Characterization of flexible CMOS technology tranferred onto a metallic foil

In this work we demonstrate a method to transfer high-performance industrial CMOS circuits thinned down to 5.7 μm and bond onto a 25-μm-thick stainless steel foil with a 800-nm-thick indium layer. The bonding is performed at the temperature of 100°C with an applied pressure of 1.2 bar. The die stack transferred onto the metallic substrate comprises the 200-nm-thick active layer and the 5.5-μm-thick interconnection multilayer stack resulting in a light, compact, and bendable thin film. We unveil that DC and RF performances are invariant after the transfer onto this metallic substrate. Unity-current-gain cutoff and maximum frequencies as high as 163/188 GHz for n-MOSFETs and 100/159 GHz for p-MOSFETs have been measured.