Measuring the thermal diffusivity of CMOS chips

Abstract

This paper describes a new method for determining the effective value of the thermal diffusivity, D eff , of a CMOS chip. D eff is a parameter that describes the rate at which heat diffuses through a chip, and hence its knowledge is essential for the thermal management of systems on chip and the design of thermal sensors. By embedding an electrothermal filter (ETF) in a frequency-locked-loop (FLL), its phase response, which is determined by its (fixed) geometry and D eff , can be measured. D eff can then be accurately determined from the measured phase response. For an ETF implemented in a 0.7μm CMOS process, the resulting values of D eff were 1.405, 0.755, and 0.495 cm 2 /s at -55, 27, and 125 ºC respectively.

Temperature- and Supply Voltage-Independent Time References for Wireless Sensor Networks

“…Instead of using the energy reservoirs available in standard CMOS, the thermal capacity of the silicon substrate is used. In [125] an electro-thermal filter (ETF) has been demonstrated using an on-chip heating …”