Laser processing equipment

Abstract

To enable highly accurate alignment, we provide a laser processing apparatus equipped with an alignment mechanism. [Solution] The laser processing apparatus 100 of this embodiment includes a mask alignment mechanism 70 and a workpiece alignment mechanism 80, and the workpiece alignment mechanism 80 includes camera mechanisms 82, 84, 86, and 88. The cameras 82A, 84A, 86A, and 88A of the camera mechanisms 82, 84, 86, and 88 are supported by actuators 82B, 84B, 86B, and 88B, and the actuators 82B, 84B, 86B, and 88B are fixed to the lens barrel 30S.

Description

Technical Field

[0001] The present invention relates to a laser processing apparatus, and more particularly to an alignment mechanism for a mask and a workpiece (object to be processed).

Background Art

[0002] In a laser processing apparatus, a laser beam is scanned over a mask placed on a mask stage, and the light transmitted through the mask pattern is projected onto a workpiece (such as a substrate) placed on a processing stage by a projection optical system. By irradiating a laser beam with a high energy density, ablation processing is performed in which the surface portion melts and evaporates to form a processing pattern.

[0003] For example, in a laser processing apparatus provided with an illumination optical unit that forms a line-shaped laser beam, the line-shaped laser beam is scanned by moving the line beam forming unit (illumination optical unit) (see Patent Document 1).

[0004] In a laser processing apparatus, alignment mechanisms for reading alignment marks formed on a mask, a substrate, etc. are provided near a mask stage and a processing stage, respectively (see, for example, Patent Document 2). During ablation processing, the reference marks are imaged by the cameras of both alignment mechanisms to determine the relative positional relationship.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0006] In laser processing equipment that scans a linear laser beam, the linear laser beam is typically scanned repeatedly over each of the multiple processing areas formed on a workpiece, such as a substrate. As a result, the alignment mechanism for the workpiece is prone to misalignment of the camera that captures the alignment marks. This is because the relative position of the camera in the mask alignment mechanism, which is determined by capturing reference marks, and the camera in the workpiece alignment mechanism change, reducing the alignment accuracy.

[0007] Therefore, there is a need to provide a laser processing apparatus equipped with an alignment mechanism to enable highly accurate alignment. [Means for solving the problem]

[0008] A laser processing apparatus according to one aspect of the present invention includes a scanning mechanism for scanning a laser beam over a mask, a mask stage having a mask table on which the mask is placed and moving the mask table in a main scanning direction and a sub-scanning direction, a processing stage having a work table on which a workpiece is placed and moving the work table along a main scanning direction and a sub-scanning direction, a projection optical system for projecting the laser beam that has passed through the mask onto the workpiece, a mask alignment mechanism capable of detecting alignment marks provided on the mask, and a workpiece alignment mechanism capable of detecting alignment marks provided on the workpiece.

[0009] Various scanning mechanisms can be applied to the laser beam. For example, a laser processing apparatus includes a linear beam forming unit that forms a linear laser beam from a laser beam emitted from a light source, and a scanning mechanism that moves the linear beam forming unit along the main scanning direction.

[0010] As for the alignment method, it can be configured to enable alignment based on an off-axis method. For example, in a laser processing apparatus, the processing stage is located next to the work table and has a reference mark that moves with the work table, and the mask alignment mechanism and the work alignment mechanism can detect the reference mark separately.

[0011] In this invention, the workpiece alignment mechanism is attached to the lens barrel of the projection optical system. The workpiece alignment mechanism can be configured, for example, to include multiple workpiece cameras and multiple adjustment mechanisms that support each of the multiple workpiece cameras and are capable of controlling their attitudes. In this case, the multiple adjustment mechanisms are fixed to the lens barrel.

[0012] For example, multiple workpiece cameras can be configured to be positioned around a dust collection chamber located below the base of the lens barrel. Furthermore, multiple adjustment mechanisms can support each of the multiple workpiece cameras so that they are positioned below the base of the lens barrel.

[0013] In a workpiece alignment mechanism, the number of workpiece cameras is arbitrary. For example, a workpiece alignment mechanism can be configured to have at least two workpiece cameras aligned along the sub-scanning direction. Alternatively, a workpiece alignment mechanism can be configured to have four workpiece cameras aligned along the main scanning direction and the sub-scanning direction.

[0014] The mask alignment mechanism includes, for example, a guide rail extending along the sub-scanning direction, a plurality of mask mark detectors movable along the guide rail, and a movement mechanism for moving the guide rail in the main scanning direction. [Effects of the Invention]

[0015] The present invention provides a laser processing apparatus equipped with an alignment mechanism to enable highly accurate alignment. [Brief explanation of the drawing]

[0016] [Figure 1] This is a schematic configuration diagram of the laser processing apparatus according to the present embodiment. [Figure 2] This is a plan view of the laser processing apparatus as viewed from the side. [Figure 3] This is a diagram showing the arrangement of the workpiece alignment mechanism when viewed from the substrate side toward the projection optical system. [Figure 4] This is a schematic configuration diagram of the mask alignment mechanism.

Mode for Carrying Out the Invention

[0017] Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[0018] FIG. 1 is a schematic configuration diagram of the laser processing apparatus according to the present embodiment. FIG. 2 is a plan view of the laser processing apparatus as viewed from the side.

[0019] The laser processing apparatus 100 is a processing apparatus capable of forming a pattern on a substrate W by ablation processing, and includes a line beam forming unit 20, a projection optical system 30, a mask stage 40, and a processing stage 50. The line beam forming unit 20, the mask stage 40, and the processing stage 50 are mounted on the apparatus main body 15 (see FIG. 2) and are movable with respect to the apparatus main body 15. The mask M and the substrate W are respectively mounted on the mask table 42 of the mask stage 40 and the work table 52 of the processing stage 50. The substrate W as the workpiece is constituted by a resin substrate such as a printed substrate here.

[0020] The laser 10 installed independently beside the apparatus main body 15 oscillates a laser beam L with a high energy density. Here, an excimer laser that pulse-irradiates a KrF excimer laser beam having a wavelength of 248 nm is applied. The laser beam L oscillated from the laser 10 is guided to the line beam forming unit 20 via the beam transmission system 12. The laser 10 may be configured as a part of the laser processing apparatus 100 or as a separate apparatus.

[0021] The line beam forming unit 20 includes a line beam forming optical system including a lens array, a cylindrical lens, etc., and an optical system such as an angle switching mirror (none of which are shown). The lens array adjusts the intensity distribution of the incident laser beam L. The line beam forming optical system shapes the beam light beam of the incident laser beam L into a line-shaped laser beam LB.

[0022] The line beam forming unit 20 houses an optical system such as a line beam forming optical system in its casing 20K, and the casing 20K is supported by a scanning mechanism 60 (see FIG. 2). The scanning mechanism 60 can move the line beam forming unit 20 at a speed determined along the main scanning direction (X direction), and can relatively move the line-shaped laser beam LB in the main scanning direction (X direction) with respect to the mask M.

[0023] The mask stage 40 can move the mask table 42 that supports the mask M in the main scanning direction (X direction) and the sub-scanning direction (Y direction), and can also rotate it. A mask stage moving mechanism (not shown) drives the mask table 42 based on a signal output from a position detection encoder (not shown).

[0024] The processing stage 50 can fix the substrate W to the work table 52 by vacuum suction or the like, and can move and rotate the substrate W in the main scanning direction (X direction) and the sub-scanning direction (Y direction). A processing stage moving mechanism (not shown) drives the work table 52 based on a signal output from a position detection encoder (not shown).

[0025] The substrate W, which is a resin substrate, has a copper wiring layer formed on a base material such as epoxy resin, and an insulating layer formed on top of that. By irradiating the substrate W with high-energy-density excimer laser light from the laser 10, ablation occurs on the substrate W, and a pattern (hereinafter referred to as the processed pattern) WA is formed according to the mask pattern formed on the mask M. The processed pattern WA can be formed as through vias, non-through vias, or grooves (trenches) and cavities for wiring patterns.

[0026] The projection optical system 30, mask stage 40, processing stage 50, and scanning mechanism 60 are supported by a support structure 16, which is the frame structure of the main body 15 of the apparatus, and these are integrated. The support structure 16 is mounted on a base 17.

[0027] As the scanning mechanism 60 moves the line beam forming unit 20 in the scanning direction (X direction), a line-shaped laser beam LB, perpendicular to the scanning direction (X direction) and parallel to the sub-scanning direction (Y direction), moves relative to the mask M (mask stage 40), projection optical system 30, and substrate W (processing stage 50). As a result, the mask M and substrate W are scanned.

[0028] The size of the entire mask pattern formed on the mask M, i.e., the scanning area, is larger than the longitudinal width of the linear laser beam LB, depending on the processing area AR where the processing pattern WA is formed and the projection magnification of the projection optical system 30. Therefore, scanning along the main scanning direction (X direction) is repeatedly performed while switching the irradiation position of the linear laser beam LB using an angle-switching mirror. This forms the processing pattern WA for the entire processing area AR (see the symbol SL in Figure 1).

[0029] Each time a processing pattern WA is formed in the processing area, the processing stage 50 moves in steps along the scanning direction (X direction) and the sub-scanning direction (Y direction), performing ablation processing over the entire substrate W. After the processing pattern is formed on the substrate W by ablation processing, a conductor such as copper is filled in. Alternatively, a mask pattern for drawing the pattern over the entire substrate W may be formed on the mask M.

[0030] The laser processing apparatus 100 is equipped with a dust collector 90 that removes dust (hereinafter referred to as debris) that melts, evaporates, and scatters during ablation processing. The dust collector 90 has a cylindrical dust collection chamber 92 positioned between the projection optical system 30 and the processing stage 50, and is fixed to the base portion 30B of the lens barrel 30S of the projection optical system 30.

[0031] The laser processing apparatus 100 employs an off-axis alignment mechanism and is equipped with a mask alignment mechanism 70 for detecting alignment marks formed on the mask M and a workpiece alignment mechanism 80 for detecting alignment marks formed on the substrate W.

[0032] The mask alignment mechanism 70 and the workpiece alignment mechanism 80 detect alignment marks provided on the mask M and the substrate W before ablation processing. Based on the positions of the detected alignment marks, the positions (including rotation) of the mask M and the substrate W are aligned.

[0033] Furthermore, the mask alignment mechanism 70 and the workpiece alignment mechanism 80 detect a reference mark MR (see Figure 1) located next to the worktable 52. Based on the position of the detected reference mark MR, the mask alignment mechanism 70 and the workpiece alignment mechanism 80 determine their relative positions (align).

[0034] The controller 18 controls the angle switching mirror, scanning mechanism 60, mask stage moving mechanism, and processing stage moving mechanism of the line beam forming unit 20, and during ablation processing, controls the positioning of the mask M, the positioning of the substrate W, the movement of the line-shaped laser beam LB in the scanning direction (X direction), and the switching of the irradiation position along the sub-scanning direction (Y direction). In addition, the controller 18 controls the mask alignment mechanism 70 and the workpiece alignment mechanism 80 during alignment.

[0035] The mask alignment mechanism 70 is attached to the mask stage 40. On the other hand, the workpiece alignment mechanism 80 is attached to the barrel 30S of the projection optical system 30. Both alignment mechanisms will be described below.

[0036] Figure 3 shows the arrangement of the workpiece alignment mechanism 80 when viewed from the substrate W side of the projection optical system 30.

[0037] The workpiece alignment mechanism 80 comprises four camera mechanisms 82, 84, 86, and 88 arranged to surround the dust collection chamber 92. An adjustment mechanism actuator 82B can control the attitude of the camera 82A. The actuator 82B supports the camera 82A so that it is positioned below the lens barrel base portion 30B. The actuator 82B is fixed to the base portion 30B of the lens barrel 30S.

[0038] When adjusting the optical axis position of the camera during device startup, maintenance, etc., the actuator 82B drives and adjusts the attitude (position) of the camera 82A. After adjustment, the position of the camera 82A is fixed. A mechanism for moving the camera 82A in the main scanning direction (X direction) and the sub-scanning direction (Y direction) may also be provided. Alternatively, the adjustment mechanism may be provided as a manual guide mechanism.

[0039] Similarly, the other camera mechanisms 84, 86, and 88 each consist of cameras 84A, 86A, and 88A, and actuators 84B, 86B, and 88B, respectively, and their configuration is the same as that of camera 82A and actuator 82B of camera mechanism 82.

[0040] Camera mechanisms 82 and 84 are mounted on the lens barrel base 30B such that cameras 82A and 84A are aligned along the sub-scanning direction (Y direction). Camera mechanisms 86 and 88 are also mounted on the lens barrel base 30B such that cameras 86A and 88A are aligned along the sub-scanning direction (Y direction).

[0041] Furthermore, the camera mechanisms 82, 84, 86, and 88 are mounted on the lens barrel base 30B such that cameras 82A and 88A are aligned along the main scanning direction (X direction), and cameras 84A and 86A are aligned along the main scanning direction (X direction).

[0042] Thus, the camera central axes of camera mechanisms 82, 84, 86, and 88 are symmetrically positioned with respect to the optical axis C of the projection optical system 30, and cameras 82A, 84A, 86A, and 88A are aligned along the main scanning direction (X direction) and the sub-scanning direction (Y direction).

[0043] Since the camera mechanisms 82, 84, 86, and 88 are attached to the lens barrel 30S of the projection optical system 30, when performing alignment adjustment, the processing stage 50 is moved to image the alignment marks on the substrate W. Alternatively, the workpiece alignment mechanism 80 may be composed of only two camera mechanisms 82, 84 or camera mechanisms 86, 88 arranged along the sub-scanning direction (Y direction).

[0044] Figure 4 is a schematic diagram of the mask alignment mechanism 70.

[0045] As shown in Figure 4(A), the mask alignment mechanism 70 includes cameras 72 and 74, and a guide rail 76 that guides the movement of cameras 72 and 74 in the sub-scanning direction (Y direction). Cameras 72 and 74 are movable in the sub-scanning direction (Y direction) by the drive of actuators (not shown). The movement mechanism 78 moves the guide rail 76 along the main scanning direction (X direction).

[0046] When performing alignment adjustment, the guide rail 76 is moved in the main scanning direction (X direction) to match the positions of the alignment marks MA and MB formed on the mask M, and the cameras 72 and 74 are moved in the sub-scanning direction (Y direction). Then, before ablation processing after alignment adjustment, the guide rail 76 is moved in the reverse direction to move the cameras 72 and 74 out of the scanning range (irradiation range) of the line-shaped laser beam LB.

[0047] As shown in Figure 4(B), even when mask M is changed to mask M', the cameras 72 and 74 of the mask alignment mechanism 70 move to match the positions of the alignment marks MA' and MB' of mask M'. In the case of mask M', the guide rail 76 moves to a position outside the scanning range of the line-shaped laser beam LB of mask M'.

[0048] As described above, the laser processing apparatus 100 of this embodiment includes a mask alignment mechanism 70 and a workpiece alignment mechanism 80, and the workpiece alignment mechanism 80 includes camera mechanisms 82, 84, 86, and 88. The cameras 82A, 84A, 86A, and 88A of the camera mechanisms 82, 84, 86, and 88 are supported by actuators 82B, 84B, 86B, and 88B, and the actuators 82B, 84B, 86B, and 88B are fixed to the lens barrel 30S.

[0049] By attaching the workpiece alignment mechanism 80 to the barrel 30S of the projection optical system 30, the projection optical system 30, the mask stage 40, and the processing stage 50 are all supported by the support 16 and are integrated. Since the camera mechanisms 82, 84, 86, and 88 are fixed to the barrel 30S, even with ablation processing that involves movement of the line beam forming section 20 and the processing stage 50, the camera position of the workpiece alignment mechanism 80 is less likely to shift, and the relative positional relationship between the mask alignment mechanism 70 and the workpiece alignment mechanism 80 is maintained.

[0050] In particular, the laser processing apparatus 100 employs an off-axis method, and the mask alignment mechanism 70 and the workpiece alignment mechanism 80 each capture a reference mark MR. The positional relationship between the cameras 72 and 74 of the mask alignment mechanism 70 and the camera mechanisms 82, 84, 86, and 88 of the workpiece alignment mechanism 80, which is determined based on the imaging of this reference mark MR, does not change due to the movement of the apparatus that occurs during ablation processing, thus enabling the maintenance of highly accurate alignment.

[0051] A dust collection chamber 92 is provided below the projection optical system 30 so as to cover the processing area, i.e., the irradiation area of ​​the line-shaped laser beam LB. Therefore, the workpiece alignment mechanism 80 cannot be positioned near the center of the projection optical system 30 on the substrate W, corresponding to the optical axis C.

[0052] However, by attaching the four camera mechanisms 82, 84, 86, and 88 to the lens barrel 30S, the distance required to move the machining stage 50 for alignment can be reduced. Furthermore, since the camera mechanisms 82, 84, 86, and 88 are fixed to the lens barrel 30S, their relative positions do not change. This allows for maintaining alignment accuracy even when using multiple cameras.

[0053] Furthermore, since the camera mechanisms 82, 84, 86, and 88 are aligned along the main scanning direction (X direction) and the sub-scanning direction (Y direction), alignment marks provided on the substrate W can be efficiently imaged. In particular, since the camera mechanisms 82, 84 and camera mechanisms 86 and 88 are aligned along the sub-scanning direction, the positional relationship with the cameras 72 and 74 of the mask alignment mechanism 70, which are also aligned along the sub-scanning direction (Y direction), can be precisely determined. The number of cameras can be arbitrary; it may be one, two, or any other number.

[0054] In the mask alignment mechanism 70, the guide rail 76 moves along the main scanning direction (X direction). Therefore, by moving the guide rail 76, it is possible to suppress misalignment of the cameras 72 and 74 along the main scanning direction (X direction). In addition, the retraction position can be appropriately adjusted according to the scanning range of the line-shaped laser beam LB or the mask size, leading to improved throughput.

[0055] The mask alignment mechanism 70 and the workpiece alignment mechanism 80 may use equipment or devices (such as photodetectors) other than cameras that can detect alignment marks. [Explanation of Symbols]

[0056] 10 lasers 20 Line beam forming section 30 Projection optical system 40 Mask Stage 50 Processing Stages 60 Scanning mechanism 70. Mask alignment mechanism 80 Workpiece alignment mechanism 90 Dust collector 100 Laser Processing Equipment

Claims

1. A scanning mechanism that scans a laser beam across a mask, A mask stage having a mask table on which the mask is placed, and moving the mask table in the main scanning direction and the sub-scanning direction, A machining stage having a worktable on which a workpiece is placed, and moving the worktable along the main scanning direction and the sub-scanning direction, A projection optical system that projects the laser beam that has passed through the mask onto the workpiece, A mask alignment mechanism capable of detecting alignment marks provided on the mask, The workpiece alignment mechanism is equipped with a mechanism capable of detecting alignment marks provided on the workpiece, A laser processing apparatus characterized in that the workpiece alignment mechanism is attached to the lens barrel of the projection optical system.

2. The workpiece alignment mechanism comprises a plurality of workpiece cameras and a plurality of adjustment mechanisms that support each of the plurality of workpiece cameras and are capable of controlling their attitude. The laser processing apparatus according to claim 1, characterized in that the plurality of adjustment mechanisms are fixed to the lens barrel.

3. The laser processing apparatus according to claim 2, characterized in that the plurality of adjustment mechanisms each support the plurality of workpiece cameras such that the plurality of workpiece cameras are positioned below the base portion of the lens barrel.

4. The laser processing apparatus according to claim 1, characterized in that the workpiece alignment mechanism has at least two workpiece cameras arranged along the sub-scanning direction.

5. The laser processing apparatus according to claim 1, characterized in that the workpiece alignment mechanism has four workpiece cameras arranged along the main scanning direction and the sub-scanning direction.

6. The workpiece alignment mechanism has a plurality of workpiece cameras, The laser processing apparatus according to claim 1, characterized in that the plurality of workpiece cameras are arranged around a dust collection chamber located below the base portion of the lens barrel.

7. The aforementioned mask alignment mechanism, A guide rail extending along the aforementioned sub-scanning direction, Multiple mask mark detectors that can move along the aforementioned guide rail, A moving mechanism for moving the guide rail in the main scanning direction and The laser processing apparatus according to claim 1, characterized by comprising:

8. The processing stage is located next to the work table and has a reference mark that moves together with the work table. The laser processing apparatus according to any one of claims 1 to 7, characterized in that the mask alignment mechanism and the workpiece alignment mechanism separately detect the reference marks.

9. A line beam forming unit that forms a line-shaped laser beam from a laser beam emitted from a light source, A scanning mechanism that moves the line-shaped beam forming section along the main scanning direction, A laser processing apparatus according to any one of claims 1 to 7, characterized by comprising:

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