Abstract: The semiconductor device (11) of the invention comprises a circuit covered by a passivation structure (50). It is provided with a first and a second security element (12A, 12B) which comprise local areas of the passivation structure (50), and with a first and a second electrode (14,15). The security elements (12A, 12B) have a first and a second impedance, respectively, which impedances differ. This is realized in that the passivation structure has an effective dielectric constant that varies laterally over the circuit. Actual values of the impedances are measured by measuring means and transferred to an access device by transferring means. The access device comprises or has access to a central database device for storing the impedances. The access device furthermore may compare the actual values with the stored values of the impedances in order to check the authenticity or the identity of the semiconductor device.

Abstract: The semiconductor device (11) of the invention comprises a circuit that is covered by a passivation structure. It is provided with a first security element (12) that comprises a local area of the passivation structure and which has a first impedance. Preferably, a plurality of security elements (12) is present, whose the impedances differ. The semiconductor device (11) further comprises measuring means (4) for measuring an actual value of the first impedance, and a memory (7) comprising a first memory element (7A) for storing the actual value as a first reference value in the first memory element (7A). The semiconductor device (11) of the invention can be initialized by a method wherein the actual value is stored as the first reference value. Its authenticity can be checked by comparison of the actual value again measured and the first reference value.