Condenser lens unit and laser processing device

Abstract

To provide a condenser lens unit that can suppress thermal expansion of a condenser lens, and to provide a laser processing device.SOLUTION: A condenser lens unit 20 includes: a condenser lens 16 for condensing a laser beam L; and a condenser lens holder 28 for storing the condenser lens 16 in the internal space. The condenser lens holder 28 includes a cooling air supply port 28B from which air is supplied so as to flow along an inner peripheral surface of the condenser lens holder 28.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present invention relates to a condenser lens unit and a laser processing device, and more particularly to a technique for removing debris generated by laser processing. [Background technology]

[0002] Prior to blade dicing, which divides wafers carrying semiconductor devices, electronic components, and the like into individual chips, laser processing is performed in which the workpiece is irradiated with laser light to remove various films and metal patterns in advance.

[0003] This laser processing generates debris called processing waste. If the scattered debris adheres to the focusing lens, it can reduce the lens's transmittance, resulting in processing defects and damage to the focusing lens coating. In addition, the scattered debris can adhere to the wafer surface and remain after cleaning, potentially reducing yield.

[0004] To prevent debris from adhering to the condenser lens, air is blown onto the lens from a distance of about 10 mm, but this method has the problem of being difficult to sufficiently remove debris.

[0005] In response to this, Patent Documents 1 and 2 disclose techniques for suctioning debris to prevent it from scattering. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-136239 [Patent Document 2] International Publication No. 2003 / 095140 Summary of the Invention [Problem to be solved by the invention]

[0007] However, even with the techniques described in Patent Documents 1 and 2, there is a problem in that the scattering of debris is not sufficiently suppressed, and debris may adhere to the condenser lens.

[0008] The present invention has been made in view of the above circumstances, and has an object to provide a condenser lens unit and a laser processing apparatus that prevent debris from adhering to the condenser lens. [Means for solving the problem]

[0009] One aspect of a focusing lens unit for achieving the above object is a focusing lens unit including a focusing lens that focuses laser light, and a nozzle having a bottom with a laser passage port at the bottom through which the focused laser light passes, and a suction port that connects the internal space of the nozzle with the outside, located somewhere other than the bottom.

[0010] According to this aspect, since a laser passage opening is provided at the bottom of the closed-end nozzle, the probability that debris generated from the workpiece irradiated with laser light will scatter onto the condenser lens can be reduced. Also, since air inside the nozzle can be sucked through the suction opening, the air flow rate between the workpiece and the bottom of the nozzle can be increased, and debris can be appropriately sucked through the suction opening via the laser passage opening. Therefore, debris can be prevented from adhering to the condenser lens.

[0011] The condenser lens holder preferably includes a condenser lens holder that houses a condenser lens in an internal space, the internal space of the condenser lens holder communicating with the internal space of the nozzle, and the condenser lens holder is preferably provided with a supply port that supplies air for cooling the condenser lens. This allows the condenser lens to be cooled by air from the supply port. Furthermore, debris scattering toward the condenser lens can be suppressed, and debris can be prevented from adhering to the condenser lens.

[0012] It is preferable to provide a condenser lens protective plate disposed between the condenser lens and the laser passage port, through which the condensed laser light passes. Even if debris is scattered toward the condenser lens, the condenser lens protective plate can block the debris, thereby preventing the debris from adhering to the condenser lens.

[0013] One aspect of a laser processing device for achieving the above object is a laser processing device comprising: a laser light source that emits laser light; a focusing lens that focuses the laser light; a nozzle with a bottom having a laser passage port at the bottom through which the focused laser light passes, and a suction port that connects the internal space of the nozzle with the outside and is located somewhere other than the bottom; and an air suction device connected to the suction port outside the nozzle.

[0014] According to this aspect, since a laser passage opening is provided at the bottom of the nozzle with a bottom, the probability of debris scattering onto the condenser lens can be reduced. Also, by using an air suction device to suck the air inside through the suction opening, the air flow rate between the workpiece and the bottom of the nozzle can be increased, so debris can be properly sucked through the suction opening via the laser passage opening. Therefore, debris can be prevented from adhering to the condenser lens.

[0015] The condenser lens holder preferably houses a condenser lens in an internal space, the internal space of the condenser lens holder communicating with the internal space of the nozzle, the condenser lens holder being provided with a supply port for supplying air for cooling the condenser lens, and further comprising an air supply device connected to the supply port outside the condenser lens holder. The condenser lens can be cooled by supplying air from the supply port toward the condenser lens inside using the air supply device. Furthermore, debris scattering toward the condenser lens can be suppressed, and adhesion of debris to the condenser lens can be prevented.

[0016] It is preferable to provide a control device that controls the amount of air suctioned by the air suction device to be greater than the amount of air supplied by the air supply device. By making the amount of air suction greater than the amount of air supplied, debris can be appropriately sucked from the suction port through the laser passage port.

[0017] It is preferable to provide a condenser lens protective plate disposed between the condenser lens and the laser passage port, through which the condensed laser light passes. Even if debris is scattered toward the condenser lens, the condenser lens protective plate can block the debris, thereby preventing the debris from adhering to the condenser lens. [Effects of the Invention]

[0018] According to the present invention, it is possible to prevent debris from adhering to the condenser lens. [Brief explanation of the drawings]

[0019] [Figure 1] FIG. 1 is a block diagram showing the configuration of a laser processing device. [Figure 2] FIG. 2 is a perspective view of the condenser lens unit as viewed from above. [Figure 3] FIG. 3 is a perspective view of the condenser lens unit as viewed from the bottom side. [Figure 4] FIG. 4 is an exploded perspective view of the condenser lens unit as viewed from above. [Figure 5] FIG. 5 is an exploded perspective view of the condenser lens unit as viewed from the bottom side. [Figure 6] FIG. 6 is a diagram for explaining the operation of the laser processing device. [Figure 7] FIG. 7 is a bottom view of a condenser lens unit according to a modified example. DETAILED DESCRIPTION OF THE INVENTION

[0020] Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0021] <Laser processing equipment> 1 is a block diagram showing the configuration of a laser processing apparatus 10. The laser processing apparatus 10 is a wafer processing apparatus that performs laser processing along a planned dividing line on a wafer W, which is a workpiece having a laminated film including a metal film formed on its surface. The laser processing apparatus 10 includes a laser source 12, a safety shutter 14, a condenser lens 16, a dust collector 18, an air supply device 50, an air suction device 52, and a control device 54.

[0022] The laser source 12 is a laser light source including a laser oscillator (not shown) that emits laser light under the control of the control device 54. The laser source 12 emits laser light L oscillated by the laser oscillator.

[0023] The safety shutter 14 includes a light-blocking member capable of blocking the laser light. The safety shutter 14 has a blocking state in which the light-blocking member is inserted into the optical path of the laser light L emitted from the laser source 12 to block the laser light, and a passing state in which the light-blocking member is retracted from the optical path of the laser light L to allow the laser light L to pass. The safety shutter 14 is controlled by the control device 54 to be in either the blocking state or the passing state.

[0024] The condenser lens 16 includes a condensing optical system (not shown) that condenses the laser light. The condenser lens 16 condenses the laser light L that is emitted from the laser source 12 and passes through the safety shutter 14 onto the wafer W, which is the workpiece.

[0025] The dust collection unit 18 collects debris generated when the laser light L focused by the focusing lens 16 is irradiated onto the wafer W. The focusing lens 16 and the dust collection unit 18 form a focusing lens unit 20. An air supply device 50 and an air suction device 52 are connected to the dust collection unit 18.

[0026] The air supply device 50 is a blower such as a fan or a blower that supplies air at a predetermined supply rate. The air suction device 52 is a vacuum pump that sucks in air at a predetermined suction rate.

[0027] The control device 54 is realized by a general-purpose computer such as a personal computer or a microcomputer. The control device 54 includes a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), an input / output interface, etc. In the control device 54, various programs such as a control program stored in the ROM are loaded into the RAM, and the programs loaded into the RAM are executed by the CPU, thereby realizing the functions of each part in the laser processing device 10, and various arithmetic processing and control processing are performed via the input / output interface. The control device 54 controls the irradiation of the laser light L along the planned dividing line of the wafer W. The control device 54 also controls the supply of air by the air supply device 50 and the suction of air by the air suction device 52.

[0028] <Configuration of the condenser lens unit> Fig. 2 is a perspective view of the condenser lens unit 20 as seen from above, and Fig. 3 is a perspective view of the condenser lens unit 20 as seen from below. Also, Fig. 4 is an exploded perspective view of the condenser lens unit 20 as seen from above, and Fig. 5 is an exploded perspective view of the condenser lens unit 20 as seen from below.

[0029] The condenser lens unit 20 is mainly composed of a condenser lens 16, an adapter 22, an upper plate 24, a condenser lens holder 28, a condenser lens protective plate support member 32, a condenser lens protective plate 34, and a nozzle 36.

[0030] The adapter 22 is a member for optically connecting a laser generating device (not shown) including the laser source 12 and the safety shutter 14 (see FIG. 1) to the condenser lens unit 20. The adapter 22 has a circular through-hole 22A in the center.

[0031] The upper plate 24 is a plate-like member having a circular through-hole 24A in the center. The through-hole 22A and the through-hole 24A form an optical path for the laser light generated by the laser generating device to enter the condenser lens 16.

[0032] The condenser lens 16 has a cylindrical housing with a predetermined diameter. The condenser lens 16 has a cylindrical connecting portion 16A on its top surface that extends upward (in the Z direction). The connecting portion 16A of the condenser lens 16 fits into the through-hole 22A of the adapter 22 via the through-hole 24A of the upper plate 24.

[0033] Collecting lens holder 28 has a cylindrical through-hole 28A that penetrates the interior in the Z direction. Collecting lens 16 is housed in through-hole 28A of collecting lens holder 28. Upper plate 24, which is sandwiched between collecting lens 16 and adapter 22, is fixed to collecting lens holder 28 with four screws 26.

[0034] Two cooling air supply ports 28B are arranged along the Z direction on the side surface of condenser lens holder 28. When viewed from above (in the XY plane), the two cooling air supply ports 28B are arranged at positions where a tangent to the housing of condenser lens 16 intersects with the side surface of condenser lens holder 28, and are directed toward the tangent to the housing of condenser lens 16. Each of the two cooling air supply ports 28B communicates between a through hole 28A corresponding to the internal space of condenser lens holder 28 and the outside of condenser lens holder 28, and air is supplied toward condenser lens 16. A supply connector 30 having a through hole is connected to each of the two cooling air supply ports 28B. The number of cooling air supply ports 28B is not limited to two and can be determined as appropriate.

[0035] The condenser lens protection plate support member 32 supports the condenser lens protection plate 34. The condenser lens protection plate support member 32 has a mounting portion 32A, a recessed portion 32B, a through-hole 32C, and a light guiding portion 32D.

[0036] The mounting portion 32A is disposed on the upper surface of the condenser lens protection plate support member 32. The mounting portion 32A is a rectangular recess that corresponds to the shape of the condenser lens protection plate 34. The mounting portion 32A is surrounded by outer peripheries on three lateral sides, and has no outer periphery on one side. The mounting portion 32A has a cylindrical recess 32B on its bottom surface. In addition, the recess 32B has a through-hole 32C in the center that penetrates the interior in the Z direction.

[0037] Light guiding section 32D is disposed on the lower surface of condenser lens protection plate support member 32. Light guiding section 32D has a cylindrical shape and has through-hole 32C therein. Through-hole 32C has a tapered shape that narrows downward (as it gets further away from recess 32B).

[0038] The condenser lens protection plate 34 is a thin plate-like member made of glass. The condenser lens protection plate 34 is placed on the upper surface of the placement portion 32A of the condenser lens protection plate support member 32.

[0039] Nozzle 36 has a rectangular parallelepiped shape with a bottom (one example of a shape with a bottom). Nozzle 36 has a circular recess 36A in the center of its upper surface, which corresponds to the size of light guiding section 32D of condenser lens protective plate support member 32. Nozzle 36 has a flat nozzle bottom 36B on its lower surface. Nozzle bottom 36B has a rectangular shape with one side measuring 50 mm to 60 mm. A laser passage port 36C is arranged in the center of nozzle bottom 36B, connecting recess 36A and nozzle bottom 36B.

[0040] The light guide section 32D of the condenser lens protective plate support member 32 is housed in the recess 36A of the nozzle 36. The condenser lens holder 28, the condenser lens protective plate support member 32, and the nozzle 36 are each fixed by four screws 40 inserted from the nozzle bottom 36B of the nozzle 36.

[0041] With the condenser lens holder 28, the condenser lens protective plate support member 32, and the nozzle 36 fixed by the screws 40, a portion of the condenser lens protective plate 34 protrudes in a direction not surrounded by the outer periphery of the mounting portion 32A. By grasping the protruding portion of the condenser lens protective plate 34, the user can remove the condenser lens protective plate 34 from the condenser lens unit 20 and insert the condenser lens protective plate 34 into the condenser lens unit 20. This makes it easy to clean and replace the condenser lens protective plate 34.

[0042] Furthermore, when the condenser lens holder 28, the condenser lens protective plate support member 32, and the nozzle 36 are fixed with the screws 40, a gap exists between the through-hole 28A of the condenser lens holder 28 and the mounting portion 32A of the condenser lens protective plate support member 32. This allows the internal space of the condenser lens holder 28 to communicate with the internal space of the nozzle 36.

[0043] Two debris suction ports 36D are arranged along the Z direction on the side surface (an example of a portion other than the bottom) of the nozzle 36. Each of the two debris suction ports 36D connects the recess 36A, which corresponds to the space inside the nozzle 36, to the outside of the nozzle 36. A suction connector 38 having a through-hole is connected to each of the two debris suction ports 36D. The number of debris suction ports 36D is not limited to two and can be determined as appropriate.

[0044] <Function of laser processing equipment> Fig. 6 is a diagram for explaining the operation of the laser processing apparatus 10. Fig. 6 shows a cross section of the condenser lens unit 20. As shown in Fig. 6, an air supply device 50 is connected to the supply connector 30 of the condenser lens unit 20. In addition, an air suction device 52 is connected to the suction connector 38 of the condenser lens unit 20.

[0045] The control device 54 (not shown in FIG. 6) positions the nozzle bottom 36B of the nozzle 36 opposite the wafer W at a distance d. The control device 54 also controls the laser source 12 (not shown in FIG. 6) to emit laser light L and sets the safety shutter 14 to a passing state.

[0046] Laser light L emitted from laser source 12 and incident on condenser lens 16 is condensed by condenser lens 16. The laser light L condensed by condenser lens 16 passes through condenser lens protective plate 34. The laser light L that has passed through condenser lens protective plate 34 passes through through-hole 32C of condenser lens protective plate support member 32 and laser passage port 36C of nozzle 36, and is incident on wafer W.

[0047] The control device 54 moves the condenser lens unit 20 and the wafer W relative to each other, and irradiates the laser light L along the planned dividing line of the wafer W. When the laser light L is irradiated onto the processing point of the wafer W, debris D is generated. Here, by making the diameter of the laser passage opening 36C as small as possible, the probability that the scattered debris will scatter toward the condenser lens 16 side can be reduced.

[0048] The control device 54 also controls the air supply device 50 to supply air and the air suction device 52 to suck air.

[0049] When air is supplied by the air supply device 50, the supplied air is supplied to the through-hole 28A of the condenser lens holder 28 via the two cooling air supply ports 28B. The air supplied to the through-hole 28A is directed toward the condenser lens 16, circulating spirally around the condenser lens 16 and cooling it. After cooling the condenser lens 16, the air then reaches the condenser lens protective plate 34 and cools it. After cooling the condenser lens protective plate 34, the air passes through the gap between the through-hole 28A of the condenser lens holder 28 and the mounting portion 32A of the condenser lens protective plate support member 32, then passes through the through-hole 32C of the condenser lens protective plate support member 32 and the laser passage port 36C of the nozzle 36, and is guided to the processing point. Line A in FIG. 6 indicates the flow of air supplied by the air supply device 50. In this way, the air supplied by the air supply device 50 cools the condenser lens 16 evenly, and is supplied coaxially with the laser light L from the laser passage opening 36C.

[0050] When air is sucked in by the air suction device 52, the air is sucked in from the laser passage port 36C via the two debris suction ports 36D. The air supplied by the air supply device 50 and led to the processing point also merges with the air sucked in from the laser passage port 36C and is sucked into the air suction device 52 via the two debris suction ports 36D.

[0051] In addition, debris D generated by irradiating the wafer W with the laser light L is also sucked in through the laser passage port 36C and enters the recessed portion 36A of the nozzle 36. The debris D that has entered the recessed portion 36A is sucked into the air suction device 52 via the two debris suction ports 36D and collected. Line B shown in FIG. 6 indicates the flow of air sucked in by the air suction device 52.

[0052] Here, the control device 54 controls the amount of air suctioned by the air suction device 52 to a value greater than the amount of air supplied by the air supply device 50. This allows air to be sucked through the laser passage opening 36C, thereby suppressing the movement of debris D toward the wafer W.

[0053] Furthermore, by narrowing the distance d between the nozzle bottom 36B of the nozzle 36 and the wafer W as much as possible, it is possible to increase the flow rate of air between the nozzle bottom 36B and the wafer W. The distance d can be set to, for example, 1 mm to 2 mm.

[0054] As described above, the laser processing apparatus 10 can prevent debris from adhering to the condenser lens 16.

[0055] Furthermore, if the condenser lens 16 or the condenser lens protective plate 34 thermally expands when processing the wafer W, the height at which the laser light is focused and the shape of the laser light spot change, which may change the focused state and result in abnormal processing quality. According to the condenser lens unit 20 of the laser processing apparatus 10, the air supplied by the air supply device 50 circulates spirally around the condenser lens 16 and reaches the condenser lens protective plate 34, thereby allowing the condenser lens 16 and the condenser lens protective plate 34 to be appropriately cooled.

[0056] <Modification> In the above example, debris is sucked from the laser passage opening 36C located at the nozzle bottom 36B of the nozzle 36, but debris may also be sucked from a location other than the laser passage opening 36C.

[0057] Fig. 7 is a bottom view of the condenser lens unit 20 according to the modified example. As shown in Fig. 7, a circular suction groove 36E is arranged around a laser passage port 36C on a nozzle bottom 36B of the nozzle 36 of the condenser lens unit 20 according to the modified example.

[0058] The suction groove 36E communicates with the recess 36A of the nozzle 36. When air is sucked by the air suction device 52, debris is sucked together with the air through the laser passage port 36C and the suction groove 36E, and is sucked into the air suction device 52 via the recess 36A of the nozzle 36 and the two debris suction ports 36D, where it is collected.

[0059] <Other> The technical scope of the present invention is not limited to the scope described in the above embodiments. The configurations and the like in each embodiment can be appropriately combined with each other within the scope that does not deviate from the spirit of the present invention. [Explanation of symbols]

[0060] 10...Laser processing equipment 12...Laser source 14...Safety shutter 16...Condenser lens 16A...Connection 18...Dust collection section 20...Condenser lens unit 22...Adapter 22A…Through hole 24...Upper board 24A…Through hole 28...Condenser lens holder 28A…Through hole 28B...Cooling air supply port 30...Supply connector 32...Condenser lens protection plate support member 32A...Placement section 32B...recess 32C…Through hole 32D…Light guide part 34...Condenser lens protection plate 36...Nozzle 36A...recess 36B...Nozzle bottom 36C...Laser passage 36D...Debris suction port 36E…Suction groove 38...Suction connector 50...Air supply device 52...Air suction device 54...Control device A…Line B…line D...Debris L...laser light

Claims

1. a condenser lens that condenses the laser light; a condenser lens holder that houses the condenser lens in an internal space, The condenser lens unit includes a supply port through which air is supplied so as to circulate around the condenser lens along an inner peripheral surface of the condenser lens holder.

2. a laser light source that emits laser light; a condenser lens that condenses the laser light; a condenser lens holder that houses the condenser lens in an internal space and has a supply port disposed therein for supplying air to the internal space; an air supply device connected to the supply port outside the condenser lens holder, The air supply device supplies the air via the supply port so as to circulate around the condenser lens along the inner circumferential surface of the condenser lens holder.

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