Silicon Sensor Prototypes for the Phase II Upgrade of the CMS Tracker

The High-Luminosity LHC (HL-LHC) has been identified as the highest priority program in High Energy Physics in the mid-term future. It will provide the experiments an additional integrated luminosity of about 2500 fb$^{−1}$ over 10 years of operation, starting in 2025. In order to meet the experimental challenges of unprecedented p–p luminosity, especially in terms of radiation levels and occupancy, the CMS collaboration will need to replace its entire strip tracker by a new one. In this paper the baseline layout option for this new Phase-II tracker is shown, together with two variants using a tilted barrel geometry or larger modules from 8-inch silicon wafers. Moreover, the two module concepts are discussed, which consist either of two strip sensors (2S) or of one strip and one pixel sensor (PS). These two designs allow $p_{T}$ discrimination at module level enabling the tracker to contribute to the L1 trigger decision. The paper presents testing results of the macro-pixel-light sensor for the PS module and shows the first electrical characterization of unirradiated, full-scale strip sensor prototypes for the 2S module concept, both on 6- and 8-inch wafers.