The memory effect of a trilayer structure (rapid thermal oxide/Ge nanocrystals in SiO2/sputtered SiO2) was investigated via capacitance versus voltage (C–V) measurements. The Ge nanocrystals were synthesized by rapid thermal annealing of the cosputtered Ge+SiO2 films. The memory effect was manifested by the hysteresis in the C–V curve. Transmission electron microscope and C–V results indicated that the hysteresis was due to Ge nanocrystals in the middle layer of the trilayer structure.

Metal assisted chemical etching (MACE) of Si has been used to fabricate both simple and complex Si nanostructures, through the relatively straightforward process of noble metal deposition and patterning followed by immersion in a suitable etching solution. Under appropriate conditions, etching is catalyzed by the metal and occurs only at the metal−silicon interface. MACE therefore requires that a force be present that keeps the metal and silicon in close proximity during etching. The geometrical characteristics of the etched nanostructures therefore depend not only on the solution chemistry, but also on the mechanical properties and constraints of the noble metal catalysts. Here we report experimental studies of etching with nanoscale Au catalyst strips that are mechanically constrained at both ends. The mechanical constraint of these strips leads to termination of etching when a mechanical force balance is achieved. Through experimental characterization of the etching end-state and through modeling, we determine the force between the catalyst and the silicon during etching, and determine how this force depends on the chemistry of the solution.

Metal assisted chemical etching with interconnected catalyst structures has been used to create a wide array of organized nanostructures. However, when patterned catalysts are not interconnected, but are isolated instead, vertical etching to form controlled features is difficult. A systematic study of the mechanism and catalyst stability of metal assisted chemical etching (MACE) of Si in HF and H(2)O(2) using Au catalysts has been carried out. The effects of the etchants on the stability of Au catalysts were examined in detail. The role of excess electronic holes as a result of MACE was investigated via pit formation as a function of catalyst proximity and H(2)O(2) concentration. We show that a suppression of excess holes can be achieved by either adding NaCl to or increasing the HF concentration of the etching solution. We demonstrate that an electric field can direct most of the excess holes to the back of the Si wafer and thus reduce pit formation at the surface of Si between the Au catalysts. The effect of hydrogen bubbles, generated as a consequence of MACE, on the stability of Au catalysts has also been investigated. We define a regime of etch chemistry and catalyst spacing for which catalyst stability and vertical etching can be achieved.

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ABSTRACT:The capillary rise of liquid on a surface, or "wicking", has potential applications in biological and industrial processes such as drug delivery, oil recovery, and integrated circuit chip cooling. This paper presents a theoretical study on the dynamics of wicking on silicon nanopillars based on a balance between the driving capillary forces and viscous dissipation forces. Our model predicts that the invasion of the liquid front follows a diffusion process and strongly depends on the structural geometry. The model is validated against experimental observations of wicking in silicon nanopillars with different heights synthesized by interference lithography and metalassisted chemical etching techniques. Excellent agreement between theoretical and experimental results, from both our samples and data published in the literature, was achieved.

Electromigration in the lower metal (M1) and the upper metal (M2) of Cu dual-damascene interconnections has been studied. The failure times of M2 test structures are significantly longer than those of identical M1 structures. It is proposed that this asymmetry is the result of a difference in the location of void formation and growth, which is believed to be related to the ease of electromigration-induced void nucleation and growth at the Cu/Si3N4 interface. Asymmetric via reliability is therefore an intrinsic characteristic of current Cu interconnect technology.

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Bottoms up! The techniques of laser interference lithography and coarsening of Au dots are combined and used to place Au nanoparticles in inverted pyramids at precise locations on silicon surfaces. The fabrication process is robust against variations in the topographic factor, for example, pit‐to‐mesa width ratio. Excellent tunability of the diameter of the nanoparticles is achieved by a careful manipulation of Au thickness and annealing condition.