JP6482061B2 - Mask stage and stage apparatus - Google Patents

Description

The present invention relates to a mask stage that supports various masks such as an optical mask and an EUV mask.
The present invention also relates to a stage apparatus that drives various masks in the X and Y directions.

In a pattern inspection apparatus that inspects a pattern formed on an optical mask (reticle or photomask), the optical mask to be inspected is arranged on an XY stage, and the entire surface of the mask is moved by relative movement of the XY stage in the X and Y directions. Are scanned by the inspection beam. In the pattern inspection system, it is necessary to detect the defect and specify the address of the detected defect. Therefore, it is important to accurately detect the mask coordinates during the inspection, and high-precision coordinate accuracy management is required. ing. In the conventional XY stage, an X-direction linear motion guide extending in the X direction is provided on a surface plate, and the X stage is connected to the X-direction linear motion guide. A Y direction linear motion guide extending in the Y direction is provided on the X stage, and the Y stage is connected to the Y direction linear motion guide. The Y stage functions as a mask stage that supports the mask. The mask stage is provided with a vacuum chuck, and the optical mask is clamped to the mask stage by the vacuum chuck.

In the XY stage, a laser interferometer is used as means for detecting mask coordinates, and two bar mirrors orthogonal to each other are fixed on the mask stage. During operation, a laser beam is projected from the laser interferometer toward the bar mirror provided on the mask stage, and the coordinates in the X and Y directions of the mask are detected using the reflected light from the bar mirror (for example, patents). Reference 1).
JP 2010-238933 A

In the conventional XY stage, the X stage and the Y stage move along two linear motion guides. However, when the parallelism and straightness of the two linear motion guides are incomplete, the mask table supporting the mask is distorted, and the mask coordinates detected by the laser interferometer are between the actual mask coordinates. A defect that causes an error occurs. Further, the distortion generated in the mask table is also transmitted to the clamped mask, the mask itself is also distorted, and the detected mask coordinates contain an error component. In such a case, when observing the inspected mask with a high-power microscope, the detected mask coordinates include an error component, which makes it difficult to accurately position the observation position on the optical axis of the objective lens. It has occurred. Similarly, when a defect detected by the inspection apparatus is corrected, there is a problem that it is difficult to accurately position the detected defect at the target position.

Further, in the conventional XY stage, the mask is clamped to the mask table using a vacuum chuck or an electrostatic chuck. If clamping is performed using the chucking means, the mask is firmly clamped to the mask table, so that even if rapid acceleration occurs on the stage during operation, a problem that the mask slips and is displaced is prevented. However, when the mask is clamped using a vacuum chuck, there is a problem that the mask itself is distorted and the accuracy of the mask coordinates is lowered.

As a method of solving the problems caused by clamping, a plurality of support pads are provided on the mask table, and the gravity acting on the support pads from the mask and the frictional force generated between the back surface of the mask and the front surface of the support pad are used. Thus, a method of supporting the mask on the table is assumed. In this mask support method, the mask is maintained in a free state, and undesired distortion does not occur in the mask, so that the coordinate accuracy can be managed with high accuracy. Therefore, there is an advantage that coordinate management can be performed with higher accuracy than the conventional mask stage. However, in this mask support method, since the mask is not clamped, if a rapid acceleration occurs, a slip occurs at the support point of the mask, and there is a possibility that a positional deviation occurs between the mask and the stage. If the mask is misaligned, the mask coordinates detected by the laser interferometer have a defect including an error component.
Further, in the mask manufacturing process, so-called defect mitigation, that is, defect coordinates of a mask blank are specified, and a circuit pattern position is corrected and drawn so as not to have this influence. In this case, it is necessary to specify the defect coordinates of the mask blank on the order of nm.

The problems described above are less likely to be a problem when the mask coordinates are managed by coordinate information with relatively low accuracy. However, the line width of the mask pattern is miniaturized, and when it is necessary to detect a defect detected by the mask inspection apparatus with a coordinate accuracy of, for example, about 10 nm, only a small displacement of the mask or a small distortion occurs on the stage. However, there is a problem that the detected mask coordinates do not match the target accuracy. That is, in the case of a mask inspection apparatus for inspecting a photomask, the coordinate accuracy of a mask inspection apparatus currently in practical use is on the order of microns. However, the line width of the mask pattern is reduced, and in the case of an EUV mask in particular, a pattern having a line width of about 10 nm is used. In this case, when the defect detected by the defect inspection apparatus is observed with a microscope after the inspection, the defect coordinates must be managed with a coordinate accuracy of about 10 nm in order to observe using a high-magnification objective lens. When such high-precision coordinate accuracy is required, there is a problem in that the detected coordinate information includes an error component even if a slight distortion occurs on the mask stage or a minute displacement occurs on the mask on the stage. Difficult positioning operation becomes difficult. Therefore, there is a strong demand for highly accurate mask coordinate management different from the conventional coordinate management system. In particular, in EUVL (EUV lithography), since it is required to manage defect coordinates detected by a mask inspection apparatus with an accuracy of several nm, high-precision coordinate management different from the coordinate precision of an optical mask is strong. It has been requested.

The above-mentioned problems are not limited to a mask inspection apparatus, but also in a pattern drawing machine that draws a pattern on a mask blank, an exposure machine that transfers a pattern onto a wafer, and a stage apparatus that is used in an inspection apparatus that performs defect inspection on a mask blank. Has been pointed out.

An object of the present invention is to realize a mask stage that can control mask coordinates with high accuracy.
Furthermore, another object of the present invention is to provide a mask stage that can accurately control mask coordinates even when the mask is not clamped to the stage.
Another object of the present invention is to realize a stage apparatus that can control mask coordinates with high accuracy.

The mask stage according to the present invention is a mask stage that supports various masks,
A mask table on which the mask is placed;
A mask support means fixed to the mask table and on which the mask is placed;
First and second bar mirrors fixed to a mask table and interlocked with a laser interferometer or laser length measuring device, wherein the first bar mirror extends in a first direction and the second bar mirror is a first bar mirror. First and second bar mirrors extending in a second direction orthogonal to the direction;
Fixed to the first bar mirror, two or more sensor means for detecting the distance to the mask in the second direction or the displacement of the mask in the second direction, and fixed to the second bar mirror And one or more sensor means for detecting a distance to the mask in the first direction or a displacement of the mask in the first direction,
The sensor means projects a light beam toward the side surface of the mask supported on the mask table, receives reflected light reflected by the side surface of the mask,
A translational movement amount of the mask is measured using an output signal from the sensor means .

INDUSTRIAL APPLICABILITY The present invention is suitable for a pattern drawing machine that performs pattern drawing while maintaining a mask in a free state without clamping the mask stage, and a stage device used for a pattern inspection apparatus that inspects a pattern formed on a mask. Realize the mask stage. Therefore, the mask stage is provided with sensor means for detecting the displacement of the mask to monitor the displacement of the mask during operation. With this configuration, the mask is not clamped and is maintained in a free state, so that the problem of unwanted distortion occurring in the mask itself is solved, and coordinate management with higher accuracy can be performed. At the same time, the position of the mask with respect to the mask stage is always detected even if the mask is displaced during operation of the stage device such as during pattern inspection or pattern drawing, so the mask stage detected by a laser interferometer or laser length measuring machine. By correcting the position information using the position information of the mask detected by the sensor means, it becomes possible to always output accurate mask coordinates.

In the present invention, the sensor means projects the measurement beam toward the side surface of the mask supported on the mask table, receives the reflected light reflected from the side surface of the mask, and performs distance measurement or displacement measurement. It consists of a sensor or a displacement meter. Optical masks and EUV masks are made of a glass material having a thickness of several millimeters, and their side surfaces are polished with high accuracy. Therefore, the side surface of the mask functions as a stable reflecting surface that is not easily affected by disturbance. In the present invention, paying attention to the stability of the mask side surface, the side surface of the mask is used as a reference reflection surface for displacement detection. As a result, the displacement of the mask during operation can be detected stably. As the sensor means, various optical distance sensors such as optical fiber sensors and displacement meters can be used.

When the sensor means is composed of a displacement meter, the distance to the mask when the mask is placed on the mask stage and initially set is the reference length, and the difference between the reference length and the detected distance to the mask is the displacement amount. Can be output.

In a preferred embodiment of the mask stage according to the present invention, the mask stage further comprises first and second bar mirrors fixed to the mask table and interlocked with a laser interferometer or laser length measuring machine, A bar mirror extends in the first direction, a second bar mirror extends in the second direction;
The first bar mirror measures the distance in the second direction to the mask side surface extending in the first direction of the mask or the amount of displacement in the second direction of the mask side surface. The sensor means is fixed, and the second bar mirror measures the distance in the first direction to the mask side surface extending in the second direction of the mask or the displacement amount in the first direction of the mask side surface. A third sensor means is fixed,
The translational movement amount of the mask is measured using output signals from the first to third sensor means.

The coordinates of the mask stage are measured by a bar mirror and a laser interferometer or laser length measuring device provided on the mask stage. That is, a laser beam is projected from the laser interferometer toward the bar mirror, and the position in the X and Y directions of the stage is detected using the reflected light from the bar mirror. The bar mirror is a reflector in which a reflecting surface is formed on a prismatic body such as synthetic quartz. This bar mirror has a small thermal expansion coefficient, is manufactured with high accuracy, and has a characteristic that it is not easily influenced by external factors. In view of the characteristics of these bar mirrors, the bar mirror can be used as a positioning reference member. A position detection sensor is provided on the bar mirror to detect the position of the mask with respect to the mask stage, and monitor the displacement of the mask during operations such as defect inspection.

In a preferred embodiment of the mask stage according to the present invention, the mask support means is constituted by a plurality of support pads fixed on the mask table and supporting the mask, and the mask is disposed on the support pads, and the masks support pads. And a frictional force acting between the back surface of the mask and the surface of the support pad. Since the mask is made of a glass material as a base material, its weight is considerably heavy, and a considerable amount of gravity acts on the support pad. Also, acrylic and polyimide elastically deformable resin materials have a considerably large coefficient of friction. Therefore, the mask can be stably supported by the gravity acting on the mask and the frictional force acting between the back surface of the mask and the surface of the support pad. Furthermore, according to the experiment results of the present inventors, when various types of stage devices currently in circulation were tested, when the mask was supported by its gravity and frictional force, almost no slip occurred during the operation, and no slip occurred. Even if it occurs, it has been confirmed that the generated slip amount is very small. Therefore, by constantly monitoring the position of the mask in the X and Y directions by the position detection means provided on the mask stage, the problem of distortion caused by clamping the mask is solved, and coordinate management with higher accuracy is performed. It can be carried out.

The support pad that supports the mask can be made of an elastically deformable resin material having a large coefficient of friction. A sudden acceleration is generated in the mask and slip occurs during a period when the mask stage shifts from the running state to the stationary state and during a period when the mask stage shifts from the stationary state to the traveling state. On the other hand, if the support pad that supports the mask is made of an elastic material, when the mask attempts to overshoot when shifting from the running state to the stationary state, the support pad is elastically deformed and a restoring force acts. This restoring force acts as a brake on the mask and prevents the occurrence of slip. Further, when shifting from the stationary state to the traveling state, the support pad acts to alleviate the acceleration. Therefore, by configuring the support pad that supports the mask with an elastically deformable material, the mask can be stably supported by the gravity of the mask and the frictional force between the mask and the support pad.

A stage apparatus according to the present invention is a stage apparatus that supports a mask and drives the supported mask in the X direction and the Y direction orthogonal to the X direction,
An X stage coupled to guide means extending in the X direction;
A mask stage provided on the X stage and connected to guide means extending in the Y direction and having mask support means for supporting the mask ;
First driving means for moving the X stage along the X direction and second driving means for driving the mask stage in the Y direction;
First and second laser interferometers or laser length measuring devices for detecting the positions of the mask stage in the X direction and Y direction, respectively;
First and second bar mirrors fixed on the mask stage and interlocked with the laser interferometer or laser length measuring machine , wherein the first bar mirror extends in the X direction and the second bar mirror is in the Y direction. First and second bar mirrors extending to
Two or more sensor means fixed to the first bar mirror and measuring the distance to the Y-direction mask or the displacement amount of the Y-direction mask, and to the X-direction mask fixed to the second bar mirror One or more sensor means for measuring a distance or a displacement of the mask in the X direction ;
Signal processing for inputting position information of the mask stage output from the first and second laser interferometers or laser length measuring instruments and distance information or displacement information output from the sensor means, and outputting coordinate information of the mask Having a device ,
The sensor means projects a light beam toward the side surface of the mask, receives reflected light reflected by the side surface of the mask ,
The signal processing apparatus has means for calculating a translational movement amount of the mask using an output signal from the sensor means .

In the stage apparatus according to the present invention, the position of the mask stage in the X and Y directions is detected by the laser interferometer, and the position of the mask in the X and Y directions relative to the mask stage is always detected by the position detection means arranged on the mask stage. Therefore, even if the mask slips during the operation, the displacement amount of the mask in the X and Y directions with respect to the mask stage is immediately measured, and the position information of the mask stage can be corrected using the measured displacement amount. . As a result, the mask coordinates can be managed with high accuracy.

In the present invention, the mask is placed on the plurality of support pads provided on the mask table, and the mask is supported by the gravity acting on the support pad from the mask and the frictional force acting between the back surface of the mask and the front surface of the support pad. As a result, the problem of undesired distortion in the mask itself is eliminated, and coordinate management with higher accuracy can be performed. Further, since sensor means for detecting the position of the mask with respect to the mask stage is provided and the displacement of the mask during operation is constantly monitored, even if a slip occurs in the mask, the laser is used by using position information output from the sensor means. Position information output from the interferometer can be corrected, and highly accurate coordinate management can be performed. As a result, when applied to a stage apparatus used in a defect inspection apparatus, alignment work when observing a detected defect using a high-magnification objective lens after inspection is facilitated.

It is a figure which shows the whole structure of the stage apparatus containing the mask stage by this invention. It is a figure which shows the structure of the coordinate output of a signal processing apparatus. It is a figure for demonstrating the displacement amount calculation method.

FIG. 1 shows an example of a stage apparatus and a mask stage according to the present invention. The stage apparatus of the present invention is applied to various apparatuses mainly composed of a mask such as a pattern drawing machine for drawing a pattern on a mask, a mask inspection apparatus for inspecting a pattern formed on the mask, and an inspection apparatus for inspecting mask blanks. Can do. The mask stage of the present invention can be applied to various stage apparatuses such as an XY stage, an XYθ stage, an XYZ stage, and an XYZθ stage. Furthermore, an optical mask, a reticle, an EUV mask, or a mask blank can be used as the mask.

In this example, an XY stage used in a mask inspection apparatus that detects a defect present in a photomask will be described as an example. FIG. 1A is a diagrammatic plan view showing a state in which a photomask is mounted, and FIG. 1B is a diagrammatic side view. Two X-direction linear motion guides 2 are provided on the surface plate 1. Only one linear guide is shown in the drawing. The X table 3 is connected to the two linear motion guides 2 via a slider. An X motor 4 for moving in the X direction is fixed to the X table 3, and the X table 3 translates in the X direction along the X direction linear motion guide 2. On the X table 3, two Y direction linear motion guides 5a and 5b extending in the Y direction are fixed. The Y table 6 is connected to the linear motion guides 5a and 5b via a slider. A Y motor 7 is connected to the Y table 6, and the Y table translates in the Y direction along the linear motion guide.

The Y table 6 functions as a mask table on which a mask is placed. On the mask table 6, three support pads 9a to 9c for supporting the mask 8 are provided. The support pad is made of, for example, an allyl, polyimide or silicon elastic resin material having a large friction coefficient. In this example, the two support pads 9a and 9b are aligned along the X direction, and the support pad 9c is orthogonal to the axis connecting the support pads 9a and 9b and is on the axis passing through the intermediate point of these support pads in the X direction. To place. The mask 8 is disposed on the three support pads 9a to 9c. Photomasks and EUV masks are made of a glass material having a thickness of several millimeters, and the support pad has a large coefficient of friction. Therefore, the photomask 8 is supported by the strong gravitational force acting on the support pad from the photomask and the friction force generated between the bottom surface of the photomask and the surface of the support pad only by arranging the photomask 8 on the three support pads. . In this case, since the mask 8 is not clamped with respect to the mask stage, the mask 8 is supported in a free state, and the problem of undesired distortion in the mask is eliminated. In addition, since the three support pads are made of an elastic material, the support pad can be used even when a sudden acceleration acts on the mask when the stage shifts from the running state to the stationary state and when the stage shifts from the stationary state to the traveling state. The elastic deformation reduces the acceleration and prevents the occurrence of slip.

First and second bar mirrors 10 a and 10 b that are linked to a laser interferometer described later are fixed to the mask table 6. The first bar mirror 10a extends in the Y direction, and the second bar mirror 10b extends in the X direction. Instead of using two bar mirrors, it is also possible to use an L-shaped bar mirror in which a reflection bar extending in the X direction and a reflection bar extending in the Y direction are combined. The first bar mirror 10a is provided with two sensor means 11a and 11b, and the second bar mirror 10b is provided with one sensor means 11c. These sensor means are constituted by an optical distance sensor or an optical displacement meter, and detect the distance from the sensor means to the mask or the displacement amount of the mask. In this example, an optical fiber sensor is used as the sensor means. That is, by projecting a laser beam from the optical fiber sensor toward the side surface of the mask 8 and receiving a reflected beam from the side surface of the mask, the positions in the X direction and the Y direction to the side surfaces 8a and 8b of the mask 8 are detected. And output as distance information. The side surface of the mask is a flat surface polished with high accuracy. Therefore, in the present invention, the mask side surface is used as a reference reflection surface for position measurement. An optical fiber sensor can also be used as a displacement meter. In this case, the distance information detected when the mask is placed on the mask table and initially set can be used as reference information, and the displacement amount from the reference information can be output. In the following description, the sensor means will be described as being used as a distance sensor and measuring the distance to the side surface of the mask.

During operation, the first and second position detection sensors 11a and 11b detect the distance in the X direction to the side surface 8a extending in the Y direction of the mask, and the third position detection sensor 11c is in the X direction of the mask. The distance in the Y direction to the side surface 8b extending in the direction is detected. Even if the mask rotates during operation, the amount of rotation is about a few seconds, and the light receiving angle of the reflected beam in the optical fiber sensor is a wide angle range of about several degrees. However, the reflected light from the bar mirror is received by the optical fiber sensor, and the distance to the mask can be measured stably. In the drawing, only the head of the optical fiber sensor is shown, and the main body of the optical fiber sensor that outputs position information is not shown.

Three laser interferometers or laser length measuring devices 12 a to 12 c are provided on the surface plate 1. The first and second laser interferometers 12a and 12b are arranged in the Y direction, project a laser beam toward the first bar mirror, and detect the X direction coordinate of the mask stage. The third laser interferometer 12c projects a laser beam toward the second bar mirror and detects the Y-direction coordinates of the mask stage. Using the outputs from these three laser interferometers, position information of the mask stage in the X and Y directions and the amount of rotation of the mask stage are detected.

The position information (coordinate information) output from the three laser interferometers 12a to 12c and the position information output from the three optical fiber sensors 11a to 11c are supplied to the signal processing device 13, and the defect is detected when the defect is detected. Is output.

The coordinate system of the laser interferometer for detecting the position of the mask stage and the coordinate system of the position detecting means for detecting the position of the mask with respect to the mask stage both use a common coordinate system. That is, the laser interferometer positions the optical axis of the inspection optical system at the reference mark formed on the mask, and detects the position of the mask stage in the X and Y directions using the position as the origin. Further, the position detection means detects the position of the mask in the X and Y directions using the intersection of the laser beams of the laser interferometer as the origin when the optical axis of the inspection optical system is positioned at the reference mark. Therefore, the position information output from the laser interferometer and the position information output from the position detection means can be handled as having the same coordinate system.

FIG. 2 is a diagram showing an algorithm for outputting defect coordinates in the signal processing apparatus. The position information output from the three laser interferometers 12 a to 12 c is stored in the first coordinate memory 21. In this case, when the defect inspection apparatus detects a defect and a defect detection signal is input, the coordinate output at that time is stored. As the defect coordinates, position information from a laser interferometer or laser length measuring devices 12a and 12c can be used. The distance information output from the three sensor units 11 a to 11 c is stored in the second coordinate memory 22. When the defect inspection apparatus detects a defect and a defect detection signal is input, the second coordinate memory 22 stores a coordinate output at that time. The defect coordinate information stored in the second coordinate memory is supplied to the displacement amount calculation means 23. The displacement amount calculation means uses the distance measured by the sensor means at the start of the defect inspection as a reference, and uses the reference distance and the input measured distance information to determine the displacement amounts of the mask in the X and Y directions relative to the mask stage. calculate. In this case, when the mask is not displaced during the inspection, a zero displacement amount is output, and when the mask is displaced during the inspection, the displacement amounts in the X direction and the Y direction from the initially set position are output.

The displacement amounts in the X direction and Y direction output from the displacement amount calculation means 23 are supplied to the correction means 24. The defect position information output from the laser interferometer and stored in the first coordinate memory is also input to the correction unit 24. The correcting unit 24 corrects the position information output from the laser interferometer by using the displacement amount output from the displacement amount calculating unit 24, and outputs it as defect coordinate information.

Next, the defect coordinate output procedure will be described. A photomask 8 to be inspected is placed on the mask stage 6. Next, the optical axis of the inspection optical system is positioned on a reference mark formed on the photomask, and the origin of the laser interferometer is set as the reference mark. When the optical axis of the inspection optical system is positioned on the reference mark, the distance to the mask side surface measured by the three sensor units 11a to 11c is stored in the displacement amount calculating unit 23 as a reference distance. Subsequently, defect inspection is started. When the inspection optical system detects a defect, a defect detection signal is input to the first and second coordinate memories 21 and 22, and the coordinate information output from the laser interferometers 12a to 12c at the time when the inspection optical system detects the defect. Is temporarily stored in the first coordinate memory 21, and the distance information output from the first to third sensor units 11 a to 11 c is temporarily stored in the second coordinate memory 22. The defect coordinate information stored in the first coordinate memory is supplied to the correction means 24. Further, the distance information at the time of defect detection stored in the second coordinate memory 22 is supplied to the displacement amount calculation means 23, and the displacement amount from the reference distance is calculated. The calculated displacement amount is supplied to the correction unit 24, and the defect coordinate information output from the laser interferometer is corrected using the displacement amount output from the displacement amount calculation unit, and defect coordinates are output.

Next, a displacement amount calculation method of the displacement amount calculation means will be described. FIG. 3 is a diagram for explaining a displacement amount calculating method in the displacement amount calculating means. Referring to FIG. 3, the optical axis of the inspection optical system is set at the position of the reference mark, and a virtual mask (shown by a one-dot chain line) indicated by reference signs A0 to D0 is virtually initialized at that position. The intersection of the laser beam of the laser interferometer for the X direction and the laser beam of the laser interferometer for the Y direction exists at the center of the virtual mask, and is common to the laser interferometer with the intersection of the beams of the laser interferometer as the origin. The mask coordinates defined by the X direction and the Y direction are set. Then, the displacement amount of the mask is calculated using the distance information measured by the sensor means. The mask is displaced during the operation, and the virtual masks A0 to D0 (indicated by the alternate long and short dash lines) are moved and rotated relative to the positions indicated by the symbols A1 to D1 (indicated by the solid lines), and are translated in the X and Y directions. The shift amount is obtained and the position information by the laser interferometer is corrected. In addition, the displacement amount calculated | required from the distance detected by each sensor means is demonstrated as a displaced position when the virtual mask is used as a reference. A detection distance when the first and second sensor means 11a and 11b for detecting a position in the X direction are initially set is displayed as X1 (0) and X2 (0), and a displacement in the Y direction is measured. The detection position when the position detection sensor is initially set is indicated by Y (0). Further, the detection positions of the first and second position detection sensors 11a and 11b after the relative movement rotation are displayed as X1 (1) and X2 (1), and the detection after the relative movement rotation of the third position detection sensor 11c is performed. The position is displayed as Y (1). It is assumed that the distance between the first position detection sensor and the second position detection sensor is known. In this example, the displacement of the mask includes rotational movement and translational movement. In FIG. 3, the virtual mask is indicated by a one-dot chain line, the mask after displacement is indicated by a solid line, and the mask that is virtually rotated by an angle θ is indicated by a broken line. Note that the detection positions of the three position detection sensors at the initial setting are stored as reference position information.

First, it is assumed that the angle θ is rotated by the displacement of the mask, and the rotation angle θ is obtained. The rotation angle θ is obtained from the relative angle between the line segments A0-B0 and A1-B1, and the coordinates X1 (0) and X2 (0) at the initial setting and the coordinates X1 (1) and X2 (1) after the displacement are set. And using

Next, the coordinates (XP, YP) of the rotation center P are obtained. The coordinates of the rotation center P are the intersections of the extension of the line segment A0-B0 and the extension of A1-B1, and the coordinates X1 (0) and X2 (0) at the initial setting and the coordinates X1 (1) after displacement and It calculates using X2 (1).

Next, translation shift amounts in the X direction and the Y direction are calculated. Assuming that the virtual masks A0 to D0 rotate only around the rotation center P and rotate to the state positions (A2 to D2) indicated by the broken lines, the positions A0 to D0 are the positions of the mask indicated by the broken lines. It will move to A2-D2. From the information of the first and second position detection sensors that detect the position in the X direction, the side A0-B0 of the virtual mask exists at an arbitrary position along the line segment A1-B1. Here, the position of the virtual mask after moving and rotating can be uniquely determined by using the position information of the third position detection sensor that measures the Y-direction coordinates.

Assuming that the measurement point of the third position detection sensor is E, assuming that the virtual mask does not translate and only rotates around the rotation center P, the sides A0-D0 of the virtual mask are displaced to sides A2-D2. . In this case, the detection position of the third position detection sensor is E (2). However, in actual measurement, the third position detection sensor detects the coordinates of E (1), and inconsistency occurs with the actual detection coordinates. This misalignment is due to translation in the X and Y directions. Therefore, the virtual mask indicated by A2 to D2 is calculated by referring to the measurement coordinate Y (1) in the Y direction by calculating the translation amount in the X direction and the Y direction in which the virtual mask indicated by A1 to D1 matches the virtual mask indicated by A1 to D1. The amount of movement rotation is uniquely determined. By the above operation, the coordinates of the rotation center P, the rotation amount θ, and the translation shift amounts ΔX and ΔY can be obtained.

Finally, the final correction coordinates are calculated. Since the initially set relative movement rotation of the virtual mask is obtained from the change amounts of the first to third sensors generated by the actual mask movement, the virtual mask relative movement rotation amount and the actual mask relative movement rotation amount are obtained. Are consistent. Therefore, translational shift amounts ΔX and ΔY and θ rotation correction around P are performed on the coordinates measured by the laser interferometer, and the final correction coordinates of the defect detection coordinates are obtained.

In the above-described embodiment, two position detection sensors are used to measure the displacement in the X direction, and one position detection sensor is used to measure the displacement in the Y direction. The measurement value of the laser interferometer can be corrected using one position detection sensor to measure and one position detection sensor to measure the displacement amount in the Y direction. In this case, the coordinate information measured at the time of initial setting is used as the reference coordinate, the displacement amount in the X and Y directions with respect to the reference coordinate is obtained, and the obtained displacement amount is used as the translation shift amount.

Further, regarding the position detection sensor, it is possible to use two position detection sensors for detecting the position in the X direction of the mask and two position detection sensors for detecting the position in the Y direction. In this case, various measurements such as measurement of the parallelism of the bar mirror can be performed.

The present invention is not limited to the above-described embodiments, and various modifications and changes can be made. For example, in the above-described embodiment, an optical fiber sensor is used as a position detecting means for detecting the position of the mask. However, by projecting a measurement beam toward the object to be measured and receiving reflected light from the object to be measured. Various optical sensors or displacement meters that perform position detection or distance measurement can be used.

1 Surface plate 2 X direction linear motion guide 3 X stage 4 X motor 5a, 5b Y direction linear motion guide
6 Mask stage (Y stage)
7 Y motor 8 Photomask 9a-9c Support pad
10a 1st bar mirror 10b 2nd bar mirror 11a-11c Sensor means 12a-12c Laser interferometer 13 Signal processing apparatus

Claims (9)

A mask stage for supporting various masks,
A mask table on which the mask is placed;
A mask support means fixed to the mask table and on which the mask is placed;
First and second bar mirrors fixed to a mask table and interlocked with a laser interferometer or laser length measuring device, wherein the first bar mirror extends in a first direction and the second bar mirror is a first bar mirror. First and second bar mirrors extending in a second direction orthogonal to the direction;
Fixed to the first bar mirror, two or more sensor means for detecting the distance to the mask in the second direction or the displacement of the mask in the second direction, and fixed to the second bar mirror And one or more sensor means for detecting a distance to the mask in the first direction or a displacement of the mask in the first direction,
The sensor means projects a light beam toward the side surface of the mask supported on the mask table, receives reflected light reflected by the side surface of the mask,
A mask stage , wherein the translational movement of the mask is measured using an output signal from the sensor means . 2. The mask stage according to claim 1, wherein first and second sensor means are fixed to the first bar mirror so as to be separated from each other in the first direction, and a third bar mirror has a third bar. A mask stage , wherein a sensor means is fixed, and a translational movement amount of the mask is measured using output signals from the first to third sensor means . 3. The mask stage according to claim 1, wherein a side surface of the mask is configured as a reflective surface, and the sensor means receives a reflected beam reflected by the side surface of the mask. The mask stage according to claim 1, 2, or 3, wherein the mask support means is composed of a plurality of support pads fixed on the mask table and on which the mask is placed.
The mask stage is supported by gravity acting from the mask toward the support pad and frictional force acting between the back surface of the mask and the front surface of the support pad.   5. The mask table according to claim 4, wherein the mask support means includes first to third support pads, and the first and second support pads are arranged in alignment along the first direction. The support pad is arranged on an axis that is orthogonal to an axis connecting the first support pad and the second support pad and passes through an intermediate point between the first support pad and the second support pad. Mask stage to do.   6. The mask stage according to claim 4, wherein the support pad is made of an elastically deformable resin material having a large friction coefficient. A stage device that supports the mask and drives the supported mask in the X direction and the Y direction perpendicular to the X direction,
An X stage coupled to guide means extending in the X direction;
A mask stage provided on the X stage and connected to guide means extending in the Y direction and having mask support means for supporting the mask ;
First driving means for moving the X stage along the X direction and second driving means for driving the mask stage in the Y direction;
First and second laser interferometers or laser length measuring devices for detecting the positions of the mask stage in the X direction and Y direction, respectively;
First and second bar mirrors fixed on the mask stage and interlocked with the laser interferometer or laser length measuring machine , wherein the first bar mirror extends in the X direction and the second bar mirror is in the Y direction. First and second bar mirrors extending to
Two or more sensor means fixed to the first bar mirror and measuring the distance to the Y-direction mask or the displacement amount of the Y-direction mask, and to the X-direction mask fixed to the second bar mirror One or more sensor means for measuring a distance or a displacement of the mask in the X direction ;
Signal processing for inputting position information of the mask stage output from the first and second laser interferometers or laser length measuring instruments and distance information or displacement information output from the sensor means, and outputting coordinate information of the mask Having a device ,
The sensor means projects a light beam toward the side surface of the mask, receives reflected light reflected by the side surface of the mask ,
The signal processing apparatus has means for calculating a translational movement amount of the mask using an output signal from the sensor means . 8. The stage device according to claim 7, wherein the signal processing device corrects coordinate information output from the laser interferometer or laser length measuring device and indicating the position of the mask stage using the calculated translational movement amount. Having means,
The stage device characterized in that the signal processing device outputs coordinate information in which the displacement of the mask during the operation of the stage device is corrected . The stage apparatus according to claim 7 or 8, wherein the mask support means is constituted by a plurality of support pads fixed on the mask stage and on which the mask is placed.
The stage apparatus is characterized in that the mask is supported by gravity acting from the mask toward the support pad and a frictional force acting between the back surface of the mask and the front surface of the support pad.

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