JP5278784B1 - Pattern inspection apparatus, pattern inspection method, and pattern substrate manufacturing method - Google Patents

Abstract

An object of the present invention is to inspect with high sensitivity any of patterns in different directions using polarized dipole illumination.
A pattern inspection apparatus according to the present invention includes a first linearly polarized light and a second linearly polarized light that are arranged at a conjugate position with a sample, change a polarization state of a part of illumination light, and have different polarization directions. A half-wave plate 130 that generates illumination light, a roof prism pair that divides one linearly polarized light in the first direction to generate first and second beams, and the other linearly polarized light differs from the first direction. A roof prism pair that divides in the second direction to generate third and fourth beams, and a first region that is a part of the field of view on the pattern substrate is irradiated with the first beam and the second beam. The objective lens 105 for irradiating the third and fourth beams to a second region different from the first region, the TDI 120a for detecting diffracted light by the first and second beams, and detecting the diffracted light by the third and fourth beams With TDI120b Obtain.
[Selection] Figure 1

Description

  The present invention relates to a pattern inspection apparatus, a pattern inspection method, and a pattern substrate manufacturing method.

  In general, a defect inspection method for a mask on which a pattern has been formed is a comparison between a mask pattern and design data (generally called a die-to-database comparison method) and two identically shaped circuit patterns. There are two well-known comparison inspection methods (generally called Die-to-die comparison methods).

  In either method, a small part of the mask pattern (hereinafter referred to as an observation region) is enlarged by an objective lens, and the enlarged optical image is detected by a CCD camera for inspection. Since a system called TDI (Time Delay Integration) is often used as the CCD camera, this CCD camera is called a TDI camera or a TDI sensor.

  As a light source for illuminating the observation region, a laser that continuously operates in the ultraviolet region or a point light source lamp having a spectrum in the ultraviolet region is used. An illumination method for irradiating ultraviolet light extracted from these lasers and lamps from the side opposite to the objective lens with respect to the mask is called transmitted illumination. On the other hand, an illumination method for illuminating the mask from the objective lens side is called reflected illumination. These two illumination methods are used because the appearance of the image captured by forming an optical image of the illuminated pattern on a TDI camera or the like is different, and the types of defects that can be detected are different. .

  Here, a configuration of an optical system of reflected illumination in a general pattern inspection apparatus 900 will be described with reference to FIG. FIG. 7 shows a case where a laser device (not shown) is used as the inspection light source. The linearly polarized laser beam L1 generated from the laser device enters the inspection optical system as an S wave. When this S wave enters a PBS (polarized beam splitter) 901, it is reflected and travels downward. The reason why the laser beam L1 is an S wave is that it is linearly polarized light having a polarization direction that is efficiently reflected by the PBS 901.

  Next, the S wave passes through the quarter wavelength plate 902 and is converted into circularly polarized light. Here, the S wave is converted into clockwise circularly polarized light. This circularly polarized light passes through the objective lens 903 and is irradiated onto the pattern surface of the mask 904. The reflected light from the pattern surface has a reverse polarization direction, that is, a counterclockwise circular polarization.

  This circularly polarized light passes through the objective lens 903 and again passes through the quarter wavelength plate 902. This returns to linearly polarized light, but this time it becomes a P wave. The P wave passes through the PBS 901. This P wave, which is reflected light from the pattern surface, passes through the projection lens 905 and reaches the TDI camera 906. At this time, the pattern surface of the mask 904 is projected onto the TDI camera 906 by the objective lens 903 and the projection lens 905. As a result, an enlarged image in the field of view of the objective lens 903 is captured, and defect inspection can be performed.

  On the other hand, a mask inspection apparatus that creates two different appearances in the optical image of the mask pattern by irradiating the mask inspection area with different forms of illumination light, and inspects using two TDI cameras as detectors Was sometimes used. This is shown in Patent Document 1. According to Patent Document 1, for example, it is possible to use reflective illumination on the half side of the field of view of the objective lens and transmit illumination on the other side. Thereby, the optical image of the mask pattern by these different illumination systems can be observed simultaneously.

  By the way, the EUV mask is called a reflection type mask because it exposes a pattern on a wafer by reflecting X-rays having a wavelength of 13.5 nm as exposure light. A cross-sectional structure of a general EUV mask is shown in FIG. As shown in FIG. 8, a multilayer film 11 made of Mo / Si that reflects X-rays is provided on the substrate 10. On the multilayer film 11, an absorber 13 that does not reflect X-rays is provided via a protective film 12.

  A conventional mask inspection apparatus can be used for EUV mask pattern inspection. However, since the EUV mask does not transmit light, it can be inspected only with reflected illumination as an illumination method. That is, the reflected light from the multilayer film 11 on the pattern surface irradiated with the reflected illumination light is detected. By projecting an optical image of the pattern surface onto the TDI camera with this reflected light, the pattern shape is imaged and defect inspection is performed.

  In addition, in a pattern inspection apparatus for an EUV mask, when two detectors are used for high-speed or high-sensitivity inspection, two types of reflected illumination light with different polarization states are irradiated, so that the appearance is improved. In some cases, an apparatus for observing different optical images with each detector is used. This is described in Patent Document 2.

  By the way, in an exposure apparatus that projects a mask pattern on a wafer in a reduced scale, illumination light that has been devised in various ways is used as the pattern becomes finer. The difference in illumination light is identified by the beam cross-sectional shape at the pupil position of the projection optical system. As illumination light, normal illumination, annular illumination, dipole illumination (also called dipole illumination), quadrupole illumination, and the like are widely used.

  There are cases where the polarization state is also used for the illumination method of the exposure apparatus. For example, in dipole illumination, it is known that resolution is improved by using linearly polarized light. Such an illumination method is called polarization dipole illumination. This is described in Patent Document 3, for example.

Japanese Patent No. 4701460 JP 2009-223095 A Japanese Patent Laid-Open No. 5-109601

  In the polarized dipole illumination, the resolution increases when the linearly polarized light in the oblique direction constituting the dipole illumination enters the wafer as an S wave. As a feature, a line pattern in a direction parallel to the polarization direction forms a clear image, but the line pattern in a direction perpendicular to the polarization direction has a poor image formation property. In order to improve the inspection sensitivity, when the polarization dipole illumination in the exposure device is applied to the mask pattern inspection device, the pattern in the direction parallel to the polarization direction can be inspected with high sensitivity, but the inspection sensitivity is in the pattern perpendicular to the polarization direction. Becomes worse.

  The present invention has been made against the background described above, and an object of the present invention is to provide a pattern inspection apparatus and a pattern inspection method capable of inspecting patterns in different directions with high sensitivity, and It is to provide a method of manufacturing a used pattern substrate.

  The pattern inspection apparatus according to the first aspect of the present invention is arranged at a position conjugate with the sample, changes the polarization state of a part of the illumination light, and changes the first linear polarization and the second linear polarization with different polarization directions. A half-wave plate for generating illumination light, separation means for separating the first linearly polarized light and the second linearly polarized light, a first beam and A beam shaping unit including first splitting means for generating two beams and second splitting means for splitting the second linearly polarized light in a second direction different from the first direction to generate a third beam and a fourth beam. And irradiating the first region which is a part of the field of view on the pattern substrate with the first beam and the second beam, and in the field of view, the third beam and the second beam in a second region different from the first region. An optical system for irradiating four beams, and the first and second beams. It comprises a first detector for detecting light from the patterned substrate by arm, the third, and a second detector for detecting light from the pattern substrate according to the fourth beam. Thereby, it is possible to inspect with high sensitivity for any of patterns in different directions.

The pattern inspection apparatus according to a second aspect of the present invention is characterized in that, in the inspection apparatus, a polarization direction of the first linearly polarized light and a polarization direction of the second beam are orthogonal to each other.
The pattern inspection apparatus according to a third aspect of the present invention is characterized in that, in the above-described inspection apparatus, the first direction and the second direction are orthogonal to each other.
This makes it possible to inspect a pattern substrate having patterns in two orthogonal directions with high sensitivity.

  In the pattern inspection apparatus according to a fourth aspect of the present invention, in the inspection apparatus described above, the first and second beams constitute polarized dipole illumination in the first direction, and the third and fourth beams provide the first. Two-direction polarization dipole illumination is configured.

  The pattern inspection apparatus according to a fifth aspect of the present invention is the above-described inspection apparatus, wherein the pattern substrate has a pattern extending in the X direction and the Y direction, and the first direction is substantially parallel to the X direction. The second direction is substantially parallel to the Y direction. This makes it possible to perform inspection with high sensitivity in both the X direction and the Y direction.

  The pattern inspection apparatus according to a sixth aspect of the present invention is characterized in that, in the above-described inspection apparatus, the beam shaping unit is disposed at a pupil position of the optical system.

  The pattern inspection apparatus according to a seventh aspect of the present invention is characterized in that, in the inspection apparatus described above, the optical path lengths of the first linearly polarized light and the second linearly polarized light in the beam shaping unit are substantially equal. Since the optical distances of the first linearly polarized light and the second linearly polarized light are equal, the illumination states of the two types of illumination light do not differ on the pattern surface of the pattern substrate. This makes it possible to detect defects with higher sensitivity.

  The pattern inspection apparatus according to an eighth aspect of the present invention is characterized in that in the above-described inspection apparatus, the first and second dividing means are roof prisms.

  The pattern inspection apparatus according to a ninth aspect of the present invention is the above-described inspection apparatus, wherein the illumination light generation means is disposed at a position conjugate with the pattern substrate and changes a polarization state of a part of incident light. It is a half-wave plate.

  In the pattern inspection apparatus according to the tenth aspect of the present invention, in the inspection apparatus, the half-wave plate is inserted up to a half position of a section of the illumination light.

  A pattern inspection method according to an eleventh aspect of the present invention generates illumination light including first linearly polarized light and second linearly polarized light having different polarization directions, and separates the first linearly polarized light and the second linearly polarized light. The first linearly polarized light is divided in a first direction to generate a first beam and a second beam, and the second linearly polarized light is divided in a second direction different from the first direction to obtain a third beam, Generating a fourth beam, combining the generated first, second, third, and fourth beams to irradiate the pattern substrate; detecting light from the pattern substrate by the first and second beams; Light from the pattern substrate by the third and fourth beams is detected. Thereby, it is possible to inspect with high sensitivity for any of patterns in different directions.

  In the pattern inspection method according to a twelfth aspect of the present invention, in the above inspection method, the polarization direction of the first linearly polarized light and the polarization direction of the second linearly polarized light are parallel to the pattern provided on the pattern substrate. It is characterized by being.

  A method for manufacturing a patterned substrate according to a thirteenth aspect of the present invention includes inspecting a mask by the inspection method described above, correcting defects in the inspected mask, exposing the substrate through the defect-corrected mask, The exposed substrate is developed.

  ADVANTAGE OF THE INVENTION According to this invention, the pattern inspection apparatus and pattern inspection method which can test | inspect with high sensitivity with respect to all the patterns of a mutually different direction can be provided.

It is a figure which shows the structure of the pattern inspection apparatus which concerns on Embodiment 1. FIG. It is a figure which shows the structure of the beam shaping part used with the pattern inspection apparatus which concerns on Embodiment 1. FIG. It is a figure for demonstrating the irradiation state of the illumination light by the pattern inspection apparatus which concerns on Embodiment 1. FIG. It is a figure which shows the other structure of the beam shaping part used with the pattern inspection apparatus which concerns on this invention. It is a figure which shows the structure of the pattern inspection apparatus which concerns on Embodiment 2. FIG. It is a figure which shows the other structure of the structure of the beam shaping part used with the pattern inspection apparatus which concerns on this invention. It is a figure which shows the structure of a normal pattern inspection apparatus. It is sectional drawing which shows an example of the structure of EUV mask.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. The following description explains the embodiment of the present invention, and the present invention is not limited to the following embodiment. For clarity of explanation, the following description is omitted and simplified as appropriate. Moreover, those skilled in the art can easily change, add, and convert each element of the following embodiments within the scope of the present invention.

  The present invention relates to a pattern inspection apparatus used when detecting a defect in a photomask (or also referred to as a reticle, but is simply referred to as a mask here) used in a semiconductor manufacturing process. The pattern inspection apparatus according to the present invention can perform inspection with high sensitivity for patterns in any direction orthogonal to each other using polarized dipole illumination.

Embodiment 1 FIG.
A pattern inspection apparatus according to Embodiment 1 of the present invention will be described with reference to FIGS. In the first embodiment, an inspection apparatus that performs pattern inspection of an EUV mask will be described as an example. FIG. 1 is a diagram illustrating a configuration of the entire illumination optical system of the pattern inspection apparatus 100 according to the first embodiment. FIG. 2 is a diagram illustrating a configuration of a beam shaping unit used in the pattern inspection apparatus 100. FIG. 3 is a diagram for explaining an irradiation state of illumination light by the pattern inspection apparatus 100.

  As shown in FIG. 1, a pattern inspection apparatus 100 includes lenses 101a, 101b, 101c, and 101d, a homogenizer 102, a half mirror 104, an objective lens 105, mirrors 107a and 107b, a projection lens 108, a space division mirror 109, and a beam shaping unit. 110, TDI cameras 120a and 120b, and a half-wave plate 130.

  A linearly polarized laser beam L1 is emitted from a laser device (not shown). The laser beam L1 is collected by the lens 101a, enters the homogenizer 102, and proceeds while repeating total reflection inside the laser beam L1. On the exit surface of the homogenizer 102, a beam having a uniform light intensity distribution is formed.

  The laser beam L1 emitted from the homogenizer 102 passes through the lens 101b. Thereby, the laser beam L1 is returned to a parallel beam. The laser beam L1 that has become a parallel beam passes through the lens 101c and is condensed. That is, the lens 101b and the lens 101c project an image at the exit end of the homogenizer 102 onto the condensing unit of the lens 101c.

  A half-wave plate 130 is disposed at the position of the condensing part of the lens 101c. That is, the half-wave plate 130 is disposed at a position conjugate with the emission surface of the homogenizer 102. The half-wave plate 130 is inserted up to a half position of the beam cross section in the condensing part of the lens 101c. That is, half of the laser light L1 collected by the lens 101c passes through the half-wave plate 130.

  In the present embodiment, an example in which the half-wave plate 130 is disposed in the lower half of the beam cross section is shown. The lower half of the beam cross section passes through the half-wave plate 130 and the upper half does not pass. As a result, reflected illumination light 103a including linearly polarized light in two orthogonal directions different in the upper half and the lower half of the beam cross section is generated. One laser beam extracted from the laser device is divided into two, and only one of them passes through the half-wave plate 130. As a result, two laser beams that are close to each other in orthogonal polarization directions can be formed.

  The reflected illumination light 103a is returned to a parallel beam through the lens 101d. The reflected illumination light 103a that has passed through the lens 101d hits the mirror 107a, is folded, and enters the beam shaping unit 110. However, since the reflected illumination light 103a passes through the lens 101d, the polarization state of the reflected illumination light 103b immediately before entering the beam shaping unit 110 is almost averaged within the beam cross section.

  The beam shaping unit 110 is provided at the pupil position of the objective lens 105 constituting the illumination optical system that projects the half-wave plate 130 onto the EUV mask 106. However, since the beam shaping unit 110 has a certain optical path length, the exact pupil position is substantially at the center of the beam shaping unit 110. Details of the beam shaping unit 110 will be described later with reference to FIG.

  The reflected illumination light 103c emitted from the beam shaping unit 110 is reflected by the half mirror 104 and travels downward like the reflected illumination light 103d. That is, two laser beams that are close to each other in the orthogonal polarization directions are incident on the same half mirror 104. In the half mirror, the incident light is linearly polarized light, and reflection and transmission occur at the same time regardless of the polarization direction of the linearly polarized light. From this, at least a part can be directed to the objective lens. The reflected illumination light 103 d enters the objective lens 105 and is condensed on a minute region on the EUV mask 106.

  In the EUV mask 106, an inspection area is set in an area irradiated with the reflected illumination light 103d. The light generated from this inspection region is diffracted light having pattern information. Of the diffracted light, diffracted light D11 passing through the objective lens 105 is incident on the half mirror 104. The diffracted light D12 passing through the half mirror 104 is folded back by the mirror 107b and passes through the projection lens 108.

  The diffracted light D13 that has passed through the projection lens 108 reaches the position of the space division mirror 109. The space division mirror 109 is inserted so that only half of the beam constituting the diffracted light D13 is incident. Half of the diffracted light D13 that does not strike the space division mirror 109 reaches the sensor surface 121a of the TDI camera 120a. The remaining half of the diffracted light D13 that strikes the space division mirror 109 strikes the sensor surface 121b of the TDI camera 120b. On the pattern surface of the EUV mask 106, the inspection area irradiated with the reflected illumination light 103d is projected onto the sensor surface 121a or the sensor surface 121b by the projection optical system including the objective lens 105 and the projection lens 108.

  Here, the beam shaping unit 110 shown in FIG. 1 will be described with reference to FIG. As shown in FIG. 2, the beam shaping unit 110 includes PBSs (polarization beam splitters) 111a and 111b, mirrors 112a and 112b, and roof prism pairs 113a and 113b.

  The cross-sectional shape of the reflected illumination light 103b incident on the beam shaping unit 110 is substantially circular. The reflected illumination light 103b includes linearly polarized light in two directions orthogonal to each other. The linearly polarized light in two directions orthogonal to each other is referred to as a P wave and an S wave, respectively. Here, the expressions P wave and S wave are used, but they are used to distinguish two lights whose polarization directions are orthogonal. When the reflected illumination light 103b is incident on the PBS 111a, the reflected illumination light 103b is separated into a P wave that passes through the PBS 111a and an S wave that is reflected.

  Each of the roof prism pairs 113a and 113b includes two roof prisms. The two roof prisms constituting the roof prism pair 113a are arranged so that their ridge lines face each other. The ridge line of one roof prism is parallel to the ridge line of the other roof prism. In the present embodiment, these ridge lines extend in a direction perpendicular to the paper surface.

  The P wave passes through the roof prism pair 113a and is divided into two beams A1 and A2 having a semicircular cross section. In the present embodiment, the P wave is divided in the vertical direction parallel to the paper surface. The cross-sectional shape of the beam A2 is a shape obtained by vertically inverting the cross-sectional shape of the beam A1. The arc portion in the cross-sectional shape of the beam A1 is opposed to the arc portion in the cross-sectional shape of the beam A2. These beams A1 and A2 strike the mirror 112a and are turned back to enter the PBS 111b.

  The two roof prisms constituting the roof prism pair 113b are arranged so that their ridge lines face each other. The ridge line of one roof prism is parallel to the ridge line of the other roof prism. In the present embodiment, these ridge lines extend in the vertical direction parallel to the paper surface. That is, the direction in which the ridge line of the roof prism of the roof prism pair 113b extends is orthogonal to the direction in which the ridge line of the roof prism of the roof prism pair 113a extends. That is, the roof prism pair 113b is arranged in a direction rotated 90 degrees around the optical axis direction of the roof prism pair 113a.

  The S wave reflected by the PBS 111a hits the mirror 112b, is folded, and passes through the roof prism pair 113b. The S wave is divided into two semicircular beams B1 and B2 by the roof prism pair 113b. In the present embodiment, the S wave is divided into two in the direction perpendicular to the paper surface. The cross-sectional shape of the beam B2 is a shape obtained by inverting the cross-sectional shape of the beam B1 left and right. The arc portion in the cross-sectional shape of the beam B1 is opposed to the arc portion in the cross-sectional shape of the beam B2. These beams B1 and B2 enter the PBS 111b.

  As described above, the beam shaping unit 110 divides one beam to form four beams. The polarization directions of the beams A1 and A2 are the same, and the polarization directions of the beams B1 and B2 are the same. The polarization directions of the beams A1 and A2 and the polarization directions of the beams B1 and B2 are orthogonal to each other.

  The optical position of the half-wave plate 130 is a conjugate position with the pattern surface of the EUV mask 106. In other words, the position where the reflected illumination light 103 a including linearly polarized light having polarization directions orthogonal to each other is formed is an optical position conjugate with the pattern surface of the EUV mask 106. As a result, the position where the reflected illumination light 103a including two laser beams close to each other in the polarization direction orthogonal to each other is projected onto the pattern surface by the projection optical system formed by the objective lens 105 and the lens 101d. The The position where the half-wave plate 130 is disposed is generally the position where the field stop is disposed.

  On the pattern surface of the EUV mask 106, two linearly polarized laser beams having polarization directions orthogonal to each other are irradiated to different adjacent areas. In the pattern inspection apparatus 100 according to the present embodiment, the two laser beams irradiated on the pattern surface are each divided into two beams by the beam shaping unit 110. For this reason, two beams are respectively incident on two adjacent regions irradiated with two laser beams having orthogonal polarization directions.

  Here, the irradiation state of illumination light will be described with reference to FIG. In FIG. 3, the direction in which the beams B1 and B2 are divided is the X direction, the direction in which the beams A1 and A2 are divided is the Y direction, and the direction perpendicular to the pattern surface of the EUV mask 106 is the Z direction. As shown in FIG. 3, within the field of view 105a of the objective lens 105 on the pattern surface of the EUV mask 106, the illumination areas A of the beams A1 and A2 that are P waves and the illumination areas B of the beams B1 and B2 that are S waves. Is formed. The illumination area A is illuminated by polarized dipole illumination consisting of beams A1 and A2, and the illumination area B is illuminated by polarization dipole illumination consisting of beams B1 and B2. However, when defining the polarization directions of the beams A1, A2, B1, and B2 irradiated obliquely to the EUV mask 106 with respect to the pattern surface of the EUV mask 106, all are S waves.

  In the example shown in FIG. 3, the beams A1 and A2 are irradiated onto the EUV mask 106 at substantially the same angle with respect to the normal line of the EUV mask 106 in the ZY plane. The polarization directions of the beams A 1 and A 2 are parallel to the X direction of the pattern surface of the EUV mask 106. The beams B1 and B2 are irradiated on the EUV mask 106 at substantially the same angle with respect to the normal line of the EUV mask in the XZ plane. The polarization directions of the beams B 1 and B 2 are parallel to the Y direction of the pattern surface of the EUV mask 106.

  In other words, the pattern inspection apparatus 100 can realize X-direction polarization dipole illumination in the illumination area A and Y-direction polarization dipole illumination in the illumination area B. Similarly to a general pattern inspection apparatus, the objective lens 105 and the projection lens 108 are arranged so that the pattern surface is projected onto the TDI cameras 120a and 120b. In the present embodiment, the space division mirror 109 is disposed immediately before the TDI cameras 120a and 120b. As a result, light from the inspection areas in the respective illumination areas A and B is projected onto the TDI cameras 120a and 120b, respectively. In the example shown in FIG. 1, the spatial division mirror 109 is arranged so that the S wave is incident on the TDI camera 120a and the P wave is incident on the TDI camera 120b. One of the two different TDI cameras detects an X-direction pattern, and the other detects a Y-direction pattern. Then, defect inspection is performed based on images acquired by the TDI cameras 120a and 120b.

  As described above, in the inspection apparatus of the present invention, different regions on the mask can be illuminated with each of two orthogonally polarized laser beams. In each region, dipole illumination is formed by two beams. Furthermore, each area can be observed by two different TDI cameras. Usually, the pattern of the EUV mask 106 is often composed of orthogonal vertical and horizontal patterns. In the pattern inspection apparatus 100, it is possible to perform inspection by using a polarized dipole illumination having a polarization direction parallel to each pattern. This makes it possible to perform inspection with high sensitivity for both vertical and horizontal patterns, regardless of the pattern direction.

  As shown in FIG. 2, in the beam shaping unit 110 used in the pattern inspection apparatus 100, the incident direction of the reflected illumination light 103b to the beam shaping unit 110 and the emission direction of the reflected illumination light 103c from the beam shaping unit 110 are as follows. Orthogonal. The optical path by the P wave and the S wave is rectangular. In the rectangular optical path, PBSs 111a and 111b are respectively arranged at two opposite corners, and mirrors 112a and 112b are respectively arranged at the other two opposite corners. The reflected light 103b is divided into a P wave and an S wave by the PBS 111a, and the P wave passes through the mirror 112a and the S wave passes through the mirror 112b until the PBS 111b merges again. Therefore, the optical path length of the P wave and the optical path length of the S wave are equal.

  As described above, since the optical distances of the P wave and the S wave in the beam shaping unit 110 are equal, the illumination states of the two types of illumination light of the P wave and the S wave do not differ on the pattern surface of the EUV mask 106. Thereby, it becomes possible to detect a defect with high sensitivity without depending on the direction of the pattern in the EUV mask 106.

  In addition, as shown in FIG. 4, you may use the beam shaping part 310 which has arrange | positioned the optical fixture so that incident light and an emitted light may become parallel instead of orthogonally crossing. In the beam shaping part 310 shown in FIG. 4, the optical path by P wave and S wave is a rectangular shape. In the rectangular optical path, PBSs 311a and 311b are respectively disposed at two adjacent corners along the P-wave optical path, and mirrors 312a and 312b are respectively disposed at the two corners along the S-wave optical path. The That is, the PBS 311a and the mirror 312b are respectively disposed at one opposite two corners, and the PBS 311b and the mirror 312a are respectively disposed at the other two opposite corners.

  In the beam shaping unit 310 shown in FIG. 4, the S wave whose optical path is bent by the PBS 311a passes through the mirrors 312a and 312b until it merges with the P wave again by the PBS 311b. That is, the optical path of the S wave is detoured. Therefore, unlike the optical path length of the P wave and the optical path length of the S wave, in the example shown in FIG. 4, the optical path of the S wave is longer than the optical path of the P wave.

Embodiment 2. FIG.
A pattern inspection apparatus according to Embodiment 2 of the present invention will be described with reference to FIG. FIG. 5 is a diagram showing a configuration of the entire illumination optical system of the pattern inspection apparatus 200 according to the second embodiment. The pattern inspection apparatus 200 is an apparatus for inspecting a normal photomask. The pattern inspection apparatus 200 performs transmission illumination on the photomask.

  As shown in FIG. 5, the pattern inspection apparatus 200 includes lenses 201a, 201b, 201c, and 201d, a homogenizer 202, a condenser lens 204, an objective lens 205, mirrors 207a and 207b, a projection lens 208, a space division mirror 209, and a beam shaping unit. 110, TDI cameras 220a and 202b, and a half-wave plate 230.

  A linearly polarized laser beam L2 is emitted from a laser device (not shown). The laser beam L2 is collected by the lens 201a, enters the homogenizer 202, and proceeds while repeating total reflection inside the laser beam L2. On the exit surface of the homogenizer 202, a beam having a uniform light intensity distribution is formed.

  The laser beam L2 emitted from the homogenizer 202 passes through the lens 201b. Thereby, the laser beam L2 is returned to a parallel beam. The laser beam L1 that has become a parallel beam is folded by the mirror 207a and condensed through the lens 201c. That is, the lens 201b and the lens 201c project an image at the exit end of the homogenizer 202 onto the condensing portion of the lens 201c, that is, the position of the field stop.

  A half-wave plate 230 is disposed at the position of the condensing unit of the lens 201c. That is, the half-wave plate 230 is disposed at a position conjugate with the emission surface of the homogenizer 202. The half-wave plate 230 is inserted up to a half position of the beam cross section in the condensing part of the lens 201c. That is, half of the laser beam L1 collected by the lens 201c passes through the half-wave plate 230.

  In the present embodiment, an example in which the half-wave plate 230 is arranged in the lower half of the beam cross section is shown. The lower half of the beam cross section passes through the half-wave plate 230 and the upper half does not pass. As a result, transmitted illumination light 203a including linearly polarized light in two orthogonal directions different in the upper half and the lower half of the beam cross section is generated. One laser beam extracted from the laser device is divided into two, and only one of them passes through the half-wave plate 130. Accordingly, it is possible to form transmitted illumination light 203a including two laser beams that are close to each other in directions of polarization orthogonal to each other.

  The transmitted illumination light 203a is returned to the parallel beam through the lens 201d. The transmitted illumination light 203 b returned to the parallel beam is incident on the beam shaping unit 110. However, since the transmitted illumination light 203b passes through the lens 201d, the polarization state of the transmitted illumination light 203 just before entering the beam shaping unit 110 is almost averaged within the beam cross section. As the beam shaping unit 110, the same one shown in FIG. 2 as that used in the first embodiment is used.

  The transmitted illumination light 203 c emitted from the beam shaping unit 110 passes through the condenser lens 204 and is condensed on a minute region on the photomask 206. In the photomask 206, an inspection area is set in an area irradiated with the transmitted illumination light 203c. The light generated from this inspection region is diffracted light having pattern information. Of the diffracted light, the diffracted light D21 passing through the objective lens 205 is folded back by the mirror 207b and passes through the projection lens 208.

  The diffracted light D22 that has passed through the projection lens 208 reaches the position of the space division mirror 209. The space division mirror 209 is inserted so that only half of the beam constituting the diffracted light D22 is incident. Half of the diffracted light D22 that does not strike the space division mirror 209 reaches the sensor surface 221a of the TDI camera 220a. The remaining half of the diffracted light D22 that strikes the space division mirror 209 strikes the sensor surface 221b of the TDI camera 220b. On the pattern surface of the photomask 206, the inspection area irradiated with the transmitted illumination light 203c is projected onto the sensor surface 221a or the sensor surface 221b by a projection optical system including the objective lens 205 and the projection lens 208.

  The optical position of the half-wave plate 230 is a conjugate position with the pattern surface of the photomask 206. That is, the position where the transmitted illumination light 203 a including linearly polarized light in the orthogonal polarization directions is formed is an optical position conjugate with the pattern surface of the photomask 206. As a result, the position at which the transmitted illumination light 203a including the two laser beams close to each other in the orthogonal polarization directions is formed is projected onto the pattern surface by the condenser lens 204. On the pattern surface of the photomask 206, two linearly polarized laser beams having polarization directions orthogonal to each other are irradiated to adjacent different regions.

  In the second embodiment, the beam shaping unit 110 is used as in the first embodiment. In the pattern inspection apparatus 200 of the present embodiment, the two laser beams irradiated on the pattern surface are each divided into two beams by the beam shaping unit 110. For this reason, two beams are respectively incident on two adjacent regions irradiated with two laser beams having orthogonal polarization directions.

  Therefore, in the pattern inspection apparatus 200, linearly polarized illumination light in two orthogonal directions is irradiated into the field of view of the condenser lens 204 in the photomask 206. Within the field of view of the pattern surface of the photomask 206, two illumination regions that are respectively illuminated by laser beams in two orthogonal directions are formed. As described above, in each illumination region, polarization dipole illumination in the X direction and polarization dipole illumination in the Y direction can be realized. The inspection area in each illumination area is projected onto the TDI cameras 220a and 220b. One of the two different TDI cameras detects an X-direction pattern, and the other detects a Y-direction pattern.

  In the pattern inspection apparatus 200, it is possible to inspect a photomask 206 configured with orthogonal vertical and horizontal patterns by polarization dipole illumination in a polarization direction parallel to each pattern. This makes it possible to inspect the pattern in any direction with high sensitivity regardless of the pattern direction.

  Here, a configuration of a beam shaping unit 410 which is an alternative to the beam shaping unit 110 used in the pattern inspection apparatus according to the present invention will be described with reference to FIG. FIG. 6 is a diagram illustrating a configuration of the beam shaping unit 410. The beam shaping unit 410 can be used in the pattern inspection apparatus 100 shown in FIG. 1 or the pattern inspection apparatus 200 shown in FIG.

  In the example illustrated in FIG. 6, an example in which the beam shaping unit 410 is applied to the pattern inspection apparatus 100 will be described. As shown in FIG. 6, the beam shaping unit 410 includes PBSs 411a and 411b, mirrors 412a and 412b, and space division mirrors 413a and 413b. In the beam shaping unit 410, the space dividing mirrors 413a and 413b are used when forming a semicircular beam.

  The cross-sectional shape of the reflected illumination light 103b incident on the beam shaping unit 410 is substantially circular. The reflected illumination light 103b includes linearly polarized light in two directions orthogonal to each other. The linearly polarized light in two directions orthogonal to each other is referred to as a P wave and an S wave, respectively. When the reflected illumination light 103b enters the PBS 411a, it is separated into a P wave that passes through it and an S wave that reflects it.

  The P wave transmitted through the PBS 411a reaches the space division mirror 413a. The space division mirror 413a is inserted so that only half of the P wave is incident. The half P wave that does not hit the space division mirror 413a goes straight, and the optical path of the remaining half P wave that hits the space division mirror 413a is bent.

  As a result, the P wave is divided into two beams having a semicircular cross section. In the present embodiment, the P wave is divided in the vertical direction parallel to the paper surface. Let these divided beams be A1 and A2. The cross-sectional shapes of the beams A1 and A2 are the same, and are semicircles with the arc portion facing upward when viewed from the straight direction of the beam.

  The beam that has traveled straight without hitting the space division mirror 413a is folded back by the mirror 412e and enters the PBS 411b. The beam whose optical path is bent upon hitting the space division mirror 413a is folded back by the mirrors 412c and 412e and enters the PBS 411b.

  The S wave reflected by the PBS 411a is folded back by the mirror 412b and reaches the space division mirror 413b. The space division mirror 413b is inserted so that only half of the S wave is incident. Half of the S wave that does not hit the space division mirror 413b goes straight, and the other half of the S wave that hits the space division mirror 413b has its optical path bent.

  As a result, the S wave is divided into two beams having a semicircular cross section. In the present embodiment, the S wave is divided in a direction perpendicular to the paper surface. Let these divided beams be B1 and B2. The cross-sectional shapes of the beams B1 and B2 are the same, and the arc portion is a semicircle with the left side viewed from the straight direction of the beam.

  The beam traveling straight without hitting the space division mirror 413b is incident on the PBS 411b. The beam whose optical path is bent upon hitting the space division mirror 413b is folded back by a mirror (not shown) and enters the PBS 411b.

  Thus, the beam shaping unit 410 divides two laser beams whose polarization directions are orthogonal to each other, thereby forming four beams. The polarization directions of the two beams generated from the P wave are the same, and the polarization directions of the two beams generated from the S wave are the same. The direction in which the two beams generated from the P wave are split is orthogonal to the direction in which the two beams generated from the S wave are split. That is, even when the beam shaping unit 410 is used, two illumination areas that are respectively illuminated by laser beams in two orthogonal directions are formed in the field of view of the pattern surface of the EUV mask 106. Y-direction polarization dipole illumination composed of beams A1 and A2 and X-direction polarization dipole illumination composed of beams B1 and B2.

  As described above, according to the present invention, the illumination areas adjacent to each other in the field of view are irradiated with the polarized dipole illumination in the polarization direction in the direction parallel to the orthogonal vertical and horizontal patterns, respectively. Can be performed. And the optical image of an adjacent illumination area is imaged with a different imaging device. As a result, even if the pattern is in the vertical direction or the horizontal direction, illumination can be performed so that one of the polarization directions follows the direction of the pattern, and the inspection is performed with high sensitivity without depending on the direction of the pattern. It becomes possible.

  The mask is inspected using the pattern inspection apparatus described above to detect a defect in the mask. Then, the defect-free mask is manufactured by correcting the defect of the mask. Thereby, the productivity of the mask can be improved. The substrate having the photosensitive resin is exposed using such a mask having no defect. Then, the exposed substrate is developed with a developer. Thereby, the photosensitive resin can be patterned with high accuracy. Therefore, a patterned substrate on which the photosensitive resin is patterned can be manufactured with high productivity. Further, when the photosensitive resin is a resist, the conductive film and the insulating film are etched through the patterned photosensitive resin. Thereby, productivity of pattern boards, such as a wiring board and a circuit board, can be improved.

  In the above-described embodiment, the example in which the roof prism pair or the space division mirror is used as the optical member that divides the P wave and the S wave to form four beams has been described. However, the present invention is not limited thereto. It is not something. It is also possible to use apertures instead of these.

  Further, the above-described inspection apparatus is not limited to the inspection of an EUV mask or a photomask, and any pattern substrate having a pattern can be used. Examples of the sample to be inspected include a color filter substrate.

  Also, a pattern inspection apparatus capable of realizing both illumination methods by combining the illumination optical system that realizes the reflected illumination described in the first embodiment and the illumination optical system that realizes the transmitted illumination described in the second embodiment. Is also possible.

DESCRIPTION OF SYMBOLS 100 Pattern inspection apparatus 101a, 101b, 101c, 101d Lens 102 Homogenizer 103a, 103b, 103c, 103d Reflection illumination light 104 Half mirror 105 Objective lens 105a Field of view 106 EUV mask 107a, 107b Mirror 108 Projection lens 109 Space division mirror 110 Beam shaping part 111a, 111b PBS
112a, 112b Mirror 113a, 113b Roof prism pair 120a, 120b TDI camera 121a, 121b Sensor surface 130 1/2 wavelength plate 200 Pattern inspection device 201a, 201b, 201c, 201d Lens 202 Homogenizer 203a, 203b, 203c Transmitted illumination light 204 Condenser Lens 205 Objective lens 206 Photomask 207a, 207b Mirror 208 Projection lens 209 Spatial division mirror 220a, 220b TDI camera 221a, 221b Sensor surface 230 1/2 wavelength plate 310 Beam shaping unit 311 PBS
312 Mirror 313 Roof prism pair 410 Beam shaping unit 411 PBS
412 Mirror 413 Spatial division mirror L1 Laser light D11, D12, D13, D21, D22 Diffracted light A, B Illumination area

Claims (13)

A half-wave plate that is arranged at a position conjugate with the sample, changes the polarization state of a part of the illumination light, and generates illumination light including first linear polarization and second linear polarization with different polarization directions;
Separating means for separating the first linearly polarized light and the second linearly polarized light; first dividing means for dividing the first linearly polarized light in a first direction to generate a first beam and a second beam; A beam shaping unit including second dividing means for dividing the two linearly polarized light into a second direction different from the first direction to generate a third beam and a fourth beam;
The first region that is a part of the field of view on the pattern substrate is irradiated with the first beam and the second beam, and the third beam and the fourth beam are irradiated on a second region different from the first region in the field of view. An optical system for irradiating
A first detector for detecting light from the pattern substrate by the first and second beams;
A second detector for detecting light from the pattern substrate by the third and fourth beams;
A pattern board inspection apparatus comprising:   The pattern inspection apparatus according to claim 1, wherein a polarization direction of the first linearly polarized light and a polarization direction of the second linearly polarized light are orthogonal to each other.   The pattern inspection apparatus according to claim 1, wherein the first direction and the second direction are orthogonal to each other. The first and second beams constitute polarized dipole illumination in the first direction,
The pattern inspection apparatus according to claim 1, wherein the third and fourth beams constitute polarized dipole illumination in the second direction. The pattern substrate has a pattern extending in the X direction and the Y direction,
The pattern inspection apparatus according to claim 1, wherein the first direction is substantially parallel to the X direction, and the second direction is substantially parallel to the Y direction.   The pattern inspection apparatus according to claim 1, wherein the beam shaping unit is disposed at a pupil position of the optical system.   The pattern inspection apparatus according to claim 1, wherein the optical path lengths of the first linearly polarized light and the second linearly polarized light in the beam shaping unit are substantially equal.   The pattern inspection apparatus according to claim 1, wherein the first and second dividing units are roof prisms.   The said illumination light generation means is a half-wave plate which is arrange | positioned in the conjugate position with the said pattern board | substrate, and changes the polarization state of a part of incident light. The pattern inspection apparatus according to item 1.   The pattern inspection apparatus according to claim 9, wherein the half-wave plate is inserted up to a half position of a cross section of the illumination light. Generating illumination light including first linearly polarized light and second linearly polarized light having different polarization directions;
Separating the first linearly polarized light and the second linearly polarized light;
Splitting the first linearly polarized light in a first direction to generate a first beam and a second beam;
Splitting the second linearly polarized light into a second direction different from the first direction to generate a third beam and a fourth beam;
Combining the generated first, second, third, and fourth beams to irradiate the pattern substrate;
Detecting light from the pattern substrate by the first and second beams;
A pattern inspection method for detecting light from the pattern substrate by the third and fourth beams.   The pattern inspection method according to claim 11, wherein a polarization direction of the first linearly polarized light and a polarization direction of the second linearly polarized light are parallel to a pattern provided on the pattern substrate. A mask is inspected by the inspection method according to claim 11 or 12, and the defect of the inspected mask is corrected,
Exposing the substrate through the defect-corrected mask,
A pattern substrate manufacturing method for developing the exposed substrate.

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