an aluminum lateral interconnect of a back end of the line is used to define the x and y dimensions of a through - silicon via in a semiconductor chip formed in a silicon substrate . the tsv includes one or more aluminum annulus formed on a surface of the substrate , and a deep trench in the substrate having a diameter that is determined by the diameter of the aluminum annulus . the annulus can also be provided with a conductive strap upon which a capacitor can be formed . the strap can also be used to provide a connection of the tsv to other beol interconnects .