Patent application number | Description | Published |
20110001978 | Inspection Method and Apparatus, Lithographic Apparatus, Lithographic Processing Cell and Device Manufacturing Method - A method of determining an overlay error between two successive layers produced by a lithographic process on a substrate, including using the lithographic process to form a calibration structure including a periodic structure of the same pitch on each of the layers, such that an overlaid pair of periodic structures is formed, the structures being parallel, but offset relative to each other by an overlay amount. A spectrum produced by directing a beam of radiation onto the calibration structure is measured and compared with one or more modeled spectra so as to determine values of the grating parameters for the calibration structure from the measured spectrum. The lithographic process is used to form further overlaid periodic structures on the same or one or more subsequent substrates, the determined grating parameter values for the calibration structure being used to determine overlay amounts for the further overlaid periodic structures. | 01-06-2011 |
20110027704 | Methods and Scatterometers, Lithographic Systems, and Lithographic Processing Cells - In a method of determining the focus of a lithographic apparatus used in a lithographic process on a substrate, the lithographic process is used to form a structure on the substrate, the structure having at least one feature which has an asymmetry in the printed profile which varies as a function of the focus of the lithographic apparatus on the substrate. A first image of the periodic structure is formed and detected while illuminating the structure with a first beam of radiation. The first image is formed using a first part of non-zero order diffracted radiation. A second image of the periodic structure is foamed and detected while illuminating the structure with a second beam of radiation. The second image is formed using a second part of the non-zero order diffracted radiation which is symmetrically opposite to the first part in a diffraction spectrum. The ratio of the intensities of the measured first and second portions of the spectra is determined and used to determine the asymmetry in the profile of the periodic structure and/or to provide an indication of the focus on the substrate. In the same instrument, an intensity variation across the detected portion is determined as a measure of process-induced variation across the structure. A region of the structure with unwanted process variation can be identified and excluded from a measurement of the structure. | 02-03-2011 |
20110043791 | Metrology Method and Apparatus, Lithographic Apparatus, Device Manufacturing Method and Substrate - A metrology apparatus is arranged to illuminate a plurality of targets with an off-axis illumination mode. Images of the targets are obtained using only one first order diffracted beam. Where the target is a composite grating, overlay measurements can be obtained from the intensities of the images of the different gratings. Overlay measurements can be corrected for errors caused by variations in the position of the gratings in an image field. | 02-24-2011 |
20110194092 | Substrate, an Inspection Apparatus, and a Lithographic Apparatus - A target for measuring an overlay error or a critical dimension of a substrate comprises a grating. In one example, lines of the grating are arranged at an angle of about 45° with respect to edges of the target. As a consequence, the diffraction order of the grating reflection has its sub-maxima not aligned along the line on which the other diffraction orders are positioned, and overlap of intensity with other diffraction orders is reduced | 08-11-2011 |
20110205518 | Substrate, a Method of Measuring a Property, an Inspection Apparatus and a Lithographic Apparatus - Scatterometry for measuring overlay. A second set of superimposed gratings are superposed over a first set of superimposed gratings. The second set of gratings have a different periodicity from the first set of gratings or a different orientation. Consequently the first order diffraction pattern from the second set of superimposed gratings can be distinguished from the first order diffraction pattern from the first set of superimposed gratings. | 08-25-2011 |
20120033193 | Inspection Apparatus and Method, Lithographic Apparatus and Lithographic Processing Cell - An inspection apparatus measures a property of a substrate including a periodic structure. An illumination system provides a beam of radiation with an illumination profile including a plurality of illuminated portions. A radiation projector projects the beam of radiation onto the substrate. A detector detects radiation scattered from the periodic structure and separately detects first order diffracted radiation and at least one higher order of diffracted radiation of each of the illuminated portions. A processor determines the property of the substrate from the detected radiation. The plurality of illuminated portions are arranged such that first order diffracted radiation arising from one or more of the illuminated portions are not overlapped by zeroth order or first order diffracted radiation arising from any other of the illuminated portions. Furthermore, the plurality of illuminated portions are arranged such that first order diffracted radiation arising from the one or more of the illuminated portions are overlapped by at least one of the higher orders of diffracted radiation arising from any other of the illuminated portions. | 02-09-2012 |
20120044470 | Substrate for Use in Metrology, Metrology Method and Device Manufacturing Method - A pattern from a patterning device is applied to a substrate. The applied pattern includes device functional areas and metrology target areas. Each metrology target area comprises a plurality of individual grating portions, which are used for diffraction based overlay measurements or other diffraction based measurements. The gratings are of the small target type, which is small than an illumination spot used in the metrology. Each grating has an aspect ratio substantially greater than 1, meaning that a length in a direction perpendicular to the grating lines which is substantially greater than a width of the grating. Total target area can be reduced without loss of performance in the diffraction based metrology. A composite target can comprise a plurality of individual grating portions of different overlay biases. Using integer aspect ratios such as 2:1 or 4:1, grating portions of different directions can be packed efficiently into rectangular composite target areas. | 02-23-2012 |
20120123581 | Metrology Method and Inspection Apparatus, Lithographic System and Device Manufacturing Method - Methods are disclosed for measuring target structures formed by a lithographic process on a substrate. A grating structure within the target is smaller than an illumination spot and field of view of a measurement optical system. The optical system has a first branch leading to a pupil plane imaging sensor and a second branch leading to a substrate plane imaging sensor. A spatial light modulator is arranged in an intermediate pupil plane of the second branch of the optical system. The SLM imparts a programmable pattern of attenuation that may be used to correct for asymmetries between the first and second modes of illumination or imaging. By use of specific target designs and machine-learning processes, the attenuation patterns may also be programmed to act as filter functions, enhancing sensitivity to specific parameters of interest, such as focus. | 05-17-2012 |
20120242970 | Metrology Method and Apparatus, and Device Manufacturing Method - Methods are disclosed for measuring target structures formed by a lithographic process on a substrate. A grating or other structure within the target is smaller than an illumination spot and field of view of a measurement optical system. The position of an image of the component structure varies between measurements, and a first type of correction is applied to reduce the influence on the measured intensities, caused by differences in the optical path to and from different positions. A plurality of structures may be imaged simultaneously within the field of view of the optical system, and each corrected for its respective position. The measurements may comprise first and second images of the same target under different modes of illumination and/or imaging, for example in a dark field metrology application. A second type of correction may be applied to reduce the influence of asymmetry between the first and second modes of illumination or imaging, for example to permit a more accurate overly measurement in a semiconductor device manufacturing process. | 09-27-2012 |
20130059240 | Substrate and Patterning Device for Use in Metrology, Metrology Method and Device Manufacturing Method - A pattern from a patterning device is applied to a substrate by a lithographic apparatus. The applied pattern includes product features and metrology targets. The metrology targets include large targets and small targets which are for measuring overlay. Some of the smaller targets are distributed at locations between the larger targets, while other small targets are placed at the same locations as a large target. By comparing values measured using a small target and large target at the same location, parameter values measured using all the small targets can be corrected for better accuracy. The large targets can be located primarily within scribe lanes while the small targets are distributed within product areas. | 03-07-2013 |
20130258310 | Metrology Method and Apparatus, Lithographic System and Device Manufacturing Method - A lithographic process is used to form a plurality of target structures (T) on a substrate (W). Each target structure comprises overlaid gratings each having a specific overlay bias. Asymmetry (A) of each grating, measured by scatterometry, includes contributions due to (i) the overlay bias, (ii) an overlay error (OV) in the lithographic process and (iii) bottom grating asymmetry within the overlaid gratings. Asymmetry measurements are obtained for three or more target structures having three or more different values of overlay bias (e.g., −d, 0, +d). Knowing the three different overlay bias values and a theoretical curve relationship between overlay error and asymmetry, overlay error (OV) can be calculated while correcting the effect of bottom grating asymmetry. Bias schemes with three and four different biases are disclosed as examples. Gratings with different directions and biases can be interleaved in a composite target structure. | 10-03-2013 |
20140139814 | Methods and Scatterometers, Lithographic Systems, and Lithographic Processing Cells - In a method of determining the focus of a lithographic apparatus used in a lithographic process on a substrate, the lithographic process is used to form a structure on the substrate, the structure having at least one feature which has an asymmetry in the printed profile which varies as a function of the focus of the lithographic apparatus on the substrate. A first image of the periodic structure is formed and detected while illuminating the structure with a first beam of radiation. The first image is formed using a first part of non-zero order diffracted radiation. A second image of the periodic structure is formed and detected while illuminating the structure with a second beam of radiation. The second image is formed using a second part of the non-zero order diffracted radiation which is symmetrically opposite to the first part in a diffraction spectrum. The ratio of the intensities of the measured first and second portions of the spectra is determined and used to determine the asymmetry in the profile of the periodic structure and/or to provide an indication of the focus on the substrate. In the same instrument, an intensity variation across the detected portion is determined as a measure of process-induced variation across the structure. A region of the structure with unwanted process variation can be identified and excluded from a measurement of the structure. | 05-22-2014 |
20140204397 | Metrology Method and Apparatus, and Device Manufacturing Method - Methods are disclosed for measuring target structures formed by a lithographic process on a substrate. A grating or other structure within the target is smaller than an illumination spot and field of view of a measurement optical system. The position of an image of the component structure varies between measurements, and a first type of correction is applied to reduce the influence on the measured intensities, caused by differences in the optical path to and from different positions. A plurality of structures may be imaged simultaneously within the field of view of the optical system, and each corrected for its respective position. The measurements may comprise first and second images of the same target under different modes of illumination and/or imaging, for example in a dark field metrology application. A second type of correction may be applied to reduce the influence of asymmetry between the first and second modes of illumination or imaging, for example to permit a more accurate overly measurement in a semiconductor device manufacturing process. | 07-24-2014 |
20140233031 | Substrate and Patterning Device for Use in Metrology, Metrology Method and Device Manufacturing Method - A pattern from a patterning device is applied to a substrate by a lithographic apparatus. The applied pattern includes product features and metrology targets. The metrology targets include large targets and small targets which are for measuring overlay. Some of the smaller targets are distributed at locations between the larger targets, while other small targets are placed at the same locations as a large target. By comparing values measured using a small target and large target at the same location, parameter values measured using all the small targets can be corrected for better accuracy. The large targets can be located primarily within scribe lanes while the small targets are distributed within product areas. | 08-21-2014 |