Device and device manufacturing method

A device comprising:

• a vertical semiconductor switch including (i) a gate terminal and a first terminal provided on a first surface of a substrate and (ii) a second terminal provided on a second surface of the substrate, the vertical semiconductor switch being configured to electrically connect or disconnect the first terminal and the second terminal;
• a first insulative film provided on the first surface of the substrate;
• a second insulative film provided on the first surface of the substrate, the second insulative film being in contact with the first insulative film and being entirely thinner than the first insulative film;
• and
• a zener diode formed on the first insulative film and the second insulative film, the zener diode including a first portion that is formed on the first insulative film and connected to the first surface of the substrate and a second portion that is formed on the second insulative film and connected to the gate terminal,
• wherein the first portion includes alternating p-type regions and n-type regions directly on the first insulative film and the second portion includes alternating p-type regions and n-type regions directly on the second insulative film, and
• the second portion of the zener diode is shorter than the first portion of the zener diode.

A device manufacturing method comprising:

• forming a first insulative film on a first surface of a substrate;
• forming a second insulative film on the first surface of the substrate, the second insulative film being entirely thinner than the first insulative film and in contact with the first insulative film;
• forming a vertical semiconductor switch including a first terminal provided on the first surface of the substrate and a second terminal provided on a second surface of the substrate, the vertical semiconductor switch being configured to electrically connect or disconnect the first terminal and the second terminal;
• forming a zener diode on the first insulative film and the second insulative film, the zener diode including a first portion provided on the first insulative film and connected to the first surface of the substrate and a second portion provided on the second insulative film and connected to a gate terminal of the vertical semiconductor switch, the first portion of the zener diode positioned more distant from a first well region to which the first terminal is connected than the second portion of the zener diode is,
• wherein forming the zener diode includes alternately implanting a p-type material and an n-type material into the first portion directly on the first insulative film and alternately implanting a p-type material and an n-type material into the second portion directly on the second insulative film.