Abstract: A mask or reticle includes a focus test area having a pattern of opaque lines, naked lines, and phase shifting lines. A resulting pattern on a wafer exposed through the focus test area may have a first area of the pattern shifted with respect to a second area of the pattern if the lithography system is out of focus. In some implementations, an area of the pattern may contract or expand if the lithography system is out of focus. An out of focus condition may be determined using a registration tool, scanning electron microscope (SEM), or an interferometer tool (OCD). An out of focus condition may be improved using out of focus information.

Abstract: A mask or reticle includes a focus test area having a pattern of opaque lines, naked lines, and phase shifting lines. A resulting pattern on a wafer exposed through the focus test area may have a first area of the pattern shifted with respect to a second area of the pattern if the lithography system is out of focus. In some implementations, an area of the pattern may contract or expand if the lithography system is out of focus. An out of focus condition may be determined using a registration tool, scanning electron microscope (SEM), or an interferometer tool (OCD). An out of focus condition may be improved using out of focus information.