High-purity platinum and palladium thin films can be deposited selectively by combining microcontact printing (µCP) and metal-organic chemical vapor deposition (MOCVD). Printed patterns of octadecyltrichlorosilane thin films are used to direct the selective deposition of the metallic thin films from bis-(hexafluoroacetylacetonato)platinum(II), Pt(hfac) 2, and bis(hexafluoroacetylacetonato)palladium(II), Pd-(hfac)2, in the presence of hydrogen. This process has been used successfully to fabricate Pt and Pd patterns on substrates such as titanium nitride, indium tin oxide, silicon dioxide, and sapphire. Features with sizes as small as 1.5 µm have been deposited by this combined µCP-MOCVD method. The Pt and Pd films were found to be free of detectable impurities, as measured by X-ray photoelectron and Auger electron spectroscopies. Grain sizes in the deposits can also be varied. We found, for example, that the Pt film growth process yields heavily faceted deposits whose habits depend strongly on the temperature of the substrate during processing. Addition of water vapor to the reactor feed during platinum chemical vapor deposition increased the number of nucleation sites, thus reducing the grain size, but did not otherwise affect the deposition rate to a significant degree. We describe in this report how this photolithography-free process might simplify the patterning of metal and other thin films of interest in integrated circuit fabrication.

10] In this study we deliberately discarded those crystals not showing dominant magnetic interactions as they would not help to establish a clear structure±magnetism correlation. The nature of the dominant magnetic interactions is clearly manifested by the temperature dependence of the magnetic susceptibility (w) in the 2±300 K range. Thus crystals with dominant ferromagnetic interaction have wT vs. T curves in which wT continuously increases when T decreases (see [1]).[12] Details on the geometry of these crystals are not given here and will be presented in a full paper elsewhere.[13] Standard deviations of the atomic distances and bond angles of this five-membered ring are smaller than 2 % of the magnitudes. See: J.Microelectronics is based on devices fabricated in silicon, using photolithography to define patterns. As feature sizes approach limits set by diffraction and the transparency of currently available lenses, there is increasing interest in alternative methods for pattern formation: X-ray, e-beam, and extreme UV lithography [1,2] are leading candidates, but a range of other techniquesÐsoft lithography, [3,4] embossing, [5] atom lithography, [6] and othersÐare also contenders for specific technological niches. Soft lithographyÐa set of techniques for non-photolithographic pattern transfer based on contact printing and polymer moldingÐis useful in a number of applications to which photolithography is not applicable: examples include patterning non-planar surfaces, forming structures in materials other than photoresists, and patterning large areas in a single process step. Fabrication of transistors requires several distinct steps, in which patterns must be transferred with registration between layers. Key issues in fabrication using soft lithography include minimizing distortion in the elastomeric molds during the pattern transfer steps, and especially carrying out the patterning steps without contaminating the surface of the semiconductor material.We have recently used soft lithography (micromolding in capillaries, MIMIC) to fabricate high electron mobility transistors (HEMTs) in GaAs/AlGaAs. [7] Fabrication of devices in GaAs/AlGaAs involves concerns that are specific to this material, and processes used with it cannot necessarily be generalized to other materials. In this communication, we demonstrate the fabrication of metal-oxidesemiconductor field effect transistors (MOSFETs) using soft lithography as the patterning step. The objective of this work is to illustrate the compatibility of soft lithography with standard silicon processes and to begin to address further issues related to fabrication using soft lithography, _______________________ ± [*] Prof.

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We demonstrate the use of micrometer-scale polymer molding, a soft-lithographic patterning technique, as a means to fabricate amorphous silicon thin-film transistors (TFTs). Two different TFT architectures were fabricated and testeda common gate, common channel architecture for single-level patterning on a spherically curved glass substrateand an isolated channel, inverted, staggered architecture with multilevel pattern registration on a planar glass substrate. The silicon and silicon nitride films are deposited by reactive magnetron sputtering, allowing all film depositions to be carried out at temperatures at or below 125 °C, and making this fabrication process a candidate for use on plastic or other thermally sensitive substrates. We discuss the performance of polymer molding as a patterning technique for thin-film microstructures on both planar substrates and on substrates with three-dimensional curvature.

This work demonstrates the feasibility of using soft lithographic patterning in conjunction with additive metallization to fabricate micron-scale electronic devices. Specifically, the fabrication of platinum/platinum silicide/silicon Schottky diodes is demonstrated using a unique combination of soft lithographic patterning and additive metallization techniques. The diode architecture provides a useful means through which to demonstrate the specific characteristics and general utility of this fabrication technique. A 30 × 10 array of micron-scale diode features was patterned on a silicon substrate using a polymeric film prepared by micromolding in capillaries (MIMIC), a soft lithographic patterning technique. Following etching to remove oxide from the substrate surface, metallization by selective platinum chemical vapor deposition (CVD) was used to form rectifying contacts to the substrate. The polymeric film successfully served both as an oxide etch resist before metallization and as a deposition-inhibiting surface for the selective deposition of platinum. The selectivity of the deposition was confirmed by secondary ion mass spectrometry (SIMS). Electrical characterization of the metallized areas showed expected diode behavior. Rutherford backscattering (RBS) and Auger sputter-depth profiling revealed the presence of significant amounts of both Pt and Si at the surface of the platinum film, suggesting that silicide formation accompanies the thin film growth. An unusual feature of the platinum−silicon microstructures obtained in this work was the presence of a platinum concentration gradient within the film instead of the well-defined interfaces between intermetallic phases that are typically seen in platinum silicide layers. A backscattering simulation was used to extract the elemental depth profiles from the RBS data.