Driver circuit, signal processing unit having the driver circuit, method for manufacturing the signal processing unit, and display device

A display device comprising:

• a substrate;
• a pixel portion over the substrate, the pixel portion including a thin film transistor and a pixel electrode;
• a display element layer over the pixel portion;
• a counter substrate over the display element layer;
• and
• a signal processing unit electrically connected to the pixel portion,
• wherein the signal processing unit comprises a shift register circuit, a switching circuit, and a latch circuit,
• wherein the latch circuit is located over the shift register circuit and the switching circuit, and
• wherein the latch circuit overlaps with the shift register circuit and the switching circuit.

A method for manufacturing a signal processing unit, the method comprising the steps of:

• forming a first semiconductor film over a substrate;
• forming a shift register and a switching circuit using the first semiconductor film;
• forming a second semiconductor film over the shift register and the switching circuit;
• and
• forming a latch circuit using the second semiconductor film.