Eur. Phys. J. Appl. Phys.
Volume 35, Number 1, July 2006
|Page(s)||7 - 12|
|Section||Microelectronics and Optoelectronics|
|Published online||06 July 2006|
Study of bulk micromachining for 〈100〉 silicon
Department of Physics,
University of Tehran, Tehran, Iran
2 Present address: Department of Physics, Islamic Azad University of Hamadan, Hamadan, Iran
3 Thin Film laboratory, ECE Department, University of Tehran, Tehran, Iran
Corresponding author: email@example.com
Revised: 19 February 2006
Accepted: 28 April 2006
Published online: 6 July 2006
Anisotropic etching of silicon is achieved in the presence of ultra-violet exposure in a solution containing hydrofluoric/nitric/acetic acids (HNA). The HNA solution is typically used for polishing silicon and etching polysilicon due to its isotropic etching property. In the technique proposed in this paper which is called UV-HNA, the etching of silicon is enhanced in the direction determined by UV exposure. A mixture of HF/HNO3/CH3COOH with a relative composition of 1:15:5 seems suitable for revealing 〈111〉 planes with an etch rate of 10 μm/h at 35 °C. The bottom of the etched craters is hillock-free and etch rates as high as 60 μm/h can be achieved using higher concentration of HF acid in HNA solution. In the latter case the etching is more isotropic and mask undercut is observed. Also membranes with a depth of 400 μm are fabricated on n-type Si 〈100〉 with a thickness of 500 μm by means of standard 34 wt% solution of KOH at temperature of 60 °C. Problems encountered during the experiment, and their solutions are discussed and results of these experiments are reported.
PACS: 68.37.Hk – Scanning electron microscopy (SEM) (including EBIC) / 68.55.Jk – Structure and morphology; thickness; crystalline orientation and texture / 81.05.Cy – Elemental semiconductors / 82.50.Hp – Processes caused by visible and UV light
© EDP Sciences, 2006
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