Thin film transistor having laminated source and drain regions
AssigneeSemiconductor Energy Laboratory Co., Ltd.
InventorsShunpei Yamazaki, Jun Koyama, Takeshi Fukunaga
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Abstract
A bottom-gate-type semiconductor device comprising crystalline semiconductor layers, in which the source/drain regions each have a laminate structure comprising a first conductive layer (n+ layer), a second conductive layer(n− layer) of which the resistance is higher than that of the first conductive layer, and an intrinsic or substantially intrinsic semiconductor layer (i-layer) is manufactured. In this, the n− layer functions as an LDD region, and the i-layer functions as an in-plane offset region. The semiconductor device has high reliability and high reproducibility, and is produced in a simple process favorable to mass-production.
Claims34
A semiconductor device comprising a thin film transistor formed over a substrate having an insulating surface, said thin film transistor comprising:
- a semiconductor film having at least a channel-forming region and source and drain regions, each of the source and drain regions has a laminate structure comprising at least a first impurity region, a second impurity region of which a concentration of an impurity is lower that of the first impurity region, and a semiconductor region having the same conductivity as the channel-forming region;
- and
- a gate electrode adjacent to said semiconductor film with a gate insulating film interposed therebetween,
- wherein said conductivity of said semiconductor region is different from that of said second impurity region, and
- wherein said semiconductor regions in said source and drain regions are asymmetry.
A semiconductor device comprising a thin film transistor formed over a substrate having an insulating surface, said thin film transistor comprising:
- a semiconductor film having at least a channel-forming region and source and drain regions, each of the source and drain regions has a laminate structure comprising at least a first impurity region, a second impurity region of which a concentration of an impurity is lower that of the first impurity region, and a semiconductor region having the same conductivity as the channel-forming region;
- and
- a gate electrode adjacent to said semiconductor film with a gate insulating film interposed therebetween,
- wherein said conductivity of said semiconductor region is different from that of said second impurity region, and
- wherein one of said semiconductor regions in said source and drain regions overlaps said gate electrode.
A semiconductor device comprising CMOS circuit having an N-channel TFT and a P-channel TFT formed over a substrate having an insulating surface, each of said N-channel and P-channel thin film transistors comprising:
- a semiconductor film having at least a channel-forming region and source and drain regions, each of the source and drain regions has a laminate structure comprising at least a first impurity region, a second impurity region of which a concentration of an impurity is lower that of the first impurity region, and a semiconductor region having the same conductivity as the channel-forming region;
- and
- a gate electrode adjacent to said semiconductor film with a gate insulating film interposed therebetween,
- wherein said conductivity of said semiconductor region is different from that of said second impurity region.
A semiconductor device comprising a thin film transistor formed over a substrate having an insulating surface, said thin film transistor comprising:
- a semiconductor film having a plurality of channel-forming regions and a plurality of source and drain regions, each of the source and drain regions has a laminate structure comprising at least a first impurity region, a second impurity region of which a concentration of an impurity is lower that of the first impurity region, and a semiconductor region having the same conductivity as the channel-forming region;
- and
- a plurality of gate electrodes adjacent to said semiconductor film with a gate insulating film interposed therebetween,
- wherein said conductivity of said semiconductor region is different from that of said second impurity region.
A semiconductor device comprising a thin film transistor formed over a substrate having an insulating surface, said thin film transistor comprising:
- a semiconductor film having a plurality of channel-forming regions and a plurality of source and drain regions, each of the source and drain regions has a laminate structure comprising at least a first impurity region, a second impurity region of which a concentration of an impurity is lower that of the first impurity region, and a semiconductor region having the same conductivity as the channel-forming region;
- and
- a gate electrode under said semiconductor film with a gate insulating film interposed therebetween,
- wherein said conductivity of said semiconductor region is different from that of said second impurity region, and
- wherein said source and drain regions are asymmetry.
A semiconductor device comprising a thin film transistor formed over a substrate having an insulating surface, said thin film transistor comprising:
- a semiconductor film having a plurality of channel-forming regions and a plurality of source and drain regions, each of the source and drain regions has a laminate structure comprising at least a first impurity region, a second impurity region of which a concentration of an impurity is lower that of the first impurity region, and a semiconductor region having the same conductivity as the channel-forming region;
- and
- a gate electrode under said semiconductor film with a gate insulating film interposed therebetween,
- wherein said conductivity of said semiconductor region is different from that of said second impurity region, and
- wherein one of said source region and said drain region overlaps said gate electrode.
A semiconductor device comprising CMOS circuit having an N-channel TFT and a P-channel TFT formed over a substrate having an insulating surface, each of said Nchannel and P-channel thin film transistors comprising:
- a semiconductor film having a plurality of channel-forming regions and a plurality of source and drain regions, each of the source and drain regions has a laminate structure comprising at least a first impurity region, a second impurity region of which a concentration of an impurity is lower that of the first impurity region, and a semiconductor region having the same conductivity as the channel-forming region;
- and
- a gate electrode under said semiconductor film with a gate insulating film interposed therebetween,
- wherein said conductivity of said semiconductor region is different from that of said second impurity region.
A semiconductor device comprising a thin film transistor formed over a substrate having an insulating surface, said thin film transistor comprising:
- a semiconductor film having a plurality of channel-forming regions and a plurality of source and drain regions, each of the source and drain regions has a laminate structure comprising at least a first impurity region, a second impurity region of which a concentration of an impurity is lower that of the first impurity region, and a semiconductor region having the same conductivity as the channel-forming region;
- and
- a plurality of gate electrodes under said semiconductor film with a gate insulating film interposed therebetween,
- wherein said conductivity of said semiconductor region is different from that of said second impurity region.
Dependencies are inferred from the claim text.