• Elwenspoek, M. C.
• Berenschot, Erwin J. W.
• Hien, Tong Duy
• Wiegerink, Remco
• Krijnen, Gijs J. M.
• Zwijze, R. A. F.

Abstract

In micro electromechanical systems (MEMS) and micro electronic devices there has been a strong demand for the fabrication of electrodes. Platinum (Pt) is a good candidate for this, because it combines some attractive properties: low electrical resistance, high melting point and high chemical stability. However, the latest leads to very difficult for patterning Pt by wet chemical or dry etching. Besides, etching damages the surface making wafer bonding impossible. Lift-off seems to be a solution to this problem. A big problem in using lift-off is that platinum particles or ears may remain at the edges after lift-off. These ears protrude from the surface and may cause electrical shortcuts with an opposite electrode. Some authors reported shortly about a modified lift-off technique to overcome this problem. Before deposition of the metal, a small cavity is etched in the insulator, which is mostly SiO2, thereby breaking the metal during deposition. In this paper the effect of cavity depth and metal thickness on ear forming is investigated. A surface roughness and a resistance of the asdeposited metals are measured. The results of method have been applied successfully for Load Cell sensors in our lab.

Topics

• Deposition
• impedance spectroscopy
• surface
• Platinum
• chemical stability
• forming
• dry etching