JP6469993B2 - Optical functional device, optical modulator, and exposure apparatus - Google Patents

Description

  The present invention relates to an optical functional device that generates polarization pairs whose polarization directions are opposite to each other by receiving an electric field, an optical modulator using the optical functional device, and an exposure apparatus.

When an electric field is applied to an electro-optic crystal substrate composed of lithium niobate (LiNbO ₃ ), lithium tantalate (LiTaO ₃ ), or the like, an electro-optic effect is generated. Thus, many optical functional devices using this have been proposed. For example, Patent Document 1 discloses an optical functional device that generates an index difference inside a substrate by applying an electric field to an electro-optic crystal substrate having a domain-inverted structure, and exhibits interaction with light incident on the substrate. Have been described. More specifically, light is modulated by controlling the voltage applied to the electro-optic crystal substrate in accordance with an electric signal so that the refractive index distribution generated inside the substrate functions as a diffraction grating. Thus, an invention is described in which light passing through an electro-optic crystal substrate is modulated by a diffraction grating formed in accordance with an electrical signal.

JP 2012-208190 A

  By the way, when the optical functional device is used as an optical modulator, an electric field in one direction is applied to the substrate by continuing to apply a positive voltage or a negative voltage. A phenomenon in which the value of the diffraction efficiency gradually changes, that is, a so-called “DC drift phenomenon” may occur. Therefore, in Patent Document 1 described above, the electric signal that vibrates on both the positive side and the negative side is applied to the substrate, that is, the bipolar drive system is employed to eliminate the residual charge in the crystal.

  However, in the bipolar drive system, the drive circuit for supplying an electric signal to the optical functional device for driving is increased. In addition, since the electric signal is vibrated on both the positive side and the negative side, there is a problem that the voltage width is widened and it is difficult to increase the modulation speed. Therefore, a new technique for effectively suppressing the DC drift phenomenon without causing these problems is desired.

  The present invention has been made in view of the above problems, and has an object to provide an optical functional device capable of effectively suppressing a DC drift phenomenon, an optical modulator and an exposure apparatus using the optical functional device. To do.

  A first aspect of the present invention is an optical functional device having a first polarization inversion region in which a first polarization part and a second polarization part in which directions of polarization generated by receiving an electric field are opposite to each other, The volume of the polarization part and the volume of the second polarization part are substantially the same.

  According to a second aspect of the present invention, there is provided an optical modulator that modulates light, wherein the first polarization unit and the second polarization unit in which the directions of polarization generated by receiving an electric field are opposite to each other are alternately arranged in a first period. The electro-optic crystal substrate having the first domain-inverted region of the periodically domain-inverted structure arranged in the first direction, the first electrode provided on one main surface of the first domain-inverted region, and the first domain-inverted region sandwiched between A potential difference is applied between the second electrode provided on the other main surface opposite to the one main surface of the first domain-inverted region, and the first electrode and the second electrode, and an electric field is applied to the first domain-inverted region. And a drive section that modulates light by forming a diffraction grating, and the volume of the first polarization section and the volume of the second polarization section are substantially the same.

  Furthermore, a third aspect of the present invention is an exposure apparatus, which is an illumination optical system that irradiates light from a light source, the light modulator that modulates light emitted from the illumination optical system, and a light modulator that modulates the light. And a projection optical system for projecting the emitted light onto the exposed portion.

  As described above, according to the present invention, the first polarization portion and the second polarization portion are arranged in the first polarization inversion region of the optical functional device. In these polarization parts, a charge bias that causes a DC drift occurs while receiving an electric field, but the polarization directions are opposite to each other, and the charge bias directions in the first polarization part and the second polarization part The signs of the biases are also opposite to each other. In addition, since the volumes of the first polarization unit 311 and the second polarization unit 312 are substantially the same, the amount of charge bias in the first polarization unit and the second polarization unit is substantially equal. For this reason, it is possible to cancel out the DC drift phenomenon effectively by canceling out the charge bias in the first polarization part and the second polarization part.

It is a figure which shows the exposure apparatus equipped with the optical modulator formed using 1st Embodiment of the optical functional device concerning this invention. It is a figure which shows the optical modulator formed using 1st Embodiment of the optical functional device concerning this invention. It is a perspective view which shows typically the electro-optic crystal substrate used with an optical modulator. It is a figure which shows 2nd Embodiment of the optical functional device concerning this invention. It is a figure which shows typically the arrangement | positioning relationship of an electro-optic crystal substrate, a signal electrode, and wiring in an optical functional device. It is a figure which shows 3rd Embodiment of the optical function device concerning this invention. It is a figure which shows 4th Embodiment of the optical function device concerning this invention. It is a front view which shows an example of the drawing apparatus which can apply this invention. It is a top view of the drawing apparatus of FIG. It is a block diagram which shows the electrical structure of the drawing apparatus of FIG.

  FIG. 1 is a view showing an exposure apparatus equipped with an optical modulator formed using the first embodiment of the optical functional device according to the present invention. FIG. 2 is a view showing an optical modulator formed by using the first embodiment of the optical functional device according to the present invention, and FIG. 2 (a) is an exploded view of the optical modulator. (B) is a figure which shows the structure of an optical modulator. FIG. 3 is a perspective view schematically showing an electro-optic crystal substrate used in the optical modulator. The exposure apparatus 1 is equipped with an optical modulator using an optical functional device, and exposes an exposed portion such as a substrate W by irradiating light. The exposure apparatus 1 is modulated by an illumination optical system 2 that irradiates light from a light source 21 in a traveling direction Z, a light modulator 3 that modulates light emitted from the illumination optical system 2, and a light modulator 3. And a projection optical system 4 that projects light onto a substrate W (exposed portion).

As the light source 21 of the illumination optical system 2, a normal laser light source having a Gaussian distribution beam shape (TEM ₀₀ basic transverse mode), a surface light source, a light source in which a plurality of point light sources are arranged, or a semiconductor laser is arranged in one dimension. The laser array etc. which were made can be used. In the illumination optical system 2, the light emitted from the light source 21 enters the light modulator 3 through the three cylindrical lenses 22 to 24.

  Among these, the cylindrical lens 22 has a negative power only in the X direction, and the light passing through the cylindrical lens 22 changes from a circular cross section perpendicular to the optical axis OA to an ellipse that is gradually longer in the X direction. . On the other hand, with respect to the optical axis OA and the Y direction perpendicular to the X direction, the width of the light beam cross section of the light passing through the cylindrical lens 22 is (almost) constant. The cylindrical lens 23 has a positive power only in the X direction, and the light that has passed through the cylindrical lens 22 is beam-shaped by the cylindrical lens 23. That is, the light that has passed through the cylindrical lens 23 is made into an elliptical shape having a constant cross-section with a long cross section in the X direction, and is incident on the cylindrical lens 24. The cylindrical lens 24 has a positive power only in the Y direction. When attention is paid only to the Y direction, the light LI passing through the cylindrical lens 24 is condensed as shown in FIG. The light enters the end surface (hereinafter referred to as “incident surface”) 31 a of the electro-optic crystal substrate 31 of the optical modulator 3 on the (−Z) side. In the X direction, the light LI emitted from the cylindrical lens 24 is incident on the electro-optic crystal substrate 31 of the optical modulator 3 as parallel light.

  The optical modulator 3 forms a diffraction grating in the electro-optic crystal substrate 31 by adjusting the voltage applied to the signal electrode 33 (FIGS. 1 and 2A) from the drive unit 32 shown in FIG. Then, light modulation is performed. Hereinafter, the configuration of the optical modulator 3 will be described with reference to FIGS. 1, 2, and 3.

  In the optical modulator 3, five signal electrodes 33 are provided on the upper surface of the base portion 34. Each of these signal electrodes 33 has a strip shape parallel to the Z direction, is arranged in the X direction while being spaced apart from each other by a predetermined distance, and independently applies a voltage from the drive unit 32 via the wiring 35. receive. Then, the electro-optic crystal substrate 31 is arranged so that the one main surface 31 b of the electro-optic crystal substrate 31 is in contact with the upper surfaces of these signal electrodes 33.

In the present embodiment, the electro-optic crystal substrate 31 is formed of a single crystal of slab-shaped lithium niobate (LiNbO ₃ ) (that is, lithium niobate, abbreviated as LN). In the electro-optic crystal substrate 31, as shown in FIG. 3, the first polarization portions 311 and the second polarization portions 312 that are opposite in direction of polarization generated by receiving an electric field are alternately arranged. The substrate 31 has a polarization inversion structure. In this embodiment, each of the first polarization unit 311 and the second polarization unit 312 has a strip shape extending in parallel with the traveling direction Z of the light L, and has the same width in the arrangement direction X orthogonal to the traveling direction Z. ing. In addition, polarization pairs 313 including the first polarization unit 311 and the second polarization unit 312 arranged adjacent to each other are arranged in the arrangement direction X at a predetermined period (period Λ). As described above, in the first embodiment, the polarization pair 313 is arranged on the entire electro-optic crystal substrate 31, and the entire electro-optic crystal substrate 31 functions as the “first polarization inversion region” of the present invention.

  As shown in the right part of FIG. 2A, the other principal surface 31 c of the electro-optic crystal substrate 31 thus configured is supported by the support plate 37 via the common electrode 36. More specifically, when the support plate 37 is viewed from above (+ Y direction side), it has a rectangular shape, and its Z-direction width is the same as that of the electro-optic crystal substrate 31, whereas the X-direction length is electrical. It is slightly longer than the optical crystal substrate 31. A common electrode 36 is formed on the entire lower surface of the support plate 37. Then, after the other main surface 31c of the electro-optic crystal substrate 31 is attached to the common electrode 36 to produce the intermediate structure 38, the one main surface 31b of the electro-optic crystal substrate 31 is signaled by the intermediate structure 38. It arrange | positions so that it may be located on the electrode 33. FIG. In the present embodiment, each signal electrode 33 and each polarization pair 313 both have a shape extending in parallel with the Z direction, and three polarization pairs 313 continuous in the polarization pair arrangement direction X on each signal electrode 33. Is arranged to be positioned. The positional relationship between the signal electrode 33 and the polarization pair 313 is not limited to this. For example, two or more polarization pairs 313 may be positioned on each signal electrode 33.

  In this embodiment employing the above arrangement, the electro-optic crystal substrate 31 is sandwiched between five signal electrodes 33 and a common electrode 36. Of these electrodes, the common electrode 36 is grounded. Therefore, in the electro-optic crystal substrate 31, when a predetermined voltage (a voltage other than 0 [V]) is applied from the driving unit 32 and a potential difference is generated, the signal electrode 33 and the common electrode are only in a region corresponding to the signal electrode 33. A refractive index change in accordance with the polarization direction is generated by the electric field generated between 36 and a diffraction grating is formed. As a result, the light traveling through the region is diffracted by the electro-optic crystal substrate 31 and emitted from the electro-optic crystal substrate 31 as diffracted light. On the other hand, an electric field is not generated in a region where voltage application to the signal electrode 33 is not performed, and light traveling through the region travels straight through the electro-optic crystal substrate 31 as it is, and is transmitted from the electro-optic crystal substrate 31 to zero-order light (non-light). (Diffracted light). Thus, by controlling the voltage application to the five signal electrodes 33, it is possible to perform optical modulation for five channels.

  Returning to FIG. 1, the description of the configuration of the exposure apparatus 1 will be continued. In the projection optical system 4 provided on the light emission side (right hand side in FIG. 1) of the electro-optic crystal substrate 31, a lens 41, an aperture plate 42, and a lens 43 are arranged in this order. The front focal point of the lens 41 is set at the position of the exit end 31 d of the electro-optic crystal substrate 31, and the aperture plate 42 is provided at the rear focus of the lens 41, and the optical axis extends from the exit end 31 d of the electro-optic crystal substrate 31. The 0th-order light Lo emitted in parallel with OA (traveling direction Z) passes through the aperture 421 of the aperture plate 42 and enters the lens 43. Further, the front focal point of the lens 43 is set at the position of the aperture plate 42, the rear focal point of the lens 43 is set on the surface of the substrate W, and the zero-order light Lo passes through the lens 43 on the surface of the substrate W. Is irradiated. On the other hand, the diffracted light emitted from the electro-optic crystal substrate 31 is emitted from the electro-optic crystal substrate 31 in a state inclined with respect to the optical axis OA, and therefore cannot pass through the aperture 421 and is shielded by the aperture plate 42. Is done. In this way, only the 0th-order light Lo is irradiated onto the surface of the substrate W, and an exposure process for the substrate W is executed.

  As described above, in the first embodiment, as shown in FIG. 3, the electro-optic crystal substrate 31 is finished into a plate shape having a constant thickness (the height in the Y direction), and the first electro-optic crystal substrate 31 has a first shape. The polarization units 311 and the second polarization units 312 are alternately arranged in the X direction. The first polarization part 311 and the second polarization part 312 have the same X-direction width and Z-direction length. Therefore, the area when the first polarization part 311 and the second polarization part 312 are viewed from the upper side (+ Y direction side) is substantially the same, and the volumes of the first polarization part 311 and the second polarization part 312 are also substantially the same. is there. Note that “substantially the same” means that a certain degree of variation occurs when the polarization portions 311 and 312 are formed in the electro-optic crystal substrate 31, and is included in the range of non-uniformity in which the variation occurs. It is.

  When the electro-optic crystal substrate 31 configured in this manner is sandwiched between the signal electrode 33 and the common electrode 36 and a predetermined voltage is applied to the signal electrode 33 by the drive unit 32, the cause of DC drift is caused in the electro-optic crystal substrate 31. The resulting charge bias occurs. However, in this embodiment, the electro-optic crystal substrate 31 is provided with a (periodic) domain-inverted structure in which the orientation of the crystal axis is reversed in the region to which the voltage is applied as described above. Depending on the direction of the axis (direction of polarization), charge biases with opposite signs occur. Moreover, as described above, the volumes of the first polarization unit 311 and the second polarization unit 312 are substantially the same, and the volumes of the non-polarization inversion region and the polarization inversion region when a voltage is applied are equal. Therefore, the electric charge biases generated in the first polarization part 311 and the second polarization part 312 are opposite in sign and equal in amount, so that they cancel each other and cancel each other. Therefore, the DC drift phenomenon can be effectively suppressed.

  In this embodiment, the “optical functional device” of the present invention is configured by the electro-optic crystal substrate 31, the signal electrode 33, and the common electrode 36, and the optical functional device is combined with the driving unit 32 to function as the optical modulator 3. ing. For this reason, light modulation can be performed appropriately. That is, when a DC drift phenomenon occurs, an electric field due to residual charges is generated in the electro-optic crystal substrate 31 even though the voltage applied to the signal electrode 33 is set to 0 [V]. For this reason, the diffraction efficiency of the diffraction grating may not become zero and may have an offset. On the other hand, when the optical modulator 3 is configured using the optical functional device (= electro-optic crystal substrate 31 + signal electrode 33 + common electrode 36) according to the first embodiment, the DC drift phenomenon can be suppressed, and the diffraction grating The diffraction efficiency offset can be suppressed, and good light modulation is possible.

  By the way, in the first embodiment, the periodic polarization inversion structure is formed on the entire electro-optic crystal substrate 31 and functions as the “first polarization inversion region” of the present invention. However, the first polarization functions as an optical functional device. The inversion region may be formed only on a part of the electro-optic crystal substrate 31. For example, a first polarization inversion region may be provided corresponding to the signal electrode 33 and a second polarization inversion region different from the first polarization inversion region may be provided corresponding to the wiring 35. This is because when an electric field generated between the wiring 35 and the common electrode 36 to apply a voltage to the signal electrode 33 is applied to the first domain-inverted region, the crystal sandwiched between the signal electrode 33 and the common electrode 36. This is because a diffraction grating may be formed in a crystal part other than the part. Therefore, as will be described next, the electro-optic crystal substrate 31 is provided with a first polarization inversion region and a second polarization inversion region different from the first polarization inversion region, and the wiring 35 is provided in the second polarization inversion region. You may comprise so that it may hang. Hereinafter, a second embodiment of the present invention will be described with reference to FIGS. 4 and 5.

  FIG. 4 is a view showing a second embodiment of the optical functional device according to the present invention. FIG. 5 is a diagram schematically showing the arrangement relationship of the electro-optic crystal substrate, the signal electrode, and the wiring in the optical functional device of FIG. The second embodiment is greatly different from the first embodiment in that the electro-optic crystal substrate 31 includes the first polarization inversion region 31e and the second polarization inversion region 31f and the second polarization inversion region 31f on the wiring 35. It is a point arranged in. Other configurations and application to the exposure apparatus 1 are basically the same as those in the first embodiment. Accordingly, the following description will focus on the differences, and the same components will be assigned the same reference numerals and description thereof will be omitted.

  In the second embodiment, as shown in FIG. 4, the first polarization inversion region 31e is formed in the central portion of the electro-optic crystal substrate 31, and the frame-shaped second polarization is formed so as to surround the first polarization inversion region 31e. An inversion region 31f is formed. In the first polarization inversion region 31e, as in the first embodiment, the polarization pairs 313 including the first polarization unit 311 and the second polarization unit 312 are arranged in the arrangement direction X to form a periodic polarization inversion structure. On the other hand, in the second domain-inverted region 31f, the third polarization units 315 and the fourth polarization units 315 whose polarization directions generated by receiving an electric field are opposite to each other are alternately arranged, and the third polarization units 315 are arranged adjacent to each other. A polarization pair 316 including the polarization unit 314 and the fourth polarization unit 315 is arranged in a Y direction that is different from the period of the polarization pair 313 and that is orthogonal to the X direction.

  As shown in FIG. 4, the other principal surface 31 c of the electro-optic crystal substrate 31 configured in this way is supported by the support plate 37 through the common electrode 36. Here, the shape, size, arrangement relationship, and the like of the electro-optic crystal substrate 31, the common electrode 36, and the support plate 37 are the same as those in the first embodiment. Arranged on the electrode 33 and the wiring 35. That is, the electro-optic crystal substrate 31 is arranged with respect to the base portion 34 so that the entire first polarization inversion region 31 e is located on the signal electrode 33 and a part of the second polarization inversion region 31 f is located on the wiring 35. Is done. In the second embodiment, each signal electrode 33 is finished to a size corresponding to the planar size of the first polarization inversion region 31e, and each signal electrode 33 and each polarization pair 313 have a shape extending in parallel with the Z direction. And three polarization pairs 313 (see FIG. 3) that are continuous in the polarization pair arrangement direction X are positioned on each signal electrode 33.

  In this embodiment employing the above arrangement, only the first domain-inverted region 31 e of the electro-optic crystal substrate 31 is sandwiched between the five signal electrodes 33 and the common electrode 36. In the first domain-inverted region 31e, the signal is generated between the signal electrode 33 and the common electrode 36 only in a region corresponding to the signal electrode 33 to which a predetermined voltage (a voltage other than 0 [V]) is applied from the drive unit 32. A refractive index change according to the polarization direction is generated by the electric field, and a diffraction grating is formed. As a result, light that travels in the region of the incident light LI is diffracted by the electro-optic crystal substrate 31 and is emitted from the electro-optic crystal substrate 31 as diffracted light. At this time, in the second polarization inversion region 31f, an electric field is generated between the wiring 35 for electrically connecting the signal electrode 33 to the driving unit 32 and the common electrode 36. As described above, the second polarization is reversed. Since the polarization pair 316 constituting the inversion region 31f has a different period and arrangement direction from the polarization pair 313 in the first polarization inversion region 31e, a diffraction grating is not formed by the electric field, and the second polarization inversion region The light traveling through 31f travels straight toward the first domain-inverted region 31e as it is. That is, light modulation can be favorably performed by applying a voltage to the signal electrode 33 without being affected by an electric field generated between the wiring 35 and the common electrode 36. Of course, when no voltage is applied to the signal electrode 33, an electric field is not generated not only between the signal electrode 33 and the common electrode 36 but also between the wiring 35 and the common electrode 36, and the light remains as it is. It goes straight through the electro-optic crystal substrate 31 and is emitted from the electro-optic crystal substrate 31 as zero-order light (non-diffracted light). In this way, light modulation for five channels can be performed satisfactorily by controlling the voltage application to the five signal electrodes 33 without being affected by the electric field generated between the wiring 35 and the common electrode 36. Is possible.

  Also, in the second domain-inverted region 31f, when a predetermined voltage is applied to the signal electrode 33 via the wiring 35 by the driving unit 32, a bias of charge that causes DC drift occurs in the crystal, but the first embodiment For the same reason, the DC drift phenomenon can be effectively suppressed. That is, the volumes of the third polarization unit 314 and the fourth polarization unit 315 constituting the second polarization inversion region 31f are substantially the same, and the volumes of the non-polarization inversion region and the polarization inversion region when voltage is applied are equal. Therefore, the charge bias generated in each of the third polarization unit 314 and the fourth polarization unit 315 has the opposite sign and the same amount, and as a result, cancels each other and cancels out.

  In the second embodiment, the other main surface 31c of the electro-optic crystal substrate 31 is configured to be supported by the support plate 37 via the common electrode 36. However, in the third embodiment shown in FIG. As described above, the formation of the common electrode 36 at the portion facing the (+ Z) side end and the (−Z) side end of the second domain-inverted region 31 f in the lower surface of the support plate 37 may be omitted. When configured in this manner, the wiring 35 and the common electrode 36 can be prevented from facing each other across the (−Z) side end portion of the second polarization inversion region 31 f, and the wiring 35 and the common electrode 36 can be prevented from facing each other. The influence of the electric field generated between them can be further suppressed.

  As described above, in the first to third embodiments, the period Λ and the arrangement direction X of the polarization pair 313 including the first polarization unit 311 and the second polarization unit 312 are the “first period” of the present invention and This corresponds to an example of “first direction”. In the second embodiment and the third embodiment, the period and the arrangement direction Y of the polarization pair 316 composed of the third polarization unit 314 and the fourth polarization unit 315 are the “second period” and “second direction” of the present invention, respectively. Is equivalent to an example. Further, the signal electrode 33 and the common electrode 36 correspond to examples of the “first electrode” and the “second electrode” of the present invention, respectively. Furthermore, in the second and third embodiments, the one principal surface 31b of the electro-optic crystal substrate 31 corresponds to an example of “one principal surface of the first domain-inverted region” of the present invention, and the other principal surface 31c is the main surface. This corresponds to an example of “the other main surface of the first domain-inverted region” of the invention.

<Others>
The present invention is not limited to the above-described embodiment, and various modifications other than those described above can be made without departing from the spirit of the present invention. For example, in the embodiment described above, the signal electrode 33 functions as the “first electrode” of the present invention by directly arranging one main surface of the first polarization inversion region on the signal electrode 33. Direct contact between one main surface of the first electrode and the first electrode is not an essential component for exerting the optical function. For example, even if the first domain-inverted region is disposed on the first electrode via an insulating layer, Good. In this regard, the same applies to the arrangement relationship between the other main surface of the first domain-inverted region and the second electrode (common electrode 36).

  In the second embodiment and the third embodiment, two conditions are satisfied in order to suppress the influence of the electric field generated between the wiring 35 and the common electrode 36 so that the light travels straight. That is, the period of the polarization pair 316 constituting the second domain-inverted region 31f (corresponding to the “second period” of the present invention) is the period of the polarization pair 313 constituting the first domain-inverted region 31e (“first” of the present invention Both of the first condition and the second condition that the arrangement direction of the polarization pair 316 is different from the arrangement direction of the polarization pair 313 are satisfied. However, in order to suppress the influence of the electric field, only one of them may be satisfied. Further, for example, as shown in FIG. 7, the ratio of the third polarization part 314 and the fourth polarization part 315 constituting the polarization pair 316 is different from the ratio of the first polarization part 311 and the second polarization part 312 constituting the polarization pair 313. The third condition may be satisfied. In short, it is only necessary to satisfy at least one of the first to third conditions.

  In the second and third embodiments, the second domain-inverted region 31f is formed so as to surround the first domain-inverted region 31e. However, the configuration of the second domain-inverted region 31f is limited to this. It is not something. In other words, the second polarization inversion region 31f is provided adjacent to the first polarization inversion region 31e, and the second polarization inversion region 31f is arranged on the wiring 35, so that the second embodiment and the third embodiment can be achieved. Similar effects can be obtained. Incidentally, in the configuration for suppressing the influence of the electric field generated between the wiring 35 and the common electrode 36 in this way, the polarization part constituting the polarization pair has a volume of 1: n (where n is other than 1). The present invention can also be applied to optical functional devices and optical modulators formed with a ratio.

  In the above embodiment, the optical functional device (= electro-optic crystal substrate 31 + signal electrode 33 + common electrode 36) is combined with the drive unit 32 to function as the optical modulator 3, but the application target of the optical functional device is For example, the present invention may be applied to an optical functional device that exhibits an optical deflection function.

  Moreover, in the said embodiment, although the optical modulator 3 using the said optical functional device is applied to the exposure apparatus 1, the exposure apparatus 1 is applicable to various apparatuses. For example, the exposure apparatus 1 may be applied to a pattern drawing apparatus, and this application enables high-precision pattern drawing. Hereinafter, an example of pattern drawing using the exposure apparatus according to the present invention will be described with reference to FIGS.

  FIG. 8 is a front view showing an example of a drawing apparatus to which the present invention is applicable. FIG. 9 is a plan view of the drawing apparatus of FIG. FIG. 10 is a block diagram showing an electrical configuration of the drawing apparatus of FIG. The drawing apparatus is an apparatus for drawing a pattern by transporting a substrate W such as a semiconductor wafer subjected to pre-alignment processing to the processing stage 101 and irradiating the surface of the substrate W with light while holding the substrate W on the processing stage 101. is there.

  The drawing apparatus includes an exposure unit 100, a pre-alignment unit 200, a transport unit 300, and a data creation unit 500. Of these, the main components of the exposure unit 100, the pre-alignment unit 200, and the transport unit 300 are formed by attaching cover panels (not shown) to the ceiling surface and the peripheral surface of the skeleton formed by the main body frame 601. Placed inside the main body.

  The inside of the main body of the drawing apparatus is divided into a processing area 602 and a delivery area 603. Of these areas, the processing area 602 mainly includes a processing stage 101, a stage moving unit 102, a stage position measuring unit 103, an optical unit 104, and an alignment unit 105, which are the main components of the exposure unit 100. The exposure control unit 106 of the exposure unit 100 controls each part of the exposure unit 100 to expose the light beam onto the substrate W and draw a pattern. On the other hand, the pre-alignment unit 200 and the transport unit 300 are arranged in the delivery area 603 as shown in FIG. The pre-alignment unit 200 performs pre-alignment processing. In addition, the transfer unit 300 includes a transfer robot 301 that loads and unloads the substrate W with respect to the processing region 602.

  Further, an illumination unit 107 that supplies illumination light to the alignment unit 105 is disposed outside the main body of the drawing apparatus as shown in FIG. Although not shown in FIGS. 8 and 9, the exposure control unit 106 and the data creation unit 500 are disposed outside the main body.

  Further, a carrier placement portion 604 for placing the carrier C is disposed outside the main body of the drawing apparatus at a position adjacent to the transfer area 603. Then, the transfer robot 301 accesses the carrier C, the pre-alignment unit 200 and the processing stage 101 and transfers the substrate W as follows. That is, the transfer robot 301 takes out the unprocessed substrate W accommodated in the carrier C placed on the carrier placement unit 604 and carries it into the pre-alignment unit 200. The pre-alignment unit 200 performs pre-alignment processing and positions the substrate W so that a notch Wa (FIG. 9) formed on the outer peripheral portion of the substrate W faces a preset reference direction. The substrate W thus subjected to the pre-alignment process is transported from the pre-alignment unit 200 to the processing stage 101, and drawing is performed. Then, after the drawing is finished, the substrate W on which the drawing process has been performed is carried out from the processing stage 101 to the carrier C.

  The processing stage 101 is a holding unit that has a flat outer shape and places and holds the substrate W in a horizontal posture on the upper surface thereof. A plurality of suction holes (not shown) are formed on the upper surface of the processing stage 101. By applying a negative pressure (suction pressure) to the suction holes, the substrate W placed on the processing stage 101 is removed. It can be fixedly held on the upper surface of the processing stage 101. Then, the processing stage 101 is moved by the stage moving unit 102.

  The stage moving unit 102 is a mechanism that moves the processing stage 101 in the main scanning direction (Y-axis direction), the sub-scanning direction (X-axis direction), and the rotation direction (rotation direction around the Z axis (θ-axis direction)). . The stage moving unit 102 is a rotating mechanism 121 that rotates the processing stage 101 about the vertical axis Z on the support plate 122, a base plate 124 that supports the support plate 122, and a sub-movement that moves the support plate 122 in the sub-scanning direction X. A scanning mechanism 123 and a main scanning mechanism 125 that moves the base plate 124 in the main scanning direction Y are provided. The sub-scanning mechanism 123 and the main scanning mechanism 125 move the processing stage 101 in response to an instruction from the exposure control unit 106. As such a stage moving unit 102, a conventionally used XY-θ axis moving mechanism can be used.

  The stage position measurement unit 103 is a mechanism that measures the position of the processing stage 101. The stage position measurement unit 103 is electrically connected to the exposure control unit 106 and measures the position of the processing stage 101 in accordance with an instruction from the exposure control unit 106. The stage position measurement unit 103 is configured by a mechanism that irradiates the processing stage 101 with laser light and measures the position of the processing stage 101 using interference between the reflected light and the emitted light, for example. The configuration operation is not limited to this.

The optical unit 104 has two exposure heads 1a and 1b. The exposure heads 1a and 1b have the same configuration as the exposure apparatus 1 shown in FIG. 1, and the light beam emitted from the light source 21 is converted into a CAD (Computer).
Aided Design) is modulated based on drawing data corresponding to a pattern described by data. Although the exposure apparatus using the optical functional device according to the first embodiment is used as the exposure head here, it goes without saying that the exposure apparatus using the optical functional device according to other embodiments may be used. Yes. Further, the number of exposure heads is not limited to this and is arbitrary.

  The alignment unit 105 images an alignment mark (not shown) formed on the surface of the substrate W. The alignment unit 105 includes an imaging unit 151 having a lens barrel, an objective lens, and a CCD (Charge Coupled Device) image sensor. In this embodiment, an area image sensor (two-dimensional image sensor) is used as the CCD image sensor, but the present invention is not limited to this. Moreover, the alignment part 105 is supported so that raising / lowering is possible within the predetermined range by the raising / lowering mechanism which is not shown in figure.

  The illumination unit 107 is connected to the lens barrel via the fiber 71, and supplies illumination light to the alignment unit 105. The light guided by the fiber 171 extending from the illumination unit 107 is guided to the upper surface of the substrate W through the lens barrel of the imaging unit 151, and the reflected light is received by the CCD image sensor through the objective lens. As a result, the upper surface of the substrate W is imaged and image data is acquired. The imaging unit 151 is electrically connected to the mark position measurement unit 152, and outputs the acquired imaging data to the mark position measurement unit 152. The mark position measurement unit 152 obtains the coordinate position of the alignment mark based on the imaging data, and outputs it to the exposure control unit 106.

  The data creation unit 500 includes a computer having a CPU (Central Processing Unit), a storage unit 510, and the like, and is arranged in the electrical rack together with the exposure control unit 106. In addition, the data creation unit 520, the alignment coordinate deriving unit 530, and the rasterizing unit 540 are realized by the CPU in the data creation unit 500 performing arithmetic processing according to a predetermined program. In the present embodiment, the pattern to be drawn superimposed on the surface of the substrate W is described in vector format design data generated by an external CAD or the like, and when the design data is input to the data creation unit 500, It is written and stored in the storage unit 510. Then, the data creation unit 520 corrects the design data 511 to create corrected design data, which is sent to the alignment coordinate deriving unit 530 and the rasterizing unit 540.

  The alignment coordinate deriving unit 530 derives the coordinates of the alignment mark included in the correction design data and transmits them to the exposure control unit 106. In response to this, the exposure control unit 106 performs alignment processing by the alignment unit 105.

  The rasterizing unit 540 rasterizes the corrected design data in parallel with the alignment mark coordinate deriving process by the alignment coordinate deriving unit 530 and the alignment process by the exposure control unit 106 to generate run-length data (drawing data) 512 to store the data. Save to 510. In response to a data request from the exposure control unit 106, run-length data 512 is output from the storage unit 510 to the exposure control unit 106, and pattern drawing on the surface of the substrate W is executed in accordance with the run-length data 512. .

  In the drawing apparatus configured as described above, the transport robot 301 unloads the substrate W from the carrier C placed on the carrier placement unit 604, transports it to the pre-alignment unit 200, and performs pre-alignment processing. When the pre-alignment process is completed, the transport robot 301 starts transporting the substrate W from the pre-alignment unit 200 to the processing stage 101. Then, during the substrate transport operation, the data creation unit 500 creates run-length data.

  When the substrate W is placed on the processing stage 101 by the transfer robot 301 and the loading operation of the substrate W is completed, the exposure control unit 106 performs alignment processing. That is, the processing stage 101 is moved to a position immediately below the imaging unit 151 by the stage moving unit 102, and the alignment marks are sequentially positioned at the imageable positions of the imaging unit 151, and mark imaging by the imaging unit 151 is executed. The image signal output from the imaging unit 151 is processed by the mark position measurement unit 152, and the position of the alignment mark on the processing stage 101 is accurately obtained. Then, based on these measurement position information, the rotation mechanism 121 is operated, and the processing stage 101 is slightly rotated about the axis parallel to the surface normal of the surface of the substrate W, that is, the vertical axis, to pattern the surface of the substrate W. Align to the appropriate orientation.

  When the alignment process is completed, the exposure control unit 106 makes a data request to the data creation unit 500 and draws a pattern on the surface of the substrate W in accordance with the run length data 512 read from the storage unit 510.

  As described above, since the exposure heads 1a and 1b are configured by the exposure apparatus equipped with the optical functional device according to the present invention, the DC drift phenomenon is suppressed and light modulation based on the drawing data can be performed satisfactorily. . As a result, a pattern can be drawn on the surface of the substrate W with high accuracy.

  The present invention can be suitably used for an optical functional device that generates a polarization pair whose polarization directions are opposite to each other by receiving an electric field, an optical modulator using the optical functional device, and an exposure apparatus in general.

DESCRIPTION OF SYMBOLS 1 ... Exposure apparatus 1a, 1b ... Exposure head (exposure apparatus)
DESCRIPTION OF SYMBOLS 2 ... Illumination optical system 3 ... Optical modulator 4 ... Projection optical system 31e ... 1st polarization inversion area | region 31f ... 2nd polarization inversion area | region 33 ... Signal electrode (1st electrode)
35 ... Wiring 36 ... Common electrode (second electrode)
311 ... 1st polarization part 312 ... 2nd polarization part 313, 316 ... Polarization pair 314 ... 3rd polarization part 315 ... 4th polarization part

Claims (10)

A first polarization inversion region in which a first polarization part and a second polarization part in which directions of polarization are opposite to each other and a refractive index change according to a polarization direction is generated by an electric field are arranged;
Having a periodic polarization reversal structure different from the first polarization reversal region in which the third polarization part and the fourth polarization part in which the polarization directions are opposite to each other and the refractive index change is generated according to the polarization direction by the electric field, A second domain-inverted region formed adjacent to the first domain-inverted region;
A first electrode provided on one main surface of the first domain-inverted region;
A second electrode provided on the other main surface opposite to one main surface of the first polarization reversal region across the first polarization reversal region,
The first domain-inverted region is provided corresponding to the first electrode, and the second domain-inverted region is provided corresponding to a wiring for applying a voltage to the first electrode,
An array of polarization pairs composed of the third polarization part and the fourth polarization part is orthogonal to an array of polarization pairs composed of the first polarization part and the second polarization part;
The volume of the first polarization part and the volume of the second polarization part are substantially the same,
The optical functional device, wherein a volume of the third polarization part and a volume of the fourth polarization part are substantially the same. The optical functional device according to claim 1,
The first polarization inversion region is an optical functional device having a periodic polarization inversion structure in which the first polarization unit and the second polarization unit are alternately arranged in a first direction in a first period. The optical functional device according to claim 2,
An optical functional device in which a diffraction grating is formed in the first domain-inverted region upon receiving the electric field. The optical functional device according to claim 2 or 3,
A polarization pair consisting of the first polarization part and the second polarization part is a first polarization pair, a polarization pair consisting of the third polarization part and the fourth polarization part is a second polarization pair,
The second domain-inverted region has a domain-inverted structure in which the second polarization pairs obtained by combining the third polarization unit and the fourth polarization unit are arranged in a second direction in a second period,
The first condition that the second period is different from the first period, and the ratio of the third polarization part and the fourth polarization part constituting the second polarization pair constitute the first polarization pair . An optical functional device that satisfies at least one of a third condition that the ratio is different from the ratio of the polarization part and the second polarization part . An optical modulator for modulating light,
The first polarization unit and the second polarization unit that have opposite polarization directions and generate a refractive index change according to the polarization direction by an electric field are alternately arranged in the first direction in the first period. An electro-optic crystal substrate having one domain inversion region;
A first electrode provided on one main surface of the first domain-inverted region;
A second electrode provided on the other principal surface opposite to the one principal surface of the first polarization inversion region across the first polarization inversion region;
A driving unit that applies a potential difference between the first electrode and the second electrode to apply an electric field to the first domain-inverted region to form a diffraction grating to modulate the light;
Having a periodic polarization reversal structure different from the first polarization reversal region in which the third polarization part and the fourth polarization part in which the polarization directions are opposite to each other and the refractive index change is generated according to the polarization direction by the electric field, A second domain inversion region formed adjacent to the first domain inversion region,
The first domain-inverted region is provided corresponding to the first electrode, and the second domain-inverted region is provided corresponding to a wiring for applying a voltage to the first electrode,
An array of polarization pairs composed of the third polarization part and the fourth polarization part is orthogonal to an array of polarization pairs composed of the first polarization part and the second polarization part;
The volume of the first polarization part and the volume of the second polarization part are substantially the same,
The optical modulator, wherein a volume of the third polarization unit and a volume of the fourth polarization unit are substantially the same. The optical modulator according to claim 5, comprising:
The wiring is an optical modulator provided on one main surface side of the first domain-inverted region. The optical modulator according to claim 6, comprising:
The second electrode is an optical modulator provided so as to cover the first domain-inverted region and the second domain-inverted region from the other main surface side of the first domain-inverted region. The optical modulator according to claim 6, comprising:
The second electrode is provided so as to cover at least the first polarization inversion region from the other main surface side of the first polarization inversion region while avoiding facing the wiring via the second polarization inversion region. Light modulator. An optical modulator for modulating light,
The first polarization unit and the second polarization unit that have opposite polarization directions and generate a refractive index change according to the polarization direction by an electric field are alternately arranged in the first direction in the first period. An electro-optic crystal substrate having one domain inversion region;
A first electrode provided on one main surface of the first domain-inverted region;
A second electrode provided on the other principal surface opposite to the one principal surface of the first polarization inversion region across the first polarization inversion region;
A drive unit that modulates the light by providing a potential difference between the first electrode and the second electrode to apply an electric field to the first domain-inverted region to form a diffraction grating;
A second domain-inverted region is formed adjacent to the first domain-inverted region;
The second domain-inverted region includes a first domain-inverted region in which a third polarization unit and a fourth domain-polarized unit in which the polarization directions are opposite to each other and the refractive index changes according to the polarization direction by an electric field are arranged Have different periodically poled structures,
A wiring for applying a voltage to the first electrode is provided in the second domain-inverted region on one main surface side of the first domain-inverted region,
The second electrode is provided so as to cover at least the first polarization inversion region from the other main surface side of the first polarization inversion region while avoiding facing the wiring via the second polarization inversion region. ,
The volume of the first polarization part and the volume of the second polarization part are substantially the same,
The optical modulator, wherein a volume of the third polarization unit and a volume of the fourth polarization unit are substantially the same. An illumination optical system that emits light from a light source;
The light modulator according to any one of claims 5 to 9, which modulates light emitted from the illumination optical system;
An exposure apparatus comprising: a projection optical system that projects light modulated by the light modulator onto an exposed portion.

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