Method of fabricating a storage device including decontinuous storage elements within and between trenches
First Claim
1. A method of fabricating a storage device in an array of storage cells, comprising:
- forming first and second trenches in a semiconductor layer, wherein the first and second trenches are immediately adjacent trenches;
forming first and second source/drain regions underlying the first and second trenches, respectively;
forming first and second select gates in the first and second trenches, respectively;
forming a charge storage stack overlying the first and second select gates, wherein the charge storage stack includes a layer of discontinuous storage elements (DSEs), wherein, within a storage cell, a plurality of DSEs lies within at least one of the first and second trenches and over a first portion of the semiconductor layer between the first and second trenches;
forming a control gate overlying the charge storage layer; and
forming third source/drain regions that are spaced apart from each other and lie within second portions of the semiconductor layer between the first and second trenches.
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Abstract
A semiconductor storage cell includes a first source/drain region underlying a first trench defined in a semiconductor layer. A second source/drain region underlies a second trench in the semiconductor layer. A first select gate in the first trench and a second select gate in the second trench are lined by a select gate dielectric. A charge storage stack overlies the select gates and a control gate overlies the stack. The DSEs may comprise discreet accumulations of polysilicon. An upper surface of the first and second select gates is lower than an upper surface of the first and second trenches. The control gate may be a continuous control gate traversing and running perpendicular to the select gates. The cell may include contacts to the semiconductor layer. The control gate may include a first control gate overlying the first select gate and a second control gate overlying the second select gate.
137 Citations
20 Claims
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1. A method of fabricating a storage device in an array of storage cells, comprising:
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forming first and second trenches in a semiconductor layer, wherein the first and second trenches are immediately adjacent trenches; forming first and second source/drain regions underlying the first and second trenches, respectively; forming first and second select gates in the first and second trenches, respectively; forming a charge storage stack overlying the first and second select gates, wherein the charge storage stack includes a layer of discontinuous storage elements (DSEs), wherein, within a storage cell, a plurality of DSEs lies within at least one of the first and second trenches and over a first portion of the semiconductor layer between the first and second trenches; forming a control gate overlying the charge storage layer; and forming third source/drain regions that are spaced apart from each other and lie within second portions of the semiconductor layer between the first and second trenches. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20)
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Specification