In this paper, a new method of photoresist coating, direct spray coating, is studied. This method is especially suited to coat high topography surfaces for some special applications in microelectromechanical systems, radio frequency components and packaging. The most suitable photoresist type and coating process are found. The influence of several coating parameters on the thickness and uniformity of the photoresist layer is investigated. A model describing the dependence of the thickness on the major parameters is presented. Very promising results are obtained using spray coating for the fabrication of several three-dimensional structures.
Through-wafer electrical connections are becoming increasingly important for three-dimensional integrated circuits, microelectromechanical systems packaging and radio-frequency components. In this paper, we report our current results on the formation of through-wafer metal plugs using the copper electroplating technique. Several approaches for via filling are investigated, such as filling before or after wafer thinning. Among the methods experimented, the one-side Cu plating and bottom-up filling appears to be the most suitable technique for copper filling into high aspect ratio vias. Using this method, we demonstrate the successful filling of vias with an aspect ratio of up to 7. Copper plugs as small as 20 × 20 μm2 are obtained uniformly over 4 inch Si wafers.
Peptide inhibitors corresponding to sequences in the six helix bundle structure of the fusogenic portion (gp41) of the HIV envelope glycoprotein have been successfully implemented in preventing HIV entry. These peptides bind to regions in HIV gp41 transiently exposed during the fusion reaction. In an effort to improve upon these entry inhibitors, we have successfully designed and tested peptide analogs composed of chemical spacers and reactive moieties positioned strategically to facilitate covalent attachment. Using a temperature-arrested state prime wash in vitro assay we show evidence for the trapping of a pre-six helix bundle fusion intermediate by a covalent reaction with the specific anti-HIV-1 peptide. This is the first demonstration of the trapping of an intermediate conformation of a viral envelope glycoprotein during the fusion process that occurs in live cells. The permanent specific attachment of the covalent inhibitor is projected to improve the pharmacokinetics of administration in vivo and thereby improve the long-term sustainability of peptide entry inhibitor therapy and help to expand its applicability beyond salvage therapy.
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