JP4444883B2 - Beam homogenizer, laser processing apparatus and laser processing method - Google Patents

Description

  The present invention relates to a beam homogenizer and a laser processing method for uniformizing an intensity distribution in a beam cross section of a laser beam.

  FIG. 9 is a cross-sectional view of the beam homogenizer 90 disclosed in Patent Document 1. Consider an XYZ orthogonal coordinate system in which the direction parallel to the optical axis of the laser beam L incident on the beam homogenizer 90 is the Z direction. FIG. 9 is a cross-sectional view parallel to the XZ plane. The beam homogenizer 90 has a pair of lens arrays 91 and 92 and a converging lens 93.

  Each of the lens arrays 91 and 92 is configured by arranging seven cylindrical lenses in which the lens optical axis is parallel to the Z-axis and the cylindrical generatrix is parallel to the Y-axis in the X direction. The lens optical axes of the cylindrical lenses constituting the front lens array 91 coincide with the lens optical axes of the corresponding cylindrical lenses constituting the rear lens array 92.

  The laser beam L is divided into seven beam bundles corresponding to each cylindrical lens by the lens array 91 in the previous stage. In FIG. 9, only the light bundles at the center and both ends are shown as representatives. The light beam focused by the front lens array 91 is further focused by the rear lens array 92. Each light bundle emitted from the lens array 92 at the subsequent stage is once condensed in front of the converging lens 93 and then enters the converging lens 93 as a divergent light bundle.

  The converging lens 93 superimposes all of the seven divergent light bundles incident thereon on a common area in the homogenizing surface 94. As a result, the in-section intensity distributions (hereinafter referred to as profiles) of the divergent light bundles are added together in a common region within the homogenized surface 94. As a result, the profile in the X direction is made uniform.

JP 2002-25933 A

  In the conventional beam homogenizer 90, the maximum incident angle of each divergent light beam emitted from the converging lens 93 with respect to the homogenized surface (irradiated surface) 94 is, for example, about 18 °. Here, the maximum incident angle of the light beam with respect to the irradiated surface refers to the incident angle of the light beam having the largest incident angle with respect to the irradiated surface among the light beams constituting the light beam. From the viewpoint of improving the processing quality, there is a case where it is desired to make the light beam incident substantially perpendicular to the irradiated surface.

  An object of the present invention is to provide a beam homogenizer capable of bringing a light beam incident on an irradiated surface close to being perpendicular to the irradiated surface. Another object of the present invention is to provide a technique capable of improving the processing quality of laser processing. Another object of the present invention is to provide a technique capable of increasing the processing efficiency of laser processing.

  According to one aspect of the present invention, a beam homogenizer that causes a laser beam to be incident on a linear long region that is long in one direction on a surface to be irradiated, the incident laser beam being a long region of the long region. A splitting optical element that splits a plurality of beams with respect to a direction corresponding to a direction, and a beam cross section of the plurality of split beams obtained by splitting with the splitting optical element are arranged in the longitudinal direction on the irradiated surface. The split beams are guided to the irradiated surface so that beam cross sections adjacent to each other in the longitudinal direction partially overlap, and the maximum incident angle of each of the split beams to the irradiated surface is A beam homogenizer provided with a superposition optical system that is 5 ° or less is provided.

Here, the maximum incident angle of a split beam refers to the incident angle of a light beam having the largest incident angle on the irradiated surface among all the light beams constituting a plurality of split beams.
According to another aspect of the present invention, a step of dividing one laser beam into a plurality of divided beams with respect to a position in the beam cross section, and an attitude such that a bus bar on a column surface intersects the first direction. In the irradiated surface of the lens array composed of a plurality of convex cylindrical lenses arranged along the irradiated surface, each beam cross section of the split beam has a long shape in the first direction, The beam cross sections of the divided beams are arranged in the first direction, and the beam cross sections adjacent to each other partially overlap each other, and the light intensity distribution in the first direction of the overlapped beam cross sections is the one A step of directing the split beam to the lens array so as to approach a light intensity distribution in a direction corresponding to the first direction of the laser beam; and a split bea guided to the lens array The arm, the step of entering the treated surface through the lens array, the incident position of the laser beam, the first to move in a second direction crossing the direction, the surface to be processed and the laser beam And a step of moving at least one of the laser processing method.

  In the beam homogenizer, the beam cross sections of all the divided beams do not overlap on the same region, but the beam cross sections of the adjacent divided beams with respect to the longitudinal direction are only partially overlapped. The maximum incident angle of the split beam on the irradiated surface can be 5 ° or less. Thereby, the processing quality of laser processing can be improved.

  In the laser processing method, a plurality of regions each extending in a direction parallel to the generatrix of the convex cylindrical lens are collectively processed by moving at least one of the processing surface and the laser beam in the second direction. Can do. For this reason, it becomes possible to improve the processing efficiency of laser processing.

  FIG. 8A shows a cross-sectional view of an object 80 to be processed by laser processing. The workpiece 80 includes a flat plate portion 81, a lens array portion 82 formed on the surface of the flat plate portion 81, and a film 83 to be processed formed on the back surface of the flat plate portion 81. Consider an STU orthogonal coordinate system in which the thickness direction of the plate-like portion 81 is the S direction. The lens array unit 82 is configured by arranging a plurality of equivalent convex cylindrical lenses in which the generatrix of each cylindrical surface is parallel to the U direction and the lens optical axis is parallel to the S direction, arranged in the T direction. The flat plate portion 81 and the lens array portion 82 are made of a material that transmits near infrared rays, for example, polyethylene terephthalate (PET). The film 83 to be processed is made of a material that absorbs near infrared rays, specifically, a material containing carbon.

  A linear beam L having a wavelength in the near infrared region and elongated in the T direction is incident on the workpiece 80 from the lens array portion 82 side. The length of each cylindrical lens constituting the lens array unit 82 in the T direction is shorter than the length of the linear beam L in the long direction (T direction). When the linear beam L is made incident on the workpiece 80, the lens array section 82 divides the linear beam L into a plurality of pieces in the T direction, and each of the divided beam bundles on the surface of the film 83 to be processed within the ST plane. Condensed on the surface to be processed. As a result, the film 83 to be processed is removed at the position where the convergent light beam obtained by being divided by the lens array unit 82 is incident. In this way, a plurality of removed portions each extending in the U direction are formed in the processed film 83 by moving the workpiece 80 in the U direction while removing a part of the processed film 83. Can do.

  FIG. 8B shows a workpiece 80 in which a plurality of removed portions 84 are formed on the film 83 to be processed. Thus, the thing in which the some removal part 84 was formed is used as the image projection screen of a projection type television.

  Here, it is considered that the conventional homogenizer 90 shown in FIG. 9 is used to form the linear beam L for processing the workpiece 80. The X, Y, and Z directions in FIG. 9 correspond to the T, U, and S directions in FIGS. 8A and 8B, respectively. In this case, the following problems arise. That is, since each of the light bundles emitted from the homogenizer 90 of FIG. 9 is diverging, when these divergent light bundle groups are used as the linear beam L, the light beams constituting the linear beam L are converted into the TU of FIG. It is not perpendicular to the plane. For this reason, the converging position of the convergent light beam divided by the lens array unit 82 is aligned with the surface (processed surface) of the film 83 to be processed, and the intervals in the T direction between adjacent condensing positions are equalized. There is room for improvement.

  On the other hand, in the case where the light beam constituting the linear beam L is brought close to perpendicular to the surface to be processed, the length of the linear beam L in the longitudinal direction (T direction) is the longitudinal direction of the lenses constituting the hosizer. The lens has an influence on the focusing or divergence of the beam, and is approximately the same as the diameter of the lens arranged closest to the processing surface. At present, it is difficult to accurately manufacture a glass lens having a diameter of 800 mm or more. For this reason, when making the light beam which comprises the linear beam L near perpendicular | vertical to a to-be-processed surface, it becomes difficult to lengthen the length of the T direction of the linear beam L to 800 mm or more. Accordingly, there is a problem with increasing the length of the linear beam L in the T direction as much as possible to improve the processing efficiency of the processing target 80. Then, the laser irradiation apparatus devised by the inventor to solve the problems described above will be described below.

FIG. 1 shows a schematic diagram of a laser irradiation apparatus according to an embodiment. The light source 1 emits the laser beam _{L 1.} Light source 1 consists of a YAG laser oscillator, the laser beam L ₁ has a wavelength in the near infrared region. Note that another light source laser or a semiconductor laser may be used as the light source 1. Beam homogenizer 2 converts the laser beam L ₁ emitted from the light source 1 into a linear beam L _2. A linear beam L ₂ is incident on the irradiated surface 3.

Figure 2 is a diagram showing an irradiation region R of the linear beam L ₂ on the surface to be illuminated 3. The irradiation region R has a linear shape that is long in one direction. Here, in a plane parallel to the surface to be illuminated 3 of Figure 1, the irradiation region (hereinafter,. As long region) the longitudinal direction of R and X ₁ direction, X ₁ to a short direction and Y ₁ direction Define a Y ₁ Cartesian coordinate system.

Hereinafter, with reference to FIGS. 3 and 4, the beam homogenizer 2, illustrating the manner of propagation of the light beam in parallel to the cross section in a direction corresponding to the longitudinal direction (X ₁ direction) of the long region R.
FIG. 3 is a sectional view of a part of the optical system constituting the beam homogenizer 2. Consider an X ₂ Y ₂ Z ₂ orthogonal coordinate system in which the direction parallel to the optical axis of the laser beam L ₁ is the Z ₂ direction. FIG. 3 is a cross-sectional view parallel to the X ₂ Z ₂ plane. X ₂ direction corresponds to the longitudinal direction of the long area R in FIG. 2 _{(X 1} direction). The Z ₂ direction, the cylindrical lens _CL 1 -CL ₆ of first to sixth, lens array LA, and seventh to tenth cylindrical lens _CL 7 _{-CL 10,} and the convex mirror _{M 1} are arranged in this order.

The laser beam _{L 1} will pass through the first to third cylindrical lens _CL 1 -CL _3, enters the fourth cylindrical lens CL _4. The first to third cylindrical lenses CL _{1 to} CL ₃ do not have a lens action in the X ₂ Z ₂ plane. The fourth cylindrical lens CL ₄ of diverging laser beam. The laser beam emitted from the fourth cylindrical lens CL ₄ is incident through the cylindrical lens CL ₅ of the fifth to the sixth cylindrical lens CL ₆ of. The fifth cylindrical lens CL _{5 of,} no lens action is X 2 _{Z 2} plane. Cylindrical lens CL ₆ of the sixth, closer to parallel light beams of the laser beam incident on self. 4 and the cylindrical lens CL ₄ and CL ₆ sixth, serve as expander for expanding the beam diameter of the laser beam in the X ₂ direction. The laser beam emitted from the cylindrical lens CL ₆ The sixth incident on the lens array LA.

Lens arrays LA are each lens optical axis was parallel to the Z ₂ axes, equivalent nine convex cylindrical lens busbars and parallel to the Y ₂ axis of the cylinder surface is configured to be arranged in the X ₂ direction . Lens array LA is a laser beam incident on the self-divided into nine terms X ₂ direction position, forming a nine split beams. In FIG. 3, for the sake of convenience, the center beam and the beam at both ends are representatively shown for each of the three split beams La, Lb, and Lc. Each divided beam emitted from the lens array LA is incident through the cylindrical lens _CL 7 _{-CL 10} of the seventh to tenth to convex mirror _{M 1.}

The seventh and eighth cylindrical lenses CL ₇ and CL ₈ are convex cylindrical lenses, and the ninth and tenth cylindrical lenses CL ₉ and CL ₁₀ have no lens action in the X ₂ Z ₂ plane. Convex surface of the convex mirror M ₁ is spherical. Incidentally, the convex surface of the convex mirror M ₁ may be a paraboloid. Each divided beam emitted from the lens array LA is converged in the seventh and the cylindrical lens CL ₇ and CL ₈ eighth, connecting once focus in front of the convex surface mirror M _1. Then, incident on the convex mirror M ₁ becomes divergent light beam.

4 is a cross-sectional view of the remaining portion of the optical system constituting the beam homogenizer 2 of FIG. Both the facing position of the convex mirror M ₁ and the illuminated surface 3 shown in FIG. 3, the concave mirror M ₂ is disposed. Concave concave mirror M ₂ is spherical. Incidentally, the concave surface of the concave mirror M ₂ may be a paraboloid.

As shown in FIG. 4 (a), each divided beam reflected by the convex mirror M ₁ is incident on the concave mirror M _2. In FIG. 4A, only the split beams La, Lb, and Lc shown in FIG. 3 are shown as representatives. With each divided beam reflected by the convex mirror M ₁ is a divergent bundle of rays, the spacing of the central optical axis thereof divergent light beam spreads as the distance from the convex mirror M _1.

As shown in FIG. 4B, each split beam reflected by the concave mirror M ₂ enters the irradiated surface 3 through the gradation filter F. FIG. 4B also shows only the split beams La, Lb, and Lc as representatives. The concave mirror M ₂ is brought close to the split beam reflected by the convex mirror M ₁ into a parallel light beam, and also close parallel optical axes of the plurality of split beams which are close to their parallel light flux. The nine split beams reflected by the concave mirror M ₂ constitute the linear beam L ₂ shown in FIG.

Beam cross-section of the split beam reflected by the concave mirror M ₂ is arranged in the X ₁ direction on the surface to be illuminated 3 (longitudinal direction of the long region R of FIG. 2). Beam cross-section adjacent to one another with respect to X ₁ direction overlap only partially. With such a configuration, the maximum incident angle of each split beam on the irradiated surface 3 can be set to 5 ° or less. Here, the maximum incident angle of a split beam refers to the incident angle of a light beam having the largest incident angle to the irradiated surface 3 among all the light beams constituting each of the split beams.

Note that in principle it is also possible to use an equivalent convex lens instead of the concave mirror M _2. However, at present, it is difficult to manufacture a lens having a diameter of 800 mm or more. In this regard, in the present embodiment, by using a concave mirror M ₂ instead of the convex lens, comprising a beam width in the X ₁ direction of the linear beam L ₂ can be greater than or equal 800 mm.

Split beam reflected by the concave mirror M _2, since the beam cross-section adjacent to X ₁ direction overlap in part, the light intensity distribution in the X ₁ direction in the surface of the irradiated surface 3, the light source 1 of FIG. 1 than the light intensity distribution in the direction corresponding to the X ₁ direction of the laser beam L emitted approach uniform. Further, the gradation by a filter F is arranged, which can further enhance the uniformity of the light intensity distribution for comparison when X ₁ direction when not disposed. That is, the gradient filter F has a X ₁ direction about such as uniformity of the light intensity distribution is enhanced, the distribution of light attenuation factor is changed to X ₁ direction by placing it.

Figure 5 shows the X ₁ direction of the light intensity distribution on the illuminated surface 3. The horizontal axis indicates the position of X ₁ direction, the vertical axis indicates the light intensity. 5, the laser beam L ₁ emitted from the light source 1 of FIG. 1 has a Gaussian-like profile, and the light intensity distribution obtained when omitting the gradient filter F in Figure 4 (b). Except for the X ₁ direction end portion, the light intensity distribution are substantially flat. Specifically, the top flat of the light intensity distribution for X ₁ direction, it was possible to 0.853. Here, the top flat rate R means that the width of a portion having an intensity of 90% or more of the maximum value of the light intensity distribution is W ₁ , and the width of a portion having an intensity of 50% or more of the maximum value is W _2. , R = W ₁ / W ₂ . The value of _{W 1} in this embodiment is 1497Mm, the value of _{W 2} is 1755Mm.

Next, with reference to FIGS. 6 and 7, the beam homogenizer 2, a state of propagation of the light beam in the cross section parallel to a direction corresponding to the shorter direction of the long area R in FIG. 2 (Y ₁ direction) explain.
FIG. 6 is a cross-sectional view parallel to the Y ₂ Z ₂ plane of the optical system shown in FIG. Y ₂ direction corresponds to the short direction of the long area R in FIG. 2 _{(Y 1} direction). The laser beam L _1, after being diverged by the first cylindrical lens CL _1, further diverged by the second cylindrical lens CL _2. Laser beam diverged by the second cylindrical lens CL ₂ is brought close to parallel light flux by the third cylindrical lens CL _3, incident on the fifth cylindrical lens CL ₅ through the fourth cylindrical lens CL ₄ To do. The fourth cylindrical lens CL ₄ of _the no lens action by Y 2 _{Z 2} plane. The fifth cylindrical lens CL _5, even more closer to parallel light beams of the light beams emitted from the third cylindrical lens CL _3. The first and second cylindrical lenses CL ₁ and CL ₂ and the third and fifth cylindrical lenses CL ₃ and CL ₅ function as an expander that expands the beam diameter of the laser beam in the Y ₂ direction. .

The beam emitted from the cylindrical lens CL ₅ of the fifth, a cylindrical lens CL ₆ of the sixth lens array LA, and passes through the seventh and the cylindrical lens CL ₇ and CL ₈ eighth, ninth and tenth The light enters the cylindrical lenses CL ₉ and CL ₁₀ . The sixth cylindrical lens CL ₆ , the lens array LA, and the seventh and eighth cylindrical lenses CL ₇ and CL ₈ have no lens action in the Y ₂ Z ₂ plane. The synthetic lens including the ninth and tenth cylindrical lenses CL ₉ and CL ₁₀ converges the beam incident thereon. The beams converged by the ninth and tenth cylindrical lenses CL ₉ and CL ₁₀ are incident on the convex mirror M ₁ .

FIG. 7 is a schematic view of the remaining part of the optical system constituting the beam homogenizer 2. The beam reflected by the convex mirror M ₁ is reflected by the concave mirror M ₂ and enters the irradiated surface 3. The optical system is adjusted so that the optical axis of the beam reflected by the concave mirror M ₂ is perpendicular to the irradiated surface 3. The concave mirror M ₂ is, for converging the beam on the irradiated surface 3, shortening of about Y ₁ direction of the long region R of FIG. 2 is achieved. In FIG. 7, the gradation filter F in FIG. 4B is not shown for convenience.

Table 1 lists the radii of curvature of the first to tenth cylindrical lenses CL _{1 to} CL ₁₀ and the lens array LA. The unit of the numerical values in Table 1 is mm. In Table 1, “incident surface” refers to the surface on the side where the lens light enters, and “exit surface” refers to the surface on the side where the lens light exits. A positive value for the radius of curvature indicates that the surface is convex, and a negative value for the radius of curvature indicates that the surface is concave. Further, a curvature radius of ∞ indicates that the surface is a plane. Further, the radius of curvature of the incident surface of the lens array LA indicates the radius of curvature of the incident surface of each cylindrical lens constituting the lens array LA.

表２に、凸面鏡Ｍ_１の凸面及び凹面鏡Ｍ_２の凹面の曲率半径を掲げる。表２中の数値の単位はｍｍである。

Table 2 below provides the radius of curvature of the concave surface of the convex and the concave mirror M ₂ of the convex mirror M _1. The unit of numerical values in Table 2 is mm.

表３に、ホモジナイザ２を構成する各シリンドリカルレンズの厚さ及び隣り合う光学素子間の距離を掲げる。表３中の数値の単位はｍｍである。ｉを自然数としたとき、ＣＬ_ｉ〜ＣＬ_ｉ＋１間の距離とは、第ｉのシリンドリカルレンズＣＬ_ｉの出射表面から、第ｉ＋１のシリンドリカルレンズＣＬ_ｉ＋１の出射表面までの距離のことである。

Table 3 lists the thickness of each cylindrical lens constituting the homogenizer 2 and the distance between adjacent optical elements. The unit of numerical values in Table 3 is mm. When i is a natural number, the distance between CL _{i to} CL _{i + 1} is the distance from the exit surface of the i- _th cylindrical lens CL _{i to} the exit surface of the i + 1-th cylindrical lens CL _{i + 1} .

また、第１〜第１０のシリンドリカルレンズＣＬ_１〜ＣＬ_１０及びレンズアレイＬＡは、合成石英（ＳｉＯ_２）からなり、その屈折率は約１．４６である。以上説明した条件でビームホモジナイザ２を構成した場合、図１の光源１から出射されるレーザビームＬ_１のビーム断面の半径が約２．５ｍｍのとき、図２の長尺領域Ｒの長尺方向（Ｘ_１方向）の長さを１２００ｍｍ以上とすることができた。また、線状ビームＬ_２を構成する分割ビームの最大入射角を約３°とすることができた。

The first to tenth cylindrical lenses CL _{1 to} CL ₁₀ and the lens array LA are made of synthetic quartz (SiO ₂ ) and have a refractive index of about 1.46. Case where the beam homogenizer 2 under the conditions described above, when the radius of the beam cross-section of the laser beam L ₁ emitted from the light source 1 of FIG. 1 is about 2.5 mm, the longitudinal direction of the elongated region R in FIG. 2 a length of _{(X 1} direction) could be at least 1200 mm. Also, it could be about 3 ° the maximum incident angle of the split beams constituting the linear beam L _2.

Next, a laser processing method using the laser irradiation apparatus of FIG. 1 will be described. The linear beam L ₂ emitted from the beam homogenizer 2 in FIG. 1, is used as the linear beam L in FIG. 8 (a). That is, the X ₁ and Y ₁ directions in FIG. 2 correspond to the T and U directions in FIG. 8, respectively. A surface (processed surface) in contact with the back surface of the flat plate-shaped portion 81 of the processed film 83 is disposed at the position of the irradiated surface 3 in FIG. The linear beam L is linear beam L ₂ in FIG. 1, when the incident from the lens array portion 82 side, a lens array 82 is divided into a plurality of linear beam L in the T direction (X ₁ direction), divided Each of the light bundles thus collected is condensed on the surface of the film 83 to be processed (processed surface) within the ST plane. As a result, the film 83 to be processed is removed at the position where the convergent light beam obtained by being divided by the lens array unit 82 is incident. In this way, while removing a portion of the film to be processed 83, the workpiece 80 by moving the U direction (Y ₁ direction), removal of the plurality of which extends in each direction U film to be processed 83 A part can be formed.

According to this laser processing method, since the light intensity distribution for linear beam L ₂ of the T direction (X ₁ direction) is uniform, the work of the convergent light beam obtained by being divided by the lens array 82 The intensity at the surface of the film 83 can be made uniform between the convergent beam bundles. For this reason, the width of the removal portion 84 is equalized. That is, the processing quality of laser processing can be improved.

Also, when considering a virtual plane parallel to the flat plate portion 81, it is possible to enter the linear beam L ₂ under the condition that the incident angle with respect to the virtual plane is 5 ° or less in the object 80, the lens array distance divided by the resulting convergence light beam condensing position of the processed film 83 surface by part 82 can be aligned to (the processing surface), and adjacent T direction of the focusing position (X ₁ direction) Can be made even. Therefore, it is possible to equalize the interval T direction of the removal portion 84 adjacent (X ₁ direction). That is, the processing quality of laser processing can be improved.

Moreover, the linear order of the beam width of the beam _{L 2} in the T direction _{(X 1} direction) can be elongated into above 1200 mm, once in the U direction of the object 80 by the moving mechanism _{(Y 1} direction) The number of removal portions 84 that can be formed by the translational movement can be increased. That is, the processing efficiency of laser processing can be increased.

In the present embodiment, although the generatrix direction and the longitudinal direction of the linear beam L ₂ of the cylindrical surface of the cylindrical lenses constituting the lens array 82 and (T direction) was constructed orthogonal, these directions It only has to cross. Further, it is assumed that moving the workpiece 80, at least one of the workpiece 80 and the linear beam L ₂ may be moved. Direction of movement of the object 80 or the linear beam L ₂ may not necessarily be a U direction perpendicular to the T direction, may be a direction intersecting the T direction.

  As mentioned above, although the Example was described, this invention is not limited to this. In the embodiment, the removal processing of the film to be processed is exemplified, but the beam homogenizer of the present invention can be applied to the modification of the irradiated surface, for example, crystallization annealing of the amorphous silicon film. It will be apparent to those skilled in the art that various modifications, improvements, combinations, and the like can be made.

It is the schematic of the laser irradiation apparatus by an Example. It is a diagram which shows the incident area | region of the linear beam on a to-be-irradiated surface. It is sectional drawing of a part of optical system which comprises a beam homogenizer. It is sectional drawing of the remainder of the optical system which comprises a beam homogenizer. It is a graph which shows the light intensity distribution regarding the elongate direction of a linear beam. It is other sectional drawing of a part of optical system which comprises a beam homogenizer. It is the schematic of the remainder of the optical system which comprises a beam homogenizer. It is sectional drawing of a process target object. It is sectional drawing of the conventional beam homogenizer.

Explanation of symbols

1 ... light source, 2 ... a beam homogenizer, 3 ... irradiated surface (the surface to be processed), L 1 _... laser beam, L 2 _... linear beam, R ... irradiated region (elongated _region), CL 1 _{-CL 10} ... a cylindrical lens, LA ... lens array (splitting optical element), M 1 _... convex mirror, M 2 _... concave mirror, F ... gradient filter, 80 ... workpiece, 81 ... flat plate portion, 82 ... lens array unit, 83 ... object to be processed Membrane, 84 ... removed portion, 91 ... front lens array, 92 ... rear lens array, 93 ... converging lens, 94 ... homogenized surface.

Claims (8)

A beam homogenizer that makes a laser beam incident on a linear long region that is long in one direction on an irradiated surface,
A splitting optical element that splits a laser beam incident thereon into a plurality of beams in a direction corresponding to a longitudinal direction of the long region;
Beam sections of a plurality of split beams obtained by splitting with the split optical element are arranged in the longitudinal direction on the irradiated surface, and beam sections adjacent to each other in the longitudinal direction are partially A beam homogenizer provided with a superimposing optical system in which the divided beams are guided to the irradiated surface so as to overlap each other, and each of the divided beams has a maximum incident angle of 5 ° or less to the irradiated surface.   Furthermore, the beam homogenizer of Claim 1 provided with the gradation filter from which attenuation amount changed regarding the said elongate direction.   3. The beam homogenizer according to claim 1, wherein the superposition optical system expands a beam width of an incident laser beam in a direction corresponding to a short direction of the long region, and then converges the laser beam on the irradiated surface. . A beam homogenizer according to any one of claims 1 to 3,
A light source for injecting a laser beam into the beam homogenizer;
A position where a laser beam emitted from the beam homogenizer is incident; (i) a plate-like portion arranged in parallel to the irradiated surface; and (ii) a lens array portion formed on the surface of the plate-like portion. A plurality of convex cylindrical lenses, each having a cylindrical surface generating line parallel to a first direction intersecting the longitudinal direction of the elongated region, are arranged in a second direction orthogonal to the first direction. A holding base for holding a processing object having a lens array portion configured as described above, and (iii) a film to be processed formed on the back surface of the flat plate portion,
A laser processing apparatus comprising: a moving mechanism that moves the holding table in the first direction.   The light source emits a laser beam having a wavelength in the near infrared region, and the plate-like portion and the lens array portion are made of a material that transmits the laser beam having a wavelength in the near infrared region. The laser processing apparatus according to claim 4, comprising a material that absorbs a laser beam having a wavelength. Splitting one laser beam into a plurality of split beams with respect to positions in the beam cross section;
Each beam of the split beams on the irradiated surface of a lens array composed of a plurality of convex cylindrical lenses arranged along the irradiated surface in such a posture that the generatrix of the column surface intersects the first direction. The cross-section has a shape that is long in the first direction, the beam cross-sections of the plurality of split beams are arranged in the first direction, and the beam cross-sections adjacent to each other partially overlap each other, and overlap each other. Directing the split beam to the lens array so that the light intensity distribution in the first direction of the laser beam is more uniform than the light intensity distribution in the direction corresponding to the first direction of the one laser beam. When,
A step of causing the split beam guided to the lens array to enter the processing surface through the lens array;
Moving the at least one of the surface to be processed and the laser beam such that the incident position of the laser beam moves in a second direction intersecting the first direction. The laser processing method according to claim 6 , wherein the split beam is incident on the lens array under a condition that a maximum incident angle with respect to the irradiated surface is 5 ° or less. The laser processing method according to claim 6 or 7 , wherein a length of a beam cross section on the irradiated surface is 1200 mm or more.

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