JP2006049606A - Laser beam machining equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a laser beam machining equipment that can suppress the variation in light intensity distribution in the cross section of each laser beam to be radiated to an object to be machined. <P>SOLUTION: The laser beam machining equipment comprises a laser light source 1 for radiating laser beams, a spread angle adjuster 3 for changing a spread angle of laser beams radiated from the above laser light source, a measuring instrument 9 for measuring the light intensity distribution in a section of laser beams radiated from the above spread angle adjuster, and a controller 10 for controlling the above spread angle adjuster so that the light intensity distribution can approach to a desired distribution based on the light intensity distribution measured by the above measuring instrument 9. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a laser processing apparatus, and more particularly to a laser processing apparatus that can adjust a light intensity distribution in a cross section of a laser beam emitted from a laser light source.

  For example, laser annealing for polycrystallizing an amorphous silicon film is performed on a substrate having an amorphous silicon film formed thereon by repeating irradiation of an excimer laser pulse. The amorphous silicon film is temporarily melted by laser irradiation, and polycrystallization is performed. The substrate on which the polycrystalline silicon film is formed is used for, for example, an active matrix liquid crystal display device.

  When performing the laser annealing treatment as described above, a homogenizer is used to shape the cross section of the laser beam into an elongated shape and to make the light intensity distribution in the longitudinal direction within the shaped beam cross section uniform. . The substrate is irradiated with a laser beam emitted from the homogenizer. While moving the light irradiation region on the substrate surface in a direction orthogonal to the longitudinal direction of the light irradiation region, the irradiation with the pulse laser beam is repeated. A light irradiation region irradiated with a shot with a pulse laser beam and a light irradiation region irradiated with the next shot partially overlap in the width direction of the light irradiation region (short direction of the light irradiation region). The light irradiation area on the substrate surface is moved at a speed. In this way, the laser beam is irradiated on the entire surface to be processed.

  If the light intensity distribution in the cross section of the laser beam irradiated on the substrate surface is not appropriate, the quality of the formed polycrystalline silicon film cannot be improved. Therefore, a laser processing apparatus that can monitor the light intensity distribution in the cross section of the laser beam emitted from the homogenizer has been considered.

  For example, the laser processing apparatus described in Patent Document 1 has a profile monitor for measuring the light intensity distribution. This profile monitor has a folding mirror, an imaging lens, and a CCD camera capable of measuring the light intensity distribution in the beam cross section, and is movably installed. For example, the light intensity distribution is measured as follows before the start of annealing.

  The profile monitor is moved, and the folding mirror is placed on the optical path of the laser beam emitted from the homogenizer and irradiated on the substrate. The laser beam emitted from the homogenizer is reflected by the folding mirror, and the cross section is shaped into a desired shape at a position that has traveled by the length of the optical path reaching the processing surface from the homogenizer, and the light intensity distribution in the cross section is made uniform. . The beam cross section at this position is imaged by the imaging lens, and a CCD camera arranged on the imaging plane measures the light intensity distribution in the beam cross section. In this way, it is possible to measure the light intensity distribution corresponding to the light intensity distribution in the cross section of the laser beam irradiated to the processing surface. When the annealing process is performed, the profile monitor is disposed at a retracted position so that the laser beam applied to the substrate does not interfere with the folding mirror.

  Patent Document 2 describes a laser processing apparatus as described below. The laser beam emitted from the laser light source passes through the attenuator, is reflected by the folding mirror that can be swung by the actuator, and enters the homogenizer. The laser beam emitted from the homogenizer is incident on a partially reflecting mirror that reflects most of the incident light and transmits the remaining light. The laser beam reflected by the partial reflection mirror is irradiated onto the substrate. The laser beam that has passed through the partial reflecting mirror is incident on three CCD cameras that are arranged so that light at both ends and the center in the longitudinal direction of the cross section of the laser beam are incident thereon.

  In this laser processing apparatus, the light intensity distribution in the beam cross section is monitored by the three CCD cameras arranged as described above. When the light intensity distribution is not appropriate, the folding mirror is swung by the actuator, and the incident direction of the laser beam incident on the homogenizer is changed to optimize the light intensity distribution in the beam cross section. Further, when the difference in light intensity between both ends in the longitudinal direction exceeds an allowable range, medium gas is injected into the laser light source, cooling water is injected, and the difference is reduced. Further, when the energy irradiated in the beam section deviates from the set value, the attenuator is controlled and adjusted so that the energy becomes the set value.

  In this laser processing apparatus, a laser beam emitted from a homogenizer is incident on a partial reflecting mirror, the reflected light is irradiated on a substrate, and the transmitted light is incident on a CCD camera. Thereby, the light intensity distribution in the beam cross section can be monitored while performing the annealing treatment.

JP 2001-77046 A JP 2003-258349 A

  By the homogenizer, the light intensity distribution in the width direction (short direction) of the beam section shaped into a long shape can be made uniform. The light intensity in the width direction in the beam cross section rises from the both ends with a certain degree of gentleness, and becomes substantially uniform inside except for both ends. In the laser annealing treatment, the light irradiation region of each shot of the pulse laser beam is partially overlapped in the width direction of the light irradiation region. If the shape of the rising portion of the light intensity distribution in the width direction of the beam cross section varies with time, the quality of the formed polycrystalline silicon film varies.

  One object of the present invention is to provide a laser processing apparatus capable of suppressing fluctuations in the light intensity distribution in the cross section of a laser beam irradiated to a workpiece.

  Another object of the present invention is to measure the light intensity distribution in the beam cross section while irradiating the workpiece with the laser beam emitted from the laser light source, and to monitor the shape of the rising portion of the light intensity distribution. It is to provide a laser processing apparatus.

  According to a first aspect of the present invention, a laser light source that emits a laser beam, and a spread angle adjuster that changes a spread angle of the laser beam emitted from the laser light source based on a control signal input from the outside; , Based on the light intensity distribution measured by the measuring device that measures the light intensity distribution in the cross section of the laser beam emitted from the divergence angle adjuster, the light intensity distribution approaches the target distribution, There is provided a laser processing apparatus having a control device for controlling the divergence angle adjuster.

  According to a second aspect of the present invention, a laser light source that emits a laser beam, a branching device that branches the laser beam emitted from the laser light source, and a branching device that emits from the branching device along a certain optical path. A first stage in the cross section of the laser beam emitted from the branching unit and propagated along the other optical path at a position where the propagated laser beam is irradiated. In the light intensity distribution, in the vicinity of the outer periphery where the light intensity increases from the edge of the beam cross section toward the inside in the light intensity distribution, a range in which the intensity changes from the first value to the second value, A laser processing apparatus having a detector for detecting a length in the first direction is provided.

  The shape of the light intensity distribution in the cross section of the laser beam (for example, the steepness of rising of the light intensity distribution) depends on the divergence angle of the laser beam. In the laser processing apparatus according to the first aspect of the present invention, the control device controls the divergence angle controller based on the light intensity distribution measured by the measuring instrument, whereby the light intensity distribution approaches the target distribution. For example, in the laser annealing treatment, it is preferable that the light intensity distribution in the cross section of the laser beam irradiated to the workpiece does not vary with time. If this laser processing apparatus is applied to a laser annealing processing apparatus, it is possible to suppress the temporal fluctuation of the light intensity distribution.

  In the laser processing apparatus according to the second aspect of the present invention, the laser beam is branched by the branching device, whereby the workpiece and the detector can be irradiated with the laser beam at the same time. A physical quantity corresponding to the shape of the rising portion of the light intensity distribution in the beam cross section is detected by the detector. For example, in the laser annealing treatment, it is preferable that the shape of the rising portion of the light intensity distribution in the cross section of the laser beam irradiated on the workpiece does not vary with time. When this laser processing apparatus is applied to a laser annealing processing apparatus, it is possible to monitor temporal variations in the shape of the rising portion of the light intensity distribution in the beam cross section while performing laser annealing processing.

  FIG. 1 is a schematic view showing a laser processing apparatus according to an embodiment of the present invention. The laser light source 1 emits a laser beam. For example, an excimer laser is used as the laser light source 1. The laser beam emitted from the laser light source 1 enters the filter 2 that changes the intensity of the laser beam. The control device 10 controls the filter 2 to adjust the intensity of the laser beam to a desired value. The laser beam that has passed through the filter 2 is incident on a zoom lens 3 having a variable magnification of the beam cross section.

  The zoom lens 3 enlarges the cross section of the incident laser beam and emits the laser beam with the enlarged cross section as substantially parallel light. It is known that the product of the beam diameter and the divergence angle has a constant value at a certain position on the optical path of the laser beam. For example, when the beam diameter at the position where the laser beam is emitted from the zoom lens 3 is enlarged to twice the beam diameter at the position where the zoom lens 3 is not disposed, the divergence angle becomes 1 / (2) when the beam diameter is not enlarged. Decrease to 2. By enlarging the beam cross section with the zoom lens 3, the divergence angle of the laser beam emitted from the laser light source 1 can be reduced.

  By changing the magnification of the beam cross section, the divergence angle of the laser beam emitted from the zoom lens 3 can be changed. The control device 10 controls the zoom lens 3 to change the enlargement ratio, and adjusts the divergence angle of the laser beam to a desired value.

  The laser beam emitted from the zoom lens 3 passes through the array lens 4 and enters the partial reflection mirror 5. The partial reflection mirror 5 reflects most of the incident light (for example, 99.5 to 99.9%) and transmits the remaining light (for example, 0.1% to 0.5%). The laser beam reflected by the partial reflection mirror 5 enters the focus lens 6a. A homogenizer 11 a that includes the array lens 4 and the focus lens 6 a and performs shaping of the beam cross section and uniformization of the light intensity distribution in the beam cross section is configured.

  The laser beam that has passed through the partial reflection mirror 5 enters the focus lens 6b. The focus lens 6b has the same optical characteristics as the focus lens 6a. The focus lens 6b is arranged so that the optical path length from the array lens 4 to the focus lens 6a is equal to the optical path length from the array lens 4 to the focus lens 6b. A homogenizer 11b is formed that includes the array lens 4 and the focus lens 6b and performs shaping of the beam cross section and uniformization of the light intensity distribution in the beam cross section.

  A homogenizer 11b having an array lens 4 and a focus lens 6b will be described with reference to FIGS. In the figure, the partial reflecting mirror 5 is omitted. Consider an XYZ orthogonal coordinate system having a Z-axis parallel to the optical axis of a light beam incident on the array lens 4. 2A is a cross-sectional view parallel to the YZ plane, and FIG. 2B is a cross-sectional view parallel to the XZ plane.

  As shown in FIG. 2 (A), a cylinder array in which seven equivalent cylindrical lenses have respective generatrix directions parallel to the X axis and arranged in the Y axis direction, along a virtual plane parallel to the XY plane 15A and 15B are configured. The optical axis surfaces of the cylindrical lenses of the cylinder arrays 15A and 15B are parallel to the XZ plane. Here, the optical axis plane means a symmetry plane of a plane-symmetric imaging system of the cylindrical lens. The cylinder array 15A is disposed on the light incident side (left side in the figure), and the cylinder array 15B is disposed on the emission side (right side in the figure).

  As shown in FIG. 2 (B), seven equivalent cylindrical lenses have their respective generatrix directions parallel to the Y axis and arranged in the X axis direction, and cylinder arrays 16A along a virtual plane parallel to the XY plane. And 16B are configured. The optical axis surfaces of the cylindrical lenses of the cylinder arrays 16A and 16B are parallel to the YZ plane. The cylinder array 16A is disposed in front of the cylinder array 15A (left side in the figure), and the cylinder array 16B is disposed between the cylinder arrays 15A and 15B. The optical axis surfaces of the corresponding cylindrical lenses of the cylinder arrays 15A and 15B coincide, and the optical axis surfaces of the corresponding cylindrical lenses of the cylinder arrays 16A and 16B also coincide. The array lens 4 includes the cylinder arrays 15A, 15B, 16A, and 16B.

  A focus lens 6b is disposed at a position behind the cylinder array 15B and away from the cylinder array 15B by a predetermined optical path length. The optical axis of the focus lens 6b is parallel to the Z axis.

  With reference to FIG. 2A, a state of propagation of the light beam in the YZ plane will be described. In the YZ plane, the cylinder arrays 16A and 16B are simply flat plates and do not affect the convergence and divergence of the light flux. A parallel light beam 17 having an optical axis parallel to the Z axis enters the cylinder array 16A from the left side of the cylinder array 16A. The parallel light flux 17 has a light intensity distribution that is strong in the central portion and weak in the peripheral portion, for example, as shown by a curve 21Y.

  The parallel light beam 17 passes through the cylinder array 16A and enters the cylinder array 15A. The incident beam bundle is divided into seven convergent beam bundles corresponding to the respective cylindrical lenses by the cylinder array 15A. In FIG. 2A, only the light beams at the center and both ends are shown as representatives. Each of the seven convergent light bundles has a light intensity distribution indicated by curves 21ya to 21yg. The beam bundle converged by the cylinder array 15A is converged again by the cylinder array 15B.

  The seven convergent light beams 18 converged by the cylinder array 15B are imaged in front of the focus lens 6b. This imaging position is closer to the lens than the focal point on the incident side of the focus lens 6b. For this reason, the seven light fluxes transmitted through the focus lens 6b become divergent light fluxes, and overlap each other on the homogenized surface 20 that is separated from the focus lens 6b by a predetermined optical path length. The light intensity distribution in the Y-axis direction of the seven light bundles that irradiate the homogenized surface 20 is equal to a distribution obtained by extending the light intensity distributions 21ya to 21yg in the Y-axis direction, respectively. Since the light intensity distributions 21ya and 21yg, 21yb and 21yf, and 21yc and 21ye have inverted relationships with respect to the Y-axis direction, the light intensity distribution obtained by superimposing these light bundles is uniform as shown by the solid line 22y. Approach the distribution.

  With reference to FIG. 2B, the state of propagation of the light beam in the XZ plane will be described. In the XZ plane, the cylinder arrays 15A and 15B are simply flat plates, and thus do not affect the convergence and divergence of the light flux. The parallel light beam 17 enters the cylinder array 16A. The parallel light flux 17 has a light intensity distribution that is strong in the central portion and weak in the peripheral portion, for example, as shown by a curve 21X.

  The parallel light bundle 17 is divided into seven convergent light bundles corresponding to the respective cylindrical lenses by the cylinder array 16A. In FIG. 2B, only the light beams at the center and both ends are shown as representatives. Each of the seven convergent light bundles has a light intensity distribution indicated by curves 21xa to 21xg.

  Each light flux forms an image in front of the cylinder array 16B, and enters the cylinder array 16B as a divergent light flux. Each light beam incident on the cylinder array 16B is emitted with a certain emission angle and is incident on the focus lens 6b. The seven light fluxes transmitted through the focus lens 6b become convergent light fluxes and overlap on the homogenized surface 20.

  The light intensity distribution in the X-axis direction of the seven light bundles that irradiate the homogenized surface 20 approaches a uniform distribution as shown by the solid line 22x. As described above, the light irradiation region on the homogenized surface 20 has a linear shape that is long in the Y-axis direction and short in the X-axis direction.

  The homogenizer 11a having the array lens 4 and the focus lens 6a is configured such that the laser beam emitted from the array lens 4 is reflected by the partial reflection mirror 5 and enters the focus lens 6a, whereby the array lens 4 and the focus lens 6b. It acts similarly to the homogenizer 11b having On the homogenization surface of the homogenizer 11a, light is irradiated to a region elongated in one direction, and the light intensity in the light irradiation region becomes substantially uniform.

  Returning to FIG. 1, the description will be continued. A laser beam emitted from the array lens 4, reflected by the partial reflecting mirror 5, and transmitted through the focus lens 6 a is irradiated onto the substrate 7 having an amorphous silicon film formed on the surface. The processed surface of the substrate 7 is disposed on the homogenized surface of the homogenizer 11a. Thereby, the elongate linear area | region on a to-be-processed surface is irradiated substantially uniformly.

  The substrate 7 is held on the XY stage 8. The XY stage 8 can move the substrate 7 in a two-dimensional direction parallel to the surface to be processed. An amorphous silicon film is annealed by irradiating a laser beam onto a processing surface while moving the substrate 7 in a direction orthogonal to the longitudinal direction of the light irradiation region on the substrate on the XY stage 8. Done.

  The laser beam emitted from the array lens 4, transmitted through the partial reflection mirror 5, and transmitted through the focus lens 6 b is incident on the line sensor 9 that can measure the light intensity distribution in the one-dimensional direction in the beam cross section. The light receiving surface of the line sensor 9 is on an appropriate position in the longitudinal direction of the beam section on the homogenizing surface of the homogenizer 11b, and the measurement direction of the light intensity distribution is orthogonal to the longitudinal direction of the beam section (that is, Arranged so as to be parallel to the width direction of the beam cross section. The line sensor 9 measures the light intensity distribution in the width direction (short direction) in the beam cross section. A signal corresponding to the light intensity distribution measured by the line sensor 9 is sent to the control device 10 at a frequency of once per second, for example.

  Since the homogenizers 11a and 11b act similarly, the beam cross section on the homogenization surface of the homogenizer 11a and the beam cross section on the homogenization surface of the homogenizer 11b are congruent. By multiplying the light intensity distribution in the beam cross section on the homogenization surface of the homogenizer 11b by a coefficient corresponding to the intensity ratio of the reflected light and the transmitted light of the partial reflector 5, the light in the beam cross section on the homogenization surface of the homogenizer 11a. It can be matched with the intensity distribution. Thus, the light intensity distributions in both beam sections correspond to each other.

  Thereby, the light intensity distribution measured by the line sensor 9 corresponds to the light intensity distribution in the width direction at a certain position in the longitudinal direction of the beam cross section on the processing surface. Thus, by monitoring the light intensity distribution on the homogenized surface of the homogenizer 11b with the line sensor 9, it is possible to monitor the light intensity distribution of the laser beam applied to the processing surface.

  The laser beam is branched by the partial reflection mirror 5 (the incident light of the partial reflection mirror 5 is divided into transmitted light and reflected light), the focus lens 6a, and the substrate 7 held by the XY stage 8. The relative positional relationship of the processed surface is equal to the relative positional relationship of the light receiving surface where the branch point, the focus lens 6b, and the line sensor 9 measure the light intensity distribution.

FIG. 3 is a graph schematically showing the light intensity distribution measured by the line sensor 9. The vertical axis of the graph indicates the light intensity, and the horizontal axis indicates the position in the width direction within the beam cross section. Maximum value of the intensity of distribution (peak intensity) is P _M.

As shown, the intensity from one end of the width direction in the beam cross-section to the center is gradually gently increased from one end, an increase from a certain position abruptly, from reaching the maximum value P _M approximately, nearly It becomes constant. In the center of the beam cross-section, the strength is the maximum value P _M. The intensity from the other end of the beam section to the center of the beam section also changes in the same manner.

In order to represent the shape of the light intensity distribution, for example, the following indices are defined. Width ranging intensity is 50% or more of the maximum value P _M is the full width at half maximum W. This represents the width of the light intensity distribution. In one end side from the center of the beam cross-section (leftward in the drawing), the outer peripheral region near the light intensity toward the interior from the edges of the beam cross section is increased, the width of the range in which the intensity is changed from P _A to P _B is left The slope width W _SA . Further, at the other side from the center of the beam cross-section (right in the figure), in the vicinity of the outer circumference region in which the light intensity is increased toward the inside from the edge of the beam cross section, intensity range varying from P _A to P _B Width Is the right slope width W _SB . The left and right slope widths represent the steepness of the rise of the light intensity distribution. The narrower the slope width, the steeper the rise of the light intensity distribution, and the wider the slope width, the slower the rise of the light intensity distribution. The intensity _{P A} and _{P B} defining the slope width, for example, each set to 20% and 80% of the peak intensity _{P M.}

1 calculates the peak intensity P _M , the full width at half maximum W, the left slope width W _SA , and the right slope width W _SB based on the signal corresponding to the light intensity distribution input from the line sensor 9. . In addition, the energy which irradiates the line sensor which passes a beam cross section can also be calculated by integrating | accumulating light intensity about the width direction. Further, it is also possible to calculate a variation in the width direction of the center position (pointing) of the light intensity distribution based on the light intensity distribution data at different times.

Now, the present inventors have found that the left and right slope widths W _SA and W _SB representing the steepness of the rise of the light intensity distribution vary depending on the divergence angle of the laser beam incident on the array lens 4 in FIG. Focused on. When the divergence angle is small, both slope widths are shortened. That is, the rise of the light intensity distribution becomes steep. On the other hand, when the divergence angle is large, both slope widths become long. That is, the rise of the light intensity distribution becomes slow. In the limit where the divergence angle is zero, both slope widths are zero.

  When the laser oscillation is continued for several tens of hours, the output of the excimer laser light source decreases due to deterioration of the gas in the laser medium or contamination of the window. Accordingly, the divergence angle of the laser beam emitted from the excimer laser light source increases. As a result, a phenomenon occurs in which the right and left slope widths increase (the rise of the light intensity distribution becomes slow) as time passes. From the viewpoint of the stability of the processing quality, it is not preferable that the shape of the light intensity distribution of the laser beam irradiated on the processing surface varies with time.

In the laser processing apparatus shown in FIG. 1, signals corresponding to the light intensity distribution are sequentially input from the line sensor 9 to the control apparatus 10 at a predetermined frequency. The control device 10 calculates the left and right slope widths W _SA and W _SB with respect to the light intensity distribution at each time. When a deviation from the target value is detected for each of the left and right slope widths, the control device 10 changes the enlargement ratio of the zoom lens 3 so that the slope width deviation is reduced.

  The laser processing apparatus shown in FIG. 1 can suppress fluctuations in the left and right slope widths in this way. Since the shape of the light intensity distribution of the laser beam irradiated onto the surface to be processed is suppressed from temporal variation, the stability of the processing quality is improved.

  When the peak intensity in the light intensity distribution deviates from the target value, or when the energy applied to the line sensor passing through the beam cross section deviates from the target value, the control device 10 controls the filter 2, The intensity of the laser beam is changed so that the peak intensity and energy deviation are reduced.

The laser processing apparatus shown in FIG. 1 irradiates the surface to be processed with the reflected light of the partial reflecting mirror 5, makes the transmitted light enter the line sensor 9, and monitors the light intensity distribution. As described above, the light intensity distribution monitored by the line sensor 9 corresponds to the light intensity distribution in the cross section of the laser beam irradiated onto the processing surface. Thereby, the light intensity distribution of the laser beam used for the annealing process can be monitored while performing the annealing process. In particular, by calculating the left and right slope widths W _SA and W _SB , it is possible to monitor the disturbance (variation) in the shape of the rising portion of the light intensity distribution. The partial reflecting mirror 5 may be configured to transmit most of the incident light and reflect the rest, irradiate the processed surface with the transmitted light, and cause the reflected light to enter the line sensor 9. Absent.

  A plurality of line sensors may be arranged in the longitudinal direction of the beam cross section. By arranging a plurality of line sensors at a plurality of positions in the longitudinal direction, it is possible to monitor whether the light intensity distribution is uniform in the longitudinal direction. Note that the measurement direction of the light intensity distribution of the line sensor may be other than the direction orthogonal to the length of the beam cross section, if necessary.

  A CCD camera that can measure the light intensity distribution in the beam cross section in the two-dimensional direction may be arranged instead of the line sensor that measures the light intensity distribution in the one-dimensional direction in the beam cross section.

  As shown in FIG. 1B, the line sensor 9 can be disposed at a position other than the homogenization surface 20a of the beam homogenizer 11b. A lens 12 that forms an image of a beam cross section on the homogenization surface 20a of the beam homogenizer 11b is disposed behind the homogenization surface, and a light receiving surface of the line sensor 9 is disposed on a surface on which the beam cross section is imaged. The light irradiation area on the imaging surface has a shape similar to the beam cross section on the homogenizing surface 20a. The beam cross section on the homogenized surface 20a and the beam cross section of the light incident on the line sensor 9 may have different sizes, but the light intensity distributions in both beam cross sections correspond to each other. Even if the line sensor 9 is arranged in this way, it is possible to monitor the light intensity distribution corresponding to the light intensity distribution of the laser beam applied to the processing surface.

  Next, a laser processing apparatus according to the second embodiment will be described with reference to FIG. The laser processing apparatus shown in FIG. 4 has a configuration in which the focus lenses 6 a and 6 b are removed from the laser processing apparatus shown in FIG. 1 and the focus lens 6 is arranged on the optical path from the array lens 4 to the partial reflection mirror 5. . In the laser processing apparatus shown in FIG. 4, the array lens 4 and the focus lens 6 constitute a homogenizer 11, and a laser beam emitted from the homogenizer 11 enters the partial reflection mirror 5.

  Reflected light from the partial reflecting mirror 5 is applied to the substrate 7, and transmitted light enters the line sensor 9. The light receiving surface of the line sensor 9 is disposed on the homogenizing surface of the homogenizer 11. The optical path length from the focus lens 6 to the light receiving surface of the line sensor 9 is set equal to the optical path length from the focus lens 6 to the processing surface of the substrate 7. Thereby, the surface to be processed is also arranged on the homogenized surface of the homogenizer 11. The laser processing apparatus shown in FIG. 4 needs only one focus lens for constituting a homogenizer.

  In the laser processing apparatus described above, the light intensity distribution in the cross section of the laser beam that passed through the homogenizer was measured. However, the homogenizer was removed from the laser processing apparatus, and the divergence angle of the laser beam emitted from the laser light source was zoomed. The light intensity distribution in the cross section of the laser beam emitted from the zoom lens may be measured by adjusting with the lens. The shape of the light intensity distribution in the cross section of the laser beam incident on the light intensity distribution measuring instrument depends on the divergence angle. By adjusting the divergence angle based on the light intensity distribution measured by the measuring device, the light intensity distribution can be brought close to the target distribution. The divergence angle of the laser beam may be adjusted by an apparatus other than the zoom lens 3. Moreover, you may use the laser processing apparatus demonstrated above for uses other than a laser annealing process.

  Although the present invention has been described with reference to the embodiments, the present invention is not limited thereto. It will be apparent to those skilled in the art that various modifications, improvements, combinations, and the like can be made.

FIG. 1A is a schematic view of a laser processing apparatus according to a first embodiment of the present invention, and FIG. 1B is a schematic view showing a part of a laser processing apparatus according to a modification of the embodiment. . FIG. 2A and FIG. 2B are schematic diagrams illustrating a configuration example of a homogenizer. It is a graph which shows roughly the light intensity distribution in the beam cross section shaped with the homogenizer. It is the schematic of the laser processing apparatus by 2nd Example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Laser light source 2 Filter 3 Zoom lens 4 Array lens 5 Partial reflection mirror 6a, 6b, 6 Focus lens 7 Substrate 8 XY stage 9 Line sensor 10 Controller 11a, 11b, 11 Homogenizer 12 Lens

Claims (12)

A laser light source for emitting a laser beam;
A divergence angle adjuster that changes a divergence angle of the laser beam emitted from the laser light source based on a control signal input from the outside;
A measuring instrument for measuring the light intensity distribution in the cross section of the laser beam emitted from the divergence angle adjuster;
A laser processing apparatus comprising: a control device that controls the divergence angle adjuster so that the light intensity distribution approaches a target distribution based on the light intensity distribution measured by the measuring device. The laser processing apparatus according to claim 1, wherein the divergence angle adjuster changes a magnification ratio of a beam cross section. The measuring device measures the light intensity distribution in the first direction in the beam cross section, and the control device detects the light intensity in the light intensity distribution in the first direction from the edge of the beam cross section toward the inside. In the vicinity of the rising outer periphery, the length of the range in which the intensity changes from the first value to the second value is calculated with respect to the first direction, and when the calculated length deviates from the target value, The laser processing apparatus according to claim 1, wherein the divergence angle adjuster is controlled so that the deviation becomes small. And a beam shaper for shaping the cross section of the laser beam emitted from the divergence angle adjuster into a shape elongated in one direction,
The laser processing apparatus according to claim 3, wherein the first direction is a direction orthogonal to the longitudinal direction of the beam cross section. further,
A branching device arranged on an optical path between the divergence angle controller and the measuring device, and branching a laser beam emitted from the divergence angle controller;
A holding base for holding a workpiece at a position irradiated with a laser beam emitted from the branching device and propagated along one optical path;
The laser processing apparatus according to claim 1, wherein the measuring device measures a light intensity distribution of a laser beam emitted from the branching device and propagated along another optical path. further,
An array lens that is arranged so that a laser beam emitted from the divergence angle adjuster is incident, and divides the laser beam into a plurality of parts within a cross section of the incident laser beam;
A branching device for branching the laser beam emitted from the array lens;
A first focus lens that irradiates a common region with a laser beam emitted from the splitter and propagating along a certain optical path, and divided by the array lens within the cross section of the laser beam When,
A holding table for holding a workpiece at a position irradiated with a laser beam emitted from the first focus lens;
A laser beam emitted from the splitter and propagating along another optical path is incident, and has a second focus lens having the same optical characteristics as the first focus lens,
The laser processing apparatus according to claim 1, wherein the measuring device measures a light intensity distribution of a laser beam emitted from the second focus lens. The relative position relationship between the branch point at which the laser beam is branched by the branching unit, the first focus lens, and the workpiece surface held by the holding table is the branch point, the second focus. The laser processing apparatus according to claim 6, wherein the lens and the measuring device are equal in relative positional relationship between a light receiving surface for measuring a light intensity distribution. A bifurcating plane that intersects the optical path from the second focus lens to the lens, the lens being disposed on the optical path from the second focus lens to the measuring instrument; The relative position relationship between the branch point where the laser beam is branched by the instrument, the second focus lens, and the virtual plane is the same as that of the workpiece to be held on the branch point, the first focus lens, and the holding table. The lens forms an image of a beam cross section on the virtual plane on a light-receiving surface on which the measuring device measures a light intensity distribution when the virtual plane equal to the relative positional relationship of the processing surface is considered. The laser processing apparatus as described. A laser light source for emitting a laser beam;
A branching device for branching a laser beam emitted from the laser light source;
A holding table for holding a workpiece at a position irradiated with a laser beam emitted from the branching device and propagated along a certain optical path;
The light intensity distribution in the first direction in the cross section of the laser beam emitted from the branching device and propagated along the other optical path is measured, and from the edge of the beam cross section to the inside in the light intensity distribution And a length calculation unit that calculates a length in the first direction in a range in which the intensity varies from the first value to the second value in a region near the outer periphery where the light intensity increases toward . A laser light source for emitting a laser beam;
An array lens that is arranged so that a laser beam emitted from the laser light source is incident, and divides the laser beam into a plurality of parts within a cross section of the incident laser beam;
A branching device for branching the laser beam emitted from the array lens;
A first focus that irradiates a common region with a laser beam that is emitted from the splitter and propagates along a certain optical path, and is divided by the array lens within the cross section of the laser beam. A lens,
A holding table for holding a workpiece at a position irradiated with a laser beam emitted from the first focus lens;
A second focus lens that is emitted from the splitter and propagates along another optical path, and has the same optical characteristics as the first focus lens;
A laser processing apparatus comprising: a measuring device that measures a light intensity distribution in a cross section of the laser beam emitted from the second focus lens; The relative position relationship between the branch point at which the laser beam is branched by the branching unit, the first focus lens, and the workpiece surface held by the holding table is the branch point, the second focus. The laser processing apparatus according to claim 10, wherein the lens and the measuring device are equal in relative positional relationship between a light receiving surface for measuring a light intensity distribution. A bifurcating plane that intersects the optical path from the second focus lens to the lens, the lens being disposed on the optical path from the second focus lens to the measuring instrument; The relative position relationship between the branch point where the laser beam is branched by the instrument, the second focus lens, and the virtual plane is the same as that of the workpiece to be held on the branch point, the first focus lens, and the holding table. 11. When considering the virtual plane that is equal to the relative positional relationship of the processing surface, the lens forms an image of a beam cross section on the virtual plane on a light receiving surface on which the measuring instrument measures a light intensity distribution. The laser processing apparatus as described.

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