Abstract: Tapered openings are formed in silicon oxide layers on a substrate by first saturating the silicon oxide layers with water, such as by immersing the substrates and the silicon oxide layers in water. The silicon oxide layers are then heated to dehydrate them to a desired water content at which a desired adhesion of a resist layer to the silicon oxide layer is achieved. A photoresist layer is then coated on the silicon oxide layers and photolithographically defined to provide them with openings therethrough over the area of the silicon oxide layers where the tapered openings are to be provided. The exposed area of the silicon oxide layers are then etched with an etchant for silicon oxide, such as buffered hydrofluoric acid, containing a component for lifting the edge of the resist from the silicon oxide, such as an acid, to etch tapered openings through the silicon oxide layers.

Abstract: A motor-driven marine propeller is disclosed for propelling a marine vessel. The propeller includes a hub member driven by the motor and a can member disposed coaxially relative to the hub member the can member having a fore and an aft end. The hub member and the can member define therebetween an annular port for the passage therethrough of a portion of the exhaust generated by the motor. Supports extend between the hub member and the can member for supporting the can member coaxially relative to the hub member and a plurality of blades are secured to and extend from the can member with each of the blades being equidistantly spaced relative to each other. Each of the blades defines a leading and a trailing surface such that the propeller rotates in a direction from the trailing towards the leading surface in normal forward motion.