JP3958327B2 - Sample inspection apparatus and sample inspection method - Google Patents

Description

  The present invention relates to a sample inspection apparatus or a sample inspection method, for example, a pattern defect inspection apparatus and a pattern defect inspection method for inspecting a defect of a pattern of a reticle used for semiconductor manufacturing.

  In recent years, the circuit line width required for a semiconductor element has been increasingly narrowed as LSI is highly integrated and has a large capacity. These semiconductor elements use a reduction projection exposure called a stepper by using an original pattern pattern (also referred to as a mask or a reticle; hereinafter, a mask and a reticle mean the same thing) on which a circuit pattern is formed. It is manufactured by exposing and transferring a pattern onto a wafer with an apparatus to form a circuit. Therefore, a pattern drawing apparatus capable of drawing a fine circuit pattern is used for manufacturing a mask for transferring such a fine circuit pattern onto a wafer. A pattern circuit may be directly drawn on a wafer using such a pattern drawing apparatus. The electron beam drawing apparatus is also described in the literature (see, for example, Patent Document 1). Alternatively, development of a laser beam drawing apparatus for drawing using a laser beam in addition to an electron beam has been attempted and disclosed in the literature (for example, see Patent Document 2).

  However, as represented by a 1 gigabit class DRAM (Random Access Memory), a pattern constituting a large scale integrated circuit (LSI) is going to be on the order of submicron to nanometer. One of the major causes of a decrease in yield in the manufacture of LSI is a defect of a mask used when an ultrafine pattern is exposed and transferred onto a semiconductor wafer by a photolithography technique. In particular, with the miniaturization of the pattern dimensions of LSIs formed on semiconductor wafers, the dimensions that must be detected as pattern defects have become extremely small. Therefore, an apparatus for inspecting such a defect has been developed.

  On the other hand, with the development of multimedia, LCDs (Liquid Crystal Display) are increasing in size of the liquid crystal substrate to 500 mm × 600 mm or more, and TFTs (Thin Film Transistors) formed on the liquid crystal substrate. : Thin film transistors) and the like are being miniaturized. Therefore, it is required to inspect a very small pattern defect over a wide range. For this reason, it has become an urgent task to develop a sample inspection apparatus for inspecting defects of a photomask used when manufacturing such a large area LCD pattern and a large area LCD with high accuracy.

  Here, as a mask defect inspection method, “die to die inspection” for comparing the same pattern at different locations on the same mask, or “die” for comparing with CAD data (design data) used when drawing the mask pattern. to database test ". In the inspection method in such an inspection apparatus, for example, the inspection area of the mask is divided into a plurality of inspection areas (inspection stripes) in stripes (bands) having overlapping portions in the Y direction, and inspection is sequentially performed for each inspection area, Finally, defects in all inspection areas are integrated to detect defects in the entire mask.

Here, a conventional reticle inspection apparatus is disclosed in literature (for example, see Patent Literature 3). Hereinafter, a conventional reticle inspection apparatus will be described.
(1) First, in the laser scanning optical apparatus, the XY stage on which the reticle is mounted is moved to the inspection start position of the inspection stripe. The reticle placed on the XY stage is irradiated with a laser beam while moving the XY stage in the X direction.
(2) The transmitted light detection unit receives the laser beam transmitted through the reticle, performs A / D conversion, and stores the image data in the optical image input unit.
(3) The X-axis direction position coordinate of the XY stage is measured by an X-axis laser interferometer and an X-axis laser scale, and the result is transferred to the deviation detector.
(4) Then, the optical image input unit transfers the image data to the image comparison unit.
(5) The data conversion unit creates a reference image by referring to the deviation data in the X-axis direction from the deviation detection unit based on the CAD data transferred from the host system, and transfers the reference image to the image comparison unit. .
(6) The image comparison unit compares and determines the image from the optical image input unit and the image from the data conversion unit, and transfers the inspection result to the host system.

Here, in such a conventional reticle inspection apparatus, correction of only one axis in the X direction is supported, so that it is not possible to cope with reticle fluctuations that require two-dimensional correction.
Japanese Patent Laid-Open No. 2002-237445 US Pat. No. 5,386,221 Japanese Patent Laid-Open No. 11-160039

  As described above, the conventional reticle inspection apparatus cannot cope with reticle fluctuations that require two-dimensional correction because it supports correction of only one axis in the X direction.

  An object of the present invention is to provide a reticle inspection apparatus capable of overcoming the above-described problems and capable of two-dimensional correction.

A sample inspection apparatus which is one embodiment of the present invention includes:
A first laser interferometer and a first laser scale for measuring the X coordinate position on the sample to be inspected;
A second laser interferometer for measuring the Y coordinate position on the sample to be inspected, and a second laser scale ;
An optical image acquisition unit for acquiring an optical image on the inspection sample;
The plurality of predetermined positions measured by the designed XY coordinates at the plurality of predetermined positions on the sample to be inspected, the first and second laser interferometers, and the first and second laser scales . A correction unit that corrects the position of the optical image acquired by the optical image acquisition unit based on XY coordinates;
A comparison unit that compares the optical image with a predetermined reference image at a corrected position;
It is provided with.

In addition, a sample inspection method according to one embodiment of the present invention includes:
X coordinate positions at a plurality of predetermined positions on the sample to be inspected are measured using a first laser interferometer and a first laser scale, and a Y coordinate position is measured with a second laser interferometer and a second laser scale. And a measurement process for measuring using
An optical image acquisition step of acquiring an optical image on the inspection sample using an optical image acquisition unit ;
The plurality of predetermined positions measured by the designed XY coordinates at the plurality of predetermined positions on the sample to be inspected, the first and second laser interferometers, and the first and second laser scales. A correction step of correcting the position of the optical image acquired by the optical image acquisition unit based on XY coordinates;
A comparison step of comparing the optical image with a predetermined reference image at the corrected position;
It is provided with.

  According to the sample inspection apparatus which is one aspect of the present invention, since the first and second X coordinate measuring units and the first and second Y coordinate measuring units are provided, a two-dimensional position of the XY coordinates is obtained. be able to. Then, based on the designed XY coordinates, the first and second X coordinate measuring units, and the XY coordinates of the predetermined positions measured by the first and second Y coordinate measuring units, Two-dimensional correction of XY coordinates can be performed on the position of the optical image acquired by the optical image acquisition unit. Since two-dimensional correction can be performed, the degree of coincidence between the optical image of the sample to be inspected and the reference image can be improved. As a result, pseudo defects can be suppressed. Therefore, the efficiency and accuracy of inspection can be improved.

  In addition, according to the sample inspection method which is an aspect of the present invention, the XY coordinates of the design of the plurality of predetermined positions on the sample to be inspected and the XY of the plurality of predetermined positions on the sample to be inspected which are measured. The X coordinate can be corrected by acquiring an optical image on the sample to be inspected at a position measured by a measuring instrument in which the X coordinate is corrected based on the coordinate. Then, by correcting the position of the acquired optical image from the Y coordinate position when measured by any of the plurality of measuring instruments to the Y coordinate position when measured by another measuring instrument, Y Coordinates can be corrected. Therefore, since two-dimensional correction can be performed, the degree of coincidence between the optical image of the sample to be inspected and the reference image can be improved.

Embodiment 1 FIG.
In this embodiment, both a laser interferometer and a laser scale are installed as measuring instruments on both the X axis and the Y axis of the XY stage, and the laser scale output is used as a trigger, and sampling is performed at a pitch measured by the laser interferometer. A reticle inspection apparatus in which an optical image is subjected to two-dimensional correction in the X direction and the Y direction by an optical image correction unit will be described.

FIG. 1 is a conceptual diagram showing a configuration of a reticle inspection apparatus according to the first embodiment.
In FIG. 1, a reticle inspection apparatus 100 includes an optical image acquisition unit and a control system circuit as an example of a sample inspection apparatus that samples a substrate such as a mask or a wafer and inspects defects of the sample. The optical image acquisition unit includes an XY stage 102, a laser optical device 103, an objective lens 104 which is an example of a magnification optical system, a transmitted light detection unit 105 such as a photodiode array, an optical image input unit 106, a collector lens 120, and a measuring instrument. An X-axis laser interferometer 201, an X-axis laser scale 202, a Y-axis laser interferometer 211, and a Y-axis laser scale 212 are provided as examples. In the control system circuit, for example, an overall control unit 110 serving as a computer is connected to a position data input unit 107, an image comparison unit 108 as an example of a comparison unit, a reference image generation unit 112, and a magnetic disk via a bus (not shown). The apparatus 109 is connected to an optical image correction unit 140 that is an example of a correction unit. The XY stage 102 is driven by an X-axis motor, a Y-axis motor, a θ-axis motor or the like (not shown).

  In FIG. 1, a laser optical device 103 irradiates a reticle 101 placed on an XY stage 102 with a laser beam via a collector lens 120. The laser beam transmitted through the reticle 101 is imaged on the transmitted light detection unit 105 via the objective lens 104, A / D (analog / digital) converted by the transmitted light detection unit 105, and stored in the optical image input unit 106. Is done. At this time, the X-axis direction and Y-axis direction image data of the optical image and the position data stored in the position data input unit are stored in association with each other. Here, the position coordinate of the XY stage 102 in the X-axis direction is measured by the X-axis laser interferometer 201 and the X-axis laser scale 202, and the result is stored in the position data input unit 107. On the other hand, the Y-axis position coordinate of the XY stage is measured by the Y-axis laser interferometer 211 and the Y-axis laser scale 212, and the result is stored in the position data input unit 107.

  The optical image correction unit 140 corrects the image data of the optical image input unit 106 based on the position coordinates stored in the position data input unit 107 and stores the corrected image data in the image comparison unit 108. The reference image generation unit 112 refers to the position coordinates of the position data input unit 107 on the basis of the drawing data transferred from the host system or the designed drawing data stored in the magnetic disk device 109. Created and transferred to the image comparison unit 108. The image comparison unit 108 compares and determines the image data from the optical image correction unit 140 and the reference image data from the reference image generation unit 112 with reference to the position coordinates of the position data input unit 107, and determines the inspection result as an upper system. Forward to. The entire control unit 110 controls the entire system.

FIG. 2 is a block diagram showing a main part of the configuration along the flow in which an optical image is acquired.
2, the optical image correction unit 140 includes a conversion coefficient calculation unit 142, an inclination amount calculation unit 144, an X coordinate correction unit 146, and a Y coordinate correction unit 148. The image comparison unit 108 includes a cutout unit 215, an alignment unit 216, and a comparison determination processing unit 218. The optical image acquired by the optical image acquisition unit 150 is corrected by the optical image correction unit 140 as a result of various calculations, and the image comparison unit 108 performs comparison determination processing.

FIG. 3 is a flowchart showing a main part of the reticle inspection method according to the first embodiment.
As shown in FIG. 3, the reticle inspection method according to the first embodiment performs a series of steps from S302 to S330.

FIG. 4 is a diagram illustrating an example of a reticle.
As shown in FIG. 4, on the reticle 101, four alignment marks 401, 402, 403, 404 are formed as alignment points so as to surround the pattern. Here, a case where there are four alignment points will be described, but four points are not necessarily required. Moreover, you may use a part of pattern as an alignment point, without using an alignment mark.

  In S (step) 302, as the alignment point moving step, first, the XY stage 102 is moved so that the alignment mark 401 serving as the first alignment point is irradiated with the laser beam.

  In S304, as a coordinate measurement step, the laser scale coordinate value and the laser interferometer coordinate value at the position of the first alignment point are read. In other words, the X-axis direction position coordinate of the XY stage 102 at the position of the first alignment point is measured by the X-axis laser interferometer 201 and the X-axis laser scale 202, and the result is stored in the position data input unit 107. . On the other hand, the Y-axis direction position coordinate of the XY stage 102 is measured by the Y-axis laser interferometer 211 and the Y-axis laser scale 212, and the result is stored in the position data input unit 107.

In S306, in the number determination step, it is determined whether or not the alignment point number n is n _max . In other words, it is determined whether laser scale coordinate values and laser interferometer coordinate values have been read for all alignment points. Here, since there are four alignment points, S302 and S304 are repeated for the remaining three points. That is, it moves to the alignment mark 402 which becomes the second alignment point, and reads the laser scale coordinate value and the laser interferometer coordinate value at the position of the second alignment point. Similarly, it moves to the alignment mark 403 to be the third alignment point, and reads the laser scale coordinate value and the laser interferometer coordinate value at the position of the third alignment point. And similarly, it moves to the alignment mark 404 used as a 4th alignment point, and the laser scale coordinate value and laser interferometer coordinate value in the position of a 4th alignment point are read.

FIG. 5 is a diagram showing a state where laser scale coordinate values and laser interferometer coordinate values are plotted on the design coordinate system for four alignment points.
In FIG. 5, the laser scale coordinate values (x _s1 , y _s1 ) and the laser interferometer coordinate values (x _k1 , y _k1 ) are used as the coordinates of the first alignment point, and the laser scale coordinate values are used as the coordinates of the second alignment point. (X _s2 , y _s2 ) and the laser interferometer coordinate value (x _k2 , y _k2 ) are the coordinates of the third alignment point, the laser scale coordinate value (x _s3 , y _s3 ) and the laser interferometer coordinate value (x _k3). , Y _k3 ) are laser scale coordinate values (x _s4 , y _s4 ) and laser interferometer coordinate values (x _k4 , y _k4 ) as the coordinates of the fourth alignment point.

  As shown in FIG. 5, the four alignment point positions measured by the laser scale and the four alignment point positions measured by the laser interferometer are deviated from the design values. Here, the design value of the first alignment point position is described as the origin. In particular, the amount of deviation in the laser interferometer is large. In FIG. 1, it seems that the laser scale is arranged immediately below the laser interferometer, but the lower and upper portions of the XY stage 102 have different shake amounts when the XY stage 102 moves. Usually, in the XY stage 102 having the drive mechanism on the lower side, the shake amount increases as the position becomes higher. Therefore, the position of the laser scale disposed on the lower side is different from the position on the upper part where the reticle 101 is actually placed. Therefore, the measurement value obtained by the laser interferometer that measures the position close to the reticle 101 deviates from the design value. Further, the laser interferometer has a characteristic that an error increases when a use environment (temperature, humidity, atmospheric pressure) fluctuates. This is because the refractive index of air changes due to environmental changes, and the wavelength of the laser light emitted from the laser interferometer changes. Therefore, a deviation corresponding to such an error also occurs. On the other hand, it is difficult to completely match the design value even with a laser scale that is resistant to environmental fluctuations.

  In S308, as the conversion coefficient calculation step, the conversion coefficient calculation unit 142 uses the set of four laser scale coordinate values that have already been collected, and calculates conversion coefficients between the design coordinates and the laser scale coordinate values that become the reticle coordinate system. Ask.

FIG. 6 is a diagram illustrating a conversion function to laser scale coordinate values.
FIG. 6 shows a conversion function formula for converting predetermined design points (x _R , y _R ) into coordinate values (x _s , y _s ) when measured on a laser scale. The conversion coefficient calculation unit 142 converts the coefficients a _s0 , b _s0 , a _s1 , b _s1 , c _s1 , a _s2 , b _s2 , and c _s2 of the conversion function equation into the laser scale coordinate values (x _s1 , y _s1 ), the laser scale coordinate values (x _s2 , y _s2 ) of the second alignment point, the laser scale coordinate values (x _s3 , y _s3 ) of the third alignment point, and the coordinates of the fourth alignment point. Using the coordinate values (x _s4 , y _s4 ), the calculation is performed. By obtaining such coefficients, it is possible to convert predetermined design points (x _R , y _R ) into coordinate values (x _s , y _s ) when measured on a laser scale.

  In S310, as a conversion coefficient calculation step, the conversion coefficient calculation unit 142 converts the design coordinates and the laser interferometer coordinate values, which become the reticle coordinate system, using a set of four laser interferometer coordinate values that have already been collected. Find the coefficient.

FIG. 7 is a diagram illustrating a conversion function to laser scale coordinate values.
FIG. 7 shows a conversion function formula for converting predetermined design points (x _R , y _R ) into coordinate values (x _k , y _k ) when measured by a laser interferometer. The conversion coefficient calculation unit 142 converts the coefficients a _k0 , b _k0 , a _k1 , b _k1 , c _k1 , a _k2 , b _k2 , c _k2 of the conversion function equation into the laser interferometer coordinate values (x _k1) of the first alignment point. , Y _k1 ), the laser interferometer coordinate values (x _k2 , y _k2 ) of the second alignment point, the laser interferometer coordinate values (x _k3 , y _k3 ) of the third alignment point, and the laser of the fourth alignment point. Calculation is performed using interferometer coordinate values (x _k4 , y _k4 ). By obtaining such coefficients, it is possible to convert predetermined design points (x _R , y _R ) into coordinate values (x _k , y _k ) when measured by a laser interferometer.

  In S312, as the image collection start position moving step, the XY stage 102 is controlled by the laser scale coordinate system and moved to the image collection start position of the nth inspection stripe.

FIG. 8 is a diagram for explaining an optical image acquisition procedure.
As shown in FIG. 8, the inspection area is virtually divided into a plurality of strip-shaped inspection stripes having a scan width W in the Y direction, and each of the divided inspection stripes is continuously scanned. Thus, the operation of the XY stage 102 is controlled, and an optical image is acquired while moving in the X direction from the image acquisition start position toward the image acquisition end position. Therefore, here, the XY stage 102 is moved to the image acquisition start position of the nth inspection stripe.

  In S <b> 314, as the tilt amount calculation step, the tilt amount calculation unit 144 calculates the tilt amount of the laser scale coordinate value and the laser interferometer with respect to a virtual line connecting the image acquisition start position and the image acquisition end position of the nth inspection stripe. The difference from the tilt amount is calculated.

FIG. 9 is a diagram for explaining the tilt amount calculation step.
As described above, since the conversion function equation for converting the predetermined design point (x _R , y _R ) to the coordinate value (x _k , y _k ) when measured by the laser interferometer is obtained, The design coordinate values of the image acquisition start position and the image acquisition end position of the nth inspection stripe can be converted into coordinate values when measured by a laser interferometer. As a result, it is possible to obtain coordinate values measured by the laser interferometer at the image acquisition start position and the image acquisition end position of the nth inspection stripe. Similarly, since a conversion function expression for converting predetermined design points (x _R , y _R ) into coordinate values (x _s , y _s ) when measured on a laser scale is obtained, the nth inspection The design coordinate values of the image acquisition start position and the image acquisition end position of the stripe can be converted into coordinate values when measured on a laser scale. As a result, it is possible to obtain coordinate values when measured on the laser scale of the image acquisition start position and the image acquisition end position of the nth inspection stripe.

  Here, as shown in FIG. 9, the tilt amount calculation unit 144 is a virtual line that connects the image acquisition start position and the image acquisition end position of the nth inspection stripe on the design coordinates when measured by the laser interferometer. The inclination θk is obtained. Similarly, the inclination amount calculation unit 144 obtains an inclination θs of an imaginary line connecting the image acquisition start position and the image acquisition end position of the nth inspection stripe on the design coordinates when measured with a laser scale. Then, the inclination amount calculation unit 144 calculates an inclination amount θ that is a difference value between the inclination θk and the inclination θs.

  Here, since the inclination amount θ may be different for each inspection stripe, it is desirable to calculate the inclination amount θ for each inspection stripe.

In S316, as a pitch calculation step, the X coordinate correction unit 146 corrects the pitch input by the transmitted light detection unit 105.
The transmitted light detection unit 105 continuously inputs images having a scan width W as shown in FIG. Then, after acquiring the image in the first inspection stripe, the image in the scan width W is continuously input in the same manner while moving the image in the second inspection stripe in the opposite direction. When acquiring the image in the third inspection stripe, the image is acquired while moving in the direction opposite to the direction in which the image in the second inspection stripe is acquired, that is, in the direction in which the image in the first inspection stripe is acquired. . In this manner, the useless movement time can be shortened by meandering and acquiring images.

FIG. 10 is a diagram for explaining the image input pitch.
Each time the X-axis laser interferometer 201 detects a certain pitch of movement while feeding the XY stage 102 at a constant speed in the X direction, the transmitted light detection unit 105 inputs an image having a scan width W. Such a pitch is 1 pitch when a value obtained by resolving the wavelength λ of the laser light emitted from the X-axis laser interferometer 201 with a predetermined resolution is 1 pulse, and when the required number of pulses is detected in accordance with the set pixel size. Yes. For example, when a laser beam having a wavelength of 632.5 nm is irradiated and the resolution is 1/1024, when the pitch is 100 pulses and 1 pitch, the transmitted light detection unit 105 inputs an image every time the pitch is moved by 62 nm. Will do.

However, if the X coordinate measured by the X-axis laser interferometer 201 deviates from the design value at the image acquisition start position and the image acquisition end position described above, the input image also expands and contracts in the X-axis direction. It will be. Therefore, the X coordinate correction unit 146 determines the distance L _k between the image acquisition start position and the image acquisition end position measured by the X-axis laser interferometer 201 and the design distance between the image acquisition start position and the image acquisition end position. The number of detected pulses per pitch that is equivalent to the deviation from _LR is corrected. For example, the number of detected pulses per pitch is corrected from 100 pulses to 99 pulses. With this correction, the X-axis direction can be corrected in an image acquisition process described later.

  Here, since the deviation may differ for each inspection stripe, it is desirable to calculate the deviation for each inspection stripe and correct the number of detected pulses per pitch.

  In S318, as an image acquisition step, the optical image acquisition unit 150 acquires an optical image from the image acquisition start position of the nth inspection stripe toward the image acquisition end position. That is, the transmitted light detection unit 105 continuously inputs images with a scan width W as shown in FIG. 8 for the nth inspection stripe.

In S320, as the image collection end position moving step, the XY stage 102 is moved to the image collection end position in the laser scale coordinate system.
While the XY stage 102 is moving, using the X-axis laser interferometer 201, the Y-axis laser interferometer 211, the X-axis laser scale 202, and the Y-axis laser scale 212, the coordinate values of the laser scale and the laser interferometer Coordinate values are collected at regular intervals, and image data at that time is transferred from the transmitted light detection unit 105 to the optical image input unit 106.

  In S322, when image data is transferred to the optical image input unit 106 as an image correction process, the Y coordinate correction unit 148 reads position coordinate data corresponding to the image data from the position data input unit 107, and the image data A value obtained by multiplying the deviation from the image acquisition start position of the X coordinate by the tilt amount θ transferred in advance from the Y coordinate, and shifting the image data by the difference between the value and the Y coordinate of the image data Correct the image data.

FIG. 11 is a diagram for explaining a Y-coordinate correction method.
When the difference between the X coordinate of the image acquisition start position of the n test strip and the X-coordinate of the image data (deviation) and [Delta] x _k, the correction amount in the Y-axis direction is the [Delta] x k _· tan .theta. Then, the Y coordinate correction unit 148 corrects the Y coordinate by adding or subtracting Δx _k · tan θ for y _kn among the coordinates (x _kn , y _kn ) of the image data.

FIG. 12 is a diagram illustrating the appearance of the image before and after correction.
As shown in FIG. 12A, when the two-dimensional image correction is not performed, the image is distorted. By performing the two-dimensional correction in the present embodiment, image distortion can be eliminated as shown in FIG.

  In S324, as an image transfer step, the optical image correction unit 140 transfers the corrected image to the image comparison unit 108.

  In S326, as a reference image transfer step, the reference image generation unit 112 reads design data from the magnetic disk device 109, creates a reference image corresponding to the designated pixel pitch from the drawing data, and sends it to the image comparison unit 108. Forward.

  In S328, as the comparison determination step, the cutout unit 215 cuts out the corrected image data and the reference image as an image of a predetermined area (area). Then, the alignment unit 216 performs alignment (area alignment) between the image data and the reference image, and the comparison determination processing unit 218 compares and inspects the area-aligned image data and the reference image, for example, If the difference is greater than or equal to the set threshold, it is determined as a defect. Then, the determination result is notified to the host system.

  In S330, as the determination process, the above process is completed if the required number of times is processed, and when the required number has not yet been reached, the XY stage 102 is repeated from the position where it is moved to the image collection start position in the laser scale coordinate system.

  As described above, according to the present embodiment, the optical image correction unit 140 shifts and corrects image data while changing the tilt amount θ each time the XY stage 102 moves to the next inspection stripe. Accordingly, two-dimensional correction in the X-axis direction and the Y-axis direction can be performed.

  In the above description, the comparison target in the image comparison unit 108 may be image data of another position coordinate in the optical image correction unit 140 instead of the image data from the reference image generation unit 112. In other words, it may be used for die to die inspection. Alternatively, both the image data from the reference image generation unit 112 and the image data at another position coordinate in the optical image correction unit 140 may be used. That is, it is possible to use both the die to database inspection and the die to die inspection. Further, although cases have been described with the above embodiment where transmitted light that has passed through reticle 101 is detected, reflected light that is reflected from reticle 101 may be detected. In other words, the transmitted light detection unit may be replaced with a reflected light detection unit to configure a reflection optical system. Alternatively, both the case where the transmitted light is detected and the case where the reflected light is detected may be used. That is, it is possible to use both the transmitted light detection unit and the reflected light detection unit.

Further, the relationship between the optical image and the reference image is also suitable in the following cases.
(1) The optical image acquisition unit 150 acquires an optical image on the reticle 101 using transmitted light that passes through the sample to be inspected, and an image created based on the design data of the reticle 101 is used as a reference image. It may be used.
Alternatively, (2) the optical image acquisition unit 150 acquires an optical image on the reticle 101 using reflected light that reflects the reticle 101, and the reference image is created based on the design data of the reticle 101. An image may be used.
Alternatively, (3) the optical image acquisition unit 150 acquires an optical image on the reticle 101 using transmitted light that passes through the reticle 101, and the reference image is based on another optical image of the reticle 101. The created image may be used.
Alternatively, (4) the optical image acquisition unit 150 acquires an optical image on the reticle 101 using the reflected light that reflects the reticle 101, and the reference image is an image created based on another optical image of the reticle 101. May be used.

  In the above description, what is described as “˜circuit” or “˜process” can be configured by a computer-operable program. Or you may make it implement by not only the program used as software but the combination of hardware and software. Alternatively, a combination with firmware may be used. When configured by a program, the program is recorded on a recording medium such as a magnetic disk device, a magnetic tape device, an FD, or a ROM (Read Only Memory).

  The embodiments have been described above with reference to specific examples. However, the present invention is not limited to these specific examples. In the embodiment, the optical image is corrected to match the reference image, but conversely, the reference image may be corrected to match the optical image.

  In addition, although descriptions are omitted for parts and the like that are not directly required for the description of the present invention, such as a device configuration and a control method, a required device configuration and a control method can be appropriately selected and used.

  In addition, all sample inspection apparatuses and sample inspection methods that include the elements of the present invention and that can be appropriately modified by those skilled in the art are included in the scope of the present invention.

1 is a conceptual diagram showing a configuration of a reticle inspection apparatus in a first embodiment. It is a block diagram which shows the principal part of the structure along the flow from which an optical image is acquired. FIG. 3 is a flowchart showing a main part of a reticle inspection method in the first embodiment. It is a figure which shows an example of a reticle. It is a figure which shows the state which plotted the laser scale coordinate value and the laser interferometer coordinate value on the design coordinate system about the four alignment points. It is a figure which shows the conversion function to a laser scale coordinate value. It is a figure which shows the conversion function to a laser scale coordinate value. It is a figure for demonstrating the acquisition procedure of an optical image. It is a figure for demonstrating the inclination amount calculating process. It is a figure for demonstrating an image input pitch. It is a figure for demonstrating the method of Y coordinate correction | amendment. It is a figure which shows the mode of the image before and behind correction | amendment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Reticle inspection apparatus 101 Reticle 102 XY stage 103 Laser optical apparatus 104 Objective lens 105 Transmitted light detection part 106 Optical image input part 107 Position data input part 108 Image comparison part 109 Magnetic disk apparatus 110 Overall control part 112 Reference image generation part 140 Optical Image correction unit 201 X-axis laser interferometer 202 X-axis laser scale 211 Y-axis laser interferometer 212 Y-axis laser scale 215 Cutting unit 216 Positioning unit 218 Comparison determination processing unit

Claims (7)

A first laser interferometer and a first laser scale for measuring the X coordinate position on the sample to be inspected;
A second laser interferometer for measuring the Y coordinate position on the sample to be inspected, and a second laser scale ;
An optical image acquisition unit for acquiring an optical image on the inspection sample;
The plurality of predetermined positions measured by the designed XY coordinates at the plurality of predetermined positions on the sample to be inspected, the first and second laser interferometers, and the first and second laser scales . A correction unit that corrects the position of the optical image acquired by the optical image acquisition unit based on XY coordinates;
A comparison unit that compares the optical image with a predetermined reference image at a corrected position;
A sample inspection apparatus comprising: The correction unit is
Based on the XY coordinates of the plurality of predetermined positions in the design, and the XY coordinates of the plurality of predetermined positions measured by the first and second laser interferometers and the first and second laser scales. An imaginary line connecting a measurement start position and a measurement end position on the sample to be inspected when measured by the first laser interferometer and the second laser interferometer, and the first laser scale. And a first calculation unit that calculates an inclination of a virtual line connecting a measurement start position and a measurement end position on the sample to be inspected when measured by the second laser scale ;
And the deviation between the X coordinate of the first of said optical image said measured by a laser interferometer and the X coordinate of the first measurement starting position on the inspected specimen as measured by a laser interferometer, the tilt A second arithmetic unit for adjusting the Y coordinate value in the optical image when the product value is measured by the second laser interferometer ,
The sample inspection apparatus according to claim 1, further comprising: The optical image acquisition unit acquires an optical image on the sample to be inspected using transmitted light that passes through the sample to be inspected,
The sample inspection apparatus according to claim 1, wherein an image created based on design data of the sample to be inspected is used as the predetermined reference image. The optical image acquisition unit acquires an optical image on the sample to be inspected using reflected light that reflects the sample to be inspected,
The sample inspection apparatus according to claim 1, wherein an image created based on design data of the sample to be inspected is used as the predetermined reference image. The optical image acquisition unit acquires an optical image on the sample to be inspected using transmitted light that passes through the sample to be inspected,
The sample inspection apparatus according to claim 1, wherein an image created based on another optical image of the sample to be inspected is used as the predetermined reference image. The optical image acquisition unit acquires an optical image on the sample to be inspected using reflected light that reflects the sample to be inspected,
The sample inspection apparatus according to claim 1, wherein an image created based on another optical image of the sample to be inspected is used as the predetermined reference image. X coordinate positions at a plurality of predetermined positions on the sample to be inspected are measured using a first laser interferometer and a first laser scale, and a Y coordinate position is measured with a second laser interferometer and a second laser scale. And a measurement process for measuring using
An optical image acquisition step of acquiring an optical image on the inspection sample using an optical image acquisition unit ;
The plurality of predetermined positions measured by the designed XY coordinates at the plurality of predetermined positions on the sample to be inspected, the first and second laser interferometers, and the first and second laser scales. A correction step of correcting the position of the optical image acquired by the optical image acquisition unit based on XY coordinates;
A comparison step of comparing the optical image with a predetermined reference image at the corrected position;
A sample inspection method comprising:

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