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Selective Atomic Layer Deposition of TiO 2 on Silicon/Copper- patterned Substrates UIC REU 2011 AMReL, University of Illinois at Chicago Abigail Jablansky.

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Presentation on theme: "Selective Atomic Layer Deposition of TiO 2 on Silicon/Copper- patterned Substrates UIC REU 2011 AMReL, University of Illinois at Chicago Abigail Jablansky."— Presentation transcript:

1 Selective Atomic Layer Deposition of TiO 2 on Silicon/Copper- patterned Substrates UIC REU 2011 AMReL, University of Illinois at Chicago Abigail Jablansky Department of Chemical and Biomolecular Engineering, University of Pennsylvania

2 What is ALD? Atomic layer deposition Method: –Precursor (TDEAT) –Purge (N 2 ) –Oxidant (H 2 O) –Purge (N 2 ) Batch adsorption process Easily controlled but time-consuming Characterized with ellipsometry, X-ray photoelectron spectroscopy (XPS) Diverse applications

3 Copper and Silicon Conductive substrate Small channels of conduction in microelectronics Need a thin barrier layer on silicon Copper oxidizes more easily –Selective ALD (SALD) –Native oxide

4 Native Oxides Prevention –Self-assembling molecules 1 Minimization –Limited air exposure 2 –Few cycles 3 Reduction –GaAs oxide remains under HfO 2 but converted under Al 2 O 3 4 Tao, Q.; Jursich, G.; Takoudis, C. App. Phys. Lett. 2010, 96, Chen, R.; Kim, H.; McIntyre, P.C.; Bent, S.F. Chem. Mater. 2005, 17, Lee, H.D.; Feng, T.; Yu, L.; Mastrogiovanni, D.; Wan, A.; Gustafsson, T.; Garfunkel, E. App. Phys. Lett. 2009, 94, Tao, Q.; Overhage, K.; Jursich, G.; Takoudis, C. Submitted to Journal of Physi Chem. C Frank, M.M.; Wilk, G.D.; Starodub, D.; Gustafsson, T.; Garfunkel, E.; Chabal, Y.J.; Grazul, J.; Muller, D.A. App. Phys. Lett. 2005, 86,

5 Copper Oxides Cu 2 O (cuprous oxide) –Linear –Most stable copper compounds at high T –Forms ammine under NH 3 5 CuO (cupric oxide) –Square planar –Decomposes at high T to Cu 2 O + O 2 –H 2 or CO reduction at 250 o C 5 Cu 2 O forms first, then CuO if stable 6 Reduction methods 5 Cotton, F.A.; Wilkinson, G. Advanced Inorganic Chemistry, 2nd ed. New York: Interscience Publishers, 1966, pp Zhu, Y.; Mimura, K.; Lim, J.; Isshiki, M.; Jiang, Q. Metal. and Mineral Trans. A. 2006, 37A, 1231.

6 Project Description ALD of TiO 2 onto Si/Cu wafers –Precursor: tetrakis(diethylamino)titanium (TDEAT) –Oxidizer: water Compare 24-hr Cu (1 nm native oxide) exposure to 1-hr 7 Minimize exposure from reactor to ellipsometer, x-ray photoelectron spectroscopy (XPS) 7 Tao, Q. PhD Dissertation, University of Illinois at Chicago, 2011.

7 Reactor Schematic Ice bath Hot wall reactor Tao, Q. PhD Dissertation, University of Illinois at Chicago, 2011.

8 Experimental Setup

9 Characterization Ellipsometry Reflects light off thin films Measures polarization after reflection X-ray photoelectron spectroscopy (XPS) X-rays are energy source Measures kinetic energy, number of escaping electrons

10 Results Verified Tao’s work 7 –Constant growth rate = linear growth 7 Tao, Q. PhD Dissertation, University of Illinois at Chicago, 2011.

11 Troubleshooting Temperature –Increases along path to reactor –Keep oxidizer cold Pressure –“Resting pressure” around torr –Cycles during deposition N 2 tank, H 2 O level in bubbler Check ellipsometer Precursor level, clogged pipes

12 Results (cont.) The colors could represent a deposition layer thickness profile or a chemical vapor deposition (CVD).

13 Summary Objective: SALD of TiO 2 on Si for microelectronic applications Method: reduce native oxide on Cu –Minimize air exposure (in progress) –In situ reduction (future work) Characterization: ellipsometry, XPS Results to date verify prior research Not enough data to conclude about TiO 2 on copper Troubleshooting, design setbacks are important parts of engineering

14 Acknowledgements National Science Foundation, EEC-NSF Grant # CMMI-NSF Grant # Jorge I. Rossero A. Runshen Xu Arman Butt Dr. Jursich Dr. Takoudis

15 References Chen, R.; Kim, H.; McIntyre, P.C.; Bent, S.F. Chem. Mater. 2005, 17, 536. Lee, H.D.; Feng, T.; Yu, L.; Mastrogiovanni, D.; Wan, A.; Gustafsson, T.; Garfunkel, E. App. Phys. Lett. 2009, 94, Tao, Q.; Jursich, G.; Takoudis, C. App. Phys. Lett. 2010, 96, Tao, Q.; Overhage, K.; Jursich, G.; Takoudis, C. Submitted to Journal of Phys. Chem. C Frank, M.M.; Wilk, G.D.; Starodub, D.; Gustafsson, T.; Garfunkel, E.; Chabal, Y.J.; Grazul, J.; Muller, D.A. App. Phys. Lett. 2005, 86, Cotton, F.A.; Wilkinson, G. Advanced Inorganic Chemistry, 2 nd ed. New York: Interscience Publishers, 1966, pp Zhu, Y.; Mimura, K.; Lim, J.; Isshiki, M.; Jiang, Q. Metal. and Mineral Trans. A. 2006, 37A, Tao, Q. PhD Dissertation, University of Illinois at Chicago, Falkenstein, Z.; Hakovirta, M.; Nastasi, M. Thin Solid Films. 2001, 381, 84. Tompkins, H.G.; Allara, D.L. J. Colloid and Interface Science. 1974, 49, 410. Sakata, Y.; Domen, K.; Maruya, K.-I.; Onishi, T. Appl. Spec. 1988, 42, 442.


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