A semiconductor device is disclosed, which reduces the depth of a metal contact so that an etching margin is increased in forming a contact hole. The output voltage powers at least one electronic component of the electronic system. This provides a compact projection type image display apparatus which can project bright images. More particularly, the dolly is configured to provide a uniform transverse lifting force to a semi-trailer in an area between the rear axles of a semi-trailer and the front of a semi-trailer where a structural failure of the semi-trailer is likely to occur.