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. 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. 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." 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
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