Improved drive current in RF vertical MOSFETS using hydrogen anneal

• Main Authors: Hakim, M.M.A (Author), Abuelgasim, A. (Author), Tan, L. (Author), de Groot, C.H (Author), Redman-White, W. (Author), Hall, S. (Author), Ashburn, P. (Author)
• Format: Article
• Language: English
• Published: 2011-03-04.
• Subjects: Article
• Online Access: Get fulltext

This letter reports a study on the effect of a hydrogen anneal after silicon pillar etch of surround-gate vertical MOSFETs intended for RF applications. A hydrogen anneal at 800 ?C is shown to give a 30% improvement in the drive current of 120-nm n-channel transistors compared with transistors without the hydrogen anneal. The value of drive current achieved is 250 ?A/?m, which is a record for thick pillar vertical MOSFETs. This improved performance is obtained even though a sacrificial oxidation was performed prior to the hydrogen anneal to smooth the pillar sidewall. The values of subthreshold slope and DIBL are 79 mV/decade and 45 mV/V, respectively, which are significantly better than most values reported in the literature for comparable devices. The H2 anneal is also shown to decrease the OFF-state leakage current by a factor of three.