Technological Viability and Proof-of-Concept of Applying Low-Temperature PECVD SiNx for Inkjet-Masked Selective Emitters
One of the major barriers for the adoption of selective emitter technology is the trade-off between optimal shielding of minority carriers and increased recombination due to the laser-induced damage. One method to form defect-free self-aligned selective emitters is to use innovative inkjet materials within adapted PERC-processes, like the PECVD of silicon nitride Herein, we utilize a novel UV-Polymer ink as mask in selective etching processes for patterning silicon and, in addition, in a thermally triggered lift-off process for patterning silicon nitride, prior to a self-aligned plating step. To address the thermal stability of the UV-Polymer inks during PECVD, the deposition process needs to be developed at low temperatures. In this work, we first investigate the maximum thermal budget that can be applied on inks during the PECVD passivation process. Based upon this temperature limit, a low temperature PECVD deposition process is developed and both optical and electrical properties of the developed layers are investigated in detail. Deposition at 250°C provided adequate optical properties (n=1.99, k=0.004) and comparable passivation quality to the PERC reference layer. At the same time, 250°C is the process temperature compatible for the innovative UV-Polymer inks investigated in this work.