JP7758983B2 - 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 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 laser light is irradiated onto the workpiece to remove various films and metal patterns.

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

To prevent debris from adhering to the focusing lens, air is blown onto the focusing lens from a distance of about 10 mm. However, this method poses the problem of making it difficult to sufficiently remove debris.

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

JP 2014-136239 A WO 2003/095140

However, even with the technologies described in Patent Documents 1 and 2, there was a problem in that debris scattering 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 objective is a focusing lens unit comprising a focusing lens that focuses laser light, and a nozzle with a bottom, in which a laser passage port through which the focused laser light passes is located at the bottom, and in which a suction port that connects the internal space of the nozzle with the outside is located somewhere other than the bottom.

In this embodiment, a laser passage opening is provided at the bottom of the closed-end nozzle, reducing the likelihood that debris generated from the workpiece irradiated with laser light will scatter onto the focusing lens. Furthermore, air inside the nozzle can be sucked through the suction opening, increasing the air flow rate between the workpiece and the bottom of the nozzle, allowing debris to be properly sucked through the suction opening via the laser passage opening. This prevents debris from adhering to the focusing lens.

A condenser lens holder that houses a condenser lens in its internal space is provided, with 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. It also reduces debris that scatters onto the condenser lens, preventing debris from adhering to the condenser lens.

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

One aspect of a laser processing device that achieves the above objective 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 that has a laser passage port located 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 that is located somewhere other than the bottom, and an air suction device that is connected to the suction port outside the nozzle.

In this embodiment, a laser passage opening is provided at the bottom of the closed-end nozzle, reducing the chance of debris scattering onto the focusing lens. Furthermore, by using an air suction device to suck air from the inside through the suction opening, the air flow rate between the workpiece and the bottom of the nozzle can be increased, allowing debris to be properly sucked through the suction opening via the laser passage opening. This prevents debris from adhering to the focusing lens.

A condenser lens holder that houses a condenser lens in its internal space, the internal space of which communicates with the internal space of the nozzle, is provided. The condenser lens holder is preferably provided with a supply port for supplying air to cool the condenser lens, and further includes an air supply device 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 using the air supply device. It is also possible to suppress debris from scattering toward the condenser lens, preventing debris 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 through the suction port and the laser passage port.

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

This 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 device. FIG. 2 is a perspective view of the condenser lens unit as seen 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 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.

The laser source 12 is a laser light source that includes 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-blocking member capable of blocking laser light. The safety shutter 14 has two states: 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 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 passed 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 microcomputer. The control device 54 includes a CPU (Central Processing Unit), ROM (Read Only Memory), RAM (Random Access Memory), and an input/output interface. The control device 54 loads various programs, such as control programs, stored in the ROM into the RAM, and the functions of each part of the laser processing device 10 are realized by the CPU executing the programs loaded in the RAM, 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 division 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 seen from above, Fig. 3 is a perspective view of the condenser lens unit 20 as seen from below, 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.

The condenser lens unit 20 is primarily 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.

The adapter 22 is a component for optically connecting the focusing lens unit 20 to a laser generating device (not shown), which includes the laser source 12 and safety shutter 14 (see Figure 1). The adapter 22 has a circular through-hole 22A in its 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 generated by the laser generating device, allowing the laser light to enter the focusing lens 16.

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

The focusing lens holder 28 has a cylindrical through-hole 28A that penetrates the interior 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, sandwiched between the focusing lens 16 and the adapter 22, is fixed to the focusing lens holder 28 with four screws 26.

Two cooling air supply ports 28B are arranged along the Z direction on the side of the focusing lens holder 28. When viewed from above (in the XY plane), the two cooling air supply ports 28B are arranged at positions where the tangent to the housing of the focusing lens 16 intersects with the side of the focusing lens holder 28, and are directed toward the tangent to the housing of the focusing lens 16. The two cooling air supply ports 28B each connect a through-hole 28A, which corresponds to the internal space of the focusing lens holder 28, to the outside of the focusing lens holder 28, and supply air toward the focusing lens 16. A supply connector 30, which has 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-guiding portion 32D.

The mounting portion 32A is placed 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 edge on three lateral sides, and has no outer edge 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.

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 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 mounting portion 32A of the condenser lens protection plate support member 32.

The nozzle 36 has a rectangular parallelepiped shape with a bottom (an example of a shape with a bottom). The nozzle 36 has a circular recess 36A in the center of its 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 its bottom surface. The nozzle bottom 36B is rectangular with sides 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 recess 36A of the nozzle 36 houses the light guide section 32D of the condenser lens protection plate support member 32. The condenser lens holder 28, condenser lens protection plate support member 32, and nozzle 36 are each fixed in place by four screws 40 inserted from the nozzle bottom 36B of the nozzle 36.

When the condenser lens holder 28, condenser lens protective plate support member 32, and nozzle 36 are fixed with screws 40, a portion of the condenser 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 condenser lens protective plate 34, the user can remove the condenser lens protective plate 34 from the condenser lens unit 20 and insert it into the condenser lens unit 20. This makes it easy to clean and replace the condenser lens protective plate 34.

Furthermore, when the condenser lens holder 28, condenser lens protective plate support member 32, and nozzle 36 are fixed with 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 communication between the internal space of the condenser lens holder 28 and the internal space of 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). Each of the two debris suction ports 36D connects the recess 36A, which corresponds to the internal space of 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 laser processing device>
Figure 6 is a diagram for explaining the operation of the laser processing apparatus 10. Figure 6 shows a cross section of the condenser lens unit 20. As shown in Figure 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, causing the safety shutter 14 to pass through.

Laser light L emitted from the laser source 12 and incident on the condenser lens 16 is focused by the condenser lens 16. The laser light L focused by the condenser lens 16 passes through the condenser lens protective plate 34. The laser light L that has passed through the condenser lens protective plate 34 passes through the through-hole 32C in the condenser lens protective plate support member 32 and the laser passage opening 36C in the nozzle 36, and is incident on the wafer W.

The control device 54 moves the condenser lens unit 20 and the wafer W relative to one another, irradiating 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 of the scattered debris scattering toward the condenser 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 air.

When air is supplied by the air supply device 50, it 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 Figure 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 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 through the laser passage port 36C via the two debris suction ports 36D. The air supplied by the air supply device 50 and directed to the processing point merges with the air sucked in through 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 when the laser light L is irradiated onto the wafer W 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 in Figure 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 through the laser passage opening 36C, thereby suppressing the movement of debris D toward the wafer W.

Furthermore, 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 velocity 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.

Furthermore, 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. With the focusing lens unit 20 of the laser processing apparatus 10, air supplied by the air supply device 50 circulates spirally around the focusing lens 16 and reaches the focusing lens protective plate 34, thereby allowing the focusing lens 16 and the focusing lens protective plate 34 to be appropriately cooled.

<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 be sucked from a location other than the laser passage opening 36C.

Figure 7 is a bottom view of a modified focusing lens unit 20. 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 modified focusing lens unit 20.

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, debris is sucked in along with the air through the laser passage port 36C and the suction groove 36E, and then passes through the recess 36A of the nozzle 36 and the two debris suction ports 36D and is sucked into the air suction device 52, where it is collected.

<Others>
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.

DESCRIPTION OF SYMBOLS 10... Laser processing apparatus 12... Laser source 14... Safety shutter 16... Collecting lens 16A... Connection portion 18... Dust collection portion 20... Collecting lens unit 22... Adapter 22A... Through hole 24... Upper plate 24A... Through hole 28... Collecting lens holder 28A... Through hole 28B... Cooling air supply port 30... Supply connector 32... Collecting lens protective plate support member 32A... Placement portion 32B... Recess 32C... Through hole 32D... Light guiding portion 34... Collecting 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 (2)

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. 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.