Method for producing a through semiconductor via connection

A method of fabricating an interconnect structure on a back side of a semiconductor substrate portion of an integrated circuit chip, the method comprising:

• providing a semiconductor substrate comprising a bulk semiconductor material or a top layer of a semiconductor material, wherein the semiconductor substrate portion of the integrated circuit chip is formed by an upper layer of the bulk semiconductor material or by the top layer of the semiconductor material;
• etching at least one through semiconductor via opening in the semiconductor substrate;
• forming a pillar by filling the at least one through semiconductor via opening with a sacrificial material;
• after forming the pillar, producing a front end of line portion of the integrated circuit chip on the semiconductor substrate, the front end of line portion comprising an array of interconnect rails that is at least partially buried in the semiconductor substrate, wherein:
• producing the front end of line portion comprises recessing portions of the semiconductor substrate and a top surface of the pillar,
• the interconnect rails are produced by etching at least one trench in the semiconductor substrate,
• wherein the at least one trench intersects the pillar causing at least a portion of the sacrificial material to be removed and creating a first open cavity above the pillar, and
• an electrically conductive material is deposited in the at least one trench and in the first open cavity above the pillar, forming a buried rail in the at least one trench and an electrically conductive pad that is integral with the buried rail;
• producing a back end of line portion on the integrated circuit chip on top of the front end of line portion;
• bonding a front side of the semiconductor substrate to a carrier substrate;
• thinning the semiconductor substrate from the back side until the pillar is exposed;
• creating a second open cavity by removing the sacrificial material of the pillar, wherein the electrically conductive pad is exposed in the second open cavity;
• filling the second open cavity with an electrically conductive material creating a through semiconductor via connection from the front of the semiconductor substrate to the back of the semiconductor substrate;
• and
• producing the interconnect structure on the back side of the semiconductor substrate portion, the interconnect structure contacting the at least one through semiconductor via connection, and wherein the interconnect structure is connected to the front side of the semiconductor substrate by the at least one through semiconductor via connection.