Semiconductor apparatus and method of manufacturing the same
It is an object of the present invention to provide a technology of controlling a threshold voltage of a thin film transistor in which an amorphous oxide film is applied to a channel layer. There is provided a semiconductor apparatus including a plurality of kinds of transistors, each of the plurality of kinds of transistors including a channel layer made of an amorphous oxide containing a plurality of kinds of metal elements; and threshold voltages of the plurality of kinds of transistors are different from one another by changing an element ratio of the amorphous oxide.
1. A semiconductor apparatus comprising a plurality of transistors each containing a channel layer with a different composition, wherein:
the channel layer of each of the plurality of transistors is made of an amorphous oxide containing at least two different metal elements;
the amorphous oxide contains In;
an element ratio of the number of atoms of In to the total number of atoms of the metal elements is changed so that respective threshold voltages of the plurality of transistors are different from one another; and
the threshold voltage of each of the plurality of transistors is decreased by increasing the element ratio of the total number of atoms of In to the total number of atoms of the metal elements.
2. A semiconductor apparatus according to claim 1 , wherein:
the amorphous oxide contains at least Ga, In, and Zn.
3. A semiconductor apparatus according to claim 1 , wherein:
the plurality of transistors is arranged in rows and columns on a substrate;
the plurality of transistors each include a gate electrode, gate electrodes of the transistors being connected to one another via a common wiring; and
the element ratio of the number of atoms of In to the total number of atoms of the metal elements is monotonically changed in the row.
4. A semiconductor apparatus according to claim 1 , wherein:
the plurality of transistors is arranged in rows and columns in a matrix form on a substrate;
the plurality of transistors each include a gate electrode, gate electrodes of the transistors disposed in each column being connected to one another via a common wiring; and
the element ratio of the number of atoms of In to the total number of atoms of the metal elements is monotonically changed in the column.
5. A semiconductor apparatus according to claim 1 , wherein:
the channel layer contains at least one element selected from the group of Ga and Zn; and
the element ratio of the number of atoms of In to the total number of atoms of the metal elements is In/(In+Ga+Zn), In/(In+Ga), or In/(In+Zn).