A high stability and uniformity W micro hot plate

Abstract In this paper, we report on the simulation, design, fabrication and characterization of a tungsten (W) hot plate with a high electro-thermal stability and thermal uniform distribution. The device is constituted by a tungsten multi-rings resistor embedded in a dielectric membrane. Different layouts have been simulated, drawn and tested in order to evaluate and optimize the uniformity of the hot region and the power consumption. For the optimized device the diameter of the hot plate region is 1.25 mm, instead the membrane diameter is 1.83 mm. An innovative layout has been drawn to monitor the temperature uniformity of the hot region: distributed contacts have been integrated on it to be used as sense terminals and to extrapolate the single ring temperature. The same W resistor branches are used as thermal sensors by evaluating in advance the TCR (Temperature Coefficient of Resistance) and extrapolating the temperature by the resistance change. Thermal mapping shows that the temperature uniformity over the heated area is lower than 6% at 400 °C with a power consumption of only 135 mW. Thermal treatments have been performed in order to enhance the device thermal and electrical performances repeatability on wafer.