Laser processing methods and laser processing equipment

Abstract

The laser processing method includes: a first step, which involves preparing a wafer having: a first region on the surface of a dicing track formed by an insulating film, and a second region on the surface formed by an insulating film and a metal structure on the insulating film; a second step, which involves irradiating the dicing track with a predetermined first laser light; and a third step, which involves irradiating the dicing track with a predetermined second laser light after the second step, wherein the first laser light is a laser light with processing energy that removes a portion of the insulating film in the first region, leaving the remaining portion, and completely removes the metal structure in the second region, and removes a portion of the insulating film in the second region, leaving the remaining portion, and the second laser light is a laser light with processing energy that completely removes the insulating film in the first region and the insulating film in the second region after the second step.

Description

Technical Field

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

[0002] In a wafer containing a plurality of functional elements arranged adjacent to each other across dices, insulating films (such as low-k films) and metal structures (such as metal piles and metal pads) are formed on the surface of the dices. In such cases, if a modified region is formed inside the wafer along the cutting line through the dices, and the wafer is wafer-sized by allowing cracks to propagate from the modified region for each functional element, wafer quality degradation, such as film peeling, may occur along the dices. Therefore, when wafer-sized for each functional element, a grooving process is sometimes performed to remove the surface layer of the dices by irradiating the dices with laser light.

[0003] In the technology described in Patent Document 1, multi-point branching laser processing is performed to suppress thermal damage caused by laser light irradiation on the cutting path. By performing multi-point branching laser processing, the effect of thermal damage at the processing point is suppressed. [Previous Technical Documents] [Patent Literature]

[0004] [Patent Document 1] Japanese Patent No. 6309341 Summary of the Invention

[0005] (The problem that the invention aims to solve)

[0006] Here, a dicing channel can include: a region comprising an insulating film and metallic structures on that insulating film forming the surface layer; and a region comprising only an insulating film (a region without metallic structures). In such a case, if the dicing channel is irradiated with laser light under conditions that reliably remove the metallic structures, there is a risk of thermal damage occurring in the regions of the dicing channel surface layer where no metallic structures have been formed. Such thermal damage is a cause of wafer quality degradation.

[0007] Therefore, one aspect of the present invention aims to provide a laser processing method and laser processing apparatus that can suppress the degradation of wafer quality. (Methods used to solve problems)

[0008] One embodiment of the laser processing method of the present invention includes: The first step involves preparing a wafer containing a plurality of functional elements arranged adjacent to each other across dicings, having: a first region on the surface of the dicings formed by an insulating film, and a second region on the surface formed by an insulating film and metal structures on the insulating film; The second step involves irradiating the cutting path with a predetermined first laser beam; and The third step, which follows the second step, involves irradiating the cutting path with a predetermined second laser beam. The first laser beam is a laser beam with processing energy that removes a portion of the insulating film in the first region within the irradiation range, leaving the remaining portion intact, and completely removes the metallic structure in the second region, also removing a portion of the insulating film in the second region while leaving the remaining portion intact. The second laser beam is a laser beam with processing energy that completely removes the insulating film in the first region and the insulating film in the second region after the second process within the irradiation range.

[0009] In one embodiment of the laser processing method of the present invention, a wafer is prepared having a first region whose surface layer is composed of an insulating film, and a second region composed of the insulating film and metal structures on the insulating film. The wafer is then irradiated with a first laser beam through the dicing track, followed by irradiation with a second laser beam. The first laser beam is a laser beam with processing energy that removes a portion of the insulating film in the first region, leaving the remaining portion, completely removes the metal structures in the second region, and removes a portion of the insulating film in the second region, leaving the remaining portion. Thus, after the dicing track is irradiated with the first laser beam, both the first and second regions are removed as part of the insulating film. Here, in the state where a portion of the insulating film is removed by the first laser beam, the area irradiated by the first laser beam forms an uneven surface (frosted glass-like). This uneven surface results in low laser light transmittance. Therefore, even if the second laser light irradiated after the first laser light is set to be a laser light that completely removes the processing energy of the insulating film in the first region and the insulating film in the second region, light transmission towards the substrate of the wafer made of silicon or the like can be suppressed by the low transmittance uneven surface, thus suppressing thermal damage to the wafer caused by the laser light. As described above, if the laser processing method according to one aspect of the present invention is used, thermal damage to the wafer caused by the laser light can be suppressed, and the deterioration of the wafer quality can be suppressed.

[0010] The second laser beam can also be a laser beam that cuts into a portion of the substrate contained in the wafer after the second process. In this way, when a portion of the substrate is cut into by the second laser beam, the grooving process for removing the surface layer can be reliably performed while suppressing film peeling in the wafer.

[0011] The second laser beam can also be a laser beam with processing energy of less than 4μm that cuts into the substrate after the second process. By setting the cut-in depth to less than 4μm, thermal damage to the wafer caused by laser light can be suppressed, thereby suppressing the degradation of wafer quality.

[0012] The laser processing method described above, after the third step, may further include a fourth step: grinding or polishing the substrate by exposing the grooves formed in the cutting path through irradiation by the second laser light. According to such a laser processing method, the cutting step after laser grooving is unnecessary; a full cut can be performed through grooving. This allows for rapid processing.

[0013] One aspect of the laser processing method of the present invention includes: The first step involves preparing a wafer containing a plurality of functional elements arranged adjacent to each other across dicings, having: a first region on the surface of the dicings formed by an insulating film, and a second region on the surface formed by an insulating film and metal structures on the insulating film; The second process involves irradiating the cutting path with laser light to create an uneven surface on the insulating film in regions 1 and 2; and The third process, which follows the second process, involves irradiating the cutting path with laser light to completely remove the insulating film from the first and second regions.

[0014] In one embodiment of the laser processing method of the present invention, a wafer is prepared having: a first region on the surface of the dicing track formed by an insulating film, and a second region formed by an insulating film and metal structures on the insulating film. Laser light is irradiated onto the dicing track of the wafer, and the insulating films in the first and second regions are formed into an uneven surface. Subsequently, laser light is irradiated onto the dicing track, and the insulating films in the first and second regions are completely removed. The surface of the insulating film with the uneven (frosted glass) surface has low transmittance of laser light. Therefore, even if the subsequently irradiated laser light is set to be a laser light with processing energy that completely removes the insulating films in the first and second regions, the low transmittance of the uneven surface can suppress light transmission towards the substrate of the wafer made of silicon or the like, and can suppress thermal damage to the wafer caused by laser light. As described above, if a laser processing method according to one aspect of the present invention is used, thermal damage to the wafer caused by laser light can be suppressed, thereby suppressing the deterioration of the wafer quality.

[0015] One embodiment of the laser processing apparatus of the present invention comprises: The support portion, which supports the wafer, is a wafer containing a plurality of functional elements arranged to be adjacent to each other across dicings, and has: a first region on the surface of the dicings formed by an insulating film, and a second region on the surface formed by an insulating film and metal structures on the insulating film; The irradiation section, which irradiates the cutting path with laser light; and The control unit, which controls the irradiation unit, The control system is configured to implement: The first control controls the irradiation unit so that a predetermined first laser beam is irradiated onto the cutting path; and The second control controls the irradiation unit so that, after the first control, a predetermined second laser beam will irradiate the cutting path. The first laser beam is a laser beam with processing energy that removes a portion of the insulating film in the first region within the irradiation range, leaving the remaining portion intact, and completely removes the metallic structure in the second region, also removing a portion of the insulating film in the second region while leaving the remaining portion intact. The second laser beam is a laser beam that completely removes the processing energy of the insulating film in the first region and the insulating film in the second region after being irradiated by the first laser beam within the irradiation range. In one embodiment of the laser processing apparatus of the present invention, similar to the laser processing method described above, thermal damage to the wafer caused by laser light can be suppressed, thereby suppressing the deterioration of the wafer quality.

[0016] One embodiment of the laser processing apparatus of the present invention comprises: The support portion, which supports the wafer, is a wafer containing a plurality of functional elements arranged to be adjacent to each other across dicings, and has: a first region on the surface of the dicings formed by an insulating film, and a second region on the surface formed by an insulating film and metal structures on the insulating film; The irradiation section, which irradiates the cutting path with laser light; and The control unit, which controls the irradiation unit, The control system is configured to implement: The first control controls the irradiation unit, ensuring that laser light is directed onto the cutting path, causing the insulating film in the first and second regions to form an uneven surface; and The second control controls the aforementioned irradiation unit so that after the first control, laser light is irradiated onto the cutting path, and the insulating film of the first and second regions is completely removed. In one embodiment of the laser processing apparatus of the present invention, similar to the laser processing method described above, thermal damage to the wafer caused by laser light can be suppressed, thereby suppressing the deterioration of the wafer quality. [The effects of the invention]

[0017] According to one embodiment of the present invention, the degradation of the wafer quality can be suppressed. Simple Explanation of the Diagram

[0018] [Figure 1] is a structural diagram of a laser processing apparatus in one embodiment. [Figure 2] is a plan view of a wafer processed by the laser processing apparatus shown in Figure 1. [Figure 3] is a cross-sectional view of a portion of the wafer shown in Figure 2. [Figure 4] is a plan view of a portion of the cutting channel shown in Figure 2. [Figure 5] is a diagram illustrating the occurrence of HAZ (Heat-Affected Zone) caused by grooving. [Figure 6] is a diagram illustrating the grooving process of this embodiment. [Figure 7] is a diagram illustrating the principle of inhibiting the occurrence of HAZ. [Figure 8] is a diagram illustrating one example of the condition settings for removing (excavating) pad areas using path 1. [Figure 9] is a diagram illustrating one example of the condition settings for removing (excavating) pad areas using a 2-path method. [Figure 10] is a diagram illustrating one example of the condition settings for removing (excavating) pad areas using a 2-path method. [Figure 11] is a graph showing the experimental conditions for the relationship between the depth of laser grooving and wafer strength. [Figure 12] is a graph showing the experimental conditions for the relationship between the depth of laser grooving and wafer strength. [Figure 13] is a graph showing the results of an experiment on the relationship between the depth of laser grooving and wafer strength. [Figure 14] is a flowchart of one embodiment of a laser processing method. [Figure 15] is a diagram illustrating the laser processing method of the modified example. [Figure 16] is a flowchart of a modified laser processing method. [Figure 17] is a diagram illustrating laser processing methods for other variations. Implementation

[0019] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Furthermore, identical or equivalent parts in each drawing are indicated by the same symbols, and repeated descriptions are omitted. [Composition of a laser processing device]

[0020] As shown in Figure 1, the laser processing apparatus 1 includes a support unit 2, an irradiation unit 3, an imaging unit 4, and a control unit 5. The laser processing apparatus 1 is a device for performing a grooving process by irradiating the dicing track (described in detail later) of a wafer 20 with laser light L to remove the surface layer of the dicing track. In the following description, the three mutually orthogonal directions are referred to as the X direction, Y direction, and Z direction. For example, the X direction is the first horizontal direction, the Y direction is the second horizontal direction perpendicular to the first horizontal direction, and the Z direction is the vertical direction.

[0021] The support portion 2 supports the wafer 20. The support portion 2 holds the wafer 20 in such a way that the surface of the wafer 20, including the dicing channel, faces the irradiation portion 3 and the imaging portion 4, for example, by adsorbing a thin film (not shown) attached to the wafer 20. For example, the support portion 2 can move along the X and Y directions, and can rotate in the Z direction about a parallel axis.

[0022] The irradiation portion 3 irradiates the laser light L through the cutting channel of the wafer 20 supported by the support portion 2 . The irradiation portion 3 is comprised of: a light source 31 , a plastic optical system 32 , a spectroscope 33 , and a collector portion 34 . Light source 31 emits laser light L. The plastic optics system 32 adjusts the laser light L ejected from the light source 31 . The plastic optics system 32 is at least one comprising: an attenuator that adjusts the output of the laser light L, a beam expander that expands the diameter of the laser light L, and a spatial light modulator that modulates the phase of the laser light L, as an example. When the plastic optical system 32 includes a spatial light modulator, it may also include an imaging optical system that constitutes a telecentric (telecentric) optical system on both sides where the modulation plane of the spatial light modulator is in imaging relationship with the incident pupil plane of the light collector 34 . The spectroscope 33 reflects the laser light L ejected from the plastic optics system 32 so that it is injected into the light collector 34 . The light collector 34 is a cutting channel that collects the laser light L reflected by the spectroscope 33 in the wafer 20 supported by the support 2 .

[0023] The irradiation portion 3 is further comprising a light source 35 , a half mirror 36 and a camera element 37 . Light source 35 emits visible light V1. The semi-reflective mirror 36 reflects the visible light V1 ejected from the light source 35 so that it is injected into the light collector 34 . The dichroic mirror 33 transmits visible light V1 between the semi-reflective mirror 36 and the light collector 34 . The light collector 34 is a cutting channel that collects the reflected visible light V1 by means of a semi-reflective mirror 36 in the wafer 20 supported by the support part 2 . The camera element 37 is the detection of visible light V1 that passes through the light collector 34 , the spectroscope 33 , and the semi-reflector 36 , which are reflected according to the cutting channel of the wafer 20 . In the laser processing device 1 , the control unit 5 causes the light collector 34 to move along the Z direction according to the detection results of the camera element 37 , for example, in such a way that the light collector point of the laser light L will be located in the cutting channel of the wafer 20 .

[0024] The camera part 4 obtains the image data of the cutting channel of the wafer 20 supported by the support part 2 . The camera section 4 is comprising a light source 41 , a semi-reflective mirror 42 , a light collector section 43 , and a camera element 44 . Light source 41 is emitting visible light V2. The semi-reflective mirror 42 reflects the visible light V2 ejected from the light source 41 so that it is injected into the light collector 43 . The light collector 43 is a cutting channel that collects the visible light V2 reflected by the semi-reflective mirror 42 in the wafer 20 supported by the support 2 . The camera element 44 is the detection of visible light V2 that passes through the light collector 43 and the semireflector 42 according to the cutting channel of the wafer 20 .

[0025] The control unit 5 controls the operation of various parts of the laser processing apparatus 1. For example, the control unit 5 controls the irradiation unit 3. The control unit 5 includes a processing unit 51, a memory unit 52, and an input receiving unit 53. The processing unit 51 is a computer device including a processor, memory, storage device, and communication device. In the processing unit 51, the processor executes software (programs) written to the memory, etc., and controls the reading and writing of data in the memory and storage device, as well as communication via the communication device. The memory unit 52, such as a hard drive, stores various types of data. The input receiving unit 53 is an interface for receiving various types of data input from the operator. For example, the input receiving unit 53 may be at least one of a keyboard, mouse, or GUI (Graphical User Interface). [Wafer Composition]

[0026] As shown in Figures 2 and 3, wafer 20 includes a semiconductor substrate 21 and a functional element layer 22. The semiconductor substrate 21 has a surface 21a and a back surface 21b. The semiconductor substrate 21 is, for example, a silicon substrate. A notch 21c indicating the crystal orientation is provided on the semiconductor substrate 21. Alternatively, an orientation flat can be provided on the semiconductor substrate 21 instead of the notch 21c. The functional element layer 22 is formed on the surface 21a of the semiconductor substrate 21. The functional element layer 22 contains a plurality of functional elements 22a. The plurality of functional elements 22a are arranged in two dimensions along the surface 21a of the semiconductor substrate 21. Each functional element 22a is, for example, a light-receiving element such as a light-emitting diode, a light-emitting element such as a laser diode, or a circuit element such as a memory. Alternatively, each functional element 22a may be stacked in multiple layers and thus formed in three dimensions.

[0027] A plurality of dices 23 are formed on wafer 20. The plurality of dices 23 are areas exposed to the outside between adjacent functional elements 22a. That is, the plurality of functional elements 22a are arranged adjacent to each other with respect to the dices 23. For example, the plurality of dices 23 extend in a lattice-like manner between adjacent functional elements 22a for the plurality of functional elements 22a arranged in a matrix. As shown in FIG4, an insulating film 24 and a plurality of metal structures 25 are formed on the surface of the dices 23. The insulating film 24 is, for example, a Low-k film. The metal structures 25 are, for example, metal pads made of aluminum.

[0028] As shown in Figures 2 and 3, the wafer 20 is pre-cut along a plurality of dicing lines 15 to cut each functional element 22a (i.e., to wafer-scale each functional element 22a). Viewed in the thickness direction of the wafer 20, each dicing line 15 passes through each dicing track 23. For example, viewed in the thickness direction of the wafer 20, each dicing line 15 extends through the center of each dicing track 23. Each dicing line 15 is a hypothetical dicing line set on the wafer 20 by the laser processing apparatus 1. Each dicing line 15 can also be an actual dicing line drawn on the wafer 20. [Operation of laser processing equipment and laser processing methods]

[0029] The laser processing apparatus 1 performs a grooving process by irradiating each dicing track 23 with laser light L to remove the surface layer of each dicing track 23. Specifically, the control unit 5 controls the irradiation unit 3 so that the laser light L is irradiated onto each dicing track 23 of the wafer 20 supported by the support unit 2, and the control unit 5 controls the support unit 2 so that the laser light L moves relative to each dicing track 23.

[0030] For example, in the case of grooving where blade cutting is performed, it is necessary to completely remove the surface layer of the cutting path 23 from the cutting line. Here, the surface of the cutting channel 23 has: The area formed solely by insulating film 24 (hereinafter referred to as the first area); and The region formed by the insulating film 24 and the metal structure 25 on the insulating film 24 (hereinafter referred to as the second region). For example, the surface layer of the cleavage 23 of the wafer 20 shown in the left image of Figure 5(a) (the area of ​​cleavage 400) is composed only of the Low-k film 242 and the SiN / SiO2 film 241 of the insulating film 24, representing the first region. Similarly, the surface layer of the cleavage 23 of the wafer 20 shown in the left image of Figure 5(b) (the area of ​​cleavage 400) is composed of the Low-k film 242 and the SiN / SiO2 film 241 of the insulating film 24 and the metal structure 25 (metal pad) on the insulating film 24, representing the second region. For a wafer 20 having both the first and second regions, if unrelated regions are processed under common grooving conditions, thermal damage to the wafer 20 may become a problem.

[0031] That is, in order to completely remove the surface layer of the dicing 23 in any region of the wafer 20, the processing energy of the laser light L for grooving needs to be set so that the second region, which is composed of the insulating film 24 and the metal structure 25 on the insulating film 24, is drilled into the interface of the semiconductor substrate 21 (see the right figure of Figure 5(b)). The absorption rate of the laser wavelength is greater in the metal structure 25 than in the insulating film 24, so most of the energy in the second region is absorbed by the metal structure 25. Therefore, in order to remove the insulating film 24 under the metal structure 25, the processing energy of the laser light L needs to be increased. However, if the laser light L with such increased processing energy is used to perform grooving on the first region composed only of the insulating film 24, there will be too much energy in the first region, as shown in the right figure of Figure 5(a), which will over-drill into the semiconductor substrate 21, creating a HAZ (Heat-Affected Zone), and there will be a problem of reduced strength of the wafer 20 due to thermal damage.

[0032] The example shown in Figure 5 illustrates the occurrence of HAZ when the conditions for wafer 20 and laser grooving are as follows. (Conditions for wafer 20) Wafer size: 12 inch, wafer thickness: 300 μm, wafer size: 5 mm, dicing width 400: 60 μm, pattern thickness (insulating film 24 thickness): 8 μm, metal structure 25 thickness: 1 μm. (Conditions for laser grooving) For cutting with a blade, a 55μm wide groove is formed. The laser light L has a wavelength of 515μm, a pulse width of 600fs, a focus position on the device surface, 21 branch points, a pulse pitch of 0.5μm, a processing energy of 9.9μJ, a fluence / point of 0.85J / cm2, and 2 scan paths.

[0033] The term "fluence / point" here refers to the pulse energy per predetermined area, representing the value at each point (1 point) of the divergence. Additionally, as shown in Figure 5, the Low-k film 242 of the insulating film 24 is, for example, provided with wiring 300.

[0034] To address the aforementioned issues, the laser processing method of this embodiment divides the irradiation of the laser light into the cutting path 23 during the grooving process into two steps. Specifically, the laser processing method implemented by the laser processing apparatus 1 includes: The process of irradiating the cutting path 23 with a predetermined first laser beam (the second process); and After the process of irradiating the first laser light, the process of irradiating the cutting channel 23 with a predetermined second laser light (the third process) is carried out. In order to implement these processes, the control unit 5 is configured to perform: The first control of the irradiation unit 3 is to control the irradiation of the first laser beam to be irradiated onto the cutting channel 23 in a predetermined manner; and After the first control, the second control of the irradiation unit 3 is controlled in such a way that a predetermined second laser beam will be irradiated onto the cutting channel 23. Furthermore, the first laser beam is a laser beam designed to remove a portion of the insulating film 24 in the first region within the irradiation range, leaving the remaining portion, and to completely remove the metal structure 25 in the second region, as well as a portion of the insulating film 24 in the second region, leaving the remaining portion. The second laser beam is a laser beam designed to completely remove the processing energy from the insulating film 24 in both the first and second regions after being irradiated by the first laser beam.

[0035] Figure 6 is a diagram illustrating the grooving process of this embodiment. Figure 6(a) shows the illumination of the first laser light L1 in the first region (see the center view of Figure 6(a)) and the illumination of the second laser light L2 (see the right view of Figure 6(a)). Figure 6(b) shows the illumination of the first laser light L1 in the second region (see the center view of Figure 6(b)) and the illumination of the second laser light L2 (see the right view of Figure 6(b)).

[0036] The first laser beam L1, as shown in the central view of Figure 6(a), is configured within the irradiation range to remove a portion of the insulating film 24 in the first region, leaving the remaining portion with processing energy. Furthermore, as shown in the central view of Figure 6(b), the first laser beam L1 is configured within the irradiation range to completely remove the metal structure 25 in the second region, and also remove a portion of the insulating film 24 in the second region, leaving the remaining portion with processing energy. Here, "removing a portion of the insulating film 24, leaving the remaining portion" means within the irradiation range, not the entire insulating film 24, but only a portion, leaving the remaining portion intact. Similarly, "completely removing the metal structure 25" means within the irradiation range, removing the entire metal structure 25. Additionally, "completely removing the metal structure 25" may also include cases where only a small amount of the metal structure 25 remains, negligible in its functionality, but almost the entire metal structure 25 is removed.

[0037] As shown in the central view of Figure 6(a), in the first region after being irradiated by the first laser light L1, a portion of the insulating film 24 (here, a portion of the SiN / SiO2 film 241) is removed by the first laser light L1, and the surface irradiated by the first laser light L1 becomes a frosted glass surface 500 with an uneven texture. Furthermore, as shown in the central view of Figure 6(b), in the second region after being irradiated by the first laser light L1, the metal structure 25 is completely removed by the first laser light L1, and a portion of the insulating film 24 (here, the entire SiN / SiO2 film 241 and a portion of the Low-k film 242) is removed, and the surface irradiated by the first laser light L1 becomes a frosted glass surface 550 with an uneven texture. Thus, the process of irradiating the first laser light L1 (the second process) is a process in which the insulating film 24 of the first region and the second region is formed into a raised and recessed shape by irradiating the cutting channel 23 with the first laser light L1. That is, the control unit 5 performs the first control of the irradiation unit 3 in such a way that the first laser light L1 is irradiated onto the cutting channel 23, so that the insulating film 24 of the first region and the second region is formed into a raised and recessed shape. The frosted glass surface 500 and the frosted glass surface 550 will be described later.

[0038] The second laser beam L2, as shown in the right-hand diagram of Figure 6(a), is set to completely remove the processing energy of the insulating film 24 in the first region after being irradiated by the first laser beam L1 within the irradiation range. Similarly, the second laser beam L2, as shown in the right-hand diagram of Figure 6(b), is set to completely remove the processing energy of the insulating film 24 in the second region after being irradiated by the first laser beam L1 within the irradiation range. Here, "completely remove the insulating film 24" means removing the entire insulating film 24 within the irradiation range. Alternatively, "completely remove the insulating film 24" may also include cases where only a small amount of the insulating film 24 remains, regardless of its functionality, but almost the entire insulating film 24 is removed.

[0039] As shown in the right-hand diagrams of Figures 6(a) and 6(b), the second laser beam L2 is the processing energy used to penetrate a portion of the semiconductor substrate 21 of the wafer 20 after irradiation by the first laser beam L1. That is, the irradiation surface 600 of the second laser beam L2 in the first region (see Figure 6(a)) and the irradiation surface 650 of the second laser beam L2 in the second region (see Figure 6(b)) both reach the semiconductor substrate 21. Thus, the process of irradiating the second laser beam L2 (the third process) is a process of completely removing the insulating film 24 of the first and second regions by irradiating the dicing 23 with the laser beam L2. In other words, after the first control described above, the control unit 5 performs the second control of the irradiation unit 3 by controlling the second laser beam L2 to irradiate the dicing 23, so that the insulating film 24 of the first and second regions is completely removed. The second laser light L2 can also be set to a processing energy that cuts the semiconductor substrate 21 of the wafer 20 after irradiation by the first laser light L1 to a depth of less than 4μm. By setting the depth to less than 4μm, thermal damage to the wafer 20 caused by the second laser light L2 can be suppressed, thereby suppressing the degradation of the wafer quality.

[0040] The grooving process in Figure 6 is carried out, for example, under the conditions of wafer 20 and laser grooving. (Conditions for wafer 20) Wafer size: 12 inch, wafer thickness: 300 μm, wafer size: 5 mm, dicing width 400: 60 μm, pattern thickness (insulating film 24 thickness): 8 μm, metal structure 25 thickness: 1 μm. (Laser grooving conditions for the process of irradiating the first laser light L1 (the second process)) For cutting with a blade, a 55μm wide groove is formed. The wavelength of the first laser L1 is 515μm, the pulse width is 600fs, the light collection position is on the device surface, the number of branches is 21, the pulse spacing is 0.5μm, the processing energy is 4.1μJ, the fluid / point is 0.35J / cm2, and the number of scans is 1 path. (Laser grooving conditions for the process of irradiating the second laser light L2 (the third process)) For cutting with a blade, a 55μm wide groove is formed. The wavelength of the second laser L2 is 515μm, the pulse width is 600fs, the light collection position is on the device surface, the number of branches is 21, the pulse spacing is 0.5μm, the processing energy is 9.9μJ, the fluid / point is 0.85J / cm2, and the number of scans is 2 paths.

[0041] Next, referring to Figure 7, we will explain the possible principle of suppressing HAZ formation through the grooving process shown in Figure 6. Figure 7 is a diagram illustrating the principle of suppressing HAZ formation. Figure 7 shows the grooving process in the first region of wafer 20.

[0042] As shown in Figure 7(a), a first laser light L1 is used to irradiate a portion of the insulating film 24 in the first region, leaving the remaining processing energy (e.g., 4.1 μJ) in the other parts. Since this first laser light L1 has weak processing energy, the occurrence of HAZ in the semiconductor substrate 21 due to light transmission is suppressed. Then, as shown in Figure 7(b), a portion of the insulating film 24 near the light-collecting point (here, a portion of the SiN / SiO2 film 241) is removed by the first laser light L1, and the surface irradiated by the first laser light L1 becomes a frosted glass surface 500 with an uneven (frosted glass) shape. The so-called frosted glass surface 500 here is a geometric surface whose direction changes randomly with respect to the normal of the optical surface. In such a frosted glass surface 500, the transmittance of the laser light decreases because light is randomly refracted or scattered. Alternatively, in such a frosted glass surface 500, the absorption rate of the laser light increases due to shape changes and color variations. Therefore, the laser light irradiated onto the frosted glass surface 500 is difficult to reach the semiconductor substrate 21.

[0043] Furthermore, as shown in FIG7(c), a second laser light L2, with processing energy (e.g., 9.9 μJ) to completely remove the insulating film 24 of the first region, is irradiated onto the frosted glass surface 500 that has been irradiated with the first laser light L1. This second laser light L2 is the laser light with processing energy that would normally create a HAZ in the semiconductor substrate 21 due to its deep penetration depth (see the right figure in FIG5(a)). However, since the second laser light L2 is irradiated onto the frosted glass surface 500, which has low laser light transmittance, the situation where the semiconductor substrate 21 is excessively penetrated and a HAZ is created by the second laser light L2 is suppressed, as shown in FIG7(d). Specifically, the penetration depth caused by the second laser light L2 is, for example, set to 4 μm or less.

[0044] Here, the second region is composed of an insulating film 24 and a metal structure 25 on the insulating film 24, which is different from the first region composed only of the insulating film 24. However, it can be grooved using the same grooving processing conditions as the first region (i.e., the first laser light L1 and the second laser light L2). That is, in the second region, when irradiated by the first laser light L1 with relatively weak processing energy, the metal structure 25 with high absorption rate is still easier to remove even with weak processing energy. Therefore, in the second region, it can also be set to a state where the first laser light L1 (completely removes the metal structure 25) removes a portion of the insulating film 24 in the second region, leaving the remaining portion, i.e., forming a frosted glass surface 550 (see the central view of Figure 6(b)). Furthermore, by irradiating the frosted glass surface 550, which has been irradiated with the first laser light L1, with a processing energy (e.g., 9.9 μJ) that completely removes the insulating film 24 in the second region, the insulating film 24 can be appropriately removed while suppressing the occurrence of HAZ, just like in the first region.

[0045] Secondly, the conditions for the grooving process will be explained in detail. Here, "condition settings" refers to the Fluence / point settings of the first laser beam L1 and the second laser beam L2. The Fluence / points of the first laser beam L1 and the second laser beam L2 are set to meet the conditions for grooving in both the first and second regions, as described above. Specifically, the Fluence / point of the first laser beam L1 is set such that it can remove a portion of the insulating film 24 in the first region within its irradiation range, leaving the remaining portion, and completely remove the metal structure 25 in the second region, and also remove a portion of the insulating film 24 in the second region, leaving the remaining portion. Similarly, the Fluence / point of the second laser beam L2 is set such that it can completely remove the insulating film 24 in both the first and second regions within its irradiation range, further suppressing the occurrence of HAZ (Hyperthermal Adhesion Zone).

[0046] Figure 8 illustrates an example of the condition settings for removing (excavating) the pad area where the metal structure 25 is formed using path 1. In Figure 8, "no Si reached" means that a portion of the insulating film 24 is removed while the rest remains; "to Si reached" means that the insulating film 24 is completely removed without HAZ occurring; and "to Si (HAZ) reached" means that the insulating film 24 is completely removed and HAZ occurs. Furthermore, in Figure 8, "not excavated" indicates a state where the metal structure 25 is not completely removed; "partially excavated" indicates a state where a portion of the metal structure 25 is removed; "excavated" indicates a state where the metal structure 25 is completely removed, a portion of the insulating film 24 is removed, and the remaining portion remains; "excavated to Si" indicates a state where the metal structure 25 and the insulating film 24 are completely removed, but no HAZ occurs; and "excavated to Si (HAZ)" indicates a state where the metal structure 25 and the insulating film 24 are completely removed, and a HAZ occurs. Figure 8(a) illustrates the condition settings for the first laser light L1. Figure 8(b) illustrates the condition settings for the second laser light L2.

[0047] In Figure 8(a), for the first laser beam L1, the states of the first region (referred to as "film-only region" in Figure 8) and the second region (referred to as "pad region" in Figure 8) after grooving are shown according to each Fluence / point reference. Furthermore, an increase in the Fluence / point reference means that the Fluence / point value increases. As mentioned above, the Fluence / point of the first laser beam L1 is set to "remove a portion of the insulating film 24 in the first region within the irradiation range, leaving the remaining portion, and completely remove the metal structure 25 in the second region, and remove a portion of the insulating film 24 in the second region, leaving the remaining portion." Therefore, in the example shown in Figure 8(a), the Fluence / point reference of the first laser beam L1 is set to 4.

[0048] In Figure 8(b), for the second laser light L2, the states of the first region (referred to as "film-only region" in Figure 8) and the second region (referred to as "pad region" in Figure 8) after grooving are shown according to each Fluence / point. Furthermore, the results in Figure 8(b) show the state of the wafer 20 after grooving with the first laser light L1 with the Fluence / point reference set according to Figure 8(a), when grooving is performed with the second laser light L2 with each Fluence / point reference. As mentioned above, the Fluence / point of the second laser light L2 is set to "completely remove the insulating film 24 of the first region and the insulating film 24 of the second region within the irradiation range, and further suppress the occurrence of HAZ." Therefore, in the example shown in Figure 8(b), the Fluence / point of the second laser light L2 is set to 7. Furthermore, the desired results can be obtained even when the Fluence / point reference of the second laser L2 is set to 8, but it is ideal to select the minimum reference level for the Fluence / point reference.

[0049] Figures 9 and 10 illustrate one example of the condition settings for removing (excavating) the pad area where the metal structure 25 is formed using a two-path method. In Figures 9 and 10, "no Si reached" means that a portion of the insulating film 24 is removed while the rest remains; "reached to Si" means that the insulating film 24 is completely removed without HAZ occurring; and "reached to Si (HAZ)" means that the insulating film 24 is completely removed and HAZ occurs. Furthermore, in Figures 9 and 10, "not excavated" indicates that the metal structure 25 has not been completely removed; "partially excavated" indicates that a portion of the metal structure 25 has been removed; "excavated" indicates that the metal structure 25 has been completely removed, a portion of the insulating film 24 has been removed, and the remaining portion remains; "excavated to Si" indicates that the metal structure 25 and the insulating film 24 have been completely removed, and no HAZ has occurred; "excavated to Si (HAZ)" indicates that the metal structure 25 and the insulating film 24 have been completely removed, and a HAZ has occurred. Figure 9(a) illustrates the condition settings for the first path of the first laser light L1; Figure 9(b) illustrates the condition settings for the second path of the first laser light L1; and Figure 10 illustrates the condition settings for the second laser light L2.

[0050] In Figure 9(a), for the first laser beam L1 of the first path, the state of the first region (referred to as "film-only region" in Figure 8) and the state of the second region (referred to as "pad region" in Figure 8) after grooving are shown according to each Fluence / point reference. The pad region is removed by two paths, so in the example shown in Figure 9(a), the Fluence / point reference of the first path of the first laser beam L1 is set to 4 (removing only a portion of the metal structure 25).

[0051] In Figure 9(b), for the first laser beam L1 of the second path, the state of the first region (referred to as "film-only region" in Figure 8) and the state of the second region (referred to as "pad region" in Figure 8) after grooving are shown according to each Fluence / point. Furthermore, the results in Figure 9(b) show the state of the wafer 20 subjected to grooving with the first laser beam L1 of the first path of the Fluence / point set according to Figure 9(a), when grooving is performed with the first laser beam L1 of the second path of each Fluence / point. As described above, the Fluence / point of the first laser beam L1 is set to "remove a portion of the insulating film 24 of the first region within the irradiation range, leaving the remaining portion, and completely remove the metal structure 25 of the second region, and remove a portion of the insulating film 24 of the second region, leaving the remaining portion." Therefore, in the example shown in Figure 9(b), the Fluence / point reference for the second path of the first laser beam L1 is set to 5.

[0052] In Figure 10, for the second laser light L2, the states of the first region (referred to as "film-only region" in Figure 8) and the second region (referred to as "pad region" in Figure 8) after grooving are shown according to each Fluence / point reference. Furthermore, the results in Figure 10 show the state of the wafer 20 after grooving with the first laser light L1 of the second path with the Fluence / point reference set according to Figure 9(b), when grooving is performed with the second laser light L2 with each Fluence / point reference. As mentioned above, the Fluence / point of the second laser light L2 is set to "completely remove the insulating film 24 of the first region and the insulating film 24 of the second region within the irradiation range, and further suppress the occurrence of HAZ." Therefore, in the example shown in Figure 10, the Fluence / point reference of the second laser light L2 is set to 7. Furthermore, the desired results can be obtained even when the Fluence / point reference of the second laser L2 is set to 8, but it is ideal to select the minimum reference level for the Fluence / point reference.

[0053] Next, the laser processing method will be explained with reference to the flowchart in FIG14. First, a wafer 20 is prepared (step S1, first process). The wafer 20 is, as described above, a wafer containing a plurality of functional elements 22a arranged adjacent to each other with cleavage 23, and having: a first region on the surface of the cleavage 23 formed by an insulating film 24, and a second region on the surface formed by the insulating film 24 and metal structures 25 on the insulating film 24.

[0054] Next, the laser processing apparatus 1 irradiates the cutting path 23 with a predetermined first laser light L1 (step S2, second process). The first laser light L1 is, as described above, a laser light with processing energy that removes a portion of the insulating film 24 in the first region within the irradiation range, leaving the remaining portion, and completely removes the metal structure 25 in the second region, and removes a portion of the insulating film 24 in the second region, leaving the remaining portion.

[0055] Next, the cutting path 23 is irradiated with a predetermined second laser beam L2 by the laser processing apparatus 1 (step S3, third process). The second laser beam L2 is, as described above, a laser beam that completely removes the processing energy of the insulating film 24 in the first region and the insulating film 24 in the second region after the second process within the irradiation range. Through this third process, the grooving process is completed.

[0056] Next, for example, using an SD processing apparatus (not shown) different from the laser processing apparatus 1, laser light is irradiated onto the wafer 20 along each cut line 15, thereby forming modified regions 11 along each cut line 15 inside the wafer 20 (step S4). Finally, in the expansion apparatus (not shown), by expanding the expansion film (not shown), cracks extend along each cut line 15 from the modified regions 11 formed inside the semiconductor substrate 21 to the thickness direction of the wafer 20, and the wafer 20 is wafered according to each functional element 22a (step S5). [Functions and Effects]

[0057] The laser processing method of this embodiment includes: In the first step, a wafer 20 is prepared, which contains a plurality of functional elements 22a arranged to be adjacent to each other across dicing 23. The wafer 20 has: a first region on the surface of the dicing 23 formed by an insulating film 24, and a second region on the surface formed by the insulating film 24 and metal structures 25 on the insulating film 24. In the second step, the cutting path 23 is irradiated with a predetermined first laser beam L1; and The third step, following the second step, involves irradiating the cutting path 23 with a predetermined second laser beam L2. The first laser beam L1 is a laser beam with processing energy that removes a portion of the insulating film 24 in the first region within the irradiation range, leaving the remaining portion intact, and completely removes the metal structure 25 in the second region, also removing a portion of the insulating film 24 in the second region while leaving the remaining portion intact. The second laser light L2 is the laser light with processing energy that completely removes the insulating film 24 in the first region and the insulating film 24 in the second region after the second process within the irradiation range.

[0058] In the laser processing method of this embodiment, a wafer 20 is prepared, which has a first region on the surface of a dicing 23 formed by an insulating film 24, and a second region formed by the insulating film 24 and metal structures 25 on the insulating film 24. A first laser light L1 is irradiated onto the dicing 23 of the wafer 20, and then a second laser light L2 is irradiated onto the dicing 23. The first laser light L1 is a laser light configured to remove a portion of the insulating film 24 in the first region, leaving the remaining portion, and completely remove the metal structures 25 in the second region, as well as remove a portion of the insulating film 24 in the second region, leaving the remaining portion. Thus, when the dicing 23 is irradiated with the first laser light L1, both the first and second regions are removed as part of the insulating film 24. Here, when a portion of the insulating film 24 is removed by the first laser light L1, the region irradiated by the first laser light L1 forms an uneven (frosted glass) shape. Such an uneven surface results in low laser light transmittance. Therefore, even if the second laser light L2, which is irradiated after the first laser light L1, is set to be a laser light that completely removes the processing energy of 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 light transmission toward the semiconductor substrate 21 of the wafer 20 made of silicon or the like, and suppress thermal damage to the wafer 20 caused by laser light. As described above, according to the laser processing method of this embodiment, thermal damage to the wafer 20 caused by laser light can be suppressed, and the deterioration of the wafer quality can be suppressed.

[0059] The second laser light L2 is a laser light that can also be used to process a portion of the semiconductor substrate 21 contained in the wafer 20 after the second process. In this way, a portion of the semiconductor substrate 21 is drilled in by the second laser light L2, and the grooving process for removing the surface layer can be reliably performed while suppressing film peeling in the wafer 20.

[0060] The second laser beam L2 can also be a laser beam with processing energy of less than 4μm that drills into the semiconductor substrate 21 after the second process. By setting the drilling depth to less than 4μm, thermal damage to the wafer 20 caused by laser beams can be suppressed, thereby suppressing the degradation of wafer quality.

[0061] Here, the results of the tests conducted to confirm the relationship between the depth of laser cutting (laser groove depth) and wafer strength are explained. Figures 11 and 12 are graphs showing the test conditions for the relationship between laser groove depth and wafer strength. Figure 13 is a graph showing the test results for the relationship between laser groove depth and wafer strength.

[0062] In this experiment, after the wafer 20 was ground to 100 μm, laser grooving was performed, and then it was cut. After wafer fabrication, a flexural strength test as shown in Figure 11(a) was performed to determine the strength of the wafer. As shown in Figure 11(a), in the flexural strength test, the device face of the wafer was placed on the lower support side, and the back face of the wafer was placed on the force application side. The destructive stress σ when force was applied to the wafer was measured. When the applied force is set as F, the distance between the two lower support points is set as L2 (mm), the grain width is set as b (mm), and the grain thickness is set as h (mm), the destructive stress σ (Pa) is expressed by the following formula (1). The destructive stress σ(Pa) = 3F(L2) / 2bh2･･･(1)

[0063] In this experiment, as shown in Figure 11(b), the wafer thickness (grain thickness) was h = 0.1 mm, the wafer width was a = 5 mm, the grain width was b = 5 mm, the bearing width (interval between lower support points) was L2 = 2 mm, and the test speed was set to 1 mm / s. Furthermore, the laser grooving conditions for this experiment were set as shown in Figure 12. That is, the laser grooving width was set to 18 μm, and the number of branching points was set to 4, representing different cutting depths (laser grooving depths). The cutting conditions were: laser wavelength 1080 nm, processing speed 180 mm / sec, output 0.12 W, and pulse spacing 2.3 μm.

[0064] As shown in the test results of Figure 13, it can be confirmed that the larger the depth of cut, the relatively lower the wafer strength. Comparing the required strength for semiconductor manufacturing with the results, it can be seen that if the depth of cut can be suppressed to 3μm, the problem of product quality deterioration caused by reduced wafer strength can be solved. As mentioned above, from the perspective of suppressing film peeling, laser grooving is required to cut into the semiconductor substrate 21. However, the test results above confirm that if the depth of cut is too large, the effect of HAZ will occur strongly, and the wafer strength will decrease.

[0065] The laser processing method of this embodiment includes: The second process involves irradiating the cutting path 23 with a first laser light L1 to form an uneven insulating film 24 in the first region and the aforementioned second region; and After the second process, the third process completely removes the insulating film 24 of the first and second regions by irradiating the cutting path 23 with the second laser light L2.

[0066] In the laser processing method of this embodiment, for the wafer 20, a first laser light L1 is irradiated through the dicing 23, and the insulating film 24 in the first and second regions is formed into an uneven shape. Then, a second laser light L2 is irradiated through the dicing 23, and the insulating film 24 in the first and second regions is completely removed. The surface of the insulating film 24 with the uneven (frosted glass) shape has low laser light transmittance. Therefore, even if the second laser light L2 is set to be a laser light with processing energy that completely removes the insulating film 24 in the first and second regions, the uneven surface with low transmittance can suppress light transmission towards the semiconductor substrate 21 of the wafer 20 made of silicon or the like, and can suppress thermal damage to the wafer 20 caused by laser light. As described above, according to the laser processing method of this embodiment, thermal damage to the wafer 20 caused by laser light can be suppressed, and the deterioration of wafer quality can be suppressed. [Variation Example]

[0067] This invention is not limited to the embodiments described above. For example, the embodiments described above illustrate dicing after laser grooving, but this is not a limitation; the dicing process can also be omitted, and full dicing can be performed by laser grooving. Hereinafter, a laser processing method for performing full dicing by laser grooving during the fabrication of a laminated wafer, omitting the dicing process, will be described with reference to FIG15. Furthermore, although a laminated wafer is described as an example, the laser processing method for performing full dicing by laser grooving, omitting the dicing process, can also be implemented for individual wafers that are not laminated wafers.

[0068] As shown in Figure 15(a), a bonding wafer is prepared to be bonded between the lower wafer 720 and the upper wafer 820. The semiconductor substrate 821 of wafer 820 is ground and polished to below 10 μm. Wafer 720 is in its original thickness state. The surface of the dicing track of wafer 720 has a region composed of an insulating film 24 and metal structures 25 on the insulating film 24. At this time, as shown in Figure 15(a), a first laser light L1 is irradiated onto the dicing track of wafer 720, completely removing the metal structures 25 and a portion of the insulating film 24. The first laser light L1 enters from the semiconductor substrate 821 side of wafer 820 and reaches the insulating film 24 of wafer 720.

[0069] Next, as shown in Figure 15(b), the dicing ridge of wafer 720 is irradiated with a second laser beam L2 to completely remove the insulating film 24 from wafer 720. Laser beam L2 enters from the semiconductor substrate 821 side of wafer 820 and penetrates a portion of the semiconductor substrate 721 of wafer 720. That is, the irradiation surface 650 of the second laser beam L2 reaches the semiconductor substrate 721. The amount of penetration of the second laser beam L2 into the semiconductor substrate 721 is set to a range where no HAZ occurs.

[0070] Next, as shown in FIG15(c), a protective film 900 is attached to the semiconductor substrate 821 side of the wafer 820, and the semiconductor substrate 721 of the wafer 720 is ground and polished in such a way that the irradiated surface 650 of the trench portion is exposed.

[0071] Finally, as shown in Figure 15(d), adhesive tape 950 is attached to the semiconductor substrate 721 side of wafer 720 to hold the wafer. As needed, a scaling process is performed to waferize the wafer.

[0072] Next, the laser processing method for the above-mentioned modified example will be explained with reference to the flowchart in Figure 16. First, prepare the bonding wafer (step S11, first process).

[0073] Next, the dicing path is irradiated with a predetermined first laser light L1 (step S12, second process). The first laser light L1 is a laser light with processing energy that removes a portion of the insulating film 24 in the first region of the wafer 720 within the irradiation range, leaving the remaining portion, and completely removes the metal structure 25 in the second region of the wafer 720, and removes a portion of the insulating film 24 in the second region, leaving the remaining portion.

[0074] Next, the dicing path is irradiated with a predetermined second laser beam L2 (step S13, third process). The second laser beam L2 is a laser beam with processing energy that completely removes the insulating film 24 in the first region and the insulating film 24 in the second region of the wafer 720 within the irradiation range. Through this third process, the grooving process is completed.

[0075] Next, a protective film 900 is attached to the semiconductor substrate 821 side of the wafer 820, and the semiconductor substrate 721 of the wafer 720 is ground and polished so that the irradiation surface 650 of the trench portion is exposed (step S14). Finally, wafer fabrication is performed (step S15).

[0076] As described above, the modified laser processing method further includes a fourth step after irradiation by the second laser light L2: grinding or polishing the semiconductor substrate in such a way that the grooves formed in the dicing path by the irradiation of the second laser light L2 are exposed. According to this laser processing method, the dicing process after laser grooving is unnecessary; a full cut can be performed through grooving. This allows for rapid processing.

[0077] Furthermore, as another variation, for example, before performing the grooving process, an isolation path can be implemented by forming fine trenches at both ends of the predetermined grooving location using the laser processing apparatus 1. In the example shown in FIG17, a wafer 20 is prepared (see FIG17(a)), fine trenches 700 are formed at both ends of the predetermined grooving location (see FIG17(b)), then a first laser light L1 is irradiated to form a frosted glass surface 500 (see FIG17(c)), and finally a second laser light L2 is irradiated so that the irradiated surface 600 reaches the semiconductor substrate (see FIG17(d)).

[0078] As described above, the processes of irradiating the first laser light L1 and the second laser light L2 are performed in a manner that ensures a uniform depth of drilling within the device surface, thereby suppressing intensity reduction caused by HAZ. However, depending on the type of device, there is a possibility that film peeling occurs at both ends of the groove during laser grooving. In this case, as in the modified example described above, fine grooves 700 are formed at both ends of the predetermined grooving location before laser grooving. After forming the fine grooves 700, laser grooving is performed, thereby suppressing HAZ while appropriately suppressing film peeling.

[0079] In the isolation path described above (refer to Figure 17(b)), burst pulses are used, for example, to adjust the laser conditions, thereby ensuring that the laser light is absorbed into the film without being too much or too little, thus suppressing film peeling while appropriately removing the film. Furthermore, while the isolation path requires separate laser irradiation at both ends, the two ends can be cut off at once by splitting the laser light into two points. Moreover, when the HAZ effect occurs in the isolation path, irradiation is performed in a roughly single-array pattern, thereby suppressing the HAZ effect.

[0080] 1: Laser processing equipment 2: Support section 3:Irradiation part 5: Control Department 20: Wafer 21: Semiconductor substrate 23: Cutting Track 24: Insulating film 25: Metal structures

Claims

1. A laser processing method, characterized by comprising: a first step of preparing a wafer containing a plurality of functional elements arranged adjacent to each other across dicings, having: a first region on the surface of the dicings formed by an insulating film, and a second region on the surface formed by an insulating film and metal structures on the insulating film; a second step of irradiating the dicings with a predetermined first laser light; and a third step of irradiating the dicings with a predetermined second laser light after the second step, wherein the first laser light is a laser light with processing energy that removes a portion of the insulating film in the first region within the irradiation range, leaving the remaining portion, and completely removes the metal structures in the second region, and removes a portion of the insulating film in the second region, leaving the remaining portion, and the second laser light is a laser light with processing energy that completely removes the insulating film in the first region and the insulating film in the second region after the second step.

2. The laser processing method as described in claim 1, wherein, The aforementioned second laser light is the laser light used to drill into a portion of the substrate contained in the aforementioned wafer after the aforementioned second process.

3. The laser processing method as described in claim 2, wherein, The aforementioned second laser light is a laser light with processing energy that cuts into the aforementioned substrate by less than 4μm after the aforementioned second process.

4. The laser processing method as described in claim 2 or 3, wherein, Following the aforementioned third step, a fourth step is further included: grinding or polishing the aforementioned substrate in such a way that the grooves formed on the aforementioned cutting path are exposed by the aforementioned second laser light.

5. A laser processing method, characterized by comprising: a first step of preparing a wafer containing a plurality of functional elements arranged adjacent to each other across dicings, having: a first region on the surface of the dicings formed by an insulating film, and a second region on the surface formed by an insulating film and a metal structure on the insulating film; a second step of forming the insulating film of the first region and the second region into an uneven shape by irradiating the dicings with laser light; and a third step of completely removing the insulating film of the first region and the second region after the second step by irradiating the dicings with laser light.

6. A laser processing apparatus, characterized by comprising: a support portion for supporting a wafer, the wafer containing a plurality of functional elements arranged adjacent to each other across dicing tracks, having: a first region on the surface of the dicing tracks formed by an insulating film, and a second region on the surface formed by an insulating film and metal structures on the insulating film; an irradiation portion for irradiating the dicing tracks with laser light; and a control portion for controlling the irradiation portion, the control portion being configured to perform: a first control, which controls the irradiation portion such that a predetermined first laser light is irradiated onto the dicing tracks; and a second control, which controls the irradiation portion such that, after the first control, a predetermined second laser light is irradiated onto the dicing tracks, wherein the first laser light is laser light with processing energy that, within the irradiation range, removes a portion of the insulating film in the first region, leaving the remaining portion, and completely removes the metal structures in the second region, and removes a portion of the insulating film in the second region, leaving the remaining portion. The aforementioned second laser light is a laser light that completely removes the processing energy of the insulating film in the aforementioned first region and the aforementioned second region after being irradiated by the aforementioned first laser light within the irradiation range.

7. A laser processing apparatus, characterized by comprising: a support portion for supporting a wafer, the wafer containing a plurality of functional elements arranged adjacent to each other across dicing tracks, having: a first region on the surface of the dicing tracks formed by an insulating film, and a second region on the surface formed by an insulating film and metal structures on the insulating film; an irradiation portion for irradiating the dicing tracks with laser light; and a control portion for controlling the irradiation portion, the control portion being configured to perform: a first control, which controls the irradiation portion such that laser light is irradiated onto the dicing tracks, and the insulating films of the first region and the second region are formed in an uneven shape; and a second control, which controls the irradiation portion such that after the first control, laser light is irradiated onto the dicing tracks, and the insulating films of the first region and the second region are completely removed.

Images