IQE has joined a €23 million pan-European project to get VCSEL fabrication ready for volume production in just three years. Compound Semiconductor finds out more

IQE has joined forces with Philips, STMicroelectronics and other Europe-based partners to get VCSEL production ready for volume applications. [IQE]

Faster datacoms, gesture recognition and industrial production are just a few of myriad up and coming applications that cannot function without the GaAs VCSEL. Integrated with other photonics and electronics devices, these III-V components will enable the high speed interconnects of tomorrow's data centres, heat future industrial manufacturing lines and more.

But there's a problem. While VCSELs are fabricated in a way that resembles LED or CMOS processing - growth of epitaxial layers, lithography, metallisation, packaging and optics integration - manufacturing is relatively slow.

Fabrication may well be transitioning to four inch wafers, but substrates are still largely three inch, process control is limited and some production steps are still manual. However, a recently launched pan-European €23 million project could soon change this.

VIDaP - VCSEL pilot line for infrared Illumination, Datacom and Power applications - aims to bring VCSEL manufacturing on par with LED and CMOS manufacturing, in just three years. The project is the latest of some fourteen pilot line projects supported by ENIAC - a European Commission-driven public-private partnership - that aim to boost European competitiveness in nanoelectronics.

This consortium comprises epitaxial material pioneer, IQE, and lighting manufacturing heavyweight, Philips, as well as a host of partners - Sick, STMicroelectronics, Mellanox Technologies and Sidel - each determined to better integrate VCSELs into its chosen application. And a prime focus is the growth of epitaxial layers.

As Andrew Joel, commercial director at IQE puts it: "VCSELs are perhaps the most epitaxially demanding of products. The thickness control requirement is a fraction of 1% from wafer to wafer and run to run, so yields are lower than traditional high volume products, and this has been due to the capability of the equipment."

So, with support from the EC ENIAC program and the Welsh government, the company is to spend nearly €6 million on its VCSEL growth processes, driving up VCSEL throughputs and yields to where LEDs are today. Key priorities include moving to 'state-of-the-art' tools with, for example, in-situ monitoring as well as carrying out more off-line SPC analysis to better understand trends in VCSEL growth processes.

"These devices are typically characterised between runs, so you need to get a fast turnaround in the assessment here," he says. "So we're streamlining this process to increase run rates."

Crucially, the company will be making the move to four inch wafers. IQE has already started production on these larger wafers and is now looking to process more wafers in each run. "The current reactor configuration for an Aixtron 2600 is eight, four inch wafers, but an upgrade tool can take this to twelve four inch wafers which is a pretty significant increase in throughput," says Joel. "This is one obvious step to take but beyond this there are even more tools that offer more wafers per run."

And as IQE optimises epitaxial growth, Philips is ploughing some €9 million into VCSEL fabrication at its ULM plant, Sidel is spending just over €2.5 million on upgrading manufacturing lines while Mellanox, Sick and STMicroelectronics are each contributing hundreds of thousands of Euros, at least, on getting production VCSEL-ready.

As Joel highlights: "Sidel, for example, makes plastic bottles and will replace the halogen lamps used during processing with VCSEL arrays that bring efficiency gains as they switch on quickly and deliver heat to exactly where you want it."

"Meanwhile Philips makes multi-killowatt [infrared power] systems for industrial processes that comprise a huge 2D array of VCSELs," he adds. "These will replace [traditional] heating lamps... and we like this as it gives us a lot of material."

And be it for gesture recognition, camera assistance, proximity sensing and even health monitoring, VCSELs are also making in-roads into mobile devices, with Joel pointing out: "Once you get designed into a cell phone that's a ten million unit hike immediately."

So with the VCSEL set to become the device of choice for such high volume applications, can the likes of IQE and Philips guarantee production processes are ready? Joel thinks so and is certain come the end of the project, production will be at LED and CMOS manufacturing levels.

As he asserts, IQE recently launched a raft of 150mm VCSEL wafer products for such applications, and is seeking additional European projects to set up similar pilot lines across even more applications.

"We have a big drive on material yields, cycle time and growth processes," he says. "Philips for example is designing VCSELs for its own applications. We're now working out how to grow these efficiently at the best possible cost."