[FLASH MEMORY CELL STRUCTURE AND METHOD OF MANUFACTURING AND OPERATING THE MEMORY CELL]
First Claim
1. A flash memory cell, comprising:
- a substrate;
a tunneling dielectric layer formed over the substrate;
a floating gate formed over the tunneling dielectric layer;
an inter-gate dielectric layer formed over the floating gate;
a control gate formed over the inter-gate dielectric layer;
a first spacer layer formed on the sidewalls and the top section of the control gate;
a pair of second spacers formed on the sidewalls of the floating gate;
a source region formed in the substrate on a first side of the control gate and the floating gate;
an erase gate formed on the source region;
an erase gate dielectric layer formed between the source region and the erase gate;
a select gate formed on a second side of the control gate and the floating gate;
a select gate dielectric layer formed between the substrate and the select gate; and
a drain region formed in the substrate on one side of the select gate.
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Accused Products
Abstract
A flash memory cell structure is provided. The flash memory cell includes a substrate, a gate structure, a source region, an erase gate, an erase gate dielectric layer, a select gate, a select gate dielectric layer and a drain region. The gate structure is set up over the substrate. The gate structure includes a tunneling oxide layer, a floating gate, an inter-gate dielectric layer, a control gate and a spacer. The source region is formed in the substrate on one side of the gate structure. The erase gate is formed over the source region on one side of the gate structure. The erase gate dielectric layer is formed between the erase gate and the source region. The select gate is set up on another side of the gate structure. The select gate dielectric layer is formed between the select gate and the substrate. The drain region is formed in the substrate on one side of the select gate.
49 Citations
20 Claims
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1. A flash memory cell, comprising:
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a substrate;
a tunneling dielectric layer formed over the substrate;
a floating gate formed over the tunneling dielectric layer;
an inter-gate dielectric layer formed over the floating gate;
a control gate formed over the inter-gate dielectric layer;
a first spacer layer formed on the sidewalls and the top section of the control gate;
a pair of second spacers formed on the sidewalls of the floating gate;
a source region formed in the substrate on a first side of the control gate and the floating gate;
an erase gate formed on the source region;
an erase gate dielectric layer formed between the source region and the erase gate;
a select gate formed on a second side of the control gate and the floating gate;
a select gate dielectric layer formed between the substrate and the select gate; and
a drain region formed in the substrate on one side of the select gate. - View Dependent Claims (2, 3, 4, 5)
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6. A flash memory cell, comprising:
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a substrate;
a first gate structure and a second gate structure formed on the substrate, wherein the first gate structure and the second gate structure each has at least a floating gate formed over the substrate and a control gate formed over the floating gate;
a source region formed in the substrate between the first gate structure and the second gate structure;
an erase gate formed above the source region between the first gate structure and the second gate structure;
an erase gate dielectric layer formed between the source region and the erase gate;
a first select gate and a second select gate formed on one side of the sidewall of the first gate structure and the second gate structure away from the source region;
a select gate dielectric layer formed between the substrate and the first and second select gate; and
a pair of drain regions formed in the substrate just outside the first select gate and the second select gate. - View Dependent Claims (7, 8, 9, 10)
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11. A method of fabricating flash memory cells, comprising the steps of:
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providing a substrate, wherein the substrate has a first gate structure and a second gate structure thereon, the first gate structure and the second gate structure each comprises a tunneling dielectric layer formed over the substrate, a floating gate formed over the tunneling dielectric layer, an inter-gate dielectric layer formed over the floating gate, a control gate formed over the inter-gate dielectric layer and a first spacer formed on the sidewalls and the top section of the control gate;
forming a source region in the substrate between the first gate structure and the second gate structure;
forming an erase gate dielectric layer over the upper surface of the source region and forming a second spacer on the sidewalls of the floating gate;
forming an erase gate over the source region such that the erase gate completely fills the space between the first gate structure and the second gate structure;
forming third spacers on the other sides of the first gate structure and the second gate structure corresponding the erase gate;
forming a select gate dielectric layer over the substrate;
forming a first select gate and a second select gate on the sidewall of the third spacers; and
forming a first drain region and a second drain region in the substrate just outside the first select gate and the second select gate. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19)
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20. A method of operating a flash memory cell, wherein the flash memory cell comprises a substrate, a floating gate formed over the substrate, a control gate formed over the floating gate, a source region formed in the substrate on a first side of the control gate and the floating gate, an erase gate formed above the source region on the firs side of the control gate and the floating gate, a select gate formed on a second side of the sidewall of the control gate and the floating gate, a drain region formed in the substrate just outside the select gate, the operating method comprising the steps of:
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applying a first positive voltage to the control gate, applying a second positive voltage to the select gate, applying a third positive voltage to the source region and connecting the drain region to ground so that channel hot electrons are injected to program data into the flash memory cell; and
applying a fourth positive voltage to the erase gate, setting the control gate to 0V and setting the source region and the drain region to a floating state so that the Fowler-Nordheim effect is triggered to erase data from the flash memory cell.
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Specification