1. Effects of Al2O3 Dielectric Cap and Nitridation on Device Performance, Scalability, and Reliability for Advanced High-k/Mëtal Gate pMOSFET Applications.
- Author
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Chang, Vincent S., Ragnarsson, Lars-Åke, Hong Yu Yu, Aoulaiche, Marc, Conard, Thierry, Kaimin Yin, Schram, Tom, Maes, Jan Willem, de Gendt, Stefan, and Biesemans, Serge
- Subjects
DIELECTRIC devices ,NITRIDES ,SCALABILITY ,COMPUTER networks ,RELIABILITY in engineering ,DIELECTRICS ,SEMICONDUCTORS ,MICROELECTRONICS ,SYSTEMS design ,NITROGEN ,PARTICLE beam instabilities - Abstract
A pFET threshold-voltage (V
t ) reduction of about 200 mV is demonstrated by inserting a thin Al2 O3 layer between the high-K dielectric and the TiN gate without noticeable degradation of other electrical properties. HfSiOx capped with 9 Å of Al2 O3 obtains a low long-channel Vt of —0.37 V (the lowest among those with TiN gate), a high mobility of 59 cm2 ⁄V · s at 0.8 MV/cm (92% of universal value), a negligible equivalent. oxide-thickness (EOT) increase of 0.1 Å (compared to the uncapped reference), and a low Vt instability of 4.8 mV at 7 MV/cm. It also passes the ten-year negative-bias-temperature-instability (NBTI) lifetime specification with a gate overdrive of —0.7 V. This indicates that Al2 O3 caps are beneficial to the pFET applications. In contrast, nitrogen incorporation in the Al2 O3 -capped HfSiOx is not favorable because it increases the Vt by 50—140 mV, degrades the mobility by 10%-22%, increases the EOT by 0.5—0.8 Å and the Vt instability by 5–13 mV, and reduces the NBTI lifetime by four to five orders of magnitude. Compared to postcap nitridation, posthigh-k nitridation results in more severe degradation of these properties by incorporating nitrogen closer to the Si/SiO2 interface. [ABSTRACT FROM AUTHOR]- Published
- 2007
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