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Abstract: Direct wafer bonding between high-density-plasma chemical vapour deposited (HDP-CVD) oxide and thermal oxide (TO) has been investigated. HDP-CVD oxides, about 230nm in thickness, were deposited on Si(001) control wafers and the wafers of interest that contain a thin strained silicon (sSi) layer on a so-called virtual substrate that is composed of relaxed SiGe (∼4μm thick) on Si(001) wafers. The surfaces of the as-deposited HDP-CVD oxides on the Si control wafers were smooth with a root-mean-square (RMS) roughness of <1nm, which is sufficiently smooth for direct wafer bonding. The surfaces of the sSi/SiGe/Si(001) substrates show an RMS roughness of >2nm. After HDP-CVD oxide deposition on the sSi/SiGe/Si substrates, the RMS roughness of the oxide surfaces was also found to be the same, i.e., >2nm. To use these wafers for direct bonding the RMS roughness had to be reduced below 1nm, which was carried out using a chemo-mechanical polishing (CMP) step. After bonding the HDP-CVD oxides to thermally oxidized handle wafers, the bonded interfaces were mostly bubble- and void-free for the silicon control and the sSi/SiGe/Si(001) wafers. The bonded wafer pairs were then annealed at higher temperatures up to 800°C and the bonded interfaces were still found to be almost bubble- and void-free. Thus, HDP-CVD oxide is quite suitable for direct wafer bonding and layer transfer of ultrathin sSi layers on oxidized Si wafers for the fabrication of novel sSOI substrates. [Copyright &y& Elsevier]

Carbon-doped SiGe (SiGe:C) bipolar devices have been developed and integrated in to a 0.25 μm CMOS platform. The resulting SiGe:C BiCMOS technology offers a wide spectrum of active and passive devices for wireless and wired communication systems. A high-performance variant of the bipolar transistor has been derived from the standard transistors by reduction of some transistor dimensions. With these alterations, fT and fmax of the bipolar transistors reaches 120 and 140 GHz, respectively. Circuit applications of the devices are demonstrated. Static and dynamic divider circuits have a maximum input frequency of 62 and 72 GHz, respectively. Integrated LC oscillators with frequencies up to 60 GHz are also demonstrated. [Copyright &y& Elsevier]

We present the deconvolution of measurements of inhomogeneous mechanical stress in silicon device structures obtained by UV micro-Raman spectroscopy. Due to the very small UV penetration depth of only 12 nm, averaging of stress over the depth is almost eliminated. Only the averaging of stress over the area of the laser spot remains. By deconvolution of the spectra and comparison with finite element simulations, it is now possible to extract information on mechanical stress from areas as small as 200 nm. Oppositely stressed regions in submicroscopic dimensions can be detected, which could not be detected in previous visible light measurements due to averaging. [ABSTRACT FROM AUTHOR]