Semiconductor Device and Method for Manufacturing the Same

A semiconductor device comprising:

• a gate electrode;
• a channel layer arranged in a region directly below or directly above the gate electrode;
• a source electrode and a drain electrode arranged to be in contact with the channel layer;
• and
• a first insulating layer arranged between the gate electrode and the channel layer,
• the channel layer including a first oxide semiconductor, and at least one of the source electrode and the drain electrode including a second oxide semiconductor,
• the first oxide semiconductor and the second oxide semiconductor containing indium, tungsten and zinc,
• a content rate of tungsten to a total of indium, tungsten and zinc in the first oxide semiconductor and the second oxide semiconductor being higher than 0.001 atomic % and not higher than 8.0 atomic %,
• a content rate of zinc to the total of indium, tungsten and zinc in the first oxide semiconductor and the second oxide semiconductor being not lower than 1.2 atomic % and not higher than 40 atomic %,
• an atomic ratio of zinc to tungsten in the first oxide semiconductor and the second oxide semiconductor being higher than 1.0 and lower than 20000.