Chemically amplified fullerene resists for e-beam lithography

Abstract

The minimum lithographic feature size for microelectronic fabrication continues to shrink, and resist properties are beginning to dominate the achievable resolution. There is a strong need for a high resolution, high sensitivity resist for future nodes that is not met by conventional polymeric resists at this time. Molecular resists, such as fullerene derivatives have the potential for lower LWR and improved resolution, but have typically been insufficiently sensitive to irradiation. Here we present a fullerene based three component chemically amplified resist system with high resolution and sensitivity, and wide process latitude. The sensitivity of this resist is between 5 and 10 µC/cm 2 at 20 keV for various combinations of post application bake and post exposure bake conditions. Using 30 keV electron beam exposure, sparse patterns with 12 nm resolution were demonstrated, at a line dose of 300 pC/cm, whilst dense patterns with half-pitch 20 nm were achieved at 200 pC/cm. The LWR for the densely patterned resist (measured at 20 nm half pitch) is ~ 4.4 nm, whilst for the 12 nm sparse feature the measured LWR is ~ 2.5 nm. The etch durability is comparable with commercial novolac resists

Plasma etching of high-resolution features in a fullerene molecular resist

“…17 Using triarylsulfonium hexafluoroantimonate PAG and an epoxy novolac crosslinker a resolution of ~12 nm for sparse features, 20 nm half pitch and a sensitivity of less than 10 C/cm 2 have been achieved. 18,19 The resist also exhibits a low activation energy contributing to its wide process latitude and stability to post exposure delay. 20 Etching with SF 6 using electron cyclotron resonance (ECR) microwave plasma shows an etch durability comparable to SAL601, although sub 50 nm hp features suffer from high sidewall roughness using ECR.…”

Effect of resist polymer molecular weight on EUV lithography

“…6 It is commonly believed that lowering of polymer molecular weight gives a low LWR because of the reduction of dissolution unit size. [6][7][8][9] Molecular glass resist such as polyphenol, 10,11 calix arene, 12,13 and fullerene 14,15 is of great interest for its potential application for EUV resist from the standpoint of its uniformity and synthetic functionality to obtain a small size of matrix molecule. In contrast, little is known how low molecular weight of polymer affects EUV lithography performance at narrow pitch below hp 32 nm.…”

Synthesis and characteristics of multi-aryl substituted molecular glasses bearing biphenyl core

“…Molecular glasses have been explored to improve line edge roughness (LER) comparing to the conventional polymeric resists, whose performance issues was originating from chain entanglement, molecular size and composition distribution as well as acid diffusion control that hinders optimal lithographic performance [6,7]. Molecular glass resists such as polyphenol [8][9][10][11], calyx[n] arene [12][13][14][15], fullerene [16][17][18][19] and ladder cyclic molecule (noria) [20,21] are of great interest for its potential application for EUV resists. A series of tert-butyloxycarbonyl (t-Boc) protected C-4-hydroxyphenyl-calix [4]resorcinarene derivatives that produces 30 nm line space patterns under EUV conditions was developed by Chang and co-workers [22], and the first report on sub-50 nm features was obtained by a molecular glass resist using standard processing conditions.…”