JP2011090169A - Mask inspection method and mask inspection device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a mask inspection device that can improve the defect detection sensitivity. <P>SOLUTION: The mask inspection device 100 includes: a light source 10 irradiating a mask 20 having a first pattern and a second pattern formed therein, which are approximately the same, with approximately the same plurality of illumination beams; photodetectors detecting a plurality of exiting beams from the first pattern and the second pattern each irradiated with the plurality of illumination beams; and a determination unit 17, which calculates a first defect determination signal by using one of exiting beams from the first pattern and one of exiting beams from the second pattern in the plurality of exiting beams, calculates a second defect determination signal by using one of exiting beams from the first pattern except for the exiting beam used for calculation of the first defect determination signal, and by using one of exiting beams from the second pattern, and determines a defect by using the first defect determination signal and the second defect determination signal. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a mask inspection method and apparatus used when detecting defects in a photomask (also referred to as a reticle, hereinafter simply referred to as a mask) used in a semiconductor manufacturing process.

  In general, there are two types of defect inspection methods for masks with patterns: a comparison inspection method (generally called die-to-database comparison method) between a mask pattern and design data, and a pattern comparison inspection method (generally called a die-to-database comparison method). There are two widely known methods, called Die-to-Die comparison methods.

  In any of these inspection methods, a small part of the mask pattern (hereinafter referred to as a visual field region) is magnified by the objective lens. The enlarged optical image is detected by a photodetector such as a CCD (Charge Coupled Device) sensor or a TDI (Time Delay Integration) sensor, and subjected to a comparative inspection. The mask inspection apparatus is outlined in, for example, Non-Patent Document 1.

  As a light source for illuminating the visual field 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 system in which ultraviolet light extracted from these lasers and lamps is irradiated from the side opposite to the objective lens with respect to the mask is called transmitted illumination. On the other hand, the illumination system that illuminates the mask from the objective lens side is called reflective illumination.

  In addition, in the Die-to-Die comparison method (hereinafter referred to as the DD comparison method), in order to improve defect inspection performance, that is, to improve inspection sensitivity, two TDI sensors are used for inspection by reflected illumination. And an inspection apparatus capable of simultaneously performing inspection using transmitted illumination. This is described in Patent Document 1, for example. Patent Document 2 uses two TDI sensors,

  If an attempt is made to reduce the size of a defect that can be detected in order to increase the inspection sensitivity of the mask inspection, the amount of illumination light that illuminates the small defect portion decreases. As a result, the variation in the amount of illumination light (unevenness in luminance) greatly affects the inspection result.

  That is, the detection signal of the pattern detected by the photodetector includes shot noise generated in the photodetector and speckle noise generated when a laser is used as the light source. When the light amount of the defect detection signal generated from the defective portion is reduced, the defect detection signal is buried in these noises.

  That is, in the DD comparison inspection, if there is a difference equal to or greater than the threshold in the luminance of each detection signal obtained by imaging the two patterns to be compared, this is determined as a defect. For this reason, a threshold value is set at a level higher than that of shot noise or speckle noise, and the defect is identified only when there is a luminance difference larger than this threshold value. For this reason, it becomes difficult to detect defects, and the detection sensitivity cannot be improved.

JP 2006-145989 A Japanese Patent No. 4185037

Toshiba Review, Vol. 58, No. 7, pp. 58-61, 2003

  The present invention has been made against the background of the above circumstances, and an object of the present invention is to provide a mask inspection method and a mask inspection apparatus capable of improving the defect detection sensitivity.

  The mask inspection method according to the first aspect of the present invention irradiates a plurality of substantially the same illumination light onto a mask on which substantially the same first pattern and second pattern are formed, and each of the plurality of illumination lights is irradiated. A plurality of emitted lights from the first pattern and the second pattern are detected, and one of the emitted light from the first pattern and one of the emitted light from the second pattern among the plurality of emitted lights; The first defect determination signal is calculated by using one of the emitted light from the first pattern other than the emitted light used for the calculation of the first defect determination signal and one of the emitted light from the second pattern. Is used to calculate a second defect determination signal, and a defect is determined using the first defect determination signal and the second defect determination signal. By performing the comparison inspection twice in this way, it becomes possible to improve the defect detection sensitivity.

  In the mask inspection method according to the second aspect of the present invention, in the above method, each of the first pattern and the second pattern when the first illumination light of the plurality of illumination lights is irradiated. The emitted light is detected by the first light detection unit, and the second illumination pattern from the first illumination pattern and the second illumination pattern when the second illumination light different from the first illumination light among the plurality of illumination lights is irradiated. Each outgoing light is detected by a second light detection unit different from the first light detection unit.

  In the mask inspection method according to a third aspect of the present invention, in the above method, the first illumination light is incident on a part of the field of view of the objective lens, and the second illumination light is applied to the other part of the objective lens. And the first illumination light and the second illumination light are condensed on the mask by the objective lens, and the first pattern and the first illumination light and the second illumination light in one scan The light emitted from the second pattern is detected. Thereby, two comparative inspections can be performed in one scan, and an increase in time required for the inspection can be suppressed.

  In the mask inspection method according to a fourth aspect of the present invention, in the above method, the first illumination light and the second illumination light are both reflected illumination light, and the mask is an EUV mask. And The present invention is particularly effective in such a case.

  A mask inspection apparatus according to a fifth aspect of the present invention includes an illumination optical system that irradiates a plurality of substantially identical illumination lights onto a mask on which substantially identical first and second patterns are formed, and the plurality of illumination lights. Detecting a plurality of emitted lights from the first pattern and the second pattern, and one of the emitted lights from the first pattern and the second of the plurality of emitted lights. The first defect determination signal is calculated using one of the emitted lights from the pattern, and one of the emitted lights from the first pattern other than the emitted light used for the calculation of the first defect determining signal and the second pattern And a determination unit that calculates a second defect determination signal using one of the emitted light from the first and determines a defect using the first defect determination signal and the second defect determination signal. By performing the comparison inspection twice in this way, it becomes possible to improve the defect detection sensitivity.

  The mask inspection apparatus according to a sixth aspect of the present invention is the mask inspection apparatus according to the above aspect, wherein the photodetector is the first pattern when the first illumination light of the plurality of illumination lights is irradiated. A first light detection unit for detecting respective emitted light from two patterns, and the first illumination pattern when the second illumination light different from the first illumination light among the plurality of illumination lights is irradiated, And a second light detection unit that detects each light emitted from the second illumination pattern.

  A mask inspection apparatus according to a seventh aspect of the present invention includes the objective lens for condensing the first illumination light and the second illumination light on the mask in the above apparatus, wherein the first illumination light is the objective light. The first illumination light and the second illumination light are incident on a partial area of the field of view of the lens, and the second illumination light is incident on another partial area of the field of view of the objective lens. The light emitted from the first pattern and the second pattern is detected. Thereby, two comparative inspections can be performed in one scan, and an increase in time required for the inspection can be suppressed.

  In the mask inspection apparatus according to an eighth aspect of the present invention, in the above apparatus, the first illumination light and the second illumination light are both reflected illumination light, and the mask is an EUV mask. It is what. The present invention is particularly effective in such a case.

  ADVANTAGE OF THE INVENTION According to this invention, the mask inspection method and mask inspection apparatus which can improve a defect detection sensitivity can be provided.

It is a figure which shows the structure of the mask inspection apparatus which concerns on Embodiment 1. FIG. It is a figure which shows the structure of the mask used as test object. It is a figure for demonstrating the visual field area | region in the visual field of the objective lens in the mask inspection apparatus which concerns on Embodiment 1. FIG. It is a figure which shows an example of the luminance distribution of each detection signal of the patterns P1 and P2 obtained with the TDI sensor 17a of the mask inspection apparatus which concerns on Embodiment 1. FIG. It is a figure which shows the brightness | luminance difference (P2a-P1a) of each detection signal of the patterns P1 and P2 shown in FIG. It is a figure which shows an example of the luminance distribution of each detection signal of the patterns P1 and P2 obtained with the TDI sensor 17b of the mask inspection apparatus which concerns on Embodiment 1. FIG. It is a figure which shows the luminance difference (P2b-P1b) of each detection signal of the patterns P1 and P2 shown in FIG. 5 is a diagram for explaining an inspection method according to Embodiment 1. FIG. It is a figure which shows the structure of the mask inspection apparatus which concerns on Embodiment 2. FIG.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. The following description shows preferred embodiments of the present invention, and the scope of the present invention is not limited to the following embodiments. In the following description, the same reference numerals indicate substantially the same contents.

Embodiment 1 FIG.
A mask inspection apparatus according to Embodiment 1 of the present invention will be described with reference to FIG. FIG. 1 is a diagram showing a configuration of a mask inspection apparatus 100 according to the present embodiment. Here, an example in which the inspection target is the mask 20 with the pellicle 24 will be described.

  First, the configuration of the mask 20 to be inspected will be described with reference to FIG. The mask 20 is a photomask used in an exposure process of a semiconductor or the like, and is also called a reticle. The mask 20 includes a substrate 21, a pattern 22, a pellicle frame 23, and a pellicle 24.

  The substrate 21 is a transparent substrate such as glass or quartz. A pattern 22 to be transferred at the time of exposure is formed on the substrate 21. The pattern 22 may be a halftone pattern, a phase shift pattern, or the like in addition to the light shielding pattern.

  As shown in FIG. 2, here, an example in which substantially the same U-shaped first pattern P1 and second pattern P2 are formed on the substrate 21 will be described. The first pattern P1 and the second pattern P2 are halftone patterns, and for example, MoSi is used.

  A frame-like pellicle frame 23 is mounted on the pattern surface side of the substrate 21. The pellicle frame 23 is attached so as to surround an area where the pattern 22 is formed. A pellicle 24 is attached to the side of the pellicle frame 23 opposite to the substrate 21. That is, the pellicle 24 is mounted on the mask 20 via the pellicle frame 23.

  The pattern 22 is arranged in a closed space (pellicle space) surrounded by the substrate 21, the pellicle frame 23, and the pellicle 24. Thereby, it can prevent that the foreign material which flies from the outside adheres to the pattern 22 surface.

  The mask inspection apparatus 100 inspects defects that adhere to the surface on which the pattern 22 is formed. Here, it is assumed that dirt (haze 25) that is opaque to the illumination light is attached to the second pattern P2 as a defect. Note that the defect is not limited to haze, but refers to a foreign substance, a pattern defect, or the like that should not be on the pattern 22 such as a particle.

  Here, an example with the pellicle 24 will be described as an example of the mask 20, but the inspection target of the mask inspection apparatus 100 is not limited to such a mask 20, and can be applied to a mask without a pellicle. .

  As shown in FIG. 1, the mask inspection apparatus 100 includes a light source 10, mirrors 11a and 11b, a condenser lens 12, an objective lens 13, a projection lens 14, a split mirror 15, TDI sensors 16a and 16b, and a determination unit 17. .

  The light source 10 irradiates the mask 20 on which the first pattern P1 and the second pattern P2 are formed with illumination light. As the light source 10, for example, an ultraviolet laser device that emits laser light having a wavelength of 193 nm can be used. In the mask inspection apparatus 100, the light extracted from the light source 10 is used as the transmitted illumination light L1.

  The transmitted illumination light L1 is guided to the lower side of the mask 20, reflected by the mirror 11a, and proceeds upward. Then, the transmitted illumination light L1 passes through the substrate 21 after passing through the condenser lens 12 and is irradiated on the pattern surface of the mask 20.

  The light generated from the inspection region passes through the objective lens 13, passes through the projection lens 14, and is divided into two by the division mirror 15. In the present embodiment, in mask inspection apparatus 100, two TDI sensors 16a and 16b are provided as photodetectors for detecting light generated from the inspection region.

  One light split by the split mirror 15 is received by the TDI sensor 16a. The other light split by the split mirror 15 is reflected by the mirror 11b and received by the TDI sensor 16b. Detection signals output from the TDI sensors 16 a and 16 b are input to the determination unit 17. The determination unit 17 determines at which position of the mask 20 the defect exists using detection signals from the TDI sensors 16a and 16b.

  Here, with reference to FIG. 3, the field region in the field of the objective lens in the mask inspection apparatus according to the present embodiment will be described. In general, in the Die-to-Die comparison method (DD comparison method), the mask 20 is scanned in the direction in which two identical patterns are arranged. That is, the illumination light is moved in the direction in which the first pattern P1 and the second pattern P2 are arranged. Each pattern is observed with the objective lens 13.

  In the present embodiment, the visual field region A inspected by the TDI sensor 16a and the visual field region B inspected by the TDI sensor 16b are arranged along the scanning direction of the mask 20 in the visual field of the objective lens 13. Therefore, the inspection of the first pattern P1 and the second pattern P2 in the visual field area A and the inspection of the first pattern P1 and the second pattern P2 in the visual field area B can be performed by one scan. That is, two identical patterns can be compared and inspected twice in one scan.

  For example, DD comparison inspection using each detection signal of the first pattern P1 and the second pattern P2 acquired in the visual field area A, and detection of each of the first pattern P1 and the second pattern P2 acquired in the visual field area B Two DD comparison inspections using a signal can be performed. Thereby, it is possible to suppress an increase in the time required for the mask inspection.

  The detection signal of the first pattern P1 in the visual field region A and the detection signal of the second pattern P2 in the visual field region B are compared, and the detection signal of the first pattern P1 in the visual field region B and the detection signal in the visual field region A are compared. You may compare with the detection signal of the 2nd pattern P2.

  Here, the mask inspection method according to the present invention will be described. FIG. 4 shows the detection signal P1a of the first pattern P1 and the detection signal P2a of the second pattern P2 obtained in the visual field region A. FIG. 5 shows a difference (P2a−P1a) between the detection signal P1a of the first pattern P1 and the detection signal P2a of the second pattern P2.

  FIG. 6 shows the detection signal P1b of the first pattern P1 and the detection signal P2b of the second pattern P2 obtained in the visual field region B. FIG. 7 shows a difference (P2b−P1b) between the detection signal P1b of the first pattern P1 and the detection signal P2b of the second pattern P2.

  Here, the detection signal is a numerical value of a luminance signal obtained by each pixel of the TDI sensors 16a and 16b receiving light generated from the first pattern P1 and the second pattern P2 when the transmitted illumination light L1 is irradiated from the light source 10. Signal. 4 and 6, the maximum value of the detection signal is set to 99 for easy understanding.

  4 and 6, portions where the first pattern P1 and the second pattern P2 are provided are indicated by broken lines. Also, the luminance difference (P2a-P1a) and the luminance difference (P2b-P1b) shown in FIGS.

  In the present embodiment, the portion of the substrate 21 transmits the irradiated light. As shown in FIGS. 4 and 6, the value of the detection signal of the substrate 21 portion is 95 to 99. Further, since the pattern 22 portion is a halftone pattern, part of the irradiated light is shielded, and the luminance is lower than that of the substrate 21 portion. The value of the detection signal in the pattern 22 portion is 18-23.

  On the other hand, the portion where the haze 25 is generated has lower brightness than the substrate 21 portion and higher brightness than the pattern 22 portion. In this example, the value of the detection signal in the portion where the haze 25 is generated is 91 to 92. As can be seen from FIGS. 4 and 6, even in the portion of the substrate 21 made of the same material, the detection signal varies from 95 to 99 depending on the location. Further, even in the pattern 22 made of the same MoSi, the detection signal varies from 18 to 23 depending on the location. This is due to speckle noise included in the transmitted illumination light L1 and shot noise in the TDI sensors 16a and 16b.

  After the scanning in each of the visual field areas A and B is completed, the luminance difference is calculated by calculating P2a-P1a and P2b-P1b, and a defect determination signal is obtained. As shown in FIGS. 5 and 7, the defect determination signal takes values from −4 to 4. The luminance difference corresponding to the minute defect portion to which the haze 25 is attached is -4 (absolute value 4).

  Conventionally, the defect inspection is performed by comparing the detection signal of the first pattern P1 and the detection signal of the second pattern P2 obtained in one visual field region. That is, in the conventional DD inspection, it is determined that there is a defect when the luminance difference in two identical patterns imaged by one TDI sensor is larger than a certain value (slice level).

  For example, the defect determination signal (FIG. 5) of P2a-P1a is compared with the slice level to determine the defect. In this case, in order to detect haze 25, the slice level (threshold) needs to be 4 or less. However, due to the presence of speckle noise in the illumination light applied to the mask or shot noise in the TDI sensor, the luminance difference is completely zero even in a portion where there is no defect. It remains slightly.

  In the example shown in FIG. 5, there is a portion where the absolute value of the luminance difference is 4 even in the portion of only the substrate 21 to which the haze 25 is not attached. As a result, a pseudo defect that is determined to be defective is detected even though there is actually no defect. As described above, conventionally, it is impossible to accurately detect a minute defect by the conventional DD comparison method.

  In contrast, in the inspection method according to the present invention, two DD comparison inspections are performed. That is, as described above, the first defect determination signal shown in FIG. 5 is calculated using the detection signals of the first pattern P1 and the second pattern P2 obtained in the visual field region A. Further, the second defect determination signal shown in FIG. 7 is calculated using the detection signals of the first pattern P1 and the second pattern P2 obtained in the visual field region B.

  Referring to FIGS. 5 and 7, the absolute value of the luminance difference corresponding to the portion where the haze 25 which is a minute defect is attached is 4. However, the portion where the luminance difference is 4 except for the portion where the haze 25 is attached in FIG. 5 is different in position from the portion where the luminance difference is 4 except for the portion where the haze 25 is attached in FIG.

  This is because speckle noise and shot noise are randomly generated, and it is extremely rare that a portion whose luminance changes based on these noises occurs at exactly the same position in two DD comparison inspections. Because.

  In the present embodiment, in two DD comparison inspections, it can be determined that a defect exists only at a position where the absolute value of the luminance difference is 4 or more in both cases. As a result, pseudo defects can be eliminated and defects can be accurately detected.

  It is also possible to lower the slice level. For example, two DD comparison inspections are performed with a slice level of 3. 8A and 8B show the DD comparison inspection results when the slice level is set to 3. FIG. FIG. 8A shows the inspection result of the first DD comparison inspection, and FIG. 8B shows the inspection result of the second DD comparison inspection. 8A and 8B, the horizontal axis indicates the position in the visual field region, and the vertical axis indicates the luminance difference.

  As shown in FIG. 8A, in the first DD comparison inspection, in addition to the actually existing defects, pseudo defects that are determined to be defective due to noise are detected. As described above, since noise is often generated at different positions, in the second DD comparison inspection, the possibility that a pseudo defect is generated at the same position as the position where the first pseudo defect is detected is extremely low.

  Accordingly, the determination unit 17 determines the position where the defect is detected in the first DD comparison inspection shown in FIG. 8A and the position where the defect is detected in the second DD comparison inspection shown in FIG. Are the same, it is determined that a true defect exists at that position. As a result, it is possible to detect a true defect that actually has a defect while eliminating the influence of speckle noise and shot noise.

  Thus, in the mask inspection method according to the present invention, the slice level can be set to a value lower than the maximum value of the luminance difference due to speckle noise or shot noise. For this reason, it is possible to detect even very minute defects.

  In this embodiment, the example in which the DD comparison inspection is performed twice has been described. However, the present invention is not limited to this. More than two DD comparison tests may be performed. Thereby, it is possible to improve inspection accuracy.

Embodiment 2. FIG.
The configuration of the mask inspection apparatus according to the second embodiment of the present invention will be described with reference to FIG. FIG. 9 is a diagram showing a configuration of a mask inspection apparatus 200 according to the present embodiment. 9, the same components as those in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted as appropriate.

  As shown in FIG. 9, the mask inspection apparatus 200 includes a light source 10, an objective lens 13, a projection lens 14, a split mirror 15, a TDI sensor 16a, a TDI sensor 16b, a determination unit 17, a wave plate 18, and a polarization beam splitter 19. ing. The mask inspection apparatus 200 is particularly effective for inspecting an EUV mask having a fine pattern.

  The light source 10 emits linearly polarized laser light having a wavelength of 193 nm. In the mask inspection apparatus 200, this linearly polarized laser light is irradiated from the pattern surface side of the EUV mask 30 and used as reflected illumination light. In the mask inspection apparatus 200, as in the first embodiment, two TDI sensors 16a and 16b are used as photodetectors for detecting inspection light from the pattern.

  The reflected illumination light emitted from the light source 10 is an S wave, which is reflected by the polarization beam splitter 19 and travels downward. Thereafter, the light reflected by the polarization beam splitter 19 is converted into circularly polarized light by the wave plate 18, passes through the objective lens 13, and is irradiated on the EUV mask 30 to be inspected.

  The light reflected by the EUV mask 30, that is, the light generated from the visual field area becomes circularly polarized light in the opposite direction. For this reason, after passing through the objective lens 13 and passing through the wave plate 18, it becomes P-polarized light. The light that has been P-polarized by the wave plate 18 passes through the polarization beam splitter 19 and travels upward.

  The light traveling upward passes through the projection lens 14 and is then split by the split mirror 15. One light split by the split mirror 15 is received by the TDI sensor 16a. The other light split by the split mirror 15 is reflected by the mirror 11b and received by the TDI sensor 16b.

  Similar to the first embodiment, also in the present embodiment, as shown in FIG. 3, the region inspected by the TDI sensor 16a and the region inspected by the TDI sensor 16b are along the scanning direction of the EUV mask 30. Are lined up. For this reason, two substantially identical patterns can be subjected to DD comparison inspection twice by one scan. Thereby, the time concerning an inspection can be shortened.

  In addition, since the determination unit 17 determines the true defect by performing the DD comparison inspection twice, the pseudo defect caused by speckle noise or shot noise can be excluded, and only a minute actual defect is detected. Can be detected.

  The EUV mask 30 has a finer pattern than a conventional ArF mask or the like. For this reason, even a minute defect that does not cause a problem with an ArF mask may cause a problem. By performing defect inspection of the EUV mask 30 by the mask inspection method according to the present invention in which multiple DD comparison inspections are performed, smaller defects can be detected.

  Further, in the case of a conventional ArF mask or the like, for example, as described in Japanese Patent Application Laid-Open No. 2008-190938, a method of inspecting by illuminating transmitted illumination and reflected illumination simultaneously using two TDI sensors Was sometimes used. Since an EUV mask cannot transmit illumination light, only inspection by reflected illumination can be applied.

  Even if an EUV mask is to be inspected using a mask inspection apparatus in which two TDI sensors are mounted for an ArF mask or the like, there remains a TDI sensor that performs inspection by transmitted illumination. In contrast, in the present invention, the remaining TDI sensor can be used effectively.

  That is, DD comparison inspection by reflected illumination can be performed by each of the two TDI sensors. Thereby, using two TDI sensors, it is possible to suppress the cost increase of the inspection apparatus and improve the inspection accuracy.

  Note that the present invention is not limited to the above-described embodiment, and can be changed as appropriate without departing from the spirit of the present invention. For example, two TDI sensors may not be provided and light generated from the mask may be received by one TDI sensor.

DESCRIPTION OF SYMBOLS 10 Light source 11a Mirror 11b Mirror 12 Condenser lens 13 Objective lens 14 Projection lens 15 Split mirror 16a TDI sensor 16b TDI sensor 17 Judgment part 18 Wave plate 19 Polarizing beam splitter 20 Mask 21 Substrate 22 Pattern 23 Pellicle frame 24 Pellicle 25 Haze 30 EUV mask DESCRIPTION OF SYMBOLS 100 Mask inspection apparatus 200 Mask inspection apparatus P1 1st pattern P2 2nd pattern

Claims (8)

Irradiating a plurality of substantially the same illumination light onto the mask on which the substantially identical first pattern and second pattern are formed,
Detecting a plurality of emitted lights from the first pattern and the second pattern when each of the plurality of illumination lights is irradiated;
Using one of the emitted light from the first pattern and one of the emitted light from the second pattern among the plurality of emitted lights, a first defect determination signal is calculated,
Using one of the emitted light from the first pattern other than the emitted light used for the calculation of the first defect determining signal and one of the emitted light from the second pattern, a second defect determining signal is calculated,
A mask inspection method for determining a defect using the first defect determination signal and the second defect determination signal. The first light detection unit detects each emitted light from the first pattern and the second pattern when the first illumination light of the plurality of illumination lights is irradiated,
Light emitted from the first illumination pattern and the second illumination pattern when the second illumination light different from the first illumination light among the plurality of illumination lights is irradiated with the first light detection unit. 2. The mask inspection method according to claim 1, wherein detection is performed by different second light detection units. Making the first illumination light incident on a part of the field of view of the objective lens, making the second illumination light incident on the other part of the objective lens,
The first illumination light and the second illumination light are condensed on the mask by the objective lens, and the first pattern and the second pattern by the first illumination light and the second illumination light in one scan. The mask inspection method according to claim 2, wherein light emitted from the pattern is detected. The plurality of illumination lights are all reflected illumination lights,
The mask inspection method according to claim 1, wherein the mask is an EUV mask. An illumination optical system that irradiates a plurality of substantially identical illumination lights to a mask on which substantially the same first pattern and second pattern are formed;
A photodetector for detecting a plurality of emitted lights from the first pattern and the second pattern when the plurality of illumination lights are respectively irradiated;
A first defect determination signal is calculated using one of the emitted light from the first pattern and one of the emitted light from the second pattern among the plurality of emitted lights, and is used to calculate the first defect determination signal. A second defect determination signal is calculated using one of the emitted light from the first pattern and one of the emitted light from the second pattern other than the used emitted light, and the first defect determining signal and the second defect are calculated. A determination unit that determines a defect using the defect determination signal;
A mask inspection apparatus comprising: The photodetector is
A first light detection unit for detecting respective emitted light from the first pattern and the second pattern when the first illumination light of the plurality of illumination lights is irradiated;
A second light detection unit that detects each of the emitted light from the first illumination pattern and the second illumination pattern when the second illumination light different from the first illumination light among the plurality of illumination lights is irradiated. When,
A mask inspection apparatus according to claim 5. An objective lens for condensing the first illumination light and the second illumination light on the mask;
The first illumination light is incident on a partial region of the objective lens field of view, and the second illumination light is incident on another partial region of the objective lens field of view, and the first illumination light is scanned once. The mask inspection apparatus according to claim 6, wherein light emitted from the first pattern and the second pattern by illumination light and the second illumination light is detected. The first illumination light and the second illumination light are both reflected illumination light,
The mask inspection apparatus according to claim 5, wherein the mask is an EUV mask.

Images