Borderless contact

A method of forming borderless contacts and vias is disclosed. Borders which are conventionally provided in aligning contacts and vias to device and/or metal regions in a semiconductor device take up too much valuable real estate on semiconductor substrates, and hence reduce productivity of the products. By employing a hard-mask of this invention, and a specific sequence of process steps, alignment can be achieved without the need for borders. First, a thin nitride layer is deposited on an insulating layer formed over a substructure of a substrate having device and/or metal regions. The hard-mask is patterned with metal line openings, and a photoresist layer is formed with contact or via pattern over the already patterned hard-mask. The contact/via openings are etched into the dielectric layer until the substructure is reached. The hole openings are filled plug metal and then partially etched back, leaving a plug in the hole opening. The line trench is etched further into the dielectric layer until metal plug is reached. The trench is then filled with metal, such as aluminum-copper or copper and the excess is removed by chemical-mechanical polishing. Thus, a borderless and self-aligned interconnect comprising plug and metal line is formed.