Method for forming a hard mask in a layer on a planar device

Abstract

A hard mask is produced from spacer structures. The spacer structures are formed from a conformal deposition on elevated structures produced lithographically in a projection process. The conformal deposition is etched back laterally on the elevated structures resulting in the spacer structures. The elevated structures between the spacer structures are subsequently etched away, so that the spacer structures remain in an isolated fashion as sublithographic structures of a hard mask with a doubled structure density compared with that originally produced in lithographic projection. In a regularly disposed two-dimensional array of structures in the hard mask for forming trenches—for instance for trench capacitors—the method achieves a doubling of the structure density in the array. A further iteration step is formed by forming further spacer structures on the first and second spacer structures, thereby achieving an even higher increase in structure density in the hard mask. REL/rit

Dependencies are inferred from the claim text.