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HIGH K METALSOLUTION

PRAVEESH.AS7 AE&I

ROLL NO

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Why is this important?

These steps are necessary if transistors are tocontinue shrinking and delivering betterperformance, while containing power consumption

These steps will enable the continuation of MooresLaw, ultimately leading to vast, lower cost computingpower and enabling applications that cannot even beimagined

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MOSFET OVERVIEW

NMOS PMOS( Arsenic , Phosphorous) (Boron)

Fundamental component of all logic chips

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N MOS - working

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What is High k? k, - dielectric constant of a material the

ability to concentrate electric fields.

SiO2 replacement This material should be thicker (to reduce

leakage) but should have a high k valuethe material had to be physically thick but

electrically thin

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Objective in transistor design

Make them smaller, faster, cheaper and Less power--hungry

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MOORES LAW

(Intel co-founder Gordon Moore)

THE NUMBER OF TRANSISTORS ON ACHIP DOUBLE EVERY 2 YEARS

4004 (1971) over 2000 transistorsIntel Quad Core 800 million transistors

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SCALING Reduction in size (increase in density)

W=width of the channel L=channel length =channel carrier mobility C ox =capacitance density associated with gate dielectric

when the underlying channel is in the inverted state Vg=gate voltage Vd =drain voltage Vt =threshold voltage

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SCALING LIMITS AND NEED FOALTERNATE GATE DIELECTR

Increased leakage current

Ultra thin SiO 2 films

Penetration of Boron

Reliability issues

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ROLE OF HIGH-k

the capacitance at the MOS junction

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ADVANTAGES OF HIGH-k

Allows greater physical thickness of oxidelayer.

Improves gate capacitance Reduces leakage, along with present drive

current level

Overcomes the problems of reliability, borondiffusion etc

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MATERIAL CONSIDERATIONS

Some of the key guidelines are briefed here.They include

Permittivity and barrier height Thermodynamic Stability Interface Quality Film Morphology Process compatibility Reliability

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HIGH-K DIELECTRIC CANDIDAMATERIAL DIELECTRIC

CONSTANT(K)

SiO2 3.9

Si3N4 7Al2O3 9Y2O3 15La

2O

330

Ta2O5 26HfO2 25TiO2 80ZrO2 25

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NEW CHALLENGES ASSOCIATED WHIGH K SOLUTION

Method of deposition Availability of precursors Phonon Scattering & low charge-carrier

mobility

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NEW CHALLENGES ASSOCIATED WHIGH K SOLUTION

Precursor must be Volatile High Vapour pressure

Thermal Stability High Absorption Highly reactive

(b) Availability of precursors

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NEW CHALLENGES ASSOCIATED WHIGH K SOLUTION

the interaction between the polysilicon gateelectrode and the new high-k dielectrics.

(C) Phonon Scattering & low charge-carrier mobility

Solution :- Use Metal gate instead of Polysilicon

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NEW CHALLENGES ASSOCIATED WHIGH K METAL SOLUTION

Finding a metal that could be used for the gateelectrode that would combine well with the

new high-k dielectricwork function similar to polysilicons

Adopting new fabrication method

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new fabrication method The normal fabrication method is known as

gate first.- Dopants for the source and drain are

implanted into the silicon on either side of thegate.- the silicon is annealed to repair the damage

from the implantation process transistor process sequence, dubbed gate

last was adopted finally

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PROBLEM SOLVED

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Result

20 percent improvement in transistor

switching speed, and

Reduction in transistor gate leakage by over

10 fold.

Intel processors based on High K Metalsolution are about to hit the market.

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High K Metal in Microprocessor

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THANK YOU