NONVOLATILE SEMICONDUCTOR MEMORY DEVICE AND METHOD OF MANUFACTURING SAME
First Claim
1. A nonvolatile semiconductor memory device, comprising a plurality of memory strings including a plurality of memory transistors connected in series, the memory transistors being electrically rewritable,the memory strings including:
- a first semiconductor layer including a columnar portion extending in a perpendicular direction relative to a substrate, the first semiconductor layer being configured to function as a body of the memory transistors;
a charge storing layer formed to surround a side surface of the columnar portion and configured to store a charge;
a plurality of first conductive layers formed to surround the side surface of the columnar portion and the charge storing layer and configured to function as gates of the memory transistors; and
a first protecting layer stacked to protect a top portion of the plurality of first conductive layers,the plurality of first conductive layers constituting a first stairway portion formed stepwise such that ends of the first conductive layers are located at different positions, each of the first conductive layers constituting a step of the first stairway portion,a top surface of a first portion of the first stairway portion being covered with the first protecting layer including a first number of layers, anda top surface of a second portion of the first stairway portion being covered with the first protecting layer including a second number of layers fewer than the first number of layers, the second portion being located at a lower level than the first portion.
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Accused Products
Abstract
A memory string is formed to surround the side surface of a columnar portion and a charge storing layer, and includes plural first conductive layers functioning as gates of memory transistors, and a first protecting layer stacked to protect an upper portion of the plural first conductive layers. The plural first conductive layers constitute a first stairway portion formed stepwise such that their ends are located at different positions. Each first conductive layer constitutes a step of the first stairway portion. A top surface of a first portion of the first stairway portion is covered with the first protecting layer including a first number of layers, and A tope surface of a second portion of the first stairway portion located at a lower level than the first portion is covered with the first protecting layer including a second number of layers fewer than the first number of layers.
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Citations
20 Claims
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1. A nonvolatile semiconductor memory device, comprising a plurality of memory strings including a plurality of memory transistors connected in series, the memory transistors being electrically rewritable,
the memory strings including: -
a first semiconductor layer including a columnar portion extending in a perpendicular direction relative to a substrate, the first semiconductor layer being configured to function as a body of the memory transistors; a charge storing layer formed to surround a side surface of the columnar portion and configured to store a charge; a plurality of first conductive layers formed to surround the side surface of the columnar portion and the charge storing layer and configured to function as gates of the memory transistors; and a first protecting layer stacked to protect a top portion of the plurality of first conductive layers, the plurality of first conductive layers constituting a first stairway portion formed stepwise such that ends of the first conductive layers are located at different positions, each of the first conductive layers constituting a step of the first stairway portion, a top surface of a first portion of the first stairway portion being covered with the first protecting layer including a first number of layers, and a top surface of a second portion of the first stairway portion being covered with the first protecting layer including a second number of layers fewer than the first number of layers, the second portion being located at a lower level than the first portion. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
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18. A method of manufacturing a nonvolatile semiconductor memory device including a plurality of memory strings including a plurality of memory transistors connected in series, the memory transistors being electrically rewritable, the method comprising:
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stacking a plurality of conductive layers; forming a through hole to penetrate the plurality of conductive layers; forming a charge storing layer on a side surface of the through hole; forming a semiconductor layer to fill the through hole; forming a first stairway portion by processing those of the conductive layers between a topmost conductive layer and a fifth conductive layer as one of the conductive layers below the topmost conductive layer by a first number, such that ends of the plurality of conductive layers are located at different positions; forming a first protecting layer to cover the first stairway portion; dividing the first protecting layer, and forming a second stairway portion by processing those of the conductive layers below the fifth conductive layer, such that the ends of the plurality of conductive layers are located at different positions; and forming a second protecting layer to cover the first protecting layer and the second stairway portion. - View Dependent Claims (19, 20)
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Specification