Masking complexity

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EUV lithography gets boost from TSMC

One episode of the original Star Trek series featured the legendary quote from chief engineer Montgomery Scott: "I can't change the Laws of Physics!" And the Laws of Physics are one of the problems facing semiconductor manufacturers. The reason is that semiconductor feature sizes are now much smaller than the wavelength of the light being used in their creation. While clever optical tricks are being used to extend optical lithography's useful life, the industry will need at some point to move to the next technology. That point is approaching rapidly, because 193nm lithography – the current work horse – is not expected to last beyond the next three or four years. So what choices do manufacturers have? Two major technologies are available for the future – maskless, or e-beam, lithography and extreme ultraviolet (euv). Maskless is currently the favourite for the short term as the challenges involved in developing euv, including the need for a vacuum and exotic mirror systems, have seen the approach being regarded as tomorrow's technology – and always likely to be. Despite this, Intel has been a major euv champion. TSMC, meanwhile, has been an euv sceptic, preferring to further develop immersion and maskless lithography. But that position appears to be changing, with the foundry about to take delivery of a prototype euv system from ASML. Despite its dominant position in the foundry business, TSMC is a cautious company and wouldn't be making this move unless it was sure that euv has a role to play in its future manufacturing processes. The remaining – and proverbial $64,000 – question is when euv might be in a position to be used 'in anger' in semiconductor manufacture. Originally, euv was expected to be 'inserted' at the 22nm node. But immersion lithography development work has shown the approach is viable at that node. So the semiconductor industry may not use euv until the 13nm node – 2016 or later. But the move will have to be made in the end – optical lithography simply won't scale any further. The fact that TSMC is now in the euv camp may well bring that 'insertion' date forward.