JP2016024049A - Measurement method and encoder device, as well as exposure method and device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simplify an optical system of a device that measures an amount of relative movement using a diffraction grating.SOLUTION: An encoder 10 measuring an amount of relative movement of a second member 7 relatively movable in an X-direction relative a first member 6 comprises: a reflection type diffraction grating 12 that is provided in the first member 6, and has a grating pattern 12a with the X-direction as a periodical direction; a branching unit 32X that branches light from a laser light source 16 to measurement light MX and reference light RX1 and RX2 different in a polarization state from the measurement light MX; a PBS member 24X that is provided in the second member 7, and makes the measurement light MX incident upon the grating pattern 12a; and a diffraction light deflection member 25X that is provided in the second member 7, and makes diffraction light EX1 and EX2 from the grating pattern 12a by the measurement light MX incident upon the PBS member 24X. The reference light RX1 and RX2 to be incident upon the PBS member 24X and the diffraction light EX1 and EX2 to be incident upon the PBS member 24X from the diffraction light deflection member 25X are configured to be overlapped by the PBS member 24X.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a measurement method and an encoder apparatus for measuring a relative movement amount between two members that move relative to each other, an exposure technique using the measurement method and the encoder apparatus, and a device manufacturing method using the exposure technique.

  In an exposure apparatus such as a so-called stepper or scanning stepper used in a photolithography process for producing an electronic device (microdevice) such as a semiconductor element, the position measurement of a stage that moves a substrate to be exposed has conventionally been a laser. It was done by an interferometer. However, in the laser interferometer, since the optical path of the measurement beam is long and changes, short-term fluctuations in measured values due to temperature fluctuations in the atmosphere on the optical path are becoming difficult to ignore.

  Therefore, for example, the measurement light made of laser light is irradiated from the detection unit fixed to the frame to the diffraction grating fixed to the stage, and interference light between the diffracted light generated from the diffraction grating and other diffracted light or reference light is emitted. A so-called encoder device (interference encoder) that measures a relative movement amount of a member (stage or the like) provided with the diffraction grating from a detection signal obtained by photoelectric conversion is also being used (see, for example, Patent Document 1). . This encoder device is excellent in short-term stability of measurement values as compared with a laser interferometer, and has a resolution close to that of a laser interferometer.

US Pat. No. 8,134,688

The conventional encoder device has a complicated optical system configuration for superimposing the diffracted light generated from the diffraction grating and other diffracted light or reference light, which increases the manufacturing cost of the optical system and allows adjustment of the optical system. It took a long time.
In view of such problems, an aspect of the present invention aims to simplify an optical system of an apparatus that measures a relative movement amount using a diffraction grating.

  According to a first aspect of the present invention, there is provided an encoder device for measuring a relative movement amount of a first member and a second member that can move relative to each other with respect to a first direction, the encoder device being provided on the first member. A reflection type diffraction grating having a grating pattern with one direction as a periodic direction, a branching portion for branching light from a light source into measurement light and reference light having different polarization states, and a second member thereof. A first optical member that causes measurement light to be incident on the grating pattern of the diffraction grating, and a second optical member that is provided on the second member and that causes diffraction light from the grating pattern caused by the measurement light to be incident on the first optical member. The reference light that enters the first optical member from the branch portion and the diffracted light that enters the first optical member from the second optical member are at least partially overlapped with each other The first Encoder device for emitting undergraduate material is provided.

  According to the second aspect, the encoder device measures the relative movement amount of the first member and the second member that can move relative to each other with respect to the first direction, the encoder device being provided on the first member, A reflection type diffraction grating having a grating pattern with a periodic direction; a branching portion for splitting light from a light source into measurement light and first and second reference lights having different polarization states; A first optical member that is provided on the member and causes the measurement light to enter the grating pattern of the diffraction grating; and a second optical member that is provided on the second member and has a predetermined order of the diffracted light from the grating pattern by the measurement light. A second deflector provided with a first deflector for deflecting one diffracted light and a second deflector for deflecting second diffracted light having a different order from the first diffracted light among the diffracted light from the grating pattern by the measurement light. An optical member, the first of which The folded light re-enters the grating pattern through the first deflecting unit, is diffracted by the grating pattern, and re-enters the first deflecting unit, and the second diffracted light passes through the second deflecting unit. Re-enters the grating pattern, is diffracted by the grating pattern, re-enters the second deflecting unit, and the first and second reference beams from the branching unit enter the first optical member, and The first diffracted light re-entering the first deflecting portion is superposed on the first reference light by the first optical member, and the second diffracted light re-entering the second deflecting portion is the first diffracted light. An encoder device is provided that is superposed on the second reference light by an optical member.

According to the third aspect, there is provided an exposure apparatus that exposes a pattern onto an object to be exposed, the frame, a stage that supports the object to be exposed and is relatively movable in at least a first direction with respect to the frame, An exposure apparatus is provided that includes at least an encoder apparatus according to an aspect of the present invention for measuring a relative movement amount between the frame and the stage in the first direction.
According to a fourth aspect, there is provided a method for measuring a relative movement amount between a first member and a second member that can move relative to each other with respect to a first direction, wherein the measurement light and the measurement light have different polarization states. Injecting the measurement light into the grating pattern of the reflective diffraction grating provided in the first member via the optical member provided in the second member, and Diffracted light is generated from the grating pattern by measurement light, the diffracted light generated from the grating pattern is incident on the optical member, the reference light is incident on the optical member, and the reference light And the diffracted light are emitted from the optical member in a state of being at least partially overlapped.

According to a fifth aspect, there is provided an exposure method for exposing a pattern to an object to be exposed supported on a stage that is relatively movable in at least a first direction with respect to a frame, and at least the frame in the first direction; An exposure method using the measurement method of the aspect of the present invention to measure the relative movement amount with respect to the stage is provided.
According to a sixth aspect, there is provided a device manufacturing method including a lithography process, and exposing an object using the exposure apparatus according to the aspect of the present invention or the exposure method according to the aspect of the present invention in the lithography process.

  According to the aspect of the present invention, since the reference light and the diffracted light are superimposed on the first optical member that makes the measurement light incident on the grating pattern of the diffraction grating, the optical system can be simplified.

It is a top view which shows the encoder which concerns on 1st Embodiment. (A) is a perspective view showing the main part of the X-axis interferometer section in FIG. 1, (B) is a plan view showing the irradiation position of the measurement light and diffracted light in FIG. 2 (A), (C) is It is explanatory drawing of the opening angle of measurement light and reference light. FIG. 2A is a diagram showing the optical path of ± first-order diffracted light in the X direction in the X-axis interferometer section of FIG. 2A, and FIG. 2B is a diagram showing optical paths of ± first-order diffracted light in the Y-axis interferometer section. It is. (A) is a figure which shows the change of the optical path of a diffracted light when the relative height of a grating | lattice pattern surface changes in the interferometer part of the X-axis of FIG. 2 (A), (B) is a relative grating | lattice pattern surface. It is a figure which shows the change of the optical path of the diffracted light when it inclines periodically. (A) is a figure which shows the principal part of the interferometer part of the X-axis which concerns on a modification, (B) is a perspective view which shows the roof mirror in FIG. 5 (A). (A) is a figure which shows the principal part of the interferometer part of the X-axis which concerns on a modification, (B) is a top view which shows the irradiation position of the measurement light and diffracted light in FIG. 6 (A). (A) is a top view showing an X-axis interferometer section according to a modification, and (B) is a side view thereof. It is a figure which shows schematic structure of the exposure apparatus which concerns on 2nd Embodiment. FIG. 9 is a plan view showing an example of the arrangement of diffraction gratings and a plurality of detection heads provided on the wafer stage of FIG. 8. It is a block diagram which shows the control system of the exposure apparatus of FIG. It is a flowchart which shows an example of the measuring method. It is a flowchart which shows an example of the manufacturing method of an electronic device.

[First Embodiment]
A first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a plan view showing an encoder 10 according to the present embodiment. In FIG. 1, as an example, the second member 7 is arranged so as to be relatively movable in three dimensions with respect to the first member 6, and the X axis is parallel to two directions of the second member 7 that are relatively movable relative to each other. The Z axis is taken along the relative movement direction perpendicular to the plane (XY plane) defined by the X axis and the Y axis. In addition, the angles around axes parallel to the X axis, the Y axis, and the Z axis are also referred to as angles in the θx, θy, and θz directions, respectively.

  In FIG. 1, an encoder 10 includes a flat plate-like two-dimensional diffraction grating 12 fixed to the upper surface of a first member 6 and substantially parallel to the XY plane, a detection head 14 fixed to the second member 7, and a detection. A laser light source 16 and an optical fiber 17 for supplying measurement laser light to the head 14, optical fibers 39XA, 39XB, 39YA, 39YB, 39C for transmitting a plurality of interference lights generated by the detection head 14, and these optical fibers Photoelectric sensors 40XA, 40XB, 40YA, 40YB, 40C, such as photodiodes, which receive a plurality of interference lights supplied via 39XA to 39C and output detection signals, and process the detection signals to form a first member A measurement calculation unit 42 (42X, 42Y, 42T) for obtaining a three-dimensional relative movement amount of the second member 7 with respect to the X direction, the Y direction, and the Z direction. That. The detection head 14 irradiates the diffraction grating 12 with measurement light, generates an X-axis interferometer unit 15X that generates a plurality of interference lights of a plurality of diffraction lights generated in the X direction from the diffraction grating 12 and a reference light, and a diffraction The Y-axis interferometer unit 15Y that irradiates the grating 12 with measurement light and generates a plurality of interference lights of the plurality of diffracted lights generated in the Y direction from the diffraction grating 12 and the reference light, and the interferometer units 15X and 15Y. Branch portions 32X and 32Y for supplying measurement light and reference light, other optical members, and a support member 35 fixed to the second member 7 to support the plurality of optical members, respectively.

  On the grating pattern surface 12b substantially parallel to the XY plane of the diffraction grating 12, a two-dimensional grating pattern 12a having a predetermined period (pitch) p in the X and Y directions and having a phase type and a reflection type is formed. Yes. The period p in the X direction and the Y direction of the lattice pattern 12a is, for example, about 100 nm to 4 μm (for example, 1 μm period). Note that the periods of the lattice pattern 12a in the X direction and the Y direction may be different from each other. The grating pattern 12a can be manufactured, for example, as a hologram (for example, a photosensitive resin baked with interference fringes) or by mechanically forming a groove or the like on a glass plate or the like and depositing a reflective film. Furthermore, the lattice pattern surface 12b may be covered with a protective flat glass.

  The laser light source 16 is made of, for example, a He—Ne laser, a semiconductor laser, or the like. Emits frequency heterodyne light. These laser beams are coherent with each other (when the polarization directions are parallel), and their average wavelength is λ. The laser light source 16 supplies a signal of a reference frequency (reference signal) obtained by photoelectric conversion of interference light of two light beams branched from the laser light to the measurement calculation unit 42. A homodyne interference method can also be used.

  The optical fiber 17 is a double core type polarization maintaining optical fiber that transmits the laser beams ML and RL emitted from the laser light source 16 while maintaining the polarization direction. In the present embodiment, when emitted from the optical fiber 17, the first laser light ML is linearly polarized light polarized in the X direction parallel to the XY plane, and the second laser light RL is linearly polarized in the Z direction. Polarized light. The other optical fibers 39XA to 39YB and 39C are single-core types, but may be any polarization-maintaining type or normal type. Moreover, you may provide a condensing lens in the entrance of optical fiber 39XA-39YB, 39C. Note that the intermediate portions of the optical fibers 17, 39XA to 39YB, etc. are omitted in FIG. Further, instead of the optical fiber 17, a beam transmission optical system in which a plurality of mirrors are combined may be used. Without using the optical fibers 39XA to 39YB and 39C, the interference light is directly detected by the photoelectric sensors 40XA to 40YB, Light may be received at 40C.

  The detection head 14 includes a lens 18 that converts the laser beams ML and RL emitted from the optical fiber 17 into parallel light beams, and the laser beams ML and RL emitted from the lens 18 as X-axis measurement light MX and reference light RX. , A half prism portion 20A having a beam splitter surface A1 that is divided into measurement light MY for Y-axis and reference light RY, a branching portion 20B, and an interference portion 20C. The Y-axis measurement light MY and the reference light RY emitted from the half prism portion 20A in parallel to the X-axis are incident on the Y-axis branch portion 32Y.

  The X-axis measurement light MX and the reference light RX emitted from the half prism portion 20A parallel to the Y-axis are the first light beam parallel to the Y-axis and the first light beam parallel to the X-axis on the beam splitter surface A2 of the branching member 20B. The first light beam is incident on the X-axis branch portion 32X. In the present embodiment, the X-axis measurement light MX and the reference light RX emitted from the half prism unit 20A are heterodyne beams linearly polarized in the X direction and the Z direction, respectively, and the Y axis measurement emitted from the half prism 20A. The light MY and the reference light RY are heterodyne beams linearly polarized in the Y direction and the Z direction, respectively. The measurement beams MX and MY and the reference beams RX and RY have a circular (e.g., oval or rectangular) cross section with a diameter of about 0.5 to several mm, for example.

  As shown in FIG. 2C, since the laser beams ML and RL are emitted from the adjacent core portion of the optical fiber 17 and converted into a parallel beam by the lens 18, the laser beam ML after being converted into a parallel beam. , RL intersect at a predetermined small angle β. For this reason, the measurement light MX and the reference light RX emitted from the half prism portion 20A, and the measurement light MY and the reference light RY are relatively inclined at an angle β. As described above, by relatively tilting the measurement light MX and the reference light RX (measurement light MY and reference light RY), it is possible to reduce noise light mixed in interference light that is finally detected.

  In FIG. 1, the interference part 20C is disposed so as to face the end face in the −X direction of the support member 35, and a polarizing plate 41C is fixed at a position facing the interference part 20C on the end face in the + X direction of the support member 35. The polarizing plates 41XA, 41XB and 41YA, 41YB are fixed so as to sandwich the plate 41C in the Y direction, and the incident ends of the optical fibers 39XA, 39XB, 39YA, 39YB, 39C are respectively attached to the polarizing plates 41XA, 41XB, 41YA, 41YB, 41C. It is fixed.

The directions of the crystal axes of the polarizing plates 41XA to 41YB and 41C are oblique so as to generate interference light by combining diffracted light to be measured linearly polarized in the Y direction, which will be described later, and reference light linearly polarized in the Z direction. Is set to Openings are formed in front of the polarizing plates 41XA to 41YB and 41C in the support member 35 so as to pass the light fluxes to be detected.
Further, in the branching unit 20B, the measurement light MXC polarized in the Y direction out of the second light flux emitted from the beam splitter surface A2 is transmitted through the polarization beam splitter surface (hereinafter referred to as PBS surface) A3 and reflected by the reflecting surface. It is reflected and enters the interference part 20C. Of the second light flux, the reference light RXC polarized in the Z direction is reflected by the PBS surface A3 and enters the interference unit 20C via the pair of wedge-shaped prisms 36E. In the interference unit 20C, the measurement light MXC reflected in the + X direction is superimposed on the reference light RXC on the PBS surface A4, that is, coaxially synthesized (combined) and emitted in the + X direction. The measurement light MXC and the reference light RXC synthesized coaxially become reference interference light through the polarizing plate 41C, and are received by the photoelectric sensor 40C through the optical fiber 39C.

Furthermore, the pair of wedge-shaped prisms 36E cancels the traveling direction of the incident reference light RXC by an angle β (see FIG. 2C) between the measurement light MX, MY and the reference light RX, RY. By changing, the reference light and the measurement light (or diffracted light) to be measured are made parallel. The same applies to other wedge-shaped prisms 36A described later.
In addition, the light beam incident on the X-axis branch portion 32X is reflected in the −X direction, and among the reflected light beam, the measurement light MX polarized in the Y direction passes through the PBS surface A5 (separation surface). The light is reflected and enters the interferometer unit 15X in the −Y direction parallel to the Y axis. On the other hand, of the reflected light flux, the reference light RX polarized in the Z direction is reflected by the PBS surface A5, then reflected in the -X direction, and enters the beam splitter surface A6. The first reference light RX1 reflected in the −Y direction by the beam splitter surface A6 and the second reference light RX2 reflected in the −Y direction after passing through the beam splitter surface A6 are each a pair of wedge prisms. The measurement light MX is incident on the interferometer unit 15X in parallel with the measurement light MX sandwiched in the center via 36A and 36B.

  The Y-axis branch portion 32Y is configured by rotating the X-axis branch portion 32X by 90 degrees, and the measurement light MY branched from the light beam incident on the Y-axis branch portion 32Y and polarized in the Y direction is + X The light enters the interferometer unit 15Y in the direction. Then, the first reference light RY1 and the second reference light RY2 branched from the light beam incident on the branching portion 32Y and polarized in the Z direction respectively center the measurement light MY via the pair of wedge-shaped prisms 36AC and 36D. In the sandwiched state, the light enters the interferometer unit 15Y in the + X direction in parallel.

  Further, the X-axis interferometer unit 15X has a polarization beam splitter surface (hereinafter referred to as a PBS surface) A11 (FIG. 2 (FIG. 2)) on which the measurement light MX and the reference beams RX1 and RX2 emitted from the branching unit 32X in the −Y direction are incident. A) and a pair of roof prisms 26XA and 26XB which are fixed symmetrically so as to sandwich the PBS member 24X in the X direction. And a reflecting member 30X made of right-angle prism-like members 30XA and 30XB each having a pair of two reflecting surfaces orthogonal to each other and disposed above the PBS member 24X and fixed to the roof prism 26XA. Furthermore, the interferometer unit 15X includes parallel plate-shaped additional members 28XA and 28XB (see FIG. 2A) fixed so as to cover the −Y-direction half surfaces of the bottom surfaces of the roof prisms 26XA and 26XB, and a PBS member 24X. And an adjustment member 29 </ b> X (see FIG. 3A) made of a parallel plate phase plate disposed between the diffraction grating 12 and the diffraction grating 12.

  The roof prisms 26XA, 26XB, the reflecting member 30X, and the additional members 28XA, 28XB constitute the diffracted light deflecting member 25X that converts the direction of the diffracted light generated by the diffraction grating 12, and the roof prism 26XA, the reflecting member 30X, and the additional member A first deflecting member that converts the direction of the diffracted light generated in the + X direction is configured from the member 28XA, and the direction of the diffracted light generated in the −X direction from the roof prism 26XB, the reflecting member 30X, and the additional member 28XB is configured. A second deflecting member to be converted is configured. The upper surfaces of the roof prisms 26XA and 26XB and the reflecting member 30X are on the same plane, and the upper surfaces are fixed to the bottom surface (the surface facing the diffraction grating 12) of the second member 7 (see FIG. 3A).

  FIG. 2A shows the PBS member 24X and the diffracted light deflection member 25X of the interferometer unit 15X in FIG. 2A, the PBS member 24X is disposed on the bottom surface side of the large member 30XA on the −Y direction side of the reflecting member 30X, and the PBS surface A11 is 45 ° around the X axis with respect to the XY surface. It is inclined at. The PBS member 24X has a rectangular parallelepiped shape surrounded by six planes, two planes parallel to the XY plane, two planes parallel to the YZ plane, and two planes parallel to the ZX plane. Good. For example, the PBS member 24X includes a PBS surface A11 inclined at 45 ° around the X axis with respect to the XY plane, one plane parallel to the XY plane, two planes parallel to the YZ plane, and parallel to the ZX plane. It may have a triangular prism shape surrounded by five surfaces. At this time, a plane parallel to the XY plane may be directed to the + Z direction side, or may be directed to the −Z direction side. The roof prism 26XA of the diffracted light deflection member 25X is symmetric with respect to an incident surface A12 inclined at an angle α1 (see FIG. 3A) counterclockwise with respect to the bottom surface of the PBS member 24X, and a ridge line A19 parallel to the XZ plane. And a pair of reflecting surfaces A13, A14 formed to be orthogonal to each other, and an exit surface A15 in close contact with the PBS member 24X and the members 30XA, 30XB. The ridge line A19 of the roof prism 26XA is inclined at an angle α2 counterclockwise with respect to the ZY plane (see FIG. 3A). The other roof prism 26XB has a symmetrical shape with the roof prism 26XA, and the roof prism 26XB also has two reflecting surfaces A23, A24 and a ridge line A29 that are orthogonal to each other.

  1 is incident on the PBS surface A11 in the -Y direction as S-polarized light with respect to the PBS surface A11, and is reflected in the -Z direction by the PBS surface A11. It enters perpendicularly (parallel to the Z axis) to the 12X lattice pattern surface 12b (lattice pattern 12a). On the other hand, the reference beams RX1 and RX2 emitted from the branching section 32X are incident on the PBS surface A11 in the approximately −Y direction as P-polarized light with respect to the PBS surface A11 and are transmitted through the PBS surface A11. Here, when the measurement light MX is incident vertically, in addition to the case where the measurement light MX is incident perpendicularly to the lattice pattern surface 12b, the measurement light MX is measured in order to reduce the influence of zero-order light (regular reflection light). The light MX is inclined approximately 0.5 to 1.5 °, for example, in the X direction (θy direction) and / or the Y direction (θx direction) with respect to an axis parallel to the Z axis, and enters the grating pattern surface 12b substantially perpendicularly. The case of making it include is also included.

  In the present embodiment, ± first-order diffracted lights DX1 and DX2 are generated symmetrically in the X direction by the measurement light MX that is perpendicularly incident on the grating pattern surface 12b of the diffraction grating 12. The generated diffracted light DX1 enters the incident surface of the roof prism 26XA, and the diffracted light DX2 enters the incident surface of the roof prism 26XB. At this time, ± first-order diffracted light is also generated symmetrically in the Y direction, but the diffracted light in the Y direction is not used in the X-axis interferometer unit 15X. The + 1st-order diffracted light DX1 is shifted in the + Y direction via the incident surface A12 and the reflective surfaces A13 and A14 of the roof prism 26XA, and is directed to the -X direction parallel to the X axis via the exit surface A15 and the reflecting member. The light enters the reflecting surface A18 of the small member 30XB of 30X. Then, the diffracted light DX1 reflected by the reflecting surface A18 is perpendicularly incident on the grating pattern surface 12b of the diffraction grating 12. In contrast to this, the −1st order diffracted light DX2 is shifted in the + Y direction via the reflecting surfaces A23, A24, etc. of the roof prism 26XB, and is directed to the reflecting surface A28 of the member 30XB in the + X direction parallel to the X axis. The diffracted light DX2 that is incident and reflected by the reflecting surface A28 enters the grating pattern 12a of the diffraction grating 12 perpendicularly.

  As shown in FIG. 2B, the position where the diffracted light DX1, DX2 is incident on the position where the measurement light MX is incident on the grating pattern 12a is shifted by the interval a1 in the Y direction and the X direction. Symmetrically shifted by a distance a2. The distance a1 is approximately ½ of the width of the PBS member 24X in the Y direction, and the distance a2 is approximately ３ of the width of the PBS member 24X in the X direction. In other words, the position where the measurement light MX is incident on the grating pattern 12a passes through the midpoint of the line connecting the positions where the diffracted lights DX1 and DX2 are incident, and is located on a straight line perpendicular to the line segment in the XY plane. . By making the measurement light MX and the diffracted lights DX1 and DX2 enter the diffraction grating 12 with such an arrangement, the configuration of the interferometer unit 15X can be reduced in size. However, the distances a1 and a2 are arbitrary. In addition, the arrangement of the incident positions of the measurement light MX and the diffracted lights DX1 and DX2 is arbitrary.

  The diffracted lights DX1 and DX2 reflected by the member 30XB generate + 1st order diffracted light EX1 and −1st order diffracted light EX2 (rediffracted light) from the diffraction grating 12 symmetrically in the X direction. The diffracted light EX1 is sequentially reflected by the reflecting surfaces A14 and A13 of the roof prism 26XA through the incident surface A17 of the additional member 28XA, thereby shifting in the -Y direction and parallel to the X axis toward the -X direction. The light enters the reflecting surface A16 of the small member 30XA. Then, the S-polarized diffracted light EX1 reflected in the −Z direction by the reflecting surface A16 is reflected by the PBS surface A11 of the PBS member 24X and superimposed on the first reference light RX1 (coaxially synthesized or combined). E) ejected from the PBS member 24X in the -Y direction. In contrast to this, the diffracted light EX2 is sequentially reflected by the reflecting surfaces A24 and A23 of the roof prism 26XB through the incident surface of the additional member 28XB, thereby shifting in the −Y direction and parallel to the X axis in the + X direction. Toward the reflecting surface A26 of the member 30XA. Then, the S-polarized diffracted light EX2 reflected by the reflecting surface A26 is reflected by the PBS surface A11 and superimposed on the second reference light RX2 (combined or combined coaxially) in the −Y direction. Injected from the member 24X. Here, the diffracted light EX1 and the reference light RX1 do not need to overlap completely in their cross section (XZ plane), and only need to partially overlap. In other words, the diffracted light EX1 and the reference light RX1 do not have to be completely coaxial when emitted from the PBS member 24X, and as long as some of them are overlapped and are parallel to each other. Good. Further, the diffracted light EX1 and the reference light RX1 emitted from the PBS member 24X do not have to be completely parallel, and the diffracted light EX1 and the reference light RX1 are at least partially overlapped at the position of the polarizing plate 41XA. If there is, it may be slightly deviated from parallel. Since the same applies to the diffracted light EX2 and the reference light RX2, the description thereof is omitted here.

The additional members 28XA and 28XB are provided for adjusting the incident positions of the diffracted lights EX1 and EX2 with respect to the PBS surface A11 by emitting the diffracted lights EX1 and EX2 incident on the additional member in a state of being transferred in the ± X direction. It has been. The additional members 28XA and 28XB can be omitted.
Further, as an example, the adjustment member 29X in FIG. 3A finally allows the diffracted light DX1, DX2, EX1, and the diffracted light EX1, EX2, so that the diffracted light EX1, EX2 enters the PBS member 24X accurately in the S-polarized state. The polarization direction (polarization state) of EX2 is individually adjusted. The adjusting member 29X can be omitted. Moreover, it may replace with the adjustment member 29X and you may provide the cover glass which consists of a parallel plane plate-shaped light transmissive member.

  In FIG. 1, the light beam including the diffracted light EX1 and the reference light RX1 emitted from the PBS member 24X and the light beam including the diffracted light EX2 and the reference light RX2 are reflected by the reflecting member 22, and then are polarizing plates 41XA and 41XB, respectively. Then, the first interference light and the second interference light are received by the photoelectric sensors 40XA and 40XB via the optical fibers 39XA and 39XB. The polarizing plates 41XA and 41XB may be provided on the exit surface of the PBS member 24X (a plane parallel to the XZ plane located on the −Y direction side of the PBS member 24X).

  The Y-axis interferometer section 15Y includes a PBS member 24Y and a diffracted light deflection member 25Y that are configured by integrally rotating the PBS member 24X and the diffracted light deflection member 25X of the X-axis interferometer section 15X by 90 ° (see FIG. (See FIG. 3B). That is, the diffracted light deflecting member 25Y also has a reflecting member 30Y composed of a roof prism 26YA, 26YB, a large member 30YA, and a small member 30YB. The additional members 28YA, 28YB are fixed to the roof prisms 26YA, 26YB, and the PBS member. An adjustment member 29Y is provided between 24Y and the diffraction grating 12. The reflecting member 30Y is fixed to the roof prism 26YA, and the upper surfaces of the reflecting member 30Y and the roof prisms 26YA and 26YB are fixed to the second member 7. Here, since the upper surface of the interferometer unit 15X is fixed to the second member 7, the structural member on the lower surface side of the interferometer unit 15X can be eliminated or thinned, so that the working distance of the interferometer unit is increased. Can do.

  The measurement light MY and the reference lights RY1 and RY2 emitted from the branching section 32Y enter the PBS member 24Y of the interferometer section 15Y, and the P-polarized reference lights RY1 and RY2 pass through the PBS surface of the PBS member 24Y and + X Injected in the direction. Then, the S-polarized measurement light MY is reflected by the PBS surface of the PBS member 24Y and enters the grating pattern 12a of the diffraction grating 12 perpendicularly, and ± 1st-order diffracted lights DY1, DY2 (symmetrical in the Y direction) from the grating pattern 12a (FIG. 3 (B)) occurs. The ± first-order diffracted light generated in the X direction is not used in the interferometer unit 15Y. These diffracted lights DY1 (DY2) are perpendicularly incident on the grating pattern 12a of the diffraction grating 12 through the roof prism 26YA (26YB) and the reflecting member 30Y. Then, a + 1st order diffracted light EY1 in the Y direction by the diffracted light DY1 and a −1st order diffracted light EY2 in the Y direction by the diffracted light DY2 are generated from the diffraction grating 12. The diffracted light EY1 is reflected by the PBS surface of the PBS member 24Y via the additional member 28YA, the roof prism 26YA, and the reflecting member 30Y, is superimposed on the first reference light RY1, and is emitted in the + X direction. The diffracted light EY2 is reflected by the PBS surface of the PBS member 24Y via the additional member 28YB, the roof prism 26YB, and the reflecting member 30Y, is superimposed on the second reference light RY2, and is emitted in the + X direction.

Then, the light beam including the diffracted light EY1 and the reference light RY1 and the light beam including the diffracted light EY2 and the reference light RY2 emitted from the PBS member 24Y pass through the polarizing plates 41YA and 41YB, respectively. Thus, the light is received by the photoelectric sensors 40YA and 40YB via the optical fibers 39YA and 39YB.
In FIG. 1, the measurement calculation unit 42 includes a first calculation unit 42X, a second calculation unit 42Y, and a third calculation unit 42T. Then, the X-axis photoelectric sensor 40XA supplies an interference light detection signal (photoelectric conversion signal) composed of the diffracted light EX1 and the reference light RX1 to the first calculation unit 42X, and the photoelectric sensor 40XB includes the diffracted light EX2 and the reference light. The detection signal of the interference light composed of RX2 is supplied to the first calculation unit 42X. Further, the Y-axis photoelectric sensor 40YA supplies an interference light detection signal made up of the diffracted light EY1 and the reference light RY1 to the second arithmetic unit 42Y, and the photoelectric sensor 40YB makes an interference light made up of the diffracted light EY2 and the reference light RY2. The detection signal is supplied to the second calculation unit 42Y. The first calculation unit 42X and the second calculation unit 42Y include a reference frequency signal (reference signal) from the laser light source 16 and a reference frequency signal (reference) of the reference interference light detected by the photoelectric sensor 40C. Signal) is also provided.

  Here, the X, Y, and Z direction relative movement amounts (relative displacements) between the first member 6 and the second member 7 are X, Y, Z, and the first calculation unit 42X and the second calculation unit 42Y. Assume that the obtained relative movement amounts in the Z direction are ZX and ZY, respectively. At this time, as an example, the first calculation unit 42X uses the detection coefficient and the reference signal (or reference signal) of the photoelectric sensor 40XA and the first relative movement amount in the X direction and the Z direction using the known coefficients a and b. (A · X + b · ZX) is obtained, and the second relative movement amount (−a · X + b · ZX) in the X direction and the Z direction is obtained from the detection signal and the reference signal (or reference signal) of the photoelectric sensor 40XB. A relative movement amount (X) in the X direction and a relative movement amount (ZX) in the Z direction are obtained from the first and second relative movement amounts, and the obtained results are supplied to the third calculation unit 42T. The second calculation unit 42Y obtains the first relative movement amount (a · Y + b · ZY) in the Y direction and the Z direction from the detection signal and the reference signal (or reference signal) of the photoelectric sensor 40YA, and detects the photoelectric sensor 40YB. The second relative movement amount (−a · Y + b · ZY) in the Y direction and the Z direction is obtained from the signal and the reference signal (or reference signal), and the relative movement in the Y direction is obtained from the first and second relative movement amounts. The amount (Y) and the relative movement amount (ZY) in the Z direction are obtained, and the obtained result is supplied to the third calculation unit 42T.

  The third calculation unit 42T calculates a value obtained by correcting the relative movement amounts (X) and (Y) supplied from the calculation units 42X and 42Y with a predetermined offset in the X direction of the first member 6 and the second member 7, Y Output as the amount of relative movement in the direction. In addition, as an example, the third calculation unit 42T calculates an average value (= (ZX + ZY) / 2) of the relative movement amounts (ZX) and (ZY) in the Z direction supplied from the calculation units 42X and 42Y with a predetermined offset. The corrected value is output as the relative movement amount in the Z direction between the first member 6 and the second member 7. The detection resolution of the relative movement amount in the X direction, the Y direction, and the Z direction is, for example, about 0.5 to 0.1 nm. In the encoder 10, since the optical paths of the measurement light MX, MY, etc. are short, short-term fluctuations in the measurement value due to the temperature fluctuation of the gas on the optical path can be reduced. Furthermore, since the interference light of the reference lights RX1 to RY2 corresponding to the + 1st order diffracted beams EX1 and EY1 and the −1st order diffracted beams EX2 and EY2 for the second time is finally detected, the detection resolution of the relative movement amount (detection accuracy) ) Can be improved to 1/2 (miniaturized). In addition, by using ± first-order diffracted light, measurement errors due to the relative rotation angles of the first member 6 and the second member 7 in the θz direction can be reduced.

Next, the optical path of the diffracted light of the detection head 14 of this embodiment will be described in detail.
FIG. 3A shows the main part of the X-axis interferometer unit 15X and the diffraction grating 12. FIG. In FIG. 3A, when the measurement light MX is incident on the grating pattern 12a of the diffraction grating 12 perpendicularly (parallel to the Z axis), the diffraction angle φx of the + 1st order diffracted light DX1 in the X direction by the measurement light MX is The following relationship is satisfied using the period p of the pattern 12a and the wavelength λ of the measurement light MX. At this time, the diffraction angle of the −1st order diffracted light DX2 in the X direction by the measurement light MX is −φx.

p · sin (φx) = λ (1)
As an example, if the period p is 1000 nm (1 μm) and the wavelength λ of the measurement light MX is 633 nm, the diffraction angle φx is approximately 39 °.
The diffracted light DX1 is bent by the roof prism 26XA (incident surface A12 and reflecting surfaces A13, A14) and the reflecting member 30X so as to be parallel to the measuring light MX (here, parallel to the Z axis). Re-incident on. Accordingly, the angle α1 of the incident surface A12 of the roof prism 26XA, the angle α2 of the ridge line A16, the refractive index ng, and the incident angle i (a function of the angle α1 and the diffraction angle φx) of the diffracted light DX1 with respect to the incident surface A12 are reflected members. It is preferable that the diffracted light DX1 reflected by 28XA is determined so as to be substantially parallel to the Z axis.

Furthermore, in the present embodiment, the rate of change (dδ / di) regarding the incident angle i of the deflection angle δ of the diffracted light DX1 incident on the incident surface A12 of the roof prism 26XA is set to cos (φx) as follows. It is preferable.
dδ / di = cos (φx) = cos {arcsin (λ / p)} (3)
The condition of this equation (3) is that the rate of change (dδ / di) of the deflection angle δ at the incident surface A12 is the diffraction angle of the diffracted light DX1 when the incident angle of the measuring light MX with respect to the diffraction grating 12 changes from zero. This means that the rate of change is canceled by the incident surface A12 (details will be described later).

  When the measurement light MX is incident on the grating pattern 12a perpendicularly (parallel to the Z axis), the diffracted light DX1 reflected by the roof prism 26XA and the like is shifted in the + X direction and the + Y direction from the position where the measurement light MX is incident. It enters the grating pattern 12a perpendicularly at the position (see FIG. 2B). The diffraction angle of the + 1st order diffracted light EX1 generated from the diffraction grating 12 by the diffracted light DX1 is the same as φx in the equation (1), and the diffracted light EX1 has its optical path bent parallel to the Z axis by the roof prism 26XA or the like. Heading toward the PBS surface A11 of the PBS member 24X. At this time, the −1st order diffracted light DX2 from the diffraction grating 12 by the measurement light MX is shifted in the −X direction and the + Y direction from the position where the measurement light MX is incident through the roof prism 26XB and the like symmetrically with the diffraction light DX1. Thus, the light is incident on the grating pattern 12a perpendicularly (see FIG. 2B). The −1st-order diffracted light EX2 generated from the diffraction grating 12 by the diffracted light DX2 is bent in the optical path parallel to the Z axis by the roof prism 26XB and the like, and travels toward the PBS surface A11.

  FIG. 3B shows the main part of the Y-axis interferometer unit 15Y and the diffraction grating 12. FIG. In FIG. 3B, when the measurement light MY is perpendicularly incident on the grating pattern 12a of the diffraction grating 12, the diffraction angle φy of the + 1st order diffracted light DY1 in the Y direction by the measurement light MY is in the X direction of the equation (1). It is the same as the diffraction angle φx. The diffracted light DY1 reflected by the roof prism 26YA or the like is perpendicularly incident on the grating pattern 12a at a position shifted in the −X direction and the + Y direction from the position where the measurement light MY is incident. On the other hand, the diffracted light DY2 reflected by the roof prism 26YB or the like is perpendicularly incident on the grating pattern 12a at a position shifted in the −X direction and the −Y direction from the position where the measurement light MY is incident. The + 1st order diffracted light EY1 generated from the diffraction grating 12 by the diffracted light DY1 through the roof prism 26YA and the −1st order diffracted light EY2 generated from the diffraction grating 12 by the −1st order diffracted light DY2 in the Y direction by the measurement light MY are The optical path is bent parallel to the Z axis by the roof prisms 26YA, 26YB, etc., and heads toward the PBS surface of the PBS member 24Y.

  In the arrangement of FIG. 3A, as shown in FIG. 4A (additional members 28XA and 28XB are not shown), the grating pattern surface 12b of the diffraction grating 12 with respect to the interferometer unit 15X. Assume that the relative position in the Z direction changes by δZ up to position B11. At this time, the + 1st order diffracted light DX1 by the measurement light MX is incident on the roof prism 26XA with the optical path shifted parallel to the position B12. The roof prism 26XA shifts the optical path of the emitted light symmetrically with respect to the incident light with respect to the center (ridge line A19). Therefore, the diffracted light DX1 reflected by the roof prism 26XA enters the diffraction grating 12 at a position that intersects the optical path of the + 1st order diffracted light EX1 when the relative position in the Z direction of the grating pattern surface 12b is not changed. Therefore, even if the grating pattern surface 12b is changed to the position B11, the relative position in the Z direction of the grating pattern surface 12b of the optical path B13 of the + 1st order diffracted light EX1 generated from the diffraction grating 12 by the diffracted light DX1 is not changed. It is the same as the optical path of time. For this reason, when the diffracted light EX1 and the reference light RX1 are coaxially combined at the PBS surface A11, there is no relative lateral shift between the diffracted light EX1 and the reference light RX1, and therefore the interference light obtained from the light beam is photoelectrically converted. The ratio of the AC signal (beat signal or signal component) in the detection signal obtained at the time does not decrease.

  The same applies to the X-order −1st-order diffracted light DX2 and the Y-axis ± 1st-order diffracted lights DY1 and DY2, and even if the relative position in the Z direction of the grating pattern surface 12b changes, the photoelectric sensors 40XA to 40XA of FIG. The ratio of the beat signal in the 40YB detection signal does not decrease. Therefore, the relative movement amount between the first member 6 and the second member 7 can be measured with high accuracy at a high S / N ratio using these detection signals.

  Next, in the arrangement of FIG. 3A, as shown in FIG. 4B, the grating pattern surface 12b of the diffraction grating 12 with respect to the interferometer portion 15X is an angle ε around an axis parallel to the Y axis. Assume the case of changing counterclockwise. At this time, when the incident angle of the measurement light MX with respect to the grating pattern surface 12b is ε, and the diffraction angle of the + 1st order diffracted light DX1 is (φx + δφx), the following relationship is established.

sin (φx + δφx) −sinε = λ / p (4)
Here, assuming that ε and δφx are very small, the derivative of sin (φx) is cos (φx), and therefore equation (4) is as follows.
sin (φx) + cos (φx) · δφx−ε = λ / p (5)
In equation (5), considering that sin (φx) is λ / p from equation (1), the following equation is obtained.

δφx = ε / cos (φx) (6)
Further, the change amount δφ of the angle of the optical path B22 of the + 1st order diffracted light DX1 from the diffraction grating 12 when the grating pattern surface 12b is inclined by the angle ε is as follows.
δφ = {1 + 1 / cos (φx)} ε (7)
Further, since the rate of change (dδ / di) of the deflection angle δ on the incident surface A12 of the roof prism 26XA with respect to the incident angle i is cos (φx) as shown in the expression (3), it passes through the roof prism 26XA. The change amount δε1 of the angle of the optical path B23 of the diffracted light DX1 is as follows.

δε1 = δφ · cos (φx) = {cos (φx) +1} ε (8)
Since the grating pattern surface 12b is inclined by the angle ε, the incident angle δε of the diffracted light DX1 incident on the grating pattern surface 12b from the roof prism 26XA or the like is as follows.
δε = ε · cos (φx) (9)
When the diffracted light DX1 is incident on the diffraction grating 12 again at an incident angle δε, the change amount δφ1 of the diffraction angle of the + 1st order diffracted light EX1 (re-diffracted light) from the diffraction grating 12 by the diffracted light DX1 is expressed by the following equation (6). It becomes like this.

δφ1 = ε (10)
This is because the diffraction angle change amount δφ1 of the diffracted light EX1 is equal to the inclination angle ε of the grating pattern surface 12b, that is, the optical path B24 of the diffracted light EX1 is parallel to the optical path before the grating pattern surface 12b is inclined. Means. Further, no lateral shift of the optical path B24 of the diffracted light EX1 occurs. For this reason, when the interference light is generated by synthesizing the diffracted light EX1 and the reference light RX1 coaxially at the PBS surface A2, the relative tilt shift and the relative lateral shift amount between the diffracted light EX1 and the reference light RX1 are increased. Therefore, the ratio of the AC signal (beat signal or signal component) in the detection signal obtained when the interference light is photoelectrically converted does not decrease. The same applies to the -1st order diffracted light EX2 on the X axis.

  Similarly, when the grating pattern 12b of the diffraction grating 12 is tilted about an axis parallel to the X axis, the deviation of the tilt angle and the lateral shift of the optical path of the ± 1st order diffracted beams EY1 and EY2 of the Y axis do not occur. Therefore, the ratio of the beat signal among the detection signals of the photoelectric sensors 40XA to 40YB in FIG. 1 does not decrease. Therefore, the relative movement amount between the first member 6 and the second member 7 can be measured with high accuracy at a high S / N ratio using these detection signals. Note that when the grating pattern 12b of the diffraction grating 12 is tilted around an axis parallel to the X axis (or Y axis), there is substantially no influence on the X axis detection signal (or Y axis detection signal).

  In the above description, the diffraction grating 12 side is inclined with respect to the detection head 14 (interferometer units 15X and 15Y). However, the incident angles of the measurement beams MX and MY with respect to the diffraction grating 12 are from 0 to the X direction and / or Alternatively, even when a slight change is made in the Y direction, the optical path of the diffracted beams EX1 to EY2 is not inclined and laterally shifted, so that the relative relationship between the first member 6 and the second member 7 with high SN ratio and high accuracy can be obtained. The amount of movement can be measured.

  As described above, the encoder 10 (encoder device) of the present embodiment is an encoder device that measures the relative movement amount of the second member 7 that can move relative to the first member 6 in at least the X direction (first direction). is there. The encoder 10 is provided on the first member 6 and has a reflective diffraction grating 12 having a grating pattern 12a having at least the X direction as a periodic direction, and light from the laser light source 16 (light source) having different polarization states. A branch part 32X that branches into the measurement light MX and the reference lights RX1 and RX2, a PBS member 24X (first optical member) that is provided in the second member 7 and makes the measurement light MX enter the grating pattern 12a, and a second member. 7 and a diffracted light deflecting member 25X (second optical member) that causes the diffracted light EX1 and EX2 from the grating pattern 12a by the measurement light MX to enter the PBS member 24X. Then, the reference beams RX1 and RX2 that enter the PBS member 24X from the branch portion 32X and the diffracted beams EX1 and EX2 that enter the PBS member 24X from the diffracted beam deflecting member 25X are overlapped by the PBS member 24X, that is, coaxially. It is detected by combining (combining).

  Moreover, the measuring method using the encoder 10 is a method for measuring the relative movement amount between the first member 6 and the second member 7 as shown in the flowchart of FIG. The measurement light MX is incident through the PBS member 24X provided on the second member 7 substantially perpendicularly to the grating pattern surface 12b of the reflective diffraction grating 12 having the grating pattern 12a with the X direction as a periodic direction, The reference light RX1, RX2 is emitted from the diffraction grating 12 in the X direction by the measurement light MX by the step 302 for emitting the reference light RX1 substantially parallel to the grating pattern surface 12b and the first deflecting unit such as the roof prism 26XA provided on the second member 7. The + 1st order diffracted light DX1 generated with respect to is incident on the diffraction grating 12, and the + 1st order diffracted light EX1 generated from the diffraction grating 12 by the diffracted light DX1 is changed to PB The first-order diffracted light DX2 generated from the diffraction grating 12 in the X direction by the measurement light MX is caused by the step 304 to enter the member 24X and the second deflection unit such as the roof prism 26XB provided on the second member 7. 12, the step 306 in which the first-order diffracted light EX2 generated from the diffraction grating 12 by the diffracted light DX2 is incident on the PBS member 24X, and the diffracted light EX1 and EX2 and the reference light RX1 and RX2 are superimposed on the PBS member 24X. Step 308 for matching, and step 310 for detecting the interference light between the diffracted beams EX1 and EX2 and the reference beams RX1 and RX2 and determining the relative movement amount between the first member 6 and the second member 7 based on the detection result. Contains.

According to the present embodiment, the PBS member 24X that causes the measurement light MX to enter the grating pattern 12a of the diffraction grating 12 also serves as a member that superimposes the reference light RX1, RX2 and the diffracted light EX1, EX2. The system can be simplified.
Furthermore, the encoder 10 detects photoelectric sensors 40XA and 40XB (photoelectric detectors) that detect light (diffracted lights EX1 and EX2 and reference lights RX1 and RX2) superimposed by the PBS member 24X, and photoelectric sensors 40XA and 40XB. Since the measurement calculation unit 42 (measurement unit) for obtaining the relative movement amount between the first member 6 and the second member 7 using the signal is provided, the relative movement amount between the first member 6 and the second member 7 is increased. The accuracy can be obtained.

  Further, when the incident angle when the diffracted light DX1 and DX2 are incident on the diffraction grating 12 is made substantially zero by the diffracted light deflecting member 25X, the relative position between the first member 6 and the second member 7 changes. Even if the relative height (position in the Z direction) of the grating pattern surface 12b of the diffraction grating 12 with respect to the PBS member 24X (detection head 14) changes, the diffracted light from the diffraction grating 12 by the diffracted lights DX1 and DX2 The optical path fluctuations of EX1 and EX2 (re-diffracted light) are almost eliminated, and the relative shift amount in the lateral direction between the diffracted lights EX1 and EX2 and the reference lights RX1 and RX2 becomes almost zero. Therefore, the intensity of the beat signal (signal including position information) of the interference light is not reduced with respect to the change in the height of the grating pattern surface 12b of the diffraction grating 12, and the relative movement between the first member 6 and the second member 7 is eliminated. High measurement accuracy of quantity can be maintained. Further, if the relative positions of the first member 6 and the second member 7 in the X direction and the Y direction are fixed, the Z of the first member 6 and the second member 7 is detected from the detection signal of the photoelectric sensor 40XA. The relative movement amount in the direction can be measured.

  Further, the encoder 10 causes the measurement light MY to enter the diffraction grating 12 vertically (substantially perpendicularly) by the PBS member 24Y, and the ± first-order diffracted lights DY1 and DY2 generated in the Y direction by the measurement light MY from the diffraction grating 12 enter. Reflecting portions 25YA and 25YB incident on the diffraction grating 12 with an angle of approximately 0, and interference light between the ± first-order diffracted lights EY1 and EX2 and the reference lights RY1 and RY2 generated by the diffracted lights DY1 and DY2 from the diffraction grating 12 are detected. Photoelectric sensors 40YA and 40YB. Therefore, even if the relative height of the grating pattern surface 12b of the diffraction grating 12 changes, the relative movement amount in the Y direction between the first member 6 and the second member 7 from the detection signals of the photoelectric sensors 40YA and 40YB. Can be measured with high accuracy.

Further, a step is provided by the additional member 28XA on the incident surface of the diffracted light DX1 and EX1 of the roof prism 26XA (first deflection unit), and a step is provided on the reflection surfaces of the members 30XA and 30XB of the reflection member 30X. The incident position of the diffracted light EX1 on the PBS surface A11 can be controlled with high accuracy.
In the above embodiment, the following modifications are possible.

In the above-described embodiment, the two-dimensional diffraction grating 12 is used. However, a one-dimensional diffraction grating having periodicity only in the X direction may be used instead of the diffraction grating 12. In this case, the Y-axis interferometer unit 15Y and the photoelectric sensors 40YA and 40YB are omitted from the detection head 14, and the X of the first member 6 and the second member 7 is detected using the detection signals of the photoelectric sensors 40XA and 40XB. The relative movement amount in the direction and the Z direction can be measured. Further, the periodic direction (pitch direction) of the diffraction grating may be non-parallel to the X direction or the Y direction. For example, the direction may be a direction in which the periodic direction forms 45 degrees with respect to the X direction, or a direction inclined by several mrad with respect to the X direction or the Y direction.
Further, the diffracted lights DX1 and DX2 generated by the first diffraction from the diffraction grating 12 may be detected by being superimposed on the reference lights RX1 and RX2, respectively.

  In the above embodiment, the interference light between the diffracted lights EX1 to EY2 and the reference lights RX1 to RY2 is detected. For example, the + first-order diffracted light EX1 and the second diffracted light EX1 of the measurement light having the first frequency on the X axis are detected. Interfering light of frequency measuring light (light used as reference light in the above embodiment) with −1st order diffracted light EX2, and + 1st order diffracted light EY1 and second light of measuring light having a first frequency on the Y axis You may detect the interference light with -1st order diffracted light EY2 of the frequency measurement light. In this case, the relative movement amount in the X direction and the Y direction between the first member 6 and the second member 7 can be measured, and even if the relative height of the grating pattern surface 12b of the diffraction grating 12 varies, Since there is no lateral shift of the two diffracted lights, measurement can be performed with high SN ratio and high accuracy at all times.

  Next, in the above embodiment, the diffracted lights DX1 and EX1 generated from the diffraction grating 12 are incident on the reflecting members 28XA and 30XA via the roof prism 26XA, respectively. However, as shown in the main part of the X-axis interferometer 15XA in the modification of FIG. 5A, a roof mirror 44XA having orthogonal reflecting surfaces A33 and A34 instead of the roof prism 26XA (FIG. 5B )) And a wedge prism 46XA having an apex angle α3. In this case, a roof mirror 44XB and a wedge prism 46XB may be used instead of the roof prism 26XB. Further, instead of the reflecting member 30X, four right-angle prism side reflecting members 47XA, 47XB and 48XA, 48XB may be used. By using the roof mirrors 44XA and 44XB, the diffracted light deflection member 25XA of the interferometer unit 15XA may be reduced in weight. The wedge prisms 46XA and 46XB may be omitted. Similarly, a plane mirror may be used as the reflecting members 28XA and 30XA.

In the above-described embodiment, the reflection surface A18 (third surface) of the reflection member 30X and the reflection surface A24 of the roof prism 26XB with respect to the surface including the Y direction (second direction) orthogonal to the X direction (first direction). (5th reflective surface) may be arrange | positioned on the opposite side mutually.
Further, the reflecting surface A16 (seventh reflecting surface) and the reflecting surface A26 (eighth reflecting surface) of the reflecting member 30X may be arranged along the Y direction.
Further, as shown in FIG. 6B, the position where the measurement light MX is incident and the position where the diffracted lights DX1 and DX2 are incident on the lattice pattern 12a are on a straight line along the Y direction (non-measurement direction). May be.

  Hereinafter, a description will be given with reference to FIGS. 6 and 7. FIG. 6A is a diagram showing the PBS member 24XB and the diffracted light deflection member 25XB of the interferometer unit 15X in FIG. FIG. 6B is a diagram showing a position where the measurement light MX is incident on the grating pattern 12a and a position where the diffracted lights DX1 and DX2 are incident. FIG. 7A is a top view of FIG. 6A, and FIG. 7B is a side view of FIG. 6A. 6 and 7, members having the same functions as those in FIGS. 1 to 5 are denoted by the same reference numerals.

  6A, the PBS member 24XB includes a PBS surface A11 inclined at 45 ° around the X axis with respect to the XY plane, two surfaces parallel to the XY surface, and two surfaces parallel to the YZ surface, It is a quadrangular prism shape surrounded by five planes, one plane parallel to the ZX plane. The roof prism 26XA of the diffracted light deflecting member 25XB and the loop prism 26XB of the diffracted light deflecting member 25XB have the same configuration as that of the first embodiment shown in FIGS.

  Hereinafter, the optical path will be described with reference to FIGS. 6 (A), 7 (A), and 7 (B). The measurement light MX emitted from the branch part 32X shown in FIG. 1 is incident on the PBS surface A11 in the -Y direction as S-polarized light with respect to the PBS surface A11, and is reflected in the -Z direction by the PBS surface A11. Incident perpendicularly (parallel to the Z axis) to the grating pattern surface 12b (grating pattern 12a) of the diffraction grating 12X. On the other hand, the reference beams RX1 and RX2 emitted from the branching section 32X are incident on the PBS surface A11 in the approximately −Y direction as P-polarized light with respect to the PBS surface A11 and are transmitted through the PBS surface A11. Here, as in the first embodiment, the measurement light MX is, for example, 0.5 to 1.5 ° in the X direction (θy direction) and / or the Y direction (θx direction) with respect to an axis parallel to the Z axis. It may be tilted to a certain extent and enter the grating pattern surface 12b substantially perpendicularly.

  In this example, ± first-order diffracted lights DX1 and DX2 are generated symmetrically in the X direction by the measurement light MX incident on the grating pattern surface 12b of the diffraction grating 12 vertically. The generated diffracted light DX1 enters the incident surface of the roof prism 26XA, and the diffracted light DX2 enters the incident surface of the roof prism 26XB. The + 1st-order diffracted light DX1 is shifted in the + Y direction via the incident surface A12 and the reflective surfaces A13 and A14 of the roof prism 26XA, and is directed to the -X direction parallel to the X axis via the exit surface A15 and the reflecting member. Incident on 50X.

  The reflecting member 50X includes a V-shaped reflecting member 51X having reflecting surfaces A31 and A41 orthogonal to each other, and a parallel flat plate-like reflecting member that is in contact with a part of the reflecting surface A31 of the reflecting member 51X and has a reflecting surface A32. It has a member 51XA and a parallel flat plate-like reflecting member 51XB that abuts a part of the reflecting surface A41 of the reflecting member 51X and has a reflecting surface A42. Here, the ridge lines of the two reflection surfaces A31 and A41 of the reflection member 50X are directed to the −Z direction side, and each reflection surface A31 and A41 is inclined at an angle of ± 45 degrees with respect to the XY plane.

  The diffracted light DX1 reflected by the reflecting surface A31 of the reflecting member 51X passes through the + Y direction side of the PBS member 24XB and enters the grating pattern surface 12b of the diffraction grating 12 substantially perpendicularly. Further, the −1st order diffracted light DX2 is shifted in the −Y direction via the reflecting surfaces A23, A24, etc. of the roof prism 26XB, and is incident on the reflecting member 51X in the + X direction parallel to the X axis. The diffracted light DX2 reflected by the 51X reflecting surface A41 passes through the −Y direction side of the PBS surface A11 of the PBS member 24XB and is incident on the grating pattern 12a of the diffraction grating 12 substantially perpendicularly.

  As shown in FIG. 2B, the position where the diffracted lights DX1 and DX2 are incident is shifted symmetrically in the Y direction by the interval b1 with respect to the position where the measurement light MX is incident on the grating pattern 12a. The interval b1 is approximately 1/3 of the width of the PBS member 24X in the Y direction. By making the measurement light MX and the diffracted lights DX1 and DX2 enter the diffraction grating 12 with such an arrangement, the configuration of the interferometer unit 15X can be reduced in size. However, the interval b1 is arbitrary. The incident positions of the diffracted beams DX1 and DX2 may be arranged so that the incident position of the measuring beam MX is substantially sandwiched in the Y direction.

  The diffracted lights DX1 and DX2 reflected by the reflecting member 51X generate + 1st order diffracted light EX1 and −1st order diffracted light EX2 (rediffracted light) symmetrically in the X direction from the diffraction grating 12, and the generated diffracted light EX1 is the roof prism. The light beam is shifted in the −Y direction via the incident surface A12 of 26XA and the reflecting surfaces A14 and A13, and is incident on the reflecting member 51XA in the −X direction parallel to the X axis. Then, the S-polarized diffracted light EX1 reflected by the reflecting surface A32 of the reflecting member 51XA is reflected by the PBS surface A11 of the PBS member 24XB and is emitted from the PBS member 24XB substantially in the −Y direction. The diffracted light EX2 is shifted in the + Y direction via the incident surface of the roof prism 26XB and the reflecting surfaces A23 and A24, and is incident on the reflecting member 51XB in the + X direction parallel to the X axis. Then, the S-polarized diffracted light EX2 reflected by the reflecting surface A42 of the reflecting member 51XB is reflected by the PBS surface A11 and is emitted from the PBS member 24X substantially in the −Y direction.

Here, the diffracted light EX1 is superimposed on the first reference light RX1 (synthesized or combined coaxially) and emitted from the PBS member 24XB in the −Y direction. In contrast to this, the diffracted light EX2 is superimposed on the second reference light RX2 (synthesized or combined coaxially) and emitted from the PBS member 24XB in the −Y direction.
Since the diffracted beams EX1 and EX2 and the first and second reference beams WX1 and RX2 emitted from the PBS member 24XB travel on the same optical paths as those in the first embodiment, the description thereof is omitted here.

In the example of FIGS. 6 and 7 as well, the PBS member 24XB that makes the measurement light MX enter the grating pattern 12a of the diffraction grating 12 also serves as a member that superimposes the reference light RX1, RX2 and the diffracted lights EX1, EX2. Therefore, the optical system can be simplified.
In addition, since the position where the measurement light MX is incident and the position where the diffracted lights DX1 and DX2 are incident are the same position in the measurement direction (X direction), the measurement accuracy due to the surface accuracy of the grating pattern surface of the diffraction grating 12 Can be reduced.

In addition, instead of the reflecting member 50X in the example of FIGS. 6 and 7, the reflecting member may be configured by three prism-shaped members each having two surface reflecting surfaces that are orthogonal to each other. In this case, two small prism members are arranged across the largest prism member among the three prism-shaped members.
6 and 7, similar to the first embodiment, parallel plate-shaped additional members 28XA and 28XB are provided that are fixed so as to cover the half surface in the −Y direction of the bottom surface of the roof prisms 26XA and 26XB. It is good also as a structure.

[Second Embodiment]
A second embodiment of the present invention will be described with reference to FIGS. FIG. 8 shows a schematic configuration of an exposure apparatus EX including the encoder apparatus according to this embodiment. The exposure apparatus EX is a scanning exposure type projection exposure apparatus composed of a scanning stepper. The exposure apparatus EX includes a projection optical system PL (projection unit PU). Hereinafter, the Z-axis is parallel to the optical axis AX of the projection optical system PL, and a plane orthogonal to the Z-axis (a plane substantially parallel to the horizontal plane). In the following description, the Y axis is taken in the direction in which the reticle R and the wafer W are relatively scanned, and the X axis is taken in the direction perpendicular to the Z axis and the Y axis.

  The exposure apparatus EX includes an illumination system 110 disclosed in, for example, US Patent Application Publication No. 2003/0025890, and illumination light (exposure light) IL (for example, an ArF excimer laser having a wavelength of 193 nm) from the illumination system 110 A reticle stage RST that holds a reticle R (mask) illuminated by light, a harmonic of a solid-state laser (such as a semiconductor laser). Further, the exposure apparatus EX includes a projection unit PU including a projection optical system PL that projects the illumination light IL emitted from the reticle R onto the wafer W (substrate), a stage apparatus 195 including a wafer stage WST that holds the wafer W, and A control system or the like (see FIG. 10) is provided.

  The reticle R is held on the upper surface of the reticle stage RST by vacuum suction or the like, and a circuit pattern or the like is formed on the pattern surface (lower surface) of the reticle R. The reticle stage RST can be driven minutely in the XY plane by the reticle stage drive system 111 of FIG. 10 including, for example, a linear motor or the like, and can be driven at a scanning speed specified in the scanning direction (Y direction).

  Position information in the moving plane of the reticle stage RST (including the position in the X direction, the Y direction, and the rotation angle in the θz direction) is transferred to the moving mirror 115 (or mirror-finished) by the reticle interferometer 116 including a laser interferometer. For example, it is always detected with a resolution of about 0.5 to 0.1 nm via the stage end face. The measurement value of reticle interferometer 116 is sent to main controller 120 formed of a computer shown in FIG. Main controller 120 controls reticle stage drive system 111 based on the measurement value, thereby controlling the position and speed of reticle stage RST.

  In FIG. 8, the projection unit PU disposed below the reticle stage RST includes a lens barrel 140 and a projection optical system PL having a plurality of optical elements held in a predetermined positional relationship within the lens barrel 140. The projection optical system PL is, for example, telecentric on both sides and has a predetermined projection magnification β (for example, a reduction magnification of 1/4 times, 1/5 times, etc.). When the illumination area IAR of the reticle R is illuminated by the illumination light IL from the illumination system 110, an image of the circuit pattern of the reticle R in the illumination area IAR via the projection optical system PL by the illumination light IL that has passed through the reticle R. Are formed in an exposure area IA (an area conjugate to the illumination area IAR) of one shot area of the wafer (semiconductor wafer) W.

  In addition, since the exposure apparatus EX performs exposure using the liquid immersion method, the lower end of the lens barrel 140 that holds the tip lens 191 that is an optical element on the most image plane side (wafer W side) constituting the projection optical system PL is used. A nozzle unit 132 constituting a part of the local liquid immersion device 108 is provided so as to surround the periphery of the part. The nozzle unit 132 is connected to a liquid supply device 186 and a liquid recovery device 189 (see FIG. 10) via a supply tube 131A and a recovery tube 131B for supplying an exposure liquid Lq (for example, pure water). . If the immersion type exposure apparatus is not used, the local immersion apparatus 108 may not be provided.

  Wafer stage WST is supported in a non-contact manner on upper surface 112a parallel to the XY plane of base board 112 via a plurality of, for example, vacuum preload type static air bearings (air pads) (not shown). Wafer stage WST can be driven in the X and Y directions by a stage drive system 124 (see FIG. 10) including, for example, a planar motor or two sets of orthogonal linear motors. The exposure apparatus EX includes an aerial image measurement system (not shown) for aligning the reticle R, an alignment system AL (see FIG. 8) for aligning the wafer W, an irradiation system 90a, and a light receiving system 90b. An oblique incidence type multi-point autofocus sensor 90 (see FIG. 10) for measuring the Z position of the location, and an encoder device 8B for measuring position information of the wafer stage WST are provided.

  Wafer stage WST is provided in stage main body 191, stage main body 191 driven in X and Y directions, wafer table WTB mounted on stage main body 191, and wafer table WTB (wafer for stage main body 191). And a Z / leveling mechanism that relatively finely drives the position of W) in the Z direction and the tilt angle in the θx direction and the θy direction. A wafer holder (not shown) that holds the wafer W on a suction surface substantially parallel to the XY plane by vacuum suction or the like is provided at the upper center of the wafer table WTB.

In addition, the upper surface of wafer table WTB has a surface (or a protective member) that has been subjected to a liquid repellency treatment with respect to liquid Lq and is substantially flush with the surface of the wafer placed on the wafer holder. A flat plate member 128 having a high flatness is provided in which a circular opening is formed in the center of the rectangular shape and a circular opening that is slightly larger than the wafer holder (wafer mounting region).
In the configuration of the so-called immersion type exposure apparatus provided with the above-mentioned local immersion apparatus 108, the plate body 128 is further shown in the plan view of the wafer table WTB (wafer stage WST) in FIG. In addition, a plate portion (liquid repellent plate) 128a surrounding the circular opening and having a liquid repellent treatment on a surface having a rectangular outer shape (outline), and a peripheral portion 128e surrounding the plate portion 128a. A pair of two-dimensional diffraction gratings 12A and 12B elongated in the X direction so as to sandwich the plate portion 128a in the Y direction is disposed on the upper surface of the peripheral portion 128e, and elongated in the Y direction so as to sandwich the plate portion 128a in the X direction. A pair of two-dimensional diffraction gratings 12C and 12D are arranged. The diffraction gratings 12 </ b> A to 12 </ b> D are reflection type diffraction gratings in which a two-dimensional grating pattern having a periodic direction in the X direction and the Y direction is formed as in the diffraction grating 12 of FIG. 1.

  In FIG. 8, a flat measurement frame 150 substantially parallel to the XY plane is supported on a frame (not shown) that supports the projection unit PU via a connecting member (not shown). A plurality of detection heads 14 having the same configuration as the triaxial detection head 14 in FIG. 1 are fixed to the bottom surface of the measurement frame 150 so as to sandwich the projection optical system PL in the X direction, and the projection optical system PL is sandwiched in the Y direction. As described above, a plurality of detection heads 14 having the same configuration as the detection head 14 of FIG. 1 are fixed (see FIG. 7). Further, one or a plurality of laser light sources (not shown) similar to the laser light source 16 of FIG. 1 for supplying laser light (measurement light and reference light) to the plurality of detection heads 14 are also provided.

  In FIG. 9, during the period in which the wafer W is exposed with the illumination light from the projection optical system PL, any two of the plurality of detection heads 14 in one row A1 in the Y direction always face the diffraction gratings 12A and 12B. Any two of the plurality of detection heads 14 in one row A2 in the X direction are configured to face the diffraction gratings 12C and 12D. Each of the detection heads 14 in the row A1 irradiates the diffraction grating 12A or 12B with measurement light, and a corresponding measurement calculation unit 42 ( (See FIG. 10). In these measurement calculation units 42, as in the measurement calculation unit 42 in FIG. 1, the relative positions (relative movement amounts) of the wafer stage WST and the measurement frame 150 in the X direction, the Y direction, and the Z direction are set to 0.5 to, for example. Each measurement value is obtained with a resolution of 0.1 nm and supplied to the switching unit 80A. In the measurement value switching unit 80A, information on the relative position supplied from the measurement calculation unit 42 corresponding to the detection head 14 facing the diffraction gratings 12A and 12B is supplied to the main controller 120.

  Each detection head 14 corresponding to one row A2 irradiates the diffraction grating 12C or 12D with measurement light, and performs a measurement calculation corresponding to a detection signal of interference light between the diffraction light generated from the diffraction gratings 12C and 12D and the reference light. It supplies to the part 42 (refer FIG. 10). In these measurement calculation units 42, as in the measurement calculation unit 42 in FIG. 1, the relative positions (relative movement amounts) of the wafer stage WST and the measurement frame 150 in the X direction, the Y direction, and the Z direction are set to 0.5 to, for example. Obtained with a resolution of 0.1 nm and supplied to the measured value switching unit 80B. In the measurement value switching unit 80B, information on the relative position supplied from the measurement calculation unit 42 corresponding to the detection head 14 facing the diffraction gratings 12C and 12D is supplied to the main controller 120.

  A plurality of detection heads 14 in one row A1, a laser light source (not shown), a measurement calculation unit 42, and diffraction gratings 12A and 12B constitute a three-axis encoder 10A. The plurality of detection heads 14 in one row A2 and the laser light source (Not shown), the measurement calculation unit 42, and the diffraction gratings 12C and 12D constitute a three-axis encoder 10B. The encoder device 8B is composed of the three-axis encoders 10A and 10B and the measurement value switching units 80A and 80B. Based on the information on the relative position supplied from encoder device 8B, main controller 120 determines the position of wafer stage WST relative to measurement frame 150 (projection optical system PL) in the X, Y, and Z directions, and in the θz direction. Information such as the rotation angle is obtained, and wafer stage WST is driven via stage drive system 124 based on this information.

  Then, at the time of exposure by the exposure apparatus EX, alignment of the reticle R and the wafer W is first performed. Thereafter, irradiation of the reticle R with the illumination light IL is started, and an image of a part of the pattern of the reticle R is projected onto one shot area on the surface of the wafer W via the projection optical system PL, while the reticle stage RST. The pattern image of the reticle R is transferred to the shot area by a scanning exposure operation that moves the wafer stage WST in synchronization with the Y direction using the projection magnification β of the projection optical system PL as a speed ratio (synchronous scanning). Thereafter, by repeating the step movement of the wafer W in the X and Y directions via the wafer stage WST and the scanning exposure operation described above, the entire wafer W is immersed by the immersion method and the step-and-scan method. The pattern image of the reticle R is transferred to the shot area.

  At this time, in the detection head 14 of the encoder device 8B, since the optical path lengths of the measurement light and the diffracted light are shorter than those of the laser interferometer, the influence of the air fluctuation on the measurement value using the detection head 14 is very small. Accordingly, the encoder device 8B of the present embodiment has much better measurement stability (short-term stability) in a short period of time when the air fluctuates than the laser interferometer. Can be transferred to W with high accuracy. Furthermore, since the detection head 14 can always detect a signal including the upper portion of the relative movement amount with a high SN ratio even if the Z positions of the diffraction gratings 12A to 12D change, the wafer stage WST can always be driven with high accuracy.

  In the present embodiment, the detection head 14 is arranged on the measurement frame 150 side, and the diffraction gratings 12A to 12D are arranged on the wafer stage WST side. As another configuration, the diffraction gratings 12A to 12D may be arranged on the measurement frame 150 side, and the detection head 14 may be arranged on the wafer stage WST side. Alternatively, diffraction gratings 12A to 12D may be arranged on the back surface of wafer stage WST, and detection head 14 may be arranged on the surface plate side of wafer stage WST.

Further, when the position information of reticle stage RST is obtained, the encoder described in this embodiment may be used instead of or in combination with reticle interferometer 116.
Further, when an electronic device (or microdevice) such as a semiconductor device is manufactured using the exposure apparatus EX or the exposure method of the above embodiment, the electronic device has a function / performance design of the electronic device as shown in FIG. Step 221 for performing a step, Step 222 for fabricating a reticle (mask) based on this design step, Step 223 for fabricating a substrate (wafer) as a base material of the device and applying a resist, and the exposure apparatus ( Substrate processing step 224 including a step of exposing a reticle pattern to a substrate (photosensitive substrate) by an exposure method), a step of developing the exposed substrate, a heating (curing) and etching step of the developed substrate, and a device assembly step (dicing) (Including processing processes such as processes, bonding processes, and packaging processes) 22 And an inspection step 226, and the like.

  In other words, this device manufacturing method includes a lithography process in which an image of a reticle pattern is transferred to a substrate (wafer) using the exposure apparatus EX (exposure method) of the above embodiment, and the pattern is developed. And a step (such as etching in step 224) of processing the substrate on which the image is transferred on the basis of the image of the pattern. At this time, according to the above-described embodiment, the position of wafer stage WST of the exposure apparatus can be controlled with high accuracy, so that an electronic device can be manufactured with high accuracy.

In the first embodiment described above, the reflecting member 30X is made of a V-shaped reflecting member having reflecting surfaces orthogonal to each other, and two parallel members that are in contact with a part of the reflecting surface of the reflecting member and have a surface reflecting surface. You may comprise with a flat plate-shaped reflective member.
In addition, the encoder 10 of the above-described embodiment moves an optical system for an object to be inspected or processed (such as an optical system for condensing laser light) such as an inspection apparatus or a measurement apparatus other than the exposure apparatus, and the object. In an optical device provided with a moving device (such as a stage), the present invention can be applied to measure the relative movement amount of the moving device (object) with respect to the optical system, for example. The present invention can also be applied to measure the amount of movement of a workpiece in an NC machine tool that includes a moving device (such as a stage) that moves the workpiece.

In the above embodiment, a step-and-scan projection exposure apparatus is described as an example. However, the present invention is also applied to an encoder of a step-and-repeat projection exposure apparatus. Can do.
The illumination light IL is not limited to ArF excimer laser light (wavelength 193 nm), but may be ultraviolet light such as KrF excimer laser light (wavelength 248 nm) or vacuum ultraviolet light such as F ₂ laser light (wavelength 157 nm). good. For example, as disclosed in US Pat. No. 7,023,610, single-wavelength laser light in the infrared region or visible region oscillated from a DFB semiconductor laser or fiber laser is used as vacuum ultraviolet light, for example, erbium. A harmonic which is amplified by a fiber amplifier doped with (or both erbium and ytterbium) and wavelength-converted into ultraviolet light using a nonlinear optical crystal may be used.

The above-described embodiment can also be applied to an exposure apparatus that uses a charged particle beam such as an electron beam or an ion beam.
In the above-described embodiment, a light transmission mask (reticle) in which a predetermined light-shielding pattern (or phase pattern / dimming pattern) is formed on a light-transmitting substrate is used. Instead of this reticle, For example, as disclosed in US Pat. No. 6,778,257, an electronic mask (variable shaping mask, which forms a transmission pattern, a reflection pattern, or a light emission pattern based on electronic data of a pattern to be exposed, as disclosed in US Pat. No. 6,778,257. For example, a non-light emitting image display element (spatial light modulator) including a DMD (Digital Micro-mirror Device) may be used.

Further, as disclosed in, for example, US Pat. No. 6,611,316, two reticle patterns are synthesized on a wafer via a projection optical system, and 1 on the wafer by one scan exposure. The above embodiment can also be applied to an exposure apparatus that performs double exposure of two shot areas almost simultaneously.
In the above embodiment, the object on which the pattern is to be formed (the object to be exposed to which the energy beam is irradiated) is not limited to the wafer, but may be another object such as a glass plate, a ceramic substrate, a film member, or a mask blank. good.

  The use of the exposure apparatus is not limited to the exposure apparatus for semiconductor manufacturing, but for example, an exposure apparatus for liquid crystal that transfers a liquid crystal display element pattern to a square glass plate, an organic EL, a thin film magnetic head, an image sensor (CCD, etc.), micromachines, DNA chips and the like can also be widely applied to exposure apparatuses. Further, in order to manufacture reticles or masks used in not only microdevices such as semiconductor elements but also light exposure apparatuses, EUV exposure apparatuses, X-ray exposure apparatuses, electron beam exposure apparatuses, etc., glass substrates or silicon wafers, etc. The above embodiment can also be applied to an exposure apparatus that transfers a circuit pattern.

  In addition, this invention is not limited to the above-mentioned embodiment, Of course, a various structure can be taken in the range which does not deviate from the summary of this invention.

  EX ... exposure apparatus, R ... reticle, W ... wafer, MX, MY ... measurement light, DX1, DY1, EX1, EY1 ... + 1st order diffracted light, DX2, DY2, EX2, EY2 ... -1st order diffracted light, 6 ... first member 7 ... second member, 10 ... encoder, 12 ... two-dimensional diffraction grating, 14 ... detection head, 16 ... laser light source, 24X, 24Y ... PBS (polarization beam splitter) member, 25X, 25Y ... diffracted light deflecting member, 26XA, 26XB, 26YA, 26YB ... roof prism, 40XA, 40XB, 40YA, 40YB, 40C ... photoelectric sensor, 42 ... measurement calculation unit

Claims (22)

An encoder device for measuring a relative movement amount of a first member and a second member that can move relative to each other in a first direction,
A reflective diffraction grating provided on the first member and having a grating pattern in which the first direction is a periodic direction;
A branching unit that branches light from the light source into measurement light and reference light having different polarization states;
A first optical member provided on the second member for allowing the measurement light to enter the grating pattern of the diffraction grating;
A second optical member that is provided on the second member and causes the diffracted light from the grating pattern by the measurement light to be incident on the first optical member;
With
The first optical member in a state in which the reference light incident on the first optical member from the branch portion and the diffracted light incident on the first optical member from the second optical member are at least partially overlapped with each other. An encoder device characterized by being injected from   The second optical member includes a first deflection unit configured to deflect a first-order diffracted light of a predetermined order out of the diffracted light from the grating pattern by the measurement light and to enter the first optical member; 2. The apparatus according to claim 1, further comprising: a second deflecting unit that deflects second diffracted light having a different order from the first diffracted light out of the diffracted light from the grating pattern and causes the second diffracted light to enter the first optical member. The encoder device described. The branching unit causes the first reference light and the second reference light branched from the reference light to enter the first optical member,
The first reference light incident on the first optical member is superimposed on the first diffracted light from the first deflecting unit,
The encoder apparatus according to claim 2, wherein the second reference light incident on the first optical member is superimposed on the second diffracted light from the second deflecting unit. The light source supplies the measurement light and the reference light in different polarization states to the branching unit as a light beam in a state where at least part of the measurement light and the reference light overlap each other.
The branch unit includes a separation surface that separates the measurement light and the reference light from the light beam, and a branch surface that branches the first reference light and the second reference light from the reference light separated by the separation surface. The encoder device according to claim 2, wherein the encoder device includes:   The first optical member is provided at a position where the reference light incident on the first optical member from the branch portion and the diffracted light incident on the first optical member from the second optical member are overlapped. The encoder device according to any one of claims 1 to 4, further comprising a first surface. The measurement light incident on the grating pattern from the first optical member is incident on the grating pattern again after being diffracted by the grating pattern,
The said 2nd optical member injects into the said 1st optical member the said measurement light which entered into the said grating pattern again and was diffracted by the said grating pattern, The 1st to 5 characterized by the above-mentioned. The encoder device described.   The second optical member has an order of the first diffracted light of a predetermined order out of the diffracted light from the grating pattern by the measurement light and the order of the first diffracted light from the diffracted light from the grating pattern by the measurement light. Differently diffracted second diffracted light is incident on a position shifted in the first direction and in a direction perpendicular to the first direction with respect to the incident position of the measurement light with respect to the grating pattern surface of the diffraction grating. The encoder device according to claim 6, wherein The first optical member causes the measurement light to enter the diffraction grating perpendicularly,
The encoder apparatus according to claim 7, wherein the second optical member causes the first and second diffracted beams to enter the diffraction grating perpendicularly. The second optical member includes a first deflecting unit configured to deflect a first-order diffracted light of a predetermined order out of the diffracted light from the grating pattern by the measurement light and to enter the first optical member; and the first measurement light A second deflecting unit that deflects the second diffracted light having a different order from the first diffracted light out of the diffracted light from the grating pattern according to, and enters the first optical member;
The first deflecting unit includes first and second reflecting surfaces that are orthogonal to each other, and a third reflecting surface that causes the first diffracted light to enter the diffraction grating via the first and second reflecting surfaces. ,
The second deflecting unit includes fourth and fifth reflecting surfaces orthogonal to each other, and a sixth reflecting surface that causes the second diffracted light incident on the diffraction grating to enter the diffraction grating via the fourth and fifth reflecting surfaces. ,
The measurement light from the third reflecting surface diffracted by the diffraction grating is incident on the first optical member via the first and second reflecting surfaces and is diffracted by the diffraction grating. The encoder apparatus according to any one of claims 1 to 8, wherein the measurement light from a surface is incident on the first optical member via the fourth and fifth reflecting surfaces.   2. The ridge line of the first and second reflection surfaces and the ridge line of the fourth and fifth reflection surfaces are located in a plane including a second direction orthogonal to the first direction. The encoder device according to any one of claims 9 to 9. The diffraction grating is a two-dimensional reflection type diffraction grating whose periodic direction is the first direction and a second direction orthogonal to the first direction;
A branching unit for the second direction that splits the light from the light source into the measurement light for the second direction and the reference light for the second direction having different polarization states;
A third optical member that is provided on the second member and makes the measurement light for the second direction incident on the grating pattern of the diffraction grating;
A fourth optical member that is provided on the second member and causes the diffracted light from the grating pattern by the measurement light for the second direction to enter the third optical member;
Further comprising
The reference light for the second direction that enters the third optical member from the branch portion for the second direction and the diffracted light that enters the third optical member from the fourth optical member are the third The encoder device according to any one of claims 1 to 9, wherein the encoder device is overlapped with an optical member. An encoder device for measuring a relative movement amount of a first member and a second member that can move relative to each other in a first direction,
A reflective diffraction grating provided on the first member and having a grating pattern in which the first direction is a periodic direction;
A branching unit for branching light from a light source into first and second reference lights having different polarization states of the measurement light and the measurement light;
A first optical member provided on the second member for allowing the measurement light to enter the grating pattern of the diffraction grating;
A first deflecting portion provided on the second member for deflecting a first-order diffracted light of a predetermined order out of the diffracted light from the grating pattern by the measurement light; A second optical member provided with a second deflecting unit for deflecting second diffracted light having a different order from the first diffracted light;
With
The first diffracted light re-enters the grating pattern through the first deflecting unit, is diffracted by the grating pattern, and re-enters the first deflecting unit.
The second diffracted light re-enters the grating pattern through the second deflection unit, is diffracted by the grating pattern, and re-enters the second deflection unit.
The first and second reference lights from the branch part are incident on the first optical member,
The first diffracted light re-entering the first deflecting unit is superimposed on the first reference light by the first optical member,
The encoder apparatus according to claim 1, wherein the second diffracted light re-entering the second deflecting unit is superposed on the second reference light by the first optical member. The first deflecting unit includes first and second reflecting surfaces that are orthogonal to each other, and a third reflecting surface that causes the first diffracted light to enter the diffraction grating via the first and second reflecting surfaces. ,
The second deflecting unit includes fourth and fifth reflecting surfaces orthogonal to each other, and a sixth reflecting surface that causes the second diffracted light incident on the diffraction grating to enter the diffraction grating via the fourth and fifth reflecting surfaces. ,
Measurement light from the third reflecting surface diffracted by the diffraction grating is incident on the first optical member via the first and second reflecting surfaces, and is diffracted by the diffraction grating. The encoder device according to claim 12, wherein measurement light from the light enters the first optical member via the fourth and fifth reflecting surfaces. The first deflecting unit includes a seventh reflecting surface that makes the first diffracted light incident on the first optical member through the first and second reflecting surfaces,
The encoder device according to claim 13, wherein the second deflecting unit includes an eighth reflecting surface that causes the second diffracted light that has passed through the fourth and fifth reflecting surfaces to enter the first optical member. .   The third and sixth reflecting surfaces and the seventh and eighth reflecting surfaces are arranged on opposite sides of a surface including a second direction orthogonal to the first direction. The encoder device described in 1.   The encoder device according to claim 14, wherein the third reflection surface and the fifth reflection surface are arranged on opposite sides with respect to a surface including a second direction orthogonal to the first direction.   The encoder device according to claim 16, wherein the seventh and eighth reflecting surfaces are disposed along the second direction. An exposure apparatus that exposes a pattern onto an object to be exposed,
Frame,
A stage that supports the object to be exposed and is relatively movable in at least a first direction with respect to the frame;
An exposure apparatus comprising: the encoder device according to any one of claims 1 to 17 for measuring a relative movement amount of at least the frame and the stage in the first direction. A method for measuring a relative movement amount between a first member and a second member that can move relative to each other in a first direction,
Emitting measurement light and reference light having different polarization states; and
Making the measurement light incident on a grating pattern of a reflective diffraction grating provided on the first member via an optical member provided on the second member;
Generating diffracted light from the grating pattern by the measurement light;
Making the diffracted light generated from the grating pattern incident on the optical member;
Making the reference light incident on the optical member;
Emitting from the optical member in a state in which the reference light and the diffracted light are at least partially overlapped;
A measurement method comprising: An exposure method for exposing a pattern to an object to be exposed supported on a stage that can move relative to a frame in at least a first direction,
An exposure method using the measurement method according to claim 19 in order to measure a relative movement amount of the frame and the stage at least in the first direction. A device manufacturing method including a lithography process,
19. A device manufacturing method comprising exposing an object using the exposure apparatus according to claim 18 in the lithography process. A device manufacturing method including a lithography process,
21. A device manufacturing method, comprising: exposing an object using the exposure method according to claim 20 in the lithography process.

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