*3.4.4. Mechanical scribing*

The front and rear contacts of the solar cells can be patterned by a process called 'mechanical scribing'. Here, an artificial diamond tip is used to scribe a uniform and shallow depth over a given surface area. The method has the advantage of process simplicity and it can be helpful in patterning the solar cell surface with high throughputs. A mechanical scribing method was used to make grooves for buried contact solar cells [69]. Passivated emitter rear-cell (PERC) solar cells with a back-contact formed by a mechanical scribing process were also reported [11]. Solar cell efficiencies of more than 20% were achieved for such PERC solar cells. An artificial diamond tip of about 10 μm was used to pattern SiOx and SiNx passivation layers, while Sienriched SiNx layers were found to be etched away easily. Solarex Corporation, USA, used a diamond blade to form deep grooves with widths within the range of 25-45 μm for solar cell applications [70]. Mechanical V-texturing for buried contact solar cells on multi-crystalline silicon with a record 17.5% efficiency was also reported [71].
