JP2014029965A - Method for monitoring surface of object to be processed, and monitoring device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make possible to grasp, by use of a relatively low-priced device, the melting state of a surface of an object to be processed which is being thermally treated by laser light including a pulsed laser light.SOLUTION: The monitoring device is a device for monitoring the condition of a surface of an object to be processed which is being thermally treated by irradiation of laser light including a pulsed laser light. The monitoring device comprises: a reference-light source for generating a reference light; a reference-light optical system for guiding the reference light from the reference-light source and irradiating the object to be processed with the reference light; a reflection-light detector unit for detecting a reflection light resulting from the reflection of the reference light by the heated object to be processed to take a surface image of the object to be processed; and a reflection-light optical system for guiding the reflection light to the reflection-light detector unit. The monitoring device irradiates the object to be processed with a pulse of reference light according to the timing of the pulsed laser light, or receives a pulse of reflection light resulting from the reflection by the object to be processed according to the timing of the pulsed laser light.

Description

  The present invention relates to a monitoring method and a monitoring apparatus for monitoring the surface state of an object to be processed that has been heat-treated by irradiation with pulsed laser light.

  In the manufacturing process of semiconductors for devices such as thin films on Si substrates, SiC substrates, GaN substrates, and glass substrates, the sample is irradiated with pulsed laser light for the purpose of crystallization and activation. A laser annealing process for heat treatment is adopted in part.

Here, a description will be given especially for a semiconductor that is activated by laser annealing. The activation of the semiconductor means that a pn junction layer is formed by heating and diffusing an intrinsic semiconductor of silicon into which impurities such as phosphorus and boron are implanted by an ion implanter. Since the laser annealing process can heat only the semiconductor surface, it is characterized by being a process capable of forming a pn junction layer in the surface layer portion.
In the laser annealing process, the spatial profile of the laser light beam is shaped into a circle, square, or line on the surface of the semiconductor wafer to be processed, and the beam is scanned. The laser beam is irradiated in pulses in time, and when a pulse of sufficient energy is irradiated, the wafer surface is heated, melted from the solid phase to the liquid phase, and cooled as the laser beam pulse falls. , Change from liquid phase to solid phase.

In the laser activation process, the activity rate of impurities doped in silicon is related to the melting time. In general, the longer the melting period, the higher the activation rate and the deeper the activation depth of silicon.
In addition, the area where silicon is melted varies depending on the spatial profile of the beam. Although the melting area depends on the spatial profile of the beam, in the period during which the laser light pulse is applied, the melting area starts to melt from the portion having the highest beam intensity, and the melted portion spreads in the surface direction. When the irradiation of the laser light pulse is completed, the area of the melted portion is reduced and the portion having a high beam intensity is finally solidified.

  In the laser annealing process, process conditions are changed by adjusting the energy intensity of laser light, changing the size of the spatial profile of the laser beam, adjusting the relative scanning speed of the beam, and the like. The quality of the process is evaluated by measuring the electrical resistance value on the silicon surface after the annealing process. Therefore, the activation state is based on indirect evaluation results, and the process conditions are set by inferring the state of laser irradiation from complicated phenomena including several phenomena.

However, a method for performing good process control by observing not only the process condition setting but also the surface state at the time of laser beam irradiation has been proposed (for example, see Patent Documents 1 and 2).
In Patent Document 1, it is determined whether or not a specific part of the material has reached a molten state with the progress of the melting process in the melting process in which melting energy is applied to the metal to melt the material by metal welding or the like. There has been proposed a method for monitoring in real time during processing the molten state of the material after melting, which largely reflects the quality of welding.
Further, in Patent Document 2, in the laser annealing process for a thin film, for example, when the film is an amorphous silicon thin film, the melt crystallization time until the silicon melts and solidifies and crystallizes, and the rate of crystal growth A method for measuring both of these has been proposed.

JP-A-7-284931 Japanese Patent Laid-Open No. 2004-146782

  Using a camera that can observe the phenomenon of the pulse period of the laser beam, the annealing process can be observed directly from the start of melting within one pulse to the expansion / reduction of the melting area, solidification, and the annealing process can be directly grasped. In-line evaluation during the laser process. Patent Document 1 proposes a method of observing the molten state at the time of one-pulse irradiation of a process pulse laser using this phenomenon. In this method, in order to observe the molten state, a camera capable of acquiring surface information with high time resolution, such as a streak camera, is required. At present, cameras having a time resolution of several nsec are expensive, such as a streak camera, and most of them are easily broken when excessive light is incident.

  Using such a streak camera in a production line is not realistic in terms of production device cost and maintenance frequency. In addition, when data on the melting state for each pulse is actually acquired from the entire irradiation area of one wafer (substrate), the amount of data becomes enormous, and the data transfer rate from the camera to the recording device is also real. This is not possible with typical equipment. Therefore, it is impractical to record all melting data during the process with a streak camera or the like and directly reflect the result on the irradiation condition of the laser beam for annealing. Even if the melting state of one pulse is obtained discretely and the result is reflected in the process, the annealing laser with a large variation for each pulse is used as a process condition based on the result of one data with a large variation. Therefore, it is difficult to realize good process control.

  The present invention has been made against the background of the above circumstances, and it is possible to satisfactorily observe the surface state of an object to be processed that is heated with a pulsed laser beam without requiring an expensive streak camera or the like. An object of the present invention is to provide a monitoring method and a monitoring apparatus for the surface of an object to be processed.

That is, in the monitoring method of the surface of the object to be processed according to the present invention, the first aspect of the present invention is that the surface of the object to be processed which is heated by irradiation with laser light including pulsed laser light is irradiated with reference light, In the method of monitoring the surface state of the object to be processed by receiving the reflected light reflected by the surface of the object to be processed by the reference light,
The surface of the object to be processed is irradiated in a pulsed manner on the surface of the object to be processed in accordance with the pulse timing of the pulsed laser light, and a surface image of the object to be processed is obtained by receiving the reflected light. It is characterized by monitoring the surface state of the treated body.

In the method for monitoring the surface of the object to be processed according to the second aspect of the present invention, the surface of the object to be processed heated by the irradiation of the laser beam including the pulsed laser beam is irradiated with the reference light, and the reference light is emitted from the object to be processed. In the method of monitoring the surface state of the object to be processed by receiving the reflected light reflected by the surface,
The reflected light is received in a pulse shape according to the pulse timing of the pulsed laser light, a surface image of the object to be processed is obtained by receiving the reflected light, and the surface state of the object to be processed is determined by the surface image. It is characterized by monitoring.

  According to a third aspect of the present invention, in the first or second aspect of the present invention, a continuous wave laser beam is used together with a pulsed laser beam as the laser beam including the pulsed laser beam. The surface of the object to be processed is heated by being irradiated on the surface of the body.

  According to a fourth aspect of the present invention, there is provided a method for monitoring a surface of an object to be processed, wherein the continuous wave laser beam is used as the reference light in the third aspect of the present invention.

  According to a fifth aspect of the present invention, there is provided a method for monitoring a surface of an object to be processed according to any one of the first to fourth aspects of the present invention, wherein two-dimensional numerical data is obtained from the surface image and processed using the numerical data. An optical constant that changes due to heat melting of the body is obtained, and a melting state of the surface of the object to be processed is determined from the constant.

  According to a sixth aspect of the present invention, there is provided a method for monitoring a surface of an object to be processed according to any one of the first to fifth aspects of the present invention. The time width is set to be a predetermined time width smaller than the pulse time width of the pulsed laser beam, and is positioned so as to overlap the pulse time width of the pulsed laser beam.

  According to a seventh aspect of the present invention, there is provided a method for monitoring a surface of an object to be processed according to any one of the first to sixth aspects of the present invention. The time width is shorter than the time during which the surface of the object to be processed is melted by irradiation with the pulsed laser light.

  According to an eighth aspect of the present invention, there is provided the method for monitoring a surface of an object to be processed according to any one of the first to seventh aspects of the present invention, wherein the pulsed irradiation or the pulsed light reception in the reference light is performed by the pulsed laser. It is characterized by being periodic with a pulse start timing having a predetermined phase difference with respect to the light pulse start timing.

  According to a ninth aspect of the present invention, there is provided the monitoring method of the surface of the object to be processed, in any one of the first to eighth aspects of the present invention, during the heat treatment of the object to be processed by irradiation with the pulsed laser beam. Changing the phase difference of the pulse start timing of the pulsed irradiation or the light receiving of the pulsed light with respect to the pulse start timing of the laser light to obtain a surface image of the object to be processed at a plurality of phase differences Features.

  According to a tenth aspect of the present invention, there is provided a monitoring method of a surface of an object to be processed in the ninth aspect of the present invention, wherein the pulsed irradiation or the pulsed light reception of the reference light is performed with a plurality of the phase differences. It is characterized in that the transient state in a continuous time connection is obtained.

  According to an eleventh aspect of the present invention, there is provided a method for monitoring a surface of an object to be processed, wherein the reference light is passed through the shutter to open and close the reference light composed of continuous waves intermittently. Irradiated in a pulsed manner.

  According to a twelfth aspect of the present invention, there is provided a method of monitoring a surface of a target object, wherein the reference target beam is irradiated with a continuous wave of reference light and the reflected light is pulsed through a shutter that opens and closes intermittently. It is characterized in that the light is received in a shape.

  According to a thirteenth aspect of the present invention, there is provided the method for monitoring a surface of an object to be processed according to any one of the first to twelfth aspects, wherein the surface image has a recording time longer than a pulse time width of the pulsed laser beam. It is obtained by photographing with a camera.

A monitoring apparatus for a surface of an object to be processed according to a fourteenth aspect of the present invention,
An apparatus for monitoring the surface state of an object to be heat-treated by irradiation with laser light including pulsed laser light,
A reference light source for generating reference light;
A reference light optical system that guides the reference light from the reference light source, and irradiates the object to be processed with the pulsed reference light according to the timing of the pulsed laser light;
A reflected light detection unit that detects reflected light reflected by the object to be processed heated by the reference light and acquires a surface image of the object to be processed;
A reflected light optical system that guides the reflected light to the reflected light detection unit.

  According to a fifteenth aspect of the present invention, in the fourteenth aspect of the invention, the reference light source outputs a pulsed reference light corresponding to a pulse timing of the pulsed laser light. It is characterized by being.

In the fourteenth aspect of the present invention, the monitoring device for the surface of the object to be processed according to the sixteenth aspect of the present invention is such that the reference light source generates continuous wave reference light,
The reference light optical system includes an irradiation light shutter that intermittently passes the reference light according to the pulse timing of the pulsed laser light to obtain pulsed reference light.

The monitoring apparatus for the surface of the object to be processed according to the seventeenth aspect of the present invention,
An apparatus for monitoring the surface state of an object to be heat-treated by irradiation with laser light including pulsed laser light,
A reference light source for generating reference light;
A reference light optical system for guiding the reference light from the reference light source and irradiating the object to be processed;
Reflected light detection for detecting a reflected light reflected by the object to be processed heated by the reference light as a pulsed reflected light corresponding to a pulse timing of the pulsed laser light and obtaining a surface image of the object to be processed And
A reflected light optical system that guides the reflected light to the reflected light detection unit.

According to an eighteenth aspect of the present invention, in the seventeenth aspect of the present invention, the reference light source generates continuous wave reference light.
The reflected light optical system includes a reflected light shutter that obtains pulsed reflected light by passing the reflected light intermittently according to the pulse timing of the pulsed laser light.

  According to a nineteenth aspect of the present invention, there is provided the monitoring apparatus for a surface of an object to be processed, wherein the reference light source generates a continuous wave laser beam for heating the object to be processed. It is a light source

  A monitoring apparatus for a surface of an object to be processed according to a twentieth aspect of the present invention is the control unit for adjusting a pulse time width of the pulse-shaped reference light or the pulse-shaped reflected light according to any of the fourteenth to nineteenth aspects of the present invention. It is characterized by having.

  According to a twenty-first aspect of the present invention, the monitoring apparatus for the surface of the object to be processed of the twenty-first aspect of the present invention provides the pulsed reference light or the pulse-shaped reference light with respect to the pulse start timing of the pulsed laser light. It has a control part which adjusts the phase difference of the pulse start timing of reflected light, It is characterized by the above-mentioned.

  According to a twenty-second aspect of the present invention, in the twenty-first aspect of the invention, the control unit is configured to change the phase difference during the heat treatment so that the pulse-like shape is changed in a plurality of phase differences. It is possible to irradiate reference light or receive the pulsed reflected light.

  A monitoring device according to a twenty-third aspect of the present invention provides the monitoring device according to any one of the fourteenth to twenty-second aspects of the present invention, wherein the surface state of the object to be processed is determined based on the surface image acquired by the reflected light detection unit. A state determination unit is provided.

  As described above, according to the present invention, a state in which the object to be processed is melted directly at a desired timing without using an expensive device with respect to the pulsed laser light for annealing treatment. There is an effect that can be observed.

It is a figure which shows the laser processing apparatus containing the monitoring apparatus of one Embodiment of this invention. Similarly, it is a longitudinal cross-sectional view showing the irradiation state of pulsed laser light and reference light on the surface of the object to be processed. Similarly, it is a top view which shows the irradiation state of the pulsed laser beam and reference light on the to-be-processed object surface, and the imaging region by a camera. Similarly, it is a figure which shows the pulse timing of the pulsed laser beam, the pulse timing of the reference beam having a phase difference, and the reflected light intensity change on the surface of the object to be processed. Similarly, it is a figure which shows the pulse timing of the reference beam which changed the pulse timing and phase difference of pulsed laser beam, and the reflected light intensity change of the to-be-processed object surface. Similarly, it is a figure which shows the laser processing apparatus containing the monitoring apparatus of other embodiment. Similarly, it is a figure which shows the laser processing apparatus containing the monitoring apparatus of other embodiment. Similarly, it is a figure which shows the laser processing apparatus containing the monitoring apparatus of other embodiment. Similarly, it is a figure which shows the laser processing apparatus containing the monitoring apparatus of other embodiment. Similarly, it is a figure which shows the laser processing apparatus containing the monitoring apparatus of other embodiment. Similarly, it is a figure which shows the laser processing apparatus containing the monitoring apparatus of other embodiment. It is a figure which shows the state irradiated to the to-be-processed object surface, while the pulsed laser beam for processes is scanned. It is a figure which shows the reflectance in the liquid phase in a silicon | silicone, and a solid phase. It is a figure which shows the transient melted state of a to-be-processed object when the pulsed laser beam for processes is irradiated to the to-be-processed object surface, and the reflected light intensity change of a to-be-processed object surface.

First, the state of the surface of the object to be processed when irradiated with laser light including pulsed laser light will be described with reference to FIG.
FIG. 12 is a partial plan view of a state in which a silicon (Si) thin film is irradiated with pulsed laser light having an elliptical beam cross-sectional shape. The pulsed laser beam is applied to the silicon thin film at a predetermined overlap rate while being scanned in the scanning direction. In the silicon thin film irradiated with the pulsed laser beam, the temperature rises in and around the part directly irradiated with the pulsed laser beam, and the surface of the silicon thin film is transiently moved in the part directly irradiated with the beam. A melted part is partly melted and a non-melted part that does not melt in other parts, and a melted / non-melted mixed part exists between them.

In silicon, the reflectivity varies depending on the melted and non-molten state, the reflectivity of the melted portion is relatively high, and the reflectivity of the non-melted portion is relatively low. The refractive index of silicon in visible light is about 3.3 in the solid phase and about 4.1 in the liquid phase.
FIG. 13 is a graph showing the reflectance in the solid phase and the relative reflectance in the liquid phase in silicon, where s-pol means s-polarized light and p-pol means p-polarized light. The reflectivity according to the incident angle of the light with polarization is shown. Therefore, by appropriately determining the incident angle of the reference light, it is possible to obtain reflectances that are clearly different depending on the melted and non-melted states. Reflectance is one of the optical constants.

  Note that the laser light including the pulsed laser light may be only the pulsed laser light, or may be a combination of continuous-wave laser light. The continuous wave laser light may be irradiated with the object to be processed after being combined with the pulsed laser light, or may be irradiated with another path. Note that when only the pulsed laser beam is irradiated, a combination of a plurality of pulsed laser beams may be used. Note that the continuous wave laser beam is usually used as an assist for the pulsed laser beam, and in this case as well, melting occurs on the surface of the object to be processed in accordance with the irradiation of the pulsed laser beam.

Next, a transient surface state at one point on the surface of the object to be processed when the pulsed laser beam is irradiated will be described.
The middle stage of FIG. 14 shows the intensity waveform of one pulse of the pulsed laser beam. With this form of pulsed laser light, the peak intensity is reached in a short time with a steep rise, and then the intensity gradually decreases and then falls abruptly to zero level. The time width of this pulse can be determined according to an appropriate standard. The reference is not limited to a specific one, and the time width of the pulse may be discussed based on the same reference. For example, the pulse time width can be determined by a time interval having an intensity of 50% or more of the maximum intensity, a time interval between the rising half-value point and the falling half-value point of the pulse peak value, and the like.

  When the object to be processed is irradiated with the pulsed laser beam having the above intensity distribution, a transient molten state is generated on the surface of the object to be processed as shown in the upper part of FIG. The upper part of FIG. 14 shows the surface state of the object to be processed at each time point. At the center of the beam cross section on the surface of the object to be processed, the laser beam is located at the maximum pulse intensity, and a thin band-shaped melted part is located along the longitudinal direction of the beam cross section. The non-melting mixed region is located outside the non-melting region. In the pulse, the intensity of the laser beam slightly decreases with the passage of time, but since the heating of the pulsed laser beam is continued, the width of the melted portion in the scanning direction widens, and the melted portion is scanned in the middle of the time width of the pulse. The direction width is maximum. Further, as time elapses, the intensity of the laser beam is reduced, the heating action is weakened, and the width of the melted portion in the scanning direction is gradually narrowed. Although not shown in the figure, the pulse disappears, and the surface of the object to be processed finally becomes a solid phase. When the next pulse is irradiated, the position shifts at a predetermined overlap rate with the relative scanning of the pulsed laser beam, and the object to be processed is irradiated with the pulsed laser beam.

  The lower part of FIG. 14 shows a change in intensity of reflected light reflected from a laser light irradiation region at one point on the surface of the object to be processed during one pulse when pulsed laser light is irradiated. The intensity of the reflected light is averaged and does not indicate a transient melting state in the irradiated area. Therefore, even if the change in the reflected light intensity at one point on the surface of the object to be processed is observed, it is impossible to grasp the change in the transient melting state on the surface of the object to be processed.

Next, a laser processing apparatus including a monitoring apparatus according to an embodiment of the present invention will be described with reference to FIG.
A laser processing apparatus 1 including a monitoring apparatus includes a laser oscillator 2 that outputs a pulsed laser beam 2a and a process optical system 3 that guides the pulsed laser beam to an object to be processed 100. In FIG. As a part of the system 3, a mirror 3a and a condenser lens 3b are shown. In addition to this, the process optical system 3 may include various optical members such as a homogenizer and a cylindrical lens. In the present invention, the configuration of the process optical system 3 is not limited to a specific one.
Further, the laser processing apparatus 1 has a scanning device (not shown) that moves the pulsed laser light 2 a relative to the object 100 to be processed. The scanning device may move the pulsed laser beam 2a side or may move the object to be processed 100 side and perform relative scanning by moving both of them. There may be. In the present invention, the relative scanning of the laser beam is not essential.

  The laser processing apparatus 1 can be used in the process of activating and crystallizing semiconductor devices and display devices such as silicon substrates, GaN substrates, SiC substrates, and thin films on glass substrates as objects to be processed. However, in the present invention, the type of the object to be processed and the content of the heat treatment in the laser processing apparatus are not particularly limited. In this embodiment, the laser processing apparatus 1 is used in an annealing process in the process of manufacturing a semiconductor device on a silicon substrate.

Next, the configuration of the monitoring device will be described.
The monitoring apparatus includes a reference light source 10 that outputs a pulsed reference light 10a, and the reference light 10a is guided to an irradiation region 100a on the surface of the object 100 to be irradiated with the pulsed laser light 2a. It has an optical optical system 11. In the drawing, a condensing lens 11 a is shown as one of the reference light optical systems 11. In the present invention, the configuration of the reference light optical system is not limited to a specific one.
Note that the reference beam 10a is irradiated on a part or all of the irradiation region 100a on the object 100 to be irradiated with the pulsed laser beam 2a. For this reason, when the pulsed laser beam 2a is scanned relative to the object to be processed 100, the reference device 10a is similarly scanned relative to the object to be processed 100. Not). This scanning device may also be used as a scanning device that performs relative scanning of the pulsed laser beam 2a.

Furthermore, the monitoring apparatus has a control unit 12 that controls the reference light source 10. The control unit 12 includes a CPU, a program for operating the CPU, a RAM serving as a work area, a nonvolatile memory, and the like. The control unit 12 includes a phase adjuster 12a and a time width adjuster 12b. For example, the phase adjuster 12a and the time width adjuster 12b are configured by a partial function of the control unit 12 to realize the operation. can do.
A trigger signal indicating the pulse start timing of the pulsed laser beam 2 a is input to the control unit 12 from the circuit of the laser oscillator 2. When the control unit 12 controls the pulse timing of the laser oscillator, the trigger signal related to the pulsed laser beam can be obtained in the control unit 12 without receiving the trigger signal from the laser oscillator 2.
The control unit 12 has a predetermined phase difference with respect to the pulse start timing of the pulsed laser beam 2a in the phase adjuster 12a on the basis of the trigger signal related to the pulsed laser beam 2a, and the pulse start timing of the reference beam 10a. Is generated and output to the reference light source 10. Further, based on the pulse time width of the pulsed laser light 2 a output from the laser oscillator 2, a predetermined time width command signal is generated by the time width adjuster 12 b and output to the reference light source 10. Information on the pulse time width of the pulsed laser beam 2a can be obtained from the laser oscillator 2, and when the laser oscillator 2 is controlled by the control unit 12, the control unit 12 can control the pulsed laser beam 2a. Information on the pulse time width can be acquired.

  The reference light source 10 receives a trigger signal and a time width command signal from the control unit 12, and has a predetermined phase difference with respect to the pulsed laser light 2a and is smaller than the pulse time width of the pulsed laser light. The pulsed reference beam 10a is output with a time width of. At this time, the phase difference is determined so that the pulse time width of the reference light 10a is located at a predetermined position within the pulse time width of the pulsed laser light 2a.

  A camera 14 is disposed as a reflected light receiving unit in a direction in which the reference light 10a is applied to the irradiation region 100a on the object 100 and the reflected light 10b is reflected. The camera 14 can obtain a surface image in the irradiation region 100a by the reflected light 10b, and can take an image in a time exceeding the pulse time width of the pulsed laser light 2a. The camera 14 is not required to have the time resolution as that of the streak camera, and can be constituted by a relatively inexpensive CCD or CMOS, and the surface of the object 100 using the reflected light 10b by the afterimage effect. Can be obtained.

A data processor 15 with a display unit is connected to the camera 14, and imaging data of the camera 14 is output to the data processor 15 with a display unit. The data processor 15 with a display unit corresponds to a surface state determination unit.
The data processor 15 with a display unit can calculate two-dimensional numerical data or create image data for display from image data indicating a surface image by image processing. As this invention, the processing content of the data processor 15 with a display part is not limited to a specific thing, What is necessary is just what can monitor the surface state of the to-be-processed object 100 surface. The monitoring of the surface state may be performed by the data processor 15 with a display unit, or the operator may observe and determine the display image.

Next, the operation of the laser processing apparatus 1 will be described.
The laser oscillator 2 outputs pulsed laser light 2a having a predetermined wavelength at a preset repetition frequency and pulse time width. In this embodiment, for example, the oscillation repetition frequency of the pulsed laser beam 2a can be set to 10 kHz, and the pulse time width can be set to about 1000 nsec.
At this time, the laser oscillator 2 outputs a trigger signal corresponding to the pulse start timing to the control unit 12. The energy of the pulsed laser beam 2a is adjusted by an attenuator (not shown) or the like, and is shaped into a predetermined beam cross-sectional shape by the process optical system 3. Further, the pulsed laser light 2 a is reflected by the mirror 3 a in the process optical system 3, condensed by the condenser lens 3 b, and irradiated on the object 100 to be processed. The condensing lens 3b aligns the focal point or imaging surface of the pulsed laser light 2a near the surface of the object 100 to be processed. The object to be processed 100 is moved by a scanning device (not shown). As a result, the pulsed laser light 2a is irradiated onto the object to be processed 100 while being scanned relative to the object to be processed 100, and a desired heat treatment is performed. Is done.

The size of the beam of the pulsed laser beam 2a on the surface of the object to be processed is not particularly limited, and may be a circle, an ellipse, a rectangle, or a line of several tens of μ to several mm depending on the processing content to be performed. Those having a light intensity profile can be used. In order to emit a pulsed laser beam in a pulse shape, for example, the object to be processed is processed by repeatedly melting and solidifying.
The surface of the object to be processed 100 is heated to near the melting point of the material or above the melting point by irradiation with the pulsed laser beam 2a, and the reflectance of the surface changes as shown in FIG.

  When the object to be processed 100 is started to be irradiated with the pulsed laser light 2a, the surface of the object to be processed 100 is heated, and when the surface of the object to be processed 100 is heated to the melting point or higher, melting starts from a portion having a high beam intensity. As the pulsed laser beam 2a continues to be irradiated, the melted area expands. When the intensity of the pulsed laser beam 2a is weakened, solidification starts from a portion where the beam intensity is weak, and the area of the melted portion decreases. All solidify when the temperature is below the melting point.

On the other hand, in the monitoring device, a trigger signal having a predetermined phase difference from the trigger signal from the laser oscillator 2 is generated by the phase adjuster 12 a of the control unit 12 by the trigger signal output from the laser oscillator 2. The predetermined phase difference may be a fixed value set in advance, or may be set so as to be appropriately changed.
In the control unit 12, a predetermined pulse time width command smaller than the pulse time width of the pulsed laser beam 2a is generated by the time width adjuster 12b. Information on the pulse time width of the pulsed laser light 2a may be acquired from the laser oscillator 2 together with the trigger signal, or information may be acquired in advance for comparison. Furthermore, predetermined pulse time width data smaller than the pulse time width of the pulsed laser beam 2a may be given without performing comparison.

The trigger signal giving the phase difference and the time width command are transmitted to the reference light source 10, and the reference light source 10 determines a predetermined pulse start timing and a predetermined pulse time width according to the trigger signal and the time width command. Thus, the pulsed reference light 10 a is output from the reference light source 10. For example, it has a phase difference of 1/4 pulse with respect to the pulsed laser beam 2a, and is set to a pulse time width of about 1/4 of the pulsed laser beam 2a.
The reference beam 10a may be output while the pulsed laser beam 2a is being output, or may be output at a predetermined timing or an arbitrary timing by the operator.

The reference light 10 a is guided while being shaped into a predetermined beam cross-sectional shape by the reference light optical system 11, collected by the condensing lens 11 a, and irradiated onto the surface of the object 100 to be processed. The reference light 10a is preferably irradiated on the surface of the object to be processed 100 at a size that exceeds the irradiation region 100a irradiated with the pulsed laser light 2a at least in the irradiation and reflection surface direction. .
In this embodiment, the reference light source 10 is described as changing the pulse width. However, the reference light optical system 11 may be configured to adjust the pulse width.
Further, the monitoring device may not have a function of adjusting the pulse width of the reference light, and may use a reference light source that outputs the reference light only with a pulse time width fixed in advance. In this embodiment, the fixed pulse time width is shorter than the pulse time width of the pulsed laser beam.

The reference light 10a is reflected by the surface of the object 100 to which the pulsed laser light 2a is irradiated, and is received by the camera 14 as reflected light 10b.
FIG. 2 is a schematic diagram for explaining the state of irradiation and reflection of laser light on the surface of the object 100 to be processed.
The surface of the workpiece 100 is irradiated with the pulsed laser beam 2a to form a melted region 110 inside the irradiated region 100a, and a non-melted region 111 is formed near the outer edge of the irradiated region 100a outside thereof. Although the non-melting region 111 is heated by irradiation with the pulsed laser beam 2a, it is a region that has not reached the molten state, and reaches a little outside the irradiation region 100a and the depth direction side of the irradiation region 100a by heat transfer. Yes.

The reference light 10a has an irradiation region that exceeds at least the irradiation region 100a in the scanning direction.
The reference light 10a is reflected by the surface of the workpiece 100, and the reflected light 10b travels in the reflection direction. The reflected light 10b is composed of reflected light 10b1 irradiated and reflected on the melting region 110 having a relatively high reflectance and reflected reflected light 10b2 irradiated on the non-melting region 111 having a relatively low reflectance, The reflected light 10b1 has a relatively high intensity, and the reflected light 10b2 has a relatively low intensity. The reflected light 10b composed of these reflected lights 10b1 and 10b2 is received by the camera 14.

FIG. 3 shows a plan view of the surface of the object to be processed 100 and an imaging region 14 a by the camera 14.
The beam cross section of the pulsed laser beam 2a has a long oval shape, and a melted part 110 is formed inside the irradiation region 100a irradiated with the pulsed laser beam 2a, and is outside the melted part 110. Thus, the non-melting region 111 is formed up to slightly outside the irradiation region 100a. The reference beam 10a has a beam size that exceeds the irradiation area in the scanning direction, and is smaller than the pulsed laser beam in the longitudinal direction of the pulsed laser beam 2a.
The imaging area 14a of the camera 14 covers an area irradiated with the reference light 10a, and has a size exceeding the irradiation area of the reference light 10a in the scanning direction of the reference light 10a. The grid of the imaging region 14a is an image of each pixel area in the camera 14, and optical elements such as a CCD and a CMOS are arranged.

Next, FIG. 4 shows the relationship between the pulse start timing and pulse time width of the pulsed laser beam 2a and the reference beam 10a.
The reference beam 10a has a pulse start timing having a phase difference of about ¼ pulse with respect to the pulsed laser beam 2a, and obtains a transient melting state of the workpiece 100 at this time. Can do. The pulse time width of the reference beam 10a is about ¼ of the pulse time width of the pulsed laser beam 2a, and the acquisition of the surface state is suppressed from being averaged over the entire pulse time width to temporarily It is possible to accurately acquire the transient state. That is, in order to observe the molten state, the reference beam 10a is irradiated for a time shorter than the pulse time width of the process pulsed laser beam 2a. The pulse irradiation time of the reference beam 10a preferably overlaps with the pulse irradiation time of the pulsed laser beam 2a, and further overlaps with the pulse irradiation time of the pulsed laser beam 2a. The time required to record one image with a general CCD camera or CMOS camera is about 1/30 second. However, when a plurality of pulses are incident on the camera 14 even with the pulsed reference light 10a, the camera 14 is referred to. Only the time during which the light 10a is irradiated can be observed as an afterimage. A desired moment in a series of melting phenomena can be observed by appropriately setting the phase of the pulses of the pulsed laser beam 2a for the process and the reference beam 10a. Also, if the phase is changed, different instantaneous transients can be observed.
On the other hand, the reflected light intensity at one point of the irradiation region shows a substantially constant value depending on the reflectance at the time of melting, as shown in the lower part of FIG.

  As described above, the camera 14 can obtain a surface image in which the light intensity distribution reflected by the melting part 110 and the non-melting part 111 is generated. That is, in the camera 14, the melted portion on the surface of the object 100 is observed brightly. From this surface image, a numerical value of a two-dimensional intensity distribution can be calculated. From this numerical value, two-dimensional data indicating a change in the refractive index, which is an optical constant, can be obtained. This data indicates a change in refractive index, which is an optical constant during the solid phase and the liquid phase of silicon, and it is possible to grasp the molten state of the surface of the object 100 to be processed.

  That is, according to this embodiment, the time resolution is orders of magnitude lower than the pulse period of the pulsed laser beam, and an inexpensive CCD camera or CMOS camera that is conventionally used as an observation camera is used. The surface melting phenomenon can be observed as an average of a very short period of irradiation called a pulse time width of the reference light 10a within a certain range of the object 100 by using the afterimage effect. .

In the above embodiment, as shown in FIG. 4, the reference beam 10a is described as having a constant phase difference in pulse start timing with respect to the pulsed laser beam 2a. Thereby, in the transitional change of a molten state, the surface state in the same time can be grasped | ascertained for every pulse.
FIG. 5 shows the relationship between the pulse start timing and the pulse time width when the pulse start timing of the reference beam 10a with respect to the pulsed laser beam 2a is changed for each pulse. This makes it possible to grasp transient phenomena at different times.

Furthermore, as shown in FIG. 5, the phase difference in each pulse is sequentially set to phase difference A, phase difference B, phase difference C, and phase difference D, and the time difference between the phase differences matches the pulse time width of reference light 10a. Thus, by connecting the surface images obtained by the pulse irradiation of the reference beam 10a with the data processor 15 with a display unit, it is possible to more accurately grasp the transitional transition state, and in terms of time. Continuous transient changes can be obtained.
Moreover, although the form which adjusts a phase difference was demonstrated above, the resolution of the time axis of a melting phenomenon can be changed by adjusting a time width.

Next, another embodiment will be described with reference to FIG. In addition, about the structure similar to the said embodiment, the same code | symbol is attached | subjected and description is abbreviate | omitted or simplified.
The laser processing apparatus 1a of this embodiment includes a reference light source 20 that performs continuous oscillation, and an irradiation light shutter 21 that transmits and opens and closes the reference light is disposed in the reference light optical system 11. The control unit 12 is connected to the irradiation light shutter 21 in a controllable manner.
Also in this embodiment, the trigger signal indicating the pulse start timing is transmitted from the laser oscillator 2 to the control unit 12. In response to this trigger signal, the control unit 12 generates a trigger signal indicating the shutter opening start timing with a predetermined phase difference. Further, a pulse time width set in accordance with the pulse time width of the pulsed laser beam 2a is set. The pulse time width indicates the shutter opening continuation time from when the irradiation light shutter 21 is opened until it is closed.

Next, the operation in this embodiment will be described.
In the laser processing apparatus 1a, the laser oscillator 2 outputs pulsed laser light 2a to start processing. As described in the above embodiment, the pulsed laser beam 2a is output at a predetermined wavelength with a preset repetition frequency and pulse time width. The pulsed laser light 2 a is shaped into a predetermined beam cross-sectional shape by the process optical system 3, reflected by the mirror 3 a of the process optical system 3, condensed by the condenser lens 3 b, and applied to the object 100 to be processed. Irradiated.

  In the laser oscillator 2, a trigger signal for pulse oscillation is output to the control unit 12. In the control unit 12, the trigger signal is generated by the phase adjuster 12a as described above, and a pulse time width command is output by the time width adjuster 12b. Is generated. Further, the control unit 12 outputs the reference light 20a from the reference light source 20 by continuous oscillation. The output of the reference beam 20a may be performed while the pulsed laser beam 2a is being output, or may be performed at a predetermined time or an arbitrary time by the operator.

The trigger signal and the pulse time width command described above are transmitted as a control signal to the irradiation light shutter 21, and the opening / closing of the irradiation light shutter 21 is controlled. Thereby, the reference beam 20a is irradiated to the object 100 to be processed in a pulse shape. In the irradiation, the pulsed laser beam 2a is started with pulsed irradiation with a predetermined phase difference, and the pulsed beam is irradiated in a time shorter than the pulse time width of the pulsed laser beam 2a. The reflected light 20b reflected by the reference light 20 in the irradiation area 100a of the object 100 is received by the camera 14 and can be subjected to image processing or the like by the data processor 15 with a display unit as in the above embodiment.
Also in this embodiment, similarly to the above-described embodiment, the surface state at the same time can be grasped for each pulse in the transitional change of the molten state of the workpiece 100.
Further, in this embodiment, since continuous oscillation reference light is used, laser light with stable output can be used for reference, and the relationship between the obtained surface image and the surface state of the object to be processed is More accurate.

Furthermore, another embodiment is described based on FIG. In addition, about the structure similar to the said embodiment, the same code | symbol is attached | subjected and description is abbreviate | omitted or simplified.
In each of the above embodiments, the incident angle of the reference light is different from the incident angle of the pulsed laser light 2a to the object 100. As a result, the reflected light of the reference light is reflected in the reflection direction of the pulsed laser light 2a. Is different. As a result, when the reflected light is received, the reference accuracy can be improved by receiving the reflected light of the pulsed laser beam 2a as much as possible. However, in the present invention, such a configuration is not essential, and the incident angle of the pulsed laser beam and the incident angle of the reference beam may be the same.

  In the laser processing apparatus 1b of FIG. 7, a half mirror 3c is provided as one of the process optical systems 3 in place of the mirror 3a, and a half mirror 11b is further disposed on the lower reflection side of the half mirror 3c. A condenser lens 3b is disposed on the transmission side. The half mirrors 3 c and 3 d and the condensing lens 3 b serve as a part of the process optical system 3 and a part of the reference light optical system 11.

  Further, a mirror 11b, which is one of the reference light optical systems 11, is disposed in the transmission direction facing the upper side of the half mirror 3c, and the camera 14 is disposed in the reflection direction thereof. A data processor 15 with a display unit is electrically connected to the camera 14 as in the above embodiments.

In this embodiment, the pulsed laser beam 2a output from the laser oscillator 2 is reflected downward by the half mirror 3c, passes downward through the half mirror 3d, is condensed by the condenser lens 3b, and is processed. The body 100 is irradiated.
On the other hand, the reference light 10a output from the reference light source 10 is reflected downward by the half mirror 3d, condensed by the condenser lens 3b, and then irradiated to the object 100. Accordingly, the reference light 10a is collected by the condenser lens 3b and is incident on the condenser lens 3b so as to have a desired beam cross-sectional size. The reference light 10a is reflected by the surface of the workpiece 100 to become reflected light 10b. The reflected light 10b travels upward, passes through the condenser lens 3b, passes through the half mirror 3d, passes through the half mirror 3c, and reaches the reflecting surface of the mirror 11b. The reflected light 10 b is reflected by the mirror 11 b and received by the camera 14.

  That is, the object to be processed 100 irradiated with the pulsed laser light 2a is irradiated with the reference light 10a at the same incident angle as the pulsed laser light 2a, reflected by the object to be processed 100, and the reflected light 10b has the same optical path. Reflected by. At this time, the reflected light of the pulsed laser light 2a proceeds in the same manner, but a surface image using the reference light 10b can be acquired. By using a wavelength filter or the like, the acquisition of the surface image by the reference light 10b can be performed with higher accuracy. In this embodiment as well, if the irradiation light shutter is provided before reaching the half mirror 3d, the reference light source 20 and the irradiation light shutter 21 that oscillate continuously can be used.

Furthermore, the laser processing apparatus 1c provided with the monitoring apparatus of other embodiment is demonstrated based on FIG. In addition, about the structure similar to the said embodiment, the same code | symbol is attached | subjected and description is abbreviate | omitted or simplified.
In each of the above embodiments, the control unit 12 generates a trigger signal having a phase difference with respect to the pulsed laser beam 2a. However, it is possible to provide a phase difference by using a cable length or the like.

That is, in this embodiment, the trigger signal of the laser oscillator 2 is taken out by the transmission cable 12c, and this transmission cable 12c is connected to the reference light source 10 to input the trigger signal. The trigger signal flowing through the transmission cable 12c has a phase difference according to the cable length of the transmission cable 12c. This is given to the reference light source 10 as a trigger signal having a phase difference, and the pulse start timing of the reference light 10a is set. . The phase difference can be performed by adjusting the cable length. Note that the pulse time width in the reference light is set in advance as being fixed. At this time, the set value is set smaller than the pulse time width of the pulsed laser beam 2a.
Also in this embodiment, the transitional change in the molten state of the surface of the object to be processed can be grasped with high accuracy as in the above embodiments.

Furthermore, the laser processing apparatus 1d provided with the monitoring apparatus of other embodiment is demonstrated based on FIG. In addition, about the structure similar to the said embodiment, the same code | symbol is attached | subjected and description is abbreviate | omitted or simplified.
In each of the above-described embodiments, the description has been made on the assumption that the reference light applied to the object to be processed is irradiated in a pulse shape. However, the reference light is continuously applied to the object to be processed 100, and the reflected light is pulsed. It is good also as what receives light.
In the laser processing apparatus 1 d shown in FIG. 9, a continuous transmission reference light source 20 is provided, and an openable / closable reflected light shutter 22 is disposed in the optical path of the reflected light 20 b reflected from the object 100 to be processed 100. The reflected light shutter 22 is controlled to be opened and closed by the control unit 12.

  Also in this embodiment, the trigger signal indicating the pulse start timing is transmitted from the laser oscillator 2 to the control unit 12. In response to this trigger signal, the control unit 12 generates a trigger signal indicating the shutter opening start timing with a predetermined phase difference. Further, a pulse time width set in accordance with the pulse time width of the pulsed laser beam 2a is set. The pulse time width indicates the shutter opening time from when the reflected light shutter 22 is opened until it is closed.

Next, the operation in this embodiment will be described.
In the laser processing apparatus 1d, the pulsed laser beam 2a is output from the laser oscillator 2 to start processing. The pulsed laser light 2 a is shaped into a predetermined beam cross-sectional shape by the process optical system 3, reflected by the mirror 3 a of the process optical system 3, condensed by the condenser lens 3 b, and applied to the object 100 to be processed. Irradiated.

  In the laser oscillator 2, a trigger signal for pulse oscillation is output to the control unit 12. In the control unit 12, the trigger signal is generated by the phase adjuster 12a as described above, and a pulse time width command is output by the time width adjuster 12b. Is generated. Further, the control unit 12 outputs the reference light 20a from the reference light source 20 by continuous oscillation.

The trigger signal and the pulse time width command described above are transmitted as control signals to the reflected light shutter 22, and the opening and closing of the reflected light shutter 22 is controlled. The reference light 20 a is continuously applied to the object 100 and is received by the camera 14 in a pulsed manner through the reflected light shutter 22. In the light reception, the pulsed laser light 2a is started at the pulsed light reception with a predetermined phase difference, and the pulsed light reception is performed in a time shorter than the pulse time width of the pulsed laser light 2a. That is, the reflected light 20b reflected by the reference light 20a in the irradiation area 100a of the object 100 is received in a pulse form by the camera 14, and image processing or the like is performed by the data processor 15 with a display unit as in the above embodiment. be able to.
Also in this embodiment, similarly to the above-described embodiment, the surface state at the same time can be grasped for each pulse in the transitional change of the molten state of the workpiece 100.

  In each of the above embodiments, the description has been given of the case where only the pulsed laser beam is used as the laser beam including the pulsed laser beam. However, in the present invention, as described above, at least the pulsed laser beam is used. Alternatively, continuous wave laser light can be used in addition to pulsed laser light. Hereinafter, a mode in which continuous wave laser light is used for heat treatment will be described with reference to FIG.

The laser processing apparatus 1e shown in FIG. 10 has a configuration common to the laser processing apparatus 1 shown in FIG. 1, and the same reference numerals are given to the common configuration, and description thereof is simplified or omitted.
In this embodiment, a multiplexing mirror 3e is arranged on the emission side of the laser oscillator 2 in place of the mirror 3a in FIG. The pulsed laser beam 2a output from the laser oscillator 2 is reflected on the reflection surface side (the lower surface side in the drawing) of the multiplexing mirror 3e and guided to the condenser lens 3b side. On the other hand, this embodiment further includes a CW laser oscillator 30 that outputs continuous-wave laser light. The CW laser oscillator 30 is connected to the control unit 12 in a controllable manner.

On the emission side of the CW laser oscillator 30, a mirror-3f is arranged. The continuous wave laser beam 30a output from the CW laser oscillator 30 is reflected by the mirror 3f, and then passes through the combining mirror 3e from the transmission surface side (the upper surface side in the drawing) of the combining mirror 3e, and then the pulsed laser beam 2a. And is condensed by the condenser lens 3b and irradiated to the object 100.
In the object 100 to be processed, the surface is melted in response to the rise of the pulse of the pulsed laser beam 2a as described in the above embodiments while being assisted by heating by the continuous wave laser beam 30a. This surface is irradiated with the reference light 10a in a pulse form from the reference light source 10, and the reflected light of the reference light is received by the camera 14 to monitor the surface of the object to be processed as described in the above embodiments. be able to.

Note that a method of using continuous wave laser light in combination with pulsed laser light can be applied to each of the above embodiments, and detailed description thereof is omitted.
In the above description, the continuous wave laser beam is combined with the pulsed laser beam to irradiate the object to be processed. However, different paths can be used without combining the pulsed laser beam and the continuous wave laser beam. In this case, the surface of the object to be processed may be irradiated. The irradiation position may be such that the pulsed laser beam and the continuous wave laser beam are completely overlapped on the surface of the object to be processed, and may be either partially overlapping or not overlapping.

In the embodiment in which the continuous wave laser beam is used for heat treatment, the continuous wave laser beam can be used as reference light and the reflected light can be used for monitoring. This form is demonstrated based on FIG.
The laser processing apparatus 1f shown in FIG. 11 has the same configuration as the laser processing apparatus 1d shown in FIG. 9, and the same reference numerals are given to the common configuration, and the description will be simplified or omitted.
In this embodiment, the CW laser oscillator 30 that irradiates the object 100 with the continuous wave laser beam 30a through a different path from the pulsed laser beam 2a is provided. The CW laser oscillator 30 is connected to the control unit 12 in a controllable manner.
A CW optical system 31 including a condensing lens 31a is provided in the emission direction of the continuous wave laser beam 30a of the CW laser oscillator 30, and the continuous wave laser beam 30a is guided by the CW optical system 31 to be pulsed. The surface of the object to be processed 100 is irradiated with the laser beam 2a, and the object 100 is subjected to heat treatment.

In addition, a reflected light shutter 22 to which a trigger signal generated by the control unit 12 and a pulse time width command are transmitted is disposed in the reflection direction of the reflected light 30b of the continuous wave laser light 30a. The camera 14 is disposed in the traveling direction of the reflected light 30b exceeding 22. As a result, the reflected light 30b is received by the camera 14 in a pulsed manner through the opening and closing of the reflected light shutter 22. In the light reception, as described above, the pulsed laser beam 2a has a start timing in the pulsed light reception with a predetermined phase difference, and the pulsed light reception is performed in a time shorter than the pulse time width of the pulsed laser beam 2a. As described in the above embodiments, the surface of the workpiece 100 can be monitored by receiving the reflected light 30b of the continuous wave laser beam 30a with the camera 14.
Therefore, the CW laser oscillator 30 also serves as a reference light optical system, the CW optical system 31 also serves as a reference light optical system, and the continuous wave laser light 30a also serves as reference light.

Also in this embodiment, the surface state of the object to be processed 100 can be grasped for each pulse in the transitional change of the molten state of the object to be processed 100, as in the above embodiments.
In this embodiment, the pulsed laser beam and the continuous wave laser beam are described as being irradiated onto the surface of the object to be processed by different paths. However, the pulsed laser beam and the continuous wave laser beam are combined. Even when heat treatment is performed, the surface of the object to be processed may be monitored using a reflected wave.

  As described above, the present invention has been described based on the above embodiments, but the present invention is not limited to the contents of the above embodiments, and appropriate modifications can be made without departing from the scope of the present invention. is there.

DESCRIPTION OF SYMBOLS 1, 1a, 1b, 1c, 1d, 1e, 1f Laser processing apparatus 2 Laser oscillator 2a Pulsed laser beam 3 Process optical system 3a Mirror 3b Condensing lens 3e Combined mirror 10 Reference light source 10a Reference light 10b Reflected light 11 Reference Optical optical system 11a Condensing lens 12 Controller 12a Phase adjuster 12b Time width adjuster 12c Transmission cable 14 Camera 15 Data processor with display unit 20 Reference light source 20a Reference light 20b Reflected light 21 Irradiation light shutter 22 Reflected light shutter 30 CW laser oscillator 30a Continuous oscillation laser light 30b Reflected light 31 CW optical system 100 Object 100a Irradiation region 110 Melting part 111 Non-melting part

Claims (23)

The surface of the object to be processed which is heated by the irradiation of the laser beam including the pulsed laser light is irradiated with the reference light, and the reference light is received by the reflected light reflected by the surface of the object to be processed. In the method of monitoring the surface condition,
The surface of the object to be processed is irradiated in a pulsed manner on the surface of the object to be processed in accordance with the pulse timing of the pulsed laser light, and a surface image of the object to be processed is obtained by receiving the reflected light. A method for monitoring the surface of an object to be processed, comprising monitoring the surface state of the object to be processed. The surface of the object to be processed which is heated by the irradiation of the laser beam including the pulsed laser light is irradiated with the reference light, and the reference light is received by the reflected light reflected by the surface of the object to be processed. In the method of monitoring the surface condition,
The reflected light is received in a pulse shape according to the pulse timing of the pulsed laser light, a surface image of the object to be processed is obtained by receiving the reflected light, and the surface state of the object to be processed is determined by the surface image. A method for monitoring the surface of an object to be processed, characterized by monitoring.   3. The surface of the object to be processed is heated by irradiating the surface of the object to be processed with a pulsed laser beam as the laser light including the pulsed laser light. The monitoring method of the to-be-processed object surface of description.   4. The method for monitoring the surface of an object to be processed according to claim 3, wherein the continuous wave laser beam is used as the reference beam.   Obtaining two-dimensional numerical data from the surface image, obtaining an optical constant that changes due to heating and melting of the object to be processed using the numerical data, and determining a melting state of the surface of the object to be processed from the constant The monitoring method of the to-be-processed object surface in any one of Claims 1-4 characterized by these.   At the time of pulsed irradiation of the reference light or pulsed light reception, the pulse time width in the irradiation or light reception is set to a predetermined time width smaller than the pulse time width of the pulsed laser light, and the pulsed laser light 6. The method for monitoring a surface of an object to be processed according to any one of claims 1 to 5, wherein the method is positioned so as to overlap the pulse time width.   At the time of pulsed irradiation of the reference light or pulsed light reception, the pulse time width in the irradiation or light reception is made shorter than the time during which the surface of the object to be processed is melted by the irradiation of the pulsed laser light. The monitoring method of the to-be-processed object surface in any one of Claims 1-6 characterized by these.   The pulsed irradiation or the pulsed light reception in the reference light is periodic having a pulse start timing having a predetermined phase difference with respect to a pulse start timing of the pulsed laser light. The monitoring method of the to-be-processed object surface in any one of Claims 1-7.   During the heat treatment of the object to be processed by the irradiation of the pulsed laser beam, the pulse starting timing of the pulsed irradiation or the pulsed light reception in the reference light is compared with the pulse starting timing of the pulsed laser beam. The method for monitoring the surface of the object to be processed according to any one of claims 1 to 8, wherein a surface image of the object to be processed at a plurality of phase differences is obtained by changing the phase difference.   10. The transient state in a continuous time sequence within a pulse is obtained by performing the pulsed irradiation or the pulsed light reception of the reference light with a plurality of the phase differences. Method for monitoring the surface of a workpiece.   2. The method for monitoring the surface of an object to be processed according to claim 1, wherein the object to be processed is irradiated in a pulsed manner by passing the reference light composed of continuous waves through a shutter that opens and closes intermittently.   3. The method for monitoring the surface of an object to be processed according to claim 2, wherein the object to be processed is irradiated with reference light comprising a continuous wave, and the reflected light is received in pulses through a shutter that opens and closes intermittently.   The method for monitoring a surface of an object to be processed according to claim 1, wherein the surface image is obtained by photographing with a camera having a recording time longer than a pulse time width of the pulsed laser light. . An apparatus for monitoring the surface state of an object to be heat-treated by irradiation with laser light including pulsed laser light,
A reference light source for generating reference light;
A reference light optical system that guides the reference light from the reference light source, and irradiates the object to be processed with the pulsed reference light according to the timing of the pulsed laser light;
A reflected light detection unit that detects reflected light reflected by the object to be processed heated by the reference light and acquires a surface image of the object to be processed;
And a reflected light optical system that guides the reflected light to the reflected light detection unit.   The apparatus for monitoring a surface of an object to be processed according to claim 14, wherein the reference light source emits pulsed reference light corresponding to a pulse timing of the pulsed laser light. The reference light source generates continuous wave reference light;
15. The irradiation light shutter according to claim 14, further comprising an irradiation light shutter that obtains pulsed reference light by intermittently passing the reference light through the reference light optical system according to a pulse timing of the pulsed laser light. Monitoring device for the surface of the workpiece. An apparatus for monitoring the surface state of an object to be heat-treated by irradiation with laser light including pulsed laser light,
A reference light source for generating reference light;
A reference light optical system for guiding the reference light from the reference light source and irradiating the object to be processed;
Reflected light detection for detecting a reflected light reflected by the object to be processed heated by the reference light as a pulsed reflected light corresponding to a pulse timing of the pulsed laser light and obtaining a surface image of the object to be processed And
And a reflected light optical system that guides the reflected light to the reflected light detection unit. The reference light source generates continuous wave reference light;
18. The reflected light optical system includes a reflected light shutter that intermittently passes the reflected light according to a pulse timing of the pulsed laser light to obtain pulsed reflected light. Monitoring device for the surface of the workpiece.   The monitoring apparatus for a surface of an object to be processed according to any one of claims 14 to 18, wherein the reference light source is a light source that generates continuous wave laser light for heat-treating the object to be processed.   The apparatus for monitoring a surface of an object to be processed according to any one of claims 14 to 19, further comprising a control unit that adjusts a pulse time width of the pulsed reference light or the pulsed reflected light.   21. The apparatus according to claim 14, further comprising a control unit that adjusts a phase difference between a pulse start timing of the pulsed reference light or the pulsed reflected light with respect to a pulse start timing of the pulsed laser light. The monitoring apparatus of the to-be-processed object surface.   The control unit is configured to change the phase difference during the heat treatment to enable irradiation of the pulsed reference light or reception of the pulsed reflected light at a plurality of phase differences. Item 21. The apparatus for monitoring the surface of an object to be processed according to Item 21.   The monitoring apparatus according to claim 14, further comprising a surface state determination unit that determines a surface state of the object to be processed based on a surface image acquired by the reflected light detection unit.

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