Stacked SPAD Photoelectric Conversion Wiring for Signal Processing
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Solution Overview
Problem
Existing photoelectric conversion apparatuses lack an effective wiring structure for electric connection between substrates, particularly between the second and third substrates, which limits the efficiency and functionality of signal processing and photon detection.
Innovation Solution
A photoelectric conversion apparatus is designed with three substrates: a first substrate containing photoelectric conversion units, a second substrate with pixel circuits, and a third substrate for signal processing, where each substrate has a specific semiconductor layer and wiring structure, with through-hole wiring connecting the substrates to facilitate efficient signal processing and photon detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If three substrates are stacked for photoelectric conversion, signal processing, and storage functions, then functional integration and processing efficiency are improved, but wiring structure complexity and manufacturing difficulty increase
Solution Approach 1:
The patent divides the photoelectric conversion system into three separate substrates: first substrate for photoelectric conversion (SPAD array), second substrate for signal processing (counter circuit), and third substrate for data storage (memory). This segmentation allows each substrate to be optimized independently while maintaining functional integration through controlled connections via through-hole wiring, thereby improving processing efficiency without excessive complexity increase.
Solution Approach 2:
The patent introduces through-hole wiring as an intermediary connection mechanism between substrates. The wiring structure includes conductive plugs penetrating through substrate layers and insulating layers, providing reliable electrical connections while maintaining physical separation between functional modules. This intermediary approach enables efficient signal transmission between stacked substrates without requiring direct complex interconnections.
2Reliability
If through-hole wiring is implemented between substrates, then electrical connection reliability is improved, but manufacturing precision requirements increase
Solution Approach 1:
The patent incorporates insulating layers and protective structures around through-hole wiring before final assembly. The insulating layers are formed beforehand to prevent short circuits and provide mechanical protection to the conductive plugs. This preparatory cushioning approach ensures reliable electrical connections while reducing the sensitivity to alignment variations during manufacturing.
Solution Approach 2:
The through-hole wiring structure uses composite construction combining conductive materials (for electrical connection) and insulating materials (for protection and isolation). This composite approach provides both reliable electrical connectivity and tolerance to manufacturing variations, as the insulating component compensates for minor alignment deviations in the conductive elements.
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 enhances the efficiency of signal processing and photon detection by allowing for improved signal transmission and processing, enabling precise distance measurement and image processing, including three-dimensional distance imaging and machine learning-based processing.
Implementation Method 1
a first substrate that includes a first semiconductor layer and a first wiring structure, the first semiconductor layer including a plurality of photoelectric conversion units
Implementation Method 2
each of the plurality of photoelectric conversion units includes an avalanche diode
Data Source
AI summary
An apparatus includes a first substrate having a plurality of avalanche diodes, a second substrate having a plurality of pixel circuits, and a third substrate having a signal processing circuit. The second substrate and the third substrate are stacked in such a manner that a third wiring structure is provided between two semiconductor layers of the second substrate and the third substrate. The apparatus includes first through-hole wiring going through the semiconductor layer of the third substrate.