This paper discusses on the development of germanium-on-insulator (GeOI) structures made by using the smart cut technology, in the preparation of the donor wafer and on the Ge epi development. Thin single crystal layers of Ge [001] have... more
This paper discusses on the development of germanium-on-insulator (GeOI) structures made by using the smart cut technology, in the preparation of the donor wafer and on the Ge epi development. Thin single crystal layers of Ge [001] have been successfully transferred via oxide to oxide bonding or by Ge to oxide bonding, onto 100 mm and 200 mm Si substrates.
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Epitaxial strained Si and Ge n- and p-MOSFETs with a TiN/HfO2 gate stack were fabricated with the same process for a dual channel integration scheme. Compared to the HfO2/Si reference, X1.7 strained Si electron and X9 strained Ge hole... more
Epitaxial strained Si and Ge n- and p-MOSFETs with a TiN/HfO2 gate stack were fabricated with the same process for a dual channel integration scheme. Compared to the HfO2/Si reference, X1.7 strained Si electron and X9 strained Ge hole mobility gains are demonstrated, achieving symmetric n- and p-MOSFET IDsat performance. This X9 strained Ge hole mobility enhancement highly exceeds previous reported results on Ge pMOSFETs with high-k dielectrics. For the first time, such a hole mobility enhancement, theoretically predicted and experimentally reported with thick SiO2 gate dielectrics, is demonstrated with a thin high-k gate dielectric (EOT=14Aring)
ABSTRACT Fully depleted GeOI (Germanium on Insulator) pMOSFETs with HfO2/TiN gate stack and Si-passivation are studied at low temperature. The impact of the starting Ge material and N-type channel doping on threshold voltage is examined.... more
ABSTRACT Fully depleted GeOI (Germanium on Insulator) pMOSFETs with HfO2/TiN gate stack and Si-passivation are studied at low temperature. The impact of the starting Ge material and N-type channel doping on threshold voltage is examined. As there is no evidence of a background doping in Ge films, the typical parasitic conduction and threshold voltage shift in p-channel GeOI MOSFETs are due to interface states. An extended model predicting the threshold voltage temperature dependence in GeOI transistors is proposed.
ABSTRACT We have grown various thickness Ge layers on nominal and 6° off Si(0 0 1) substrates using a low-temperature/high-temperature strategy followed by thermal cycling. A combination of 'mounds' and a perpendicular... more
ABSTRACT We have grown various thickness Ge layers on nominal and 6° off Si(0 0 1) substrates using a low-temperature/high-temperature strategy followed by thermal cycling. A combination of 'mounds' and a perpendicular cross-hatch were obtained on nominal surfaces. On 6° off surfaces, three sets of lines were obtained on top of the 'mounds': one along the 1 1 0 direction perpendicular to the misorientation direction and the other two at ~4.5° on each side of the 1 1 0 direction parallel to the misorientation direction. The surface root mean square roughness was less than 1 nm for 2.5 µm thick nominal and 6° off Ge layers. Those slightly tensily strained Ge layers (R ~ 104%) were characterized by 5 × 107 cm−2 (as-grown layers) −107 cm−2 (annealed layers) threading dislocation densities, independently of the substrate orientation. We have then described the 550 °C/650 °C process used to passivate nominal Ge(0 0 1) surfaces with Si prior to gate stack deposition. An ~5 Å thick SiGe interfacial layer is self-limitedly grown at 550 °C and then thickened at 650 °C (5 Å min−1) thanks to SiH2Cl2 at 20 Torr. Such a Ge surface passivation yields state-of-the-art p-type metal oxide semiconductor field effect transistors provided that 15 Å Si layer thickness is not exceeded. For higher thickness, elastic strain relaxation (through the formation of numerous 2D islands) occurs, followed by plastic relaxation (for a 35 Å thick Si layer).
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As layer transfer techniques have been notably improved in the past years, lithium niobate (LiNbO3) appears as a candidate for the next generation of ultrawide band radio frequency (rf) filters. Depending on the crystalline orientation,... more
As layer transfer techniques have been notably improved in the past years, lithium niobate (LiNbO3) appears as a candidate for the next generation of ultrawide band radio frequency (rf) filters. Depending on the crystalline orientation, LiNbO3 can achieve electromechanical coupling factors Kt2 more than six times larger than those of sputtered aluminum nitride films. In this letter, a process based on direct bonding, grinding, polishing, and deep reactive ion etching is proposed to fabricate a single crystal LiNbO3 film bulk acoustic resonator. From the fabricated test vehicles, Kt2 of 43% is measured confirming the values predicted by theoretical computations.