SEMICONDUCTOR DEVICE
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Abstract
An object is to provide a semiconductor device having good electrical characteristics. A gate insulating layer having a hydrogen concentration less than 6×1020 atoms/cm3 and a fluorine concentration greater than or equal to 1×1020 atoms/cm3 is used as a gate insulating layer in contact with an oxide semiconductor layer forming a channel region, so that the amount of hydrogen released from the gate insulating layer can be reduced and diffusion of hydrogen into the oxide semiconductor layer can be prevented. Further, hydrogen present in the oxide semiconductor layer can be eliminated with the use of fluorine; thus, the hydrogen content in the oxide semiconductor layer can be reduced. Consequently, the semiconductor device having good electrical characteristics can be provided.
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Citations
16 Claims
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1. (canceled)
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2. A method for manufacturing a semiconductor device comprising the steps of:
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forming a conductive layer over a substrate; forming a first insulating layer using a gas comprising SiH4 over the conductive layer; forming a second insulating layer using a gas comprising SiF4 over the second insulating layer; and forming an oxide semiconductor layer over and in contact with the second insulating layer, wherein a fluorine concentration in a part of the first insulating layer is less than 1×
1020 atoms/cm3, andwherein a hydrogen concentration in a part of the second insulating layer is less than 6×
1020 atoms/cm3 and a fluorine concentration in the part of the second insulating layer is greater than 1×
1021 atoms/cm3. - View Dependent Claims (3, 4, 5, 6, 7, 8)
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9. A method for manufacturing a semiconductor device comprising the steps of:
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forming a first conductive layer over a substrate; forming a first insulating layer using a gas comprising SiH4 over the first conductive layer; forming a second insulating layer using a gas comprising SiF4 over the second insulating layer; forming an oxide semiconductor layer over and in contact with the second insulating layer; forming a second conductive layer over and in contact with the oxide semiconductor layer; and forming a third insulating layer using a gas comprising SiF4 over and in contact with the oxide semiconductor layer and the second conductive layer, wherein a fluorine concentration in a part of the first insulating layer is less than 1×
1020 atoms/cm3,wherein a hydrogen concentration in a part of the second insulating layer is less than 6×
1020 atoms/cm3 and a fluorine concentration in the part of the second insulating layer is greater than or equal to 1×
1020 atoms/cm3, andwherein a hydrogen concentration in a part of the third insulating layer is less than 6×
1020 atoms/cm3 and a fluorine concentration in the part of the third insulating layer is greater than or equal to 1×
1020 atoms/cm3. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16)
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Specification