Semiconductor device and fabrication method thereof

A semiconductor device comprising:

• a first substrate;
• a second substrate facing to the first substrate;
• a shading film between the first substrate and the second substrate;
• a pixel region comprising:
• a first transistor over the first substrate, the first transistor comprising:
• a first semiconductor layer including a first channel formation region and a second channel formation region;
• a first gate electrode and a second gate electrode overlapping with the first channel formation region and the second channel formation region, respectively, with a gate insulating layer interposed therebetween;
• and
• one of a source electrode and a drain electrode connected to the first semiconductor layer;
• a second transistor over the first substrate;
• a first spacer overlapping with a third channel formation region of a second semiconductor layer of the second transistor;
• and
• a second spacer overlapping with the first semiconductor layer of the first transistor,
• wherein the first transistor is a top gate transistor,
• wherein a width of the shading film is greater than a width of the second spacer,
• wherein the shading film overlaps with the first channel formation region,
• wherein a size of the second spacer is different with a size of the first spacer, and
• wherein the second spacer overlaps with the one of the source electrode and the drain electrode.