Abstract: A system and method for exposing a layer of resist on a target such as a semiconductor wafer are provided. An optical system includes a step and repeat projection aligner, and a mask having adjacent complementary pattern segments arranged in an alternating array of columns and rows. The method includes exposing the layer of resist in multiple stages by directing exposure energy through the mask onto the target. During each stage the target can be stepped through unequal stepping distances. A first stepping distance can be a width of a single pattern segment, and a second stepping distance can be a combined width of multiple pattern segments. The unequal stepping distances permit the complementary pattern segments to be initially exposed, and then overlayed on the target using relatively short stepping distance across most of the target.

Abstract: An oil pump for use in a vehicle engine includes a rotary pump for pressurizing oil to be pumped, and a movable piston cooperating with the rotary pump to facilitate metering of oil to and from the pump. The oil metering device is incorporated directly into the pump by means of a cam-actuated piston or a spring-loaded piston which cooperates with a displacement chamber for metering oil. Alternatively, a solenoid-actuated piston may be provided for selectively blocking pressurized fluid from entering a spring-loaded diaphragm chamber. The diaphragm is stroked alternatively by a spring and by oil pressure for metering of fluid therethrough in desired increments.