Microscopic machines :

The microprocessor is a complex beast. The complexity of  minimum component costs has increased at a rate of roughly a factor per year.As technology processes, processors shrink in size. The increase in the number of transistors (capacitance) increases the performance of that particular processor. Generally a processor consist of transistors. A transistor is similar to a gate. It stops the flow of current from one side of the gate to the other side. The gate is closed until the transistor is less than a certain 'threshold'. As the voltage crosses the threshold , the gate opens up and lets the current through.Thus a transistor is either ON or OFF depending upon the threshold voltage.

The incredible shrinking through though,throws a wrench to the ideal. As transistors shrink, the wires connecting them shrink and the insulation provided by the transistor gets worse. This can be quoted as an example to a leaking dam with heavy pressure on the bottom. The walls of the dam develops holes and also it gets larger in due course of time, letting more water through.Thus when even the transistor should stop the current, it lets it through (leakage). By this a processor loses as much as 100 watts of current at 45nm.

How can you tame this beast?

Yes  you  can!  Leakage  without  solutions  could  cause  the  processor  to  leak  100 watts  of  at  45nm  and  about  250  watts  in  total. One  part  of  the  solution  is  the implementation  of  a  technology  called  silicon  on  insulator  (SOI),  pioneered  by IBM.  Processors  are  generally  built  on  a substrate  of  silicon. With  SOI ,  the silicon substrate  is  replaced  by  a  sandwich  of  silicon-insulator-silicon.  This improves  the insulation of the transistor gate. Another part of the solution is using a high-k-material,such as hafnium. Replacing the silicon dioxide with the high-k-material allows increased gate capacitance with the leakage effects.