Laser processing apparatus and laser processing method

Abstract

The invention provides a laser processing device, which is used for processing a semiconductor device, and comprises at least one laser oscillator for outputting a laser beam; at least one beam adjusting element for adjusting the shape of the laser beam output from the laser oscillator; the at least one lens is positioned between the light beam adjusting element and a processed object and is used for adjusting the size of the laser beam of which the shape is adjusted by the light beam adjusting element and irradiating the processed object; and a controller which sets a processing line width to be formed on the processed object, determines a rotation angle of the light beam adjusting element according to the set processing line width, and controls the light beam adjusting element to rotate with a rotation axis parallel to a normal line of a plane of the processed object as a reference according to the determined rotation angle.

Description

Technical Field

[0001] This disclosure relates to a laser processing apparatus and a laser processing method for processing semiconductor devices. Background Technology

[0002] In semiconductor device manufacturing, laser etching can be used to precisely form desired patterns on the workpiece. Furthermore, during semiconductor chip dicing or chip packaging, laser grooving can be performed on the workpiece to create precise grooves.

[0003] The laser processing device used for this type of laser processing needs to change the shape of the laser beam irradiating the workpiece according to the type of workpiece, the specifications and form of the processing shape, and the process method. Therefore, the type and size of the optical units in the laser processing device also need to be changed accordingly.

[0004] However, modifying optical units according to various processing specifications not only presents technical limitations but also leads to decreased production yield, reduced processing quality, increased defect rate, and cost issues. The structure of optical units is highly complex. If multiple components within an optical unit are replaced to meet various processing specifications, the optical aberrations generated by these components will result in decreased processing quality and defects, ultimately leading to reduced production yield. Summary of the Invention

[0005] The problem the invention aims to solve

[0006] This disclosure provides a laser processing apparatus and a laser processing method, which adjust the processing linewidth of the workpiece by rotating a beam adjustment element during semiconductor device processing. The technical problem to be solved in this embodiment is not limited to the technical problem described above; other technical problems can be derived from the following embodiments.

[0007] means for solving problems

[0008] According to one aspect of this disclosure, a laser processing apparatus is disclosed for processing a workpiece. The apparatus includes: at least one laser oscillator for outputting a laser beam; at least one beam adjustment element for adjusting the shape of the laser beam output from the laser oscillator; at least one lens located between the beam adjustment element and the workpiece, the at least one lens for adjusting the size of the laser beam after its shape has been adjusted by the beam adjustment element and irradiating the workpiece; and a controller. The controller is configured to: set a processing linewidth to be formed on the workpiece; determine a rotation angle based on the set processing linewidth; and control the beam adjustment element to rotate about a rotation axis parallel to the normal to the plane of the workpiece based on the determined rotation angle.

[0009] The beam adjustment element is a one-dimensional diffractive optical element that divides the laser beam into multiple branch beams in a one-dimensional array, and the controller is configured to determine the rotation angle based on the radius of curvature of the branch beams passing through the lens and the spacing between adjacent branch beams passing through the lens.

[0010] When defining a parallel axis Lt parallel to the direction of the linear arrangement of the plurality of branch beams and a reference axis As parallel to the processing direction intersecting the processing linewidth, the rotation angle is selected within the range of 0 degrees to the acute angle formed by the parallel axis Lt and the reference axis As, wherein 0 degrees is defined when the parallel axis Lt is parallel to the reference axis As.

[0011] The beam adjustment element is a linear beam generating diffractive optical element that adjusts the laser beam into a linear beam.

[0012] The beam adjustment element is a cylindrical lens that adjusts the laser beam into a linear beam.

[0013] When defining a parallel axis Lt parallel to the linear laser beam and a reference axis As parallel to the processing direction intersecting the processing linewidth, the rotation angle is selected within the range of 0 degrees to 90 degrees. Specifically, 0 degrees is defined when the parallel axis Lt is parallel to the reference axis As, and 90 degrees is defined when the parallel axis Lt is perpendicular to the reference axis As.

[0014] It also includes a beam limiting element, disposed between the beam adjusting element and the lens, for blocking a portion of the laser beam after its shape has been adjusted by the beam adjusting element.

[0015] The beam limiting element is a slit or an aperture.

[0016] The controller is configured to determine the beam blocking range based on the rotation angle.

[0017] The lens in question is an objective lens.

[0018] The controller is configured to adjust the magnification by changing the focal length of the lens, thereby adjusting the size of the processing linewidth.

[0019] According to another aspect of this disclosure, a laser processing method is disclosed, which uses a laser processing apparatus to process a workpiece, wherein the laser processing apparatus is configured to: output a laser beam from a laser oscillator; adjust the shape of the output laser beam through a beam adjustment element; adjust the size of the laser beam after shape adjustment through a lens and irradiate the workpiece; set the processing linewidth to be formed on the workpiece; determine a rotation angle according to the set processing linewidth; and control the beam adjustment element to rotate around a rotation axis parallel to the normal of the plane of the workpiece based on the determined rotation angle.

[0020] Invention Effects

[0021] According to the above-described technical solution of this disclosure, various processing techniques can be performed by adjusting the processing linewidth even without replacing the optical unit included in the laser processing device.

[0022] Specifically, even with a single optical unit, the linear alignment of the laser beam irradiating the workpiece can be adjusted simply by rotating the beam adjustment element, thus enabling the workpiece to be processed from a narrow range to a wide range.

[0023] Furthermore, even without replacing the optical unit, it can meet various processing specifications, thus helping to simplify and stabilize process conditions. Attached Figure Description

[0024] Figure 1 This is a diagram illustrating a laser processing apparatus according to an embodiment of the present invention.

[0025] Figure 2 It is used to illustrate the use Figure 1 A flowchart of a laser processing method using a laser processing device.

[0026] Figure 3 This is a schematic diagram illustrating a laser processing method when the beam adjustment element is a one-dimensional diffractive optical element that divides a laser beam into multiple branch beams in a one-dimensional array.

[0027] Figure 4 This is a schematic diagram illustrating a laser processing method when the beam adjustment element is a diffractive optical element for linear beam generation.

[0028] Figure 5 This is a schematic diagram illustrating a laser processing method when the beam adjustment element is a cylindrical lens.

[0029] Figure 6 It is filming Figure 3 When the beam adjustment element is a one-dimensional diffractive optical element, it is a picture of the state of the workpiece being processed according to the rotation angle determined by the controller.

[0030] Figure 7 It is used for explanation Figure 3 A schematic diagram of the operation of the controller setting the rotation angle when the beam adjustment element is a one-dimensional diffractive optical element.

[0031] Figure 8 This is a diagram illustrating a laser processing apparatus according to another embodiment of the present invention.

[0032] Figure 9 This is a schematic diagram illustrating a laser processing method using a laser processing apparatus that includes a beam-limiting element.

[0033] Explanation of reference numerals in the attached figures

[0034] 100: Laser processing equipment

[0035] 110: Laser Oscillator

[0036] 120: Optical Unit

[0037] 121m: Lens

[0038] 122s: Beam adjustment element

[0039] 122l: Lens

[0040] 123: Beam limiting element

[0041] 130: Processing table

[0042] 150: Controller Detailed Implementation

[0043] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings to enable those skilled in the art to readily implement them. However, the present invention can be implemented in various different forms and is not limited to the embodiments described herein. Furthermore, for the purpose of clearly describing the present invention, parts irrelevant to the description have been omitted from the drawings, and similar reference numerals have been assigned to similar parts throughout the specification.

[0044] In the following embodiments, the terms "first," "second," etc., are not restrictive, but are used to distinguish one constituent element from another.

[0045] In the following embodiments, unless the context clearly specifies otherwise, singular expressions include plural expressions.

[0046] In the following embodiments, terms such as include or have mean the presence of a feature or constituent element described in the specification, and do not preclude the additional possibility of more than one other feature or constituent element.

[0047] In the following embodiments, when referring to a membrane, region, constituent element, or other part being located "above" or "on top of" other parts, it includes not only the case where it is directly above other parts, but also the case where other membranes, regions, constituent elements, or other parts are interspersed in between.

[0048] For ease of explanation, the dimensions of the components in the accompanying drawings may be enlarged or reduced. For example, the dimensions and thicknesses of the components in the drawings are arbitrarily shown for ease of explanation, and therefore the present invention is not necessarily limited to the form shown in the drawings.

[0049] In the following embodiments, the x-axis, y-axis, and z-axis are not limited to three axes in an orthogonal coordinate system, but can be understood in a broader sense that includes this meaning. For example, the x-axis, y-axis, and z-axis can be orthogonal to each other, or they can refer to different directions that are not orthogonal to each other.

[0050] Where a particular embodiment can be implemented in different ways, a specific process sequence can also be performed in a manner different from the stated sequence. For example, two processes described consecutively can be performed substantially simultaneously, or they can be performed in the reverse order.

[0051] This disclosure will now be described in detail with reference to the accompanying drawings.

[0052] Figure 1 This is a diagram illustrating a laser processing apparatus 100 according to an embodiment of the present invention.

[0053] Reference 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.

[0054] The laser oscillator 110 may be equipped with a laser source that generates and outputs a laser beam with a specific wavelength. The type of laser beam output from the laser oscillator 110 is not particularly limited and can be appropriately selected according to the type of workpiece W or the processing method. For example, the laser beam output from the laser oscillator 110 may be any of the following: a solid-state laser beam including ruby ​​laser beams, Nd:YAG laser beams, Ti:sapphire laser beams, etc.; a liquid laser beam including dye laser beams, etc.; a gas laser beam including CO2 laser beams, He-Ne laser beams, Ar+ laser beams, excimer laser beams, etc.; or an ultraviolet (UV) laser beam. The laser oscillator 110 is connected to a controller 150. The characteristics of the laser beam output from the laser oscillator 110, such as the output power, intensity, period, and timing of the laser beam, can be controlled by signals generated by the controller 150.

[0055] The processing table 130 can be configured to face the direction of laser irradiation. The workpiece W is placed on the processing table 130. The processing table 130 can move in a set direction. For example, the processing table 130 can move along the X-axis, Y-axis, and Z-axis. The operation of the processing table 130, such as the moving speed, moving direction, and moving distance, can be controlled by the controller 150. The processing table 130 may include a rotating rotary table.

[0056] The optical unit 120 may include at least one mirror 121m, at least one beam adjustment element 122s, and at least one lens 122l. The optical unit 120 can direct the laser beam L output from the laser oscillator 110 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.

[0057] The mirror 121m can control the optical path of the laser beam La output by the laser oscillator 110. The number of mirrors 121m included in the laser processing apparatus 100 is not particularly limited, and the mirrors 121m can be galvano-mirrors. The mirrors 121m can be controlled by the controller 150.

[0058] A beam adjustment element 122s can be disposed between the mirror portion 121m and the lens 122l. The beam adjustment element 122s adjusts the shape of the laser beam Lb output from the laser oscillator 110 and having a set optical path. The beam adjustment element 122a forms a specific pattern by adjusting the shape and distribution of the laser beam. The beam adjustment element 122a can be a beam shaping element. The beam adjustment element 122a can be an element that changes the shape of the laser beam to be generally linear. Here, "generally linear" means, in addition to the case where the laser beam is linear, also includes the case where multiple branch beams of the laser beam are linearly arranged.

[0059] In one embodiment, the beam adjustment element 122a may be a one-dimensional diffractive optical element (1D DOE) that splits the laser beam into multiple branch beams in a one-dimensional array. In another embodiment, the beam adjustment element 122a may be a linear beam generating diffractive optical element that adjusts the laser beam into a linear beam, for example, a flat-top line beam diffractive optical element. In yet another embodiment, the beam adjustment element 122a may be a cylindrical lens that adjusts the laser beam into a linear beam. The cylindrical lens may include, but is not limited to, concave cylindrical lenses, convex cylindrical lenses, etc. The embodiments of the present invention are not limited to these; any element that adjusts the laser beam to a substantially linear form can be used as the beam adjustment element 122a.

[0060] The beam adjustment element 122a can rotate with reference to a rotation axis parallel to the normal (vertical axis) of the workpiece W plane. Specifically, the controller 150 can control the beam adjustment element 122a to rotate about an angle θ around the rotation axis. The rotation axis can be parallel to the normal of the workpiece plane. Alternatively, the rotation axis can be an axis parallel to the normal of the surface of the workpiece W and located at the center of the beam adjustment element 122a. The beam adjustment element 122a can change the linear alignment direction of the laser beam irradiating the workpiece W by rotating.

[0061] The controller 150 can control the various components of the laser processing apparatus 100. The control unit 150 can be implemented by at least one of application-specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DSPDs), programmable logic devices (PLDs), field-programmable gate arrays (FPGAs), controllers, microcontrollers, microprocessors, and electronic units for performing other functions.

[0062] According to an embodiment, the controller 150 can set the machining linewidth to be formed on the workpiece W, determine the rotation angle θ according to the set machining linewidth, and then control the beam adjustment element 122a to rotate at the determined rotation angle θ. Specific operation of the controller 150 will be described later.

[0063] Lens 122l can be disposed between the processing stage 130 and the lens portion 121m. Lens 122l focuses the laser beam Lc, whose shape has been adjusted by beam adjustment element 122a. Lens 122l adjusts the size of the laser beam Lc after its shape adjustment and illuminates the workpiece W after the size adjustment of the laser beam Lc. In one embodiment, lens 122l can be at least one objective lens. However, the lens is not limited to at least one objective lens, and can also include any lens capable of focusing a laser beam, such as a telecentric lens, an f-θ lens, or a focusing lens. Lens 122l is shown as one in the figures, but lens 122l can include multiple lenses. For example, lens 122l can be composed of multiple spherical lenses or planar lenses.

[0064] Figure 2 It is used to illustrate the use Figure 1 A flowchart of the laser processing method of the laser processing apparatus 100. Figure 3 This is a schematic diagram illustrating a laser processing method when the beam adjustment element 122s is a one-dimensional diffractive optical element that divides a laser beam into multiple branch beams in a one-dimensional array. Figure 4 This is a schematic diagram illustrating a laser processing method when the beam adjustment element 122s is a diffractive optical element for linear beam generation. Figure 5This is a schematic diagram illustrating a laser processing method when the beam adjustment element 122s is a cylindrical lens. Figures 3 to 5 Part (a) is a plan view showing the rotating beam adjustment element 122s. Figures 3 to 5 Part (b) is a cross-sectional view showing the workpiece W. Figure 3 Section (c) shows a plan view of the workpiece W.

[0065] Reference Figure 2 In step 501, the controller 150 sets the processing linewidth to be formed on the workpiece W. The processing linewidth can refer to the width of the laser processing area formed by the laser beam on the surface of the workpiece in a laser processing process. Specifically, as shown... Figures 3 to 5 As shown, the processing linewidth can refer to the width D1, D2, D3, and D4 of the processing area formed on the workpiece after processing, corresponding to the linear alignment direction of the laser beam changed by the rotation of the beam adjustment element, in the first direction DR1. The first direction DR1 can be a direction intersecting the second direction DR2 (where the laser beam irradiates the workpiece) on the cross-section of the workpiece, or it can be a direction intersecting the processing direction of the laser beam, i.e., the third direction DR3, on the plane of the workpiece.

[0066] The controller 150 can set the machining linewidth based on the machining shape of the workpiece W and the dimensions of the machining area. For example, when receiving input of the machining shape of the workpiece W and the dimensions of the machining area, the controller 150 can set the machining linewidth by mapping a table that has been pre-determined based on the machining shape of the workpiece W and the dimensions of the machining area. The machining linewidth can also be set as additional parameters, taking into account the material, thickness, and required machining depth of the workpiece W. However, it is not limited to this; the machining linewidth can also be set based on user input.

[0067] In step 502, the controller 150 determines the rotation angle θ of the beam adjustment element based on the processing linewidth. The rotation angle θ refers to the angle by which the beam adjustment element 122s, positioned opposite the surface of the workpiece W, rotates relative to the workpiece W. The rotation angle θ is defined based on the positional relationship between the laser beam to be irradiated onto the workpiece W and the workpiece W. (Refer to...) Figure 3 The rotation angle θ can be interpreted as the angle formed by the parallel axis Lt, which is parallel to the linear alignment direction of the branched beam, and the reference axis As, which is parallel to the machining direction (third direction, DR3) intersecting the machining linewidth, when the laser beam irradiating the workpiece W has the narrowest machining linewidth relative to the workpiece W. (Refer to...) Figure 4 and Figure 5The rotation angle θ can refer to the angle formed between the parallel axis Lt, which is parallel to the linear laser beam, and the reference axis As, which is parallel to the machining direction (third direction, DR3) intersecting the machining linewidth, when the laser beam irradiating the workpiece W forms the narrowest machining linewidth on the workpiece W. That is, in this specification, when the parallel axis Lt is parallel to the reference axis As, the rotation angle θ can be defined as 0 degrees (°), and when the parallel axis Lt is perpendicular to the reference axis As, the rotation angle θ can be defined as 90 degrees (°). According to one embodiment, the rotation angle θ can be selected between 0 degrees (°) defined when the parallel axis Lt is parallel to the reference axis As and 90 degrees (°) defined when the parallel axis Lt is perpendicular to the reference axis As.

[0068] On the other hand, the linear alignment direction of the laser beam irradiating the workpiece W can be changed by rotating the beam adjustment element 122s. The rotation angle θ can be defined as follows: the rotation angle when the linear alignment direction of the laser beam processes the narrowest processing linewidth is defined as the first angle; the rotation angle when processing the widest processing linewidth is defined as the second angle. The first angle can be approximately 0 degrees, and the second angle can be approximately 90 degrees, but is not limited to these.

[0069] In one embodiment, the controller 150 includes a table mapping a rotation angle θ corresponding to the machining linewidth according to the beam adjustment element 122s, and can determine the rotation angle θ according to the set machining linewidth.

[0070] In another embodiment, the controller 150 may further receive the type of the beam adjustment element 122s as an input parameter, and includes a table of rotation angles θ corresponding to the processing linewidth based on the type of the beam adjustment element 122s, and determines the rotation angle θ based on the selected type of the beam adjustment element 122s and the set processing linewidth. For example, Table 1 is an exemplary table showing the matching of rotation angles θ based on the processing linewidth when the beam adjustment element 122s is a one-dimensional diffractive optical element that splits a laser beam into multiple branch beams in a one-dimensional array. The radius of curvature of a single branch beam may be 5 micrometers, and the spacing between adjacent branch beams may be 0.13 degrees.

[0071] Table 1

[0072] In another embodiment, the controller 150 may determine the rotation angle θ based on the set processing linewidth and the length of the linear beam passing through the lens 122l. The length of the linear beam may be the total length of the linear laser beam passing through the lens 122l along the linear axis, or the distance between the two endpoints when the center intensity of the laser beam begins to drop below a specific reference (e.g., 1 / e² or approximately 50% of the intensity, where e is the base of the natural logarithm). Specifically, the rotation angle θ may be determined based on the processing linewidth D and the total length X of the linear beam passing through the lens 122l using trigonometric functions, as shown in Equation 1.

[0073]

Mathematical Formula 1

[0074] On the other hand, the way the controller 150 determines the rotation angle based on the processing linewidth is not limited to the above embodiment. Various variations can be adopted, such as using an artificial intelligence model that learns by learning data.

[0075] The narrower the machining linewidth, the smaller the rotation angle θ determined by the controller 150 (approximately 0 degrees); conversely, the wider the machining linewidth, the larger the rotation angle θ determined by the controller 150 (approximately 90 degrees). This is because the linear alignment of the laser beam changes according to the rotation angle, thereby altering the machining linewidth. The change in the linear alignment of the laser beam also changes the energy density of the laser beam irradiating the workpiece, resulting in a change in the machining depth.

[0076] Figures 3 to 5 The diagram shows the machining linewidths w1, w2, w3, w4 and machining depths t1, t2, t3, t4 based on the rotation angles θ1, θ2, θ3, θ4 of the beam adjustment element 122s.

[0077] Referring to the attached figures, when the first rotation angle θ1 is 0 degrees, it has the narrowest first machining linewidth D1 and the deepest first machining depth t1. Next, it can be confirmed that at a second rotation angle θ2 greater than the first rotation angle θ1, it has a second machining linewidth D2 wider than the first machining linewidth D1 and a second machining depth t2 shallower than the first machining depth t1; at a third rotation angle θ3 greater than the second rotation angle θ2, it has a third machining linewidth D3 wider than the second machining linewidth D2 and a third machining depth t3 shallower than the second machining depth t2; at a fourth rotation angle θ4 greater than the third rotation angle θ3, it has a fourth machining linewidth D4 wider than the third machining linewidth D3 and a fourth machining depth t4 shallower than the third machining depth t3.

[0078] Refer again Figure 2In step 503, the controller 150 controls the beam adjustment element 122s to rotate by a determined rotation angle θ. In step 504, the laser processing apparatus 100 irradiates the workpiece W with a laser beam whose linear alignment direction has been changed by the rotation of the beam adjustment element 122s. As a result, the workpiece W is processed to have a processing linewidth and processing depth corresponding to the laser beam whose linear alignment direction has been adjusted, according to the rotation angle θ.

[0079] According to the embodiment, even without replacing the lens 122l, the laser processing apparatus 100 can adjust the processing linewidth on the workpiece W by adjusting the linear alignment direction of the laser beam irradiating the workpiece W. Specifically, the processing linewidth of the workpiece W can be narrowed or widened simply by rotating the beam adjustment element 122s, thereby enabling the workpiece W to be processed quickly and easily according to different processing specifications.

[0080] Figure 6 It is filming Figure 3 When the beam adjustment element 122s is a one-dimensional diffractive optical element, it is a picture of the state of the workpiece being processed according to the rotation angle θ determined by the controller 150.

[0081] for Figure 3 One-dimensional diffractive optical elements, unlike Figure 4 and Figure 5 The beam adjustment element does not adjust the shape of the laser beam to be continuous and linear. Therefore, when the beam adjustment element 122s is a one-dimensional diffractive optical element, the controller 150 needs to specially control the rotation angle so that the laser beam irradiating the workpiece W is approximately linearly aligned. The laser beam Lb output from the laser oscillator 110 is split into multiple branch beams in a one-dimensional array after passing through the one-dimensional diffractive optical element, instead of forming a continuous linear laser beam. The split branch beams are adjusted in size by a lens 122l with a specified focal length. Even when the laser beam is a collection of multiple branch beams in a one-dimensional array, the controller 150 can adjust the rotation angle within a specified range to achieve an effect similar to a roughly linear laser beam irradiating the workpiece W.

[0082] That is, when the beam adjustment element 122s is a one-dimensional diffractive optical element, the range of the rotation angle is smaller than the range of the rotation angle of the beam adjustment element 122s used to irradiate a linear laser beam (e.g., a diffractive optical element for linear beam generation). For example, the rotation angle when the beam adjustment element 122s is a one-dimensional diffractive optical element can be selected from 0 degrees when the parallel axis Lt is parallel to the reference axis As to an acute angle formed between the parallel axis Lt and the reference axis As. Specifically, when the beam adjustment element 122s is a one-dimensional diffractive optical element, the controller 150 can determine the rotation angle based on the minimum overlap angle of the branched beams, which will be described later.

[0083] In this embodiment, when the beam adjustment element 122s is a one-dimensional diffractive optical element, the spacing between the branch beams changes with 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 the following angle range: the angle at which the spacing between the branch beams disappears and the branch beams completely overlap when the rotation of the beam adjustment element 122s causes the spacing between the branch beams to shrink and the overlap between the branch beams begins. That is, when the rotation angle θ exceeds this range, the spacing between the branch beams incident on the workpiece W increases, resulting in the problem that the workpiece W cannot be uniformly processed within the specified processing linewidth.

[0084] Reference Figure 6 It can be confirmed that when the beam adjustment element 122s is a one-dimensional diffractive optical element, the images show the actual processing results of the workpiece W at rotation angles θ from left to right of 0 degrees, 5 degrees, and 7 degrees. This confirms that when the rotation angle θ is within the range of 0 to 7 degrees, the workpiece W achieves uniform processing according to the specified linewidth. Furthermore, it can be confirmed that for the same rotation angles of 0 degrees and 5 degrees with the same image magnification, the processing linewidth at the 5-degree rotation angle is wider than that at the 0-degree rotation angle. Since the image magnification at a 7-degree rotation angle differs from that at 0 and 5 degrees, its processing linewidth is not compared with that at 0 and 5 degrees.

[0085] The following will explain the 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.

[0086] Figure 7 It is used for explanation Figure 3 A schematic diagram of the operation of the controller 150 in setting the rotation angle θ when the beam adjustment element 122s is a one-dimensional diffractive optical element.

[0087] Reference Figure 7The controller 150 can determine the rotation angle θ based on the minimum overlap angle of the branch beams, according to the set machining linewidth. The minimum overlap angle refers to the angle at which the branch beams begin to overlap. The minimum overlap angle can correspond to the maximum value of the rotation angle θ. This is because when the rotation angle θ exceeds the minimum overlap angle, the spacing between the branch beams increases, making it impossible to achieve uniform machining of the workpiece W. The minimum overlap angle can be based on the radius of curvature d0 of the branch beams transmitted through the lens 122l and the spacing between adjacent branch beams transmitted through the lens 122l. And that is determined. Specifically, the minimum overlap angle θ m Based on the radius of curvature d0 of the branched beam transmitted through lens 122l and the spacing between adjacent branched beams transmitted through lens 122l It is determined by mathematical formula 2.

[0088]

Mathematical Formula 2

[0089] Assuming the branched beams transmitted through lens 122l are approximately circular, the radius of curvature d0 of a single branched beam reaching the workpiece W can be derived from the diameter 2d0 of the single branched beam. The radius of curvature d0 of a single branched beam can be half the diameter of the single branched beam. The diameter 2d0 of the single branched beam can be determined based on the wavelength λ of the laser beam, the focal length F of the lens, the diameter DD of the laser beam incident on the lens, and the quality factor M of the laser beam. 2 As shown in Equation 3, the quality factor of the laser beam is an index representing how closely the laser beam approximates an ideal Gaussian beam.

[0090]

Mathematical Expression 3

[0091] Among them, the spacing between adjacent branch beams It can be based on the focal length F of the lens and the diffraction angle θ of the branched beam. s The trigonometric function values ​​are obtained as shown in mathematical formula 4.

[0092]

Mathematical Expression 4

[0093] The diffraction angle of the branched beam is 4θ. s It can be obtained using the diffraction grating equation, based on the diffraction order m, the wavelength λ of the laser beam, and the grating period d of the one-dimensional diffraction optical element, as shown in mathematical formula 5.

[0094]

Mathematical Expression 5

[0095] According to one embodiment, this assumes a one-dimensional diffractive optical element forming six branched beams, and that the one-dimensional diffractive optical element is combined with a lens with a focal length of 20 mm. The diffraction angle θ of the branched beams is... s Based on the provided diffraction order and laser beam wavelength, it is determined to be 0.13 using Equation 5. Using Equation 4, the spacing (Δx) of the branched beams transmitted through the lens is determined to be 46.77 micrometers. Using Equation 3, the radius of curvature d0 of the branched beams transmitted through the lens is determined to be 2.5 micrometers. By substituting the determined values ​​into Equation 2, Equation 6 calculates the minimum overlap angle of the branched beams to be 6.14 degrees. That is, the controller 150 can use 6.14 degrees as the maximum value of the rotation angle θ.

[0096]

Mathematical Expression 6

[0097] In the above embodiments, even if the beam adjustment element 122s is a one-dimensional diffractive optical element and the laser beam is split into multiple branch beams, the controller 150 can still derive the rotation angle θ required to achieve uniform laser processing within the processing linewidth, thereby maintaining the consistency of processing quality and preventing processing defects.

[0098] On the other hand, according to another embodiment of the present invention, in addition to the method of rotating the beam adjustment element 122s, the controller 150 can also adjust the magnification by changing the focal length of the lens 121l, thereby adjusting the size of the processing linewidth. Specifically, the controller 150 can adjust the position of the focal point by adjusting the distance between the lens 121l and the workpiece W. At this time, the workpiece W can be moved while the lens 121l is fixed, or the lens 121l can be moved while the workpiece W is fixed. Furthermore, the laser processing apparatus 100 may include at least one lens 121l; therefore, the controller 150 can adjust the overall focal length or magnification by changing the position between the lenses in a multi-lens arrangement. For example, when the lens 121l with a focal length of 20mm is adjusted to a lens 121l with a focal length of 40mm, the diameter of the branch beam passing through the lens 121l will increase by a factor of two, and the size of the processing linewidth will also increase by a factor of two.

[0099] According to the above embodiments, the rate of change of the processing linewidth can be adjusted by changing the focal length of the lens 121l. Therefore, the laser processing apparatus 100 can precisely control the processing linewidth and adapt to diverse processing designs, thereby improving production efficiency.

[0100] Figure 8 This is a diagram illustrating a laser processing apparatus 100 according to another embodiment of the present invention. According to... Figure 8 The laser processing apparatus of the embodiment and Figure 1Compared to the previous embodiment, the optical unit 120 further includes a beam limiting element 123. Apart from this, the remaining configuration is the same as... Figure 1 The embodiments are the same, so repeated descriptions are omitted.

[0101] A beam limiting element 123 is disposed between a beam adjusting element 122s and a lens 122l. The beam limiting element 123 blocks a portion of the laser beam Lc, after its shape has been adjusted by the beam adjusting element 122s, thereby generating a partially blocked laser beam Ld. The beam limiting element 123 can be a slit or an aperture, but is not limited to these; any element capable of blocking a portion of the laser beam can be used.

[0102] In order to ensure that the workpiece W can be processed to a constant processing depth even if the rotation angle θ of the beam adjustment element 122s changes, the controller 150 can control the beam limiting element 123 based on the rotation angle θ, thereby adjusting the laser beam blocking ratio of the beam limiting element 123. That is, the controller 150 can control the beam limiting element synchronously with the rotation angle.

[0103] Specifically, the controller 150 can control the beam limiting element 123 such that when the size of the rotation angle θ is smaller (closer to 0 degrees), the laser beam blocking ratio is increased, and when the size of the rotation angle θ is larger (closer to 90 degrees), the laser beam blocking ratio is decreased. In other words, the controller 150 is configured to increase the laser beam blocking ratio when the set processing linewidth is narrower and decrease the laser beam blocking ratio when the set processing linewidth is wider, thereby enabling the workpiece to be processed to a uniform processing depth.

[0104] Figure 9 This is a schematic diagram illustrating a laser processing method using a laser processing apparatus 100 including a beam limiting element 123. Figure 9 The example shown is a one-dimensional diffractive optical element 122s, but it is not limited to this. This laser processing method can also be used when the beam adjustment element 122s is a diffractive optical element for linear beam generation, a cylindrical lens, etc. Figure 9 and Figure 3 similar, Figure 9 Part (a) is a plan view showing the rotating beam adjustment element 122s and the beam limiting element 123. Figure 9 (b) is a cross-sectional view showing the workpiece W. The following will refer to... Figure 3 and Figure 9 Please provide an explanation.

[0105] Refer again Figure 3At a second rotation angle θ2 greater than the first rotation angle θ1, the workpiece W is processed into a second processing linewidth D2 that is wider than the first processing linewidth D1, and a second processing depth t2 that is shallower than the first processing depth t1. This is because, although the output power and processing speed of the laser beam remain constant, when the linear alignment direction of the laser beam changes, the processing linewidth narrows. Therefore, the energy density per unit area of ​​the laser beam transmitted to the narrower processing linewidth increases accordingly.

[0106] Reference Figure 9 The controller 150 synchronously adjusts the beam blocking ratio of the laser beam of the beam limiting element 123 with the rotation angle θ of the beam adjusting element 122s, thereby maintaining a constant energy density per unit area delivered to the workpiece W. Therefore, even when the workpiece W is processed to various linewidths, the laser processing apparatus 100 can maintain a constant processing depth. Specifically, in Figure 9 It can be confirmed that although the machining depth is the same (fourth machining depth t4) under the first rotation angle θ1, the third rotation angle θ3, and the fourth rotation angle θ4, the corresponding machining linewidths are the first machining linewidth D1, the third machining linewidth D3, and the fourth machining linewidth D4, respectively, which are different.

[0107] Where the order of steps constituting the method described in this invention is not explicitly stated or is not stated to the contrary, the steps may be performed in an appropriate order. This invention is not necessarily limited to the order in which the steps are described above. All examples or exemplary terms used in this invention (e.g., etc.) are for the purpose of describing the invention in detail only, and the scope of the invention is not limited by the examples or exemplary terms unless otherwise defined by the claims. Furthermore, those skilled in the art will understand that it can be constructed within the scope of the claims, which include various modifications, combinations, and variations, or their equivalents, depending on design conditions and factors.

[0108] Therefore, the concept of this invention should not be limited to the embodiments described above, and all scopes of the claims and their equivalents or variations should be included within the scope of the concept of this invention.

Claims

1. A laser processing apparatus for processing semiconductor devices, characterized in that, The laser processing apparatus includes: At least one laser oscillator for outputting a laser beam. At least one beam adjustment element is provided for adjusting the shape of the laser beam output from the laser oscillator. At least one lens is located between the beam adjustment element and the workpiece, the at least one lens being used to adjust the size of the laser beam, after its shape has been adjusted by the beam adjustment element, and to irradiate the workpiece. Controller; The controller is configured to: The machining linewidth to be formed on the workpiece is set, the rotation angle of the beam adjustment element is determined according to the set machining linewidth, and the beam adjustment element is controlled to rotate with a rotation axis parallel to the normal of the plane of the workpiece as a reference according to the determined rotation angle.

2. The laser processing apparatus according to claim 1, characterized in that, The beam adjustment element is a one-dimensional diffractive optical element that divides the laser beam into multiple branch beams in a one-dimensional array. At this time, the controller is configured as follows: The rotation angle is determined based on the radius of curvature of the branch beams passing through the lens and the spacing between adjacent branch beams passing through the lens.

3. The laser processing apparatus according to claim 2, characterized in that, When defining a parallel axis (Lt) parallel to the direction of the linear arrangement of the plurality of branch beams and a reference axis (As) parallel to the machining direction intersecting the machining linewidth, the rotation angle is selected from 0 degrees to the acute angle formed by the parallel axis (Lt) and the reference axis (As), wherein 0 degrees is defined when the parallel axis (Lt) is parallel to the reference axis (As).

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

5. The laser processing apparatus according to claim 4, characterized in that, When defining a parallel axis (Lt) parallel to the linear laser beam and a reference axis (As) parallel to the processing direction intersecting the processing linewidth, the rotation angle is selected within the range of 0 degrees to 90 degrees, wherein 0 degrees is defined when the parallel axis (Lt) is parallel to the reference axis (As), and 90 degrees is defined when the parallel axis (Lt) is perpendicular to the reference axis (As).

6. The laser processing apparatus according to claim 1, characterized in that, Also includes: A beam limiting element is disposed between the beam adjusting element and the lens and is used to block a portion of the laser beam after its shape has been adjusted by the beam adjusting element.

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

8. The laser processing apparatus according to claim 6, characterized in that, The controller is configured to: The beam blocking range is determined based on the rotation angle.

9. The laser processing apparatus according to claim 1, characterized in that, The lens is an objective lens.

10. The laser processing apparatus according to claim 9, characterized in that, The controller is configured to: The magnification is adjusted by changing the focal length of the lens, thereby regulating the dimensions of the processing linewidth.

11. A laser processing method, wherein a workpiece is processed using a laser processing apparatus for semiconductor device processing, characterized in that, This includes the following processes performed by the laser processing apparatus: A laser beam is output through a laser oscillator. The shape of the output laser beam is adjusted using beam adjustment elements. The size of the laser beam, after its shape has been adjusted, is then irradiated onto the workpiece using a lens. The controller is configured as follows: Set the machining linewidth to be formed on the workpiece. The rotation angle of the beam adjustment element is determined based on the set processing linewidth. The beam adjustment element is controlled to rotate relative to a rotation axis that is parallel to the normal of the plane of the workpiece, based on the determined rotation angle.

12. The method according to claim 11, characterized in that, The beam adjustment element is a one-dimensional diffractive optical element that divides the laser beam into multiple branch beams in a one-dimensional array. The controller is now configured as follows: The rotation angle is determined based on the radius of curvature of the branch beams passing through the lens and the spacing between adjacent branch beams passing through the lens.

13. The method according to claim 12, characterized in that, When defining a parallel axis (Lt) parallel to the direction of the linear arrangement of the plurality of branch beams and a reference axis (As) parallel to the machining direction intersecting the machining linewidth, the rotation angle is selected from 0 degrees to the acute angle formed by the parallel axis (Lt) and the reference axis (As), wherein 0 degrees is defined when the parallel axis (Lt) is parallel to the reference axis (As).

14. The method according to claim 11, characterized in that, The beam adjustment element is a linear beam generating diffractive optical element or cylindrical lens that adjusts the laser beam into a linear beam.

15. The method according to claim 14, characterized in that, When defining a parallel axis (Lt) parallel to the linear laser beam and a reference axis (As) parallel to the processing direction intersecting the processing linewidth, the rotation angle is selected within the range of 0 degrees to 90 degrees, wherein 0 degrees is defined when the parallel axis (Lt) is parallel to the reference axis (As), and 90 degrees is defined when the parallel axis (Lt) is perpendicular to the reference axis (As).

16. The method according to claim 11, characterized in that, A beam limiting element is disposed between the beam adjusting element and the lens and is used to block a portion of the laser beam after its shape has been adjusted by the beam adjusting element.

17. The method according to claim 16, characterized in that, The beam limiting element is a slit or an aperture.

18. The method according to claim 16, characterized in that, The controller controls the beam limiting element in sync with the rotation angle.

19. The method according to claim 11, characterized in that, The lens is an objective lens.

20. The method according to claim 19, characterized in that, The controller is configured to: The magnification is adjusted by changing the focal length of the lens, thereby regulating the dimensions of the processing linewidth.

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