21-02-2010, 12:55 PM
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HIGH-K SOLUTION
INTRODUCTION
MOORE™™S LAW
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
MATERIALS
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
Aluminium oxide
Titanium dioxide
Tantalum pentoxide
Hafnium dioxide
Hafnium silicate
Zirconium oxide
Zirconium silicate
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.
GATE ELECTRODE
PROBLEMS WHEN SiO2 IS REPLACED WITH HIGH-K
Problems arise due to interaction with the Poly-Si gate
Low carrier mobility “electrons slow down
Metal Gate
Using a Metal Gate instead of Polysilicon.
The key property- Work Function of metal.
Tungsten and Molybdenum
Fabrication Methods
Gate First
-Gate dielectrics and gate electrodes are constructed first.
-Source and Drain are constructed next.
-Annealing
-Gate Electrode should withstand the high temperature.
Gate Last
-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.
Summary
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.
HIGH-K SOLUTION
INTRODUCTION
MOORE™™S LAW
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
MATERIALS
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
Aluminium oxide
Titanium dioxide
Tantalum pentoxide
Hafnium dioxide
Hafnium silicate
Zirconium oxide
Zirconium silicate
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.
GATE ELECTRODE
PROBLEMS WHEN SiO2 IS REPLACED WITH HIGH-K
Problems arise due to interaction with the Poly-Si gate
Low carrier mobility “electrons slow down
Metal Gate
Using a Metal Gate instead of Polysilicon.
The key property- Work Function of metal.
Tungsten and Molybdenum
Fabrication Methods
Gate First
-Gate dielectrics and gate electrodes are constructed first.
-Source and Drain are constructed next.
-Annealing
-Gate Electrode should withstand the high temperature.
Gate Last
-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.
Summary
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.