Silicon Detector 3D Wiring for Rear-Illumination Fill Factor
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Solution Overview
Problem
Conventional optical detectors face performance impairment due to wiring and addressing devices on the front surface, which block light and reduce the useful area for photodetectors, necessitating a design that avoids these obstructions.
Innovation Solution
A three-dimensional structure using dielectrically isolated silicon pathways to connect photodetectors from the top side to the bottom side of a substrate, eliminating the need for front-surface wiring and addressing devices, and incorporating dual-walled insulating regions and conductive shell members for electrical connections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If wiring and addressing devices are provided on the front surface of the die, then electrical connections and addressing can be made, but light is blocked and the useful area for photodetectors is reduced
Solution Approach 1:
The patent moves the wiring and addressing devices from the front surface (2D plane) to the back surface and subsurface layers, utilizing the third dimension (depth) to route connections. This dimensional relocation allows the front surface to be fully dedicated to photodetector elements while wiring is embedded in vertical trenches and back-surface layers, eliminating the trade-off between wiring complexity and useful area.
2Reliability
If wiring and addressing devices are provided on the front surface, then electrical connections can be made, but noise performance deteriorates due to increased interconnect capacitance
Solution Approach 1:
The patent extracts the wiring and addressing devices from the front surface environment and relocates them to the back surface and subsurface. This separation removes the source of interconnect capacitance and associated noise from proximity to the photodetector active regions, thereby improving noise performance while maintaining electrical connectivity functionality.
3Productivity
If conventional front-illumination structure is used, then wiring can be provided, but the fill factor is reduced due to blocked light area
Solution Approach 1:
The patent inverts the conventional architecture by placing photodetectors on the front surface and routing all wiring, addressing, and readout electronics to the back surface. This inversion allows the front surface to achieve maximum fill factor with no blocking structures, while the back surface accommodates all necessary electrical infrastructure, effectively reversing the traditional layout paradigm.
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 reduces interconnect capacitance, improves noise performance, and enhances the fill factor by allowing direct bonding to a carrier substrate, thereby improving the efficiency and effectiveness of photodetectors in rear-illumination applications.
Implementation Method 1
The photodetectors typically generate charge in response to light that illuminates the front surface of the die
Data Source
AI summary
Described is a die having photodetectors provided on a first surface thereof. The die includes an insulative shell member, a conductive shell member and a photodetector conductor. The insulative shell member extends around a periphery of the photodetector receptors and extending through a depth of the semiconductor die. The conductive shell member bridges the insulative shell member and extends through the depth of the semiconductor die. The photodetector conductors are provided on the first surface of the semiconductor die and electrically couple respective photodetectors with a corresponding conductive shell member. Also described is a process for making a semiconductor die and an integrated circuit structure.