See discussions, stats, and author profiles for this publication at: https://www.researchgate.net/publication/244484913 5 Presentation ALD2012 StefanMueller Data · July 2013 CITATIONS READS 0 162 7 authors , including: Johannes Müller A. Singh Fraunhofer Institute for Photonic Microsystems IPMS Bruker Corporation 114 PUBLICATIONS 4,603 CITATIONS 28 PUBLICATIONS 890 CITATIONS SEE PROFILE SEE PROFILE Some of the authors of this publication are also working on these related projects: DRAM capacitor View project Ferroelectric doped HfO2 View project All content following this page was uploaded by Thomas Mikolajick on 21 May 2014. The user has requested enhancement of the downloaded file.
Fe Ferroe oelec lectric ric Ph Phase e Tr Transitio sitions ns in Po Poly-Cry rystall stallin ine e Al Al:HfO fO 2 -Th Thin in Fi Films Stefan Müller 1 , Johannes Müller 2 , Aarti Singh 1 , Stefan Riedel 2 , Jonas Sundqvist 2 , Uwe Schröder 1 and Thomas Mikolajick 1 2 1 18.06.2012 Slide 1
Outlin line: e: - Motiva ivatio tion: n: Why Hf HfO 2 ? - Ex Experim rimen ental tal: : Al Al:HfO fO 2 Capaci citor tors - El Electr ctrica ical l / Ph Physica ical l Ch Charac acter teriza ization on - Immedi diate ate Ap Applic icati ations ns + - - + - + - - - n+ n+ p-Substrate - Su Summary 18.06.2012 Slide 2
Motivation: Why HfO 2 ? CMOS S Transi nsistors stors DRAM Capacitors itors HfO 2 k k 20 20 Panasonic 32 nm HKMG Winbond 65 nm DRAM Si SiO 2 k 4 k r “k“ Drain n Curren ent C OX OX C OX OX = = 0 0 r r A / d Signal al Charge C OX OX 18.06.2012 Slide 3
Motivation: Doping HfO 2 for higher-k phase stabilization Anneal + Doping High-symme symmetry try / / 2 Amorphous HfO 2 high-k k phases es + “Homeopathic” Anneal 1 Doping Non Non-cent entrosy rosymm mmetr etric / ferroelec / electr tric phase Low-symmetry Low symmetry / / lower-k k phase Tetragonal P4 2 /nmc Cubic Fm3m Stabilizing dopants (see literature): 13 14 21 38 39 Al Si Sc Sr Y Orthorhombic Pbc2 1 40 64 66 ? 14 39 13 Zr Gd Dy … Monoclinic P2 1 /c Si Y Al Figures: A. Navrotsky , “ Thermochemical insights into refractory ceramic materials based on oxides with large tetravalent cations ”, J. Mater. Chem. 15 15, 1883 (2005) 18.06.2012 Slide 4
Experimental: Fabrication of Al:HfO 2 PMA and PDA Capacitors 800°C / 1000°C PMA Wet etch + Pt Dots 800°C / PMA = “Post -Metallization- Anneal” 1000°C PDA + Pt Dots PDA = “Post -Dielectric- Anneal” Silicon CVD-TiN ALD - Al:HfO 2 Pt (5 nm Ti adhesion layer) 3 h at 450 °C T dep = 275 °C 30 nm 10 nm 16 nm (TEMAH:TMA) 11.4 mol% 8.5 mol% 7.1 mol% 4.8 mol% 3.1 mol% HfO 2 S. Mueller et al., “Incipient Ferroelectricity in Al- Doped HfO2 Thin Films”, Adv. Func. Mat. 22 22, 2412 (2012) 18.06.2012 Slide 5
Experimental: Process Control and Thin Film Quality Control rollab abili lity ty of of ALD-Process Process TEM 0 0.05 0.1 0.15 20 25 AlO 1.5 content [mol%] 20 TiN 15 (10 nm nm) 15 10 10 5 5 0 0 0.00 0.05 0.10 0.15 ALD cycle ratio [Al/(Al+Hf)] Al:HfO HfO 2 (b) Surface face Roughness ness: AFM (16 nm nm) PDA PMA TiN (10 nm nm) Height [nm] 0.0 0.5 1.0 Height [nm] 0.0 0.5 1.0 16 16 16 16 8 8 8 8 0 0 0 0 0 0.2 0.4 0.6 0.8 1 Si Si 0 0.2 0.4 0.6 0.8 1 Lateral Dimension [µm] Lateral Dimension [µm] (Bulk) k) S. Mueller et al., “Incipient Ferroelectricity in Al- Doped HfO2 Thin Films”, Adv. Func. Mat. 22 22, 2412 (2012) 18.06.2012 Slide 6
Results: Electrical Polarization Measurements (PMA Capacitors) 4.8 mol% 450 °C 450 11.4 mol% 8.5 mol% 7.1 mol% 4.8 mol% 3.1 mol% -40 P [µC/cm 2 ] +40 800 °C 800 -4 E [MV/cm] +4 1000 °C 1000 °C 1000 1000 S. Mueller et al., “Incipient Ferroelectricity in Al- Doped HfO2 Thin Films”, Adv. Func. Mat. 22 22, 2412 (2012) 18.06.2012 Slide 7
Results: Electrical Polarization Measurements (PDA Capacitors) 11.4 mol% 8.5 mol% 7.1 mol% 4.8 mol% 3.1 mol% 800 °C 800 -40 P [µC/cm 2 ] +40 1000 °C 1000 -4 E [MV/cm] +4 PDA: : Electrica ctrical chara ract cteriza rizatio tion limite ited d by by breakdown kdown of of capacitors citors! S. Mueller et al., “Incipient Ferroelectricity in Al- Doped HfO2 Thin Films”, Adv. Func. Mat. 22 22, 2412 (2012) 18.06.2012 Slide 8
Results: Additional Characteristics of the Thin Films r / / P r vs. mol% C-V-Chara ract cteris ristics tics 3.1 4.8 7.1 8.5 11.4 0.8 Rem. Polarization [µC/cm 2 ] 8 40 Relative Permittivity [1] Capacitance [nF] 0.7 35 6 11.4 mol% 8.5 mol% 0.6 30 7.1 mol% 4 0.5 4.8 mol% 25 3.1 mol% 2 0.4 20 0 15 0.3 3.1 4.8 7.1 8.5 11.4 -6 -4 -2 0 2 4 6 Aluminum Concentration [mol%] Voltage [V] S. Mueller et al., “Incipient Ferroelectricity in Al- Doped HfO2 Thin Films”, Adv. Func. Mat. 22 22, 2412 (2012) 18.06.2012 Slide 9
Results: Additional Characteristics of the Thin Films cont’d Leakage and and Breakd kdown wn 10 0 10 0 10 -2 10 -2 11.4 mol% 8.5 mol% 10 -4 10 -4 Current [A] Current [A] 1000 °C 7.1 mol% 800 °C 10 -6 10 -6 4.8 mol% 450 °C 3.1 mol% 10 -8 10 -8 10 -10 10 -10 10 -12 10 -12 10 -14 10 -14 -7.0 -3.5 0.0 3.5 7.0 -7.0 -3.5 0.0 3.5 7.0 Voltage [V] Voltage [V] 18.06.2012 Slide 10
Results: Crystallographic Investigations: GI-XRD HfO 2 313 m -241 m 133 m Compared to -124 m -304 m 3.1 mol% e.g. 30° to 40°: HfO 2 4.8 mol% Intensity [a.u.] 421 o Unlikely to Intensity [a.u.] 133 o 331 o occur from 7.1 mol% sole superposition 4.8 mol% 8.5 mol % of m & t 331 c 420 c 11.4 mol% Transition Existen stence ce phase seems of of a a transi nsitio tion 11.4 mol% plausible phase cubic d 10 20 30 40 50 60 70 80 90 80 85 90 2 [°] 2 [°] monoclinic d 10 20 30 40 50 60 70 80 90 2 [°] tetragonal d 10 20 30 40 50 60 70 80 90 2 [°] orthorombic d 10 20 30 40 50 60 70 80 90 2 [°] S. Mueller et al., “Incipient Ferroelectricity in Al- Doped HfO2 Thin Films”, Adv. Func. Mat. 22 22, 2412 (2012) 18.06.2012 Slide 11
Immed ediate ate Applica icatio tion: n: Ferroelectric Field Effect Transistors (FeFET) + - - + - + - - - n+ n+ p-Substrate Intel 45 nm node (2007): Globalfoundries 28 nm node (2012): Introduction of HfO 2 as Gate- World‘s first st 28 28 nm nm Si:HfO HfO 2 Oxide Replacement ferroele roelectric ctric field effe fect ct Stand ndard rd Materi erial l to to date! “Homeopathic” transistor nsistor (FeFET FET) Doping ng „1“ „0“ „1“ „0“ Source: J J . Müller et al., “ Ferroelectricity in HfO 2 Enables Nonvolatile Data Storage in 28 nm HKMG”, 2012 IEEE Symposia on VLSI Technology and Circuits , submitted for publication. 18.06.2012 Slide 12
Advantages and Applications + - - + - + - - - n+ n+ p-Substrate FRAM Memorie ies Ease se of of Non-Volat latil ility ity Proce Pr ocessing ssing ns- ns FeFE Fe FET Switch tchin ing Ferr rroel elect ectric ric Memorie ies HfO 2 CMOS- CM Compati Co atibil bility ity ALD- capability bility Scal alabi ability ty Energy gy Negat gativ ive Lead ad-Free ee Stora orage ge Effi ficient cient Capac pacit itanc nce Ferr rroele oeletric ic Clas ass Devic ices (Log ogic ic) Memor ory 18.06.2012 Slide 13
Summary of Al Al :HfO 1 Proce cessin ssing of fO 2 MIM-Capa Capacito citors rs (PMA A & PDA) 2 Observa ervati tion on of of Ferroe roelectric ectric Phase se Transitio sitions PE “AFE” (A)F )FE FE FE PE 3 Explan anati ation on in Terms ms of of Inte termed rmediate ate Phase se Pbc2 1 4 (Immed mediate ate ) ) Applicatio cations FeFET ET FRAM 18.06.2012 Slide 14
Thank You! and Thanks to the FeFET-Team at & The work for this paper was supported within the scope of technology development by the EFRE fund of the European Community and by funding from the Free State of Saxony (Project HEIKO). 18.06.2012 Slide 15
Backup 18.06.2012 Slide 16
Piezo-Response Even though crystallog. Origin of FE not 100% proven, behavior very FE FE- FE FE- characte acteristic ristic: characteri racterist stic: • Piezo Resp. • Imprint • Retention • Fatigue • PUND Source: T.S.Böschke et al., „ Ferroelectricity in hafnium oxide thin films “ , Appl. Phys. Lett. • SW-Speed 99, 102903 (2011) • Sub-Loops Source: T.S.Böschke et al., „ Phase transitions in ferroelectric silicon doped hafnium oxide “ , Appl. Phys. Lett. 99, 112904 (2011) 18.06.2012 Slide 17 View publication stats View publication stats
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