JP2018027551A - Confocal beam profiler - Google Patents

Abstract

Kind Code: A1 The present invention is a reduction imaging laser processing apparatus that requires high resolution, and is capable of monitoring, in real time and with high resolution, the shape of a laser beam formed as a reduction image on an irradiated surface of an object to be processed. It is intended to provide a beam profiler. A beam profiler for monitoring and analyzing the transverse mode distribution of a laser beam reduced and projected by a reduction imaging optical system including at least a mask, a mirror and an objective lens in this order, wherein the mirror is , a non-total reflection mirror that transmits part of the laser beam, and the image pickup device has an image pickup surface at a position conjugate to a position where the pattern drawn on the mask is reduced and projected by the objective lens and formed into an image. and a beam profiler that receives reflected light from an object to be processed that has passed through the non-total reflection mirror on its imaging surface. [Selection drawing] Fig. 5

Description

The present invention relates to an apparatus for monitoring an imaging state of a laser beam on an irradiated surface of an object to be processed in a laser processing apparatus.

  In a reduction imaging type laser processing apparatus that requires submicron processing accuracy, monitoring of the laser beam shape projected on the irradiated surface of the object to be processed and control of the focal length of the reduction imaging optical system are as follows: Very important. Therefore, a beam profiler is used for this purpose.

  As a conventional beam profiler, a part of the laser beam propagating toward the irradiated surface of the workpiece is branched by a beam splitter or the like before the irradiated surface, and this is simulated and projected onto an imaging device such as a CCD camera. Thus, there are those that estimate the beam shape and the like on the irradiated surface, and those that monitor off-axis a fluorescent screen placed at the same focal position as the irradiated surface.

  In Patent Document 1, laser light is irradiated to an adjustment fluorescent plate placed at the same height as the irradiated surface of the workpiece, and the fluorescence is monitored and analyzed off-axis. There has been disclosed a technique for estimating the shape of a laser beam irradiated on an irradiated surface of an object to be processed in actual processing and pre-adjusting an optical system based on the estimated shape. However, in this technique, the shape of the laser beam actually irradiated onto the irradiated surface of the workpiece cannot be monitored in real time with an accuracy equivalent to the processing accuracy.

  Patent Document 2 discloses an imaging optical system on a measurement reference plane of a monitor substrate that is installed for estimating the shape of a laser beam irradiated on an irradiation surface of an object to be processed, or for its prior adjustment. A technique for monitoring the imaging state and the irradiated energy using a processing laser beam that has passed through the measurement reference plane is disclosed.

  Further, separately from the processing laser light, the measurement laser light is irradiated on the irradiated surface of the object to be processed coaxially with the processing laser light through the processing objective lens located at the final stage of the imaging optical system. By measuring the reflected light, changes in the position and state of the irradiated surface and, in turn, changes in the imaging state caused by temperature changes in the optical element such as the processing objective lens are monitored in real time. A technique for performing automatic control for optimizing machining is disclosed.

  However, in any technique, the state of the laser beam used for actual processing that is reduced and imaged on the irradiated surface of the object to be processed can be measured in real time with an accuracy equivalent to the processing accuracy of the reduced imaging optical system. It cannot be monitored.

JP 2001-284281 A JP 2008-119716 A

  The present invention has been made in view of the above-described problems of the background art, and in a reduced imaging type laser processing apparatus that requires high resolution, reduced image formation is performed on an irradiated surface of an object to be processed. The object is to provide a beam profiler that can monitor the laser beam shape in real time and with high resolution.

  The first invention is mounted on a laser processing apparatus including at least a reduction imaging optical system including a mask, a mirror, and an objective lens in this order, and a stage on which an object to be processed is placed. A beam profiler comprising an imaging device for monitoring the transverse mode distribution and image formation state of a laser beam at an image point, and an analyzer for analyzing captured image data, wherein the mirror transmits a part of the laser beam. The imaging device has an imaging surface at a position where the pattern drawn on the mask is projected by reduction by the objective lens and forms an image, and the imaging surface is the non-reflection mirror. A beam profiler that receives reflected light that is return light from the object to be processed that has passed through a total reflection mirror.

  Here, the imaging device refers to an imaging device including an image sensor such as a CCD or a CMOS, but is not limited to these. The analysis device that analyzes the captured image data is not only the operation screen for analyzing the data captured by the image sensor, but also 2D / 3D display (visualization), cross section display, intensity distribution display, etc. Time statistics can be displayed.

  The number of total reflection mirrors included in the reduction imaging optical system is not limited because it depends on the design of the optical path arrangement. The position of the non-total reflection mirror in the reduction imaging optical system need not be immediately before the objective lens (on the laser light source side) as long as the confocal relationship described above can be maintained.

  In addition, the reflectance of the non-total reflection mirror includes the intensity of the reflected light that is reflected by the irradiated surface on the object to be processed and the intensity of the reflected light that is incident on the image sensor. This is a design matter determined by a damage threshold in the image sensor. As an example, when a laser beam having a wavelength of 248 nm is incident at 45 °, 99% is reflected and the remaining 1% is reflected. And 1% of the reflected light is further transmitted through the non-total reflection mirror. Depending on the specification value of the mirror, it is possible to use a commercially available total reflection mirror in many cases.

  According to a second invention, in the first invention, the analysis device monitors an imaging state on an irradiated surface of the workpiece by cross section analysis with respect to a transverse mode distribution of laser beam intensity. It is a beam profiler.

  The specific state of analysis is shown in FIG. 1, FIG. 2 and FIG. FIG. 1 shows a two-dimensional profile of a laser beam when the surface to be processed is irradiated at a position of minus 40 μm in the optical axis direction from the position where the image is correctly formed. FIG. 2 shows an intensity distribution (cross section) at the horizontal bar position among the cross bars shown in FIG. The portion where the intensity changes abruptly corresponds to the edge portion in the transverse mode distribution of the laser beam.

  FIG. 3 shows the transition of the edge shape obtained from the cross section analysis, that is, the sharpness of the rise when the position in the optical axis direction of the irradiated surface is sequentially measured from the imaging position to −40 μm to +40 μm at a pitch of 10 μm. Shows the transition. Here, the sharpness of the rise and the amount of gradient are shown as the distribution width (edge width) required for the laser beam intensity at the edge portion to change from 10% to 90% of the maximum value. When the imaging state is good, the edge width is narrow, and in the defocused state, the edge width is wide. The above parameters can be freely set in the analysis apparatus.

  According to a third invention, in each of the first and second inventions, each side of the pixel size of the image pickup device constituting the image pickup device is a numerical value of a product of the reduction ratio of the reduction imaging optical system and the required processing resolution. A beam profiler characterized by the following.

  For example, when the required processing resolution defined as the required separation limit due to line and space is 1 μm and the magnification of the reduction imaging optical system is 5 times, the pixel size of the CCD camera used as the image sensor is , Each side is 5 μm or less.

  According to a fourth invention, in the first to third inventions, the beam profiler further juxtaposes an adjustment optical member that can be switched to the workpiece, on the stage, and the adjustment optical member is the laser The height of the surface irradiated with the laser beam of the optical member for adjustment is the same height as the surface to be irradiated of the workpiece to be processed. It is a beam profiler characterized by being.

For example, when the laser light source is an excimer laser, a quartz plate can be suitably used as the adjustment optical member, and when the laser light source is a CO ₂ laser, zinc selenide can be suitably used.

  A fifth invention is a beam profiler according to any one of the first to fourth inventions, wherein the back surface of the adjusting optical member is a wedge plate having an angle with respect to the front surface.

  Here, the surface of the optical member for adjustment is perpendicular to the optical axis because the reflected light returns on the optical axis and is applied to the imaging surface, whereas the back surface is not vertical, but temporarily Even if the laser beam is reflected at, the reflected light does not return on the optical axis.

  A sixth invention is the first to fifth inventions, wherein the reduced imaging optical system is an image-side or both-side telecentric optical system, the adjustment optical member is a parallel plane plate, and the front and back sides of the parallel plane plate Two reflected lights from each surface are picked up by the imaging device, and the telecentricity on the image side of the telecentric optical system is confirmed by analyzing the two reflected light images picked up by the analyzing device. A beam profiler that can.

  In this sixth invention, unlike the fifth invention in which the optical member for adjustment is a wedge plate in order to avoid double imaging due to the return light from the back surface, rather, the return light is actively used. It is. From the state of the transverse mode distribution of the reflected light from the front and back surfaces, the reduction ratio of the reduction imaging optical system is constant regardless of the imaging position, and the telephoto side on the image side is at least twice as long as the thickness of the parallel plane plate. You can check whether or not sentry city is secured.

  Even when the reduction imaging optical system is not a telecentric optical system, it is possible to monitor the axial deviation of the optical system by double imaging with the return light from the back surface.

  According to a seventh invention, in the first to sixth inventions, a confocal position correction plate is provided between the non-total reflection mirror and the imaging surface, and the confocal position correction plate is formed from a workpiece. The reflected light has the same material and thickness as the non-total reflection mirror, and the normal line is rotated by 90 ° around the optical axis with the normal line of the non-total reflection mirror. Profiler.

  4 and 5 show the positional relationship between the non-total reflection mirror 2 and the confocal position correction plate 71. FIG. In this figure, the axis of the laser beam dropped from the non-total reflection mirror 2 onto the workpiece 41 is taken as the Z axis, and the plane having this axis as the normal is taken as the XY axis plane.

  If the feature of the seventh aspect of the invention is described using the coordinate system of the XYZ axes shown in FIG. 5, the direction of the normal line 21 of the non-total reflection mirror 2 is the (−X, 0, −Z) direction. That is, the direction of the normal line 711 of the confocal position correction plate 71 has a positional relationship of (0, -Y, -Z) direction obtained by rotating it 90 degrees around the Z axis. . As is clear from FIGS. 4 and 5, the confocal position corrected by the confocal position correction plate 71 is for reflected light on the imaging surface of the imaging device 61. The non-total reflection mirror 2 has an angle with respect to the optical axis, and corrects image blurring on the imaging surface caused thereby.

  An eighth invention is a beam profiler according to any one of the first to seventh inventions, further comprising a band-pass filter that transmits only the wavelength of laser light between the imaging surface and the non-total reflection mirror 2. is there.

  The band pass filter 72 shown in FIGS. 4 and 5 may have a transmission performance of about 20 nm at the FWHM with respect to the center wavelength of the laser light, and the workpiece 41 or the adjustment optical material that has been irradiated with the laser beam. The member 42 only needs to be capable of blocking the fluorescence emitted by the material. In many cases, commercially available products can be used. Thereby, the light incident on the imaging surface of the imaging device 61 is only reflected light from the workpiece 41 and the adjustment optical member 42, and energy components of other wavelengths that become noise can be eliminated.

  The beam profiler according to the present invention is a reduction imaging type laser processing apparatus that requires high resolution, and uses the laser beam to form a laser beam shape that is reduced and imaged on an irradiated surface of a workpiece. It can be monitored in real time and with high resolution.

The two-dimensional profile of the laser beam irradiated to the irradiated surface of the workpiece is shown. The cross section (intensity distribution) in arbitrary one axis | shafts of a two-dimensional profile is shown. FIG. 1 and FIG. 2 show the transition of the edge width when measured at a pitch of 10 μm from −40 μm to +40 μm. The arrangement of each optical element is shown. FIG. 4 is shown three-dimensionally. 1 shows a schematic configuration of a laser processing apparatus. 2 shows a mask on which a cross pattern and a processing pattern used for adjusting a focal position by a reduction imaging optical system are drawn. A state in which the X axis of the cross pattern when the confocal position correction plate is not inserted is imaged is shown. The enlarged image of the cross pattern part of FIG. 8A is shown. A state in which the Y-axis is imaged in the cross pattern when the confocal position correction plate is not inserted is shown. The enlarged image of the cross pattern part of FIG. 8C is shown. The state of image formation of the cross pattern when the confocal position correction plate is inserted is shown. The state which reflected the reflected light from the surface of the optical member for adjustment in the state which can maintain telecentricity and the back surface is shown. A state in which reflected light from the front surface and the back surface of the optical member for adjustment in a state where telecentricity cannot be maintained is shown. The analysis screen of the beam profiler is shown. FIG. 11A is an enlarged view of a part (inside the frame) of FIG. 11A.

  Hereinafter, a usage mode of a beam profiler according to the present invention will be described in detail with reference to the drawings.

  First, a schematic configuration of a microfabrication apparatus using a beam profiler according to an embodiment of the present invention is shown in FIG. In the present embodiment, an excimer laser 8 having a pulse oscillation wavelength of 248 nm is used as a laser light source. As the pulse laser light source, a short wavelength laser or the like that enables high resolution processing such as triple or quadruple of Nd: YAG laser can be used. Appropriate selection is required. Furthermore, depending on the processing mode such as scan processing, a continuous wave, a laser pulsed by a shutter operation, or a mode-locked laser can be used.

  The beam emitted from the excimer laser 8 is incident on the mask 1 through an optical system for beam shaping. On the mask 1, a pattern to be reduced and projected onto the workpiece 41 and a focus position adjustment pattern to be reduced and projected onto the adjustment optical member 42 are drawn. In this embodiment, a synthetic quartz plate with aluminum plating is used. The mask 1 was placed on a mask stage that moves along the XYZ axis and the θ axis (YZ plane) shown in FIG. 6 for adjusting the position and for switching between the two patterns.

  Determination of the position of each optical member of the reduction imaging optical system is performed by focal scan processing, which is a general technique, and is performed by changing the position (Z axis) of the object to be processed stepwise. In this case, the actual processed shape is observed under a microscope, and each of the specifications such as the reduction magnification (5 ×), the resolution (1 μm), the image side telecentric, etc., which are the design values of the reduction imaging optical system in this embodiment, is satisfied. The position of the optical member was adjusted. The optimization was achieved by repeating this series of processing, observation, and optical system adjustment.

  After various adjustments by focal scan processing of the reduction imaging optical system, the optical members for the confocal beam profiler according to the present invention and the imaging device 61 are installed after maintaining the positional relationship of the optical members. The position of the imaging surface was adjusted and determined. Hereinafter, the details will be divided into “(1) confocal position adjustment stage” and “(2) telecentricity recording stage”, and then “(3) actual machining stage” will be used for actual machining. Will be explained.

  Hereinafter, the pulse energy of the laser beam that has passed through the mask 1 will be described as “1” for convenience.

(1) Confocal Position Adjustment Stage The mask pattern used in the confocal position adjustment stage is an adjustment cross pattern 12 shown in the lower left of FIG. 7, which is not subjected to aluminum plating, that is, in a region through which the laser beam passes. It is a pattern. The line width is 10 μm at any location, and the length of each cross line is 250 μm. The reduced projection sizes by an objective lens 3 described later used in this embodiment are 2 μm and 50 μm, respectively.

  The laser beam that has passed through the adjustment cross pattern 12 of the mask 1 is reflected by the non-total reflection mirror 2 and enters the objective lens 3. Here, when a laser beam having a wavelength of 248 nm is incident at 45 °, the non-total reflection mirror 2 has a reflection characteristic of reflecting 99% of the pulse energy and transmitting the remaining 1%. That is, the pulse energy reflected to the objective lens 3 is 0.99.

  The objective lens 3 is an objective lens with an antireflection film for 248 nm (P-lens 5x / 18-248 manufactured by Coherent Co., Ltd.) having a magnification of 5 times and an NA of 0.13. Incident light from the non-total reflection mirror 2 is reduced and projected onto the adjustment optical member 42. The objective lens 3 is installed on the objective lens stage in order to finely adjust the position on the optical axis (Z axis). The transmittance is 90%, and the pulse energy transmitted through the transmittance is 0.89.

  The surface position (Z axis) of the adjustment optical member 42 has been adjusted in advance to be the same as the position (Z axis) of the irradiated surface of the workpiece 41 by the above-described focal scan or the like. The adjusting optical member 42 in the present embodiment is a parallel flat plate having a thickness of 2 mm and made of synthetic quartz.

  In this optical member for adjustment 42, about 5% of the energy irradiated on the first irradiated surface (first reflective surface) is reflected in the Z-axis direction, and on the bottom surface (second reflective surface). Also reflects the same 5%. That is, the energy reflected by the first reflecting surface is 0.045, and the energy reflected by the second reflecting surface and returning to the objective lens 3 is 0.040.

  Both the reflected light from the first reflecting surface (first reflected light) and the reflected light from the second reflecting surface (second reflected light) in the adjustment optical member 42 propagate through the objective lens 3 in the Z-axis direction, and again. The non-total reflection mirror 2 is reached. Due to the above-mentioned transmission characteristics (reflection characteristics), 1% is transmitted through the non-total reflection mirror 2, and is further imaged through a confocal position correction plate 71 (transmittance 95%) and a bandpass filter 72 (transmittance 95%). 61 is incident on the imaging surface. The pulse energy is 0.00036 for the first reflected light and 0.00033 for the second reflected light.

  As the confocal position correcting plate 71, a parallel flat plate made of synthetic quartz having the same thickness and the same material as the non-total reflection mirror 2 was used. When the confocal position correction plate 72 is not used, the Z position (see FIGS. 8A and 8B) of the cross pattern 12 of the mask 1 that can be recognized as the focal point by the image forming state of the line in the X-axis direction in FIG. .) And the Z position (see FIGS. 8C and 8D) that can be recognized as the focal point due to the image formation state of the line in the Y-axis direction. 8A to 8D show a case where a wedge plate that does not generate second reflected light returning on the optical axis is used as the adjustment optical member 42, and double imaging by reflected light from the second reflecting surface is avoided. Is.

  As is clear from FIGS. 8A to 8D, when the imaging plane position of the imaging device 61 is adjusted so that the X-axis direction line intensity and sharpness in the cross pattern image are maximized, the Y-axis direction line intensity decreases. , The sharpness will be lost. Conversely, if the intensity and sharpness of the line in the Y-axis direction are adjusted to the maximum, the intensity of the line in the X-axis direction is lowered, resulting in a loss of the sharpness. In this case, when specifying the correct image formation position, it cannot be determined at all whether the adjustment should be made with the X-axis image or the Y-axis image.

  Therefore, by inserting the confocal position correction plate 71 with the non-total reflection mirror 2 rotated 90 degrees on the XY plane, observation is performed with equal intensity and sharpness in any of the XY axes of the cross pattern 12 as shown in FIG. Thus, the position of the imaging surface of the imaging device 61 can be correctly adjusted to a position that is beneficial to the imaging surface of the workpiece 41 (adjusting optical member 42).

  Further, when a laser beam having a wavelength of 248 nm, which is ultraviolet light, is irradiated on the non-total reflection mirror 2, the adjustment optical member 42, and the workpiece 41, there is a case where it is excited and emits fluorescence. In particular, the fluorescence component generated in the non-total reflection mirror 2 has a high intensity, and is stronger than that of the far surface where the intensity of the emitted light is nearer to the imaging surface. Then, the intensity incident on the imaging surface has a distribution in the X-axis direction.

  Furthermore, since most of the fluorescent components from the adjustment optical member 42 and the workpiece 41 are transmitted through the non-total reflection mirror 2, the influence may not be negligible when the fluorescent component has an intensity distribution. is there. In order to prevent this, a band pass filter 72 having a central wavelength of 248 nm is installed in front of the imaging device 61 in this embodiment. A bandpass FWHM of 20 nm was used.

  As described above, the mask image of the adjustment cross pattern 12 that is projected to be reduced to 1/5 with respect to the irradiated surface (front surface) of the adjustment optical member 42 is simultaneously made confocal by the confocal beam profiler according to the present invention. Each optical member was arranged so that it could be observed, and its position was adjusted.

(2) Telecentricity recording stage In the adjustment stage of the reduction imaging optical system by the above-mentioned focal scan processing, the telecentricity is adjusted through microscopic observation of the processed shape formed on the workpiece 41. Has finished. Therefore, in the future, the confocal beam profiler according to the present invention will be prepared in preparation for the case where the telecentricity of the reduced imaging optical system is disturbed in actual processing or due to changes in the optical system over time. To record. Specifically, in the reduced imaging optical system in which the telecentricity is adjusted, an image of the first reflected light from the surface of the adjusting optical member 42 that is a plane-parallel plate and an image of the second reflected light from the back surface. Are simultaneously picked up and recorded as a reference image.

  In addition, since the depth of focus (20 μm) of the objective lens 3 used in the present embodiment is extremely short as compared with the thickness of the adjustment optical member 42, it is possible to image the first reflected light and the second reflected light with the same sharpness. Can not. However, the comparison with the reference image contributes to the confirmation of telecentricity in the actual processing stage.

  A state of double imaging to be recorded at this stage is shown in FIG. Here, the image of the reflected light from the surface of the adjustment optical member 42 is the image 13 of the first reflected light, and the image of the reflected light from the back surface is the image 14 of the second reflected light.

  FIG. 10B shows an example of an image that would be observed if the telecentricity is disturbed. As shown in this figure, if the size of the cross pattern image is still different between the first reflected light image 13 and the second reflected light image 14 even if the difference due to the depth of focus is taken into account, the telecentricity It means that the adjustment is insufficient or this is disturbed.

  Further, when the center of the cross pattern image is displaced, the sigma (σ) indicating the deviation is insufficiently adjusted for the optical axis of the reduced imaging optical system, and hence the optical axis of the reflected light incident on the beam profiler. Or it means that this is disturbed.

(3) Actual processing stage Next, the mask 1 is moved or switched, and the cross pattern 12 for adjustment is changed to a reduced imaging optical system using the actual processing mask pattern 11. Then, a one-shot scan process was performed on the workpiece 41 using a predetermined processing program.

  The confocal beam profiler according to the present embodiment monitors reflected light from the irradiated surface on the workpiece in real time for each shot. As another embodiment, for example, in the case of scan processing of several shots, the processing depth increases beyond the focal depth of the objective lens 3 by each shot (the Z-axis position of the irradiated surface changes to the minus side). In addition, since it is assumed that the processed surface is roughened, it is desirable that the reflected light used for the real-time monitor is reflected light from the first shot irradiated on the workpiece 41.

  As the processing time increases, the mask 1, the objective lens 3 and other optical components may accumulate heat and their optical characteristics may change. Thereby, the focus position confirmed in the above-described steps (1) and (2) may not be maintained on the irradiated surface of the workpiece 41. Further, the same focal position abnormality may occur due to the thickness distribution abnormality of the workpiece 41 in the Z-axis direction and the non-straightness of the processing stage.

  Therefore, the confocal beam profiler according to the present embodiment monitors these focal position abnormalities in real time by image analysis, and when the imaging position deviates from a predetermined allowable range, the Z axis for the objective lens 3 is used. Feedback is applied to the Z-axis stage on which the stage or the workpiece 41 is placed, and the imaging state is returned to the allowable range.

  Specifically, as shown in FIG. 11A, the reflected light from the workpiece 41 is received by the imaging surface of the imaging device 61, and an edge (rising: Ascent, falling: Descent) at the boundary of the lateral mode distribution. Analyze the sharpness. In this example, the sharpness was confirmed by the edge width (Asc-Length or Desc-Length) required for the cross section of the laser beam at the edge to change from 30% to 65% of the maximum value. .

  As shown in detail in FIG. 11B, the edge width at the falling edge is 0.004 mm. And when this edge width is less than 0.008 mm is set as the allowable range (upper limit), and when the edge width deviates from this range during processing (when the upper limit value is exceeded), The focus position was readjusted before moving to the next workpiece 41. The readjustment was performed in accordance with the relationship between the amount of movement of the Z-axis stage and the amount of change in edge width.

  Further, during the processing of one workpiece 41, for example, when the above allowable range is deviated due to the abnormal thickness distribution, the ongoing processing process is temporarily stopped and the focal position is adjusted. It is also possible to program to do.

  In the first embodiment described above, in order to monitor the shape of the laser beam that is reduced and projected onto the workpiece 41 in real time, the reflected light from the irradiated surface at the stage before being processed and roughened by the laser beam is used. That is, the irradiation light by the first shot irradiated to the irradiated surface was monitored.

  As an embodiment different from this, in this embodiment, the pulse energy of the laser beam that has passed through the mask 1 which is “1” for convenience in the embodiment 1 is set to 0.25 which is a quarter of the pulse energy, and is reduced and projected. A situation was created in which the workpiece 41 was not processed by the laser beam.

Specifically, in this embodiment using polyimide for the workpiece 41, the actual energy density on the irradiated surface is 50 mJ / cm ^2, and the irradiated surface is processed by a laser beam regardless of the number of shots. The condition setting was not set. Irradiation with such an energy density is a pseudo processing state that cannot be actually processed, but in an environment close to actual processing regardless of the number of laser shots irradiated to the workpiece 41. The shape of the laser beam projected in a reduced scale can be monitored in real time.

  However, in this case, various optical members absorb the laser beam and change the optical characteristics caused by storing the laser beam is different from the actual processing because the pulse energy of the laser beam is low and the heat storage amount is small. Note that the monitoring result is obtained.

  It can be used for a high-resolution laser processing apparatus equipped with a reduction imaging optical system.

DESCRIPTION OF SYMBOLS 1 Mask 11 Processing mask pattern 12 Adjustment cross pattern 13 First reflected light image 14 Second reflected light image 2 Non-total reflection mirror 21 Non-total reflection mirror normal 3 Objective lens 41 Non-processing object 42 For adjustment Optical member 5 Processing stage 61 Imaging device 62 Analysis device 71 Confocal position correction plate 711 Normal line of confocal position correction plate 72 Band pass filter 8 Excimer laser

Claims (8)

At least a reduction imaging optical system including a mask, a mirror, and an objective lens in this order, and a laser processing apparatus including a stage on which an object to be processed is mounted. A beam profiler comprising an imaging device that monitors the transverse mode distribution and its imaging state, and an analysis device that analyzes the captured image data,
The mirror is a non-total reflection mirror that transmits a part of the laser beam,
The imaging device has an imaging surface at a position where the pattern drawn on the mask is projected and reduced by the objective lens and is beneficial.
The imaging surface receives reflected light from the workpiece that has passed through the non-total reflection mirror,
A beam profiler characterized by that.   2. The beam profiler according to claim 1, wherein the analysis device monitors an imaging state on an irradiated surface of the object to be processed by cross section analysis with respect to a transverse mode distribution of laser beam intensity.   3. The image pickup device of the image pickup apparatus according to claim 1, wherein each side of the pixel size is equal to or less than a numerical value of a product of a reduction ratio of the reduction imaging optical system and a required processing resolution. Crab beam profiler. The beam profiler further juxtaposes an adjustment optical member that can be switched to a workpiece on the stage,
The adjustment optical member is a material that reflects a part of the laser beam and transmits the other, and the height of the surface irradiated by the laser beam of the adjustment optical member is the height of the workpiece. The beam profiler according to any one of claims 1 to 3, wherein the beam profiler has the same height as the irradiated surface.   The beam profiler according to any one of claims 1 to 4, wherein the adjustment optical member is a wedge plate having a back surface having an angle with respect to the front surface. The reduced imaging optical system is an image side or both side telecentric optical system,
The adjusting optical member is a plane parallel plate,
Two reflected lights from the front and back surfaces of the parallel plane plate are both imaged by the imaging device,
The beam according to any one of claims 1 to 4, wherein the analysis device can confirm the telecentricity on the image side of the telecentric optical system by analyzing the captured images of the two reflected lights. Profiler. A confocal position correction plate between the non-total reflection mirror and the imaging surface;
In the confocal position correction plate, the reflected light from the workpiece has the same material and thickness as the non-total reflection mirror, and the normal line is around the normal line and the optical axis of the non-total reflection mirror. The beam profiler according to any one of claims 1 to 6, which is in a state rotated by 90 °. The beam profiler according to any one of claims 1 to 7, further comprising a band-pass filter that transmits only a wavelength of laser light between the imaging surface and the non-total reflection mirror.