Characterization of the FBK-LGAD devices manufactured at an external foundry for large-volume productions

In recent years, the HEP detector community has shown an increasing interest in Low Gain Avalanche Diodes (LGADs) due to their excellent temporal resolution, good radiation resistance, and low material budget. An example of this is the upcoming CMS Endcap Timing Layer (ETL), a subdetector which will feature four disks (14 m2) covered with these devices. In this context, Fondazione Bruno Kessler (FBK), one of the qualified producers of the ETL LGAD sensors, has recently initiated a technology transfer of the FBK-LGAD technology to an external CMOS foundry (LFoundry) in order to enable a larger and cost-effective production. The first prototype run from LFoundry was produced in May 2024. In order to evaluate the success of the technology transfer, this batch has been assessed against the CMS-ETL detector specifications. The initial characterization focused on the LGADs electrical properties (Leakage current, Breakdown Voltage, Depletion Voltage, Gain, Pad Isolation and Interpad distance). Additionally, a test beam at the H6 CERN hadron beam line allowed us to assess their performance in terms of collected charge and time resolution, while laboratory measurements on neutron-irradiated samples their radiation resistance. The positive results obtained are very promising for the future of large-scale LGAD production.