Abstract: In an alignment or overlay measurement of patterns on a semiconductor wafer an error that occurs during the measurement in one of a predefined number of alignment structures in an exposure field of a corresponding predefined set of exposure fields can be handled by selecting an alignment structure in a substitute exposure field. The latter exposure field need not be part of the predefined set of exposure fields, that is, an inter-field change may be effected. The number of alignment measurements on a wafer remains constant and the quality is increased. Alternatively, when using another alignment structure in the same exposure field—by effecting an intra-field change—the method becomes particularly advantageous when different minimum structure sizes are considered for the substitute targets. Due to the different selectivity in, say, a previous CMP process, such targets might not erode and do not cause an error in a measurement, thus providing an increased alignment or overlay quality.

Abstract: In an alignment or overlay measurement of patterns on a semiconductor wafer an error that occurs during the measurement in one of a predefined number of alignment structures in an exposure field of a corresponding predefined set of exposure fields can be handled by selecting an alignment structure in a substitute exposure field. The latter exposure field need not be part of the predefined set of exposure fields, that is, an inter-field change may be effected. The number of alignment measurements on a wafer remains constant and the quality is increased. Alternatively, when using another alignment structure in the same exposure field—by effecting an intra-field change—the method becomes particularly advantageous when different minimum structure sizes are considered for the substitute targets. Due to the different selectivity in, say, a previous CMP process, such targets might not erode and do not cause an error in a measurement, thus providing an increased alignment or overlay quality.

Abstract: An apparatus for clamping individual pieces of textile fabric exiting a fusing machine conveyor 13, for withdrawing the fabrics until the trailing edges thereof clear a photocell sensor 42, and for stacking the fabrics with aligned leading edges on a hinged and vertically movable table 19 includes a withdrawable stacking rake 21 and a cooperable, vertically movable clamping plate 20. The rake and plate comprise a plurality of laterlly spaced, longitudinally oriented prongs 38 and rods 37, respectively, which are relatively staggered such that they may be partially interleaved during operation to clamp a piece of fabric therebetween.

Abstract: An apparatus for stacking glued textile fabrics has photocells 43, 44 for controlling the withdrawal movement of a stacking table 25 in dependence on the length of the fabrics. The stacking table moves in the same direction as a fabric piece until the trailing edge of the fabric no longer interrupts a light beam, whereupon the table returns to its original position to receive further pieces of fabric. The apparatus also includes clamping means 37, 38 to firmly hold the already stacked fabrics.

Abstract: A slip plate located at the discharge end of an endless band transport device is provided with apertures on both sides at the end remote from the transport device and a stop located at that edge between the apertures. Alternately operating clamping devices movable at right angles to the direction of movement of the textile pieces of the slip plate convey the textile pieces by clamping at the apertures to stacking tables to the right and left of the slip plate.