JP2013234997A - Encoder device, optical device and exposure device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress reduction in signal intensity of interference light with respect to a height change of a grating pattern surface when measuring by use of a diffraction grating.SOLUTION: An encoder measuring a relative movement amount of a first member 6 and a second member 7 comprises: a diffraction grating 12 that is provided at the first member 6; a polarizing beam splitter (PBS) member 24X that is provided at the second member 7 and allows measurement light MX to enter the diffraction grating 12 almost vertically; and reflection parts 25XA and 25XB that are provided so as to interpose the PBS member 24X therebetween and be displaced in a Y direction, allow diffraction light beams DX1 and DX2 generated from the diffraction grating 12 to enter the diffraction grating 12 and allow diffraction light beams EX1 and EX2 generated from the diffraction grating 12 to enter the PBS member 24X. Thus, interference light beams of the diffraction light beams EX1 and EX2 and reference light beams are detected.

Description

  The present invention relates to an encoder apparatus for measuring a relative movement amount between relatively moving members, an optical apparatus and an exposure apparatus including the encoder apparatus, and a device manufacturing method using the exposure apparatus.

  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, from a detection signal obtained by irradiating the diffraction grating fixed to the stage with measurement light made of laser light and photoelectrically converting interference light between the diffracted light generated from the diffraction grating and other diffracted light or reference light A so-called encoder device (interference encoder) that measures the relative movement amount of a member (such as a stage) provided with the diffraction grating 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.

International Publication No. 2008/029757 Pamphlet

Since the conventional encoder device reflects the diffracted light generated from the diffraction grating by a flat mirror or the like, when the height of the grating pattern surface of the diffraction grating changes, the diffracted light is compared with other diffracted light or reference light. The signal intensity of the interference light may decrease.
In view of such a problem, the aspect of the present invention suppresses a decrease in the signal intensity of the interference light when a height change of the grating pattern surface occurs when measuring the relative movement amount using the diffraction grating. With the goal.

  According to the first aspect of the present invention, there is provided an encoder apparatus for measuring a relative movement amount between a first member and a second member supported so as to be relatively movable in at least a first direction with respect to the first member. The The encoder device is provided in the first member, and is provided in a reflective diffraction grating having a grating pattern having a periodic direction at least in the first direction, a light source unit that emits measurement light, and a second member. A first optical member that causes the measurement light to enter the grating pattern surface of the diffraction grating substantially perpendicularly, and a first optical member that is provided on the second member and that is generated from the diffraction grating in the first direction by the measurement light. A first reflecting portion that causes the diffracted light to enter the diffraction grating and causes the second diffracted light generated from the diffraction grating to be incident on the first optical member by the first diffracted light, and the first optical member with respect to the first optical member. It is provided on the second member so as to face the reflecting portion and is displaced in the direction orthogonal to the first direction, and from the diffraction grating to the first direction by the measurement light. The third diffracted light having an order different from that of the first diffracted light generated is incident on the diffraction grating, and the fourth diffracted light generated from the diffraction grating by the third diffracted light is incident on the first optical member. First and second photoelectric detectors for detecting the second diffracted light, the second diffracted light and the fourth diffracted light through the first optical member, and the interference light of the other light flux, respectively, and the first And a measuring unit for obtaining a relative movement amount between the first member and the second member using a detection signal of the second photoelectric detector.

Moreover, according to the 2nd aspect, an optical apparatus provided with the encoder apparatus of a 1st aspect and the optical system for objects is provided.
According to the third aspect, there is provided an exposure apparatus that exposes a pattern onto an object to be exposed, the stage supporting the frame and the object to be exposed and movable relative to the frame in at least the first direction. And an encoder apparatus according to a first aspect for measuring a relative movement amount of the frame and the stage in the first direction at least.

  Moreover, according to the 4th aspect, the device manufacturing method which exposes an object using the exposure apparatus of a 3rd aspect in the lithography process including the lithography process is provided.

  According to the aspect of the present invention, the first diffracted light is incident on the diffraction grating by the first reflecting portion, and the third diffracted light is incident on the diffraction grating by the second reflecting portion. Even if the relative height of the grating pattern surface of the diffraction grating changes, the relative relationship between the second diffracted light and the fourth diffracted light generated from the diffraction grating by the first diffracted light and the third diffracted light and the other light fluxes. Shift amount is reduced. Accordingly, it is possible to suppress a decrease in the signal intensity of the interference light with respect to a change in the height of the grating pattern surface of the diffraction grating, and to maintain high measurement accuracy.

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 1st modification, (B) is a perspective view which shows the roof mirror in FIG. 5 (A). It is a top view which shows a part of detection head which concerns on a 1st modification. It is a figure which shows schematic structure of the exposure apparatus which concerns on 2nd Embodiment. FIG. 8 is a plan view illustrating an example of an arrangement of a diffraction grating and a plurality of detection heads provided on the wafer stage of FIG. 7. 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 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. Laser light source 16 and optical fiber 17 for supplying measurement laser light to head 14, optical fibers 39XA, 39XB, 39YA, 39YB, 39C for transmitting a plurality of interference lights generated by detection head 14, and optical fiber 39XA Photosensors 40XA, 40XB, 40YA, 40YB, 40C, such as photodiodes, which receive a plurality of interference lights supplied through -39C and output detection signals, and process these detection signals to process the first member 6 A measurement calculation unit 42 for obtaining a three-dimensional relative movement amount of the second member 7 in the X direction, the Y direction, and the Z direction. 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 Y-axis interferometer unit 15Y that irradiates measurement light onto grating 12 and generates a plurality of interference lights of a plurality of diffracted lights generated from diffraction grating 12 in the Y direction and a reference light, other optical members, a plurality of And supporting members 35X and 35Y, which are fixed to the second member 7 to support the optical member, and in which a plurality of openings through which the light beam passes are formed.

  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 and 40C. You may receive light.

  The detection head 14 includes a connecting portion 18 including a lens 18b (see FIG. 2C) that converts the laser beams ML and RL emitted from the optical fiber 17 into parallel light beams, and the laser light ML and the laser light ML, emitted from the connecting portion 18. A half prism 20A that divides RL into measurement light MX and reference light RX for X-axis, measurement light MY and reference light RY for Y-axis, and measurement light MX and reference light RX are directed substantially in the −Y direction. Two mirrors 22A and 22B that enter the X-axis interferometer unit 15X, and optical members 36A and 36B that cause most of the measurement light MY and the reference light RY to enter the Y-axis interferometer unit 15Y substantially in the + X direction. And having. In the present embodiment, the X-axis measurement light MX and the reference light RX emitted from the half prism 20A are heterodyne beams linearly polarized in the X direction and the Z direction, respectively, and the Y-axis measurement light emitted from the half prism 20A. MY and 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 portions of the optical fiber 17 and converted into parallel beams by the lens 18b, the laser beams ML after being converted into parallel beams. , 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 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, on the end surface in the −X direction of the support member 35X on the + Y direction side, the reflecting surface A3 and the polarization beam splitter surface parallel to the surface obtained by rotating the YZ surface 45 ° clockwise about an axis parallel to the Z axis. A PBS surface A2 and a half mirror surface A1 parallel to a surface obtained by rotating the YZ surface 45 ° counterclockwise about an axis parallel to the Z axis via a synthetic optical member 33X having A4 (hereinafter referred to as a PBS surface). The synthetic optical member 32X having the above is fixed. A wedge-shaped prism 34X is fixed to the incident surface of the synthetic optical member 32X. Further, polarizing plates 41XA and 41XB are fixed at positions facing the PBS surfaces A2 and A4 on the end surface in the + X direction of the support member 35X, and incident ends of the optical fibers 39XA and 39XB are fixed to the polarizing plates 41XA and 41XB.

  An optical element having a beam splitter surface (hereinafter referred to as a BS surface) B1 and a PBS surface B2 having high transmittance and low reflectance at the end portion in the + Y direction of the end surface in the −X direction of the support member 35Y on the −Y direction side. The member 36A is fixed. Furthermore, the composite optical members 33Y and 32Y having the same configuration as the composite optical members 33X and 32X are fixed to the −Y direction side region of the end surface of the support member 35Y, and the same as the wedge-shaped prism 34X on the incident surface of the composite optical member 32Y. A wedge-shaped prism 34Y having a shape is fixed. Polarizers 41YB, 41YA, and 41C are fixed to end surfaces in the + X direction of the support member 35Y at positions facing the PBS surfaces of the composite optical members 32Y and 33Y and the PBS surface B2 of the optical member 36A, and the polarizers 41YB, 41YA, and 41C. In addition, the incident ends of the optical fibers 39YB, 39YA, and 39C are fixed. The directions of the crystal axes of the polarizing plates 41XA to 41YB and 41C are such that interference light is generated by combining diffracted light or measurement 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 in the diagonal direction. Further, the wedge-shaped prisms 34X and 34Y cancel the angle β (see FIG. 2C) between the measurement light MX and MY and the reference light RX and RY with respect to the traveling direction of the incident reference light RX and RY. The reference light and the diffracted light to be measured are made parallel to each other.

  The optical member 36B has a BS surface B3 having a low transmittance and a high reflectance, two reflecting surfaces B4 and B5 that are substantially orthogonal to each other, and a reflecting surface that is disposed at a position away from the BS surface B3 in the -Y direction. B6. Most of the Y-axis measurement light MY and the reference light RY branched by the half prism 20A pass through the BS surface B1 of the optical member 36A, and a part of the measurement light MY and the reference light reflected by the BS surface B1. A part (reference light RY3) enters the PBS surface B2, and the S-polarized reference light RY3 is reflected by the PBS surface B2. Further, most of the measurement light MY and the reference light RY transmitted through the BS surface B1 are reflected by the BS surface B3 of the optical member 36B, and the reflected measurement light MY and the reference light RY are substantially −X through the reflection surface B6. Incidently enters the Y-axis interferometer unit 15Y.

  A part of the measurement light (measurement light MY3) and the part of the reference light RY transmitted through the BS surface B3 are reflected by the reflection surfaces B4 and B5 and enter the PBS surface B2 of the optical member 36A, and are P-polarized measurement light. MY3 is combined with the reference light RY3 transmitted through the PBS surface B2 and reflected by the PBS surface B2, thereby forming reference interference light. The reference interference light enters the optical fiber 39C through the polarizing plate 41C, and the interference light transmitted through the optical fiber 39C is received by the photoelectric sensor 40C. As an example, the position and angle of the reflection surface B5 of the optical member 36B are adjusted so that the measurement light MY3 synthesized on the PBS surface B2 and the reference light RY3 are coaxial and parallel to each other. Is set to

  Further, the X-axis interferometer unit 15X has a polarization beam splitter surface (hereinafter referred to as a PBS surface) A11 on which the measurement light MX and the reference light RX reflected by the mirror 22B substantially in the −Y direction are incident (FIG. 2A). A polarizing beam splitter member (hereinafter referred to as a PBS member) 24X having a reference) and a pair of roof prisms 26XA, 26XB fixed so as to sandwich the PBS member 24X in the X direction and displaced in the Y direction; A large-sized right-angle prism type reflecting member 28XA fixed to the + Y direction on the upper surface of the PBS member 24X and facing the + X direction, and symmetrically outward in the X direction on the −Y direction side at the center of the upper surface of the PBS member 24X. A pair of small right-angle prism type reflecting members 30XA and 30XB fixed facing and a large-sized fixed facing the −X direction on the −Y direction side of the upper surface of the BS member 24X. Having a reflecting member 28XA corner prism type, a. Further, the reflection member 22C, the wedge-shaped prism 34X, and the composite optical members 32X and 33X are also included in the interferometer unit 15X.

  The first reflecting portion 25XA is constituted by the roof prism 26XA and the reflecting members 28XA and 30XA on the + X direction side, and the second reflecting portion 25XB is constituted by the roof prism 26XB and the reflecting members 28XB and 30XB on the -X direction side. . The second member 7 has an opening (not shown) through which the measurement light MX and the diffracted light emitted from the diffraction grating 12 pass. The PBS member 24X is fixed to the second member 7 so as to cover the opening. ing.

  FIG. 2A shows the PBS member 24X and the reflecting portions 25XA and 25XB of the interferometer portion 15X in FIG. In FIG. 2A, the PBS member 24X has a transmission part inside the part where the large reflecting member 28XA on the + Y direction side is fixed and the part where the large reflecting member 28XB on the −Y direction side is fixed. A member having a three-layer structure in which a PBS surface A11 is formed obliquely (inclined at 45 ° around the X axis with respect to the XY surface) inside the portion where the small reflective members 30XA and 30XB at the center are fixed It is. 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. The roof prism 26XA of the reflector 25XA is symmetrical with respect to the incident surface A12 inclined at an angle α1 (see FIG. 3A) counterclockwise with respect to the bottom surface of the PBS member 24X, and the ridge line A16 parallel to the XZ plane. And it has a pair of reflective surfaces A13 and A14 formed so as to be orthogonal to each other, and an exit surface A15 in close contact with the PBS member 24X and the reflective members 28XA and 30XB. The ridgeline A16 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 and A24 that are orthogonal to each other.

  The measurement light MX reflected by the mirror 22B in FIG. 1 is incident on the PBS surface A11 of the PBS member 24X in FIG. 2A in the −Y direction as S-polarized light and the reference light RX as P-polarized light. The light passes through the PBS surface A11 and is emitted from the PBS member 24X substantially in the -Y direction. On the other hand, the S-polarized measurement light MX is reflected by the PBS surface A11 and enters the grating pattern surface 12b (grating pattern 12a) of the diffraction grating 12X substantially perpendicularly (approximately parallel to the Z axis). The term “substantially perpendicularly incident” means that the measurement light MX is parallel to the Z axis in order to reduce the influence of zero-order light (regular reflection light) in addition to the case where the measurement light MX is incident perpendicularly to the grating pattern surface 12b. This includes the case where the light is incident on the grating pattern surface 12b with an inclination of, for example, about 0.5 to 1.5 ° in the X direction (θy direction) and / or the Y direction (θx direction) with respect to the axis. .

  In the present embodiment, the measurement light MX incident on the grating pattern surface 12b of the diffraction grating 12 substantially vertically generates ± first-order diffracted lights DX1 and DX2 symmetrically in the X direction, and the generated diffracted lights DX1 and DX2 are the roof prisms. It is incident on the incident surfaces of 26XA and 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 parallel to the X axis and directed toward the −X direction via the exit surface A15 through the reflective member 28XA. Is incident on. The diffracted light DX1 reflected by the reflecting member 28XA passes through the PBS member 24X and enters the grating pattern surface 12b of the diffraction grating 12 substantially perpendicularly. The −1st order diffracted light DX2 is shifted in the −Y direction via the reflecting surfaces A23 and A24 of the roof prism 26XB and incident on the reflecting member 28XB in the + X direction parallel to the X axis. The diffracted light DX2 reflected by 28XB 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 members 28XA and 28XB 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 light beam is shifted in the −Y direction via the incident surface A12 and the reflecting surfaces A14 and A13 of the roof prism 26XA, and is incident on the reflecting member 30XA in the −X direction parallel to the X axis. Then, the S-polarized diffracted light EX1 reflected by the reflecting member 30XA is reflected by the PBS surface A11 of the PBS member 24X, and is emitted from the PBS member 24X in a substantially −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 30XB in the + X direction parallel to the X axis. Then, the s-polarized diffracted light EX2 reflected by the reflecting member 30XB is reflected by the PBS surface A11 and emitted from the PBS member 24X substantially in the -Y direction.

  In FIG. 1, diffracted beams EX1 and EX2 emitted from the PBS member 24X are reflected by the reflecting member 22C and pass through the PBS surfaces A2 and A4 of the synthetic optical members 32X and 33X, respectively. The diffracted beams EX1 and EX2 are S-polarized light with respect to the PBS surface A11 of the PBS member 24X, but are P-polarized light with respect to the PBS surfaces A2 and A4. Further, the reference light RX transmitted through the PBS member 24X is reflected by the reflecting member 22C and enters the half mirror surface A1 of the combining optical member 32X via the wedge-shaped prism 34X. The reference light RX1 reflected by the half mirror surface A1 is reflected by the PBS surface A2 and synthesized coaxially with the diffracted light EX1 to become interference light. This interference light is received by the photoelectric sensor 40XA via the polarizing plate 41XA and the optical fiber 39XA. The reference light RX2 that has passed through the half mirror surface A1 is reflected by the reflecting surface A3 of the combining optical member 33X, then is reflected by the PBS surface A4, and is coaxially combined with the diffracted light EX2 to become interference light. This interference light is received by the photoelectric sensor 40XB via the polarizing plate 41XB and the optical fiber 39XB. This is because the reference beams RX1 and RX2 are P-polarized with respect to the PBS surface A11 of the PBS member 24X, but are S-polarized with respect to the PBS surfaces A2 and A4.

  The Y-axis interferometer unit 15Y includes a PBS member 24Y and reflecting units 25YA and 25YB that are configured by integrally rotating the PBS member 24X and the reflecting units 25XA and 25XB of the X-axis interferometer unit 15X by 90 °. That is, the reflecting portions 25YA and 25YB also have roof prisms 26YA and 26YB, large reflecting members 28YA and 28YB, and small reflecting members 30YA and 30YB, respectively, and the PBS member 24Y covers the opening (not shown). It is fixed to the member 7. Further, the interferometer unit 15Y includes a wedge prism 34Y and synthetic optical members 32Y and 33Y.

  The measurement light MY and the reference light RY reflected by the reflection surface B6 are incident on the PBS member 24Y of the interferometer unit 15Y, and the P-polarized reference light RY is transmitted through the PBS surface of the PBS member 24Y and emitted in the + X direction. The 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 substantially perpendicularly, and ± 1st-order diffracted lights DY1, DY2 (symmetrically in the Y direction from the grating pattern 12a) 3B) 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 incident on the grating pattern 12a of the diffraction grating 12 substantially perpendicularly via the reflecting portion 25YA (reflecting portion 25YB). Then, the + 1st order diffracted light EY1 in the Y direction by the diffracted light DY1 and the −1st order diffracted light EY2 in the Y direction by the diffracted light DY2 are generated from the diffraction grating 12, and the diffracted light EY1 passes through the reflecting portion 25YA to the PBS surface of the PBS member 24Y. The diffracted light EY2 is reflected by the PBS surface of the PBS member 24Y via the reflector 25YB and emitted in the + X direction.

  Then, the diffracted beams EY1 and EY2 emitted from the PBS member 24Y are transmitted through the PBS surfaces of the composite optical members 33Y and 32Y in a P-polarized state, respectively. Further, the reference light RY transmitted through the PBS member 24Y is incident on the half mirror surface of the combining optical member 32Y through the wedge prism 34Y. The reference light RY2 reflected by the half mirror surface is reflected by the PBS surface and synthesized coaxially with the diffracted light EY2 to become interference light. This interference light is received by the photoelectric sensor 40YB via the polarizing plate 41YB and the optical fiber 39YB. The reference light RY1 transmitted through the half mirror surface is reflected by the reflecting surface of the combining optical member 33Y, then is reflected by the PBS surface, and is coaxially combined with the diffracted light EY1 to become interference light. This interference light is received by the photoelectric sensor 40YB through the polarizing plate 41YA and the optical fiber 39YA.

  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. 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 X-axis photoelectric sensor 40XB receives the diffracted light EX2. And the detection signal of the interference light which consists of reference light RX2 is supplied to the 1st calculating part 42X. The Y-axis photoelectric sensor 40YA supplies the interference light detection signal composed of the diffracted light EY1 and the reference light RY1 to the second calculation unit 42Y, and the Y-axis photoelectric sensor 40YB receives the diffracted light EY2 and the reference light RY2. The interference light 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 °.
Further, the diffracted light DX1 is bent by the roof prism 26XA (incident surface A12 and reflecting surfaces A13, A14) and the reflecting member 28XA 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 reflecting portion 25XA is shifted from the position where the measurement light MX is incident in the + X direction and the + Y direction. Incident perpendicularly to the grating pattern 12a. Then, 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 is bent in parallel with the Z axis by the reflecting portion 25XA, and PBS It goes to the PBS surface A11 of the 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 reflection portion 25XB symmetrically with the diffraction light DX1. Incident perpendicularly to the grating pattern 12a. Then, the minus first-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 reflecting portion 25XB 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. Then, the + 1st order diffracted light EY1 generated from the diffraction grating 12 by the diffracted light DY1 via the reflecting portion 25YA 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 reflecting portions 25YA and 25YB, respectively, and heads toward the PBS surface of the PBS member 24Y.

  In the arrangement of FIG. 3A, as shown in FIG. 4A, the relative position in the Z direction of the grating pattern surface 12b of the diffraction grating 12 with respect to the interferometer unit 15X has changed by δZ to the position B11. Assume a case. At this time, the + 1st-order diffracted light DX1 by the measurement light MX is incident on the reflection unit 25XA with the optical path shifted parallel to the position B12. However, in the reflection unit 25XA, the optical path of the emitted light is shifted symmetrically with respect to the incident light. To do. Therefore, the diffracted light DX1 reflected by the reflecting portion 25XA 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 interference light is generated by coaxially combining the diffracted light EX1 and the reference light RX1 on the PBS surface A2 (see FIG. 1), there is no relative lateral shift amount between the diffracted light EX1 and the reference light RX1. The ratio of the AC signal (beat signal or signal component) in the detection signal obtained when photoelectrically converting the interference light does not decrease.

  This also 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 to 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 reflecting portion 25XA 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.

The effects and the like of this embodiment are as follows.
The encoder 10 of the present embodiment is a three-axis encoder device that measures the relative movement amount of a second member 7 that can be three-dimensionally moved relative to the first member 6 in the X, Y, and Z directions. . The encoder 10 is a laser that is provided on the first member 6 and includes a reflective diffraction grating 12 having a two-dimensional grating pattern 12a having a periodic direction in the X direction and the Y direction, and the measurement light MX and the reference light RX. A laser light source 16 that generates light, a PBS member 24X (first optical member) that is provided on the second member 7, transmits the measurement light MX, and enters the grating pattern surface 12b of the diffraction grating 12 substantially perpendicularly; The + 1st order diffracted light DX1 (first diffracted light) in the X direction generated from the diffraction grating 12 by the measurement light MX is incident on the diffraction grating 12, and is generated from the diffraction grating 12 by the + 1st order diffracted light DX1. A reflective portion 25XA that makes X-direction + 1st order diffracted light EX1 (second diffracted light) incident on the PBS member 24X, and the PBS member 24X faces the reflective portion 25XA. In addition, the first-order diffracted light DX2 (the first diffracted light DX2 (first) generated symmetrically to the diffracted light DX1 in the X direction from the diffraction grating 12 by the measurement light MX is provided in the second member 7 while being displaced in the Y direction orthogonal to the X direction. (3 diffracted light) is incident on the diffraction grating 12, and the X-direction -1st order diffracted light EX2 (4th diffracted light) generated from the diffraction grating 12 by the -1st order diffracted light DX2 is incident on the PBS member 24X; The photoelectric sensors 40XA and 40XB that detect the interference light between the diffracted lights EX1 and EX2 reflected by the PBS member 24X and the reference light branched from the reference light RX, and the detection signals of the photoelectric sensors 40XA and 40XB, respectively, are used. A measurement calculation unit 42 (measurement unit) for obtaining a relative movement amount between the member 6 and the second member 7 in the X direction and the Z direction.

  According to the present embodiment, the incident angle when the diffracted lights DX1 and DX2 are incident on the diffraction grating 12 is substantially 0 by the reflecting portions 25XA and 25XB, so the relative position between the first member 6 and the second member 7 Changes, and 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) also changes from the diffraction grating 12 by the diffracted light DX1 and DX2. The optical path of the diffracted beams EX1 and EX2 (re-diffracted beams) hardly changes, and the relative shift amount in the lateral direction between the diffracted beams EX1 and EX2 and the reference beams 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, since the reflecting portions 25XA and 25XB are displaced in the Y direction, the interferometer portion 15X can be easily downsized.
Further, the encoder 10 causes the measurement light MY to enter the diffraction grating 12 almost perpendicularly by the PBS member 24Y, and the incident angles of the ± first-order diffracted lights DY1 and DY2 generated in the Y direction by the measurement light MY from the diffraction grating 12 are substantially 0. Interference light between the reflection portions 25YA and 25YB that are shifted in the X direction to be incident on the diffraction grating 12 and 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. Photoelectric sensors 40YA and 40YB for detection. 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.

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.

  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 of the measurement light having the first frequency on the X axis and the second 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, EX1, etc. generated from the diffraction grating 12 are incident on the reflecting members 28XA, 30XA via the roof prism 26XA, respectively. However, as shown in the main part of the X-axis interferometer 15XA of the first modification of FIG. 5A, a roof mirror 44XA having orthogonal reflecting surfaces A33 and A34 instead of the roof prism 26XA (FIG. 5). (B)) and a wedge-shaped prism 46XA having an apex angle α3 may be used. In this case, a roof mirror 44XB and a wedge prism 46XB may be used instead of the roof prism 26XB. By using the roof mirrors 44XA and 44XB, the interferometer unit 15XA may be reduced in weight. The wedge prisms 46XA and 46XB can be omitted. Similarly, a plane mirror may be used as the reflecting members 28XA and 30XA.

Further, as shown in the main part of the detection head 14A of the first modified example in FIG. 6, instead of using the wedge prisms 34X and 34Y in FIG. 1, the X-axis diffracted beams EX1 and EX2 (measurement beams) are on the optical path. A pair of declination prisms 46XA and 46XB are installed, and a pair of declination prisms 46YA and 46YB are installed on the optical path of the Y-axis diffracted beams EY1 and EY2 (measurement beam), respectively. A pair of declination prisms 46C may be installed on the optical path. In the above embodiment, the measurement beams MX and MY and the reference beams RX and RY supplied to the detection head 14A intersect at an angle β. For this reason, the angle and inclination direction of the reference measurement light are adjusted from the diffracted light EX1 by the declination prisms 46XA, 46XB, 46YA, 46YB, and 46C, and the reference light corresponding to the reference measurement light from the diffracted light EX1. The signal-to-noise ratio of the interference fringe detection signal can be increased.
Note that the measurement beams MX and MY supplied to the detection head 14 and the reference beams RX and RY may be substantially parallel. In this case, it is not necessary to provide the wedge-shaped prisms 34X and 34Y or the declination prisms 46XA to 46C.

[Second Embodiment]
A second embodiment of the present invention will be described with reference to FIGS. FIG. 7 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. 9) 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. 9 including a linear motor, for example, 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. 7, 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. 9) 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. 9) 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. 9) 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. 8) for measuring the Z position of the location, and an encoder device 8B for measuring position information of 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-described 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. 7, 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. 10). 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. 8, 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 corresponds to a measurement calculation unit 42 (corresponding to a detection signal of interference light between the diffraction light generated from the diffraction gratings 12A and 12B and the reference light. (See FIG. 9). 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. 9). 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.
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.

The present invention can be applied to a step-and-repeat type projection exposure apparatus (stepper or the like) in addition to the above-described scanning exposure type projection exposure apparatus (scanner). Furthermore, the present invention can be similarly applied to a dry exposure type exposure apparatus other than an immersion type exposure apparatus.
In addition, the present invention is not limited to application to an exposure apparatus for manufacturing a semiconductor device, for example, an exposure apparatus for a display device such as a liquid crystal display element formed on a square glass plate or a plasma display, It can also be widely applied to an exposure apparatus for manufacturing various devices such as an image sensor (CCD or the like), a micromachine, a thin film magnetic head, and a DNA chip. Furthermore, the present invention can also be applied to an exposure apparatus when manufacturing a mask (photomask, reticle, etc.) on which a mask pattern of various devices is formed using a photolithography process.

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.
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, 25XA, 25XB, 25YA, 25YB ... reflection , 26XA, 26XB, 26YA, 26YB ... roof prism, 40XA, 40XB, 40YA, 40YB, 40C ... photoelectric sensor, 42 ... measurement calculation unit

Claims (12)

An encoder device for measuring a relative movement amount between a first member and a second member supported so as to be relatively movable in at least a first direction with respect to the first member,
A reflective diffraction grating provided on the first member and having a grating pattern having at least the first direction as a periodic direction;
A light source unit for emitting measurement light;
A first optical member provided on the second member for allowing the measurement light to enter the grating pattern surface of the diffraction grating substantially perpendicularly;
A second diffracted light that is provided on the second member and that is generated by the measurement light from the diffraction grating in the first direction is incident on the diffraction grating, and is generated from the diffraction grating by the first diffracted light. A first reflecting portion for making diffracted light incident on the first optical member;
The first optical member is provided on the second member so as to be opposed to the first reflecting portion and shifted in a direction orthogonal to the first direction, and from the diffraction grating by the measurement light. Third diffracted light having a different order from the first diffracted light generated in one direction is incident on the diffraction grating, and fourth diffracted light generated from the diffraction grating by the third diffracted light is incident on the first optical member. A second reflecting part to be made,
First and second photoelectric detectors for detecting interference light between the second diffracted light and the fourth diffracted light and other light beams via the first optical member;
A measurement unit for obtaining a relative movement amount between the first member and the second member using detection signals of the first and second photoelectric detectors;
An encoder device comprising:   The incident positions of the first diffracted light and the third diffracted light with respect to the grating pattern surface are substantially symmetrical with respect to the direction orthogonal 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 1, wherein the encoder device is deviated.   3. The encoder device according to claim 1, wherein the third diffracted light is generated substantially symmetrically with the first diffracted light with respect to the first direction from the diffraction grating. The first reflecting portion causes the first diffracted light to enter the diffraction grating substantially perpendicularly, and the second diffracted light generated from the diffraction grating substantially parallel to the first diffracted light is applied to the first optical member. Incident,
The second reflecting unit causes the third diffracted light to enter the diffraction grating substantially perpendicularly, and the fourth diffracted light generated from the diffraction grating to be substantially parallel to the third diffracted light is applied to the first optical member. The encoder device according to claim 3, wherein the encoder device is incident. The first reflecting portion includes a first light beam reflecting member having two orthogonal reflecting surfaces that reflect the first diffracted light and the second diffracted light,
The said 2nd reflection part has a 2nd light beam reflective member with two orthogonal reflective surfaces which reflect the said 3rd diffracted light and the said 4th diffracted light, The any one of Claims 1-4 characterized by the above-mentioned. The encoder device according to item. The light source unit emits the measurement light and reference light having a polarization state different from that of the measurement light,
The first optical member includes a polarization beam splitter that makes the measurement light incident on the diffraction grating out of the measurement light and the reference light,
The first and second photoelectric detectors detect interference light between the second diffracted light, the fourth diffracted light, and the first reference light and the second reference light branched from the reference light, respectively. The encoder device according to any one of claims 1 to 5, wherein The measurement light and the reference light are emitted from the light source unit at a predetermined angle,
A first angle correction member that corrects a relative angle between the second diffracted light and the first reference light;
The encoder apparatus according to claim 6, further comprising a second angle correction member that corrects a relative angle between the fourth diffracted light and the second reference light. 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 second optical member that is provided on the second member and makes the measurement light incident substantially perpendicularly to a grating pattern surface of the diffraction grating;
A fifth diffracted light that is provided on the second member and is generated from the diffraction grating in the second direction by the measurement light is incident on the diffraction grating, and is generated from the diffraction grating by the fifth diffracted light. A third reflecting portion for allowing diffracted light to enter the second optical member;
The second optical member is provided on the second member so as to be opposed to the third reflecting portion and in a direction orthogonal to the second direction, and the first optical member is moved from the diffraction grating by the measurement light. Seventh diffracted light having a different order from the fifth diffracted light generated in two directions is incident on the diffraction grating, and the eighth diffracted light generated from the diffraction grating by the seventh diffracted light is incident on the second optical member. A fourth reflecting portion to be made,
And third and fourth photoelectric detectors for detecting interference light between the fifth diffracted light and the eighth diffracted light and other light beams via the second optical member,
The measurement unit obtains a relative movement amount between the first member and the second member using detection signals of the first, second, third, and fourth photoelectric detectors. The encoder apparatus as described in any one of 1-7.   The measurement unit obtains a relative movement amount between the first member and the second member in the first direction, the second direction, and a third direction perpendicular to a grating pattern surface of the diffraction grating. The encoder device according to claim 8. The encoder device according to any one of claims 1 to 9,
And an optical system for an object. 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 claim 1 for measuring at least a relative movement amount of the stage in the first direction. A device manufacturing method including a lithography process,
12. A device manufacturing method comprising exposing an object using the exposure apparatus according to claim 11 in the lithography process.

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