Design, electrical properties and fabrication method study of a novel 3D-Compound-Shell-Electrode silicon detector

摘要

In this work, a novel three-dimensional (3D) structure of silicon detector: 3D-Compound-Shell-Electrode detector (3DCSED), based on the 3D-Trench-Electrode detector and 3D-Open-Shell-Electrode detector (3DOSED), is proposed. In a 3DCSED, an open trench electrode will be etched about 10% of the detector thickness from the bottom side of the detector to meet the close trench electrode etched about 90% of the detector thickness from the top side. This not only makes the unit structure stable in the fabrication process, but also improves the detection efficiency through the optimization of the electrode structure compared to the conventional 3D-Trench-Electrode detector. In order to optimize the 3DCSED structure, it is important to study 3DCSED's electrical properties by full 3D technology computer-aided design (TCAD) simulations. From the electric field distribution results, detector charge collection efficiency has been simulated and optimized by incorporating charge trapping caused by irradiation. Due to the highly doped trench walls, each pixel cell is electrically isolated to ensure a uniform electric field distribution. However, each pixel cell is physically connected to its neighboring cells, therefore also connected to the Si substrate, through the small portion of broken electrodes in the 3DOSED bulk (about 10% of the detector thickness from the bottom side of the detector). Furthermore, current-voltage (I-V) characteristics and full depletion voltage have been analyzed to study the detector's properties. We also propose a method to fabricate the 3DCSED. In this method, the deep etching is processed by Deep Reacting Ion Etching (DRIE) or laser with respective processing procedures.