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Investigation of the thermal stability of reactively sputter deposited TiN MOS gate electrodes
Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Technology, Department of Engineering Sciences.
In: IEEE Transaction on electron devicesArticle in journal (Refereed) Submitted
URN: urn:nbn:se:uu:diva-92225OAI: oai:DiVA.org:uu-92225DiVA: diva2:165225
Available from: 2004-10-08 Created: 2004-10-08Bibliographically approved
In thesis
1. Investigation of Novel Metal Gate and High-κ Dielectric Materials for CMOS Technologies
Open this publication in new window or tab >>Investigation of Novel Metal Gate and High-κ Dielectric Materials for CMOS Technologies
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. 71 p.
Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1104-232X ; 1023
Electronics, metal gate, high-κ dielectics, titanium nitride, zirconium nitride, MOSFET, thin film, tantalum oxide, aluminum nitride, Elektronik
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
urn:nbn:se:uu:diva-4611 (URN)91-554-6058-5 (ISBN)
Public defence
2004-10-29, Polhemssalen, Ångströmlaboratoriet, Lägerhyddsvägen 1, Uppsala, 09:30 (English)
Available from: 2004-10-08 Created: 2004-10-08 Last updated: 2013-05-15Bibliographically approved

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