Abstract: 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.

Abstract: Apparatus and methods are disclosed pertaining to microlithography performed using a charged particle beam. In an exemplary apparatus, the projection-optical system includes a first projection lens situated downstream of a pattern-defining reticle and a second projection lens situated downstream of the first projection lens. Between the first and second projection lenses is a back focal plane of the first projection lens, at which focal plane a beam crossover is formed. The projection-optical system includes a cutoff-plate assembly, including at least one aperture-defining cutoff plate, located between the reticle and the back focal plane. The respective aperture in each cutoff plate is wider than an aperture in a scattering aperture conventionally located at the back focal plane. If the cutoff-plate assembly includes multiple cutoff plates, the aperture defined in the cutoff plate closer to the reticle is wider than the aperture defined in the more downstream cutoff plate.

Abstract: Methods are disclosed for correcting proximity effects as affected by varying magnitudes of beam blur occurring at different respective locations in an image of a reticle subfield as projected onto the sensitive surface of a substrate. Local resizings of pattern-element profiles as defined on the reticle are made taking into consideration not only proximity effects arising from Coulomb interactions but also different magnitudes of beam blur occurring at different respective locations in a projected subfield. Beam blur is imparted by the projection-optical system and is a function of the magnitude of beam deflection, the location of pattern element(s) within the area of the exposed subfield, and the exposure-energy profile on the surface of the substrate being exposed. A resist-development energy threshold is established such that the edges of pattern elements as transferred to the wafer in response to the exposure-energy profile will be at their desired locations according to design specifications.

Abstract: Microlithography reticles are disclosed that include a high-contrast reticle-identification code (bar code). The bar code is configured as a pattern (usually linearly arrayed) of high-scattering regions (bar-code elements) each exhibiting a relatively high degree of reflection-scattering of irradiated probe light. The high-scattering regions are separated from one another by respective low-scattering regions each exhibiting a relatively low degree of reflection-scattering of incident probe light. For example, the low-scattering regions have smooth surfaces from which very little probe light is reflection-scattered, wherein each high-scattering region includes multiple scattering features such as line, channels, projections, or the like that provide multiple edges and/or points that reflection-scatter probe light.

Abstract: Methods and apparatus are disclosed for performing charged-particle-beam (CPB) microlithography, in which methods and apparatus certain position-measurement marks are detected by appropriate deflections of a charged particle beam. The deflections are performed using a primary deflector and a mark-scanning deflector. For example, the beam is deflected by the primary deflector to illuminate a position-measurement mark on the reticle and a corresponding position-measurement mark on the substrate. The position-measurement mark on the substrate is scanned by minute deflections of the beam as performed by the mark-scanning deflector. Meanwhile, charged particles backscattered from the position-measurement mark on the substrate (as the mark is being scanned) are captured and detected by a detector. The marks are detected at timing moments during normal operation of the primary deflector.

Abstract: In the context of charged-particle-beam (CPB) microlithography methods and systems, methods are disclosed for detecting the incidence orthogonality of a patterned beam on the lithographic substrate. In an embodiment, the position of reticle-fiducial-mark images, as formed on the substrate stage at a position Z1, are detected at two lateral positions of a corresponding reticle fiducial mark. A distance L1 between the images is determined. Then, the substrate stage is moved to a position Z2, at which the position of reticle-fiducial-mark images are detected at two lateral positions of the corresponding reticle fiducial mark. A distance L2 between the images is determined. The incidence-orthogonality error &Dgr;&thgr; is calculated by substitution into &Dgr;&thgr;=(L1−L2)/2&Dgr;H. The projection-optical system of the CPB microlithography apparatus is adjusted so that &Dgr;&thgr;=0.

Abstract: 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.

Abstract: In the context of charged-particle-beam (CPB) microlithography methods and systems, methods are disclosed for detecting the incidence orthogonality of a patterned beam on the lithographic substrate. In an embodiment, the position of reticle-fiducial-mark images, as formed on the substrate stage at a position Z1, are detected at two lateral positions of a corresponding reticle fiducial mark. A distance L1 between the images is determined. Then, the substrate stage is moved to a position Z2, at which the position of reticle-fiducial-mark images are detected at two lateral positions of the corresponding reticle fiducial mark. A distance L2 between the images is determined. The incidence-orthogonality error &Dgr;&thgr; is calculated by substitution into &Dgr;&thgr;=(L1−L2)/2&Dgr;H. The projection-optical system of the CPB microlithography apparatus is adjusted so that &Dgr;&thgr;=0.

Abstract: Methods and apparatus are provided for performing charged-particle-beam microlithography at improved accuracy. A pattern is formed on a substrate (wafer) by repeated shot exposure of respective areas on a wafer substrate mounted on a wafer stage. Exposure of the wafer is made while the wafer stage is undergoing continuous motion and the charged particle beam making the exposure is being deflected continuously. As the magnitude of the beam deflection changes according to the motion of the stage, correction data for deflecting the beam are updated appropriately so as to correct deflection aberrations continuously.

Abstract: Methods and apparatus are disclosed for performing charged-particle-beam (CPB) microlithography, in which methods and apparatus certain position-measurement marks are detected by appropriate deflections of a charged particle beam. The deflections are performed using a primary deflector and a mark-scanning deflector. For example, the beam is deflected by the primary deflector to illuminate a position-measurement mark on the reticle and a corresponding position-measurement mark on the substrate. The position-measurement mark on the substrate is scanned by minute deflections of the beam as performed by the mark-scanning deflector. Meanwhile, charged particles backscattered from the position-measurement mark on the substrate (as the mark is being scanned) are captured and detected by a detector. The marks are detected at timing moments during normal operation of the primary deflector.

Abstract: Methods are disclosed for reducing effects of thermal expansion of a sensitive substrate arising during microlithographic exposure of the substrate using a charged particle beam. Thermal expansion ordinarily causes lateral shift of exposure position of dies (chips) on the substrate which tends to reduce the positional accuracy with which images of the dies are formed on the substrate. Generally, regions of the substrate where entire dies are formed are exposed first, followed by regions (especially peripheral regions) exposed with only portions of dies. In addition, the substrate can be mounted on a wafer chuck configured to circulate a heat-transfer gas in contact with the substrate to remove heat from the substrate. In addition, the wafer chuck can be maintained at a constant temperature by circulating a liquid coolant through a conduit in the body of the wafer chuck.

Abstract: Apparatus and methods are disclosed pertaining to microlithography performed using a charged particle beam. In an exemplary apparatus, the projection-optical system includes a first projection lens situated downstream of a pattern-defining reticle and a second projection lens situated downstream of the first projection lens. Between the first and second projection lenses is a back focal plane of the first projection lens, at which focal plane a beam crossover is formed. The projection-optical system includes a cutoff-plate assembly, including at least one aperture-defining cutoff plate, located between the reticle and the back focal plane. The respective aperture in each cutoff plate is wider than an aperture in a scattering aperture conventionally located at the back focal plane. If the cutoff-plate assembly includes multiple cutoff plates, the aperture defined in the cutoff plate closer to the reticle is wider than the aperture defined in the more downstream cutoff plate.

Abstract: Charged-particle-beam microlithography apparatus and methods are disclosed that achieve correction of positioning errors of one or both the reticle stage and wafer stage using a deflector. The deflector is situated in one or both lenses of the projection-optical system of the apparatus. The deflector preferably is electrostatic for rapid responsiveness, and desirably is configured also to correct distortions corresponding to the positioning errors.

Abstract: Charged-particle-beam (CPB) microlithography methods and apparatus are disclosed that suppress increases in reticle temperature caused by CPB irradiation during exposure. The methods and apparatus employ a reticle segmented into subfields or analogous exposure units arranged into minor stripes and at least one major stripe. At least some of the minor stripes comprise a region in which the constituent minor stripes are illuminated multiple times to achieve transfer of the respective pattern portions to a corresponding region on the substrate. Each time a constituent minor stripe is illuminated, the beam energy is reduced, thereby reducing reticle heating. After a subfield in the region has been transferred multiple times to a corresponding transfer subfield on the substrate, the net exposure energy received by the transfer subfield is the same as if the transfer subfield had been exposed only once at a correspondingly higher dose.

Abstract: Methods are disclosed for producing reticles for use in charged-particle-beam microlithography. In an exemplary method, a pattern to be formed on a sensitive substrate is designed. For at least certain of the pattern elements, local resizing is determined as appropriate for correcting proximity effects. Corresponding “initial value” reticle-pattern data is then produced. During drawing of the reticle pattern on a reticle substrate using an electron beam, the beam dose is varied so as to change linewidths of the pattern elements from their respective initial value data. Drawn linewidths also can be changed for pattern elements during drawing. The reticle that is produced exhibits better correction of proximity effects when the pattern is transferred to the sensitive substrate.

Abstract: Methods and apparatus are disclosed for reducing thermal deformation of “upstream” marks (as used for alignment and/or calibration) situated on a reticle or on a reticle plane (e.g., on the reticle stage), thereby facilitating more accurate transfer of the reticle pattern to a sensitized substrate (e.g., semiconductor wafer) using a charged particle beam (e.g., electron beam). The charged particle beam illuminates an upstream mark situated on the reticle or on a reticle plane and projects an image of the illuminated upstream mark onto a corresponding “downstream” mark situated on a substrate plane. A shield is situated upstream of the upstream mark and serves to block downstream passage of the charged particle beam except to illuminate the upstream mark or a portion of the upstream mark. The upstream mark can be situated on the reticle or on a mark member situated in the reticle plane.

Abstract: Methods are disclosed for correcting proximity effects as affected by varying magnitudes of beam blur occurring at different respective locations in an image of a reticle subfield as projected onto the sensitive surface of a substrate. Local resizings of pattern-element profiles as defined on the reticle are made taking into consideration not only proximity effects arising from Coulomb interactions but also different magnitudes of beam blur occurring at different respective locations in a projected subfield. Beam blur is imparted by the projection-optical system and is a function of the magnitude of beam deflection, the location of pattern element(s) within the area of the exposed subfield, and the exposure-energy profile on the surface of the substrate being exposed. A resist-development energy threshold is established such that the edges of pattern elements as transferred to the wafer in response to the exposure-energy profile will be at their desired locations according to design specifications.

Abstract: 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.

Abstract: Methods and apparatus are disclosed for reducing thermal deformation of “upstream” marks (as used for alignment and/or calibration) situated on a reticle or on a reticle plane (e.g., on the reticle stage), thereby facilitating more accurate transfer of the reticle pattern to a sensitized substrate (e.g., semiconductor wafer) using a charged particle beam (e.g., electron beam). The charged particle beam illuminates an upstream mark situated on the reticle or on a reticle plane and projects an image of the illuminated upstream mark onto a corresponding “downstream” mark situated on a substrate plane. A shield is situated upstream of the upstream mark and serves to block downstream passage of the charged particle beam except to illuminate the upstream mark or a portion of the upstream mark. The upstream mark can be situated on the reticle or on a mark member situated in the reticle plane.

Abstract: 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.