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Title:
 
Gentle and Damage Free Ablation of Dielectric Layers Using a Femtosecond Laser Source for High Efficiency Silicon Wafer Solar Cells
 
Author(s):
 
J.M. Yacob Ali, V. Shanmugam, A.G. Aberle, T. Mueller
 
Keywords:
 
c-Si, Laser Processing, Femtosecond Laser, Damage-free Ablation
 
Topic:
 
Silicon Cells
Subtopic: Manufacturing & Production of Si Cells
Event: 35th European Photovoltaic Solar Energy Conference and Exhibition
Session: 2DV.3.57
 
Pages:
 
802 - 804
ISBN: 3-936338-50-7
Paper DOI: 10.4229/35thEUPVSEC20182018-2DV.3.57
 
Price:
 
 
0,00 EUR
 
Document(s): paper, poster
 

Abstract/Summary:


Laser opening of dielectric layers without inducing damage to the underlying substrate is an attractive process simplification for ablation intensive silicon solar cell architectures. In this work, ablation of dielectric layers such as SiNx, AlOx/SiNx stack and SiO2/SiNx stack is carried out using a femtosecond (fs) laser source at two different wavelengths: 343 nm (UV) and 515 mm (green). At 515 nm wavelength, the laser pulses are absorbed in the underlying silicon substrate, causing defects. However, the defects can be minimised by carrying out a gentle ablation process wherein the laser induced damage can be etched off in less than 5 s of chemical etching. At 343 nm wavelength, the laser pulses are mostly absorbed in the dielectric. Hence, it is possible to selectively ablate the dielectric layers by choosing the right pulse fluence and pulse overlap, thus completely avoiding the requirement of post laser chemical etching process. Operating the fs (ultrashort pulse) laser at high pulse fluence induces severe bulk damage that typically requires a prolonged (15 min) chemical etching and therefore should be avoided. Hence, gentle and damage free fs laser ablation process will result in reduced fabrication time, reduced process costs for PV manufacturers applying laser ablation in their processing sequence, and higher wafer/hour throughput.