Oxide semiconductor film, film formation method thereof, and semiconductor device

摘要

An oxide semiconductor film with high crystallinity is formed. An oxide semiconductor film having a single crystal region, which is formed by a sputtering method using a sputtering target including a polycrystalline oxide containing a plurality of crystal grains, is provided. The plurality of crystal grains contained in the sputtering target has a plane that is cleaved or is likely to be cleaved because of a weak crystal bond; therefore, the cleavage planes in the plurality of crystal grains are cleaved when an ion collides with the sputtering target, whereby flat plate-like sputtered particles can be obtained. The obtained flat plate-like sputtered particles are deposited on a deposition surface; accordingly, an oxide semiconductor film is formed. The flat plate-like sputtered particle is formed by separation of part of the crystal grain and therefore the oxide semiconductor film can have high crystallinity.

主权项

1. A semiconductor device comprising:
a gate electrode layer; a first insulating layer over the gate electrode layer; a first oxide semiconductor layer over the first insulating layer; a second oxide semiconductor layer over the first oxide semiconductor layer; a source electrode layer and a drain electrode layer on and in contact with the second oxide semiconductor layer; a third oxide semiconductor layer on and in contact with the second oxide semiconductor layer, the source electrode layer, and the drain electrode layer, wherein at least one of the first, second, and third oxide semiconductor layers comprises a single crystal region having a crystal structure including indium, gallium, and zinc, and wherein the crystal structure of the single crystal region has bonds for forming a hexagonal lattice in an a-b plane of the crystal structure and includes a c-axis perpendicular to a surface of the first insulating layer.