Patent ID: 6514857
Filing Date: 2003-02-04
Classification: H01L,Y10S

Abstract:
A method of forming a dual damascene structure comprising the steps of:depositing a first layer of insulative material having a relatively low dielectric constant; depositing an etch stop layer atop said first layer of insulative material, depositing a second layer of insulative material having a relatively low dielectric constant atop said etch stop layer; depositing a mask layer of silicon-based photosensitive material atop said second layer of insulative material; illuminating said mask layer with various intensity levels of radiation to change a characteristic of said mask layer to define a multilevel pattern therein, wherein said illuminating step includes providing a grey tone mask proximate said mask layer, where said grey tone mask contains transparent portions, partially transparent port ions and opaque portions that define said multilevel pattern, and illuminating said mask layer with radiation through said grey tone mask such that a surface of said mask layer is fully exposed, partially exposed and not exposed to said illumination in correspondence with said transparent portions, partially transparent portions and opaque portions of said grey tone mask, where said silicon-based photosensitive material changes characteristics with respect to an amount of illumination; etching said mask layer to form a patterned hard mask layer defining a via; etching said second layer of insulative material to said etch stop layer to transfer therethrough said via defined in said patterned hard mask layer; etching said patterned hard mask to define a trench and simultaneously etching said etch stop layer to transfer therethrough said via previously transferred through said second layer of insulative material; and etching said first layer of insulative material to transfer therethrough said via previously transferred through said etch stop layer and simultaneously etching said second layer of insulative material to transfer therethrough said trench defined in said patterned hard mask layer.