# Effectiveness of Electrode Design Methodologies for Fast EDM Slotting of Thick Silicon Wafers
## 1 Introduction  
Due to silicon's distinctive characteristics, including resistance to radiation and high temperature, crystalline perfection, and high conversation efficiency in thermoelectric energy, it has been used widely in electronics and photovoltaic industries [1, 2]. Silicon is utilized to fabricate micro features for micro-electro-mechanical systems (MEMSs), microprocessors, solid-state devices, integrated circuits, computer chips, solar cells, infrared optical technologies, and other components. At present, the applications of silicon are no longer limited to the electronics sector only; it also has a vast application in aerospace, telecommunication, architecture, automobile, textiles, biomedical, and many more fields [3, 4]. Silicon is a brittle material with a low fracture toughness (-1 MPa \(\surd{\rm m}\)) and high hardness (12-14 GPa), which poses several obstacles for machining regarding the material removal rate. Surface defects (micro-cracks), tool wear, low machining efficiency, accuracy, and high cost are some drawbacks of using the conventional machining process for machining silicon, as these processes use cutting force during machining [3]. The two major conventional methods used to slice silicon wafers from ingots are inner diameter (ID) saws and wire saws. However, both techniques have limitations, such aslow efficiency, high surface roughness, high kerf loss, and restriction on the thickness. Defects such as transverse cracks, chipping, saw marks, and waste material have been found in these two processes due to the vibration and deformation of the saw blades and the quick movement of abrasive material in the wire saw. Slicing using multi-wire saws is a cost-effective method for cutting silicon wafers of lower thickness only [5; 6; 7; 8]. Due to the drawbacks of the conventional machining process, new approaches have been developed for machining silicon. Non-traditional/no-contact machining processes that avoid cutting force for machining silicon have recently gained more viability and popularity. Non-conventional techniques like plasma and wet chemical etching were investigated to fabricate micro-electro-mechanical system (MEMS) components in silicon. However, properties such as crystal orientations and masking material selectivity make it very difficult to produce truly three-dimensional structures using these processes. Due to the complexity of producing plasma via the de-ionization of etching gas, plasma is still unsuitable for slicing silicon wafers. Processes like X-ray, _Lithographie_, _Galvanoformung_, _Abformung_--lithography, electroplating, and molding (LIGA), and micro stereolithography are developed to solve these problems, but expensive operational costs restrict their usage [8; 9]. Laser beam machining has excellent potential for fabricating intricate curves and three-dimensional shapes in silicon. It offers remarkable machining speed and is not constrained by material conductivity. However, defects such as micro cracks, thermal flaws, etc., have a negative impact on the surface integrity and efficiency of the fabricated parts. To eliminate these defects for machining silicon using laser beams, research has been going on to develop hybrid methods such as laser-induced plasma micromachining (LIPMM), magnetically controlled LIPMM, etc. [3; 5]. For machining fine details, lithography and chemical etching have been introduced, but the restriction on the minimum feature size due to the wavelength in lithography and the slow machining rate in chemical etching limits the use of silicon machining [10]. Another non-conventional method is electrical discharge machining (EDM), which has the potential for machining hard and difficult-to-cut materials like silicon. It is an electrothermal technique that removes material via melting and vaporizing as a result of the extreme heat generated by the spark that occurs between the workpiece and the tool.