[OPTICAL REVIEW Vol. 13, No. 4 (2006) 225-227]
© 2006 The Optical Society of Japan

Electroless Nickel Plating under Continuous Ultrasonic Irradiation to Fabricate a Near-Field Probe Whose Metal Coat Decreases in Thickness toward the Tip

Yuichi SAITO*, Shuji MONONOBE1,†, Motoichi OHTSU2 and Hideo HONMA

Graduate School of Engineering, Kanto Gakuin University, Mutsuurahigashi, Kanazawa-ku, Yokohama 236-8501, Japan
1Kanagawa Academy of Science and Technology, KSP East 409, 3-2-1 Sakado, Takatsu-ku, Kawasaki 213-0012, Japan
2Department of Electronics Engineering, University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-8656, Japan

(Received November 15, 2005; Accepted December 16, 2005)

This paper describes a size-dependent electroless plating method to fabricate a new type of probe with a locally decreasing thickness of metal and a tiny tip size for a combined high resolution shear-force and near-field optical microscope. In this method, the tip size and decreasing thickness profile, which affect the resolution capabilities of the microscopes, are controlled by adding a continuous ultrasonic wave with a frequency of 1 MHz to a nickel plating bath. The probe with a tip radius of curvature of 25 nm was successfully fabricated at an ultrasonic power density of 1.6 W cm-2, its metal thickness gradually decreased from 850 to 20 nm toward the distal tip.

Key words: electroless plating, metallization, ultrasonic wave, optical fiber, SNOM, NSOM, etching, non-contact atomic force microscope

*Present address: Surface Engineering Research Institute, Kanto Gakuin University, 4-4-1 Ikeda-cho, Yokosuka, Kanagawa 239-0806, Japan.
Present address: Department of Mechanical Engineering, Toyo University, Kawagoe, Saitama 350-8585, Japan.