Semiconductor device and method for manufacturing the same
A highly reliable semiconductor device and a method for manufacturing the semiconductor device are provided. The semiconductor device is manufactured with a high yield to achieve high productivity. In the manufacture of a semiconductor device including a transistor in which a gate electrode layer, a gate insulating film, and an oxide semiconductor film are sequentially stacked and a source electrode layer and a drain electrode layer are provided in contact with the oxide semiconductor film, the source electrode layer and the drain electrode layer are formed through an etching step and then a step for removing impurities which are generated by the etching step and exist on a surface of the oxide semiconductor film and in the vicinity thereof is performed.
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 island-shaped oxide semiconductor film over the gate electrode layer with the gate insulating film interposed therebetween;
forming a conductive film over the gate insulating film and the island-shaped oxide semiconductor film;
processing the conductive film by plasma treatment using an etching gas containing a halogen element, so that a source electrode layer and a drain electrode layer are formed; and
performing impurity removal treatment on the island-shaped oxide semiconductor film to remove the halogen element contained in the etching gas,
wherein the impurity removal treatment includes oxygen plasma treatment or dinitrogen monoxide plasma treatment, and
wherein a surface of the island-shaped oxide semiconductor film on which the impurity removal treatment has been performed has a halogen concentration lower than or equal to 5×10 18 atoms/cm 3 .
2. The method for manufacturing a semiconductor device according to claim 1 ,
wherein cleaning treatment using a dilute hydrofluoric acid solution is performed as the impurity removal treatment.
3. The method for manufacturing a semiconductor device according to claim 1 ,
wherein, as the impurity removal treatment, oxygen plasma treatment or dinitrogen monoxide plasma treatment is performed and then cleaning treatment using a dilute hydrofluoric acid solution is performed.
4. 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 island-shaped oxide semiconductor film over the gate electrode layer with the gate insulating film interposed therebetween;
forming a conductive film electrically connected to the island-shaped oxide semiconductor film;
processing the conductive film by plasma treatment using an etching gas containing a halogen element, so that a source electrode layer and a drain electrode layer are formed; and
performing impurity removal treatment on the island-shaped oxide semiconductor film to remove the halogen element contained in the etching gas,
wherein the impurity removal treatment includes oxygen plasma treatment or dinitrogen monoxide plasma treatment, and
wherein a surface of the island-shaped oxide semiconductor film on which the impurity removal treatment has been performed has a halogen concentration lower than or equal to 5×10 18 atoms/cm 3 .
5. The method for manufacturing a semiconductor device according to claim 4 ,
wherein cleaning treatment using a dilute hydrofluoric acid solution is performed as the impurity removal treatment.
6. The method for manufacturing a semiconductor device according to claim 4 ,
wherein, as the impurity removal treatment, oxygen plasma treatment or dinitrogen monoxide plasma treatment is performed and then cleaning treatment using a dilute hydrofluoric acid solution is performed.