Water Vapor

One of the major issues in surface micromachining is process-induced failures of overhanged microstructures, after sacrificial removal. This failure process consists of temporary deformation due to capillary force and permanent stiction of the deformed microstructures to substrate due to the residue product. In order to alleviate this failure, some researchers have investigated the use of low surface-tension liquids, temporary support, sublimation of the final liquid or supercritical method. These conventional methods, however, are complicated liable to plasma damage during PR ashing, or require careful handling of the samples in rinse liquid. In this paper, we present a newly developed anhydrous HF gas-phase etching (GPE) technology for the removal of sacrificial TEOS (tetraethylorthosilicate) oxide. In order to minimize the capillary force of gas-liquid interface and residue product, methanol of low vapor pressure was employed as a catalyst instead of water vapor. The proposed process features simplicity, virtually no capillary forces and even compatibility with IC process as well. The effectiveness of HF GPE with methanol was verified by successfully fabricating the polysilicon cantilevers up to 1000 um in length with no stiction. The etch rate of HF GPE was 10-15 um/hr for the sacrificial TEOS oxide of 0.1-2 um channel height

A conceptual trigeneration system is proposed based on the conventional gas turbine cycle for the high temperature heat addition while adopting the heat recovery steam generator for process heat and vapor absorption refrigeration for the cold production. Combined first and ...

Climate models differ in their responses to imposed forcings, such as increased greenhouse gas concentrations, due to different climate feedback strengths. Feedbacks in NCAR’s Community Atmospheric Model (CAM) are separated into two components: the change in climate components in response to an imposed forcing and the “radiative kernel,” the effect that climate changes have on the top-of-the-atmosphere (TOA) radiative budget. This technique’s usefulness depends on the linearity of the feedback processes. For the case of CO2 doubling, the sum of the effects of water vapor, temperature, and surface albedo changes on the TOA clear-sky flux is similar to the clear-sky flux changes directly calculated by CAM. When monthly averages are used rather than values from every time step, the global-average TOA shortwave change is underestimated by a quarter, partially as a result of intramonth correlations of surface albedo with the radiative kernel. The TOA longwave flux changes do not depend o...

The water vapor sorption behavior of a range of natural fibers (jute, flax, coir, cotton, hemp, Sitka spruce) has been studied. The data were analyzed using the Hailwood Horrobin model for isotherm fitting and determination of monolayer moisture content. The Hailwood Horrobin model was found to provide good fits to the experimental data. The extent of hysteresis exhibited between the adsorption and desorption isotherms was dependent on fiber type studied and was larger with high lignin compared with low lignin content fibers. The area bounded by the hysteresis loop decreased as the isotherms were performed at progressively higher temperatures. This behavior is consistent with sorption interactions occurring with a glassy solid below the glass transition temperature. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009