APD Light Detector Layout Isolation for Flexible Circuit Placement
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing light detectors with avalanche photodiodes lack the flexibility in layout design for peripheral circuits, as they are typically configured with the light receiving portion and peripheral circuit portion on the same semiconductor substrate, limiting the degree of freedom in circuit design and arrangement.
Innovation Solution
A light detector configuration where the light receiving portion with avalanche photodiodes and the peripheral circuit portion are separated by a conductive type separation portion on a semiconductor substrate, allowing for a predetermined interval and independent layout of the peripheral circuit portion relative to the light receiving portion, enabling electrical separation and flexible layout design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the light receiving portion and peripheral circuit portion are formed on the same semiconductor substrate without separation, then the device complexity is reduced and manufacturing is simplified, but the degree of freedom in layout design of the peripheral circuit portion is limited
Solution Approach 1:
The patent divides the semiconductor substrate into distinct regions: a light receiving portion containing avalanche photodiodes and a peripheral circuit portion containing CMOS circuits. These portions are separated by a separation region that extends from the front surface to the back surface of the substrate, creating independent functional zones that can be laid out flexibly while maintaining electrical isolation.
Solution Approach 2:
The patent introduces a separation region as an intermediary structure between the light receiving portion and peripheral circuit portion. This separation region, formed by etching grooves and filling with insulating material, acts as a barrier that provides electrical isolation while allowing both portions to coexist on the same substrate with independent layout flexibility.
2Area of stationary object
If the light receiving portion and peripheral circuit portion are placed close together on the same substrate, then the area is reduced, but electrical interference and field intensity between the portions increase
Solution Approach 1:
The separation region serves as an intermediary barrier between the light receiving portion and peripheral circuit portion. By extending this separation region from the front surface through to the back surface of the substrate and filling it with insulating material, the patent creates effective electrical isolation that prevents field intensity and electrical interference even when the portions are placed close together, thereby reducing the overall substrate area while maintaining electrical stability.
3Reliability
If a separation region is introduced between the light receiving portion and peripheral circuit portion, then electrical separation is improved, but the device complexity and manufacturing difficulty increase
Solution Approach 1:
The separation region is implemented by dividing the substrate into distinct functional zones with clear boundaries. The etching grooves are formed in a systematic pattern, and the insulating material is filled uniformly, creating a segmented structure that provides reliable electrical separation while following a regular manufacturing process that maintains ease of production.
Solution Approach 2:
The separation region serves multiple functions simultaneously: it provides electrical isolation between the light receiving portion and peripheral circuit portion, acts as a physical barrier to prevent signal interference, and creates distinct layout zones that enable independent design optimization. This multi-functionality achieves reliable electrical separation without proportionally increasing manufacturing 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 configuration allows for reliable electrical separation of the light receiving and peripheral circuit portions, reducing field intensity and enabling the layout of peripheral circuits to be freely changed, improving light detection efficiency and sensitivity.
Implementation Method 1
a photodiode configured to multiply a signal charge, which is generated by photoelectric conversion of light having entered a photoelectric conversion layer
Implementation Method 2
multiply a signal charge, which is generated by photoelectric conversion of light having entered a photoelectric conversion layer, by means of avalanche breakdown to enhance light detection sensitivity
Implementation Method 3
a back electrode provided on a second principal surface of the semiconductor substrate facing the first principal surface and configured to apply a predetermined voltage to the semiconductor substrate
Implementation Method 4
a first conductive type first separation portion provided between the light receiving portion and the peripheral circuit portion with a predetermined interval from each of the light receiving portion and the peripheral circuit portion
Data Source
AI summary
A light detector is configured such that a light receiving portion having APDs and a peripheral circuit portion are provided on a first principal surface of a p-type semiconductor substrate, and further includes a back electrode provided on a second principal surface of the semiconductor substrate and a p-type first separation portion provided between the light receiving portion and the peripheral circuit portion. The APD has, on a first principal surface side, an n-type region and a p-epitaxial layer contacting the n-type region in a Z-direction. The peripheral circuit portion has an n-type MISFET provided at a p-well and an n-well provided to surround side and bottom portions of the p-well.