Active solid-state devices (e.g. – transistors – solid-state diode – Field effect device – Having insulated electrode
Reexamination Certificate
1999-05-07
2002-11-12
Lee, Eddie (Department: 2815)
Active solid-state devices (e.g., transistors, solid-state diode
Field effect device
Having insulated electrode
C257S315000, C257S406000, C257S411000
Reexamination Certificate
active
06479858
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to semiconductor devices, and more particularly, to a device with multiple floating gates which can serve as a memory cell with multiple floating gates in which the threshold voltage is adjustable.
BACKGROUND OF THE INVENTION
There is a trend in the semiconductor industry to reduce the geometry of semiconductor devices to thereby increase the number of such devices available in a given area. This reduction of the geometry of the semiconductor device results in increased density of an integrated circuit (IC) chip. As the integration degree of semiconductor devices becomes high, the device size must be gradually reduced. The increased density of semiconductor devices in a given area of an IC chip results in an increased performance by the IC chip, including faster operating speeds and lower power consumption necessary to supply the IC chip.
The size of a semiconductor device is in large part dependent on the critical length of a “channel” in a semiconductor device. A “channel” is a thin region of the device that supports conduction. Channel lengths have continuously shrunk to the submicron range. State of the art channel lengths range from approximately 0.18 &mgr;m to 0.25 &mgr;m.
If a semiconductor device below 0.1 micron size is manufactured, there may be a need to use multiple threshold voltages. For instance, random logic may be located on the same chip as the memory when using semiconductor devices below 0.1 micron size. The random logic may require a low threshold voltage while the memory may require a higher threshold voltage. Conventionally, it is typically very difficult to manufacture a single IC chip which allows the use of multiple threshold voltages. Many additional masking steps would be required to produce such an IC chip in the conventional manner.
Accordingly, what is needed is a device which is smaller than the conventionally sized semiconductor devices which can allow the threshold voltages to be adjusted, and a method for producing such a device. The present invention addresses such a need.
SUMMARY OF THE INVENTION
The present invention provides a semiconductor device which can serve as a memory cell in which the threshold voltage is adjustable. Additionally, the semiconductor device according to the present invention has a channel length below approximately 0.1 microns, and preferably approximately 0.05 microns. A semiconductor device according to the present invention, and a method for producing such a semiconductor device, comprises a control gate, a first floating gate located in proximity to the control gate, and a second floating gate located in proximity to the control gate. The present invention allows the threshold voltage of the device to be adjusted to various levels. Additionally, the device according to the present invention can be used as a very effective nonvolatile memory device.
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Lee Eddie
Lee Eugene
Sawyer Law Group LLP
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