Physical and Electrical Properties of Polycrystalline Si1 − x Ge x Deposited Using Single-Wafer-Type Low Pressure CVD

Polycrystalline (poly)  films have been suggested as a promising alternative to the currently employed poly silicon gate electrode for complementary metal oxide semiconductor field effect transistor technology due to lower resistivity, less boron penetration, and less gate depletion effect than that of poly Si gates. We investigated the deposition characteristics and physical properties of poly  films using  and  as deposition source gases in single-wafer-type low pressure chemical vapor deposition (LPCVD) system and the electrical properties of  MOS capacitors with the poly   gate stack. Deposition rate as well as Ge content of poly  films shows the large increase with the addition of a small fraction of  while, above critical  flux, it is slightly changed. In addition, the Ge content in poly  films decreased with an increase in deposition temperature. The flatband voltage of the poly  gate stack decreased by 0.3 V and gate depletion effect of poly  gate stack was reduced by 18% as compared to that of the poly Si gate stack. In addition, the charge to breakdown  of the poly  gate stack was higher than that of poly Si gate stack. © 2003 The Electrochemical Society. All rights reserved.

Source:IOPscience

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(Invited) Ge/III-V Heterostructures and Their Applications in Fabricating Engineered Substrates

Chip level integration of III-V devices with Si-CMOS platform requires the use of engineered substrates. Fabrication of engineered substrates utilizes technologies such as epitaxy, wafer bonding and layer transfer. We report on two aspects of III-V/IV materials integration developments that are on the path to enabling Ge-on-insulator (GeOI) and GaAs-on-insulator (GaAsOI) on Si substrates without the use of SmartcutTM technology. We report on the establishment of Ge/AlAs/GaAs and GaAs/Ge/GaAs epitaxial structures/sequences with low defect density and surface properties suitable for wafer bonding. The epitaxial structures have embedded layers that offer highly selective etch properties that facilitate lift-off onto Si substrates. We demonstrate the use of these novel Ge/III-V heterostructures to liftoff layers of Ge through an aqueous hydrogen fluoride (HF) based epitaxial lift-off (ELO) process, or layers of GaAs through a gas phased ELO process enabled by xenon difluoride (XeF2) selective etching of Ge.

Source:IOPscience

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