Method for fabricating thin-film semiconductor device and thin-film semiconductor device
View Patent ↗A thin-film semiconductor device) having two thin-film transistors, wherein one of the thin-film transistors includes: a first gate electrode; a first gate insulating film; a first semiconductor film; an intrinsic semiconductor layer; a first contact layer of n-type in contact with and above a portion of the intrinsic semiconductor layer; a first source electrode; and a first drain electrode, and the other of the thin-film transistors includes: a second gate electrode; a second gate insulating film; a second semiconductor film; an intrinsic semiconductor layer; a second contact layer of p-type in contact with portions of sides of the semiconductor film and the intrinsic semiconductor layer; a second source electrode; and a second drain electrode.
1. A thin-film semiconductor device having at least a first thin-film transistor and a second thin-film transistor,
wherein the first thin-film transistor includes:
a first gate electrode;
a first insulating film on the first gate electrode;
a first semiconductor layer which is on the first insulating film and has, as a channel region, a region that is opposite to the first gate electrode with the first insulating film therebetween;
a first contact layer of a first conductivity type in contact with and above at least a portion of the semiconductor layer;
a first source electrode on the first contact layer; and
a first drain electrode opposite to the first source electrode on the first contact layer, and
the second thin-film transistor includes:
a second gate electrode;
a second insulating film on the second gate electrode;
a second semiconductor layer which is on the second insulating film and has, as a channel region, a region that is opposite to the second gate electrode with the second insulating film therebetween;
a second contact layer of a second conductivity type in contact with at least a portion of sides of the semiconductor layer, the second conductivity type being different from the first conductivity type;
a second source electrode on the second contact layer; and
a second drain electrode opposite to the second source electrode on the second contact layer.
2. The thin-film semiconductor device according to claim 1 ,
wherein the first contact layer and the second contact layer have an average grain size smaller than an average grain size of the channel regions.
3. The thin-film semiconductor device according to claim 1 ,
wherein the first thin-film transistor has a first channel protection layer above the first semiconductor layer, and
in the first thin-film transistor, the first channel protection layer has a channel direction length less than a channel direction length of the first semiconductor layer.
4. The thin-film semiconductor device according to claim 1 ,
wherein the second thin-film transistor has a second channel protection layer above the second semiconductor layer, and
in the second thin-film transistor, the second channel protection layer has a channel direction length equal to a channel direction length of the second semiconductor layer.
5. The thin-film semiconductor device according to claim 1 ,
wherein each of the first semiconductor layer and the second semiconductor layer includes a semiconductor film and an intrinsic semiconductor layer that is non-crystalline and formed above the semiconductor film, and
the first conductivity type is an n-type, and the second conductivity type is a p-type.
6. The thin-film semiconductor device according to claim 1 ,
wherein each of the first contact layer and the second contact layer is formed above a corresponding one of the first channel protection layer and the second channel protection layer.
7. The thin-film semiconductor device according to claim 1 ,
wherein the first insulating film and the second insulating film are connected.
8. The thin-film semiconductor device according to claim 1 ,
wherein at least one of the first semiconductor layer and the second semiconductor layer includes:
a semiconductor film; and
an intrinsic semiconductor layer that is non-crystalline and formed between the semiconductor film and a channel protection layer.
9. The thin-film semiconductor device according to claim 8 ,
wherein E cp <E c1 is satisfied, where energy levels at lower edges of conduction bands of the semiconductor film and the intrinsic semiconductor layer are E cp and E c1 , respectively.
10. The thin-film semiconductor device according to claim 8 ,
wherein the intrinsic semiconductor layer includes a first intrinsic semiconductor film formed on the semiconductor film, and a second intrinsic semiconductor film formed on the first intrinsic semiconductor film, and
the first intrinsic semiconductor film and the second intrinsic semiconductor film have different electron affinities.
11. The thin-film semiconductor device according to claim 10 ,
wherein the first intrinsic semiconductor film has a crystallization rate higher than a crystallization rate of the second intrinsic semiconductor film.
12. The thin-film semiconductor device according to claim 10 ,
wherein an energy level E cp at a lower edge of a conduction band of the semiconductor film and an energy level E c1 at a lower edge of a conduction band of the first intrinsic semiconductor film are adjusted to prevent a spike from occurring in a connection part of the semiconductor film and the first intrinsic semiconductor film.