Yorkfield: What’s New
In the previous part of our review we have briefly pointed out the main differences between the Core 2 Extreme QX9650 and its predecessor. Now it’s time to take a closer look at the innovations that the Penryn processor family will boast.
45nm Technological Process
We will start discussing the peculiarities of the new processors with the new manufacturing process. It was the 45nm process that actually created Penryn CPUs. It allowed not only increasing the complexity of the die thanks to enhancements made to the processor’s functional units, but also allowed reducing the processor Vcore and heat dissipation and guaranteed the ability to increase the core frequency in the future.
The new production technology is extremely interesting also because Intel has to actually perform tremendous amount of research. As a result, classical materials (such as silicon oxide), which had been used since 1960s to manufacture transistors, were replaced with absolutely new ones (rare-earth hafnium based compound). The new 45nm transistors use metal gate made of polysilicon and a high-k dielectric – hafnium silicide.
These changes in the semiconductor elements design help solve a few acute problems at the same time. New 45nm technological process almost doubled the transistor density on the die. Besides, it increases their switching speed by about 20% and reduce the power needed for that by about 30%. Also the use of new materials allows reducing leakage current significantly: in source-drain leakage power by the factor of 5 and in gate oxide leakage power – by the factor of 10.
I have to say that it would hardly be possible to get to 45nm production process without involving new materials. The thing is that older transistors with gate dielectric of silicon oxide lose their primary features when miniaturized for the sake of higher switch speed. In 65nm semiconductor devices, the dielectric layer became only 5 atoms thin already. Further thinning of this layer for even better performance of the semiconductor devices would have made it unable to keep the electrons outside. The new high-k dielectric solves this problem: it allows increasing the gate dielectric layer thickness without losing any of the transistor speed.
As for replacing the polysilicon gate with metal one, this is a partially forced measure. It was necessary because the hafnium silicide dielectric appeared incompatible with the old material on the quantum level, which led to lower transistor performance.
Just like before, they manufacture 45nm processors using copper interconnects, 300mm wafers and 193nm lithography. So, the new production process didn’t require Intel to replace most of its manufacturing equipment. This gives us hope that mass production of new Penryn processors shouldn’t hit against any significant obstacles and will deliver high chip yields.
Thanks to the new production technology Intel is planning on increasing the clock speeds of its Core 2 Quad processors up to 3.0GHz, and of Core 2 Duo – up to 3.33GHz within the next year, while their TDP will remain within the common 95W and 65W respectively. As for the frequencies of the top quad-core processor models for enthusiasts, that boast typical heat dissipation of 130W, they will hit 3.2GHz. Intel, however, is going to do one more thing in order to increase their performance even more: they will shift to faster 1600MHz bus.