According to an aspect of the present invention, there is disclosed a semiconductor device comprising a semiconductor substrate, and a gate insulating film of a P-channel MOS transistor, formed on the semiconductor substrate. Fracture growth orientation in a subterranean region is modeled by a computer system. The height adjustment mechanism is adjustable to place a second stop surface in engagement with the prop so that the cutting deck assembly is prevented from lowering below a second height different from the first height. Each cluster is electrically connected to at least one resistor.