[Leapfrog: First Look]
Transistor Recovers From Midlife Crisis With Fundamental Material Changes
Not since Neil Armstrong took his first steps on the moon has the transistor seen such a dramatic change, and that change holds some big promises.
The semiconductor industry is about to experience a tectonic shift. Wave goodbye to traditional transistors based on polysilicon-gate electrodes and silicon-dioxide (SiO2) dielectric insulators, which had been used to make the transistor gate dielectric for more than 40 years because of its manufacturability and ability to deliver continued transistor performance improvements. Say hello to hafnium-gate dielectric insulators and new non-disclosed metal materials for the NMOS and PMOS transistors that make up CMOS semiconductors (Fig. 1).
Intel is leading this change with the first working 45-nm multicore processors using these novel technologies. The company plans on selling CPUs that use the high-k + metal-gate (HK+MG) stackup in the second half of this year (Fig. 2). Based on the new Penryn die, these CPUs have been tested with the Windows Vista, Mac OS X, and Linux operating systems (Fig. 3).
"Intel has developed a complete high-k plus metal-gate solution, with a high-k gate dielectric and two types of metal gate electrodes optimized for NMOS and PMOS transistors," says Kaizad Mistry, 45-nm Program Manager, Logic Technology Development of the Technology and Manufacturing Group for Intel. Not since 1969 has there been such a dramatic change to transistors.
"These materials have been integrated together to form a reliable and manufacturable 45-nm process technology, which allowed us to demonstrate the world's first working 45-nm CPUs with high-k plus metal-gate transistors just a couple of [months] ago," adds Mistry. "We believe no other company has achieved this level of success with these new transistors." Intel also indicated it has five early version Penryn-based products up and running, and the company plans to build 15 45-nm processors total.
"The implementation of high-k and metal gate materials marks the biggest change in transistor technology since the introduction of polysilicon-gate MOS transistors in the late 1960s," says Intel co-founder Gordon Moore. Compared to its 65-nm counterparts, the 45-nm HK+MG stackup offers higher transistor density, faster switching speed, reduced gate and source-to-drain leakage current, and reduced switching power (see the table).
Along with its research partners AMD, Sony, and Toshiba, IBM announced a similar breakthrough, with plans to use an HK+MG transistor in a server-based IC in 2008. Not to be outdone, Sematech also announced an HK+MG transistor stack. The bandwagon jumping will continue as other fabs follow with their own flavors of HK+MG solutions.
Intel believes these other companies will need a year or two to catch up. In the meantime, creating circuits using 45-nm process technology is still feasible without the combined use of the new materials. However, leakage would be too problematic at 32 nm and below using the older poly plus SiO2 stackup.
Silencing critics who said it couldn't be done while delivering density increases and reductions in leakage currents, these new technologies are helping Intel, IBM, and other companies revive Moore's Law for a few more generations. Intel expects to be at 32 nm in 2009 and 22 nm in 2011.
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