JP7775082B2 - Laser processing auxiliary tool, laser processing device, and laser processing method - Google Patents

Description

The present invention relates to a laser processing auxiliary tool, a laser processing device, and a laser processing method.

A laser processing device is known that irradiates a target object having multiple functional elements formed on its surface with laser light to form a modified region in the target object for cutting the target into individual functional elements. In such laser processing devices, tape (so-called backgrind tape) may be attached to the surface of the target object and held in place by a frame, and laser light may be incident on the target object from its back side. Compared to laser processing methods in which laser light is incident on the target object from its surface, where multiple functional elements are formed, laser processing methods in which laser light is incident on the target object from its back side have the advantages of "laser light irradiation is less affected by films and structures formed in the street regions (regions between multiple functional elements) on the target object's surface, as well as by the width of the street regions," and "the straightness of cracks from the modified region to the street regions is improved."

However, if the functional element has a fragile structure, there is a risk that the functional element may be damaged by applying tape to the surface of the target object. Furthermore, when placed on the suction table (also known as the chuck table) of the laser processing device, a suction effect is generated on the surface of the target object via the tape, and the suction effect of the suction table may also damage the functional element.

In response, a laser processing device has been proposed that holds the frame while tape is attached to the back surface of the object and held by the frame, and supports only the outer edge area of the surface of the object where multiple functional elements are not formed (see, for example, Patent Document 1).

JP 2010-29927 A

However, if processing is performed while supporting only the outer edge region of the object's surface, where multiple functional elements are not formed, deformation and positional deviation in the object may become significant during processing, making it impossible to properly form a modified region in the desired position on the object.

The present invention aims to provide a laser processing auxiliary tool, laser processing device, and laser processing method that can accurately form modified regions on an object while preventing damage to multiple functional elements formed on the surface side of the object, even if the functional elements have a fragile structure.

The laser processing aid of the present invention is a laser processing aid used in a laser processing device that irradiates a target object having multiple functional elements formed on its surface with laser light, thereby forming modified regions in the target object along each of multiple lines that are set to pass between the multiple functional elements.The laser processing device includes a support unit that supports the target object, an irradiation unit that irradiates the target object with laser light, and a control unit that controls at least one of the support unit and the irradiation unit so that the focal point of the laser light moves relatively along each of the multiple lines. The laser processing aid of the present invention comprises: a first sheet that is placed on a suction table included in the support unit and on which the object is placed when a tape that is transparent to laser light is attached to the back surface of an object and the tape is held by a frame, and the frame is held by a holding unit included in the support unit so that laser light is incident on the object from the back surface side through the tape; and a second sheet that is placed on the suction table in the above case and is located lower than the back surface of the object placed on the first sheet, causing the suction action of the suction table to occur in an intermediate portion of the tape between the object and the frame, and the suction action of the suction table that is caused on the object by the first sheet is weaker than the suction action of the suction table that is caused in the intermediate portion by the second sheet.

In the laser processing auxiliary tool, the frame is held by the holding unit so that laser light is incident on the object from the back side through the tape, and the object is placed on the first sheet with the front side facing the first sheet. The second sheet is then positioned lower than the back side of the object, causing the suction table to apply suction to the middle portion of the tape. This causes the elastic force of the tape to press the object against the suction table, thereby minimizing deformation and misalignment of the object and enabling the precise formation of a modified region on the object. Furthermore, tape does not need to be applied to the surface of the object, and the suction table effect on the object by the first sheet is weaker than the suction table effect on the middle portion of the tape by the second sheet. This prevents damage to multiple functional elements formed on the front side of the object, even if the functional elements have a fragile structure. As described above, the laser processing auxiliary tool allows the precise formation of a modified region on the object while minimizing damage to multiple functional elements formed on the front side of the object, even if the functional elements have a fragile structure.

In the laser processing aid of the present invention, the first sheet may be laminated to the second sheet so that the outer edge of the first sheet is located inside the outer edge of the second sheet. Alternatively, the second sheet may extend along the outer edge of the first sheet. This allows the laser processing aid to be easily constructed.

In the laser processing aid of the present invention, the adhesive strength of the tape to the second sheet may be lower than the adhesive strength of the tape to the suction table. This makes it possible to easily peel the middle portion of the tape from the second sheet after processing.

In the laser processing aid of the present invention, each of the multiple functional elements may be a MEMS device. In this case, a laser processing aid that can prevent damage to the multiple functional elements formed on the surface side of the object is particularly effective.

The laser processing device of the present invention irradiates a target object having multiple functional elements formed on its front surface with laser light, thereby forming modified regions in the target object along multiple lines that are set to pass between the multiple functional elements. The device includes: a support unit that supports the target object, with a tape that is transparent to laser light attached to the back surface of the target object and the tape held by a frame, so that the laser light is incident on the target object from the back surface via the tape; an irradiation unit that irradiates the target object with laser light; and a control unit that controls at least one of the support unit and the irradiation unit so that the focal point of the laser light moves relatively along each of the multiple lines. The support unit includes a holder that holds the frame, a placement unit on which the target object is placed, and a suction unit that applies suction to an intermediate portion of the tape between the target object and the frame at a position lower than the back surface of the object placed on the placement unit, and the suction effect applied to the target by the placement unit is weaker than the suction effect applied to the intermediate portion by the suction unit.

The laser processing method of the present invention is a laser processing method used in a laser processing device that irradiates a target object having multiple functional elements formed on its surface side with laser light, thereby forming modified regions in the target object along each of multiple lines that are set to pass between the multiple functional elements.The laser processing device includes a support unit that supports the target object, an irradiation unit that irradiates the target object with laser light, and a control unit that controls at least one of the support unit and the irradiation unit so that the focal point of the laser light moves relatively along each of the multiple lines. The laser processing method of the present invention comprises: a first step in which a tape that is transparent to laser light is attached to the back surface of an object and the tape is held by a frame; a second step in which a holding section included in a support section holds the frame so that laser light is incident on the object from the back surface side through the tape, and the object is placed on a mounting section included in the support section, and a suction section included in the support section generates a suction effect on an intermediate portion of the tape between the object and the frame at a position lower than the back surface of the object placed on the mounting section; and a third step in which a control unit controls at least one of the support section and the irradiation section so that the focal point moves relatively along each of a plurality of lines, and in the second step, the suction effect generated on the object by the mounting section is weaker than the suction effect generated on the intermediate portion by the suction section.

In the above laser processing apparatus and laser processing method, the frame is held by the holding unit so that laser light is incident on the object from the back side via the tape, and the object is placed on the placing unit with the front side of the object facing the placing unit. The suction unit then applies suction to the middle portion of the tape at a position lower than the back side of the object. This causes the elastic force of the tape to press the object toward the placing unit, thereby suppressing deformation and misalignment of the object and accurately forming a modified region in the object. Furthermore, there is no need to apply tape to the surface of the object, and the suction applied to the object by the placing unit is weaker than the suction applied to the middle portion of the tape by the suction unit. This prevents damage to multiple functional elements formed on the front side of the object, even if the functional elements have a fragile structure. As described above, the above laser processing apparatus and laser processing method allow for accurate formation of a modified region in the object while suppressing damage to multiple functional elements formed on the front side of the object, even if the functional elements have a fragile structure.

The present invention makes it possible to provide a laser processing auxiliary tool, laser processing device, and laser processing method that can accurately form modified regions in an object while preventing damage to multiple functional elements formed on the surface side of the object, even if the functional elements have a fragile structure.

1 is a configuration diagram of a laser processing apparatus according to an embodiment; 2 is a perspective view of an object unit attached to a support portion of the laser processing apparatus shown in FIG. 1; FIG. 2 is a configuration diagram of a support portion and a laser processing auxiliary tool of the laser processing apparatus shown in FIG. 1 . 2 is a configuration diagram of a support portion and a laser processing auxiliary tool of the laser processing apparatus shown in FIG. 1 . 2 is a configuration diagram of a support portion and a laser processing auxiliary tool of the laser processing apparatus shown in FIG. 1 . 2 is a configuration diagram of a support portion and a laser processing auxiliary tool of the laser processing apparatus shown in FIG. 1 . FIG. 2 is a structural diagram of a portion of an expanding device. 10 is a graph showing the amount of displacement of the rear surface of an object. 1 is a photograph showing the state of a modified region formed on an object. FIG. 10 is a configuration diagram of a modified laser processing auxiliary tool. 10A and 10B are configuration diagrams of a support portion of a modified example and a laser processing auxiliary tool of a modified example. FIG. 10 is a configuration diagram of a support portion according to a modified example. FIG. 10 is an exploded perspective view of a modified target unit.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In each drawing, the same or corresponding parts are designated by the same reference numerals, and duplicated explanations will be omitted.
[Configuration of laser processing device]

As shown in FIG. 1, the laser processing device 1 includes a support unit 2, an irradiation unit 3, and a control unit 4. The support unit 2 supports an object 11. In this embodiment, the support unit 2 is movable along both the X and Y directions. The support unit 2 is also rotatable around an axis parallel to the Z direction. As an example, the X direction is a first horizontal direction, the Y direction is a second horizontal direction perpendicular to the first horizontal direction, and the Z direction is a vertical direction.

The irradiation unit 3 irradiates the object 11 with laser light L. The irradiation unit 3 includes a light source 31, a spatial light modulator 32, and a condenser lens 33. The light source 31 outputs laser light L that is transparent to the object 11, for example, using a pulse oscillation method. The spatial light modulator 32 modulates the laser light L output from the light source 31. The spatial light modulator 32 is, for example, a reflective liquid crystal (LCOS: Liquid Crystal on Silicon) spatial light modulator (SLM). The condenser lens 33 condenses the laser light L modulated by the spatial light modulator 32. In this embodiment, the irradiation unit 3 is movable along the Z direction. The position of the condenser lens 33 in the Z direction is fine-tuned by a piezoelectric element (not shown) based on displacement data of the laser light incident surface of the object 11 acquired by a distance measurement sensor (not shown).

When laser light L is focused inside the object 11 supported by the support portion 2, the laser light L is particularly absorbed in the area corresponding to the focal point C of the laser light L, forming a modified region M inside the object 11. The modified region M is an area whose density, refractive index, mechanical strength, and other physical properties differ from those of the surrounding unmodified region. Examples of modified regions M include melt-treated regions, crack regions, dielectric breakdown regions, and refractive index change regions.

As an example, when the support part 2 is moved along the X direction and the focal point C is moved along the X direction relative to the object 11, multiple modified spots are formed in a row along the X direction. One modified spot is formed by irradiating one pulse of laser light L. A row of modified regions M is a collection of multiple modified spots lined up in a row. Adjacent modified spots may be connected to each other or separated from each other, depending on the relative movement speed of the focal point C with respect to the object 11 and the repetition frequency of the laser light L.

The control unit 4 controls the support unit 2, the light source 31, the spatial light modulator 32, and the condenser lens 33. The control unit 4 is configured as a computer device including a processor, memory, storage, a communication device, etc. In the control unit 4, software (programs) loaded into the memory, etc. are executed by the processor, and the processor controls the reading and writing of data in the memory and storage, as well as communication by the communication device. In this way, the control unit 4 realizes various functions.
[Configuration of object unit]

As shown in FIG. 2, the object unit 10 includes an object 11, a tape 14, and a frame 15. The object 11 includes a substrate 12 and multiple functional elements 13. The multiple functional elements 13 are formed on the surface 11a of the object 11. In this embodiment, the multiple functional elements 13 are arranged two-dimensionally (e.g., in a matrix) on the substrate 12. The substrate 12 is, for example, a semiconductor substrate such as a silicon substrate. Each functional element 13 is a MEMS (Micro Electro Mechanical Systems) device. In the laser processing apparatus 1, multiple lines 16 are set on the object 11 so as to pass between the multiple functional elements 13. For example, if the multiple functional elements 13 are arranged in a matrix, the multiple lines 16 will extend in a grid pattern.

The tape 14 is attached to the back surface 11b (the surface opposite to the front surface 11a) of the object 11. Specifically, the central portion 14a of the tape 14 is attached to the back surface 11b of the object 11. The tape 14 is transparent to the laser light L. The tape 14 is a dicing tape and is expandable. For example, the base material of the tape 14 is polyvinyl chloride, polyolefin, polyethylene terephthalate, polypropylene, etc., and the adhesive material of the tape 14 is acrylic resin, etc. The transmittance of the tape 14 to the laser light L is 70% or more. The expansion rate of the tape 14 is 103% or more.

The frame 15 holds the tape 14. Specifically, the frame 15 holds the tape 14 by attaching an outer edge portion 14b of the tape 14 to the frame 15. The frame 15 is formed into a ring shape, for example, from a metal plate. In the object unit 10, the object 11 is located inside the frame 15, and an intermediate portion 14c of the tape 14 between the object 11 and the frame 15 (i.e., the portion of the tape 14 between the central portion 14a and the outer edge portion 14b) is exposed to the outside.
[Configuration of the support part of the laser processing device and the laser processing auxiliary tool]

As shown in Figures 3 and 4, the object unit 10 is attached to the support 2 via the laser processing auxiliary tool 5. The support 2 includes a holding unit 21 and a suction table 22. The holding unit 21 holds the frame 15 of the object unit 10. The holding unit 21 is configured, for example, with multiple clamps. The suction table 22 generates an air suction action on the suction surface 22a. The suction table 22 is, for example, a chuck table configured so that multiple suction ports of multiple nozzles that suck air are located on the suction surface 22a. In this embodiment, the support 2 supports the object 11 so that, when the object unit 10 is configured (i.e., when the tape 14 is attached to the back surface 11b of the object 11 and the tape 14 is held by the frame 15), the laser light L is incident on the object 11 from the back surface 11b side via the tape 14.

The laser processing auxiliary tool 5 comprises a first sheet 51 and a second sheet 52. The second sheet 52 is placed on the suction table 22 so as to cover the suction surface 22a. The first sheet 51 is laminated on the second sheet 52 so that the outer edge 51a of the first sheet 51 is located inside the outer edge 52a of the second sheet 52. In other words, the first sheet 51 is placed on the suction table 22 via the second sheet 52. When viewed from the Z direction, the shape of the first sheet 51 is approximately the same as the shape of the target object 11. When viewed from the Z direction, the shape of the second sheet 52 is approximately the same as the shape of the suction surface 22a, and the shape of the portion of the second sheet 52 outside the outer edge 51a of the first sheet 51 is approximately the same as the shape of the middle portion 14c of the tape 14.

The air permeability of the first sheet 51 is lower than that of the second sheet 52. In this embodiment, the second sheet 52 is a porous sheet, while the first sheet 51 is a non-porous sheet, so the air permeability of the first sheet 51 is approximately zero. The suction action of the suction table 22 that the first sheet 51 exerts on the object 11 is weaker than the suction action of the suction table 22 that the second sheet 52 exerts on the middle portion 14c of the tape 14. In other words, the suction force that the first sheet 51 exerts on the object 11 is weaker than the suction force that the second sheet 52 exerts on the middle portion 14c of the tape 14. In this embodiment, the air permeability of the first sheet 51 is approximately zero, so the suction force that the first sheet 51 exerts on the object 11 is approximately zero. The adhesive force of the tape 14 to the second sheet 52 is lower than the adhesive force of the tape 14 to the suction table 22.

Note that "air permeability" refers to the "volume per unit area, unit time, and unit partial pressure difference between the two sides of the sheet" of air that passes through the sheet (first sheet 51 or second sheet 52) under certain conditions. "Suction force" refers to the "magnitude per unit area" of the force that sucks an object under certain conditions. "Adhesive force" refers to the "magnitude per unit area" of the force required to peel tape 14 from an object under certain conditions.

As an example, the first sheet 51 is made of polyethylene terephthalate, and the second sheet 52 is made of polyethylene. The first sheet 51 may be made of a cushioning material, or may be made of a hard material (e.g., glass) as long as it is flat. The second sheet 52 may be coated to reduce the adhesive strength of the tape 14, or may have a surface shape that reduces the adhesive strength of the tape 14. The second sheet 52 is preferably low in dust generation and is preferably antistatically treated.

When the frame 15 is held by the holder 21 with the object unit 10 configured so that the laser light L is incident on the object 11 from the back surface 11b side via the tape 14, the object 11 is placed on the first sheet 51. In this state, the second sheet 52 causes the suction table 22 to apply suction to the middle portion 14c of the tape 14 at a position lower than the back surface 11b of the object 11 placed on the first sheet 51. As a result, the middle portion 14c of the tape 14 is sucked by the second sheet 52 and comes into contact with the second sheet 52. Note that "a position lower than the back surface 11b" refers to a position on the side of the surface including the back surface 11b where multiple functional elements 13 are present (in this embodiment, the side where the suction table 22 is present).

In this embodiment, the suction table 22 and the laser processing auxiliary tool 5 may be integrally configured. In this case, the first sheet 51 functions as a mounting portion 23 on which the object 11 is placed. A portion of the second sheet 52 outside the outer edge 51 a of the first sheet 51 functions as a suction portion 24 that generates a suction effect on the middle portion 14 c of the tape 14 at a position lower than the back surface 11 b of the object 11 placed on the mounting portion 23. The suction effect that the mounting portion 23 generates on the object 11 is weaker than the suction effect that the suction portion 24 generates on the middle portion 14 c of the tape 14.
[Laser processing method using laser processing auxiliary tool]

As shown in Figures 3 and 4, first, tape 14 is attached to the back surface 11b of the object 11 and held by frame 15, thereby forming object unit 10 (first step). Next, object unit 10 is attached to support 2 (second step). Specifically, holder 21 holds frame 15, and object 11 is placed on first sheet 51 so that laser light L is incident on object 11 from the back surface 11b side via tape 14. In this state, second sheet 52 (more specifically, the portion of second sheet 52 outside the outer edge 51a of first sheet 51) generates a suction effect on middle portion 14c of tape 14 at a position lower than the back surface 11b of object 11 placed on first sheet 51.

Next, as shown in FIG. 5, the control unit 4 controls at least one of the support unit 2 and the irradiation unit 3 so that the focal point C moves relatively along each line 16 (third step). At this time, the position of the focusing lens 33 in the Z direction is fine-tuned by the piezoelectric element based on the displacement data of the rear surface 11b acquired by the distance measurement sensor so that the distance from the rear surface 11b to the focal point C remains constant. By irradiating the object 11 with the laser light L in this manner, modified regions M are formed in the object 11 along each line 16. Next, as shown in FIG. 6, the object unit 10 is removed from the support unit 2. Next, as shown in FIG. 7, the tape 14 is expanded by pressing the pressing member 6 against the tape 14 from the side opposite the object 11. As a result, the object 11 is cut into functional elements 13 starting from the modified regions M formed along each line 16, and the multiple semiconductor chips 110 obtained by cutting are separated from each other. Next, ultraviolet light is irradiated onto the tape 14, reducing the adhesive strength of the tape 14 and allowing each semiconductor chip 110 to be picked up.

3 and 4 , when the suction table 22 and the laser processing auxiliary tool 5 are integrally configured, the holding unit 21 holds the frame 15 and the object 11 is placed on the placing unit 23 so that the laser light L is incident on the object 11 from the back surface 11b side through the tape 14. In this state, the suction unit 24 generates a suction effect on the middle portion 14c of the tape 14 at a position lower than the back surface 11b of the object 11 placed on the placing unit 23.
[Action and effect]

In the laser processing auxiliary tool 5, the frame 15 is held by the holder 21 so that the laser light L is incident on the object 11 from the back surface 11b side via the tape 14, and the object 11 is placed on the first sheet 51 with the front surface 11a of the object 11 facing the first sheet 51. The second sheet 52 then generates a suction action of the suction table 22 on the middle portion 14c of the tape 14 at a position lower than the back surface 11b of the object 11. As a result, the elastic force of the tape 14 presses the object 11 against the suction table 22, thereby suppressing deformation and misalignment of the object 11 and accurately forming a modified region M in the object 11. Furthermore, there is no need to attach tape 14 to the surface 11a of the object 11. Furthermore, the suction effect of the suction table 22 that the first sheet 51 exerts on the object 11 is weaker than the suction effect of the suction table 22 that the second sheet 52 exerts on the middle portion 14c of the tape 14. This prevents damage to the multiple functional elements 13 formed on the surface 11a of the object 11, even if the functional elements 13 have a fragile structure. As described above, the laser processing auxiliary tool 5 can accurately form a modified region M in the object 11 while preventing damage to the multiple functional elements 13 formed on the surface 11a of the object 11, even if the functional elements 13 have a fragile structure. In this embodiment, each functional element 13 is a MEMS device, so the laser processing auxiliary tool 5 is particularly effective because it can prevent damage to the multiple functional elements 13 formed on the surface 11a of the object 11.

In the laser processing aid 5, the first sheet 51 is laminated on the second sheet 52 so that the outer edge 51a of the first sheet 51 is positioned inside the outer edge 52a of the second sheet 52. This allows the laser processing aid 5 to be easily constructed.

In the laser processing auxiliary tool 5, the adhesive strength of the tape 14 to the second sheet 52 is lower than the adhesive strength of the tape 14 to the suction table 22. This makes it easy to peel the middle portion 14c of the tape 14 from the second sheet 52 after processing.

Furthermore, even when the suction table 22 and the laser processing auxiliary tool 5 are configured as an integrated unit, for the reasons described above, the laser processing apparatus 1 and the laser processing method can accurately form a modified region M in the object 11 while suppressing damage to the multiple functional elements 13 formed on the surface 11a of the object 11, even if the functional element 13 has a fragile structure.
[Experimental Results]

According to the procedure of the above-described "laser processing method using a laser processing auxiliary tool," modified regions M were formed on the object 11 along each line 16 extending along the X direction under the following conditions. Then, the displacement of the back surface 11b of the object 11 along the Y direction was measured. The results shown in FIG. 8 were obtained. In FIG. 8, the horizontal axis represents the position in the Y direction, and the region between the two rising edges corresponds to the object 11. In FIG. 8, the vertical axis represents the voltage value of the signal indicating the displacement of the back surface 11b, with 1 V corresponding to approximately 8 μm. As shown in FIG. 8, after forming modified regions M on the object 11 along each line 16 extending along the X direction, the "displacement of the back surface 11b along the Y direction" was within a range of approximately 8 μm. This level of displacement allows for fine adjustment of the position of the condenser lens 33 in the Z direction, allowing modified regions M to be formed on the object 11 along each line 16 extending along the Y direction with high precision.
Object 11: Silicon wafer Diameter of object 11: 8 inches
Thickness of object 11: 300 μm
Diameter of suction surface 22a: 12 inches
Distance between adjacent lines 16: 1 mm
Relative moving speed of the focal point C along each line 16: 530 mm/sec
Wavelength of laser light L: 1099 nm
Repetition frequency of laser light L: 80 kHz
Number of columns of modified regions M per line 16: 4 columns

Following the above experiment, modified regions M were formed in the object 11 along each line 16 extending in the Y direction under the above conditions, and the object 11 was cut into multiple chips. The results shown in FIG. 9 were obtained. (a) of FIG. 9 is a photograph of the cut surface of the chip when a suction effect was applied to the surface 11a of the object 11 (Comparative Example), and (b) of FIG. 9 is a photograph of the cut surface of the chip when a suction effect was not applied to the surface 11a of the object 11 according to the procedure of the "laser processing method using a laser processing auxiliary tool" described above (Example). As shown in (a) and (b) of FIG. 9, the modified regions M were formed with high precision in the Example with the same accuracy as in the Comparative Example. Furthermore, the achievement rate of cutting the object 11 into multiple chips, the straightness of the crack on the surface 11a, and the straightness of the crack on the back surface 11b were 100%, within 3 μm, and within 5 μm, respectively, and similar results were obtained between the Example and the Comparative Example. The comparative example that generates a suction effect on the surface 11a of the object 11 is effective only in terms of forming the modified region M with high precision, but has the problem that if the functional element 13 has a fragile structure, the multiple functional elements 13 formed on the surface 11a side of the object 11 are likely to be damaged.
[Modification]

The present invention is not limited to the above embodiment. For example, as shown in FIG. 10, in the laser processing aid 5, the second sheet 52 may extend along the outer edge 51a of the first sheet 51. In this case, the laser processing aid 5 can be easily constructed. In this form, the suction table 22 and the laser processing aid 5 may also be constructed integrally. In that case, the first sheet 51 functions as the mounting portion 23, and the second sheet 52 functions as the suction portion 24.

As shown in FIG. 11, when viewed from the Z direction, the shape of the first sheet 51 may be substantially the same as the shape of the suction surface 22a, and the shape of the second sheet 52 may be larger than the shape of the suction surface 22a. In this case, the laser processing auxiliary tool 5 may include a guide 53 that positions and fixes the first sheet 51 and the second sheet 52 relative to the suction table 22. Even in this form, the suction table 22 and the laser processing auxiliary tool 5 may be configured as an integrated unit. In that case, the first sheet 51 functions as the mounting portion 23, and the second sheet 52 functions as the suction portion 24.

As shown in FIG. 12, the support unit 2 may be provided with a mounting unit 23 and a suction unit 24 as separate units. Furthermore, the suction force of the multiple nozzles on the suction table 22 may be adjusted so that the suction action generated in the area of the suction surface 22a corresponding to the object 11 is weaker than the suction action generated in the area of the suction surface 22a corresponding to the middle portion 14c of the tape 14.

As shown in FIG. 13 , the adhesive strength of the tape 14 may be lower at the intermediate portion 14c than at the central portion 14a and the outer edge portion 14b. Such a tape 14 may have a release film (a protective film for the adhesive) remaining only at the intermediate portion 14c, or may have no adhesive formed only at the intermediate portion 14c. In this case, it is not necessary to consider the adhesive strength of the tape 14 to the second sheet 52. The release film remaining only at the intermediate portion 14c may be divided into multiple portions. In this case, there may or may not be a gap between adjacent portions. Furthermore, if the adhesive strength of the intermediate portion 14c of the tape 14 is reduced by irradiating the intermediate portion 14c of the tape 14 with ultraviolet light before the object unit 10 is removed from the support portion 2, it is also not necessary to consider the adhesive strength of the tape 14 to the second sheet 52.

The first sheet 51 is not limited to having a shape substantially identical to that of the object 11 when viewed from the Z direction. The first sheet 51 may have a shape including multiple functional elements 13 when viewed from the Z direction. Furthermore, each functional element 13 is not limited to a MEMS device. If the functional elements 13 have a fragile structure, the laser processing aid 5, laser processing apparatus 1, and laser processing method are effective in preventing damage to the multiple functional elements 13 formed on the surface 11a of the object 11. As an example, the above-described laser processing aid 5, laser processing apparatus 1, and laser processing method are also effective for an object 11 having multiple bumps on the surface 11a (a so-called bump wafer). If a suction force is applied to the surface 11a of the object 11, warping of the object 11 may occur, potentially resulting in damage to the object 11. In this case, it may be appropriate for the first sheet 51, which comes into contact with the multiple bumps, to be made of a cushioning material.

1...laser processing device, 2...support unit, 3...irradiation unit, 4...control unit, 5...laser processing auxiliary tool, 11...object, 11a...surface, 11b...back surface, 13...functional element, 14...tape, 14c...intermediate portion, 15...frame, 16...line, 21...holding unit, 22...suction table, 23...placing unit, 24...suction unit, 51...first sheet, 51a...outer edge, 52...second sheet, 52a...outer edge, L...laser light, C...focus point, M...modified area.

Claims (7)

A laser processing device that irradiates a target object having a plurality of functional elements formed on a surface side thereof with laser light to form a modified region in the target object along each of a plurality of lines that are set to pass between the plurality of functional elements, the laser processing device comprising: a support unit that supports the target object; an irradiation unit that irradiates the target object with the laser light; and a control unit that controls at least one of the support unit and the irradiation unit so that a focal point of the laser light moves relatively along each of the plurality of lines,
a first sheet on which the object is placed, the first sheet being placed on a suction table included in the support unit when the frame is held by a holding unit included in the support unit so that the laser light is incident on the object from the back side via the tape, with a tape that is transparent to the laser light being attached to the back side of the object and the tape being held by a frame;
a second sheet that is placed on the suction table in the above case, and that generates a suction effect of the suction table on an intermediate portion of the tape between the object and the frame at a position lower than the back surface of the object placed on the first sheet,
A laser processing auxiliary tool, wherein the suction action of the suction table that the first sheet causes on the object is weaker than the suction action of the suction table that the second sheet causes on the intermediate portion. The laser processing aid described in claim 1, wherein the first sheet is laminated on the second sheet so that the outer edge of the first sheet is located inside the outer edge of the second sheet. A laser processing aid as described in claim 1, wherein the second sheet extends along the outer edge of the first sheet. The laser processing aid described in any one of claims 1 to 3, wherein the adhesive strength of the tape to the second sheet is lower than the adhesive strength of the tape to the suction table. A laser processing aid according to any one of claims 1 to 4, wherein each of the plurality of functional elements is a MEMS device. A laser processing apparatus that irradiates a target object having a plurality of functional elements formed on a surface side thereof with laser light to form modified regions in the target object along each of a plurality of lines that are set to pass between the plurality of functional elements,
a support portion that supports the object such that a tape that is transparent to the laser light is attached to a back surface of the object and the tape is held by a frame, and the laser light is incident on the object from the back surface side via the tape;
an irradiation unit that irradiates the object with the laser light;
a control unit that controls at least one of the support unit and the irradiation unit so that a focal point of the laser light moves relatively along each of the plurality of lines,
The support portion is
a holding portion that holds the frame;
a placement section on which the object is placed;
a suction portion that generates a suction effect on an intermediate portion of the tape between the object and the frame at a position lower than the back surface of the object placed on the placement portion,
A laser processing device, wherein the suction effect that the placing portion generates on the object is weaker than the suction effect that the suction portion generates on the intermediate portion. A laser processing method for use in a laser processing apparatus that irradiates a target object having a plurality of functional elements formed on a surface side thereof with laser light to form modified regions in the target object along each of a plurality of lines that are set to pass between the plurality of functional elements, the laser processing method comprising: a support unit that supports the target object; an irradiation unit that irradiates the target object with the laser light; and a control unit that controls at least one of the support unit and the irradiation unit so that a focal point of the laser light moves relatively along each of the plurality of lines,
a first step in which a tape transparent to the laser light is attached to a back surface of the object and the tape is held by a frame;
a second step in which a holding portion included in the support portion holds the frame and the object is placed on a placement portion included in the support portion so that the laser light is incident on the object from the back side through the tape, and a suction portion included in the support portion generates a suction effect on an intermediate portion of the tape between the object and the frame at a position lower than the back side of the object placed on the placement portion;
a third step in which the control unit controls at least one of the support unit and the irradiation unit so that the light-focusing point moves relatively along each of the plurality of lines,
In the second step, the suction effect that the placing section generates on the object is weaker than the suction effect that the suction section generates on the intermediate portion.