JP2009031601A - Photomask inspection method and photomask inspection apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To stably detect CD error defects regardless of a chip size. <P>SOLUTION: A photomask formed with a light shielding film pattern is irradiated with laser, and the image of the light shielding film pattern is acquired by changing the relative position of a laser and the photomask while reciprocating an irradiation spot of the laser within a micro range. The light shielding film pattern is inspected based on the acquired image. At this time, a direction to reciprocate the irradiation spot of the laser within the micro range is, for example, orthogonal to a main direction in which the light shielding film pattern is extended (step S1, inspection in a 0° direction). After acquiring images for the whole surface of the photomask in the orthogonal state, the photomask is rotated by 90° (step S2), and a direction to reciprocate the irradiation spot of the laser within the micro range is set parallel to the main direction of the pattern to acquire an image (step S3, inspection in a 90° direction). <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a photomask inspection method and a photomask inspection apparatus.

  In recent years, patterns of semiconductor devices such as LSIs have been miniaturized as technology has evolved, and photomask patterns used in photolithography processes for producing the patterns have also been miniaturized. If there is a defect in the pattern of the photomask, the defect is transferred to the wafer as it is, and a defective circuit is produced. Therefore, when manufacturing a photomask, it is necessary to inspect the light-shielding film pattern of the photomask and correct any defects. Note that in this specification, the photomask includes not only a reticle as a mask when performing reduced projection exposure but also a reticle as an original for producing a photomask.

  19 to 21 are diagrams schematically showing typical examples of defects in a photomask. The defect 1 shown in FIG. 19 is a light shielding film remaining in a portion that should be removed. The defect 2 shown in FIG. 20 is a part in which the light shielding film that should originally remain has been removed. Most of these two pattern defects can be detected by a conventional general photomask inspection apparatus. The defect 3 shown in FIG. 21 has a gradually changing edge position and is called a CD error defect. While the defect 1 shown in FIG. 19 protrudes locally, the CD error defect has a larger influence on the wafer because the line width increases in a wide range along the edge. Therefore, there is an increasing need to detect CD error defects.

  Conventionally, the following photomask defect inspection apparatuses have been proposed as inspection apparatuses for detecting CD error defects. This photomask defect inspection apparatus is an apparatus for detecting a photomask defect by a die-to-die method, and includes a first condenser lens that projects illumination light generated from a light source onto a photomask to be inspected, and a photomask A first objective lens that condenses the transmitted light that has passed through the mask, a first imaging device that receives the transmitted light emitted from the first objective lens, and the first objective lens and the first imaging device. A first inspection optical system including a first spatial low-pass filter disposed therebetween, a second condenser lens for projecting illumination light generated from the light source onto the photomask to be inspected, and the photomask transmitted A second objective lens that condenses the illumination light, a second imaging device that receives light emitted from the second objective lens, and a second objective lens disposed between the second objective lens and the second imaging device. Two spatial low-pass filters A second inspection optical system, an xy stage that supports the photomask and moves in the x direction and the y direction orthogonal to the x direction, and an output signal from the first imaging device as two-dimensional image information A first frame buffer to be accumulated; a first sampling unit for compressing the image signal accumulated in the first frame buffer to 1 / N and outputting; and a first frame for adding an output signal from the sampling unit A first signal processing circuit including addition means; a second frame buffer for storing an output signal from the second imaging device as a two-dimensional image; and an image signal stored in the second frame buffer. A second signal processing circuit comprising: a second sampling means for compressing to 1 / N and outputting; and a second addition means for adding the output signals from the sampling means; Characterized in that it comprises a defect detection circuit for generating an output signal is detected and the defect detection signal difference between the output signal of the second addition means adding means (e.g., see Patent Document 1.).

JP 2004-138948 A

  However, since the conventional general photomask inspection apparatus does not consider detecting a CD error defect, there is a problem in that the detection capability for the CD error defect is low. Moreover, in the inspection apparatus of the type which compares the die | dye disclosed by the said patent document 1, since a several die cannot be arrange | positioned on a photomask if a chip size is large, comparative inspection between dies is performed. There is a problem that can not be.

  An object of the present invention is to provide a photomask inspection method and a photomask inspection apparatus that can stably detect a CD error defect regardless of the chip size in order to eliminate the above-described problems caused by the prior art. To do.

  In order to solve the above-described problems and achieve the object, a photomask inspection method according to the present invention has the following features. The photomask on which the pattern of the light shielding film is formed is irradiated with laser, and the image of the pattern of the light shielding film is obtained by changing the relative position of the laser and the photomask while reciprocating the irradiation spot of the laser within a minute range. The pattern of the light shielding film is inspected based on the acquired image. At this time, the direction in which the laser irradiation spot is reciprocated in the minute range (hereinafter referred to as laser scanning direction) is, for example, orthogonal to the main direction (main pattern direction) in which the pattern of the light shielding film extends. After acquiring an image with respect to the entire surface of the photomask in this orthogonal state, the photomask is rotated by 90 °, or the laser scan direction is rotated by 90 °, so that the laser scan direction is the main pattern direction. You may make it acquire an image so that it may become parallel.

  When the photomask is rotated by 90 °, the photomask inspection apparatus according to the present invention includes a holder that holds the photomask and a holder driving unit that rotates the holder by 90 °. When the laser scanning direction is rotated by 90 °, the photomask inspection apparatus according to the present invention includes a laser control unit that rotates the laser scanning direction by 90 °. The present invention also detects a defect in the pattern of the light-shielding film by comparing image data obtained by laser irradiation with image data generated from photomask design data.

  According to the present invention, since the laser scanning direction intersects the main pattern direction, for example, the orthogonal direction, CD error defects can be easily detected. In addition, since image data acquired by laser irradiation is compared with image data generated from photomask design data, inspection can be performed even when the chip size is large.

  According to the photomask inspection method and the photomask inspection apparatus of the present invention, it is possible to stably detect a CD error defect regardless of the chip size.

  Exemplary embodiments of a photomask inspection method and a photomask inspection apparatus according to the present invention will be explained below in detail with reference to the accompanying drawings. In the following description, the same components are denoted by the same reference numerals, and redundant description is omitted.

(Embodiment 1)
FIG. 1 is a diagram showing a main part of a photomask inspection apparatus according to Embodiment 1 of the present invention. As shown in FIG. 1, the photomask inspection apparatus 10 is configured to irradiate a photomask 11 with a laser 12 and receive the laser 12 transmitted through the photomask 11 with a sensor 13. The photomask 11 is moved in the x direction and the y direction of the two-dimensional coordinate system by a driving mechanism (not shown). The laser 12 is vibrated by a vibration mechanism (not shown) so that the irradiation spot reciprocates within a minute range of the photomask 11 as indicated by a double arrow 14. The sensor 13 includes an objective lens and a light receiving element. The objective lens converges the laser 12 that vibrates in a minute range and makes it incident on the light receiving element.

  2 and 3 are diagrams for explaining the relationship between the laser movement and the photomask movement in the first embodiment. FIG. 2 shows a state in which the laser scanning direction indicated by the double arrow 14 is orthogonal to the main pattern direction (represented by three vertical lines in the photomask 11). FIG. 3 shows a state in which the laser scanning direction is parallel to the main pattern direction (represented by three horizontal lines in the photomask 11). The transition from the state of FIG. 2 to the state of FIG. 3 is realized by rotating the photomask 11 by 90 °. In these drawings, a single arrow indicated by reference numeral 15 represents the movement of the photomask.

  FIG. 4 is a diagram showing the configuration of the photomask inspection apparatus according to the first embodiment of the present invention. As shown in FIG. 4, the photomask inspection apparatus 10 includes a design data development unit 21, an image data development unit 22, an image data storage unit 23, a defect inspection unit 24, a light source 25, a laser vibration unit 26, an objective lens 27, and a light reception. An element 28, a data correction unit 29, a defect information storage unit 30, a stage 31, a holder 32, a lens control unit 33, a holder drive unit 34, a stage drive unit 35, and a control unit 36 are provided.

  The stage 31 is moved in the x direction and the y direction by the stage driving unit 35. A holder 32 is placed on the stage 31. The holder 32 holds the photomask 11 and is rotated by 90 ° by the holder driving unit 34. The holder driving unit 34 is configured by, for example, a stepping motor. The control unit 36 controls the rotation angle and the rotation timing of the holder driving unit 34. The light source 25 is composed of a semiconductor laser or the like, and emits the laser 12.

  The laser vibration unit 26 vibrates the laser 12 emitted from the light source 25 so that the irradiation spot on the photomask 11 reciprocates in a minute range. The laser vibration unit 26 is configured by an optical element such as a mirror that changes the optical axis of the laser 12, and vibrates the optical axis of the laser 12 when the optical element vibrates.

  The objective lens 27 causes the lens control unit 33 to focus the laser 12 that vibrates in a minute range and make it incident on the light receiving element 28. The light receiving element 28 is configured by a photodiode or the like, and converts the received optical signal of the laser 12 into an electrical signal. In FIG. 4, a thick arrow between the light source 25 and the light receiving element 28 represents the laser 12. The lens control unit 33 and the stage drive unit 35 are controlled by the control unit 36.

  The design data expansion unit 21 expands design data 37 input from the outside. The image data development unit 22 develops the design data developed by the design data development unit 21 into image data based on the correction information of the data correction unit 29. The data correction unit 29 outputs correction information so that the image data generated from the design data 37 and the image data generated from the output signal of the light receiving element 28 correspond to each other in the defect inspection unit 24. The image data storage unit 23 stores the image data developed by the image data development unit 22.

  The defect inspection unit 24 compares the image data based on the design data 37 stored in the image data storage unit 23 and the image data generated from the output signal of the light receiving element 28, and the light shielding formed on the photomask 11. Detect defects in the film pattern. The defect information storage unit 30 stores information on defects detected by the defect inspection unit 24. The defect inspection unit 24 and the defect information storage unit 30 are also controlled by the control unit 36.

  FIG. 5 is a diagram for explaining the procedure of the photomask inspection method according to the first embodiment of the present invention. Before starting the inspection, the photomask 11 is attached to the holder 32 so that the main pattern direction is, for example, orthogonal to the laser scanning direction. At this time, for example, the main pattern direction may be the longitudinal direction of the gate electrode pattern of the transistor, and the laser 12 may acquire an image while traversing the gate electrode pattern.

  As shown in FIG. 5, when the inspection is started, first, the photomask 11 is moved in the x direction and the y direction by the stage 31 in a state where the laser scanning direction and the main pattern direction are orthogonal to each other. (Step S1). Hereinafter, the inspection in a state where the laser scanning direction and the main pattern direction are orthogonal to each other is referred to as an inspection at 0 °. When the inspection in the direction of 0 ° with respect to the entire surface of the photomask 11 is completed, the holder 32 is rotated and the photomask 11 is rotated 90 ° (step S2).

  Next, in a state where the laser scan direction and the main pattern direction are parallel, the photomask 11 is inspected by moving the photomask 11 in the x and y directions by the stage 31 (step S3). Hereinafter, the inspection in a state where the laser scanning direction and the main pattern direction are parallel is referred to as an inspection at a 90 ° direction. Then, when the inspection in the 90 ° direction with respect to the entire surface of the photomask 11 is completed, the inspection is ended.

  FIG. 6 shows the relationship between the laser scan direction and the photomask pattern in the inspection at 0 °. FIG. 7 shows the relationship between the laser scan direction and the photomask pattern in an inspection at a 90 ° orientation. In the photomask 11 shown in these drawings, the filled portion indicated by reference numeral 16 is a light shielding film extending in the main pattern direction. A portion indicated by reference numeral 17 is a CD error defect.

  According to the first embodiment, in the inspection in the direction of 0 ° in step S1, as shown in FIG. 6, since the laser 12 crosses the light shielding film 16 extending in the main pattern direction, the laser 12 extends in the main pattern direction. The CD error defect 17 extending along the edge of the light shielding film 16 can be detected. The photomask 11 is also formed with a light shielding film extending in a direction intersecting the main pattern direction, for example, a direction orthogonal to the main pattern direction (hereinafter referred to as a subpattern direction). In the inspection in the direction of 0 ° in step S1, the sub-pattern direction and the laser scanning direction are parallel, so that the detection accuracy of the CD error defect extending along the edge of the light shielding film extending in the sub-pattern direction is the main pattern direction. The detection accuracy of the CD error defect extending along the edge of the light-shielding film extending in the direction is low.

  Therefore, by rotating the photomask 11 by 90 ° in step S2, the laser 12 crosses the light shielding film extending in the subpattern direction in the inspection in the direction of 90 ° in step S3, so that the photomask 11 extends in the subpattern direction. A CD error defect extending along the edge of the light shielding film can be detected. Further, according to the first embodiment, since the defect inspection unit 24 compares the image data acquired by the irradiation of the laser 12 with the image data generated from the photomask design data 37, the chip size is reduced. Inspection can be performed even if it is large.

(Embodiment 2)
FIG. 8 is a diagram showing the configuration of the photomask inspection apparatus according to the second embodiment of the present invention. As shown in FIG. 8, the photomask inspection apparatus 40 of the second embodiment is similar to the photomask inspection apparatus 10 (see FIG. 4) of the first embodiment in that a vertical pattern area extraction unit 41, a coordinate conversion calculation unit 42, and a vertical A pattern area storage unit 43 is added. By these units, in the second embodiment, the inspection target region in the 90 ° direction is extracted in advance before performing the inspection in the 90 ° direction.

  The vertical pattern area extraction unit 41 extracts, for example, a region in which the laser scanning direction and the direction in which the light shielding film pattern extends are parallel from the light shielding film pattern during the inspection in the direction of 0 °. The area extracted by the vertical pattern area extraction unit 41 is defined as a vertical pattern area. In the vertical pattern area, the laser scanning direction and the direction in which the pattern of the light shielding film extends are perpendicular to each other in the inspection at a 90 ° orientation. The vertical pattern area extraction unit 41 extracts the vertical pattern area using the design data developed by the design data development unit 21 as the pattern data of the light shielding film. Alternatively, the vertical pattern area extraction unit 41 generates, as pattern data of the light shielding film, from the image data developed by the image data development unit 22, the image data stored in the image data storage unit 23, or the output signal of the light receiving element 28. The image data to be processed may be used.

  The vertical pattern area may be an area excluding the portion of the light shielding film pattern where the laser scanning direction and the direction in which the light shielding film pattern extends are orthogonal to each other. In this case, in the inspection at a 90 ° orientation, a region where the laser scanning direction and the direction in which the pattern of the light shielding film extends is excluded. The coordinate conversion calculation unit 42 calculates and obtains coordinates obtained by rotating the coordinates of the vertical pattern area extracted by the vertical pattern area extraction unit 41 by 90 °. The vertical pattern area storage unit 43 stores the coordinates after the 90 ° rotation converted by the coordinate conversion calculation unit 42. The control unit 36 controls the stage driving unit 35 based on the coordinates stored in the vertical pattern area storage unit 43 when performing the inspection in the 90 ° orientation. Other configurations are the same as those in the first embodiment.

  FIG. 9 is a diagram for explaining the procedure of the photomask inspection method according to the second embodiment of the present invention. Attachment of the photomask before the start of inspection is the same as in the first embodiment. Further, as shown in FIG. 9, the inspection in the 0 ° direction after the start of inspection (step S11), the photomask 90 ° rotation (step S12), and the inspection in the 90 ° direction (step S13) are performed. This is the same as step S1, step S2 and step S3 of the first embodiment. In the second embodiment, the process of extracting the area of the vertical pattern is performed during the inspection in the direction of 0 ° in step S11 (step S14). The area extraction process of the vertical pattern will be described later.

  Then, the coordinates when the coordinates of the extracted vertical pattern area are rotated by 90 ° are extracted (step S15). In step S13, only the coordinate area extracted in step S15 is inspected in the 90 ° direction. When inspecting at an angle of 90 °, for example, the laser may be reciprocated once in a minute range with respect to one edge. However, it is preferable to reciprocate the laser several times with respect to one edge in a minute range because sufficient image information can be obtained.

  FIG. 10 is a diagram for explaining the procedure of vertical pattern area extraction processing. As shown in FIG. 10, when the vertical pattern area extraction process is started, the vertical pattern area extraction unit 41 detects vertical edges based on the acquired pattern data (step S21). The term “vertical edge” refers to an edge of a light shielding film pattern extending in a direction parallel to the laser scanning direction. Next, the length (distance) of the detected vertical edge is calculated and obtained (step S22). If the edge length is, for example, 5 pixels or more, the inspection is performed in a 90 ° direction (step S22: 5 pixels or more), and the process proceeds to step S23. If the edge length is less than 5 pixels, for example, it is excluded from the object to be inspected in the 90 ° direction (step S22: less than 5 pixels), and the process proceeds to step S26.

  Here, a pixel is a minimum unit for dividing an image, and in a state-of-the-art inspection apparatus, the pixel size is 100 nm or less. In this embodiment, the length of the edge in the vertical direction is set to 5 pixels as a criterion for determining whether or not to inspect at an angle of 90 °. However, the present invention is not limited to this. It may be an arbitrary number of pixels equal to or less than 6 pixels. When the vertical edge is to be inspected at an angle of 90 °, the coordinates of the lower end and the upper end of the edge are extracted (step S23). Then, the coordinate conversion calculation unit 42 converts the extracted coordinates into coordinates rotated by 90 ° (step S24). For example, when the point at the coordinates (a, b) is rotated 90 ° counterclockwise, the coordinates are (−b, a).

  Next, the converted coordinates are stored in the vertical pattern area storage unit 43 (step S25). Thereafter, it is determined whether or not there is a remaining pattern (step S26). If the pattern remains (step S26: present), the process returns to step S21 and the above-described processing is repeated until there are no more patterns. If there are no remaining patterns (step S26: No), the process is terminated, and the process returns to step S15.

  According to the second embodiment, the inspection of the photomask can be completed in a shorter time than in the first embodiment by extracting the inspection target edge in the 90 ° direction in advance. When an inspection is performed at a 90 ° orientation, a CD error defect can be detected even if an area in which the extending direction of the light shielding film pattern is not perpendicular to the laser scanning direction is excluded from the inspection target. There is no problem.

(Embodiment 3)
FIG. 11 is a diagram for explaining the relationship between the laser movement and the photomask movement in the third embodiment. As shown in FIG. 11, in the third embodiment, instead of rotating the photomask 11 by 90 °, the laser scan direction is rotated by 90 °, so that the laser scan direction and the main pattern direction are in parallel. I do. The state in which the laser scanning direction is orthogonal to the main pattern direction is as shown in FIG. As in the first embodiment, the inspection in the state shown in FIG. 2 is an inspection in the direction of 0 °. In the third embodiment, the inspection in the state shown in FIG. 11 is an inspection in a 90 ° direction. The transition from the state of FIG. 2 to the state of FIG. 11 is realized by rotating the vibration direction of the laser 12 by 90 °.

  FIG. 12 is a diagram showing the configuration of the photomask inspection apparatus according to the third embodiment of the present invention. As shown in FIG. 12, in the photomask inspection apparatus 50 of the third embodiment, a laser control unit 51 is added to the photomask inspection apparatus 10 (see FIG. 4) of the first embodiment. The laser control unit 51 controls the angle of a mirror or the like constituting the laser vibration unit 26 so that the vibration direction of the laser 12 is rotated by 90 °. The control unit 36 controls the rotation angle and rotation timing of the mirror and the like. In the third embodiment, a holder for rotating the photomask 11 by 90 ° is not necessary. The photomask 11 is placed directly on the stage 31. Other configurations are the same as those in the first embodiment.

  FIG. 13 is a diagram for explaining the procedure of the photomask inspection method according to the third embodiment of the present invention. Attachment of the photomask before the start of inspection is the same as in the first embodiment. Further, as shown in FIG. 13, the inspection (step S31) in the direction of 0 ° after the start of the inspection is the same as step S1 of the first embodiment. In the third embodiment, when the inspection in the direction of 0 ° in step S31 is completed, the laser control unit 51 and the laser vibration unit 26 rotate the vibration direction of the laser 12, that is, the laser scanning direction by 90 °. Then, an inspection is performed in a 90 ° direction (step S32). When the inspection in the direction of 90 ° with respect to the entire surface of the photomask 11 is completed, the inspection is ended.

(Embodiment 4)
FIG. 14 is a diagram showing a configuration of a photomask inspection apparatus according to Embodiment 4 of the present invention. As shown in FIG. 14, the photomask inspection apparatus 60 of the fourth embodiment includes a vertical pattern area extraction unit 41 and a vertical pattern area storage unit 43 in addition to the photomask inspection apparatus 50 (see FIG. 12) of the third embodiment. In addition, before performing the inspection in the 90 ° direction, the inspection object region in the 90 ° direction is extracted in advance. That is, the third embodiment is a combination of the functions added to the first embodiment in the second embodiment. However, in the fourth embodiment, since the photomask 11 does not rotate, there is no coordinate conversion calculation unit.

  FIG. 15 is a diagram for explaining the procedure of the photomask inspection method according to the fourth embodiment of the present invention. Attachment of the photomask before the start of inspection is the same as in the first embodiment. Further, as shown in FIG. 15, the inspection in the 0 ° direction (step S41) and the inspection in the 90 ° direction (step S42) after the start of the inspection are the same as step S31 and step S32 in the third embodiment. It is. In the fourth embodiment, the process of extracting the area of the vertical pattern is performed during the inspection in the direction of 0 ° in step S41 (step S43). In step S42, only the region extracted in step S43 is inspected in a 90 ° direction. At that time, the laser may be reciprocated once in a minute range with respect to one edge, or the laser may be reciprocated several times.

  FIG. 16 is a diagram for explaining the procedure of the vertical pattern area extraction process. In Embodiment 4, since the photomask 11 is not rotated, it is not necessary to perform coordinate conversion when the photomask 11 is rotated by 90 °. Therefore, as shown in FIG. 16, the vertical edge is detected (step S51), the distance between the edges is calculated (step S52), and the coordinates of the lower end and the upper end of the edge to be inspected in the 90 ° direction are detected. Is extracted (step S53). Then, the extracted coordinates are stored as they are without conversion (step S54), and the presence or absence of the remaining pattern is determined (step S55). The details of the processing contents in steps S51, S52, S53, S54, and S55 are the same as those in steps S21, S22, S23, S25, and S26 described in the second embodiment, respectively. It is.

  Next, a CD error defect evaluation experiment conducted by the present inventor will be described. FIG. 17 is a diagram for explaining an evaluation experiment for a CD error defect. FIG. 18 is a diagram showing the results of a CD error defect evaluation experiment. In this evaluation experiment, a reticle having a CD error defect (hereinafter referred to as a defect reticle) was prepared. As shown in FIG. 6, the pattern of the light shielding film was a pattern in which linear patterns with a width of 360 nm were arranged at intervals of 360 nm. As partly enlarged in FIG. 17, a CD error defect 17 is formed in a part of the light shielding film 16.

  The defect sizes of the CD error defect 17 are 42 nm and 36 nm as shown in FIG. Here, the defect size is a protruding amount (d) of the CD error defect 17. The results of AIMS (Aerial Image Measurement System) of each CD error defect 17 are −20% (d = 42 nm) and −17% (d = 36 nm). AIMS is a light intensity simulator and has an optical system similar to a stepper. AIMS is commonly used to investigate the effect of photomask defects on a wafer. In the case of performing an evaluation with AIMS, the CD fluctuation amount at the defective place is obtained by using the CD at the defective place as a reference.

  The evaluation result shown in FIG. 18 shows that the CD varies by 20% on the wafer, even though the defect size d is 42 nm (42/360 = 12%) on the photomask. This is because the MEF (Mask Error Factor) is large, and the defect size on the photomask has a greater influence on the wafer. Thus, the influence on the wafer by the CD error defect is great.

  Moreover, the photomask inspection method according to the above-described embodiment was performed using this defect reticle, and the defect detection rate was examined. FIG. 18 also shows the result. When the inspection in the direction of 0 ° was continuously performed 5 times, the CD error defect 17 could be detected 5 times regardless of the size of the defect. The detection rate is 100%. On the other hand, although the inspection at a 90 ° orientation was performed five times continuously, the CD error defect 17 could not be detected at all five times regardless of the size of the defect. The detection rate is 0%. From this result, it can be seen that micro defects can be detected stably by making the laser scanning direction orthogonal to the pattern direction.

  Normally, a vertical pattern and a horizontal pattern (main pattern and subpattern) are mixed in the photomask. Therefore, as in each embodiment, by performing both the inspection at 0 ° and the inspection at 90 °, the CD error defect generated in the vertical pattern and the horizontal pattern occurred. CD error defects can be detected. Conventionally, the inspection is performed only in the direction of 0 ° or the inspection in the direction of 90 °, so that the CD error defect is missed.

  In the above, this invention is not restricted to each embodiment mentioned above, A various change is possible. In addition, when the photomask inspection apparatus does not include a mechanism for rotating the photomask by 90 ° or a mechanism for rotating the laser scanning direction by 90 °, after the inspection in the direction of 0 ° is completed, the operator The photomask may be removed from the stage, and the photomask may be attached to the stage again after being rotated by 90 °. Even in this way, the photomask inspection method according to the present invention can be carried out.

  In addition, when a pattern having a high CD required accuracy, such as a gate electrode of a transistor, that is, a critical pattern is uniformly arranged as either a main pattern or a sub-pattern, is performed. It is not necessary to perform both the 0 ° inspection and the 90 ° inspection. Only the inspection in the direction in which the laser scanning direction is orthogonal to the direction in which the critical pattern extends may be performed. The photomask inspection method according to the present invention can also be applied to the case where inspection is performed by a die-to-die method.

(Appendix 1) In a photomask inspection method for irradiating a photomask with a pattern formed thereon, moving an irradiation spot of the laser to obtain an image of the pattern, and inspecting the pattern based on the image, A photomask inspection method comprising: detecting an extending direction of an edge of the pattern; and determining a moving direction of the irradiation spot based on the extending direction of the edge.

(Supplementary note 2) The photomask inspection method according to supplementary note 1, wherein a direction in which the irradiation spot moves and a direction in which the edge of the pattern extends are orthogonal to each other.

(Additional remark 3) After acquiring the image with respect to the whole surface of the said photomask in the 1st state in which the direction where the said irradiation spot moves, and the said extending | stretching direction of the said edge of the said pattern are orthogonal, the said irradiation spot moves 2. The photomask inspection method according to appendix 1, wherein an image is acquired in a second state in which the direction and the extending direction of the edge of the pattern are parallel to each other.

(Additional remark 4) The area | region which acquires an image in the said 2nd state is a part of the said pattern in which the direction where the said irradiation spot moves in the said 1st state, and the extending direction of the said edge of the said pattern are orthogonal 4. The photomask inspection method according to appendix 3, wherein the region is excluded.

(Additional remark 5) The area | region which acquires an image in the said 2nd state is an area | region where the direction where the said irradiation spot moves in the said 1st state and the extending direction of the said edge of the said pattern are parallel among the said patterns The photomask inspection method according to appendix 3, wherein:

(Appendix 6) In a photomask inspection apparatus that irradiates a photomask on which a pattern is formed, moves an irradiation spot of the laser to acquire an image of the pattern, and inspects the pattern based on the image, A light source that emits the laser, a laser vibration unit that moves an irradiation spot of the laser emitted from the light source, a holder that holds the photomask, a holder driving unit that rotates the holder by 90 °, and the holder A photomask inspection apparatus comprising: a stage that moves the laser beam in a two-dimensional direction; and a light receiving element that receives the laser.

(Appendix 7) Based on the image data generated from the output signal of the light receiving element, the direction in which the laser irradiation spot reciprocates and the direction in which the pattern of the light shielding film extends out of the light shielding film pattern are orthogonal to each other The photomask inspection apparatus according to appendix 6, further comprising: an extraction unit that extracts an area excluding the portion to be removed; and a coordinate conversion unit that rotates the coordinates of the area extracted by the extraction unit by 90 ° .

(Appendix 8) Based on the image data generated from the photomask design data, the direction in which the laser irradiation spot reciprocates and the direction in which the light shielding film pattern extends out of the light shielding film pattern are orthogonal to each other. The photomask inspection apparatus according to appendix 6, further comprising: an extraction unit that extracts an area excluding the portion to be removed; and a coordinate conversion unit that rotates the coordinates of the area extracted by the extraction unit by 90 ° .

(Additional remark 9) Based on the image data produced | generated from the output signal of the said light receiving element, the direction to reciprocate the said laser irradiation spot and the direction where the pattern of the light shielding film are extended are parallel among the patterns of the light shielding film 7. The photomask inspection apparatus according to appendix 6, further comprising: an extraction unit that extracts a region to become, and a coordinate conversion unit that rotates the coordinates of the region extracted by the extraction unit by 90 °.

(Additional remark 10) Based on the image data produced | generated from the design data of the said photomask, the direction which reciprocates the irradiation spot of the laser among the patterns of the said light shielding film, and the direction where the pattern of the said light shielding film are extended are parallel 7. The photomask inspection apparatus according to appendix 6, further comprising: an extraction unit that extracts a region to become, and a coordinate conversion unit that rotates the coordinates of the region extracted by the extraction unit by 90 °.

  As described above, the photomask inspection method and the photomask inspection apparatus according to the present invention are useful for manufacturing various solid elements such as semiconductor elements and magnetic device elements, and particularly when forming a fine pattern of a solid element. Suitable for manufacturing photomasks used in

It is a figure which shows the principal part of the photomask inspection apparatus concerning Embodiment 1 of this invention. 6 is a diagram illustrating a relationship between laser movement and photomask movement in Embodiment 1. FIG. 6 is a diagram illustrating a relationship between laser movement and photomask movement in Embodiment 1. FIG. It is a figure which shows the structure of the photomask inspection apparatus concerning Embodiment 1 of this invention. It is a figure explaining the procedure of the photomask inspection method concerning Embodiment 1 of this invention. 6 is a diagram illustrating a relationship between a laser scanning direction and a photomask pattern in Embodiment 1. FIG. 6 is a diagram illustrating a relationship between a laser scanning direction and a photomask pattern in Embodiment 1. FIG. It is a figure which shows the structure of the photomask inspection apparatus concerning Embodiment 2 of this invention. It is a figure explaining the procedure of the photomask inspection method concerning Embodiment 2 of this invention. It is a figure explaining the procedure of the area extraction process of the vertical pattern in the photomask inspection method concerning Embodiment 2 of this invention. 10 is a diagram illustrating a relationship between a laser movement and a photomask movement in Embodiment 3. FIG. It is a figure which shows the structure of the photomask inspection apparatus concerning Embodiment 3 of this invention. It is a figure explaining the procedure of the photomask inspection method concerning Embodiment 3 of this invention. It is a figure which shows the structure of the photomask inspection apparatus concerning Embodiment 4 of this invention. It is a figure explaining the procedure of the photomask inspection method concerning Embodiment 4 of this invention. It is a figure explaining the procedure of the area extraction process of the vertical pattern in the photomask inspection method concerning Embodiment 4 of this invention. It is a figure explaining evaluation experiment of CD error defect. It is a figure which shows the result of evaluation experiment of CD error defect. It is a figure which shows typically the defect with which the excess light shielding film remained. It is a figure which shows typically the defect which a part of light shielding film lacked. It is a figure which shows a CD error defect typically.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10, 40, 50, 60 Photomask inspection apparatus 11 Photomask 12 Laser 16 Light shielding film 24 Defect inspection part 25 Light source 26 Laser vibration part 28 Light receiving element 31 Stage 32 Holder 34 Holder drive part 37 Design data 41 Vertical pattern area extraction part 42 Coordinate transformation calculation unit 51 Laser control unit

Claims (5)

  In a photomask inspection method for irradiating a photomask on which a pattern is formed, moving an irradiation spot of the laser to acquire an image of the pattern, and inspecting the pattern based on the image, the edge of the pattern And a step of determining a moving direction of the irradiation spot based on the extending direction of the edge.   The photomask inspection method according to claim 1, wherein a direction in which the irradiation spot moves and the extending direction of the edge of the pattern are orthogonal to each other.   The direction in which the irradiation spot moves and the pattern after acquiring an image with respect to the entire surface of the photomask in a first state in which the direction in which the irradiation spot moves and the extending direction of the edge of the pattern are orthogonal to each other The photomask inspection method according to claim 1, wherein an image is acquired in a second state in which the extending direction of the edge is parallel to the edge.   A region in which an image is acquired in the second state is a region of the pattern in which the direction in which the irradiation spot moves in the first state is parallel to the extending direction of the edge of the pattern. The photomask inspection method according to claim 3, wherein:   In a photomask inspection apparatus that irradiates a photomask on which a pattern is formed, moves an irradiation spot of the laser, acquires an image of the pattern, and inspects the pattern based on the image, emits the laser Light source, a laser vibration part for moving the laser irradiation spot emitted from the light source, a holder for holding the photomask, a holder driving part for rotating the holder by 90 °, and the holder in a two-dimensional direction. A photomask inspection apparatus comprising: a stage that is moved to a position; and a light receiving element that receives the laser.

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