SEMICONDUCTOR DEVICE AND METHOD FOR MANUFACTURING THE SAME
An object is to provide a semiconductor device including an oxide semiconductor with stable electric characteristics can be provided. An insulating layer having many defects typified by dangling bonds is formed over an oxide semiconductor layer with an oxygen-excess mixed region or an oxygen-excess oxide insulating layer interposed therebetween, whereby impurities in the oxide semiconductor layer, such as hydrogen or moisture (a hydrogen atom or a compound including a hydrogen atom such as H 2 O), are moved through the oxygen-excess mixed region or oxygen-excess oxide insulating layer and diffused into the insulating layer. Thus, the impurity concentration of the oxide semiconductor layer is reduced.
1 . (canceled)
2 . A method for manufacturing a semiconductor device, comprising the steps of:
forming a gate electrode layer over a substrate;
forming a gate insulating layer over the gate electrode layer;
providing the substrate into a process chamber under reduced pressure;
introducing a sputtering gas from which hydrogen and moisture are removed while removing moisture remaining in the process chamber to form an oxide semiconductor layer over the gate insulating layer;
forming a source electrode layer and a drain electrode layer over the oxide semiconductor layer;
forming an oxygen-excess oxide insulating layer over the source electrode layer, the drain electrode layer, and the oxide semiconductor layer;
forming an insulating layer having defects over the oxygen-excess oxide insulating layer by a sputtering method; and
heating the substrate to make an impurity included in the oxide semiconductor layer move through the oxygen-excess oxide insulating layer and diffuse into the insulating layer having defects.
3 . The method for manufacturing a semiconductor device according to claim 2 ,
wherein the impurity includes at least one of hydrogen, moisture, hydroxyl, and hydride.
4 . The method for manufacturing a semiconductor device according to claim 2 ,
wherein the process chamber where the oxygen-excess oxide insulating layer and the insulating layer having defects are formed is evacuated with a cryopump to remove remaining moisture.
5 . The method for manufacturing a semiconductor device according to claim 2 , further comprising forming a protective insulating layer over the insulating layer having defects.
6 . A method for manufacturing a semiconductor device, comprising the steps of:
forming a gate electrode layer over a substrate;
forming a gate insulating layer over the gate electrode layer;
providing the substrate into a process chamber under reduced pressure;
introducing a sputtering gas from which hydrogen and moisture are removed while removing moisture remaining in the process chamber to form an oxide semiconductor layer over the gate insulating layer;
forming a source electrode layer and a drain electrode layer over the oxide semiconductor layer;
forming an insulating layer having defects over the oxide semiconductor layer by a sputtering method, whereby forming an oxygen-excess mixed region provided at an interface between the oxide semiconductor layer and the insulating layer; and
heating the substrate to make an impurity included in the oxide semiconductor layer move through the oxygen-excess mixed region and diffuse into the insulating layer having defects.
7 . The method for manufacturing a semiconductor device according to claims 6 ,
wherein the impurity includes at least one of hydrogen, moisture, hydroxyl, and hydride.
8 . The method for manufacturing a semiconductor device according to claim 6 ,
wherein the process chamber where the insulating layer having defects are formed is evacuated with a cryopump to remove remaining moisture.
9 . The method for manufacturing a semiconductor device according to claim 6 , further comprising the step of forming a protective insulating layer over the insulating layer having defects.