Semiconductor device, method for manufacturing the same, and electronic device

An electronic appliance comprising:

• a display portion;
• and
• an imaging device comprising a silicon substrate,
• wherein a first portion of the silicon substrate is included in a photoelectric conversion element,
• wherein a second portion of the silicon substrate is included in a transistor,
• wherein a trench of the silicon substrate is adjacent to the photoelectric conversion element,
• wherein a first insulator is provided along a side surface of the trench and a curved bottom surface of the trench,
• wherein a second insulator is provided in the trench with the first insulator therebetween,
• wherein the trench does not penetrate the silicon substrate,
• wherein a depth of the trench is more than half a thickness of the silicon substrate,
• wherein a light-receiving surface of the photoelectric conversion element is provided on a first side of the silicon substrate, the first side being opposite to a second side where the transistor is formed,
• wherein a gate electrode of the transistor is provided over the second portion of the silicon substrate,
• wherein an insulating layer is provided over the gate electrode of the transistor,
• wherein a first wiring and a second wiring are provided over and in contact with the insulating layer,
• wherein the first wiring is electrically connected to one of a source and a drain of the transistor,
• wherein the second wiring is electrically connected to the gate electrode of the transistor, and
• wherein the display portion is configured to show an image taken by the imaging device.