Conventional source/drain junction and contact formation processes can not meet the stringent requirements of future nanoscale complimentary metal oxide silicon (CMOS) technologies. The selective Si<sub>1-x</sub>Ge<sub>x</sub> source/drain technology was proposed in this laboratory as an alternative to conventional junction and contact schemes. The technology is based on selective chemical vapor deposition of in-situ boron or phosphorus doped Si<sub>1-x</sub>Ge<sub>x</sub> in source/drain areas. The fact that the dopant atoms occupy substitutional sites during growth make the high temperature activation anneals unnecessary virtually eliminating dopant diffusion to yield abrupt doping profiles. Furthermore, the smaller band gap of Si<sub>1-x</sub>Ge<sub>x</sub> results in a smaller Schottky barrier height, which can translate into significant reductions in contact resistivity due to the exponential dependence of contact resistivity on barrier height. This study is focused on formation of self-aligned germanosilicide contacts to phosphorous-doped Si<sub>1-x</sub>Ge<sub>x</sub> alloys. The experimental results obtained in this study indicate that self-aligned nickel germanosilicide (NiSi<sub>1-x</sub>Ge<sub>x</sub>) contacts can be formed on Si<sub>1-x</sub>Ge<sub>x</sub> layers at temperatures as low as 350¢XC. Contacts can yield a contact resistivity of 1E-8 ohm-cm<sup>2</sup> with no sign of germanosilicide induced leakage. However, above a threshold temperature determined by the Ge concentration in the alloy, the NiSi<sub>1-x</sub>Ge<sub>x</sub>/Si<sub>1-x</sub>Ge<sub>x</sub> interface begins to roughen, which affects the junction leakage. For phosphorus doped layers considered in this study, the threshold temperature was around 500¢XC, which is roughly 100¢XC higher than the threshold temperature for NiSi<sub>1-x</sub>Ge<sub>x</sub> contacts formed on boron doped Si<sub>1-x</sub>Ge<sub>x</sub> layers with a Ge percentage of ~ 50%. Nickel and zirconium germanosilicides were also considered as contact candidates but they were found to result in a contact resistivity near 1E-7 ohm-cm<sup>2</sup>.
| Identifer | oai:union.ndltd.org:NCSU/oai:NCSU:etd-12182003-143823 |
| Date | 30 December 2003 |
| Creators | Mo, Hongxiang |
| Contributors | Douglas Barlage, Gregory Parsons, Mehmet Ozturk, Veena Misra |
| Publisher | NCSU |
| Source Sets | North Carolina State University |
| Language | English |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://www.lib.ncsu.edu/theses/available/etd-12182003-143823/ |
| Rights | unrestricted, I hereby certify that, if appropriate, I have obtained and attached hereto a written permission statement from the owner(s) of each third party copyrighted matter to be included in my thesis, dissertation, or project report, allowing distribution as specified below. I certify that the version I submitted is the same as that approved by my advisory committee. I hereby grant to NC State University or its agents the non-exclusive license to archive and make accessible, under the conditions specified below, my thesis, dissertation, or project report in whole or in part in all forms of media, now or hereafter known. I retain all other ownership rights to the copyright of the thesis, dissertation or project report. I also retain the right to use in future works (such as articles or books) all or part of this thesis, dissertation, or project report. |
Page generated in 0.0016 seconds