Publication Date: 2015-Jan-19
The IP.com Prior Art Database
Disclosed are designs/methods to measure the temperature of large Field Effect Transistors (FETs)/micro-hot-spots.
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Current solutions for on-chip temperature monitoring capture the average temperature on a much larger-scale compared to FET dimensions. In addition, these can be placed away from the hottest circuit regions. It is also difficult to determine alternating current (AC) switching environment around the temperature monitor. Thus, current solutions for on-chip temperature monitoring cannot measure the temperature of individual FETs / micro-hot-spots.
The novel contribution is designs and methods to measure the temperature of large FETs/micro-hot-spots. The components for the designs and implementation methods include:
• A single-finger on the shared RX region as the large FET
- The method measures gate-resistance change to monitor micro-hot-spot temperature
- The method operates it in gate-connected-diode mode and uses diode operation to monitor micro-hot-spot temperature
• A metal wire resistor is positioned directly above the center region of the large FET. The method measures wire-resistance change to monitor micro-hot-spot heating.
• Voltage comparator based circuit to measure resistance change of thermal resistor
• Voltage comparator based circuit to measure threshold -voltage change of thermal diode
For the temperature, it is important to know the switching frequency and load of the Large FET for measurement or know that the switching frequency and load are representative of critical on chip circuits. Thus, the large FET to be measured can be located in a circuit that can be tested in direct current (DC) or AC mode with a known
Local circuits on chips are running hotter than the ambient temperature under normal operation, as well as under stress operations used for defect screening . With continued device scaling (i.e. with higher power densities, increased leakage, etc.), the local heating problem is reaching levels that could impact system reliability .
In addition to the circuit-scale/functional-macro-scale heating problem (i.e. 1e2 ~1e3 um scale), large Field Effect Transistors (FETs) (e.g., multi-finger buffer FETs, large inverters, etc.) are getting hotter at an even smaller scale (< 1um ~ micro-hot-spots). These micro-hot spots can dominate reliability fail calculations due to the exponential dependence on temperature for electromigration...