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Investigation of Novel Metal Gate and High-κ Dielectric Materials for CMOS Technologies
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
2004 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The demands for faster, smaller, and less expensive electronic equipments are basically the driving forces for improving the speed and increasing the packing density of microelectronic components. Down-scaling of the devices is the principal method to realize these requests. For future CMOS devices, new materials are required in the transistor structure to enable further scaling and improve the transistor performance.

This thesis focuses on novel metal gate and high-κ dielectric materials for future CMOS technologies. Specifically, TiN and ZrN gate electrode materials were studied with respect to work function and thermal stability. High work function, suitable for pMOS transistors, was extracted from both C-V and I-V measurements for PVD and ALD TiN in TiN/SiO2/Si MOS capacitor structures. ZrNx/SiO2/Si MOS capacitors exhibited n-type work function when the low-resistivity ZrNx was deposited at low nitrogen gas flow. Further, variable work function by 0.6 eV was achieved by reactive sputter depositing TiNx or ZrNx at various nitrogen gas flow. Both metal-nitride systems demonstrate a shift in work function after RTP annealing, which is discussed in terms of Fermi level pinning due to extrinsic interface states. Still, the materials are promising in a gate last process as well as show potential as complementary gate electrodes.

The dielectric constant of as-deposited (Ta2O5)1-x(TiO2)x thin films is around 22, whereas that of AlN is about 10. The latter is not dependent on the degree of crystallinity or on the measurement frequency up to 10 GHz. Both dielectrics exhibit characteristics appropriate for integrated capacitors. Finally, utilization of novel materials were demonstrated in strained SiGe surface-channel pMOSFETs with an ALD TiN/Al2O3 gate stack. The transistors were characterized with standard I-V, charge pumping, and low-frequency noise measurements. Correlation between the mobility and the oxide charge was found. Improved transistor performance was achieved by conducting low-temperature water vapor annealing, which reduced the negative charge in the Al2O3.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis , 2004. , p. 71
Series
Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1104-232X ; 1023
Keywords [en]
Electronics, metal gate, high-κ dielectics, titanium nitride, zirconium nitride, MOSFET, thin film, tantalum oxide, aluminum nitride
Keywords [sv]
Elektronik
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
URN: urn:nbn:se:uu:diva-4611ISBN: 91-554-6058-5 (print)OAI: oai:DiVA.org:uu-4611DiVA, id: diva2:165233
Public defence
2004-10-29, Polhemssalen, Ångströmlaboratoriet, Lägerhyddsvägen 1, Uppsala, 09:30 (English)
Opponent
Supervisors
Available from: 2004-10-08 Created: 2004-10-08 Last updated: 2013-05-15Bibliographically approved
List of papers
1. On the thermal stability of atomic layer deposited TiN as gate electrode in MOS devices
Open this publication in new window or tab >>On the thermal stability of atomic layer deposited TiN as gate electrode in MOS devices
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2003 (English)In: IEEE Electron Device Letters, ISSN 0741-3106, E-ISSN 1558-0563, Vol. 24, no 9, p. 550-552Article in journal (Refereed) Published
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:uu:diva-92224 (URN)
Available from: 2004-10-08 Created: 2004-10-08 Last updated: 2017-12-14
2. Investigation of the thermal stability of reactively sputter deposited TiN MOS gate electrodes
Open this publication in new window or tab >>Investigation of the thermal stability of reactively sputter deposited TiN MOS gate electrodes
In: IEEE Transaction on electron devicesArticle in journal (Refereed) Submitted
Identifiers
urn:nbn:se:uu:diva-92225 (URN)
Available from: 2004-10-08 Created: 2004-10-08Bibliographically approved
3. Variable work function in MOS capacitors utilizing nitrogen-controlled TiNx gate electrodes
Open this publication in new window or tab >>Variable work function in MOS capacitors utilizing nitrogen-controlled TiNx gate electrodes
2004 (English)In: Microelectronic Engineering, ISSN 0167-9317, E-ISSN 1873-5568, Vol. 75, no 4, p. 389-396Article in journal (Refereed) Published
Abstract [en]

A substantial shift in the work function of TiNx by as much as 0.7 eV is achieved by varying the nitrogen gas flow during the reactive sputter deposition of the metal gate, which indicates tunability for replacing poly-Si in a CMOS process. TiNx MOS capacitors having multiple SiO2 thicknesses have been evaluated and the work function of TiNx can be altered from 4.2 to 4.9 eV depending on the nitrogen content. The values are stable after RTP annealing up to 600 °C in nitrogen gas for 30 s, although annealing at 800 °C changes the work function for the different compositions towards a mid-gap value. No variation in EOT with annealing temperature is observed for the TiNx/SiO2 stacks deposited at high nitrogen gas flow. The change in work function appears not to be correlated to the crystalline orientation of the TiNx. The work function is instead believed to be affected by extrinsic states in the metal/dielectric interface.

National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:uu:diva-94803 (URN)10.1016/j.mee.2004.07.061 (DOI)
Available from: 2006-09-08 Created: 2006-09-08 Last updated: 2017-12-14Bibliographically approved
4. Low-resistivity ZrNx metal gate in MOS devices
Open this publication in new window or tab >>Low-resistivity ZrNx metal gate in MOS devices
In: IEEE Electron device lettersArticle in journal (Refereed) Submitted
Identifiers
urn:nbn:se:uu:diva-92227 (URN)
Available from: 2004-10-08 Created: 2004-10-08Bibliographically approved
5. Effects of low-temperature water vapor annealing of strained SiGe surface-channel pMOSFETs with high-κ dielectric
Open this publication in new window or tab >>Effects of low-temperature water vapor annealing of strained SiGe surface-channel pMOSFETs with high-κ dielectric
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2003 (English)In: Proceedings of ESSDERC, 2003, p. 525-528Conference paper, Poster (with or without abstract) (Refereed)
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:uu:diva-92228 (URN)
Conference
33rd ESSDERC
Available from: 2004-10-08 Created: 2004-10-08 Last updated: 2013-11-14
6. Investigation of low-frequency noise and Coulomb scattering in Si0.8Ge0.2 surface channel pMOSFETs with ALD Al2O3 gate dielectrics
Open this publication in new window or tab >>Investigation of low-frequency noise and Coulomb scattering in Si0.8Ge0.2 surface channel pMOSFETs with ALD Al2O3 gate dielectrics
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In: Solid-state electronicsArticle in journal (Refereed) Submitted
Identifiers
urn:nbn:se:uu:diva-92229 (URN)
Available from: 2004-10-08 Created: 2004-10-08Bibliographically approved
7. Electrical characterization of AlN MIS and MIM structures
Open this publication in new window or tab >>Electrical characterization of AlN MIS and MIM structures
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2003 In: IEEE Transaction on electron devices, Vol. 50, no 5, p. 1214-1219Article in journal (Refereed) Published
Identifiers
urn:nbn:se:uu:diva-92230 (URN)
Available from: 2004-10-08 Created: 2004-10-08Bibliographically approved
8. Simulation and dielectric characterization of reactive dc magnetron co-sputtered (Ta2O5)1-x(TiO2)x thin films
Open this publication in new window or tab >>Simulation and dielectric characterization of reactive dc magnetron co-sputtered (Ta2O5)1-x(TiO2)x thin films
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2002 (English)In: Journal of vacuum science and technology B, Vol. 20, no 3, p. 855-861Article in journal (Refereed) Published
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:uu:diva-92231 (URN)
Available from: 2004-10-08 Created: 2004-10-08 Last updated: 2012-09-26
9. Patterning of tantalum pentoxide, a high epsilon material, by inductively coupled plasma etching
Open this publication in new window or tab >>Patterning of tantalum pentoxide, a high epsilon material, by inductively coupled plasma etching
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2000 In: Journal of vacuum science and technology B, Vol. 18, no 4, p. 1906-1910Article in journal (Refereed) Published
Identifiers
urn:nbn:se:uu:diva-92232 (URN)
Available from: 2004-10-08 Created: 2004-10-08Bibliographically approved

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Citation style
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Output format
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