JP7503233B2 - Condenser lens unit and laser processing device - Google Patents

Description

The present invention relates to a focusing lens unit and a laser processing device, and in particular to a technology for removing debris generated by laser processing.

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

This laser processing generates processing waste called debris. If the scattered debris adheres to the focusing lens, it can reduce the transmittance of the focusing lens, 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, which can reduce yields.

To prevent debris from adhering to the focusing lens, air is blown onto the focusing lens from a position about 10 mm away. However, there is a problem in that it is difficult to sufficiently remove the debris.

In response to this, Patent Documents 1 and 2 disclose technology that sucks up debris to prevent it from scattering.

JP 2014-136239 A International Publication No. 2003/095140

However, even with the technologies described in Patent Documents 1 and 2, there was a problem in that the scattering of debris was not sufficiently suppressed, and debris could adhere to the focusing lens.

The present invention was made in consideration of these circumstances, and aims to provide a focusing lens unit and laser processing device that prevents debris from adhering to the focusing lens.

One embodiment of a focusing lens unit for achieving the above object is a focusing lens unit that includes 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.

According to this aspect, a laser passage opening is provided at the bottom of the bottomed nozzle, which reduces the probability that debris generated from the workpiece irradiated with laser light will scatter onto the focusing lens. In addition, air inside the nozzle can be sucked in through the suction opening, which increases the air flow rate between the workpiece and the bottom of the nozzle, allowing debris to be properly sucked in through the suction opening via the laser passage opening. This makes it possible to prevent debris from adhering to the focusing lens.

The focusing lens holder preferably includes a focusing lens holder that houses a focusing lens in its internal space, the internal space of the focusing lens holder being connected to the internal space of the nozzle, and the focusing lens holder is preferably provided with a supply port that supplies air for cooling the focusing lens. This allows the focusing lens to be cooled by air from the supply port. It is also possible to suppress debris from scattering onto the focusing lens, and to prevent debris from adhering to the focusing lens.

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

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

According to this embodiment, a laser passage opening is provided at the bottom of the nozzle, which has a bottom, so the probability of debris scattering onto the focusing lens can be reduced. In addition, by sucking the air inside through the suction opening with an air suction device, the flow rate of the air between the workpiece and the bottom of the nozzle can be increased, so that debris can be appropriately sucked through the suction opening via the laser passage opening. This makes it possible to prevent debris from adhering to the focusing lens.

A condenser lens holder that houses a condenser lens in its internal space, the condenser lens holder has an internal space that communicates 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, and further includes an air supply device that is connected to the supply port on the outside of the condenser lens holder. The condenser lens can be cooled by supplying air from the supply port toward the internal condenser lens by the air supply device. In addition, debris that scatters onto the condenser lens can be suppressed, and debris can be prevented from adhering to the condenser lens.

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

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

The present invention makes it possible to prevent debris from adhering to the focusing lens.

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

A preferred embodiment of the present invention will now be described in detail with reference to the accompanying drawings.

<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 division line of 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 collection unit 18, an air supply device 50, an air suction device 52, and a control device 54.

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.

The safety shutter 14 includes a light-shielding member capable of blocking the laser light. The safety shutter 14 has a blocking state in which the light-shielding 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-shielding 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.

The focusing lens 16 includes a focusing optical system (not shown) that focuses the laser light. The focusing lens 16 focuses the laser light L emitted from the laser source 12 and passing through the safety shutter 14 onto the wafer W, which is the workpiece.

The dust collector 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 collector 18 form the focusing lens unit 20. An air supply device 50 and an air suction device 52 are connected to the dust collector 18.

The air supply device 50 is a blower such as a fan or 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.

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), and an input/output interface. In the control device 54, various programs such as a control program stored in the ROM are expanded into the RAM, and the programs expanded 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.

<Configuration of Condenser Lens Unit>
Fig. 2 is a perspective view of the condenser lens unit 20 as viewed from above, Fig. 3 is a perspective view of the condenser lens unit 20 as viewed from below, Fig. 4 is an exploded perspective view of the condenser lens unit 20 as viewed from above, and Fig. 5 is an exploded perspective view of the condenser lens unit 20 as viewed from below.

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

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 focusing lens unit 20. The adapter 22 has a circular through hole 22A in the center.

The upper plate 24 is a plate-like member having a circular through hole 24A in the center. The through holes 22A and 24A form the optical path of the laser light that is generated by the laser generating device and that enters the focusing lens 16.

The focusing lens 16 has a cylindrical housing with a predetermined diameter. The focusing lens 16 has a cylindrical connection part 16A on the top surface that extends upward (in the Z direction). The connection part 16A of the focusing lens 16 fits into the through hole 22A of the adapter 22 via the through hole 24A of the upper plate 24.

The focusing lens holder 28 has a cylindrical through-hole 28A that penetrates the inside in the Z direction. The focusing lens 16 is stored in the through-hole 28A of the focusing lens holder 28. The upper plate 24, which is sandwiched between the focusing lens 16 and the adapter 22, is fixed to the focusing lens holder 28 by four screws 26.

Two cooling air supply ports 28B are arranged along the Z direction on the side of the focusing lens holder 28. The two cooling air supply ports 28B are arranged toward the tangent of the housing of the focusing lens 16 at the position where the tangent of the housing of the focusing lens 16 intersects with the side of the focusing lens holder 28 when viewed from above (XY plane view). The two cooling air supply ports 28B each connect the through hole 28A corresponding to the internal space of the focusing lens holder 28 to the outside of the focusing lens holder 28, and air is supplied toward the focusing 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.

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 recess 32B, a through hole 32C, and a light guide portion 32D.

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 an outer periphery on three lateral sides, and has no outer periphery on one side. The mounting portion 32A has a cylindrical recess 32B on the bottom surface. In addition, the center of the recess 32B has a through hole 32C that penetrates the interior in the Z direction.

The light guide section 32D is disposed on the underside of the condenser lens protection plate support member 32. The light guide section 32D has a cylindrical shape and has a through hole 32C inside. The through hole 32C has a tapered shape that narrows downward (as it moves away from the recess 32B).

The focusing lens protection plate 34 is a thin plate-like member made of glass. The focusing lens protection plate 34 is placed on the upper surface of the mounting portion 32A of the focusing lens protection plate support member 32.

The nozzle 36 has a rectangular parallelepiped shape with a bottom (one example of a shape with a bottom). The nozzle 36 has a circular recess 36A in the center of the top surface that corresponds to the size of the light guide section 32D of the condenser lens protection plate support member 32. The nozzle 36 has a flat nozzle bottom 36B on the bottom surface. The nozzle bottom 36B is rectangular with one side measuring 50 mm to 60 mm. A laser passage port 36C is located in the center of the nozzle bottom 36B, connecting the recess 36A and the nozzle bottom 36B.

The light guide section 32D of the condenser lens protection plate support member 32 is housed in the recess 36A of the nozzle 36. The condenser lens holder 28, the condenser lens protection 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.

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

In addition, when the focusing lens holder 28, the focusing lens protection plate support member 32, and the nozzle 36 are fixed with the screws 40, a gap exists between the through hole 28A of the focusing lens holder 28 and the mounting portion 32A of the focusing lens protection plate support member 32. This allows the space inside the focusing lens holder 28 to communicate with the space inside the nozzle 36.

Two debris suction ports 36D are arranged along the Z direction on the side of the nozzle 36 (an example of a portion other than the bottom). The two debris suction ports 36D each connect 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.

<Function of the laser processing device>
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.

The control device 54 (not shown in FIG. 6) positions the nozzle bottom 36B of the nozzle 36 facing the wafer W at a distance d. The control device 54 also causes the laser source 12 (not shown in FIG. 6) to emit laser light L and causes the safety shutter 14 to pass through.

The laser light L incident on the focusing lens 16 from the laser source 12 is focused by the focusing lens 16. The laser light L focused by the focusing lens 16 passes through the focusing lens protective plate 34. The laser light L that passes through the focusing lens protective plate 34 passes through the through hole 32C of the focusing lens protective plate support member 32 and the laser passage port 36C of the nozzle 36, and is incident on the wafer W.

The control device 54 moves the focusing lens unit 20 and the wafer W relative to one another, 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 fly toward the focusing lens 16 can be reduced.

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

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 through the two cooling air supply ports 28B. The air supplied to the through hole 28A is supplied toward the condenser lens 16, circulates around the condenser lens 16 in a spiral shape, and cools the condenser lens 16. The air that has cooled the condenser lens 16 further reaches the condenser lens protection plate 34 and cools the condenser lens protection plate 34. The air that has cooled the condenser lens protection plate 34 passes through the gap between the through hole 28A of the condenser lens holder 28 and the mounting portion 32A of the condenser lens protection plate support member 32, then passes through the through hole 32C of the condenser lens protection plate support member 32 and the laser passage port 36C of the nozzle 36, and is led to the processing point. Line A shown 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 focusing lens 16 evenly and is supplied from the laser passage port 36C coaxially with the laser light L.

When air is sucked in by the air suction device 52, it 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 guided 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.

Furthermore, 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 recess 36A of the nozzle 36. The debris D that enters the recess 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.

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 in through the laser passage port 36C, thereby suppressing the movement of debris D toward the wafer W.

In addition, by narrowing the distance d between the nozzle bottom 36B of the nozzle 36 and the wafer W as much as possible, the air flow rate between the nozzle bottom 36B and the wafer W can be increased. The distance d can be set to, for example, 1 mm to 2 mm.

As described above, the laser processing device 10 can prevent debris from adhering to the focusing lens 16.

In addition, if the focusing lens 16 or the focusing 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 can change the focusing state and result in abnormal processing quality. According to the focusing lens unit 20 of the laser processing device 10, the air supplied by the air supply device 50 circulates in a spiral shape around the focusing lens 16 and reaches the focusing lens protective plate 34, thereby appropriately cooling the focusing lens 16 and the focusing lens protective plate 34.

<Modification>
In the above example, the debris is sucked through the laser passage opening 36C disposed in the nozzle bottom 36B of the nozzle 36, but the debris may be sucked through a port other than the laser passage opening 36C.

Figure 7 is a bottom view of the focusing lens unit 20 according to the modified example. As shown in Figure 7, a circular suction groove 36E is arranged around the laser passage opening 36C on the nozzle bottom 36B of the nozzle 36 of the focusing lens unit 20 according to the modified example.

The suction groove 36E is connected to the recess 36A of the nozzle 36. When air is sucked in by the air suction device 52, the debris is sucked in 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.

＜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 without departing from the spirit of the present invention.

10...laser processing apparatus 12...laser source 14...safety shutter 16...condensing lens 16A...connection portion 18...dust collection portion 20...condensing lens unit 22...adapter 22A...through hole 24...upper plate 24A...through hole 28...condensing lens holder 28A...through hole 28B...cooling air supply port 30...supply connector 32...condensing lens protective plate support member 32A...mounting portion 32B...recess 32C...through hole 32D...light guiding portion 34...condensing lens protective plate 36...nozzle 36A...recess 36B...nozzle bottom 36C...laser passage port 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 (7)

A condenser lens that condenses the laser light;
a nozzle having a bottom, a laser passage port through which the focused laser light passes, the nozzle having a suction port communicating an internal space of the nozzle with the outside, the suction port being disposed somewhere other than the bottom;
a condenser lens holder that houses the condenser lens in an internal space, the internal space of the condenser lens holder communicating with an internal space of the nozzle;
The condenser lens holder has a supply port through which air is supplied so as to flow along an inner peripheral surface of the condenser lens holder. a condenser lens protection plate disposed between the condenser lens and the laser passage port and through which the condensed laser light passes;
The condenser lens unit according to claim 1 , wherein the condenser lens protection plate is cooled by the air. a condenser lens protective plate support member disposed between the condenser lens holder and the nozzle and supporting the condenser lens protective plate;
The condenser lens unit according to claim 2 , wherein a gap through which air flows from the supply port to the suction port is provided between the condenser lens protection plate and the condenser lens protection plate support member. A laser light source that emits laser light;
a condenser lens for condensing the laser light;
a nozzle having a bottom, a laser passage port through which the focused laser light passes, the nozzle having a suction port communicating an internal space of the nozzle with the outside, the suction port being disposed somewhere other than the bottom;
an air suction device connected to the suction port outside the nozzle;
a condenser lens holder that houses the condenser lens in an internal space, the internal space of the condenser lens holder being in communication with an internal space of the nozzle, and the condenser lens holder having 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 through the supply port so as to flow along an inner peripheral surface of the condenser lens holder. The laser processing device according to claim 4, further comprising a control device that controls the amount of air suctioned by the air suction device to a value greater than the amount of air supplied by the air supply device. a condenser lens protection plate disposed between the condenser lens and the laser passage port and through which the condensed laser light passes;
The laser processing apparatus according to claim 4 , wherein the condenser lens protection plate is cooled by the air. a condenser lens protective plate support member disposed between the condenser lens holder and the nozzle and supporting the condenser lens protective plate;
7. The laser processing apparatus according to claim 6, wherein a gap through which air flows from the supply port to the suction port is provided between the condenser lens protection plate and the condenser lens protection plate support member.

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