Laser processing methods and laser processing equipment

Abstract

Laser processing method comprising: a first step of producing a wafer with a first area in which a surface layer of a road contains an insulating film, and a second area in which the surface layer contains an insulating film and a metal structure on the insulating film; a second step of irradiating the road with a predetermined first laser beam;and a third step of irradiating the road with a predetermined second laser beam after the second step, wherein the first laser beam is a laser beam having a processing energy to remove part of the insulating film in the first area while leaving the other part intact, to completely remove the metal structure in the second area, and to remove part of the insulating film in the second area while leaving the other part intact, and wherein the second laser beam is a laser beam having a processing energy to completely remove the insulating film in the first area and the insulating film in the second area after the second step.

Description

Technical area

[0001] One aspect of the present invention relates to a laser processing method and a laser processing apparatus. Background Technology

[0002] In a wafer containing a plurality of functional elements arranged side by side across a street, there is a case where an insulating film (low-k film or the like) and a metal structure (a metal post, a metal pad, or the like) are formed on a surface layer of the street. In such a case, if a modified region is formed in the wafer along a line passing through the street and the wafer is divided into chips for each of the functional elements by extending a fracture from the modified region, the quality of the chips may deteriorate; for example, film peeling may occur in a portion along the street. Therefore, when the wafer is divided into chips for each of the functional elements, in some cases, groove processing is performed to remove the surface layer of the street by irradiating the street with a laser beam.

[0003] In the methods described in Patent Literature 1, machining is performed with multi-branched laser beams to suppress the occurrence of thermal damage on the road surface caused by laser beam irradiation. Machining with multi-branched laser beams suppresses the influence of thermal damage at a single machining point. Citation listPatent literature

[0004] Patent Literature 1: Japanese Patent No. 6309341 Summary of the inventionTechnical problem

[0005] Here, the road may include a region where the surface layer includes the insulating film and a metal pattern on the insulating film, and a region where the surface layer includes only the insulating film (region where the metal pattern is not formed). In such a case, if the road is irradiated with a laser beam under the condition that the metal pattern can be reliably removed, there is a possibility that thermal damage may occur in the region where the metal pattern is not formed in the surface layer of the road. Such thermal damage will lead to deterioration of chip quality.

[0006] An object of the present invention is therefore to provide a laser processing method and a laser processing apparatus capable of suppressing deterioration of chip quality. Solution to the problem

[0007] A laser processing method according to one aspect of the present invention comprises: a first step of manufacturing a wafer including a plurality of functional elements arranged side by side across a street, the wafer having a first region in which a surface layer of the street includes an insulating film, and a second region in which the surface layer includes an insulating film and a metal pattern on the insulating film; a second step of irradiating the street with a predetermined first laser beam;and a third step of irradiating the road with a predetermined second laser beam after the second step, wherein the first laser beam is a laser beam having a processing energy for removing a part of the insulating film in the first region to leave another part, for completely removing the metal pattern in the second region, and for removing a part of the insulating film in the second region to leave another part in an irradiation region, and the second laser beam is a laser beam having a processing energy for completely removing the insulating film in the first region and the insulating film in the second region after the second step in the irradiation region.

[0008] In the laser machining method according to one aspect of the present invention, the wafer having, in the surface layer of the street, the first region having the insulating film and the second region having the insulating film and the metal pattern on the insulating film is prepared, the street of the wafer is irradiated with the first laser beam, and then the street is irradiated with the second laser beam. The first laser beam is the laser beam having the machining energy to remove a part of the insulating film in the first region to leave the other part, to completely remove the metal pattern in the second region, and to remove a part of the insulating film in the second region to leave the other part. In this way, a part of the insulating film in both the first region and the second region has been removed after the street is irradiated with the first laser beam.Here, a region irradiated with the first laser beam has an uneven shape (frosted glass shape) in the state where a part of the insulating film has been removed by the first laser beam. Such an uneven surface has low transmittance to the laser beam. Therefore, even in a case where the second laser beam emitted after irradiation with the first laser beam is the laser beam having the processing energy to completely remove the insulating film in the first region and the insulating film in the second region, the uneven surface with the low transmittance can suppress the transmission of light toward a substrate of the wafer made of silicon or the like, and thermal damage to the wafer caused by the laser beam can be suppressed.As described above, it is possible to suppress the thermal damage of the wafer caused by the laser beam and prevent deterioration of the chip quality by the laser processing method according to one aspect of the present invention.

[0009] The second laser beam may be a laser beam having a processing energy sufficient to excavate a portion of a substrate contained in the wafer after the second step. As a result, a portion of the substrate is hollowed out by the second laser beam, and it is possible to suppress the occurrence of film peeling in the wafer while reliably performing the groove processing for removing the surface layer.

[0010] The second laser beam can be a laser beam with a processing energy sufficient to hollow the substrate by 4 µm or less after the second step. Setting the hollowing amount to 4 µm or less can suppress thermal damage to the wafer caused by the laser beam, and chip quality deterioration can be suppressed.

[0011] The laser machining method may further comprise a fourth step of grinding or polishing the substrate after the third step to expose a groove formed on the road by irradiation with the second laser beam. With such a laser machining method, complete cutting can be performed by grooving without performing a dicing step after laser grooving. This allows for rapid machining.

[0012] A laser processing method according to one aspect of the present invention comprises: a first step of manufacturing a wafer including a plurality of functional elements arranged side by side via a street, the wafer having a first region in which a surface layer of the street includes an insulating film, and a second region in which the surface layer includes an insulating film and a metal pattern on the insulating film; a second step of irradiating the street with a laser beam to make the insulating films in the first region and the second region uneven; and a third step of irradiating the street with a laser beam to completely remove the insulating films in the first region and the second region after the second step.

[0013] In the laser processing method according to one aspect of the present invention, the wafer having the first region with the insulating film and the second region with the insulating film and the metal pattern on the insulating film in the surface layer of the street is prepared. The street of the wafer is irradiated with the laser beam to make the insulating films in the first region and the second region uneven. Then, the street is irradiated with the second laser beam to completely remove the insulating films in the first region and the second region. An uneven (frosted) surface of the insulating film has low transmittance to the laser beam.Therefore, even in a case where the subsequently emitted laser beam is the laser beam having the processing energy to completely remove the insulating film in the first region and the insulating film in the second region, the uneven surface with low transmittance can suppress the transmission of light toward a substrate of the wafer made of silicon or the like, and thermal damage to the wafer caused by the laser beam can be suppressed. As described above, it is possible to suppress thermal damage to the wafer caused by the laser beam and prevent deterioration of chip quality by the laser processing method according to one aspect of the present invention.

[0014] A laser processing apparatus according to one aspect of the present invention comprises: a support member configured to support a wafer including a plurality of functional elements arranged side by side across a street, the wafer having a first region in which a surface layer of the street includes an insulating film, and a second region in which the surface layer includes an insulating film and a metal pattern on the insulating film; an irradiation unit configured to irradiate the street with a laser beam; and a control unit configured to control the irradiation unit, the control unit configured to perform first control to control the irradiation unit to irradiate the street with a predetermined first laser beam and perform second control to control the irradiation unitthat the road is irradiated with a predetermined second laser beam after the first control, wherein the first laser beam is a laser beam having a processing energy for removing a part of the insulating film in the first region to leave another part, completely removing the metal structure in the second region, and removing a part of the insulating film in the second region to leave another part in an irradiation region, and the second laser beam is a laser beam having a processing energy for completely removing the insulating film in the first region and the insulating film in the second region after irradiation with the first laser beam in the irradiation region. In the laser processing apparatus according to one aspect of the present invention, it is possibleto suppress thermal damage to the wafer caused by the laser beam and to suppress deterioration of chip quality, which is similar to the laser processing method described above.

[0015] A laser processing apparatus according to one aspect of the present invention comprises: a support member configured to support a wafer including a plurality of functional elements arranged side by side across a street, the wafer having a first region in which a surface layer of the street includes an insulating film, and a second region in which the surface layer includes an insulating film and a metal pattern on the insulating film; an irradiation unit configured to irradiate the street with a laser beam;and a control unit configured to control the irradiation unit, the control unit configured to perform first control to control the irradiation unit in such a manner that the road is irradiated with the laser beam to make the insulating films in the first region and the second region uneven, and second control to control the irradiation unit in such a manner that the road is irradiated with the laser beam to completely remove the insulating films in the first region and the second region after the first control. In the laser processing apparatus according to one aspect of the present invention, it is possible to suppress thermal damage to the wafer caused by the laser beam and suppress deterioration of chip quality, which is similar to the laser processing method described above. Advantageous effects of the invention

[0016] According to one aspect of the present invention, it is possible to suppress the deterioration of chip quality. Brief description of the drawings Fig. 1 is a configuration diagram showing a laser processing apparatus according to an embodiment. Fig. 2 is a plan view of a wafer coated with the Fig. 1 shown laser processing device. Fig. 3 is a cross-sectional view showing a part of the Fig. 2 shows the wafer. Fig. 4 is a plan view of a part of a Fig. 2 shown street. Fig. Figure 5 is a diagram describing the generation of a heat-affected zone (HAZ) by grooving. Fig. 6 is a diagram for describing the grooving process according to the present embodiment. Fig. Figure 7 is a diagram describing the principle of suppressing the formation of HAZ. Fig. 8 is a view for describing an example of setting conditions in a case where a pad area is removed (ablated) in one pass. Fig. 9 is a view showing an example of setting the state in a case where a pad area is removed (ablated) in two passes. Fig. 10 is a view for describing an example of setting conditions in the case where the pad area is removed (ablated) in two passes. Fig. 11 is a view showing the conditions of a test regarding the relationship between the depth of the laser groove and the chip strength. Fig. Figure 12 is a view showing the test conditions regarding the relationship between the depth of the laser groove and the chip strength. Fig. Figure 13 is a view showing the test results regarding the relationship between the depth of the laser groove and the chip strength. Fig. 14 is a flowchart of a laser processing method according to an embodiment. Fig. 15 is a diagram for describing a laser processing method according to a modification. Fig. 16 is a flowchart of the laser processing method according to the amendment. Fig. 17 is a diagram for describing a laser processing method according to another modification. Description of the embodiments

[0017] Embodiments of the present invention will be described in detail below with reference to the drawings. Note that in the drawings, identical or corresponding parts are designated by identical reference numerals, and redundant descriptions are omitted. [Configuration of laser processing equipment]

[0018] As in Fig. 1, a laser processing apparatus 1 includes a support part 2, an irradiation unit 3, an imaging unit 4, and a control unit 5. The laser processing apparatus 1 is an apparatus that performs groove processing for removing a surface layer of a street of a wafer 20 by irradiating the street (details will be described later) of the wafer 20 with a laser beam L. In the following description, three mutually perpendicular directions are referred to as the X direction, the Y direction, and the Z direction, respectively. For 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.

[0019] The holding part 2 supports the wafer 20. The holding part 2 holds the wafer 20 such that a front surface of the wafer 20, including the street, faces the irradiation unit 3 and the imaging unit 4, for example, by suctioning a film (not shown) attached to the wafer 20. For example, the holding part 2 can move along the X-direction or the Y-direction and rotate around an axis parallel to the Z-direction as the centerline.

[0020] The irradiation unit 3 irradiates the street of the wafer 20 supported by the carrier part 2 with the laser beam L. The irradiation unit 3 includes a light source 31, a shaping optical system 32, a dichroic mirror 33, and a light condenser 34. The light source 31 emits the laser beam L. The shaping optical system 32 adjusts the laser beam L emitted by the light source 31. For example, the shaping optical system 32 includes at least an attenuator that adjusts the output power of the laser beam L, a beam expander that increases the diameter of the laser beam L, and a spatial light modulator that modulates the phase of the laser beam L.When the spatial light modulator is included, the shaping optical system 32 may comprise an imaging optical system forming a double telecentric optical system in which a modulation surface of the spatial light modulator and an entrance pupil surface of the light condenser 34 are in an imaging relationship. The dichroic mirror 33 reflects the laser beam L emitted by the shaping optical system 32 so that it impinges on the light condenser 34. The light condenser 34 condenses the laser beam L reflected by the dichroic mirror 33 onto the wafer 20 supported by the support member 2.

[0021] The irradiation unit 3 further includes a light source 35, a half mirror 36, and an imaging element 37. The light source 35 emits visible light V1. The half mirror 36 reflects the visible light V1 emitted by the light source 35, so that it is incident on the light condenser 34. The dichroic mirror 33 transmits the visible light V1 between the half mirror 36 and the light condenser 34. The light condenser 34 condenses the visible light V1 reflected by the half mirror 36 onto the wafer street 20 supported by the support member 2. The imaging element 37 detects the visible light V1 reflected from the wafer street 20 and transmitted through the light condenser 34, the dichroic mirror 33, and the half mirror 36.In the laser processing apparatus 1, the control unit 5 moves the light condenser 34 along the Z direction based on a detection result by the imaging element 37, for example, so that a condensation point of the laser beam L is located on the road of the wafer 20.

[0022] The imaging unit 4 acquires image data from the street of the wafer 20 supported by the support part 2. The imaging unit 4 includes a light source 41, a half mirror 42, a light condenser 43, and an imaging element 44. The light source 41 emits visible light V2. The half mirror 42 reflects the visible light V2 emitted by the light source 41, causing it to be incident on the light condenser 43. The light condenser 43 condenses the visible light V2 reflected by the half mirror 42 onto the street of the wafer 20 supported by the support part 2. The imaging element 44 detects the visible light V2 reflected from the street of the wafer 20 and transmitted through the light condenser 43 and the half mirror 42.

[0023] The control unit 5 controls the operation of the individual parts of the laser processing device 1. The control unit 5 controls, for example, the irradiation unit 3. The control unit 5 includes a processing unit 51, a storage unit 52, and an input receiving unit 53. The processing unit 51 is a computer device including a processor, a memory, a storage device, a communication device, and the like. In the processing unit 51, the processor executes software (program) read into the memory or the like, and controls the reading and writing of data in the memory and storage, as well as communication through a communication device. The storage unit 52 is, for example, a hard disk or the like and stores various types of data. The input receiving unit 53 is an interface unit that receives inputs of various types of data from an operator.The input receiving unit 53 is, for example, at least one keyboard, one mouse or one graphical user interface (GUI). [Wafer configuration]

[0024] As in Fig. 2 and Fig. 3, the wafer 20 includes a semiconductor substrate 21 and a functional element layer 22. The semiconductor substrate 21 has a front surface 21a and a back surface 21b. The semiconductor substrate 21 is, for example, a silicon substrate. The semiconductor substrate 21 is provided with a notch 21c indicating a crystal orientation. The semiconductor substrate 21 may also be provided with an orientation surface instead of the notch 21c. The functional element layer 22 is formed on the front surface 21a of the semiconductor substrate 21. The functional element layer 22 includes a plurality of functional elements 22a. The plurality of functional elements 22a are arranged two-dimensionally along the front surface 21a of the semiconductor substrate 21. Each of the functional elements 22a is, for example, a light-receiving element such as a photodiode, a light-emitting element such as a laser diode, a circuit element such as a memory, or the like.Each of the functional elements 22a can be configured three-dimensionally by superimposing a plurality of layers.

[0025] A plurality of streets 23 are formed on the wafer 20. The plurality of streets 23 are regions that are open to the outside between the adjacent functional elements 22a. That is, the plurality of functional elements 22a are arranged next to one another across the streets 23. For example, the plurality of streets 23 extend in a grid shape so that they run between the adjacent functional elements 22a with respect to the plurality of functional elements 22a arranged in a matrix. As shown in Fig. As shown in Figure 4, an insulating film 24 and a plurality of metal structures 25 are formed on a surface layer of the road 23. The insulating film 24 is, for example, a low-k film or the like. The metal structure 25 is, for example, a metal pad made of aluminum or the like.

[0026] As in Fig. 2 and Fig. 3, the wafer 20 is to be cut (i.e., divided into chips for each of the functional elements 22a) along a plurality of lines 15. The lines 15 each pass through the streets 23 when viewed from a thickness direction of the wafer 20. For example, the lines 15 pass through the centers of the streets 23 when viewed from the thickness direction of the wafer 20. Each of the lines 15 is a virtual line drawn on the wafer 20 by the laser processing apparatus 1. Each of the lines 15 may be a line actually drawn on the wafer 20. [Operation of a laser processing device and a laser processing method]

[0027] The laser processing apparatus 1 performs groove processing by irradiating each of the streets 23 with the laser beam L and removing the surface layer of each of the streets 23. Specifically, the control unit 5 controls the irradiation unit 3 so that each of the streets 23 of the wafer 20 supported by the support member 2 is irradiated with the laser beam L, and the control unit 5 controls the support member 2 so that the laser beam L moves relatively along each of the streets 23.

[0028] For example, in groove processing, in the case of performing knife dicing, it is necessary to completely remove the surface layer of the street 23 from a dicing street. Here, the surface layer of the street 23 includes a region (hereinafter sometimes referred to as the first region) containing only the insulating film 24 and a region (hereinafter sometimes referred to as the second region) containing the insulating film 24 and the metal structure 25 on the insulating film 24. For example, a surface layer (region of a dicing street 400) of the street 23 of the wafer 20 shown in the left diagram of Fig. 5(a), only a low-k film 242 and a SiN / SiO2 film 241 corresponding to the insulating film 24, and represents the first region. In addition, a surface layer (dicing street region 400) of the street 23 of the wafer 20 shown in the left diagram of Fig. 5(b) shows the low-k film 242 and the SiN / SiO2 film 241 corresponding to the insulating film 24, and the metal pattern 25 (metal pad) on the insulating film 24, indicating the second region. When the wafer 20 having the first region and the second region is processed under the usual groove processing conditions regardless of the region, thermal damage to the wafer 20 may become a problem.

[0029] That is, in order to completely remove the surface layer of the street 23 in any region of the wafer 20, it is necessary to adjust the processing energy of the laser beam L for the groove processing so that the surface layer is excavated up to an interface of the semiconductor substrate 21 in the second region including the insulating film 24 and the metal structure 25 on the insulating film 24 (see the right diagram of Fig. 5(b)). Since the absorption rate of a laser wavelength in the metal structure 25 is greater than in the insulating film 24, most of the energy is absorbed by the metal structure 25 in the second region. Therefore, it is necessary to increase the processing energy of the laser beam L in order to also remove the insulating film 24 below the metal structure 25. However, if the groove processing in the first region containing only the insulating film 24 is performed with the laser beam L whose processing energy has been increased in this way, the energy in the first region is too high, and the semiconductor substrate 21 is too strongly attacked to create a heat-affected zone (HAZ), as shown in the right diagram of Fig. 5(a), and a decrease in the strength of the wafer 20 may be a problem due to thermal damage to the wafer 20.

[0030] The Fig. The example shown in Fig. 5 illustrates the generation of the HAZ in a case where the conditions for the wafer 20 and the conditions for laser engraving are set as follows, for example. (Conditions of Wafer 20)

[0031] Wafer size: 12 inches, wafer thickness: 300 µm, chip size: 5 mm, dicing street width 400: 60 µm, pattern thickness (thickness of insulating film 24): 8 µm, and metal structure thickness 25: 1 µm. (Conditions for laser engraving)

[0032] Forming groove with a width of 55 µm for cutting blades, laser beam wavelength L: 515 µm, pulse width: 600 fs, condensation position: device surface, number of branches: 21-point branches, pulse pitch: 0.5 µm, machining energy: 9.9 µJ, fluence / point: 0.85 J / cm2, and number of scans: 2 passes.

[0033] Here, Fluence / point indicates the pulse energy per predetermined area and denotes a value at each branch point (a point). Note that the low-k film 242, which is the insulating film 24, is provided with, for example, a wiring 300, as shown in Fig. 5 shown.

[0034] To solve the above-described problem, a laser machining method according to the present embodiment divides the irradiation of the road 23 with a laser beam in the groove machining into two steps. Specifically, the laser machining process performed by the laser machining device 1 includes a step (second step) of irradiating the road 23 with a predetermined first laser beam and a step (third step) of irradiating the road 23 with a predetermined second laser beam after the first laser beam irradiation step. To perform these steps, the control unit 5 is configured to perform first control for controlling the irradiation unit 3 so that the road 23 is irradiated with the predetermined first laser beam and second control for controlling the irradiation unit 3 so that the road 23 is irradiated with the predetermined second laser beam after the first control.Then, the first laser beam is a laser beam with processing energy for removing a portion of the insulating film 24 in the first region to leave the other portion, for completely removing the metal pattern 25 in the second region, and for removing a portion of the insulating film 24 in the second region to leave the other portion in an irradiation region. Furthermore, the second laser beam is a laser beam with processing energy for completely removing the insulating film 24 in the first region and the insulating film 24 in the second region after irradiation with the first laser beam in the irradiation region.

[0035] Fig. 6 is a diagram for describing the grooving process according to the present embodiment. Fig. 6(a) shows the irradiation with a first laser beam L1 (see the middle diagram of Fig. 6(a)) and irradiation with a second laser beam L2 (see the right diagram of Fig. 6(a)) in the first area. Fig. 6(b) shows the irradiation with the first laser beam L1 (see the middle diagram of Fig. 6(b)) and the irradiation with the second laser beam L2 (see the right diagram of Fig. 6(b)) in the second area.

[0036] As shown in the middle diagram of Fig. 6(a), the first laser beam L1 has processing energy to remove a part of the insulating film 24 in the first region to leave the other part in the irradiation region. In addition, as shown in the middle diagram of Fig. 6(b), the processing energy is used to completely remove the metal structure 25 in the second region and to remove a part of the insulating film 24 in the second region to leave the other part in the irradiation area. Here, the term "removing a part of the insulating film 24 to leave the other part" means that not all of the insulating film 24 is removed, but only a part of it, and a part other than the removed part remains in the irradiation area. Furthermore, the term "completely removing the metal structure 25" means that the entire metal structure 25 in the irradiation area is removed. The term "completely removing the metal structure 25" may also mean that substantially all of the metal structure 25 is removed, so that the metal structure 25 remains to such an extent that its function can be neglected.

[0037] As shown in the central diagram of Fig. As shown in Figure 6(a), in the first region after irradiation with the first laser beam L1, a part of the insulating film 24 (here, a part of the SiN / SiO2 layer 241) has been removed by the first laser beam L1, and a surface irradiated with the first laser beam L1 has formed a frosted glass surface 500 with an uneven shape (frosted glass shape). In addition, as shown in the central diagram of Fig. 6(b), in the second region after irradiation with the first laser beam L1, the metal structure 25 has been completely removed by the first laser beam L1, a part of the insulating film 24 (here, the entire SiN / SiO2 layer 241 and a part of the low-k layer 242) has been removed, and a surface irradiated with the first laser beam L1 has formed a frosted surface 550 with an uneven shape (frosted glass shape). In this way, the step of irradiating the first laser beam L1 (second step) is a step of irradiating the road 23 with the first laser beam L1 to make the insulating films 24 uneven in the first region and the second region. That is, the control unit 5 performs the first control of the irradiation unit 3 so that the road 23 is irradiated with the first laser beam L1 to make the insulating films 24 uneven in the first region and the second region.The frosted glass surface 500 and the frosted glass surface 550 will be described later.

[0038] As shown in the right diagram of Fig. 6(a), the second laser beam L2 has a processing energy for completely removing the insulating film 24 in the first region after being irradiated with the first laser beam L1 in the irradiation region. As shown in the right diagram of Fig. As shown in Figure 6(b), the second laser beam L2 has a processing energy to completely remove the insulating film 24 in the second region after irradiation with the first laser beam L1 in the irradiation region. The term "complete removal of the insulating film 24" means removing the entire insulating film 24 in the irradiation region. The term "complete removal of the insulating film 24" may also mean removing substantially the entire insulating film 24, so that the insulating film 24 remains in such a small amount that its function can be neglected.

[0039] As shown in the right diagram of Fig. 6(a) and in the right diagram of Fig. 6(b), the second laser beam L2 has a processing energy for digging a part of the semiconductor substrate 21 of the wafer 20 after irradiation with the first laser beam L1. That is, both an irradiation plane 600 of the second laser beam L2 in the first region (see Fig. 6(a)) as well as an irradiation plane 650 of the second laser beam L2 in the second area (see Fig. 6(b)) reach the semiconductor substrate 21. In this way, the step of irradiating the second laser beam L2 (third step) is a step of irradiating the street 23 with the laser beam L2 to completely remove the insulating films 24 in the first region and the second region. That is, after the first control described above, the control unit 5 executes the second control to control the irradiation unit 3 so that the street 23 is irradiated with the second laser beam L2 to completely remove the insulating films 24 in the first region and the second region. The second laser beam L2 may have a processing energy to hollow out the semiconductor substrate 21 of the wafer 20 by 4 μm or less after irradiation with the first laser beam L1.When the excavation is set to 4 μm or less in this way, thermal damage to the wafer 20 caused by the second laser beam L2 can be suppressed, and deterioration of chip quality can be prevented.

[0040] Grooving in Fig. 6 is carried out, for example, under the following conditions of the wafer 20 and the laser grooving. (Conditions of Wafer 20)

[0041] Wafer size: 12 inches, wafer thickness: 300 µm, chip size: 5 mm, dicing street width 400: 60 µm, pattern thickness (thickness of insulating film 24): 8 µm, and metal structure thickness 25: 1 µm.

[0042] (Conditions of laser engraving processing in the irradiation step with the first laser beam L1 (second step))

[0043] Forming groove with a width of 55 µm for cutting blades, wavelength of the first laser beam L1: 515 µm, pulse width: 600 fs, condensation position: device surface, number of branches: 21-point branches, pulse pitch: 0.5 µm, machining energy: 4.1 µJ, fluence / point: 0.35 J / cm2, and number of scans: 1 pass.

[0044] (Conditions of laser engraving processing in the irradiation step with the second laser beam L2 (third step))

[0045] Forming groove with a width of 55 µm for cutting blades, wavelength of the second laser beam L2: 515 µm, pulse width: 600 fs, condensation position: device surface, number of branches: 21-point branches, pulse pitch: 0.5 µm, machining energy: 9.9 µJ, fluence / point: 0.85 J / cm2, and number of scans: 2 passes.

[0046] The following describes the principle of suppressing the formation of the HAZ by the Fig. 6 shown groove machining with reference to Fig. 7 described. Fig. Figure 7 is a diagram describing the principle of suppressing the formation of HAZ. Fig. 7 shows the steps of groove processing in the first area of ​​the wafer 20.

[0047] As in Fig. As shown in Figure 7(a), it is assumed that the irradiation is performed with the first laser beam L1, which has a processing energy (e.g., 4.1 µJ) to remove a portion of the insulating film 24 in the first region and leave the other portion. Since the first laser beam L1 has a weak processing energy, the formation of the HAZ in the semiconductor substrate 21 is suppressed by the transmitted light. Then, as shown in Fig. As shown in Figure 7(b), a portion (here, a portion of the SiN / SiO2 layer 241) of the insulating film 24 near a condensation point is removed by the first laser beam L1, and a surface irradiated with the first laser beam L1 becomes a frosted glass surface 500 having an uneven shape (frosted glass shape). Here, the frosted glass surface 500 is a geometric surface whose direction changes randomly with respect to a normal line of an optical surface. In such a frosted glass surface 500, light is randomly refracted or scattered, so that the transmittance of the laser beam decreases. Alternatively, the absorption rate of the laser beam in such a frosted glass surface 500 increases due to shape changes, discoloration, and the like. Therefore, the laser beam irradiated onto the frosted glass surface 500 hardly reaches the semiconductor substrate 21.

[0048] Then, as in Fig. 7(c), the frosted glass surface 500, which has already been irradiated with the first laser beam L1, is irradiated with the second laser beam L2 with processing energy (e.g., 9.9 µJ) to completely remove the insulating film 24 in the first region. Such a second laser beam L2 is originally a laser beam with a processing energy that increases a dent depth in the semiconductor substrate 21 and generates the HAZ in the semiconductor substrate 21 (see the right diagram of Fig. 5(a)). However, since the frosted glass surface 500, which has a low laser beam transmittance, is irradiated with the second laser beam L2, the generation of the HAZ due to excessive indentation of the semiconductor substrate 21 with the second laser beam L2, as shown in Fig. 7(d). In particular, the digging depth with the second laser beam L2 is 4 µm or less.

[0049] Here, the second region includes the insulating film 24 and the metal structure 25 on the insulating film 24, and is different from the first region, which includes only the insulating film 24, but can be subjected to grooving under the same conditions (i.e., the first laser beam L1 and the second laser beam L2) as in the processing of the first region. That is, when the second region is irradiated with the first laser beam L1 with relatively weak processing energy, the metal structure 25 is relatively easily removed with a high absorption rate even if the processing energy is weak. Therefore, the second region can also be brought into a state in which (the metal structure 25 is completely removed and) a part of the insulating film 24 in the second region is removed by the first laser beam L1 and the other part remains, i.e., a state in which the frosted glass surface 550 (see the central diagram in Fig. 6(b)). Then, the frosted glass surface 550, which has already been irradiated with the first laser beam L1, is irradiated with the second laser beam L2 having a processing energy (e.g., 9.9 µJ) to completely remove the insulating film 24 in the second region, whereby the insulating film 24 can be appropriately removed while suppressing the formation of the HAZ similarly to the first region.

[0050] Next, the setting of the groove machining conditions will be described in detail. The condition setting here means the adjustment (condition setting) of the fluence / spot of each of the first laser beam L1 and the second laser beam L2. As described above, the fluence / spot of the first laser beam L1 and the second laser beam L2 are adjusted to meet the groove machining conditions of both the first and second regions. That is, the fluence / spot of the first laser beam L1 is adjusted so that part of the insulating film 24 in the first region is removed to leave the other part, the metal pattern 25 in the second region is completely removed, and part of the insulating film 24 in the second region is removed to leave the other part in the irradiation area.In addition, the fluence / spot of the second laser beam L2 is adjusted so that the insulating film 24 of the first region and the insulating film 24 of the second region are completely removed and the formation of the HAZ in the irradiation region is suppressed.

[0051] Fig. Fig. 8 is a view for describing an example of the state setting in a case where a pad region in which the metal pattern 25 is formed is removed in one pass (dug). In Fig. 8, "Not reaching Si" indicates a state in which a part of the insulating film 24 is removed and the other part remains, "reaching Si" indicates a state in which the insulating film 24 is completely removed and the HAZ is not generated, and "reaching Si (HAZ)" indicates a state in which the insulating film 24 is completely removed and the HAZ is generated. In addition, in Fig. 8, “Not dug” indicates a state in which the metal structure 25 is not removed at all, and “Partially dug” indicates a state in which part of the metal structure 25 is removed, “Dug” indicates a state in which the metal structure 25 is completely removed, part of the insulating film 24 is removed, and the other part remains, “Dug, reaching Si” indicates a state in which the metal structure 25 is completely removed, the insulating film 24 is completely removed, and the HAZ is not generated, and “Dug, reaching Si (HAZ)” indicates a state in which the metal structure 25 is completely removed, the insulating film 24 is completely removed, and the HAZ is generated. Fig. 8(a) is a view for describing the state setting of the first laser beam L1. Fig. 8(b) is a view for describing the state setting of the second laser beam L2.

[0052] Fig. 8(a) illustrates a state of the first region (in Fig. 8 as “area containing only film”) and a state of the second area (in Fig. 8 as the "pad area") after the groove processing, each fluence / point level with respect to the first laser beam L1. Note that an increase in the fluence / point level means that the value of fluence / point increases. As described above, the fluence / point of the first laser beam L1 is set such that a part of the insulating film 24 in the first area is removed to leave the other part, the metal structure 25 in the second area is completely removed, and a part of the insulating film 24 in the second area is removed to leave the other part in the irradiation area. Therefore, the fluence / point level of the first laser beam L1 in the Fig. 8(a) is set to 4.

[0053] Fig. 8(b) illustrates a state of the first region (in Fig. 8 as “area containing only the film”) and a state of the second area (in Fig. 8 as “pad area”) after groove processing with each fluence / point value with respect to the second laser beam L2. Note that the results of Fig. 8(b) illustrate a state in which the wafer 20 after being subjected to groove processing with the first laser beam L1 in the method based on Fig. 8(a), is subjected to groove processing with the second laser beam L2 at each fluence / point level. As described above, the fluence / point value of the second laser beam L2 is adjusted so that "the insulating film 24 of the first region and the insulating film 24 of the second region are completely removed and the formation of the HAZ in the irradiation area is suppressed." Therefore, the fluence / point value of the second laser beam L2 is adjusted in the manner shown in Fig. 8(b) is set to 7. Note that a desired result is also obtained when the fluence / spot level of the second laser beam L2 is set to 8, but it is preferable that the minimum level is selected as the fluence / spot level.

[0054] Fig. 9 and Fig. 10 are views for describing examples of state setting in a case where the pad region in which the metal structure 25 is formed is removed (dug) in two passes. In Fig. 9 and Fig. 10, "Not reaching Si" indicates a state in which a part of the insulating film 24 is removed and the other part remains, "reaching Si" indicates a state in which the insulating film 24 is completely removed and the HAZ is not generated, and "reaching Si (HAZ)" indicates a state in which the insulating film 24 is completely removed and the HAZ is generated. In addition, in Fig. 9 and Fig. 10, “Not dug” indicates a state in which the metal structure 25 is not removed at all, and “Partially dug” indicates a state in which part of the metal structure 25 is removed, “Dug” indicates a state in which the metal structure 25 is completely removed, part of the insulating film 24 is removed, and the other part remains, “Dug, reaching Si” indicates a state in which the metal structure 25 is completely removed, the insulating film 24 is completely removed, and the HAZ is not generated, and “Dug, reaching Si (HAZ)” indicates a state in which the metal structure 25 is completely removed, the insulating film 24 is completely removed, and the HAZ is generated. Fig. 9(a) is a view for describing the state setting for the first pass of the first laser beam L1, Fig. 9(b) is a view for describing the state setting for the second pass of the first laser beam L1, and Fig. 10 is a view for describing the state setting of the second laser beam L2.

[0055] Fig. 9(a) shows a state of the first area (in Fig. 8 as “area containing only film”) and a state of the second area (in Fig. 8 as the "pad area") after groove processing, each fluence / dot level with respect to the first laser beam L1 of the first pass. Since the pad area is removed in two passes, the fluence / dot value in the first pass of the first laser beam L1 is set to 4 (only a part of the metal structure 25 is removed), as shown in Fig. 9(a).

[0056] Fig. 9(b) illustrates a state of the first region (in Fig. 8 as “area containing only film”) and a state of the second area (in Fig. 8 as the “pad area”) after groove processing of each fluence / dot level with respect to the first laser beam L1 of the second pass. Note that the results of Fig. 9(b) illustrate a state in which the wafer 20 on which the groove processing with the first laser beam L1 is carried out in the first pass in the method based on Fig. 9(a), is subjected to groove processing with the first laser beam L1 in the second pass at each fluence / point level. As described above, the fluence / point of the first laser beam L1 is adjusted so that a part of the insulating film 24 in the first region is removed to leave the other part, the metal structure 25 in the second region is completely removed, and a part of the insulating film 24 in the second region is removed to leave the other part in the irradiation area. Therefore, the fluence / point value of the second pass of the first laser beam L1 in the Fig. 9(b) is set to 5.

[0057] Fig. 10 illustrates a state of the first area (in Fig. 8 as “area containing only the film”) and a state of the second area (in Fig. 8 as “pad area”) after groove processing with each fluence / point value with respect to the second laser beam L2. Note that the results of Fig. 10 illustrate a state in which the wafer 20, after being subjected to the groove processing with the first laser beam L1 of the second pass in the method based on Fig. 9(b), is subjected to groove processing with the second laser beam L2 at each fluence / point level. As described above, the fluence / point value of the second laser beam L2 is adjusted so that "the insulating film 24 of the first region and the insulating film 24 of the second region are completely removed and the formation of the HAZ in the irradiation area is suppressed." Therefore, the fluence / point value of the second laser beam L2 is adjusted in the manner shown in Fig. 10 is set to 7. It should be noted that a desired result is also achieved if the fluence / spot level of the second laser beam L2 is set to 8, but it is preferable that the minimum level be selected as the fluence / spot level.

[0058] The laser processing process is described below with reference to a flow chart in Fig. 14. First, the wafer 20 is prepared (step S1, a first step). As described above, the wafer 20 is a wafer having a plurality of functional elements 22a arranged side by side across the street 23, the wafer having a first region in which a surface layer of the street 23 includes the insulating film 24, and a second region in which the surface layer includes the insulating film 24 and the metal pattern 25 on the insulating film 24.

[0059] Subsequently, the street 23 is irradiated with the predetermined first laser beam L1 by the laser processing apparatus 1 (step S2, the second step). As described above, the first laser beam L1 is a laser beam having a processing energy for removing a part of the insulating film 24 in the first region to leave the other part, completely removing the metal pattern 25 in the second region, and removing a part of the insulating film 24 in the second region to leave the other part in an irradiation range.

[0060] Subsequently, the road 23 is irradiated with the predetermined second laser beam L2 by the laser processing device 1 (step S3, the third step). As described above, the second laser beam L2 is a laser beam with a processing energy for completely removing the insulating film 24 in the first region and the insulating film 24 in the second region after the second step in the irradiation region. The groove processing is completed by the third step.

[0061] Subsequently, the wafer 20 is irradiated with a laser beam along each of the lines 15 using, for example, an SD processing device (not shown) different from the laser processing device 1, and a modified region 11 is formed inside the wafer 20 along each of the lines 15 (step S4). Finally, an expanded film (not shown) is expanded by an expansion device (not shown) to widen a crack in the thickness direction of the wafer 20 from the modified region 11 formed inside the semiconductor substrate 21 along each of the lines 15, thereby dividing the wafer 20 into chips for each of the functional elements 22a (step S5). [Actions and effects]

[0062] A laser processing method according to the present embodiment includes: a first step of preparing the wafer 20 including the plurality of functional elements 22a arranged side by side across the street 23, the wafer 20 having a first region in which a surface layer of the street 23 includes the insulating film 24, and a second region in which the surface layer includes the insulating film 24 and the metal pattern 25 on the insulating film 24; a second step of irradiating the street 23 with the predetermined first laser beam L1;and a third step of irradiating the street 23 with the predetermined second laser beam L2 after the second step, wherein the first laser beam L1 is a laser beam having a machining energy for removing a part of the insulating film 24 in the first region to leave the other part, completely removing the metal pattern 25 in the second region, and removing a part of the insulating film 24 in the second region to leave the other part in an irradiation region, and the second laser beam L2 is a laser beam having a machining energy for completely removing the insulating film 24 in the first region and the insulating film 24 in the second region after the second step in the irradiation region.

[0063] In the laser processing method according to the present embodiment, the wafer 20, which has the first region with the insulating film 24 and the second region with the insulating film 24 and the metal pattern 25 on the insulating film 24 in the surface layer of the street 23, is prepared, and the street 23 of the wafer 20 is irradiated with the first laser beam L1, and then the street 23 is irradiated with the second laser beam L2. The first laser beam L1 is the laser beam with the processing energy to remove a part of the insulating film 24 in the first region to leave the other part, to completely remove the metal pattern 25 in the second region, and to remove a part of the insulating film 24 in the second region to leave the other part. In this way, a part of the insulating film 24 is removed in both the first region and the second region when the street 23 is irradiated with the first laser beam L1.Here, a region irradiated with the first laser beam L1 has an uneven shape (frosted glass shape) in a state where a part of the insulating film 24 has been removed by the first laser beam L1. Such an uneven surface has low transmittance to the laser beam. Therefore, even in a case where the second laser beam L2 emitted after irradiation with the first laser beam L1 is the laser beam having the processing energy to completely remove the insulating film 24 in the first region and the insulating film 24 in the second region, the uneven surface with the low transmittance can suppress the transmission of light toward the semiconductor substrate 21 of the wafer 20 made of silicon or the like, and thermal damage to the wafer 20 caused by the laser beam can be suppressed.As described above, it is possible to suppress the thermal damage of the wafer 20 caused by the laser beam and suppress the deterioration of the chip quality by the laser processing method according to the present embodiment.

[0064] The second laser beam L2 may be a laser beam having a processing energy sufficient to excavate a portion of the semiconductor substrate 21 contained in the wafer 20 after the second step. As a result, a portion of the semiconductor substrate 21 is excavated by the second laser beam L2, and it is possible to suppress the occurrence of film peeling in the wafer 20 while reliably performing the groove processing for removing the surface layer.

[0065] The second laser beam L2 may be a laser beam with a processing energy sufficient to hollow the semiconductor substrate 21 by 4 μm or less after the second step. When the hollowing amount is set to 4 μm or less, thermal damage to the wafer 20 caused by the laser beam can be suppressed, and deterioration of chip quality can be suppressed.

[0066] The results of a test conducted to confirm the relationship between laser engraving depth and chip strength are described here. Fig. 11 and Fig. 12 are views showing the test conditions regarding the relationship between the depth of laser engraving and chip strength. Fig. Figure 13 is a view showing the test results regarding the relationship between the depth of the laser groove and the chip strength.

[0067] In this test, after the wafer was ground 20 to 100 µm, laser grooving was performed, then dicing was performed to obtain chips, and then a Fig. 11(a) was performed to measure a chip thickness. As shown in Fig. As shown in Figure 11(a), in the bending strength test, a device surface of a chip was placed on a lower fulcrum side, a back surface of the chip was placed on a side to which a force was applied, and a fracture stress σ was measured when the force was applied to the chip. When the applied force is F, a distance between two lower fulcrums is L2 (mm), a die width is b (mm), and a die thickness is h (mm), the fracture stress σ (Pa) is expressed by the following formula (1). Fracture stress σ(Pa)=3F(L2) / 2bh2

[0068] In this test, as in Fig. As shown in Figure 11(b), the chip thickness (cube thickness) was h = 0.1 mm, the lateral chip width was a = 5 mm, the cube width was b = 5 mm, the pick-up width (distance between the bottom pivot points) was L2 = 2 mm, and the test speed was 1 mm / s. Furthermore, the laser engraving conditions in this test were as shown in Fig. The dicing conditions were set to 1080 nm, 180 mm / s, 0.12 W, and 2.3 µm. This means that the laser engraving width was set to 18 µm, the number of branching points to 4, and the laser engraving depth to different values. Dicing conditions were set to a laser beam wavelength of 1080 nm, a processing speed of 180 mm / s, a power of 0.12 W, and a pulse spacing of 2.3 µm.

[0069] As shown in the test results of Fig. As shown in Figure 13, it was confirmed that the strength of the chip relatively decreases with the increase in the amount of excavation. Furthermore, by comparing the strength required in semiconductor manufacturing with the results, it was found that the problem of product quality deterioration due to a decrease in chip strength can be solved if the amount of trenching can be reduced to as little as 3 μm. As described above, it is necessary to dig the semiconductor substrate 21 by laser engraving from the perspective of suppressing the occurrence of film peeling, but it has been confirmed from the above test results that the influence of HAZ is greatly generated and the chip strength is lowered if the semiconductor substrate is dug excessively.

[0070] The laser machining method according to the present embodiment includes the second step of irradiating the road 23 with the first laser beam L1 to make the insulating films 24 in the first region and the second region uneven, and the third step of irradiating the road 23 with the second laser beam L2 to completely remove the insulating films 24 in the first region and the second region after the second step.

[0071] In the laser processing method according to the present embodiment, the street 23 of the wafer 20 is irradiated with the first laser beam L1 to make the insulating films 24 in the first region and the second region uneven, and then the street 23 is irradiated with the second laser beam L2 to completely remove the insulating films 24 in the first region and the second region. An uneven (frosted) surface of the insulating film 24 has low transmittance to laser beams.Therefore, even in a case where the second laser beam L2 is the laser beam with the processing energy for completely removing the insulating film 24 in the first region and the insulating film 24 in the second region, the uneven surface with low transmittance can suppress the transmitted light toward the semiconductor substrate 21 of the wafer 20 made of silicon or the like, and thermal damage to the wafer 20 by the laser beam can be suppressed. As described above, it is possible to suppress the thermal damage to the wafer 20 caused by the laser beam and suppress the deterioration of chip quality by the laser processing method according to the present embodiment. [The change]

[0072] The present invention is not limited to the above embodiment. For example, the example in which dicing is performed after laser engraving was described in the above embodiment, but the present invention is not limited thereto, and the dicing step may be omitted and the complete cutting may be performed by laser engraving. A laser processing method in which the dicing step is omitted and the complete cutting is performed by laser engraving in a method for producing a bonded wafer will be described below (see Fig. 15). Note that the bonded wafer is described as an example. A laser processing method that eliminates the dicing step and performs the entire cutting process by laser engraving can be performed on a single wafer, excluding the bonded wafer.

[0073] As in Fig. As shown in Figure 15(a), the bonded wafer in which a wafer 720 on a lower surface side and a wafer 820 on an upper surface side are bonded together is manufactured. The wafer 820 is ground or polished so that the semiconductor substrate 821 is 10 μm or less. Moreover, the wafer 720 has an original thickness. A surface layer of one street of the wafer 720 has a region including the insulating film 24 and the metal pattern 25 on the insulating film 24. As shown in Fig. As shown in Figure 15(a), the street of wafer 720 is irradiated with the first laser beam L1, so that the metal structure 25 is completely removed and part of the insulating film 24 is removed. The first laser beam L1 enters from the semiconductor substrate 821 side of wafer 820 and reaches the insulating film 24 of wafer 720.

[0074] Then, as in Fig. As shown in Figure 15(b), the street of the wafer 720 is irradiated with the second laser beam L2, so that the insulating film 24 of the wafer 720 is completely removed. The laser beam L2 enters from the semiconductor substrate 821 side of the wafer 820 and excavates a part of the semiconductor substrate 721 of the wafer 720. That is, the irradiation plane 650 of the second laser beam L2 reaches the semiconductor substrate 721. The extent to which the second laser beam L2 attacks the semiconductor substrate 721 is determined so as not to create a danger zone.

[0075] Then, as in Fig. 15(c), a protective film 900 is applied to the semiconductor substrate 821 side of the wafer 820, and the semiconductor substrate 721 of the wafer 720 is ground or polished so that the irradiation plane 650 is exposed as a groove part.

[0076] Finally, as in Fig. As shown in Figure 15(d), a tape 950 is attached to the side of the semiconductor substrate 721 of the wafer 720 to hold the chip. Expansion processing and machining are performed as necessary.

[0077] Hereinafter, the laser processing method according to the modification described above will be described with reference to a flowchart in Fig. 16. First, a bonded wafer is prepared (step S11, a first step).

[0078] Subsequently, a street is irradiated with the predetermined first laser beam L1 (step S12, a second step). The first laser beam L1 is a laser beam with a processing energy for removing a part of the insulating film 24 in the first region of the wafer 720 to leave the other part, for completely removing the metal pattern 25 in the second region of the wafer 720, and for removing a part of the insulating film 24 in the second region to leave the other part in an irradiation area.

[0079] Subsequently, the road is irradiated with the predetermined second laser beam L2 (step S13, a third step). The second laser beam L2 is a laser beam with a processing energy for completely removing the insulating film 24 in the first region and the insulating film 24 in the second region of the wafer 720 in the irradiation area. The groove processing is completed with the third step.

[0080] Subsequently, the protective film 900 is applied to the semiconductor substrate 821 side of the wafer 820, and the semiconductor substrate 721 of the wafer 720 is ground or polished to expose the irradiation plane 650 as a groove portion (step S14). Finally, the wafer is divided into chips (step S15).

[0081] As described above, the laser machining method according to the modification further includes the fourth step of grinding or polishing the semiconductor substrate to expose the groove formed in the street by the irradiation with the second laser beam L2 after irradiation with the second laser beam L2. With such a laser machining method, complete cutting can be performed by groove machining without performing a dicing step after laser trenching. This allows machining to be performed quickly.

[0082] In addition, as a further modification, for example, before performing the grooving, an insulation pass may be performed to form narrow grooves at both ends of a portion to be grooved by the laser processing device 1. In the Fig. In the example shown in Figure 17, the wafer 20 is prepared (see Fig. 17(a)), narrow grooves 700 are formed at both ends of a section to be grooved (see Fig. 17(b)), and then the first laser beam L1 is emitted to form the frosted glass surface 500 (see Fig. 17(c)), and finally, the second laser beam L2 is emitted so that an irradiation plane 600 reaches a semiconductor substrate (see Fig. 17(d)).

[0083] As described above, a step of irradiating the first laser beam L1 and a step of irradiating the second laser beam L2 are steps for performing processing so that a notch depth in a component surface becomes uniform to suppress a decrease in strength due to HAZ. Here, there is a case where, during laser grooving, film peeling occurs at both ends of the groove depending on the component type. In this regard, as in the modification described above, the narrow grooves 700 are formed at both ends of the portion to be grooved before laser grooving is performed, and the laser grooving is performed after the narrow grooves 700 are formed, whereby the film peeling can be appropriately suppressed while suppressing HAZ.

[0084] In the isolation passage described above (see Fig.17(b)), a film can be removed in a suitable manner, allowing the film to absorb a laser beam without excess or deficiency and suppressing film peeling, for example, by setting the laser conditions with a burst pulse. Note that both ends in the isolation passage must be irradiated with the laser beam, but the two ends can be cut at once by splitting the laser beam into two points. Furthermore, in a case where the influence of the HAZ is also exerted in the isolation passage, the influence of the HAZ can be suppressed by performing the branching in a substantially single array form and performing the irradiation. Reference character list 1 laser processing device 2 support part 3 Irradiation unit 5 Control unit 20 wafers 21 Semiconductor substrate 23 Street 24 Insulating film 25 Metal structure QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] JP 6309341

[0004]

Claims

[1] A laser processing method comprising: a first step of manufacturing a wafer including a plurality of functional elements arranged side by side across a street, the wafer having a first region in which a surface layer of the street includes an insulating film, and a second region in which the surface layer includes an insulating film and a metal pattern on the insulating film; a second step of irradiating the road with a predetermined first laser beam; and a third step of irradiating the road with a predetermined second laser beam after the second step, wherein the first laser beam is a laser beam having a processing energy to remove a part of the insulating film in the first region to leave another part, to completely remove the metal structure in the second region, and to remove a part of the insulating film in the second region to leave another part in an irradiation region, and the second laser beam is a laser beam having a processing energy to completely remove the insulating film in the first region and the insulating film in the second region after the second step in the irradiation region. [2] The laser machining method according to claim 1, wherein the second laser beam is a laser beam having a machining energy for digging a part of the substrate included in the wafer after the second step. [3] The laser machining method according to claim 2, wherein the second laser beam is a laser beam having a machining energy to scribe the substrate by 4 µm or less after the second step. [4] The laser machining method according to claim 2 or 3, further comprising a fourth step of grinding or polishing the substrate to expose a groove formed in the road by irradiation with the second laser beam after the third step. [5] A laser processing method comprising: a first step of manufacturing a wafer including a plurality of functional elements arranged side by side across a street, the wafer having a first region in which a surface layer of the street includes an insulating film, and a second region in which the surface layer includes an insulating film and a metal pattern on the insulating film; a second step of irradiating the road with a laser beam to make the insulating films in the first and second regions uneven; and a third step of irradiating the road with a laser beam to completely remove the insulating films in the first region and the second region after the second step. [6] A laser processing device with: a support member configured to support a wafer including a plurality of functional elements arranged side by side across a street, the wafer having a first region in which a surface layer of the street includes an insulating film, and a second region in which the surface layer includes an insulating film and a metal pattern on the insulating film; an irradiation unit configured to irradiate the road with a laser beam; and a control unit configured to control the irradiation unit, wherein the control unit is configured to perform the following first controlling the irradiation unit in such a way that the road is irradiated with a predetermined first laser beam, and second control, which controls the irradiation unit so that the road is irradiated with a predetermined second laser beam after the first control, the first laser beam is a laser beam having a processing energy for removing a part of the insulating film in the first region while leaving another part, completely removing the metal structure in the second region, and removing a part of the insulating film in the second region while leaving another part in an irradiation region, and the second laser beam is a laser beam having a processing energy to completely remove the insulating film in the first region and the insulating film in the second region after irradiation with the first laser beam in the irradiation region. [7] A laser processing device with: a support member configured to support a wafer including a plurality of functional elements arranged side by side across a street, the wafer having a first region in which a surface layer of the street includes an insulating film, and a second region in which the surface layer includes an insulating film and a metal pattern on the insulating film; an irradiation unit configured to irradiate the road with a laser beam; and a control unit configured to control the irradiation unit, wherein the control unit is configured to perform the following first controlling the irradiation unit such that the road is irradiated with the laser beam to make the insulating films in the first region and the second region uneven, and second control of the irradiation unit such that the road is irradiated with the laser beam to completely remove the insulating films in the first region and the second region after the first control.

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