JP2022031317A - Laser machining device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laser machining device that can increase an overlap rate of spots of two first laser beams or a spot of a second laser beam on a street.

SOLUTION: The laser machining device comprises: a laser beam emitting system that emits two first laser beams for edge-cutting processing and a second laser beam for punching processing; two collecting lenses disposed along a machining-feed direction; and a connection optical system that guides the two first laser beams to the collecting lens close to a forward path-direction and guides the second laser beam to the collecting lens close to a backward path-direction, when the laser optical system is relatively moved in the forward path-direction, and guides the two first laser beams to the collecting lens close to the backward path-direction and guides the second laser beam to the collecting lens close to the forward path-direction, when the laser optical system is relatively moved in the backward path-direction. The connection optical system divides either of the two first laser beams and the second laser beam into two and then guides the either to both of the two collecting lenses.

SELECTED DRAWING: Figure 37

COPYRIGHT: (C)2022,JPO&INPIT

Description

The present invention relates to a laser processing apparatus for laser processing a wafer.

In the field of semiconductor device manufacturing in recent years, a plurality of devices are formed by laminating a low-dielectric-constant insulator film (Low-k film) made of a vitreous material and a functional film forming a circuit on the surface of a substrate such as silicon. Wafers (semiconductor wafers) forming the above are known. In such a wafer, a plurality of devices are partitioned in a grid pattern by grid-like streets, and individual devices are manufactured by dividing the wafer along the streets.

As a method of dividing a wafer into a plurality of devices (chips), a method using a blade that rotates at high speed, a laser processing region is formed inside the wafer along a street, and the strength is lowered by forming this laser processing region. It is known how to apply an external force along the street. However, in the case of a wafer to which a Low-k film is applied, since the material of the Low-k film and the material of the wafer are different, it is difficult to cut the insulating film and the substrate at the same time by the blade by the former method. Also, with the latter method, it is difficult to divide into individual devices with good quality when a Low-k film is present on the street.

Therefore, in Patent Document 1, the edge cutting process (see Patent Document 2) for forming two edge cutting grooves (blocking grooves) along the street of the wafer and the hollow groove (dividing groove) between the two edge cutting grooves are described. ) Is formed, and a laser processing apparatus for performing the hollowing process is disclosed. This laser machining apparatus includes a first laser beam irradiation unit corresponding to edge cutting and a second laser beam irradiation unit corresponding to hollowing along a machining feed direction parallel to the street of the wafer (Patent Document). 1). Then, by relatively moving the first laser beam irradiation unit and the second laser beam irradiation unit relative to the wafer in one direction side in the machining feed direction (for example, the outward path direction side), two edges are cut along the same street. The Low-k film and the like are removed by simultaneously forming (parallel forming) the groove and the hollow groove.

Patent Document 3 describes a first groove machining for forming a first groove (fusing portion) along a street of a wafer, and a second groove machining for forming a second groove (fusing portion) at the bottom of the first groove. A laser processing apparatus for performing the above is disclosed. This laser machining apparatus includes a first laser beam head portion corresponding to the first groove machining and a second laser beam head section corresponding to the second groove machining along the machining feed direction parallel to the street of the wafer. ing. Then, by relatively moving the first laser beam head portion and the second laser beam head portion relative to the wafer in one direction side in the machining feed direction (for example, the outward path direction side), the first groove and the first groove along the same street. The second groove is formed at the same time.

In Patent Document 4, a pair of trenches (first groove of Article 2) parallel to each other along a dicing street by relatively moving a chuck holding a wafer and a laser optical system arranged at a position facing the wafer. And a laser processing apparatus for forming a wafer (second groove) which is a recess formed between a pair of trenches are disclosed. The laser optical system of Patent Document 4 is a laser that emits a laser beam (two first laser beams) corresponding to the processing of a pair of trenches and a laser beam (second laser beam) corresponding to the processing of a fellow. It includes a light emitting system and a condensing optical system that condenses each laser beam on a wafer. This condensing optical system uses a laser beam for trench processing and a laser beam for Farrow processing regardless of the processing feed direction (outward path direction, return path direction) of the laser optical system (condensing optical system) for the wafer. It is ahead of the others.

Japanese Unexamined Patent Publication No. 2009-182019 U.S. Pat. No. 5,922,224 Japanese Unexamined Patent Publication No. 58-143553 Japanese Unexamined Patent Publication No. 2016-20835

By the way, as described in Patent Document 1, when the two edge cutting grooves and the hollow groove are formed along the street, the two edge cutting grooves are formed in advance, and then the hollow groove is formed. It is necessary to form a groove. Therefore, in the laser processing apparatus of Patent Document 1, when the first laser beam irradiation unit and the second laser beam irradiation unit are relatively moved to one direction side (for example, the outward path direction side) in the processing feed direction with respect to the wafer. Only, two edge cutting grooves and a hollow groove can be formed at the same time along the same street. Therefore, in the laser processing apparatus of Patent Document 1, when each light beam irradiation unit is relatively moved to the other direction side (for example, the return path direction side) of the processing feed direction with respect to the wafer, two rows are along the same street. It is not possible to form the edge cutting groove and the hollow groove at the same time. As a result, the time (tact time) required for processing one wafer increases.

Therefore, in the laser processing apparatus of Patent Document 1, when each light beam irradiation unit is relatively moved to the other direction side in the processing feed direction with respect to the wafer, the second laser beam irradiation unit performs edge cutting processing and the first laser beam is used. It is conceivable to perform hollowing with the irradiation unit. However, since the optical system corresponding to edge cutting and the optical system corresponding to hollowing are different, when each light irradiation unit is compatible with both edge cutting and hollowing, the optical system of each light irradiation unit is supported. Becomes very complicated.

Even in the laser processing apparatus of Patent Document 3, when each laser beam head portion is relatively moved to the other direction side (for example, the return path direction side) of the processing feed direction with respect to the wafer, the first groove is along the same street. And the second groove cannot be formed at the same time.

Further, in the laser processing apparatus of Patent Document 4, the edge cutting process can be preceded by the hollowing process regardless of the processing feed direction (outward path direction, return path direction). Therefore, the lasers described in Patent Documents 1 to 3 are described above. The tact time can be reduced as compared with the processing equipment. However, in the laser processing apparatus described in Patent Document 4, edge cutting and hollowing are performed using a laser beam emitted from a common laser light source. At this time, suitable laser light conditions (wavelength, pulse width, repetition frequency, etc.) differ between the edge cutting process and the hollowing process. Therefore, if the laser beam conditions deviate from the conditions suitable for either edge cutting or hollowing, it is necessary to slow down the processing speed of one of them, and the processing speed of the other is also slowed down accordingly. There is a need to. Therefore, even in the laser processing apparatus described in Patent Document 4, there is a limit to the reduction of the tact time required for laser processing of the wafer.

The present invention has been made in view of such circumstances, and an object of the present invention is to provide a laser processing apparatus capable of reducing the tact time required for laser processing of a wafer.

The laser processing apparatus for achieving the object of the present invention is a laser processing apparatus in which a table holding a wafer and a laser optical system arranged at a position facing the table are relatively moved in a processing feed direction along a street of the wafer. By irradiating the wafer with laser light from the optical system, edge cutting is performed to form two first grooves parallel to each other along the street, and hollowing out to form a second groove between the first two grooves. In a laser processing device that performs processing for each street, the laser optical system emits a first laser light source that emits laser light under conditions corresponding to edge cutting, and a first laser light that emits laser light under conditions corresponding to hollowing. Two laser light sources, a first light forming element that forms two first laser lights from the laser light emitted from the first laser light source, and a second laser light formed from the laser light emitted from the second laser light source. Two second condensing lenses arranged in a row along the processing feed direction together with the first condensing lens with the second condensing element, the first condensing lens, and the first condensing lens sandwiched between them. Then, the two first laser beams emitted from the first light forming element are guided to the first condensing lens, and the second laser light emitted from the second light forming element is directed to the two second condensing lenses. A connection optical system that selectively guides the light is provided, and the connection optical system transmits the second laser beam to the first condenser lens when the laser optical system is relatively moved toward the outward path side in the processing feed direction with respect to the table. The second laser beam is focused on the first condensing light when it is guided to the second condensing lens located on the return path side in the processing feed direction and the laser optical system is relatively moved toward the return path direction with respect to the table. It leads to the second condenser lens located on the outward path side with respect to the lens.

According to this laser processing apparatus, it is possible to improve the processing speed of the wafer (reduce the tact time).

The laser processing apparatus for achieving the object of the present invention is a laser processing apparatus in which a table holding a wafer and a laser optical system arranged at a position facing the table are relatively moved in a processing feed direction along a street of the wafer. By irradiating the wafer with laser light from the optical system, edge cutting is performed to form two first grooves parallel to each other along the street, and hollowing out to form a second groove between the first two grooves. In a laser processing device that performs processing for each street, the laser optical system emits a first laser light source that emits laser light under conditions corresponding to edge cutting, and a first laser light that emits laser light under conditions corresponding to hollowing. Two laser light sources, a first light forming element that forms two first laser lights from the laser light emitted from the first laser light source, and a second laser light formed from the laser light emitted from the second laser light source. A second light forming element, two first condensing lenses arranged in a row along the processing feed direction, and a second condensing lens arranged between the two first condensing lenses. The two first laser beams emitted from the first light forming element are selectively guided to the two first condensing lenses, and the second laser light emitted from the second light forming element is directed to the second condensing lens. When the laser optical system is relatively moved toward the outward path side in the processing feed direction with respect to the table, the connection optical system is provided with a connection optical system that leads the two first laser beams to a second focus. When the laser optical system is guided to the first condensing lens located on the outward path side with respect to the lens and the laser optical system is relatively moved to the return path direction side in the processing feed direction with respect to the table, the two first laser beams are emitted. It leads to the first condenser lens located on the return path side with respect to the second condenser lens.

According to this laser processing apparatus, it is possible to improve the processing speed of the wafer (reduce the tact time).

In the laser processing apparatus according to another aspect of the present invention, the first moving mechanism for moving the first condenser lens relative to the table in the first vertical direction parallel to the table and perpendicular to the processing feed direction, and the table. A second moving mechanism for relatively moving the second condenser lens in the first vertical direction is provided. As a result, each machining point can be moved (traced) with an optimum motion locus regardless of the motion accuracy of the machining feed shaft during laser machining.

In the laser processing apparatus according to another aspect of the present invention, the first moving mechanism can move the first condenser lens relative to the table in the first vertical direction and the second vertical direction perpendicular to the table. There, the second moving mechanism can move the second condenser lens relative to the table in the first vertical direction and the second vertical direction. As a result, each machining point can be moved (traced) with an optimum motion locus regardless of the motion accuracy of the machining feed shaft during laser machining.

In the laser processing apparatus according to another aspect of the present invention, the first moving mechanism for moving the first condenser lens relative to the table in the first vertical direction parallel to the table and perpendicular to the processing feed direction, and the table. A second moving mechanism for integrally moving the two second condenser lenses in the first vertical direction is provided.

In the laser processing apparatus according to another aspect of the present invention, the first moving mechanism can move the first condenser lens relative to the table in the first vertical direction and the second vertical direction perpendicular to the table. There, the second moving mechanism can move the two second condenser lenses integrally with respect to the table in the first vertical direction and the second vertical direction.

In the laser processing apparatus according to another aspect of the present invention, the first condensing lens is integrally relative to the table in the first vertical direction parallel to the table and perpendicular to the processing feed direction. It includes a moving mechanism and a second moving mechanism that moves the second condenser lens relative to the table in the first vertical direction.

In the laser processing apparatus according to another aspect of the present invention, the first moving mechanism integrally combines two first condensing lenses with respect to the table in a first vertical direction and a second vertical direction perpendicular to the table. The second moving mechanism can move the second condenser lens relative to the table in the first vertical direction and the second vertical direction.

In the laser processing apparatus according to another aspect of the present invention, the first moving mechanism moves the table in the first vertical direction.

In the laser processing apparatus according to another aspect of the present invention, the second moving mechanism moves the table in the first vertical direction.

In the laser processing apparatus according to another aspect of the present invention, the first moving mechanism moves the table in the first vertical direction and the second vertical direction.

In the laser processing apparatus according to another aspect of the present invention, the second moving mechanism moves the table in the first vertical direction and the second vertical direction.

INDUSTRIAL APPLICABILITY According to the present invention, the tact time required for laser machining of a wafer can be reduced with a simple configuration.

It is a schematic diagram of the laser processing apparatus of 1st Embodiment. It is a top view of the wafer to be processed by a laser processing apparatus. It is explanatory drawing for demonstrating laser processing along an odd-numbered street. It is explanatory drawing for demonstrating the laser processing along the even-numbered street. It is explanatory drawing for demonstrating edge cutting processing and hollow processing by a laser optical system which is moved relative to the wafer in the outward direction direction. It is explanatory drawing for demonstrating edge cutting processing and hollow processing by a laser optical system which is moved relative to the wafer in the return direction side. It is a flowchart which showed the flow of the laser processing process for each street of the wafer by the laser processing apparatus of 1st Embodiment. It is explanatory drawing for demonstrating the space adjustment in the Y direction of 2 edge cutting grooves by the 1st rotation mechanism. It is explanatory drawing for demonstrating the space adjustment in the Y direction of 2 edge cutting grooves by the 1st rotation mechanism. It is explanatory drawing for demonstrating the width adjustment in the Y direction of the hollow groove by the 2nd rotation mechanism. It is explanatory drawing for demonstrating the width adjustment in the Y direction of the hollow groove by the 2nd rotation mechanism. It is a schematic diagram of the laser processing apparatus of 3rd Embodiment. It is explanatory drawing for demonstrating edge cutting processing and hollow processing by the laser optical system which is moved relative to the wafer in the outward direction direction in 4th Embodiment. It is explanatory drawing for demonstrating edge cutting processing and hollow processing by the laser optical system which is moved relative to the wafer in the return direction side with respect to the 4th Embodiment. It is explanatory drawing for demonstrating the specific example 1 of the connection switching element of 4th Embodiment. It is explanatory drawing for demonstrating the specific example 2 of the connection switching element of 4th Embodiment. It is explanatory drawing for demonstrating the specific example 3 of the connection switching element of 4th Embodiment. It is explanatory drawing for demonstrating edge cutting processing and hollow processing by the laser optical system which is moved relative to the wafer in the outward direction direction in 5th Embodiment. It is explanatory drawing for demonstrating edge cutting processing and hollow processing by the laser optical system 24 which is moved relative to the wafer in the return direction side with respect to the 5th Embodiment. It is explanatory drawing for demonstrating edge cutting processing and hollow processing by the laser optical system which is moved relative to the wafer in the outward direction direction in 6th Embodiment. It is explanatory drawing for demonstrating edge cutting processing and hollow processing by the laser optical system 24 which is moved relative to the wafer in the return direction side with respect to the 6th Embodiment. It is explanatory drawing for demonstrating the problem in the case where the intensity distribution of the 2nd laser beam becomes a Gaussian shape. It is explanatory drawing which showed an example of the ideal intensity distribution of the 2nd laser beam. It is explanatory drawing which showed an example of the actual intensity distribution of the 2nd laser beam. The reference numeral XXVA is an explanatory diagram showing an example of the intensity distribution (E) of the second laser beam in the Y direction, and the reference numeral XXVB is an explanatory diagram showing an example of the intensity distribution (E) of the second laser beam in the X direction. be. It is explanatory drawing which showed an example of the intensity distribution of the XY plane of the 2nd laser beam L2 of 7th Embodiment. It is the schematic of the laser optical system of the laser processing apparatus of 8th Embodiment. It is explanatory drawing for demonstrating the effect of the laser processing apparatus of 8th Embodiment. It is explanatory drawing for demonstrating edge cutting processing and hollow processing by the laser optical system of the laser processing apparatus of 9th Embodiment which is moved relative to the wafer in the outward direction direction. It is explanatory drawing for demonstrating edge cutting processing and hollow processing by the laser optical system of the laser processing apparatus of 9th Embodiment which is moved relative to the wafer in the return direction side. It is explanatory drawing for demonstrating the function of the connection optical system when the laser optical system is moved relative to the wafer in the outward direction direction by the relative movement mechanism. It is explanatory drawing for demonstrating the function of the connection optical system when the laser optical system is moved relative to the wafer in the return direction side by the relative movement mechanism. It is explanatory drawing for demonstrating edge cutting processing and hollow processing by the laser optical system which is moved relative to the wafer in the outward direction direction in the modification 1 of the 9th Embodiment. It is explanatory drawing for demonstrating edge cutting processing and hollow processing by the laser optical system which is moved relative to the wafer in the return direction side in the modification 1 of the 9th Embodiment. It is explanatory drawing for demonstrating edge cutting processing and hollow processing by the laser optical system which is moved relative to the wafer in the outward direction direction in the modification 2 of the 9th Embodiment. It is explanatory drawing for demonstrating edge cutting processing and hollow processing by the laser optical system which is moved relative to the wafer in the return direction side in the modification 2 of the 9th Embodiment. It is explanatory drawing for demonstrating edge cutting processing and hollow processing by the laser optical system of the laser processing apparatus of tenth embodiment. It is explanatory drawing for demonstrating edge cutting processing and hollow processing by the laser optical system of the laser processing apparatus of eleventh embodiment which is moved relative to the wafer in the outward direction direction. It is an enlarged view in the dotted line circle K1 in FIG. 38. It is explanatory drawing for demonstrating edge cutting processing and hollow processing by the laser optical system of the laser processing apparatus of eleventh embodiment which is moved relative to the wafer in the return direction side. It is an enlarged view in the dotted line circle K2 in FIG. 40. It is explanatory drawing for demonstrating the modification of 11th Embodiment. FIG. 43 is an explanatory diagram for explaining a modified example of the third embodiment.

[Overall configuration of the laser processing apparatus of the first embodiment]
FIG. 1 is a schematic view of the laser processing apparatus 10 of the first embodiment. As shown in FIG. 1, the laser processing apparatus 10 performs laser processing (ablation groove processing) on the wafer 12 as a pre-process before dividing the wafer 12 into a plurality of chips 14 (see FIG. 2). The XYZ directions in the figure are orthogonal to each other, of which the X direction and the Y direction are the horizontal direction, and the Z direction is the vertical direction. Here, the X direction corresponds to the processing feed direction of the present invention.

FIG. 2 is a plan view of the wafer 12 to be machined by the laser machining apparatus 10. As shown in FIG. 2, the wafer 12 is a laminated body in which a Low-k film and a functional film forming a circuit are laminated on the surface of a substrate such as silicon. The wafer 12 is divided into a plurality of regions by a plurality of streets C (planned division lines) arranged in a grid pattern. A device 16 constituting the chip 14 is provided in each of the partitioned areas.

The laser processing apparatus 10 performs laser processing (ablation groove processing) on the wafer 12 along the street C for each street C, as shown by the numbers (1) to (4) in parentheses in the figure. By doing so, the Low-k film or the like on the substrate is removed.

At this time, the laser processing apparatus 10 sets the relative movement direction when the laser optical system 24 described later is relatively moved in the X direction with respect to the wafer 12 in order to reduce the tact time required for laser processing of the wafer 12. Switch alternately every time.

For example, when laser processing is performed along the odd-numbered streets C shown by the numbers (1) and (3) in parentheses in the figure, the laser optical system 24 described later is set to one in the X direction with respect to the wafer 12. It is relatively moved to the outward direction side X1 (see FIG. 5) which is the direction side. Further, when laser processing is performed along the even-numbered streets C shown by the numbers (2) and (4) in parentheses in the drawing, the laser optical system 24 is placed on the other side in the X direction with respect to the wafer 12. It is relatively moved to the return direction side X2 (see FIG. 6).

FIG. 3 is an explanatory diagram for explaining laser machining along the odd-numbered street C. FIG. 4 is an explanatory diagram for explaining laser processing along the even-numbered street C.

As shown in FIGS. 3 and 4, in this embodiment, edge cutting and hollowing are simultaneously (parallel) executed as laser machining. The edge cutting process is a laser process performed by using two first laser beams L1 and has two edge cutting grooves 18 parallel to each other along the street C (corresponding to the first groove of Article 2 of the present invention). Laser processing to form an ablation groove). The hollowing process is a laser process performed by using one second laser beam L2 having a diameter larger than that of the two first laser beams L1, and the edge cutting groove 18 of the two strips formed by the edge cutting process. It is a laser machining that forms a hollow groove 19 (ablation groove corresponding to the second groove of the present invention) between them. Since the two edge cutting grooves 18 and the hollow grooves 19 which are ablation grooves are known techniques, the details thereof will be omitted (see Patent Document 1).

As described above, in the laser processing apparatus 10 of the present embodiment, the laser optical system 24 described later is moved relative to the wafer 12 to the outward direction side X1 (see FIG. 5) or to the return direction side X2 (see FIG. 6). In any case of relative movement, the edge cutting process is performed prior to the hollowing process.

Returning to FIG. 1, the laser processing apparatus 10 includes a table 20, a laser light source 22, a laser optical system 24, a microscope 26, a relative moving mechanism 28, and a control device 30.

The table 20 holds the wafer 12. Further, the table 20 is moved in the X direction, which is the machining feed direction parallel to the street C to be machined, by the relative movement mechanism 28 under the control of the control device 30, and the central axis of the table 20 parallel to the Z direction. It is rotated around (rotation axis).

The laser light source 22 constitutes the laser optical system of the present invention together with the laser optical system 24 described later. The laser light source 22 constantly emits laser light L under conditions (wavelength, pulse width, repetition frequency, etc.) suitable for both edge cutting and hollowing. The laser beam L emitted from the laser light source 22 is incident on the laser optical system 24.

The laser optical system 24 (also referred to as a laser unit) will be described in detail later, but the laser beam L from the laser light source 22 is branched into two, and two first laser beams L1 for edge cutting and a hollowing process are used. It forms one second laser beam L2. Then, the laser optical system 24 emits (irradiates) two first laser beams L1 from the first condenser lens 38 toward the street C. Further, the laser optical system 24 selectively emits (irradiates) the second laser beam L2 from the two second condenser lenses 40A and 40B toward the street C under the control of the control device 30.

Further, the laser optical system 24 is moved in the Y direction and the Z direction by the relative moving mechanism 28 under the control of the control device 30.

The microscope 26 is fixed to the laser optical system 24 and moves integrally with the laser optical system 24. The microscope 26 photographs an alignment reference (not shown) formed on the wafer 12 before edge cutting and hollowing on the wafer 12. Further, the microscope 26 photographs the two edge cutting grooves 18 and the hollow grooves 19 formed along the street C by the edge cutting process and the hollowing process. The captured image (image data) captured by the microscope 26 is output to the control device 30, and is displayed on a monitor (not shown) by the control device 30.

The relative movement mechanism 28 is composed of an XYZ actuator, a motor, etc. (not shown), and under the control of the control device 30, the relative movement mechanism 28 moves the table 20 in the X direction, rotates around the rotation axis, and causes the laser optical system 24 to move. The movement in the Y direction and the Z direction is performed. As a result, the relative movement mechanism 28 can move the laser optical system 24 relative to the table 20 and the wafer 12 held on the table 20. Instead of moving the table 20 in the X direction and the laser optical system 24 in the YZ direction, for example, the laser optical system 24 may be moved in the Z direction and the table 20 may be moved in the XY direction. As long as the laser optical system 24 can be moved relative to (wafer 12) in each direction (including rotation), the relative movement method is not particularly limited.

By driving the relative movement mechanism 28, the laser optical system 24 is aligned with the machining start position, which is one end of the street C to be machined, and the X direction along the street C [outward direction side X1 (FIG. 5). (See) or the relative movement of the laser optical system 24 on the return direction side X2 (see FIG. 6)] can be repeatedly executed. Further, by driving the relative movement mechanism 28 and rotating the table 20 by 90 °, each street C along the Y direction of the wafer 12 can be made parallel to the X direction which is the machining feed direction.

The control device 30 is composed of an arithmetic unit such as a personal computer, and includes an arithmetic circuit composed of various processors (Processor), a memory, and the like. Various processors include CPU (Central Processing Unit), GPU (Graphics Processing Unit), ASIC (Application Specific Integrated Circuit), and programmable logic devices [for example, SPLD (Simple Programmable Logic Devices), CPLD (Complex Programmable Logic Device), etc. And FPGA (Field Programmable Gate Arrays)] and the like. The various functions of the control device 30 may be realized by one processor, or may be realized by a plurality of processors of the same type or different types.

The control device 30 comprehensively controls the operations of the laser light source 22, the laser optical system 24, the microscope 26, and the relative movement mechanism 28.

[Laser optical system]
FIG. 5 is an explanatory diagram for explaining edge cutting and hollowing by the laser optical system 24 that is relatively moved to the outward direction side X1 with respect to the wafer 12. FIG. 6 is an explanatory diagram for explaining edge cutting and hollowing by the laser optical system 24 that is relatively moved to the return direction side X2 with respect to the wafer 12. Hereinafter, the odd-numbered street C, which is the processing target of the laser optical system 24 that is relatively moved to the outward direction side X1 with respect to the wafer 12, is appropriately referred to as an “outward path”, and the laser optical system that is relatively moved to the return direction side X2. The even-numbered street C, which is the object of processing of 24, is appropriately referred to as "return route".

As shown in FIGS. 5 and 6, the laser optical system 24 is connected to the safety shutter 100, the safety shutter drive mechanism 102, the branch element 31, the first light forming element 32, and the second light forming element 34. It includes a switching element 36, a first condensing lens 38, two second condensing lenses 40A and 40B, a first high-speed shutter 47A and a second high-speed shutter 47B, and a high-speed shutter drive mechanism 47C.

The safety shutter drive mechanism 102 is an actuator that inserts and removes the safety shutter 100 from the optical path between the laser light source 22 and the branch element 31 under the control of the control device 30. The safety shutter drive mechanism 102 emits two first laser beams L1 and second laser beams L2 from the laser optical system 24 by inserting the safety shutter 100 into the above-mentioned optical path except during laser processing. To stop. Further, the safety shutter drive mechanism 102 can emit two first laser beams L1 and a second laser beam L2 from the laser optical system 24 by retracting the safety shutter 100 from the above-mentioned optical path during laser processing. To.

For the branching element 31, for example, a half mirror or the like is used. The branching element 31 branches the laser light L emitted from the laser light source 22 into two, emits one of the two-branched laser light L to the first light forming element 32, and forms the other of the laser light L as the second light. It emits light to the element 34. The branching ratio of "two branches" in the present specification is not limited to 50:50 and can be changed as appropriate.

As the first light forming element 32, for example, a diffractive optical element (DOE) is used. The first light forming element 32 forms two first laser light L1 corresponding to the edge cutting process from the laser light L incident from the branching element 31, and the two first laser light L1 is the first condensing lens. It emits toward 38. As a result, the two first laser beams L1 are focused on the street C (outward and return paths) by the first condenser lens 38, and the two spots (condensing point or condensing point or) separated in the Y direction on the street C. (Also called a processing point) is formed. Although not shown, the optical path (including various optical elements provided on the optical path) of the two first laser beams L1 from the first optical forming element 32 to the first condenser lens 38 is the present invention. It constitutes a part of the connection optical system of.

As the second light forming element 34, for example, a diffractive optical element, a mask, or the like is used. The second light forming element 34 forms the second laser light L2 corresponding to the hollowing process from the laser light L incident from the branching element 31. The second laser beam L2 forms one rectangular spot (see FIGS. 10 and 11) on the wafer 12 between the two edge cutting grooves 18 in a rectangular shape (another shape such as a circular shape is also possible). The width of this spot in the Y direction is adjusted according to the distance between the two edge cutting grooves 18. Then, the second light forming element 34 emits the second laser beam L2 to the connection switching element 36.

The connection switching element 36 constitutes the connection optical system of the present invention together with the branch element 31 and the like described above. The connection switching element 36 includes, for example, a known optical switch or various optical elements (λ / 2 plate 52 and polarization beam splitter 54, half mirror 58 and shutters 62A, 62B, mirror 66A) shown in FIGS. 15 to 17 described later. , 66B, etc.) is used. The connection switching element 36 selectively guides the second laser beam L2 emitted from the second light forming element 34 to the second condenser lenses 40A and 40B under the control of the control device 30.

The first condenser lens 38 and the second condenser lenses 40A and 40B are arranged in a row along the X direction (processing feed direction). The first condensing lens 38 is arranged between the second condensing lens 40A and the second condensing lens 40B. The second condenser lens 40A is arranged on the return path side X2 with respect to the first condenser lens 38. The second condenser lens 40B is arranged on the outward direction side X1 with respect to the first condenser lens 38.

The first condensing lens 38 condenses the two first laser beams L1 incident from the first light forming element 32 on the street C (outward and return paths). The second condenser lens 40A concentrates the second laser beam L2 incident from the connection switching element 36 on the street C (outward route). The second condenser lens 40B concentrates the second laser beam L2 incident from the connection switching element 36 on the street C (return path).

The connection switching element 36 is provided from the second light forming element 34 when the relative moving mechanism 28 moves the laser optical system 24 relative to the wafer 12 in either the outward direction side X1 or the inbound direction side X2. The emitted second laser beam L2 is guided to a lens located on the other direction side of the outward path direction side X1 and the return path direction side X2 with respect to the first condenser lens 38 among the second condenser lenses 40A and 40B.

Specifically, as shown in FIG. 5, the connection switching element 36 is a second light forming element when the laser optical system 24 is relatively moved to the outward direction side X1 with respect to the wafer 12 by the relative moving mechanism 28. The second laser beam L2 emitted from 34 is guided to the second condenser lens 40A. As a result, the second laser beam L2 is condensed on the street C (outward route) by the second condenser lens 40A. As a result, the relative movement of the laser optical system 24 to the outward direction side X1 causes the edge cutting process to be executed in advance along the street C (outward path), so that two edge cutting grooves 18 are formed, and then hollowing out. By executing the processing, the hollow groove 19 is formed between the two edge cutting grooves 18.

Further, as shown in FIG. 6, when the laser optical system 24 is relatively moved to the return path side X2 with respect to the wafer 12 by the relative movement mechanism 28, the connection switching element 36 is emitted from the second light forming element 34. The generated second laser beam L2 is guided to the second condenser lens 40B. As a result, the second laser beam L2 is focused on the street C (return path) by the second condenser lens 40B. As a result, the relative movement of the laser optical system 24 to the return path side X2 causes the edge cutting process to be performed in advance along the street C (return path) to form two edge cutting grooves 18, which are subsequently hollowed out. By executing the processing, the hollow groove 19 is formed between the two edge cutting grooves 18.

The first high-speed shutter 47A has an optical path of laser light L between the branching element 31 and the first light forming element 32 (an optical path between the first light forming element 32 and the first condensing lens 38 is also possible). It is provided so that it can be inserted and removed freely. When the first high-speed shutter 47A is inserted into the optical path between the branch element 31 and the first light forming element 32, the first high-speed shutter 47A blocks the laser beam L incident on the first light forming element 32 from the branch element 31. , The emission of the two first laser beams L1 from the first condenser lens 38 is stopped.

The second high-speed shutter 47B is inserted into the optical path of the laser beam L between the branch element 31 and the second light forming element 34 (the optical path between the second light forming element 34 and the connection switching element 36 is also possible). It is provided freely. When the second high-speed shutter 47B is inserted into the optical path between the branch element 31 and the second light forming element 34, the second high-speed shutter 47B blocks the laser beam L incident on the second light forming element 34 from the branch element 31. , The emission of the second laser beam L2 from the second condenser lenses 40A and 40B is stopped.

The high-speed shutter drive mechanism 47C is an actuator that inserts and removes the first high-speed shutter 47A and the second high-speed shutter 47B for each of the above-mentioned optical paths under the control of the control device 30. The high-speed shutter drive mechanism 47C retracts the first high-speed shutter 47A from the optical path of the laser beam L during the edge cutting process, and inserts the first high-speed shutter 47A into the optical path of the laser beam L except during the edge cutting process. Further, the high-speed shutter drive mechanism 47C retracts the second high-speed shutter 47B from the optical path of the laser beam L during the hollowing process, and inserts the second high-speed shutter 47B into the optical path of the laser beam L except during the hollowing process.

FIG. 7 is a flowchart showing a flow of laser machining processing (control method of the laser machining device 10) for each street C of the wafer 12 by the laser machining device 10 of the first embodiment having the above configuration. In the initial state, it is assumed that the first high-speed shutter 47A, the second high-speed shutter 47B, and the safety shutter 100 are each inserted on the optical path of the laser beam L. Further, it is assumed that the emission of the laser beam L from the laser light source 22 is started at the start of the laser processing apparatus 10.

As shown in FIG. 7, when the wafer 12 to be laser-processed is held on the table 20, the control device 30 first drives the safety shutter drive mechanism 102 to retract the safety shutter 100 from the optical path of the laser beam L. (Step S0). As a result, the laser optical system 24 is in a state where the two first laser beams L1 and the second laser beam L2 can be emitted. At this point, since the first high-speed shutter 47A and the second high-speed shutter 47B are respectively inserted in the optical path of the laser beam L, the two first laser beams L1 and the second laser beam from the laser optical system 24 are inserted. L2 is not emitted.

Next, the control device 30 drives the relative movement mechanism 28 to move the microscope 26 relative to the wafer 12 to a position where the alignment reference (not shown) of the wafer 12 can be photographed, and then the alignment reference by the microscope 26. To execute the shooting of. Then, the control device 30 performs alignment detection for detecting the position of each street C in the wafer 12 based on the image taken by the alignment reference taken by the microscope 26. Next, the control device 30 drives the relative movement mechanism 28 to align the optical axis of the first condenser lens 38 of the laser optical system 24 with the processing start position of the first street C (outward path). (Step S1).

Further, the control device 30 drives the connection switching element 36 to switch the lens that emits the second laser beam L2 to the second condenser lens 40A (step S2). The order of steps S0 to S3 may be changed as appropriate, or these processes may be executed in parallel.

When step S2 is completed, the control device 30 drives the high-speed shutter drive mechanism 47C to retract the first high-speed shutter 47A from the optical path of the laser beam L (step S3). As a result, two first laser beams L1 are emitted from the first condenser lens 38 via the branch element 31 and the first light forming element 32, and the two first laser beams L1 are on the street C (outbound route). The light is focused on the processing start position.

Next, the control device 30 drives the relative movement mechanism 28 to move the laser optical system 24 relative to the wafer 12 on the outward direction side X1 (step S4). Then, when the optical axis of the second condenser lens 40A reaches the processing start position of the street C (outward path), the control device 30 drives the high-speed shutter drive mechanism 47C to emit the second high-speed shutter 47B with the light of the laser beam L. Evacuate from the road (step S5). As a result, the second laser beam L2 is emitted from the second condenser lens 40A via the branch element 31, the second light forming element 34, and the connection switching element 36, and the second laser beam L2 is collected at the above-mentioned processing start position. Be lit. Further, by shifting the start timing of the hollowing process, it is possible to prevent the outside of the wafer 12 from being laser machined (hollowing process).

When the relative movement of the laser optical system 24 to the outward direction side X1 continues, as shown in FIGS. 3 and 5, the two spots of the first laser beam L1 and the spots of the second laser beam L2 are on the street C. It moves to the outbound route side X1 along the (outbound route). As a result, along the street C (outward route), the formation of the two edge cutting grooves 18 by the edge cutting process and the formation of the hollow groove 19 by the hollowing process are simultaneously executed at intervals.

Then, the control device 30 sets the high-speed shutter drive mechanism 47C at the timing when the spots of the two first laser beams L1 emitted from the first condenser lens 38 reach the processing end position of the street C (outward route). Is driven to insert the first high-speed shutter 47A into the optical path of the laser beam L (steps S6 and S7). Further, the control device 30 drives the high-speed shutter drive mechanism 47C at the timing when the spot of the second laser beam L2 emitted from the second condenser lens 40A reaches the above-mentioned processing end position to drive the second high-speed. The shutter 47B is inserted into the optical path of the laser beam L, and the driving of the relative moving mechanism 28 is stopped (step S8). As a result, the laser processing of the first street C (outward route) is completed. When the outside of the wafer 12 may be laser-processed (edge cutting), the timing of inserting the first high-speed shutter 47A into the optical path of the laser beam L is set, and the second high-speed shutter 47B is the light of the laser beam L. It may be adjusted to the timing of insertion on the road.

When the laser processing of the first street C (outward route) is completed, the control device 30 drives the relative movement mechanism 28 to drive the optical axis of the first condenser lens 38 and the second street C (return route). Is aligned with the machining start position of (YES in step S9, step S10).

Further, the control device 30 drives the connection switching element 36 to switch the lens that emits the second laser beam L2 to the second condenser lens 40B (step S11). It should be noted that steps S10 and S11 may also be executed in the reverse order or at the same time.

When step S11 is completed, the control device 30 drives the high-speed shutter drive mechanism 47C to retract the first high-speed shutter 47A from the optical path of the laser beam L (step S12). As a result, two first laser beams L1 are emitted from the first condenser lens 38 via the branch element 31 and the first light forming element 32, and the two first laser beams L1 are on the street C (return path). The light is focused on the processing start position.

Next, the control device 30 drives the relative movement mechanism 28 to move the laser optical system 24 relative to the wafer 12 on the return direction side X2 (step S13). Then, when the optical axis of the second condenser lens 40B reaches the processing start position of the normal street C (return path), the control device 30 drives the high-speed shutter drive mechanism 47C to cause the second high-speed shutter 47B to receive the laser beam L. Evacuate from the optical path (step S14). As a result, the second laser beam L2 is emitted from the second condenser lens 40B via the branch element 31, the second light forming element 34, and the connection switching element 36, and the second laser beam L2 is an outward path from the above-mentioned processing start position. The light is focused at the position shifted to the direction side X1. Further, by shifting the start timing of the hollowing process, it is possible to prevent the outside of the wafer 12 from being laser machined (hollowing process).

When the relative movement of the laser optical system 24 to the return direction side X2 continues, as shown in FIGS. 4 and 6, the two spots of the first laser beam L1 and the spots of the second laser beam L2 are on the street C. Move to X2 on the return route side along (return route). As a result, along the street C (return route), the formation of the two edge cutting grooves 18 by the edge cutting process and the formation of the hollow groove 19 by the hollowing process are simultaneously executed at intervals.

Then, the control device 30 sets the high-speed shutter drive mechanism 47C at the timing when the spots of the two first laser beams L1 emitted from the first condenser lens 38 reach the processing end position of the street C (return path). Is driven to insert the first high-speed shutter 47A into the optical path of the laser beam L (steps S15 and S16). Further, the control device 30 drives the high-speed shutter drive mechanism 47C at the timing when the spot of the second laser beam L2 emitted from the second condenser lens 40B reaches the processing end position, and the second high-speed shutter 47B. Is inserted into the optical path of the laser beam L and the drive of the relative moving mechanism 28 is stopped (step S17). As a result, the laser processing of the second street C (return route) is completed. As described above, the timing of inserting the first high-speed shutter 47A into the optical path of the laser beam L may be matched with the timing of inserting the second high-speed shutter 47B into the optical path of the laser beam L.

Similarly, laser machining (edge cutting and hollowing) is repeatedly executed along all streets C parallel to the X direction (YES in step S9, YES in step S18). Next, the control device 30 drives the relative movement mechanism 28 to rotate the table 20 by 90 °, so that each of the remaining streets C parallel to the Y direction on the wafer 12 is parallel to the X direction. Then, the control device 30 repeatedly executes the above-mentioned series of processes. As a result, laser machining is performed along each street C in a grid pattern.

When the laser machining on all the grid-like streets C is completed (NO in step S9, NO in step S18), the wafer 12 is sent to a post-process where it is divided into a plurality of chips 14 (device 16). In this embodiment, two edge cutting grooves 18 and hollow grooves 19 are formed by one laser processing operation in one direction (outward route: X1 direction, inbound route: X2 direction) for each street C (outward route and inbound route). The flow of the fastest condition to complete is taken as an example, but the present invention is not limited to this. For example, in consideration of the processing depth of each of the two edge cutting grooves 18 and the hollowing groove 19, even if at least one of the edge cutting processing and the hollowing processing is executed a plurality of times for each street C (outward route and return route). good.

[Effect of the first embodiment]
As described above, in the laser processing apparatus 10 of the first embodiment, the second condenser lenses 40A and 40B can be selectively used for hollowing processing according to the relative moving direction of the laser optical system 24 with respect to the wafer 12. can. As a result, the edge cutting process and the hollowing process can be performed simultaneously along the same street C regardless of the outward route and the return route. Therefore, by reciprocating the laser optical system 24 once in the X direction, the laser machining of two streets C (outward and return paths) is completed, so that the tact time required for the laser machining of the wafer 12 is reduced. Further, according to the relative movement direction of the laser optical system 24, the hollowing process by the second condenser lens 40A and the hollowing process by the second condenser lens 40B can be switched by simply operating the connection switching element 36. The complexity of the laser optical system 24 (optical system) is prevented. As a result, the tact time required for laser machining of the wafer 12 can be reduced with a simple configuration.

[Second Embodiment]
Next, the laser processing apparatus 10 of the second embodiment will be described. The laser processing apparatus 10 of the second embodiment has a function of adjusting the distance between the two edge cutting grooves 18 in the Y direction and the width of the hollow groove 19 in the Y direction. The laser processing apparatus 10 of the second embodiment is provided with a first rotation mechanism 44 (see FIGS. 8 and 9) and a second rotation mechanism 46 (see FIGS. 10 and 11), which will be described later, except that the laser processing device 10 includes the first rotation mechanism 44 (see FIGS. 8 and 9). It has basically the same configuration as the laser processing apparatus 10 of the first embodiment. Therefore, those having the same function or configuration as those of the first embodiment are designated by the same reference numerals and the description thereof will be omitted.

8 and 9 are explanatory views for explaining the spacing adjustment of the two edge cutting grooves 18 in the Y direction by the first rotation mechanism 44. As shown in FIGS. 8 and 9, the first rotation mechanism 44 is composed of, for example, a motor and a drive transmission mechanism, and the first light forming element 32 is centered on the optical axis under the control of the control device 30. Rotate in the direction around the axis. As a result, when the wafer 12 is viewed from above in the Z direction, the spots of the two first laser beams L1 focused on the street C by the first condenser lens 38 are spotted on the first condenser lens 38. It can be rotated around the optical axis. As a result, the distance between the spots of the two first laser beams L1 focused on the street C in the Y direction can be widened or narrowed, so that the distance between the two edge cutting grooves 18 in the Y direction can be widened or narrowed. Can be adjusted.

10 and 11 are explanatory views for explaining the width adjustment of the hollow groove 19 in the Y direction by the second rotation mechanism 46. As shown in FIGS. 10 and 11, the second rotation mechanism 46 is composed of, for example, a motor and a drive transmission mechanism like the first rotation mechanism 44, and is a second optical forming element under the control of the control device 30. The 34 is rotated in the direction around the axis around the optical axis. As a result, when the wafer 12 is viewed from above in the Z direction, the spots of the second laser beam L2 focused on the street C by the second condenser lenses 40A and 40B are spotted on the second condenser lenses 40A and 40B. Can be rotated around the optical axis of. Here, the spot of the second laser beam L2 formed on the street C has a rectangular shape, that is, a non-circular shape. Therefore, by rotating the rectangular spot, it is possible to make adjustments such as widening or narrowing the width of the hollow groove 19 formed on the street C in the Y direction. The shape of the spot of the second laser beam L2 is not limited to a rectangular shape as long as it is a non-circular shape.

The control device 30 drives the first rotation mechanism 44 and the second rotation mechanism 46, respectively, based on the adjustment instruction input to the operation unit (not shown) by the operator, and the first light forming element 32 and the second light forming element 32, respectively. By rotating each of the 34, the distance between the two edge cutting grooves 18 and the width of the hollow groove 19 are adjusted.

[Third Embodiment]
FIG. 12 is a schematic view of the laser processing apparatus 10 of the third embodiment. In the laser processing apparatus 10 of each of the above embodiments, edge cutting and hollowing are performed along the street C of the wafer 12. At this time, in the laser processing apparatus 10 of each of the above embodiments, the processing point of the edge cutting process (the spot of the two first laser beams L1 condensed on the street C by the first condenser lens 38) and the middle Since the total of 3 processing points including the 2 processing points of the punching process (the spot of the 2nd laser beam L2 condensed on the street C by the 2nd condensing lenses 40A and 40B) are independent of each other, each processing is performed. The points have an interval of several tens of mm. Therefore, if the positions of the first condensing lens 38 and the second condensing lenses 40A and 40B in the laser optical system 24 are fixed as in each of the above embodiments, the processing feed shaft (X) during laser processing is used. Depending on the motion accuracy of the shaft), a deviation occurs in the horizontal direction (Y direction) and the vertical direction (Z direction) between the processing point of the two edge cutting grooves 18 and the processing point of the hollow groove 19. There is a problem that it deviates from the optimum processing point).

Therefore, the laser machining apparatus 10 of the third embodiment has a function of individually adjusting the positions in the Y direction and the Z direction of the machining point of edge cutting and the two machining points of hollowing. The laser processing device 10 of the third embodiment is basically the same as the laser processing device 10 of each of the above-described embodiments, except that it includes three mirrors 37, 39A, 39B and three moving mechanisms 48, 49A, 49B. It has the same configuration. Therefore, those having the same function or configuration as each of the above embodiments are designated by the same reference numerals and the description thereof will be omitted.

The mirror 37 (first reflecting element) is arranged above the first condensing lens 38 in the Z direction, and two first lenses incident from the laser light source 22 via the branching element 31 and the first light forming element 32. The laser beam L1 is reflected toward the first condensing lens 38.

The mirrors 39A and 39B correspond to the second reflecting element of the present invention. The mirror 39A is arranged above the second condenser lens 40A in the Z direction, and reflects the second laser beam L2 incident from the laser light source 22 via the connection switching element 36 or the like toward the second condenser lens 40A. do. Further, the mirror 39B is arranged above the second condensing lens 40B in the Z direction, and directs the second laser beam L2 incident from the laser light source 22 via the connection switching element 36 or the like toward the second condensing lens 40B. Reflects.

The moving mechanism 48 corresponds to the first moving mechanism of the present invention, and the moving mechanisms 49A and 49B correspond to the second moving mechanism of the present invention. As the moving mechanisms 48, 49A, 49B, for example, known linear actuators are used. Under the control of the control device 30, the moving mechanism 48 integrally moves the mirror 37 and the first condenser lens 38 in the Y direction (corresponding to the first vertical direction of the present invention), and moves the first condenser lens 38. Move in the Z direction (corresponding to the second vertical direction of the present invention). Under the control of the control device 30, the moving mechanism 49A integrally moves the mirror 39A and the second condenser lens 40A in the Y direction, and moves the second condenser lens 40A in the Z direction. Further, the moving mechanism 49B integrally moves the mirror 39B and the second condenser lens 40B in the Y direction and moves the second condenser lens 40B in the Z direction under the control of the control device 30.

Instead of moving the first condenser lens 38 and the second condenser lenses 40A and 40B in the Y direction by the moving mechanisms 48, 49A and 49B, respectively, the first condenser lens 38 and the second condenser lenses 40A and 40B are used. May be tilted.

As described above, in the third embodiment, the mirror 37 and the first condenser lens 38, the mirror 39A and the second condenser lens 40A, and the mirror 39B and the second condenser lens 40B are individually moved in the Y direction and the Z direction, respectively. Can be made to. As a result, the positions of the two spots of the first laser beam L1 formed on the street C and the spots of the second laser beam L2 for each of the second condenser lenses 40A and 40B are individually positioned in the Y direction and the Z direction. Can be adjusted. Thereby, for example, the manufacturer of the laser processing apparatus 10 can adjust the Y-direction position and the Z-direction position of each spot (adjust the parallelism).

Further, the street C and the two edge cutting grooves 18 (spots of the two first laser beams L1) and the hollow grooves 19 (spots of the second laser beam L2) photographed by the microscope 26 during the laser processing of the wafer 12 are taken. Based on the photographed image of, the processing point (spot) of the edge cutting process can be traced to the street C, and the processing point (spot) of the hollowing process can be traced to the center of the two edge cutting grooves 18. Further, based on the above-mentioned captured image, the amount of deviation (of the condensing position) between the two spots of the first laser beam L1 and the spots of the second laser beam L2 with respect to the surface of the wafer 12 (street C) in the Z direction. The amount of deviation) can be adjusted.

In this case, the processed grooves (two edge cutting grooves 18, hollow grooves 19) and spots can be simultaneously photographed for each of the first condensing lens 38 and the second condensing lenses 40A and 40B. A camera may be provided.

As described above, in the third embodiment, the positions of the three processing points including the processing point of the edge cutting process and the two processing points of the hollowing process can be individually adjusted in the Y direction and the Z direction. It is possible to move (trace) each machining point with an optimum motion locus regardless of the motion accuracy of the machining feed axis (X axis).

In the third embodiment, the positions of the three processing points including the processing point of edge cutting and the two processing points of hollowing are individually adjustable in the Y direction and the Z direction, but in the Y direction and the Z direction. Only one of them may be adjustable.

In the third embodiment, the positions of the three processing points including the processing point of edge cutting and the two processing points of hollowing are individually adjustable by the moving mechanisms 48, 49A, and 49B. However, the position of the processing point of the edge cutting process may be adjusted by the moving mechanism 48, and the position of the two processing points of the hollowing process may be adjusted by the relative moving mechanism 28. That is, the positions of the two machining points of the hollowing process may be adjusted by moving the table 20 in at least one of the Y direction and the Z direction by the relative moving mechanism 28.

Conversely, the positions of the processing points for edge cutting may be adjusted by moving the table 20 by the relative moving mechanism 28, and the positions of the two processing points for hollowing may be adjusted by the moving mechanisms 49A and 49B.

FIG. 43 is an explanatory diagram for explaining a modified example of the third embodiment. The first laser light source 22A and the second laser light source 22B in FIG. 43 will be described in the fourth embodiment. In the third embodiment, the positions of the two machining points of the hollowing process in the Y direction and the Z direction can be individually adjusted by the moving mechanisms 49A and 49B. On the other hand, as shown by reference numerals 1000A and 1000B in FIG. 43, the second condenser lenses 40A and 40B and the mirrors 39A and 39B corresponding to the two processing points of the hollowing process are framed in the same frame (not shown). It may be installed above and the positions of the two machining points for hollowing may be integrally adjustable in at least one of the Y direction and the Z direction by one moving mechanism 49. Since the two processing points of the hollowing process are not processed at the same time, there is no problem even if the positions of the two processing points of the hollowing process are moved integrally.

Further, in FIG. 43, the position of the processing point of the edge cutting process may be adjusted by moving the table 20 by the relative movement mechanism 28. Furthermore, the position adjustment of the two processing points of the hollowing process may be performed by moving the table 20 by the relative moving mechanism 28.

[Fourth Embodiment]
Next, the laser processing apparatus 10 of the fourth embodiment will be described. In the laser processing apparatus 10 of each of the above embodiments, two first laser light L1 for edge cutting and a second laser light L2 for hollowing are formed from the laser light L emitted from the common laser light source 22. However, the conditions (wavelength, pulse width, repetition frequency, etc.) of the suitable laser beam L are different between the edge cutting process and the hollowing process. Therefore, if the conditions of the laser beam L deviate from the conditions suitable for either edge cutting or hollowing, it is necessary to slow down the processing speed of one of them, and the processing speed of the other is also increased accordingly. Need to be late.

That is, when performing edge cutting groove processing and hollow groove processing with one laser light source 22, the speed of edge cutting groove processing can be improved depending on the laser light conditions, but the speed of hollow groove processing cannot be improved, and the speed is improved. It is necessary to process at a speed of hollow groove processing that cannot be performed. The opposite may be true depending on the laser light conditions. Therefore, the speed on the lower side in each case becomes the upper limit speed in machining. In this way, the edge cutting process for forming the two edge cutting grooves 18 (blocking groove) along the street C of the wafer 12 and the groove processing for forming the hollow groove 19 (divided groove) between the two edge cutting grooves 18 Then, since there are laser light conditions suitable for the processing speed and the processing finish, it is difficult to satisfy both conditions with one laser light source 22.

Therefore, in the fourth embodiment, a different light source is used for each of the first laser beam L1 and the second laser beam L2.

FIG. 13 is an explanatory diagram for explaining edge cutting and hollowing by the laser optical system 24 which is relatively moved to the outward direction side X1 with respect to the wafer 12 in the fourth embodiment. FIG. 14 is an explanatory diagram for explaining edge cutting and hollowing by the laser optical system 24 which is relatively moved to the return direction side X2 with respect to the wafer 12 in the fourth embodiment.

As shown in FIGS. 13 and 14, in the laser processing apparatus 10 of the fourth embodiment, instead of the laser light source 22 and the branching element 31, the first laser light source 22A, the second laser light source 22B, and the first safety shutter 100A are used. The configuration is basically the same as that of the laser processing apparatus 10 of each of the above-described embodiments, except that the second safety shutter 100B and the safety shutter drive mechanism 102A are provided. Therefore, those having the same function or configuration as each of the above embodiments are designated by the same reference numerals and the description thereof will be omitted.

The first laser light source 22A constantly emits laser light LA under conditions suitable for edge cutting (wavelength, pulse width, repetition frequency, etc.) to the first light forming element 32. As a result, as in each of the above embodiments, the formation of the two first laser beams L1 by the first light forming element 32 and the two first laser beams L1 on the street C by the first condenser lens 38. Condensing and condensing is performed.

The second laser light source 22B constantly emits the laser light LB under the conditions suitable for the hollowing process (wavelength, pulse width, repetition frequency, etc.) to the second light forming element 34. As a result, as in each of the above embodiments, the second light forming element 34 forms the second laser beam L2, the connection switching element 36 switches between the second condensing lenses 40A and 40B, and the second condensing lens 40A. The second laser beam L2 is focused on the street C (outbound route) by the second condenser lens 40B, and the second laser beam L2 is focused on the street C (return route) by the second condenser lens 40B.

The first safety shutter 100A is removably provided on the optical path of the laser beam LA between the first laser light source 22A and the first light forming element 32. Further, the second safety shutter 100B is provided removably on the optical path of the laser beam LB between the second laser light source 22B and the second light forming element 34.

Under the control of the control device 30, the safety shutter drive mechanism 102A inserts and removes the first safety shutter 100A from the optical path of the laser beam LA, and inserts and removes the second safety shutter 100B from the optical path of the laser beam LB. It is an actuator to make it. The safety shutter drive mechanism 102A stops the emission of the two first laser beams L1 from the laser optical system 24 by inserting the first safety shutter 100A into the optical path of the laser beam LA except during edge cutting. Let me. Further, the safety shutter drive mechanism 102A retracts the first safety shutter 100A from the optical path of the laser beam LA at the time of edge cutting, so that two first laser beams L1 are emitted from the laser optical system 24.

Similarly, the safety shutter drive mechanism 102A emits the second laser beam L2 from the laser optical system 24 by inserting the second safety shutter 100B into the optical path of the laser beam LB except during the hollowing process. To stop. Further, the safety shutter drive mechanism 102A retracts the second safety shutter 100B from the optical path of the laser beam LB at the time of hollowing, so that the second laser beam L2 is emitted from the laser optical system 24.

The flow of the laser processing for each street C by the laser processing apparatus 10 of the fourth embodiment is basically the same as the flow of the laser processing of the first embodiment shown in FIG. 7 described above. However, in step S0 of the fourth embodiment, the control device 30 controls the safety shutter drive mechanism 102A to retract the first safety shutter 100A from the optical path of the laser light LA and to move the second safety shutter 100B to the laser light LB. Evacuate from the optical path.

As described above, in the fourth embodiment, the first laser light source 22A corresponding to the edge cutting process and the second laser light source 22B corresponding to the center cutting process are separately provided, so that the edge cutting process and the center cutting process are performed respectively. The slowdown is prevented. As a result, the above-mentioned takt time can be further reduced. In addition, the processing qualities of the edge cutting process and the hollowing process can be optimized.

Further, in the edge cutting process and the hollowing process, the processing speed can be improved by optimizing the processing conditions at the wavelengths by using the laser beams LA and LB having different wavelengths. As a result, the laser machining apparatus 10 using the first laser light source 22A and the second laser light source 22B of the fourth embodiment is more than the laser machining apparatus 10 using a single laser light source 22 as in the first embodiment. Machining at high speed is possible.

In the fourth embodiment as well, as in the third embodiment, the third embodiment is performed by individually adjusting the positions in the Y direction and the Z direction of the processing point of the edge cutting process and the two processing points of the hollowing process. The same effect as the morphology can be obtained. Further, not only the positions of the three processing points including the processing point of edge cutting and the two processing points of hollowing can be individually adjusted in the Y direction and the Z direction, but also only one of the Y direction and the Z direction can be adjusted. May be adjustable.

[Specific example of connection switching element of the fourth embodiment]
Next, specific examples 1 to 3 of the connection switching element 36 of the fourth embodiment will be described. The configuration other than the connection switching element 36 is basically the same as that of the laser processing apparatus 10 of the fourth embodiment (first to third embodiment). Therefore, those having the same function or configuration as each of the above embodiments are designated by the same reference numerals and the description thereof will be omitted. Further, these specific examples 1 to 3 can also be applied to the connection switching element 36 of the first to third embodiments.

<Specific example 1 of the connection switching element 36>
FIG. 15 is an explanatory diagram for explaining a specific example 1 of the connection switching element 36 of the fourth embodiment. As shown in FIG. 15, the connection switching element 36 of the first embodiment includes a λ / 2 plate 52, a plate rotation mechanism 53, and a polarization beam splitter 54.

The λ / 2 plate 52 rotates the polarization direction of the second laser beam L2 (linearly polarized light) emitted from the second light forming element 34, and then emits the second laser beam L2 toward the polarizing beam splitter 54. do.

The plate rotation mechanism 53 adjusts the polarization direction of the second laser beam L2 by rotating the λ / 2 plate 52 about its optical axis under the control of the control device 30. As a result, in the plate rotation mechanism 53, when the laser optical system 24 is relatively moved to the outward direction side X1 with respect to the wafer 12 by the relative movement mechanism 28, the second laser beam L2 is S-polarized. Adjust the rotation angle of the λ / 2 plate 52. Further, the plate rotation mechanism 53 is λ so that when the laser optical system 24 is relatively moved to the return direction side X2 with respect to the wafer 12 by the relative movement mechanism 28, the second laser beam L2 is P-polarized. / 2 Adjust the rotation angle of the plate 52.

The polarization beam splitter 54 reflects the S polarization toward the second condenser lens 40A, transmits the P polarization as it is, and emits the S polarization toward the second condenser lens 40B. Thereby, the second condenser lenses 40A and 40B can be selectively used for the hollowing process according to the relative movement direction (outward direction side X1 or inbound direction side X2) of the laser optical system 24 with respect to the wafer 12. ..

<Specific example 2 of the connection switching element 36>
FIG. 16 is an explanatory diagram for explaining a specific example 2 of the connection switching element 36 of the fourth embodiment. As shown in FIG. 16, the connection switching element 36 of the second embodiment includes a half mirror 58, a mirror 60, shutters 62A and 62B, and a shutter drive mechanism 64.

The half mirror 58 is arranged on the optical path of the second laser beam L2 emitted from the second light forming element 34 and at a position facing the second condenser lens 40A. The half mirror 58 bifurcates the second laser beam L2 incident from the second light forming element 34, reflects one of the bifurcated second laser beam L2 toward the second condenser lens 40A, and second. It passes through the other side of the laser beam L2 and emits light toward the mirror 60.

The mirror 60 is arranged on the optical path of the second laser beam L2 transmitted through the half mirror 58 and at a position facing the second condenser lens 40B. The mirror 60 reflects the second laser beam L2 transmitted through the half mirror 58 toward the second condenser lens 40B.

The shutter 62A is removably provided on the optical path of the second laser beam L2 between the half mirror 58 and the second condenser lens 40A. As a result, when the shutter 62A is inserted into the optical path of the second laser beam L2, the second laser beam L2 reflected by the half mirror 58 is blocked by the shutter 62A. Further, when the shutter 62A is retracted from the optical path of the second laser beam L2, the second laser beam L2 reflected by the half mirror 58 is incident on the second condenser lens 40A.

The shutter 62B is removably provided on the optical path of the second laser beam L2 between the mirror 60 and the second condenser lens 40B. As a result, when the shutter 62B is inserted in the optical path of the second laser beam L2, the second laser beam L2 reflected by the mirror 60 is blocked by the shutter 62B. When the shutter 62B is retracted from the optical path of the second laser beam L2, the second laser beam L2 reflected by the mirror 60 is incident on the second condenser lens 40B.

The shutter drive mechanism 64 is a known actuator that inserts / removes (opens / closes) the shutters 62A and 62B on the optical path of the second laser beam L2 under the control of the control device 30. When the laser optical system 24 is relatively moved to the outward direction side X1 with respect to the wafer 12, the shutter drive mechanism 64 retracts the shutter 62A from the optical path of the second laser beam L2 and the shutter. 62B is inserted into the optical path of the second laser beam L2.

On the contrary, when the laser optical system 24 is relatively moved to the return path side X2 with respect to the wafer 12, the shutter drive mechanism 64 moves the shutter 62A onto the optical path of the second laser beam L2. At the same time as inserting the shutter 62B, the shutter 62B is retracted from the optical path of the second laser beam L2. As a result, the hollowing process is performed by selectively using the two second condensing lenses 40A and 40B according to the relative movement direction (outward direction side X1 or inbound direction side X2) of the laser optical system 24 with respect to the wafer 12. be able to.

<Specific example 3 of the connection switching element 36>
FIG. 17 is an explanatory diagram for explaining a specific example 3 of the connection switching element 36 of the fourth embodiment. As shown in FIG. 17, the connection switching element 36 of the third embodiment includes a mirror 66A, a mirror 66B, and a mirror drive mechanism 68.

The mirror 66A is removably provided on the optical path of the second laser beam L2 emitted from the second light forming element 34 and at a position facing the second condenser lens 40A. When the mirror 66A is inserted in the optical path of the second laser beam L2, the mirror 66A reflects the second laser beam L2 incident from the second light forming element 34 toward the second condenser lens 40A. When the mirror 66A is retracted from the optical path of the second laser beam L2, the second laser beam L2 emitted from the second light forming element 34 is incident on the mirror 66B.

The mirror 66B is provided on the optical path of the second laser beam L2 emitted from the second light forming element 34 and at a position facing the second condenser lens 40B. The mirror 66B reflects the second laser beam L2 incident from the second light forming element 34 toward the second condenser lens 40B.

The mirror drive mechanism 68 is a known actuator that inserts and removes the mirror 66A on the optical path of the second laser beam L2 under the control of the control device 30. When the laser optical system 24 is relatively moved to the outward direction side X1 with respect to the wafer 12, the mirror drive mechanism 68 inserts the mirror 66A into the optical path of the second laser beam L2. As a result, all of the second laser beam L2 emitted from the second light forming element 34 is reflected by the mirror 66A toward the second condenser lens 40A.

On the contrary, when the laser optical system 24 is relatively moved to the return direction side X2 with respect to the wafer 12, the mirror drive mechanism 68 moves the mirror 66A from the optical path of the second laser beam L2. Evacuate. As a result, all of the second laser beam L2 emitted from the second light forming element 34 is reflected by the mirror 66B toward the second condenser lens 40B. As a result, the hollowing process is performed by selectively using the two second condensing lenses 40A and 40B according to the relative movement direction of the laser optical system 24 with respect to the wafer 12 (outward direction side X1 or inbound direction side X2). be able to.

[Fifth Embodiment]
Next, the laser processing apparatus 10 of the fifth embodiment will be described. The laser processing apparatus 10 of the fourth embodiment is provided with two types of first laser light source 22A and second laser light source 22B, but one of the first laser light source 22A and the second laser light source 22B is defective. If this occurs, laser processing of the wafer 12 cannot be performed. Therefore, the laser processing apparatus 10 of the fifth embodiment has a function of being able to continue laser processing of the wafer 12 even if a defect occurs in either the first laser light source 22A or the second laser light source 22B.

FIG. 18 is an explanatory diagram for explaining edge cutting and hollowing by the laser optical system 24 which is relatively moved to the outward direction side X1 with respect to the wafer 12 in the fifth embodiment. FIG. 19 is an explanatory diagram for explaining edge cutting and hollowing by the laser optical system 24 which is relatively moved to the return direction side X2 with respect to the wafer 12 in the fifth embodiment. It should be noted that FIGS. 18 and 19 show a case where the second laser light source 22B has a defect.

As shown in FIGS. 18 and 19, the laser processing apparatus 10 of the fifth embodiment is laser-processed according to the fourth embodiment (including specific examples 1 to 3) except that the bypass optical systems 72 and 74 are provided. It has basically the same configuration as the device 10. Therefore, those having the same function or configuration as the fourth embodiment are designated by the same reference numerals and the description thereof will be omitted.

The bypass optical system 72 is composed of one or a plurality of optical elements, and is provided on the optical path of the laser light LA between the first laser light source 22A and the first light forming element 32. In this bypass optical system 72, under the control of the control device 30, if there is no problem with the second laser light source 22B, all the laser light LA emitted from the first laser light source 22A is sent to the first light forming element 32. It emits toward. The presence or absence of a defect in the second laser light source 22B can be determined by monitoring the operation of the second laser light source 22B, the amount of light of the laser light LB, and the like.

On the other hand, under the control of the control device 30, the bypass optical system 72 branches the laser light LA emitted from the first laser light source 22A into two branches when the second laser light source 22B has a problem. One of the laser light LA is emitted toward the first light forming element 32, and the other of the laser light LA is emitted toward the second light forming element 34. As a result, the second laser beam L2 is formed from the laser beam LA by the second light forming element 34. The second laser beam L2 is selectively emitted from the second condenser lenses 40A and 40B via the connection switching element 36 according to the relative moving direction of the laser optical system 24 as in the fourth embodiment.

The bypass optical system 74 is composed of one or a plurality of optical elements like the bypass optical system 72, and is provided on the optical path of the laser beam LB between the second laser light source 22B and the second light forming element 34. ing. In this bypass optical system 74, under the control of the control device 30, if there is no problem with the first laser light source 22A, all the laser light LB emitted from the second laser light source 22B is sent to the second light forming element 34. It emits toward. The presence or absence of a defect in the first laser light source 22A can also be determined by monitoring the operation of the first laser light source 22A, the amount of light of the laser light LA, and the like.

On the other hand, under the control of the control device 30, the bypass optical system 74 branches the laser light LB emitted from the second laser light source 22B into two branches when the first laser light source 22A has a problem. One of the laser light LB is emitted toward the second light forming element 34, and the other of the laser light LB is emitted toward the first light forming element 32. As a result, two first laser beams L1 are formed from the laser beam LB at the first light forming element 32. The two first laser beams L1 are emitted from the first condenser lens 38 in the same manner as in the fourth embodiment.

As described above, in the laser processing apparatus 10 of the fifth embodiment, by providing the bypass optical systems 72 and 74, even if a defect occurs in either the first laser light source 22A or the second laser light source 22B, the wafer 12 Laser processing can be continued. As a result, the downtime of the laser processing apparatus 10 can be reduced.

[Sixth Embodiment]
Next, the laser processing apparatus 10 of the sixth embodiment will be described. The laser processing apparatus 10 of each of the above embodiments includes a first condensing lens 38 for edge cutting and a second condensing lens 40A for hollowing with the first condensing lens 38 sandwiched between the first condensing lens 38. Although 40B is provided, the first condensing lens 38 and the second condensing lenses 40A and 40B may be interchanged.

FIG. 20 is an explanatory diagram for explaining edge cutting and hollowing by the laser optical system 24 which is relatively moved to the outward direction side X1 with respect to the wafer 12 in the sixth embodiment. FIG. 21 is an explanatory diagram for explaining edge cutting and hollowing by the laser optical system 24 which is relatively moved to the return direction side X2 with respect to the wafer 12 in the sixth embodiment.

As shown in FIGS. 20 and 21, in the laser processing apparatus 10 of the sixth embodiment, one second condenser lens 40 for hollowing is provided in place of the first condenser lens 38, and the second condenser lens 40 is provided. Instead of the condenser lenses 40A and 40B, two first condenser lenses 38A and 38B for edge cutting are provided, and the arrangements of the first light forming element 32 and the second light forming element 34 are interchanged. Since the other configurations are basically the same as those of the laser processing apparatus 10 of the first to third embodiments, specific description thereof will be omitted here.

The first condenser lenses 38A and 38B and the second condenser lens 40 are arranged in a row along the X direction (processing feed direction). The second condenser lens 40 is arranged between the two first condenser lenses 38A and 38B. The first condensing lens 38A is arranged on the outward direction side X1 with respect to the second condensing lens 40. The first condensing lens 38B is arranged on the return path side X2 with respect to the second condensing lens 40.

The first condensing lens 38A condenses two first laser beams L1 input from the connection switching element 36 via the first light forming element 32 onto the street C (outward route). The first condensing lens 38B condenses two first laser beams L1 input from the connection switching element 36 via the first light forming element 32 onto the street C (return path). The second condensing lens 40 condenses the second laser beam L2 input from the second light forming element 34 on the street C (outward and return paths).

The connection switching element 36 of the sixth embodiment is the first when the relative moving mechanism 28 moves the laser optical system 24 relative to the wafer 12 in either the outward direction side X1 or the inbound direction side X2. The two first laser beams L1 emitted from the light forming element 32 are guided to the lens located on the one-way side of the second condensing lens 40 among the two first condensing lenses 38A and 38B. ..

Specifically, as shown in FIG. 20, the connection switching element 36 controls the control device 30 when the laser optical system 24 is relatively moved to the outward path direction X1 with respect to the wafer 12 by the relative movement mechanism 28. Below, the two first laser beams L1 emitted from the first optical forming element 32 are guided to the first condenser lens 38A. As a result, the two first laser beams L1 are focused on the street C (outward route) by the first condenser lens 38A. Further, the second laser beam L2 is condensed by the second condenser lens 40. As a result, the edge cutting process and the hollowing process are executed along the street C (outward path) by the relative movement of the laser optical system 24 to the outward path direction side X1.

As shown in FIG. 21, when the laser optical system 24 is relatively moved to the return path side X2 with respect to the wafer 12 by the relative movement mechanism 28, the connection switching element 36 is controlled by the control device 30. The two first laser beams L1 emitted from the one optical forming element 32 are guided to the first condenser lens 38B. As a result, the two first laser beams L1 are focused on the street C (return path) by the first condenser lens 38B. Further, the second laser beam L2 is condensed by the second condenser lens 40. As a result, the edge cutting process and the hollowing process are executed along the street C (return path) by the relative movement of the laser optical system 24 to the return path side X2.

As for the fourth embodiment (including specific examples 1 to 3) and the fifth embodiment, the arrangement of the first condensing lens 38 and the second condensing lenses 40A and 40B is the same as in the sixth embodiment. At the same time, the arrangement of the first light forming element 32 and the second light forming element 34 may be changed.

Further, even if the position adjustment of the two machining points of edge cutting is performed by moving the table 20 by the relative moving mechanism 28, or the position of the machining point of the hollowing machining is adjusted by moving the table 20 by the relative moving mechanism 28. good. Further, as a modification of the embodiment shown in FIG. 43 described above, the first condenser lenses 38A, 38B and the like corresponding to the two processing points of the edge cutting process are installed on the same frame (not shown). The positions of the two processing points for edge cutting may be integrally adjustable in at least one of the Y direction and the Z direction by the two moving mechanisms 48.

[7th Embodiment]
FIG. 22 is an explanatory diagram for explaining a problem when the intensity distribution (E) of the second laser beam L2 has a Gaussian shape. FIG. 23 is an explanatory diagram showing an example of the ideal intensity distribution (E) of the second laser beam L2. FIG. 24 is an explanatory diagram showing an example of the actual intensity distribution (E) of the second laser beam L2.

As shown by the reference numeral XXIIA in FIG. 22, the intensity distribution of the laser beam L emitted from the laser light source 22 has a Gaussian shape. Therefore, when the hollowing process is executed by the second laser beam L2 having a Gaussian shape, the cross-sectional shape of the hollow groove 19 (the edge cutting groove 18 of the two rows is not shown) also becomes a Gaussian shape as shown by the reference numeral XXIIB. In this case, in the cutting step of cutting the wafer 12 along the hollow groove 19 (street C) by the blade 110 that rotates at high speed after laser machining, the blade 110 is biased to the blade 110 depending on the positional relationship of the blade 110 with respect to the hollow groove 19. Wear may occur. Therefore, it is required to form the bottom of the hollow groove 19 flat (including substantially flat).

As shown in FIG. 23, in order to form the bottom of the hollow groove 19 flat, for example, a DOE and a refraction type beam shaper are used to form the intensity distribution of the second laser beam L2 into an isotropic top hat shape. The method can be considered. However, although the optical elements such as the DOE and the refraction type beam shaper described above are made on the premise of an ideal perfect circle (cross-sectional shape) of the laser beam L (beam), the actual cross-sectional shape of the laser beam L is a perfect circle. Instead, it becomes an elliptical shape (a state in which the spread angle has anisotropy) due to individual differences in the laser light source 22 and the like. In this case, as shown in FIG. 24, since the intensity distribution (E) of the second laser beam L2 has a shape different from the top hat shape, it is difficult to form the bottom of the hollow groove 19 flat. Become.

Further, as described above, when the spread angle of the laser beam L has anisotropy, astigmatism occurs, and the Z position of the top hat shape is different in each of the XY directions. Further, when the hollowing process is performed using the second laser beam L2 having the intensity distribution (E) as shown in FIG. 23, the cross-sectional shape of the hollowing groove 19 makes the spot of the second laser beam L2. The shape is integrated according to the overlap ratio in the machining feed direction (X direction). As a result, it is difficult to infer the cross-sectional shape of the hollow groove 19 from the shape of the spot alone of the second laser beam L2.

Therefore, in the laser processing apparatus 10 of the seventh embodiment, the second light so that the intensity distribution (E) of the second laser light L2 becomes a stable top hat shape and the cross-sectional shape of the hollow groove 19 can be easily estimated. The intensity distribution (E) of the second laser beam L2 is adjusted by the forming element 34. The laser processing device 10 of the seventh embodiment has basically the same configuration as the laser processing device 10 of each of the above-described embodiments, except that the functions of the second light forming element 34 are different. Therefore, those having the same function or configuration as each of the above embodiments are designated by the same reference numerals and the description thereof will be omitted.

The reference numeral XXVA of FIG. 25 is an explanatory diagram showing an example of the intensity distribution (E) of the second laser beam L2 of the seventh embodiment in the Y direction, and the reference numeral XXVB is the X of the second laser beam L2 of the seventh embodiment. It is explanatory drawing which showed an example of the intensity distribution (E) in a direction. FIG. 26 is an explanatory diagram showing an example of the intensity distribution of the XY plane of the second laser beam L2 of the seventh embodiment.

As shown in FIGS. 25 and 26, the second laser beam L2 formed by the second light forming element 34 of the seventh embodiment is a top hat in the first direction (for example, the Y direction perpendicular to the machining feed direction). It has a shape intensity distribution and a Gaussian-shaped intensity distribution in the second direction (X direction parallel to the machining feed direction). As such a second light forming element 34, for example, an optical element such as a DOE and a refraction type beam shaper (a combination of a plurality of types of optical elements is also possible) is used.

As described above, the formation of the second laser beam L2 having the intensity distribution of the top hat shape only in one direction (here, the Y direction) has the intensity distribution of the top hat shape in a plurality of directions as shown in FIG. 23. Compared with the formation of the two laser beams L2, the difficulty of adjusting the formation of the second laser beam L2 into a top hat shape is lowered. As a result, the second laser beam L2 can be formed into a stable top hat shape, so that the bottom of the hollow groove 19 can be formed flat.

Further, by forming the intensity distribution of the second laser beam L2 in the X direction (machining feed direction) into a Gaussian shape, the profile shape (that is, the inverted top hat shape) of the spot of the second laser beam L2 in the Y direction is hollowed out. It can be directly reflected in the processed shape of the groove 19. As a result, the machined shape of the hollow groove 19 can be easily inferred from the shape of the spot alone of the second laser beam L2.

In FIGS. 25 and 26, the first direction is the Y direction and the second direction is the X direction, but the second light is provided by the second rotation mechanism 46 of the second embodiment (see FIGS. 10 and 11). By rotating the forming element 34, the first direction and the second direction can be set to any direction in the XY plane (in the horizontal plane). That is, when the directions parallel to the table 20 (vertical to the traveling direction of the second laser beam L2 emitted from the second light forming element 34) and orthogonal to each other are the first direction and the second direction, the second light The forming element 34 forms a second laser beam L2 having a top hat-shaped intensity distribution in the first direction and a Gaussian-shaped intensity distribution in the second direction.

Further, in the seventh embodiment, the second light forming element 34 forms the second laser beam L2 having the intensity distribution of the top hat shape only in one direction, but the first light forming element 32 also forms the second laser light L2 in one direction. Only two first laser beams L1 having a top hat-shaped intensity distribution may be formed. Further, the invention of the seventh embodiment can be applied to various laser machining of the wafer 12 other than edge cutting and hollowing.

[Eighth Embodiment]
FIG. 27 is a schematic view of the laser optical system 24 of the laser processing apparatus 10 of the eighth embodiment. In each of the above embodiments, the edge cutting process is performed using any of the first condensing lenses 38, 38A, and 38B, and the hollowing process is performed using any of the second condensing lenses 40, 40A, 40B. On the other hand, as shown in FIG. 27, in the laser processing apparatus 10 of the eighth embodiment, the edge cutting process is performed using the first condenser lens group 120, and either of the second condenser lens groups 122A and 122B is used. Use to perform hollowing.

The laser processing apparatus 10 of the eighth embodiment has the above-mentioned embodiments (excluding the sixth embodiment) except that the laser processing apparatus 10 includes the first condenser lens group 120 and the second condenser lens groups 122A and 122B. It has basically the same configuration as the laser processing apparatus 10. Therefore, those having the same function or configuration as each of the above embodiments are designated by the same reference numerals, and the description thereof will be omitted. The first condensing lens group 120 and the second condensing lens groups 122A and 122B together with the connection switching element 36 and the like described above constitute a condensing optical system.

The first condensing lens group 120 is provided in place of the first condensing lens 38 of each of the above embodiments. The first condensing lens group 120 includes a branching element 124 and three first condensing lenses 38.

The branching element 124 branches the two first laser beams L1 incident from the first light forming element 32 into three branches and emits the two first laser beams L1 toward the three first condensing lenses 38, respectively. The three first condensing lenses 38 are arranged in a row along the X direction (processing feed direction), and the two first laser beams L1 incident from the branch element 124 are directed to the street C (outward path and return path, respectively). ) Condensate on the top at the same time.

The second condenser lens group 122A is provided in place of the second condenser lens 40A of each of the above embodiments. The second condensing lens group 120A includes a branching element 126A and three second condensing lenses 40A.

The branching element 126A branches the second laser beam L2 incident from the second light forming element 34 into three branches and emits the second laser beam L2 toward the three second condensing lenses 40A. The three second condenser lenses 40A are arranged in a row along the X direction (processing feed direction), and the second laser beam L2 incident from the branch element 126A is simultaneously collected on the street C (outward route). Let it shine.

The second condenser lens group 122B is provided in place of the second condenser lens 40B of each of the above embodiments. The second condensing lens group 120B includes a branching element 126B and three second condensing lenses 40B.

The branching element 126B branches the second laser beam L2 incident from the second light forming element 34 into three branches and emits the second laser beam L2 toward the three second condensing lenses 40B. The three second condenser lenses 40B are arranged in a row along the X direction (processing feed direction), and the second laser beam L2 incident from the branch element 126B is simultaneously collected on the street C (return path). Let it shine.

FIG. 28 is an explanatory diagram for explaining the effect of the laser processing apparatus 10 of the eighth embodiment. Reference numeral XXVIIIA in FIG. 28 indicates each laser beam (two first laser beams L1, second) focused on the street C during edge cutting and hollowing by the laser machining apparatus 10 of each of the above embodiments. It shows the movement of the spot SP of the laser beam L2). Further, reference numeral XXVIIIB in FIG. 28 indicates the movement of the spots SP1 to SP3 of each laser beam focused on the street C during edge cutting and hollowing by the laser processing apparatus 10 of the eighth embodiment.

As shown by reference numeral XXVIIIA in FIG. 28, the laser optical system 24 causes street C (outward and inbound) due to the relative movement of the laser optical system 24 to the outward direction side X1 or the inbound direction X2 during edge cutting and hollowing. ), The spot SP of the two first laser beams L1 and the spot SP of the second laser beam L2 move along the street C. At this time, if the moving speed of the relative movement of the laser optical system 24 is increased, the distance between the spots SP along the machining feed direction is increased, so that the bottom surface of the machining groove (two edge cutting groove 18 and the hollow groove 19) is formed. Unevenness will occur. Therefore, in each of the above embodiments, it is necessary to limit the relative movement speed of the laser optical system 24 so that the spots SP adjacent to each other in the processing feed direction partially overlap each other.

On the other hand, in the laser processing apparatus 10 of the eighth embodiment, a plurality of first condensing lenses 38 and second condensing lenses 40A and 40B are arranged along the processing feed direction, so that the reference numeral XXVIIIB in FIG. 28 can be obtained. As shown, the two first laser beams L1 and the second laser beam L2 can be focused on the street C (outward and return paths) at a plurality of points at the same time. Therefore, in the eighth embodiment, the two first laser beams L1 formed on the street C (outward and return) due to the relative movement of the laser optical system 24 to the outward direction side X1 or the return direction side X2. The three spots SP1, SP2, SP3 and the three spots SP1, SP2, SP3 of the second laser beam L2 move along the street C.

As described above, in the eighth embodiment, by increasing the number of spots for each laser machining, even when the moving speed of the relative movement of the laser optical system 24 is increased, the spots SP1 that are adjacent to each other in the machining feed direction SP2 and SP3 can be partially overlapped with each other. This makes it possible to form a machined groove having a stable shape. As a result, in the eighth embodiment, the tact time required for laser machining of the wafer 12 can be reduced as compared with each of the above embodiments.

In the eighth embodiment, the first condensing lens 38, the second condensing lens 40A, and the second condensing lens 40B are arranged three along the processing feed direction, but the number of arrangements is two. It may be 4 or more. Further, the first condenser lens group 120 and the second condenser lens groups 122A and 122B may be interchanged in the same manner as in the sixth embodiment (see FIGS. 21 and 22).

[9th Embodiment]
FIG. 29 is an explanatory diagram for explaining edge cutting and hollowing by the laser optical system 24 of the laser processing apparatus 10 of the ninth embodiment, which is relatively moved to the outward direction side X1 with respect to the wafer 12. FIG. 30 is an explanatory diagram for explaining edge cutting and hollowing by the laser optical system 24 of the laser processing apparatus 10 of the ninth embodiment, which is relatively moved to the return direction side X2 with respect to the wafer 12.

In each of the above embodiments, three types of first condenser lenses 38 (38A, 38B) and second condenser lenses 40A, 40B (40) are selectively used according to the relative movement direction of the laser optical system 24 with respect to the wafer 12. Laser processing is performed. On the other hand, as shown in FIGS. 29 and 30, in the ninth embodiment, laser processing is performed using the first condenser lens 38 and the second condenser lens 40. Then, in the ninth embodiment, the edge cutting process by the first condenser lens 38, the hollowing process by the second condenser lens 40, and the second condenser lens are performed according to the relative movement direction of the laser optical system 24 with respect to the wafer 12. The edge cutting process by 40 and the hollowing process by the first condenser lens 38 are switched.

The laser optical system 24 of the ninth embodiment includes a first condenser lens 38 and a second condenser lens 40 in place of the first condenser lens 38 and the second condenser lenses 40A and 40B, and has a connection switching element 36. The configuration is basically the same as that of the laser processing apparatus 10 of the first embodiment, except that the connection optical system 200 is provided instead of the above. Therefore, those having the same function or configuration as those of the first embodiment are designated by the same reference numerals and the description thereof will be omitted.

The first condenser lens 38 and the second condenser lens 40 are arranged in a row along the X direction (processing feed direction). The first condensing lens 38 is arranged on the outward direction side X1 with respect to the second condensing lens 40. The first condensing lens 38 condenses the two first laser beams L1 or the second laser beam L2 incident from the connection optical system 200 described later on the street C. Further, the second condensing lens 40 condenses the two first laser beams L1 or the second laser beam L2 incident from the connecting optical system 200 on the street C.

In the connection optical system 200, two first laser beams L1 emitted from the first light forming element 32 when the relative movement mechanism 28 moves the laser optical system 24 relative to the wafer 12 on the outward direction side X1. Is guided to the first condensing lens 38 and the second laser beam L2 emitted from the second light forming element 34 is guided to the second condensing lens 40 (see FIG. 29). On the contrary, in the connection optical system 200, when the relative movement mechanism 28 moves the laser optical system 24 relative to the wafer 12 on the return path side X2, the two first light forming elements 32 are emitted. The laser light L1 is guided to the second condensing lens 40, and the second laser light L2 emitted from the second light forming element 34 is guided to the first condensing lens 38 (see FIG. 30).

FIG. 31 is an explanatory diagram for explaining the function of the connection optical system 200 when the laser optical system 24 is relatively moved to the outward direction side X1 with respect to the wafer 12 by the relative movement mechanism 28. FIG. 32 is an explanatory diagram for explaining the function of the connection optical system 200 when the laser optical system 24 is relatively moved to the return direction side X2 with respect to the wafer 12 by the relative movement mechanism 28.

In FIGS. 31 and 32, the reference numeral PP1 indicates that the two first laser beams L1 are P-polarized, and the reference numeral SP1 indicates that the two first laser beams L1 are S-polarized. The reference numeral PP2 indicates that the second laser beam L2 is P-polarized, and the reference numeral SP2 indicates that the second laser beam L2 is S-polarized. Further, in the present embodiment, it is assumed that the two first laser beams L1 emitted from the first light forming element 32 and the second laser light L2 emitted from the second light forming element 34 are P-polarized, respectively. Give an explanation.

As shown in FIGS. 31 and 32, the connection optical system 200 includes a polarization beam splitter 202, a λ / 2 plate 204, a polarization beam splitter 206, a λ / 2 plate 208, and a polarization beam splitter 210, 212, λ / 2 plate 214. , And mirrors 220, 222.

The polarization beam splitter 202, the λ / 2 plate 204, and the polarization beam splitter 206 are arranged along the optical path from the first light forming element 32 to the first condenser lens 38. The λ / 2 plate 208, the polarization beam splitter 210, 212, and the λ / 2 plate 214 are arranged along the optical path from the second light forming element 34 to the second condensing lens 40. The mirror 220 is arranged on the optical path between the polarizing beam splitter 202 and the polarizing beam splitter 210. The mirror 222 is arranged on the optical path between the polarizing beam splitter 206 and the polarizing beam splitter 212.

Each of the polarization beam splitters 202, 206, 210, 212 transmits P-polarization and reflects S-polarization.

The λ / 2 plates 204, 208, 214 can be switched between a reference state in which P-polarization and S-polarization are transmitted without changing the polarization state, and a rotation state in which the optical axis is rotated by 45 degrees from this reference state. be. When the λ / 2 plates 204, 208, 214 are in a rotating state, the incident P-polarization is converted into S-polarization and the incident S-polarization is converted into P-polarization.

The mirror 220 guides the S polarization reflected by the polarization beam splitter 210 to the polarization beam splitter 202. Further, the mirror 222 guides the S polarization reflected by the polarization beam splitter 206 to the polarization beam splitter 212. The mirror 220 can be omitted when the polarizing beam splitters 202 and 210 are arranged to face each other in the X direction, and the mirror 222 is omitted when the polarizing beam splitters 206 and 212 are arranged to face each other in the X direction. It is possible.

As shown in FIG. 31, in the control device 30 (see FIG. 1) of the ninth embodiment, when laser processing of the street C (outward route) is performed, that is, the relative moving mechanism 28 transfers the laser optical system 24 to the wafer 12. When moving relative to the outward direction side X1, the λ / 2 plates 204, 208, and 214 are set to the reference states, respectively.

The two first laser beams L1 (P-polarized) emitted from the first light forming element 32 pass through the polarizing beam splitter 202, the λ / 2 plate 204, and the polarizing beam splitter 206 in order, and are first focused. It is guided to the lens 38. As a result, the two first laser beams L1 are focused on the street C (outward route) by the first condenser lens 38.

The second laser beam L2 (P-polarized light) emitted from the second light forming element 34 passes through the λ / 2 plate 208, the polarization beam splitters 210, 212, and the λ / 2 plate 214 in order, and is second focused. It is guided to the lens 40. As a result, the second laser beam L2 is focused on the street C (outward route) by the second condenser lens 40.

Similar to each of the above embodiments, the edge cutting process is executed in advance along the street C (outward path) due to the relative movement of the laser optical system 24 to the outward path direction side X1, and then the hollowing process is executed. Since the timing of emission and emission stop of the two first laser beams L1 and the second laser beam L2 during the laser processing of the street C (outbound route) is the same as that of the first embodiment, the specific timing is described here. The description will be omitted (the same applies to the tenth embodiment and the eleventh embodiment described later).

As shown in FIG. 32, in the control device 30 of the ninth embodiment, when laser processing of the street C (return path) is performed, that is, the relative movement mechanism 28 makes the laser optical system 24 relative to the wafer 12 on the return path direction side X2. When moving, the λ / 2 plates 204, 208, and 214 are set to the rotational state, respectively.

The two first laser beams L1 (P-polarized light) emitted from the first light forming element 32 are transmitted through the polarizing beam splitter 202 and then converted into S-polarized light by the λ / 2 plate 204. The two first laser beams L1 converted to S polarization are reflected by the polarizing beam splitter 206 toward the mirror 222, further reflected by the mirror 222, and incident on the polarizing beam splitter 212. The two first laser beams L1 (S-polarized light) incident on the polarizing beam splitter 212 were reflected by the polarizing beam splitter 212 toward the λ / 2 plate 214, and converted into P polarization by the λ / 2 plate 214. Later, it is guided to the second condenser lens 40. As a result, the two first laser beams L1 are focused on the street C (return path) by the second condenser lens 40.

The second laser beam L2 (P-polarized) emitted from the second photoforming element 34 is converted into S-polarized light by the λ / 2 plate 208, then reflected by the polarizing beam splitter 210 toward the mirror 220, and further. It is reflected by the mirror 220 and incident on the polarization beam splitter 202. The second laser beam L2 (S polarization) incident on the polarization beam splitter 202 is reflected by the polarization beam splitter 202 toward the λ / 2 plate 204, converted into P polarization by the λ / 2 plate 204, and then polarized. It passes through the beam splitter 206 and is guided to the first condenser lens 38. As a result, the second laser beam L2 is focused on the street C (return path) by the first condenser lens 38.

Similar to each of the above embodiments, the edge cutting process is executed in advance along the street C (return path) due to the relative movement of the laser optical system 24 to the return path side X2, and then the hollowing process is executed. The timing of emission and stop of emission of the two first laser beams L1 and the second laser beam L2 at the time of laser processing on the street C (return path) is the same as that of the first embodiment. The description will be omitted (the same applies to the tenth embodiment and the eleventh embodiment described later).

In the ninth embodiment, λ / in order to align the polarization states of the two first laser beams L1 that perform the edge cutting process of the street C (return path) with the same P polarization as that at the time of the edge cutting process of the street C (outward path). Although the two plates 214 are provided, the λ / 2 plate 214 may be omitted if it is not necessary to align the P polarization.

As described above, in the ninth embodiment, the edge cutting process using the first condenser lens 38 and the hollowing process using the second condenser lens 40 are performed according to the relative movement direction of the laser optical system 24 with respect to the wafer 12. It is possible to switch between the edge cutting process using the second condensing lens 40 and the hollowing process using the first condensing lens 38. As a result, the same effect as that of each of the above embodiments can be obtained.

[Variation example of the ninth embodiment]
<Modification 1>
FIG. 33 is an explanatory diagram for explaining edge cutting and hollowing by the laser optical system 24 which is relatively moved to the outward direction side X1 with respect to the wafer 12 in the first modification of the ninth embodiment. FIG. 34 is an explanatory diagram for explaining edge cutting and hollowing by the laser optical system 24 which is relatively moved to the return direction side X2 with respect to the wafer 12 in the first modification of the ninth embodiment.

In the ninth embodiment, two first laser beams L1 for edge cutting and a second laser beam L2 for hollowing are formed from the laser beam L emitted from the laser light source 22. On the other hand, as shown in FIGS. 33 and 34, in the modified example 1 of the ninth embodiment, the first laser corresponding to the edge cutting process is supported as in the fourth embodiment (see FIGS. 13 and 14). The light source 22A and the second laser light source 22B corresponding to the hollowing process are separately provided. Those having the same function or configuration as the fourth embodiment are designated by the same reference numerals and the description thereof will be omitted.

As described above, in the first modification of the ninth embodiment, the first laser light source 22A corresponding to the edge cutting process and the second laser light source 22B corresponding to the hollowing process are separately provided, as in the fourth embodiment. In addition, since the reductions in the processing speeds of the edge cutting process and the hollowing process are prevented, the tact time can be further reduced.

<Modification 2>
FIG. 35 is an explanatory diagram for explaining edge cutting and hollowing by the laser optical system 24 which is relatively moved to the outward direction side X1 with respect to the wafer 12 in the second modification of the ninth embodiment. FIG. 36 is an explanatory diagram for explaining edge cutting and hollowing by the laser optical system 24 which is relatively moved to the return direction side X2 with respect to the wafer 12 in the second modification of the ninth embodiment.

As shown in FIGS. 35 and 36, in the second modification of the ninth embodiment, even if one of the first laser light source 22A and the second laser light source 22B has a defect in the first modification, the wafer 12 is provided with a defect. It has a function to continue laser processing. Specifically, the second modification of the ninth embodiment is provided with bypass optical systems 72 and 74, as in the fifth embodiment (see FIGS. 18 and 19). Those having the same function or configuration as the fifth embodiment are designated by the same reference numerals and the description thereof will be omitted.

As described above, in the second modification of the ninth embodiment, by providing the bypass optical systems 72 and 74, one of the first laser light source 22A and the second laser light source 22B has a defect as in the fourth embodiment. Even if it occurs, the laser processing of the wafer 12 can be continued.

<Others>
Also in the ninth embodiment, similarly to the second embodiment (see FIGS. 8 to 11), the width of the edge cutting groove 18 of the two articles is adjusted by the first rotation mechanism 44, and the second rotation mechanism 46 is used to adjust the width of the edge cutting groove 18. 2 The width of the laser beam L2 may be adjusted.

Further, also in the ninth embodiment, as in the third embodiment (see FIG. 12), the spots of the two first laser beams L1 and the second laser beam L1 are used by using the mirrors 37, 39B, the moving mechanisms 48, 49B and the like. 2 The position of the spot of the laser beam L2 in the Y direction may be adjustable.

Further, the configurations of the 7th embodiment and the 8th embodiment may be appropriately combined with the 9th embodiment (including the first and second modifications).

[10th Embodiment]
FIG. 37 is an explanatory diagram for explaining edge cutting and hollowing by the laser optical system 24 of the laser processing apparatus 10 of the tenth embodiment. In the ninth embodiment, the edge cutting process using the first condenser lens 38, the hollowing process using the second condenser lens 40, and the second collection are performed according to the relative movement direction of the laser optical system 24 with respect to the wafer 12. The edge cutting process using the optical lens 40 and the hollowing process using the first condensing lens 38 are switched. On the other hand, in the tenth embodiment, the edge cutting process is performed in the same manner as in the ninth embodiment, and the hollowing process is performed using both the first condenser lens 38 and the second condenser lens 40.

Since the laser optical system 24 of the tenth embodiment has basically the same configuration as the laser processing apparatus 10 of the ninth embodiment except that the functions of the λ / 2 plate 208 are partially different, the ninth embodiment is described above. Those having the same form and function or configuration are designated by the same reference numerals and the description thereof will be omitted.

The λ / 2 plate 208 of the tenth embodiment is set to a half-rotation state rotated by 22.5 degrees from the reference angle state by the above-mentioned control device 30. In the half-rotation state, the λ / 2 plate 208 rotates the polarization direction of the second laser beam L2 by 45 degrees when the second laser beam L2 (P-polarized light) is incident from the second light forming element 34.

The polarization beam splitter 210 of the tenth embodiment transmits the P polarization component of the second laser beam L2 that has passed through the λ / 2 plate 208 in the half-rotation state and emits the light toward the polarization beam splitter 212, and S. The polarization component is reflected toward the mirror 220. As a result, the second laser beam L2 is split into two by the polarization beam splitter 210. The second laser beam L2 (P-polarized light) transmitted through the polarizing beam splitter 210 is transmitted through the polarizing beam splitter 212 and the λ / 2 plate 214 and guided to the second condenser lens 40.

On the other hand, the second laser beam L2 (S-polarized light) reflected by the polarizing beam splitter 210 is reflected by the mirror 220 and incident on the polarizing beam splitter 202. Then, the second laser beam L2 (S polarization) is reflected toward the λ / 2 plate 204 by the polarization beam splitter 202, converted into P polarization by the λ / 2 plate 204, and then transmitted through the polarization beam splitter 206. Then, it is guided to the first condenser lens 38. As a result, the second laser beam L2 is focused on the street C (return path) by both the first condenser lens 38 and the second condenser lens 40.

Due to the relative movement of the laser optical system 24 to the return path side X2, the edge cutting process and the hollowing process are executed in advance by the second condenser lens 40 along the street C (return path), so that the edge cutting groove 18 of the two rows is performed. The hollow groove 19 is formed in advance, and then the hollow groove 19 is formed again on the previous hollow groove 19 by performing the hollow processing by the first condenser lens 38. This makes it possible to improve the overlap rate of the spots of the second laser beam L2 adjacent to each other in the processing feed direction.

When the laser optical system 24 is relatively moved to the outward direction side X1, the second laser beam L2 (S-polarized light) reflected by the polarizing beam splitter 202 is incident on the polarizing beam splitter 206. It is necessary to convert to P polarization. In this case, for example, the λ / 2 plate (rotational state) is temporarily arranged only on the optical path of the second laser beam L2 between the polarizing beam splitter 202 and the polarizing beam splitter 206. As a result, due to the relative movement of the laser optical system 24 toward X1 on the outward path direction, edge cutting and hollowing are performed in advance by the first condenser lens 38 along the street C (outward path), followed by the second collection. Hollowing is performed by the optical lens 40.

As described above, in the tenth embodiment, the edge cutting process and the hollowing process by either the first condenser lens 38 or the second condenser lens 40 are performed according to the relative movement direction of the laser optical system 24 with respect to the wafer 12. , Pseudo three-point simultaneous processing including hollowing processing by the other of the first condensing lens 38 and the second condensing lens 40 can be performed. As a result, the overlap rate of the spots of the second laser beam L2 on the street C can be improved.

In order to improve the overlap rate of the spots of the two first laser beams L1 on the street C, instead of setting the λ / 2 plate 208 to the half rotation state, the λ / 2 plate 204 is half. Set to the rotating state. As a result, the λ / 2 plate 204 divides the two first laser beams L1 (P-polarized light) incident from the polarizing beam splitter 202 into two, P-polarized and S-polarized, and emits them toward the polarized beam splitter 206. As a result, the P polarization of the two first laser beams L1 is guided to the first condenser lens 38, and the S polarization is guided to the polarization beam splitter 212 (second condenser lens 40).

Therefore, depending on the relative movement direction of the laser optical system 24 with respect to the wafer 12, the edge cutting process by either the first condensing lens 38 or the second condensing lens 40 and the first condensing lens 38 and the second condensing lens 40 are performed. It is possible to perform pseudo three-point simultaneous processing including edge cutting processing and hollow processing by the other side of the lens 40. As a result, the overlap rate of the spots of the two first laser beams L1 on the street C can be improved.

<Modification example>
Also in the tenth embodiment, the configurations of the second to eighth embodiments may be appropriately combined in the same manner as in the ninth embodiment (including the first and second modifications).

[11th Embodiment]
FIG. 38 is an explanatory diagram for explaining edge cutting and hollowing by the laser optical system 24 of the laser processing apparatus 10 of the eleventh embodiment, which is relatively moved to the outward direction side X1 with respect to the wafer 12. FIG. 39 is an enlarged view of the dotted circle K1 in FIG. 38. FIG. 40 is an explanatory diagram for explaining edge cutting and hollowing by the laser optical system 24 of the laser processing apparatus 10 of the eleventh embodiment, which is relatively moved to the return direction side X2 with respect to the wafer 12. FIG. 41 is an enlarged view of the dotted circle K2 in FIG. 40.

In each of the above embodiments, edge cutting and hollowing are performed using a plurality of various lenses while the laser optical system 24 is relatively moved to the outward direction side X1 and the inbound direction side X2 with respect to the wafer 12. On the other hand, in the eleventh embodiment, the laser optical system 24 is moved relative to the outward path side X1 and the return path direction side X2 with respect to the wafer 12, and the edge cutting process is performed using only one first condensing lens 38. And perform hollowing.

As shown in FIGS. 38 to 41, the laser optical system 24 of the eleventh embodiment includes a first condensing lens 38 and a connection optical system 200A, and the first light forming element 32 has two first laser beams. The configuration is basically the same as that of the laser processing apparatus 10 of each of the above-described embodiments, except that L1 (S-polarized light) is generated and the second light forming element 34 generates the second laser light L2 (P-polarized light). .. Therefore, those having the same function or configuration as each of the above embodiments are designated by the same reference numerals, and the description thereof will be omitted.

The first condensing lens 38 of the eleventh embodiment condenses the two first laser beams L1 and the second laser beam L2 incident from the connection optical system 200A described later on the street C. The reference numeral OP in FIGS. 39 and 41 indicates the optical axis of the first condensing lens 38, the reference numeral SPA indicates the spots of the two first laser beams L1, and the reference numeral SPB indicates the spot of the second laser beam L2. Is shown.

In the connection optical system 200A, the two first laser beams L1 emitted from the first light forming element 32 and the second laser light L2 emitted from the second light forming element 34 are combined with the first condenser lens 38. Guide. At this time, in the connection optical system 200A, when the relative movement mechanism 28 moves the laser optical system 24 relative to the wafer 12 on the outward direction side X1, the spot SPA of the two first laser beams L1 is second. The spot SPB of the laser beam L2 is shifted relative to the outward direction side X1. On the contrary, in the connection optical system 200A, when the relative movement mechanism 28 moves the laser optical system 24 relative to the wafer 12 on the return direction side X2, the spot SPA of the two first laser beams L1 is second. The spot SPB of the laser beam L2 is shifted relative to the return direction side X2.

The connection optical system 200A includes a shift element 230, a mirror 232, and a polarization beam splitter 234.

The shift element 230 and the mirror 232 are arranged on the optical path from the first light forming element 32 to the polarizing beam splitter 234.

The shift element 230 is composed of, for example, a plurality of prisms (shift prisms) or a plurality of mirrors, and after shifting the two first laser beams L1 incident from the first light forming element 32 in the X direction, the shift element 230 is formed. The two first laser beams L1 are emitted toward the mirror 232 located on the lower side in the Z direction. By rotating the shift element 230 around the Z axis, the shift directions of the two first laser beams L1 can be arbitrarily adjusted. When the shift element 230 is set at the first angle position in the Z-axis axial direction, the shift element 230 shifts the two first laser beams L1 to the outward direction side X1 and rotates 180 degrees from the first angle position. When set at two angle positions, the two first laser beams L1 are shifted to the return direction side X2.

The mirror 232 guides the two first laser beams L1 incident from the shift element 230 to the polarizing beam splitter 234.

The polarization beam splitter 234 is arranged on the optical path from the second light forming element 34 to the first condensing lens 38. The polarized beam splitter 234 reflects the two first laser beams L1 (S-polarized light) incident from the mirror 232 toward the first condenser lens 38, and the second laser incident from the second light forming element 34. Light L2 (P-polarized light) is transmitted and emitted to the first condenser lens 38. As a result, the two first laser beams L1 and the second laser beam L2 are focused on the street C by the first condenser lens 38.

As shown in FIGS. 38 and 39, in the control device 30 of the eleventh embodiment, when laser processing of the street C (outward path) is performed, that is, the relative moving mechanism 28 moves the laser optical system 24 with respect to the wafer 12 in the outward path direction. When moving relative to the side X1, the shift element 230 is set at the first angle position. As a result, on the street C (outward route), the spot SPAs of the two first laser beams L1 are shifted to the outward route direction X1 with respect to the spot SPB of the second laser beam L2. As a result, as in each of the above embodiments, the edge cutting process is executed in advance along the street C (outward path) due to the relative movement of the laser optical system 24 to the outward path direction side X1, and then the hollowing process is executed. Ru.

As shown in FIGS. 40 and 41, in the control device 30 of the eleventh embodiment, when laser processing of the street C (return path) is performed, that is, the relative movement mechanism 28 moves the laser optical system 24 with respect to the wafer 12 in the return path direction. When moving relative to the side X2, the shift element 230 is set at the second angle position. As a result, on the street C (return path), the spot SPAs of the two first laser beams L1 are shifted to the return path direction X2 with respect to the spot SPB of the second laser beam L2. As a result, as in each of the above embodiments, the edge cutting process is executed in advance along the street C (return path) due to the relative movement of the laser optical system 24 to the return path side X2, and then the hollowing process is executed. Ru.

As described above, in the eleventh embodiment, the shift element 230 shifts the two first laser beams L1 relative to the second laser beam L2 in the processing feed direction side, whereby one first collection is obtained. The optical lens 38 can perform edge cutting and hollowing of street C (outward and inbound). As a result, the same effect as that of each of the above embodiments can be obtained.

<Modification example>
In the eleventh embodiment, the two first laser beams L1 (spot SPA) are shifted by the shift element 230, but the second laser beam L2 (spot SPB) is shifted to the side opposite to the processing feed direction. You may let me.

FIG. 42 is an explanatory diagram for explaining a modified example of the eleventh embodiment. As shown by the reference numerals XLIIA and the reference numeral XLIIB in FIG. 42, in the eleventh embodiment as well as in the second embodiment (see FIGS. 8 to 11), the first rotation mechanism 44 allows the two edge cutting grooves 18 to be formed. The width may be adjusted, or the width of the second laser beam L2 may be adjusted by the second rotation mechanism 46.

Further, also in the eleventh embodiment, the configurations of the fourth embodiment, the fifth embodiment, the seventh embodiment, and the eighth embodiment may be appropriately combined.

[others]
In each of the above embodiments, the safety shutters 100, 100A, and 100B are inserted and removed on the optical path to switch off / on of the edge cutting process and the hollowing process, but the laser light source 22 (first laser light source 22A and second laser) is switched. By turning the light source 22B) on and off, the edge cutting process and the hollowing process may be switched on and off.

[Additional Notes]
As can be seen from the description of the embodiments detailed above, the present specification includes disclosure of various technical ideas including the inventions shown below.

(Appendix 1)
To irradiate the wafer with laser light from the laser optical system while relatively moving the table holding the wafer and the laser optical system arranged at a position facing the table in the machining feed direction along the street of the wafer. The edge cutting process for forming the first groove of the two rows parallel to each other along the street and the hollowing process for forming the second groove between the first grooves of the two rows are performed for each street. In laser processing equipment
The laser optical system
A laser light emitting system that emits two first laser beams corresponding to the edge cutting process and a second laser beam corresponding to the hollowing process.
A condensing optical system that concentrates the two first laser beams and the second laser beam on the street to be processed, and
Equipped with
When the condensing optical system moves relative to the table in the outward path direction of the processing feed direction, the two first laser beams are directed to the second laser beam. When the laser optical system is focused on the street at a position relatively shifted toward the outward path direction and the laser optical system is relatively moved toward the return path direction in the processing feed direction with respect to the table, the above 2). A laser processing device that focuses the first laser beam of a book on the street at a position relatively shifted toward the return path side with respect to the second laser beam.

(Appendix 2)
The condensing optical system
A first condensing lens that condenses the two first laser beams on the wafer, and
Two second condensing lenses arranged in a row along with the first condensing lens with the first condensing lens sandwiched between them, and the second condensing lens is described for each second condensing lens. Two second condensing lenses that condense the second laser beam on the wafer, and
The two first laser beams emitted from the laser light emitting system are guided to the first focusing lens, and the second laser light emitted from the laser light emitting system is directed to the two second focusing lenses. The connection optical system that selectively guides the lens,
Equipped with
When the laser optical system is relatively moved toward the outward path side with respect to the table, the connecting optical system positions the second laser beam on the return path direction side with respect to the first condenser lens. When the laser optical system is guided to the second condenser lens and the laser optical system is relatively moved toward the return path side with respect to the table, the second laser beam is directed to the outward path direction with respect to the first condenser lens. The laser processing apparatus according to Supplementary Item 1, which leads to the second condenser lens located on the side.

(Appendix 3)
The condensing optical system
Two first condensing lenses arranged in a row along the processing feed direction, and two first condensing lenses for condensing the two first laser beams on the wafer for each first condensing lens. 1 condenser lens and
A second condenser lens arranged between the two first condenser lenses, the second condenser lens that concentrates the second laser beam on the wafer, and the second condenser lens.
The two first laser beams emitted from the laser beam emitting system are selectively guided to the two first focusing lenses, and the second laser beam emitted from the laser beam emitting system is referred to as the first laser beam. 2 The connection optical system that leads to the condenser lens and
Equipped with
When the connecting optical system moves the laser optical system relative to the table in the outward path direction, the two first laser beams are directed to the outward path direction side with respect to the second condenser lens. When the laser optical system is moved relative to the table in the return path direction, the two first laser beams are transferred to the second condenser lens. The laser processing apparatus according to Supplementary Item 1, which leads to the first condensing lens located on the return path side.

(Appendix 4)
The condensing optical system
Two condenser lenses arranged in a row along the processing feed direction, and
A connecting optical system that guides the two first laser beams and the second laser beam emitted from the laser beam emitting system to the condenser lens.
Equipped with
When the connecting optical system moves the laser optical system relative to the outward path side with respect to the table, the two first laser beams are guided to the condenser lens on the outward path direction side and said. When the second laser beam is guided to the condenser lens on the return path direction and the laser optical system is relatively moved toward the return path direction with respect to the table, the two first laser beams are transferred to the return path. The laser processing apparatus according to Appendix 1, which guides the condensing lens on the direction side and guides the second laser beam to the condensing lens on the outward direction side.

(Appendix 5)
Item 4. The appendix 4 wherein the connecting optical system divides one of the two first laser beams and the second laser beam into two and guides the one to both of the two condenser lenses. Laser processing equipment.

(Appendix 6)
The condensing optical system
Condensing lens and
A connecting optical system that guides the two first laser beams and the second laser beam emitted from the laser beam emitting system to the condenser lens.
Equipped with
When the connecting optical system moves the laser optical system relative to the table in the outward path direction, the second laser beam is directed to the return path side with respect to the two first laser beams. When the laser optical system is relatively shifted and the laser optical system is relatively moved toward the return path side with respect to the table, the second laser beam is directed to the outward path direction side with respect to the two first laser beams. Item 2. The laser processing apparatus according to Item 1, further comprising a shift element that shifts relative to.

(Appendix 7)
A first moving mechanism that moves the first condenser lens in a vertical direction parallel to the table and perpendicular to the processing feed direction.
A second moving mechanism that moves the second condenser lens in the vertical direction,
2. The laser processing apparatus according to Supplementary Item 2 or 3.

(Appendix 8)
The laser processing apparatus according to annex 4 or 5, further comprising a moving mechanism for moving the condenser lens in a vertical direction parallel to the table and perpendicular to the processing feed direction.

(Appendix 9)
The laser light emitting system
A laser light source that emits laser light and
A branching element that bifurcates the laser beam emitted from the laser light source, and
A first light forming element that forms the two first laser beams from one of the laser beams branched into two by the branching element.
A second light forming element that forms the second laser beam from the other side of the laser beam branched into two by the branching element.
The laser processing apparatus according to any one of Supplementary Items 1 to 8.

(Appendix 10)
The laser light emitting system
A first laser light source that emits a laser beam under the conditions corresponding to the edge cutting process,
A second laser light source that emits a laser beam under the conditions corresponding to the hollowing process, and
A first light forming element that forms the two first laser beams from the laser light emitted from the first laser light source.
A second light forming element that forms the second laser beam from the laser beam emitted from the second laser light source, and
The laser processing apparatus according to any one of Supplementary Items 1 to 8.

(Appendix 11)
When a problem occurs in the first laser light source, the laser light emitted from the second laser light source is branched into two and emitted to the first light forming element and the second light forming element, and the second one. Appendix 10 comprising a bypass optical system that branches the laser light emitted from the first laser light source into two and emits the laser light to the first light forming element and the second light forming element when a defect occurs in the laser light source. The laser processing apparatus described in.

(Appendix 12)
The laser processing apparatus according to any one of Items 9 to 11, further comprising a first rotation mechanism for rotating the first light forming element in a direction around an axis about the optical axis of the first light forming element.

(Appendix 13)
The second light forming element forms the second laser beam that forms a non-circular spot on the wafer.
A second rotation mechanism that rotates the second light forming element in a direction around the axis centered on the optical axis of the second light forming element.
The laser processing apparatus according to any one of Supplementary Items 9 to 12.

(Appendix 14)
When the directions parallel to the table and orthogonal to each other are the first direction and the second direction, the second light forming element has a top hat-shaped intensity distribution in the first direction and the second direction. The laser processing apparatus according to any one of Supplementary Items 9 to 13, which forms the second laser beam having a Gaussian-shaped intensity distribution in the above.

(Appendix 15)
The condensing optical system
A group of first condensing lenses in which a plurality of first condensing lenses for condensing the two first laser beams on the wafer are arranged along the processing feed direction.
Two sets of second condensing lenses arranged in a row along with the first condensing lens group with the first condensing lens group sandwiched between them, the second condensing lens. A second condenser lens group in which a plurality of second condenser lenses for condensing the second laser beam on the wafer are arranged along the processing feed direction for each group.
The two first laser beams emitted from the laser light emitting system are guided to the first condenser lens group, and the second laser light emitted from the laser light emitting system is combined with two sets of the second collection. A connection optical system that selectively guides the optical lens group,
Equipped with
When the laser optical system is relatively moved toward the outward path side with respect to the table, the connecting optical system positions the second laser beam on the return path direction side with respect to the first condenser lens group. When the laser optical system is relatively moved toward the return path side with respect to the table, the second laser beam is directed to the first condenser lens group. Item 2. The laser processing apparatus according to Supplementary Item 1, which leads to the second condenser lens group located on the outward path direction side.

10 Laser processing equipment 12 Wafer 14 Chip 16 Device 18 Edge cutting groove 19 Drilling groove 20 Table 22 Laser light source 22A First laser light source 22B Second laser light source 24 Laser optical system 26 Microscope 28 Relative movement mechanism 30 Control device 31 Branch element 32 No. 1 Optical forming element 34 2nd optical forming element 36 Connection switching element 37 Mirror 38, 38A, 38B 1st condensing lens 39A, 39B Mirror 40, 40A, 40B 2nd condensing lens 44 1st rotation mechanism 46 2nd rotation mechanism 47A 1st high-speed shutter 47B 2nd high-speed shutter 47C High-speed shutter drive mechanism 48, 49A, 49B Movement mechanism 52 λ / 2 plate 53 Plate rotation mechanism 54 Polarization beam splitter 58 Half mirror 60 Mirror 62A, 62B Shutter 64 Shutter drive mechanism 66A, 66B Mirror 68 Mirror drive mechanism 72,74 Bypass optical system 100 Safety shutter 100A First safety shutter 100B Second safety shutter 102,102A Safety shutter drive mechanism 110 Blade 120 First condenser lens group 120A, 120B, 122A, 122B Second Condensing lens group 124,126A, 126B Branching element 200,200A Connecting optical system 202 Splitting beam splitter 204 2 plates 206 Splitting beam splitter 208 λ / 2 plates 210, 212 Polarizing beam splitter 214 λ / 2 plates 220, 222 Mirror 230 shift Element 232 Mirror 234 Polarization beam splitter C Street L Laser light L1 First laser light L2 Second laser light LA, LB Laser light SP, SP1, SP2, SP3, SPA, SPB Spot X1 Outward route side X2 Inbound route side

Claims (1)

To irradiate the wafer with laser light from the laser optical system while relatively moving the table holding the wafer and the laser optical system arranged at a position facing the table in the machining feed direction along the street of the wafer. The edge cutting process for forming the first groove of the two rows parallel to each other along the street and the hollowing process for forming the second groove between the first grooves of the two rows are performed for each street. In laser processing equipment
The laser optical system
A laser light emitting system that emits two first laser beams corresponding to the edge cutting process and a second laser beam corresponding to the hollowing process.
Two condenser lenses arranged in a row along the processing feed direction, and
When the laser optical system is relatively moved toward the outward path side in the processing feed direction with respect to the table, the two first laser beams are guided to the condenser lens on the outward path direction side and the second laser beam is directed to the condenser lens. When the laser beam is guided to the condenser lens on the return path side in the processing feed direction and the laser optical system is relatively moved toward the return path direction with respect to the table, the two first laser beams are emitted. A connecting optical system that guides the second laser beam to the condenser lens on the return direction side and guides the second laser beam to the condenser lens on the outward path direction side.
Equipped with
Further, the connecting optical system divides one of the two first laser beams and the second laser beam into two, and guides the one to both of the two condenser lenses.

Images