Abstract: Disclosed are methods and apparatus for analyzing the quality of overlay targets. In one embodiment, a method of extracting data from an overlay target is disclosed. Initially, image information or one or more intensity signals of the overlay target are provided. An overlay error is obtained from the overlay target by analyzing the image information or the intensity signal(s) of the overlay target. A systematic error metric is also obtained from the overlay target by analyzing the image information or the intensity signal(s) of the overlay target. For example, the systematic error may indicate an asymmetry metric for one or more portions of the overlay target. A noise metric is further obtained from the overlay target by applying a statistical model to the image information or the intensity signal(s) of the overlay target. Noise metric characterizes noise, such as a grainy background, associated with the overlay target.

Abstract: An overlay method for determining the overlay error of a device structure formed during semiconductor processing is disclosed. The overlay method includes producing calibration data that contains overlay information relating the overlay error of a first target at a first location to the overlay error of a second target at a second location for a given set of process conditions. The overlay method also includes producing production data that contains overlay information associated with a production target formed with the device structure. The overlay method further includes correcting the overlay error of the production target based on the calibration data.

Abstract: An overlay mark for determining the relative position between two or more successive layers of a substrate or between two or more separately generated patterns on a single layer of a substrate is disclosed. The overlay mark includes a plurality of coarsely segmented lines that are formed by a plurality of finely segmented bars. In some cases, the coarsely segmented lines also include at least one dark field while being separated by a plurality of finely segmented bars and at least one clear field. In other cases, the coarsely segmented lines are positioned into at least two groups. The first group of coarsely segmented lines, which are separated by clear fields, are formed by a plurality of finely segmented bars. The second group of coarsely segmented lines, which are separated by dark fields, are also formed by a plurality of finely segmented bars.

Abstract: An overlay mark for determining the relative shift between two or more successive layers of a substrate via scanning is disclosed. The overlay mark includes at least one test pattern for determining the relative shift between a first and a second layer of the substrate in a first direction. The test pattern includes a first set of working zones and a second set of working zones. The first set of working zones are disposed on a first layer of the substrate and have at least two working zones diagonally opposed and spatially offset relative to one another. The second set of working zones are disposed on a second layer of the substrate and have at least two working zones diagonally opposed and spatially offset relative to one another. The first set of working zones are generally angled relative to the second set of working zones thus forming an “X” shaped test pattern.

Abstract: An overlay mark for determining the relative position between two or more successive layers of a substrate or between two or more separately generated patterns on a single layer of a substrate is disclosed. The overlay mark includes a plurality of working zones, which are used to calculate alignment between a first and a second layer of the substrate or between a first and a second pattern on a single layer of the substrate. Each of the working zones is positioned within the perimeter of the mark. Each of the working zones represents a different area of the mark. The working zones are configured to substantially fill the perimeter of the mark such that the combined area of the working zones is substantially equal to the total area of the mark.

Abstract: relative position between two or more successive layers of a substrate or between two or more separately generated patterns on a single layer of a substrate, is disclosed. The method includes optimizing the geometry of a first element of the mark according to a first scale. The method further includes optimizing the geometry of a second element of the mark according to a second scale. The method additionally includes optimizing the geometry of a third element of the mark according to a third scale.