JPH09101473A - Method and device for removing vibration from scanning device utilizing electrostrictive element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To remove vibration from the base of a mirror stage. SOLUTION: A base 30 where a mirror stage 6a is installed, is provided with a piezoelectric scanner 26 for vibration removal. The mass of the piezoelectric scanner 26 is equal to the sum of the mass of the mirror stage 6a and the mass of a mirror 7 mounted on the stage 6a. The piezoelectric scanner 26 is vibrated in opposite phase to the mirror stage 6a. Consequently, the vibration that the mirror stage 6a gives to the base 30 and further peripheral equipment such as an objective 10 is removed. Consequently, a pattern position measuring instrument can accurately measure the position and line width of a pattern.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vibration isolation method for a scanning device using an electrostrictive element, a vibration isolation device, and a pattern position measuring device with a vibration isolation device.

[0002]

2. Description of the Related Art Conventionally, various devices for measuring the position of an IC pattern formed on a mask or a semiconductor wafer have been proposed (for example, JP-A-61-233312). In such an apparatus, a sample to be measured such as a mask and a reticle is placed on an XY stage, the mounted sample to be measured is irradiated with a laser beam, and the laser beam is scanned to scan the light beam. The detector detects scattered light and reflected light, and also detects the amount of movement of the XY stage to measure the position and line width of the pattern.

A pattern position measuring apparatus for measuring the position of such a pattern measures a laser light source for emitting a laser beam, an XY stage on which a sample to be measured is placed, and a laser beam emitted from the laser light source to be measured. An optical system that guides the sample and a mirror stage that vibrates by an electrostrictive element to which a frequency voltage is applied and that holds a mirror that is a part of the optical system are provided. Here, a piezo scanner is composed of a mirror and a mirror stage. Then, the piezo scanner is vibrated to scan the laser beam on the sample to be measured, whereby the scattered light from the sample to be measured placed on the XY stage is detected by the detector and the position of the pattern on the sample or Measure the line width. With such a piezo scanner, the laser beam can scan the sample to be measured minutely and precisely, so that the pattern of the sample to be measured can be accurately measured. It is also possible to construct a biaxial scanner that vibrates the laser beam in the X and Y directions by stacking the piezoelectric scanners so that they vibrate in directions orthogonal to each other.

[0004]

If the weight of the mirror stage is m1, the mass of the mirror mounted on the mirror stage is m2, and the moving speed of the mirror stage driven by a predetermined frequency is v, the piezo scanner will be described. Has a momentum of (m1 + m2) v.

However, the XY stage, the optical system, and other peripheral devices vibrate due to the momentum due to the vibration of the piezo scanner. Therefore, the measurement accuracy is lowered, and the pattern of the sample to be measured cannot be accurately measured.

An object of the present invention is to prevent the vibration generated by the scanning device from affecting the peripheral equipment and improve the measurement accuracy.

[0007]

[Means for Solving the Problems]

Description will be made in association with FIG. 1 and FIG. 2 showing an embodiment. According to a first aspect of the present invention, there is provided a method of deviating a scanning device 6 having a stage 6a which vibrates in a predetermined direction at a frequency dependent on a frequency voltage applied to an electrostrictive element.
It is characterized in that the vibrating body 26 having a mass approximately equal to the sum of the mass of a and the mass 7 of the stage is vibrated in a phase opposite to that of the stage 6a to vibrate the base 30 on which the stage 6a is installed. . In the vibration isolator of the scanning device 6 having the stage 6a vibrating in a predetermined direction at a frequency depending on the frequency voltage applied to the electrostrictive element, the invention of claim 2 is provided on the base 30 on which the stage 6a is installed. In addition, a vibrating body 26 having a mass approximately equal to the sum of the mass of the stage 6a and the mass of the mounted object 7 of the stage 6a and vibrating in a phase opposite to that of the stage 6a is provided. According to the invention of claim 3, the XY stage 20 on which the measured sample 21 is placed, the position detector 18 for detecting the position of the XY stage 20, and the optical system 3 for guiding the laser beam 2 onto the measured sample 21. , 4, 5, 7, 8, 9, 10 and the sample to be measured 2
A detector 15 for detecting the reflected light from the mirror 1, and a mirror stage 6a for holding a mirror 7 that vibrates in a predetermined direction at a frequency depending on the frequency voltage applied to the electrostrictive element and holds a mirror 7 that constitutes a part of an optical system. Is provided on the base 30 on which the mirror stage 6a is installed, has a mass approximately equal to the sum of the mass of the mirror stage 6a and the mass of the mirror 7, and includes a vibrating body 26 that vibrates in an opposite phase to the mirror stage 6a. It is characterized by being provided.

Vibration having a phase opposite to that of the vibrating stage 6a is applied to the base 30 by the vibrating body 26. The vibration of the base 30 due to the vibration of the stage 6a is canceled by the vibration of the vibrating body 26. As a result, vibration that adversely affects the peripheral devices 1, 3, 4, 5, 8, 10 installed on the base 30 on which the mirror stage 6a is installed, or on the base integrated with the base 30. Can be reduced.

In the section of the means for solving the above problems for explaining the structure of the present invention, the drawings of the embodiments are used for the sake of easy understanding of the present invention. It is not limited to.

[0010]

1 is a diagram showing a pattern position measuring device to which a vibration isolator according to the present invention is applied. As shown in FIG. 1, the pattern position measuring device includes a laser light source 1, a mirror stage 6a installed on a base 30 and vibrating, a half mirror 3, a reflecting mirror 4, 9, a beam expander 5, and a beam expander 5.
8, an optical system including a reflecting mirror 7 and an objective lens 10 mounted on a mirror stage 6a, a stage 20 for mounting a wafer 21 as a sample to be measured, and a laser beam 2'reflected by the sample to be measured. Detector 15 for detecting
Consists of Such a pattern position measuring apparatus collects light on a minute spot 11 on a sample to be measured on which a pattern with a minute line width such as a semiconductor wafer 21 is formed on a stage 20 capable of precisely measuring the position. The laser beam 2 is emitted, the laser beam 2 is scanned on the wafer 21 and the scattered light or reflected light 2 ′ of the light is detected by the detector 15, so that the wafer 21
The line width dimension and position of the pattern 22 are accurately measured.

The procedure for detecting the pattern position by the pattern position measuring device will be described in more detail. The laser beam 2 emitted from the laser light source 1 is reflected by the half mirror 3 and the first reflecting mirror 4, and further, the beam width thereof is widened by the first beam expander 5, and the laser beam 2 is provided in the piezo scanner 6. It is incident on the reflecting mirror 7. The piezo scanner 6 vibrates at a frequency when a voltage of a predetermined frequency is applied to the electrostrictive element from a control circuit (not shown),
It is composed of a mirror stage 6a and a reflecting mirror 7. The piezo scanner 6 is attached to the base 30 of the apparatus. The laser beam 2 reflected by the reflecting mirror 7 is
The light is transmitted through the second beam expander 8 to be collimated light. The laser beam 2 made into parallel light is transmitted to the second reflecting mirror 9
The light beam is reflected by and is incident on the objective lens 10 to form a minute beam spot 11 which is focused on a pattern 22 formed on the semiconductor wafer 21 mounted on the stage 20.

At this time, since the piezo scanner 6 reciprocates in the direction of arrow A at a predetermined frequency, the minute beam spot 11 focused on the pattern 22 reciprocates in the direction of arrow B on the pattern 22, As a result, the pattern 22 is scanned by the minute beam spot 11.

The minute beam spot 11 focused on the pattern 22 changes the intensity of the reflected light 2'scattered by the edges of the pattern 22 and reflected by the pattern 22. The reflected light 2 ′ whose intensity is changed by the edge of the pattern 22 in this way passes through the objective lens 10,
It is reflected by the second reflecting mirror 9, further passes through the beam expander 8, is reflected by the reflecting mirror 7 provided in the piezo scanner 6, and is further converted into parallel light by the beam expander 5. Reflected by 4. The laser beam 2 ′ reflected by the first reflecting mirror 4 passes through the half mirror 3 and is detected by the detector 15.

On the other hand, the movement of the piezo scanner 6 depends on the interferometer 1
The position where the piezo scanner 6 is vibrating is accurately read. Thus, the scanning position of the minute beam spot 11 scanned by the vibration of the piezo scanner 6 can be accurately grasped. The position of the stage 20 is also measured by the interferometer 18, and the position of the stage 20 can be accurately read by the interferometer 18. Then, the accurate line width and position of the pattern 22 can be measured based on the information about the edge of the pattern 22 detected by the detector 15, the position information of the piezo scanner 6, and the position information of the stage 20.

In such a measuring apparatus, the mechanical vibration generated by the piezo scanner 6 scanning the laser beam 2 causes the objective lens 10, the reflecting mirrors 4, 9,
Also, peripheral devices such as the beam expanders 5 and 8 or the XY stage 20 are vibrated, which adversely affects the accuracy in pattern measurement. That is, when the peripheral device such as the objective lens 10 vibrates due to the vibration of the piezo scanner 6, the image forming position of the minute beam spot 11 shifts, so that the position and the line width of the pattern 22 cannot be accurately measured. .

Therefore, in this embodiment, as shown in detail in FIG. 2, a vibration isolation piezo scanner 26 having the same mass as that of the piezo scanner 6 is provided on the back surface of the base 30 on which the piezo scanner 6 is provided. , This vibration isolation piezo scanner 2
6 is vibrated in a phase opposite to that of the piezo scanner 6. That is, as shown in FIG. 1 and FIG.
When moving in the direction, the vibration isolation piezo scanner 26 is moved in the direction D. The mass of the vibration isolation piezo scanner 26 is equal to the sum of the mass of the mirror stage 6 a and the mass of the mirror 7 which compose the piezo scanner 6.

In such a vibration isolator, two vibrating bodies having the same momentum always vibrate in opposite phases, and the vibration given to the base 30 by the piezo scanner 6 vibrates in the opposite phase of the vibration isolating piezo scanner 26. Therefore, the vibration of the base 30 is damped. As a result, vibrations that adversely affect peripheral devices other than the piezo scanner 6 are eliminated, so that the position and line width of the pattern can be accurately measured.

In the above-described embodiment, the vibration isolation piezo scanner 26 is installed on the base 30 so as to face the back surface of the piezo scanner 6, but as shown in FIG. The piezo scanners 6 may be arranged on the base 30 side by side in the vertical direction. Further, the vibration isolation piezo scanner 26 and the piezo scanner 6 may be arranged side by side. Further, although the case where the vibration isolation method and the vibration isolation device according to the present invention are applied to the pattern position measurement device has been described above, the vibration isolation device for various scanning devices that applies a frequency voltage to the electrostrictive element to scan the stage. Applicable to

In the correspondence between the embodiment of the invention and the claims, the vibration isolation piezo scanner 26 uses the vibrating body as the first embodiment.
The second reflecting mirror, the beam expanders 5 and 8, the mirror 7 and the objective lens 10 form an optical system, and the interferometers 17 and 18 form a position detector. The piezo scanner 6 is a scanning device.

[0020]

As described above in detail, according to the present invention, the vibration having a phase opposite to that of the vibrating stage is generated by the vibrating body and applied to the base on which the stage is installed. The vibration applied to the base is canceled by the vibration of the vibrating body, thereby reducing the vibration that adversely affects the base on which the stage is installed or peripheral equipment provided on the base integrated with the base. You can

[Brief description of the drawings]

FIG. 1 is a diagram showing an example of a pattern position measuring device to which a vibration isolation device according to the present invention is applied.

FIG. 2 is a perspective view for explaining the arrangement of the scanning piezo scanner and the vibration isolation piezo scanner of FIG.

FIG. 3 is a perspective view showing another example of the arrangement of the scanning piezo scanner and the vibration isolation piezo scanner.

[Explanation of symbols]

 1 laser light source, 2,2 'laser beam 3 half mirror 4,9 reflecting mirror 5,8 beam expander 6 piezo scanner 6a stage 7 reflecting mirror 10 objective lens 11 small beam spot 17,18 interferometer 20 stage 21 wafer 22 wafer Pattern 26 Piezo Scanner for Vibration Isolation 30 Base

Claims (3)

[Claims] 1. A method of deviating a scanning device having a stage which vibrates in a predetermined direction at a frequency dependent on a frequency voltage applied to an electrostrictive element, the sum of the mass of the stage and the mass of a mounted object on the stage. A method of isolating a scanning device using an electrostrictive element, wherein a vibrating body having a mass substantially equal to is vibrated in a phase opposite to that of the stage to vibrate a base on which the stage is installed. 2. An anti-vibration device for a scanning device having a stage that vibrates in a predetermined direction at a frequency dependent on a frequency voltage applied to an electrostrictive element, wherein the stage is provided on a base on which the stage is installed. An anti-vibration device for a scanning device using an electrostrictive element, comprising a vibrating body having a mass substantially equal to the sum of the mass and the mass of a mounted object on the stage and vibrating in a phase opposite to that of the stage. 3. An XY stage on which a sample to be measured is mounted, a position detector for detecting the position of the XY stage, an optical system for guiding a laser beam onto the sample to be measured, and an optical system for measuring the sample from the sample to be measured. A detector that detects reflected light, a mirror stage that oscillates in a predetermined direction at a frequency that depends on the frequency voltage applied to the electrostrictive element, and that holds a mirror that forms a part of the optical system, and this mirror stage A pattern position, which is provided on a base to be installed, has a mass substantially equal to the sum of the mass of the mirror stage and the mass of the mirror, and includes a vibrating body that vibrates in an opposite phase to the mirror stage. Detection device.