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*¹, KAM CHUNG LEW²& TEGUH DARSONO²

¹Physics Department, Faculty of Science, Jazan University, Jazan, Saudi Arabia

²School of Materials and Mineral Resources Engineering, Engineering Campus, Universiti Sains Malaysia, 14300 Nibong Tebal, Penang, Malaysia

Received: 7 January 2013/Accepted: 19 July 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

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*Corresponding author; email: mrsabar@eng.usm.my