Semiconductor device, method for manufacturing same, and display device

A method of manufacturing a semiconductor device that includes a thin film transistor and a thin film diode on a same substrate, wherein a thickness and surface roughness of a semiconductor layer of the thin film diode are greater than a thickness and surface roughness of a semiconductor layer of the thin film transistor, respectively, the method comprising:

• (a) forming a first film made of a crystalline semiconductor in a first region of the substrate that includes a region in which the thin film diode is to be formed, wherein the first film is not formed in a second region including a region in which the thin film transistor is to be formed;
• (b) forming a second film made of an amorphous semiconductor in the first region and the second region of the substrate;
• (c) crystallizing the second film by radiating laser light over the second film to form a crystalline semiconductor film including the first film and the second film that has been crystallized;
• and
• (d) patterning the crystalline semiconductor film to form a semiconductor layer that becomes an active region of the thin film diode in the first region, and to form a semiconductor layer that becomes an active region of the thin film transistor in the second region.

A display device, comprising:

• a display region having a plurality of display units;
• a frame region disposed around the display region;
• and
• an optical sensor unit including a thin film diode,
• wherein each of the display units includes an electrode and a thin film transistor connected to the electrode,
• wherein the thin film transistor and the thin film diode are formed on a same substrate,
• wherein the thin film transistor comprises a semiconductor layer including a channel region, a source region, and a drain region, a gate insulating film disposed so as to cover the semiconductor layer, and a gate electrode disposed on the gate insulating film,
• wherein the thin film diode comprises a semiconductor layer including at least an n-type region and a p-type region,
• wherein the semiconductor layer of the thin film transistor and the semiconductor layer of the thin film diode are both crystalline semiconductor layers,
• wherein the semiconductor layer of the thin film transistor and the semiconductor layer of the thin film diode include portions formed by crystallizing a same amorphous semiconductor film,
• wherein a thickness of the semiconductor layer of the thin film diode is greater than a thickness of the semiconductor layer of the thin film transistor,
• wherein a difference between the thickness of the semiconductor layer of the thin film transistor and the thickness of the semiconductor layer of the thin film diode is greater than 25 nm, and
• wherein surface roughness of the semiconductor layer of the thin film diode is greater than surface roughness of the semiconductor layer of the thin film transistor.