Patent ID: 8415731

Claim:
A semiconductor device comprising: a first transistor comprising: a first channel formation region including a first semiconductor material; impurity regions provided with the first channel formation region interposed therebetween; a first gate insulating layer provided over the first channel formation region; a first gate electrode overlapping with the first channel formation region and is provided over the first gate insulating layer; and a first source or drain electrode electrically connected to one of the impurity regions, and a second transistor comprising: a second source electrode; a second drain electrode; a second channel formation region including a second semiconductor material and electrically connected to the second source electrode and the second drain electrode; a second gate insulating layer provided over the second channel formation region; and a second gate electrode overlapping with the second channel formation region and provided over the second gate insulating layer, wherein the first semiconductor material comprises a single crystal semiconductor layer provided over an insulating surface, wherein the second semiconductor material is an oxide semiconductor, wherein the first transistor and the second transistor are provided so that at least part thereof overlap with each other, and wherein one of the second source electrode and the second drain electrode is electrically connected to the first gate electrode.