JP4895356B2 - Line width measuring device - Google Patents

Description

  The present invention relates to an apparatus for measuring or inspecting line width or dimensions, and more particularly to an apparatus for measuring or inspecting a multi-imaging head system.

  The line width measuring device or the dimension measuring device is a device that measures the pattern width and pattern interval of a TFT (Thin Film Transistor) on a substrate (for example, an LCD (Liquid Crystal Display) substrate) or a semiconductor mask. For example, the line width measuring device or the dimension measuring device enlarges a pattern image obtained by irradiating a film pattern formed on a transparent glass substrate (sample) with a microscope, and displays the image on a CCD (Charge Coupled Device). A pattern image obtained by imaging with a camera is subjected to image processing to measure dimensions and shape. Hereinafter, the line width measuring device or the dimension measuring device or the line width inspecting device or the dimension inspecting device will be collectively referred to as a line width measuring device.

  In recent years, the demand for LCD substrates has increased. Along with this, in the manufacturing process of LCD substrates, production efficiency is improved by increasing the display part (display size) and increasing the number of products that can be acquired on one substrate (multiple picks). . In the following, an LCD substrate is a unit of objects to be measured placed on a line width measuring device during the manufacturing process, so that multiple products (for example, LCD panels) are allocated on it. It means the substrate. Therefore, there are a plurality of film patterns to be inspected having the same shape in such an object to be measured.

As described above, when an object to be measured such as an LCD substrate becomes larger, an exposure error (positional deviation) of a film pattern formed on the object to be measured tends to generally increase accordingly. The dimensions (unit: mm) of the LCD substrate are, for example, 1850 × 1500 or 2250 × 1950 in the horizontal dimension X × vertical dimension Y, and the thickness is about 0.5 to 0.7.
As a result of the large positional shift of the film pattern formed on the object to be measured, the line width measuring device can measure the object to be measured, such as an LCD substrate, even if the XY stage is moved to image the predetermined measurement position. Since the pattern position on the upper side is shifted, there may occur a situation in which a part to be measured that is necessary for image processing protrudes from the captured video (for example, see Patent Document 1).

  When the sample stage is moved in the X or Y direction in order to reduce the increase in exposure error (positional deviation) described above or in order to image a predetermined measurement position, the required image processing image is included in the captured image. It is necessary to minimize the situation where a part of the measurement part protrudes. For this purpose, conventionally, the object to be measured is carried on the sample table by a transfer robot, etc., and a positioning stopper such as a fixing pin is provided on the sample table in each of the X and Y directions. After placement, the object to be measured was pressed against the stopper in the X and Y directions to improve positioning accuracy. Thereafter, for example, the object to be measured is adsorbed by an adsorbing mechanism, and the object to be measured is fixed to the sample stage.

  Furthermore, in the line width measuring device that is intended to measure a fine dimension with an enlarged image, when measuring with a multi-imaging head provided with a plurality of imaging heads, the position of the object to be measured is similar to the above. A positioning mechanism for reducing the deviation is provided, and the object to be measured is positioned at the time of loading by a transport robot or the like so as not to impair the accuracy and sequence of measurement.

  The mounting position of the object to be measured is forcibly moved by the clamp mechanism (pressing mechanism using an air cylinder or the like), and the two imaging heads enter the imaging field of view, and the measurement conditions are met. In the control so as to be within (for example, the clamp reproducibility range is within 30 μm), the positioning accuracy of the object to be measured in the line width measuring device is required to be, for example, about 30 μm.

  However, as the object to be measured becomes larger, it becomes difficult to move the object itself due to its mass, static electricity, etc., compulsory positioning operation becomes difficult, and many positioning operation failures occur. became. In order to reduce such a positioning operation failure, a positioning mechanism and an operation sequence having a complicated sequence have been required as an apparatus (for example, see Patent Document 2).

JP 2004-184411 A JP 2004-186681 A

As described above, in the prior art, when the object to be measured is carried into the sample stage, the object to be measured, which is once fixed after being carried into the sample stage, is weakened and then moved and positioned (positional deviation correction). There was a need. For this reason, when the object to be measured becomes large, it becomes difficult to move the object to be measured due to the influence of its mass, static electricity, etc., and a positioning operation failure occurs at a certain rate. In order to reduce such a positioning operation failure, a positioning mechanism having a complicated sequence and an operation sequence are required.
An object of the present invention is to solve the above-described problems and to realize a line width measuring apparatus that does not require a positioning operation when a measurement object is carried into a sample stage. That is, an object of the present invention is to reduce a positioning operation failure caused by an increase in the size of a sample. A camera image alignment method (an object to be measured from a camera image without physically positioning a substrate). And a method for correcting the observation positioning).
Furthermore, an object of the present invention is to provide a plurality of imaging head units in order to realize the above-described camera alignment method, to shorten measurement time and tact time, and to omit complicated sequence operations. It is to provide an image alignment method.

Moreover, in the line width measuring apparatus, shortening the tact time is an indispensable function. In order to shorten the tact time, conventionally, the movement speed of the stage has been increased and the image processing speed has been improved.
Conventional line width measuring device with only one imaging head (in this document, line width measurement with one imaging unit compared to a multi-imaging head type line width measuring device with multiple imaging heads) In this case, the corrective movement to center the predetermined measurement position of the object to be measured on the observation field (in the captured image) is translated in the X-axis direction or in the Y-axis direction. It was done by moving in at least one direction. However, in the case of a multi-imaging head type line width measuring device, with the conventional correction based on XY movement using only the X-axis direction and Y-axis direction, the movement direction and movement correction required for positional deviation correction for each head. Since the amounts are different (the moving direction between the heads and the amount of positional deviation do not match), it is difficult to correct the positional deviation.
Another object of the present invention is to provide a line width measuring apparatus capable of solving the above-described problems and capable of correcting misalignment for each imaging head unit in a multi-imaging head type line width measuring apparatus. .

In order to achieve the above object, the line width measuring apparatus of the present invention is an alignment method based on a captured image, that is, a measured object from a captured camera image without physically positioning the measured object such as a substrate. The mounting position of the object (sample) is measured, and the observation positioning is corrected. Therefore, the present invention includes a fine movement axis mechanism and a correction control means for correcting the position of the head portion of the imaging apparatus.
In other words, the present invention has means for individually correcting the image capture positions of the plurality of imaging head units.
Therefore, when the object to be measured is loaded onto the line width measuring device by the loading robot, the object to be measured is fixed to the sample stage of the line width measuring device by only positioning by the loading robot, and the sample does not have to be moved. .

Preferably, the line width measuring apparatus according to the present invention includes a plurality of imaging head units and an image processing unit, and the image processing unit performs image processing on an image acquired by each imaging head unit, thereby obtaining a desired object to be measured. In the line width measuring apparatus that measures or inspects the position, the image processing unit includes position correcting means that individually corrects the positions of the plurality of imaging head units, and the image processing unit uses the plurality of imaging heads from the images acquired by the plurality of imaging head units. The position correction unit is configured to individually and independently correct the positions of the plurality of imaging head units based on the detected positions.
Preferably, the line width measuring apparatus according to the present invention includes means for enlarging and photographing a part of the sample, a plurality of imaging head units that can be individually moved on the same axis, and a position for changing the position at which the sample is imaged. It has a correction means, a means for performing image processing on the captured image, and a control means for operating the position correction means, and corrects the positional deviation of the sample.

That is, the line width measuring apparatus of the present invention is the above-described camera image alignment method, that is, a method of measuring the mounting position of the sample from the camera image without physically positioning the substrate and correcting the observation positioning. Therefore, a fine movement axis mechanism is provided for each imaging head unit, and a correction control function for correcting them independently is provided.
Further preferably, the line width measuring apparatus according to the present invention is based on the operating range of the fine movement shaft mechanism after correcting the displacement of the measurement object mounting position using the fine movement shaft mechanisms of each of the plurality of imaging head units. In addition, it has a function to automatically adjust the range of measurement points that can be measured simultaneously.
Preferably, the multi-imaging head type line width measuring device of the present invention is an imaging head unit that can be individually moved on the same axis, and each imaging head unit can be moved in an orthogonal direction. A fine movement shaft mechanism is provided.

According to the present invention, since the positioning operation when the object to be measured is carried into the sample stage is not performed, the clamping mechanism (air cylinder or the like) that is the positioning operation when the object to be measured is carried into the sample stage is performed. It is not necessary to use a method of forcibly moving the mounting position of the sample mechanically using the pressing mechanism. Therefore, it is possible to eliminate the disadvantage that the sample cannot be actually moved due to the increase in the size of the measurement object or the influence of static electricity or the like.
Further, according to the present invention, the measurement points that can be measured simultaneously according to the operating range of the fine movement shaft mechanism after correcting the inclination of the measurement object mounting position using the fine movement axis mechanisms of each of the plurality of imaging head units. Therefore, the tact shortening effect obtained by the multi-imaging head can be further increased.
Further, according to the present invention, since it is a multi-imaging head system that can be individually moved on the same axis, the object to be measured is provided with a moving function in a direction perpendicular to each imaging head unit in the fine movement axis mechanism. Therefore, it is possible to simplify the movement process for placing each desired measurement location in the center of the observation field (correcting the positional deviation), and to shorten the measurement tact. In other words, if the movement of the conventional axis corresponds to the corrected movement distance for placing the measurement target obtained after image processing at the center of the observation field, simultaneous measurement may not be possible because the movement direction differs between the imaging head units. On the other hand, according to the present invention, the simultaneous measurement is always possible by having the fine movement shaft mechanism.

The present invention can magnify a part of a sample (object to be measured), includes an imaging unit including a plurality of imaging head units that can be individually moved on the same axis, and determines the position of the sample to be imaged. Line width measuring device with manipulator (operating means) for changing, has a function to perform image processing on the captured image, and further has a function to operate the manipulator by a computer program, combining these functions In a device that can automatically measure the line width, size, shape, etc. from the image of the sample, the movement fine movement in the direction perpendicular to the moving axis of the imaging head unit is used to correct the sample mounting position deviation. An apparatus having a mechanism and a function for controlling the mechanism in an imaging unit.
In addition, it has a function (alignment correction process) that measures the sample mounting displacement and corrects the position, and moves the position of the other imaging head unit relative to one imaging head unit to correct the image capture position. This is a multi-imaging head type line width measuring apparatus capable of

  Furthermore, in the multi-imaging head type line width measuring apparatus of the present invention, in order to correct the mounting displacement among the information of the measurement position registered in advance and the movable range of the fine movement mechanism for correcting the mounting displacement of the sample. It is possible to reduce the number of movements in the axial direction perpendicular to the axis on which the imaging head unit is located and reduce the tact time by comparing the status of the movable range used for the measurement and determining the measurement positions that can be measured simultaneously. This is a multi-imaging head type line width measuring apparatus.

  Furthermore, in the multi-imaging head type line width measuring apparatus of the present invention, the multi-imaging head type line width in which the fine movement moving mechanism provided in the imaging head unit can correct the observation position between the imaging head units. It is a measuring device.

  Furthermore, in the multi-imaging head type line width measuring device of the present invention, the fine movement moving mechanism provided in the imaging head unit aims to place the measurement object obtained by the image processing at the time of measurement in the center of the observation visual field. This is a multi-imaging head type line width measuring apparatus capable of performing correction movement.

  An embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a diagram for explaining the configuration of a two-head LCD (Liquid Crystal Display) line width measuring apparatus using the present invention. FIG. 1 (a) is a plan view of the apparatus as viewed from above, FIG. 1 (b) is a plan view of FIG. 1 (a) as viewed from the direction of arrow A, and FIG. It is the figure which looked at the top view of a) from the direction of arrow B.

With reference to FIG. 1, the configuration and operation direction of the moving shaft of the two-head LCD line width measuring device will be described. 101 is a pedestal, 103 is an object to be measured, and 102 is a sample table on which the object to be measured 103 is mounted. The sample stage 102 is fixed on the pedestal 101, and the object 103 to be measured is carried in or out on the sample stage 102 by a transport unit (not shown). The object to be measured 103 carried in from the transport unit is fixed to the sample stage 102 by a method such as vacuum suction. For example, the object 103 to be measured is adsorbed by an adsorption mechanism (not shown) of a two-head LCD line width device and fixed to the sample stage 102. The object to be measured 103 is, for example, a plate-like substrate such as a substrate, and the line width measuring device of the present invention measures or inspects the line width or the like of a film pattern formed or applied on the plate-like substrate. The plate-like substrate is, for example, a glass substrate on which a TFT (Thin Film Transistor) of an LCD (Liquid Crystal Display) substrate and a semiconductor mask are formed.
The two-head LCD linewidth measuring device is an LCD linewidth measuring device with two imaging heads. The N-head LCD linewidth measuring device is an LCD linewidth measuring device with N imaging heads. (N is a natural number greater than or equal to 2).

  1 is a beam on the Y axis, 2 is an X1 axis guide, and 3 is an X2 axis guide. The Y-axis beam 1 moves on the X1 axis guide 2 and along the X2 axis guide 3 parallel to the X axis (in FIG. 1 (a), left and right in the drawing). The rail part of the Y-axis beam 1 (hereinafter referred to as the Y-axis rail) is orthogonal to the X-axis. Note that the height of the X1 axis guide 2 and the X2 axis guide 3 may be lowered, and the Y axis beam 1 may have a gantry structure.

  4 is the Y1 axis guide and 5 is the Y2 axis guide. Y1 axis guide 4 and Y2 axis guide 5 move independently along the Y axis rail. At this time, the Y1 axis guide and the Y2 axis guide move in a direction perpendicular to the X axis (Y axis (up and down in FIG. 1A)).

  6 is the Z1 axis guide, and 7 is the Z2 axis guide. Z1 axis guide 6 is mounted on Y1 axis guide 4 and Z2 axis guide 7 is mounted on Y2 axis guide 5. The Z1 axis guide 6 moves along the Y1 axis guide 4 in the Z axis direction (up and down on the page in FIG. 1 (b)). Similarly, the Z2 axis guide 7 changes to the Y2 axis guide 5 Along the Z axis.

8 is a △ X1 axis guide, 9 is a △ X2 axis guide, and 10 and 11 are imaging heads. △ X1 axis guide 8 is mounted on Z1 axis guide 6, and △ X2 axis 9 guide is mounted on Z2 axis guide 7.
The imaging head unit 10 is mounted on a ΔX1-axis guide 8 and the imaging head unit 11 is mounted on a ΔX2-axis guide 9.
The imaging head unit 10 moves in the X axis direction along the ΔX1 axis guide 8, and similarly, the imaging head unit 11 moves in the X axis direction along the ΔX2 axis guide 9.

Further, in the embodiment of FIG. 1, a transmission illumination shaft mechanism that operates in pairs with the imaging head units 10 and 11 is provided. That is, 12 is the Py1 axis of the imaging head unit 10, 13 is the Py2 axis of the imaging head unit 11, 14 is the ΔPx1 axis of the imaging head unit 10, and 15 is the ΔPx2 axis of the imaging head unit 11.
The Py1 axis 12 and the Py2 axis 13 are mounted on the transmitted illumination guide 104 suspended from the beam 1 of the Y axis, and operate along the transmitted illumination guide 104 in the Z-axis direction.

Further, a ΔPx1 axis 14 is provided on the Py1 axis 12, and a ΔPx2 axis 15 is provided on the Py2 axis 13. The △ Px1 axis 14 is equipped with a transmitted illumination 16, and the △ Px2 axis 15 is equipped with a transmitted illumination 17.
The transmitted illumination 16 moves along the ΔPx1 axis 14 in the X-axis direction. Similarly, the transmitted illumination 17 moves along the ΔPx2 axis 15 in the X-axis direction.

The movement of the transmitted illumination 16 along the ΔPx1 axis 14 and the movement of the imaging head unit 10 along the ΔX1 axis 8 are linked, for example, the central axis of the transmitted illumination 16 and the imaging head. The incident optical axis of the part 10 is the same optical axis 111.
Similarly, the movement of the transmitted illumination 17 along the ΔPx2 axis 15 and the movement of the imaging head unit 11 along the ΔX2 axis 9 are interlocked. The incident optical axis of the imaging head unit 11 is the same optical axis 112.

  In FIG. 1 (b), a part of the beam 1, the Py1 axis 12, the Py2 axis 13, the ΔPx1 axis 14, the ΔPx2 axis 15 and the transmitted illuminations 16 and 17 attached to the beam 1, 102 is a view that is easy to see by mixing the part that can be seen from the direction of arrow B with the part that cannot be seen, and is not an accurate side view. Similarly, FIG. 1C is a schematic cross-sectional view.

  FIG. 2 is a diagram for explaining a position error and correction caused by a sample mounting deviation that requires the present invention. The horizontal axis in FIG. 2 indicates the movement direction of the X axis on the sample stage 102 of the line width measurement device, and the vertical axis indicates the movement direction of the Y axis on the sample stage 102 of the line width measurement device.

The broken line frame 24 is an ideal mounting position of the object to be measured, and the coordinate axis of the object 103 to be measured at this mounting position is parallel to the XY axis of the stage mechanism of the line width measuring device, and the reference ( This is the mounting position where the origin of the object to be measured and the origin of the line width measuring device match. When such an object to be measured is, for example, an LCD substrate, when a plurality of products to be inspected having the same shape are broken line 24, x pieces are parallel to the X axis and y pieces are parallel to the Y axis. A total of x x y is arranged on the pitch.
The solid line frame 25 is the position of the sample that is actually mounted, and a positional deviation in the XY-axis direction (reference point mismatch) and a rotational direction deviation occur. These deviations cause measurement errors that require position correction. For example, among the two products arranged in the same column, the measurement coordinate P1 is included in the imaging field of the imaging head unit 10, but is arranged in the same column in the imaging field of the imaging head unit 11. If the measurement coordinate P2 is not included, it can be said that the measurement error requires position correction. Details will be described below.

Fig. 2 shows the displacement (particularly the displacement in the rotational direction) caused by mounting the object to be measured, where 24 is a broken line frame indicating the ideal mounting position of the object to be measured, and 25 is the actual object to be measured. A solid line frame 18 indicating the mounting position of the object, 18 is a positional deviation amount θ in the rotation direction. At the actual mounting position of the object to be measured, an ideal mounting position of the object to be measured and a positional deviation in the rotation direction are generated. 18 is the rotational misalignment θ in the rotation direction, 19 is the position of the measurement coordinate P1 (measurement point) of the imaging head unit 10 which is the reference for position control in the multi-imaging head unit, and 20 is actually measured by the imaging head unit 11 The position of the coordinate P2 to be measured, 21 The position of the measurement coordinate of the imaging head unit 11 at the ideal mounting position of the object to be measured, 22 is the amount of deviation in the X axis direction caused by the deviation in the rotational direction to be corrected Δ X and 23 are Y-axis direction displacements ΔY and 26 caused by deviations in the rotational direction to be corrected, and 26 is the distance (Y _P1-P2 ) between the measurement coordinates P1 and P2.

  In order to detect the shift in the rotation direction, for example, the alignment pattern 28 shown in FIG. 2 is used, and the alignment pattern is recognized by pattern recognition by matching the pattern registered in advance with the image captured by the imaging head unit 10. The position coordinates of 28 are obtained, then the imaging head unit 10 is moved, the position coordinates of the alignment pattern 29 are obtained by the same pattern recognition, and the difference from the ideal sample mounting position is detected and obtained. .

The deviation amount ΔX 22 and the deviation amount ΔY 23 can be obtained by the following expressions (1) and (2).
△ X = Y _P1-P2 × sin θ ............ Formula (1)
△ Y = Y _P1-P2 × (1-cos θ) ··· Equation (2)

  In FIG. 2, when the mounting position of the measurement target object 103 is shifted as indicated by the solid line frame 25, the position 19 of the measurement coordinate P1 of the imaging head unit 10 on the sample table 102 and the measurement coordinate P2 of the imaging head unit 11 The position 21 on the sample stage 102 is the ideal ideal mounting position of the object to be measured, and the coordinates on the X axis must match, but the position 20 of the correct position coordinate P2 to be actually measured is Amount △ X 22 is shifted, and also the amount △ X 23 is shifted on the Y axis.

  When the position 19 of the measurement coordinate P1 of the imaging head unit 10 is used as a reference, in order to move the imaging head unit 11 to the correct measurement position 21, the amount ΔX 22 and the amount ΔY 23 must be moved. Here, in order to perform the correction movement of the amount ΔX 22, the imaging head unit 10 and a drive shaft for individually moving the imaging head unit 11 are required. That is, the ΔX1 axis 8 and the ΔX2 axis 9 of the present invention are required.

  For example, only the imaging head unit 11 is slightly moved in the X-axis direction by the △ X2 axis 9 and only the imaging head unit 10 is slightly moved in the X-axis direction by the △ X1 axis 8 or individually. By moving at least one of the imaging head unit 10 and the imaging head unit 11, the measurement points of the imaging head unit 10 and the imaging head unit 11 can be corrected so as to coincide on the X axis.

  The Y-axis direction can also be corrected with higher accuracy by moving at least one of the imaging head unit 10 or the imaging head unit 11 individually by the guide 4 of the Y1 axis or the guide 5 of the Y2 axis.

The number of imaging head units is two in the above embodiment, but any number may be used as long as there are a plurality of imaging head units.
In the above-described embodiment, the measurement or inspection is performed using the transmitted illumination. However, if the line width measuring device is only used for the measurement or inspection using the reflected illumination, the transmitted illumination is not necessary. Interlocking is also unnecessary.

  In FIG. 1, only the configuration according to the invention has been described in the line width measuring apparatus. However, for example, an image of a predetermined portion of the measurement target object is acquired from the imaging head unit and output after the image processing unit. A unit to measure or inspect is needed. In addition, a light source must be attached to the transmitted illumination, and all necessary components in the line width measuring device, such as a mechanism part for moving each guide and shaft for position correction, etc. are described. Not. For example, at least the configuration described in FIG. 3 below is necessary.

FIG. 3 is a block diagram showing a schematic configuration of the line width measuring apparatus.
In FIG. 3, reference numeral 508 denotes an imaging head unit including an observation color camera unit, a measurement camera unit, an electric revolver unit, a laser autofocus unit, 509 is a sample stage, 510 is a position correction unit, 512 is an air vibration isolation table, 513 is an illumination power supply, 514 is a color monitor, 515 is a measurement monitor, 516 is a measurement result display monitor, 517 is a video printer, 518 is an image processing PC (Personal Computer), 519 is a control PC, and 520 is a stage controller. , 521 is a transmission illumination power source, and 522 is a transmission illumination head. Reference numeral 501 includes an imaging head unit 508, a sample stage 509, a position correction unit 510, an air vibration isolation table 512, an illumination power source 513, a stage control unit 520, a transmission illumination power source 521, and a transmission illumination head unit 522. It is a measuring part.

In FIG. 3, an image taken with the observation color camera of the imaging head unit 508 is displayed on the color monitor 514, and an image taken with the measurement camera is displayed on the measurement monitor 515.
The measuring device starts measurement in response to a command from the external host (HOST) or control PC 519. The measurement is started automatically or manually based on a preset recipe, the measurement result is displayed on the measurement result display monitor 516, and the measurement result is, for example, HD (Hard Disk) in the control PC 519. Written in a predetermined area of the magnetic disk. Further, the measurement result data is distributed to the external host in response to a request from the external host.
The air vibration isolation table 512 prevents external vibrations from being transmitted to the sample table 509.

The image processing PC 518 analyzes the image input from the imaging head unit 508, recognizes a predetermined pattern set in advance in the measurement target object 103, acquires its position coordinates, and obtains a correction amount.
The obtained correction amount information is output to the control PC 519, and the control PC 519 gives a control instruction signal to the stage control unit 520 based on the correction amount information. The stage control unit 520 gives a control signal corresponding to the input control instruction signal to the position correction unit 510 to perform position correction.
Measurement or inspection is performed while correcting the position in this way.

The dimensions (unit: mm) of the LCD substrate are, for example, 1850 × 1500 or 2250 × 1950 in the horizontal dimension X × vertical dimension Y, and the thickness is about 0.5 to 0.7. For example, when it is predicted that the amount of positional deviation when the object to be measured is carried on the sample stage by a transfer robot or the like is about ± 5 to 10 mm, the maximum correction amount is set to ± 10 mm. That is, the stroke of the guide 8 on the △ X1 axis and the guide 9 on the △ X2 axis should be set to ± 10 mm.
As described above, the correction of the deviation in the Y-axis direction may be executed by the guide 4 on the Y1 axis or the guide 5 on the Y2 axis.
Further, a manipulator that can be finely adjusted in the X-axis direction, the Y-direction, and the rotation (θ) direction may be used, and correction may be performed by the control PC 519.

  As described above, according to the present invention, using a conventional clamping mechanism (pressing mechanism using an air cylinder or the like), there is a problem in a method of mechanically moving the mounting position of the object to be measured. The sample cannot be actually moved due to the increase in the size of the object to be measured and the influence of static electricity. In addition, even when using a method of measuring and correcting the displacement of the mounting position by image recognition, there is a problem that the measurement cannot be performed efficiently due to the displacement between the heads caused by the multi-imaging head (originally the coordinate in the X-axis direction). For example, when measuring two points with the same image using two imaging heads, it is efficient to perform simultaneous image capture processing with a single positioning operation in the X-axis direction. However, if the sample mounting position shift includes a rotational component, the amount ΔX shifts, and the detection process is practically performed in one X-direction positioning operation, especially for large samples. This problem can be solved by providing a ΔX axis mechanism and controlling this mechanism for position correction by an amount ΔX.

4 to 15 are flowcharts showing an embodiment of the operation sequence of each axis in the present invention.
The flowchart of the positioning operation of the embodiment of the present invention is roughly divided into four processing sequences (procedures). That is, the main sequence unit that controls the entire process, the first image analysis sequence unit that analyzes the image captured by the imaging head unit 10 according to the instruction from the main sequence unit, and the imaging head unit 11 captured according to the instruction from the main sequence unit According to an instruction from the second image analysis sequence unit that analyzes the image and the main sequence unit, the measurement unit 501 of the line width measurement apparatus (in the configuration shown in FIG. 3, the imaging head unit 508, the sample stage 509, the position correction unit 510, an air vibration isolator 512, an illumination power source 513, a stage control unit 520, a transmission illumination power source 521, and a transmission illumination head unit 522).
Further, as shown in FIG. 3, the main sequence unit is processed in the control PC 519, and the first image analysis sequence unit and the second image analysis sequence unit receive an instruction from the control PC 519 and receive the image processing PC. Processed with 518. Further, the operation of the measurement unit 501 is processed by the stage control unit 520 in response to an instruction from the control PC 519.

4, 7, and 12 are flowcharts showing the central processing operation of the positioning operation sequence of the present invention, and show the main processing operation sequence in the control PC 519. 5 to 6, FIG. 8 to FIG. 11, and FIG. 13 to FIG. 15 show image processing for each head based on commands from the main processing operation sequences of FIG. 4, FIG. 7, and FIG. 5 is a flowchart showing a processing operation sequence for controlling each stage unit of the line width measuring apparatus and returning result information to the main processing operation sequence.
For example, FIG. 5, FIG. 8, and FIG. 13 show flowcharts of an image 1 processing operation sequence for processing an image (Image 1) taken by the imaging head unit 10, and FIG. 5, FIG. 9, and FIG. A flowchart of an image 2 processing operation sequence for processing an image (Image 2) taken by the head unit 11 is shown. 6, FIG. 10, FIG. 11 and FIG. 15 show a measurement unit processing sequence for processing a required component of the measurement unit 501 in response to a command from the main processing operation sequence.

  The Interlock signal in FIG. 4 is an emergency stop command, and is generated when, for example, an operator or the like enters the room in which the apparatus is installed, and detects that the door is opened. Another example is when the operator presses the stop button of the apparatus. When this Interlock signal is input, Interlock presence / absence determination processing is performed. If the Interlock signal is input, the operation of the apparatus is stopped as Error processing. This Interlock signal input and Interlock presence / absence judgment processing is shown as this sequence in FIG. 4 because it needs to be displayed in the figure. However, when Interlock signal is input in any sequence in the main processing operation sequence, Processing operations are performed.

In addition, the image PC HDD in FIG. 5 stores an image captured by the imaging head unit, and a desired image is captured by specifying an address from the main processing operation sequence, and processing of image 1 or 2 is performed. Used in the operation sequence. In addition, the processing result is stored.
The correction table in FIG. 6 stores correction data for correcting mechanical errors of the apparatus such as straightness, and is used for correcting position coordinates and the like.
The laser autofocus process (Laser AF) and the measurement autofocus process (Measurement AF) in the sequences of FIGS. 8 to 11 and FIGS. 13 to 15 are not shown in FIG. Used (see, for example, JP-A-2005-98970 and JP-A-7-17013).

Next, with reference to FIG. 16 and FIG. 2, an embodiment of the process of correcting the position of the imaging head unit with respect to the shift in the rotation direction when the sample (object to be measured) of the present invention is mounted will be described. FIG. 16 is a flowchart showing an embodiment of the operation sequence of the present invention.
As shown in FIG. 2, the position when the object to be measured (solid line frame 25) mounted on the sample stage 102 deviates in the rotation direction, as can be seen from the ideal mounting position (dashed line frame 24). The correction processing operation will be described.

First, in FIG. 2, the deviation amount ΔX in the X direction caused by the deviation in the rotational direction to be corrected and the deviation amount ΔY in the Y direction are calculated by the above-described equations (1) and (2).
Using the calculated deviation amount ΔX 22 and deviation amount ΔY 23, position correction is performed according to the sequence shown in FIG.

In FIG. 16, measurement position coordinate data 301 is output from the Main PC HDD in FIG. 4, and image processing PC 518 in FIG. 3 is used as the alignment correction amount data 302 to analyze the image input from the imaging head unit 508 and It is obtained by recognizing a predetermined pattern preset in the measurement object 103 and acquiring its position coordinates.
From these data, the X axis travel (X1 + X _{AL_offset} ), Y1 travel (Y1 + Y _{AL_offset} ), Y2 travel (Y2 + Y _{AL_offset} + Y _{AL_angle} ), and △ X2 travel A quantity (X2−X1 + _{YAL_offset} + _{YAL_angle} ) is sent from the control PC 519 to the stage controller 520, and each axis moves (stage movement 303).
As a result, the respective measurement points P1 and P2 are projected within the visual field range of the imaging head units 10 and 11.

Next, the image processing PC 518 performs pattern matching position detection processing between a part of the image 1 acquired by the imaging head unit 10 and a pre-registered pattern (detection processing 304), and moves the measurement target to the center of the visual field range. A correction amount for movement is calculated, and the movement amount of the Y1 axis and the movement amount of the ΔX1 axis are sent to the stage control unit 520 via the control PC 519 (processing 305).
Similarly, the image processing PC 518 performs pattern matching position detection processing between a part of the image 2 acquired by the imaging head unit 11 and a pre-registered pattern (detection processing 306), and moves the measurement target to the center of the visual field range. A correction amount for movement is calculated, and the movement amount of the Y2 axis and the movement amount of the ΔX2 axis are sent to the stage control unit 520 via the control PC 519 (processing 307).

In response to the above movement instruction, the stage control unit 520 moves the Y1, △ X1, Y2, and △ X2 axes while keeping the X axis fixed, and then the imaging head units 10 and 11 respectively. An image is acquired, and line width measurement processes 309 and 310 are executed.
When the line width measurement process within the visual field range centering on the current measurement points P1 and P2 is completed, the measurement position coordinate data 301 of the next measurement point is output from the Main PC HDD in FIG. Moving. That is, the operation of FIG. 16 is repeated.

As described above, when moving a plurality of imaging head units to the measurement point, it is necessary to move the plurality of imaging head units in order to correct the rotation when the object to be measured is mounted on the sample stage. Since the number of axes and the procedure can be minimized, the tact time can be shortened.
In the above embodiment, the position correction of the ΔX2 axis is executed each time the measurement point is moved. However, if the production position accuracy of each multi-piece product on one object to be measured is good, If the ΔX2 axis position correction is performed, the ΔX2 axis position correction need not be performed each time the measurement point is moved.

The figure for demonstrating the structure of one Example of the line | wire width measuring apparatus of this invention. The figure explaining the position error and correction which generate | occur | produce by the mounting | wearing deviation of a sample. The block diagram which shows the structure of one Example of the line | wire width measuring apparatus by this invention. The flowchart which shows one Example of the operation | movement sequence of each axis | shaft by this invention. The flowchart which shows one Example of the operation | movement sequence of each axis | shaft by this invention. The flowchart which shows one Example of the operation | movement sequence of each axis | shaft by this invention. The flowchart which shows one Example of the operation | movement sequence of each axis | shaft by this invention. The flowchart which shows one Example of the operation | movement sequence of each axis | shaft by this invention. The flowchart which shows one Example of the operation | movement sequence of each axis | shaft by this invention. The flowchart which shows one Example of the operation | movement sequence of each axis | shaft by this invention. The flowchart which shows one Example of the operation | movement sequence of each axis | shaft by this invention. The flowchart which shows one Example of the operation | movement sequence of each axis | shaft by this invention. The flowchart which shows one Example of the operation | movement sequence of each axis | shaft by this invention. The flowchart which shows one Example of the operation | movement sequence of each axis | shaft by this invention. The flowchart which shows one Example of the operation | movement sequence of each axis | shaft by this invention. The flowchart which shows one Example of the operation | movement sequence of this invention.

Explanation of symbols

  1: Y axis beam (beam), 2: X1 axis guide, 3: X2 axis guide, 4: Y1 axis guide, 5: Y2 axis guide, 6: Z1 axis guide, 7: Z2 axis guide Guide: 8: ΔX1 axis guide, 9: ΔX2 axis guide, 10, 11: Imaging head, 12: Py1 axis, 13: Py2 axis, 14: ΔPx1 axis,, 15: ΔPx2 axis, 16 , 17: Transmitted illumination, 101: Pedestal, 102: Sample table, 103: Object to be measured, 104: Transmitted illumination guide.

Claims (3)

A line width measuring device including a plurality of imaging head units and an image processing unit, and measuring or inspecting a desired portion of the measurement target object by performing image processing on the image acquired by the imaging head unit. In
A position correcting means for individually correcting the positions of the plurality of imaging head units;
The image processing unit detects the position of each of the plurality of imaging head units from the image of the measurement target acquired by the plurality of imaging head units,
The position correction means corrects the positions of the plurality of imaging head units individually based on the detected positions ,
A line width measuring apparatus for correcting a mounting position shift of an object to be measured by image processing . Means for enlarging a part of the sample,
A plurality of imaging head units that can be individually moved on the same axis;
Position correction means for changing the position of the sample to be photographed ;
Image processing means for detecting the position of the imaging head unit from the image of the photographed sample and correcting the positional deviation of the sample from the detected position and the position of the sample;
Having a control means for operating the position correction means based on the positional deviation correction of the image processing means ,
A line width measuring apparatus for correcting a positional deviation of the sample. In a line width measuring apparatus having a plurality of imaging head units capable of enlarging imaging of a part of a sample and movable independently of each other, and an operation means for changing the position of the sample ,
An image processing function for performing image processing for detecting the positions of the plurality of imaging head units with respect to an image of the sampled image;
An apparatus for measuring the dimensions of the sample from the captured image, the control means having the operation means operated by a computer program ,
A moving fine movement mechanism in a direction perpendicular to the moving axis of the imaging head unit for correcting the mounting position deviation of the sample;
By providing fine movement mechanism control means for controlling the moving fine movement mechanism based on image processing of the image processing function, and position correction means for measuring and correcting the mounting deviation of the sample ,
Referenced to one of the imaging head, the line width measuring device and corrects a position capture image by moving the position of the other imaging head.

Images