Patent ID: 6440640
Filing Date: 2002-08-27
Classification: H01L

Abstract:
A method for forming a via, comprising:forming a dielectric layer on an antireflective coating (ARC) layer covering a first metal layer; forming a transition metal layer on the dielectric layer; forming an ultra-thin photoresist layer on the transition metal layer, the ultra-thin photoresist layer having a thickness within the range of 500 Ã¥-5000 Ã¥; patterning the ultra-thin photoresist layer with radiation to define a pattern for the via; using the ultra-in photoresist layer as a mask dug a first etch step to transfer the via pattern to the transition metal layer, the first etch step including an etch chemistry that is selective to the transition metal layer over the ultra-in photoresist layer; removing the ultra-thin photoresist layer completely from the transition metal layer immediately after completion of the first etch step but before a second etch step; using the transition metal layer as a hard mask during a second etch step to form a contact hole corresponding to the via pattern by etching portions of the dielectric layer.