摘要:
According to an example, a first layer of a substrate comprises a plurality of gratings having a periodicity P. A second layer of the substrate comprises a plurality of gratings, overlapping with the first set of gratings, and having a periodicity of NP, where N is an integer greater than 2. A first set of gratings has a bias of +d and the second set of gratings has a bias of −d. A beam of radiation is projected onto the gratings and the angle resolved spectrum of the reflected radiation detected. The overlay error is then calculated using the angle resolved spectrum of the reflected radiation.
摘要:
An overlay marker for use with a scatterometer includes two overlying two-dimensional gratings. The two gratings have the same pitch but the upper grating has a lower duty ratio. Cross-talk between X and Y overlay measurements can therefore be avoided. The gratings may be directly overlying or off set so as to be interleaved in one or two directions.
摘要:
Both the 1st and 0th diffraction orders are detected in a scatterometer. The 1st diffraction orders are used to detect the overlay error. The 0th diffraction order is then used to flag if this is a false overlay error calculation of magnitude greater than the bias but smaller than the pitch of the grating.
摘要:
One or more focus settings for use in a device manufacturing method is determined by printing a plurality of target markers at different focus settings and using a scatterometer, e.g. off-line, to measure a property of the target markers that is indicative of focus.
摘要:
An overlay target on a substrate is disclosed, the overlay target including a periodic array of structures wherein every nth structure is different from the rest of the structures. The periodic array is desirably made of two interlaced gratings, one of the gratings having a different pitch from the other grating in order to create an asymmetry in the array. This asymmetry can then be measured by measuring the diffraction spectra of radiation reflected from the overlay target. Variation in the asymmetry indicates the presence of an overlay error in layers on the substrate, where overlay targets are printed on subsequent layers.
摘要:
Each target used in a method of measuring overlay using a scatterometer includes a first portion and a second portion, the first portion has features varying only in a first direction and the second portion has features only varying in a second direction. The first and second directions are orthogonal, thus eliminating cross talk between the directions, and improving the accuracy of overlay error calculations.
摘要:
A fault detection and classification method is disclosed that uses raw back-focal-plane image data of radiation from a substrate surface, detected by a scatterometer detector, to determine a variation in the raw data and correlate the variation in the raw data with a possible fault in a lithographic apparatus or a process that patterned the substrate surface. The correlation is carried out by comparing the variation in the raw data with known metrology data. Once a fault has been determined, a user may be notified of the fault.
摘要:
Both the 1st and 0th diffraction orders are detected in a scatterometer. The 1st diffraction orders are used to detect the overlay error. The 0th diffraction order is then used to flag if this is a false overlay error calculation of magnitude greater than the bias but smaller than the pitch of the grating.
摘要:
A combined alignment and overlay target to be applied to a substrate to enable measurement of the alignment of the substrate with respect to its surroundings, and measurement of the relative alignment of a series of layers on the substrate, is disclosed. In an embodiment, the target comprises an array of structures substantially equidistant apart except for a portion of the structures that are offset by a specific amount in a first direction, and a second portion of the structures that are offset by the same amount in the opposite direction. This target on the substrate may be used to measure its alignment and the same target applied to a second layer, superposed on a first layer, may be used to measure overlay.
摘要:
A lithographic projection apparatus is provided with an optical system built into the wafer table for producing an image of a wafer mark that is provided on the back side of the wafer. The image is located at the plane of the front side of the wafer and can be viewed by an alignment system from the front side of the wafer. Simultaneous alignment between marks on the back and front of the wafer and a mask can be performed using a pre-existing alignment system