JP2013026273A - Encoder device, optical device, and exposure device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to compactly arrange an interferometric optical system and suppress reduction of interference beam intensity against height variation of a diffraction grating pattern surface when a measurement is done using a diffraction grating.SOLUTION: An encoder 10X comprises: a diffraction grating 12X disposed in a first component 6; a laser source 16 which makes measurement beams MX1 and MX2 incident roughly perpendicularly on a diffraction grating pattern surface 12Xb of the diffraction grating 12X; a rectangular prism 26A which is disposed in a second component 7 and makes a diffraction beam DX1 generated from the diffraction grating 12X by the measurement beam MX1 incident on the diffraction grating 12X again ; and a photoelectronic sensor 40X which detects an interference beam between a diffraction beam DX2 generated by the diffraction beam DX1 and the other diffraction beam EX2.

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

Since the conventional encoder device reflects the diffracted light generated from the diffraction grating by a flat mirror or the like, when the height of the grating pattern surface of the diffraction grating changes, the diffracted light is compared with other diffracted light or reference light. There is a risk that the intensity of the interference light is lowered due to relative shift.
In addition, the conventional encoder device has a plurality of optical members for causing the diffracted light and other diffracted light or reference light to interfere with each other substantially along the incident surface of the measurement light. It has become high and it has been difficult to incorporate the optical system into, for example, a narrow space.

  In view of such a problem, the aspect of the present invention makes it possible to arrange an interference optical system in a compact manner when measuring the amount of relative movement using a diffraction grating, and to provide interference light with respect to a change in the height of the grating pattern surface. It aims at suppressing the fall of intensity | strength.

  According to the first aspect of the present invention, there is provided an encoder device that measures the relative movement amount of the 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 has a reflection type diffraction grating having a grating pattern having the first direction as a periodic direction, and the first measurement light is supplied to the grating of the diffraction grating. A light source unit that is substantially perpendicularly incident on the pattern surface, and provided on the other of the first member and the second member, and has first and second reflecting surfaces orthogonal to each other, and the first measurement from the diffraction grating. The first two-surface reflecting member that makes the first diffracted light generated by the light enter the diffraction grating again through the two reflecting surfaces so as to include a shift component in the second direction orthogonal to the first direction. A photoelectric detector for detecting interference light between the second diffracted light and other diffracted light or reference light generated from the diffraction grating by the first diffracted light approximately perpendicularly to the grating pattern surface, and the photoelectric detector Use the detection signal A measuring unit for determining the relative movement amount of the second member Te are those comprising a.

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 includes 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 book for measuring a relative movement amount of the stage in the first direction. And an encoder device according to the 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, since the two-surface reflecting member for allowing the first diffracted light generated by the first measurement light from the diffraction grating to enter the diffraction grating again through the two reflecting surfaces is provided, the interference of the encoder device is provided. The optical system can be arranged compactly.
In addition, by using a two-surface reflecting member, the relative lateral shift amount between the diffracted light and other diffracted light or reference light can be reduced, so that the intensity of interference light is reduced with respect to changes in the height of the grating pattern surface Can be suppressed, and high measurement accuracy can be maintained.

1A is a perspective view showing an encoder according to a first embodiment. FIG. (A) is a figure which shows the optical path of the diffracted light in the encoder of FIG. 1, (B) is a figure which shows the optical path of the diffracted light when the height of a grating | lattice pattern surface changes. It is a figure which shows the optical path of the diffracted light used as noise light in the encoder of FIG. It is a perspective view showing an encoder concerning a modification of an embodiment. It is a figure which shows schematic structure of the exposure apparatus which concerns on 2nd Embodiment. FIG. 6 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. 5. 6 is a block diagram showing a control system of the exposure apparatus of FIG. It is a flowchart which shows an example of the manufacturing method of an electronic device.

[First Embodiment]
A first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a perspective view showing a main part of an X-axis encoder 10X according to the present 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 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 transmits measurement light to the diffraction grating 12 </ b> X, which is fixed to the upper surface of the first member 6, and is a flat plate-shaped X-axis diffraction grating 12 </ b> X parallel to the XY plane, and the second member 7. The X-axis detection head 14 </ b> X to be irradiated, the laser light source 16 that supplies the detection head 14 </ b> X with measurement laser light, and the detection signal output from the detection head 14 </ b> X are processed to process the second member 7 with respect to the first member 6. And a measurement calculation unit 42X for obtaining a relative movement amount in the X direction.

  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, and emits a two-frequency heterodyne light made up of first and second linearly polarized laser beams whose polarization directions are orthogonal to each other and have different frequencies. . These laser beams are coherent with each other, and their average wavelength is λ. The laser light source 16 supplies a signal of a reference frequency (reference signal) obtained by photoelectric conversion of interference light of two light beams branched from the laser light to the measurement calculation unit 42X. A homodyne interference method can also be used.

  The detection head 14X includes a flat base member 22 fixed to the second member 7 and parallel to the XY plane, and heterodyne light supplied from the laser light source 16 and S-polarized first measurement light MX1 having the same light amount. A polarization beam splitter (hereinafter referred to as PBS) 18 that divides the light into P-polarized second measurement light MX2 (the optical path is indicated by a dotted line), and the optical path length of the measurement light MX1 are matched with the optical path length of the measurement light MX2. The mirrors 20A1, 20A2, 20A3, and 20B that reflect the measurement light MX1, the mirror 20C that reflects the measurement light MX2, the mirror 20D, the polarizing plate 30, and a photoelectric sensor 40X such as a photodiode. The mirrors 20 </ b> A <b> 1 to 20 </ b> D are disposed on the upper surface side of the base member 22. The members from PBS 18 to photoelectric sensor 40XA are supported by a support member (not shown) fixed to base member 22. The base member 22 is formed with two window portions 22b and 22c arranged at a predetermined interval along the X direction, and a window portion 22d arranged at a position away from the intermediate position between the window portions 22b and 22c in the Y direction. Has been. The measurement beams MX1 and MX2 are reflected by the mirrors 20B and 20C, pass through the window portions 22b and 22c, respectively, and enter the grating pattern surface 12Xb of the diffraction grating 12X substantially perpendicularly.

  Further, the detection head 14X is fixed to the support member 28A on the bottom surface of the base member 22 and the step mirror 24A and the support member 28A fixed adjacent to the −X direction side of the windows 22b to 22d in the X direction. And a right angle prism 26A. The step mirror 24A has a first reflection surface 24Aa parallel to the XY plane and a second reflection surface 24Ab parallel to the reflection surface 24Aa and offset in the + Z direction. The right-angle prism 26A has first and second reflecting surfaces 26Aa and 26Ab orthogonal to each other, and an incident / exit surface between the reflecting surfaces 26Aa and 26Ab is described later in a clockwise direction in the θy direction from a state parallel to the XY plane. Is supported in a state rotated by an angle (θd + α / 2). The detection head 14X includes the step mirror 24B, the support member 28B, and the right-angle prism 26B having the same shape and symmetrically arranged with the step mirror 24A, the support member 28A, and the right-angle prism 26A across the windows 22b to 22d. Have.

  In FIG. 1, the first measurement light MX1 enters the first measurement point PA of the grating pattern surface 12Xb of the diffraction grating 12X through the window portion 22b substantially perpendicularly, and is +1 next time from the diffraction grating 12X in the −X direction. The folding light DX1 is generated. The diffracted light DX1 is reflected by the first reflecting surface 24Aa of the step mirror 24A, enters the right-angle prism 26A, is reflected by the two reflecting surfaces 26Aa, 26Ab of the right-angle prism 26A, and is reflected by the second reflecting surface of the step mirror 24A. Incident on 24 Ab. Then, the diffracted light DX1 reflected by the reflecting surface 24Ab is obliquely incident on the third measurement point PC on the grating pattern surface 12Xb, and the −1st order diffracted light DX2 is vertically generated from the measurement point PC.

  On the other hand, the second measurement light MX2 is incident substantially perpendicularly to the second measurement point PB of the grating pattern surface 12Xb through the window portion 22c, and −1st order diffracted light EX1 is generated in the + X direction from the diffraction grating 12X. The diffracted light EX1 is reflected by the first reflecting surface 24Ba of the step mirror 24B, enters the right-angle prism 26B, is reflected by the two reflecting surfaces 26Ba, 26Bb of the right-angle prism 26B, and is reflected by the second reflecting surface of the step mirror 24B. Incident on 24Bb. Then, the diffracted light EX1 reflected by the reflecting surface 24Bb is obliquely incident on the third measurement point PC where the diffracted light DX1 of the grating pattern surface 12Xb is incident, and the + 1st order diffracted light EX2 is vertically generated from the measurement point PC. . The −1st order diffracted light DX2 and the + 1st order diffracted light EX2 generated vertically at the measurement point PC are coaxially combined and received by the photoelectric sensor 40X via the window portion 22d of the base member 22, the mirror 20D, and the polarizing plate 30. . A detection signal of the photoelectric sensor 40X is supplied to the measurement calculation unit 42X. In this embodiment, since the optical path lengths of the measurement lights MX1 and MX2 (diffracted light) from being branched by the PBS 18 to being incident on the photoelectric sensor 40X are set to be substantially equal to each other, the measurement lights MX1 and MX2 are relatively wavelengths. A wide laser beam can be used. In addition, when the wavelength width of measurement light MX1, MX2 is narrow, you may enlarge the optical path length difference of measurement light MX1, MX2 (diffracted light).

  As an example, the measurement calculation unit 42 </ b> X obtains the relative movement amount in the X direction of the second member 7 relative to the first member 6 from the detection signal and the reference signal supplied from the laser light source 16. The detection resolution of the relative movement amount in the X direction is, for example, about 0.5 to 0.1 nm. In this embodiment, since the interference light between the second −1st order diffracted light DX2 and the second + 1st order diffracted light EX2 is finally detected, the detection resolution (detection accuracy) of the relative movement amount is halved. It can be improved (miniaturized). In addition, by using ± first-order diffracted light, measurement errors due to the relative rotation angles of the first member 6 and the second member 7 in the θz direction can be reduced.

  Next, the incident angles in the θy direction (X direction) of the measurement light MX1 and MX2 of the present embodiment with respect to the lattice pattern surface 12Xb are symmetrical as shown in FIG. 2A in order to reduce the influence of noise light. Is shifted by an angle α. In the following, it is assumed that the incident angle α of the measurement light MX1 is shifted clockwise. The angle α is, for example, about 0.5 ° to several degrees, and is preferably set to, for example, 0.5 ° to 1.5 ° (target value is about 1 °).

In this case, assuming that the diffraction angle of the + 1st order diffracted light DX1 when the measurement light MX1 is perpendicularly incident on the grating pattern surface 12Xb is φd (counterclockwise angle), the measurement light MX1 is rotated using the average wavelength λ of the measurement lights MX1 and MX2. The folding angle φd satisfies the following relationship.
sin φd = λ (1)
In this embodiment, since the measurement light MX1 is incident on the diffraction grating 12X at an incident angle α, the diffraction angle φ1 of the + 1st order diffracted light DX1 from the diffraction grating 12X by the incident measurement light MX1 is approximately the diffraction angle φd as follows. Than the angle α.

φ1 ≒ φd + α (2)
The diffracted light DX1 is reflected by the first reflecting surface 24Aa of the step mirror 24A and enters the right-angle prism 26A. In the present embodiment, the inclination angle in the θy direction with respect to the ZY plane of the mounting surface of the right-angle prism 26A of the support member 28A is set to (θd + α / 2). As a result, the incident / exit surface between the reflecting surfaces 26Aa and 26Ab of the right-angle prism 26A is rotated from the state parallel to the XY plane by an angle (θd + α / 2) clockwise in the θy direction. Accordingly, the diffracted light DX1 reflected by the two orthogonal reflecting surfaces 26Aa and 26Ab of the right-angle prism 26A is reflected by the second reflecting surface 24Ab of the step mirror 24A and then counterclockwise with respect to the grating pattern surface 12Xb. At an incident angle φd (the same angle as the diffraction angle of the + 1st order diffracted light). Accordingly, the −1st order diffracted light DX2 is generated vertically upward (diffraction angle 0) from the diffraction grating 12X by the incidence of the diffracted light DX1.

  In contrast to this, the first-order diffracted light EX1 generated by the second measurement light MX2 is reflected by the first reflecting surface 24Ba of the step mirror 24B, and is parallel to the XY plane of the right-angle prism 26B in the θy direction. The light is incident on a surface rotated counterclockwise by an angle (θd + α / 2) and reflected by two orthogonal reflecting surfaces 26Ba and 26Bb of the right-angle prism 26B. The diffracted light EX1 is reflected by the second reflecting surface 24Bb of the step mirror 24B, and then enters the grating pattern surface 12Xb clockwise with an incident angle φd. Accordingly, the + 1st order diffracted light EX2 is generated vertically upward (diffraction angle 0) from the diffraction grating 12X by the incidence of the diffracted light EX1, that is, parallel to the -1st order diffracted light DX2. Therefore, since the interference light of the diffracted light DX2 and EX2 has a high intensity change contrast, the position can be detected with high accuracy.

  In the present embodiment, as shown in FIG. 2B, when the height (the position in the Z direction) of the grating pattern surface 12Xb of the diffraction grating 12X changes to the position PD, the measurement point PA of the diffraction grating 12X starts. The generated diffracted light DX1 is incident on the original measurement point PC of the diffraction grating 12X as indicated by the optical path PE through the step mirror 24A, the right-angle prism 26A, and the step mirror 24A. Similarly, the diffracted light EX1 generated from the measurement point PB of the diffraction grating 12X is substantially measured at the original measurement point PC of the diffraction grating 12X as indicated by the optical path PF via the step mirror 24B, the right-angle prism 26B, and the step mirror 24B. Is incident on. Accordingly, since the relative lateral shift between the diffracted beams DX2 and EX2 hardly occurs, the position can always be detected with high accuracy.

  However, as shown in FIG. 3, in the present embodiment, the -second-order diffracted light DX21 is generated in the same direction by the diffracted light DX1 incident on the measurement point PC of the diffraction grating 12X. In FIG. 3, the diffracted light DX21 returns to the measurement point PA of the diffraction grating 12X via the second reflection surface 24Ab, the right-angle prism 26A, and the first reflection surface 24Aa, and the diffraction angle from the measurement point PA is substantially (θd -Α) + 2nd order diffracted light DX22 is generated. The diffracted light DX22 returns to the measurement point PC of the diffraction grating 12X via the first reflection surface 24Aa, the right-angle prism 26A, and the second reflection surface 24Ab, and is approximately −1 next time from the measurement point PC at a diffraction angle 2 · α. The folded light DX23 is generated. Interference light between the diffracted light DX23 and the other diffracted lights DX2 and EX2 becomes noise light.

  However, the angle (crossing angle) in the θy direction between the diffracted light DX23 and the other diffracted lights DX2 and EX2 is approximately 2 · α, and an interference fringe with a small 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 the interference fringes formed by the combination of the diffracted light DX23 and the diffracted lights DX2 and EX2 is 1/100 of the beam diameter d. If it is less than or equal to the extent (if more than 100 interference fringes are formed), the fluctuation component (noise component) due to the 0th order light of the detection signal obtained by photoelectrically converting the obtained interference fringes is approximately 1. %, The measurement error is extremely small. The conditions at this time are as follows. However, the angle α is represented by rad.

d · 2 · α ≧ 100λ (3)
Here, as an example, when the beam diameter d is 2 mm and the wavelength λ is 0.633 μm, the angle α satisfying the expression (3) is as follows.
α ≧ 0.0158 (rad) = 0.91 ° (4)
Therefore, when the beam diameters of the measuring beams MX1 and MX2 are about 2 mm, the incident angle α in the X direction of the measuring beams MX1 and MX2 is preferably 0.91 ° or more, for example, about 1 °. When the incident angle α of the measurement beams MX1 and MX2 increases, the amount of lateral shift of the diffracted beams DX2 and EX2 increases with respect to the change in the position of the grating pattern surface 12Xa in the Z direction, and the interference light includes relative position information. Therefore, it is better not to increase the angle α within a range satisfying the equation (4).

For example, when the diffraction efficiency of the + 2nd order diffracted light is low, the angle α may be zero.
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 receives the measurement lights MX1 and MX2 from the diffraction grating 12X whose periodic direction is the X direction and the laser light source 16 that generates coherent measurement lights MX1 and MX2. Mirrors 20B and 20C that enter the grating pattern surface 12Xb of the diffraction grating 12X substantially perpendicularly and the second member 7 have reflection surfaces 26Aa and 26Ab that are orthogonal to each other, and are generated from the diffraction grating 12X by the measurement light MX1. The + 1st-order diffracted light DX1 is generated substantially perpendicularly to the grating pattern surface 12Xb by the diffracted light DX1 from the diffraction grating 12X and the right-angle prism 26A that is shifted in the Y direction via the reflecting surfaces 26Aa and 26Ab and re-entered on the diffraction grating 12X. A photoelectric sensor 40X that detects interference light between the -1st order diffracted light DX2 and the other diffracted light EX2, And a, a measurement calculation unit 42X to determine the relative amount of movement of the second member 7 by using the detection signal of the photoelectric sensor 40X.

According to the present embodiment, the right-angle prism 26A (two-surface reflecting member) that makes the diffraction light DX1 generated by the measurement light MX1 from the diffraction grating 12X shift to the diffraction grating 12X in the Y direction via the two reflection surfaces and enter again. ) Is provided, the optical system for interference of the encoder 10X can be compactly arranged on the bottom surface of the second member 7, for example.
Further, since the relative lateral shift amount between the diffracted light DX2 and the other diffracted light EX2 can be reduced by using the right-angle prism 26A, the decrease in the intensity of the interference light is suppressed with respect to the height change of the grating pattern surface 12Xb. And high measurement accuracy can be maintained.

Instead of the right-angle prisms 26A and 26B, for example, a roof prism having two orthogonal reflecting surfaces can be used.
In the present embodiment, the interference light between the diffracted light EX2 and the diffracted light DX2 generated from the diffraction grating 12X is detected by the second measurement light MX2. However, for example, interference light between the diffracted light DX2 and other reference light may be detected.

Next, a modification of the present embodiment will be described with reference to FIG. In FIG. 4, parts corresponding to those in FIG. 1 are denoted by the same reference numerals, and detailed description thereof is omitted.
FIG. 4 shows a Y-axis encoder 10Y. The encoder 10Y includes a Y-axis diffraction grating 12Y configured by rotating the diffraction grating 12X fixed to the first member 6 by 90 °, a Y-axis detection head 14Y fixed to the second member 7, and a detection head 14Y. A laser light source 16 that supplies laser light, and a measurement calculation unit 42Y that processes a detection signal output from the detection head 14Y to obtain a relative movement amount of the second member 7 in the Y direction with respect to the first member 6 are included. Note that a two-dimensional diffraction grating may be used instead of the diffraction grating 12Y.

  The detection head 14Y is a flat base member 22 fixed to the second member 7 and parallel to the XY plane, a PBS 18A for dividing the laser light from the laser light source 16 into coherent measurement light MY1 and MY2, and a mirror 20E. To 20H and the photoelectric sensor 40Y. The base member 22 is formed with two window portions 22e and 22f arranged at a predetermined interval along the Y direction, and a window portion 22g arranged at a position away from the window portion 22f in the Y direction. The measurement beams MY1 and MY2 are reflected by the mirrors 20E and 20G and the mirror 20F, pass through the windows 22e and 22f, respectively, and enter the measurement points PD and PE on the grating pattern surface 12Xb of the diffraction grating 12X at an incident angle α in the Y direction. To do. Also in this modified example, the optical path lengths of the measurement lights MY1 and MY2 from the time branched by the PBS 18A to the incident on the photoelectric sensor 40Y are set substantially equal to each other.

  The detection head 14Y includes a step mirror 24C and a support member 28C having the same shape as the step mirror 24A fixed to the bottom surface of the base member 22, and a right-angle prism 26C fixed to the support member 28C. The detection head 14Y is fixed to the step member 24C, the support member 28C, and the right angle prism 26C so as to face the stepped mirror 24C, the support member 32, and the support member 32 with the window portions 22e to 22g interposed therebetween. It has a right-angle prism 26D that faces the direction of PE.

  In FIG. 4, the first measurement light MY1 is incident substantially perpendicularly to the first measurement point PD on the grating pattern surface 12Yb of the diffraction grating 12Y, and the + 1st order diffracted light DY1 from the diffraction grating 12Y is the second measurement light of the step mirror 24C. The light is reflected by one reflecting surface and enters the right-angle prism 26C, and is reflected by two reflecting surfaces of the right-angle prism 26C and enters the second reflecting surface of the step mirror 24C. The diffracted light DY1 reflected by this reflecting surface is incident obliquely on the third measurement point PF of the grating pattern surface 12Xb, and the −1st order diffracted light DY2 is generated vertically from the measurement point PF.

On the other hand, the second measurement light MY2 is incident on the second measurement point PE of the grating pattern surface 12Yb via the window portion 22f at the incident angle α in the Y direction, and the −1st order diffracted light EY1 in the + Y direction from the diffraction grating 12Y. Will occur. The diffracted light EY1 is reflected by the two reflecting surfaces 26Da and 26Db of the right-angle prism 26C and obliquely enters the third measurement point PF where the diffracted light DY1 on the grating pattern surface 12Yb is incident, and the + 1st order diffracted light from the measurement point PF. EY2 occurs vertically. The −1st order diffracted light DY2 and the + 1st order diffracted light EY2 generated vertically at the measurement point PF are combined coaxially and received by the photoelectric sensor 40Y through the window 22g of the base member 22, the mirror 20H, and the polarizing plate 30. . The detection signal of the photoelectric sensor 40Y is supplied to the measurement calculation unit 42Y, and the measurement calculation unit 42Y obtains the relative movement amount in the Y direction between the first member 6 and the second member 7 using the detection signal. Also in the encoder 10Y of this modified example, the same effect as the above embodiment can be obtained.
The detection head 14X of the encoder 10X in FIG. 1 and the detection head 14Y of the encoder 10Y in FIG. 4 can be arranged so as to intersect.

[Second Embodiment]
A second embodiment will be described with reference to FIGS. FIG. 5 shows a schematic configuration of an exposure apparatus EX provided with the encoder apparatus according to this embodiment. The exposure apparatus EX is a scanning exposure type projection exposure apparatus composed of a scanning stepper. The exposure apparatus EX includes a projection optical system PL (projection unit PU). Hereinafter, the Z-axis is parallel to the optical axis AX of the projection optical system PL, and a plane orthogonal to the Z-axis (a plane substantially parallel to the horizontal plane). In the following description, the Y axis is taken in the direction in which the reticle R and the wafer W are relatively scanned, and the X axis is taken in the direction perpendicular to the Z axis and the Y axis.

  The exposure apparatus EX includes an illumination system 110 disclosed in, for example, US Patent Application Publication No. 2003/0025890, and illumination light (exposure light) IL (for example, an ArF excimer laser having a wavelength of 193 nm) from the illumination system 110 A reticle stage RST that holds a reticle R (mask) illuminated by light, a harmonic of a solid-state laser (such as a semiconductor laser). Further, the exposure apparatus EX includes a projection unit PU including a projection optical system PL that projects the illumination light IL emitted from the reticle R onto the wafer W (substrate), a stage apparatus 195 including a wafer stage WST that holds the wafer W, and A control system or the like (see FIG. 7) 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 the reticle interferometer 116 is sent to the 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. 5, the projection unit PU disposed below the reticle stage RST includes a lens barrel 140 and a projection optical system PL having a plurality of optical elements held in 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. 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. 5, 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. 7) for measuring the Z position of the location and an encoder device 8B for measuring position information of wafer stage WST are provided.

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

In addition, the upper surface of wafer table WTB has a surface (or a protective member) that has been subjected to a liquid repellency treatment with respect to liquid Lq and is substantially flush with the surface of the wafer placed on the wafer holder. A flat plate member 128 having a high flatness is provided in which a circular opening is formed in the center of the rectangular shape and a circular opening that is slightly larger than the wafer holder (wafer mounting region).
In the configuration of the so-called immersion type exposure apparatus provided with the above-described local immersion apparatus 108, the plate body 128 is further shown in the plan view of 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. 5, a flat measurement frame 150 substantially parallel to the XY plane is supported by 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. 1 are fixed to the bottom surface of the measurement frame 150 so as to sandwich the projection optical system PL in the X direction, and the projection optical system PL is sandwiched in the Y direction. As described above, a plurality of detection heads 14Y having the same configuration as the Y-axis detection head 14Y of FIG. 4 are fixed (see FIG. 6). 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. Instead of the detection head 14Y, a detection head having a configuration obtained by rotating the detection head 14X of FIG. 1 by 90 ° may be used.

  In FIG. 6, during the period in which the wafer W is exposed with the illumination light from the projection optical system PL, any two of the plurality of detection heads 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. 7). 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.
Further, when an electronic device (or microdevice) such as a semiconductor device is manufactured using the exposure apparatus EX or the exposure method of the above embodiment, the electronic device has a function / performance design of the electronic device as shown in FIG. Step 221 for performing a step, Step 222 for fabricating a reticle (mask) based on this design step, Step 223 for fabricating a substrate (wafer) as a base material of the device and applying a resist, and the exposure apparatus ( Substrate processing step 224 including a step of exposing a reticle pattern to a substrate (photosensitive substrate) by an exposure method), a step of developing the exposed substrate, a heating (curing) and etching step of the developed substrate, and a device assembly step (dicing) Process, bonding process, packaging process, etc.) And an inspection step 226, etc. each time.

  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.

Further, the encoders 10X and 10Y of the above-described embodiment or example are the relative movement amounts of the objects in the optical apparatus having the optical system for the object to be inspected or processed such as the inspection apparatus or the measurement apparatus other than the exposure apparatus. Can be applied to measure.
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, DX1, DX2 ... ± first order diffracted light, EX2, EX ... ± first order diffracted light, 10X ... X-axis encoder, 12X ... X-axis Diffraction grating, 14X: X axis detection head, 16: Laser light source, 24A, 24B ... Step mirror, 26A, 26B ... Right angle prism, 40X, 40Y ... Photoelectric sensor, 42X, 42Y ... Measurement calculation unit

In this case, if the period in the X direction of the grating pattern 12Xa is p, and the diffraction angle of the + 1st order diffracted light DX1 when the measurement light MX1 is perpendicularly incident on the grating pattern surface 12Xb is φd (counterclockwise angle), the measurement light The diffraction angle φd satisfies the following relationship using the average wavelength λ of MX1 and MX2.
p · sin φd = λ (1)
In this embodiment, since the measurement light MX1 is incident on the diffraction grating 12X at an incident angle α, the diffraction angle φ1 of the + 1st order diffracted light DX1 from the diffraction grating 12X by the incident measurement light MX1 is approximately the diffraction angle φd as follows. Than the angle α.

Claims (11)

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 causing the first measurement light to enter the grating pattern surface of the diffraction grating substantially perpendicularly;
The first diffracted light that is provided on the other of the first member and the second member, has first and second reflecting surfaces orthogonal to each other, and is generated by the first measurement light from the diffraction grating, A first two-surface reflecting member that is incident again on the diffraction grating so as to include a shift component in a second direction orthogonal to the first direction through two reflecting surfaces;
A photoelectric detector for detecting interference light between the second diffracted light and other diffracted light or reference light generated from the diffraction grating by the first diffracted light substantially perpendicular to the grating pattern surface;
A measurement unit for obtaining a relative movement amount of the second member using a detection signal of the photoelectric detector;
An encoder device comprising: The light source unit also causes the second measurement light having coherence with the first measurement light to enter the grating pattern surface of the diffraction grating substantially perpendicularly,
It is provided on the other of the first member and the second member, and has third and fourth reflecting surfaces orthogonal to each other, and is generated almost symmetrically with the first diffracted light by the second measurement light from the diffraction grating. And a second two-surface reflecting member that re-enters the diffraction grating so as to include a shift component in the second direction through the two reflecting surfaces.
The photoelectric detector detects interference light between the second diffracted light and fourth diffracted light generated substantially perpendicularly to the grating pattern surface by the third diffracted light from the diffraction grating. Item 5. The encoder device according to Item 1. A first parallel reflecting member having fifth and sixth reflecting surfaces parallel to the lattice pattern surface and having different heights;
The first diffracted light generated from the diffraction grating is converted into the fifth reflecting surface of the first parallel reflecting member, the first reflecting surface and the second reflecting surface of the first two-surface reflecting member. The encoder device according to claim 2, wherein the diffraction grating is incident again on the diffraction grating through the sixth reflecting surface of the first parallel reflecting member. The first and second incident positions of the first measurement light and the second measurement light with respect to the diffraction grating are shifted in the first direction,
A second parallel reflecting member having seventh and eighth reflecting surfaces parallel to the lattice pattern surface and having different heights;
The third diffracted light of the second measurement light generated from the diffraction grating is converted into the seventh reflecting surface of the second parallel reflecting member, the third reflecting surface of the second two-surface reflecting member, and 4. The light is incident again on the third incident position of the diffraction grating through the fourth reflective surface and the eighth reflective surface of the second parallel reflective member. 5. Encoder device.   An angle adjusting member for inclining the first measurement light and the second measurement light emitted from the light source unit to the diffraction grating by a predetermined angle in the first direction with respect to a normal direction of the grating pattern surface; The encoder apparatus according to claim 2, further comprising:   The encoder apparatus according to claim 5, wherein the normal direction of the incident surface of the first two-surface reflecting member is corrected by an angle that is ½ of the predetermined angle.   The encoder apparatus according to claim 1, wherein the first diffracted light and the second diffracted light of the first measurement light are first-order diffracted light by the diffraction grating.   6. The encoder apparatus according to claim 2, wherein each of the first and second two-surface reflecting members is a right-angle prism. The encoder device according to any one of claims 1 to 8,
And an optical system for an object. An exposure apparatus that exposes a pattern onto an object to be exposed,
Frame,
A stage that supports the object to be exposed and is relatively movable in at least a first direction with respect to the frame;
An exposure apparatus comprising: the encoder device according to any one of claims 1 to 9 for measuring a relative movement amount of the stage in the first direction. A device manufacturing method including a lithography process,
A device manufacturing method, comprising: exposing an object using the exposure apparatus according to claim 10 in the lithography process.

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