Active solid-state devices (e.g. – transistors – solid-state diode – With means to increase breakdown voltage threshold – In integrated circuit
Reexamination Certificate
1999-02-18
2001-08-14
Lee, Eddie (Department: 2815)
Active solid-state devices (e.g., transistors, solid-state diode
With means to increase breakdown voltage threshold
In integrated circuit
C257S491000, C257S605000
Reexamination Certificate
active
06274918
ABSTRACT:
TECHNICAL FIELD OF THE INVENTION
This invention relates in general to implementation of a zener diode in an integrated circuit and, more particularly, to an integrated circuit diode and a method of fabricating the diode so as to realize reduced power consumption and a higher breakdown voltage for a given integrated circuit area.
BACKGROUND OF THE INVENTION
One technique for implementing a zener diode in an integrated circuit involves the provision of spaced and alternating n+ and p+ regions in an n-well or p-well. A variation is to provide a p-base (shallow p-well) around the p+ regions in an n-well, or an n-base around the n+ regions in a p-well. The p+ regions are interconnected and serve as the anode, and the n+ regions are interconnected and serve as a cathode.
Where a particular application requires a zener diode with a specified breakdown voltage, a design criteria is to realize the specified breakdown voltage, while using the smallest possible area in the integrated circuit. Stated differently, for a given area of the integrated circuit, a design criteria is to implement a zener diode with the highest possible breakdown voltage.
A further design criteria is to decrease the power dissipated in the zener diode when it is forward biased. Since power is defined to be the product of voltage and current, there must be efficient current conductivity for a given forward bias voltage, which means reduced resistance to current flowing through the diode for a given voltage. Stated differently, it is desirable to achieve a lower operational voltage across the diode for a given current flow through the diode.
SUMMARY OF THE INVENTION
From the foregoing, it may be appreciated that a need has arisen for a method and apparatus for implementing an integrated circuit diode so as to achieve reduced power consumption, and so as to achieve an increased breakdown voltage for a given area of the integrated circuit. According to the present invention, a method and apparatus are provided to address this need, and involve: providing a semiconductor substrate having a portion which is made from a first type of semiconductor material; fabricating in the portion of the substrate a first region which is made from the first type of semiconductor material and is doped more heavily than the portion of the substrate; fabricating a second region which is disposed in the portion of the substrate, which is spaced from the first region, and which is made from a second type of semiconductor material different from the first type of semiconductor material, one of the first and second types of semiconductor material being a p-type material and the other thereof being an n-type material; and fabricating a RESURF region in the substrate between the first and second regions and in contact with the second region, the RESURF region being made of the second type of semiconductor material and being doped more lightly than second region.
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Efland Taylor R.
Tsai Chin-Yu
Brady III Wade James
Eckert II George C.
Lee Eddie
Telecky , Jr. Frederick J.
Texas Instruments Incorporated
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