A prediction made by Mr. Gordon Moore
that the number of transistors on a chip double every two years.
RUNNING OUT OF ATOMS
Transistor physical gate length reached 1.2nm in 90nm logic technology.
At this point the dielectric has became
so thin,we are literally running out of atoms for further scaling
WHAT ARE HIGH-K
Thicker class of material known as High-K is likely to replace Silicon oxide.
K stands for dielectric constant, a measure of how much charge a material can hold.
ALTERNATE HIGH K MATERIALS
Problem Associated with Dielectric Layer Formation
Trapped Charge Problem -as a result there will be shift in threshold voltage each time the transistor is turned on.
PROBLEMS WHEN SiO2 IS REPLACED WITH HIGH-K
Problems arise due to interaction with the Poly-Si gate
Low carrier mobility â€œelectrons slow down
Using a Metal Gate instead of Polysilicon.
The key property- Work Function of metal.
Tungsten and Molybdenum
-Gate dielectrics and gate electrodes are constructed first.
-Source and Drain are constructed next.
-Gate Electrode should withstand the high temperature.
-Gate is constructed after the source and drain are formed.
-Research is going on to find the material with right work function that could survive high temperature and enable the industry standard gate first process flow.
With the High K/Metal Gate Transistor it is possible to develop 45 nm technology node.
This will drive Moore's Law into next decade.