ROFIN is the worldwide leader in development and manufacturing of industrial lasers. Backed by over 35 years of experience in laser material processing ROFIN uses this knowledge to develop solutions for almost any laser application in solar cell manufacturing. For the EUPVSEC exhibition the company selected five examples, covering thin film and c-Si technology as well as volume production and research.

Leading laser range for edge deletion

ROFIN is offering the world’s broadest range of laser sources for edge deletion applications. The 800W DQ x80 in fact established itself as the top-selling laser for edge deletion of thin film cells. Furthermore, the new PowerLine L 400 covers the lower end of the spectrum. Using an optimised resonator design, which significantly increases output power, the laser source replaces the PowerLine L 300. For both lasers optimised square fibres are available. Compared with round fibres, square fibres provide the highest efficiency by machining a bigger area per pulse and enabling consistent overlap of individual pulses.

New ECCI code for wafer traceability marking

Wafer marking in solar cell manufacturing is the key to traceability and improved manufacturing processes. DataMatrix codes may be used on solar active areas but they deteriorate in the multitude of coating and etching processes. With the new ECCI code, ROFIN presents a potential solution. Unlike ECC DataMatrix codes, the code is highly resistant against changing contrasts, often found on inhomogenous surfaces like polycrystalline solar cells. As long as anything is visible decoding works – even in case of contrast inversions within the marking. Additionally, ECCI code redundancy is adjustable. Markings which might be subject to heavy wear and tear can use a highly redundant coding.

Femtosecond laser with galvo

At the EUPVSEC ROFIN presents StarFemto, one of the first industrial grade femto second lasers, in combination with an optimised scanner head. It is a setup which offers ideal prerequisites for R&D applications on femtosecond laser technology in photovoltaics. Femtosecond lasers bear a huge potential for a new level of precision and selectivity in applications like thin film structuring and ablation of dielectric layers. Femtosecond lasers process materials faster than energy can diffuse within the atomic lattice and therefore almost no energy diffusion to the surrounding medium takes place. Furthermore, because most of the interaction processes do not depend on linear absorption, virtually any material can be machined by the same laser beam – laser wavelength becomes marginal.

Most versatile lab system for photovoltaics

ROFIN’s PowerLine E 25 SHG is one of the few laser sources that copes with almost all applications in c-Si manufacturing. Thus it is ideally suited for process evaluation. ROFIN combined it with a wafer fixture, an image processing system and a fine tuned, easy-to-use software. With this setup, any R&D lab has the ability to easily evaluate new manufacturing methods for laser doping, SiN backside opening, laser drilling or laser edge isolation, just to name a few.

Perfect tool for mass production of enhanced solar cells

Selective opening of dielectric layers and direct laser doping currently draw a lot of interest in crystalline solar cell manufacturing. For both applications the frequency-doubled PowerLine L 100 SHG already proved its perfect applicability in various research projects and production machines. The laser source offers optimum beam characteristics and sufficient power for large production scale and short cycle time. Green lasers with 532nm show the desired near-surface absorption in silicon and can be equipped with a wide range of optical components and fibres. At the EUPVSEC ROFIN presents for the first time its patent-pending rectangular spot size with a top-hat beam profile.