Title | Interface Characterization of Dry-Etched Emitters |
Author(s) | Caroline Clement, Johannes Seiffe, Marc Hofmann, Jochen Rentsch, Ralf Preu, Volker Naumann, Martina Werner |
Keywords | Passivation, PECVD, Dry Etching, Interface Characterisation |
Topic | Wafer-Based Silicon Solar Cells and Materials Technology |
Subtopic | Silicon Solar Cell Improvements |
Event | 26th EU PVSEC |
Session | 2BV.1.42 |
Pages manuscript | 1353 - 1357 |
ISBN | 3-936338-27-2 |
DOI | 10.4229/26thEUPVSEC2011-2BV.1.42 |
The electrical quality of a diffused phosphorous emitter can be significantly improved by etching back the defect-rich surface region (dead layer). This work focuses on the combination of a dry-etch process of the dead layer and a subsequent inline PECVD deposition of the anti-reflective coating (ARC). As we will show in the present work, the surface passivation of the ARC deposited on the plasma-etched surface is affected by a poor firing stability. At a critical temperature of about 800°C, the firing stability of the plasma-etched samples is no longer guaranteed. Therefore, the characteristics and the composition of the resulting Si/SiNx interface play a decisive role. To investigate the reason for the firing-instability of the dry-etched samples, the interface is analyzed by transmission electron microscopy (TEM) and time-of-flight secondary ion mass spectroscopy (ToF-SIMS). The etch-back emitters show a porous interface structure with a roughness of about 10 to 20 nm and strong blistering effects in the SiNx layer.