US Patent 7244534 Device manufacturing method

A method of manufacturing devices with device layers on both sides of a substrate according to an embodiment of the invention includes ensuring that the movements of the substrate during the exposure of the backside are a mirror image of the movements during the exposure of the frontside. In an application of such a method, positioning errors that are characteristic of direction of movement are thus reversed in the backside exposure as compared to the frontside exposure, such that the net overlay error between front and backside is zero or near zero. Embodiments of the invention may be used to reduce overlay errors arising out of certain types of positioning error at no cost, either in machine modifications or throughput.