Nonvolatile semiconductor memory device
First Claim
1. A nonvolatile semiconductor memory device comprising:
- a semiconductor substrate in which a channel formation region is formed between a pair of impurity regions formed with an interval; and
a first insulating layer, a floating gate, a second insulating layer, and a control gate which are provided at a position of an upper layer portion of the semiconductor substrate and about overlapped with the channel formation region,wherein the floating gate is formed of a semiconductor material, and a band gap of the semiconductor material is smaller than a band gap of the channel formation region in the semiconductor substrate.
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Abstract
A nonvolatile semiconductor memory device which is superior in writing and charge holding properties, including a semiconductor substrate in which a channel formation region is formed between a pair of impurity regions formed with an interval, and a first insulating layer, a floating gate, a second insulating layer, and a control gate over an upper layer portion of the semiconductor substrate. It is preferable that a band gap of a semiconductor material forming the floating gate be smaller than that of the semiconductor substrate. For example, it is preferable that the band gap of the semiconductor material forming the floating gate be smaller than that of the channel formation region in the semiconductor substrate by 0.1 eV or more. This is because, by decreasing the bottom energy level of a conduction band of the floating gate electrode to be lower than that of the channel formation region in the semiconductor substrate, carrier injecting and charge holding properties are improved.
74 Citations
36 Claims
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1. A nonvolatile semiconductor memory device comprising:
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a semiconductor substrate in which a channel formation region is formed between a pair of impurity regions formed with an interval; and a first insulating layer, a floating gate, a second insulating layer, and a control gate which are provided at a position of an upper layer portion of the semiconductor substrate and about overlapped with the channel formation region, wherein the floating gate is formed of a semiconductor material, and a band gap of the semiconductor material is smaller than a band gap of the channel formation region in the semiconductor substrate. - View Dependent Claims (11, 17, 27)
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2. A nonvolatile semiconductor memory device comprising:
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a semiconductor substrate in which a channel formation region is formed between a pair of impurity regions formed with an interval; and a first insulating layer, a floating gate, a second insulating layer, and a control gate which are provided at a position of an upper layer portion of the semiconductor substrate and about overlapped with the channel formation region, wherein the floating gate is formed of a material having a higher electron affinity than silicon. - View Dependent Claims (18, 28)
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3. A nonvolatile semiconductor memory device comprising:
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a semiconductor substrate in which a channel formation region is formed between a pair of impurity regions formed with an interval; and a first insulating layer, a floating gate, a second insulating layer, and a control gate which are provided at a position of an upper layer portion of the semiconductor substrate and about overlapped with the channel formation region, wherein a barrier energy with respect to electrons of the floating gate, formed from the first insulating layer is higher than a barrier energy with respect to electrons of the channel formation region in the semiconductor substrate, formed from the first insulating layer. - View Dependent Claims (19, 29)
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4. A nonvolatile semiconductor memory device comprising:
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a semiconductor substrate in which a channel formation region is formed between a pair of impurity regions formed with an interval; and a first insulating layer, a floating gate, a second insulating layer, and a control gate which are provided at a position of an upper layer portion of the semiconductor substrate and about overlapped with the channel formation region, wherein the floating gate is formed of germanium or a germanium compound. - View Dependent Claims (13, 20, 30)
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5. A nonvolatile semiconductor memory device comprising:
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a semiconductor substrate in which a channel formation region is formed between a pair of impurity regions formed with an interval; and a first insulating layer, a floating gate, a second insulating layer, and a control gate which are provided at a position of an upper layer portion of the semiconductor substrate and about overlapped with the channel formation region, wherein the floating gate is formed of germanium or a germanium compound with a thickness of 1 nm or more and 20 nm or less. - View Dependent Claims (14, 21, 31)
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6. A nonvolatile semiconductor memory device comprising:
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a semiconductor substrate in which a channel formation region is formed between a pair of impurity regions formed with an interval; and a first insulating layer, a floating gate, a second insulating layer, and a control gate which are provided at a position of an upper layer portion of the semiconductor substrate and about overlapped with the channel formation region, wherein the first insulating layer is formed of a stacked layer of silicon oxide layer and a silicon nitride layer on a semiconductor substrate side; and wherein the floating gate is formed of a semiconductor material, and a band gap of the semiconductor material is smaller than a band gap of the channel formation region in the semiconductor substrate. - View Dependent Claims (12, 22, 32)
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7. A nonvolatile semiconductor memory device comprising:
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a semiconductor substrate in which a channel formation region is formed between a pair of impurity regions formed with an interval; and a first insulating layer, a floating gate, a second insulating layer, and a control gate which are provided at a position of an upper layer portion of the semiconductor substrate and about overlapped with the channel formation region, wherein the first insulating layer is formed of a stacked layer of silicon oxide layer and a silicon nitride layer on a semiconductor substrate side; and wherein the floating gate is formed of a material having a higher electron affinity than silicon. - View Dependent Claims (23, 33)
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8. A nonvolatile semiconductor memory device comprising:
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a semiconductor substrate in which a channel formation region is formed between a pair of impurity regions formed with an interval; and a first insulating layer, a floating gate, a second insulating layer, and a control gate which are provided at a position of an upper layer portion of the semiconductor substrate and about overlapped with the channel formation region, wherein the first insulating layer is formed of a stacked layer of silicon oxide layer and a silicon nitride layer on a semiconductor substrate side; and wherein a barrier energy with respect to electrons of the floating gate, formed from the silicon oxide layer is higher than a barrier energy with respect to electrons of the channel formation region in the semiconductor substrate, formed from the silicon oxide layer. - View Dependent Claims (24, 34)
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9. A nonvolatile semiconductor memory device comprising:
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a semiconductor substrate in which a channel formation region is formed between a pair of impurity regions formed with an interval; and a first insulating layer, a floating gate, a second insulating layer, and a control gate which are provided at a position of an upper layer portion of the semiconductor substrate and about overlapped with the channel formation region, wherein the first insulating layer is formed of a stacked layer of silicon oxide layer and a silicon nitride layer on a semiconductor substrate side; and wherein the floating gate is formed of germanium or a germanium compound. - View Dependent Claims (15, 25, 35)
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10. A nonvolatile semiconductor memory device comprising:
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a semiconductor substrate in which a channel formation region is formed between a pair of impurity regions formed with an interval; and a first insulating layer, a floating gate, a second insulating layer, and a control gate which are provided at a position of an upper layer portion of the semiconductor substrate and about overlapped with the channel formation region, wherein the first insulating layer is formed of a stacked layer of silicon oxide layer and a silicon nitride layer on a semiconductor substrate side; and wherein the floating gate is formed of germanium or a germanium compound with a thickness of 1 nm or more and 20 nm or less. - View Dependent Claims (16, 26, 36)
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Specification