In order to build a new concept of photomultiplier based on silicon technology, design and characterization of 5x5 arrays of a new generation of single photon avalanche diodes (SPAD) manufactured by ST-Microelectronics have been performed. Single photons sensitivity, dark noise and timing resolution of the SPAD-STM devices in several experimental conditions have been evaluated. Moreover, the effects arising from the multiple integration of many elements and the study of their common read-out have been deeply investigated.