Evaluation of passive CMOS strip sensors

Silicon sensors will continue to be the central tracking elements for upcoming particle physics detectors. They will have to cover large areas and thus be a main cost driver. The silicon sensors currently used are available only from very few manufacturers, thus detector technologies and designs that can be realized through established commercial industrial production processes and are cost-effective are becoming increasingly relevant. The CMOS technology is one of the important candidates. Since typically CMOS foundries are equipped for producing much smaller sizes than the currently used wafer-scale strip sensors, several neighbouring reticles have to be connected via a stitching process to obtain large sensors. In this study, strip sensors were designed and developed with the passive p-CMOS 150 nm process including stitching of up to five reticles. After initial electrical characterizations the sensors were tested in the laboratory with a 90Sr source and infrared lasers. The key investigation was to evaluate the impact of stitching on the sensor performance. The results presented will demonstrate that the stitching does not show any negative effect on the sensor performance before and after irradiation, and the stitching process is successful.