Ultra-thin wafers for 450mm FD-SOI on schedule

Wafers need to be ready years in advance of a technology shift. Here’s what the supply chain’s doing now.

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While much of the focus on the impending move to 450mm has focused on the equipment challenges, the wafers themselves are of course the primordial consideration. Predictions are starting to mount up linking the move to 450mm with a move to fully-depleted silicon-on-insulator (FD-SOI). So the question needs to be asked: will the wafers be ready?

Engineered substrates like SOI wafers need to be ready years in advance of any major shift in technology – and before much of the rest of the materials and equipment. The fabs and foundries as well as the entire design chain – need real wafers they can work with early on to meet R&D and testbed needs – plus to ensure that volume ramping goes smoothly when the time comes.

450mm wafers for FD-SOI are on target for the industry’s current 450mm deployment plans. (If you want some more info on FD-SOI, see the related blog.)

The current buzz says that 450mm will coincide with the 14nm technology node – around 2015. That’s actually not all that much time for such a big shift – pilot lines will have to be in place in just a couple of years.

FD-SOI requires SOI wafers with very thin top silicon, and current trends also include a very thin layer of insulating buried oxide (BOX). Soitec, the leading SOI wafer manufacturer, is currently in volume ramp for the 300mm version of its Xtreme SOI wafers for FDSOI, shipping thousands of samples every month (wafer giant SEH is producing them, too). In synch with the industry rollout, wafers for 450mm FD-SOI will be ready on schedule, too.

450mm FD-SOI wafers

Both 300mm and 450mm SOI wafers with ultra-thin top silicon and ultra-thin insulating buried oxide (BOX) will ramp to high-volumes on target with the industry's schedules. (Courtesy: Soitec)

Soitec makes wafers of all sizes using their industry-proven Smart Cut(TM) technology. They’ve used it in high-volume production of SOI wafers for over a decade, so there are no surprises there. (To see how they do it, see their ASN article, FD-SOI: The Substrates Are Ready.)

Under the aegis of the European 450mm Equipment and Materials Initiative – or EEMI 450, for short (which we covered last year in ASN), the EV Group and Soitec worked together on the requisite wafer bonding equipment for 450mm SOI wafers. The first system is being delivered to Soitec’s manufacturing facility near Grenoble this fall for test and qualification.

EVG says the EVG850SOI/450-mm runs at production line speed and comprises a cleaning module and pre-bonding module.

So to recap, it’s all systems go for FD-SOI – first for 22nm/300mm, then for 14nm/450mm. FD-SOI is:

  • comparable to FinFETs (which can be bulk or SOI) in terms of speed gain and low-power performance
  • turn-key, and easily manufacturable, both in terms of the technology and the wafers
  • a simpler solution than bulk FinFETS in terms of the design platforms
  • cost competitive and superior to planar bulk CMOS in terms of power-performance

And it will keep right on going through 11nm. The ball is clearly rolling.