Trench-gated MOSFET with integral temperature detection diode
First Claim
1. A trenched gate MOSFET comprising:
- a semiconductor body comprising a drain region of a first conductivity type;
a trench formed in a surface of said semiconductor body;
a gate formed in said trench, said trench being lined with a dielectric layer for electrically insulating said gate from said semiconductor body;
a body region of a second conductivity type located adjacent said trench;
a source region of said first conductivity type located adjacent said trench and abutting said surface of said semiconductor body;
said MOSFET comprising a temperature detection cell, said temperature detection cell comprising a first diffusion of said first conductivity type and a second diffusion of said second conductivity type, said second diffusion enclosing and forming a PN junction with said first diffusion, said second diffusion extending to a level below a level of a bottom of said trench and having a dopant concentration such that said second diffusion functions to protect said dielectric layer at a comer of said trench from damage from high electric fields and to inhibit a turn-on of a bipolar transistor comprising said first and second diffusions, said PN junction forming a temperature detection diode.
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Accused Products
Abstract
A vertical N-channel trenched-gate power MOSFET includes an integral temperature detection diode. The diode includes an N+ region which serves as the cathode and which is formed within a tub of P-type material, which serves as the anode. The N+ region is separated from the trench. The anode of the temperature detection diode may be shorted to the source or may be separately biased. The temperature of the MOSFET is monitored by supplying a current through the diode in the forward direction and measuring the voltage across the forward-biased diode. In an alternative embodiment, a pair of N+ regions are formed within the P-tub, constituting a diode pair, and the temperature is detected by monitoring the difference in the voltages across the diodes. An overtemperature detection unit compares the voltage across the diode or diodes with a reference voltage and provides an output which can be used to turn the MOSFET off when the temperature reaches a predetermined level.
161 Citations
31 Claims
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1. A trenched gate MOSFET comprising:
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a semiconductor body comprising a drain region of a first conductivity type; a trench formed in a surface of said semiconductor body; a gate formed in said trench, said trench being lined with a dielectric layer for electrically insulating said gate from said semiconductor body; a body region of a second conductivity type located adjacent said trench; a source region of said first conductivity type located adjacent said trench and abutting said surface of said semiconductor body; said MOSFET comprising a temperature detection cell, said temperature detection cell comprising a first diffusion of said first conductivity type and a second diffusion of said second conductivity type, said second diffusion enclosing and forming a PN junction with said first diffusion, said second diffusion extending to a level below a level of a bottom of said trench and having a dopant concentration such that said second diffusion functions to protect said dielectric layer at a comer of said trench from damage from high electric fields and to inhibit a turn-on of a bipolar transistor comprising said first and second diffusions, said PN junction forming a temperature detection diode. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25)
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11. A trenched gate MOSFET comprising:
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a semiconductor body comprising a drain region of a first conductivity type; a trench formed in a surface of said semiconductor body; a gate formed in said trench, said gate being electrically insulated from said semiconductor body by a dielectric layer; a body region of a second conductivity type located adjacent said trench; a source region of said first conductivity type located adjacent said trench and abutting said surface of said semiconductor body; said MOSFET comprising a temperature detection cell, said temperature detection cell comprising first and second diffusions of said first conductivity type and a third diffusion of said second conductivity type, said first and second diffusions being spaced apart from each other and being enclosed in said third diffusion, a first diode being formed at a PN junction between said first and third diffusions and a second diode being formed at a PN junction between said second and third diffusions, said first and second diodes being for detecting a temperature within said MOSFET; and a first metal contact in electrical contact with said first diffusion and a second metal contact in electrical contact with said second diffusion, said first and second metal contacts being electrically isolated from each other. - View Dependent Claims (12, 13, 14, 26, 27)
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28. A method of detecting a temperature within a MOSFET formed in a semiconductor chip, said method comprising:
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fabricating first and second temperature detection diodes integrally within said semiconductor chip; causing respective currents to flow through said diodes; detecting a first voltage across said first temperature detection diode and detecting a second voltage across said second temperature detection diode; comparing said first and second voltages; using the difference between said first and second voltages to determine said temperature. - View Dependent Claims (29, 30, 31)
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Specification