Method of fabricating a sub-lithographic sized via

摘要

A method of fabricating a sub-lithographic sized via 31 is disclosed. A dual-polymer method is used to form a stacked layer of polymer materials wherein a first polymer layer 11 has a first etch rate and a second polymer layer 13 has a second etch rate. The first etch rate is preselected to be faster than the second etch rate when the first and second polymer layers (11, 13) are isotropically etched. The second polymer layer 13 is made from a photo active material and is operative as an etch mask for the first photoresist layer. The etching is continued until the first polymer layer 11 has a sub-lithographic feature size SF that is less than a lithography limit lambda L of a lithography system. A dielectric material 25 is deposited on the etch mask 19 and the first polymer layer 11. The first polymer layer 11 is lifted-off to define a sub-lithographic sized via 31.