4577www.MaterialsViews.com wileyonlinelibrary.com particles with diameters ranging from tens of nanometers to several micrometers are commercially available; thus, a wide variety of patterns can be fabricated by colloidal lithography. The colloidal lithography technique has been extensively used to fabricate various periodic structures including nanowire/nanopillar arrays of different materials such as Si, ZnO, InP. [6][7][8] Despite being a very successful technique, [ 9 ] the use of colloidal lithography in case of wetchemical synthesis has been very limited. The main limitation in using colloidal lithography in combination with solutionbased synthesis is that the masked region, that is, the contact area between the colloidal sphere and the substrate is very small while the rest of the substrate remains accessible for the solution. So, in a normal approach involving drop casting of solution on a monolayer of colloidal particles, the solution easily penetrates through the interstices between the colloidal spheres and settles down on the substrate making a continuous layer with periodic holes.With respect to pattern fabrication using liquids, superhydrophilic-superhydrophobic micropatterns is a unique and rapidly developing fi eld, which is based on extreme differences in wettability between superhydrophilic and superhydrophobic regions on the same substrate. [ 10,11 ] Enormous research effort is being devoted to understand and control the wettability of the solid surface in order to uniquely and precisely control the geometry, position and the shape of the liquid droplets on the solid surface. In addition to the fabrication of periodic microdroplets, [ 10 ] this technique is also widely used in various other applications such as surface tension confi ned micro channels, [ 12 ] fi lling micro patterns, [ 13,14 ] passive dispensing by dewetting, [ 15 ] controlling bioadhesion, [ 16 ] cell encapsulation droplet arrays [ 17 ] and fabrication of complex micropatterns. [ 18 ] However, this technique is only suitable for large (>50 µm) structures.Here, we combine colloidal lithography with generation of hydrophobic-hydrophilic regions and demonstrate a novel interfacial energy driven colloidal lithography technique to fabricate periodic micron and submicron-size patterns from solution phase. We utilize self-developed periodic wettability of a Si substrate in the presence of self-assembled colloidal silica spheres. The feasibility and the versatility of the concept are demonstrated by fabricating periodically arranged ZnO nanowire (NW) ensembles on sol-gel derived ZnO seed pattern
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.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.