Programmable structure including discontinuous storage elements and spacer control gates in a trench
First Claim
1. An array of storage cells wherein at least one of the storage cells comprises;
- a first source/drain region underlying a first trench defined in a semiconductor substrate;
a second source/drain region underlying a second trench in the substrate;
a charge storage stack on sidewalls of the trenches wherein the charge storage stack includes a layer of discontinuous storage elements (DSEs); and
electrically conductive spacers formed in the first and second trenches adjacent to the charge storage stacks wherein the depth of the trenches exceeds a height of the spacers wherein a gap exists between a top of the spacers and an upper surface of the substrate.
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Accused Products
Abstract
A semiconductor storage cell includes first and second source/drain regions underlying first and second trenches defined in a semiconductor substrate. Sidewalls of the trenches are lined with a charge storage stack that includes a layer of discontinuous storage elements (DSEs), which are preferably silicon nanocrystals. Spacer control gates are located in the trenches adjacent to the charge storage stacks on the trench sidewalls. The trench depth exceeds the spacer height so that a gap exists between a top of the spacers and the top of the substrate. A continuous select gate layer overlies the first trench. The gap facilitates ballistic programming of the DSEs adjacent to the gap by accelerating electrons traveling substantially perpendicular to the trench sidewalls. The storage cell may employ hot carrier injection programming to program a portion of the DSEs proximal to the source/drain regions.
91 Citations
20 Claims
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1. An array of storage cells wherein at least one of the storage cells comprises;
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a first source/drain region underlying a first trench defined in a semiconductor substrate; a second source/drain region underlying a second trench in the substrate; a charge storage stack on sidewalls of the trenches wherein the charge storage stack includes a layer of discontinuous storage elements (DSEs); and electrically conductive spacers formed in the first and second trenches adjacent to the charge storage stacks wherein the depth of the trenches exceeds a height of the spacers wherein a gap exists between a top of the spacers and an upper surface of the substrate. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A method of programming a first bit of storage cell in an array of storage cells by injecting charge into a first injection region of the storage cell, comprising:
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biasing a first source/drain region underlying a first trench in a semiconductor substrate to a first programming voltage (VP1); biasing a second source/drain region to a fourth programming voltage (VP4); biasing a first conductive spacer adjacent to a first layer of discontinuous storage elements (DSEs) on a sidewall of the first trench to a second programming voltage (VP2) wherein a depth of the trench exceeds a height of the spacer wherein a gap is defined from a top of the spacer to a top of the substrate; and biasing a first select gate overlying the first trench to a third programming voltage (VP3). - View Dependent Claims (12, 13, 14, 15, 16, 17, 18)
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19. A programmable storage cell, comprising:
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a semiconductor substrate defining first and second trenches running parallel to each other; first and second source/drain regions underlying the first and second trenches, respectively; charge storage stacks lining sidewalls of the trenches; control gates formed in the first and second trenches adjacent to the charge storage stacks wherein the depth of the trenches exceeds a height of the control gates wherein a gap exists between a top of the control gates and an upper surface of the substrate; a first select gate overlying the first trench; a first diffusion region occupying an upper portion of the substrate between the first and second trenches. - View Dependent Claims (20)
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Specification