JP5614768B2 - Laser processing apparatus and laser processing method - Google Patents

Description

  The present invention relates to a laser processing apparatus and a laser processing method that can be used for laser annealing when manufacturing a polycrystalline or single crystal semiconductor film of a thin film transistor used in a pixel switch or a drive circuit of a liquid crystal display or an organic EL display. Is.

  As a semiconductor thin film used for a flat panel display substrate or the like, a semiconductor thin film using an amorphous film or a crystalline thin film is known. With respect to this crystalline thin film, a method of manufacturing an amorphous film by annealing and crystallizing has been proposed. In the annealing treatment, the object to be processed such as an amorphous film is irradiated with laser light so that the laser light enters the object to be processed and gives thermal energy to crystallize the object to be processed. In addition, there is also known a technique in which a crystalline film is irradiated with laser light to perform modifications such as defect removal and crystallinity improvement. The laser beam is output from a laser oscillator, attenuated by an attenuator, and irradiated to an object to be processed through an optical system including a lens, a mirror, an introduction window of a processing chamber, and the like.

The laser light applied to the object to be processed must have an appropriate power and energy so that an appropriate process such as annealing is performed on the object to be processed. The attenuation factor in the attenuator is adjusted appropriately. Further, in the laser oscillator, the output adjustment is usually performed by detecting the output of the laser beam and feeding back the detection result.
However, the optical system is contaminated with time, and in the processing chamber, the processing object is irradiated with laser light, whereby a part of the processing object is evaporated and the processing chamber introduction window is contaminated. For this reason, even if the laser oscillator and the attenuator are adjusted appropriately, the power and energy of the laser beam given to the object to be processed may vary due to the dirt, etc. There is a desire to accurately grasp energy.

In response to the above request, an apparatus that detects the energy of laser light at a measurement position corresponding to the laser irradiation position has been proposed (see Patent Document 1).
The above apparatus will be described with reference to FIG.
The laser processing apparatus shown in FIG. 5 includes a chamber 21 that houses a stage 20, and a substrate 22 to be processed is placed on the stage 20. A laser light source 30, an attenuator 31, mirrors 32, 33, 34, and 35 are provided outside the chamber 21, and the irradiation optical system 36 that is irradiated with the laser light is positioned toward the chamber 21 by the position adjusting device 23. And can be moved to a position facing the outside of the chamber 21. At the position where the irradiation optical system 36 is directed to the chamber 21 by the position adjusting device 23, the slit 24 and the joule meter 25 are installed at the irradiation position, and the output of the joule meter 25 is an attenuator controller 27 connected to the main controller 26. Configured to be sent to.

  In the above apparatus, when irradiating the substrate 22 with laser light, the position adjusting device 23 moves the irradiation optical system 36 to a position facing the substrate 22. On the other hand, when measuring the laser beam, the irradiation optical system 36 is moved to a position facing the slit 24 and the joule meter 25 by the position adjusting device 23. The output of the joule meter 25 is transmitted to the attenuator controller 27, and by adjusting the attenuator 31 based on the measurement result, feedback control of the laser light energy is possible.

Japanese Patent Laid-Open No. 2001-351876

  However, in the above apparatus, it is necessary to interrupt the irradiation of the laser beam to the object to be measured and transfer the laser beam irradiation optical system to irradiate the joule meter outside the processing chamber with the laser beam during the measurement. There is a problem that productivity is lowered because it cannot be performed. In addition, since the laser beam is irradiated to a position different from the position where the substrate is installed, there is a problem that the accuracy of the measurement result is not sufficient and the contamination of the processing chamber introduction window is not reflected.

  The present invention has been made against the background of the above circumstances, and it is possible to accurately measure the power, energy, and the like of laser light applied to the object to be processed without reducing productivity, and to adjust the output of the laser light. An object of the present invention is to provide a laser processing apparatus and a laser processing method that can be reflected in the above.

  The present invention has been made by paying attention to the fact that a part of the laser beam is reflected when the object to be processed is processed with the laser beam. For example, a silicon film used for a semiconductor has a characteristic of reflecting about 50% on the surface of the silicon film when irradiated with excimer laser light (wavelength: 308 nm).

That is, among the laser processing apparatuses of the present invention, the first aspect of the present invention includes a laser oscillation source that outputs laser light, an optical system that guides the laser light to the object to be processed, and the object to be processed inside. A processing chamber for guiding laser light to the object to be processed through the optical system provided outside, an introduction window provided in the processing chamber for introducing the laser light from the outside into the processing chamber, and disposed in the processing chamber. Measuring means for measuring the power or energy of reflected laser light irradiated and reflected on the object to be processed at an incident angle θ (θ> 0) in the processing chamber, and receiving the result of the measuring means, the laser oscillation source the adjustment, the measurement result of correlation the reflected laser beam and power or energy that is emitted to an object to be processed is within a predetermined range corresponding to proper power or energy corresponding to the target object with predetermined And a control device for controlling the output of the laser beam.
A laser processing apparatus according to a second aspect of the present invention includes a laser oscillation source that outputs laser light, an optical system that guides the laser light to the object to be processed, and the optical that is provided outside and the object to be processed is disposed inside. A processing chamber for guiding laser light to the object to be processed through a system; an introduction window provided in the processing chamber for introducing the laser light into the processing chamber from the outside ; and an angle of incidence on the object to be processed. Irradiating the object to be processed by adjusting the attenuator according to the measurement means for measuring the power or energy of the reflected laser beam irradiated and reflected at θ (θ> 0) in the processing chamber and the result of the measurement means is power or energy to the measurement result of correlation the reflected laser beam, said laser beam to fall within a predetermined range corresponding to proper power or energy corresponding to the target object with predetermined The control apparatus which controls the output of this is provided.
In the laser processing apparatus according to a third aspect of the present invention, in the second aspect of the present invention, the control unit receives the result of the measurement unit, and adjusts the laser transmission source and the attenuator to adjust the measurement unit. A control device is provided for controlling the output of the laser beam so that the measurement result of the measured reflected laser beam is within a predetermined range.
The laser processing method of the present invention performs processing of the object to be processed by irradiating the object to be processed in the processing chamber from the outside with an incident angle θ (θ> 0) through the introduction window. The power or energy of the partially reflected laser light is measured in the processing chamber, and the processing target is determined based on the measurement result based on the correlation between the measured value and the power or energy applied to the processing target. Estimate the power or energy of the laser beam irradiated on the body, compare the estimated value of the laser beam power or energy with the estimated value and a threshold value corresponding to a preset appropriate value, The laser beam power or energy is appropriately determined based on the determination, and if it is determined in the determination that the laser beam power or energy is not appropriate, Based on the measurement result, the measurement result of the reflected laser light measured by the measurement means by adjusting the attenuator is within a predetermined range corresponding to a predetermined power or energy corresponding to a predetermined object to be processed. And adjusting the output of the laser beam.

  According to the present invention, the characteristics of laser light can be evaluated while processing the object to be processed by measuring the laser light irradiated and reflected on the object. In addition, the laser beam is a reflected laser beam reflected by the object to be processed, and its reflectance is maintained almost constant, so that the state of the laser light itself irradiated to the object to be processed can be almost known, and optical Even when the system and the processing chamber introduction window are dirty, the state of the laser beam can be grasped more accurately.

The reflected laser beam can be measured by measuring the power and energy of the laser beam. As the measuring means for measuring, a known device such as a power meter or a joule meter can be used. The type is not limited. Measurement can be performed in a single shot, continuously, or intermittently while irradiating the target object with laser light, and measurement is performed on a target selected from a plurality of target objects. May be performed.
In order to facilitate installation and measurement of the measuring means, it is desirable that the laser beam is irradiated to the object to be processed at an incident angle θ (> 0). The incident angle θ can be set by the optical system.
The optical system is composed of appropriate optical members such as a lens, a mirror, and a homogenizer disposed in the optical path of the laser beam, and the present invention is not limited to a specific one.

  The measurement of the laser light may be performed either inside or outside the processing chamber in the present invention, even when the laser processing apparatus is provided with a processing chamber, but it is desirable to perform measurement by arranging a measuring means inside the processing chamber. . By measuring the reflected laser beam reflected in the processing chamber inside the processing chamber, the reliability of the measurement result can be improved. When the reflected laser beam reflected in the processing chamber is measured outside the processing chamber, the measurement accuracy is likely to be deteriorated due to the influence of dirt or the like when passing through a transmission window provided in the processing chamber.

Note that the laser beam used in the laser processing apparatus may have an appropriate beam shape depending on the purpose of processing, and the present invention is not limited to a specific beam shape of the laser beam. For example, a laser beam having a linear laser beam shape can be used.
In the case of a line-shaped laser beam, the distribution of power density and energy density in the major axis direction is also important, and if it is uniformly determined, the power density and energy density in the major axis direction must be uniform. Therefore, the measuring means may have a plurality of measurement points that can be measured independently along the long axis direction of the reflected laser beam having the line beam shape.

  When a moving device that moves the laser light applied to the object to be processed relative to the object to be processed is provided, the reflected light also moves relatively, and it is necessary to measure this with measuring means.

  The result measured by the measuring means is transmitted to a control device that controls the laser oscillator, the attenuator and the like. The control device can be configured by a CPU, a program for operating the CPU, an appropriate storage unit such as a ROM and a RAM, and the like. The laser oscillator can adjust the output by adjusting the voltage of the drive circuit, and the attenuator can adjust the output of the laser light by adjusting the transmission amount of the laser light, the attenuation factor, and the like.

In the control device, a threshold value that is an appropriate value corresponding to the object to be processed is determined in advance, and a determination is made as to whether or not the output of the laser beam is appropriate by comparing the measured value by the measuring means with the threshold value. It can be performed. The measurement value measured by the measurement means has a correlation with the power and energy of the laser beam irradiated to the object to be processed, and the power and energy of the laser beam irradiated to the object to be processed based on the measurement value. Can be estimated.
The threshold value can be determined in consideration of a value corresponding to a measured value of the reflected laser beam when appropriate power or energy is obtained. The threshold value can be determined in consideration of the safety level.

In the determination by the control device, if the measured value is equal to or greater than the threshold value, the power and energy of the irradiated laser light are appropriate, and if the measured value falls below the threshold value, it can be determined that the measured value is not appropriate. It is also possible to determine an upper and lower threshold value, determine that the threshold value is within the threshold range, and determine that the threshold value is exceeded and that the threshold value is below the threshold value.
In the control device, when it is determined from the measurement result that the power and energy of the laser beam are not appropriate, the laser oscillator and the attenuator are adjusted and irradiated during irradiation of the target object or while each target object is processed. The laser beam can be controlled so as to have appropriate power and energy.

  Based on the above determination, for example, when laser annealing treatment is performed on a semiconductor thin film or the like as an object to be processed, laser light can be irradiated based on appropriate power or energy, so that the object to be processed can be appropriately processed without variation. .

  As described above, according to the present invention, the laser oscillation source that outputs laser light, the optical system that guides the laser light to the object to be processed, and the reflected laser light that is irradiated and reflected on the object to be processed are measured. Since the object to be processed acts like a mirror, the state of the laser beam can be measured without causing a loss of energy or power and a decrease in productivity. Accurately grasp.

It is the schematic which shows the laser processing apparatus of one Embodiment of this invention. Similarly, it is a control block diagram. Similarly, it is a flowchart which shows a control procedure. Similarly, it is a perspective view which shows the example of a change of a measurement means. It is the schematic which shows the conventional laser processing apparatus.

Hereinafter, an embodiment of the present invention will be described with reference to FIG.
The laser annealing apparatus 1 corresponding to the laser processing apparatus of the present invention includes a laser oscillator 2 that outputs an excimer laser, and the output of the laser oscillator 2 outputs the output of the laser beam 2a output from the laser oscillator 2. An attenuator 3 to be adjusted is arranged. The attenuator 3 can adjust the output of the laser beam by adjusting the transmittance of the laser beam. In the attenuator 3, the adjustment of the transmittance is variable.

At the destination of the laser beam 2a whose output is adjusted by the attenuator 3, an optical system 4 is provided that shapes the laser beam 2a into a line beam-like laser beam 100 and guides it to the object to be processed in the processing chamber 6. . In the figure, only the convex lens 4a and mirror 4b of the optical system 4 are shown.
The attenuator 3 and the optical system 4 are accommodated in an optical system protector 5, and the laser beam 100 is irradiated toward the processing chamber 6 through the emission window 5 a of the protector 5.

  The processing chamber 6 is provided with an introduction window 6 a through which the laser beam 100 is incident, and a stage 7 is disposed in the processing chamber 6. The stage 7 can be reciprocated at least in one horizontal direction by a driving device (not shown). A workpiece 8 is placed on the stage 7. In this example, the target object 8 is obtained by forming an amorphous silicon thin film 8b on a substrate 8a, and the amorphous silicon thin film 8b is crystallized by annealing.

The optical system 4 is set so that the laser beam 100 is incident on the amorphous silicon thin film 8b at an incident angle φ (φ> 0) with respect to the major axis direction. For example, the amorphous silicon thin film 8b is irradiated while being condensed by an objective lens (not shown). At that time, the laser beam 100 converges near the surface of the amorphous silicon thin film 8b.
In the direction of the reflection angle φ with respect to the incident angle φ, a measuring instrument 10 for measuring the power and energy of the laser beam reflected in the processing chamber 6 is installed as a measuring means. In this embodiment, the measuring instrument 10 can measure the power or energy of the incident laser beam and output the measurement result to the outside.

  Further, as shown in FIG. 2, the laser annealing apparatus 1 has a control device 11 capable of adjusting the output of the laser oscillator 2 and the attenuation factor of the attenuator 3, and the measurement result is input to the control device 11. As described above, the measuring instrument 10 is connected. The control device 11 includes a storage unit 11a that stores a threshold value for controlling the laser oscillator 2 or the attenuator 3 in a nonvolatile manner. The storage unit 11a can hold data in a nonvolatile manner using a flash memory, an HDD, or the like, and can read the data as necessary.

Next, the operation of the laser annealing apparatus 1 will be described.
First, the target object 8 on which the amorphous silicon thin film 8b is formed is placed on the stage 7 in the processing chamber 6.
The laser oscillator 2 outputs a laser beam 2a that is an excimer laser beam having a wavelength of 308 nm. The laser beam 2a passes through the attenuator 3 and is adjusted to a desired output. The laser beam 2a is shaped into a line beam-like laser beam 100 after being condensed by the lens 4a and reflected by the mirror 4b in the optical system 4. The laser beam 100 is introduced into the processing chamber 6 through the emission window 5a and the introduction window 6a, and irradiated to the amorphous silicon thin film 8b on the stage 7 at an incident angle φ.
At this time, the movement of the stage 7 is controlled by a control device (not shown), and at the time of laser irradiation, the stage 7 is moved at a constant speed at a predetermined feed speed in the minor axis direction of the line beam.

About 50% of the laser light 100 irradiated to the amorphous silicon thin film 8b enters the amorphous silicon thin film 8b, and the energy is absorbed to heat the amorphous silicon thin film 8b. The heated amorphous silicon thin film 8b is subjected to annealing such as crystallization according to heating and cooling.
On the other hand, about 50% of the laser beam 100 irradiated to the amorphous silicon thin film 8b is reflected on the surface. At this time, as shown in FIG. 1, the laser beam is reflected at the reflection angle φ according to the incident angle φ, and the reflected laser beam 100 enters the measuring instrument 10 in the traveling direction.

  The measuring instrument 10 measures the power and energy of the incident laser beam and transmits the measurement result to the control device 11. The control device 11 compares the measurement result with a threshold value (upper and lower threshold values in this example) stored in the storage unit 11a, and controls the laser oscillator 2 and the attenuator 3 based on the comparison result. Which of the laser oscillator 2 and the attenuator 3 is to be adjusted is determined in advance, and the adjustment target is controlled. Moreover, you may make it determine a control object according to a measurement result.

The control procedure in the control device 11 will be described based on the flowchart of FIG.
With the start of the annealing process, the energy or power of the laser beam reflected by the object 8 is measured by the measuring instrument 10 (step s1). The measurement result in the measuring instrument 10 is transmitted to the control device 11 as described above.
The control device 11 receives the measured value (detected value), reads the threshold value stored in the storage unit 11a, compares the detected value with the threshold value, and determines whether or not the detected value is within a predetermined range within the upper and lower threshold values. Is determined (step s2). If the detected value is within the predetermined range (step s2, YES), it is determined that the output of the laser beam is appropriate, and the processing and detection of energy or power are continued (to step s1).

  On the other hand, if the detected value is not within the predetermined range (step s2, NO), it is determined that the output of the laser beam is not appropriate, and the laser oscillator output adjustment or attenuator adjustment is performed (step s3). The adjustment amount at this time may be performed with a predetermined fixed value, or may be performed according to the difference between the detected value and the threshold value. After the adjustment, if the annealing process is not completed (step s4, NO), the process is continued (to step s1). If the annealing process is completed (step s4, YES), the processing procedure is terminated.

  According to the above, the change in the output of the laser beam at the time of the laser beam irradiation can be accurately grasped in real time, and the change in the transmittance due to the contamination of the exit window 5a of the optical system protector and the introduction window 6a of the processing chamber 6 can be observed. It can be easily confirmed, dirt on the introduction window and the like can be confirmed accurately without removing the window, and the maintenance timing of the optical system and the window can be accurately determined.

In the above embodiment, the laser beam is measured with a single measuring instrument for the line beam shaped laser beam 100. However, the laser beam is measured at a plurality of points in the long axis direction of the laser beam. You may make it perform.
FIG. 4 shows the measuring instrument 15 that can measure at a plurality of points, and has a plurality of measuring sections 15a... 15a along the long axis direction of the laser beam. Each measurement unit 15a ... 15a has an output line 15b ... 15b, respectively, and can output a measurement result independently to the control device 11 described above. As a result, the control device 11 can know the energy density and power density distribution of the laser light in the major axis direction, and can perform maintenance and the like appropriately. It is also possible to adjust the output of the laser light in accordance with the above distribution.

In the above-described embodiment, the amorphous silicon thin film that is an object to be processed is described as being annealed. However, the present invention is not particularly limited to the content of the processing performed by laser light irradiation. What is necessary is just to perform an appropriate process with respect to a to-be-processed object by laser beam irradiation.
As mentioned above, although this invention was demonstrated based on the said embodiment, this invention is not limited to description of the said embodiment, As long as it does not deviate from the scope of the present invention, an appropriate change is possible. .

DESCRIPTION OF SYMBOLS 1 Laser annealing apparatus 2 Laser oscillator 2a Laser beam 3 Attenuator 4 Optical system 6 Processing chamber 8 To-be-processed object 10 Measuring instrument 11 Control apparatus 15 Measuring instrument 15a Measuring part 100 Laser beam

Claims (8)

A laser oscillation source that outputs laser light, an optical system that guides the laser light to the object to be processed, and the object to be processed are arranged inside, and the laser light is guided to the object to be processed through the optical system provided outside. A processing chamber, an introduction window provided in the processing chamber for introducing the laser beam from the outside into the processing chamber, and disposed in the processing chamber, which is irradiated with an incident angle θ (θ> 0) and reflected. A measuring means for measuring the power or energy of the reflected laser beam in the processing chamber, and a correlation with the power or energy irradiated to the object to be processed by adjusting the laser oscillation source in response to the result of the measuring means. the measurement result of some the reflected laser beam comprises a control device for controlling the output of the laser light to be within a predetermined range corresponding to proper power or energy corresponding to the target object with predetermined The laser processing apparatus characterized by the above-mentioned. A laser oscillation source that outputs laser light, an optical system that guides the laser light to the object to be processed, and the object to be processed are arranged inside, and the laser light is guided to the object to be processed through the optical system provided outside. A processing chamber, an introduction window provided in the processing chamber for introducing the laser beam from the outside into the processing chamber, and disposed in the processing chamber, which is irradiated with an incident angle θ (θ> 0) and reflected. Measuring means for measuring the power or energy of the reflected laser light in the processing chamber, and receiving the result of the measuring means, there is a correlation with the power or energy irradiated to the object to be processed by adjusting the attenuator the measurement result of the reflected laser beam comprises a control device for controlling the output of the laser light to be within a predetermined range corresponding to proper power or energy corresponding to the target object with predetermined The laser processing apparatus characterized by the above-mentioned.
The control unit receives the result of the measurement unit, and the measurement result of the reflected laser light measured by the measurement unit by adjusting the laser transmission source and the adjustment of the attenuator is within a predetermined range. The laser processing apparatus according to claim 2, further comprising a control device that controls an output of the laser light . It said measuring means, a laser processing apparatus according to claim 1 to 3 in which characterized in that to measure the power or energy of the reflected laser beam. The laser beam applied to the object to be processed has a line beam shape, and the measuring means can measure a plurality of each independently along the major axis direction of the reflected laser beam having the line beam shape. the laser processing apparatus according to any one of claims 1 to 4, characterized in that it has a measurement point. The laser processing apparatus according to any one of claims 1 to 5, characterized in that it comprises the mobile device to move relative該被processed with laser light to be irradiated on the target object.   The laser processing according to claim 1, wherein the optical system is configured so that the laser beam is irradiated to the object to be processed at an incident angle θ (> 0). apparatus. Performs processing該被processed by irradiating with an incident angle from outside the laser beam through the inlet window to the object to be processed in the processing chamber θ (θ> 0), the laser beam partially reflected by該被treated The power or energy is measured in the processing chamber, and based on the measurement result, the laser light irradiated to the object to be processed is correlated with the measured value and the power or energy irradiated to the object to be processed. Estimating the power or energy, comparing the estimated power or energy value of the laser beam that has been estimated with a threshold value corresponding to a preset appropriate value, and based on the comparison result, If the energy is determined appropriately and it is determined in the determination that the power or energy of the laser beam is not appropriate, the increase is made based on the measurement result of the laser beam. The output of the laser beam so that the measurement result of the reflected laser beam measured by the measuring unit by adjusting the tenator is within a predetermined range corresponding to a predetermined power or energy corresponding to a predetermined object to be processed. The laser processing method characterized by adjusting.

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