An apparatus for characterizing a surface, such as on a semiconductor wafer, includes a heater for establishing controlled temperature conditions, a nitrogen input, and a desiccant for establishing a controlled atmosphere at the surface. A dispensing mechanism provides a known quantity of a liquid in a droplet on the surface. The surface is characterized by determining the evaporation rate of the liquid from the surface under the controlled conditions established by the apparatus. This is usually done by measuring the time for complete evaporation of the droplet to take place. The method is especially suited for characterizing the photoresist application characteristics of semiconductor wafer surfaces.
A method and apparatus for measuring the porosity or density of a porous structure surface is disclosed. A controlled quantity of volatile liquid is applied to a porous surface and is allowed to evaporate. The temperature at the surface reaches equilibrium at the point necessary to supply the latent heat of vaporization of the liquid. This equilibrium temperature depends on the evaporation rate, which has been found to be a function of surface porosity. The porosimeter substantially eliminates other factors influencing evaporation rate, and measures and records the temperature at the surface. Once calibrated with samples of known porosity, this system is capable of making rapid, accurate surface porosity measurements.
A method for determining the cleanliness of a surface of a substrate involves using a visual pattern (17, 29). The visual pattern is either provided in the optical portion of a visual system or is formed on the surface of the substrate to be analyzed. A liquid droplet (26, 27) is dispensed onto the substrate surface, and the extent of the spread area of the droplet is compared to the visual pattern. If the area of the droplet is greater than or equal to a tolerance as signified by the pattern markings, then the surface of the substrate is determined to be sufficiently clean. In relying upon a simple visual comparison of the area of the surface covered by the droplet with an empirically determined visual pattern, a method for analyzing surface cleanliness is consistent between operators and surfaces, is easy to set up and operate, and improves manufacturing throughput.
A method and apparatus for estimating the degree of cleanliness of a substrate surface by measuring the surface wettability, particularly of an inorganic surface used in the manufacturing of electronic components. The wettability of the substrate surface is measured by depositing a droplet of test liquid on the substrate surface and measuring the speed at which the droplet evaporates. This speed is proportional to the droplet liquid surface area, which depends on the substrate surface wettability. A good surface wettability indicates a clean surface.
