Method for manufacturing semiconductor element and semiconductor device, and deposition apparatus

A method for manufacturing an oxide semiconductor element, comprising the steps of:

• forming a gate electrode over a substrate;
• forming a gate insulating film over the gate electrode;
• forming an oxide semiconductor layer over the gate electrode with the gate insulating film therebetween;
• forming a source electrode and a drain electrode in contact with the oxide semiconductor layer so that end portions of the source electrode and the drain electrode overlap with the gate electrode;
• and
• forming an oxide insulating film covering the oxide semiconductor layer between the source electrode and the drain electrode,
• wherein the substrate is held in a chamber kept in a reduced pressure state,
• wherein moisture remaining in the chamber is removed and a sputtering gas from which hydrogen and moisture are removed is introduced, and
• wherein the oxide semiconductor layer is formed by using a sputtering target in the chamber,
• wherein a filling rate of the sputtering target is greater than or equal to 90%, and
• wherein the sputtering target is heated by a heater in the chamber before the step of forming the oxide semiconductor layer so that hydrogen and carbon contained in the sputtering target are removed.