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Photolithography is the most widely used mass nanoproduction process. Technology requirements demand smaller nanodevices. However, smaller features risk collapse during the drying of rinse liquid because of capillary forces. In the present study, progress is made on two fronts: (i) The importance of surface tension force (STF) on three-phase line on the pattern collapse is investigated. The STF was ignored in previous pattern collapse studies. It is found that inclusion of STF increases the pattern deformation. The calculated deformation error from neglecting STF increases by increasing contact angle, pattern height to width ratio, and trough to width ratio. The deformation error decreases with an increase in elasticity module of pattern. (ii) A more accurate representation for the interface curvature (and related Laplace pressure), that is, using Surface Evolver (SE) simulation rather than cylindrical interface model (CIM), is presented. Curvature values of two-line parallel and box-shaped patterns are derived from SE and compared with the curvature values from CIM. It was found that CIM for the case of two-line parallel overestimates the curvature value and for the case of box-shaped underestimates it. SE simulations also showed that the error of calculating curvature values using CIM for both shapes is only a function of LAR (ratio of pattern length to trough width). For LAR values less than 20, the curvature values from CIM are not accurate for calculating pattern deformation.

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The average evaporation in Iran is 3 times higher than the world average. Applying chemical monolayers on water surfaces is one of the promising methods for suppressing the evaporation. Literature studies have shown that the mixture of cetyl and stearyl (ratio of 1 to 9) is the state-of-the-art monolayer to minimize the evaporation. Adding calcium hydroxide increases the spreading rate and self-healing of the monolayer. Despite long study and investigation on monolayers, there are inconsistencies in explaining the mechanism by which monolayers decrease the evaporation. The mechanisms used to explain the evaporation reduction are: (i) increasing the reflected solar radiation, (ii) dampening the waves formed by winds and decreasing the water surface area, consequently, and (iii) limiting the escape of water molecules. In this paper, by design of experiments (DOE), we try to answer the above question. Evaporation rate from a container in absence of wind or low wind (~0.2 m/s) and at moderate temperature and relative humidity (~20 °C and 45%) is ~10 mm/day. Utilization of the monolayer can save 41% of the evaporated water. Also, in absence of radiation, a 9 m/s wind caused ~15 mm/day evaporation. By increasing the wind speed from 0 to 9 m/s, effectiveness of the monolayer deteriorated from 60 to 13%. Therefore, the main mechanism is neither reflecting the radiation (as in absence of radiation, monolayer was still effective) nor dampening the waves and decreasing the surface area (as in absence of wind, monolayer was effective; also, at higher wind speeds where the surface area increases, monolayer efficiency decreases). Therefore, the main mechanism by which monolayers decrease the evaporation rate is limiting the escape of water molecules. So, monolayers may be effective even during the nights even though radiation is at its lowest.

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