Peter Gu, W. Walkosz, R.F. Klie Nanoscale Physics Group University of Illinois at Chicago

Transcription

1 Stabilizing Cubic HfO 2 Doped Y 2 O 3 using TEM Peter Gu, W. Walkosz, R.F. Klie Nanoscale Group University of Illinois at Chicago

2 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

3 XRD-data 1000 GI-XRD 2.5% Y in HfO2 annealed at different temperatures 900 Intensity C 600 C 925 C (111) (101) monclinic-hfo2 (200) (220) (311) (222) cubic-hfo2 (002) (110) (112) (200) (103) (211) tetra.-hfo Theta Image from professor Takoudis group

4 XRD-data GI-XRD 20% Y in HfO2 annealed at different temperatures Intensity C 925 C 600 C monclinic-hfo2 (111) (200) (220) (311) (222) (101) cubic-hfo2 (002) (110) (112) (200) (103) (211) tetra.-hfo Theta Image from professor Takoudis group

5 % Yttrium concentration measured via XPS κ measured via CV Local Max ~ 20% Yttrium κ vs Yttrium Concentration Image from professor Takoudis group

6 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 103, (2008)

7 2.5% Y2O3 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

8 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

9 2.5% Yttrium Oxide / Hafnium Oxide Annealed Sample Image at 600,000 Magnification Silicon Substrate Silicon Dioxide Hafnia / Yttria film 2.5% Y 2 O 3 Annealed Epoxy

10 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

11 20% Yttrium Oxide / Hafnium Oxide Annealed Sample Image at 500,000 Magnification 20% Y 2 O 3 Annealed Epoxy Hafnia / Yttria film Silicon Dioxide Silicon Substrate

12 20% Y 2 O 3 Annealed - Diffraction 20% 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 (3,1,-1) Si (4,0,0) (-1,3,-3) Si Si (0,2,-2) Si (1,1,-1) Si (2,0,0)Si (-2,2,-2) (3,-1,1) Si Si (-1,1,-1) Si (0,0,0) Si (1,-1,1) Si (-3,1,-1) (2,-2,2) Si Si (1,1,1) (-2,0,0) HfO2 Si (-1,-1,1) (2,0,0) Si HfO2 (0,-2,2) Si (-4,0,0) (1,-3,3) Si Si (-3,-1,1) (1,1,3) Si HfO2 (-5,-1,1) Si (-4,-2,2) Si (-2,-2,2) Si (-3,-3,3) Si (-1,-3,3) Si (0,-4,4) Si

13 SiO 2 Layer Analysis film layer thickness SiO2 layer thickness film layer thickness + SiO2 layer thickness + = 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 unannealed(nm) 2.5% Y 2 O 3 annealed(nm) 20% Y 2 O 3 annealed(nm) average max min stdev

14 Grain Size Analysis Grain Size Measurements - 20% annealed sample Along Grain Perpendicular to Grain (nm) (nm) Grain Size Measurements - 2.5% annealed sample Along Grain Perpendicular to Grain (nm) (nm) Average (nm) Standard Dev

15 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?

16 Acknowledgements National Science Foundation Grant NSF EEC NSF CMS 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

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