Threshold voltage control for PMOSFETs using an undoped epitaxial Si channel and a p(+)-SixGe1-x gate
2000 (English)In: Solid-State Electronics, ISSN 0038-1101, E-ISSN 1879-2405, Vol. 44, no 11, 2085-2088 p.Article in journal (Refereed) Published
This paper examines experimentally the performance of PMOSFETs with an undoped epitaxial Si channel in combination with a p(+)-SixGe1-x gate electrode. The channel doping profiles were made using shallow As-implantation followed by selective epitaxy of undoped Si to different thicknesses of 40, 80 and 120 nm. The p(+)-SixGe1-x gate with different values of x was used to tailor the threshold voltage. The transconductance and saturation current were found to increase and the threshold voltage to decrease with increasing thickness of the undoped Si channel for the same gate material. Increasing Ge content in the p(+)-SixGe1-x gate resulted in an increased threshold voltage. Compared to the p(+)-Si gate, the threshold voltage was increased by 0.15 and 0.35 V with a p(+)-Si0.79Ge0.21 and p(+)-Si0.53Ge0.47 gate, respectively, independently of the Si channel thickness. Therefore, the use of a p(+)-SixGe1-x gate introduces an extra degree of freedom when designing the channel for high performance PMOSFETs.
Place, publisher, year, edition, pages
2000. Vol. 44, no 11, 2085-2088 p.
silicon, germanium, epitaxy, MOSFET, gate electrode, channel engineering, films, cmos
IdentifiersURN: urn:nbn:se:kth:diva-20183ISI: 000165546700028OAI: oai:DiVA.org:kth-20183DiVA: diva2:338876
QC 201005252010-08-102010-08-10Bibliographically approved