The measurement of the power dissipated by a semiconductor device is essential to evaluate the performance and reliability of power electronics systems. Power loss measurement can be difficult when the device is highly efficient and the losses are extremely low. When measuring the efficiency of an electronic system, many kind of errors can be introduced by the probes or by instruments and therefore the use of bulky and expensive set-ups are often required. The paper presents a simple method based on a heat flux measurement sensor that allows the estimation by calorimetry of the power dissipated by a semiconductor device. A control/readout circuit keeps the switching device at room temperature minimizing the heat exchanged with the ambient, improving the accuracy of the measurement. ... Read more

We report a novel investigation of the tribological properties of aluminum oxide (Al2O3) when it is used as protective coating on the sidewalls of microelectromechanical systems (MEMS). By using an in-house built optical displacement measurement system, we were able to measure the on-chip displacements with an unprecedented resolution of 2 nm. This corresponds to 2 nN and 9 nN force resolution, respectively, depending on whether an adhesion or a friction sensor MEMS device was used for the measurement. Al2O3 was deposited on the vertical etched sidewalls using atomic layer deposition (ALD). All tests were carried out in ambient conditions. The same tests carried out on uncoated polysilicon devices were not reproducible due to stiction, which sometimes prevented the interacting surfaces from moving once contact was made. The higher adhesion of silicon was also found to hinder the mobility of the slider. In the ALD-coated devices, we observed increasing adhesion after 50000 repeated contacts. We attribute this increase to the accumulation of aluminum hydroxide debris produced by the reaction with moisture in the environment. We also investigated the long-term effect of friction on the coated silicon sidewalls. The dissipated energy decreases, with a minimum lateral force occurring around the 1000th cycle. After 1000 cycles, the lateral displacement decreases, suggesting an additional lateral dragging force caused by the interaction between a mixture of aluminum hydroxides and water. However, the small overall amount of debris produced during the friction test indicates the outstanding characteristic of Al2O3 as a protective coating for MEMS that use contacting or sliding interfaces. ... Read more

In this paper, we demonstrate, at 300 GHz and with integrated technology, the effectiveness of artificial dielectric layers to enhance the front-to-back ratio of printed antennas. This concept was previously proposed at microwave frequencies and using printed circuit board technology. The artificial material is now realized by introducing non-resonant metallic inclusions in a silicon dioxide host material. This allows to enhance the permittivity of the host medium and renders it anisotropic. By loading an electrically
thin dielectric with these metallic inclusions, an engineered slab with effectively quarter wavelength thickness has been realized.
Despite the large effective height and density of the artificial dielectric, the surface wave efficiency of the antenna is 99%. This
is entirely due to the anisotropic properties of the material. A prototype antenna was built using an in-house CMOS back-end compatible integrated circuits (IC) process. Measured results from the antenna are presented and show a good agreement with the expected results. ... Read more