US Patent 8431485 Manufacturing method for a buried circuit structure

A manufacturing method for a buried circuit structure includes providing a substrate having at least a trench formed therein, forming a firs conductive layer on the substrate blanketly, forming a patterned photoresist having a surface lower than an opening of the trench in the trench, removing the first conductive layer not covered by the patterned photoresist to form a second conductive layer having a top lower than an opening of the trench in the trench, removing the patterned photoresist, performing a dry etching process to remove the second conductive layer from the bottom of the trench to form a third conductive layer on the sidewalls of the trench, performing a selective metal chemical vapor deposition to form a metal layer having a surface lower than a surface of the substrate, and forming a protecting layer filling the trench on the metal layer.