The present invention relates to a semiconductor device, comprising a semiconductor substrate (102) with a thickness of less than 100 micrometer and with a first substrate side and an opposite second substrate side. A plurality of at least four monolithically integrated Zener or avalanche diodes (164,166,168,170) with a reverse breakdown voltage of less than 20 V are defined in the semiconductor substrate and connected with each other in a series connection. The diodes are defined in a plurality of mutually isolated substrate islands (120,122,124,126) in the semiconductor substrate, at least one diode per substrate island. The substrate islands are laterally surrounded by through-substrate isolations extending from the first to the second substrate side and comprising a filling (128) that electrically isolates a respective substrate island from a respective laterally surrounding area of the semiconductor substrate.