AVS 51st International Symposium
    Plasma Science and Technology Tuesday Sessions
       Session PS1-TuM

Paper PS1-TuM5
A Novel Etching Process Employing Pulse-Modulated Electron-Beam-Excited Plasma for Fabrication of Micro-Optical Devices

Tuesday, November 16, 2004, 9:40 am, Room 213A

Session: Dielectric Etching
Presenter: K. Takeda, Nagoya University, Japan
Authors: K. Takeda, Nagoya University, Japan
Y. Tomekawa, Wakayama University, Japan
T. Ohta, Wakayama University, Japan
K. Yamakawa, Nagoya University, Japan
M. Ito, Wakayama University, Japan
M. Hori, Nagoya University, Japan
Correspondent: Click to Email
Recently, micromachining of optical devices such as core lens on the edge of optical fiber attracts much attention. In this process, the fast atomic-beam etching (FABE) or the ion-beam etching (IBE) has been employed, since the conventional reactive plasma etching cannot be employed as the radio-frequency self-biasing is not efficiently supplied to the thick dielectric materials. However, the etch rates of FABE and IBE are typically around a few tens nm/min, which are very low compared with the reactive ion etching. Therefore, novel processes to realize the higher etch rate are strongly required to reduce the processing time. We have proposed a SiO@sub2@ etching employing an electron-beam-excited plasma (EBEP) for the fabrication of micro-optical devices. The dc-EBEP have realized the high etch rate without any additional bias power supply. However, it had problems such as the thermal damage of the photo resist, non etch-uniformity and instability of plasmas. In this study, we have developed a novel etching process for the fabrication of micro-optical devices employing a pulse-modulated EBEP and have investigated the etching characteristics. Plasma was generated at a total pressure of 0.27Pa and the fed gases were C@sub4@F@sub8@/Ar, a discharge current of 25A and an electron beam acceleration-voltage (V@subA@) of 100V with a pulse-modulation frequency of 50kHz and 50% duty ratio. The pulse-modulated EBEP have been found to have a great potential to realize the high etch rate of 375nm/min with 0.75mm hole-pattern and improve some problems in the dc-EBEP. Moreover, from the results of the optical emission spectroscopy, F atom density was reduced with the decrease of the duty ratio of V@subA@. Therefore, We performed the anisotropic SiO@sub2@ etching with a high rate by the ion assisted etching without any self-biasing power supply. Consequently, the micro-fabrication of core lens on the edge of optical fiber was successfully carried out.