Silicon Sensor Quality Control for the CMS High Granularity Calorimeter

The CMS collaboration, as part of its HL-LHC upgrade program, is replacing its existing endcap calorimeters with a high-granularity calorimeter (HGCAL). This new design features active silicon and scintillator tiles interleaved with dense absorber plates. Notably, the silicon coverage exceeds 1,000 m² on both sides of the intersection point. The sensors, produced from 8-inch wafers, are divided into hundreds of hexagonal cells measuring between ~0.5 and ~1 cm², resulting in high- or low-density sensors. To characterize these silicon sensors, the ARRAY system has been developed. This compact and modular system features an active switching matrix of 512 input channels and a passive probe card adaptable to various HGCAL sensor geometries. The ARRAY measures currents from 500 pA to 5 A and capacitances ranging from 5 pF to 100 pF, with a precision of 0.2 pF. At TTU, we actively use the ARRAY system for quality control of production silicon sensors intended for the final detector's module production. We discuss the details of the ARRAY probe station, online data analyses, and quality control processes, highlighting the key features of the silicon sensors.