Nonvolatile semiconductor memory device and manufacturing method thereof
First Claim
1. A nonvolatile semiconductor memory device which has memory cells of a split structure, each memory cell comprising:
- (a) a first semiconductor region and a second semiconductor region formed in a semiconductor substrate;
(b) a select gate and a memory gate formed after the formation of said select gate, said gates being formed above the portion located between said first and second semiconductor regions of said semiconductor substrate;
(c) a first insulator film formed between said select gate and said semiconductor substrate; and
(d) a second insulator film formed between said memory gate and said semiconductor substrate and also on the sidewall of said select gate, said sidewall being located between said select gate and said memory gate, wherein said second insulator film formed between said memory gate and said semiconductor substrate includes a first potential barrier film on said semiconductor substrate, a silicon nitride film formed further thereon and a second potential barrier film formed yet further thereon, and one end of said silicon nitride film touches said first potential barrier film of said second insulator film formed on said select gate sidewall, and wherein said second insulator film formed on said select gate sidewall between said select gate and said memory gate includes said first and second potential barrier films but does not include said silicon nitride film.
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Accused Products
Abstract
A MONOS nonvolatile memory of a split gate structure, wherein writing and erasing are performed by hot electrons and hot holes respectively, is prone to cause electrons not to be erased and to remain in an Si nitride film on a select gate electrode sidewall and that results in the deterioration of rewriting durability. When long time erasing is applied as a measure to solve the problem, drawbacks appear, such as the increase of a circuit area caused by the increase of the erasing current and the deterioration of retention characteristics. In the present invention, an Si nitride film is formed by the reactive plasma sputter deposition method that enables oriented deposition and the Si nitride film on a select gate electrode sidewall is removed at the time when a top Si oxide film is formed.
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Citations
25 Claims
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1. A nonvolatile semiconductor memory device which has memory cells of a split structure, each memory cell comprising:
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(a) a first semiconductor region and a second semiconductor region formed in a semiconductor substrate;
(b) a select gate and a memory gate formed after the formation of said select gate, said gates being formed above the portion located between said first and second semiconductor regions of said semiconductor substrate;
(c) a first insulator film formed between said select gate and said semiconductor substrate; and
(d) a second insulator film formed between said memory gate and said semiconductor substrate and also on the sidewall of said select gate, said sidewall being located between said select gate and said memory gate, wherein said second insulator film formed between said memory gate and said semiconductor substrate includes a first potential barrier film on said semiconductor substrate, a silicon nitride film formed further thereon and a second potential barrier film formed yet further thereon, and one end of said silicon nitride film touches said first potential barrier film of said second insulator film formed on said select gate sidewall, and wherein said second insulator film formed on said select gate sidewall between said select gate and said memory gate includes said first and second potential barrier films but does not include said silicon nitride film. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A nonvolatile semiconductor memory device which has memory cells of a split structure, each memory cell comprising:
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(a) a first semiconductor region and a second semiconductor region formed in a semiconductor substrate;
(b) a select gate and a memory gate formed after the formation of said select gate, said gates being formed above the portion located between said first and second semiconductor regions of said semiconductor substrate;
(c) a first insulator film formed between said select gate and said semiconductor substrate; and
(d) a second insulator film formed between said memory gate and said semiconductor substrate and also on the sidewall of said select gate, said sidewall being located between said select gate and said memory gate, wherein said second insulator film includes a first potential barrier film on said semiconductor substrate, a silicon nitride film formed further thereon, and a second potential barrier film formed yet further thereon and the thickness of the silicon nitride film formed on said select gate sidewall between said select gate and said memory gate is thinner than the thickness of the silicon nitride film formed between said memory gate and said semiconductor substrate. - View Dependent Claims (9, 10, 11, 12, 13, 14)
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15. A nonvolatile semiconductor memory device which has memory cells of a split structure, each memory cell comprising:
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(a) a first semiconductor region and a second semiconductor region formed in a semiconductor substrate;
(b) a select gate and a memory gate formed after the formation of said select gate, said gates being formed above the portion located between said first and second semiconductor regions of said semiconductor substrate;
(c) a first insulator film formed between said select gate and said semiconductor substrate; and
(d) a second insulator film formed between said memory gate and said semiconductor substrate and also on the sidewall of said select gate, said sidewall being located between said select gate and said memory gate, wherein said second insulator film formed between said memory gate and said semiconductor substrate includes a first potential barrier film on said semiconductor substrate, a silicon nitride film formed further thereon and a second potential barrier film formed yet further thereon, and wherein said second insulator film formed on said select gate sidewall between said select gate and said memory gate includes said first potential barrier film on said semiconductor substrate, said silicon nitride film formed further thereon and said second potential barrier film formed yet further thereon, and said silicon nitride film formed on said select gate sidewall and the silicon nitride film formed between said memory gate and said semiconductor substrate are separated from each other by said second potential barrier film on said semiconductor substrate, resulting in non-continuous films. - View Dependent Claims (16, 17, 18, 19, 20, 21, 22)
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23. A method for producing a nonvolatile semiconductor memory device, in which the process of forming said silicon nitride film employs the reactive sputter deposition method that uses Si as the target and is applied in a gas atmosphere containing nitrogen and rare gas, said nonvolatile semiconductor memory device having memory cells of a split structure, each memory cell, comprising:
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(a) a first semi-conductor-region and a second semiconductor region formed in a semiconductor substrate;
(b) a select gate and a memory gate formed after the formation of said select gate, said gates being formed above the portion located between said first and second semiconductor regions of said semiconductor substrate;
(c) a first insulator film formed between said select gate and said semiconductor substrate; and
(d) a second insulator film formed between said memory gate and said semiconductor substrate and also on the sidewall of said select gate, said sidewall being located between said select gate and said memory gate, wherein said second insulator film formed between said memory gate and said semiconductor substrate includes a first potential barrier film on said semiconductor substrate, a silicon nitride film formed further thereon and a second potential barrier film formed yet further thereon, and one end of said silicon nitride film touches said first potential barrier film of said second insulator film formed on said select gate sidewall and wherein said second insulator film formed on said select gate sidewall between said select gate and said memory gate includes said first and second potential barrier films but does not include said silicon nitride film.
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24. A method for producing a nonvolatile semiconductor memory device, in which the process of forming said silicon nitride film employs any one of the reactive sputter deposition method, the plasma enhanced chemical vapor deposition method, the low-pressure chemical vapor deposition method that uses monosilane and ammonia as the material gas, and the low-pressure chemical vapor deposition method that uses monosilane and ammonia as the material gas, said nonvolatile semiconductor memory device having memory cells of a split structure, each memory cell comprising:
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(a) a first semiconductor region and a second semiconductor region formed in a semiconductor substrate;
(b) a select gate and a memory gate formed after the formation of said select gate, said gates being formed above the portion located between said first and second semiconductor regions of said semiconductor substrate;
(c) a first insulator film formed between said select gate and said semiconductor substrate; and
(d) a second insulator film formed between said memory gate and said semiconductor substrate and also on the sidewall of said select gate, said sidewall being located between said select gate and said memory gate, wherein said second insulator film includes a first potential barrier film on said semiconductor substrate, a silicon nitride film formed further thereon and a second potential barrier film formed yet further thereon, and the thickness of the silicon nitride film formed on said select gate sidewall between said select gate and said memory gate is thinner than the thickness of the silicon nitride film formed between said memory gate and said semiconductor substrate.
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25. A method for producing a nonvolatile semiconductor memory device, in which the process of forming said silicon nitride film employs any one of the reactive sputter deposition method, the plasma enhanced chemical vapor deposition method, the low-pressure chemical vapor deposition method that uses monosilane and ammonia as the material gas, and the low-pressure chemical vapor deposition method that uses monosilane and ammonia as the material gas, said nonvolatile semiconductor memory device being provided with memory cells of a split structure, each memory cell comprising:
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(a) a first semiconductor region and a second semiconductor region formed in a semiconductor substrate;
(b) a select gate and a memory gate formed after the formation of said select gate, said gates being formed above the portion located between said first and second semiconductor regions of said semiconductor substrate;
(c) a first insulator film formed between said select gate and said semiconductor substrate; and
(d) a second insulator film formed between said memory gate and said semiconductor substrate and also on the sidewall of said select gate, said sidewall being located between said select gate and said memory gate, wherein said second insulator film formed between said memory gate and said semiconductor substrate includes a first potential barrier film on said semiconductor substrate, a silicon nitride film formed further thereon and a second potential barrier film formed yet further thereon, and wherein said second insulator film formed on said select gate sidewall between said select gate and said memory gate includes said first potential barrier film, said silicon nitride film formed further thereon and said second potential barrier film formed yet further thereon, and said silicon nitride film formed on said select gate sidewall and said silicon nitride film formed between said memory gate and said semiconductor substrate are separated from each other by said second potential barrier film on said semiconductor substrate, resulting in non-continuous films.
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Specification