Sains Malaysiana 43(2)(2014): 267–272

Nanoscale Patterning by AFM Lithography and its Application on the Fabrication

of Silicon Nanowire Devices

(Pencorakan Berskala Nano dengan Litografi AFM dan Aplikasinya dalam Fabrikasi

Peranti Nanowayar Silikon)

SABAR D. HUTAGALUNG*¹², KAM CHUNG LEW¹& TEGUH DARSONO¹

¹School of Materials and Mineral Resources Engineering, Engineering Campus, Universiti Sains Malaysia, 14300 Nibong Tebal, Penang, Malaysia

²Physics Department, Faculty of Science, Jazan University, Jazan, Saudi Arabia

Diserahkan: 7 Januari 2013/Diterima: 19 Julai 2013

ABSTRACT

Many techniques have been applied to fabricate nanostructures via top-down approach such as electron beam lithography. However, most of the techniques are very complicated and involves many process steps, high cost operation as well as the use of hazardous chemicals. Meanwhile, atomic force microscopy (AFM) lithography is a simple technique which is considered maskless and involves only an average cost and less complexity. In AFM lithography, the movement of a probe tip can be controlled to create nanoscale patterns on sample surface. For silicon nanowire (SiNW) fabrication, a conductive tip was operated in non-contact AFM mode to grow nanoscale oxide patterns on silicon-on-insulator (SOI) wafer surface based on local anodic oxidation (LAO) mechanism. The patterned structure was etched through two steps of wet etching processes. First, the TMAH was used as the etchant solution for Si removing. In the second step, diluted HF was used to remove oxide mask in order to produce a completed SiNW based devices. A SiNW based device which is formed by a nanowire channel, source and drain pads with lateral gate structures can be fabricated by well controlling the lithography process (applied tip voltage and writing speed) as well as the etching processes.

Keywords: AFM lithography; nanodevices; nanoscale pattern; silicon nanowire

ABSTRAK

Pelbagai teknik telah digunakan untuk fabrikasi nanostruktur melalui pendekatan atas-bawah seperti litografi alur elektron. Walau bagaimanapun, teknik tersebut sangat rumit dan prosesnya memerlukan banyak langkah, kos operasi tinggi dan menggunakan bahan kimia merbahaya. Manakala, litografi mikroskop daya atom (AFM) merupakan suatu teknik yang mudah serta dapat dikatakan tanpa topeng, melibatkan kos sederhana dan prosesnya tidak rumit. Dalam litografi AFM, pergerakan tip penduga dapat dikawal untuk menghasilkan corak berskala nano pada permukaan sampel. Bagi fabrikasi nanowayar silikon (SiNW), sebatang tip konduktif dioperasikan dalam mod AFM tak-sentuh untuk menumbuhkan corak oksida berskala nano pada permukaan wafer silikon-di atas-penebat (SOI) berdasarkan mekanisme pengoksidaan anod setempat (LAO). Struktur tercorak kemudian dipunar melalui dua langkah proses punaran basah. Pertama, TMAH telah digunakan sebagai larutan punar bagi menghilangkan Si. Langkah kedua, HF yang dicairkan digunakan menghilangkan topeng oksida untuk menghasilkan satu peranti lengkap berasaskan SiNW. Struktur peranti SiNW yang terdiri daripada suatu saluran nanowayar, pad sumber dan longkang dengan get sisi dapat dihasilkan apabila proses litografi (voltan yang dikenakan pada tip dan laju pencorakan) serta proses punaran dikawal dengan baik.

Kata kunci: Corak berskala nano; litografi AFM; nanowayar silikon; peranti nano

REFERENCES

Cervenka, J., Kalousek, R., Bartos, M., Skoda, D., Tomanec, O. & Sikola, T. 2006. Fabrication of nanostructures on Si(100) and GaAs(100) by local anodic oxidation. Applied Surface Science 253: 2373-2378.

Fang, T-H., Wang, T.H. & Wu, K-T. 2008. Local oxidation of titanium films by non-contact atomic force microscopy. Microelectronic Engineering 85: 1616-1623.

Fang, T-H. 2004. Mechanisms of nanooxidation of Si(100) from atomic force microscopy. Microelectronics Journal 35: 701-707.

Fu, E.S., Wang, X-S. & Williams, E.D. 1999. Characterization of structures fabricated by atomic force microscope lithography. Surface Science 438: 58-67.

Giesbers, A.J.M., Zeitler, U., Neubeck, S., Freitag, F., Novoselov, K.S. & Maan, J.C. 2008. Nanolithography and manipulation of graphene using an atomic force microscope. Solid State Communications 147: 366-369.

Gwo, S. 2001. Scanning probe oxidation of Si3N4 masks for nanoscale lithography, micromachining, and selective epitaxial growth on silicon. Journal of Physics and Chemistry of Solids 62: 1673-1687.

Held, R., Heinzel, T., Studerus, P. & Ensslin, K. 1998. Nanolithography by local anodic oxidation of metal films using an atomic force microscope. Physica E: Low-dimensional Systems and Nanostructures 2: 748-752.

Hsu, H-F. & Lee, C-W. 2008. Effects of humidity on nano-oxidation of silicon nitride thin film. Ultramicroscopy 108: 1076-1080.

Hu, X. & Hu, X. 2005. Analysis of the process of anodization with AFM. Ultramicroscopy 105: 57-61.

Hutagalung, S.D., Darsono, T., Yaacob, K.A. & Ahmad, Z.A. 2007. Effects of tip voltage and writing speed on the formation of silicon oxide nanodots patterned by scanning probe lithography. Journal of Scanning Probe Microscopy 2: 28-31.

Hutagalung, S.D. & Lew, K.C. 2011. Current-voltage characteristics of side-gated silicon nanowire transistor fabricated by AFM lithography. Advanced Materials Research 277: 84-89.

Hutagalung, S.D. & Lew, K.C. 2012. Effect of TMAH etching duration on the formation of silicon nanowire transistor patterned by AFM nanolithography. Sains Malaysiana 41: 1023-1028.

Kuramochi, H., Ando, K. & Yokoyama, H. 2003. Effect of humidity on nano-oxidation of p-Si(001) surface. Surface Science 542: 56-63.

Kuramochi, H., Ando, K., Tokizaki, T., Yasutake, M., Perez- Murano, F., Dagata, J.A. & Yokoyama, H. 2004. Large scale high precision nano-oxidation using an atomic force microscope. Surface Science 566-568: 343-348.

Lee, S.K., Lee, S.Y., Rogdakis, K., Jang, C.O., Kim, D.J., Bano, E. & Zekentes, K. 2009. Si nanowire p-FET with asymmetric source-drain I-V characteristics. Solid State Communications 149: 461-463.

Lew, K.C. & Hutagalung, S.D. 2010. Silicon nanowire transistor fabricated by AFM nanolithography followed by wet chemical etching process. International Journal of Nanoscience 9: 289-293.

Nguyen, Q.D. & Elwenspoek, M. 2006. Characterisation of anisotropic etching in KOH using network etch rate function model: Influence of an applied potential in terms of microscopic properties. Journal of Physics: Conference Series 34: 1038-1043.

Park, J.W., Lee, S.S., So, B.S., Jung, Y.H., Kawasegi, N., Morita, N. & Lee, D.W. 2007. Characteristics of mask layer on (100) silicon induced by tribo-nanolithography with diamond tip cantilevers based on AFM. Journal of Materials Processing Technology 187-188: 321-325.

Rosoft, M. 2002. Nano-Surface Chemistry. New York: Marcel Dekker, Inc.

Salem, B., Dhalluin, F., Abed, H., Baron, T., Gentile, P., Pauc, N. & Ferret, P. 2009. Self-connected horizontal silicon nanowire field effect transistor. Solid State Communications 149: 799-801.

Suk, S.D., Yeo, K.H., Cho, K.H., Li, M., Yeoh, Y.Y., Lee, S.Y., Kim, S.M., Yoon, E.J., Kim, M.S., Oh, C.W., Kim, S.H., Kim, D.W. & Park, D. 2008. High-performance twin silicon nanowire MOSFET (TSNWFET) on bulk Si wafer. IEEE Transactions on Nanotechnology 7: 181-184.

Williams & Muller 1996.

Xie, X.N., Chung, H.J., Sow, C.H. & Wee, A.T.S. 2006. Nanoscale materials patterning and engineering by atomic force microscopy nanolithography. Materials Science and Engineering: R: Reports 54: 1-48.

Yoon, C., Kang, J., Yeom, D., Jeong, D.Y. & Kim, S. 2008. Comparison of electrical characteristics of back- and top-gate Si nanowire field-effect transistors. Solid State Communications 148: 293-296.

*Pengarang untuk surat-menyurat; email: mrsabar@eng.usm.my