Semiconductor device and method for manufacturing the same

A semiconductor device comprising:

• a transistor comprising a gate electrode, a source electrode, a drain electrode, and a light-transmitting semiconductor film;
• an insulating film having a stacked structure of an oxide insulating film and a nitride insulating film over the oxide insulating film, wherein the insulating film is over the light-transmitting semiconductor film;
• a light-transmitting conductive film on a surface where the light-transmitting semiconductor film is formed, wherein the light-transmitting conductive film is in contact with the nitride insulating film and functions as one of a pair of electrodes of a capacitor;
• a pixel electrode electrically connected to the transistor, wherein the pixel electrode functions as the other of the pair of electrodes of the capacitor;
• a capacitor line on a surface where the gate electrode is formed;
• an electrode on a surface where the pixel electrode is formed;
• and
• a conductive film on a surface where the source electrode or the drain electrode is formed,
• wherein the nitride insulating film functions as a dielectric film of the capacitor,
• wherein the capacitor line is electrically connected to the light-transmitting conductive film through the electrode and the conductive film, and
• wherein the light-transmitting conductive film includes a region whose conductivity is higher than the conductivity of the light-transmitting semiconductor film.

A method for manufacturing a semiconductor device comprising a transistor and a capacitor, comprising the steps of:

• forming a gate electrode of the transistor and a capacitor line;
• forming a first insulating film over the gate electrode and the capacitor line;
• forming, over the first insulating film, a light-transmitting semiconductor film of the transistor and a light-transmitting semiconductor film functioning as one of a pair of electrodes of the capacitor;
• doping the light-transmitting semiconductor film of the capacitor with a dopant to form a light-transmitting conductive film;
• forming a source electrode and a drain electrode over the first insulating film and the light-transmitting semiconductor film of the transistor and forming a conductive film over the first insulating film and the light-transmitting conductive film of the capacitor;
• forming a second insulating film over the first insulating film, the source electrode, the drain electrode, and the conductive film;
• forming a first opening reaching the capacitor line in the first insulating film and the second insulating film and forming a second opening reaching the conductive film in the second insulating film concurrently;
• and
• forming an electrode over the second insulating film and in the first opening and the second opening and forming a pixel electrode overlapping with the light-transmitting conductive film of the capacitor and functioning as the other of the pair of electrodes of the capacitor.

A method for manufacturing a semiconductor device comprising a transistor and a capacitor, comprising the steps of:

• forming a gate electrode of the transistor and a capacitor line;
• forming a first insulating film over the gate electrode and the capacitor line;
• forming, over the first insulating film, a light-transmitting semiconductor film of the transistor and a light-transmitting semiconductor film functioning as one of a pair of electrodes of the capacitor;
• forming a source electrode and a drain electrode over the first insulating film and the light-transmitting semiconductor film of the transistor and forming a conductive film over the first insulating film and the light-transmitting semiconductor film of the capacitor;
• forming a second insulating film over the first insulating film, the source electrode, the drain electrode, and the conductive film;
• processing part of the second insulating film to expose the light-transmitting semiconductor film of the capacitor;
• forming a third insulating film over the second insulating film and the exposed light-transmitting semiconductor film of the capacitor;
• forming a light-transmitting conductive film by dispersion of a component of the third insulating film into the light-transmitting semiconductor film of the capacitor;
• forming a first opening reaching the capacitor line in the first insulating film, the second insulating film, and the third insulating film and forming a second opening reaching the conductive film in the second insulating film and the third insulating film concurrently;
• and
• forming an electrode over the second insulating film and in the first opening and the second opening and forming a pixel electrode overlapping with the light-transmitting conductive film of the capacitor and functioning as the other of the pair of electrodes of the capacitor.