A mold is for obtaining, on a substrate, an array of carbon nanotubes with a high control of their positioning. The boosted voltage is used as an operational voltage of a driving circuit of the switching element, another sourcedrain region and a substrate gate are connected with each other, and a junction diode between one sourcedrain region and the substrate gate is inversely directed with respect to the boosted voltage which is formed by the bootstrap capacity. The first and second enclosure regions each have an inner surface.