| AVS 58th Annual International Symposium and Exhibition | |
| Nanomanufacturing Science and Technology Focus Topic | Tuesday Sessions |
| Session NM+MN+MS+TF-TuM |
| Session: | Lithography Strategies for Nanomanufacturing |
| Presenter: | D.G. De Oteyza, Lawrence Berkeley National Laboratory |
| Authors: | D.L. Olynick, Lawrence Berkeley National Laboratory D.G. De Oteyza, Lawrence Berkeley National Laboratory P. Perera, Lawrence Berkeley National Laboratory P. Kulshreshtra, Lawrence Berkeley National Laboratory P. Ashby, Lawrence Berkeley National Laboratory M. Schmidt, Lawrence Berkeley National Laboratory S. Dhuey, Lawrence Berkeley National Laboratory B.D. Harteneck, Lawrence Berkeley National Laboratory R.M. Falch, Lawrence Berkeley National Laboratory A. Schwartzberg, Lawrence Berkeley National Laboratory P.J. Schuck, Lawrence Berkeley National Laboratory S. Cabrini, Lawrence Berkeley National Laboratory |
| Correspondent: | Click to Email |
As features sizes continue to shrink, new approaches are required to overcome roadblocks toward high-resolution lithographic patterning. One significant roadblock towards miniaturization is pattern collapse due to capillary forces during drying.[1] We have invented a dry development method for creation of high resolution and high aspect ratio resist features. We use resists that undergo an optical absorption change after exposure to high-resolution radiation (here we use electron beam lithography). This optical change allows the material to be selectively laser ablated such that the resolution is defined by the high-resolution radiation and not limited by the laser spot size. Using methyl-acetoxy calix[6]arene, a CW 532 nm laser, and spot sizes ~300 nm, we have produced features down to 10 nm in a film 120 nm thick, with pitch resolution down to 30 nm(Fig. 1). Calixarene was introduced as a high resolution electron-beam resist [2] and has demonstrated 12.5 nm half-pitch in extreme ultra-violet lithography.[3] Typically, films are spun thin to prevent high-resolution pattern collapse in thicker films but using the dry development, the patterns are well defined even in the thick films. Note, the resist acts negative with solvent development, as the cross-linked material can not be removed, whereas it is positive under laser dry development at the same electron-beam dose conditions. This is in contrast to the thermal dry development process where calixarenes are developed in negative tone.[4] With thermal development, patterns were demonstrated at 25 nm half-pitch in a 25 nm film (1:1 aspect ratio.
We have systematically studied the optical absorption contrast behavior as a function of electron beam dose, laser wavelength, and laser dose. At 532 nm laser wavelength, we identified that the absorption is a two photon process and found one functional group which is responsible for the optical contrast. We will discuss the options for materials beyond calixarenes.
This work was supported by the U.S. Department of Energy under Contract No. DE-AC02-05CH11231.
References
[1] T. Tanaka, M. Morigami, N. Atoda, Jpn. J. Appl. Phys. 32 (1993) 6059-6064.
[2] J. Fujita, Y. Ohnishi, S. Manako, Y. Ochiai, E. Nomura, T. Sakamoto, S. Matsui, Jpn. J. Appl. Phys. 36 (1997) 7769-7772.
[3] H.H. Solak, Y. Ekinci, P. Kaser, S. Park, J. Vac. Sci. Technol. B, 25 (2007) 91-95.
[4] V. Auzelyte, A. Langner, H.H. Solak, J. Vac. Sci. Technol. B, 27 (2009) 2990-2992.