Sunday, February 25, 2007

45 Nanometer Transistor Technology

Recently Intel announced that it will use 45nm Transisitors in Intel's next generation processors, codenamed Penryn. Those processors will be available in the second half of 2007. At preset it is using 65nm Transistors in Intel Processors.

First let us know what is a nanometer?

There are one billion nanometers in one meter. The first Transistor was built by Bell Labs in 1947. We can hold it with our hand. We can not see the 45nm Transistor with our eye. We need a very advanced microscope to see it. More than 30 million 45nm Transistors could fit on the head of a pin. More than 2000 45nm Transistors could fit across the width of a human hair. More than 2 million 45nm Transistors could fit on the period(.). A 45nm Transistor can switch on and off at 300 billion times per second.

When compared to today's 65nm technology, we get 20 % improvement in Transistor switching speed and the power consumption is reduced by 30 percent in transistor switching. Due to smaller size of transistors we will get benefit of twice the transistor density. The transistor gate oxide leakage is reduced by 10 times.

Now let us know the new technology in 45nm Transistors

A Transistor is a switch that process the ones and zeroes. A gate is used to turn the transistor on and off. A dielectric is used under the gate to separate the gate from the channel where the current flows. The dielectric is nothing but a insulator. Today's 65nm Technology has been using silicon dioxide as gate dielectric, polysilicon in gate electrode. The transistor size reduces as the thickness of the dielectric reduces. The transistor speed increases by reducing gate electrode length and by reducing the thickness of the dielectric. But as the gate dielectric gets thinner, electric leakage increases. Today's gate dielectric thickness is 1.2nm(equal to 5 atomic layers). Now at this stage it becomes impossible to reduce thickness of dielectric further. If we reduce the thickness further then electric leakage increases further and the transistors become over heated and in sometimes they may burn.

So inorder to reduce electric leakage we have to use some other material as dielectric instead of silicon dioxide. So Intel is using a hafnium-based high-k material in the gate dielectric in their new 45nm Transistors. But this high-k dielectric is not compatible with polysilicon gate electrode. Intel replaced this polysilicon by special metals. These special metal gates are well compatible with hafnium gate dielectric. This combination improves performance of transistors to high level with very low current leakage.

Intel continues to maintain Moore's Law with this new 45nm technology. According to Moore's Law (Intel co-founder), the number of transistors on a chip doubles about every two years.

The number of transistors on first Microprocessor(4004) to latest Processors increases like below.

2000 transistors in first Processor, 4004
29000 transistors in 8080
134000 transistors in 80286
275000 transistors in 386
3000000 transistors in Pentium
9500000 transistors in Pentium 3
55000000 transistors in Pentium 4
77000000 transistors in Centrino
230000000 transistors in Pentium D
1720000000 transistors in Itanium 2
290000000 transistors in Intel Core 2 duo
580000000 transistors in Intel Core 2 quad