Abstract:
A measurement method comprising using multiple radiation poles to illuminate a diffraction grating on a mask at a mask side of a projection system of a lithographic apparatus, coupling at least two different resulting diffraction orders per illumination pole through the projection system, using the projection system to project the diffraction orders onto a grating on a wafer such that a pair of combination diffraction orders is formed by diffraction of the diffraction orders, coupling the combination diffraction orders back through the projection system to detectors configured to measure the intensity of the combination diffraction orders, and using the measured intensity of the combination diffraction orders to measure the position of the wafer grating.
Abstract:
Controlling, based on characteristics, a lithographic apparatus having an exposure mode configured to expose a wafer held by a substrate table to an image of a pattern on a production reticle via a projection system, wherein in the exposure mode the production reticle is held at a reticle stage and is protected by a pellicle, the method comprising determining the characteristics of the projecting in a calibration mode, and the controlling comprising moving in the exposure mode at least one of the projection system, the reticle stage and the substrate table during the exposing in dependence on the characteristics.
Abstract:
A method of determining a configuration of a projection system for a lithographic apparatus, wherein manipulators of the projection system manipulate optical elements so as to adjust its optical properties, the method comprising: receiving dependencies of the optical properties of the projection system on a configuration of the manipulators, receiving a plurality of constraints of the manipulators, formulating a cost function, wherein the cost function represents a difference between the optical properties of the projection system for a given configuration of the manipulators and desired optical properties, wherein the cost function is formulated using the dependency of the optical properties on the configuration of the manipulators, scaling the cost function into a scaled variable space, wherein the scaling is performed by using the plurality of constraints and finding a solution configuration of the manipulators which substantially minimises the scaled cost function subject to satisfying the plurality of constraints.
Abstract:
A method of reducing an aberration of a lithographic apparatus, the method comprising measuring the aberration, taking the measured aberration into account, estimating a state of the lithographic apparatus, calculating a correction using the estimated state, and applying the correction to the lithographic apparatus.
Abstract:
Lithographic apparatus and device manufacturing methods are disclosed. In one arrangement there is provided an immersion lithographic apparatus comprising a projection system (PS). The projection system is configured to project a patterned radiation beam through an immersion liquid onto a target portion of a substrate. An external surface of the projection system comprises a first surface (102). The first surface has a non-planar shape. An element (106) is attached to the first surface and positioned so that at least a portion of the element contacts the immersion liquid in use. The element comprises a closed loop of continuously integral material in a preformed state and conforming to the non-planar shape of the first surface.
Abstract:
Systems and methods are provided for measuring aberration in a lithographic apparatus. A radiation beam is modulated using an array of individually controllable elements (PD), and the modulated beam is projected using a projection system (PS). A pattern is provided on the array of individually controllable elements (PD) to modulate the radiation beam, and the pattern comprises a repeating structure that is formed from a plurality of features that are dimensioned such that first order diffraction of the radiation beam substantially fills the pupil of the projection system. A sensor (S) detects the projected radiation and measures interference in the radiation projected by the projection system (PS). Aberration in the detected radiation beam is then measured.
Abstract:
Disclosed is source selection module for spectrally shaping a broadband illumination beam to obtain a spectrally shaped illumination beam. The source selection module comprises a beam dispersing element for dispersing the broadband illumination beam; a grating light valve module for spatially modulating the broadband illumination beam subsequent to being dispersed; and a beam combining element to recombine the spatially modulated broadband illumination beam to obtain an output source beam.
Abstract:
Described herein are apparatuses and techniques for suppressing a zeroth order portion of a configured radiation beam. In some embodiments, an extreme ultraviolet (EUV) lithographic apparatus for forming an image on a substrate by use of an EUV radiation beam that is configured by a patterning device comprising a pattern of reflective regions and partially reflective regions, wherein the partially reflective regions are configured to suppress and apply a phase shift to a portion of the EUV radiation beam, may include a projection system. The projection system may be configured to suppress a zeroth order portion of a configured EUV radiation beam, and direct an unsuppressed portion of a configured EUV radiation beam towards a substrate to form an image on the substrate.
Abstract:
A phase stepping method for determining an aberration map for a projection system and an apparatus for carrying out said method. The method uses first patterned region arranged in an object plane of the projection system and a second patterned region arranged in an image plane of the projection system. At least one of the first and second patterning regions is moved in a shearing direction to generate an oscillating phase stepping signal. A set of coefficients that characterize the aberration map of the projection system are determined by equating the phase of a harmonic of the oscillating signal at each of the plurality of positions on the radiation detector to a combination of a plurality of differences in the aberration map between a pair of positions in a pupil plane of the projection system and solving to find the set of coefficients.
Abstract:
A method of determining a sensor contribution to a measurement of apodization. The method comprises directing a radiation beam through an aperture when the aperture is in a first configuration having a first aperture diameter, the first aperture diameter being smaller than a diameter of the radiation beam, receiving the radiation beam at the sensor, obtaining a first measurement of an amount of radiation detected by the sensor in a first region of the sensor, wherein the radiation beam is not incident on the first region and determining, based on the first measurement, a sensor contribution to a measurement of apodization.