Stabilizing Cubic HfO 2 Doped Y 2 O 3 using TEM Stabilizing Cubic HfO - PowerPoint PPT Presentation

Stabilizing Cubic HfO 2 Doped Y 2 O 3 using TEM Stabilizing Cubic HfO 2 Doped Y 2 O 3 using TEM •http://www.tedpella.com/grids_html/si-window.jpg Peter Gu, W. Walkosz, R.F. Klie Nanoscale Physics Group University of Illinois at Chicago UIC APS March Meeting 2008 Physics

Moore’s Law Moore’s Law • 1965 by Intel cofounder, Gordon Moore • Exponential increase in transistor density • Limit to trend • SiO 2 (2 nm – breakdown) • Criteria • Insulating • Thermally Stable • Chemically Stable • High κ materials •http://www.developers.net/storyImages/062404/inteldemystifying1.jpg UIC APS March Meeting 2008 Physics

XRD-data XRD-data GI-XRD 2.5% Y in HfO2 annealed at different temperatures 1000 900 800 monclinic-HfO2 (111) 700 (200) (220) (311) (222) 925 C Intensity 600 cubic-HfO2 800 C (101) 500 (211) (112) (110) (200) (002) (103) 400 tetra.-HfO2 600 C 300 200 100 0 10 20 30 40 50 60 70 2 Theta Image from professor Takoudis’ group UIC APS March Meeting 2008 Physics

XRD-data XRD-data GI-XRD 20% Y in HfO2 annealed at different temperatures 1000 900 800 monclinic-HfO2 700 (220) (311) (222) (200) (111) 925 C Intensity 600 800 C cubic-HfO2 500 (101) (112)(200) (103)(211) (002) (110) 400 tetra.-HfO2 600 C 300 200 100 0 10 20 30 40 50 60 70 2 Theta Image from professor Takoudis’ group UIC APS March Meeting 2008 Physics

κ vs Yttrium Concentration κ vs Yttrium Concentration % Yttrium • concentration measured via XPS κ measured via CV • Local Max ~ 20% • Yttrium •Image from professor Takoudis’ group UIC APS March Meeting 2008 Physics

Research Plan Research Plan • Samples: • Annealed 2.5% Y 2 O 3 on HfO 2 • Unannealed 2.5% Y 2 O 3 on HfO 2 • Annealed 20% Y 2 O 3 on HfO 2 • TEM 3010 • Diffraction mode • Check crystal structure – polymorphs (cubic vs. tetragonal vs. monoclinic) • Check for homogeneity • SiO 2 layer thickness • Grain Size •Journal of Applied Physics 103, 084103 (2008) UIC APS March Meeting 2008 Physics

2.5% Y 2 O 3 Un-Annealed 2.5% Y 2 O 3 Un-Annealed 2.5% Yttrium Oxide / Hafnium Oxide Un-Annealed Sample Image at 150,000 Magnification Silicon Substrate Silicon Dioxide Hafnia / Yttria film -layers Epoxy UIC APS March Meeting 2008 Physics

2.5% Y 2 O 3 Un-Annealed - Diffraction 2.5% Y 2 O 3 Un-Annealed - Diffraction 2.5% Yttrium Oxide / Hafnium Oxide Un-Annealed Sample Image at 50 cm Camera Length •Superimposed Patterns •Spot Pattern – Silicon Substrate (001) •Cubic structure •Fuzzy circular – Film •Amorphous UIC APS March Meeting 2008 Physics

2.5% Y 2 O 3 Annealed 2.5% Y 2 O 3 Annealed 2.5% Yttrium Oxide / Hafnium Oxide Annealed Sample Image at 600,000 Magnification Silicon Substrate Silicon Dioxide Hafnia / Yttria film Epoxy UIC APS March Meeting 2008 Physics

2.5% Y 2 O 3 Annealed - Diffraction 2.5% Y 2 O 3 Annealed - Diffraction 2.5% Yttrium Oxide / Hafnium Oxide Annealed Sample Image at 50 cm Camera Length •Superimposed Patterns •Spot Pattern – Silicon Substrate (001) •Cubic structure •Concentric Circular pattern– Film •Cubic Hafnium Oxide UIC APS March Meeting 2008 Physics

20% Y 2 O 3 Annealed 20% Y 2 O 3 Annealed 20% Yttrium Oxide / Hafnium Oxide Annealed Sample Image at 500,000 Magnification Epoxy Hafnia / Yttria film Silicon Dioxide Silicon Substrate UIC APS March Meeting 2008 Physics

20% Y 2 O 3 Annealed - Diffraction 20% Y 2 O 3 Annealed - Diffraction (3,1,-1) Si 20% Yttrium Oxide / (4,0,0) Si Hafnium (-1,3,-3) Si (0,2,-2) Si Oxide Annealed Sample (1,1,-1) Si (2,0,0)Si Image at 50 cm Camera •(3,-1,1) Si (-2,2,-2) Si Length (-1,1,-1) Si •Superimposed Patterns (0,0,0) Si (1,-1,1) Si •Spot Pattern – Silicon Substrate (001) (2,-2,2) Si (-3,1,-1) Si (1,1,1) HfO2 •Cubic structure (-2,0,0) Si •Concentric Circular (-1,-1,1) Si (2,0,0) HfO2 pattern– Film (0,-2,2) Si •Cubic Hafnium (1,-3,3) Si (-4,0,0) Si Oxide (1,1,3) HfO2 (-3,-1,1) Si (-2,-2,2) Si (-1,-3,3) Si (0,-4,4) Si (-5,-1,1) Si UIC (-4,-2,2) Si APS March Meeting 2008 Physics (-3,-3,3) Si

SiO 2 Layer Analysis SiO 2 Layer Analysis + film layer thickness SiO layer thickness film layer thickness SiO layer thickness = 2 2 + film dielectric constant SiO dielectric constant total dielectric constant 2 • Expected for 30 nm film thickness: • ~3 nm for 20% Y 2 O 3 • ~12 nm for 2.5% Y 2 O 3 • Silicon Dioxide Layer Analysis 2.5% Y 2 O 3 2.5% Y 2 O 3 20% Y 2 O 3 unannealed(nm) annealed(nm) annealed(nm) average 2.289 3.072 3.175 max 3.845 5.774 4.2 min 0.939 1.303 0.765 stdev 0.875 1.332 0.759 UIC APS March Meeting 2008 Physics

Grain Size Analysis Grain Size Analysis Grain Size Measurements - 20% Grain Size Measurements - 2.5% annealed sample annealed sample Along Grain Perpendicular to Grain Along Grain Perpendicular to Grain (nm) (nm) (nm) (nm) Average (nm) 4.339 5.510 5.705 5.069 Standard Dev. 0.833 1.217 1.007 1.507 UIC APS March Meeting 2008 Physics

Summary / Conclusion Summary / Conclusion • 20% Annealed Sample has a larger dielectric constant than 2.5% Annealed Sample • No Difference in Structural makeup of interfacial film (Both cubic polymorph) • No Difference in Silicon Dioxide Layer Thickness • No Difference in Grain Size • Difference in film shape or thickness? • Difference in Oxygen Concentration? UIC APS March Meeting 2008 Physics

Acknowledgements Acknowledgements • National Science Foundation • Grant NSF EEC 0755115 • NSF CMS 0829903 • Department of Defense • Professor R.F. Klie • Professor C. Takoudis • Professor G. Jursich • PhD G. Yang • PhD Q. Tao • Weronica Walkosz • Ke-Bin Low • K.C. Kragh UIC APS March Meeting 2008 Physics

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