Optimizing process time of laser drilling processes in solar cell manufacturing by coaxial camera control

Volker Jetter; Simon Gutscher; Andreas Blug; Annerose Knorz; Christopher Ahrbeck; Jan Nekarda; Daniel Carl

doi:10.1117/12.2039448

6 March 2014 Optimizing process time of laser drilling processes in solar cell manufacturing by coaxial camera control

Volker Jetter, Simon Gutscher, Andreas Blug, Annerose Knorz, Christopher Ahrbeck, Jan Nekarda, Daniel Carl

Proceedings Volume 8967, Laser Applications in Microelectronic and Optoelectronic Manufacturing (LAMOM) XIX; 896715 (2014) https://doi.org/10.1117/12.2039448
Event: SPIE LASE, 2014, San Francisco, California, United States

Abstract

In emitter wrap through (EWT) solar cells, laser drilling is used to increase the light sensitive area by removing emitter contacts from the front side of the cell. For a cell area of 156 x 156 mm², about 24000 via-holes with a diameter of 60 μm have to be drilled into silicon wafers with a thickness of 200 μm. The processing time of 10 to 20 s is determined by the number of laser pulses required for safely opening every hole on the bottom side. Therefore, the largest wafer thickness occurring in a production line defines the processing time. However, wafer thickness varies by roughly ±20 %. To reduce the processing time, a coaxial camera control system was integrated into the laser scanner. It observes the bottom breakthrough from the front side of the wafer by measuring the process emissions of every single laser pulse. To achieve the frame rates and latency times required by the repetition rate of the laser (10 kHz), a camera based on cellular neural networks (CNN) was used where the images are processed directly on the camera chip by 176 x 144 sensor–processor–elements. One image per laser pulse is processed within 36 μs corresponding to a maximum pulse rate of 25 kHz. The laser is stopped when all of the holes are open on the bottom side. The result is a quality control system in which the processing time of a production line is defined by average instead of maximum wafer thickness.

Citation Download Citation

Volker Jetter, Simon Gutscher, Andreas Blug, Annerose Knorz, Christopher Ahrbeck, Jan Nekarda, and Daniel Carl "Optimizing process time of laser drilling processes in solar cell manufacturing by coaxial camera control", Proc. SPIE 8967, Laser Applications in Microelectronic and Optoelectronic Manufacturing (LAMOM) XIX, 896715 (6 March 2014); https://doi.org/10.1117/12.2039448

ACCESS THE FULL ARTICLE

INSTITUTIONAL
Select your institution to access the SPIE Digital Library.

SELECT YOUR INSTITUTION

PERSONAL
Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.

PERSONAL SIGN IN

No SPIE Account? Create one

PURCHASE THIS CONTENT

SUBSCRIBE TO DIGITAL LIBRARY

50 downloads per 1-year subscription

Members: $195

Non-members: $335 ADD TO CART

25 downloads per 1 - year subscription

Members: $145

Non-members: $250 ADD TO CART

PURCHASE SINGLE ARTICLE

Includes PDF, HTML & Video, when available