Effective interface passivation of a Ge/HfO<sub>2</sub> gate stack using ozone pre-gate treatment and ozone ambient annealing

Mei Zhao; Renrong Liang; Jing Wang; Jun Xu

doi:10.1088/1674-4926/34/6/066005

J. Semicond. > 2013, Volume 34 > Issue 6 > 066005

SEMICONDUCTOR TECHNOLOGY

Effective interface passivation of a Ge/HfO₂ gate stack using ozone pre-gate treatment and ozone ambient annealing

Mei Zhao, Renrong Liang, Jing Wang and Jun Xu

+ Author Affiliations

Corresponding author: Xu Jun, Email:junxu@tsinghua.edu.cn

DOI: 10.1088/1674-4926/34/6/066005

Abstract: The physical and electrical properties of a Ge/GeO₂/HfO₂/Al gate stack are investigated. A thin interfacial GeO₂ layer (~1 nm) is formed between Ge and HfO₂ by dual ozone treatments, which passivates the Ge/high-k interface. Capacitors on p-type Ge substrates show very promising capacitance-voltage (C-V) characteristics by using in situ pre-gate ozone passivation and ozone ambient annealing after high-k deposition, indicating efficient passivation of the Ge/HfO₂ interface. It is shown that the mid-gap interface state density at the Ge/GeO₂ interface is 6.4×10¹¹ cm^-2·eV^-1. In addition, the gate leakage current density of the Ge/GeO₂/HfO₂/Al gate stack passivated by the dual ozone treatments is reduced by about three orders of magnitude compared to that of a Ge/HfO₂/Al gate stack without interface passivation.

Key words: germanium, surface passivation, ozone treatment, interface trap density, gate leakage current density

References

[1]	Kamata Y. High-k/Ge MOSFETs for future nanoelectronics. Mater Today, 2008, 11(1):30
[2]	Shang H, Frank M M, Gusev E P, et al. Germanium channel MOSFETs:opportunities and challenges. IBM J Res Develop, 2006, 50(4):377
[3]	Caymax M, Eneman G, Bellenger F, et al. Germanium for advanced CMOS anno 2009:a SWOT analysis. IEDM Tech Dig, 2009:461
[4]	Gusev E P, Shang H, Copel M, et al. Microstructure and thermal stability of HfO₂ gate dielectric deposited on Ge(100). Appl Phys Lett, 2004, 85(12):2334 doi: 10.1063/1.1794849
[5]	Chui C O, Ramanathan S, Triplet B B, et al. Germanium MOS capacitors incorporating ultrathin high-k gate dielectric. IEEE Electron Device Lett, 2002, 23(8):473 doi: 10.1109/LED.2002.801319
[6]	Kuzum D, Krishnamohan T, Pethe A J, et al. Ge-interface engineering with ozone oxidation for low interface-state density. IEEE Electron Device Lett, 2008, 29(4):328 doi: 10.1109/LED.2008.918272
[7]	Maeda T, Morita Y, Takagi S. Impact of Ge nitride interfacial layers on performance of metal gate/high-k Ge-nMISFETs. VLSI Symp Tech Dig, 2010:213
[8]	Kim K H, Gordon R J, Ritenour A, et al. Atomic layer deposition of insulating nitride interfacial layers for germanium metal oxide semiconductor field effect transistors with high-k oxide/tungsten nitride gate stacks. Appl Phys Lett, 2007, 90(21):212104 doi: 10.1063/1.2741609
[9]	Bellenger F, De Jaeger B, Merckling C, et al. High FET performance for a future CMOS GeO₂-based technology. IEEE Electron Device Lett, 2010, 31(5):402 doi: 10.1109/LED.2010.2044011
[10]	Lee C H, Nishimura T, Saido N, et al. Record-high electron mobility in Ge n-MOSFETs exceeding Si universality. IEDM Tech Dig, 2009:457
[11]	Delabie A, Bellenger F, Houssa M, et al. Effective electrical passivation of Ge(100) for high-k gate dielectric layers using germanium oxide. Appl Phys Lett, 2007, 91(8):082904 doi: 10.1063/1.2773759
[12]	Fukuda Y, Yazaki Y, Otani Y, et al. Low-temperature formation of high-quality GeO₂ interlayer for high-k gate dielectrics/Ge by electron-cyclotron-resonance plasma techniques. IEEE Trans Electron Devices, 2010, 57(1):282 doi: 10.1109/TED.2009.2035030
[13]	Chui C O, Kim H, McIntyre P C, et al. Atomic layer deposition of high-k dielectric for germanium MOS applications-substrate surface preparation. IEEE Electron Device Lett, 2004, 25:274 doi: 10.1109/LED.2004.827285
[14]	Prabhakaran K, Ogino T. Oxidation of Ge (100) and Ge (111) surfaces:an UPS and XPS study. Surf Sci, 1995, 325:263 doi: 10.1016/0039-6028(94)00746-2
[15]	Hubbard K J, Schlom D G. Thermodynamic stability of binary oxides in contact with silicon. J Mater Res, 1996, 11:2757 doi: 10.1557/JMR.1996.0350
[16]	Moreau M, Munteanu D, Autran J L, et al. Investigation of capacitance-voltage characteristics in Ge/high-k MOS devices. J Non Cryst Solids, 2009, 355(18-21):1171 doi: 10.1016/j.jnoncrysol.2009.01.056
[17]	Hill W A and Coleman C C. A single-frequency approximation for interface-state density determination. Solid-State Electron, 1980, 23:987 doi: 10.1016/0038-1101(80)90064-7
[18]	Lee C H, Nishimura T, Nagashio K, et al. High-electron-mobility Ge/GeO₂ n-MOSFETs with two-step oxidation. IEEE Trans Electron Devices, 2011, 58(5):1295 doi: 10.1109/TED.2011.2111373

Fig. 1. Ge3d spectra analyzed by XPS for wafers with different process conditions

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Fig. 2. HR-TEM images of the cross-section of (a) Sample A, (b) Sample B, and (c) Sample C

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Fig. 3. Capacitance-voltage (C-V) characteristics of (a) Sample A, (b) Sample B, and (c) Sample C with different measurement frequencies ranging from 1 kHz to 1 MHz

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Fig. 4. Leakage current density-voltage ($J_{\rm g}$-V) characteristics of the three MOS capacitors

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[1]	Kamata Y. High-k/Ge MOSFETs for future nanoelectronics. Mater Today, 2008, 11(1):30
[2]	Shang H, Frank M M, Gusev E P, et al. Germanium channel MOSFETs:opportunities and challenges. IBM J Res Develop, 2006, 50(4):377
[3]	Caymax M, Eneman G, Bellenger F, et al. Germanium for advanced CMOS anno 2009:a SWOT analysis. IEDM Tech Dig, 2009:461
[4]	Gusev E P, Shang H, Copel M, et al. Microstructure and thermal stability of HfO₂ gate dielectric deposited on Ge(100). Appl Phys Lett, 2004, 85(12):2334 doi: 10.1063/1.1794849
[5]	Chui C O, Ramanathan S, Triplet B B, et al. Germanium MOS capacitors incorporating ultrathin high-k gate dielectric. IEEE Electron Device Lett, 2002, 23(8):473 doi: 10.1109/LED.2002.801319
[6]	Kuzum D, Krishnamohan T, Pethe A J, et al. Ge-interface engineering with ozone oxidation for low interface-state density. IEEE Electron Device Lett, 2008, 29(4):328 doi: 10.1109/LED.2008.918272
[7]	Maeda T, Morita Y, Takagi S. Impact of Ge nitride interfacial layers on performance of metal gate/high-k Ge-nMISFETs. VLSI Symp Tech Dig, 2010:213
[8]	Kim K H, Gordon R J, Ritenour A, et al. Atomic layer deposition of insulating nitride interfacial layers for germanium metal oxide semiconductor field effect transistors with high-k oxide/tungsten nitride gate stacks. Appl Phys Lett, 2007, 90(21):212104 doi: 10.1063/1.2741609
[9]	Bellenger F, De Jaeger B, Merckling C, et al. High FET performance for a future CMOS GeO₂-based technology. IEEE Electron Device Lett, 2010, 31(5):402 doi: 10.1109/LED.2010.2044011
[10]	Lee C H, Nishimura T, Saido N, et al. Record-high electron mobility in Ge n-MOSFETs exceeding Si universality. IEDM Tech Dig, 2009:457
[11]	Delabie A, Bellenger F, Houssa M, et al. Effective electrical passivation of Ge(100) for high-k gate dielectric layers using germanium oxide. Appl Phys Lett, 2007, 91(8):082904 doi: 10.1063/1.2773759
[12]	Fukuda Y, Yazaki Y, Otani Y, et al. Low-temperature formation of high-quality GeO₂ interlayer for high-k gate dielectrics/Ge by electron-cyclotron-resonance plasma techniques. IEEE Trans Electron Devices, 2010, 57(1):282 doi: 10.1109/TED.2009.2035030
[13]	Chui C O, Kim H, McIntyre P C, et al. Atomic layer deposition of high-k dielectric for germanium MOS applications-substrate surface preparation. IEEE Electron Device Lett, 2004, 25:274 doi: 10.1109/LED.2004.827285
[14]	Prabhakaran K, Ogino T. Oxidation of Ge (100) and Ge (111) surfaces:an UPS and XPS study. Surf Sci, 1995, 325:263 doi: 10.1016/0039-6028(94)00746-2
[15]	Hubbard K J, Schlom D G. Thermodynamic stability of binary oxides in contact with silicon. J Mater Res, 1996, 11:2757 doi: 10.1557/JMR.1996.0350
[16]	Moreau M, Munteanu D, Autran J L, et al. Investigation of capacitance-voltage characteristics in Ge/high-k MOS devices. J Non Cryst Solids, 2009, 355(18-21):1171 doi: 10.1016/j.jnoncrysol.2009.01.056
[17]	Hill W A and Coleman C C. A single-frequency approximation for interface-state density determination. Solid-State Electron, 1980, 23:987 doi: 10.1016/0038-1101(80)90064-7
[18]	Lee C H, Nishimura T, Nagashio K, et al. High-electron-mobility Ge/GeO₂ n-MOSFETs with two-step oxidation. IEEE Trans Electron Devices, 2011, 58(5):1295 doi: 10.1109/TED.2011.2111373

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Received: 13 November 2012 Revised: 11 December 2012 Online: Published: 01 June 2013

Article Navigation > Journal of Semiconductors > 2013 > 34(6): 066005

Mei Zhao, Renrong Liang, Jing Wang, Jun Xu. Effective interface passivation of a Ge/HfO2 gate stack using ozone pre-gate treatment and ozone ambient annealing[J]. Journal of Semiconductors, 2013, 34(6): 066005. doi: 10.1088/1674-4926/34/6/066005 ****M Zhao, R R Liang, J Wang, J Xu. Effective interface passivation of a Ge/HfO2 gate stack using ozone pre-gate treatment and ozone ambient annealing[J]. J. Semicond., 2013, 34(6): 066005. doi: 10.1088/1674-4926/34/6/066005.

Citation:

Mei Zhao, Renrong Liang, Jing Wang, Jun Xu. Effective interface passivation of a Ge/HfO₂ gate stack using ozone pre-gate treatment and ozone ambient annealing[J]. Journal of Semiconductors, 2013, 34(6): 066005. doi: 10.1088/1674-4926/34/6/066005 ****

M Zhao, R R Liang, J Wang, J Xu. Effective interface passivation of a Ge/HfO2 gate stack using ozone pre-gate treatment and ozone ambient annealing[J]. J. Semicond., 2013, 34(6): 066005. doi: 10.1088/1674-4926/34/6/066005.

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Effective interface passivation of a Ge/HfO₂ gate stack using ozone pre-gate treatment and ozone ambient annealing

DOI: 10.1088/1674-4926/34/6/066005

Tsinghua National Laboratory for Information Science and Technology, Institute of Microelectronics, Tsinghua University, Beijing 100084, China

Funds:

the State Key Development Program for Basic Research of China 2011CBA00602

Project supported by the State Key Development Program for Basic Research of China (No. 2011CBA00602) and the National Natural Science Foundation of China (Nos. 60876076, 60976013)

the National Natural Science Foundation of China 60976013

the National Natural Science Foundation of China 60876076

More Information

Corresponding author: Xu Jun, Email:junxu@tsinghua.edu.cn
Received Date: 2012-11-13
Revised Date: 2012-12-11
Published Date: 2013-06-01

Abstract

Abstract

The physical and electrical properties of a Ge/GeO₂/HfO₂/Al gate stack are investigated. A thin interfacial GeO₂ layer (~1 nm) is formed between Ge and HfO₂ by dual ozone treatments, which passivates the Ge/high-k interface. Capacitors on p-type Ge substrates show very promising capacitance-voltage (C-V) characteristics by using in situ pre-gate ozone passivation and ozone ambient annealing after high-k deposition, indicating efficient passivation of the Ge/HfO₂ interface. It is shown that the mid-gap interface state density at the Ge/GeO₂ interface is 6.4×10¹¹ cm^-2·eV^-1. In addition, the gate leakage current density of the Ge/GeO₂/HfO₂/Al gate stack passivated by the dual ozone treatments is reduced by about three orders of magnitude compared to that of a Ge/HfO₂/Al gate stack without interface passivation.
- germanium,
- surface passivation,
- ozone treatment,
- interface trap density,
- gate leakage current density

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References(18)

References

[1]	Kamata Y. High-k/Ge MOSFETs for future nanoelectronics. Mater Today, 2008, 11(1):30
[2]	Shang H, Frank M M, Gusev E P, et al. Germanium channel MOSFETs:opportunities and challenges. IBM J Res Develop, 2006, 50(4):377
[3]	Caymax M, Eneman G, Bellenger F, et al. Germanium for advanced CMOS anno 2009:a SWOT analysis. IEDM Tech Dig, 2009:461
[4]	Gusev E P, Shang H, Copel M, et al. Microstructure and thermal stability of HfO₂ gate dielectric deposited on Ge(100). Appl Phys Lett, 2004, 85(12):2334 doi: 10.1063/1.1794849
[5]	Chui C O, Ramanathan S, Triplet B B, et al. Germanium MOS capacitors incorporating ultrathin high-k gate dielectric. IEEE Electron Device Lett, 2002, 23(8):473 doi: 10.1109/LED.2002.801319
[6]	Kuzum D, Krishnamohan T, Pethe A J, et al. Ge-interface engineering with ozone oxidation for low interface-state density. IEEE Electron Device Lett, 2008, 29(4):328 doi: 10.1109/LED.2008.918272
[7]	Maeda T, Morita Y, Takagi S. Impact of Ge nitride interfacial layers on performance of metal gate/high-k Ge-nMISFETs. VLSI Symp Tech Dig, 2010:213
[8]	Kim K H, Gordon R J, Ritenour A, et al. Atomic layer deposition of insulating nitride interfacial layers for germanium metal oxide semiconductor field effect transistors with high-k oxide/tungsten nitride gate stacks. Appl Phys Lett, 2007, 90(21):212104 doi: 10.1063/1.2741609
[9]	Bellenger F, De Jaeger B, Merckling C, et al. High FET performance for a future CMOS GeO₂-based technology. IEEE Electron Device Lett, 2010, 31(5):402 doi: 10.1109/LED.2010.2044011
[10]	Lee C H, Nishimura T, Saido N, et al. Record-high electron mobility in Ge n-MOSFETs exceeding Si universality. IEDM Tech Dig, 2009:457
[11]	Delabie A, Bellenger F, Houssa M, et al. Effective electrical passivation of Ge(100) for high-k gate dielectric layers using germanium oxide. Appl Phys Lett, 2007, 91(8):082904 doi: 10.1063/1.2773759
[12]	Fukuda Y, Yazaki Y, Otani Y, et al. Low-temperature formation of high-quality GeO₂ interlayer for high-k gate dielectrics/Ge by electron-cyclotron-resonance plasma techniques. IEEE Trans Electron Devices, 2010, 57(1):282 doi: 10.1109/TED.2009.2035030
[13]	Chui C O, Kim H, McIntyre P C, et al. Atomic layer deposition of high-k dielectric for germanium MOS applications-substrate surface preparation. IEEE Electron Device Lett, 2004, 25:274 doi: 10.1109/LED.2004.827285
[14]	Prabhakaran K, Ogino T. Oxidation of Ge (100) and Ge (111) surfaces:an UPS and XPS study. Surf Sci, 1995, 325:263 doi: 10.1016/0039-6028(94)00746-2
[15]	Hubbard K J, Schlom D G. Thermodynamic stability of binary oxides in contact with silicon. J Mater Res, 1996, 11:2757 doi: 10.1557/JMR.1996.0350
[16]	Moreau M, Munteanu D, Autran J L, et al. Investigation of capacitance-voltage characteristics in Ge/high-k MOS devices. J Non Cryst Solids, 2009, 355(18-21):1171 doi: 10.1016/j.jnoncrysol.2009.01.056
[17]	Hill W A and Coleman C C. A single-frequency approximation for interface-state density determination. Solid-State Electron, 1980, 23:987 doi: 10.1016/0038-1101(80)90064-7
[18]	Lee C H, Nishimura T, Nagashio K, et al. High-electron-mobility Ge/GeO₂ n-MOSFETs with two-step oxidation. IEEE Trans Electron Devices, 2011, 58(5):1295 doi: 10.1109/TED.2011.2111373

Effective interface passivation of a Ge/HfO₂ gate stack using ozone pre-gate treatment and ozone ambient annealing

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Effective interface passivation of a Ge/HfO₂ gate stack using ozone pre-gate treatment and ozone ambient annealing

Effective interface passivation of a Ge/HfO₂ gate stack using ozone pre-gate treatment and ozone ambient annealing