JP2019176079A - Wafer processing method and wafer machining device - Google Patents

Abstract

To provide a wafer processing method and a wafer machining device which are arranged to be able to efficiently divide a wafer having a multilayer film including a metal film and formed in a substrate surface along division-scheduled lines into chips at low cost without needing labor and time.SOLUTION: A wafer processing method is arranged to apply a laser beam L to a wafer 10 having a multilayer film 16 including a metal film and formed in a surface of a silicon substrate 14 to divide the wafer 10 along division-scheduled lines into chips. The wafer processing method comprises: a modified-region formation step of applying a laser beam L to the silicon substrate 14 with a focus point P of the laser beam focused on the silicon substrate to form a modified region 20 in the silicon substrate 14 along each division-scheduled line; and a heat-processing step of applying the laser beam L to the multilayer film 16 with the focus point P focused thereon, thereby forming a heat-processing region 24 in the multilayer film 16 along each division-scheduled line.SELECTED DRAWING: Figure 9

Description

  The present invention relates to a technology for irradiating a wafer having a laminated film including a metal film on a surface of a substrate with a laser beam and dividing the wafer into chips along a predetermined division line.

  Conventionally, a modified region is formed inside the wafer along the planned dividing line by irradiating the inside of the wafer with a laser beam having a wavelength that is transmissive to a wafer such as a silicon wafer, and the like. In addition, there is known a method of dividing a wafer into chips along the planned division line by applying an external force along the planned division line whose strength has decreased due to the formation of the modified region (for example, patents). Reference 1).

  By the way, in a wafer in which a laminated film including a metal film such as a TEG (Test Element Group) is formed on the surface of a substrate such as a silicon substrate, the above-mentioned method cannot divide the metal film, so that the quality is good. There is a problem that it cannot be divided into chips.

  In order to solve the above problem, prior to forming the modified region inside the wafer, laser light having a wavelength that absorbs the laminated film formed on the surface of the wafer is irradiated along the planned division line. And the method of performing the ablation process which removes the laminated film on the division | segmentation planned line and forms a division | segmentation groove | channel is proposed (for example, refer patent document 2).

Japanese Patent No. 3408805 JP 2007-173475 A

  However, the conventional method (the method described in Patent Document 2) has a problem that the ablation process must be performed before the modified region is formed inside the wafer, resulting in poor productivity. Further, in order to perform the ablation process, a protective film such as a resin must be formed on the surface of the wafer, and after the ablation process is performed, the protective film needs to be removed. As described above, the conventional method has a problem in that it takes time and effort and increases the cost.

  The present invention has been made in view of the above circumstances, and does not require labor and time, and at low cost, a wafer in which a laminated film including a metal film is formed on the surface of a substrate is formed along a division schedule line. An object of the present invention is to provide a wafer processing method and a wafer processing apparatus that can be efficiently divided into chips.

  In order to achieve the above object, the following invention is provided.

  In the wafer processing method according to the first aspect of the present invention, the wafer processing is performed by irradiating the wafer having the laminated film including the metal film on the surface of the substrate with the laser beam, and dividing the wafer into chips along the division line. In this method, the laser beam and the wafer are relatively moved along the planned division line, and the substrate is aligned along the planned division line by irradiating the laser beam with the laser beam focused on the substrate. A modified region forming step for forming a modified region on the substrate and irradiating the laminated film with the laser beam while aligning the condensing point of the laser beam while relatively moving the laser beam and the wafer along the planned dividing line. And a thermal processing step of forming a thermal processing region in the laminated film along the scheduled division line.

  In the wafer processing method according to the second aspect of the present invention, in the first aspect, after the modified region forming step and the thermal processing step are performed, an external force is applied to the wafer to divide the wafer into chips along the planned division line. A dividing step is provided.

  In the wafer processing method according to the third aspect of the present invention, in the first aspect or the second aspect, the thermal processing step is performed using the same apparatus as the modified region forming step.

  In the wafer processing method according to the fourth aspect of the present invention, in any one of the first to third aspects, the thermal processing step is performed after the modified region forming step.

  In the wafer processing method according to the fifth aspect of the present invention, in any one of the first to third aspects, the thermal processing step is performed before the modified region forming step.

  In the wafer processing method according to the sixth aspect of the present invention, in any one of the first to third aspects, the thermal processing step is performed simultaneously with the modified region forming step.

  A wafer processing apparatus according to a seventh aspect of the present invention is a wafer processing apparatus that divides a wafer, on which a laminated film including a metal film is formed on the surface of a substrate, into chips along a predetermined division line, and emits laser light. A laser light irradiation device having a laser light source for performing the above operation, a condensing lens for condensing the laser light emitted from the laser light source, and a relative movement for relatively moving the wafer and the laser light irradiation device along the division line A mechanism, a distance adjustment mechanism that adjusts the distance between the wafer and the laser beam irradiation device, and a control unit that controls the distance adjustment mechanism. When the control unit forms a modified region on the substrate, In the first control for controlling the distance adjustment mechanism so that the laser beam condensing point is aligned with the substrate, and when the thermal processing region is formed in the laminated film, the laser beam condensing point is aligned with the laminated film. Distance adjustment Executing a second control for controlling the structure, the.

  According to the present invention, a wafer in which a laminated film including a metal film is formed on the surface of a substrate can be efficiently divided into chips along a planned division line at low cost without requiring labor and time. .

The flowchart which showed the flow of the wafer processing method which concerns on 1st Embodiment. Plan view showing an example of a wafer Partial sectional view of the wafer of FIG. Configuration diagram showing the outline of the laser processing equipment Block diagram showing the configuration of the control device in the laser processing apparatus The figure for demonstrating the modification area | region formation process in 1st Embodiment. The figure for demonstrating the modification area | region formation process in 1st Embodiment. The figure for demonstrating the modification area | region formation process in 1st Embodiment. The figure for demonstrating the heat processing process in 1st Embodiment. The figure for demonstrating the heat processing process in 1st Embodiment. The figure for demonstrating the division | segmentation process in 1st Embodiment. The figure for demonstrating the modification area | region formation process in 2nd Embodiment. The flowchart which showed the flow of the wafer processing method which concerns on 3rd Embodiment. The figure for demonstrating the heat processing process in 3rd Embodiment. The figure for demonstrating the modification area | region formation process in 3rd Embodiment. The flowchart which showed the flow of the wafer processing method which concerns on 4th Embodiment The figure for demonstrating the modification area | region formation and heat processing process in 4th Embodiment

  Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[First Embodiment]
First, a first embodiment of the present invention will be described.

  FIG. 1 is a flowchart showing a flow of a wafer processing method according to the first embodiment. As shown in FIG. 1, the wafer processing method according to the present embodiment includes a modified region forming step (step S10), a thermal processing step (step S12), and a dividing step (step S14).

<Wafer>
First, the wafer 10 to be processed in the present embodiment will be briefly described with reference to FIGS. FIG. 2 is a plan view showing an example of the wafer 10. FIG. 3 is a partial cross-sectional view of the wafer 10 of FIG.

  As shown in FIGS. 2 and 3, the wafer 10 is partitioned into a plurality of regions by division lines 12 arranged in a lattice pattern, and various devices constituting a semiconductor chip are formed in the partitioned regions. Yes. The wafer 10 includes a silicon substrate 14, and a laminated film 16 including a metal film is formed on the surface 10a side of the wafer 10 (that is, the surface of the silicon substrate 14). The laminated film 16 on the surface 10a side of the wafer 10 is provided with a plurality of metal films called TEGs (test element groups) for testing the function of the device partially on the division line 12. Yes. In addition, as a board | substrate which comprises the wafer 10, it is not limited to the silicon substrate 14, For example, a glass substrate, a piezoelectric ceramic substrate, etc. may be sufficient.

<Laser processing equipment>
In the present embodiment, the modified region forming step (step S10) and the thermal processing step (step S12) are performed using the laser processing apparatus 100 shown in FIG. The laser processing apparatus 100 is one of the components of the “wafer processing apparatus” of the present invention. Hereinafter, the configuration of the laser processing apparatus 100 will be described.

  FIG. 4 is a configuration diagram showing an outline of the laser processing apparatus 100. As shown in FIG. 4, the laser processing apparatus 100 mainly includes a stage 110 that moves the wafer 10, a laser processing head 120 that performs laser processing on the wafer 10, and a control device 150 that controls each part of the laser processing apparatus 100. It is configured.

  The stage 110 sucks and holds the wafer 10. The stage 110 includes a stage moving mechanism (not shown), and is configured to be movable in the XYZθ directions by the stage moving mechanism. As a stage moving mechanism, it can be comprised by various mechanisms, such as a ball screw drive and a linear motor mechanism, for example. The stage 110 is an example of the “relative movement mechanism” and the “distance adjustment mechanism” in the present invention.

  In the example shown in FIG. 4, the three directions XYZ are orthogonal to each other, among which the X direction and the Y direction are horizontal directions, and the Z direction is a vertical direction. Further, the θ direction is a rotation direction with a vertical axis (Z axis) as a rotation axis.

  The laser processing head 120 is disposed at a position facing the stage 110. The laser processing head 120 irradiates the wafer 10 with processing laser light L while moving relative to the stage 110 that holds the wafer 10 by suction. The laser processing head 120 is an example of the “laser light irradiation device” in the present invention.

  The laser processing head 120 mainly includes a laser light source 122, a spatial light modulator 128, a condenser lens 138, and the like.

  The laser light source 122 outputs a processing laser beam L irradiated to the wafer 10 under the control of the control device 150. The laser light L irradiated in the modified region forming step and the thermal processing step is set to a wavelength that is transmissive to the silicon substrate 14 constituting the wafer 10. As the wavelength of the laser light L, a wavelength of 1000 nm to 1300 nm, preferably 1050 nm to 1200 nm, more preferably 1100 nm to 1150 nm is used. In the present embodiment, as an example, laser light L having the same wavelength (for example, 1135 nm) is irradiated in the modified region forming step and the thermal processing step.

  The spatial light modulator 128 is of a phase modulation type, and receives the laser light L output from the laser light source 122 and modulates the phase of the laser light L in each of a plurality of pixels arranged two-dimensionally. A pattern (modulation pattern) is presented, and the phase-modulated laser beam L is output.

  As the spatial light modulator 128, for example, a reflective liquid crystal (LCOS) spatial light modulator (SLM) is used. The operation of the spatial light modulator 128 and the hologram pattern presented by the spatial light modulator 128 are controlled by the control device 150. Since the specific configuration of the spatial light modulator 128 and the hologram pattern presented by the spatial light modulator 128 are already known, detailed description thereof will be omitted here.

  The condensing lens 138 is an objective lens (infrared objective lens) that condenses the laser light L inside the wafer 10. The numerical aperture (NA) of the condenser lens 138 is, for example, 0.65.

  In addition to the above configuration, the laser processing head includes a beam expander 124, a λ / 2 wavelength plate 126, a reduction optical system 136, and the like.

  The beam expander 124 expands the laser light L output from the laser light source 122 to an appropriate beam diameter for the spatial light modulator 128. The λ / 2 wavelength plate 126 adjusts the polarization plane of incidence of laser light on the spatial light modulator 128. The reduction optical system 136 is an afocal optical system (bilateral telecentric optical system) including a first lens 136 a and a second lens 136 b, and reduces the laser light L modulated by the spatial light modulator 128 to a condenser lens 138. Project.

  Although not shown, the laser processing head includes an alignment optical system for performing alignment with the wafer 10, and an auto for maintaining a constant distance (working distance) between the wafer 10 and the condenser lens 138. A focus unit and the like are provided.

  The control device 150 is realized by a general-purpose computer such as a personal computer or a microcomputer.

  The control device 150 includes a central processing unit (CPU), a read only memory (ROM), a random access memory (RAM), an input / output interface, and the like. In the control device 150, various programs such as a control program stored in the ROM are expanded in the RAM, and the programs expanded in the RAM are executed by the CPU, so that each unit in the control device 150 shown in FIG. Functions are realized, and various arithmetic processes and control processes are executed via the input / output interface.

  FIG. 5 is a block diagram showing the configuration of the control device 150. As shown in FIG. 5, the control device 150 functions as a main control unit 152, a stage control unit 154, a laser control unit 156, and a spatial light modulator control unit 158.

  The main control unit 152 comprehensively controls each unit constituting the control device 150, that is, the stage control unit 154, the laser control unit 156, and the spatial light modulator control unit 158.

  The stage control unit 154 outputs a control signal for controlling the movement (including rotation) of the stage 110 to the stage 110. The stage control unit 154 is one of the components of the “control unit” of the present invention along with the main control unit 152.

  The laser control unit 156 controls the emission of the laser light L, and outputs a control signal for controlling the wavelength, pulse width, intensity, emission timing, repetition frequency, and the like of the laser light L to the laser light source 122.

  The spatial light modulator control unit 158 outputs a control signal for controlling the operation of the spatial light modulator 128 to the spatial light modulator 128. That is, the spatial light modulator control unit 158 performs control for presenting a predetermined hologram pattern to the spatial light modulator 128. The hologram pattern to be presented to the spatial light modulator 128 is derived in advance based on the formation position of the modified region, the wavelength of the laser light L to be irradiated, the refractive index of the condenser lens 138 and the wafer 10, and the like. It is stored in 150 memory units (not shown).

  In addition to this, the laser processing apparatus 100 includes a wafer transfer means, an operation plate, a television monitor, an indicator lamp, and the like (not shown).

  On the operation plate, switches and a display device for operating operations of each unit of the laser processing apparatus 100 are attached. The television monitor displays a wafer image captured by an imaging device (CCD camera or the like) (not shown), or displays program contents, various messages, and the like. The indicator lamp displays an operation status such as processing end or emergency stop during the processing of the laser processing apparatus 100.

<Modified region forming process>
Next, the modified region forming step (step S10) shown in FIG. 1 will be described.

  6 to 8 are views for explaining the modified region forming step in the first embodiment, and are partial cross-sectional views of the wafer 10. 6 and 7 are cross-sectional views in a direction orthogonal to the direction along the planned division line 12 of the wafer 10. FIG. 8 is a cross-sectional view in the direction along the division line 12 of the wafer 10 (corresponding to a cross-sectional view in a direction perpendicular to the paper surface of FIGS. 6 and 7).

  As shown in FIG. 1, when the wafer processing method of the present embodiment is started, a modified region forming step (step S10) is first performed. This modified region forming step is performed using the laser processing apparatus 100 shown in FIG. Hereinafter, the modified region forming step will be described in detail.

  First, the wafer 10 is placed on the stage 110 of the laser processing apparatus 100 with the back surface 10b of the wafer 10 (that is, the back surface of the silicon substrate 14) facing upward. Subsequently, the wafer 10 is aligned using an alignment optical system (not shown).

  Next, as shown in FIG. 6, the stage 110 is moved under the control of the stage control unit 154 (corresponding to “first control” of the present invention), and the laser beam L is collected inside the silicon substrate 14 of the wafer 10. Match the light spot P. The initial position of the stage 110 is determined based on the thickness and refractive index of the wafer 10, the numerical aperture of the condenser lens 138, and the like.

  Next, under the control of the laser control unit 156 and the stage control unit 154, the laser light L is emitted from the laser light source 122 of the laser processing head 120, and the laser light L condensed by the condenser lens 138 is scheduled to be divided into the wafer 10. The stage 110 is moved so as to scan on the line 12. That is, the laser beam L is irradiated inside the silicon substrate 14 with the back surface 10b of the wafer 10 as the laser beam incident surface, and the laser beam L is irradiated. The condensing point P is relatively moved along.

  At this time, the laser light L output from the laser light source 122 is expanded in beam diameter by the beam expander 124, reflected by the first mirror 130, and the polarization direction is changed by the λ / 2 wavelength plate 126 so that spatial light modulation is performed. Is incident on the device 128.

  The laser light L incident on the spatial light modulator 128 is modulated according to a predetermined hologram pattern presented on the spatial light modulator 128. At that time, the spatial light modulator control unit 158 spatially generates a hologram pattern for modulating the laser light L so that aberration correction is performed at the position where the condensing point P of the laser light L is aligned inside the silicon substrate 14. Control to be presented to the optical modulator 128 is performed.

  The laser light L emitted from the spatial light modulator 128 is sequentially reflected by the second mirror 131 and the third mirror 132, passes through the first lens 136 a, and further reflected by the fourth mirror 133 and the fifth mirror 134. Then, the light passes through the second lens 136 b and enters the condenser lens 138. Thus, the laser light L emitted from the spatial light modulator 128 is reduced and projected onto the condenser lens 138 by the reduction optical system 136 including the first lens 136a and the second lens 136b. The laser light L incident on the condenser lens 138 is condensed inside the silicon substrate 14 by the condenser lens 138.

  Since the condensing point P of the laser beam L incident from the back surface 10b of the wafer 10 is set inside the silicon substrate 14, the laser beam L transmitted through the back surface 10b of the wafer 10, as shown in FIG. Energy concentrates at the condensing point P inside the substrate 14, and the modified region 20 is formed in the vicinity of the condensing point P inside the silicon substrate 14. When the modified region 20 is formed, a crack 22 is generated in the thickness direction of the wafer 10 starting from the modified region 20.

  Such relative movement of the condensing point P of the laser beam L along each division line 12 is performed a plurality of times with respect to one division line 12. At this time, by changing the position where the condensing point P is matched with the distance from the back surface 10b each time, as shown in FIG. 7, a plurality of modified regions 20 are formed in the thickness direction of the wafer 10 in order from the front surface 10a side. It is formed inside the silicon substrate 14. Thus, as shown in FIG. 8, two layers of the modified region 20 are formed in the silicon substrate 14 along the direction of the division line 12.

  In the present embodiment, as an example, the case where two layers of the modified region 20 are formed inside the silicon substrate 14 is shown, but the present invention is not limited to this, and one layer or three or more layers are formed inside the silicon substrate 14. The modified region 20 may be formed.

<Thermal processing process>
Next, the thermal processing step (step S12) shown in FIG. 1 will be described.

  9 and 10 are diagrams for explaining the thermal processing step in the first embodiment, and are partial cross-sectional views of the wafer 10. FIG. 9 is a cross-sectional view in a direction orthogonal to the direction along the planned division line 12 of the wafer 10. FIG. 10 is a cross-sectional view in the direction along the division line 12 of the wafer 10 (corresponding to a cross-sectional view in a direction perpendicular to the paper surface of FIG. 9).

  As shown in FIG. 1, in the wafer processing method of this embodiment, after the modified region forming step is performed, the thermal processing step (step S12) is performed. This thermal processing step is performed using a laser processing apparatus 100 shown in FIG. Hereinafter, the thermal processing step will be described in detail.

  The thermal processing step is performed with the wafer 10 being placed on the stage 110 of the laser processing apparatus 100. That is, since the modified region process and the thermal processing step are performed using the same apparatus (laser processing apparatus 100), after the wafer 10 is aligned in the modified region forming process, the alignment of the wafer 10 is performed. It is not necessary to perform again.

  In the thermal processing step, as shown in FIG. 9, the stage 110 is moved under the control of the stage controller 154 (corresponding to “second control” of the present invention), and the laser beam L enters the laminated film 16 of the wafer 10. The condensing point P is adjusted.

  Next, under the control of the laser control unit 156 and the stage control unit 154, the laser light L is emitted from the laser light source 122 of the laser processing head 120, and the laser light L condensed by the condenser lens 138 is scheduled to be divided into the wafer 10. The stage 110 is moved so as to scan on the line 12. That is, the back surface 10b of the wafer 10 is used as a laser light incident surface, the laser beam L is irradiated with the condensing point P inside the laminated film 16, and the division planned lines 12 formed in a lattice shape by moving the stage 110 are used. The condensing point P is relatively moved along.

  Since the condensing point P of the laser beam L incident from the back surface 10b of the wafer 10 is set in the laminated film 16, the laser beam L irradiated from the back surface 10b of the wafer 10 is as shown in FIG. Through the silicon substrate 14, energy is concentrated at the condensing point P inside the laminated film 16, absorbed by the laminated film 16 including a metal film such as TEG and converted into heat, and the laminated film 16 is converted into heat. Thermal processing is performed to melt the material. That is, by irradiating the laser beam L with the condensing point P of the laser beam L aligned with the inside of the laminated film 16, the laminated film 16 including the metal film can be effectively affected by heat, and the laminated film 16 is laminated. A thermal processing region (melting region) 24 in which the material of the laminated film 16 is thermally deformed is formed in the vicinity of the condensing point P inside the film 16. As a result, as shown in FIG. 10, one layer of the thermal processing region 24 is formed in the laminated film 16 along the direction of the division line 12.

  In the thermal processing step as well, the spatial light modulator control unit 158 performs aberration correction at the position where the condensing point P of the laser light L is aligned in the laminated film 16, as in the modified region forming step described above. As shown in the figure, the spatial light modulator 128 is controlled to present a hologram pattern for modulating the laser light L.

  In the present embodiment, the wavelength of the laser beam L applied to the wafer 10 in the thermal processing step is the same as the wavelength of the laser beam L applied to the wafer 10 when the modified region forming step is performed. Note that the wavelength of the laser beam L applied to the wafer 10 in the thermal processing step may be any wavelength as long as it has transparency to the silicon substrate 14, and is applied to the wafer 10 when the modified region forming step is performed. The wavelength of the laser beam L may be different.

  Further, the intensity of the laser beam L irradiated on the wafer 10 in the thermal processing step may be the same as or different from the intensity of the laser beam L irradiated on the wafer 10 when the modified region forming step is performed. . For example, according to the material and thickness of the laminated film 16, the intensity of the laser beam L irradiated to the wafer 10 in the thermal processing step is set to the laser beam L irradiated to the wafer 10 when the modified region forming step is performed. It may be larger or smaller than the strength.

<Division process>
Next, the dividing step (step S14) shown in FIG. 1 will be described.

  FIG. 11 is a diagram for explaining the dividing step in the first embodiment, and is a partial cross-sectional view of the wafer 10. 11 is a cross-sectional view (corresponding to the cross-sectional view of FIG. 9) in a direction orthogonal to the direction along the planned division line 12 of the wafer 10.

  As shown in FIG. 1, in the wafer processing method of the present embodiment, after the thermal processing step is performed, the dividing step (step S14) is performed. The dividing step is performed using a dividing device (not shown). Since a known device can be used as the dividing device, detailed description thereof is omitted here (see, for example, JP 2012-186446 A). The dividing apparatus is one of the components of the “wafer processing apparatus” of the present invention, together with the laser processing apparatus 100 described above.

  In the division step, an external force is applied to the wafer 10 to divide the wafer 10 into chips along the division line 12.

  Specifically, as shown by reference numeral XIA in FIG. 11, an expanded tape 26 having an adhesive on one side is attached to the back surface 10b of the wafer 10 and mounted on a frame (not shown) via the expanded tape 26. The wafer 10 is placed on the table of the dividing apparatus. Then, in a state where the frame is fixed by a frame fixing mechanism (not shown), the expand tape (push-up ring) is lifted to push up the expand tape 26 from below, and the expand tape 26 to which the wafer 10 is attached is radially expanded. Thus, a radial tensile force F along the plane direction of the wafer 10 is applied to the wafer 10 as indicated by reference numeral XIB in FIG. Thereby, the crack 22 extended from the modified region 20 inside the silicon substrate 14 becomes a division starting point, and the wafer 10 can be divided into chips along the division planned line.

  Here, in the present embodiment, since the thermal processing region 24 is formed inside the multilayer film 16 in the thermal processing step, when the tensile force F is applied to the wafer 10, the multilayer film starts from the thermal processing region 24. The metal film included in 16 can be easily divided, which can help to divide the wafer 10 into chips.

  In addition, as an aspect which applies external force to the wafer 10 in a division | segmentation process, you may make it apply external force with respect to the wafer 10 with members, such as a squeegee and a roller, for example, without using an expand ring.

<Effect>
Next, the effect of this embodiment will be described.

  According to the present embodiment, the modified region forming step of irradiating the laser beam L with the laser beam L being focused on the silicon substrate 14 and the laser beam with the laser beam L being focused on the laminated film 16 are performed. And a thermal processing step of irradiating L. Therefore, the ablation process performed by the conventional method is not required, and the protective film formation / removal process performed before and after that is not required, thereby simplifying the process and reducing the cost.

  Further, according to the present embodiment, the laser light L having a wavelength that is transmissive to the silicon substrate 14 is used in both the modified region forming step and the thermal processing step. Therefore, in the thermal processing step, even if the laser beam L is irradiated from the back surface 10b side of the wafer 10 with the condensing point of the laser beam L set in the laminated film 16, the silicon substrate 14 is affected by heat (thermal damage). ), The bending strength of the chip can be increased, the thermal effect can be effectively exerted on the laminated film 16, and the thermal processing region 24 is formed inside the laminated film 16. Can do. Thereby, the metal film contained in the laminated film 16 can be easily divided from the thermal processing region 24 as a starting point, and the wafer 10 can be helped to be divided into chips.

  Therefore, according to the present embodiment, the wafer 10 having the laminated film 16 including the metal film formed on the surface of the silicon substrate 14 can be efficiently formed on the chip along the division line without cost and time. Can be divided.

  Moreover, in this embodiment, since the kerf width (cutting width) can be narrowed compared with the case where an ablation process is performed, the yield of chips can be improved.

  In the present embodiment, as a preferable mode, the modified region forming step and the thermal processing step are performed using the same apparatus (laser processing apparatus 100). However, the present invention is not necessarily in this mode. Not limited to this, the modified region forming step and the thermal processing step may be performed using different apparatuses.

  In the present embodiment, the stage 110 is configured to be movable in the XYZθ direction. However, any other configuration can be used as long as the laser processing head 120 and the stage 110 can be moved relative to each other in the XYZθ direction. There may be. For example, the stage 110 may be configured to be movable in the XZθ direction, and the laser processing head 120 may be configured to be movable in the Y direction.

  Although the first embodiment has been described above, the embodiment of the present invention is not limited to this. Therefore, other embodiments for carrying out the present invention will be described below. Each of the following embodiments is basically the same as the first embodiment. Therefore, in the following, each embodiment will be described with a focus on differences from the first embodiment, and description of the contents overlapping with those of the first embodiment will be omitted.

[Second Embodiment]
The second embodiment is different from the first embodiment in that, in the modified region forming step, the laser light L condensed by the condenser lens 138 is branched and simultaneously condensed at a plurality of different positions. It is in the point.

  FIG. 12 is a view for explaining the modified region forming step in the second embodiment, and is a cross-sectional view in the direction along the division line 12 of the wafer 10.

  In the present embodiment, in the modified region forming step, the spatial light modulator control unit 158 controls the hologram pattern to be presented to the spatial light modulator 128, thereby condensing light by the condenser lens 138 as shown in FIG. The laser beam L to be split is split and simultaneously focused at two different positions (focusing points P1 and P2). At this time, the two light condensing points P1 and P2 are different from each other in the thickness direction of the wafer 10 and are in a positional relationship in which they are separated from each other in the direction along the planned dividing line 12 (scan direction). Then, the laser beam L is scanned along the planned division line 12 in a state where the two condensing points P1 and P2 are aligned inside the silicon substrate 14, so that the planned division line 12 is formed inside the silicon substrate 14. Two layers of the modified region 20 are formed along the direction.

  According to this embodiment, since a plurality of modified layers can be formed by one scan in the modified region forming step, it is possible to further improve productivity.

  In the present embodiment, the laser light L condensed by the condenser lens 138 is condensed at two different positions. However, the present invention is not limited to this, and may be condensed at three or more different positions. Good.

[Third Embodiment]
The third embodiment is different from the first embodiment in that the order of the modified region forming step and the thermal processing step is reversed. Note that, in the modified region forming step in the third embodiment, the laser light L condensed by the condenser lens 138 is branched and simultaneously condensed at a plurality of different positions, as in the second embodiment. It is a thing.

  FIG. 13 is a flowchart showing the flow of the wafer processing method according to the third embodiment. FIG. 14 is a view for explaining the thermal processing step in the third embodiment, and is a cross-sectional view in the direction along the division planned line 12 of the wafer 10. FIG. 15 is a view for explaining the modified region forming step in the third embodiment, and is a cross-sectional view in the direction along the division line 12 of the wafer 10.

  As shown in FIG. 13, in the present embodiment, first, a thermal processing step (step S20) is performed. In this thermal processing step, the first implementation is performed except that the laser beam L is scanned along the planned dividing line 12 in a state where the condensing point P of the laser beam L is aligned with the inside of the laminated film 16 of the wafer 10. This is basically the same as the modified region forming step (step S10). By performing the thermal processing step, as shown in FIG. 14, one layer of the thermal processing region 24 is formed in the laminated film 16 along the direction of the division line 12.

  Next, a modified region forming step (step S22) is performed. In this modified region forming step, as shown in FIG. 15, the spatial light modulator controller 158 controls the hologram pattern to be presented to the spatial light modulator 128 in the same manner as in the second embodiment. The laser light L condensed by the optical lens 138 is branched and simultaneously condensed at two different positions (condensing points P1 and P2). Then, the laser beam L is scanned along the planned division line 12 in a state where the two condensing points P1 and P2 are aligned inside the silicon substrate 14, so that the planned division line 12 is formed inside the silicon substrate 14. Two layers of the modified region 20 are formed along the direction.

  Thereafter, a dividing step (step S24) is performed. Since the dividing step is the same as the dividing step (step S14) of the first embodiment, description thereof is omitted here.

  According to the present embodiment, since the thermal processing step is performed before the modified region forming step, in the thermal processing step, the influence of the modified region 20 formed inside the silicon substrate 14 in the modified region forming step is affected. Without receiving, the energy of the laser beam L can be concentrated only in the vicinity (the part to be processed) of the condensing point P inside the laminated film 16. As a result, the thermal processing region 24 can be accurately formed in the laminated film 16, and the quality of the chip can be improved.

[Fourth Embodiment]
The fourth embodiment is different from the first embodiment in that the modified region forming step and the thermal processing step are performed simultaneously.

  FIG. 16 is a flowchart showing a flow of a wafer processing method according to the fourth embodiment. FIG. 17 is a view for explaining the modified region formation / thermal processing step in the fourth embodiment, and is a cross-sectional view of the wafer 10 in the direction along the division line 12.

  As shown in FIG. 16, in this embodiment, a modified region formation / thermal processing step (step S30) is performed. In this modified region formation / thermal processing step, the spatial light modulator control unit 158 controls the hologram pattern to be presented to the spatial light modulator 128, thereby branching the laser light L condensed by the condenser lens 138. Light is condensed simultaneously at three different positions (light condensing points P1, P2, and P3). At this time, the three condensing points P1, P2, and P3 are different from each other in the thickness direction of the wafer 10 and are in a positional relationship that is separated from each other in the direction along the division planned line 12 (scan direction). . Then, as shown in FIG. 17, among the three condensing points P 1, P 2, P 3, the first condensing point P 1 and the second condensing point P 2 are aligned with the inside of the silicon substrate 14, and the inside of the laminated film 16. The laser beam L is scanned along the planned division line 12 in a state where the third condensing point P3 is aligned, so that the modified region 20 is formed along the direction of the planned division line 12 inside the silicon substrate 14. 2 layers are formed, and one layer of the thermal processing region 24 is formed in the laminated film 16 along the direction of the division line 12.

  Since the dividing step (step S32) is the same as the dividing step (step S14) of the first embodiment, the description thereof is omitted here.

  According to the present embodiment, since the modified region process and the thermal processing process are performed simultaneously, it becomes possible to further improve productivity.

  In the present embodiment, the laser light L condensed by the condenser lens 138 is condensed at three different positions. However, the present invention is not limited to this, for example, the thickness of the silicon substrate 14 constituting the wafer 10. Is thin, the laser beam L is condensed at two different positions so that one of the condensing points is aligned with the inside of the silicon substrate 14 and the other condensing point is aligned with the inside of the laminated film 16. In this state, the laser beam L may be scanned along the scheduled division line 12.

  The embodiments of the present invention have been described above. However, the present invention is not limited to the above examples, and various improvements and modifications may be made without departing from the scope of the present invention. .

  DESCRIPTION OF SYMBOLS 10 ... Wafer, 12 ... Divided line, 14 ... Silicon substrate, 16 ... Laminated film, 20 ... Modification area | region, 22 ... Crack, 24 ... Thermal processing area | region, 26 ... Expanding tape, 100 ... Laser processing apparatus, 110 ... Stage , 120 ... laser processing head, 122 ... laser light source, 124 ... beam expander, 126 ... λ / 2 wavelength plate, 128 ... spatial light modulator, 136 ... reduction optical system, 138 ... condensing lens, 150 ... control device, 152 ... main control unit, 154 ... stage control unit, 156 ... laser control unit, 158 ... spatial light modulator control unit, P ... condensing point, P1, P2, P3 ... condensing point

Claims (7)

A wafer processing method of irradiating a wafer on which a laminated film including a metal film is formed on a surface of a substrate with a laser beam, and dividing the wafer into chips along a predetermined division line,
By irradiating the laser beam with the laser beam being focused on the substrate while moving the laser beam and the wafer relatively along the planned dividing line, the laser beam is irradiated along the planned dividing line. A modified region forming step of forming a modified region on the substrate;
By irradiating the laser beam with the laser beam and the focusing point of the laser light while moving the laser beam and the wafer relatively along the planned dividing line, Along the thermal processing step of forming a thermal processing region in the laminated film,
A wafer processing method comprising: After the modified region forming step and the thermal processing step are performed, the method includes a dividing step of applying an external force to the wafer to divide the wafer into chips along the planned dividing line.
The wafer processing method according to claim 1. The thermal processing step is performed using the same apparatus as the modified region forming step.
The wafer processing method according to claim 1 or 2. The thermal processing step is performed after the modified region forming step.
The wafer processing method according to any one of claims 1 to 3. The thermal processing step is performed before the modified region forming step.
The wafer processing method according to any one of claims 1 to 3. The thermal processing step is performed simultaneously with the modified region forming step.
The wafer processing method according to any one of claims 1 to 3. A wafer processing apparatus for dividing a wafer in which a laminated film including a metal film is formed on a surface of a substrate into chips along a predetermined division line,
A laser light irradiation apparatus comprising: a laser light source that emits laser light; and a condenser lens that condenses the laser light emitted from the laser light source;
A relative movement mechanism for relatively moving the wafer and the laser beam irradiation device along the scheduled division line;
A distance adjusting mechanism for adjusting a distance between the wafer and the laser beam irradiation device;
A control unit for controlling the distance adjustment mechanism;
With
The controller is
When forming a modified region on the substrate, a first control for controlling the distance adjustment mechanism so as to align the condensing point of the laser beam on the substrate;
When forming a thermal processing region in the laminated film, a second control for controlling the distance adjusting mechanism so as to align the condensing point of the laser beam with the laminated film is executed.
Wafer processing equipment.

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