JP2001351876A - Apparatus and method for laser processing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily and correctly control the energy of laser light cast on a workpiece. SOLUTION: Irradiation energy measured by a joulemeter 60 is stored as a reference in a main controller 100 is advance. When a specified amount of annealing is finished, an irradiation optical system 20 is moved from the irradiation position B to measurement positing A to measure the irradiation energy again by the joulemeter 60. The main controller 100 compares the measured value with the preliminarily stored reference value. As a result of the comparison, if there is a change in energy, the permittivity of a variable attenuator 40 is changed in response to the change to keep energy reaching the surface of a substrate W constant.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser processing apparatus and method used for laser annealing and the like.

[0002]

2. Description of the Related Art As a laser processing apparatus, for example, a glass substrate on which an amorphous Si film is formed is housed in a process chamber, and an annealing light such as an excimer laser is irradiated onto the glass substrate from outside the process chamber to form an amorphous film on the glass substrate. There is a laser annealing apparatus for polycrystallizing a Si film.

In this type of laser annealing apparatus, the transmittance of the attenuator is adjusted so that the energy of the laser beam on the irradiation surface becomes a desired value. Also, by performing feedback control in the laser oscillator, fluctuations in the energy of the laser light are prevented and the target value is maintained substantially.

[0004]

However, when laser irradiation is performed for a long time, the efficiency of the irradiation optical system changes due to a change in the spread angle of the laser light, and the energy of the laser light reaching the irradiation surface changes. . Since the Si film is very sensitive to a change in the energy of the laser light, a uniform film cannot be obtained when the energy of the laser light changes. In particular,
In recent years, more accurate and stable laser light irradiation has been demanded in the process.

Accordingly, an object of the present invention is to provide a laser processing apparatus and method capable of easily controlling the energy of a laser beam applied to a workpiece with higher accuracy.

[0006]

In order to solve the above problems, a laser processing apparatus according to the present invention comprises a light source for generating a laser beam, and an irradiation optical system for irradiating a laser beam from the light source to an irradiation position on a workpiece. A system, energy detecting means for detecting the energy of the laser light at the measurement position corresponding to the irradiation position, and control means for adjusting the energy of the laser light emitted from the irradiation optical system based on the output of the energy detecting means.

In the above apparatus, energy detecting means for detecting the energy of the laser light at the measurement position corresponding to the irradiation position, and control means for adjusting the energy of the laser light emitted from the irradiation optical system based on the output of the energy detecting means Therefore, the energy of the laser beam at the measurement position can be detected at a necessary timing, and the energy of the laser beam emitted from the irradiation optical system can be adjusted as needed. Therefore, the energy of the laser beam applied to the workpiece can be easily and precisely controlled.

In a preferred aspect of the above-mentioned apparatus, the apparatus further comprises a moving means for moving a position where the laser beam from the irradiation optical system is incident between the irradiation position and the measurement position. A slit for adjusting the beam shape of the incident laser light is provided.

The above apparatus further includes a moving means for moving the position where the laser light from the irradiation optical system is incident between the irradiation position and the measurement position, so that the energy of the laser light irradiated on the workpiece can be appropriately adjusted. It can be easily detected at a suitable timing and used for control. When the shape of the laser light is larger than the energy detecting means, precise energy detection is possible by arranging a slit in front of the energy detecting means and easily adjusting the shape of the laser light. Therefore, when the laser light is sufficiently smaller than the opening shape of the energy detecting means, the slit is unnecessary.

In some cases, it is not possible to dispose the energy detecting means in the processing container for accommodating the workpiece, for example, when the workpiece is overheated during processing. In this case, the measurement position is outside the processing container, and the laser light from the irradiation optical system is incident on the irradiation position in the processing container or the measurement position outside the processing container by the moving unit.

A laser processing method according to the present invention is a laser processing method for performing processing by irradiating a laser beam onto an irradiation position on a workpiece through an irradiation optical system, and performs laser processing at a measurement position corresponding to the irradiation position. A step of detecting the energy of the laser light; and a step of adjusting the energy of the laser light emitted from the irradiation optical system based on the detected energy.

In the above method, the energy of the laser beam emitted from the irradiation optical system can be adjusted as needed by detecting the energy of the laser beam at the measurement position at a necessary timing. Therefore, the energy of the laser beam applied to the workpiece can be easily and precisely controlled.

[0013]

FIG. 1 is a side view for explaining the structure of a laser annealing apparatus which is a laser processing apparatus according to an embodiment. This laser annealing apparatus is for heat-treating a substrate W which is a workpiece having a semiconductor thin film made of amorphous Si or the like formed on a glass substrate. An excimer laser or another laser beam AL for heating the semiconductor thin film is used. And a laser light source 10 for generating
An irradiation optical system 20 for linearly converting L into a predetermined illuminance on the substrate W, and supporting the substrate W so that the substrate W can be smoothly translated in an XY plane and can be moved in the Z-axis direction. And a process stage device 30 that can be moved up and down.

A variable attenuator 40 is disposed between the laser light source 10 and the irradiation optical system 20 to adjust the intensity of the laser light AL incident on the irradiation optical system 20.
A slit 50 is arranged at a measurement position below the irradiation optical system 20 in the illustrated state. The slit 50 is longer than the opening diameter of the energy detecting means described later because the laser beam of the annealing device is adjusted linearly, and the energy of the laser beam cannot be directly measured because the energy is higher. Use if By using the slit 50 without using a new optical system, the shape of the laser beam can be easily adjusted and incident on the energy detecting means. When the laser beam is smaller than the energy detecting means, the slit is unnecessary. At a position below the slit 50, a joule meter 60 as energy detecting means for detecting the energy of the incident laser light AL is arranged, and detects the energy of the laser light AL passing through the slit 50. The detection output of the joule meter 60 is output to an attenuator controller 70 as control means, and is used for operation control of the variable attenuator 40.

Between the laser light source 10 and the irradiation optical system 20, there are provided a plurality of mirrors M1 to M1 for adjusting the optical path of the laser beam AL.
M4 is arranged. The irradiation optical system 20 is composed of a homogenizer that makes the laser light AL from the laser light source 10 uniform and projects it on the surface of the substrate W, that is, on the irradiation position.

The process stage device 30 is housed in a process chamber 80 which is a processing container,
And a stage 31 for supporting X,
A stage driving device 32 that moves three-dimensionally in the Y and Z axis directions. Thus, the substrate W can be supported in the process chamber 80 as a processing container and can be appropriately moved in the process chamber 80. Note that the stage 31 has a plate portion that supports the substrate W from below. This plate portion has a built-in heater, and can maintain the substrate W at a high temperature required for laser annealing.

The irradiation optical system 20 and the mirror M4 are fixed to a support member 21 and have a position adjusting device 9 as a moving means.
By 0, both move in the AB direction as one. The position adjusting device 90 includes a guide 9 for guiding the movement of the support member 21.
1 and a drive device 92 for adjusting the movement of the support member 21. The support member 21 is reciprocated between the operating position and the retracted position by the position adjusting device 90. Support member 21
Is in the operating position, the laser beam AL that has passed through the irradiation optical system 20 passes through a window 80a provided in the process chamber 80, and is incident on a desired region on the substrate W disposed at the irradiation position. When the support member 21 is at the retracted position, the laser light AL that has passed through the irradiation optical system 20 is transmitted to the slit 5 disposed at the measurement position corresponding to the irradiation position.
Incident at 0.

The main controller 100 controls the operation of the attenuator controller 70 and the operation of the position adjusting device 90.

In the above embodiment, the joule meter 6
Reference numeral 0 denotes a position outside the process chamber 80 and below a measurement position equivalent to the surface of the substrate W. Ideally, it is desirable to control the transmittance of the variable attenuator 40 by measuring energy on the surface of the substrate W. However, since the process chamber 80 is a heating chamber, the joule meter 60 cannot be installed in the process chamber 80. For this reason, the joule meter 60
Is disposed outside the process chamber 80. in this case,
It is desirable to arrange the Joule meter 60 at a measurement position equivalent to the surface of the substrate W outside the process chamber 80. However, in the laser annealing apparatus of the present embodiment, the intensity of the laser beam AL is high. Exceeds the damage limit of 60. Therefore, the slit 5 is placed at a measurement position equivalent to the surface of the substrate W outside the process chamber 80.
0, and the laser light A
The Joule meter 60 is installed at a position where L is sufficiently diffused.

When the laser beam AL projected onto the surface of the substrate W is a linear beam, the energy of the laser beam cannot be directly measured because the laser beam is long and has high energy. A new optical system is required to perform the measurement, but the measurement accuracy is reduced due to the addition of the deterioration of the lens to the measured value. Since the effectiveness of the present invention is that the measurement accuracy is stable and simple, by arranging a slit without using a new optical system, a uniform laser beam can be obtained at the measurement position corresponding to the surface of the substrate W. The laser beam AL is cut off as appropriate within the aperture diameter of the joule meter 60 by cutting off the AL. The slit 50 has an opening for partially cutting the incident laser light AL.

The attenuator controller 70 compares the set value with an actually measured value measured by a joule meter, and
The actuator of the variable attenuator 40 is commanded and driven so that an energy amount corresponding to the difference passes. As a result, the transmittance of the variable attenuator 40 changes, and the energy reaching the measurement position, that is, the irradiation position on the surface of the substrate W is made constant.

Hereinafter, the operation of the laser annealing apparatus shown in FIG. 1 will be described. The substrate W is transported and placed on the stage 31 in the process chamber 80, and the temperature of the substrate W is raised to a desired temperature.

Next, the irradiation optical system 20 is moved to the retracted position, and the slit 50 is disposed at a measurement position equivalent to the irradiation position.
Irradiates the laser beam AL to the joule meter 60 via the to measure the irradiation energy. This irradiation energy is
Is proportional to the energy applied to the surface of the substrate W,
By determining the relationship in advance, the energy applied to the surface of the substrate W can be set to a desired value by adjusting the variable attenuator 40.

Next, at the stage where the above adjustment is completed, the irradiation energy measured by the joule meter 60 is stored in the main controller 100. That is, a reference value (set value) serving as a reference for feedback control is measured and stored.

Next, the irradiation optical system 20 is moved to the operating position, and the stage drive unit 32 is operated to move the substrate W on the stage 31 to the irradiation start position with respect to the irradiation optical system 20. Thereafter, the pulsed laser light AL from the laser light source 10 is made into a linear beam and incident on the substrate W while moving the stage 31. On the substrate W,
A thin film of an amorphous semiconductor such as amorphous Si is formed. The thin film of the amorphous semiconductor is annealed and recrystallized in a predetermined region on the substrate W by irradiation and scanning with a linear beam, and has excellent electrical characteristics. Polysilicon layer can be provided.

Before each irradiation of each substrate, the irradiation optical system 20 is moved from the irradiation position to the measurement position, and
At 0, the irradiation energy is measured again. Main controller 100
Compares the measured value with a previously stored reference value. As a result of such a comparison, if there is a change in the energy, the transmittance of the variable attenuator 40 is changed in accordance with the change, and the energy reaching the surface of the substrate W is kept constant. Further, the timing of the energy measurement is not limited to before the irradiation of the substrate W.

For example, a joule meter 6 having an initial set transmittance of 60% and an energy reaching the substrate of 30 mJ.
Assume that a measured value of 0 has been obtained. When a certain amount of annealing has been completed, the measured value reaches the substrate reaching energy of 20 mJ.
When the value of the variable attenuator 40 changes to 90%, the substrate surface energy is returned to 30 mJ by setting the transmittance of the variable attenuator 40 to 90%. As a result, the energy reaching the surface of the substrate W can be kept constant without relying only on the feedback control of the laser light source 10 itself, and a stable annealing result can be always obtained.

According to the above embodiment, the energy of the laser beam AL at the measurement position outside the process chamber 80 is detected at a necessary timing, and the energy of the laser beam AL emitted from the irradiation optical system 20 is adjusted at an arbitrary timing. be able to. Therefore, the energy of the laser beam AL applied to the substrate W can be accurately and simply controlled. Thereby, the productivity and the yield of the process using laser annealing are improved.

Although the present invention has been described with reference to the embodiment, the present invention is not limited to the above embodiment. For example, instead of moving the irradiation optical system, the irradiation direction of the laser beam AL exiting the irradiation optical system can be changed by moving a mirror in and out, and the irradiation can be made incident on a Joule meter to measure the irradiation energy. Also, the laser beam AL
Is applied to the Joule meter 60 to detect the energy of the laser beam AL, and is not limited to the stage where a fixed amount of annealing is completed. For example, the laser energy can be periodically or irregularly measured at an appropriate timing while avoiding the laser annealing process.

Further, a laser beam AL for annealing the substrate W
Is not limited to an excimer laser, but may be various laser beams.

In the above embodiment, the energy of the annealing light is adjusted in the laser annealing apparatus.
The energy of the processing laser light can be adjusted in the same manner as described above in various laser processing apparatuses used for forming compounds and the like.

[0032]

As is clear from the above description, according to the laser processing apparatus of the present invention, the energy detecting means for detecting the energy of the laser beam at the measuring position corresponding to the irradiation position and the output of the energy detecting means are provided. And control means for adjusting the energy of the laser light emitted from the irradiation optical system based on the detected energy of the laser light at the measurement position at the required timing to adjust the energy of the laser light emitted from the irradiation optical system as needed. can do. Therefore, the energy of the laser beam applied to the workpiece can be easily and precisely controlled, and the energy stability of the irradiated surface can be maintained with high accuracy.

According to the laser processing method of the present invention,
The energy of the laser beam emitted from the irradiation optical system can be adjusted as needed by detecting the energy of the laser beam at the measurement position at the required timing, and the energy of the laser beam applied to the workpiece can be easily and precisely controlled. can do.

[Brief description of the drawings]

FIG. 1 is a side view of a laser processing apparatus according to an embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Laser light source 20 Irradiation optical system 30 Process stage device 31 Stage 32 Stage drive device 40 Variable attenuator 50 Slit 60 Joule meter 70 Attenuator controller 80 Process chamber 90 Position adjustment device 100 Main control device AL Laser light M1-M4 Mirror W Substrate

Claims (3)

[Claims] A light source for generating a laser beam; an irradiation optical system for irradiating a laser beam from the light source onto an irradiation position on a workpiece; and detecting an energy of the laser beam at a measurement position corresponding to the irradiation position. A laser processing apparatus, comprising: an energy detecting unit that performs an operation; and a control unit that adjusts energy of a laser beam emitted from the irradiation optical system based on an output of the energy detecting unit. A moving means for moving a position where the laser light from the irradiation optical system is incident between the irradiation position and the measurement position, wherein the measurement position is incident on the energy detection means. The laser processing apparatus according to claim 1, wherein a slit for adjusting a beam shape of the laser light is provided. 3. A laser processing method for performing processing by irradiating a laser beam to an irradiation position on a workpiece through an irradiation optical system, wherein the laser beam energy at a measurement position corresponding to the irradiation position is determined. A laser processing method comprising: a step of detecting; and a step of adjusting energy of a laser beam emitted from the irradiation optical system based on the detected energy.