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HighHigh--K Dielectric Materials K Dielectric Materials In MicroelectronicsIn Microelectronics
NAME: Neha TomarNAME: Neha Tomar
IIT GUWAHATIIIT GUWAHATI
OUTLINEOUTLINEINTRODUCTIONINTRODUCTIONMOOREMOORE’’S LAW AND TRANSISTOR SCALINGS LAW AND TRANSISTOR SCALINGWHY HIGHWHY HIGH--K DIELECTRICS?K DIELECTRICS?
APPLICATIONS IN MICROELECTRONICS APPLICATIONS IN MICROELECTRONICS HIGHHIGH--K DIELECTRICS IN DRAMS K DIELECTRICS IN DRAMS HIGHHIGH--K GATE DIELECTRICSK GATE DIELECTRICS
SUMMARYSUMMARY
HIGHHIGH--K DIELECTRICS IN MICROELECTRONICSK DIELECTRICS IN MICROELECTRONICS
INTRODUCTIONINTRODUCTIONMOOREMOORE’’S LAWS LAW
HIGHHIGH--K DIELECTRICS IN MICROELECTRONICSK DIELECTRICS IN MICROELECTRONICS
A prediction made by Mr. Gordon Moorethat the number of transistors on a chip double every two years.
HIGHHIGH--K DIELECTRICS IN MICROELECTRONICSK DIELECTRICS IN MICROELECTRONICS
INTRODUCTION
•Transistor physical
gate length will reach
~15nm before
end of this decade, and ~10nm early next decade
HIGHHIGH--K DIELECTRICS IN MICROELECTONICSK DIELECTRICS IN MICROELECTONICS
PROBLEM AS TRANSISTOR IS MADESMALLER.
INTRODUCTION
Gate dielectric ,Silicon dioxide are only a few atomic layers thick now.
Leakage current increases, as thickness decreases.
A New dielectric material is needed to reduce leakage current.
HIGHHIGH--K DIELECTRICS IN MICROELECTONICSK DIELECTRICS IN MICROELECTONICS
INTRODUCTION
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.
WHAT ARE HIGH-K MATERIALS?
HIGHHIGH--K DIELECTRICS IN MICROELECTONICSK DIELECTRICS IN MICROELECTONICS
INTRODUCTIONHIGH-K MATERIAL BENEFITS
Sio2Sio2 HighHigh--k k CapacitanceCapacitance 1*1* 1.6*1.6*LeakageLeakage 1*1* < 0.01*< 0.01*
HIGHHIGH--K DIELECTRICS IN MICROELECTRONICSK DIELECTRICS IN MICROELECTRONICS
TRANSISTORA simple switch Current flows source to drain when a certain Voltage is applied on The gate, otherwiseDoesn’t flow.
HIGH-K GATE STACKS
Schematic of important regionsOf field effect transistor gate stack
APPLICATIONS IN MICROELECTRONICS
HIGHHIGH--K DIELECTRICS IN MICROELECTRONICSK DIELECTRICS IN MICROELECTRONICS
Scaling limits for current Gate DielectricsSilicon dioxide is current gate dielectrics
So, Continual scaling.will require high-K
material for dielectric layer.
Sio2 thickness can’t be decreased less than 1-1.5nm, becauseleakage currentincreases
HIGH-K GATE STACKSAPPLICATIONS IN MICROELECTRONICS
HIGHHIGH--K DIELECTRICS IN MICROELECTRONICSK DIELECTRICS IN MICROELECTRONICS
ALTERNATIVE HIGH-K GATE DIELECTRICS
Metal oxides of ZrO2, HfO2, Y2O3 and Al2O3
HighHigh--KKmaterialmaterial
Dielectric Dielectric constantconstant
LeakageLeakageCurrent Current reductionreduction
Thermal Thermal stabilitystabilityTmax Tmax ‘‘cc
ZrO2ZrO2 ~23~23 *10*1044--101055 ~900~900HfO2HfO2 ~20~20 *10*1044--101055 ~950~950Y2O3Y2O3 ~15~15 *10*1044--101055 Silicate Silicate
formation formation Al2O3Al2O3 ~10~10 *10*1022--101033 ~1000~1000
HIGH-K GATE STACKSAPPLICATIONS IN MICROELECTRONICS
HIGHHIGH--K DIELECTRICS IN MICROELECTRONICSK DIELECTRICS IN MICROELECTRONICS
Pseudo binary materials(HfO2)x (SiO2)1-x and (ZrO2)x(SiO2)1-x
ALTERNATIVE HIGH-K GATE DIELECTRICS
Silicate-Si interfaceis chemically similarto the SiO2-Si Interface.
Low defect densities
HIGH-K GATE STACKS
Hf-silicate between Si layer
APPLICATIONS IN MICROELECTRONICS
HIGHHIGH--K DIELECTRICS IN MICROELECTRONICSK DIELECTRICS IN MICROELECTRONICS
Pseudo binary materials(HfO2)x (SiO2)1-x and (ZrO2)x(SiO2)1-x
ALTERNATIVE HIGH-K GATE DIELECTRICS
Silicate-Si interfaceis chemically similarto the SiO2-Si Interface.
Low defect densities
HIGH-K GATE STACKS
Hf-silicate between Si layer
APPLICATIONS IN MICROELECTRONICS
HIGHHIGH--K DIELECTRICS IN MICROELECTRONICSK DIELECTRICS IN MICROELECTRONICS
APPLICATIONS IN MICROELECTRONICS
KEY GUIDELINES FOR SELECTING AN ALTERNATIVE GATE DIELECTRIC
Interface qualityPermittivity and band gapThermodynamic stabilityCompatibility with the current or expected materialsto be used in processing for CMOS devicesReliability
HIGH-K GATE STACKS
APPLICATIONS IN MICROELECTRONICS
HIGHHIGH--K DIELECTRICS IN MICROELECTRONICSK DIELECTRICS IN MICROELECTRONICS
HIGH-K GATE STACKS
PROCESS ISSUES THAT AFFECT DEVICE
Pre-deposition treatmentsHF last,O3 etc.
Pre/post-depositionannealingO2 and N2 annealing etc.
High-k depositionALD,CVD etc.
Gate electrodemetal gates, poly-silicongates etc.
APPLICATIONS IN MICROELECTRONICS
HIGHHIGH--K DIELECTRICS IN MICROELECTRONICSK DIELECTRICS IN MICROELECTRONICS
HIGH-K GATE STACKS
GATE ELECTRODE
Problems arise due to interaction with the Poly-Si gate
Phonon Scattering –electrons slow down
Threshold voltage pinning-Due to defects that arise at the gate-dielectric/gate electrode
PROBLEMS WHEN SiO2 IS REPLACED WITH HIGH-K
APPLICATIONS IN MICROELECTRONICSHIGH-K DIELECTRICS IN DRAMS
HIGHHIGH--K DIELECTRICS IN MICROELECTRONICSK DIELECTRICS IN MICROELECTRONICS
GATE ELECTRODE
SOLUTION-METAL GATE
HIGHHIGH--K DIELECTRICS IN MICROELECTRONICSK DIELECTRICS IN MICROELECTRONICS
APPLICATIONS IN MICROELECTRONICS
STATE-OF-THE-ART TRANSISTOR
HIGH-K GATE STACKS
Other technologies are also emerging for low-powerand high-performance logic. For exampleNanoelectronic devices, SOI, double gateand tri-gate etc.
Metal gate and high-K dielectric transistor offerthe promise toward CMOS Technology nodes.
HIGHHIGH--K DIELECTRICS IN MICROELECTRONICSK DIELECTRICS IN MICROELECTRONICS
APPLICATIONS IN MICROELECTRONICSHIGH-K DIELECTRICS FOR DRAMS
WHAT IS DRAM?
DRAM is a type of random access memory that stores each bit of data in a separate capacitor.
HIGHHIGH--K DIELECTRICS IN MICROELECTRONICSK DIELECTRICS IN MICROELECTRONICS
APPLICATIONS IN MICROELECTRONICSHIGH-K DIELECTRICS FOR DRAMS
The continuous “shrinking technology” up to Gbit density exposes many challenges.
Sio2 can not be made thinner any more.
Alternative dielectric having a substantially higher permittivity is needed for further high density DRAMs.
APPLICATIONS IN MICROELECTRONICS
HIGHHIGH--K DIELECTRICS IN MICROELECTRONICSK DIELECTRICS IN MICROELECTRONICS
HIGH-K DIELECTRICS FOR DRAMSALTERNATIVE HIGH-K DIELECTRICS FOR DRAMS
Among this, BST film is the most promising capacitor material in future DRAM applications.
APPLICATIONS IN MICROELECTRONICS
HIGHHIGH--K DIELECTRICS IN MICROELECTRONICSK DIELECTRICS IN MICROELECTRONICS
HIGH-K DIELECTRICS FOR DRAMS
Cross-section TEMImage of a stacked-capacitorStructure with a BST dielectricPt electrode and a TaSiN barrier layer.Minimum feature size=0.2umDielectric thickness=27 nm
BST capacitor structure with the stacked barrier scheme.
HIGH-K DIELECTRICS FOR DRAMS
HIGHHIGH--K DIELECTRICS IN MICROELECTRONICSK DIELECTRICS IN MICROELECTRONICS
APPLICATIONS IN MICROELECTRONICS
Factors that influence BST thin film properties
Processing methodsFilm compositionCrystalline structureMicrostructure Surface morphologyFilm thickness
HIGH-K DIELECTRICS FOR DRAMSAPPLICATIONS IN MICROELECTRONICS
HIGHHIGH--K DIELECTRICS IN MICROELECTRONICSK DIELECTRICS IN MICROELECTRONICS
Process Integration
Main Points
BST deposition techniques
Electrode material & Barriers
HIGH-K DIELECTRICS FOR DRAMSAPPLICATIONS IN MICROELECTRONICS
HIGHHIGH--K DIELECTRICS IN MICROELECTRONICSK DIELECTRICS IN MICROELECTRONICS
Process IntegrationBST deposition techniques
Main techniques
MOCVD
rf-sputtering
HIGH-K DIELECTRICS FOR DRAMSAPPLICATIONS IN MICROELECTRONICS
HIGHHIGH--K DIELECTRICS IN MICROELECTRONICSK DIELECTRICS IN MICROELECTRONICS
Process Integration
ELECTRODE MATERIAL
Noble metalsExp-Pt, Ru etc
•Low leakage current
Conducting Oxides
Exp-Iro2 etc•High leakage
current
HIGH-K DIELECTRICS FOR DRAMSAPPLICATIONS IN MICROELECTRONICS
HIGHHIGH--K DIELECTRICS IN MICROELECTRONICSK DIELECTRICS IN MICROELECTRONICS
Process Integration
Various integration schemes for BST capacitor
APPLICATIONS IN MICROELECTRONICS
HIGHHIGH--K DIELECTRICS IN MICROELECTRONICSK DIELECTRICS IN MICROELECTRONICS
HIGH-K DIELECTRICS FOR DRAMS
Reliability
Time to breakdown Ba0.47Sr0.53TiO3Deposited on various electrodes
Time to breakdown Ba0.47Sr0.53TiO3 at various OMR
TDDB for various DRAM dielectrics
Last but not least
HIGHHIGH--K DIELECTRICS IN MICROELECTRONICSK DIELECTRICS IN MICROELECTRONICS
APPLICATIONS IN MICROELECTRONICSHIGH-K DIELECTRICS FOR DRAMS
High-k dielectrics (BST film ) has become the dielectricmaterial of choice for cell capacitor of the dynamicrandom access memory devices (DRAMs) having gigabitdensities
To continue “shrinking technology” , BST thin films willbe a productive field of research and development.
HIGHHIGH--K DIELECTRICS IN MICROELECTRONICSK DIELECTRICS IN MICROELECTRONICS
SUMMARY
To continue Moore’s law for next decades,New materials are needed.
High-k dielectrics may ultimately lead to vaster and enable applications.
Industry is seeking for new materials and technologies that can replace SiO2 and scaling remains continue.
HIGHHIGH--K DIELECTRICS IN MICROELECTRONICSK DIELECTRICS IN MICROELECTRONICS
References1. H.R. Huff , A. Hou, C. Lim, Y. Kim, J. Barnett, G. Bersuker, G.A Brown, C.D.
Young,P.M. Zeitzoff, J. Gutt, P. Lysaght, M.I. Gardner, R.W. Murto” High-k gate stacks for planar, scaled CMOS integrated circuits”(2003).
2. Cheol Seong Hwang” (Ba,Sr)TiO3 thin films for ultra large scale dynamic random access memory. A review on the process integration”.(1998)
3. S. Ezhilvalavan, Tseung-Yuen Tseng” Progress in the developments of (Ba,Sr)TiO3 (BST) thin films for Gigabit era DRAMs”(2000).
4. G. D. Wilk, R. M. Wallaceb, J. M. Anthony” High- kgate dielectrics: Current status and materials properties considerations”(2001).
5. Ofer Sneh*, Robert B.Clark-Phelps, Ana R.Londer gan, Jereld Winkler, Thomas E.Seidel” Thin film atomic layer deposition equipment for semiconductor processing”(2002).
6. E.P. Gusev , E. Cartier , D.A. Buchanan , M. Gribelyuk , M. Copel ,a H. Okorn-Schmidt , C. D’Emic” Ultrathin high-K metal oxides on silicon:
processing, characterization and integration issues”(2001).
References
HIGHHIGH--K DIELECTRICS IN MICROELECTRONICSK DIELECTRICS IN MICROELECTRONICS
7. D. E. Kotecki,J. D. Baniecki,H. Shen ,R. B. Laibowitz,K. L. Saenger ,J. J. Lian,T. M Shaw ,S. D. Athavale,C. Cabral, Jr.,P. R. Duncombe ,M. Gutsche ,G. Kunkel ,Y.-J. Park,Y.-Y. Wang,R. Wise “(Ba,Sr)TiO3 dielectrics for future stacked capacitor DRAM”(1999).
8.Intel’s High Gate k/Metal Gate Announcement November 4th, 2003.
9.Wilman Tsai and Robert Chau” Integration of Metal gate-High k Dielectrics to Extend Transistor Scaling”(2004).