Avalanche Diode Wiring Insulator Reflects Light
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Solution Overview
Problem
Current photoelectric conversion apparatuses face challenges in enhancing quantum conversion efficiency due to limitations in elongating the optical path length of incident light, particularly in the design of avalanche diodes within semiconductor layers.
Innovation Solution
The proposed solution involves a photoelectric conversion apparatus with avalanche diodes arranged in a semiconductor layer, featuring specific conductivity types, wiring structures, and insulating films to optimize the optical path length and electric field distribution, including a recess and protrusion structure to reflect light and enhance near-infrared sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a light reflector is provided in the wiring layer to elongate the optical path length, then photoelectric conversion efficiency is improved, but device complexity increases due to additional wiring structures
Solution Approach 1:
The insulating film is designed to serve multiple functions: it provides electrical isolation between the first and second wiring portions, and simultaneously acts as a light reflector to elongate the optical path length. This multi-functionality eliminates the need for separate dedicated reflector structures, thereby improving photoelectric conversion efficiency while avoiding additional device complexity
Solution Approach 2:
The insulating film, which already exists as part of the standard wiring structure, is utilized to provide the light reflection function. Instead of adding a separate component, the existing insulating film is configured to reflect light, making the system self-sufficient and avoiding increased device complexity while still achieving enhanced optical path length
2Productivity
If the optical path length is elongated by extending wiring structures, then quantum conversion efficiency is improved, but manufacturing precision requirements increase
Solution Approach 1:
The insulating film serves dual purposes as both an electrical isolator and a light reflector. Since the insulating film is already part of the standard wiring structure and its position is determined by conventional wiring layout, no additional alignment precision is required. The light reflection function is achieved through the inherent properties and positioning of this existing component, thereby improving quantum conversion efficiency without increasing manufacturing precision requirements
3Reliability
If wiring portions are positioned to overlap semiconductor regions, then electrical connection is improved, but dark count rate increases due to electric field concentration
Solution Approach 1:
The insulating film acts as an intermediary between the first and second wiring portions, providing electrical isolation that prevents direct contact and potential electric field concentration. This intermediary structure allows the wiring portions to be positioned effectively for electrical connection while the insulating film blocks the harmful electric field interaction that would otherwise increase dark count rate
Solution Approach 2:
The electrical isolation function is extracted and provided by the insulating film, separating the electrical connection function from the potential harmful electric field concentration. By taking out the isolation function and assigning it to the insulating film, the wiring portions can maintain good electrical connection while the harmful effect of electric field concentration is eliminated
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 the photoelectric conversion efficiency by elongating the optical path length and reducing dark count rates, while minimizing timing jitter and temporal changes in breakdown voltage.
Implementation Method 1
The optical path length of incident light is elongated by a light reflector provided in the wiring layer reflecting incident light that has passed through the semiconductor substrate
Implementation Method 2
a photoelectric conversion apparatus includes an avalanche diode arranged in a semiconductor layer
Implementation Method 3
an avalanche multiplication region formed between the first semiconductor region and a second semiconductor region
Data Source
AI summary
A photoelectric conversion apparatus includes an avalanche diode arranged in a semiconductor layer having a first surface and a second surface facing the first surface. The avalanche diode includes a first semiconductor region of a first conductivity type, which is arranged at a first depth, a second semiconductor region of a second conductivity type, which is arranged at a second depth deeper than the first depth with respect to the second surface, a third semiconductor region provided in contact with an end of the first semiconductor region in a planar view from the second surface, a first wiring portion connected to the first semiconductor region, and a second wiring portion connected to the second semiconductor region. In a planar view from the second surface, at least part of a boundary between an insulating film and the second wiring portion that faces the first wiring portion overlaps the third semiconductor region and does not overlap the first semiconductor region.