Oxide semiconductor, thin film transistor, and display device
First Claim
1. A thin film transistor comprising:
- a first oxide insulating layer;
an oxide semiconductor as a channel formation region, over the first oxide insulating layer;
a second oxide insulating layer over the oxide semiconductor; and
an insulating layer over the second oxide insulating layer,wherein the insulating layer prevents water vapor of an external environment from entering into the oxide semiconductor,wherein the oxide semiconductor contains hydrogen higher than or equal to 1×
1018/cm3 and lower than or equal to 5×
1020/cm3 and the concentration of hydrogen is higher at an interface of the oxide semiconductor with the first oxide insulating layer than in the inside of the oxide semiconductor, andwherein the oxide semiconductor comprises In, Zn, and M (M is one or a plurality of elements selected from a group consisting of Ga, Fe, Ni, Mn, Co, and Al) as components.
1 Assignment
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Accused Products
Abstract
An object is to control composition and a defect of an oxide semiconductor. Another object is to increase field effect mobility of a thin film transistor and to obtain a sufficient on-off ratio with off current suppressed. The oxide semiconductor is represented by InMO3(ZnO)n (M is one or a plurality of elements selected from Ga, Fe, Ni, Mn, Co, and Al, and n is a non-integer number of greater than or equal to 1 and less than 50) and further contains hydrogen. In this case, the concentration of Zn is made to be lower than the concentrations of In and M (M is one or a plurality of elements selected from Ga, Fe, Ni, Mn, Co, and Al). In addition, the oxide semiconductor has an amorphous structure. Here, n is preferably a non-integer number of greater than or equal to 50, more preferably less than 10.
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Citations
30 Claims
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1. A thin film transistor comprising:
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a first oxide insulating layer; an oxide semiconductor as a channel formation region, over the first oxide insulating layer; a second oxide insulating layer over the oxide semiconductor; and an insulating layer over the second oxide insulating layer, wherein the insulating layer prevents water vapor of an external environment from entering into the oxide semiconductor, wherein the oxide semiconductor contains hydrogen higher than or equal to 1×
1018/cm3 and lower than or equal to 5×
1020/cm3 and the concentration of hydrogen is higher at an interface of the oxide semiconductor with the first oxide insulating layer than in the inside of the oxide semiconductor, andwherein the oxide semiconductor comprises In, Zn, and M (M is one or a plurality of elements selected from a group consisting of Ga, Fe, Ni, Mn, Co, and Al) as components. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 29)
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10. A thin film transistor comprising:
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a gate electrode; a first oxide insulating layer as a gate insulator, over the gate electrode; an oxide semiconductor as a channel formation region, over the first oxide insulating layer; a second oxide insulating layer over the oxide semiconductor; and an insulating layer over the second oxide insulating layer, wherein the insulating layer prevents water vapor of an external environment from entering into the oxide semiconductor, wherein the oxide semiconductor contains hydrogen higher than or equal to 1×
1018/cm3 and lower than or equal to 5×
1020/cm3 and the concentration of hydrogen is higher at an interface of the oxide semiconductor with the first oxide insulating layer than in the inside of the oxide semiconductor, andwherein the oxide semiconductor comprises In, Zn, and M (M is one or a plurality of elements selected from a group consisting of Ga, Fe, Ni, Mn, Co, and Al) as components. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18)
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19. A thin film transistor comprising:
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a source electrode; a drain electrode; a gate electrode; a first oxide insulating layer as a gate insulator, over the gate electrode; an oxide semiconductor as a channel formation region, over the first oxide insulating layer; a second oxide insulating layer over the oxide semiconductor; and an insulating layer over the second oxide insulating layer, wherein the insulating layer prevents water vapor of an external environment from entering into the oxide semiconductor, wherein the oxide semiconductor contains hydrogen higher than or equal to 1×
1018/cm3 and lower than or equal to 5×
1020/cm3 and the concentration of hydrogen is higher at an interface of the oxide semiconductor with the first oxide insulating layer than in the inside of the oxide semiconductor, andwherein the oxide semiconductor comprises In, Zn, and M (M is one or a plurality of elements selected from a group consisting of Ga, Fe, Ni, Mn, Co, and Al) as components. - View Dependent Claims (20, 21, 22, 23, 24, 25, 26, 27, 28, 30)
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Specification