JP2013101084A - Position detection method and device, encoder device and exposure device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect the absolute position in a normal direction of a grating pattern face in the case of measuring relative movement quantity by using a diffraction grating.SOLUTION: An origin detection device 11X includes: a reflection type diffraction grating 12X arranged in a first member 6 with an X direction as a periodic direction; a first interference head 14X for making first measurement rays of light MX1 incident to the diffraction grating 12X at a first incidence angle, and for detecting first interference rays of light between diffraction rays of light and first reference rays of light MR1; a second interference head 15X for making third measurement rays of light MX3 incident to the diffraction grating 12X at a second incidence angle which is different from the first incidence angle, and for detecting third interference rays of light between the diffraction rays of light and third reference rays of light MR3; and a third arithmetic part 41C for searching the relative position of a Z direction from the detection signals of the first and third interference rays of light.

Description

  The present invention relates to a position detection technique for detecting a relative position between members that move relative to each other, an encoder apparatus that measures a relative movement amount between these members, an exposure apparatus that includes the encoder apparatus, and a device manufacturing method that uses the exposure apparatus About.

  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, conventionally, the position measurement of a stage that moves a substrate to be exposed is laser interference. It was done by the total. 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

  The conventional encoder device can measure the relative movement amount in units of a predetermined distance or a fraction of this integer with respect to the periodic direction of the diffraction grating and the normal direction of the grating pattern surface of the diffraction grating. That is, the relative position in the normal direction of the grating pattern surface with respect to the member provided with the detection unit of the member provided with the diffraction grating can be measured as an absolute position within the predetermined distance range. It was not possible to measure as an absolute position in the range exceeding the distance of. For this reason, for example, immediately after the power is turned on, the relative position in the normal direction of the lattice pattern surface of the two members cannot be set as an absolute position from a predetermined initial position or the like. For this purpose, a device for detecting an absolute position such as a limit switch is required separately.

  In view of such a problem, the aspect of the present invention is a method of the grating pattern surface of the diffraction grating that exceeds the range where the absolute position can be measured when measuring the relative movement amount when measuring using the diffraction grating. The purpose is to detect the absolute position in the line direction.

  According to the first aspect of the present invention, a position detection device is provided that detects the relative position of the second member that moves relative to the first member. The position detection device is provided on one of the first member and the second member, and has a reflection type diffraction grating having a grating pattern having at least a first direction as a periodic direction, and first measurement light from the diffraction grating. A first interferometer that is incident on the grating pattern surface at a first incident angle in the first direction and detects the first interference light of the first diffracted light and the first reference light from the diffraction grating; and a second measurement A second interference for detecting the second interference light of the second diffracted light and the second reference light from the diffraction grating by causing light to enter the grating pattern surface of the diffraction grating at a second incident angle with respect to the first direction. A first detection of a first relative position in the normal direction of the grating pattern surface of the first member and the second member from the detector, the detection signal of the first interference light, and the detection signal of the second interference light A wavelength of the first measurement light and a wave of the second measurement light , And at least one of which is different from the first incident angle and its second angle of incidence.

  Moreover, according to the 2nd aspect, the position detection method which detects the relative position of the 2nd member which moves relatively with respect to a 1st member is provided. In this position detection method, the first measurement light is provided on the grating pattern surface of a reflection type diffraction grating provided on one of the first member and the second member and having a grating pattern having at least a first direction as a periodic direction. Incident at a first incident angle with respect to the first direction, detecting the first interference light from the first diffraction light and the first reference light from the diffraction grating, and the second measurement light to the grating pattern of the diffraction grating A first incident light incident on the surface at a second incident angle to detect second interference light between the second diffracted light and the second reference light from the diffraction grating, and a detection signal of the first interference light And determining a first relative position in the normal direction of the grating pattern surface of the first member and the second member from the detection signal of the second interference light, and the wavelength of the first measurement light, The wavelength of the second measurement light, the first incident angle, and the second At least one of the incident angle are different.

  Moreover, according to the 3rd aspect, the encoder apparatus which measures the relative movement amount of the 2nd member at least relatively moved with respect to the 1st member is provided. The encoder device includes a position detection device according to a first aspect, and a method of a lattice pattern surface of the first member and the second member from the detection signal of the first interference light or the detection signal of the second interference light. A third detection unit that measures the relative movement amount in the linear direction, and the third detection unit uses the first relative position detected by the first detection unit to measure the relative movement amount measurement value. Preset.

  Moreover, according to the 4th aspect, the exposure apparatus which exposes a pattern to a to-be-exposed body is provided. The exposure apparatus measures 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 a relative position or a relative movement amount of the stage in the first direction. And a position detecting device according to the first aspect or an encoder device according to the third aspect.

  According to the fifth 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 fourth aspect.

  According to the aspect of the present invention, since at least one of the wavelength of the first measurement light and the wavelength of the second measurement light and the first incident angle and the second incident angle are different, the detection signal of the first interference light can be used as a grating. The first position that can measure the absolute position when measuring the relative movement amount in the normal direction of the pattern surface and the absolute position when measuring the relative movement amount in the normal direction from the detection signal of the second interference light It is different from the second length that can be made. And the period of the 1st relative position of the normal direction calculated | required from the detection signal of the 1st and 2nd interference light becomes longer than the 1st length and the 2nd length. Therefore, when measuring using the diffraction grating, the first member and the second member exceed the range (first length or second length) in which the absolute position can be measured when measuring the relative movement amount. The absolute position in the normal direction of the grating pattern surface of the diffraction grating can be detected.

It is a perspective view which shows the encoder which concerns on 1st Embodiment. (A) is a perspective view which shows the 2nd time diffracted light of the 1st interferometer in FIG. 1, (B) is a front view which shows the diffracted light of a 1st interferometer. (A) is a front view showing the diffracted light of the second interferometer of FIG. 1, (B) is a diagram showing a case where the height of the grating pattern surface is relatively changed in the second interferometer, and (C) is the first view. It is a figure which shows the difference signal obtained from the contrast signal obtained from 2 interferometers, and a 1st and 2nd interferometer. It is a figure which shows schematic structure of the exposure apparatus which concerns on 2nd Embodiment. FIG. 5 is a plan view showing an example of an arrangement of a diffraction grating and a plurality of detection heads provided on the wafer stage of FIG. 4. FIG. 5 is a block diagram showing a control system of the exposure apparatus in FIG. 4. It is a flowchart which shows an example of the manufacturing method of an electronic device.

[First Embodiment]
A first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a perspective view showing the main part of an X-axis and Z-axis encoder 10X according to this embodiment. In FIG. 1, 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 is parallel to two directions of the second member 7 that are relatively movable relative to each other. An axis and a Y axis are taken, and an axis orthogonal to a plane (XY plane) defined by the X axis and the Y axis will be described as a Z axis. In the present embodiment, the first member 6 and the second member 7 are relatively movable in the Z direction to some extent. 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. 1, an encoder 10 </ b> X measures a flat plate-shaped X-axis diffraction grating 12 </ b> X parallel to the XY plane fixed to the upper surface of the first member 6 and a diffraction grating 12 </ b> X fixed to the bottom surface of the second member 7. X-axis first interference head 14X (first detection head) and second interference head 15X (second detection head) for irradiating light, and laser light source 16A for supplying laser light for measurement to the interference heads 14X, 15X, 16B, a movement amount detection unit 42X that calculates a relative movement amount of the second member 7 in the X direction and the Z direction with respect to the first member 6 by processing a detection signal output from the first interference head 14X, and two interference heads And an origin signal calculation unit 43X that detects the origin of the absolute position of the second member 7 in the Z direction relative to the first member 6 by processing the detection signals output from 14X and 15X. The movement amount detection unit 42X includes a first calculation unit 41A and a second calculation unit 41B. The origin detection device 11X includes the diffraction grating 12X, the two interference heads 14X and 15X, the laser light sources 16A and 16B, and the origin signal calculator 43X. Therefore, the encoder 10X includes the origin detection device 11X. Further, a Y-axis encoder (not shown) 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.

  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, 1 μm period) 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 sources 16A and 16B are made of, for example, a He—Ne laser or a semiconductor laser. As an example, the first and second linearly polarized light whose polarization directions (X direction and Z direction) are orthogonal to each other and whose frequencies (wavelengths) are different from each other. The two-frequency heterodyne lights XR1 and XR2 made of the laser beam are emitted. The laser light sources 16A and 16B use a reference frequency signal (reference signal) obtained by photoelectrically converting the interference light of two light beams branched from the first and second linearly polarized laser beams as the movement amount detector 42X. The first calculation unit 41A and the fourth calculation unit 41D of the origin signal calculation unit 43X are supplied. Note that the laser light source 16B may be omitted, and a laser beam branched from the heterodyne light output from the laser light source 16A may be supplied to the second interference head 15X via a routing optical system (not shown). In addition to the heterodyne interference method, a homodyne interference method can also be used.

  The heterodyne light XR1 emitted from the laser light source 16A is divided into two by the half mirror 18A of the first interference head 14X, and one light beam is reflected by the mirror 18B and enters a polarization beam splitter (hereinafter referred to as PBS) 28. The other light beam enters the PBS 28 as it is. The two light beams are separated in the X direction and enter the PBS 28 in parallel with the Y axis. One light beam is split into P-polarized first measurement light MX1 that passes through the PBS surface (polarized beam splitter surface) 28a of the PBS 28 and S-polarized first reference light MR1 that is reflected by the PBS surface 28a. The other light beam is split into P-polarized second measurement light MX2 that is transmitted through the PBS surface 28a and S-polarized second reference light MR2 that is reflected by the PBS surface 28a.

  The PBS 28 is fixed to the bottom surface of the second member 7, and the first and second corner cubes 29A and 29B are fixed to the side surface in the + X direction of the PBS 28 so as to be adjacent to the Y direction. The quarter wave plates 30A and 30B are fixed to the side surfaces in the direction, respectively. A mirror 35 having a reflecting surface parallel to the ZY plane is fixed below the second member 7 so as to face the side surface of the PBS 28 in the −X direction. Further, the first tilting mirror 32X for the first measurement light MX1 and the second tilting mirror 34X for the second measurement light MX2 are arranged so as to be supported by the second member 7 on the + Y direction side of the PBS 28. ing. The first interference head 14X includes the half mirror 18A, the mirror 18B, the PBS 28, the corner cubes 29A and 29B, the quarter-wave plates 30A and 30B, the mirror 35, and the inclined mirrors 32X and 34X. The first interference head 14X includes two polarizing plates 39A and 39B arranged in the −Y direction of the PBS 28, and photoelectric sensors 40XA and 40XB such as photodiodes that receive the interference light that has passed through the polarizing plates 39A and 39B. Have

In the first interference head 14X, the measurement lights MX1 and MX2 transmitted through the PBS surface 28a of the PBS 28 are incident on the planar reflecting surfaces of the inclined mirrors 32X and 34X via the quarter-wave plates 30A, respectively. The measurement beams MX1 and MX2 reflected by these reflecting surfaces are incident so as to intersect irradiation positions separated in the X direction on the lattice pattern surface 12Xb.
FIG. 2B is a diagram showing the reflecting surfaces of the inclined mirrors 32X and 34X in FIG. In FIG. 2B, the measurement light MX1 incident on the reflecting surface of the inclined mirror 32X is reflected by the reflecting surface, and the incident angle in the θy direction (X direction) is reflected on the grating pattern surface 12Xb of the diffraction grating 12X. The + 1st order diffracted light is incident on the grating pattern 12Xa at a Littrow angle (Littrow angle) φLI as follows.

  The Littrow angle φLI of the + 1st order diffracted light is an incident angle of the measurement light MX1 when the incident measurement light MX1 is parallel to the + 1st order diffracted light DX1 from the diffraction grating 12X by the measurement light MX1. In FIG. 2B, for easy understanding, the measurement light MX1 and the like and the diffracted light DX1 and the like are shown with slightly different angles. When the period in the X direction of the grating pattern 12Xa is p and the wavelength of the measurement light MX1 is λ, the Littrow angle φLI satisfies the following relationship.

2p · sin φLI = λ (1)
As an example, if the period p of the diffraction grating 12X is 1000 nm and the wavelength λ of the measurement light MX1 is 633 nm, the Littrow angle φLI is approximately 18.5 °.
As described above, when the measurement light MX1 is incident at the Littrow angle φLI, since the lateral shift of the + first-order diffracted light DX1 does not occur even if the height of the grating pattern surface changes, there is an advantage that the intensity of the interference light does not change. There is a possibility that the problem of noise light due to the 0th order light may occur. Therefore, in practice, in order to reduce the influence of the 0th-order light, the incident angle of the measurement light MX1 may be shifted from the Littrow angle φLI by a predetermined angle, for example, about 0.5 to 1.5 °.

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 may also be shifted by, for example, about ½ of the predetermined angle. . The + 1st order diffracted light DX1 by the measurement light MX1 is returned to the tilt mirror 32X in parallel (or substantially in parallel) with the measurement light MX1.
Further, the measurement light MX2 incident on the reflection surface of the inclined mirror 34X is reflected by the reflection surface and is incident on the lattice pattern surface 12Xb so that the incident angle in the θy direction (X direction) is symmetric with the measurement light MX1. Incident at (-φLI). Note that the incident angle of the measurement light MX2 may also be shifted from the angle (−φLI) by a predetermined angle symmetrically with the measurement light MX1. 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 inclination mirror 34X at the incident angle (−φLI) is returned to the inclination mirror 34X in parallel (or substantially parallel) to the measurement light MX2. It is.

  The diffracted beams DX1 and EX1 from the grating pattern 12Xa are reflected in the substantially −Y direction by the reflecting surfaces of the inclined mirrors 32X and 34X, respectively, and become S-polarized light via the quarter-wave plate 30A in FIG. Incident light is reflected by the PBS surface 28a. The diffracted lights DX1 and EX1 reflected by the PBS surface 28a are reflected by the corner cubes 29B and 29A, respectively, and returned to the PBS surface 28a.

  On the other hand, the reference beams MR1 and MR2 reflected by the PBS surface 28a of the PBS 28 are incident on the planar reflecting surface of the mirror 35 via the quarter-wave plate 30B, as indicated by the dotted lines in FIG. Then, the reference beams MR1 and MR2 reflected by the reflecting surfaces become P-polarized light through the quarter-wave plate 30B, enter the PBS 28, pass through the PBS surface 28a, and are received by the corner cubes 29B and 29A, respectively. Reflected and returned to the PBS surface 28a.

  As shown in FIG. 2 (A), the diffracted lights DX1 and EX1 reflected by the corner cubes 29B and 29A and then returned to the PBS surface 28a are reflected again by the PBS surface 28a, and then ¼ wavelength. The light enters the lower position of the reflecting surface of the inclined mirrors 32X and 34X via the plate 30A. The diffracted beams DX1 and EX1 reflected by the inclined mirrors 32X and 34X are incident symmetrically on the irradiation positions on the grating pattern surface 12Xb that are substantially away from the irradiation positions in FIG.

  In FIG. 2B, the diffracted light DX1 that has entered the low position of the reflecting surface of the inclined mirror 32X is reflected by the reflecting surface and incident on the diffraction grating 12X in parallel with the measuring light MX1 at an incident angle φLI (Littrow angle). Incident at. Note that the incident angle of the diffracted light DX1 may also be shifted from the angle φLI by a predetermined angle. The + 1st order diffracted light DX2 (substantially + 2nd order diffracted light with respect to the measurement light MX1) from the grating pattern 12Xa by the diffracted light DX1 is returned to the inclined mirror 32X in parallel (or substantially in parallel) with the diffracted light DX1.

  Further, the diffracted light EX1 that has entered the lower position of the reflecting surface of the inclined mirror 34X is reflected by the reflecting surface, and is incident on the diffraction grating 12X in parallel with the measuring light MX2 (symmetrically with the diffracted light DX1) (− Incident at φLI). Note that the incident angle of the diffracted light EX1 may also be shifted from the angle by a predetermined angle. The −1st order diffracted light EX2 (substantially −2nd order diffracted light with respect to the measurement light MX2) from the grating pattern 12Xa by the diffracted light EX1 is returned to the inclined mirror 34X in parallel (or substantially in parallel) with the diffracted light EX1.

The diffracted beams DX2 and EX2 from the grating pattern 12Xa are reflected almost in the −Y direction by the reflecting surfaces of the inclined mirrors 32X and 34X, respectively, and become P-polarized light through the quarter-wave plate 30A in FIG. Then, the light enters the PBS 28 and passes through the PBS surface 28a. The diffracted lights DX2 and EX2 transmitted through the PBS surface 28a enter the polarizing plates 39A and 39B, respectively.
On the other hand, the reference beams RX1 and RX2 that have been reflected by the corner cubes 29B and 29A and then returned to the PBS surface 28a are again transmitted through the PBS surface 28a, and then reflected by the mirror 35 via the quarter-wave plate 30B. Incident at a low position on the surface. Then, the reference beams RX1 and RX2 reflected by the reflecting surface of the mirror 35 become S-polarized light via the quarter-wave plate 30B, enter the PBS 28, and are reflected by the PBS surface 28a. The reference beams RX1 and RX2 reflected by the PBS surface 28a enter the polarizing plates 39A and 39B, respectively, and are synthesized coaxially with the diffracted beams DX2 and EX2. Then, the + 1st order first interference light (heterodyne beam) composed of the diffracted light DX2 (measurement light MX1) and the reference light RX1 is received by the photoelectric sensor 40XA, and is composed of the diffracted light EX2 (measurement light MX2) and the reference light RX2. First-order first interference light (heterodyne beam) is received by the photoelectric sensor 40XB. In order to make the optical path lengths of the measurement beams MX1, MX2 and the reference beams RX1, RX2 substantially equal, a step may be provided on the reflection surface of the mirror 35 to adjust the distance between the PBS 28 and the mirror 35. The configuration of the first interference head 14X is arbitrary. In short, it is only necessary that the measurement gratings MX1 and MX2 can be irradiated to the diffraction grating 12X with substantially symmetric incident angles.

  In FIG. 1, photoelectric sensors 40XA and 40XB supply detection signals SXA and SXB (heterodyne signals) obtained by photoelectrically converting incident interference light to the first calculation unit 41A of the movement amount detection unit 42X. As an example, the first calculation unit 41A uses the detection signal SXA and the reference signal supplied from the laser light source 16 to move the second member 7 relative to the first member 6 in the Z direction and the relative movement in the X direction. A weighted sum (a · X + b1 · Z) (a and b1 are known coefficients) is obtained, and the obtained values are supplied to the second computation unit 41B and the third computation unit 41C. Furthermore, the first calculation unit 41A calculates a difference between the weights of 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 based on the detection signal SXB and the reference signal. (−a · X + b1 · Z) is obtained, and the obtained value is supplied to the second calculation unit 41B. The second computing unit 41B uses the weighted sum and the difference between the weighted values to calculate the relative movement amount (X) of the second member 7 relative to the first member 6 in the X direction and the second member 7 relative to the first member 6. The relative movement amount (Z) in the Z direction is obtained. Further, the second calculation unit 41B resets the relative movement amount (Z) in the Z direction to 0 in accordance with a reset signal SR supplied from the origin signal calculation unit 43X as described later, and from a control unit (not shown) The relative movement amount (X) in the X direction is reset to 0 according to the supplied reset signal. A value other than 0 may be preset instead of reset. 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.

  The first interference head 14X of the present embodiment finally detects 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. Therefore, the detection resolution (detection accuracy) of the relative movement amount can be improved (miniaturized) to ½. 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, the heterodyne light XR2 emitted from the laser light source 16B enters the PBS (polarization beam splitter) 27 of the second interference head 15X, and is reflected by the PBS surface (polarization beam splitter surface) of the PBS 27. The light is divided into third measurement light MX3 and P-polarized third reference light MR3 that passes through the PBS surface.
The PBS 27 is fixed to the bottom surface of the second member 7, the corner cube 29 </ b> D is fixed to the side surface in the −Y direction of the PBS 27, and the corner is directed diagonally downward so that it is supported by the second member 7 on the + X direction side of the PBS 27. A cube 29C is arranged. The second interference head 15X includes the PBS 27, the corner cubes 29C and 29D, the polarizing plate 39C arranged in the + Y direction of the PBS 27, and the photoelectric sensor 40XC such as a photodiode that receives the interference light that has passed through the polarizing plate 39C. ing.

In the second interference head 15X, the measurement light MX3 reflected by the PBS surface of the PBS 27 enters the grating pattern surface 12Xb of the diffraction grating 12X substantially perpendicularly.
FIG. 3A is a front view showing the second interference head 15X in FIG. In FIG. 3A, in order to reduce the influence of the 0th order light, the measurement light MX3 may be incident on the grating pattern surface 12Xb with a small incident angle (for example, about 0.5 to 1 °). Good. With this measurement light MX3, + 1st order diffracted light FX1 is generated from the grating pattern 12Xa in the θy direction (X direction) with a diffraction angle φ01. Using the period p of the grating pattern 12Xa and the wavelength λ of the measurement light MX3, the diffraction angle φ01 is as follows.

p · sin φ01 = λ (2)
This diffraction angle φ01 is larger than the Littrow angle φLI defined by the equation (1). As an example, if the period p is 1000 nm and the wavelength λ of the measurement light MX3 is 633 nm, the diffraction angle φ01 is approximately 39.3 °, which is approximately twice the Littrow angle φLI. In the present embodiment, the incident angle (approximately 0) of the measurement light MX3 incident on the diffraction grating 12X from the second interference head 15X is equal to the incident angle (almost Littrow) of the measurement light MX1 incident on the diffraction grating 12X from the first interference head 14X. The diffraction angle φ01 of the diffracted light FX1 generated by the measurement light MX3 is smaller than the diffraction angle (substantially Littrow angle φLI) of the diffracted light DX1 generated by the measurement light MX1.

  The + 1st-order diffracted light FX1 by the measurement light MX3 is reflected symmetrically and in parallel by the corner cube 29C, and is substantially reflected on the grating pattern surface 12Xb of the diffraction grating 12X at a position shifted in the −X direction with respect to the incident position of the measurement light MX3. Incident light is incident at an incident angle of φ01. Therefore, the −1st order diffracted light FX2 of the + 1st order diffracted light FX1 is generated substantially vertically upward from the grating pattern surface 12Xb of the diffraction grating 12X, and the generated diffracted light FX2 returns to the PBS 27.

  On the other hand, in FIG. 1, the reference light MR3 transmitted through the PBS surface of the PBS 27 is reflected by the corner cube 29D and transmitted through the PBS surface. Further, the diffracted light FX2 returned to the PBS 27 is reflected by the PBS surface and synthesized coaxially with the reference light MR3. Then, the second interference light (heterodyne beam) composed of the diffracted light FX2 (measurement light MX3) and the reference light RX3 is received by the photoelectric sensor 40XC via the polarizing plate 39C. In order to make the optical path lengths of the measurement light MX3 and the reference light RX3 substantially equal, an optical path routing optical system may be disposed between the PBS 27 and the corner cube 29D.

  The photoelectric sensor 40XC supplies a detection signal SXC (heterodyne signal) obtained by photoelectrically converting incident interference light to the fourth calculation unit 41D and the fifth calculation unit 41E of the origin signal calculation unit 43X. As an example, the fourth calculation unit 41D uses the detection signal SXC and the reference signal supplied from the laser light source 16B, and the relative movement amount in the Z direction and the relative movement in the X direction of the second member 7 relative to the first member 6. A weighted sum (a · X + b2 · Z) (a and b2 are known coefficients) is obtained, and the obtained value is supplied to the third computing unit 41C. The third calculation unit 41C calculates the difference between the weighted sum (a · X + b1 · Z) supplied from the first calculation unit 41A and the weighted sum (a · X + b2 · Z) supplied from the fourth calculation unit 41D for one cycle. A differential signal ΔFZ (detailed later) converted to a value within 2π (rad) is obtained, and this differential signal FZ is supplied to the origin signal output unit 41F.

The fifth calculation unit 41E obtains a contrast signal SC indicating the ratio of the AC signal in the detection signal SXC, and supplies this contrast signal SC to the origin signal output unit 41F. An origin signal computation unit 43X is configured by the first computation unit 41A, the third computation unit 41C, the fourth computation unit 41D, and the origin signal output unit 41F.
In this embodiment, as shown in FIG. 3B, it is assumed that the grating pattern surface 12Xb of the diffraction grating 12X is displaced relative to the second interference head 15X by δz in the Z direction. At this time, since the grating pattern surface 12Xb moves to the position A1 indicated by the two-dot chain line, the optical path of the + 1st order diffracted light FX1 by the measurement light incident on the diffraction grating 12X from the second interference head 15X is shifted to the dotted optical path A2. Then, the optical path of the −1st order diffracted light FX2 generated almost vertically upward from the diffraction grating 12X by the + 1st order diffracted light FX1 is shifted in the X direction by δx to the dotted optical path A3. As a result, when the reference light MR3 and the diffracted light FX2 are combined with the PBS 27, the ratio of the area of the portion where the cross section A4 of the reference light MR3 and the cross section A5 of the diffracted light FX2 overlap is reduced. Further, a signal obtained by photoelectric conversion of the light beam at the portion where the cross section A4 and the cross section A5 overlap is a beat signal (AC signal). When the area of the overlapped portion becomes small, the component of the AC signal in the detection signal SC of FIG. And the contrast signal SC is also reduced.

  As a result, as shown in FIG. 3C, when the relative position in the Z direction of the grating pattern surface 12Xb of the diffraction grating 12X with respect to the second interference head 15X is a predetermined Zc, the fifth calculation unit 41E in FIG. The contrast signal SC outputted from is maximized, and the contrast signal SC becomes small when the relative position in the Z direction deviates from Zc. Therefore, as an example, in the origin signal output unit 41F in FIG. 1, the relative position (Zc) in the Z direction of the lattice pattern surface 12Xb when the contrast signal SC reaches the maximum value is set as a rough origin Zc. This rough origin Zc can be regarded as an absolute position in the sense that almost the same position can be specified with a certain degree of reproducibility even after the encoder 10X is turned off.

Next, the difference signal ΔFZ obtained by the third calculation unit 41C will be described. First, in the third calculation unit 41C, the difference between the weighted sum (a · X + b1 · Z) supplied from the first calculation unit 41A and the weighted sum (a · X + b2 · Z) supplied from the fourth calculation unit 41D is calculated. The original difference signal ΔFZR converted into the phase is obtained as follows.
ΔFZR = 2π {(a · X + b2 · Z) − (a · X + b1 · Z)}
= 2π (b2-b1) Z (3)
Here, the coefficient b1 is as follows using a cycle (hereinafter referred to as a fringe length) Fz1 in the Z direction of the weighted sum (a · X + b1 · Z) detected by using the first interference head 14X. Similarly, the coefficient b2 is as follows using a period (hereinafter referred to as fringe length) Fz2 of the weighted sum (a · X + b2 · Z) detected using the second interference head 15X in the Z direction.

b1 = 1 / Fz1 (4A), b2 = 1 / Fz2 (4B)
The fringe lengths Fz1 and Fz2 are the amount of change in the relative position in the Z direction when the corresponding weighted sum (detection signal) is expressed in phase and the weighted sum value changes by 2π (rad), which is one cycle. It is. As an example, if the period p of the diffraction grating 12X is 1000 nm and the wavelength λ of the measurement lights MX1 to MX3 is 633 nm, the fringe lengths Fz1 and Fz2 (here, Fz1> Fz2) are approximately as follows.

Fz1 = 189 (nm) (5A), Fz2 = 178 (nm) (5B)
Substituting equations (4A) and (4B) into equation (3) yields:
ΔFZR = 2π (1 / Fz2-1 / Fz1) Z
= 2π {(Fz1−Fz2) / (Fz1 · Fz2)} Z
= 2π (1 / Fs) Z (6)
In addition, the synthetic | combination fringe length Fs in Formula (6) is represented by following Formula. The combined fringe length Fs is a change amount (period) of the Z position when the original difference signal ΔFZR changes by 2π which is one period.

Fs = Fz1 · Fz2 / (Fz1-Fz2) (7)
When the values of equations (5A) and (5B) are substituted into equation (7) as Fz1 and Fz2, the combined fringe length Fs is approximately 16 times (approximately 3 μm) of the individual fringe lengths Fz1 and Fz2 as follows: .
Fs≈3000 (nm) = 3 (μm) (8)
Further, the third calculation unit 41C adds ± i · 2π (i is an integer) to the original difference signal ΔFZR so that the value of the original difference signal ΔFZR is greater than or equal to 0 and less than 2π. A difference signal ΔFZ (0 ≦ ΔFZ <2π) is obtained. The difference signal ΔFZ is supplied to the origin signal output unit 41F.

ΔFZ = 2π (1 / Fs) Z ± i · 2π (9)
As shown in FIG. 3C, the difference signal ΔFZ is a periodic function of the period Fs (combined fringe length) with respect to the Z position (the relative position in the Z direction between the diffraction grating 12X and the second interference head 15X). Therefore, for example, the origin signal output unit 41F changes the relative position in the Z direction between the second member 7 and the first member 6 via a drive mechanism (not shown) when the contrast signal SC reaches the maximum value. When the difference signal ΔFZ is closest to the Z position (rough origin Zc) and the difference signal ΔFZ becomes 0 (when the Z position becomes Zs), the reset signal SR is output to the second calculation unit 41B. In the second calculation unit 41B, the Z position obtained from the detection signal of the first interference head 14X is set to 0 in synchronization with the reset signal SR. This means that the Z position value Zs when the difference signal ΔFZ becomes 0 is used as the Z position origin (absolute position origin). The relative position in the Z direction (relative movement amount) measured thereafter can be regarded as an absolute position in the Z direction with the Z position Zs so far as the origin.

  In the present embodiment, the period of the differential signal ΔFZ (the combined fringe length Fs) is 10 times or more the Z-direction period (the fringe length Fz1) of the detection signal of the first interference head 14X, and is within the range of the combined fringe length Fs. Then, the absolute position of the Z position can be obtained from the difference signal ΔFZ. In addition, since the difference signal ΔFZ having a specific period can be detected by using the contrast signal SC, the absolute position origin (Zs) can be obtained within a range exceeding the combined fringe length Fs. As an example, when the drive mechanism that sets the relative position in the Z direction between the second member 7 and the first member 6 can set the relative position in the Z direction with finer accuracy than the synthetic fringe length Fs, It is not necessary to use the contrast signal SC.

Further, the Y-axis encoder of the present embodiment has substantially the same configuration as the X-axis encoder 10X in FIG. 1, and the diffraction gratings 12Y1 and 12Y2 (see FIG. 5) of the Y-axis encoder have a 90 ° diffraction grating 12X. The Y-axis detection head is configured by rotating the first interference head 14X and the second interference head 15X by 90 °.
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 device that measures the relative movement amounts of the first member 6 and the second member 7 in the X direction and the Z direction, and the encoder 10 </ b> X is relative to the first member 6. An origin detection device 11X (position detection device) that detects the relative position of the second member 7 that moves relatively is provided. The origin detection device 11X is provided on the first member 6 and has a reflection type diffraction grating 12X having a grating pattern 12Xa having at least the X direction as a periodic direction, and the measurement light MX1 on the grating pattern surface 12Xb of the diffraction grating 12X. The first interference head 14X (the first interference head 14X that detects the + 1st order first interference light of the diffracted light DX2 from the diffraction grating 12X and the reference light MR1 by making the first incident angle (approximately Littrow angle φLI) in the X direction. Interferometer) and measurement light MX3 are incident on the grating pattern surface 12Xb of the diffraction grating 12X at a second incident angle (approximately 0 °) different from the first incident angle in the X direction, and the diffracted light from the diffraction grating 12X. The second interference head 15X (second interferometer) that detects the second interference light between FX2 and the reference light MR3, the detection signal (a · X + b1 · Z) of the first interference head 14X, and the second interference head Origin signal calculation unit for obtaining a difference signal ΔFZ representing a relative position in the normal direction (Z direction) of the lattice pattern surface 12Xb between the first member 6 and the second member 7 from the detection signal (a · X + b2 · Z) of the switch 15X 43X (first detection unit). The wavelengths of the measuring beams MX1 and MX3 are substantially equal to each other.

  Further, in the position detection method using the origin detection device 11X of the present embodiment, the measurement light MX1 is transmitted from the first interference head 14X to the grating pattern surface 12Xb of the diffraction grating 12X provided on the first member 6 in the X direction (diffraction grating). 12X periodic direction), a step of detecting + 1st-order first interference light between the diffracted light DX2 from the diffraction grating 12X and the reference light MR1, and measurement light from the second interference head 15X. MX3 is incident on the grating pattern surface 12Xb of the diffraction grating 12X at a second incident angle different from the first incident angle in the X direction, and second interference light from the diffracted light FX2 and the reference light MR3 from the diffraction grating 12X is detected. And the origin signal calculation unit 43X uses the + first-order first interference light detection signal and the second interference light detection signal to determine the lattice pattern surface 12X between the first member 6 and the second member 7. The relative position of the normal direction (Z-direction) and a step of obtaining a difference signal ΔFZ representing the (first relative position).

  According to this embodiment, since the first incident angle and the second incident angle are different, the relative movement amount (second relative position) in the Z direction is measured from the detection signal of the first-order first interference light. The absolute position can be measured when the relative movement amount (third relative position) in the Z direction is measured from the fringe length Fz1 (first length), which is a range in which the absolute position can be measured, and the detection signal of the second interference light. This is different from the range of the fringe length Fz2 (second length). The combined fringe length Fs, which is the period of the relative position in the Z direction (first relative position) represented by the difference signal ΔFZ obtained from the detection signals of the first and second interference lights, is greater than the fringe lengths Fs1 and Fs2. become longer. Therefore, when performing measurement using the diffraction grating 12X, the normal line of the grating pattern surface 12Xb of the diffraction grating 12X exceeds the range (fringe lengths Fs1, Fs2) in which the absolute position can be measured when measuring the relative movement amount. The absolute position of the direction can be detected.

  In addition, the origin detection device 11X shifts the first member 6 and the second member 7 in the Z-direction relative position (fourth relative position) from the lateral shift amount (shift amount) of the diffracted light FX2 obtained by the second interference head 15X. A fifth calculation unit 41E (second detection unit) that outputs a corresponding contrast signal SC is provided, and the origin signal calculation unit 43X (first detection unit) includes a contrast signal SC (first detection unit) output from the fifth calculation unit 41E. The Z position (first relative position) Zs when the difference signal ΔFZ becomes a predetermined value (for example, 0) within the period when the (4 relative position) becomes the maximum value is obtained. For example, by measuring the relative movement amount with reference to the Z position Zs, the absolute position in the Z direction can be obtained within a range exceeding one cycle (the combined fringe length Fs) of the difference signal ΔFZ.

In addition, in order to detect the relative position in the Z direction in a range exceeding the combined fringe length Fs, other Z position sensors (for example, a capacitance sensor or a proximity switch) using a method other than detecting the lateral shift amount of the diffracted light FX2 ) May be used.
Further, the encoder 10X generates a signal between the detection signal of the + 1st order first interference light and the -1st order diffracted light EX2 and the reference light MR2 generated by the measurement light MX2 irradiated to the diffraction grating 12X from the first interference head 14X. A second calculation unit 41B (third detection unit) that measures the relative movement amount of the first member 6 and the second member 7 in the Z direction from the detection signal of the primary first interference light is provided. 41B uses the Z position Zs (first relative position) detected by the origin signal calculation unit 43X to preset the measured value of the relative movement amount in the Z direction (including resetting to 0). Thereby, the relative movement amount between the two members 6 and 7 can be measured as an absolute position with reference to the Z position Zs.

The encoder 10X also obtains the relative movement amount in the periodic direction (X direction) of the diffraction grating 12X between the two members 6 and 7 from the detection signals of the + 1st order first interference light and the −1st order first interference light. ing. Therefore, the relative movement amounts in the X direction and the Z direction can be obtained without further complicating the configuration of the first interference head 14X.
In the present embodiment, the first interference head 14X and the second interference head 15X detect the interference light between the diffracted light and the reference light generated by the second diffraction from the diffraction grating 12X, respectively. , 15X may detect the interference light between the diffracted light generated by the first diffraction from the diffraction grating 12X and the reference light. Further, the first interference head 14X and the second interference head 15X may be arranged so as to be shifted in the periodic direction (X direction) of the diffraction grating 12X.

  Further, in the present embodiment, the first interference head 14X causes the measurement light MX1 to be incident on the diffraction grating 12X at a substantially Littrow angle, and the second interference head 15X causes the measurement light MX3 to be incident on the diffraction grating 12X substantially perpendicularly. (± 1st order) diffracted light is detected. As another configuration, an interferometer in which the incident angles of the measurement beams MX1 and MX3 with respect to the diffraction grating 12X are different by an angle smaller than the Littrow angle in the X direction may be used as the first interference heads 14X and 15X. Good. The point is that if the fringe lengths Fz1 and Fz2 which are the periods of the relative positions in the Z direction are different from each other, the combined fringe length Fs becomes longer. Therefore, the absolute position can be measured in a wide range as in the above embodiment.

  In addition, an interferometer having the same configuration as that of the first interference head 14X is used as the second interference head 15X, and laser light (heterodyne light) having a wavelength different from that of the measurement light MX1 by about ± 10%, for example, is used as the measurement light MX3. The measurement light MX3 may be incident on the diffraction grating 12X at a substantially Littrow angle. An interferometer having the same configuration as that of the second interference head 15X is used as the first interference head 14X, and laser light (heterodyne light) whose wavelength is different from the measurement light MX3 by about ± 10%, for example, is used as the measurement light MX1. The measurement light MX1 may be incident on the diffraction grating 12X substantially vertically. Also in these cases, since the fringe lengths Fz1 and Fz2 which are periods of relative positions in the Z direction are different from each other, the absolute position can be measured in a wide range as in the above embodiment.

[Second Embodiment]
A second embodiment will be described with reference to FIGS. FIG. 4 shows a schematic configuration of an exposure apparatus EX provided with the encoder apparatus according to the present embodiment. The exposure apparatus EX is, for example, 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. 6) 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 shown in FIG. 6 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. 4, 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 the lens barrel 140 in a predetermined positional relationship. 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. 6) 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. 4, wafer stage WST is supported in a non-contact manner on upper surface 112a parallel to the XY plane of base board 112 via a plurality of, for example, vacuum preload type static air bearings (air pads) (not shown). Wafer stage WST can be driven in the X and Y directions by a stage drive system 124 (see FIG. 6) 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. 6) for aligning the wafer W, an irradiation system 90a, and a light receiving system 90b. An oblique incidence type multi-point auto-facus sensor 90 (see FIG. 6) for measuring the Z position of the location, and an encoder device 8B for measuring the position information of wafer stage WST are provided.

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

In addition, the upper surface of wafer table WTB has a surface (or a protective member) that has been subjected to a liquid repellency treatment with respect to liquid Lq and is substantially flush with the surface of the wafer placed on the wafer holder. A flat plate member 128 having a high flatness is provided in which a circular opening is formed in the center of the rectangular shape and a circular opening that is slightly larger than the wafer holder (wafer mounting region).
In the configuration of the so-called immersion type exposure apparatus provided with the above-described local immersion apparatus 108, the plate body 128 is further shown in the plan view of 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 X-axis first and second diffraction gratings 12X1 and 12X2 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. Thus, a pair of Y-axis diffraction gratings 12Y1 and 12Y2 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. 4, 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 first interference heads 14X having the same configuration as the X-axis first interference head 14X in FIG. 1 are fixed to the bottom surface of the measurement frame 150 so as to sandwich the projection optical system PL in the Y direction. A plurality of Y-axis first interference heads 14Y having a configuration in which the first interference head 14X is rotated by 90 ° are fixed so as to be sandwiched in the X direction (see FIG. 5). Further, as shown in FIG. 5, the second interference head 15X having the same configuration as the second interference head 15X in FIG. 1 is fixed to the pair of first interference heads 14X sandwiching the projection optical system PL in proximity to the Y direction. A second interference head 15Y having a configuration in which the second interference head 15X is rotated by 90 ° in the vicinity of the pair of Y-axis first interference heads 14Y sandwiching the projection optical system PL is fixed. A plurality of laser light sources (not shown) are also provided for supplying laser light (measurement light and reference light) to the plurality of first interference heads 14X and 14Y and the second interference heads 15X and 15Y.

  In FIG. 5, during the period in which the wafer W is exposed with the illumination light from the projection optical system PL, any two of the plurality of first interference heads 14X always face the X-axis diffraction gratings 12X1 and 12X2, Any two of the detection heads 14Y are configured to face the Y-axis diffraction gratings 12Y1 and 12Y2. Each of the first interference heads 14X irradiates the diffraction grating 12X1 or 12X2 with measurement light, and a corresponding movement amount detection unit 42X (see FIG. 6) detects a detection signal of interference light between the diffraction light generated from the diffraction gratings 12X1 and 12X2 and the reference light. 6). In the movement amount detection unit 42X, as in the movement amount detection unit 42X of FIG. 1, the relative position (relative movement amount) between the wafer stage WST and the measurement frame 150 in the X direction and the Z direction is, for example, 0.5 to 0.1 nm. And is supplied to the measurement value switching unit 80X.

  Further, in FIG. 6, an origin signal calculation unit 43X (the same calculation unit as the origin signal calculation unit 43X in FIG. 1) for obtaining the absolute position in the Z direction from the detection signals of the first interference head 14X and the second interference head 15X is provided. If necessary, the relative movement amount in the Z direction of the movement amount detection unit 42X is reset by a reset signal from the origin signal calculation unit 43X. In the measurement value switching unit 80X, information on the relative position supplied from the movement amount detection unit 42X corresponding to the first interference head 14X facing the diffraction gratings 12X1 and 12X2 is supplied to the main controller 120.

  Further, each detection head 14Y irradiates the diffraction grating 12Y1 or 12Y2 with measurement light, and the corresponding measurement calculation unit 42Y (FIG. 6) corresponds to the detection signal of the interference light between the diffraction light generated from the diffraction gratings 12Y1 and 12Y2 and the reference light. ). In the measurement calculation unit 42Y, as in the movement amount detection unit 42X, the relative position (relative movement amount) between the wafer stage WST and the measurement frame 150 in the Y direction and the Z direction is obtained with a resolution of 0.5 to 0.1 nm, for example. To the measured value switching unit 80Y. In FIG. 6, an origin signal calculation unit 43Y (calculation unit having the same configuration as the origin signal calculation unit 43X in FIG. 1) that obtains the absolute position in the Z direction from the detection signals of the first interference head 14Y and the second interference head 15Y is provided. The relative movement amount in the Z direction of the movement amount detection unit 42Y is reset by a reset signal from the origin signal calculation unit 43Y as necessary. 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 first interference heads 14X, second interference heads 15X, a laser light source (not shown), a movement amount detection unit 42X, an origin signal calculation unit 43X, and X-axis diffraction gratings 12X1 and 12X2 constitute an X-axis encoder 10XB. A plurality of detection heads 14Y, a second interference head 15Y, a laser light source (not shown), a measurement calculation unit 42Y, an origin signal calculation unit 43Y, and Y-axis diffraction gratings 12Y1 and 12Y2 constitute a Y-axis encoder 10YB. ing. 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 first interference 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 first interference heads 14X and 14Y is affected. 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. Further, since the second interference heads 15X and 15Y and the origin signal calculation units 43X and 43Y (origin detection device) are provided, the measurement is performed by the encoder device 8B at the start of operation of the exposure apparatus EX (for example, when the power is turned on). The relative movement amount in the Z direction can be reset in a reproducible state. Therefore, for example, the encoder device 8B can be easily operated without using a mechanical limit switch or the like.

  In this embodiment, the interference heads 14X, 14Y, 15X, 15Y, etc. are arranged on the measurement frame 150 side, and the diffraction gratings 12X1, 12Y1, etc. 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 interference heads 14X, 14Y, 15X, 15Y, etc. may be arranged on the wafer stage WST side.

  Further, when an electronic device (or a micro device) 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 embodiment, the position of wafer stage WST of the exposure apparatus can be controlled with high accuracy using encoder device 8B, so that the 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 like of the above embodiment measure the relative movement amount of an object in an optical apparatus having 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. Can be applied to.
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 device, R ... reticle, W ... wafer, MX1-MX3 ... measurement light, RX1-RX3 ... reference light, 10X ... X-axis and Z-axis encoders, 11X ... origin detection device, 12X ... X-axis diffraction grating , 14X ... first interference head, 15X ... second interference head, 16A, 16B ... laser light source, 40XA to 40XC ... photoelectric sensor, 41C ... third calculation unit, 42X ... movement amount detection unit, 43X ... origin signal calculation unit

Claims (14)

A position detection device that detects a relative position of a second member that moves relative to a first member,
A reflective diffraction grating provided on one of the first member and the second member and having a grating pattern having at least a first direction as a periodic direction;
First measurement light is incident on the grating pattern surface of the diffraction grating at a first incident angle with respect to the first direction, and first interference light from the first diffraction light and the first reference light from the diffraction grating is detected. A first interferometer;
Second measurement light is incident on the grating pattern surface of the diffraction grating at a second incident angle with respect to the first direction, and second interference light from the second diffraction light and the second reference light from the diffraction grating is detected. A second interferometer;
A first detector for obtaining a first relative position in a normal direction of the lattice pattern surface of the first member and the second member from the detection signal of the first interference light and the detection signal of the second interference light; With
A position detection device, wherein the wavelength of the first measurement light and the wavelength of the second measurement light, and at least one of the first incident angle and the second incident angle are different. The period of the second relative position in the normal direction obtained from the detection signal of the first interference light is Fz1, and the period of the third relative position in the normal direction obtained from the detection signal of the second interference light is Fz2 ( As Fz2 <Fz1),
The position detection device according to claim 1, wherein the first detection unit obtains the first relative position within a range of the next one cycle.
1 period = Fz1 · Fz2 / (Fz1-Fz2) The wavelength of the first measurement light and the wavelength of the second measurement light are substantially the same,
The position detection apparatus according to claim 1, wherein the first incident angle is different from the second incident angle. The first measurement light is incident on the lattice pattern surface at a Littrow angle with respect to the first direction,
The second measurement light is incident on the grating pattern surface substantially perpendicularly with respect to the first direction,
The position detection apparatus according to claim 3, wherein the orders of the first diffracted light and the second diffracted light are the same.   The position detection device according to claim 3, wherein the first incident angle and the second incident angle are different by an angle smaller than a Littrow angle of the diffraction grating with respect to the first direction. A second detector for detecting a fourth relative position in a normal direction of the grating pattern surface of the first member and the second member from a lateral shift amount of at least one of the first diffracted light and the second diffracted light; Prepared,
The said 1st detection part calculates | requires the said 1st relative position within the period according to the said 4th relative position detected by the said 2nd detection part, The any one of Claims 1-5 characterized by the above-mentioned. The position detection apparatus described in 1. A sensor for obtaining a fourth relative position in a normal direction of the lattice pattern surface of the first member and the second member;
6. The position according to claim 1, wherein the first detection unit determines the first relative position within a period corresponding to the fourth relative position determined by the sensor. Detection device. An encoder device that measures a relative movement amount of a second member that moves at least relative to a first member,
The position detection device according to any one of claims 1 to 7,
A third detector for measuring a relative movement amount of the first member and the second member in the normal direction of the lattice pattern surface from the detection signal of the first interference light or the detection signal of the second interference light; With
The encoder device, wherein the third detection unit presets a measurement value of the relative movement amount using the first relative position detected by the first detection unit. A position detection method for detecting a relative position of a second member that moves relative to a first member,
The first measurement light is provided in one of the first member and the second member on the grating pattern surface of a reflective diffraction grating having a grating pattern having at least a first direction as a periodic direction. Detecting the first interference light between the first diffracted light and the first reference light from the diffraction grating,
Second measurement light is incident on the grating pattern surface of the diffraction grating at a second incident angle with respect to the first direction, and second interference light from the second diffraction light and the second reference light from the diffraction grating is detected. And
Obtaining a first relative position in a normal direction of the lattice pattern surface of the first member and the second member from the detection signal of the first interference light and the detection signal of the second interference light,
A position detection method, wherein the wavelength of the first measurement light and the wavelength of the second measurement light, and at least one of the first incident angle and the second incident angle are different. The period of the first relative position in the normal direction obtained from the detection signal of the first interference light is Fz1, and the period of the second relative position in the normal direction obtained from the detection signal of the second interference light is Fz2 ( As Fz2 <Fz1),
The position detection method according to claim 9, wherein the first relative position is obtained within a range of the next one cycle.
1 period = Fz1 · Fz2 / (Fz1-Fz2) The wavelength of the first measurement light and the wavelength of the second measurement light are substantially the same,
The first measurement light is incident on the lattice pattern surface at a Littrow angle with respect to the first direction,
The second measurement light is incident on the grating pattern surface substantially perpendicularly with respect to the first direction,
The position detection method according to claim 9 or 10, wherein the orders of the first diffracted light and the second diffracted light are the same. 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 movable relative to the frame;
An exposure apparatus comprising: the position detection device according to claim 1 for detecting a relative position of the stage with respect to the frame. 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 movable relative to the frame;
An exposure apparatus comprising: the encoder apparatus according to claim 8 for measuring a relative movement amount of the stage with respect to the frame. A device manufacturing method including a lithography process,
14. A device manufacturing method, comprising: exposing an object using the exposure apparatus according to claim 12 or 13 in the lithography process.

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