A study of the electrical properties of InP channel MOSFETs with S/D Engineering

Autor: Chen, Jia-Chi, 陳家琪
Rok vydání: 2015
Druh dokumentu: 學位論文 ; thesis
Popis: 104
In the thesis, we fabricated the ZrO2/Al2O3/InP MOS capacitors and compared the characteristics of ZrO2/Al2O3/InP MOSCAPs w/ or w/o O2 plasma treatments. Besides, we compared the characteristics of various PDA treatment temperatures which were completed in N2 ambient. Moreover, the Dit was extracted by terman method. For ZrO2/Al2O3/InP MOSCAPs w/o O2 plasma treatment, the frequency dispersion in accumulation region was severely degraded, and the Dit minimum was about 3×10E12 eV-1cm-2 at PDA 300℃; for the ZrO2/Al2O3/InP MOSCAPs w/ O2 plasma treatment, the frequency dispersion in accumulation region was obviously improved. However, the Dit minimum was about 5×10E12 eV-1cm-2. From the XPS analysis, we speculated that the interface quality was degraded due to the In2O3 state generation. For the MOSCAPs w/ O2 plasma treatment, the In2O3 ratio was increased slightly and led to higher Dit. Following, the p-type InP was selectively implanted with Si dose of 2×10E14 cm-2 at 80keV; then TiN with various thicknesses was deposited as encapsulation layer, and the PN junction was completed by RTA at 750℃ for 15s. Among the TiN thicknesses conditions, the PN junction with 2000Å TiN encapsulation exhibited the best characteristics, including the lowest ideality factor of 1.74 and series resistance of 208Ω. After that, the TLM stuctures were fabricated to extract the specific contact resistances and sheet resistances, the condition with TiN 2000Å encapsulation exhibited the specific contact resistances of 3.49×10E-6 Ω∙cm2, which was considerably lower than the condition without TiN encapsulation. On the other hand, the sheet resistances were almost equal values due to the same implantation conditions. From the XRD analysis, we could not relate the TiN thicknesses to the XRD results. From the XPS depth profiles, the N atoms diffused into InP substrate with TiN encapsulation, so we speculated that the contact resistance was improved due to the N atoms diffusion. Next, the InP MOSFETs were fabricated using ZrO2/Al2O3 as gate oxide; source and drain were selectively implanted with Si dose and deposited TiN as encapsulations; the dopant activation was completed by RTA at 750℃. The device exhibited Ion/Ioff ratio of 6.39×105 and subthreshold swing of 238mV/dec. We compared the devices with various TiN encapsulation thicknesses, and the on current with TiN 2000Å was 8.3 times higher than the on current with TiN 500Å. Subsequently, in order to scale down equivalent oxide thickness, the ZrO2/Al2O3 gate oxide thickness was adjusted. The device exhibited Ion/Ioff ratio of 1.84×10E4 and subthreshold swing of 200mV/dec. The driving current was 3.25 times higher but the off-state current was also increased due to the reduction of EOT. Finally, in order to reduce the RSD, the Ni-InP/InP Schottky junction was completed with RTA 250 ℃ for 60s. The Schottky junction exhibited Ion/Ioff ratio of 6.37×10E4 and ideality factor of 1.42. The device exhibited Ion/Ioff ratio of 1.29×10E5 and subthreshold swing of 152 mV/dec. Moreover, the Ni-InP MOSFETs exhibited lower RSD than N+-InP MOSFETs due to the lower sheet resistance of Ni-InP.
Databáze: Networked Digital Library of Theses & Dissertations
Externí odkaz: