Semiconductor device and method for manufacturing the same
AssigneeSemiconductor Energy Laboratory Co., Ltd.
InventorsShunpei Yamazaki, Hidekazu Miyairi, Akiharu Miyanaga, Kengo Akimoto, Kojiro Shiraishi
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Abstract
An embodiment is to include a staggered (top gate structure) thin film transistor in which an oxide semiconductor film containing In, Ga, and Zn is used as a semiconductor layer and a buffer layer is provided between the semiconductor layer and a source and drain electrode layers. The buffer layer having higher carrier concentration than the semiconductor layer is provided intentionally between the source and drain electrode layers and the semiconductor layer, whereby an ohmic contact is formed.
Claims12
A method for manufacturing a semiconductor device, comprising the steps of:
- forming a source electrode layer and a drain electrode layer over a substrate;
- forming a buffer layer having n-type conductivity over the source electrode layer and the drain electrode layer;
- forming a semiconductor layer over the buffer layer;
- forming a gate insulating layer over the semiconductor layer;
- and
- forming a gate electrode layer over the gate insulating layer,
- wherein the semiconductor layer and the buffer layer are formed using oxide semiconductor layers,
- wherein a carrier concentration of the semiconductor layer is lower than 1×1017 atoms/cm3, and a carrier concentration of the buffer layer is 1×1018 atoms/cm3 or higher, and
- wherein each of the source electrode layer and the drain electrode layer is electrically connected to the semiconductor layer with the buffer layer interposed between the source electrode layer or the drain electrode layer and the semiconductor layer.
A method for manufacturing a semiconductor device, comprising the steps of:
- forming a source electrode layer and a drain electrode layer over a substrate;
- forming a buffer layer having n-type conductivity over the source electrode layer and the drain electrode layer;
- forming a semiconductor layer over the buffer layer;
- forming a gate insulating layer over the semiconductor layer;
- and
- forming a gate electrode layer over the gate insulating layer,
- wherein the semiconductor layer and the buffer layer are formed using oxide semiconductor layers,
- wherein a carrier concentration of the semiconductor layer is lower than 1×1017 atoms/cm3, and a carrier concentration of the buffer layer is 1×1018 atoms/cm3 or higher,
- wherein each of the source electrode layer and the drain electrode layer is electrically connected to the semiconductor layer with the buffer layer interposed between the source electrode layer or the drain electrode layer and the semiconductor layer;
- and
- wherein the semiconductor layer, the gate insulating layer, and the gate electrode layer are successively formed without exposure to air.
Dependencies are inferred from the claim text.