Recent developments in the processing of p-type spiral drift detectors

Recently we have designed and developed various methods of fabricating a new p-type drift detector (PDD), which possesses one-sided hexagonal spiral shaped cathodes around the center anode. We have utilized gettering methods in order to remove detrimental impurities from the critical device-active area and transport them to a different part of the wafer. In this work, we discuss the intrinsic and the extrinsic gettering methods involved in the process. In the intrinsic gettering, we use the magnetic Czochralski silicon material that has a high resistivity (≥2 kΩcm). This material naturally has high oxygen concentration (about 10¹⁸/cm³), and under a high temperature cycling it provides nucleation sites where the impurities can precipitate. In the extrinsic process we utilize the phosphorus implantation to form a region with increased impurity solubility. The goal of these processes is to reduce the leakage current of the detector thus improving its energy resolution.