A technique, comprising: forming a stack comprising a semiconductor layer for providing the semiconductor channels of one or more transistors, and an insulator layer; and patterning the stack so as to form in a single process both: (i) one or more interconnection holes for connecting a conductor level on one side of the stack to a conductor level on the opposite side of the stack; and (ii) one or more leakage reduction trenches for reducing leakage paths via the semiconductor between conductor elements on one side of the stack.