MBE stalwarts concentrate on emerging markets

In a forgotten corner of Paris, tucked away at the end of a one-way street and close to the river Seine, there stands an unprepossessing building. But venture inside and you can witness the very cutting edge of advanced semiconductor production technology.

Here stands Riber, the company that has arguably done more than any other to propel molecular beam epitaxy (MBE) into the production environment. Behind the iron gates guarding its parking lot, in a cleanroom at the heart of the building, nearly a dozen MBE reactors are being prepared for shipment.

It is these new machines that will produce some of the first GaN HEMT epiwafers for high-power RFIC fabrication, organic LED technology for the coolest of displays and solar cells that will become a cornerstone of energy production.

But the MBE equipment business has been no easy ride. With sales of production reactors slowing to a near standstill, Riber s finances have been under pressure. Disappointing financial results were the inevitable outcome, before a new supervisory and executive board began to take shape.

Noël Goutard might not be a familiar name in semiconductor circles. But as the former CEO of automotive equipment multinational Valeo, a company that once cornered the market in clutch systems for cars, he has business experience to burn. In December 2007, Goutard increased his investment in Riber. He then brought in Jean-Pierre Regner, a seasoned executive with 30 years of experience at Philips Semiconductors France as an external consultant – including a stint as wafer fab manager.

Regner s analysis was stark – Riber needed to change. It was not placing enough focus on service and should be integrated much more closely with Addon, its MBE component parts subsidiary. Within a few months, Regner became president of Riber s executive board, with Michel Picault moving to head up the company s systems division, and Addon was fully assimilated under Riber s control.

"We are now focused on three key activities," said Regner. "Systems, sources and service." Systems has long been Riber s core strength – the company has been selling MBE equipment for more than 30 years. Central to the renewed focus on sources was the 2008 fusion with Addon. Spun out of Riber under the direction of Pierre Bouchaib, the man who spearheaded Riber s early MBE activity in the 1970s and 1980s, this part of the business is going to be instrumental in Riber s future. New sources are crucial for the deposition of materials like copper and selenium for thin-film solar, and of more complex chemistries needed for organic transistors and organic LEDs.

Under construction
Bouchaib, now back in the sales director role at Riber, strolls the company corridors, a familiar face to every employee. With a friendly greeting and a pack of Gauloises always at the ready, here is the "godfather" of MBE. Peering into the Class 100 cleanroom where 10 MBE machines are under construction, Bouchaib confidently predicts that all of them will be completed and shipped within a few short weeks. Inside the cleanroom sit reactors large and small, destined for production facilities and research labs, where they will make quantum-dot lasers, organic transistors and more.

Having designed and sold MBE equipment for the past 35 years, Bouchaib is probably as well placed as anybody to predict the future. "Solar cells," is his definitive response. And not just the complex, high-efficiency III-V cells – where the rival MOCVD technology has so far cornered the market – Bouchaib is talking about CdTe and copper indium gallium selenide (CIGS) technologies.

Despite stacks of venture capital funding and its emergence as a high-speed, low-cost production technology (a 750 kW system from Global Solar has just been deployed in Tucson, AZ), there remains a problem with CIGS – specifically in the uniform deposition of the elements required to form CuInxGa1–xSe2 heterojunctions. While there is no requirement for the precision that a typical MBE reactor brings, uniform deposition is needed to produce the cells reliably at good, economic yields.

Indium and gallium can be deposited relatively easily, with good uniformity. However, copper and selenium pose a challenge. If makers of CIGS cells are to solve this problem, which Bouchaib believes will seriously hamper volume CIGS cell production, his name should be at the top of their contacts list.

Riber s engineers, in close collaboration with the expertise developed at Addon, are now adapting the company s MBE sources to provide the kind of deposition speeds that are demanded. So far, they have come up with specially designed crucibles called Muso cells that are compatible with each of the CIGS elements. MC crucibles deliver sulphur and selenium, PG crucibles suit indium and gallium, while the HT version is designed for copper.

Bouchaib s components should be up to the task, so far as film deposition quality is concerned. As ever though, speed is key. CIGS developers want at least 10 µm/h. "I m not sure that we can deliver huge volumes at the moment, and we certainly need to do more development to get to higher volumes, but we think that we can adapt," Bouchaib said. At the moment uniformity is quoted as ±5%, with a material yield of 75% and a flux stability of 1.45%. CIGS companies will want more than this, but the approach is looking promising and Bouchaib believes that the sources are suited to low-cost deposition.

The third plank of Riber s strategy – service – is what precipitated its take over of Oxford Instruments Plasma Technology s (OIPT s) MBE division last year. Although OIPT had sold barely any MBE reactors in recent years, it did have an enormous number still in service, under either its own brand or that of the old VG Semicon group. In a single swipe, this acquisition increased Riber s footprint dramatically. Of the 800 or so MBE machines around the world, some 500 are now serviced by Riber and former OIPT customers will benefit from improvements to their kit, such as software upgrades.

The MBE systems market is now largely the preserve of two vendors – Riber and US rival Veeco Instruments. But in the history of the III-V sector, it is difficult to overstate the importance of Riber s pioneers. Having reinvigorated itself over the past year, it looks set to take on the challenges posed by new applications, customers and materials. Once upon a time, GaAs was that new application. Now Riber is ready to spread its wings beyond III-Vs.   

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