Abstract: Cleaning of optical components for use in a lithographic projection apparatus can be carried out by irradiating a space within the apparatus containing the optical component with UV or EUV radiation having a wavelength of less than 250 nm, in the presence of an oxygen-containing species selected from water, nitrogen oxide and oxygen-containing hydrocarbons. Generally, the space will be purged with an ozone-less purge gas which contains a small amount of the oxygen-containing species in addition to the usual purge gas composition. The technique can also be used in an evacuated space by introducing a low pressure of the oxygen-containing species into the space.

Abstract: The present invention provides a method of operating a lithographic projection apparatus including calculating a change in aberration effect in the projection system, due to heating effects, as a function of time, based on at least one set of predetermined parameters; and adjusting the lithographic projection apparatus to compensate for the calculated change in aberration effect. The parameters are obtained by a calibration operation, which may comprise a coarse calibration followed by at least one fine calibration. The coarse calibration yields a first estimate of at least a subset of the parameters. The estimate can be used as an input for a subsequent fine calibration. The calibration may also comprise a single fine calibration.

Abstract: A method of generating complementary masks for use in a multiple-exposure lithographic imaging process. The method includes the steps of identifying “horizontal” critical features and “vertical” critical features from a plurality of features forming a layout; identifying interconnection areas which are areas in which one of the horizontal critical features or the vertical critical features contacts another feature of the layout; defining a set of primary parameters on the basis of the proximity of the plurality of features relative to one another; and generating an edge modification plan for each interconnection area based on the primary parameters. A horizontal mask pattern is then generated by compiling the horizontal critical features, a first shield plan for the vertical critical features and the interconnection areas containing a horizontal critical feature modified by the edge modification plan.

Abstract: The reflectivity of multilayered EUV mirrors tuned for 11-16 nm, for which the two-component Mo/Be and Mo/Si multilayered systems are commonly used, is enhanced by incorporating additional elements and their compounds mainly from period 5 of the periodic table. In addition, the reflectivity performance of the multilayer stacks is further enhanced by a numerical global optimization procedure by which the layer thicknesses are varied for optimum performance in, contradistinction to the constant layer thickness—i.e. constant partition ratio—multilayer stacks commonly designed and, fabricated hitherto. By incorporating additional materials with differing complex refractive indices in various regions of the stack, or by wholly replacing one of the components (typically Mo), we have observed peak reflectivity enhancements of up to 5% for a single reflector compared to a standard unoptimized stack. The additional materials used are: Rb, RbCl, Sr, Y, Zr, Ru, Rh, Tc, Pd, Nb and Be.

Abstract: An object table is supported in a vacuum chamber by an elongate beam or beams extending though elongate slots in opposite walls of the vacuum chamber. Displacement of the beam in two orthogonal directions is achieved by displacing the beam laterally and longitudinally. The elongate slots are sealed by sliding plates supported by a gas bearing. The beam is driven longitudinally by linear motors acting against between a balance mass and the beam. The beam is driven laterally by linear motors acting between a balance mass and the sliding plates. The two balance masses may be separate or combined.

Abstract: An illumination system for a microlithographic stepper has a light source that emits light of selected wavelength(s) along an optical path toward a photomask. An aperture mask is positioned in the path of the illumination light and between the light source and the photomask. The aperture mask has a dithered pattern of pixels. The intensity of the pattern controls the illumination of the photomask. The masking aperture pattern defines one or more zones of illumination. Each zone has elements that are patterned in accordance with a selected wavelength of incident light to diffract the incident light into an illumination pattern for illuminating a photomask. Each of the elements is constructed with a matrix of pixels. In the preferred embodiment the array of pixels is 8×8. The number of elements is generally greater than 3×3.

Abstract: A masking aperture for a photomask illumination system provides controlled on-axis and off-axis illumination. The masking aperture has a dithered pattern of pixels. The intensity of the pattern controls the illumination of the photomask. The masking aperture pattern defines one or more zones of illumination. Zones comprise elements that are patterned in accordance with a selected wavelength of incident light to diffract the incident light into an illumination pattern for illuminating a photomask. Each of the elements is constructed with a matrix of pixels. In the preferred embodiment the array of pixels is 8×8. The number of elements is generally greater than 3×3.

Abstract: A plate with substantially constant thickness is used to compensate for the residual distortion in the image projected by a high-quality projection lens for lithography. The two surfaces of the plate have an identical aspherical profile, whose shape has been calculated using the measured distortion map of the lithographic objective. The figuring process applied to the plate uses the principle of polishing in the presence of an elastic deformation, so as to achieve the desired aspherical shape on both sides.

Abstract: A masking aperture for a photomask illumination system provides controlled on-axis and off-axis illumination. The masking aperture has a dithered pattern of pixels. The intensity of the pattern controls the illumination of the photomask. The masking aperture pattern defines one or more zones of illumination. Zones comprise elements that are patterned in accordance with a selected wavelength of incident light to diffract the incident light into an illumination pattern for illuminating a photomask. Each of the elements is constructed with a matrix of pixels. In the preferred embodiment the array of pixels is 8×8. The number of elements is generally greater than 3×3.

Abstract: In a lithographic projection apparatus, an object such as a mask is shielded from stray particles by a particle shield using electromagnetic fields. The fields may be a uniform electric field, a non-uniform electric field or an optical breeze. The particle shield means are fixed to the mask holder rather than the mask.

Abstract: In a lithographic projection apparatus, a grating spectral filter is used to filter an EUV projection beam. The grating spectral filter is preferably a blazed, grazing incidence, reflective grating. Cooling channels may be provided in or on the rear of the grating spectral filter. The grating spectral filter may be formed of a material effectively invisible to the desired radiation.

Abstract: A lithographic projection apparatus includes conduits which supply utilities to components in a vacuum chamber such as object tables and/or associated motors and/or sensors. The conduits are shielded from exposure to the vacuum by conduit conducts having at least the same number of degrees of freedom as their associated object table.

Abstract: A microphone or other acoustic sensor is used to detect sound or other vibrations caused by the passage of pulses of radiation of a projection beam. The measured vibrations may be used to determine the intensity of the projection beam or the presence of contaminants. The vibrations are caused by absorption of the beam pulses in an absorptive gas or by objects, e.g. the substrate or mirrors in the projection lens, on which the projection beam is incident.

Abstract: A projection lithography system provides a cross-quadrupole illumination pattern in combination with a translucent substrate having boundary relief features. The features are spaced close together so that they are not imaged in a focal plane, but generate a dark image of the space between the features in the focal plane.

Abstract: In an interferometric alignment system provides an alignment signal for reproducibly registering a reticle 10 with a wafer 12. The radiation from a laser 50, which is the illumination source for the interferometer, is modulated by a phase modulator 52 to eliminate spurious noise from the alignment signal.

Abstract: A plate with substantially constant thickness is used to compensate for the residual distortion in the image projected by a high-quality projection lens for lithography. The two surfaces of the plate have an identical aspherical profile, whose shape has been calculated using the measured distortion map of the lithographic objective. The figuring process applied to the plate uses the principle of polishing in the presence of an elastic deformation, so as to achieve the desired aspherical shape on both sides.

Abstract: A lithographic projection apparatus has a radiation system for supplying a projection beam of radiation, a mask table provided with a mask holder for holding a mask, a substrate table provided with a substrate holder for holding a substrate, a projection system for imaging an irradiated portion of the mask onto a target portion of the substrate, first driving means, for moving the mask table in a given reference direction substantially parallel to the plane of the table, second driving means, for moving the substrate table parallel to the reference direction so as to be synchronous with the motion of the mask table.

Abstract: Aberrations of an imaging system (PL) can be detected in an accurate and reliable way by imaging, by means of the imaging system, a circular phase structure (22) on a photoresist (PR), developing the resist and scanning it with a scanning detection device (SEM) which is coupled to an image processor (IP). The circular phase structure is imaged in a ring structure (25) and each type of aberration, like coma, astigmatism, three-point aberration, etc. causes a specific change in the shape of the inner contour (CI) and the outer contour (CE) of the ring and/or a change in the distance between these contours, so that the aberrations can be detected independently of each other. Each type of aberration is represented by a specific Fourier harmonic (Z-), which is composed of Zernike coefficients (Z-), each representing a specific lower or higher order sub-aberration.

Abstract: A lithographic apparatus exposes a radiation sensitive layer on a substrate to the pattern on a mask including pattern areas and opaque support. The apparatus uses a beam having a trapezoidal profile to provide a more uniform exposure at sub-field stitches in the event of any positional inaccuracies. The trapezoidal beam profile is generated by changing a characteristic, such as size or position, of the illumination beam on the mask during an exposure period.

Abstract: A lithographic apparatus of the scanning type in which reticle masking blades 7 are opened at the beginning of a scan. Means are provided to compensate for an increase in the intensity density of the illumination beam as the reticle masking blades are opened. These means may comprise lamp control means 10 for controlling a compensating decrease in the lamp intensity. The reticle masking blades 70 may be manufactured of, e.g., quartz and provided with a reflective rear coating, e.g. of aluminum, so that portions of the illumination beam intercepted by the reticle masking blades are totally internally reflected.