SEMICONDUCTOR MEMORY DEVICE AND METHOD OF MANUFACTURING THE SAME
First Claim
1. A semiconductor memory device comprising nonvolatile memory cells including a first field effect transistor in a first region of the main surface of a semiconductor substrate, and a second field effect transistor which is adjacent to the first field effect transistor in a second region, whereina first gate electrode of the first field effect transistor formed in the first region, a second gate electrode of the second field effect transistor formed in the second region, a first gate dielectric formed between the semiconductor substrate and the first gate electrode, a charge storage layer formed between the semiconductor substrate and the second gate electrode and between the first gate electrode and the second gate electrode, and a first dielectric film formed between the semiconductor substrate and the charge storage layer and between the first gate electrode and the charge storage layer are arranged,the thickness of the first gate dielectric under the gate longitudinal direction end of the first gate electrode is thicker than that of the first gate dielectric under the gate longitudinal direction center of the first gate electrode, and the thickness of the first dielectric film that is positioned between the first gate electrode and the charge storage layer and is nearest to the semiconductor substrate, is 1.5 times or below of the thickness of the first dielectric film between the semiconductor substrate and the charge storage layer.
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Accused Products
Abstract
In a memory cell including an nMIS for memory formed on the sides of an nMIS for select and an nMIS for select via dielectric films and a charge storage layer, the thickness of a gate dielectric under the gate longitudinal direction end of a select gate electrode is formed thicker than that of the gate dielectric under the gate longitudinal direction center and the thickness of the lower layer dielectric film that is positioned between the select gate electrode and the charge storage layer and is nearest to a semiconductor substrate is formed 1.5 times or below of the thickness of the lower layer dielectric film positioned between the semiconductor substrate and the charge storage layer.
58 Citations
19 Claims
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1. A semiconductor memory device comprising nonvolatile memory cells including a first field effect transistor in a first region of the main surface of a semiconductor substrate, and a second field effect transistor which is adjacent to the first field effect transistor in a second region, wherein
a first gate electrode of the first field effect transistor formed in the first region, a second gate electrode of the second field effect transistor formed in the second region, a first gate dielectric formed between the semiconductor substrate and the first gate electrode, a charge storage layer formed between the semiconductor substrate and the second gate electrode and between the first gate electrode and the second gate electrode, and a first dielectric film formed between the semiconductor substrate and the charge storage layer and between the first gate electrode and the charge storage layer are arranged, the thickness of the first gate dielectric under the gate longitudinal direction end of the first gate electrode is thicker than that of the first gate dielectric under the gate longitudinal direction center of the first gate electrode, and the thickness of the first dielectric film that is positioned between the first gate electrode and the charge storage layer and is nearest to the semiconductor substrate, is 1.5 times or below of the thickness of the first dielectric film between the semiconductor substrate and the charge storage layer.
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11. A method of manufacturing a semiconductor memory device for forming nonvolatile memory cells including a first field effect transistor in a first region of the main surface of a semiconductor substrate, and a second field effect transistor which is adjacent to the first field effect transistor in a second region, the method comprising the steps of:
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(a) forming a first gate dielectric in the main surface of the semiconductor substrate in the first region; (b) forming the first gate electrode of the first field effect transistor comprising the first conductive film via the first gate dielectric in the first region, after forming the first conductive film on the main surface of the semiconductor substrate; (c) removing the first gate dielectric of other regions than the first gate dielectric under the first gate electrode; (d) performing a first oxidation processing to the semiconductor substrate, and making the thickness of the first gate dielectric under the gate longitudinal direction end of the first gate electrode thicker than that of the first gate dielectric under the gate longitudinal direction center of the first gate electrode; (e) performing a second oxidation processing to the semiconductor substrate by removing the whole or part of an oxide film formed by the first oxidation processing, after the step (d), and thereby forming a first dielectric film; (f) forming a charge storage layer on the first dielectric film, after the step (e); (g) forming the second conductive film on the main surface of the semiconductor substrate after the step (f), processing the second conductive film by anisotropic etching, and thereby forming sidewalls comprising the second conductive films on both of the sides of the first gate electrode; (h) removing the sidewall formed on one side of the first gate electrode, and making the sidewall remaining on the other side of the first gate electrode a second gate electrode; and (i) removing the first dielectric film and the charge storage layer of other regions than the first dielectric film and the charge storage layer formed between the first gate electrode and the second gate electrode, and in a second region. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19)
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Specification