Feature sizes fall as wavelengths shorten

Feature sizes fall as wavelengths shorten
David Manners in Munich The era of ‘sub-wavelength processing’ is with us ‘forever’ according to mask makers Dupont, with chip manufacturers demanding machines that can make feature sizes at least half the wavelength of the light source used. “Customers expect to achieve 50 to 60 per cent of the wavelength by using advanced techniques such as phase shifting, optical proximity correction and advanced binary masks,” said Ken Rygler, executive v-p of Dupont, speaking at the Semicon Europa show in Munich last week. So stepper manufacturers Silicon Valley Group expect to achieve minimum feature sizes of 180nm from a 248nm wavelength; 130nm from 193nm; 100nm from 157nm and 50nm from extreme ultra-violet (EUV). That could be conservative. Intel says it is already achieving, on a production process, 130nm feature sizes from 248nm wavelength UV. “No one’s sure what will happen after 193nm,” said ASML’s Dave Chavoustie. So the company is backing four different routes: the ion beam project supported by MEDEA, the European Euclides EUV programme, the US EUV consortium, and a co-operation with Lucent Technologies and Applied Materials on Scalpel e-beam. Nikon aims to stay with UV until 2006 with a logic road map hitting 100nm in 2003, then a switch to e-beam steppers for 70nm in 2006 and 50nm in 2009. All of which leaves IBM out on a limb with its pursuit of X-rays. X-ray lithography does not show up in any stepper company’s roadmap, yet IBM has just fabricated various chips using X-ray lithography with Oxford Instruments’ synchrotron as the light source. IBM’s X-ray chips included a PowerPC 604e with a critical dimension of 250nm running at 400MHz, a Gigabit DRAM and an SRAM with dimensions down to 130nm.


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