Abstract: Scatterometry method and apparatus are useful in a lithographic apparatus and device manufacturing. A back focal plane diffraction intensity image of a measurement projection system configured to project a radiation beam onto a target portion of a substrate is measured. A beam of radiation having a first wavelength is directed to the substrate. A diffraction image of a zeroth diffraction order and higher order diffraction from a diffraction structure in the substrate is provided. A first layer (4) of the diffractionstructure provides a diffraction image having only a zeroth diffraction order. A second layer (5) has a periodic structure (6a, 6b) configured such that a lowest spatial frequency of the periodic structure is lower than spatial frequencies of interest of the first structure. From the diffraction image originating from diffraction of the radiation beam in both the first and second layer a critical dimension metrology parameter is determined.

Abstract: 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.

Abstract: A method of determining an overlay error in which asymmetry of a first order of a diffraction pattern is modeled as being a weighted sum of harmonics. Both the first order harmonic and higher order harmonics are non-negligible and weights for both are calculated. The weights are calculated using three or more of sets of superimposed patterns using a least mean square method.

Abstract: A method of measuring a phase difference between two regions in an aberration function: Reference structures are produced on a substrate using illumination that minimizes effects of phase aberration. A grating is produced on the substrate using a phase-shift grating reticle to produce, in the exit pupil, a pair of diffracted non-zero orders, while forbidding other diffracted orders and produces interference fringes formed by interference between the pair. The interference contributes to a first grating on the substrate. Overlay error is measured between the grating and the reference structure using diffraction-based or image-based overlay measurements. A phase aberration function for the exit pupil of the lithographic apparatus can then be determined from the measured overlay errors.

Abstract: 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.

Abstract: 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.

Abstract: Scatterometry method and apparatus are useful in a lithographic apparatus and device manufacturing. A back focal plane diffraction intensity image of a measurement projection system configured to project a radiation beam onto a target portion of a substrate is measured. A beam of radiation having a first wavelength is directed to the substrate. A diffraction image of a zeroth diffraction order and higher order diffraction from a diffraction structure in the substrate is provided. A first layer (4) of the diffractionstructure provides a diffraction image having only a zeroth diffraction order. A second layer (5) has a periodic structure (6a, 6b) configured such that a lowest spatial frequency of the periodic structure is lower than spatial frequencies of interest of the first structure. From the diffraction image originating from diffraction of the radiation beam in both the first and second layer a critical dimension metrology parameter is determined.

Abstract: 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.

Abstract: Calibration of an angularly resolved scatterometer is performed by measuring a target in two or more different arrangements. The different arrangements cause radiation being measured in an outgoing direction to be different combinations of radiation illuminating the target from ingoing directions. A reference mirror measurement may also be performed. The measurements and modeling of the difference between the first and second arrangements is used to estimate separately properties of the ingoing and outgoing optical systems. The modeling may account for symmetry of the respective periodic target. The modeling typically accounts for polarizing effects of the ingoing optical elements, the outgoing optical elements and the respective periodic target. The polarizing effects may be described in the modeling by Jones calculus or Mueller calculus. The modeling may include a parameterization in terms of basis functions such as Zernike polynomials.

Abstract: 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.

Abstract: A method of determining an overlay error in a set of superimposed patterns. The patterns are divided into two and a first part of the pattern has a bias of d+s/2 between the first layer and second layer. A second part of the pattern has a bias of d?s/2 between the first and second layer. The two parts of the pattern are of equal size. To eliminate a particular harmonic s is chosen to be T/(2n) where T is the period of the pattern and n is a positive integer.

Abstract: 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.

Abstract: A method of determining an overlay error in which asymmetry of a first order of a diffraction pattern is modeled as being a weighted sum of harmonics. Both the first order harmonic and higher order harmonics are non-negligible and weights for both are calculated. The weights are calculated using three or more of sets of superimposed patterns using a least mean square method.

Abstract: A coder converts M-bit information words into N-bit code words by generating a first and a second provisional code sequence using a coding rule by which, code words are logically assigned to information words so that a two's complement of a sum of coding bits included in the first provisional code sequence, is always different from a two's complement of a sum of coding bib included in the second provisional code sequence, when a first code state of the first sequence encoded starting from a predetermined original state is identical to a second code state of the second sequence encoded starting from said predetermined original state. Then, selecting either the first sequence or the second sequence depending on a value of at least one parameter that correlates with a DC content of the coded bit stream.

Abstract: The present invention discloses an optical drive and a method for preprocessing a disc readout signal rk of an optical drive on the basis of a set of low-pass filters. The cutoff frequency fC of the filters wk, more particularly, can be set within the optical bandwidth, which improves the Viterbi detection performance in the case of high speed drive operations. Three types of filters are described, in which a Type I shaping filter performs best given a limited hardware cost for the bit detector. Compared to other more advanced noise-whitening techniques, it is only speed dependent and requires little prior knowledge of the channel and noise, thus cheap and easy to design. The invention can be applied in connection with optical disc drives, in particular when high frequency noises are dominant, for example, in the case of high speed operations.

Abstract: A loss of performance of slicer adaptation at high capacities due to the mismatch between the exact bits used in the computation of the RDS for the DC-control on the one hand and the often erroneous threshold decisions that are preliminarily made based on the HF waveform on the other hand, is resolved by performing a new method of DC-control at the encoder: the RDS is modified such that it is not based on the exact channel bits, but on the threshold decisions from a synthetic HF signal waveform that is generated based on a nominal MTF (modulation transfer function) or its IRF (impulse response function) of the channel. In this way, the impact of the erroneous threshold decisions in the receiver are already taken into account at the encoder, and the slicer control is no longer negatively affected thereby.

Abstract: The invention provides an efficient reading device in which, even if one radiation beam should fail, no information is lost and the information can still be read out without time-consuming recurring operations. The present invention solves this problem by providing a reading device (FIG. 5A) and a means (FIG. 4) for forming read-out spots (A, B, C, D, E) that are built up by multiple radiation beams from the radiation source (4). This has the advantage that each read-out spot will have energy contributions from different radiation beams and, should one radiation beam break down, the intensity of some of the read-out spots may indeed diminish, but the information can still be read out thanks to the contributions from other radiation beams.

Abstract: The present invention relates to a method of recording secondary information on a record carrier, in particular on an optical record carrier, besides its content information, whereby it is possible to differentiate the record carrier from other record carrier bearing the same content information, for example by recording an individual identifier. The secondary information is recorded by: forming at predetermined positions dummy patterns (23), preferably at the same moment as when recording the content information, and recording the secondary information by selectively modifying the dummy patterns, thereby obtaining modified dummy patterns (24), wherein the dummy patterns as well as the modified dummy patterns correspond to valid channel words. The invention further relates to an apparatus for recording secondary information, to a record carrier, and to a method and to an apparatus for reproducing the secondary information.

Abstract: Devices and methods, record carrier and signal for embedding, extracting, carrying and representing secondary signal such as a copy protection signal embedded in a primary signal such as a blu ray disc signal modulated by a 17PP RMTR runlength limited modulation code. Each frame comprises a frame sync patterns followed by DC control blocks each including a DC control bit. Two modulation tables are used. Each bit of the secondary signal is represented by a relationship between the polarity of the frame sync signal and the values of the DC control bits in a fashion which complies with the constraints of the modulation code and the DC control algorithm.

Abstract: Proposed is a method and apparatus for writing/reading a data block onto/from an information carrier with M-spots schemes and such an information carrier. The method comprises the steps of dividing the data block into N portions according to predetermined writing capacities for each one of the N writers of the M-spots schemes, N and M being integers not less than 2 and N<=M, and writing simultaneously the N portions of data onto the information carrier with the N writers correspondingly. Since all the writers are processing different portions of one data block, the data rate of processing one data block is increased almost N times. Therefore the period that the certain buffer capacity occupied by a data block is decreased substantially, total buffering capacity may be decreased, that means the cost of the schemes is dropped substantially.