1. A method of producing a semiconductor device, comprising the steps of: preparing an SOQ (Silicon On Quartz) substrate in which a semiconductor layer is formed on a quartz substrate; forming a plurality of semiconductor device forming regions in the SOQ substrate; forming a crack inspection pattern in the SOQ substrate; inspecting the crack inspection pattern to detect a crack in the crack inspection pattern in a first inspection step; and inspecting the semiconductor device forming regions to detect a crack in the semiconductor device forming regions in a second inspection step when the crack is detected in the crack inspection pattern in the first inspection step.