Patent application number | Description | Published |
20100165312 | Method of Determining a Characteristic - A plurality of targets including a second population superimposed on a first population are formed. In the first target the second population has an asymmetry with respect to the first population. In the second target the second population has a different asymmetry with respect to the first population. Reflected radiation is detected from both the targets and used to determine different characteristics of the underlying populations. | 07-01-2010 |
20110141450 | Method and Apparatus for Overlay Measurement - A method of measurement of at-resolution overlay offset may be implemented in a scatterometer. At least three targets are provided on a wafer, each target comprising a first marker grating and a second interleaved marker grating and each target having a different overlay bias between its first and second marker. The first and second markers are provided by subsequent lithography steps in a double patterning lithographic process. The targets are measured with a scatterometer and for each target a measured CD of at least one of the markers is determined using reconstruction. The CD of the first marker may be fixed in the reconstruction. The measured CDs and at least one of the overlay biases is used to determine an overlay result corresponding to a minimum measured CD. The overlay result may be determined by fitting a function such as a parabola to the measured CDs and the overlay biases and determining the overlay at the minimum of the fitted function. | 06-16-2011 |
20120206703 | Inspection Apparatus and Method, Lithographic Apparatus, Lithographic Processing Cell and Device Manufacturing Method - Asymmetry properties of a periodic target on a substrate, such as a grating on a wafer, are determined. An inspection apparatus has a broadband illumination source with illumination beams point mirrored in the pupil plane of a high numerical aperture objective lens. The substrate and target are illuminated via the objective lens from a first direction and a second direction mirror reflected with respect to the plane of the substrate. A quad wedge optical device separately redirects diffraction orders of radiation scattered from the substrate and separates diffraction orders from illumination along each of the first and second directions. For example the zeroth and first orders are separated for each incident direction. After capture in multimode fibers, spectrometers are used to measure the intensity of the separately redirected diffraction orders as a function of wavelength. | 08-16-2012 |
20130100427 | Metrology Method and Apparatus, and Device Manufacturing Method - An approach is used to estimate and correct the overlay variation as function of offset for each measurement. A target formed on a substrate includes periodic gratings. The substrate is illuminated with a circular spot on the substrate with a size larger than each grating. Radiation scattered by each grating is detected in a dark-field scatterometer to obtain measurement signals. The measurement signals are used to calculate overlay. The dependence (slope) of the overlay as a function of position in the illumination spot is determined. An estimated value of the overlay at a nominal position such as the illumination spot's center can be calculated, correcting for variation in the overlay as a function of the target's position in the illumination spot. This compensates for the effect of the position error in the wafer stage movement, and the resulting non-centered position of the target in the illumination spot. | 04-25-2013 |