The present disclosure provides a thermo-mechanically reliable copper TSV and a technique to form such TSV during BEOL processing. The TSV constitutes an annular trench which extends through the semiconductor substrate. The substrate defines the inner and outer sidewalls of the trench, which sidewalls are separated by a distance within the range of 5 to 10 microns. A conductive path comprising copper or a copper alloy extends within said trench from an upper surface of said first dielectric layer through said substrate. The substrate thickness can be 60 microns or less. A dielectric layer having interconnect metallization conductively connected to the conductive path is formed directly over said annular trench.