Laser ablation of TCO (SnO 2 : F) coating on glass substrates is of special interest as these films are used as a transparent front contact for the thin film solar cells (TFSC). On the TFSC, in order to archive suitable current voltage characteristic and to reduce the ohmic losses, the panel is separated into multiple cells, which are connected in series. This fabrication process involves multiples coating and 3 steps patterning named P1, P2 and P3. During the P1 process, the TCO coating is scribed in line structure and perfectly isolated for the monolithic serial interconection. On the TFSC, width of the grooves of power-generating thin film layers is one of the most important factors to determine its efficiency because size of dead area, where cannot generate electricity, critically depends on it. Traditionally, mechanical scribing is used to fabricate a channel with typical width of hundreds of micrometer and a typical death zone of ~500 micrometers. Compared with mechanical scribing, laser scribing is able to fabricate a smaller channel width, typically ~ few tens of micrometers, so the dead zone can be much smaller, ~240 micrometers, and therefore higher efficiency (Booth et al. 2010 and Burn et al. 2012). However, traditional scribing process with nanosecond laser pulse, which is governed by heating, melting and vaporizing of TCO, has been show to leave a heat affect zone (HAZ) with poor isolation. In order to reduce the HAZ, ultra-short laser pulse, sub-picosecond pulse, is introduced with an optimization of laser parameters. However, industrial adoption is limited due to the immature process and higher cost of ownership which is typically 2x a typical nanosecond laser scribing process (Booth (2010) and Burn (2012)).Backside scribing, which was first introduced by Avagliano et al. (1994), shows great advantages of HAZ free, recast free, shape edges and perfectly isolated (Avagliano et al. 1999 andHeise et al. 2011). In the backside laser ablation process, laser beam is induced from the glass side and is focused on the surface between glass and TCO coating layer. And the TCO layer is removed by thermal stress induced fracture (Heise et al. 2011). As material is removed without melting and evaporation processes, the fabrication is carried out at the small laser energy, without Bulletin of the JSME
