Characterization of Nanoscale Dielectrics or What characterizes dielectrics needed for the 22 nm node?

Characterization of Nanoscale DielectricsorWhat characterizes dielectrics needed for the 22 nm node? O. Engstrom1, M. Lemme2, P.Hurley3 and S.Hall4 1Chalmers University of Technology 2AMO GmbH 3Tyndal Laboratories 4Liverpool University

Questions at issue • How long can HfO2 be used? • How to find the road to higher-k, higher offset dielectrics? • Problems in connection with bulk and SOI

HfO2

High-k Metal Gate Ni HfO2 Si Tyndall : e-beam evaporation Liverpool: MoCVD, ALD Chalmers: Reactive sputtering, ALD AMO: MBE & metallization AMO, Liverpool, Chalmers and Tyndall

High-k Metal Gate (100)Si/SiOx(0.6nm)/HfO2(3.5nm)/Ni SINANO Exchange: Tyndall  Chalmers Nov 2006 : Study of Bulk Defects in HfO2 JV Dispersion: 65 sites 55umx55um Tox (max/min) = 42.9Å/41.4Å =0.15Å

(100)Si/SiOx/HfO2/TiN SystemInterface defects: Origin and Annealing • P.K.Hurley, K. Cherkaoui, and A.W. Groenland “Electrically active interface defects in the • (100)Si/SiOx/HfO2/TiN system: Origin, Instabilities and Passivation”, • Invited paper: ECS, Cancun, Mexico, October 2006 • SINANO Acknowledged p Si n Si HfO2 by ALD

HfO2/TiN n channel MOSFETsMobility degradation: Interface States HfO2 by ALD ICP(1 MHz) -ICP (1 kHz) Dit = 4.0 x 1010 cm-2 Interface states do not limit mobility (DIT <5.0 x 1010 cm-2)

100000 10000 /Vs] 2 msr [cm mc mph o m 1000 mo (fitting) mo (measured) 100 0 100 200 300 400 Temperature [K] HfO2/TiN n channel MOSFETsMobility degradation Presented at EMRS Symposium L, 2006: SINANO acknowledged Remote phonon scattering term limits mobility above temperature 50 K. Weber et al, Proc. ESSDERC, 2005, p. 379

Oxide defects, ALD HfO2 Gavartin et al, JAP 97, 053704 (2005) Johansson et al, subm. JAP

Hafnium silicate Absorption constant [arb. units] Spectroscopic ellipsometry Mitrovic et al, manuscript submitted

The road to higher k and higher band offset values

Scaling problem of the bulk MOSFET: Shorter channel length requires increased doping under the channel whichrequires higher capacitive coupling between gate and channel which in turn requires thinner gate insulator material

k=f(<Z>) Clausius-Mosotti O. Engström, B. Raeissi, S. Hall, O. Buiu, M.C. Lemme, H.D.B. Gottlob, P.K. Hurley, K. Cherkaoui, Proc. ULIS, 2006, subm. To SSE

k=f(<Z>) O. Engström, B. Raeissi, S. Hall, O. Buiu, M.C. Lemme, H.D.B. Gottlob, P.K. Hurley, K. Cherkaoui, Proc. ULIS, 2006, subm. To SSE

Offset value = f(heat of formation) O. Engström, B. Raeissi, S. Hall, O. Buiu, M.C. Lemme, H.D.B. Gottlob, P.K. Hurley, K. Cherkaoui, Proc. ULIS, 2006, subm. To SSE

The 22 nm node border Borders for the 22 nm LSTP node O. Engström, B. Raeissi, S. Hall, O. Buiu, M.C. Lemme, H.D.B. Gottlob, P.K. Hurley, K. Cherkaoui, Proc. ULIS, 2006, subm. To SSE

Gate insulators for SOI

Epitaxial Gd2O3 with NiSi gate electrodes • ITRS targets for 2012 • EOT given here for a quantum mechanical correction of CET by 0.3 nm H.D.B. Gottlob et al., IEEE EDL, Vol. 27, No. 10, October, 2006

SOI FD MOSFET Single gate x Double gate Lg From Risch, SSE 50, 527 (2006) ”natural length”

g 10 5 3 g = 5 (b) (a) Source Drain Source Drain x [nm] x [nm] Conduction band shape for an SOI FD DG MSFET Ec [eV]

Silicon thickness for FD DG SOI MOSFETs in the 22 nm LSTP node La2O3 tSi [nm] Gd2O3 HfO2 SiO2 Lg/l

Phonon and interface scattering in thin silicon layers Phonon modes Mobility Sotomayor-Torres et al, Phys. Stat. Sol. 1, 2609 (2004) Uchida & Takagi, APL 82, 2916 (2003) Theory Donetti et al, JAP, 100, 013701 (2006)

Summary High-k for the 22 nm LSTP node • Bulk: • So far only La2O3, LaAlO3 seem to pass • SOI: • SiO2 cannot be used neither for DG nor GAA • Probably HfO2 can be used for GAA • For DG La2O3 seems to be necessary, but Gd2O3 may be an alternative Brask-lapp: Things may change!

Characterization of Nanoscale Dielectrics or What characterizes dielectrics needed for the 22 nm node?