JP2000349043A - Precise focusing method for rectangular beam - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a focusing method by which a machining optical system can be focused easily and extremely precisely on a work. SOLUTION: In a precise focusing method, three points on a work W are moved to the measuring point of a noncontact displacement gauge 70, and the height values of the three points are measured. Then a tilting device 42 adjusts the tilting angles θX and θY of the work W, so that the heights of the three points become the same value. Then the work W is appropriately moved in the X-Y plane by means of a translation device 44, and the heights values of the three points are re-measured. When the height value measurement and tilt angle adjustment are repeated, the height measurement errors due to the tilt of the work W can be reduced gradually. When the measured height values of the three points finally agree with each other, both the tilt angles θX and θY become zero (Χ=0 and θY=0), and the state with zero inclination of the work W results. In this state, measured height value of one of the three points becomes the height of a machining area. Lastly, a stage 30 is raised or lowered to an aimed height by operating the tilt device 42 as a Z-stage.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is applied to a laser annealing apparatus and other laser processing machines used for manufacturing a semiconductor thin film, and tilts and positions (heights) of a workpiece with respect to an irradiation optical system for irradiating processing light. The present invention relates to a focus adjustment device and method for measuring the focus adjustment.

[0002]

2. Description of the Related Art In a laser annealing apparatus, an amorphous semiconductor thin film formed on a glass substrate is crystallized by heating with a laser. In such a laser annealing apparatus,
It is necessary to irradiate a laser beam as a spot or a line onto a glass substrate which is a work, and scan the irradiated laser beam on the glass substrate. When irradiating a laser beam, it is necessary to align the annealing surface of the glass substrate with respect to the irradiation optical system for irradiating the laser beam, and to form a laser beam having a desired shape on the annealing surface.

[0003]

However, there is no conventional laser annealing apparatus which simply and extremely precisely positions the glass substrate with respect to the irradiation optical system. In other words, when performing precise annealing, particularly in an application in which a mask image illuminated by a laser beam is reduced and projected on an annealing surface on a glass substrate, the focal depth of the laser beam becomes extremely shallow, for example, ± 3 μm or less. There is no method for simply adjusting the height and inclination of the glass substrate with respect to the irradiation optical system so that the annealed surface is within the focal depth of the laser beam with this accuracy.

There are the following general methods for measuring and adjusting the height and inclination of a work in a processing apparatus.

For example, there is a method in which a mark image patterned on a work surface through an optical axis of a processing optical system is captured, and precise displacement measurement is performed from the focused state. In this method, a mark is always required on the workpiece, a mechanism for putting the mark into the camera field is required, and special processing optical systems such as the irradiation optical system built into the laser annealing device are imaged through this. The applicable range is narrow, such as difficulty in measuring

There is also a method in which an interference image of a special mark patterned on a work surface is detected obliquely while avoiding the processing optical system, and precise displacement measurement is performed from that position.
In this method, special marks are always required on the workpiece, a machine that puts the marks into the camera field is required, the alignment of the optical axis is severe, and the shape of the special marks changes due to the temperature rise of the workpiece The applicable range is narrow, such as inability to measure.

There is also a method for directly and precisely measuring the displacement of a workpiece using a capacitance sensor or the like. In this method, measurement is not possible for a work such as a glass substrate because the work is limited to a conductive work.

In the focusing system, it is necessary to make the optical axis of the processing light coincide with the optical axis of the measuring laser light, and the measurement optical system and the processing optical system must be formed on the same optical axis. For this reason, a special focusing optical system such as an irradiation optical system of a laser annealing apparatus cannot incorporate a focusing measurement system.

In view of the above, the present invention provides a focus adjusting device and a method capable of extremely precisely positioning a workpiece with respect to a processing optical system by a simple technique in a laser processing machine such as a laser annealing apparatus. With the goal.

[0010]

In order to solve the above-mentioned problems, a focus adjusting apparatus according to the present invention is provided with an irradiation optical system for irradiating a workpiece with a processing light in a predetermined state, and a workpiece mounting body. And a stage device for adjusting the position and inclination of the workpiece with respect to the irradiation optical system, a light projecting means for projecting inspection light with a flat area on the workpiece as a measurement target, and a positive light from the measurement target. Non-contact light receiving means for receiving reflected light and outputting information on the incident position of the regular reflected light, and conversion means for obtaining a measurement value including information corresponding to the height of the measurement target based on the information on the incident position The displacement meter and 3 which are arranged on the workpiece and are in the same plane
A control device that drives a stage device based on measurement values of two or more different measurement targets measured by a non-contact displacement meter to adjust a tilt and a position (height) of the workpiece.

In the above-described apparatus, the control device drives the stage device based on the measurement values of three or more different measurement targets located on the workpiece and located in the same plane and measured by the non-contact displacement meter. Since the inclination of the work is adjusted,
Information on the inclination of the workpiece can be obtained as the inclination of the surface corresponding to the three measurement targets, and the workpiece can be aligned with the irradiation optical system while correcting the inclination of the workpiece. At this time, since a flat region on the workpiece is used as the measurement target, it is not necessary to provide a mark on the workpiece, and as a result, the search for the mark becomes unnecessary. Also, since measurement is not performed through the irradiation optical system,
Even if the irradiation optical system is special, focus detection can be performed easily and independently of the processing operation.

In a preferred embodiment of the above apparatus, the control device drives the stage device so that the measured values at three or more points measured by the non-contact displacement meter become equal, and the inclination and the position (high) of the workpiece are adjusted. Adjust).

In the above apparatus, the control device drives the stage device to adjust the inclination of the workpiece so that three or more measured values measured by the non-contact displacement meter become equal.
The workpiece can be simply and quickly aligned with the irradiation optical system.

According to the focus adjusting method of the present invention, inspection light is incident on a measurement target to receive specularly reflected light from the measurement target, and the height of the measurement target is adjusted based on information on the incident position of the specularly reflected light. Measurement of three or more different flat areas in the same plane on a workpiece placed at a processing light irradiation position by a stage device as a measurement target by a non-contact displacement meter that obtains measurement values including information. The inclination and the position (height) of the workpiece are adjusted by driving the stage device based on the values.

[0015] In the above method, the stage device is driven by driving the stage device based on measurement values obtained by measuring three or more different flat regions in the same plane on the workpiece with the non-contact displacement meter as the measurement target. Since the tilt of the body is adjusted, the workpiece can be aligned with the irradiation optical system while correcting the tilt of the workpiece. At this time, since a flat region on the workpiece is used as the measurement target, it is not necessary to provide a mark on the workpiece, and as a result, the search for the mark becomes unnecessary. Further, since measurement is not performed through processing means such as an irradiation optical system, even if the irradiation optical system is special, focus detection can be performed easily and independently of the processing operation.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a focus adjusting device and a focus adjusting method according to an embodiment of the present invention will be specifically described with reference to the drawings.

FIG. 1 is a view for explaining the overall structure of a laser annealing apparatus incorporating the focus adjusting device of the embodiment. This laser annealing apparatus is used for heat-treating a workpiece W, which is a workpiece having a semiconductor thin film such as amorphous Si formed on a glass plate, and an excimer laser or another laser beam AL for heating the semiconductor thin film. A laser light source 10 for generating a laser beam AL, an irradiation optical system 20 which is a processing optical system for making the laser beam AL linear or spot-like and incident on the work W at a predetermined illuminance, and a work W
And a stage 30 on which the workpiece W can be smoothly moved in the XY plane and tiltable around the X-axis and the Y-axis, and the stage 30 on which the workpiece W is mounted can be moved with respect to the irradiation optical system 20 and the like. The apparatus includes a stage driving device 40 which is a driving means for moving or tilting by a required amount, and a main control device 80 for controlling the operation of each part of the laser annealing apparatus. Here, the stage 30 and the stage driving device 40 constitute a stage device and are housed in a chamber 90 for reducing the pressure around the work W and adjusting the atmosphere. This chamber 90 is installed on the floor via a vibration isolator 92.

Further, this laser annealing apparatus detects the amount of movement of the stage 30 as optical information or electrical information in addition to the stage 30, the stage driving device 40 and the main control device 80 as a focus adjusting device. A moving amount measuring device 50, a tilt measuring device 60 for detecting the height and tilt amount of the stage 30 with respect to the stage driving device 40 as optical information and electrical information, and a height and tilt amount of the work W with respect to the irradiation optical system 20; And a non-contact displacement meter 70 for detecting a signal corresponding to

Here, the irradiation optical system 20 includes the laser light source 1.
A homogenizer 20a for making the laser beam AL incident from 0 through the mirror 15 a uniform distribution, and a homogenizer 20a
And a projection lens 20c for reducing and projecting the slit image of the mask 20b onto the workpiece W. The irradiation optical system 20 is disposed so as to face the work W via a transmission window 90a provided in the chamber 90, and is fixed to the chamber 90 by a member (not shown).

The stage driving device 40 includes a tilt device 42 for tilting the stage 30 around the X axis and the Y axis, and a translation device 44 for moving the stage 30 together with the tilt device 42 smoothly in the XY plane. . Here, the tilt device 42 includes three support members 42a that house a cylinder inside the bellows and can expand and contract to any length, and a support member driving device 42b that expands and contracts the support member 42a. By adjusting the length of these three support members 42a via the support member driving device 42b, the inclination and the distance of the stage 30 with respect to the irradiation optical system 20 can be finely adjusted as appropriate. That is, the position (distance) of the work W in the Z-axis direction with respect to the irradiation optical system 20, the tilt angle θX around the X-axis, and the tilt angle θY around the Y-axis can be adjusted. The three tilt measuring devices 60 extending from the side of the tilt device 42 directly below the stage 30 are eddy current sensors or capacitance sensors. It is now possible to accurately determine whether the vehicle is inclined to a certain degree.

FIG. 2 is a view for explaining the structure of the translation device 44. The translation device 44 is provided on a pair of Y driving devices 44a each composed of a linear motor and a linear bearing, a Y movable portion 44b which is driven by both Y driving devices 44a and moves in the Y axis direction, and a Y movable portion 44b, respectively. And a pair of X drive units 44c each comprising a linear motor and a linear bearing, and an X movable unit 44d driven by both X drive units 44a to move in the X-axis direction. X
The tilt device 42 and the stage 30 are placed on the movable portion 44d.
Is installed. The position of the Y movable portion 44b is detected by the Y axis encoder 44f, and the position of the X movable portion 44d is
It is detected by the X-axis encoder 44g. The outputs of the linear encoders 44f and 44g are monitored by the main controller 80, so that the movement amounts of the stage 30 and the work W in the XY plane can be known.

Returning to FIG. 1, the non-contact displacement meter 70 is a laser displacement meter, and a light projecting unit 71 as a light projecting unit for projecting the inspection light DL with a flat area on the workpiece W as a measurement target T. And a light receiving unit 72 that is a light receiving unit that receives the regular reflection light RL from the measurement target T and outputs information on the incident position of the regular reflection light RL. The light projecting unit 71 and the light receiving unit 72 are arranged to face each other with the irradiation optical system 20 interposed therebetween. That is, the light projecting unit 71 emits the inspection light DL in a direction inclined by a predetermined angle with respect to the optical axis of the irradiation optical system 20, and the light receiving unit 72 performs inspection with respect to the optical axis of the irradiation optical system 20. The reflected light RL that travels in the direction opposite to the light DL in the direction inclined by the predetermined angle is incident. Note that the main controller 8
0 also functions as a conversion unit that obtains a measurement value including information corresponding to the height of the measurement target T based on the information on the incident position detected by the light receiving unit 72.
0.

Here, the light projecting section 71 includes a light source for generating inspection light and a light projection optical system, and applies a spot-like beam of the inspection light DL to the measurement target T on the work W through the transmission window 90a. Make it incident. On the other hand, the light receiving unit 72 includes an imaging optical system that condenses the reflected light RL from the measurement target T and a line sensor that receives the condensed reflected light RL.
The line sensor extends in a direction perpendicular to the optical axis of the reflected light RL in the XZ plane, and utilizes the fact that the height position of the work W has a linear relationship with the position detection signal from the line sensor. To detect a change in the height position of the work W. However,
When the work W is inclined with respect to the optical axis of the irradiation optical system 20, the output of the non-contact displacement meter 70 reflects not only the height position of the work W but also the inclination of the work W. Therefore, as will be described later in detail, the tilt device 42 is configured by using the tilt device 42 and once the inclination of the work W is corrected and the normal line of the work W becomes parallel to the optical axis of the irradiation optical system 20. The distance between the workpiece W and the irradiation optical system 20 is adjusted by expanding and contracting the three supporting members 42a to be the same amount.

FIG. 3 is a diagram for explaining an example of the arrangement of the measurement targets T on the work W. As is clear from the figure, the measurement targets T1, T2, and T3 are arranged at the positions of the vertices of an equilateral triangle, and are each equidistant from the processing area on the work W (the center of the work W in the figure). Is set to Under the control of the translation device 44, the inspection light DL from the light projecting unit 71 is transmitted to each measurement target T1,
Light can be sequentially incident on T2 and T3. When correcting the inclination of the work W, each measurement target T1, T2, T3
The tilt device 42 is operated so as to average the output of the light receiving unit 72 at the time of. In addition, each measurement target T1, T
2. The arrangement and number of T3 can be appropriately changed according to the required accuracy and the like. In particular, when there is deformation such as warpage on the surface of the work W, 3
It is necessary to select one or more measurement targets again.
Further, the measurement targets T1, T2, T3 described above
It is not necessary to form a specific mark as long as it is sufficient to simply form a flat surface and form regular reflection light.

Hereinafter, the operation of the laser annealing apparatus of the present embodiment will be described. First, the work W is transported and placed on the stage 30 of the laser annealing apparatus. Next, the work W on the stage 30 is aligned with the irradiation optical system 20 that guides the annealing laser beam AL. next,
While moving the mask 20b of the irradiation optical system 20 or appropriately moving the stage 30 with respect to the irradiation optical system 20, the laser light AL from the laser light source 10 is incident on the work W in a line shape or a spot shape. . A thin film of an amorphous semiconductor such as amorphous Si is formed on the work W, and a desired region of the semiconductor is annealed and recrystallized by the irradiation and scanning of the laser beam AL, so that the semiconductor thin film has excellent electric characteristics. Can be provided.

The operation of aligning the height and inclination of the work W on the stage 30 with respect to the irradiation optical system 20 will be described in more detail. First, three vertices of a regular triangle centered on the processing area are defined as measurement targets T1, T2, and T3. The work W is appropriately moved in the XY plane by the control of the translation device 44, and each measurement target T1,
T2 and T3 are sequentially moved to the measurement points of the non-contact displacement meter 70,
The inspection light DL from the light projecting unit 71 is applied to each measurement target T1,
The light is incident on T2 and T3. Each measurement target T1, T2, T
The reflected light RL from 3 is converted by the light receiving unit 72 into a signal corresponding to the incident position. In main controller 80, light receiving section 72
The measurement values relating to the heights of the respective measurement targets T1, T2, T3 are obtained based on the signal relating to the incident position from. 3 points T
Regarding the measurement results of T1, T2, and T3, it is considered that errors due to the inclination are included in all of them. However, ignoring them here, the heights of the three points T1, T2, and T3 have the same value. Tilt angle θX, θY of the work W by the tilting device 42
To adjust. Again, the work W is moved by the translation device 44 to X
The measurement target is moved as needed in the Y plane, and a measurement value regarding the height of each of the measurement targets T1, T2, and T3 on the work W is obtained. By repeating the height measurement of the three points T1, T2, and T3 and the adjustment of the tilt angle in this manner, the error of the height measurement due to the inclination gradually decreases. Finally three points T1, T2, T
In a state where the measured values of 3 coincide with each other, θX = 0 and θY = 0, resulting in a state where the inclination is 0. The height measurement value at any one point at this time is the height of the processing area on the work W. Finally, the tilt device 42 is operated as a Z stage, and the stage 30, that is, the work W, is moved up and down until the target height is reached.

Although the present invention has been described with reference to the embodiment, the present invention is not limited to the above embodiment. For example, three or more non-contact displacement meters 70 can be provided. In this case, different non-contact displacement meters 70 can simultaneously measure different 3 on the work W. Thereby, the inclination of the work W can be quickly corrected without moving the work W by the translation device 44.

In the above embodiment, the tilt device 42
Is operated as the Z stage, but the Z stage can be provided independently to perform the tilt adjustment and the height adjustment of the work W completely separately.

In the above embodiment, the work W is formed by forming a semiconductor thin film on a glass substrate. However, the work W may be made of any material as long as it can obtain regular reflection light.

In addition, the above-mentioned focus adjusting device uses the laser light A
Although incorporated into a laser annealing apparatus that anneals the semiconductor layer on the work W using L, if the structures of the laser light source 10 and the irradiation optical system 20 are appropriately changed, not only annealing of the semiconductor material but also modification of various materials, A pulse laser processing apparatus or the like that enables cutting, welding, and the like can also be used.

[0031]

As is apparent from the above description, according to the focus adjusting apparatus of the present invention, the control device is arranged on the workpiece to control three or more different measurement targets in the same plane. Since the inclination of the workpiece is adjusted by driving the stage device based on the measurement value measured by the contact displacement meter, the workpiece is aligned with the irradiation optical system while correcting the inclination of the workpiece. Can be. At this time, since a flat area on the workpiece is used as a measurement target,
There is no need to provide a mark on the workpiece, and consequently no mark search is required. Further, since measurement is not performed through the irradiation optical system, focus detection can be easily performed even if the irradiation optical system is special.

Further, according to the focus adjusting apparatus of the present invention, based on measurement values obtained by measuring three or more different flat areas in the same plane on the workpiece by the non-contact displacement meter as measurement targets. Since the tilt of the workpiece is adjusted by driving the stage device, the workpiece can be aligned with the irradiation optical system while correcting the tilt of the workpiece. At this time, since a flat region on the workpiece is used as the measurement target, it is not necessary to provide a mark on the workpiece, and as a result, the search for the mark becomes unnecessary.
Further, since measurement is not performed through processing means such as an irradiation optical system, even if the irradiation optical system is special, focus detection can be performed easily and independently of the processing operation.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a laser annealing apparatus incorporating a focus adjusting device according to an embodiment.

FIG. 2 is a diagram illustrating a stage driving mechanism of the apparatus of FIG.

FIG. 3 is a diagram illustrating an example of arrangement of measurement targets on a workpiece.

[Explanation of symbols]

 Reference Signs List 10 laser light source 20 irradiation optical system 30 stage 40 stage drive device 42 tilt device 44 translation device 50 movement amount measurement device 60 inclination measurement device 70 non-contact displacement meter 71 light projecting unit 72 light receiving unit 80 main control device 90 chamber DL inspection light RL Reflected light T Measurement target W Work θX, θY Tilt angle

Claims (3)

[Claims] 1. An irradiation optical system for irradiating a processing light to a processing object in a predetermined state, and a position and an inclination of the processing object with respect to the irradiation optical system while mounting the processing object. A stage device for adjusting the distance, a light projecting unit for projecting inspection light with a flat area on the workpiece as a measurement target, and information on an incident position of the regular reflection light upon receiving regular reflection light from the measurement target. A non-contact displacement meter, comprising: a light receiving unit that outputs a measured value; and a conversion unit that obtains a measurement value including information corresponding to the height of the measurement target based on the information on the incident position. A control device for adjusting the inclination and position of the workpiece by driving the stage device based on the measurement values measured by the non-contact displacement meter on three or more different measurement targets in the same plane. Focusing device comprising: 2. The control device drives the stage device to adjust the inclination and the position of the workpiece so that the measured values at three or more points measured by the non-contact displacement meter become equal. The focus adjusting device according to claim 1, wherein: 3. A measurement including making inspection light incident on a measurement target to receive specularly reflected light from the measurement target, and including information corresponding to a height of the measurement target based on information on an incident position of the specularly reflected light. By the non-contact displacement meter that obtains a value, a measurement value obtained by measuring three or more different flat areas in the same plane on the workpiece placed at the irradiation position of the processing light by the stage device as the measurement target A focus adjustment method for adjusting the tilt and the position of the workpiece by driving the stage device based on the information.