Photoelectric Conversion Device Light Cut-Off Layer
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Solution Overview
Problem
In solid-state image sensing elements, especially those with a stack-type configuration using a CIGS photoelectric conversion film on a silicon substrate, unnecessary currents are generated due to light passing through gaps, leading to image quality deterioration and challenges in reducing device size, as well as issues with the XY address reading scheme causing image distortion and current leakage during global shutter operations.
Innovation Solution
A photoelectric conversion device is designed with a semiconductor substrate, insulating layers, and planar electrodes within the insulating layer to block light and reduce size, incorporating a row selection circuit and capacitors to manage pixel signals effectively, allowing for a global shutter scheme without current leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a photoelectric conversion film is provided on a silicon substrate with transistors, then photoelectric conversion efficiency is improved, but incident light generates unnecessary current in transistors causing image quality deterioration
Solution Approach 1:
The patent divides the substrate into multiple layers: a first substrate for photoelectric conversion, a light cut-off layer to block stray light, and a second substrate for transistor circuits. This segmentation allows each layer to perform its specific function without interfering with others, solving the contradiction between photoelectric efficiency and image quality.
Solution Approach 2:
The light cut-off layer acts as an intermediary element between the photoelectric conversion film and the transistor substrate. It selectively blocks incident light from reaching transistors while allowing the photoelectric conversion process to proceed efficiently, thus resolving the harmful effect of light-induced current in transistors.
2Object-affected harmful factors
If a light cut-off film is added to prevent light from reaching transistors, then image quality is improved, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The light cut-off layer is designed with uniform optical properties and is integrated into the existing substrate structure. By using materials and fabrication processes consistent with the existing device architecture, the patent minimizes additional complexity while achieving the light blocking function.
Solution Approach 2:
The patent employs composite material structures where the light cut-off layer is formed using materials compatible with existing semiconductor fabrication processes. This approach allows the light blocking function to be added without requiring entirely new manufacturing techniques, thus limiting the increase in device complexity.
3Ease of manufacture
If conventional XY address reading scheme is used, then manufacturing is simpler, but image distortion occurs due to sequential row reading
Solution Approach 1:
The patent implements a global shutter mechanism that performs preliminary exposure for all pixels simultaneously before reading. This preliminary action captures the entire scene at a consistent moment, preventing image distortion even though reading occurs sequentially afterward.
Solution Approach 2:
The reading scheme uses periodic row selection where all rows are exposed during a first period, then read during a second period. This periodic structure allows simultaneous exposure while maintaining sequential reading capability, resolving the contradiction between manufacturing simplicity and image fidelity.
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 prevents image quality deterioration by blocking light, reduces device size, and enables a stable global shutter operation, improving image fidelity and reducing signal variation.
Implementation Method 1
a photoelectric conversion film, which converts received light to charges
Data Source
AI summary
A photoelectric conversion device includes a semiconductor substrate, an insulating layer provided on the semiconductor substrate, an electrode provided on the insulating layer, a photoelectric conversion film provided on the electrode for converting received light to charges, a line connected between the electrode and the semiconductor substrate, a first planar electrode provided in the insulating layer and connected to the electrode, and a second planar electrode provided in the insulating layer between the first planar electrode and the semiconductor substrate.