Effects of Plasma- \hbox Passivation on Mobility Degradation Mechanisms of \hbox \hbox\hbox nMOSFETs

• Published in: IEEE transactions on electron devices Vol. 59; no. 5; pp. 1377 - 1384
• Main Authors: Suleiman, S. A. B., Hoon-Jung Oh, Sungjoo Lee
• Format: Journal Article
• Language: English
• Published: IEEE 01.05.2012
• Subjects: hbox{In}_{0.53}\hbox{Ga}_{0.47}\hbox{As} metal-oxide-semiconductor field-effect transistor; High K dielectric materials; mobility degradation mechanism; MOSFETs; Passivation; Phonons; plasma- hbox{PH}_{3} passivation; Scattering; Substrates; Temperature measurement
• ISSN: 0018-9383; 1557-9646
• DOI: 10.1109/TED.2012.2187209

In this paper, we investigated the inversion-layer scattering mechanisms of HfAlO In 0.53 Ga 0.47 As nMOSFETs with a plasma-PH 3 passivation layer to understand the physical origins of mobility enhancement compared with a nonpassivated device. It has been found in low E eff that the mobility enhancement caused by the plasma- PH 3 passivation is due to the reduction in Coulomb scattering caused by reduction in D it in the upper half of the band gap, as shown from the plasma-PH 3 reaction, which involves P-for-As exchange reaction that reduces the As vacancy sites. Plasma- PH 3 passivation also results in reduction of the phonon scattering caused by soft optical phonons in the HfAlO, which has weak temperature dependence. This is due to the thicker passivation layer of the plasma-PH 3 -passivated device compared with the interfacial layer present in the nonpassivated device. Plasma- PH 3 passivation also helps to reduce the interface dipole scattering caused by fluctuating dipoles at the HfAlO/ In 0.53 Ga 0.47 As interface, which may be attributed to the interdiffusion of elements from HfAlO and In 0.53 Ga 0.47 As . In addition, it is found that effective channel mobility is decreased as gate length reduces until sub-100 nm, due to increased effects of neutral scattering of charges near the source/drain as well as the effect of ballistic transport, thus possibly degrading mobility with further device scaling.