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Advanced metrology of Laser Groove Buried Contact processing for silicon CPV

Published online by Cambridge University Press:  15 June 2012

B Maniscalco
Affiliation:
CREST, School of Electronic, Electrical and Systems Engineering, Loughborough University, Loughborough, Leicestershire, LE11 3TU, UK
P M Kaminski
Affiliation:
CREST, School of Electronic, Electrical and Systems Engineering, Loughborough University, Loughborough, Leicestershire, LE11 3TU, UK
K Bass
Affiliation:
CREST, School of Electronic, Electrical and Systems Engineering, Loughborough University, Loughborough, Leicestershire, LE11 3TU, UK
A Abbas
Affiliation:
Department of Materials, Loughborough University, Loughborough, Leicestershire, LE11 3TU, UK
G West
Affiliation:
Department of Materials, Loughborough University, Loughborough, Leicestershire, LE11 3TU, UK
P.N. Rowley
Affiliation:
CREST, School of Electronic, Electrical and Systems Engineering, Loughborough University, Loughborough, Leicestershire, LE11 3TU, UK
G Claudio
Affiliation:
CREST, School of Electronic, Electrical and Systems Engineering, Loughborough University, Loughborough, Leicestershire, LE11 3TU, UK
J M Walls
Affiliation:
CREST, School of Electronic, Electrical and Systems Engineering, Loughborough University, Loughborough, Leicestershire, LE11 3TU, UK
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Abstract

The solar cells employed in low to medium (50 to 200 suns) concentration photovoltaic (CPV) are usually mono-crystalline silicon. Laser Groove Buried Contacts (LGBC) are preferred to screen printing in these cells due to the high currents generated in the system. In this paper, we report on the use of Coherence Correlation Interferometry (CCI) to accurately measure the width and depth of the laser-ablated grooves. In addition, the technique is also used to measure the surface roughness at the bottom of the trenches, since this can determine the success of the subsequent plating process, and at the top surface to optimize the debris control and obtain clean surfaces and well-shaped groove edges. The laser ablation process was also optimized to obtain the groove aspect ratio and surface quality required. Process parameters to be controlled include laser power, pulse energy, stage speed and focal length. The CCI technique is capable of providing all the groove and surface metrology required for this process optimization.

Type
Articles
Copyright
Copyright © Materials Research Society 2012

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References

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