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Abstract: With the increasing demand for proton therapy and heavy-ion therapy, 3D sensor technologies with effective detection volumes comparable to cell sizes have become a key research focus. This paper proposes a novel design method for a bowl-shaped 3D sensor and conducts simulation studies on their performance. The device structure designed for proton therapy consists of an array of three bowl-shaped sensors approximately 20 μm in diameter, fabricated on an epitaxial silicon substrate with a 10 μm epitaxial layer and a heavily doped buried layer. The proposed 3D sensor avoids complex deep trench etching processes, offering high feasibility for practical implementation. Each pixel forms its intermediate electrode and edge electrodes through in-situ doping and protective ion implantation at a concentration of 1×1019 cm−3. A guard ring on the surface of each pixel is formed by ion implantation to optimize electric field distribution and prevent premature breakdown.
Electrical properties of the 3D sensor, including potential/electric field distribution, carrier concentration profiles, specific gravity fields, minimum ionizing particle (MIP) response current curves, and extracted rise times/collected charges, are investigated through TCAD simulations. Additionally, a fabrication process is proposed: starting with a substrate comprising a semiconductor base layer, a buried heavy doped layer, and a semiconductor top layer. Wet/dry etching forms spaced bowl-shaped structures. Electrodes and guard rings are then sequentially formed via in-situ and ion implantation doping. This design method lays a solid foundation for future device research in proton therapy, Lidar, and related fields.
Keywords: Novel Bowl-shaped 3D sensor; Electric field; MIP; Collected Charge; Fabrication process
