Post-trench processing of silicon deep trench capacitors for power electronic applications

Silicon deep trench capacitors represent a promising alternative to surface-mounted capacitors, which are typically used in high power applications. Using these devices, modules with significantly lower parasitic inductances as well as a lower thermal impedance can be realized. It is demonstrated that the high aspect ratio trenches enlarge the surface area of the substrate, which yields an increase in capacitance per surface area by a factor of about 39 in comparison with planar silicon capacitors of comparable design. Moreover, high temperature post-trench processing in argon atmosphere is shown to enhance the dielectric breakdown voltage of the devices and to yield a significantly lower leakage current. Only a small deviation in capacitance of about 3.2% across the wafer and a high voltage stability indicates the high homogeneity and the good quality both of the dielectric layer and the post-trench process.