Patterning trenches in a photoresist layer with tight end-to-end separation

摘要

A method for forming two trenches with tight end-to-end spacing in a dielectric layer begins with providing a substrate having a dielectric layer. A hard-mask layer is deposited on the dielectric layer and a first photoresist layer is deposited on the hard-mask layer. The first photoresist layer is patterned to form an extended trench in the first photoresist layer. The hard-mask layer is then etched using the first photoresist layer as a mask to form an extended trench in the hard-mask layer. Next, a second photoresist layer is deposited on the hard-mask layer and patterned to form a resist line that intersects the extended trench. The resist line divides the extended trench into two separate trenches. The dielectric layer is then etched using the hard-mask layer and the resist line as a mask, thereby forming two trenches in the dielectric layer with end-to-end separation that corresponds to the resist line width.