Monolithic Active Pixel Radiation Detector Shielding
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Solution Overview
Problem
Current semiconductor-based radiation detectors face limitations due to insufficient absorption in thin active layers and degradation from radiation damage, particularly in direct detection methods, which require improved shielding and radiation hardness.
Innovation Solution
A monolithic active pixel radiation detector is developed using a Silicon-on-Insulator (SOI) process with nested wells that collect charge carriers, separate electronics from the sensor portion, and provide shielding, enhancing radiation hardness by reducing charge trapping in the oxide and minimizing electric field interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a thin silicon layer is used for electronics fabrication, then device complexity is reduced and manufacturing is easier, but radiation absorption capability is insufficient
Solution Approach 1:
The patent divides the silicon substrate into multiple functional layers: a thin silicon layer for electronics fabrication and a thick silicon layer for radiation detection. This segmentation allows each layer to be optimized independently - the thin layer enables standard CMOS processing while the thick layer provides sufficient radiation absorption capability.
Solution Approach 2:
The patent transitions from a planar detector design to a three-dimensional stacked architecture by placing the electronics layer above the thick detection layer. This vertical stacking enables the thin electronics layer to benefit from standard fabrication processes while the thick detection layer below provides adequate radiation absorption.
2Device complexity
If electronics are placed close to the sensor portion, then device complexity is reduced, but electric field interference degrades detector performance
Solution Approach 1:
The patent introduces an isolation oxide layer as an intermediary between the electronics and the sensor portion. This oxide layer acts as an electrical barrier that blocks harmful electric field interference and charge carrier leakage from the electronics into the detection region, while still allowing the device to maintain a compact monolithic structure.
Solution Approach 2:
The patent extracts the harmful electric field interference by removing electrical continuity between the electronics and sensor regions through the isolation oxide. This creates an electrical barrier that eliminates charge sharing and field distortion problems while maintaining structural integration.
3Ease of manufacture
If standard CMOS processes are used, then ease of manufacture is improved, but radiation hardness is insufficient due to charge trapping in oxide
Solution Approach 1:
The patent converts the harmful charge trapping effect in the isolation oxide into a beneficial feature by deliberately designing the oxide layer to collect and isolate charges. The isolation oxide, which would normally cause radiation damage, is instead used to create an electrical barrier that protects the electronics from radiation-induced charges while maintaining standard CMOS fabrication compatibility.
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
The nested well structure effectively collects charge carriers, decouples electronics from the sensor region, and improves radiation hardness, allowing for efficient detection in high-energy applications while maintaining compatibility with standard integrated circuit fabrication processes.
Implementation Method 1
the nested wells assist in collecting charge carriers released in interaction with radiation
Implementation Method 2
signals flow through electrically conducting vias established in an isolation oxide on the substrate
Data Source
AI summary
A monolithic active pixel radiation detector including a method of fabricating thereof. The disclosed radiation detector can include a substrate comprising a silicon layer upon which electronics are configured. A plurality of channels can be formed on the silicon layer, wherein the plurality of channels are connected to sources of signals located in a bulk part of the substrate, and wherein the signals flow through electrically conducting vias established in an isolation oxide on the substrate. One or more nested wells can be configured from the substrate, wherein the nested wells assist in collecting charge carriers released in interaction with radiation and wherein the nested wells further separate the electronics from the sensing portion of the detector substrate. The detector can also be configured according to a thick SOA method of fabrication.