Martijn Boerkamp is the CTO of Inphocal and a freelance science journalist at Coolscience.

16 February

With its optical system, Inphocal can take focused laser beams beyond their current limitations. This has caught international attention, with the team picking up an Innovation Award at the Consumer Electronics Show in Las Vegas. The HightechXL startup expects the novel laser beams to reach the market already this year.

Everyone who has ever played with a magnifying glass knows that lenses focus light. They’re used in everyday items, such as the camera in your smartphone but also microscopes and telescopes. The principles behind focusing light are well known and already taught in high school. The knowledge has been with us for hundreds of years, since the days of Galileo pointing a telescope towards the heavens and Van Leeuwenhoek discovering a microscopic world. With its application, however, also come limitations that have to be accounted for when designing a system that makes use of it.

Focused light has a wide range of uses. In the semiconductor industry, it’s being employed to separate chips from a wafer, in a process called wafer dicing. This was previously done with a saw. The rough blade, however, can do a lot of damage and to prevent this, there needs to be sufficient space in between the chips. The wasted space means fewer chips fit on a wafer and, with the global chip shortage hitting us hard, more is of course better than less. The yield can be increased using lasers, which can be focused to a very small spot on the wafer. But even this has its limitations, with the laser spot reaching a bounded small size, better known as the “diffraction limit.”

Inphocal Logitec mouse

It’s not the only limit that comes with a focused laser beam. In laser marking, a commonly used technology in the food industry, it’s being used to burn expiration dates directly into materials in a production line. Focusing the laser light generates enough heat to leave an imprint on the product. It does require an object to be placed precisely onto the spot, due to the light quickly diverging after it reaches a focus and losing its ability to leave a mark. This need for precise placement limits the speed of marking and restricts its use to flat objects.

A new optical technology from the Swiss particle institute CERN may just be the answer to overcome some of these limitations. It was developed as part of a project for the precise placement of components inside the huge Large Hadron Collider tunnel. It required optical technology that uses a laser beam with little diffraction. This optical beam technology was made available by CERN’s Knowledge Transfer department in 2018, where it was picked up by the Eindhoven-based HightechXL incubator. Within its 9-month Venture Building program, the startup Inphocal saw the potential to shake up the laser processing market. It’s working with the technology based on the CERN patent and in the process of signing a license agreement.

Longer focus

The uniqueness of this novel laser beam lies in its structure, which is obtained by a set of optical components that transforms almost any laser beam into a concentric beam, consisting of a central spot surrounded by rings. The center maintains a high amount of power over a relatively long distance, thereby significantly extending the focus region. On the other hand, when the beam is focused, its intense central spot becomes smaller than a diffraction-limited laser spot. Both characteristics take the technology beyond the limits set by conventional optics.

Inphocal machine prototype
Inphocal has built a prototype using technology based on the CERN patent.

The longer focus speeds up laser marking in production lines in two ways. The laser beam can go faster when being moved with a scanner, allowing more code or images to be imprinted within the same timeframe. Additionally, the laser marking window is widened, making it possible to start earlier and finish later. More than ten times the amount of content can be inscribed compared to conventional laser marking systems. This renders the technology competitive with inkjet while providing a cleaner printing alternative.

The longer focus depth opens the door for laser marking on any kind of shape or size. There are systems on the market that can actively adjust the focus, but these require sensing the shape and adjusting the lens position accordingly. This is a time-consuming process and doesn’t work in a fast-moving production line. Inphocal is investigating the use of its long focus beam for direct marking of logos and traceability codes onto fruit and vegetables together with the company Nature’s Pride. It would eliminate the use of stickers and labels and significantly reduce plastic waste.

Inphocal avocado

A longer focus potentially has an equally huge impact on laser cutting through thick pieces of steel. The cutting process creates a trench with high walls that cut off the incoming laser light. A factor of ten in cutting efficiency is already lost after the first centimeter. Additional laser power is pumped into the process to overcome the loss, narrowing the field of application to users who can afford extremely high-power laser equipment. A longer focus would overcome this loss in efficiency and puts lower requirements on the necessary laser power.

In wafer dicing, focusing light to a smaller spot reduces the so-called “heat-affected zone,” which can damage chips if it’s too big. Chipmakers account for this in their design by creating “streets” in between the chips, spaces that are large enough for the chips not to become damaged. Having a smaller heat-affected zone reduces the number of damaged chips, but it also allows more chips to be placed on a wafer, with less space wasted in the streets. Both increase the yield, making it a sustainable way of solving the current global chip shortage.

Big difference

The laser processing industry still mostly relies on conventional optics. What Inphocal adds, isn’t something completely new but an improvement in the process. The company aims to become the standard in laser processing by 2025, following a phased approach. Its first systems are ready for production – to be used for paid pilot testing for laser marking applications in production lines. Simultaneously, it will invest heavily in R&D to explore other promising markets.

To make big steps in wafer dicing, Inphocal is closely collaborating with the Optics department of Delft University of Technology. They already have support from some of the bigger players in the semiconductor industry. With the current partnerships, they aim to create an ideal triangle: they have a disruptive technology that still requires some fundamental research but, at the same time, allows for fast market penetration. Extending its application to the multi-trillion euro semiconductor market has the potential of making a big difference, as even adding a small percentage of extra yield results in a large increase in chip production.

Edited by Nieke Roos