SoI Monolithic Active Pixel Sensors for Radiation Detection Applications: A Review

Silicon-on-insulator (SoI) monolithic active pixel sensors have been developing fast in recent years. An SoI sensors use a thin low-resistivity upper Si layer for circuit implementation, and a high-resistivity bottom wafer as a sensor, sandwiching a buried oxide layer. These devices can be made very thin, fully depleted, avoiding bump bonding. In addition, they have fine pitch and low capacitance. An SoI pixel is a very attractive technology due to its inherent advantages. An SoI pixel process for monolithic radiation detectors is developed mainly based on Lapis Semiconductor Co. Ltd. 0.2-μm SoI FD-CMOS technology. The multilateral developments for both fundamental properties and dedicated application are progressing simultaneously. There have been many research projects on high-energy physics, space experiments, synchrotron radiation and industrial scan, and so on. Difficulties are unavoidable in the R&D process and many of them are solved by introducing new techniques, process/structure modifications, such as buried p-well, double-SoI, and 3-D vertical integration. This paper provides a review of the SoI sensor development: the theory; features; key issues; process; research; and applications.