Trench-gated MOSFET with integral temperature detection diode

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 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.

A method of detecting a temperature within a MOSFET formed in a semiconductor chip, said method comprising:

• 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.