New High-Throughput Laser for UV Solar Cell Manufacturing

New High-Throughput Laser for UV Solar Cell Manufacturing

Coherent, Inc. introduces a new high-power addition to the widely-acclaimed AVIA laser product line. The AVIA-355-28 delivers output power levels to 28 W at the short ultra-violet wavelength of 355 nm. This represents the highest power level within its class.

The AVIA series of turn-key, pulsed, solid-state lasers has played a pivotal role in accelerating the adoption of laser processing within the solar industry, and is one of the most widely-used lasers in volume production today. Indeed, AVIA lasers have been qualified within numerous cell and panel manufacturing steps for both crystalline-Silicon and Thin-Film production lines.

The new higher power level – at 28 W – provides increased throughput levels (reduced processing time per wafer), aligned with the production line capacities now demanded by solar cell manufacturers. Existing applications such as Edge Isolation and Laser Grooved Buried Contacts stand to benefit immediately from the incremental power level increase – a greater than 20% step up from existing power levels - and the reduced $/Watt capital equipment cost.

The AVIA family of ultra-violet lasers has almost single-handedly proven the benefits of 24/7 laser micromachining on c-Si cells/wafers with short-wavelengths at 355 nm. Such benefits include (i) higher yield levels by matching the laser’s input wavelength to the absorption bands of c-Si / dielectrics, and (ii) increased efficiency by scribing narrower grooves due to tighter focusing from the short-wavelength operation.

It’s not just front surface processes such as laser Edge Isolation and Laser Grooved Buried Contacts that benefit from the higher power levels at 355 nm, the new AVIA-355-28 brings through-via-drilling closer to becoming industrially viable within the solar industry. There is currently a wide range of laser processes within c-Si cell manufacturing that rely upon via-drilling as an essential production step. This includes solar cells incorporating Emitter-Wrap-Through and Metal-Wrap-Through designs where via-drilling forms an integral part of several ‘advanced’ cell concepts proposed by leading research labs. Tiny vias are also required for various ‘contact-opening’ configurations.

In via-drilling, higher-power levels translate directly to increased holes-per-second, and allow solar applications to benefits from UV laser processing techniques learned from Through-Silicon-Via (TSV) progress in the advanced packaging sector. The ability now to drill thousands of holes per second in c-Si wafers with improved sidewall hole quality and wafer structural integrity (compared to 1064-nm laser alternatives) will help move advanced cell concepts from pilot- to full-production status.

The AVIA-355-28 is a Diode-Pumped Solid State (or DPSS) laser, which operates off single-phase electricity and requires no external consumables. Featuring a wealth of software-controlled pulsing options, the AVIA-355-28 is designed as an industrial field-integrated laser for solar production lines, and is comprised of long-lived components with lifetimes of tens of thousands of hours.