Semiconductor device and fabrication method thereof

A semiconductor device includes: a metal-containing compound layer on a semiconductor substrate; a dielectric film on the semiconductor substrate and the metal-containing compound layer; a contact hole penetrating through the dielectric film to reach the metal-containing compound layer; a contact plug in the contact hole. The semiconductor device further includes a manganese oxide layer extending between the contact plug and respective one of the dielectric film and the metal-containing compound layer.