Laser processing apparatus and laser processing method

Abstract

We provide a laser processing device used for processing semiconductor devices. [Solution] A laser processing apparatus is provided, comprising: at least one laser oscillator that outputs a laser beam; at least one beam adjustment element that adjusts the shape of the laser beam output from the laser oscillator; at least one lens positioned between the beam adjustment element and the workpiece, which adjusts the size of the laser beam whose shape has been adjusted by the beam adjustment element and irradiates the workpiece with it; and a controller that sets the processing line width to be formed on the workpiece, determines the rotation angle of the beam adjustment element according to the set processing line width, and controls the beam adjustment element to rotate with respect to a rotation axis parallel to the normal of the plane of the workpiece according to the determined rotation angle.

Description

Technical Field

[0001] The present invention relates to a laser processing apparatus and a laser processing method used for processing semiconductor elements.

Background Art

[0002] When processing a semiconductor element, laser patterning can be performed to precisely form a desired pattern on the workpiece by utilizing a laser. Also, in the process of semiconductor chip separation (dicing) and chip packaging, laser grooving can be performed to form precise grooves on the workpiece.

[0003] A laser processing apparatus for performing such laser processing must also change the shape of the laser beam irradiated on the workpiece according to the type of the workpiece to be laser processed, the specifications and patterns of the processing shape, the process method, etc. For this purpose, the type and size of the optical unit included in the laser processing apparatus must also be changed accordingly.

[0004] However, changing the optical unit according to various processing specifications is accompanied by not only technical limitations but also a decrease in production yield, a decrease in processing quality, an increase in processing defects, and cost problems. The configuration of the optical unit is very complex. However, when changing and operating a plurality of elements included in the optical unit to satisfy various processing specifications, problems such as a decrease in processing quality and processing defects occur due to aberrations generated by the plurality of elements included in the optical unit, and thus there is a drawback that the production yield decreases.

Summary of the Invention

Problems to be Solved by the Invention

[0005] The present invention provides a laser processing apparatus and a laser processing method for adjusting the processing line width of a workpiece by rotating a beam adjustment element in the processing of semiconductor elements. The technical problems that this embodiment aims to solve are not limited to those described above, and other technical problems can be inferred from the following embodiments. [Means for solving the problem]

[0006] According to one aspect of the present invention, a laser processing apparatus for processing a workpiece is disclosed, comprising: at least one laser oscillator that outputs a laser beam; at least one beam adjustment element that adjusts the shape of the laser beam output from the laser oscillator; at least one lens positioned between the beam adjustment element and the workpiece, which adjusts the size of the laser beam whose shape has been adjusted by the beam adjustment element and irradiates the workpiece with it; and a controller that sets the processing line width to be formed on the workpiece, determines the rotation angle of the beam adjustment element according to the set processing line width, and controls the beam adjustment element to rotate with respect to a rotation axis parallel to the normal of the plane of the workpiece according to the determined rotation angle.

[0007] Here, the beam adjustment element is a one-dimensional diffractive optical element that divides the laser beam into a plurality of branched beams in a one-dimensional array, and the controller determines the rotation angle based on the radius of curvature of the branched beams that have passed through the lens and the spacing between adjacent branched beams that have passed through the lens.

[0008] Here, when a parallel axis (Lt) parallel to the direction in which the plurality of branched beams are arranged linearly and a reference axis (As) parallel to the machining direction intersecting the machining line width are defined, the rotation angle is selected within a range from 0 degrees, which is defined as the case when the parallel axis (Lt) and the reference axis (As) are parallel, to the range when the parallel axis (Lt) and the reference axis (As) are at an acute angle to each other.

[0009] Here, the beam adjustment element is a diffractive optical element for linear beam generation that adjusts the laser beam into a linear beam.

[0010] Here, the beam adjustment element is a cylindrical lens that adjusts the laser beam into a linear beam.

[0011] Here, when a parallel axis (Lt) parallel to the linear beam and a reference axis (As) parallel to the machining direction intersecting the machining line width are defined, the rotation angle is selected within a range from 0 degrees, defined as the case where the parallel axis (Lt) and the reference axis (As) are parallel, to 90 degrees, defined as the case where the parallel axis (Lt) and the reference axis (As) are perpendicular.

[0012] This further includes a beam limiting element, which is positioned between the beam adjusting element and the lens and blocks a portion of the laser beam whose shape has been adjusted by the beam adjusting element.

[0013] Here, the beam limiting element is a slit or an aperture.

[0014] Here, the controller determines the cutoff range of the laser beam based on the rotation angle.

[0015] Here, the lens is an objective lens.

[0016] Here, the controller adjusts the size of the processed line width by adjusting the magnification due to the change in the focal length of the lens.

[0017] According to another aspect of the present invention, a laser processing method for processing a workpiece using a laser processing apparatus is disclosed, wherein the laser processing apparatus outputs a laser beam using a laser oscillator, adjusts the shape of the output laser beam using a beam adjustment element, adjusts the size of the laser beam whose shape has been adjusted using a lens and irradiates the workpiece with it, sets the processing line width to be formed on the workpiece using a controller, determines the rotation angle of the beam adjustment element according to the set processing line width, and controls the beam adjustment element to rotate with respect to a rotation axis parallel to the normal of the plane of the workpiece according to the determined rotation angle. [Effects of the Invention]

[0018] According to the problem-solving means of the present invention described above, various processing steps can be performed by adjusting the processing line width without changing the optical unit included in the laser processing apparatus.

[0019] Specifically, even with a single optical unit, it is possible to adjust the linear arrangement direction of the laser beam irradiated on the workpiece only by rotating the beam adjustment element, and to process the workpiece from a narrow range to a wide range.

[0020] In addition, since various processing specifications can be satisfied without changing the optical unit, it is possible to contribute to the simplification and stabilization of the process conditions.

Brief Description of the Drawings

[0021] [Figure 1] It is a diagram showing a laser processing apparatus according to an embodiment of the present invention. [Figure 2] It is a flowchart for explaining a laser processing method using the laser processing apparatus of FIG. 1. [Figure 3] It is an explanatory diagram for explaining a laser processing method when the beam adjustment element is a one-dimensional diffractive optical element that divides a laser beam into a plurality of branched beams in a one-dimensional array. [Figure 4] It is an explanatory diagram for explaining a laser processing method when the beam adjustment element is a diffractive optical element for generating a linear beam. [Figure 5] It is an explanatory diagram for explaining a laser processing method when the beam adjustment element is a cylindrical lens. [Figure 6] It is a photograph of the shape of the workpiece processed by the rotation angle determined by the controller when the beam adjustment element in FIG. 3 is a one-dimensional diffractive optical element. [Figure 7] It is an explanatory diagram for explaining the operation of the controller setting the rotation angle when the beam adjustment element in FIG. 3 is a one-dimensional diffractive optical element. [Figure 8] It is a diagram showing a laser processing apparatus according to another embodiment of the present invention. [Figure 9] This is an explanatory diagram illustrating a laser processing method using a laser processing apparatus that includes a beam limiting element. [Modes for carrying out the invention]

[0022] Hereinafter, embodiments of the present invention will be described in detail with reference to the attached drawings, so that they can be easily implemented by a person with ordinary skill in the art to which the present invention pertains. However, the present invention can be realized in a variety of different forms and is not limited to the embodiments described below. In the figures, parts unrelated to the explanation have been omitted in order to clearly illustrate the present invention, and similar parts throughout the specification are denoted by similar reference numerals.

[0023] In the following embodiments, terms such as "first," "second," etc., are not limited in meaning but are used to distinguish one component from another.

[0024] In the following embodiments, a singular expression shall include plural expressions unless the context clearly indicates otherwise.

[0025] In the following embodiments, terms such as "includes" and "has" mean that the features or components described in the specification are present, and do not preclude the possibility of the addition of one or more other features or components.

[0026] In the following embodiments, a part such as a membrane, region, or component being above or above another part includes not only cases where it is directly above another part, but also cases where another membrane, region, or component is interposed between them.

[0027] In the diagrams, the size of the components may be exaggerated or reduced for illustrative purposes. For example, the dimensions and thicknesses of each component shown in the drawings are arbitrary for illustrative purposes, and the present invention is not necessarily limited to those shown.

[0028] In the following embodiments, the x, y, and z axes are not limited to the three axes on the Cartesian coordinate system, but can be interpreted in a broader sense that includes them. For example, the x, y, and z axes may be orthogonal to each other, but they may also point in different directions that are not orthogonal to each other.

[0029] Where other implementations of a particular embodiment are possible, certain steps may be performed in an order different from that described. For example, two steps described consecutively may be performed substantially simultaneously, or they may be performed in the reverse order of their description.

[0030] The present invention will be described in detail below with reference to the attached drawings.

[0031] Figure 1 shows a laser processing apparatus 100 according to one embodiment of the present invention.

[0032] Referring to Figure 1, the laser processing apparatus 100 includes at least one laser oscillator 110, at least one optical unit 120, a processing table 130, and a controller 150.

[0033] The laser oscillator 110 may include a laser source capable of generating and outputting a laser beam having a specific wavelength. Furthermore, the type of laser beam output from this laser oscillator 110 is not particularly limited and can be appropriately selected according to the type of workpiece W and processing method. For example, the laser beam output from the laser oscillator 110 includes solid-state laser beams such as ruby ​​laser beams, Nd:YAG laser beams, and Ti:sapphire laser beams, as well as liquid laser beams such as dye laser beams, and CO2 laser beams, He-Ne laser beams, and Ar +This may be a laser beam, a gas laser beam including an excimer laser beam, or a UV (Ultraviolet) laser beam. The laser oscillator 110 is connected to the controller 150. Furthermore, the characteristics of the laser beam output from the laser oscillator 110, such as the output power, intensity, period, and output timing of the laser beam, can be controlled by signals generated from the controller 150.

[0034] The processing table 130 may be positioned so as to face the direction from which the laser is irradiated. The workpiece W is placed on the processing table 130. Furthermore, this processing table 130 can be moved in a set direction. For example, the machining table 130 can move in the X, Y, and Z directions. The operation of the processing table 130, such as its movement speed, direction of movement, and distance of movement, can be controlled by the controller 150. The processing table 130 may include a rotating stage.

[0035] The optical unit 120 may include at least one mirror 121m, at least one beam adjusting element 122s, and at least one lens 122l. Furthermore, this optical unit 120 adjusts the optical path of the laser beam La output from the laser oscillator 110, and can irradiate the laser beam L to a desired position on the workpiece W. Furthermore, the operation and position of the optical unit 120 can be controlled by the controller 150.

[0036] The mirror 121m can control the optical path of the laser beam La output from the laser oscillator 110. The number of mirrors 121m included in the laser processing apparatus 100 is not particularly limited, and the mirrors 121m may be galvano-mirrors. Mirror 121m can be controlled by controller 150.

[0037] The beam adjustment element 122s may be positioned between the mirror 121m and the lens 122l. The beam adjustment element 122s then adjusts the shape of the laser beam Lb, which is output from the laser oscillator 110 and whose optical path has been set. The beam adjustment element 122s adjusts the shape and distribution of the laser beam to form a specific pattern. Furthermore, this beam adjustment element 122s may also be a beam shaping element. The beam adjustment element 122s may be an element that changes the shape of the laser beam to be nearly linear. Here, "nearly linear" includes not only cases where the laser beam is linear, but also cases where the laser beam is a collection of multiple branched beams arranged in a linear fashion.

[0038] In one embodiment, the beam adjustment element 122s may be a one-dimensional diffractive optical element (1D DOE) that splits the laser beam into a plurality of branched beams in a one-dimensional array. In other embodiments, the beam adjustment element 122s may be a linear beam generating diffractive optical element that adjusts the laser beam into a linear beam, for example, a flat-top linear beam diffractive optical element. In yet another embodiment, the beam adjustment element 122s may be a cylindrical lens that adjusts the laser beam into a linear beam. Cylindrical lenses include, but are not limited to, cylindrical concave lenses and cylindrical convex lenses. The embodiments of the present invention are not limited thereto, and any beam adjustment element 122s can be used as long as it is an element that can adjust the laser beam to be substantially linear.

[0039] Furthermore, this beam adjustment element 122s can rotate with respect to a rotation axis parallel to the normal (vertical axis) of the plane of the workpiece W. In detail, the controller 150 can control the beam adjustment element 122s to rotate by a rotation angle (θ) around the rotation axis. Here, the axis of rotation may be parallel to the normal of the plane of the workpiece W. Furthermore, the axis of rotation can mean an axis that is parallel to the normal of the surface of the workpiece W and located in the center of the beam adjustment element 122s. The beam adjustment element 122s can change the linear alignment direction of the laser beam irradiated onto the workpiece W by rotating it.

[0040] The controller 150 can control each component of the laser processing apparatus 100. Furthermore, the controller 150 may be implemented as a processor by including at least one of the following: ASICs (application-specific integrated circuits), DSPs (digital signal processors), DSPDs (digital signal processing devices), PLDs (programmable logic devices), FPGAs (field programmable gate arrays), controllers, microcontrollers, microprocessors, and other electrical units for performing functions.

[0041] According to this embodiment, the controller 150 can set the machining line width formed on the workpiece W, determine the rotation angle (θ) according to the set machining line width, and control the beam adjustment element 122s to rotate according to the determined rotation angle (θ). The specific operation of controller 150 will be described later.

[0042] The lens 122l may be positioned between the processing table 130 and the mirror 121m. Then, this lens 122l focuses the laser beam Lc, whose shape has been adjusted after passing through the beam adjustment element 122s. The lens 122l adjusts the size of the shape-adjusted laser beam Lc and irradiates the workpiece W with the adjusted-size laser beam L. In one embodiment, the lens 122l may be at least one objective lens. However, lens 122l may include, in addition to at least one objective lens, any lens capable of focusing the laser beam, such as a telecentric lens, an f-theta lens, or a focusing lens. The drawing shows a case where there is one lens 122l, but there may be multiple lenses 122l. For example, lens 122l may be composed of multiple spherical lenses or planar lenses.

[0043] Figure 2 is a flowchart illustrating a laser processing method using the laser processing apparatus 100 shown in Figure 1. Figure 3 is an explanatory diagram illustrating a laser processing method when the beam adjustment element 122s is a one-dimensional diffractive optical element that splits the laser beam into multiple branched beams in a one-dimensional array. Figure 4 is an explanatory diagram illustrating a laser processing method when the beam adjustment element 122s is a diffractive optical element for linear beam generation. Figure 5 is an explanatory diagram illustrating a laser processing method when the beam adjustment element 122s is a cylindrical lens. Figures 3 to 5(a) show a plan view of the rotating beam adjustment element 122s, and Figures 3 to 5(b) show a cross-sectional view of the workpiece W. Figure 3(c) shows the workpiece W as a plan view.

[0044] Referring to Figure 2, in step 501, the controller 150 sets the width of the machining line to be formed on the workpiece W. Here, the processing line width can refer to the width of the laser-processed area formed on the surface of the workpiece by the laser beam during the laser processing process. In detail, the processing line width can refer to the width (D1, D2, D3, D4) of the processing region in the first direction (DR1) where the workpiece is processed, corresponding to the linear arrangement direction of the laser beam changed by the rotation of the beam adjustment element, as shown in Figures 3 to 5. Here, the first direction (DR1) may be a direction that intersects with the second direction (DR2) in which the laser beam is irradiated onto the workpiece on the cross-section of the workpiece, or it may be a direction that intersects with the third direction (DR3), which is the processing direction of the laser beam on the plane of the workpiece.

[0045] The controller 150 can set the machining line width based on the machining shape and size of the machining area of ​​the workpiece W. For example, when the processing shape and size of the processing area of ​​the workpiece W are input to the controller 150, the processing line width can be set using a table in which the processing line width is predetermined and mapped according to the processing shape and size of the processing area of ​​the workpiece W. Furthermore, the machining line width may be set by taking into consideration the material and thickness of the workpiece W, as well as the desired machining depth, as additional parameters. However, this is not the only option; the processing line width may also be set by user input.

[0046] In step 502, the controller 150 determines the rotation angle (θ) of the beam adjustment element according to the processing line width. Here, the rotation angle (θ) refers to the angle by which the beam adjustment element 122s, which is positioned opposite the surface of the workpiece W, rotates relative to the workpiece W. This rotation angle (θ) is determined based on the positional relationship between the laser beam irradiated onto the workpiece W and the workpiece W itself. Referring to Figure 3, the rotation angle (θ) can be defined as the angle that a parallel axis Lt, which is parallel to the direction in which the branched beams are arranged linearly, makes with respect to a reference axis As, which is parallel to the machining direction (third direction (DR3)) that intersects the machining line width when the laser beam irradiated onto the workpiece W has the narrowest machining line width relative to the workpiece W. Referring to Figures 4 and 5, the rotation angle (θ) can be defined as the angle that a parallel axis Lt, which is parallel to the linear beam, makes with respect to a reference axis As, which is parallel to the machining direction (third direction (DR3)) that intersects the machining line width when the laser beam irradiated onto the workpiece W has the narrowest machining line width relative to the workpiece W. In other words, in this specification, when the parallel axis Lt and the reference axis As are parallel, the rotation angle (θ) is defined as 0 degrees (°), and when the parallel axis Lt and the reference axis As are perpendicular, the rotation angle (θ) can be defined as 90 degrees (°). According to one embodiment, the rotation angle (θ) may be selected between 0 degrees (°), defined as the case where the parallel axis Lt and the reference axis As are parallel, and 90 degrees (°), defined as the case where the parallel axis Lt and the reference axis As are perpendicular.

[0047] On the other hand, by rotating the beam adjustment element 122s, the linear arrangement direction of the laser beam irradiated onto the workpiece W can be changed. The rotation angle (θ) can be defined as follows: the first angle is defined as the angle when the laser beam's linear alignment direction produces the narrowest processing line width, and the second angle is defined as the angle when the widest processing line width is produced. Here, the first angle may be approximately 0 degrees and the second angle may be approximately 90 degrees, but it is not limited to these two values.

[0048] In one embodiment, the controller 150 includes a table on which rotation angles (θ) corresponding to the machining line width are mapped by the beam adjustment element 122s, and can determine the rotation angle (θ) according to the set machining line width.

[0049] In another embodiment, the controller 150 receives input of the type of beam adjustment element 122s as an additional parameter, includes a table in which the rotation angle (θ) corresponding to the machining line width for each type of beam adjustment element 122s is mapped, and can determine the rotation angle (θ) according to the selected type of beam adjustment element 122s and the set machining line width. For example, Table 1 is an example of a table showing the matching of the rotation angle (θ) according to the processing line width when the beam adjustment element 122s is a one-dimensional diffractive optical element that splits the laser beam into multiple branched beams in a one-dimensional array. Here, the radius of curvature of each branch beam may be 5 micrometers, and the spacing between adjacent branch beams may be 0.13 degrees.

[0050] [Table 1]

[0051] In yet another embodiment, the controller 150 can determine the rotation angle (θ) based on the set processing line width and the length of the linear beam that has passed through the lens 122l. Here, the length of the linear beam may be the total length of the linear beam in the linear axis direction after passing through lens 122l, and the central intensity of the laser beam may be a specific standard (e.g., 1 / e 2 Alternatively, the distance between the two endpoints may be such that the intensity begins to decrease to approximately 50%, where e is the base of the natural logarithm. In detail, the rotation angle (θ) can be expressed using trigonometric functions as shown in Equation 1, based on the processing line width (D) and the total length (X) of the linear beam that passed through lens 122l.

[0052]

number

[0053] On the other hand, the method by which the controller 150 determines the rotation angle from the machining line width is not limited to the embodiment described above, and various modifications are possible, such as using an artificial intelligence model trained on training data.

[0054] This controller 150 determines a smaller rotation angle (θ) (a rotation angle close to approximately 0 degrees) when the machining line width is narrower, and a larger rotation angle (θ) (a rotation angle close to approximately 90 degrees) when the machining line width is wider. Furthermore, the linear alignment direction of the laser beam is changed according to this rotation angle, which in turn changes the processing line width. This change in the linear alignment direction of the laser beam changes the energy density of the laser beam irradiated onto the workpiece, thus changing the processing depth.

[0055] Figures 3 to 5 show the machining line width (w1, w2, w3, w4) and machining depth (t1, t2, t3, t4) according to the rotation angle (θ1, θ2, θ3, θ4) of the beam adjustment element 122s.

[0056] Referring to the figure, at the first rotation angle (θ1) which is 0 degrees, the narrowest first machining line width (D1) and the deepest first machining depth (t1) are obtained. Next, it can be confirmed that at a second rotation angle (θ2) greater than the first rotation angle (θ1), the second machining line width (D2) is wider than the first machining line width (D1) and the second machining depth (t2) is shallower than the first machining depth (t1); at a third rotation angle (θ3) greater than the second rotation angle (θ2), the third machining line width (D3) is wider than the second machining line width (D2) and the third machining depth (t3) is shallower than the second machining depth (t2); and at a fourth rotation angle (θ4) greater than the third rotation angle (θ3), the fourth machining line width (D4) is wider than the third machining line width (D3) and the fourth machining depth (t4) is shallower than the third machining depth (t3).

[0057] Referring again to Figure 2, in step 503, the controller 150 controls the beam adjustment element 122s to rotate by the determined rotation angle (θ). In step 504, the laser processing apparatus 100 irradiates the workpiece W with a laser beam whose linear arrangement direction has been changed by the rotation of the beam adjustment element 122s. As a result, the workpiece W is processed with a processing line width and processing depth corresponding to a laser beam whose linear arrangement direction is adjusted according to the rotation angle (θ).

[0058] According to one embodiment, the laser processing apparatus 100 can adjust the processing line width on the workpiece W by adjusting the linear arrangement direction of the laser beam irradiated onto the workpiece W without changing the lens 122l. In detail, simply by rotating the beam adjustment element 122s, the machining line width of the workpiece W can be controlled to be narrower or wider, which has the effect of allowing the workpiece W to be machined quickly and easily according to various machining specifications.

[0059] Figure 6 is a photograph showing the shape of the workpiece W after it has been processed by the rotation angle (θ) determined by the controller 150 when the beam adjustment element 122s in Figure 3 is a one-dimensional diffractive optical element.

[0060] In the case of the one-dimensional diffractive optical element in Figure 3, unlike the beam adjustment elements in Figures 4 and 5, the shape of the laser beam is not adjusted to a continuous linear shape. Therefore, if the beam adjustment element 122s is a one-dimensional diffractive optical element, the controller 150 must specially control the rotation angle so that the laser beam is irradiated onto the workpiece W in a nearly linear manner. When the laser beam Lb output from the laser oscillator 110 passes through the one-dimensional diffractive optical element, it is not a continuous linear beam, but is split into multiple branched beams arranged in a one-dimensional array. The divided branch beams are adjusted in size through a lens 122l having a predetermined focal length. The controller 150 can adjust the rotation angle within a predetermined range to obtain the same effect as when a nearly linear laser beam is irradiated onto the workpiece W, even if the laser beam is a collection of multiple branched beams arranged in a one-dimensional array.

[0061] In other words, the range of rotation angles when the beam adjustment element 122s is a one-dimensional diffractive optical element is smaller than the range of rotation angles of the beam adjustment element 122s that irradiates a linear beam (for example, a diffractive optical element for generating a linear beam). For example, if the beam adjustment element 122s is a one-dimensional diffractive optical element, the rotation angle may be selected within a range from 0 degrees, which is defined as the case where the parallel axis Lt and the reference axis As are parallel, to the range where the parallel axis Lt and the reference axis As are at an acute angle. In detail, the controller 150 can determine the rotation angle based on the minimum overlap angle of the branched beams when the beam adjustment element 122s is a one-dimensional diffractive optical element, which will be described later.

[0062] In this embodiment, when the beam adjustment element 122s is a one-dimensional diffractive optical element, the spacing between the branched beams changes according to the rotation angle (θ) of the beam adjustment element 122s. The controller 150 can select the rotation angle (θ) of the beam adjustment element 122s within a range of angles in which the gap between the branched beams disappears and the branched beams completely overlap, or angles in which the gap between the branched beams narrows and the overlap between the branched beams begins. In other words, if the rotation angle (θ) deviates from the specified range, the spacing between the branched beams incident on the workpiece W widens, resulting in the problem that the workpiece W cannot be machined uniformly within a predetermined machining line width.

[0063] Referring to Figure 6, if the beam adjustment element 122s is a one-dimensional diffractive optical element, you can see the actual processing results of the workpiece W from left to right, when the rotation angle (θ) is 0 degrees, 5 degrees, and 7 degrees. This allows us to confirm that the workpiece W has been uniformly machined according to a predetermined line width within a rotation angle (θ) range of 0 to 7 degrees. Furthermore, it can be confirmed that, when the magnification of the photographs is the same, and the rotation angle is 0 degrees and 5 degrees, the processed line width when the rotation angle is 5 degrees is even wider than the processed line width when the rotation angle is 0 degrees. When the rotation angle is 7 degrees, the magnification of the photograph is different from when the rotation angle is 0 degrees or 5 degrees; therefore, the size of the processed line width is not compared to when the rotation angle is 0 degrees or 5 degrees.

[0064] The following describes a specific method by which the controller 150 sets the rotation angle (θ) when the beam adjustment element 122s is a one-dimensional diffractive optical element.

[0065] Figure 7 is an explanatory diagram illustrating the operation of the controller 150 to set the rotation angle (θ) when the beam adjustment element 122s in Figure 3 is a one-dimensional diffractive optical element.

[0066] TIFF2026075620000004.tif64157

[0067]

number

[0068] Here, assuming that the branched beam that has passed through lens 122l is nearly circular, the radius of curvature (d0) of each branched beam reaching the workpiece W can be derived from the diameter (2d0) of each branched beam. The radius of curvature (d0) of an individual branch beam may be half the diameter of that individual branch beam. The diameter of this individual branched beam (2d0) is determined by the wavelength of the laser beam (λ), the focal length of the lens (F), the diameter of the laser beam incident on the lens (DD), and the quality factor of the laser beam (M). 2 It is determined by equation 3. Here, the quality factor of the laser beam is an indicator of how close the laser beam is to an ideal Gaussian beam.

[0069]

number

[0070] TIFF2026075620000007.tif12158

[0071]

number

[0072] Here, the diffraction angle (θ) of the branched beam. s The ) can be obtained using the diffraction grating equation, based on the diffraction order (m), the wavelength of the laser beam (λ), and the grating period (d) of the one-dimensional diffractive optical element, as shown in Equation 5.

[0073]

number

[0074] TIFF2026075620000010.tif63157

[0075]

number

[0076] In the above-described embodiment, since the beam adjustment element 122s is a one-dimensional diffractive optical element, even when the laser beam is divided into multiple branched beams, the controller 150 can maintain consistent processing quality and prevent processing defects by deriving a rotation angle (θ) for uniform laser processing within the processing line width.

[0077] On the other hand, according to another embodiment of the present invention, the controller 150 can adjust the size of the processed line width by adjusting the magnification by changing the focal length of the lens 121l, in addition to rotating the beam adjustment element 122s. Here, the controller 150 can adjust the focal position by adjusting the distance between the lens 121l and the workpiece W. Here, the workpiece W may be moved while the lens 121l is fixed, or the lens 121l may be moved while the workpiece W is fixed. Furthermore, since the laser processing device 100 can include at least one lens 121l, the controller 150 can adjust the overall focal length or magnification by changing the position between the lenses in the multi-lens array. For example, if the focal length is adjusted from a lens 121l with a focal length of 20mm to a lens 121l with a focal length of 40mm, the diameter of the branched beam that passes through lens 121l doubles, and the size of the processed line width also doubles.

[0078] According to the above embodiment, since the rate of change of the processing line width can be adjusted by changing the focal length of the lens 121l, the laser processing device 100 can precisely control the processing line width and can accommodate various processing designs, which has the effect of improving production efficiency.

[0079] Figure 8 shows a laser processing apparatus 100 according to another embodiment of the present invention. The laser processing apparatus according to the embodiment shown in Figure 8 is characterized in that, compared to the embodiment shown in Figure 1, the optical unit 120 further includes a beam limiting element 123. Since the other components are the same as those in the embodiment shown in Figure 1, redundant explanations will be omitted.

[0080] The beam limiting element 123 is positioned between the beam adjustment element 122s and the lens 122l. The beam limiting element 123 then blocks a portion of the laser beam Lc whose shape has been adjusted by the beam adjustment element 122s, thereby generating a laser beam Ld with a portion of it blocked. The beam limiting element 123 may be a slit or a aperture, but is not limited to these; any element that can block a portion of the laser beam can be used.

[0081] The controller 150 can control the beam limiting element 123 to adjust the laser beam blocking ratio of the beam limiting element 123 based on the rotation angle (θ) in order to process the workpiece W to a constant machining depth regardless of the rotation angle (θ) of the beam adjustment element 122s. In other words, the controller 150 can control the beam limiting element 123 in synchronization with the rotation angle.

[0082] In detail, the controller 150 can control the beam limiting element 123 so that the laser beam cutoff ratio increases as the rotation angle (θ) is smaller (closer to 0 degrees), and decreases as the rotation angle (θ) is larger (closer to 90 degrees). In other words, the controller 150 can process the workpiece with a uniform processing depth by increasing the laser beam blocking ratio as the set processing line width narrows and decreasing the laser beam blocking ratio as the set processing line width widens.

[0083] Figure 9 is an explanatory diagram illustrating a laser processing method using a laser processing apparatus 100 that includes a beam limiting element 123. Figure 9 shows the case where the beam adjustment element 122s is a one-dimensional diffractive optical element, but it is not limited to this, and this laser processing method can also be used when the beam adjustment element 122s is a linear beam generation diffractive optical element, a cylindrical lens, etc. Figure 9, similar to Figure 3, shows (a) a plan view of the rotating beam adjustment element 122s and beam limiting element 123, and (b) a cross-sectional view of the workpiece W. The following explanation will refer to Figures 3 and 9 together.

[0084] Referring again to Figure 3, at a second rotation angle (θ2) that is greater than the first rotation angle (θ1), the workpiece W is machined with a second machining line width (D2) that is wider than the first machining line width (D1), and with a second machining depth (t2) that is shallower than the first machining depth (t1). Although the output (power) and processing speed (speed) of the laser beam remain constant, changing the linear arrangement direction of the laser beam narrows the processing line width, and the energy density per unit area of ​​the laser beam transmitted to the narrowed processing line width increases.

[0085] Referring to Figure 9, the controller 150 can maintain a constant energy density per unit area transmitted to the workpiece W by adjusting the laser beam blocking ratio of the beam limiting element 123 in synchronization with the rotation angle (θ) of the beam adjustment element 122s. As a result, the laser processing device 100 can maintain a constant processing depth even when processing the workpiece W with various processing line widths. In detail, Figure 9 shows that the fourth machining depth (t4) is the same at the first rotation angle (θ1), the third rotation angle (θ3), and the fourth rotation angle (θ4), but the machining line widths at each rotation angle are different, as the first machining line width (D1), the third machining line width (D3), and the fourth machining line width (D4).

[0086] With respect to each step constituting the laser processing method according to the present invention, unless there is a description specifying an order or a description to the contrary, the above steps may be carried out in any order. The present invention is not necessarily limited to the order of steps described above. All use of examples or exemplary terms (e.g., etc.) in this invention is solely for illustrative purposes and does not limit the scope of the invention unless limited by the claims. Furthermore, those skilled in the art will understand that various modifications, combinations, and changes can be made to the claims or their equivalents, depending on the design conditions and factors.

[0087] Therefore, the concept of the present invention should not be limited to the embodiments described above, and it can be said that not only the scope of the appended claims, but also all scopes equivalent to or equivalently modified from those claims, fall within the scope of the concept of the present invention. [Explanation of symbols]

[0088] 100 ···Laser processing equipment 110 ···Laser oscillator 120 ···Optical Unit 121m...Mirror 122s... Beam adjustment element 122l...lens 123 ···Beam limiting element 130 ··· Processing Table 150 ···Controller

Claims

1. In a laser processing apparatus used for processing semiconductor devices, A laser oscillator that outputs a laser beam, At least one beam adjustment element that adjusts the shape of the laser beam output from the laser oscillator, A lens positioned between the beam adjustment element and the workpiece, which adjusts the size of the laser beam whose shape has been adjusted by the beam adjustment element and irradiates the workpiece with it, A controller that sets the machining line width formed on the workpiece, determines the rotation angle of the beam adjustment element according to the set machining line width, and controls the beam adjustment element to rotate with respect to a rotation axis parallel to the normal of the plane of the workpiece according to the determined rotation angle. Laser processing equipment, including...

2. The beam adjustment element is a one-dimensional diffractive optical element that divides the laser beam into a plurality of branched beams in a one-dimensional array. The laser processing apparatus according to claim 1, wherein the controller determines the rotation angle based on the radius of curvature of the branched beam that has passed through the lens and the distance between adjacent branched beams that have passed through the lens.

3. When a parallel axis (Lt) parallel to the direction in which the plurality of branched beams are arranged linearly and a reference axis (As) parallel to the machining direction that intersects the machining line width are defined, The laser processing apparatus according to claim 2, wherein the rotation angle is selected from 0 degrees, which is defined as the case when the parallel axis (Lt) and the reference axis (As) are parallel, to a range where the parallel axis (Lt) and the reference axis (As) are at an acute angle to each other.

4. The laser processing apparatus according to claim 1, wherein the beam adjustment element is a diffractive optical element for linear beam generation or a cylindrical lens that adjusts the laser beam into a linear beam.

5. When a parallel axis (Lt) parallel to the linear beam and a reference axis (As) parallel to the machining direction intersecting the machining line width are defined, The laser processing apparatus according to claim 4, wherein the rotation angle is selected from a range of 0 degrees, defined as the case where the parallel axis (Lt) and the reference axis (As) are parallel, to 90 degrees, defined as the case where the parallel axis (Lt) and the reference axis (As) are perpendicular.

6. Displaced between the beam adjusting element and the lens, The laser processing apparatus according to claim 1, further comprising a beam limiting element that blocks a portion of the laser beam whose shape has been adjusted by the beam adjustment element.

7. The laser processing apparatus according to claim 6, wherein the beam limiting element is a slit or an aperture.

8. The laser processing apparatus according to claim 6, wherein the controller determines the cutoff range of the laser beam based on the rotation angle.

9. The laser processing apparatus according to claim 1, wherein the lens is an objective lens.

10. The laser processing apparatus according to claim 9, wherein the controller adjusts the size of the processing line width by adjusting the magnification due to a change in the focal length of the lens.

11. In a laser processing method for processing a workpiece using a laser processing device used for processing semiconductor devices, The aforementioned laser processing apparatus A laser oscillator outputs a laser beam, The shape of the output laser beam is adjusted by the beam adjustment element. The size of the laser beam, whose shape has been adjusted by the lens, is adjusted and irradiated onto the workpiece. Controller The width of the processing line formed on the workpiece is set, The rotation angle of the beam adjustment element is determined according to the set processing line width. A laser processing method in which the beam adjustment element is controlled to rotate with respect to a rotation axis parallel to the normal of the plane of the workpiece, according to the rotation angle determined above.

12. The beam adjustment element is a one-dimensional diffractive optical element that divides the laser beam into a plurality of branched beams in a one-dimensional array. The laser processing method according to claim 11, wherein the controller determines the rotation angle based on the radius of curvature of the branched beam that has passed through the lens and the distance between adjacent branched beams that have passed through the lens.

13. When a parallel axis (Lt) parallel to the direction in which the plurality of branched beams are arranged linearly and a reference axis (As) parallel to the machining direction that intersects the machining line width are defined, The laser processing method according to claim 12, wherein the rotation angle is selected within a range from 0 degrees, which is defined as the case when the parallel axis (Lt) and the reference axis (As) are parallel, to the range when the parallel axis (Lt) and the reference axis (As) are at an acute angle.

14. The laser processing method according to claim 11, wherein the beam adjustment element is a diffractive optical element for linear beam generation or a cylindrical lens that adjusts the laser beam into a linear beam.

15. When a parallel axis (Lt) parallel to the linear beam and a reference axis (As) parallel to the machining direction intersecting the machining line width are defined, The laser processing method according to claim 14, wherein the rotation angle is selected from within a range of 0 degrees, defined as the case where the parallel axis (Lt) and the reference axis (As) are parallel, to 90 degrees, defined as the case where the parallel axis (Lt) and the reference axis (As) are perpendicular.

16. The laser processing method according to claim 11, wherein a beam limiting element is disposed between the beam adjusting element and the lens, and blocks a portion of the laser beam whose shape has been adjusted by the beam adjusting element.

17. The laser processing method according to claim 16, wherein the beam limiting element is a slit or an aperture.

18. The laser processing method according to claim 16, wherein the controller controls the beam limiting element in synchronization with the rotation angle.

19. The laser processing method according to claim 11, wherein the lens is an objective lens.

20. The laser processing method according to claim 19, wherein the controller adjusts the size of the processing line width by adjusting the magnification due to a change in the focal length of the lens.

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