<title>Experimental study of micro-EDM machining performances on silicon wafer</title>

Abstract

The micro-EDM silicon machining performances have been studied on a highly doped P-type { 100) silicon wafer. To demonstrate and to emphasis the special performances of silicon micro-EDM, one kind of stainless steel is machined as a reference material. Both materials are sparked with specific sparking energy in micro-Joule energy range and machining characteristics such as material removal mechanism, cutting rate, relative electrode wear ratio and surface quality are examined and analyzed. The thermally induced microcracks are also examined and analyzed using an optical and a Scanning Electron Microscope (SEM). It is found that for silicon, the micro-EDM material removal mechanism is not completely similar to conventional metal micro-EDM; besides melting and evaporation there is a significant contribution from thermal spallation, which is a kind of direct mechanical material damage without melting. This paper also presents that microcrack generation is not only related to the sparking energy but also has a close relationship with the silicon crystal lattice. In order to get microcrack free silicon surfaces, the sparking energy should be controlled to low levels, which are much lower than the voltage levels used in metal micro-EDM. All in all, thermal spalling should be reduced as much as possible, to obtain smooth and crack free machined surfaces.

Fabrication of compliant high aspect ratio silicon microelectrode arrays using micro-wire electrical discharge machining

“…It should be noted that no cracks are visible after the recast layer is removed. This is an indication that the EDM settings (150 V, 3.3 nF) remove the material by melting and not thermal spalling, which would cause thermal shocks and cracks (Song et al 2000). The pre-etch is then followed by etching using HNO 3 :HF mixed in the ratio 4:1 by volume, again for 1 min.…”

“…Heeren et al (1997) successfully fabricated an actuator and sensor using sinker EDM from silicon. Song et al (2000) have investigated the effects of machining characteristics of sinker EDM on silicon.…”

Experimental investigation of wire electrical discharge machining of gallium-doped germanium

“…Thus, this paper investigates the use of wire electrical discharge machining (WEDM) as an alternative process for machining germanium to reduce or even eliminate subsurface damage. Several authors in the past have experimented with EDM of silicon (Luo et al, 1992;Peng and Liao, 2003;Song et al, 2000;Reynaerts et al, 1998;Kunieda and Ojima, 2000;Uno et al, 1999). Luo et al (Luo et al, 1992) and Peng and Liao (Peng and Liao, 2003) investigated the use of WEDM for slicing of silicon wafers.…”

“…Luo et al (Luo et al, 1992) and Peng and Liao (Peng and Liao, 2003) investigated the use of WEDM for slicing of silicon wafers. Song et al (Song et al, 2000) investigated the performance of micro-EDM on highly doped p-type silicon wafers. It was found that not only melting and evaporation but also thermal spalling plays a significant role in the material removal mechanism.…”

Process capabilities of Micro-EDM and its applications

“…Conductive Si3N4-, ZrO2-and Al2O3-based ceramic composites, which have excellent performances in high temperature and high stress applications such as micro gasturbines, can also be machined by micro-EDM [3]. More extended applications are the machining of semi-conducting materials such as silicon [4] and even insulating ceramics like Si3N4 using conductive assisting electrodes [5]. In addition, the implementation of high frequency electrical components in pulse generators, development of accurate motion drive devices and the availability of advanced CNC systems, allows high precision manufacturing and complex 3D micro-structuring [6][7][8].…”