WO2002103285A1 - Interferometer system - Google Patents
Interferometer system Download PDFInfo
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- WO2002103285A1 WO2002103285A1 PCT/US2002/018983 US0218983W WO02103285A1 WO 2002103285 A1 WO2002103285 A1 WO 2002103285A1 US 0218983 W US0218983 W US 0218983W WO 02103285 A1 WO02103285 A1 WO 02103285A1
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- WO
- WIPO (PCT)
- Prior art keywords
- reflective surface
- axis
- measure
- tilt
- distance
- Prior art date
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Classifications
-
- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
- G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
- G03F7/70—Microphotolithographic exposure; Apparatus therefor
- G03F7/70691—Handling of masks or workpieces
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B11/00—Measuring arrangements characterised by the use of optical techniques
- G01B11/002—Measuring arrangements characterised by the use of optical techniques for measuring two or more coordinates
Definitions
- the invention relates generally to an interferometer system for position measurement and more specifically to an interferometer system and method for improving the accuracy of interferometric measurements.
- a laser interferometer is often used to accurately measure relative displacement between two members in a projection exposure system used to manufacture semiconductor devices.
- the laser interferometer is used as a measuring apparatus for measuring the coordinates of a wafer stage or mask stage for highly accurate positioning of a semiconductor wafer or reticle relative to stationary projection optics.
- a prior art laser interferometer system is shown in Figs. 1 and 2. The interferometer system typically measures a change in position in measurement mirrors
- Beam 3 is the portion of each beam B that is reflected by the beam splitter and directed toward respective reference mirrors IX and 1 Y.
- the beams 3 reflect off the reference mirrors IX and 1 Y and pass through the beam splitters to give beams C.
- Beam 4 is the portion of each beam B that passes through the beam splitters and is directed toward respective measurement mirrors 2X and 2Y, and is then reflected by the measurement mirrors back to the respective beam splitters.
- the reflected beams 4 are reflected by the respective beam splitters where they are combined with reflected beams 3 into the combined beams C.
- the combined beams C are then directed into respective sensors SX and S Y, where they are analyzed to compare the distances represented by beams 3 and 4. If the measurement mirror 2X moves relative to the reference mirror IX, the intensity of the combined beam periodically increases and decreases as the reflected light from the two paths alternately interferes constructively and destructively. This constructive and destructive interference is caused by the two beams moving in and out of phase. Each half wavelength of movement of the measurement mirror results in a total optical path change of one wavelength and thus, one complete cycle of intensity change. The number of cycle changes indicates the number of wavelengths that the measurement mirror has moved. Therefore, by counting the number of times the intensity of the light cycles between darkest and lightest, the change in position of the measurement mirror can be estimated as an integral number of wavelengths.
- the 2Y mirror surface should not change its position along the y axis during x axis movements of the stage, and the beams 3 and 4 should stay perfectly in phase as received by the sensor SY.
- the mirror 2Y is never perfectly planar (of course the same holds true for mirror 2X).
- these mirrors generally have a polishing error of ⁇ /10 or more which equates, for present semiconductor uses, to up to 60 nm deformations measured from the theoretical plane of the mirror surface.
- U.S. Patent No. 5,790,253 to Kamiya describes an interferometer system for correcting linearity errors of a moving mirror and stage.
- Kamiya can correct for the deformation in the mirror along the long axis of the mirror, which is referred to in the art as correcting "mirror bow".
- Kamiya measures the curvature data of the moving mirror prior to its installation on the stage and stores the data as mapping data.
- Kamiya takes discrete curving error measurement along the length of the mirror after it has been mounted on the stage.
- a main controller creates continuous curvature error data after installation of the mirror on the wafer based on the relationship between the data generated before and after mounting the mirror on the stage. The continuous curvature error data is then used as correction data for more accurately placing the stage.
- U.S. Patent No. 5,363,196 to Cameron also describes an interferometer system for correcting mirror bow of a moving mirror mounted to a stage.
- Cameron provides two interferometer laser metering devices, either one of which is capable of providing measurement data of the angle of rotation of the stage in the x-y plane, for use by computer controlled servo devices that control the x-y movement of the stage.
- the servo devices may receive data of specific measurements defining the respective values of undesired departures from flatness or straightness of the moving mirror surfaces that are mounted to the stage.
- the departure data is stored in memory, and may be used by the computer controlled servo devices to compensate for the undesired departures in linearity of the mirrors, during the actual movement and processing phases of the stage.
- Cameron also discloses that, if desired, an additional interferometer may be provided along each of the x and y axes to measure twist in the moving mirrors. However, because of the long, narrow aspect ration of both of the moving mirrors, Cameron indicates that determination of twist may not be worth pursuing.
- Sueyoshi in Japanese HEI9-210648, discloses a method and device for measuring a plane shape at a desired pitch by detecting positional information on the plane along three specified points that are separated by predetermined distances. For example, three x direction interferometers are aligned in the y direction and spaced at predetermined distances along the y direction. A similar arrangement is provide for y direction interferometers. These arrangements are then used to take measurements for a determination of mirror bowing in the x and y reflective mirrors, respectively. As manufacturers of integrated circuits attempt to increase circuit density and reduce circuit feature size, interferometers are required to provide more precise measurement data.
- the tolerance for error in alignment of the stage system decreases, so that a shift of the reflection point caused by deformation of a mirror in the x-z or y-z plane also becomes more significant. Additionally, if the stage tilts, a lateral shift of the reflection point occurs which will not be detected by a system for correction of mirror bowing. The result is an error in the position measurement of the stage that results in misalignment of circuit patterns on the wafer (mounted on the stage) relative to one another.
- the invention provides a measuring system that measures and corrects for deformation and tilt of substantially planar surfaces with respect to a vertical axis.
- the measurement system generally includes first, second, third and fourth sensors, each capable of generating data indicative of a distance between the sensors, respectively, and corresponding locations on a reflective surface of the reflective object.
- a controller is provided for receiving inputs from the first, second, third and fourth sensors and determining a tilt of the reflective surface with respect to a z axis.
- a support on which the reflective object is mounted has a generally planar surface that is generally perpendicular to the z axis but which may tilt with respect thereto.
- the reflective object is mounted to the support so that said reflective surface is in a plane substantially parallel with the z axis and longitudinally extends substantially parallel to an axis normal to the z axis.
- the first and second sensors are aligned substantially parallel to the axis normal to the z axis along which the reflective surface extends longitudinally and are separated by a distance a.
- the third and fourth sensors are aligned substantially parallel to the axis normal to the z axis along which the reflective surface extends longitudinally and are separated by the distance a.
- the first and third sensors are aligned substantially parallel to the z axis and are separated by the distance a
- the second and fourth sensors are aligned substantially parallel to the z axis and are separated by the distance a.
- the controller determines a tilt of the reflective surface at a location ka along the longitudinally extending direction of the reflective surface according to the following formula:
- ⁇ (ka) ⁇ ((k+l)a)- ⁇ (ka)
- ⁇ (ka) is a measure of a displacement of the reflective surface out of the plane substantially parallel with the z axis, at location ka; (ka) is a measure of tilt of the reflective surface measured by the second and fourth sensors; and
- ⁇ ((k+l)a) is a measure of tilt of the reflective surface measured by the first and third sensors.
- the first, second, third and fourth sensors comprise first, second, third and fourth measuring laser beams LI, L2, L3 and L4 that are emitted from an interferometric measurement system.
- the beams LI and L2 are aligned along an imaginary line parallel to the y axis, and the beams L3 and L4 are aligned along another imaginary line parallel to the y axis and separated from the imaginary line joining LI and
- a reflective surface or mirror can be located at position ka along the y axis with respect to the system, and can alternately be located at position ka + a along the y axis with respect to the system.
- LI (ka) s(ka+a) + ⁇ (ka) - (a/2)0(ka) (6)
- L3(ka) t(ka+a) + ⁇ (ka) - (a/2)0(ka) (7)
- Jl is defined as the difference between equations (5) and (4)
- J2 is defined as the difference between equations (7) and (6) as follows:
- the mirror is incrementally moved with respect to the sensors, preferably by at least one motor, to continue measuring displacement of the mirror out of the intended plane with respect to the z axis.
- the measurements are performed at each incremental location.
- This process is repeatedly performed while incrementally moving the mirror in the y axis direction by a distance a for each iteration.
- the mirror tilt can readily be determined at any of the incremental positions along the mirror by a simple summation of the differential tilt values obtained from an initial end of the mirror, where the first tilt measurement was made, sequentially up to the actual location on the mirror where It is ⁇ desire ⁇ " t6 ⁇ determinelthe mirror " tilt.
- ⁇ ((k-l)a) ⁇ (ka) - ⁇ ((k-l)a)
- ⁇ ((k-2)a) ⁇ ((k-l)a) - ⁇ ((k-2)a)
- ⁇ (0) ⁇ (a) - ⁇ (0)
- tilt measurement values are differential values defined with respect to the previously measured value
- a tilt value for a given location can be determined by summing the sequence of values preceding and including that location.
- the mirror tilt of the mirror at position ka can be readily determined using equation (12). This value is then added, by the controller, to the interferometer position measurement value that is inputted to the controller, to more accurately position the stage by including the lateral offset due to the mirror tilt.
- the measurement system preferably includes a second reflective surface and a second set of four sensors, preferably four measuring laser beams incorporated into an interferometric measurement system that measures the second substantially planar reflective surface that is oriented orthogonally to the first reflective surface. Measurements from the second set of sensors are also inputted to the controller for a determination of tilt of the second reflective surface. The determination is made according to the same procedure used to determine tilt of the first reflective surface.
- the invention also provides a method of measuring the tilt of a substantially planar surface that includes (1) providing a measurement system having the capability of measuring distances between first, second, third and fourth adjacent locations on the substantially planar surface and respective first, second, third and fourth adjacent locations on the measurement system, where the distances measured are along imaginary lines substantially perpendicular to the substantially planar surface; (2) positioning the substantially planar surfaces such that the measurement system is near an end of the substantially planar surface; (3) measuring distances between the pairs of first, second, third and fourth locations; (4) subtracting the distance between the second locations from the distance between the fourth locations and dividing the difference by a distance between the second and fourth locations on the substantially planar surface to give a term Jl; (5) subtracting the distance between the first locations from the distance between the third locations and dividin g the difference- bv the distance between the- first and third locations on the substantially planar surface to give a term J2; and (6) determining a tilt of the substantially planar surface at the location of the substantially planar surface according to the following formula:
- ⁇ (ka) is a measure of a displacement out of the substantially planar surface
- ⁇ (ka) is a measure of tilt of the substantially planar surface with respect to the vertical axis measured between the second and fourth locations;
- ⁇ ((k+l)a) is a measure of tilt of the substantially planar surface with respect to the vertical axis measured between the first and third locations; and a is a distance between the first and second locations on the substantially planar surface.
- ⁇ (ka+a) is a measure of a displacement out of the substantially planar surface
- ⁇ ((k+l)a) is a measure of tilt of the substantially planar surface with respect to the vertical axis measured between the second and fourth locations on the measurement system and the new locations on the substantially planar surface;
- ⁇ ((k+2)a) is a measure of tilt of the substantially planar surface with respect to the vertical axis measured between the first and third locations on the measurement system and the new locations on the substantially planar surface.
- Incremental measurements are continued by incrementally repeating the previously described incremental procedure, until an opposite end of the substantially planar surface is reached and no further incremental measurements can be taken, or until a predetermined length of the substantially planar surface has been measured.
- a determination of the tilt of the substantially planar surface with respect to the vertical axis for any predetermined position ka can be determined according to the following formula:
- ⁇ (ka) is a measure of tilt of the substantially planar surface with respect to the vertical axis at position ka;
- FIG. 1 is a plan view of a prior art interferometer system for measuring position of a stage movable in x and y directions;
- Fig. 2 is a partial view of the prior art interferometer system of Fig. 1 showing an exaggerated view of mirror bowing, or deformation in the x-y plane;
- Fig. 3 is a side view of an interferometer system where a moving mirror is perfectly parallel to the z axis.
- Fig. 4 is a side view of an interferometer system where a moving mirror tilts at an angle ⁇ with respect to the z axis.
- Fig. 5 is a schematic showing changes in optical path lengths of light beams due to combined effect of mirror tilt and stage tilt;
- Fig. 6 is a perspective view of an interferometer system of the invention applied to a wafer stage of a projection type exposure apparatus;
- Fig. 7 is a schematic showing the pattern of measurement beams resultant from a preferred layout of interferometers used to measure mirror deformation in the x-z plane;
- Fig. 8 is a schematic showing a structure that enables a stage of an interferometer system to be incrementally moved.
- An interferometer such as one used in the prior art system 10 shown in Figs. 1-2, is used to accurately measure the displacement of a measurement target (e.g., stage S) by using interference between light waves that have propagated along a measurement optical path 4 and a reference optical path 3.
- the interferometer may be used as a position measurement system of a stage apparatus such as a wafer stage or a mask stage in a one- shot or scan type exposure apparatus for which highly precise driving control is required.
- the interferometer is not limited to use with an exposure apparatus.
- the interferometer may be used to accurately measure the relative displacement between two members in various high precision tools, for example.
- a measurement mirror (reflector) 2X is attached to the stage S and movable therewith to provide measurement of the measurement optical path 4, and a reference mirror (reflector) IX is attached to a lens or other stationary portion of the exposure apparatus to provide the reference optical path 3.
- the measurement mirror 2X is attached to the stage S parallel to the y direction and measurement mirror 2Y is attached to the stage S parallel to the x direction (Fig. 1).
- the measurement mirror 2X is used to measure displacement of the stage along the x axis while the measurement mirror 2Y is used to measure displacement of the stage along the y axis.
- a measurement mirror in this case measurement mirror 2X, is never perfectly planar but will have a certain amount of
- the interferometer system shown in Figs. 1 and 2 cannot detect deviations of the measurement mirror 2X where the surface of the measurement mirror 2X deviates from the ideal surface that is parallel to the z axis. It is known that a measurement mirror, in this case measurement mirror 2X, is never perfectly parallel to the z axis, but will have a certain amount of "tilt" with respect to the z axis.
- Fig. 3 shows the case where the moving mirror is perfectly parallel to the z axis.
- Fig. 4 shows the case where the moving mirror tilts at an angle ⁇ with respect to the z axis.
- the interferometer systems of the invention measure displacement due to mirror tilt and stage tilt, as well as displacement due to mirror bowing.
- measurement beams In order to measure tilt, measurement beams must be displaced with regard to one another along the z axis, as shown in Fig. 4 by the placement of measurement beams LI and L3.
- Fig. 4 is a partial schematic view of an interferometer system 20 according to the invention. As can be seen in Fig. 4, beams LI and L3 are displaced with regard to one another along the z axis, while being aligned with regard to the y axis. Thus, any differences in the measurement lengths of beams LI and L3 will indicate tilt with respect to the z axis and will not reflect bowing deviations.
- the tilt of the surface of measurement mirror 26x with regard to the ideal 26X1 by the angle ⁇ results in a difference between the lengths of measurement beams LI and L3 that when analyzed can give the degree of tilt between the two measuring points contacted by measurement beams LI and L3, respectively.
- z the z coordinate of the location on the measurement mirror 26X on which the measurement beam is incident:
- ⁇ the mirror tilt with respect to the z axis, as described above:
- x the x coordinate of the location on the measurement mirror 26X on which the measurement beam is incident;
- L the distance between the center of tilt (i.e., the central axis of the illumination lens, or the optical axis of the projection lens) and the location on the measurement mirror 26X on which the measurement beam is incident, measured parallel to the x axis.
- the mirror surface becomes laterally shifted in the x axis direction by an amount in addition to the mirror tilt, due to the tilting angle ⁇ of the stage 36 about the z axis.
- the additional lateral displacement is indicated by ⁇ x in Fig. 5 and is measured by the displacement between the x coordinate of the mirror surface when stage tilt is zero (as indicated by a phantom line in Fig. 5) and the x coordinate of the mirror surface as effected by both the mirror tilt and the stage tilt (as shown by the solid line).
- the coordinates of a point on the reflecting surface of mirror 26X upon which a measurement beam is incident, in a situation as shown in Fig. 5, are given by the equation (2):
- the second term in the equation (3) takes into account the mirror tilt ⁇ and the first term is only affected by stage tilt 0.
- the component effected by mirror tilt ⁇ i.e., L ⁇ 8 alters the term ⁇ x by about 1.5 nm.
- the interferometer measurement will have a 1.5 nm measurement error. Although in the past this error has been ignored because it is much smaller than the error values due to mirror bowing, the density of integrated circuit patterns have become such that the tilt error can no longer be ignored.
- Fig. 6 shows a preferred arrangement of an interferometer system 20 according to the invention applied to a wafer stage 36 of a projection type exposure apparatus 100. The apparatus is described in further detail below.
- Fig. 7 shows the relative positioning of measurement beams LI, L2, L3 and L4 emitted from interferometer system 30X that has the ability to measure mirror tilt of the measurement mirror 26X with respect to the z axis.
- Fig. 7 shows the relational positions of beams LI, L2, L3 and L4 in solid lines when the mirror 26X is located at position ka along the y axis with respect to the interferometer system 30X, and the relational positions of beams LI, L2, L3 and L4 in phantom lines when the mirror 26X is located at position ka + a along the y axis with respect to the interferometer system.
- the beams LI and L2 are aligned along an imaginary line parallel to the y axis
- the beams L3 and L4 are aligned along another imaginary line parallel to the y axis and separated from the imaginary line joining Ll and L2 by a distance a.
- the beams L2 and L4 are aligned along an imaginary line parallel to the z axis, and the beams Ll and L3 are aligned along another imaginary line parallel to the z axis and separated from the imaginary line joining L2 and L4 by a distance a.
- the distances between Ll and L2, Ll and L3, L2 and L4, and L3 and L4 are all equal to a.
- Jl is defined as the difference between equations (5) and (4)
- J2 is defined as the difference between equations (7) and (6) as follows:
- L2(ka+a) s(ka+a) + ⁇ (ka+a) - (a/2)0(ka+a) (4')
- L4fka+a tH a+a + ⁇ fka+a ⁇ + fa/2 ka+a (5 ')
- Jl and J2 are defined according to the equations
- This process is repeatedly performed while incrementally moving the mirror 26X in the y axis direction by a distance a for each iteration.
- the mirror tilt can readily be determined at any of the incremental positions along the mirror 26X by a simple summation of the differential tilt values obtained from an initial end of the mirror 26X, where the first tilt measurement was made, sequentially up to the actual location on the mirror 26X where it is desired to determine the mirror tilt.
- ⁇ (0) ⁇ (a) - ⁇ (0) Since the tilt measurement values are differential values embedded in the previously measured value, a tilt value for a given location can be determined by summing the sequence of values preceding and including that location. A summation of the general equations given above gives:
- the mirror tilt of the mirror 26X can be readily determined using equation (12). If we assume that the initial measurement location along mirror 26X is a location very near the intersection of the mirrors 26X and 26Y shown in Fig. 6, then the incremental measurements will be made moving toward the opposite end of the mirror 26X along the y axis, as schematically illustrated by Fig. 7 which shows a one step increment. It is not possible to directly measure the tilt at the very ends of the mirror, due to the lateral displacement of the beams Ll and L3 from L2 and L4, and because all of the beams Ll - L4 are used to measure a tilt value, as described above. If a mirror area L is used for exposure, a mirror length of L+2a can be used to measure mirror tilt.
- the tilt of the mirror 26X at position ka can be determined by sununing all of the incremental differential values of ⁇ and adding them to the initial measurement, as described above in equation (12). This value is then added, by the controller 40, to the interferometer position measurement value that is inputted to the controller 40, to more accurately position the stage 36 by including the lateral offset due to the mirror tilt. It is noted that although only incremental values for the mirror tilt are measured and stored, it is possible to interpolate, using algorithms known in the art (such as a Spline interpolation algorithm), between values to determine a value of a final increment for a position of the stage that is not located directly at one of the incremental measurement positions.
- algorithms known in the art such as a Spline interpolation algorithm
- a mirror length of L+2a can be used to measure mirror tilt.
- determination of the tilt measurements of the mirror 26Y can be determined, and inputted to the controller 40.
- the tilt measurement value is added by the controller 40 to the interferometer position measurement value of the y position of the stage, which is inputted to the controller 40 from interferometer system 30Y, to more accurately position the stage 36 by including the lateral offset in the y direction due to the mirror tilt (i.e., the component of ⁇ y effected by mirror tilt in the y-z plane).
- interferometer systems 30X and 30Y have the capability of correcting for mirror bowing, and providing control measurements to control yawing, according to techniques known in the art.
- Beams Ll, L2, L3 and L4 in each of interferometer systems 30X and 30Y may be formed using a single laser with appropriate optical components to form the four beams, as would be readily apparent to one of ordinary skill in the art, or may comprise four aligned sources to form the four beams, or two beams with appropriate optical components, or other combinations that would be apparent to those of ordinary skill in the art.
- Preferably a single laser source is used in each of interferometer systems 3 OX and 30Y.
- FIG. 6 a schematic illustration of an example of an interferometric measuring system 20 according to the invention is shown applied to an exposure apparatus, the entire apparatus being generally referred to by reference numeral 100.
- the exposure apparatus 100 generally comprises an illumination system 102, the wafer stage 36 for supporting and positioning the wafer 34, a reticle stage (not shown) for supporting and positioning a reticle 104, and motors (not shown) for positioning the wafer stage 36 n tac reticle stage.
- the illumination system 102 projects energy HI the form of, for example, light or an electron beam light through a mask pattern (e.g., circuit pattern for a semiconductor device) formed in the reticle 104 that is supported and scanned using the reticle stage.
- a mask pattern e.g., circuit pattern for a semiconductor device
- the illumination system 102 is part of an optical system that further includes a projection lens 106.
- the 102 preferably has an optical integrator (not shown) for producing secondary light source images and a condenser lens for illuminating the reticle 104 with uniform light flux.
- the projection lens 106 focuses the light or electron beam received through the reticle 104, onto the wafer 34.
- the wafer 34 is positioned under the projection lens 106 and preferably held, for example, by vacuum suction or electrostatic suction on a wafer holder (not shown) that is supported by the wafer stage 36.
- light or electron beams from the illumination system 102 pass through the reticle 104 and expose resist on the wafer 34, which is supported and scanned using the wafer stage 36 driven by the motor.
- the stage 36 is movable in at least two directions along the x and y axes in a plane perpendicular to an optical axis of the exposure apparatus 200, which is defined as the z axis.
- Measurement mirrors 26X and 26Y are provided at two locations around the stage 36.
- the measurement mirror 26Y has its reflecting surface extending along or parallel to the x axis for measuring movement of the stage 36 in the y direction and the measurement mirror 26X has its reflecting surface extending along or parallel to the y axis for measuring movement of the stage in the x direction.
- the interferometer systems 3 OX and 30Y are mounted with respect to the mirrors 26X and 26Y, respectively, so as to illuminate the respective mirrors with a pattern of measuring beams Ll, L2, L3 and L4, as described above.
- each of the interferometer systems 30X and 30Y is provided with a laser head 38X, 38Y that provides the laser illumination for the formation of the measurement beams Ll , L2, L3 and L4.
- the interferometer systems 30X and 30Y input measurement values to the controller 40, which analyzes the inputted measurement data and determines an accurate position of the stage 36, as described above.
- the interferometer systems 30X and 30Y can provide accurate yaw, pitch and roll control, as described above, where pitch is defined here as tilt in the x-z plane and roll is defined as tilt in the y-z plane.
- the interferometer systems incrementally measure the tilt of the mirrors 26X and 26Y, as described above, and these values are stored in the controller to be relied upon, during real time measurement, to more accurately measure lateral offset ⁇ x and ⁇ y, but accounting for the influence of these offset values that is attributed to mirror tilt.
- the interferometer systems may be used to incrementally measure mirror bow, according to methods known in the art, and these values can also be stored by the controller 40 to be combined with real time measurements to more accurately determine the position of the stage.
- Further details of the components of the exposure apparatus 100 may be referenced from U.S. Patent No. 5,528,118 to M. Lee, for example. The entire contents of U.S. Patent No. 5,528,118 are hereby incorporated by reference thereto. It is to be understood that the invention is not limited to the exposure apparatus 100 described herein or to exposure systems for wafer processing. The general reference to the exposure apparatus 100 is purely for illustrating an embodiment in an environment in which the invention may be used.
- the interferometer systems of the invention provide a number of advantages over prior art systems. Importantly, the interferometer systems account for displacement of the measurement mirrors due to a compound effect of mirror tilt and stage tilt, thus providing more accurate stage position measurement than possible with prior art interferometer systems.
Abstract
Description
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Priority Applications (2)
Application Number | Priority Date | Filing Date | Title |
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EP02747900A EP1407220A1 (en) | 2001-06-19 | 2002-06-18 | Interferometer system |
JP2003505558A JP2004530888A (en) | 2001-06-19 | 2002-06-18 | Interferometer system |
Applications Claiming Priority (4)
Application Number | Priority Date | Filing Date | Title |
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US09/883,296 US20030020924A1 (en) | 2001-06-19 | 2001-06-19 | Interferometer system |
US09/883,296 | 2001-06-19 | ||
US09/934,081 US6813022B2 (en) | 2001-06-19 | 2001-08-22 | Interferometer system |
US09/934,081 | 2001-08-22 |
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WO2002103285A1 true WO2002103285A1 (en) | 2002-12-27 |
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PCT/US2002/018983 WO2002103285A1 (en) | 2001-06-19 | 2002-06-18 | Interferometer system |
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EP (1) | EP1407220A1 (en) |
JP (1) | JP2004530888A (en) |
WO (1) | WO2002103285A1 (en) |
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WO2007087301A2 (en) * | 2006-01-23 | 2007-08-02 | Zygo Corporation | Interferometer system for monitoring an object |
Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5801832A (en) * | 1991-02-07 | 1998-09-01 | Asm Lithography | Method of and device for repetitively imaging a mask pattern on a substrate using five measuring axes |
US6285457B2 (en) * | 1998-07-27 | 2001-09-04 | Canon Kabushiki Kaisha | Exposure apparatus and device manufacturing method including measuring position and/or displacement of each of a base and a stage with respect to a support |
-
2002
- 2002-06-18 EP EP02747900A patent/EP1407220A1/en not_active Withdrawn
- 2002-06-18 JP JP2003505558A patent/JP2004530888A/en active Pending
- 2002-06-18 WO PCT/US2002/018983 patent/WO2002103285A1/en active Application Filing
Patent Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5801832A (en) * | 1991-02-07 | 1998-09-01 | Asm Lithography | Method of and device for repetitively imaging a mask pattern on a substrate using five measuring axes |
US6285457B2 (en) * | 1998-07-27 | 2001-09-04 | Canon Kabushiki Kaisha | Exposure apparatus and device manufacturing method including measuring position and/or displacement of each of a base and a stage with respect to a support |
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JP2004530888A (en) | 2004-10-07 |
EP1407220A1 (en) | 2004-04-14 |
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