Exitech makes its mark in materials processing

17 Jun 2002

Expertise in drilling microscopic holes and patterning the surface of thin films is creating lucrative business opportunities for a UK laser firm, discovers Vanessa Spedding.

From Opto & Laser Europe June 2002

A company that seems to know instinctively how to ride out the downturns, Exitech is now experiencing a growth spurt. The UK laser system integrator, which sported a turnover of more than $15 m (EURO 16.4 m) in 2001, has just moved to a new site on the outskirts of Oxford which gives it three times more space (56 000 sq. ft).

Founded in 1984 as a small spin-off from the Rutherford Appleton Laboratory, UK, Exitech today boasts more than 70 employees and has overseas offices in Japan and the US. The secret of its business success seems to be its uninhibited approach to diversifying into new application areas, coupled with a focus on customer needs - supplying custom-built, perfect-for-the-job machinery for just about any process involving laser microfabrication.Of course, its machines don't come cheap. A typical platform can cost £500 000 (EURO 800 000) and take six months to put together. But by the end of that development period the customer could be equipped, for example, with a system that enables nanometre-perfect scribing of silicon wafers for solar-cell photovoltaics; performs pixel-scale patterning of thin films for LCD displays; or writes fibre Bragg gratings for optical communications.

These are just a few examples of the contents of Exitech's portfolio. How does the company do it? Malcolm Gower, chairman and technical director of the firm and one of its founders (the other being managing director Phil Rumsby), explained: "We are an innovative company and we make a point of employing highly trained people. Also, we are extremely customer driven. The advantage for us is that we always know that there is a need for what we're trying to develop. Our philosophy is that the customers are the experts - no-one knows the applications better than they do. We listen when people approach us and try to adapt our technology to suit their needs."

Over recent years, six core application areas have emerged for the company and it has organized itself accordingly, building up specialized expertise in each one. These sectors - micromachining, hole drilling, photonics, photovoltaics, displays and semiconductors - call on different techniques and approaches. "We use pretty much all classes of laser," continued Gower, "solid-state, CO₂ and excimer, femtosecond, and so on. Anything that might be of industrial interest."

Exitech's engineers are expert at drilling microscopic holes. For example, they have honed the art of creating microvia holes to facilitate electrical interconnects on printed circuit boards. They use a dual-laser approach to deal with the three-layer, two-material composition of the substrate: first, holes in the uppermost copper layer are trepanned to 50-100 µm in diameter using a UV laser. The exposed dielectric underneath is then drilled with a CO₂ infrared laser using the copper as a mask. This part of the process self-terminates when the beam reaches another copper layer beneath the dielectric. Exitech offers a platform that drills a staggering 10 000 complete holes per second by this process.

"We probably have the fastest drilling technology around, although there is lots of competition - especially in Japan. We have licensed our technology to US firm Excellon and are working with them to satisfy the volume market," explained Gower.

Microfabrication is the common theme across all of Exitech's divisions. The ability to develop innovative solutions for the aspects of new and burgeoning industries that require them looks set to guarantee the company's growth for some time to come. The observation that plasma displays were taking off and that traditional chemical-etching processes were not coping with the increasing size of the displays, for example, led Exitech to develop a laser approach to patterning thin films.

The technique employs a high repetition-rate Nd-YAG laser to remove a layer of indium tin oxide from the substrate, leaving pixels of a diameter of 200-250 µm. The Exitech display-panel processing tool creates 12 000 pixels a second with a positional accuracy of 1 part in 10¹².

The company's photovoltaics processing technology is equally inventive. It has developed tools that can create a grooved grid, in poly- or single-crystalline silicon wafers, with grooves 20 µm wide and 30 µm deep using a 1.06 µm Nd laser. Fabrication of micro-optical elements, biochips and microelectromechanical systems is also on the list of can-dos, as is making microstepper tools for research into 157 nm and EUV semiconductor lithography. "With this we are moving towards nanometrology," said Gower. "The tools create feature sizes down to 30 nm and positioning can be achieved to within a few nanometres using laser and interferometry techniques. We are heading towards control almost at the single atom level."

Just about the only area in which Exitech is not particularly active at the moment is the fibre-optics sector. "The photonics market is dormant at the moment," Gower conceded, "but this is compensated for by the growing use of lasers within the displays sector. Meanwhile the solar-power market is steady, and we think hole-drilling applications will continue to grow. There are lots of opportunities for new laser processes within the semiconductor industry too, but it's hard to say yet what form they will take."It's not just the company's eye for new applications and its innovative approach to problem-solving that is taking it forward. Its management - Gower in particular - also displays a valuable acumen when it comes to funding the outfit.

From the outset, Exitech has gained an advantage from collaboration, grants and funding from UK and European establishments. It is currently benefiting from the LINK and Eureka programmes run by the UK government's Department of Trade and Industry (DTI), and has links with more than a dozen UK research institutes.

The European Union's Brite-Euram and Esprit programmes are also feeding into some of Exitech's work. "There are great benefits in obtaining state funding for pre-competitive R&D," acknowledged Gower. "Of course, we never get more than 50% of the investment: we have to find the other 50% ourselves. But there are a number of benefits which are not necessarily quantifiable - for example, working with potential customers, learning of new industrial areas that they are likely to develop or move into, and learning about new laser technologies from researchers in academia."

Other grants are enabling the company to build on the expertise it already has. One example is its exploration of the possibility of taking rapid prototyping to the sub-micron level. "There are always imperatives to make the machines more user-friendly, more flexible, more efficient at meeting customers' new desires and needs," said Gower.

Exitech www.exitech.co.uk