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US 6,271,818 B1Granted
Semiconductor device
AssigneeSemiconductor Energy Laboratory Co., Ltd.
InventorsShunpei Yamazaki, Jun Koyama, Hisashi Ohtani
Life of this patent
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Abstract
A systemized active matrix display in which a pixel matrix circuit, a driver circuit and a logic circuit are mounted on the same substrate, is formed. A TFT of the present invention has such characteristics as to be able to operate in a wide driving frequency range of 0.05 to 2 GHz, and by designing a channel length and a film thickness of a gate insulating film of the TFT according to characteristics required by circuits, it is possible to form a high frequency driving circuit and a low frequency driving circuit on the same substrate.
Claims32
An active matrix display comprising:
- a pixel matrix circuit including at least a plurality of source lines, a plurality of gate lines, and a plurality of TFTs;
- a driver circuit including at least a source line driver circuit for driving the source lines and a gate line driver circuit for driving the gate lines;
- and
- a frequency divider circuit operationally connected to the driver circuit,
- wherein the pixel matrix circuit, the driver circuit and the frequency divider circuit are disposed over the same substrate,
- wherein the pixel matrix circuit, the driver circuit, and the frequency divider circuit are constituted by a plurality of TFTs each having a crystalline semiconductor film comprising crystalline silicon as an active layer thereof, and
- wherein one of the TFTs which constitute said frequency divider circuit is operated at a frequency of 0.1 to 0.5 GHz, has a channel length not lower than 0.5 mm and has a gate insulating film having a thickness of not larger than 600 Å, and the active layer in said one of the TFTs contains a metal at a concentration 1×1017 atoms/cm3 or lower.
4 more elements
A semiconductor device comprising:
- a substrate having an insulating surface;
- and
- a circuit operated at a frequency within a range form 0.1 to 0.5 GHz, formed over said substrate, said circuit comprising at least one thin film transistor, wherein said thin film transistor comprises a crystalline semiconductor film including a channel region therein, a gate insulating film adjacent to said crystalline semiconductor film and a gate electrode adjacent to said gate insulating film wherein said crystalline semiconductor film is formed by heating an amorphous semiconductor film together with a crystallization promoting material comprising a metal,
- wherein a thickness of said gate insulating film is not larger than 600 Å and a channel length of said thin film transistor is not smaller than 0.5 mm, and a subthreshold coefficient of the thin film transistor is from 60 to 100 mV/decade,
- wherein said semiconductor film contains said metal at a concentration 1×1017 atoms/cm3 or lower.
2 more elements
A semiconductor device comprising:
- a substrate having an insulating surface;
- and
- a circuit formed over said substrate operated at a frequency of 0.2 GHz or higher, said circuit comprising at least one thin film transistor, wherein said thin film transistor comprises a crystalline semiconductor film including a channel region therein, a gate insulating film adjacent to said crystalline semiconductor film and a gate electrode adjacent to said gate insulating film wherein said crystalline semiconductor film is formed by heating an amorphous semiconductor film with a crystallization promoting material comprising a metal,
- wherein a thickness of said gate insulating film is not larger than 400 Å and a channel length of said thin film transistor is not smaller than 0.1 mm, and a subthreshold coefficient of the thin film transistor is from 60 to 100 mV/decade,
- wherein said semiconductor film contains said metal at a concentration 1×1017 atoms/cm3 or lower.
2 more elements
A semiconductor device comprising:
- a substrate having an insulating surface;
- and
- a circuit operated at a frequency of at least 25 MHz, formed over said substrate, said circuit comprising at least one thin film transistor, wherein said thin film transistor comprises a crystalline semiconductor film including a channel region therein, a gate insulating film adjacent to said crystalline semiconductor film and a gate electrode adjacent to said gate insulating film wherein said crystalline semiconductor film is formed by a method comprising a step of heating an amorphous semiconductor film together with a crystallization promoting material comprising a metal,
- wherein a thickness of said gate insulating film is not smaller than 1000 Å and a channel length of said thin film transistor is not smaller than 1.5 mm, and a subthreshold coefficient of the thin film transistor is from 60 to 100 mV/decade, and
- wherein said semiconductor film contains said metal at a concentration 1×1017 atoms/cm3 or lower.
2 more elements
An active matrix display comprising:
- a pixel matrix circuit including at least a plurality of source lines, a plurality of gate lines, and a plurality of TFTs;
- a driver circuit including at least a source line driver circuit for driving the source lines and a gate line driver circuit for driving the gate lines;
- and
- a frequency divider circuit operationally connected to the driver circuit,
- wherein the pixel matrix circuit, the driver circuit and the frequency driver circuit are disposed over the same substrate,
- wherein the pixel matrix circuit, the driver circuit, and the frequency divider circuit are constituted by a plurality of TFTs each having a crystalline semiconductor film comprising crystalline silicon as an active layer thereof, and
- wherein one of the TFTs which constitute said frequency divider circuit is operated at a frequency of 0.1 to 0.5 GHz, has a channel length not lower than 0.5 mm, and the active layer in said one of the TFTs contains a metal at a concentration 1×1017 atoms/cm3 or lower.
4 more elements
Dependencies are inferred from the claim text.