substrate.