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SiGe has been widely used for source/drain (S/D) engineering in pMOSFETs to enhance channel mobility. In this study, selective Si1-xGex growth (0.25 ≤ x ≤ 0.35) with boron concentration of 1-3 × 1020 cm-3 in the process for 22 nm node complementary metal-oxide semiconductor (CMOS) has been investigated and optimized. The growth parameters were carefully tuned to achieve deposition of high quality and highly strained material. The thermal budget was decreased to 800 °C to suppress dopant diffusion, to minimize Si loss in S/D recesses, and to preserve the S/D recess shape. Two layers of Si1-xGex were deposited: a bottom layer with high Ge content (x = 0.35) which filled the recess and a cap layer with low Ge content (x = 0.25) which was elevated in the S/D regions. The elevated SiGe cap layer was intended to be consumed during the Ni-silicidation process in order to avoid strain reduction in the channel region arising from strain relaxation in SiGe S/D. In this study, a kinetic gas model was also applied to predict the pattern dependency of the growth and to determine the epi-profile in different transistor arrays. The input parameters include growth temperature, partial pressures of reactant gases, and chip layout. By using this model, the number of test wafers for epitaxy experiments can be decreased significantly. When the epitaxy process parameters can be readily predicted by the model for epi-profile control in an advanced chip design, fast and cost-effective process development can be achieved. [ABSTRACT FROM AUTHOR]

This study presents investigations about the physical mechanisms, origin, and methods to control the pattern dependency in selective epitaxial growth of Si1-xGex (x=0.14–0.32) layers. It is shown with a comprehensive experimental study that the local Si coverage of individual chips on patterned wafers is the main parameter for the layer profile in the epitaxial growth. This was explained by the gas depletion of the growth species in the low velocity boundary layer over the wafer. The gas depletion radius around each oxide opening was in the centimeter range which is related to the boundary layer thickness. The results from these experiments were applied to grow Si0.75Ge0.25 layers with B concentration of 4×1020 cm-3 selectively for elevated source and drains in fully depleted ultrathin body silicon on insulator p metal oxide semiconductor field effect transistor (p-MOSFET) devices. The epitaxy control was maintained over a wide range of device sizes by optimized process parameters in combination with a wafer pattern design consisting of dummy features causing a uniform gas depletion over the chips on the wafer. [ABSTRACT FROM AUTHOR]

We report the effect of strain on the structural and electrical properties of colossal magnetoresistive (CMR) La0.75Sr0.25MnO3 (LSMO) films grown on Bi4Ti3O12/CeO2/ yttrium-stabilized-zirconia-buffered Si1-xGex/Si (x=0–0.20) and Si1-yCy/Si (y=0–0.01) substrates. The strain in the buffer layer stack was tailored by varying the Ge and C contents in SiGe and SiC layers. It has been demonstrated that the relaxation of Bi4Ti3O12 layer is dependent on Ge content and this strongly affects the quality of the LSMO film. The surface roughness of LSMO was also strain dependent and samples grown on SiGe and SiC template layers were significantly smoother than that on Si. High resistivity and low values of the temperature coefficient of resistivity were obtained in LSMO films on Si0.8Ge0.2/Si and Si0.99C0.01/Si whereas Si0.9Ge0.1/Si sample shows a slight improvement in the crystalline and electrical LSMO properties compared to the CMR film grown onto the Si substrate. [ABSTRACT FROM AUTHOR]

The morphological stability of NiSi1-uGeu ternary alloy films formed by reacting Ni with single-crystal (sc) and polycrystalline (poly) Si1-xGeu is studied (u can be different from x). The agglomeration of NiSi1-uGeu films on Si0.7Ge0.3 occurs at 550°C after rapid thermal processing for 30 s, independently of the crystallinity of the Si1-xGeu. This behavior distinctly different from NiSi: NiSi films on poly-Si display a poorer morphological stability and degrade at lower temperatures than NiSi on sc-Si. On strained Si1-xGex, the presence of Ge simultaneously gives rise to two effects of different origin: mechanical and thermodynamic. The main driving forces behind the agglomeration of NiSi1-uGeu on sc-Si1-xGex are found to be the stored strain energy in the Si1-xGex and the larger (absolute) free energy of formation of NiSi compared to NiGe. The latter constitutes the principal driving force behind the agglomeration of NiSi1-uGeu on poly-Si1-xGex and is not affected by the degree of crystallinity of Si1-xGex. The total free-energy change also includes terms corresponding to the entropy of mixing of Si and Ge in both Si1-xGex and NiSi1-uGeu. Calculations show that the strain energy and the total free-energy change can be 5–7 times (with 30 at.% Ge) the surface/interface and grain-boundary energies in a NiSi film or the grain-boundary energy in an underlying poly-Si. These latter energies are responsible for the agglomeration of NiSi on sc- and poly-Si. The agglomeration takes place primarily via the interdiffusion of Si and Ge between Si1-xGex and NiSi1-uGeu. A structure likely to improve the stability of NiSi1-uGeu/Si1-xGex is discussed. [ABSTRACT FROM AUTHOR]

Phosphorus diffusion has been studied in relaxed Si[sub 1-x]Ge[sub x] samples (x=0.11 and 0.19) and strained Si/Si[sub 1-x]Ge[sub x]/Si heterostructures (x=0.08, 0.13, and 0.18). The diffusivity of P is found to increase with increasing Ge content, while the influence of compressive strain results in a decrease in diffusivity as compared to that in relaxed material. The effect of strain is found to be equivalent to an apparent activation energy of -13 eV per unit strain, where the negative sign indicates that the P diffusion is mediated by interstitials in Si[sub 1-x]Ge[sub x] (x<0.20). This conclusion is also supported by an experiment utilizing injection of Si self-interstitials, which results in an enhanced P diffusion in strained Si[sub 1-x]Ge[sub x]. Further, P is found to segregate into Si across Si/Si[sub 1-x]Ge[sub x] interfaces and the segregation coefficient increases with increasing Ge concentration. © 2003 American Institute of Physics. [ABSTRACT FROM AUTHOR]

The evolution of the loading effect in Si[sub 1-x]Ge[sub x] layers (0≤x≤20%) versus growth parameters has been investigated for selective and nonselective growth using silane- and dichlorosilane-based epitaxy. Various methods have been examined in order to reduce the loading effect, and their influence on the defect density will be further discussed. High-resolution x-ray diffraction and atomic force microscopy were applied as the main tools in these investigations. It is shown that SiGe epitaxy is strongly sensitive to the opening size on the patterned substrates. This dependence is affected by the chemistry of the deposition. This effect can be decreased by adding HCl to the gas mixture or decreasing the growth rate. Meanwhile, adding HCl during the growth of SiGe layers or using a low growth rate decreases the epitaxial quality of the layers. Depositing a Si seed layer prior to the growth of the SiGe layer reduces the loading effect without degrading the epitaxial quality of the layer. © 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Studies a nonselective epitaxial growth process for heterojunction bipolar transistors. Use of the difference in growth rates for epitaxial and polycrystalline films to monitor the thickness of the intrinsic and extrinsic base layers; Film growth; Dopant incorporation; Growth kinetics.

Reports on the use of two-dimensional reciprocal space mapping with high-resolution x-ray diffraction to characterize the strain in as-grown and annealed antimony-doped silicon (Si). Preparation of the samples; Data on the strain perpendicular to the surface in Si films measured from the maps.

Presents a study on the low temperature growth and critical epitaxial thickness of fully strained metastable Ge1-xSnx. Additional obstacle to be overcome in the epitaxial growth of Ge1-xSnx; Investigation and crystalline quality of the layers of Ge1-xSnx; Experimental procedure used to carry out the study; Results of the study; Discussion on the study.

Presents a study which examined the excitonic transitions in high quality metalorganic vapor phase epitaxy grown indium gallium arsenide and indium phosphide quantum wells. Electronic structure of the quantum wells; Deatils on the Fourier transform photoluminescence; Results.

Presents information on a study which investigated the microstructure and microchemistry of CoSi[sub2]/Si[sub1-x]Ge/Si(001) heterostructures using a combination of high-resolution cross-sectional transmission electron microscopy, high-resolution x-ray diffraction and secondary-ion mass spectroscopy. Experimental procedure; Results and discussion; Conclusions.