Solid-State Imaging Reflection Film for Near-Infrared Sensitivity
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Solution Overview
Problem
Existing solid-state imaging devices face challenges in improving sensitivity to near-infrared wavelengths while suppressing color mixing, as the use of wiring layers as reflection layers restricts layout and can cause light leakage to adjacent pixels.
Innovation Solution
A reflection design film with higher reflectivity than the wiring layer is formed at the junction between the substrate and wiring layer, reflecting the vertical component of incident light, and is positioned to avoid overlapping with photoelectric conversion units and transistors, enhancing sensitivity without layout restrictions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the wiring layer is used as the reflection layer, then the sensitivity of near-infrared wavelengths is improved, but the wiring layout is restricted and color mixing occurs
Solution Approach 1:
The reflection function is segmented from the wiring layer and assigned to a dedicated reflection layer. This separates the signal processing function (wiring layer) from the optical reflection function (reflection layer), allowing independent optimization of each without mutual interference.
Solution Approach 2:
A dedicated reflection layer is introduced as an intermediary component between the substrate and the wiring layer. This intermediary structure provides the reflection function without requiring the wiring layer to serve dual purposes, thereby eliminating layout restrictions and color mixing issues.
2Measurement precision
If the wiring layer is used as the reflection layer, then the sensitivity of near-infrared wavelengths is improved, but light leaks to adjacent pixels causing color mixing
Solution Approach 1:
The reflection function is segmented from the wiring layer and assigned to a dedicated reflection layer. This separation prevents reflected light from leaking into adjacent pixels, as the reflection layer can be precisely positioned and controlled independently of the wiring layout.
Solution Approach 2:
A dedicated reflection layer acts as an intermediary that controls light reflection precisely. This intermediary structure prevents unwanted light leakage to adjacent pixels while maintaining high sensitivity for the intended photoelectric conversion units.
3Measurement precision
If a reflection layer with high reflectivity is introduced, then the sensitivity is improved, but the device structure becomes more complex
Solution Approach 1:
The reflection layer is merged with the existing substrate structure rather than being added as a completely separate component. It is formed at a specific depth within the substrate, integrating the reflection function into the existing device architecture and minimizing additional structural complexity.
Solution Approach 2:
The substrate serves multiple functions: it provides mechanical support, houses the photoelectric conversion units, and contains the reflection layer for enhancing sensitivity. This multi-functionality reduces the need for additional separate components, thereby limiting the increase in device complexity.
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 improves sensitivity to near-infrared and visible light while minimizing color mixing by effectively reflecting vertical light components and securing wiring integrity, thus optimizing conversion efficiency.
Implementation Method 1
a reflection design film which is formed on a transistor side from at least a junction between the substrate and the wiring layer, which has higher reflectivity than the wiring layer and reflects a vertical component of incident light
Implementation Method 2
a plurality of photoelectric conversion units that photoelectrically convert incident light are formed corresponding to different light wavelengths
Data Source
AI summary
Provided is a solid-state imaging device capable of improving sensitivity of near-infrared wavelengths and suppressing color mixing without being restricted by a wiring layout. A solid-state imaging device includes: a substrate on which a plurality of photoelectric conversion units are formed corresponding to different light wavelengths; a wiring layer including a transistor on a surface opposite to a surface on a light incident side of the substrate and on a photoelectric conversion unit side to execute signal processing on a charge output from the photoelectric conversion unit and a wiring on a side opposite to the photoelectric conversion unit side of the transistor to transfer an electrical signal obtained by the transistor; and a reflection design film on a transistor side from at least a junction between the substrate and the wiring layer, which has higher reflectivity than the wiring layer and reflects a vertical component of incident light.