Understanding and Use of IR Belt Furnace for Rapid Thermal Firing of Screen-Printed Contacts to Si Solar Cells

We have simulated the rapid thermal firing process using a high-throughput conveyor belt furnace to study the physics of solar cell contact formation in mass production. We show that as sinter dwell time decreases, a lower Ag finger contact resistance is observed. Scanning electron micrographs reveal a correlation between glass thickness at the Ag/Si finger interface and Ag finger contact resistance. Secondary ion mass spectrometry shows that glass-frit and Ag emitter penetration are controlled by sinter dwell time. The observed trends in contact formation lead to lower series resistance, higher fill factors, and greater efficiencies with rapid firing.