Extension of ArF lithography for poly gate patterning of 65-nm generation and beyond

Abstract

Due to the existing problems and delay of 157nm lithography tool, extension of the ArF (193nm) lithography process with resolution enhancement techniques (RET) should be considered for the 65nm generation lithography and beyond. The mature double-exposure lithography process based on dark-field alternating phase-shift mask (PSM) is one of the promising RET candidates, which is proven to be one of the production-ready strong phase-shifting techniques for current and future IC generations.In this paper, poly gate patterning with the minimum pitch of 160nm has been demonstrated with high numeric aperture (NA) and small partial coherence of ArF lithography along with a dark-field alternating PSM. For poly gate patterning of 65nm generation, optimum illumination settings are found for minimum pitch of 160nm. Through-pitch common process windows for gates with 65nm after-development-inspection (ADI) critical dimension (CD) at minimum pitch of 160nm can be reached larger than 0.30um depth of focus (DOF), which can be used for 65nm node production. Through-pitch proximity can be compensated by optical proximity correction (OPC). Line edge roughness (LER) can be improved a little by this dark-field alternating PSM technique. LER is found of strong aerial image contrast dependency. Shifter width is also chosen as optimum value to obtain the largest process windows and minimize the phase conflicts. 193nm Hi-NA or liquid immersion lithography is suggested to push the alternating PSM resolution limitation.

Updates in Advanced Lithography

“…Many devices, such as optical pick-up heads (Huang et al, 2004), embedded waveguide mirrors (Dou et al, 2010), and sharped microneedles (Han et. al., 2007), require microstructures with large side surface angles measured from the normal direction of the resin surface.…”

“…However, the refractive beam path bending associated to the large index difference between the air and photoresist has limited the exposure angles in the resin and thus the realization of large angle side surfaces. In order to expand the exposure angle in the resin, one way is to immerse the lithographic resin in an index matching liquid (Huang et al, 2004;Han et. al., 2007;Ling & Lian, 2007), such as deionized (DI) water (n=1.33), heptane (n=1.39), or glycerol (n=1.6), which can effectively minimize the light beam path bending, as shown in Fig.…”

“…Many practical applications of 3D micro-and nano-structures have been reported, such as Vgrooves for fiber holder (Ling & Lian, 2007), mesh structures for microfilter (Sato et al, 2004), inclined surfaces for the optical pick-up head (Huang et al, 2004), pyramid array for optical display (Yoon et al, 2006;Shieh et al, 2005), some complex microstructures for micromixer Sato et al, 2006) and drug delivery (Han et al, 2007;Yoon et al, 2011), and periodic array for photonic crystal. In this section, we will demonstrate our exploitation of micro-and nano-structures applications on 45° inclined mirrors and microfilter system, fabricated by the prism-assisted photolithography.…”

Femtosecond Laser Lithography in Organic and Non-Organic Materials

“…When smaller structures were required for the metal-oxide-semiconductor (MOS) circuits improvement, the UV lamps were replaced with excimer lasers. Deep UV lithography (DUV), based on 248 nm (KrF) and 194 nm (ArF) wavelengths [3,4], is used in semiconductor industry to produce transistors with 90 nm gate lengths. A further decrease of the radiation source to the requirement of special vacuum chambers and the growth of calcium fluoride material [6,7], have limited the implementation of this technology on large scale.…”