Semiconductor device and method for manufacturing the same

摘要

A highly reliable semiconductor device and a method for manufacturing the semiconductor device are provided. In a semiconductor device including a bottom-gate transistor in which an insulating layer functioning as a channel protective film is provided over an oxide semiconductor film, elements contained in an etching gas can be prevented from remaining as impurities on a surface of the oxide semiconductor film by performing impurity-removing process after formation of an insulating layer provided over and in contact with the oxide semiconductor film and/or formation of source and drain electrode layers. The impurity concentration in the surface of the oxide semiconductor film is lower than or equal to 5×1018 atoms/cm3, preferably lower than or equal to 1×1018 atoms/cm3.

主权项

1. A method for manufacturing a semiconductor device, comprising the steps of:
forming a gate electrode layer over an insulating surface; forming a gate insulating film over the gate electrode layer; forming an oxide semiconductor film over the gate insulating film; forming an insulating layer over the oxide semiconductor film, the insulating layer overlapping with the gate electrode layer; forming a conductive film over the oxide semiconductor film and the insulating layer; etching the conductive film with an etching gas containing a halogen element to form a source electrode layer and a drain electrode layer; and removing the halogen element from the oxide semiconductor film, wherein a concentration of the halogen element in the oxide semiconductor film subjected to the removing step is lower than or equal to 5×1018 atoms/cm3.