Nikon Corporation

Noriyuki Hirayanagi

Tomoharu Fujiwara

Teruaki Okino

Kazuaki Suzuki

Keiichi Tanaka

Hajime Yamamoto

Mamoru Nakasuji

Shintaro Kawata

Takehisa Yahiro

Jin Udagawa

Tohru Isogami

A method to measure the height-direction position of a mask M in an exposure device having a function to irradiate the mask M with light emitted from a light source and transfer a pattern formed on the mask M onto a photosensitive substrate such as a wafer by a projection optical system, a mask surface height-direction position measurement method characterized by moving, before measuring the height-direction position of the mask M, an exposure area defining memberwhich is installed between the mask M and the projection optical system and defines an exposure area at the time of exposure.

Method of measuring the position of a mask surface along the height direction, exposure device, and exposure method

Exposure apparatus are disclosed that can control, to high precision, exposure doses on a photosensitive substrate of a mask pattern defined on a reflective mask as the pattern is being exposed on the substrate using a projection-optical system. An exemplary apparatus includes a first illumination sensor for detecting light that is incident on a reflective mask from an illumination system and a second illumination sensor for detecting light that has propagated from the illumination system to a reference reflective surface on the reflective mask, reflected from the reference reflective surface, and arrived at an image surface of the projection-optical system. Calibration of the first sensor is performed based on detection data obtained by the first sensor and detection data obtained by the second sensor. Exposure of the substrate is controlled based on the detection data obtained by the calibrated first sensor.

Illumination-sensor calibration methods, and exposure methods and apparatus and device-manufacturing methods including same, and reflective masks used in same

An exposure apparatus transfers a pattern from a mask onto a sensitive substrate. A film protects the mask, and a film frame, between the mask and the film, holds the film spaced away from a surface of the mask. The film has a first transmittance for radiation of a necessary wavelength and has a second transmittance for radiation of an unnecessary wavelength; the first transmittance is higher than the second transmittance. The film might reflect or absorb the unnecessary wavelength. The necessary wavelength may be an exposure wavelength and may also be in the range of extreme ultra violet radiation. An atmosphere around the mask transitions from an air atmosphere to a reduced-pressure atmosphere, or from a reduced-pressure atmosphere to an air atmosphere, at a speed that allows a difference between a pressure applied to one surface of the film and a pressure applied to the other surface of the film to be held at a predetermined value or smaller.

Mask and exposure apparatus

With respect to a substrate conveyor apparatus that, being a substrate conveyor apparatus that carries substrate on which patterns are formed, carries the substrate in a state protected by a protective cover when the substrate is not used, a substrate conveyor apparatus having a cover protection means that covers the inner surface of the protective cover when the substrate is used.

Substrate conveyor apparatus, substrate conveyance method and exposure apparatus

A method to measure the height-direction position of a mask M in an exposure device having a function to irradiate the mask M with light emitted from a light source and transfer a pattern formed on the mask M onto a photosensitive substrate such as a wafer by a projection optical system, a mask surface height-direction position measurement method characterized by moving, before measuring the height-direction position of the mask M, an exposure area defining memberwhich is arranged between the mask M and the projection optical system and defines an exposure area at the time of exposure.

Methods and apparatus for alignment of masks and wafers in charged-particle-beam (CPB) pattern-transfer use optical position sensors to determine the positions of a mask or a mask stage with respect to an axis of a CPB optical system. The optical position sensor uses optical reference marks provided on the mask or mask stage. Determination of the position of the mask of the mask stage permits a coarse alignment of the mask or the mask stage. CPB reference marks are provided on masks, mask stages, wafers, and wafer stages, permitting alignment of the mask stage or the mask with respect to the wafer stage or wafer, respectively, using the charged particle beam. The charged particle beam is scanned with respect to the wafer or wafer-stage CPB reference marks to determine a deflection corresponding to an alignment of the CPB reference marks of the mask and wafer (or mask stage and wafer stage). Use of the charged particle beam for such alignment permits a fine alignment.

Apparatus and methods for mask/substrate alignment in charged-particle-beam pattern-transfer

Reticles and apparatus for performing charged-particle-beam microlithography, and associated methods, are disclosed, in which the pattern to be transferred to a sensitive substrate is divided according to any of various schemes serving to improve throughput and pattern-transfer accuracy. The methods and apparatus are especially useful whenever a divided stencil reticle is used that includes complementary pattern portions.

Divided reticles for charged-particle-beam microlithography apparatus, and methods for using same

For use in association with microlithography systems, reticle chambers and reticle cassettes are disclosed that provide ready access to and exchange of reticles for exposure as well as temperature control of the reticles. In an embodiment a vacuum reticle library is provided in a reticle-storage chamber. The vacuum reticle library includes a rack comprising multiple shelves for holding respective reticles at different respective elevations. One or more shelves comprises a fluid conduit through which is circulated a temperature-controlled fluid. By adjusting and controlling the temperature of the fluid (e.g., water) circulated to each shelf, the temperature of the respective reticles held on the shelves can be controlled and adjusted quickly. Similarly, an atmospheric-pressure reticle library can be provided in an atmospheric-pressure chamber containing a rack of multiple shelves on which respective reticle cassettes (containing reticles) can be stored. The cassettes and reticles can be identified by a bar code or the like that is read to avoid mixups during reticle transport and exchange.

Reticle chambers and reticle cassettes providing temperature control and ready exchange of reticles for exposure

Methods and devices are provided that achieve accurate detection of the positions of alignment marks on wafer substrates and other specimens as used in charged-particle-beam (CPB) microlithography. A charged particle beam (e.g., electron beam) is irradiated onto an area, of a specimen, lacking an alignment mark to obtain a first backscattered-particle signal regarded as 'background.' The beam is irradiated onto an area, of the specimen, where an alignment mark is present to obtain a second backscattered-particle signal. The difference of the first signal from the second signal is determined to produce a difference signal containing data concerning only aspects of the alignment mark and not of the background. The methods are especially useful whenever the specimen has crystalline properties that otherwise could affect the backscattered-particle signal.

Alignment-mark detection methods and devices for charged-particle-beam microlithography, and microelectronic-device manufacturing methods comprising same

Microlithography methods and apparatus are disclosed that allow reticle deformations to be measured and corrected quickly and accurately. Multiple alignment marks (comprising a &ldquo;first set&rdquo; and &ldquo;second set&rdquo; of reticle-position-measurement marks) are formed on the reticle. A first set of reticle-deformation data is obtained by detecting the positions of at least some of the first set of reticle-position-measurement marks using an inspection device that is separate from the microlithography apparatus with which the reticle will be used for making lithographic exposures. The first set of reticle-deformation data is stored in a first memory. The reticle then is mounted in the microlithography apparatus, in which a second set of reticle-deformation data is obtained by detecting the positions of at least some of the second set of reticle-position-measurement marks. The second set of reticle-deformation data is stored in a second memory. Lithographic exposures are performed, using the reticle so measured, while correcting the respective positions and/or deformations of the respective subfields on the fly, according to both sets of reticle-deformation data recalled from the respective memories.

Methods and apparatus for detecting and correcting reticle deformations in microlithography

Alignment-mark patterns are disclosed that are defined on stencil reticles and that can be transferred lithographically from the reticle to a sensitized substrate using charged-particle-beam microlithography. The corresponding alignment marks as transferred to the substrate are detectable at high accuracy using an optical-based alignment-detection device (e.g., an FIA-based device). The transferred alignment marks can be used in place of alignment marks used in optical microlithography systems. An alignment-mark pattern as defined on a stencil reticle includes pattern elements that are split in any of various ways into respective pattern-element portions separated from each other on the membrane of the stencil reticle by &ldquo;girders&rdquo; (band-like membrane portions) that prevent the formation of islands in the stencil reticle and that prevent deformation of the pattern elements on the stencil reticle.

Alignment-mark patterns defined on a stencil reticle and detectable, after lithographic transfer to a substrate, using an optical-based detector

Charged-particle-beam (CPB) apparatus and methods are disclosed that achieve efficient correction of imaging conditions such as shape-astigmatic aberrations, etc., caused by differences in the distribution of pattern elements within respective subfields of the reticle. Indices based on the pattern-element distributions within subfields are stored, together with corresponding optical-correction data for the subfields. As the subfields are exposed, respective data are recalled and the exposure is performed with optical corrections made according to the data. The indices are determined beforehand from pattern data at time of reticle manufacture. The tabulated data are rewritable with changes in apparatus parameters such as beam-current density and beam-divergence angle. Intermediate data can be determined by interpolation of tabulated data.

Charged-particle-beam microlithography apparatus and methods including optical corrections made during subfield exposures

Fiducial mark bodies are provided for use in CPB microlithography apparatus and methods. Such bodies are especially useful for attachment to the wafer stage of such apparatus, for measuring a distance between a reference position of the CPB-optical system of the apparatus and a reference position of an optical-based alignment sensor of the apparatus. The mark bodies provide improved accuracy of these and other positional measurements. A typical mark body is made of a substrate plate (e.g., quartz or quartz-ceramic) having a low coefficient of thermal expansion. Mark elements are defined on the substrate plate by a layer of heavy metal (e.g. are Ta, W, or Pt). The mark body includes a surficial or interior layer of an electrically conductive light metal that prevents electrostatic charging of the mark body and can be connected to ground.

Fiducial mark bodies for charged-particle-beam (CPB) microlithography, methods for making same, and CPB microlithography apparatus comprising same

A charged-particle-beam exposure apparatus for exposing mask patterns onto a substrate includes a mask illumination system capable of varying the size and/or shape of the beam cross-section (the irradiated or mask-illumination field) at the mask. Initial mask alignment (rough alignment) and calibration are performed by irradiating respective alignment and calibration marks on the mask with a beam having a cross-sectional size smaller than the cross-sectional size of a beam used in the normal exposure process.

Charged-particle-beam mask-based exposure apparatus employing a variable mask-illumination field and alignment and calibration methods therefor

Charged-particle-beam (CPB) microlithography methods are disclosed in which exposure dose on the lithographic substrate is controlled and adjusted as required to achieve proper exposure and maximal throughput, regardless of beam-transmissivity (e.g., membrane thickness) of the reticle in use. A reticle is provided with a transmitted-current-detection window exhibiting the same beam-transmissivity and forward-scattering behavior as a non-scattering membrane portion of the pattern-defining portion of the reticle. A charged-particle illumination beam is directed at the transmitted-current-detection window of the reticle. The beam current passing through the transmitted-current-detection window and reaching the wafer stage is sensed by a sensor located at or on the wafer stage. From the obtained beam-current data, a controller calculates the beam-current density on the wafer stage and calculates and sets a corresponding exposure time for exposing the wafer with an appropriate amount of exposure energy. Lithographic exposure is performed according to the set exposure time.

Growing community of inventors

Tokyo, Japan

Noriyuki Hirayanagi