JP2013248656A - Laser beam irradiation method and laser beam irradiation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laser beam irradiation method and a laser beam irradiation device capable of stabilizing irradiation conditions of a laser beam even when a thermal lens effect generates in a laser optical system.SOLUTION: A laser beam irradiation device includes a laser oscillator 2 that outputs laser beams, a laser optical system 6 that converges laser beams output by the laser oscillator 2 to lead to a workpiece 10, a power meter 13 that detects the irradiation output of the laser beam that has passed the laser optical system 6, a camera 14 that detects the focal position of the laser beam that has passed the laser optical system 6, and a controller 3 that receives the detection result of the irradiation output of laser beam by the power meter 13 and the detection result of the focal position of laser beam by the camera 14, and performs a control based on the detection results to regulate the irradiation output of laser beam and the focal position of laser beam fill a predetermined condition respectively at the same time.

Description

  The present invention relates to a laser light irradiation method and a laser light irradiation apparatus for irradiating a workpiece with laser light through a laser optical system.

A laser beam irradiation apparatus using a high-power laser is used for wafer activation processing in a semiconductor manufacturing process. In such a laser beam irradiation apparatus, the laser beam is guided through an optical system including an optical member such as a lens. At this time, the laser beam passes through an optical member such as a lens constituting a laser optical system, and the optical member is heated by the laser beam, so that the focal position and the beam size of the irradiated laser beam change. The phenomenon of effect occurs. When the thermal lens effect occurs, the irradiation condition of the laser beam on the object to be processed changes as a result.
Therefore, in order to stabilize the laser light irradiation conditions by the laser light irradiation device, the focal position and beam size of the laser light changed by the thermal lens effect are adjusted, and the irradiation conditions such as the focal position and beam size are fixed. It is desirable to keep Until now, as a technique for suppressing the change in the irradiation condition of the laser beam due to the thermal lens effect, for example, those proposed in Patent Documents 1 and 2 are known.

FIG. 5 is a schematic view showing a conventional laser processing apparatus described in Patent Document 1. As shown in FIG.
The laser oscillator 101 includes an optical resonator 102 having a rear mirror 103 and an output mirror 104. A workpiece 109 is disposed on the optical path of the laser beam output from the output mirror 104 of the laser oscillator 101 via a collimation optical system 105 and a condensing optical system 108 in order. The collimation optical system 105 includes collimation lenses 106 and 107, and one collimation lens 107 is provided with a drive stage 110 that moves the collimation lens 107. Further, a half mirror 111 is disposed between the collimation optical system 105 and the condensing optical system 108.
On the reflection side of the half mirror 111, half mirrors 112 and 113 for reflecting and branching a part of the laser beam reflected by the half mirror 111 are arranged. The half mirrors 112 and 113 are provided with power meters 114 and 115 on which the laser beams branched by the half mirrors 112 and 113 are incident, respectively.
The power meters 114 and 115 are connected to a feedback circuit 116 that controls the amount of movement of the collimation lens 107 by the drive stage 110 based on the measurement result of the incident power of the laser beam by the power meters 114 and 115.

  In the laser processing apparatus, when the focal position of the laser beam irradiated to the workpiece 109 changes due to the thermal lens effect, the change in the focal position is branched by the half mirror 111 and the half mirrors 112 and 113 to be the power meter 114. , 115 is detected in the form of a change in the incident power of the laser beam incident on 115. The feedback circuit 116 feeds back the movement amount of the collimation lens 307 so as to correct the change in incident power detected by the power meters 114 and 115, and the collimation lens 107 is moved by the drive stage 110 by the movement amount. Thus, the focal position of the laser beam irradiated on the workpiece 109 is corrected.

FIG. 6 is a schematic diagram showing a conventional laser processing apparatus described in Patent Document 2.
As shown in the figure, the laser oscillator 201 includes an optical resonator 202 having a rear mirror 203 and an output mirror 204. A workpiece 209 is disposed on the optical path of the laser beam output from the output mirror 204 of the laser oscillator 201 via a collimation optical system 205 and a condensing optical system 208 in sequence. The collimation optical system 205 includes collimation lenses 206 and 207, and one collimation lens 207 is provided with a drive stage 210 that moves the collimation lens 207.
Further, the lens barrel 211 that holds the condensing optical system 208 is provided with a half mirror 212 that branches a very small part of the outside of the laser beam incident on the condensing optical system 208. The laser beam branched by the half mirror 212 is incident on a power meter 215 provided in the laser processing apparatus.
A feedback circuit 214 is connected to the power meter 215, and the feedback circuit 214 controls the amount of movement of the collimation lens 207 by the drive stage 210 based on the measurement result of the incident power of the laser beam by the power meter 215.

  In the laser processing apparatus, when the beam size of the laser beam applied to the workpiece 209 changes due to the thermal lens effect, the change in the beam size is branched by the half mirror 212 and incident on the power meter 215. It is detected in the form of a change in incident power. In the feedback circuit 214, the position of the collimation lens 207 is feedback-controlled by the drive stage 210 so as to correct the change in incident power detected by the power meter 215.

JP-A-7-185860 Japanese Patent Laid-Open No. 7-185861

In each of the conventional laser processing apparatuses described above, changes in the focal position and beam size of the laser light due to the thermal lens effect are detected in the form of changes in the power of the laser light. For this reason, for example, when there is a change in the power of the laser beam irradiated due to factors other than the thermal lens effect, such as a decrease in the transmittance of the lens, the device may malfunction, and the laser beam irradiation conditions are stabilized. It is difficult to make.
In addition, measuring the irradiation beam profile and adjusting the focal position and size by moving the lens has been performed in the past. However, moving the lens changes the efficiency of the optical system, which changes the laser irradiation output and thermal lens effect. The state can also change and it is equally difficult to stabilize the irradiation conditions of the device.

  The present invention has been made against the background of the above circumstances, and an object thereof is to provide a laser light irradiation method and a laser light irradiation apparatus capable of stabilizing the laser light irradiation conditions.

That is, among the laser light irradiation methods of the present invention, the first present invention is a laser light irradiation method for condensing laser light through a laser optical system and irradiating the object to be processed,
Detecting an irradiation output of the laser light irradiated to the object to be processed and a focal position of the laser light irradiated to the object to be processed;
Based on the detection result of the laser beam irradiation output and the focal position of the laser beam, the laser beam irradiation output and the focal position of the laser beam are adjusted so as to satisfy a predetermined condition simultaneously. To do.

  The laser light irradiation method according to the second aspect of the present invention is the laser light irradiation method according to the first aspect of the present invention, in addition to the irradiation output of the laser light and the focal position of the laser light. The size is detected, and based on the detection result of the laser beam irradiation output, the laser beam focal position, and the laser beam beam size, the laser beam irradiation output, the laser beam focal position, and the laser beam The light beam size is adjusted so as to satisfy a predetermined condition at the same time.

  The laser beam irradiation method of the third aspect of the present invention is characterized in that, in the first or second aspect of the present invention, the focal position of the laser beam is adjusted by adjusting the laser optical system.

  The laser beam irradiation method of the fourth aspect of the present invention is characterized in that, in the second aspect of the present invention, the beam size of the laser beam is adjusted by adjusting the laser optical system.

  In the laser beam irradiation method of the fifth aspect of the present invention, in any one of the first to fourth aspects of the present invention, the adjustment of the laser beam irradiation output includes an output adjustment of a laser beam output source from which the laser beam is output and The adjustment is performed by one or both of the adjustment of the light amount of the laser beam output from the laser beam output source.

A laser beam irradiation apparatus according to a sixth aspect of the present invention includes a laser beam output source that outputs a laser beam,
A laser optical system that focuses the laser light output from the laser light output source and guides the laser light to an object to be processed;
An irradiation output detection unit for detecting an irradiation output of the laser beam irradiated to the object to be processed;
A focal position detection unit for detecting a focal position of the laser beam irradiated to the object to be processed;
Upon receiving the detection result of the laser beam irradiation output by the irradiation output detection unit and the detection result of the focal position of the laser beam by the focal position detection unit, and based on each detection result, And a control unit that performs control to adjust the focal position of the laser beam so as to satisfy a predetermined condition at the same time.

A laser beam irradiation apparatus according to a seventh aspect of the present invention includes, in the sixth aspect of the present invention, a beam size detection unit that detects a beam size of the laser beam irradiated onto the object to be processed.
The control unit includes the detection result of the irradiation output of the laser beam by the irradiation output detection unit, the detection result of the focal position of the laser beam by the focal position detection unit, and the laser beam by the beam size detection unit. The laser beam irradiation output, the laser beam focal position, and the laser beam beam size are adjusted to satisfy the predetermined conditions at the same time based on the respective detection results. It is characterized by performing control to perform.

  According to an eighth aspect of the present invention, in the seventh aspect of the present invention, the focal position detection unit and the beam size detection unit perform the respective detections using the same beam profile by the laser beam. It is characterized by being.

  According to a ninth aspect of the present invention, in the sixth aspect of the present invention, the control unit adjusts the focal position of the laser light by controlling adjustment of the laser optical system. Features.

  According to a tenth aspect of the present invention, in the seventh or eighth aspect of the present invention, the control unit adjusts the beam size of the laser light by controlling adjustment of the laser optical system. It is characterized by being.

According to an eleventh aspect of the present invention, in the tenth aspect of the present invention, the laser optical system has a condensing member at an emission end.
The said control part controls the said adjustment by the position change of the said condensing member, It is characterized by the above-mentioned.

In the laser beam irradiation apparatus of the twelfth aspect of the present invention according to the eleventh aspect of the present invention, the laser optical system has a telescope on the incident side front side of the condensing member,
The control unit controls the adjustment by changing a position of the telescope.

A laser beam irradiation apparatus according to a thirteenth aspect of the present invention includes the variable attenuator according to any one of the sixth to twelfth aspects of the present invention, which can adjust the attenuation rate of the laser beam output from the laser beam output source. And
The control unit adjusts the irradiation output of the laser light by controlling one or both of output adjustment of the laser light output source and adjustment of the attenuation factor of the laser light by the variable attenuator. .

  The type of the laser light output source of the present invention is not particularly limited, but can be appropriately selected according to the processing content to be subjected to laser irradiation. For example, the laser light output source may be either a continuous oscillation output source or a pulse oscillation output source, and the laser oscillation medium is also particularly limited.

In addition, the laser optical system that condenses the laser light and guides it to the object to be processed is not particularly limited, and an optical member such as a lens, a mirror, or a homogenizer may be used depending on the required laser light irradiation conditions. It can select suitably and can comprise.
For example, the laser optical system can be provided with a condensing member that condenses the laser light on the object to be processed at least at the emission end thereof, and further, the laser beam is distributed in a desired intensity distribution on the incident front side of the condensing member. It is possible to provide a telescope that is deformed into a shape. The telescope is not required to be positioned immediately before the light collecting member.

  The focal position adjustment of the laser beam and the beam size adjustment of the laser beam can be performed by adjusting the laser optical system. The adjustment of the laser optical system can be performed, for example, by adjusting the position and direction of a lens and other optical members constituting the laser optical system.

  Further, the adjustment of the irradiation output of the laser beam irradiated to the object to be processed is, for example, one of the output adjustment of the laser beam output source from which the laser beam is output and the adjustment of the light amount of the laser beam output from the laser beam output source or It can be done by both. The amount of laser light can be adjusted, for example, by adjusting the attenuation rate of the laser light with a variable attenuator.

  The irradiation output detection unit that detects the irradiation output of the laser beam is not particularly limited as long as it can measure the irradiation output of the laser beam, but can be configured by a power meter, for example. Although the measurement position is not particularly limited, it is desirable to perform measurement at a position where an irradiation output that is the same as or approximately the same as the laser beam applied to the object to be processed is obtained. As a result, a measurement result that is the same as or close to the irradiation output of the laser light that is actually irradiated onto the irradiated object can be obtained. Even when a measurement result different from the actual irradiation output is obtained, it is possible to know the actual irradiation output by grasping the correlation between the measurement result and the actual irradiation output.

  Further, the configuration of the focal position detection unit that detects the focal position of the laser beam is not particularly limited as long as the focal position of the laser beam can be measured. For example, the beam profile can be measured using a camera capable of imaging. The focal position of the laser beam can be detected by observing the beam profile. At that time, the focal position may be measured by moving the camera along the optical axis direction of the laser beam. The measurement position of the focal position of the laser beam is not particularly limited in the present invention, and the measurement position is not limited as long as the focal position of the laser beam irradiated to the object to be processed can be grasped as a result.

  The beam size detector for detecting the beam size of the laser beam is not particularly limited as long as the beam size of the laser beam can be measured. A camera or the like that can capture the beam profile of the laser beam can be used. The focal position and beam size of the laser light can be measured using the same beam profile acquired by a camera or the like. The measurement location of the laser beam beam size is not particularly limited in the present invention, and the measurement position is not limited as long as the beam size of the laser beam irradiated to the object to be processed can be grasped as a result.

The above-described adjustment of the laser beam irradiation output, the focal position, and the beam size can be performed under the control of the control unit. The control unit has, for example, a CPU and a program for operating the CPU as a main component, a ROM storing the program, a RAM serving as a work area, a non-volatile flash memory storing the reference value of the irradiation condition described above, and the like It can be configured with a storage unit.
The control unit receives the detection result of the laser light irradiation output and the focal position, or the detection result of the laser light beam size in addition to the above, and based on the detection result, the laser light irradiation output and the focal position are Alternatively, in addition to these, control is performed so that the beam size is adjusted to satisfy a predetermined condition at the same time.

For example, the control unit can adjust the focal position of the laser beam and the beam size of the laser beam by controlling the adjustment of the laser optical system.
The adjustment of the laser beam irradiation output can be performed by adjusting the output of the laser beam output source or adjusting the attenuation factor of the laser beam by a variable attenuator, and can be performed by either one or both. The irradiation output can be adjusted based on a predetermined standard. For example, the irradiation output can be adjusted based on the integrated value of energy or the maximum value of energy, and the present invention is not limited to a specific standard.

  As described above, according to the present invention, a laser light irradiation method for condensing laser light through a laser optical system and irradiating the object to be processed, the irradiation output of the laser light irradiating the object to be processed And the focal position of the laser beam irradiated to the object to be processed, and based on the detection result of the laser beam irradiation output and the laser beam focal position, the laser beam irradiation output, Since the focal positions of the laser beams are adjusted so that the predetermined conditions are satisfied simultaneously, it is possible to stabilize the irradiation conditions of the laser beams including the case where the thermal lens effect occurs in the laser optical system.

It is the schematic which shows the laser beam irradiation state in the laser beam irradiation apparatus of one Embodiment of this invention. Similarly, it is the schematic which shows the adjustment state of the laser beam irradiation conditions in a laser beam irradiation apparatus. Similarly, it is a flowchart showing a procedure for adjusting a laser beam irradiation condition in the laser beam irradiation method. It is a flowchart which shows the adjustment procedure of the irradiation condition of the laser beam in the laser beam irradiation method of other embodiment of this invention. It is the schematic which shows an example of the conventional laser processing apparatus. It is the schematic which shows the other example of the conventional laser processing apparatus.

An embodiment of the present invention will be described with reference to FIGS.
The laser beam irradiation apparatus 1 includes a laser oscillator 2 corresponding to the laser beam output source of the present invention that outputs a laser beam. The laser oscillator 2 can adjust the output of the laser beam by adjusting the amount of injected gas and the discharge voltage. As the laser oscillator 2, for example, a gas excitation pulse oscillation output source can be used. However, the present invention is not limited to this, and may be a continuous oscillation output source, and the laser output medium is not limited to gas.

  The laser oscillator 2 is controllably connected to a control unit 3 that controls the entire laser light irradiation apparatus 1, and the output of the laser oscillator 2 can be adjusted by the control unit 3. The control unit 3 can be configured by a CPU, a program that operates the CPU, a storage unit that includes a nonvolatile memory, and the like. In the storage unit, it is possible to store in advance predetermined conditions relating to the irradiation output of the laser light to be adjusted by the present invention, the focal position of the laser light, the beam size of the laser light, and the like. The predetermined condition may be the laser beam irradiation output, the focal position of the laser beam, the beam size of the laser beam, or the like, or may be a numerical value associated with these.

A variable attenuator 5 capable of adjusting the transmission attenuation factor of the laser beam 4 is disposed on the optical path along which the laser beam 4 output from the laser oscillator 2 travels. The configuration of the variable attenuator 5 is not particularly limited, and a known one can be used.
The variable attenuator 5 is controllably connected to the control unit 3, and the control unit 3 can adjust the attenuation rate of the laser light 4 in the variable attenuator 5, that is, the light quantity of the transmitted laser light 4.

  On the optical path on the emission side of the variable attenuator 5, a laser optical system 6 that performs beam shaping, deflection, and condensing of the laser light 4 is provided. In this embodiment, the laser optical system 6 includes a lens 60, a telescope 61, a condenser lens 62, and the like from the incident end side. However, the configuration of the present invention is not particularly limited.

The telescope 61 is attached to a drive unit 63 that enables the telescope 61 to move along the optical path of the laser light 4. The condenser lens 62 is attached to a drive unit 64 that allows the condenser lens 62 to move along the optical path of the laser light 4.
The drive units 63 and 64 are connected to the control unit 3 in a controllable manner, and the control unit 3 controls the drive unit 63 so that the position of the telescope 61 can be adjusted. Thus, the position of the condenser lens 62 can be adjusted.

On the emission side of the laser optical system 6, a beam splitter 7 is disposed on the optical path of the laser light 4 to reflect and extract a part of the laser light 4. On the transmission side of the beam splitter 7 through which most of the laser light 4 is transmitted, an opening 8 is disposed, and a stage 9 that can be moved horizontally is disposed so that the stage 9 can be positioned in the transmission direction. The opening 8 is provided in a mask (not shown) that shapes the beam cross-sectional shape of the laser light 4.
An object 10 to be irradiated with the laser beam 4 is placed on the stage 9. The stage 9 can irradiate the workpiece 10 while scanning the laser beam 4, and when adjusting the irradiation condition of the laser beam 4, so as not to interfere with a power meter 13 and a camera 14 described later. A moving device (not shown) is provided so as to be movable in a horizontal plane. In this embodiment, when adjusting the irradiation condition of the laser beam 4, the irradiation of the laser beam to the object to be processed 10 is stopped and the stage 9 is moved in the lateral direction to be retracted. It is also possible to configure so that the irradiation condition of the laser beam 4 can be adjusted while performing the laser beam irradiation.

  In the reflection direction in which a part of the laser beam 4 is reflected by the beam splitter 7, a mirror 11 that reflects the laser beam 4 a reflected by the beam splitter 7 downward is disposed. A horizontally movable shutter 12 is disposed below the mirror 11. When the laser beam 4 is irradiated on the workpiece 10, the shutter 12 is positioned in the reflection direction of the mirror 11 to close the optical path of the reflected light on the mirror 11 and adjust the irradiation condition of the laser beam 4. First, the optical path of the laser beam 4a reflected by the mirror 11 is opened by retracting from the reflection direction of the mirror 11 to the side. The movement of the shutter 12 can be controlled by the control unit 3.

  On the side of the stage 9, a power meter 13 and a camera 14 are arranged so as to be movable in the horizontal direction. The power meter 13 corresponds to the irradiation output detection unit of the present invention, and the camera 14 constitutes a part of the focus position detection unit and the beam size detection unit of the present invention.

  As shown in FIG. 2, when adjusting the irradiation condition of the laser beam 4, the power meter 13 moves on the optical path of the laser beam 4 that has passed through the opening 8, receives the laser beam 4, and outputs its irradiation. Is detected. Although the light receiving surface of the power meter 13 is at a position slightly lower than the irradiation surface of the object to be irradiated 10, measurement on the irradiation surface of the object to be processed 10 can be performed. By obtaining a correlation between the measurement result and the irradiation output on the irradiation surface in advance, the irradiation output on the irradiation surface can be determined from the measurement result and adjusted to a predetermined condition of the irradiation output. In addition, appropriate predetermined conditions can be determined based on the measurement result at the measurement position. The power meter 13 is connected to the control unit 3 so that the detection result of the irradiation output of the laser beam 4 can be transmitted.

As shown in FIG. 2, when adjusting the irradiation condition of the laser beam 4, the camera 14 moves on the optical path in the reflection direction of the mirror 11 and photographs the beam profile of the laser beam 4 a reflected by the mirror 11. . The camera 14 is connected to the control unit 3 so as to transmit the observation result of the beam profile of the laser beam 4a. The camera 14 is disposed at a position substantially coincident with the irradiation surface to the object 10 in consideration of the optical path length that has passed through the splitter 7 and the mirror 11. Thereby, the beam profile imaged with the camera 14 becomes substantially the same as on the irradiation surface.
The power meter 13 and the camera 14 are connected to a drive unit 15 that can move these in the horizontal direction. The drive unit 15 is connected to the control unit 3 in a controllable manner, and the power meter 13 and the camera 14 move integrally between the measurement position and the retracted position under the control of the control unit 3.

Next, the procedure for adjusting the irradiation condition of the laser beam 4 in the laser beam irradiation apparatus 1 will be described with reference to the flowchart shown in FIG. The adjustment procedure of the irradiation conditions is executed by the control unit 3.
The object to be processed 10 is not particularly limited in type, application, or the like. For example, a semiconductor wafer such as a silicon wafer into which a dopant is introduced by ion implantation or the like can be used. In this case, the semiconductor wafer is irradiated with the laser beam 4 to activate the dopant.

  In the laser beam irradiation apparatus 1, the laser beam irradiation output, the focal position, and the beam size are set as the irradiation conditions of the laser beam 4. The adjustment of the irradiation condition of the laser beam 4 can be performed when the laser beam irradiation apparatus 1 is installed, every predetermined time, or every number of processing lots. The frequency and opportunity are not particularly limited in the present invention.

First, the laser beam irradiation apparatus 1 collects calibration data indicating the relationship between the variable attenuator 5 and the laser beam irradiation output (step s1).
Calibration data can be collected using the power meter 13. At this time, the laser optical system 6 is adjusted so that the processing object is irradiated with the laser light 4 at a predetermined focal position and beam size. The laser optical system 6 can be adjusted by observing a beam profile using the camera 14 as will be described later.

  When collecting the calibration data, the stage 9 is retracted from the irradiation position of the laser beam 4, and the power meter 13 is moved horizontally by the driving unit 15 to be positioned on the emission side of the opening 8. In this state, the laser beam 4 is output from the laser oscillator 2, and the laser beam 4 transmitted through the opening 8 through the optical system 6 is incident on the power meter 13. The measurement result of the power meter 13 is transmitted to the control unit 3. At this time, the control unit 3 can obtain calibration data relating to the irradiation output P by associating the adjustment of the variable attenuator 5 with the result measured by the power meter 13.

Next, an irradiation output reference value (P ₀ ) is set (step s2). The irradiation output reference value (P ₀ ) may be set at this time, or a predetermined condition relating to the irradiation output stored in the storage unit or the like may be read and set.
Subsequently, the attenuation rate of the variable attenuator 5 is adjusted by the control unit 3 so that the irradiation output P of the laser beam 4 becomes the set reference value P ₀ (step s3), and the irradiation output P of the laser beam 4 is adjusted. To do. In place of or together with the adjustment of the attenuation factor of the variable attenuator 5, the control unit 3 adjusts the output of the laser oscillator 2 so that the irradiation output P of the laser beam 4 is adjusted. Good.

Next, the irradiation output P of the laser beam 4 is measured by the power meter 13 (step s4), and the measurement result is transmitted to the control unit 3. The control unit 3 determines whether irradiation output P which is measured by the power meter 13 is in the reference value P ₀ (step s5). If not become irradiation power P is the reference value _{P 0} (step s5, No), the process returns to step s1, the above procedure is repeated.

On the other hand, it is determined in step s5, when the irradiation power P is determined to have become the reference value P ₀ (step s5, Yes), taken out by the beam splitter 7, the beam of the laser beam 4a reflected by the mirror 11 The profile is imaged by the camera 4 and transmitted to the control unit 3 to observe the beam profile (step s6). At this time, the shutter 12 is opened.
The camera 14 is located at the measurement position when the power meter 13 is moved by the driving unit 15, and can acquire a beam profile together with the measurement of the irradiation output by the power meter 13 or immediately after the measurement.

The control unit measures the focal position of the laser beam 4 based on the observation of the beam profile (step s7). The method for measuring the focal position is not particularly limited, and the focal position is estimated from the beam size, or the position where the beam size is minimized is determined as the focal position by moving the camera 14 along the optical path. be able to.
Next, it is determined whether the focal position is a reference value (Z ₀ ) (step s8). For example, the predetermined condition of the focal position is stored in advance in a storage unit or the like, and the above determination can be made by reading this and comparing it with the observation result.

If the focal position is the reference value (Z ₀ ) (step s8, Yes), the laser beam irradiation output and the focal position satisfy the predetermined condition at the same time, and thus the process is terminated.
If the focal position is not the reference value (Z ₀ ) (step s8, No), the driving lens 64 moves the condenser lens 62 along the optical path while observing the beam profile with the camera 14 and the controller 3. The position of the condenser lens 62 is adjusted so that the focal position becomes the reference value (Z ₀ ) (step s9). The amount of movement at this time can be adjusted based on this correlation by obtaining a correlation with the amount of shift of the focal position in advance. Further, in the loop of steps s7 to s9, after the focal position reaches the reference value (Z ₀ ), the process may move to step s5.

Next, based on the measurement by the power meter 13, it is determined whether the irradiation output is a reference value (P ₀ ) (step s5). If the irradiation output is the reference value (P ₀ ) (step s5, Yes), the beam position is observed (step s6), the focus position is measured (step s7), and the focus position is determined (step s8). Satisfies the reference value (Z ₀ ), the process is terminated. If it is determined that the irradiation output is not the reference value (P ₀ ) after the focus position adjustment (No in step s5), the procedure returns to the irradiation output calibration (step s1), and the procedure of irradiation output adjustment and focus adjustment is repeated. When the laser beam irradiation output and the focal position satisfy a predetermined condition at the same time, the process is terminated.

  According to this embodiment, even when the laser beam fluctuates due to the influence of the thermal lens effect, the irradiation condition is optimized by setting the laser beam irradiation output and the focal position to predetermined conditions in a short time. In addition, it is possible to perform laser beam irradiation on the object to be processed while maintaining optimized irradiation conditions.

  After performing the process of adjusting the irradiation condition of the laser beam 4, the power meter 13 and the camera 14 are returned to the retracted position, and the stage 9 on which the workpiece 10 is placed is irradiated with the laser beam 4 from the retracted position. Moved to position. After the stage 9 is moved to the irradiation position, the object 10 on the stage 9 is irradiated with the laser beam 4 under the adjusted irradiation conditions, and a desired process is performed. Thereby, it becomes possible to perform processing in a stable state, and a stable state can be maintained for a long period of time by appropriately adjusting the irradiation condition of the laser light 4 appropriately.

Next, the procedure of other forms of adjustment processing will be described with reference to the flowchart of FIG.
In the processing shown in the flow of FIG. 3, the adjustment condition is that the irradiation condition of the laser beam and the focus position satisfy the predetermined condition at the same time. The adjustment may be performed as described above. This will be described below.

Note that the steps s1 to s8 of this embodiment have the same contents as the steps s1 to s8 of the procedure of FIG. 3, and the description thereof will be simplified and will be described in order below.
First, in the laser beam irradiation apparatus 1, calibration data indicating the relationship between the variable attenuator 5 and the laser beam irradiation output is collected (step s1).
Next, an irradiation output reference value (P ₀ ) is set (step s2).
Subsequently, the attenuation rate of the variable attenuator 5 is adjusted by the control unit 3 so that the irradiation output P of the laser beam 4 becomes the set reference value P ₀ (step s3), and the irradiation output P of the laser beam 4 is adjusted. Is done. In place of or together with the adjustment of the attenuation factor of the variable attenuator 5, the control unit 3 adjusts the output of the laser oscillator 2 so that the irradiation output P of the laser beam 4 is adjusted. Good.

Next, the irradiation output P of the laser beam 4 is measured by the power meter 13 (step s4), and the measurement result is transmitted to the control unit 3. The control unit 3 determines whether irradiation output P which is measured by the power meter 13 is in the reference value P ₀ (step s5). If not become irradiation power P is the reference value _{P 0} (step s5, No), the process returns to step s1, the above procedure is repeated.

On the other hand, it is determined in step s5, when the irradiation power P is determined to have become the reference value P ₀ (step s5, Yes), taken out by the beam splitter 7, the beam of the laser beam 4a reflected by the mirror 11 The profile is photographed by the camera 4 and transmitted to the control unit 3 to observe the beam profile (step s6).
The camera 14 is located at the measurement position when the power meter 13 is moved by the driving unit 15, and can acquire a beam profile together with the measurement of the irradiation output by the power meter 13 or immediately after the measurement.

The control unit 3 measures the focal position of the laser beam 4 based on the observation of the beam profile (step s7). Next, it is determined whether the focal position is a reference value (Z ₀ ) (step s8). When the focus position is the reference value (Z ₀ ) (step s8, Yes), the beam size (S) is further measured (step s10). The measurement of the beam size can be determined by the control unit 3 using the beam profile acquired by the camera 14. That is, with the same configuration, measurement of the focal position of the laser beam and measurement of the beam size can be performed.
Next, it is determined whether the beam size S is the reference value (S ₀ ) (step s11).
For example, the predetermined condition of the beam size is stored in advance in a storage unit or the like, and can be determined by reading this and comparing it with the measurement result. When the beam size satisfies the reference value (S ₀ ) ( In step s11, Yes), since the irradiation output of the laser beam, the focal position, and the beam size satisfy the predetermined conditions at the same time, the processing is terminated.

On the other hand, if the focal position is not the reference value (Z ₀ ) in step s8 (No in step s8), the condensing lens 62 is placed on the optical path by the driving unit 64 while observing the beam profile with the camera 14 and the control unit 3. The position of the condenser lens 62 is adjusted so that the focal position becomes the reference value (Z ₀ ) (from step s9 to steps s7 and 8).

On the other hand, when the beam size is not the reference value (S ₀ ) in step s11 (No in step s11), the camera 14 and the control unit 3 observe the beam profile, and the driving unit 63 moves the telescope 61 along the optical path. The position of the telescope 61 is adjusted so that the beam size becomes the reference value (S ₀ ) (step s12). The movement amount at this time can be adjusted based on the correlation obtained in advance by obtaining a correlation with the deviation of the beam size. Further, in the loop of steps s10 to s12, after the beam size reaches the reference value (S ₀ ), the process may move to step s5.

Next, based on the measurement by the power meter 13, it is determined whether the irradiation output is a reference value (P ₀ ) (step s5). If the irradiation output is a reference value (P ₀ ) (step s5, Yes), beam profile observation (step s6), focal position measurement (step s7), focal position determination (step s8), beam size measurement ( After step s10) and beam size determination (step s11), since the focal position satisfies the reference value (Z ₀ ) and the beam size satisfies the reference value (S ₀ ), the process is terminated.

If it is determined that the irradiation output is not the reference value (P ₀ ) after the focus position adjustment and the beam size adjustment (No in step s5), the process returns to the irradiation output calibration (step s1), and the irradiation output adjustment, the focus adjustment, The procedure for adjusting the beam size is repeated, and the processing ends when the irradiation output of the laser beam, the focal position, and the beam size satisfy predetermined conditions at the same time.

  After performing the process of adjusting the irradiation condition of the laser beam 4, the power meter 13 and the camera 14 are returned to the retracted position, and the stage 9 on which the workpiece 10 is placed is irradiated with the laser beam 4 from the retracted position. Moved to position. After the stage 9 is moved to the irradiation position, the object 10 on the stage 9 is irradiated with the laser beam 4 under the adjusted irradiation conditions, and a desired process is performed. By doing so, it becomes possible to perform processing in a stable state, and by adjusting the irradiation condition of the laser light 4 appropriately as occasion demands, a stable state can be maintained for a long period of time.

  In the present embodiment, it is possible to further optimize the irradiation condition by setting the irradiation output and focal position of the laser beam and the beam size to predetermined conditions in a short time, and to maintain the further optimized irradiation condition. Thus, the laser beam can be irradiated to the object to be processed.

  In each embodiment, when the dopant is activated by irradiating the semiconductor wafer into which the dopant is introduced as the object 10 to be activated, the irradiation output is kept constant as described above. By irradiating the semiconductor wafer with laser light, the sheet resistance value of the semiconductor wafer can be maintained at the reference value. Further, by irradiating the wafer with laser light while maintaining the bead size constant as described above, the sheet resistance value of the semiconductor wafer can be more reliably maintained at the reference value. Moreover, the uniformity of the sheet resistance value of the semiconductor wafer in which the dopant is activated can be improved by irradiating the laser beam while keeping the focal position constant as described above.

  As mentioned above, although this invention was demonstrated based on the said embodiment, this invention is not limited to the content of the said description, As long as it does not deviate from the range of this invention, an appropriate change is possible.

DESCRIPTION OF SYMBOLS 1 Laser beam irradiation apparatus 2 Laser oscillator 3 Control part 4 Laser beam 4a Laser beam 5 Variable attenuator 6 Laser optical system 60 Lens 61 Telescope 62 Condensing lens 63 Drive part 64 Drive part 7 Beam splitter 8 Aperture part 9 Stage 10 Subject Processing body 11 Mirror 12 Shutter 13 Power meter 14 Camera 15 Drive unit

Claims (13)

A laser irradiation method for condensing laser light through a laser optical system and irradiating the object to be processed,
Detecting an irradiation output of the laser light irradiated to the object to be processed and a focal position of the laser light irradiated to the object to be processed;
Based on the detection result of the laser beam irradiation output and the focal position of the laser beam, the laser beam irradiation output and the focal position of the laser beam are adjusted so as to satisfy a predetermined condition simultaneously. Laser beam irradiation method.   Along with the irradiation output of the laser light and the focal position of the laser light, the beam size of the laser light irradiated on the object to be processed is further detected, the irradiation output of the laser light, the focal position of the laser light, and the Based on the detection result of the beam size of the laser beam, the irradiation output of the laser beam, the focal position of the laser beam, and the beam size of the laser beam are adjusted so as to satisfy a predetermined condition simultaneously. The laser beam irradiation method according to claim 1.   The laser beam irradiation method according to claim 1, wherein the focal position adjustment of the laser beam is performed by adjusting the laser optical system.   The laser beam irradiation method according to claim 2, wherein the laser beam beam size is adjusted by adjusting the laser optical system.   The irradiation output adjustment of the laser beam is performed by one or both of an output adjustment of a laser beam output source from which the laser beam is output and an adjustment of the light amount of the laser beam output from the laser beam output source. The laser beam irradiation method according to claim 1. A laser beam output source for outputting a laser beam;
A laser optical system that focuses the laser light output from the laser light output source and guides the laser light to an object to be processed;
An irradiation output detection unit for detecting an irradiation output of the laser beam irradiated to the object to be processed;
A focal position detection unit for detecting a focal position of the laser beam irradiated to the object to be processed;
Upon receiving the detection result of the laser beam irradiation output by the irradiation output detection unit and the detection result of the focal position of the laser beam by the focal position detection unit, and based on each detection result, And a control unit that performs control to adjust the focal position of the laser beam so as to satisfy a predetermined condition at the same time. A beam size detection unit for detecting a beam size of the laser light irradiated on the object to be processed;
The control unit includes the detection result of the irradiation output of the laser beam by the irradiation output detection unit, the detection result of the focal position of the laser beam by the focal position detection unit, and the laser beam by the beam size detection unit. The laser beam irradiation output, the laser beam focal position, and the laser beam beam size are adjusted to satisfy the predetermined conditions at the same time based on the respective detection results. The laser beam irradiation apparatus according to claim 6, wherein the control is performed.   The laser beam irradiation apparatus according to claim 7, wherein the focus position detection unit and the beam size detection unit perform the detection using the same beam profile by the laser beam.   The laser light irradiation apparatus according to claim 6, wherein the control unit adjusts a focal position of the laser light by controlling adjustment of the laser optical system.   9. The laser beam irradiation apparatus according to claim 7, wherein the control unit adjusts a beam size of the laser beam by controlling adjustment of the laser optical system. The laser optical system has a condensing member at the exit end,
The laser light irradiation apparatus according to claim 10, wherein the control unit controls the adjustment by changing a position of the light collecting member. The laser optical system has a telescope on the incident side front side of the light collecting member,
The laser beam irradiation apparatus according to claim 11, wherein the control unit controls the adjustment by changing a position of the telescope. A variable attenuator capable of adjusting the attenuation rate of the laser beam output from the laser beam output source;
The control unit adjusts the irradiation output of the laser light by controlling one or both of output adjustment of the laser light output source and adjustment of the attenuation factor of the laser light by the variable attenuator. The laser beam irradiation apparatus according to claim 6.

Images