PURPOSE: To avoid dielectric breakdown at a contact part where a diffused layer is connected to a material wiring provided near a diffused layer connected to an external terminal and improve the breakdown strength of a whole device against a high voltage and facilitate improvement of the reliability of the device by a method wherein the end margin of the diffused layer at the contact part mentioned above is so formed as to be larger than the end margins of the other contact parts.

CONSTITUTION: A metal wiring 2 as an external terminal is provided on a semiconduc tor substrate 1 made of silicon or the like and an N-type diffused layer 3 formed on the main surface of the substrate 1 as a protective resistor is connected to the metal wiring 2 at a contact part 4. A metal wiring 5 connected to a Vcc potential and an N-type diffused layer 6 are provided near the diffused layer 3 and the wiring 5 and the layer 6 are connected together at a contact part 7. At the contact part 4, the end margin 3a of the diffused layer 3 is predetermined to be sufficiently large as with the conventional constitution and, also at the contact part 7, the end margin 6a of the diffused layer 6 is predetermined to be as large as possible. Especially the end margin 6a of the diffused layer 6 is predetermined to have sufficiently larger dimensions then the contact parts in the other parts such as internal circuits.