JP5862857B2 - Encoder device, optical device, and exposure device - Google Patents

Description

  The present invention relates to an encoder apparatus that measures a relative movement amount between members that move relatively, an optical apparatus and an exposure apparatus that include the encoder apparatus, and a device manufacturing method that uses 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 can obtain a resolution close to that of a laser interferometer.

International Publication No. 2008/029757 Pamphlet

In the conventional encoder device, a plurality of optical members for causing the diffracted light and other diffracted light or reference light to interfere with each other are arranged almost along the incident surface of the measurement light, so that the height of the optical system becomes high. For example, it is difficult to incorporate the optical system in a narrow space.
Further, in the conventional encoder device, there is a possibility that certain diffracted light including measurement information and the direction of zero-order light (regularly reflected light) generated from the diffraction grating are parallel. When the 0th-order light is mixed with the interference light to be detected in a state where the diffracted light and the 0th-order light are parallel in this way, interference light having a period different from the period including the original measurement information is included in the interference light. As a result, the measurement accuracy may be reduced.

  In view of such a problem, the aspect of the present invention reduces the height of the optical system and reduces the influence of zero-order light from the diffraction grating when measuring using the diffraction grating. It aims to improve.

According to the first aspect of the present invention, there is an encoder device for measuring a relative movement amount of a second member that moves relative to the first member at least in the first direction, the first member and the second member. A reflection type diffraction grating having a grating pattern having a first direction as a periodic direction, a light source unit for supplying first and second measurement light, and the first member and the second member. The first measurement light, which is provided on the other side and is supplied from the light source unit, is irradiated toward the diffraction grating at a first angle with respect to the normal of the surface of the diffraction grating, and is diffracted by the diffraction grating. A first optical member that irradiates the first measurement light toward the diffraction grating at a second angle with respect to the normal line, and is provided on the other of the first member and the second member. the supplied its second measuring light with respect to the normal to the plane of the diffraction grating Irradiated toward the diffraction grating in the third angle, and a second optical member for irradiating the its second measurement light diffracted by the diffraction grating on the diffraction grating at a fourth angle relative to the normal A photoelectric detector for photoelectrically detecting the first measurement light diffracted by the diffraction grating and the second measurement light diffracted by the diffraction grating, and using the detection signal of the photoelectric detector, the second A measuring unit for determining a relative movement amount of the member, and the traveling direction of the first measurement light irradiated to the diffraction grating at the first angle and the diffraction grating irradiated to the diffraction grating at the third angle. The traveling direction of the second measurement light regularly reflected by the diffraction grating is non-parallel, and the traveling direction of the first measurement light irradiated on the diffraction grating at the second angle is the fourth direction. The second measurement light irradiated to the diffraction grating at an angle and regularly reflected by the diffraction grating The traveling direction encoder device is provided which is non-parallel.
According to another aspect of the present invention, there is provided an encoder device that measures a relative movement amount of a second member that relatively moves in at least a first direction with respect to the first member. This encoder device is provided on one of the first member and the second member, and a reflective diffraction grating having a grating pattern whose first direction is a periodic direction, and a first measurement light having coherence with each other. And a light source part that supplies the second measurement light, and a first reflection that is provided on the other of the first member and the second member and reflects the first measurement light supplied from the light source part toward the lattice pattern surface. The first photoelectric detector that detects interference light between the member, the diffracted light from the diffraction grating and the other diffracted light or the second measurement light, and the second photoelectric detector using the detection signal of the first photoelectric detector. A measuring unit for obtaining a relative movement amount of the member, and the incident angle in the first direction of the first measurement light from the reflecting member toward the grating pattern surface is set to a predetermined angle with respect to the Littrow angle of the diffraction grating. The changed angle is set.
According to still another aspect of the present invention, there is provided an encoder device that measures a relative movement amount of a second member that moves relative to the first member in at least the first direction. The encoder device is provided on one of the first member and the second member, and includes a reflection type diffraction grating having a grating pattern whose periodic direction is the first direction, a light source unit that supplies measurement light, and An optical system that is provided on the other of the first member and the second member, irradiates the measurement light supplied from the light source unit toward the grating pattern surface, and receives the measurement light diffracted by the diffraction grating. And the optical member irradiates the grating pattern surface with the first and second measurement light beams having different traveling directions, and the traveling direction of the first measurement light that is regularly reflected by the diffraction grating. And the traveling direction of the second measurement light which is diffracted by the diffraction grating and enters the second optical member is set to a different direction.

Moreover, according to the 2nd aspect, an optical apparatus provided with the encoder apparatus of this invention and the optical system for objects is provided.
Moreover, according to the 3rd aspect, the exposure apparatus which exposes a pattern to a to-be-exposed body is provided. The exposure apparatus supports a 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, and measures a relative movement amount of the stage in the first direction. And an encoder device according to the present invention.

  According to the fourth aspect, there is provided a device manufacturing method that includes a lithography process, and in the lithography process, exposes an object using the exposure apparatus.

According to the present invention, the height of the optical system of the encoder device (the height in the normal direction of the surface of the diffraction grating ( grating pattern surface )) can be reduced.
Furthermore, if the first angle of incidence of the first measurement light toward the surface of the diffraction grating was set to a predetermined angle changed angle to the Littrow angle of the diffraction grating from the first optical member, the surface The lateral shift amount of the diffracted light is small with respect to the height change, the intensity change of the interference light is small, and the influence of the zeroth order light from the diffraction grating can be reduced to improve the measurement accuracy.

(A) is a perspective view which shows the encoder which concerns on an example of embodiment, (B) is a figure which shows the reflective surface etc. of the inclination mirror in FIG. 1 (A). It is a perspective view which shows the optical path of the 2nd time diffracted light of the encoder of FIG. (A) is a diagram showing a state in which reflected light from an inclined mirror is perpendicularly incident on the diffraction grating, (B) is a diagram showing a state in which reflected light from the inclined mirror is incident on the diffraction grating while being inclined in the X direction. C) is a diagram showing a state in which the reflected light from the inclined mirror is incident on the diffraction grating while being inclined in the X direction and the Y direction. (A) is a perspective view showing a state in which reflected light from an inclined mirror enters a diffraction grating through a wedge-shaped prism, (B) is a view seen from the direction B in FIG. 4 (A), and (C) is a two-dimensional view. It is a perspective view which shows the example which uses this diffraction grating. It is a top view which shows the two-dimensional encoder which concerns on 1st Example. It is a top view which shows the encoder which concerns on 2nd Example. (A) is sectional drawing which follows the AA line of FIG. 6, (B) is a figure which follows the BB line of FIG. 6, (C) is a figure which abbreviate | omits and shows a part along the BB line of FIG. It is a top view which shows the optical path of the reference light of FIG. It is a figure which shows schematic structure of the exposure apparatus which concerns on 3rd Example. FIG. 10 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. 9. 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.

  Hereinafter, an exemplary embodiment of the present invention will be described with reference to FIGS. FIG. 1A is a perspective view showing a main part of an X-axis encoder 10X according to the present embodiment. In FIG. 1A, as an example, the second member 7 is disposed so as to be relatively movable in a two-dimensional plane with respect to the first member 6, and the second member 7 is disposed in two directions that are relatively movable relative to each other. A description will be given assuming that the X axis and the Y axis are taken in parallel, and the axis orthogonal to the plane (XY plane) defined by the X axis and the Y axis is the Z 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 direction, the θy direction, and the θz direction, respectively.

  In FIG. 1A, an encoder 10X includes a flat plate-shaped X-axis diffraction grating 12X fixed to the upper surface of the first member 6 and parallel to the XY plane, and a diffraction grating fixed to the upper surface of the second member 7. An X-axis detection head 14X that irradiates measurement light to 12X, a laser light source 16 that supplies laser light for measurement to the detection head 14X, and a detection signal output from the detection head 14X to process the first member 6 A measurement calculation unit 42X that obtains a relative movement amount of at least the second member 7 in the X direction. Further, a Y-axis encoder for obtaining a relative movement amount of the second member 7 in the Y direction with respect to the first member 6 is also provided. In FIG. 1A, only the detection head 14Y of the Y-axis encoder is shown.

  On the grating pattern surface 12Xb parallel to the XY plane of the diffraction grating 12X, a phase-type and reflection-type grating pattern 12Xa having a predetermined period (pitch) in the X direction is formed. The period of the lattice pattern 12Xa is about 100 nm to 4 μm (for example, a period of 2 μm) as an example. The grating pattern 12Xa can be produced, for example, as a hologram (for example, an interference fringe baked on a photosensitive resin) or by mechanically forming a groove or the like on a glass plate or the like and applying a reflective film. Furthermore, the lattice pattern surface 12Xb may be covered with a protective flat glass. Instead of the diffraction grating 12X, a two-dimensional diffraction grating having a grating pattern periodically formed in the X direction and the Y direction may be used.

  The laser light source 16 is made of, for example, a He—Ne laser or a semiconductor laser. For example, a dual-frequency heterodyne light composed of first and second linearly polarized laser beams XR and YR whose polarization directions are orthogonal to each other and have different frequencies. Inject. The laser beams XR and YR are coherent with each other, and their average wavelength is λ. The laser light source 16 supplies a reference frequency signal (reference signal) obtained by photoelectrically converting the interference light of two light beams branched from the laser beams XR and YR to the measurement calculation unit 42X. A homodyne interference method can also be used.

  The heterodyne light emitted from the laser light source 16 is split into a P-polarized first laser light XR and an S-polarized second laser light YR having the same light quantity by a polarizing beam splitter (hereinafter referred to as PBS) 18. Is done. The first laser beam XR is incident on the PBS 22X via the half-wave plate 20A for adjusting the polarization direction, and the S-polarized X-axis measurement beam MX in the -X direction and the P beam in the + Y direction. It is split into polarized Y-axis reference light RY. The Y-axis reference light RY is supplied to the Y-axis detection head 14Y via the mirrors 45A and 45B, and the reference light RY is transmitted from the Y-axis diffraction grating (not shown) by the Y-axis measurement light in the detection head 14Y. Interferes with the generated diffracted light.

  The second laser light YR divided by the PBS 18 is incident on the PBS 22Y via the half-wave plate 20B, and is converted into the P-polarized Y-axis measurement light MY and the S-polarized X-axis reference light RX. The Y-axis measurement light MY is divided and supplied to the Y-axis detection head 14Y. The half-wave plate 20B and the PBS 22Y can be regarded as a part of the detection head 14Y. The rotation angles of the half-wave plates 20A and 20B are adjusted so that the light amounts of the measurement beams MX and MY are about 95% of the light amounts of the incident laser beams XR and YR, respectively. The S-polarized reference light RX reflected by the PBS 22Y is converted into P-polarized light by the half-wave plate 20C, and then enters the half mirror 45E via the mirrors 45C and 45D with the optical path shifted in the + Z direction. The first and second reference beams RX1 and RX2 having the same light amount are divided. The reference light RX1 enters the PBS 38XA as P-polarized light, and the reference light RX2 enters the PBS 38XB as P-polarized light through the mirror 45F. The reference beams RX1 and RX2 are combined with first and second diffracted beams on the X axis, which will be described later, in PBSs 38XA and 38XB to become interference light (heterodyne beams). These interference lights enter the first and second photoelectric sensors 40XA and 40XB made of a photodiode or the like via a wave plate (not shown). In practice, the optical paths are set so that the optical path lengths of the reference beams RX1 and RX2 are substantially equal to the optical path length of the corresponding measurement light (diffracted light).

  As described above, in this embodiment, the reference light RY divided from the X-axis laser light XR is supplied to the Y-axis detection head 14Y, and the reference light RX (RX1, RX2) divided from the Y-axis laser light YR. Interferes with the diffracted light generated by the X-axis detection head 14X. As an example, the diffraction efficiency of the diffraction grating 12X is approximately 10%, and the efficiency of the finally used diffracted light is approximately 1% by performing diffraction twice as described later. Accordingly, by setting the light amounts of the measurement beams MX and MY to approximately 95% in this way, the light amount ratio between the finally diffracted light and the reference light becomes approximately 1: 1, and it is necessary to attenuate the reference light. Therefore, the use efficiency of the laser beams XR and YR is increased. An optical system 44 for adjusting the optical path length of the reference light to the optical path length of the measurement light is configured from the mirrors 45A to 45F, the half mirror 45E, and the half-wave plate 20C.

  Further, as described later, in this embodiment, in order to measure the difference (XZ) (or YZ) between the relative movement amount X in the X direction (or Y direction) and the relative movement amount Z in the Z direction. In addition, the + 1st order and −1st order diffracted lights are also used in the X direction diffraction grating 12X (or the Y direction diffraction grating 12Y). In the present embodiment, the wavelengths of the + 1st order and −1st order diffracted light (measured as λ1) for measuring the relative movement amount X are made the same. Similarly, when measuring the relative movement amount Y, the wavelengths of the diffracted light of the + 1st order and the −1st order (referred to as λ2) are made the same. Thus, the measurement light (light diffracted by the diffraction gratings 12X and 12Y) for measuring the movement amount X and the movement amount Y is set to have different wavelengths. Thus, as described above, when the light amount ratio between the measurement light (wavelength λ1) and the reference light (wavelength λ2) for measuring the movement amount X is 95: 5, the movement amount Y is measured. The light quantity ratio between the measurement light (wavelength λ2) and the reference light (wavelength λ1) is also 95: 5. In this case, the wavelengths λ1 and λ2 are two wavelengths of the heterodyne beam emitted from the laser light source 16.

The detection head 14X of the present embodiment has a two-story structure, and the PBSs 18, 22X, 22Y, etc. are on the first floor portion on the second member 7, whereas the PBSs 38XA, 38XB, etc. are passed through a frame (not shown). Located on the second floor.
The X-axis detection head 14X has a half mirror surface 25A and a reflection surface 25B separated in the X direction on the first floor, together with the half-wave plate 20A, the PBS 22X, and the optical system 44 for reference light. An optical path changing member 24X having a reflecting surface 25C on the second floor, a mirror 36X having a reflecting surface disposed near the end of the optical path changing member 24X in the -X direction and inclined at approximately 45 ° with respect to the Y axis, Have Further, the detection head 14X includes first and second PBSs 28A and 28B that are symmetrically disposed adjacent to each other in the X direction so as to face the + Y direction side of the optical path changing member 24X, and the + X direction side of the PBSs 28A and 28B. The first and second corner cubes 29A and 29B fixed symmetrically on the side surface on the −X direction side, and the first and second + 1st order diffracted light beams supported by a frame (not shown) on the + Y direction side of the PBS 28A. Inclined mirrors 32XA and 32XB, and first and second inclined mirrors 34XA and 34XB for -1st order diffracted light supported by a frame (not shown) on the + Y direction side of PBS 28B. The inclined mirrors 32XA and 34XA have a reflecting surface on the first floor portion, and the inclined mirrors 32XB and 34XB have a reflecting surface on the second floor portion. The polarization beam splitter surfaces of the PBSs 28A and 28B are surfaces obtained by rotating a plane parallel to the ZY plane by 45 ° and −45 ° in the θz direction, respectively. Further, a half-wave plate 27 is fixed to the side surfaces of the PBSs 28A and 28B in the -Y direction, and a quarter-wave plate 30 is fixed to the side surfaces of the PBSs 28A and 28B in the + Y direction. Including the 1/2 wavelength plate 27, PBS 28A, 28B, corner cubes 29A, 29B, 1/4 wavelength plate 30, tilting mirrors 32XA, 32XB, and tilting mirrors 34XA, 34XB, each ± 2nd order diffraction An X-axis diffracted light generator 26X is configured to be performed.

  In the detection head 14X, the S-polarized X-axis measurement light MX branched in the −X direction by the PBS 22X is incident on the optical path changing member 24X, and the first measurement light MX1 that substantially goes in the + Y direction at the half mirror surface 25A. The second measurement light MX2 is divided into the second measurement light MX2 directed in the −X direction, and the second measurement light MX2 is reflected almost in the + Y direction by the reflection surface 25B. The measurement lights MX1 and MX2 are converted into P-polarized light (here, the polarization direction is the X direction) via the half-wave plate 27 and enter the PBSs 28A and 28B. The incident measurement lights MX1 and MX2 pass through the PBSs 28A and 28B, respectively, and enter the plane reflecting surfaces of the inclined mirrors 32XA and 34XA via the quarter-wave plate 30.

  FIG. 1B is a diagram showing the reflecting surfaces and the like of the inclined mirrors 32XA and 34XA in FIG. In FIG. 1B, the measurement light MX1 incident on the reflecting surface of the inclined mirror 32XA is reflected by the reflecting surface, and the incident angle φ1 in the θy direction (X direction) is reflected on the grating pattern surface 12Xb of the diffraction grating 12X. Then, the light enters the grating pattern 12Xa in a state of being larger than the Littrow angle (Littrow angle) φLI of the + 1st order diffracted light by a predetermined angle β.

φ1 = φLI + β (1)
The incident angle in the θx direction (Y direction) of the measurement light MX1 incident on the grating pattern surface 12Xb may be 0, but the incident angle in the Y direction of the measurement light MX1 is inclined to, for example, about 0 to β (for example, about β / 2). It is preferable. The angle β is about 0.5 ° to several degrees as an example, and is set to, for example, 0.5 ° to 1.5 ° (target value is about 1 °).

  The Littrow angle φLI of the + 1st order diffracted light is an incident angle of the light beam LA when the incident light beam LA and the + 1st order diffracted light LA1 are parallel, as indicated by the dotted light beam LA. When the light beam LA is incident at the Littrow angle φLI as described above, there is an advantage that the intensity of the interference light does not change because the lateral shift of the + 1st order diffracted light LA1 does not occur even if the height of the grating pattern surface changes. As described later, a problem of noise light due to zero-order light occurs. When the period in the X direction of the grating pattern 12Xa is p and the average wavelength of the measurement lights MX1 and MX2 is λ, the Littrow angle φLI satisfies the following relationship.

2 ・p ・ sin φLI = λ (2)
The 0th order light (regular reflection light) LA0 by the grating pattern 12Xa of the light beam LA incident at the Littrow angle φLI is symmetric with the + 1st order diffracted light LA1. In this case, since the −1st order diffracted light of the light beam incident on the grating pattern 12Xa symmetrically with the light beam LA and the 0th order light LA0 are substantially parallel, the −1st order diffracted light and the 0th order light LA0 merge. Interference fringes (noise light) with a large period are formed, which may cause measurement errors.

Further, the diffraction angle φ2 of the + 1st order diffracted light DX1 from the diffraction grating 12X by the measurement light MX1 incident on the grating pattern 12Xa from the inclined mirror 32XA at the incident angle φ1 is substantially smaller than the Littrow angle φLI by an angle β as follows. .
φ2 ≒ φLI-β (3)
Further, the measurement light MX2 incident on the reflection surface of the inclined mirror 34XA is reflected by the reflection surface, and is incident on the grating pattern surface 12Xb so that the incident angle in the θy direction (X direction) is symmetric with the measurement light MX1. Incident at (−φ1). The incident angle in the X direction of the measurement light MX2 has an absolute value larger by an angle β than the Littrow angle (−φLI) of the −1st order diffracted light with respect to the grating pattern 12Xa. The incident angle of the measurement light MX2 in the θx direction (Y direction) is, for example, about the same as the incident angle of the measurement light MX1 in the Y direction. The diffraction angle of the minus first-order diffracted light EX1 from the diffraction grating 12X by the measurement light MX2 incident on the grating pattern 12Xa from the inclined mirror 34XA at the incident angle (−φ1) is opposite in sign to the diffraction angle φ2 of the diffracted light DX1. Further, the reflection angles of the zero-order light (regular reflection light) M10 and M20 from the lattice pattern 12Xa by the measurement lights MX1 and MX2 are −φ1 and φ1, respectively.

For this reason, in the present embodiment, the angle (crossing angle) in the θy direction between the 0th-order light M10 and the −1st-order diffracted light EX1 of the measurement light MX1 is approximately 2 · β. Accordingly, even if the 0th-order light M10 and the −1st-order diffracted light EX1 are merged, an interference fringe with a short period is only formed, and the measurement error becomes extremely small.
The diffracted lights DX1 and EX1 from the grating pattern 12Xa are reflected substantially in the −Y direction by the reflecting surfaces of the inclined mirrors 32XA and 34XA, respectively, and become S-polarized light through the quarter-wave plate 30 in FIG. Then, the light enters the PBSs 28A and 28B and is reflected by the polarization beam splitter surface.

As shown in FIG. 2, the diffracted lights DX1 and EX1 reflected by the polarization beam splitter surfaces of the PBSs 28A and 28B are reflected by the corner cubes 29A and 29B, respectively, and then reflected again by the second floor portion of the polarization beam splitter surface. Then, the light is incident on the reflecting surfaces of the second inclined mirrors 32XB and 34XB through the quarter-wave plate 30.
In FIG. 1B, the diffracted light DX1 incident on the reflecting surface of the inclined mirror 32XB on the second floor is reflected by the reflecting surface and enters the diffraction grating 12X substantially parallel to the measuring light MX1. Accordingly, the incident angle φ1 of the diffracted light DX1 in the X direction is also substantially larger by the angle β than the Littrow angle φLI. The diffraction angle φ2 of the + 1st order diffracted light DX2 (+ 2nd order diffracted light with respect to the measurement light MX1) from the grating pattern 12Xa by the diffracted light DX1 is substantially the same as the diffraction angle of the diffracted light DX1.

  Further, the diffracted light EX1 incident on the reflecting surface of the inclined mirror 34XB on the second floor is reflected by the reflecting surface and enters the diffraction grating 12X substantially parallel to the measuring light MX2. Therefore, the incident angle in the X direction of the diffracted light EX1 is approximately −φ1. The diffraction angle of the −1st order diffracted light EX2 (−2nd order diffracted light with respect to the measurement light MX2) from the grating pattern 12Xa by the diffracted light EX1 incident from the inclined mirror 34XB is approximately −φ2. The reflection angles of the 0th-order light (regular reflection light) D10 and E10 from the grating pattern 12Xa by the diffracted light DX1 and EX1 are approximately −φ1 and φ1, respectively. In FIG. 1B, actually, the positions in the X direction on the diffraction grating 12X where the measurement light (diffracted light) from the inclined mirrors 32XA and 34XB is incident are substantially equal, and the diffraction from the inclined mirrors 32XB and 34XA is performed. The positions in the X direction on the diffraction grating 12X where light (measurement light) enters are substantially equal.

  Therefore, the angle (crossing angle) in the θy direction between the 0th-order light D10 (E10) and the diffracted light EX2 (diffracted light DX2) of the diffracted light DX1 (EX1) is approximately 2 · β. Therefore, even if the 0th-order light D10 and the like and the diffracted light EX2 and the like merge, only an interference fringe with a short period is formed, and the measurement error becomes extremely small. Here, assuming that the beam diameters of the measurement lights MX1 and MX2 (average wavelength λ) are d, the period of interference fringes formed by the merge of the 0th-order light D10 and the diffracted light EX2 is 1 / of the beam diameter d. If it is about 50 or less (if 50 or more interference fringes are formed), the fluctuation component (noise component) caused by the 0th-order light of the detection signal obtained by photoelectrically converting the obtained interference fringes is almost the same. It becomes 2% or less, and the measurement error becomes extremely small. The conditions at this time are as follows. However, the angle β is represented by rad.

d · 2 · β ≧ 50λ (4)
Here, as an example, when the beam diameter d is 1 mm and the wavelength λ is 0.633 μm, the angle β satisfying the equation (4) is as follows.
β ≧ 0.0158 (rad) = 0.91 ° (5)
Accordingly, if the beam diameters of the measurement lights MX1 and MX2 are about 1 mm, the deviation angle β of the incident angle in the X direction of the measurement lights MX1 and MX2 with respect to the Littrow angle is 0.91 ° or more, for example, about 1 °. It is preferable. Note that when the shift β of the incident angles of the measurement beams MX1 and MX2 with respect to the Littrow angle increases, the lateral shift amount of the diffracted beams DX1 and EX1 increases with respect to the change in the position of the grating pattern surface 12Xa in the Z direction, and the relative position. Since the intensity of the interference light including information becomes small, it is better not to make the angle β too large within the range satisfying Expression (5).

The diffracted beams DX2 and EX2 from the grating pattern 12Xa are reflected in the substantially −Y direction by the reflecting surfaces of the inclined mirrors 32XB and 34XB, respectively, and become P-polarized light via the quarter-wave plate 30 in FIG. It enters 28B and passes through the polarization beam splitter surface.
As shown in FIG. 2, the diffracted lights DX2 and EX2 transmitted through the PBSs 28A and 28B of the diffracted light generator 26X are converted into S-polarized light through the half-wave plates 27, respectively, and then reflected by the optical path changing member 24X. The light is reflected substantially in the + X direction by the surface 25C and the mirror 36X. Then, the reflected diffracted lights DX2 and EX2 are incident on PBSs 38XA and 38XB and synthesized coaxially with the reference lights RX1 and RX2, respectively, and then photoelectrically converted into interference light (heterodyne beam) via a polarizing plate (not shown). The light enters the sensors 40XA and 40XB.

  In FIG. 1A, photoelectric sensors 40XA and 40XB supply detection signals SXA and SXB (heterodyne signals) obtained by photoelectrically converting incident interference light to the measurement calculation unit 42X. As an example, the measurement calculation unit 42X uses the detection signal SXA and the reference signal supplied from the laser light source 16, and the relative movement amount in the Z direction and the relative movement amount in the X direction of the second member 7 with respect to the first member 6. Is obtained (Z + X). Further, the measurement calculation unit 42X determines, based on the detection signal SXB and its reference signal, the difference (Z−X) between the relative movement amount in the Z direction and the relative movement amount in the X direction of the second member 7 with respect to the first member 6. ) And the measurement calculating part 42X can obtain | require the relative movement amount (X) to the X direction of the 2nd member 7 with respect to the 1st member 6 by averaging the difference of the sum and difference, The sum And the difference are averaged, the relative movement amount (Z) of the second member 7 with respect to the first member 6 in the Z direction can be obtained. The detection resolution of the relative movement amount in the X direction and the Z direction is, for example, about 0.5 to 0.1 nm.

  In the present embodiment, the interference light between the second + 1st order diffracted light DX2 and the reference light RX1 and the interference light between the second + 1st order diffracted light EX2 and the reference light RX2 are finally detected. Detection resolution (detection accuracy) can be improved to 1/2 (miniaturization). Further, by using the second diffracted light and using the ± first-order diffracted light, the measurement error due to the relative rotation angle in the θz direction between the first member 6 and the second member 7 can be reduced.

Next, with respect to a plurality of methods for setting the incident angle of the measurement light MX1 incident on the grating pattern surface 12Xb of the diffraction grating 12X from the inclined mirror 32XA to φ1 (= φLI + β), for example, FIGS. This will be described with reference to FIGS. These methods can also be applied to angle adjustment of the other tilt mirrors 32XB, 34XA, 34XB.
First, as preparation for setting the tilt angle, as shown in the perspective view in FIG. 3A, the reflecting surface of the tilted mirror 32XA is tilted 45 ° around the axis parallel to the X axis from the state parallel to the XZ plane. . At this time, the light beam LA incident on the reflecting surface of the inclined mirror 32XA parallel to the Y-axis is reflected in the −Z direction by the reflecting surface, and is a diagram viewed from the A direction in FIG. As shown in A), the light is incident perpendicular to the grating pattern surface 12Xb of the diffraction grating 12X. In this state, the light beam LA is used as the measurement light MX1, and as shown in the perspective view in FIG. 3B, the measurement light MX1 and the inclined mirror 32XA are arranged on an axis parallel to the Y axis (incident measurement light MX1). Rotates integrally around the Littrow angle φLI. At this time, as indicated by an arrow B in FIG. 3B, the measurement light MX1 reflected by the inclined mirror 32XA is incident on the diffraction grating 12X at an incident angle φLI in the θy direction (X direction). Furthermore, as a first method, the incident angle of the measurement light MX1 with respect to the diffraction grating 12X can be set to φ1 by setting the rotation angle of the measurement light MX1 and the tilt mirror 32XA as an integral unit to φ1 (= φLI + β). By fixing the tilting mirror 32XA to a frame (not shown) in this state, the incident angle in the X direction of the measuring light MX1 becomes φ1.

  Next, as a second method, as shown in FIG. 3B, the measurement light MX1 and the tilt mirror 32XA are tilted in a state where the measurement light MX1 and the tilt mirror 32XA are integrally rotated around the axis parallel to the Y axis by the Littrow angle φLI The mirror 32XA may be fixed to a frame (not shown). In this case, as shown in the perspective view of FIG. 3C, the incident measurement light MX1 is inclined from the state parallel to the Y axis by an angle α in the θz direction. The dotted optical path MX0 is an optical path before the measurement light MX1 is inclined by the angle α. At this time, the incident angle in the X direction with respect to the diffraction grating 12X of the measurement light MX1 reflected by the inclined mirror 32XA is an angle (φLI + β) as indicated by an arrow CX in FIG. Further, the incident angle of the measurement light MX1 in the Y direction is an angle γ as shown by an arrow CY in FIG. The relationship between the angles α, β, and γ is as follows.

β = α cos φLI (6A), γ = α sin φLI (6B)
Therefore, by determining the angle α so that the angle β in the equation (6A) is, for example, about 1 °, the incident angle in the X direction of the measuring light MX1 with respect to the diffraction grating 12X can be shifted from the Littrow angle by a predetermined angle. . At this time, the incident angle of the measurement light MX1 in the Y direction is set to a value determined by Expression (6B). The angle α can be adjusted by, for example, the angles of the half mirror surface 25A and the reflection surface 25B of the optical path changing member 24X in FIG.

  Next, in the third method, as shown in FIG. 4A, the measurement light MX1 and the tilt mirror 32XA are integrally rotated by an angle (φLI + 3 · β) around an axis parallel to the Y axis. Thus, the inclined mirror 32XA is fixed to a frame (not shown), and a wedge-shaped prism 62 having a predetermined opening angle δ in the θz direction is disposed between the inclined mirror 32XA and the diffraction grating 12X. At this time, as shown in FIG. 4B, which is a view seen from the B direction in FIG. 4A, the opening angle δ is set so that the deflection angle of incident light by the wedge prism 62 becomes 2 · β. Has been. As a result, the measurement light MX1 reflected by the inclined mirror 32XA and incident on the wedge-shaped prism 62 at an angle (φLI + 3 · β) with respect to the normal direction of the lattice pattern surface 12Xb is 2 in the θy direction by the wedge-shaped prism 62. After β change, the light enters the grating pattern surface 12Xb at an incident angle (φLI + β) in the X direction. Accordingly, the incident angle of the measurement light MX1 with respect to the diffraction grating 12X is set to an angle shifted by β from the Littrow angle.

  Further, the diffraction angle of the + 1st order diffracted light DX1 from the grating pattern surface 12Xb is substantially (φLI−β), and when the diffracted light DX1 passes through the wedge prism 62, the angle in the θy direction changes by 2 · β, and the grating pattern The light enters the reflecting surface of the inclined mirror 32XA at an angle (φLI + β) with respect to the normal direction of the surface 12Xb. Accordingly, by returning the diffracted light DX1 from the reflecting surface to the reflecting surface (or another tilted mirror 32XB) via the corner cube 29A of FIG. 1, the diffracted light DX1 is now free from the wedge prism 62. In this state, the light is incident on the lattice pattern surface 12Xb in the X direction at an incident angle (φLI + β). Therefore, the method using the wedge-shaped prism 62 is particularly when the first diffraction light DX1 by the measurement light MX1 is generated by the diffraction grating 12X and then the second diffraction light DX2 by the diffraction light DX1 is generated from the diffraction grating 12X. It is effective for. That is, it is not necessary to use the wedge-shaped prism 62 when generating the second diffraction light DX2.

  The effects and the like of this embodiment are as follows. The X-axis encoder 10 </ b> X of the present embodiment is an encoder that measures the relative movement amount of the first member 6 and the second member 7 in the X direction. The encoder 10X is provided on the first member 6 and has a diffraction grating 12X in which a grating pattern 12Xa having a periodic direction in the X direction (first direction) is formed. The measurement light MX1 and the reference light that are coherent with each other. And a laser light source 16 for supplying RX1. The encoder 10X is provided on the second member 7, and reflects the measurement light MX1 toward the diffraction grating 12X at an angle φ1 that is shifted from the Littrow angle by a predetermined angle β in the X direction, and the diffraction grating 12X. Of the diffracted light DX1 toward the diffraction grating 12X at an angle φ in the X direction, a photoelectric sensor 40XA for detecting interference light between the diffracted light DX2 from the diffraction grating 12X and the reference light RX1, and a photoelectric sensor A measurement calculation unit 42X that obtains a relative movement amount of the second member 7 in the X direction with respect to the first member 6 using a detection signal SXA of 40XA.

The detection signal SXA accurately calculates the sum of the relative movement amounts in the X direction and the Z direction. However, if the first member 6 and the second member 7 are almost stationary in the Z direction. Can determine the relative movement amount in the X direction from the detection signal SXA.
According to the present embodiment, since the inclined mirrors 32XA and 32XB that reflect the measurement light MX1 and the diffracted light DX1 toward the grating pattern surface 12Xa are provided, the height of the optical system of the encoder 10X in the Z direction (grating pattern surface) The height in the normal direction of 12Xa can be reduced. Therefore, the detection head 14X of the encoder 10X can be easily and compactly installed on the second member 7.

Further, since the incident angles in the X direction of the measurement light MX1 and the diffracted light DX1 from the inclined mirrors 32XA and 32XB toward the grating pattern surface 12Xa are set to be approximately in the vicinity of the Littrow angle φLI of the + 1st order diffracted light of the diffraction grating 12X. Since the lateral shift amount of the diffracted light DX1 is small and the intensity change of the interference light is small with respect to the change in the position (height) of the lattice pattern surface 12Xa in the Z direction, the relative movement amount can always be measured stably. Further, since the incident angles in the X direction of the measurement light MX1 and the diffracted light DX1 toward the grating pattern surface 12Xa are set to an angle changed by an angle β with respect to the Littrow angle φLI, the zeroth order from the diffraction grating 12X. Measurement accuracy can be improved by reducing the influence of light. As the Littrow angle, a Littrow angle of diffracted light of ± 2nd order or higher may be used.
Further, in the conventional encoder device, when the diffraction light is diffracted twice by the diffraction grating when the diffraction efficiency of the diffraction grating is low, there is a large difference in intensity between the reference light and the measurement light. And the intensity of measurement light is extremely small.
In the conventional encoder device, the optical path length of the measurement light changes due to the change in the distance between the detection head and the diffraction grating. In this case, a measurement error occurs due to the wavelength error of the laser light source 16, but in the present embodiment, such a measurement error is extremely small.

In the present embodiment, the measurement light MX1 is diffracted substantially twice by the diffraction grating 12X using the two inclined mirrors 32XA and 32XB, so that the detection resolution can be improved. Note that the interference light between the first-time diffracted light DX1 and the reference light RX1 may be detected using only one inclined mirror 32XA.
Furthermore, in the present embodiment, the second measurement light MX2 detects interference light between the −1st order diffracted light EX2 and the reference light RX2 generated from the diffraction grating 12X via the tilt mirrors 34XA and 34XB. However, for example, interference between the second + 1st order diffracted light DX2 (or first diffracted light DX1) from the tilt mirror 32XB and the second -1st order diffracted light EX2 (or first diffracted light EX1) from the tilted mirror 34XB. Light may be detected, and the relative movement amount in the X direction between the first member 6 and the second member 7 may be obtained from this detection signal.

  As shown in FIG. 4C, the first and second measurement beams MXY1 and MXY2 having two wavelengths λ1 and λ2 are incident on the two-dimensional diffraction grating 12XY almost vertically, for example. The method of this embodiment can also be applied to the case where ± 1st-order diffracted light in the direction and the Y direction is generated and interference light between these diffracted light and reference light is detected. That is, interference light between the reference light RXY2 separated from the first measurement light MXY1 and the second measurement light MXY2 is detected, and the reference light RXY1 separated from the second measurement light MXY2 and the first measurement light MXY1 are detected. Interference light may be detected.

[First embodiment]
The first embodiment will be described with reference to FIG. 5, parts corresponding to those in FIG. 1A are denoted by the same reference numerals and detailed description thereof is omitted. FIG. 5 shows a schematic configuration of the two-dimensional encoder device 8 according to the first embodiment. The encoder device 8 determines the relative movement amount in the direction of at least two orthogonal axes (X and Y axes) between a first member (not shown) and a second member (not shown). Encoder 10X and Y-axis encoder 10Y. The encoders 10X and 10Y are fixed to a diffraction grating 12X whose periodic direction is the X direction fixed to a first member (not shown) and a diffraction grating 12Y whose periodic direction is the Y direction, and a second member (not shown). An X-axis detection head 14X and a Y-axis detection head 14Y. The encoders 10X and 10Y have a common laser light source 16 and a measurement calculation unit 42.

  In the X-axis detection head 14X, the P-polarized laser light emitted from the laser light source 16 and branched by the PBS (polarization beam splitter) 18 is a half-wave plate 20A and a pair of declination prisms for direction adjustment. Then, the light enters the PBS 22X. The P-polarized reference light transmitted through the PBS 22X is split by the half mirror 58A into a Y-axis reference light RY and a local interference signal generating light beam MXL. The light beam MXL is incident on the PBS 38L as P-polarized light through the mirror 52B, the deflection prism 56, and the polarization adjusting half-wave plate 54 (which may be omitted here).

  In the Y-axis detection head 14Y, the S-polarized laser beam branched by the PBS 18 and supplied via the mirror 52A is incident on the PBS 22Y via the half-wave plate 20B and the deflection prism 56. Reference light of P-polarized light (polarization direction opposite to that in the example of FIG. 1A) transmitted through the PBS 22Y is split by the half mirror 58B into an X-axis reference light RX and a light beam MYL for generating a local interference signal. Is done. The light beam MYL is incident on the PBS 38L as S-polarized light through the half-wave plate 54A. The detection heads 14X and 14Y have a two-story structure, the half mirror 58B, PBS 38L, etc. are on the first floor, the later-described PBS 38YA, etc. are on the second floor, and the light beam MYL passes through the bottom of the PBS 38YA. ing.

  The light beams MXL and MYL incident on the PBS 38L are combined coaxially, and then enter the photoelectric sensor 40L that is the same as the photoelectric sensor 40XA as local interference light via the deflection prism 56 and the polarizing plate 60. The photoelectric sensor 40L outputs the detection signal of the local interference light to the measurement calculation unit 42. The detection signal can be used instead of a reference signal supplied from the laser light source 16 to the measurement calculation unit 42, for example.

  The Y-axis reference light RY that has passed through the half mirror 58A is reflected in the + X direction by the first reflecting surface of the two-surface mirror member 52C, and then reflected by the corner cube 46A and moves to the second floor. The reference light RY traveling in the −X direction in the second floor portion is transmitted through the plurality of glass plates 47A for setting the optical path length substantially the same as the optical member on the optical path of the Y-axis measurement light MY, and the roof prism 48 Is reflected in the + X direction. The reference light RY reflected in the + X direction is split by the half mirror 58C into first and second P-polarized Y-axis reference lights RY1 and RY2. The reference light RY1 enters the PBS 38YA in the −Y direction via the deflection prism 56, and the reference light RY2 is reflected by the mirror 52E and then enters the PBS 38YB in the −Y direction via the deflection prism 56.

  On the other hand, the X-axis reference light RX that has passed through the half mirror 58B is reflected in the −X direction by the mirror 52 on the first floor, passes through the plurality of glass plates 47A, and then is reflected by the corner cube 46B. Move to the floor. The reference light RX traveling in the + X direction at the second floor portion is transmitted through a plurality of glass plates 47B for optical path length adjustment, and the first and second P-polarized X-axis reference lights RX1, RX2 are transmitted by the half mirror 58D. It is divided into. The reference light RX1 is incident on the PBS 38XA in the −Y direction via the deflection prism 56, and the reference light RX2 is reflected by the second reflecting surface of the two-surface mirror member 52C, and then −Y via the deflection prism 56. Incident in PBS38XB in the direction. An optical system 44XY for reference light common to the detection heads 14X and 14Y is constituted by the two-surface mirror member 52C, the corner cubes 46A and 46B, the roof prism 48, the glass plates 47A and 47B, and the like.

  In the X-axis detection head 14X, the measurement light MX reflected by the PBS 22X is incident on the diffracted light generator 26X via the optical path changing member 24X, and the + 1st order diffracted light from the diffraction grating 12X by the diffracted light generator 26X. DX2 and -1st order diffracted light EX2 are generated. In the diffracted light generator 26X of FIG. 5, a phase correction plate 31 for correcting a phase change of the measurement light in the diffraction grating 12X is provided on the surface of the quarter wavelength plate 30. The diffracted light DX2 passes through the optical path changing member 24X and enters the PBS 38XA as S-polarized light in the + X direction. The diffracted light DX2 and the reference light RX1 synthesized coaxially in the −Y direction by the PBS 38XA are the polarizing plate 60 and the deflection prism 56. Is received by the photoelectric sensor 40XA as interference light. The diffracted light EX2 passes through the mirror 36X and enters the PBS 38XB as S-polarized light in the + X direction. The diffracted light EX2 and the reference light RX2 synthesized coaxially in the −Y direction by the PBS 38XB pass through the polarizing plate 60 and the deflection prism 56. The interference light is received by the photoelectric sensor 40XB. At this time, by adjusting the plurality of pairs of declination prisms 56, the interference fringes formed from the diffracted beams DX2 and EX2 and the reference beams RX1 and RX2 are adjusted to be, for example, one or less as a whole.

  The Y-axis detection head 14Y is basically configured by rotating the X-axis detection head 14X by 90 °. In the Y-axis detection head 14Y, the S-polarized measurement light MY reflected by the PBS 22Y is diffracted in the Y-axis as two measurement lights MY1 and MY2 separated in the Y direction via the mirror 37Y and the optical path changing member 24Y. It enters the light generator 26Y. The diffracted light generator 26Y is configured by rotating the X-axis diffracted light generator 26X by 90 °. Note that the two pairs of inclined mirrors above the diffraction grating 12Y in the diffracted light generator 26Y are the inclined mirrors 32YA, 32YB and 34YA, 34YB. The diffracted light generator 26Y generates second + 1st order diffracted light DY2 and −1st order diffracted light EY2 from the diffraction grating 12Y. The diffracted beams DY2 and EY2 pass through the space (second floor portion) above the optical path changing member 24Y in the + X direction, and the diffracted beam DY2 is incident on the PBS 38YA as S-polarized light and is coaxially combined in the −Y direction by the PBS 38YA. The diffracted light DY2 and the reference light RY1 are received by the photoelectric sensor 40YA as interference light through the polarizing plate 60 and the deflection prism 56. The diffracted light EY2 is incident on the PBS 38YB as S-polarized light, and the diffracted light EY2 and the reference light RY2 synthesized coaxially in the −Y direction by the PBS 38YB are supplied to the photoelectric sensor 40YB as interference light through the polarizing plate 60 and the deflection prism 56. Is received.

At this time, by adjusting the plural pairs of declination prisms 56, the interference fringes formed from the diffracted beams DY2 and EY2 and the reference beams RY1 and RY2 are adjusted, for example, to be within one as a whole.
Detection signals of the photoelectric sensors 40XA, 40XB, 40YA, and 40YB are supplied to the measurement calculation unit 42. In the measurement calculation unit 42, the X direction and the Z direction of the first member and the second member are determined based on the detection signals of the X-axis photoelectric sensors 40XA and 40XB and the reference signal from the laser light source 16 (or the detection signal from the photoelectric sensor 40L). Find the relative amount of movement in the direction. Further, in the measurement calculation unit 42, the Y direction of the first member and the second member is detected from the detection signals of the Y-axis photoelectric sensors 40YA and 40YB and the reference signal from the laser light source 16 (or the detection signal from the photoelectric sensor 40L). And the relative movement amount in the Z direction is obtained.

  At this time, the detection heads 14X and 14Y can be arranged in a compact manner. Further, the angle at which the incident angles in the X and Y directions of the measurement light directed from the inclined mirrors 32XA and 32YA to the grating pattern surfaces of the diffraction gratings 12X and 12Y are changed by an angle β with respect to the Littrow angles of the diffraction gratings 12X and 12Y. Therefore, the amount of lateral shift of the diffracted light is small with respect to the change in the height of the grating pattern surface, the change in the intensity of the interference light is small, and the influence of the 0th-order light from the diffraction gratings 12X and 12Y is reduced. Measurement accuracy can be improved.

[Second Embodiment]
A second embodiment will be described with reference to FIGS. 6 to 8, parts corresponding to those in FIG. 1A are denoted by the same reference numerals, and detailed description thereof is omitted. 6 and 8 show a schematic configuration of an X-axis encoder 10XA according to the second embodiment. 7A is a cross-sectional view taken along line AA in FIG. 6, and FIGS. 7B and 7C are cross-sectional views taken along line BB in FIG. 6, respectively. The encoder 10XA includes a diffraction grating 12X whose periodic direction is the X direction fixed to a first member (not shown), a detection head 14XA fixed to the upper surface of the second member 64, a laser light source 16, and a measurement calculation unit 42XA. Have The detection head 14XA also has a two-story structure.

  In the detection head 14XA, the P-polarized measurement light MX emitted from the laser light source 16 and transmitted through the PBS 18 is incident on the second-layer PBS 18C via the half-wave plate 54 and transmitted through the PBS 18C ( Part of the measurement light MX) is reflected by the beam splitter 70 and enters the local interference light generation PBS 18B via the mirror 72A. The first measurement light MX1 that has passed through the beam splitter 70 enters the PBS (polarization beam splitter) 28 in the -Y direction as P-polarized light through a pair of deflection prisms 56. The S-polarized second measurement light MX2 reflected by the PBS 18C enters the PBS 28 as P-polarized light in the −Y direction via the mirror 72C, the pair of declination prisms 56, and the half-wave plate 54B.

  The S-polarized reference light RX reflected by the PBS 18 is incident on the second-floor PBS 18A via the mirror 52A and the like, the half-wave plate 54, and the deflection prism 56. Actually, the optical path length of the measurement light MX from the PBS 18 to the half-wave plate 54 is substantially equal to the optical path length of the reference light RX from the PBS 18 to the half-wave plate 54. The optical paths of MX and reference light RX are set. Part of the reference light RX reflected by the PBS 18A enters the PBS 18B as S-polarized light. Part of the measurement light MX and part of the reference light RX synthesized coaxially in the −Y direction by the PBS 18B are received by the photoelectric sensor 40L through the polarizing plate 60 as local interference light. The detection signal of the photoelectric sensor 40L is supplied to the measurement calculation unit 42XA.

  As shown in FIG. 7A, the P-polarized reference light RX transmitted through the PBS 18A is applied to an optical path changing member 68A having two polarization beam splitter surfaces (PBS surfaces) 68Aa and 68Ab whose ZX surfaces are inclined by 45 °. Incident. Since the reference light RX is S-polarized with respect to the PBS surfaces 68Aa and 68Ab, it is reflected by the PBS surfaces 68Aa and 68Ab, then moves to the first floor portion, and passes through the half-wave plate 54 to the −Y direction. Is incident on the mirror 72B. As shown in FIG. 8, the reference light RX reflected in the −X direction by the mirror 72B is divided into the reference lights RX1 and RX2 by the half mirror 58C, and the reference light RX1 enters the PBS 28 as S-polarized light in the −Y direction. The reference light RX2 enters the PBS 28 as S-polarized light in the −Y direction via the mirror 72C. As shown in FIGS. 7B and 7C, the measurement beams MX1 and MX2 pass above the half mirror 58C and the mirror 72C and enter the PBS 28.

  In FIG. 6, the P-polarized measurement light MX1 incident on the PBS 28 is transmitted through the PBS surface 28a and reflected by the reflecting surface of the inclined mirror 32XA, and the incident angle in the X direction on the grating pattern 12Xa of the diffraction grating 12X is smaller than the Littrow angle. Incident light is incident at an angle φ1 that is larger by the angle β, and + 1st order diffracted light DX1 is generated from the grating pattern 12Xa. As shown in FIG. 7B, a wedge-shaped prism 62A, a quarter-wave plate 30B, and a phase correction plate 31B that are the same as the wedge-shaped prism 62 in FIG. 4A are provided in the optical path of the diffracted light DX1 (measurement light MX1). Has been placed. The diffracted light DX1 is reflected by the second floor portion of the reflecting surface and enters the PBS 28 with S-polarized light.

  As shown in FIG. 6, the diffracted light DX1 reflected by the PBS surface 28a is reflected by the corner cube 29A, reflected by the PBS surface 28a, and then reflected by the inclined mirror 32XA as shown in FIG. 7B. Incident on the first floor of the surface. The diffracted light DX1 reflected by the reflecting surface is incident on the grating pattern 12Xa through the quarter-wave plate 30B and the phase correction plate 31B at an incident angle φ1 in the X direction, and the second plus first time from the grating pattern 12Xa. The folded light DX2 is generated. The diffracted light DX2 is reflected by the inclined mirror 32XA and incident on the PBS 28 with P-polarized light. As shown in FIG. 6, the diffracted light DX2 transmitted through the PBS surface 28a is reflected by the mirrors 72D and 72E, and a pair of hervings 66 And enters the first floor portion of the optical path combining member 68B.

As shown in FIG. 7B, the optical path combining member 68B has two PBS surfaces 68Ba and 68Bb parallel to the PBS surface of the optical path changing member 68A, and the diffracted light DX2 is not applied to the PBS surfaces 68Ba and 68Bb. S-polarized light. Therefore, the diffracted light DX2 is reflected by the PBS surfaces 68Ba and 68Bb and emitted in the + Y direction at the second floor portion.
Similarly, in FIG. 6, the P-polarized measurement light MX2 incident on the PBS 28 is transmitted through the PBS surface 28a and reflected by the reflecting surface of the inclined mirror 34XA, and is incident on the grating pattern 12Xa at an incident angle (−φ1) in the X direction. Incident light and −1st order diffracted light EX1 from the grating pattern 12Xa are generated. As shown in FIG. 7C, a wedge-shaped prism 62B, a quarter-wave plate 30B, and a phase correction plate 31B, which are the same as the wedge-shaped prism 62 in FIG. 4A, are provided in the optical path of the diffracted light EX1 (measurement light MX2). Has been placed. The diffracted light EX1 is reflected by the second floor portion of the reflecting surface and enters the PBS 28 with S-polarized light. The diffracted light EX1 reflected by the PBS surface 28a is reflected by the corner cube 29B, reflected by the PBS surface 28a, and then enters the first floor portion of the reflecting surface of the inclined mirror 34XA. The diffracted light EX1 reflected by the reflecting surface is incident on the grating pattern 12Xa through the quarter-wave plate 30B and the phase correction plate 31B at an incident angle (−φ1) in the X direction, and the second time from the grating pattern 12Xa. -1st order diffracted light EX2 is generated. The diffracted light EX2 is reflected by the inclined mirror 34XA and enters the PBS 28 with P-polarized light. As shown in FIG. 6, the diffracted light EX2 transmitted through the PBS surface 28a is reflected by the mirrors 72F and 72G and passes through the herving 66. It enters the first floor portion of the optical path combining member 68C. As shown in FIG. 7C, the diffracted light EX2 is emitted in the + Y direction at the second floor portion of the optical path combining member 68C having the same configuration as the optical path combining member 68B.

  On the other hand, in FIG. 8, the S-polarized first reference light RX1 incident on the PBS 28 is reflected in the + X direction by the PBS surface 28a and then parallel to the YZ surface of the mirror 74A via the quarter-wave plate 30A. After being reflected by the reflecting surface, it is incident on the PBS surface 28a as P-polarized light through the quarter-wave plate 30A. The reference light RX1 transmitted through the PBS surface 28a is reflected by the corner cube 29A on the second floor (see FIG. 7B), then reflected by the mirror 74A via the quarter-wave plate 30A, and is ¼. Reflected by the PBS surface 28a through the wave plate 30A. The reflected reference light RX1 is incident on the PBS surface of the optical path combining member 68B as P-polarized light via the mirrors 72H and 72E. The diffracted light DX2 and the reference light RX1 synthesized coaxially on the PBS surface are received by the photoelectric sensor 40XA as interference light through the polarizing plate 60.

  The S-polarized second reference light RX2 incident on the PBS 28 is reflected in the + X direction by the PBS surface 28a, and then reflected by the reflective surface parallel to the YZ surface of the mirror 74B via the quarter-wave plate 30A. Then, the light is incident on the PBS surface 28a as P-polarized light through the quarter-wave plate 30A. The reference light RX2 transmitted through the PBS surface 28a is reflected to the second floor portion by the corner cube 29B (see FIG. 7C), then reflected by the mirror 74B through the quarter-wave plate 30A, and ¼ Reflected by the PBS surface 28a through the wave plate 30A. The reflected reference light RX2 enters the PBS surface of the optical path combining member 68C as P-polarized light via the mirrors 72I and 72G. The diffracted light EX2 and the reference light RX2 synthesized coaxially on the PBS surface are received by the photoelectric sensor 40XB through the polarizing plate 60 as interference light.

  The optical path length from the PBS surface 28a to the reflecting surfaces of the mirrors 74A and 74B is set to be substantially the same as the optical path length from the PBS surface 28a to the diffraction grating 12X via the inclined mirrors 32XA and 34XA, respectively. Further, the reference beams RX1 and RX2 and the diffracted beams DX2 and EX2 pass through substantially the same optical path in the PBS 28 and the corner cubes 29A and 29B. Accordingly, since the reference beams RX1, RX2 and the diffracted beams DX2, EX2 pass through substantially equivalent optical paths, high measurement accuracy can be obtained even if there is a slight temperature change in the environment and / or a temperature change in the atmosphere. can get.

  At this time, by adjusting the plurality of pairs of declination prisms 56 and the herving 66, the interference fringes formed from the diffracted beams DX2 and EX2 and the reference beams RX1 and RX2 are adjusted to be within one overall, for example. . Detection signals of the photoelectric sensors 40XA and 40XB are supplied to the measurement calculation unit 42XA. In the measurement calculation unit 42XA, the X and Z directions of the first member and the second member 64 are determined based on the detection signals of the photoelectric sensors 40XA and 40XB and the reference signal from the laser light source 16 (or the detection signal from the photoelectric sensor 40L). The relative movement amount can be obtained.

  At this time, the detection head 14XA can be compactly arranged. Further, since the incident angle in the X direction of the measurement light from the inclined mirrors 32XA and 34XA toward the grating pattern surface of the diffraction grating 12X is set to an angle changed by an angle β with respect to the Littrow angle of the diffraction grating 12X, The lateral shift amount of the diffracted light is small with respect to the change in the height of the pattern surface, the change in the intensity of the interference light is small, and the influence of the zero-order light from the diffraction grating 12X can be reduced to improve measurement accuracy.

[Third embodiment]
A third embodiment will be described with reference to FIGS. FIG. 9 shows a schematic configuration of an exposure apparatus EX provided with an encoder apparatus according to the third 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. 11) 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. 11 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. 9, the projection unit PU arranged 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. 11) 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.

  In FIG. 9, 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 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. 11) 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. 11) for aligning the wafer W, an irradiation system 90a, and a light receiving system 90b. An oblique incidence type multipoint autofocus sensor 90 (see FIG. 11) 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-described local immersion apparatus 108, the plate body 128 is further shown in the plan view of 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 Y-axis first and second diffraction gratings 12Y1 and 12Y2 elongated in the X direction are disposed on the upper surface of the peripheral portion 128e so as to sandwich the plate portion 128a in the Y direction, and the plate portion 128a is sandwiched in the X direction. In this way, a pair of X-axis diffraction gratings 12X1 and 12X2 elongated in the Y direction are arranged. The reflection type diffraction gratings 12X1 and 12X2 having the X direction as the periodic direction have the same configuration as the diffraction grating 12X in FIG. 1, and the diffraction gratings 12Y1 and 12Y2 having the Y direction as the periodic direction are configured by rotating the diffraction grating 12X by 90 °. It is.

  In FIG. 9, 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 14X having the same configuration as the X-axis detection head 14X in FIG. 5 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 14Y having the same configuration as the Y-axis detection head 14Y in FIG. 5 are fixed (see FIG. 10). In addition, a plurality of laser light sources (not shown) for supplying laser light (measurement light and reference light) to the plurality of detection heads 14X and 14Y are also provided. The detection head 14XA of FIG. 6 may be used instead of the detection head 14X, or a detection head having a configuration in which the detection head 14XA is rotated by 90 ° may be used instead of the detection head 14Y.

  In FIG. 10, during the period in which the wafer W is exposed with illumination light from the projection optical system PL, any two of the plurality of detection heads 14X always face the X-axis diffraction gratings 12X1 and 12X2, and the plurality of detection heads. Any two of 14Y are configured to face Y-axis diffraction gratings 12Y1 and 12Y2. Each detection head 14X irradiates the diffraction grating 12X1 or 12X2 with measurement light, and outputs a detection signal of interference light between the diffraction light generated from the diffraction gratings 12X1 and 12X2 and the reference light to the corresponding measurement calculation unit 42X (FIG. 11). Supply. In the measurement calculation unit 42X, as in the measurement calculation unit 42 in FIG. 1, the relative position (relative movement amount) between the wafer stage WST and the measurement frame 150 in the X direction and Z direction is, for example, a resolution of 0.5 to 0.1 nm. And supplied to the measured value switching unit 80X. In the measurement value switching unit 80X, information on the relative position supplied from the measurement calculation unit 42X corresponding to the detection head 14X facing the diffraction gratings 12X1 and 12X2 is supplied to the main controller 120.

  In addition, each detection head 14Y irradiates the diffraction grating 12Y1 or 12Y2 with measurement light, and the measurement calculation unit 42Y corresponding to the detection signal of the interference light between the diffraction light generated from the diffraction gratings 12Y1 and 12Y2 and the reference light (FIG. 11). ). In the measurement calculation unit 42Y, as in the measurement calculation unit 42X, the relative positions (relative movement amounts) of the wafer stage WST and the measurement frame 150 in the Y direction and Z direction are obtained with a resolution of 0.5 to 0.1 nm, for example. The measured value switching unit 80Y is supplied. In the measurement value switching unit 80Y, information on the relative position supplied from the measurement calculation unit 42Y corresponding to the detection head 14Y facing the diffraction gratings 12Y1 and 12Y2 is supplied to the main controller 120.

  A plurality of detection heads 14X, a laser light source (not shown), a measurement calculation unit 42X, and an X-axis diffraction grating 12X1, 12X2 constitute an X-axis encoder 10XB, and a plurality of detection heads 14Y, a laser light source (not shown), A Y-axis encoder 10YB is composed of the measurement calculation unit 42Y and the Y-axis diffraction gratings 12Y1 and 12Y2. An encoder device 8B is configured by the X-axis encoder 10XB, the Y-axis encoder 10YB, and the measurement value switching units 80X and 80Y. 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 heads 14X and 14Y, since the optical path lengths of the measurement light and the diffracted light are shorter than those of the laser interferometer, the influence of air fluctuations on the measurement values using the detection heads 14X and 14Y is very small. Therefore, 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 heads 14X and 14Y can be configured compactly with a low height in the Z direction, a plurality of detection heads 14X and 14Y can be easily installed on the bottom surface of the measurement frame 150 or the like.

In this embodiment, the detection heads 14X and 14Y and the like are arranged on the measurement frame 150 side, and the diffraction gratings 12X1 and 12Y1 and the like are arranged on the wafer stage WST side. As another configuration, the diffraction gratings 12X1, 12Y1, etc. may be arranged on the measurement frame 150 side, and the detection heads 14X, 14Y, etc. may be arranged on the wafer stage WST side.
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) Process, bonding process, packaging process, etc.) 225 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 10X and the encoder devices 8 and 8B of the above-described embodiment or example are the objects in an optical apparatus including an optical system for an object to be inspected or processed, such as an inspection apparatus or a measurement apparatus other than the exposure apparatus. It can be applied to measure the relative movement amount.
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, MX1, MX2 ... measurement light, RX1, RX2 ... reference light, 10X ... X-axis encoder, 12X ... X-axis diffraction grating, 14X ... X-axis detection head, 16 ... Laser light source, 27 ... 1/2 wavelength plate, 28A, 28B ... PBS (polarization beam splitter), 29A, 29B ... Corner cube, 30 ... ¼ wavelength plate, 32XA, 32XB ... + 1-order diffracted light mirror , 34XA, 34XB, tilt mirror for -1st order diffracted light, 40XA, 40XB, photoelectric sensor, 42X, measurement calculation unit

Claims (20)

An encoder device that measures a relative movement amount of a second member that moves relative to the first member in at least a first direction,
A reflective diffraction grating provided on one of the first member and the second member and having a grating pattern having the first direction as a periodic direction;
A light source unit for supplying first and second measurement light;
The first measurement light provided on the other of the first member and the second member and supplied from the light source unit is directed toward the diffraction grating at a first angle with respect to a normal line of the surface of the diffraction grating. A first optical member that irradiates and irradiates the first measurement light diffracted by the diffraction grating toward the diffraction grating at a second angle with respect to the normal ;
The second measurement light provided on the other of the first member and the second member and supplied from the light source unit is directed toward the diffraction grating at a third angle with respect to a normal line of the surface of the diffraction grating. A second optical member that irradiates and irradiates the second measurement light diffracted by the diffraction grating toward the diffraction grating at a fourth angle with respect to the normal line ;
A photoelectric detector that photoelectrically detects the first measurement light diffracted by the diffraction grating and the second measurement light diffracted by the diffraction grating;
Using a detection signal of the photoelectric detector, and a measuring unit for obtaining a relative movement amount of the second member,
The traveling direction of the first measurement light irradiated on the diffraction grating at the first angle and the second measurement light irradiated on the diffraction grating at the third angle and regularly reflected by the diffraction grating. Non-parallel to the direction of travel,
The traveling direction of the first measurement light applied to the diffraction grating at the second angle and the second measurement light applied to the diffraction grating at the fourth angle and regularly reflected by the diffraction grating. An encoder apparatus characterized by being non-parallel to the traveling direction .   The traveling direction of the second measurement light applied to the diffraction grating at the third angle, and the first measurement light applied to the diffraction grating at the first angle and regularly reflected by the diffraction grating. Non-parallel to the direction of travel,
  The traveling direction of the second measurement light applied to the diffraction grating at the fourth angle, and the first measurement light applied to the diffraction grating at the second angle and regularly reflected by the diffraction grating. The encoder apparatus according to claim 1, wherein the encoder apparatus is non-parallel to the traveling direction.   The traveling direction of the first measurement light irradiated on the diffraction grating at the first angle and the traveling direction of the second measurement light irradiated on the diffraction grating at the third angle are the same as those of the diffraction grating. The encoder apparatus according to claim 1, wherein the encoder apparatus is symmetric with respect to a normal line of the surface.   4. The encoder device according to claim 1, wherein the first angle is equal to the second angle, and the third angle is equal to the fourth angle. 5. The first optical member has an incident angle in the first direction of the first measurement light traveling from the first optical member toward the surface of the diffraction grating to an angle changed by a predetermined angle with respect to the Littrow angle of the diffraction grating. setting encoder device according to any one of claims 1 to 4, characterized in that.   The encoder apparatus according to claim 5, wherein the predetermined angle is larger than 0.5 °.   The encoder apparatus according to claim 5, wherein the predetermined angle is 0.5 ° to 1.5 °.   When the predetermined angle is β, the beam diameters of the first and second measurement lights are d, and the wavelengths of the first and second measurement lights are λ,
    d × 2β ≧ 50λ
The encoder device according to claim 5, wherein: The first optical member includes a first reflection member that reflects the first measurement light, and an incident angle in the first direction of the first measurement light that travels from the first reflection member toward the surface of the diffraction grating. The encoder device according to any one of claims 5 to 8 , further comprising an angle adjusting member that sets the angle changed by the predetermined angle with respect to the Littrow angle. An optical path bending member that makes the first measurement light output from the light source unit substantially parallel to the surface of the diffraction grating of the diffraction grating ;
The first optical member causes the first measurement light having passed through the optical path bending member to enter the surface of the diffraction grating at the Littrow angle,
The optical path bending member reflects the first measurement light by being inclined by an angle corresponding to the predetermined angle with respect to a second direction orthogonal to the first direction within a plane parallel to the surface of the diffraction grating. The encoder device according to any one of claims 5 to 9, wherein The angle adjusting member is provided between the first reflecting member and the surface of the diffraction grating, and a deflection angle in an incident surface of the first measurement light with respect to the surface of the diffraction grating is set according to the predetermined angle. The encoder device according to claim 9 , wherein the encoder device is a wedge-shaped prism set to an angle. A re-reflecting member that reflects the first measurement light diffracted by the diffraction grating so that the incident angle in the first direction changes to the Littrow angle on the surface of the diffraction grating ;
The encoder apparatus according to claim 11 , wherein a deflection angle of the wedge-shaped prism is twice the predetermined angle. The second optical member has an incident angle in the first direction of the second measurement light directed from the second optical member toward the surface of the diffraction grating, a predetermined angle with respect to a Littrow angle whose sign is opposite to the Littrow angle. The encoder device according to any one of claims 5 to 12 , wherein the changed angle is set. The light source unit is
A separation optical member having a separation surface for separating the first and second measurement lights and the first and second reference lights from a light beam emitted from a light source;
A reference reflecting member that has a reflecting surface having substantially the same optical path length to the surface of the diffraction grating with respect to the separation surface, and reflects the first and second reference lights on the reflecting surface. The encoder apparatus as described in any one of Claims 1 thru | or 13 . The measurement unit obtains a relative movement amount in the first direction of the second member and a relative movement amount in a normal direction of the surface of the diffraction grating using a detection signal of the photoelectric detector. Item 15. The encoder device according to any one of Items 1 to 14 . The grating pattern of the diffraction grating also has periodicity in a second direction orthogonal to the first direction,
The light source unit further supplies third and fourth measurement light,
Provided on the other of the first member and the second member, irradiates the third measurement light supplied from the light source unit toward the surface of the diffraction grating, and diffracts in the second direction by the diffraction grating. A third optical member that receives the measured third measurement light;
Provided on the other of the first member and the second member, irradiates the fourth measurement light supplied from the light source unit toward the surface of the diffraction grating, and diffracts in the second direction by the diffraction grating A fourth optical member that receives the measured fourth measurement light,
The photoelectric detector photoelectrically detects the third measurement light diffracted by the diffraction grating and the fourth measurement light diffracted by the diffraction grating,
The third optical member has a traveling direction of the third measurement light regularly reflected by the diffraction grating, and a traveling direction of the fourth measurement light incident on the third optical member after being diffracted by the diffraction grating. the encoder apparatus according to any one of claims 1 to 15, characterized in that set in different directions. The photoelectric detector is
First and second detectors for detecting interference light between the first and second measurement lights and the first and second reference lights separated from the third and fourth measurement lights, respectively;
A third and a fourth detector for detecting interference light between the third and fourth measurement lights and the third and fourth reference lights separated from the first and second measurement lights, respectively;
A first and second light amount ratio for adjusting the light amount ratio of the third and fourth measurement lights to the first and second reference lights and a light amount ratio of the first and second measurement lights to the third and fourth reference lights. The encoder device according to claim 16 , further comprising an adjustment member. An encoder device according to any one of claims 1 to 17 ,
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 the 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 the stage in the first direction. A device manufacturing method including a lithography process,
20. A device manufacturing method comprising exposing an object using the exposure apparatus according to claim 19 in the lithography process.

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