Mobility extraction in SOI MOSFETs with sub 1 nm body thickness
2009 (English)In: Solid-State Electronics, ISSN 0038-1101, E-ISSN 1879-2405, Vol. 53, no 12, 1246-1251 p.Article in journal (Refereed) Published
In this work we discuss limitations of the split-CV method when it is used for extracting carrier mobilities in devices with thin silicon channels like FinFETs, ultra thin body silicon-on-insulator (UTB-SOI) transistors and nanowire MOSFETs. We show that the high series resistance may cause frequency dispersion during the split-CV measurements, which leads to underestimating the inversion charge density and hence overestimating mobility. We demonstrate this effect by comparing UTB-SOI transistors with both recessed-gate UTB-SOI devices and thicker conventional SOI MOSFETs. In addition, the intrinsic high series access resistance in UTB-SOI MOSFETs can potentially lead to an overestimation of the effective internal source/drain voltage, which in turn results in a severe underestimation of the carrier mobility. A specific MOSFET test structure that includes additional 4-point probe channel contacts is demonstrated to circumvent this problem, Finally, we accurately extract mobility in UTB-SOI transistors down to 0.9 nm silicon film thickness (four atomic layers) by utilizing the 4-point probe method and carefully choosing adequate frequencies for the split-CV measurements. It is found that in Such thin silicon film thicknesses quantum mechanical effects shift the threshold voltage and degrade mobility.
Place, publisher, year, edition, pages
2009. Vol. 53, no 12, 1246-1251 p.
SOI, MOSFET, Mobility, Fully depleted, Ultra thin body
IdentifiersURN: urn:nbn:se:kth:diva-50564DOI: 10.1016/j.sse.2009.09.017ISI: 000272910200006OAI: oai:DiVA.org:kth-50564DiVA: diva2:495287
QC 201202092012-02-082011-12-062012-02-09Bibliographically approved