Disclosed are structures with a complementary field effect transistor (CFET) and a buried metal interconnect that electrically connects a source/drain region of a lower-level transistor of the CFET with another device. The structure can include a memory cell with first and second CFETs, where each CFET includes a pull-up transistor stacked on and having a common gate with a pull-down transistor and each pull-down transistor has a common source/drain region with a pass-gate transistor. The metal interconnect connects a lower-level source/drain region of the first CFET (i.e., the common source/drain region of first pass-gate and pull-up transistors) to the common gate of the second CFET (i.e., to the common gate of second pull-down and pull-up transistors). Formation methods include forming an interconnect placeholder during lower-level source/drain region formation. After upper-level source/drain regions and replacement metal gates are formed, the interconnect placeholder is exposed, removed and replaced with a metal interconnect.