6_Mobility_Boosters_in_Silicon_MOS_lecture2

6_Mobility_Boosters_in_Silicon_MOS_lecture2 - Mobility...

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Unformatted text preview: Mobility Boosters in Silicon MOS 
 1. Strain 2. Crystal Orientation Aneesh Nainani / Prof. Krishna Saraswat Department of Electrical Engineering Stanford University Stanford, CA 94305 nainani@stanford.edu / saraswat@stanford.edu araswat tanford University 1 EE311/Strained Si Recap : Si bandstructure Silicon Band Structure ml (z) 001 m t (y) 010 (x)100 6 equivalent types of electrons are involved in conduction regime of nMOS 2 types of holes are involved in conduction regime of pMOS : heavy and light araswat tanford University Source: F. Boeuf (ST Microelectronics) 2 EE311/Strained Si 1 Recap : Strain breaks crystal symmetry Band structure deformation Band structure without strain Band Splitting •  Sub-band carrier redistribution -  Carriers occupy valleys with lighter mass •  Less intervalley phonon scattering Iso-energy ellipsoid ml mt mt < m l mt Mobility is increased araswat tanford University 3 EE311/Strained Si Strained Silicon – Process induced strain Which is best? araswat tanford University Source: Synopsys, AMD Corp. 4 EE311/Strained Si 2 S/D : Uniaxial strain engineering araswat tanford University 5 EE311/Strained Si SiC : Uniaxial Tension for nMOS araswat tanford University 6 EE311/Strained Si 3 SiC : Uniaxial Tension for nMOS araswat tanford University 7 EE311/Strained Si Shape and volume of S/D stressor matters Volume Important Shape Important Magnitude of compressive strain in channel proportional to [Ge], proximity to channel, and volume of SiGe araswat tanford University 8 EE311/Strained Si 4 Dual Stress Liners K.Rim IEDM 07 araswat tanford University 9 EE311/Strained Si Stress adders can be used in a combined fashion K.Rim IEDM 07 araswat tanford University 10 EE311/Strained Si 5 Stress in novel transistor options ? araswat tanford University 11 EE311/Strained Si Is Stress the Only Way to Enhance Mobility ?   Carrier effective mass can depend on crystal direction ! –  For Electron iso-energy are ellipsoidal  average dependance does not depend on Si direction for standard (100) substrate (not true is other direction) –  For Hole : extremely high anisotopy of mass !! 1 1 d2E = m* ! 2 dk 2 Heavy Mass k = k0 Crystal Direction (3D) Light Mass ! Source: F. Boeuf (ST Microelectronics) Iso-energy surface of holes in the valance band of Si araswat tanford University 12 EE311/Strained Si 6 Surface orientation araswat tanford University 13 EE311/Strained Si Surface orientation K.Kuhn SSDM 08 araswat tanford University 14 EE311/Strained Si 7 Surface orientation : band structure K.Kuhn SSDM 08 araswat tanford University 15 EE311/Strained Si Surface orientation : experimental data PMOS araswat tanford University NMOS (110) pMOS is 2X better than (100) 16 EE311/Strained Si 8 Bandstructure nMOS : orientation dependence Packan IEDM 08 araswat tanford University 17 EE311/Strained Si Bandstructure pMOS : orientation dependence Packan IEDM 08 araswat tanford University 18 EE311/Strained Si 9 Bandstructure pMOS : orientation dependence Packan IEDM 08 araswat tanford University 19 EE311/Strained Si MASTAR demo araswat tanford University 20 EE311/Strained Si 10 pMOS : hole bands under strain (MASTAR) araswat tanford University 21 EE311/Strained Si pMOS : hole bands under strain (MASTAR) araswat tanford University 22 EE311/Strained Si 11 pMOS : hole bands under strain (MASTAR) ! "#$%#"&'()%*+,-)./01/2)34&&56778889+&:*9,'&7;<('#*94&;#= !""#$ !""#$ %&'()'(* +,-./011',& >%4,) ?@A.)0!)BCCD 2'()'(* 30&1',& !""#$ !""#$ " #4. 54. 64. EF araswat tanford University 23 EE311/Strained Si pMOS : hole bands under strain (MASTAR) araswat tanford University 24 EE311/Strained Si 12 pMOS : hole bands under strain (MASTAR) araswat tanford University 25 EE311/Strained Si pMOS : hole bands under strain (MASTAR) araswat tanford University 26 EE311/Strained Si 13 Hybrid Orientation (HOT) araswat tanford University 27 EE311/Strained Si HOT by Direct Silicon Bonding araswat tanford University 28 EE311/Strained Si 14 (110) PMOS by HOT araswat tanford University 29 EE311/Strained Si (110) PMOS in FinFET ? •  (110) easily achievable in FinFET •  (110) nMOS bad •  Rotate pMOS / nMOS by 45 degree -> hard to integrate araswat tanford University 30 EE311/Strained Si 15 Mobility Booster Effects Can be Additive Crystal Orientation + Uniaxial Stress 1.E-06 Ioff [A/µm] 1.E-07 > 00 <1 -c n ha l ne pM O SiGe SD <110> S Wafer Wafer #1 and #2 +20% +15% 1.E-08 1.E-09 250 300 350 400 450 500 Ion [µA/µm] 550 600 650 700 Courtesy: F. Boeuf (ST Microelectronics) araswat tanford University 31 EE311/Strained Si Mobility Enhancement Innovations NMOS benefit PMOS benefit Biaxial Tensile Strain   Contact etch-stop liner (DSL)   Stress memorization technique (SMT) Dual Stress Liner  e-SiGe  Compressive Gate Poly  Substrate Orientation (HOT) Tensile Channel orientation (<100>) Stress Memory K. Ota et al., IEDM 2002; D.V. Singh et al., IEDM 2005 32 araswat tanford University  Hybrid Orientation NFET PFET H.S. Yang et al., IEDM 2004 SSDOI M. Yang et al., IEDM 2003 K. Rim et al., IEDM 2003 ISSCC 2006: T.C. Chen 32 EE311/Strained Si 16 Picking the Right High-! Material Strain Engineering in Novel Channel Materials Material ! Property " Si Ge GaAs InAs InSb Electron mobility 1600 3900 9200 40000 77000 Hole mobility 430 1900 400 500 850 Bandgap (eV) 1.12 0.66 1.424 0.36 0.17 Dielectric constant 11.8 16 12.4 14.8 17.7 Why Ge? • More symmetric and higher carrier mobilities •  New channel materials must be benchmarked against strained Si 24 ! Highest hole mobility • Easier integration on Si • Lower temperature processing a ra sw a t ! Integration on pre-processed Si t a n fo r d IEDM Short Course 2007 A Nainani APL, 96, 242110 araswat tanford University 33 EE311/Strained Si Germanium MOSFET •  By itself Ge pMOSFET has little advantage over strained-Si •  Strained Ge a neccessity Kobayashi, PhD Thesis, 2010 araswat tanford University 34 EE311/Strained Si 17 CMOS Channel Scenarios: Non-planar FETs with Uniaxial Strain Germanium MOSFET H4(%427,/-*1 @7,G !P(4)F-'%3G Strained Si % Relaxed SiGe 30 Ge E*4FC,/4/1 I%(3'/440,(;,*4&%-76%4/,(-042%*4? A$0-01*2-173-710(*4(+7,GB Ge % Strained SiGe 60 Ge 30% Relaxed SiGe *9%60 0% Strained SiGe 6 I% D *9%60 Si “HOI” Srai ined S Sttraned Si i J EFLHIMNO S Strained Si I% I% Strained Si “30% SSDOI” J0 3'/440,(;,*4&%-76%4/,(3*)C1022%*4? Ge J KFLHIMNO S *9%60 D *9%60 Si # $%&'()*+%,%-.()/-01%/,2(3/4(+0(-1/42501106(-*(%427,/-*1(8'%,0(10-/%4%4&(+%/9%/,(2-1/%4 : ,/1&0(2-1/%4(;0<&<(=>?(3/4(+0(+7%,-(%4-*(-'0(3'/440,()/-01%/, # @%/9%/,(2-1/%4(+03*)02(A74%/9%/,B 7C*4(C/--014%4&(;1067302(3*4673-%D%-.(05503-%D0()/22? # E*4FC,/4/1(&0*)0-1.(%)C1*D02(23/,/+%,%-.(/46(04/+,02(,*801(3'/440,(6*C%4&(;1067302(5,73-7/-%*42? Judy Hoyt, 2010 araswat tanford University 35 !" EE311/Strained Si Uniaxial Strain : III-V nMOSFET araswat tanford University 36 EE311/Strained Si 18 Mobility Booster’s Summary Main Mobility Enhancement Techniques Main Main Mobility Enhancement Techniques Process-based Process-based ProcessProcess ProcessProcess Process--based Process--based Substrate--based Substrate--based SubstrateSubstrate SubstrateSubstrate Substrate-based Substrate-based SixGe1-x SixGe 1-x Si Ge1-x Si xGe1-x SixxGe1-x SSOI SSOI SSOI SSOI SSOI Crystal/Channel Crystal/Channel Crystal/Channel Crystal/Channel Crystal/Channel Bulk Bulk Bulk Bulk Bulk SOI SOI SOI SOI SOI Liners Liners Liners Liners Liners SEG SEG SEG SEG SEG CESL CESL CESL CESL CESL SMT SMT SMT SMT SMT eSiGe eSiGe eSiGe eSiGe eSiGe eSiC eSiC eSiC eSiC eSiC Gate Gate Gate Gate Gate MEOL MEOL MEOL MEOL MEOL Replac. Gate Replac. Gate Replac. Gate Replac. Gate Replac. Gate Contact Contact Contact Contact Contact Tensile bi-axial Tensile bi-axial Tensile bi-axial Tensile bi-axial Tensile bi-axial Natural µµenhancement Natural µ enhancement Natural enhancement Natural µ enhancement Natural µ enhancement Tensile Tensile Tensile Tensile Tensile Tensile Tensile Tensile Tensile Tensile Comp. Comp. Comp. Comp. Comp. Tensile Tensile Tensile Tensile Tensile Tensile Tensile Tensile Tensile Tensile nMOS nMOS nMOS nMOS nMOS +pMOS +pMOS +pMOS +pMOS +pMOS pMOS pMOS pMOS pMOS pMOS nMOS nMOS MOS nMOS nnMOS nMOS nMOS MOS nMOS nnMOS pMOS pMOS MOS pMOS ppMOS nMOS nMOS MOS nMOS nnMOS nMOS nMOS MOS nMOS nnMOS Compressive Compressive Compressive Compressive Compressive Tensile Tensile Tensile Tensile Tensile nMOS nMOS nMOS nMOS nMOS Compressive Compressive Compressive Compressive Compressive pMOS pMOS MOS pMOS ppMOS pMOS pMOS MOS pMOS ppMOS <100> <100> <100> <100> <100> (110) (110) (110) (110) (110) SSOI SSOI SSOI SSOI SSOI Channel Orient. Substrate Orient. Channel Orient. Substrate Orient. Channel Orient. Substrate Orient. Channel Orient. Substrate Orient. Channel Orient. Substrate Orient. araswat Thomas Skotnicki Thomas Skotnicki Thomas Skotnicki Thomas Skotnicki Thomas Skotnickiniversity tanford U IEDM 2010 Short Course •••CMOSTechnologies ––Trends, Scaling and Issues IEDM 2010 Short Course • CMOS Technologies – Trends, Scaling and Issues IEDM 2010 Short Course CMOS Technologies Trends, Scaling and Issues IEDM 2010 Short Course CMOS Technologies Trends, Scaling and Issues IEDM 2010 Short Course • CMOS Technologies ––Trends, Scaling and Issues 37 28 28 28 28 28 EE311/Strained Si Strain Doodle : http://www.intel.com/pressroom/kits/advancedtech/ araswat tanford University 38 EE311/Strained Si 19 ...
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This document was uploaded on 11/18/2011.

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