Showing papers by "ASML Holding published in 2004"

System and method for lithography simulation

Abstract: In one aspect, the present invention is directed to a technique of, and system for simulating, verifying, inspecting, characterizing, determining and/or evaluating the lithographic designs, techniques and/or systems, and/or individual functions performed thereby or components used therein. In one embodiment, the present invention is a system and method that accelerates lithography simulation, inspection, characterization and/or evaluation of the optical characteristics and/or properties, as well as the effects and/or interactions of lithographic systems and processing techniques.

Lithographic apparatus and methods, patterning structure and method for making a patterning structure, device manufacturing method, and device manufactured thereby

Abstract: Without changing the initial illumination setting and resist process condition, a method according to one embodiment includes manipulating the design shape by application of additional and non-printable assist features (“sub-resolution assist features” or “SRAF”), such that CD sensitivities of the pattern feature are minimized. The SRAF may comprise chrome dots, or any other design objects of different sizes, shapes, and/or types, which can modulate the intensity and/or phase of the original pattern. to minimize an aberration sensitivity of selected ones of the plurality of pattern features A pattern that was not designed to include SRAF may be modified to include SRAF. In such a method, one or more aspects of the assist features are selected to reduce the aberration-induced image variation for a pattern and its sensitivity to aberrations.

Immersion photolithography system and method using inverted wafer-projection optics interface

Abstract: A liquid immersion photolithography system includes an exposure system that exposes a substrate with electromagnetic radiation, and also includes a projection optical system that focuses the electromagnetic radiation on the substrate. A liquid supply system provides a liquid between the projection optical system and the substrate. The projection optical system is positioned below the substrate.

Lithographic printing with polarized light

Abstract: The present invention provides systems and methods for improved lithographic printing with polarized light. In embodiments of the present invention, polarized light (radially or tangentially polarized) is used to illuminate a phase-shift mask (PSM) and produce an exposure beam. A negative photoresist layer is then exposed by light in the exposure beam. A chromeless PSM can be used. In further embodiments of the present invention, radially polarized light is used to illuminate a mask and produce an exposure beam. A positive photoresist layer is then exposed by light in the exposure beam. The mask can be an attenuating PSM or binary mask. A very high image quality is obtained even when printing contact holes at various pitches in low k applications.

Device manufacturing method and a substrate

Abstract: A method of reducing the effect of bubbles on the imaging quality of an immersion lithography apparatus, in which a top coating is applied to a substrate to keep bubbles away from a radiation sensitive layer of the substrate.

Lithographic apparatus, device manufacturing method and a substrate

Abstract: A substrate is provided with a coating of material which is substantially transparent to the wavelength of the projection beam. The coating may be thicker than the wavelength of the projection beam and have a refractive index of the coating such that the wavelength of the projection beam is shortened as it passes through it. This allows the imaging of smaller features on the substrate. Alternatively, the coating may be used with a liquid supply system and act to keep bubbles away from a radiation sensitive layer of the substrate.

Plasma sources for EUV lithography exposure tools

Abstract: The source is an integral part of an extreme ultraviolet lithography (EUVL) tool. Such a source, as well as the EUVL tool, has to fulfil extremely high demands both technical and cost oriented. The EUVL tool operates at a wavelength in the range 13–14 nm, which requires a major re-thinking of state-of-the-art lithography systems operating in the DUV range. The light production mechanism changes from conventional lamps and lasers to relatively high temperature emitting plasmas. The light transport, mainly refractive for DUV, should become reflective for EUV. The source specifications are derived from the customer requirements for the complete tool, which are: throughput, cost of ownership (CoO) and imaging quality. The EUVL system is considered as a follow up of the existing DUV based lithography technology and, while improving the feature resolution, it has to maintain high wafer throughput performance, which is driven by the overall CoO picture. This in turn puts quite high requirements on the collectable in-band power produced by an EUV source. Increased, due to improved feature resolution, critical dimension (CD) control requirements, together with reflective optics restrictions, necessitate pulse-to-pulse repeatability, spatial stability control and repetition rates, which are substantially better than those of current optical systems. All together the following aspects of the source specification will be addressed: the operating wavelength, the EUV power, the hot spot size, the collectable angle, the repetition rate, the pulse-to-pulse repeatability and the debris induced lifetime of components.

Lithographic apparatus, device manufacturing method and device manufacturing thereby

Abstract: The X, Y and Rx positions of a mask stage are measured using two optical encoder-reading heads measuring displacements of respective grid gratings mounted on the mask stage. The grid gratings are preferably provided on cut-away portions of the mask table so as to be coplanar with the pattern on the mask itself. Measurements of the table position in the other degrees of freedom can be measured with capacitative or optical height sensors.

Multilayer high kappa dielectric films

Abstract: A new multilayer dielectric film for improving dielectric constant and thermal stability of gate dielectrics is provided. The multilayer dielectric film comprises a first layer formed of a metal oxide material having a high dielectric constant, and a second layer formed on the first layer. The second layer is formed of a metal silicate material having a dielectric constant lower than the dielectric constant of the first layer. A semiconductor transistor incorporating the multilayer dielectric film is also provided.

Lithographic apparatus and method for optimizing an illumination source using photolithographic simulations

Abstract: A method for optimizing the illumination conditions of a lithographic apparatus by computer simulation, the lithographic apparatus including an illuminator and a projection system, includes defining a lithographic pattern to be printed on the substrate, selecting a simulation model, selecting a grid of source points in a pupil plane of the illuminator, calculating separate responses for individual source points, each of the responses representing a result of a single or series of simulations using the simulation model, and adjusting an illumination arrangement based on analysis of accumulated results of the separate calculations.

Off-axis leveling in lithographic projection apparatus

Abstract: In an off-axis levelling procedure a height map of the substrate is generated at a measurement station. The height map is referenced to a physical reference surface of the substrate table. The physical reference surface may be a surface in which is inset a transmission image sensor. At the exposure station the height of the physical reference surface is measured and related to the focal plane of the projection lens. The height map can then be used to determine the optimum height and/or tilt of substrate table to position the exposure area on the substrate in best focus during exposure. The same principles can be applied to (reflective) masks.

Full optical column characterization of DUV lithographic projection tools

Abstract: Advanced optical systems for low k1 lithography require accurate characterisation of various imaging parameters to insure that OPC strategies can be maintained. Among these parameters lens aberrations and illumination profiles are the most important optical column charcteristics. The phase measurement interferometer hardware (ILIAS: Integrated Lens Interferometer At Scanner) integrated into high-NA ArF lithographic projection tools opens novel pathways to measure and control tool critical performance parameters. In this presentation we address new extensions of this in-line tool that will allow the measurement of optical parameters of the full optical column. The primary functionality of the ILIAS system is to measure and analyse wavefront aberrations across the full image field with high accuracy and speed. In this paper performance data of the in-line wavefront sensor over multiple high-NA ArF lithographic systems is presented. In addition to the acquisition of wavefront aberrations in terms of Zernike polynomials, detailed measurements of high resolution wavefronts are now possible. Examples of such wavefronts and PSD analysis thereof are presented. Besides the projection lens properties, the detailed shape of the pupil distribution and transmission (apodisation) becomes critical for system optimization. The integrated ILIAS hardware can also be used to measure these parameters.

Lithographic projection apparatus and a device manufacturing method using such lithographic projection apparatus

Abstract: A lithographic projection apparatus includes a measurement system for measuring changes in projection system aberrations with time, and a predictive control system for predicting variation of projection system aberrations with time on the basis of model parameters and for generating a control signal for compensating a time-varying property of the apparatus, such as the OVL values (X-Y adjustment) and the FOC values (Z adjustment) of a lens of the projection system for example. An inline model identification system is provided for estimating model parameter errors on the basis of projection system aberration values provided by the predictive control system and measured projection system aberration values provided by the measurement system, and an updating system utilizes the model parameter errors for updating the model parameters of the predictive control system in order to maintain the time-varying property within acceptable performance criteria.

Source and mask optimization

Abstract: An illumination source is optimized by changing the intensity and shape of the illumination source to form an image in the image plane that maximizes the minimum ILS at user selected fragmentation points while forcing the intensity at the fragmentation points to be within a small intensity range. An optimum mask may be determined by changing the magnitude and phase of the diffraction orders to form an image in the image plane that maximizes the minimum ILS at user selected fragmentation points while forcing the intensity at the fragmentation points to be within a small intensity range. An optimal mask may be used to create a CPL mask by assigning areas of minimum transmission in an optimum transmission mask a −1, and areas of maximum transmission a +1. Primitive rectangles having a size set to a minimum feature size of a mask maker are assigned to the located minimum and maximum transmission areas and centered at a desired location. The edges of the primitive rectangle are varied to match optimal diffraction orders O(m,n). The optimal CPL mask O CPL (X,Y) is then formed.

Lithographic apparatus, measurement system, and device manufacturing method

Abstract: The invention pertains to a measurement system for measuring displacement of a moveable object relative to a base in at least a first direction of measurement, the moveable object having at least one reference part that is moveable in a plane of movement relative to the base, the actual movements of the reference part being within an area of said plane of movement that is bounded by a closed contour having a shape. The measurement system comprises a sensor head that operatively communicates with a planar element. The sensor head is mounted onto the base and the planar element being mounted onto the reference part of the moveable object or the other way around, wherein the planar element has a shape that is essentially identical to the shape of the closed contour.

Feature optimization using interference mapping lithography

Abstract: Disclosed concepts include a method of, and program product for, optimizing an illumination profile of a pattern to be formed in a surface of a substrate relative to a given mask. Steps include mathematically representing resolvable feature(s) from the given mask, generating an interference map representation from the previous step, modifying the interference map representation to maximize intensity corresponding to the resolvable features, and determining assist feature size(s) such that intensity side lobes do not print.

Interface unit, lithographic projection apparatus comprising such an interface unit and a device manufacturing method

Abstract: An interface unit for transferring objects, such as substrates, is presented. The interface unit includes a first object transfer path to transfer objects between a track configured to process objects and a lithographic exposure unit configured to expose objects, wherein the interface unit is also provided with a second object transfer path extending through a closable transfer opening to an external space to transfer objects between the external space and the lithographic exposure unit. Furthermore, the invention relates to a lithographic apparatus provided with a lithographic exposure unit and an interface unit according to the invention.

Method for coating a substrate for euv lithography and substrate with photoresist layer

Abstract: A method for coating a substrate for EUV lithography includes coating a photoresist layer on the substrate. A device manufacturing method using a lithographic projection apparatus includes providing a substrate that is at least partially covered by a photoresist layer by coating the photoresist layer on the substrate and projecting a patterned beam of radiation onto a target portion of the photoresist layer. A substrate includes a photoresist layer.

Contact hole reticle optimization by using interference mapping lithography (IML)

Abstract: The theory of interference mapping lithography (IML) is presented for low k1 (k1<0.4) contact hole imaging. IML with a coherent source is shown to be analogous to methods used in creating a Fresnel lens. With IML for a partially coherent source, the interference map is calculated by using the first eigenfunction of the transmission cross coefficient (TCC). From this interference map, clear 0° AFs and for clear 180° AFs are placed in the optimal location. Thus, IML is a method to place AFs via a model. From the interference map, a method for creating a CPL mask is demonstrated. Using IML, techniques to optimize a binary mask or a CPL mask are presented for maximizing the exposure latitude (EL) or depth of focus (DOF). These techniques are verified with simulation. Using IML for maximum EL, a CPL mask with 100nm (k1=0.39) contacts was created and exposed on an ASML /1100 ArF scanner using NA of 0.75 and Quasar illumination (σin=0.72, σout=0.92, span angle=20°). Measurements on the exposed wafers show that IML CPL results in printing 100nm contacts through pitch (200nm minimum pitch to isolated) with 0.45μm DOF at 10% EL.

Benefits and limitations of immersion lithography

Abstract: Liquid immersion has been used for more than 100 years to increase the numeric aperture (NA) and resolution in optical microscopy. We explore the benefits and limitations of immersion technology in lithography. Immersion optical lithography has the potential to extend the resolution below 40 nm. The theory of immersion is decribed. Simulations show that a 193-nm immersion system at NA = 0.95 can double the depth of focus as compared to a dry system. Also, an immersion 193-nm system at NA = 1.05 has slightly more depth of focus than a 157-nm dry system at NA = 0.85. However, the exposure latitude at 193 nm is decreased due to the impact of polarization in imaging. Design schemes are presented to realize an immersion step and scan system. Two configuration approaches are proposed and explored. A localized shower type solution may be preferred over a bath type solution, because the impact on the step and scan platform design is significantly less. However, scanning over the wafer edge becomes the main design challenge with a shower solution. Studies are presented that look at the interaction of immersion fluids with the lens and the photoresist. Water seems to be a likely candidate, as it does not impact productivity of the step and scan system; however, focus and aberration levels need to be carefully controlled. For 157 nm, per-fluor-polyether (PFPE) materials are currently being studied, but their characteristics may limit the productivity of the exposure system. Further research on fluid candidates for 157-nm immersion is required.

Extending optical lithography with immersion

Abstract: As the semiconductor industry looks to the future to extend manufacturing beyond 100nm, ASML have developed a new implementation of an old optical method for lithography. Immersion lithography can support the aggressive industry roadmap and offers the ability to manufacture semiconductor devices at a low k1. In order to make immersion lithography a production worthy technology a number of challenges have to be overcome. This paper provides the results of our feasibility study on immersion lithography. We show through experimental and theoretical evaluation that we can overcome the critical concerns related to immersion lithography. We show results from liquid containment tests focussing on its effects on the scan speed of the system and the formation of micro-bubbles in the fluid. We present fluid-to-resist compatibility tests on resolution, using a custom-built interference setup. Ultimate resolution is tested using a home build 2 beam interference setup. ASML built a prototype full field scanning exposure system based on the dual stage TWINSCAN platform. It features a full field 0.75 NA refractive projection lens. We present experimental data on imaging and overlay.

Optical attenuator device, radiation system and lithographic apparatus therewith and device manufacturing method

Abstract: An optical attenuator device operates to remove a part of a beam of radiation having a higher than average intensity using at least one optical attenuator element. The device has application in a radiation system, and/or a lithographic apparatus, in particular a scanning lithographic apparatus, wherein the optical attenuator element(s) are provided in a central part of the beam, for example perpendicularly to a scanning direction.

Immersion photolithography system comprising microchannel nozzles

Abstract: A liquid immersion photolithography system includes an exposure system that exposes a substrate with electromagnetic radiation and includes a projection optical system (100) that focuses the electromagnetic radiation on the substrate (101). A liquid supply system provides liquid flow between the projection optical system (100) and the substrate (101). An optional plurality of micronozzles (416) are arranged around the periphery of one side of the projection optical system so as to provide a substantially uniform velocity distribution (107) of the liquid flow in an area where the substrate is being exposed.

Method and apparatus for providing optical proximity features to a reticle pattern for deep sub-wavelength optical lithography

Abstract: A method of generating a mask design having optical proximity correction features disposed therein. The methods includes the steps of obtaining a desired target pattern having features to be imaged on a substrate; determining an interference map based on the target pattern, the interference map defining areas of constructive interference and areas of destructive interference between at least one of the features to be imaged and a field area adjacent the at least one feature; and placing assist features in the mask design based on the areas of constructive interference and the areas of destructive interference.

Level sensor for lithographic apparatus

Abstract: A level sensor for a lithographic projection apparatus includes a light source configured to direct light onto a substrate to be measured, a detector configured to detect light reflected from the substrate, and a processor configured to calculate a difference between measurements made with the filter in the first configuration and in the second configuration. The sensor is adjustable between a first configuration, in which the light is given a first property, and a second configuration, in which the light is given a second property. The sensor may include a polarizing filter, such that the first and second properties are different polarization states.

System and method for calibrating a spatial light modulator

Abstract: A method and system as used to calibrate a reflective SLM. The system can include the SLM having an array of pixels and a projection optical system resolving individual pixels and having an apodized pupil. During a calibration operation, the pixels of the SLM receive varying voltage values to move them through various angles. Light reflecting from the pixels during these movements forms individual images for each pixel at each angle. The light passes through the apodized pupil and is received on one or more sections of a detector. The apodization pattern is selected so that individual pixels remain well resolved with strong sensitivity to the pixel mirror tilt. The light intensity received for each pixel at each angle is correlated to the voltage value received at the pixel to tilt the pixel to that angle producing a result signal used by a control device to calibrate the SLM.

OML: optical maskless lithography for economic design prototyping and small-volume production

Abstract: The business case for Maskless Lithography is more compelling than ever before, due to more critical processes, rising mask costs and shorter product cycles. The economics of Maskless Lithography gives a crossover volume from Maskless to mask-based lithography at surprisingly many wafers per mask for surprisingly few wafers per hour throughput. Also, small-volume production will in many cases be more economical with Maskless Lithography, even when compared to “shuttle” schemes, reticles with multiple layers, etc. The full benefit of Maskless Lithography is only achievable by duplicating processes that are compatible with volume production processes on conventional scanners. This can be accomplished by the integration of pattern generators based on spatial light modulator technology with state-of-the-art optical scanner systems. This paper reports on the system design of an Optical Maskless Scanner in development by ASML and Micronic: small-field optics with high demagnification, variable NA and illumination schemes, spatial light modulators with millions of MEMS mirrors on CMOS drivers, a data path with a sustained data flow of more than 250 GPixels per second, stitching of sub-fields to scanner fields, and rasterization and writing strategies for throughput and good image fidelity. Predicted lithographic performance based on image simulations is also shown.

Lithographic apparatus and device manufacturing method, and measurement systems

Abstract: The invention pertains to a lithographic apparatus including a radiation system configured to condition a beam of radiation; a projection system configured to project the beam of radiation onto a target portion of a substrate; a displacement device configured to move the moveable object relative to the projection system in substantially a first direction and a second direction differing from the first direction; and a measuring device configured to measure a displacement of the moveable object in a third direction, which is substantially perpendicular to the first direction and to the second direction, wherein the measuring device may include an encoder system

Method of optical proximity correction design for contact hole mask

Abstract: Disclosed concepts include a method of optimizing an illumination profile of a pattern to be formed in a surface of a substrate. Illumination is optimized by defining a transmission cross coefficient (“TCC”) function determined in accordance with an illumination pupil and a projection pupil corresponding to an illuminator, representing at least one resolvable feature of a mask to be printed on the substrate by at least one impulse function, and creating an interference map of a predetermined order based on the at least one impulse function and the TCC function, wherein the interference map represents the at least one resolvable feature to be printed on the substrate and areas of destructive interference.

Lithographic apparatus and device manufacturing method with feed-forward focus control

Abstract: A lithographic apparatus includes an illumination system configured to provide a beam of radiation, a first support structure configured to support a patterning device, a second support that includes a substrate holder for holding a substrate, a projection system configured to project the patterned beam of radiation onto the substrate, and a servo unit configured to position the substrate holder. The apparatus further includes a sensor unit configured to determine a distance of at least one location point on the surface of the substrate relative to a reference plane, a memory unit configured to store surface information of the substrate based on respective distances of corresponding location points on the substrate surface, and a calculating unit configured to determine a feed-forward set-point signal based on the stored surface information, such that the feed-forward set-point signal is forwardly fed to the servo unit in order to position the substrate holder.