<inline-formula><math display="inline" overflow="scroll"><mrow><mn>30</mn><mtext>-</mtext><mi>nm</mi></mrow></math></inline-formula> half-pitch metal patterning using Motif™ critical dimension shrink technique and double patterning

Abstract

Double-patterning lithography appears a likely candidate to bridge the gap between water-based immersion lithography and EUV. A double-patterning process is discussed for 30-nm half-pitch interconnect structures, using 1.2 numerical aperture immersion lithography combined with the MotifTM critical dimension (CD) shrink technique. An adjusted optical proximity correction (OPC) calculation is required to model the proximity effects of the Motif shrink technique and subsequent metal hard mask (MHM) etch, on top of the lithography-based proximity effects. The litho-etch-litho-etch approach is selected to pattern a TiN metal hard mask. This mask is then used to etch the low-k dielectric. The various process steps and challenges encountered are discussed, with the feasibility of this approach demonstrated by successfully transferring a 30-nm half-pitch pattern into the MHM.