Intel Corp. started 2007 with a bang with a breakthrough in transistor design, one of the biggest advancements in 40 years. In fact, 45nm high-k then became one of the buzzwords early on as Intel drew first blood in its highly intense battle for processor supremacy.
Now, the company is on its way on ending the year on a high note as it speeds past other chipmakers who are still months away from having production-ready 45nm chips. Intel in November introduced its Penryn 45nm processors using high-k dielectric gate insulator to control leakage current.
Three Intel researchers Robert Chau, Intel Senior Fellow, technology and manufacturing group director, transistor research and nanotechnology; Kaizad Mistry, 45nm program manager, logic technology development, technology and manufacturing Group; and Tahir Ghani, Fellow TMG, Portland technology development director, transistor technology and integration who were part of the team behind the 45nm high-k metal gate success, talk about the highs and lows of the project and what motivated them to press on and move on to more challenging endeavors.
EE Times Asia: Can you walk us through the discovery process of the high-k materials? How long did the whole process take and how tough was it?
Mistry: In the late 1990s, we realized that silicon dioxide was running out of steam so at that point we started a research effort on finding the appropriate hi-k dielectric material. This was started under Robert's group.
Chau: Yeah, we felt that we need to look at a high-k material with higher dielectric constant. We started looking at different materials for a number of years, before we zero in on a couple of materials.
How many materials where you considering then?
Chau: We were looking at multiple materials, a wide range actually.
Mistry: I think it is in the range of five to 15 different kinds of materials, different flavors of different high-k materials.
Ghani: I think during the research phase, around 2001 to early 2002, we began to see data that it is very difficult to integrate high-k with polysilicon gates which was historically used by the industry in the last 40 years. Therefore, at that time, Robert's group looked at a range of different metals.
There are two different types of transistors: PMOS and NMOS. So there were two different metals with different electrical requirements needed for MMC devices. At that time, the number of metals Robert's team looked at was significantly more than the number of high-k materials being looked at that time.
Mistry: So we were looking between five to 15 different high-k materials, and then we realized that fundamentally high-k materials were not compatible with polysilicon gates, which was around the turn of the decade. So at that point we started to look at not just the high-k material, but the two independent metal gates materials that provided the right electrical properties for NMOS and PMOS and were compatible with whatever high-k materials we chose.
So it really became a choice of three separate materials that have to work together and that process of choosing the right metal gate material that we tried with five or more high-k materials.