The Revolutionary Choice of LEDs in Photolithography
The Revolutionary Choice of LEDs in Photolithography: A Vision 25 Years Ahead
Nearly 25 years ago, KLOE made a bold and forward-thinking decision to adopt LED technology for its photolithography systems. At the time, LEDs were far from mainstream, especially in high-end microtechnology instrumentation. This strategic choice not only set KLOE apart but also transformed the way scientists approach photolithography today. Here’s why LEDs have proven to be a game-changer:
1. Energy Efficiency
Mercury lamps operate on three-phase power, which is particularly energy-consuming. Moreover, they waste most of their energy as heat and emit broad-spectrum light, much of which goes unused. In contrast, LEDs deliver precise wavelengths, consuming up to 10 times less energy!
2. Longer Lifespan
While mercury lamps start to fade after just a few hundred hours, LEDs last over 10,000 hours with consistent performance throughout their lifespan. This eliminates the need to adjust settings over time to compensate for intensity loss, improving reproducibility while reducing costs significantly. Essentially, light sources are not consumable anymore!
3. Instant On/Off
Mercury lamps require lengthy warm-up periods and must stay on for extended workdays. LEDs, however, are ready instantly, allowing users to turn them on and off as needed. This flexibility maximizes working time, as the source is only activated during exposure, while also enhancing user comfort by eliminating the need to keep the lamp on for extended periods.
4. Tunable Emission
This On/Off capability also enables pulse mode operation, which is particularly useful for homogenizing structures over large areas and minimizing edge effects. Additionally, the power density can be precisely adjusted, offering improved flexibility in dose control by fine-tuning both time and power.
5. Monochromatic Light
Unlike mercury lamps, which emit polychromatic light, LEDs provide precise, single-wavelength emission. This precision not only improves energy efficiency but also avoids undesirable thermal or optical effects on photosensitive materials. Since LEDs do not emit infrared light, the risk of thermal stress or material cracking due to heat is eliminated.
6. Environmentally Friendly
LEDs have a significantly lower environmental impact as they are easier and more cost-effective to recycle compared to mercury lamps. This makes them a more sustainable choice, aligning with current and upcoming EU eco-design regulations and complying with the Minamata Convention on Mercury.
A Choice Aligned with Sustainability
The Minamata Convention, which came into effect in August 2017, aims to reduce mercury's harmful impact on human health and the environment. Mercury, a highly toxic metal, can accumulate in ecosystems, affecting food chains and causing serious health issues. By progressively phasing out mercury in products like light sources, the convention promotes safer and more sustainable alternatives, such as LEDs. These regulations are progressing in Europe and are taking time to be fully implemented, but it is clear that in a few years, all mercury vapor lamps will need to be replaced by LEDs
Thus, many manufacturers are now rushing to adapt their systems to LED technology, but KLOE’s early adoption gave it a unique advantage. By optimizing LEDs specifically for photolithography for nearly 25 years, KLOE set a standard that others still strive to reach.
At KLOE, innovation and sustainability have been at the core of our vision since day one. By choosing LEDs early on, we embraced the future of photolithography while championing eco-friendly microfabrication. It’s a decision we continue to refine and improve every single day, for the benefit of scientists, the environment, and the future of technology.
Finally, one of the last key advantages of LEDs is their ability to optimize light collimation (and consequently the resolution of photolithography instruments) thanks to their intrinsic structure. However, we explore the topic of collimation in greater detail in another article.
