TWI550703B - A method of processing a substrate having a pattern - Google Patents

Description

Method for processing patterned substrate

The present invention relates to a method of dividing a substrate having a pattern by repeatedly arranging a plurality of unit patterns two-dimensionally on a substrate.

The LED element is manufactured by, for example, a substrate having a pattern in which a unit pattern of an LED element is two-dimensionally overlaid on a substrate (wafer, mother substrate) such as sapphire single crystal (a substrate having an LED pattern). It is divided and diced (wafered) by a predetermined segmentation region called a scribe line which is formed in a lattice shape. Here, the scribe line is a narrow-width region which is a gap portion of the two portions of the LED element by division.

As a method for such division, there is a known method of arranging the irradiated light of the ultrashort pulse light having a pulse width of psec level at a discrete position along the planned line by the irradiated area of each unit pulsed light. Irradiation is performed to form a starting point for division along a line to be formed (usually a center position of the cutting path) (see, for example, Patent Document 1). In the method disclosed in Patent Document 1, a crack extension (crack extension) formed by splitting or splitting between the processing marks formed in the irradiated region of each unit pulsed light is performed, and the substrate is divided along the crack. To achieve singulation.

[Previous Technical Literature]

[Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open Publication No. 2001-131256

In the substrate having the pattern as described above, the unit pattern is usually arranged in a direction parallel to the orientation flat provided on the sapphire single crystal substrate and in a direction orthogonal to the direction. Therefore, in such a patterned substrate, the scribe line extends in a direction parallel to the orientation flat and a direction perpendicular to the direction.

In the case of dividing such a patterned substrate by the method disclosed in Patent Document 1, it is of course possible to illuminate the laser light along a scribe line parallel to the orientation plane and a scribe line perpendicular to the orientation plane. In this case, the extension of the crack of the self-processing mark accompanying the irradiation of the laser light is generated not only in the irradiation direction (scanning direction) of the laser light in the extending direction of the planned line but also in the thickness direction of the substrate.

However, the crack extension in the thickness direction of the substrate is generated from the processing mark in the vertical direction as compared with the irradiation of the laser light along the dicing plane parallel to the orientation plane, and the ray is irradiated along the scribe line perpendicular to the orientation plane under the same irradiation conditions. When the light is emitted, the crack does not extend in the vertical direction but in the direction inclined from the vertical direction. This difference has been known from past experience.

Further, as a sapphire single crystal substrate for a patterned substrate, the surface orientation of the crystal face such as the c-plane or the a-plane may be used to be perpendicular to the orientation plane in the main surface, in addition to the plane orientation of the principal surface of the c-plane or the a-plane. The direction in which the plane orientation of the crystal faces is inclined with respect to the normal direction of the main surface as the tilt axis, so-called an off-angle substrate (also referred to as an off substrate), but the above-described cutting perpendicular to the orientation plane The inclination of the crack when the laser is irradiated with the laser light is generated regardless of whether or not the substrate is off, which has been confirmed by the inventors of the present invention.

On the other hand, in view of the miniaturization of the LED elements or the increase in the number of extractions per substrate area, it is preferable that the width of the dicing streets is narrow. However, when the method disclosed in Patent Document 1 is applied to a substrate having a pattern having a narrow width of such a scribe line, a scribe line perpendicular to the orientation plane may be inclined and the crack is not formed in the cut. A problem in the width of the scribe line that reaches the region adjacent to the LED element. Such a problem arises because it is a factor that lowers the yield of the LED element, which is not preferable.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a dividing method capable of dividing a substrate having a pattern well.

In order to solve the above problems, the invention of claim 1 is a method for processing a patterned substrate, wherein the patterned substrate is formed by repeatedly arranging a plurality of unit patterns two-dimensionally on a single crystal substrate, and the method includes: a dividing start point forming step of setting a first predetermined line to be extended in a first direction along the orientation plane in the substrate having the pattern and a second direction extending in a direction orthogonal to the first direction The two-divided predetermined line illuminates the laser light, whereby the substrate having the pattern forms a division starting point in a lattice shape, and the cracking step singulates the substrate having the pattern along the dividing starting point to singulate the substrate; The dividing start point forming step includes a crack stretching processing step of irradiating the laser light while scanning along the first and second divided planned lines to cause each unit of the laser light to be irradiated The processing marks formed on the workpiece by the pulsed light are located at discrete points along the first and second dividing lines, and the cracks are added from the respective processing marks. In the step of expanding the cracking process, when the dividing starting point is formed along the first dividing line, the crack reaches the opposite side of the main surface on which the processing mark side is formed on the patterned substrate. The first processing condition of the main surface irradiates the laser beam, and when the dividing start point is formed along the second dividing line, the laser beam is irradiated with the second processing condition in which the crack stops inside the patterned substrate.

The invention of claim 2, wherein the method of processing a substrate having a pattern according to claim 1, wherein the peak power of the laser light at the start of the division along the second predetermined line is set 50% or more and 70% or less of the peak power at the time of forming the division starting point along the first division planned line.

The invention of claim 3, wherein the method of processing a substrate having a pattern according to claim 1 or 2, wherein, in the step of forming the division starting point, the unit pattern is not formed in the substrate having the pattern The main surface on the side is set as the irradiated surface of the aforementioned laser light.

The method of processing a patterned substrate according to any one of claims 1 to 3, wherein the single crystal substrate is in a main surface of the patterned substrate The direction perpendicular to the orientation plane serves as an axis, and the surface orientation of the predetermined crystal plane is inclined by about several degrees with respect to the normal direction of the main surface.

According to the invention of claims 1 to 4, when the substrate having the pattern is diced by the crack stretching process, the crack may be inclined in the process orthogonal to the orientation plane, After the optical axis of the laser light is shifted from the vertical direction, the crack stretching process is performed to suppress the inclination of the crack. Thereby, it is possible to very satisfactorily suppress the occurrence of damage when the unit pattern of the respective element wafers provided on the patterned substrate is singulated. As a result, the yield of the element wafer obtained by singulating the patterned substrate is improved.

1‧‧‧ controller

4‧‧‧ stage

4m‧‧‧Mobile agencies

5‧‧‧Optical Optics

6‧‧‧Upper viewing optics

6a, 16a‧‧‧ camera

6b, 16b‧‧‧ monitor

7‧‧‧Upper lighting system

8‧‧‧Lower lighting system

10‧‧‧Processed objects

10a‧‧‧ Keeping the film

11‧‧‧Attraction means

100‧‧‧ Laser processing equipment

16‧‧‧ Lower Observation Optics

51, 71, 81‧‧‧ half mirror

52, 82‧‧‧ concentrating lens

CP‧‧‧ component chip

CR0~CR3‧‧‧ crack

L1‧‧‧Upper illumination

L2‧‧‧Lower illumination

LB‧‧‧Laser light

M‧‧‧ machining marks

OF‧‧‧ Orientation plane

PL, PL1, PL2‧‧‧ processing line

S1‧‧‧Upper illumination source

S2‧‧‧lower illumination source

SL‧‧‧Laser light source

ST‧‧‧ cutting road

Terminal position of T1, T2, T3‧‧ (crack)

UP‧‧‧ unit pattern

W‧‧‧patterned substrate

W1‧‧‧Single crystal substrate

Main surface of Wa, Wb‧‧‧ (with patterned substrate)

Fig. 1 is a schematic view showing the configuration of a laser processing apparatus 100 for dividing a workpiece.

Fig. 2 is a view for explaining an irradiation state of the laser light LB in the crack stretching process.

3 is a schematic plan view and a partial enlarged view of a substrate W having a pattern.

Fig. 4 is a view showing a state in which the substrate W having the pattern is stretched by the crack CR0 of the cross section perpendicular to the X direction.

5(a) and 5(b) are views showing how the crack of the patterned substrate W in the cross section perpendicular to the Y direction is CR1 or CR2.

6(a) and 6(b) are schematic plan views of the element wafer.

Figure 7 is an optical microscope image of a cross section perpendicular to the Y direction of the sample of Example 1.

Fig. 8 is an optical microscope image of a cross section perpendicular to the Y direction of the sample of Comparative Example 1.

Figure 9 is an optical microscope image of a cross section perpendicular to the Y direction of the sample of Example 2.

Fig. 10 is an optical microscope image of a cross section perpendicular to the Y direction of the sample of Comparative Example 1.

<Laser processing device>

Fig. 1 is a schematic view showing the configuration of a laser processing apparatus 100 which can be applied to the division of a workpiece according to an embodiment of the present invention. The laser processing apparatus 100 mainly includes a controller that controls various operations (observation operation, alignment operation, machining operation, and the like) in the device, a stage 4 on which the workpiece 10 is placed, and The laser beam LB emitted from the laser light source SL is irradiated onto the illumination optical system 5 of the workpiece 10.

The stage 4 is mainly composed of an optically transparent member such as quartz. The stage 4 can be suction-fixed by the suction means 11 such as a suction pump to load the workpiece 10 placed thereon. Further, the stage 4 can be moved in the horizontal direction by the moving mechanism 4m. In addition, in the case of the workpiece 10, the adhesive sheet 10a is attached to the workpiece 10, and the workpiece 10 is placed on the stage 4 with the side of the holding sheet 10a as the placement surface. It is not necessary to use the aspect of the holding piece 10a.

The moving mechanism 4m moves the stage 4 in the horizontal direction of the predetermined XY in the horizontal plane by the action of a driving means (not shown). Thereby, the movement of the observation position or the movement of the laser light irradiation position is achieved. Further, the movement mechanism 4m is preferably driven in a horizontal direction by a rotation (θ rotation) operation in a horizontal plane centering on a predetermined rotation axis.

The illuminating optical system 5 includes a laser light source SL, a half mirror 51 provided in a lens barrel (not shown), and a condensing lens 52.

The laser processing apparatus 100 roughly reflects the laser light LB emitted from the laser light source SL on the half mirror 51, and causes the laser beam LB to focus on the workpiece placed on the stage 4 by the collecting lens 52. The portion to be processed of 10 is condensed and irradiated onto the workpiece 10. Then, in this aspect, the workpiece 4 is moved while the laser light LB is irradiated, and the workpiece 10 can be processed along a predetermined planned line. That is, the laser processing apparatus 100 is a device that performs processing by relatively scanning the laser beam LB with respect to the workpiece 10.

As the laser light LB, the Nd:YAG laser is very suitably used. As the laser light source SL, a wavelength of 500 nm to 1600 nm is used. Further, in order to realize the processing of the above-described processing pattern, the pulse width of the laser light LB must be about 1 psec to 50 psec. Further, the repetition frequency R is about 10 kHz to 200 kHz, and the irradiation energy (pulse energy) of the laser light is about 0.1 μJ to 50 μJ, which is very suitable.

Further, in the laser processing apparatus 100, it is also possible to irradiate the laser beam LB in a defocused state in which the in-focus position is intentionally shifted from the surface of the workpiece 10 as necessary during the processing. In the present embodiment, it is preferable to set the defocus value (the amount of shift from the in-focus position in the direction from the workpiece 10 to the inside) to a range of 0 μm or more and 30 μm or less.

Further, in the laser processing apparatus 100, above the stage 4, the optical system 6 is viewed from above, the upper portion of the workpiece 10 is imaged, and the workpiece 10 is illuminated from above the stage 4. The upper lighting system is 7. Further, below the stage 4, the illumination system 8 is irradiated with illumination light below the workpiece 10 from below the stage 4.

The upper observation optical system 6 includes a CCD camera 6a provided above the half mirror 51 (above the lens barrel) and a monitor 6b connected to the CCD camera 6a. Further, the upper illumination system 7 includes an upper illumination light source S1 and a half mirror 71.

The upper observation optical system 6 and the upper illumination system 7 and the illumination optical system 5 are coaxial. More specifically, the half mirror 51 and the condensing lens 52 of the illuminating optical system 5 are shared with the upper observation optical system 6 and the upper illumination system 7. Thereby, the upper illumination is emitted from the upper illumination source S1. The light beam L1 is reflected by the half mirror 71 provided in the lens barrel (not shown), and is transmitted through the half mirror 51 constituting the illumination optical system 5, and then concentrated by the condensing lens 52 to be irradiated onto the workpiece. 10. Further, in the upper observation optical system 6, the bright field image of the workpiece 10 transmitted through the condensing lens 52, the half mirror 51, and the half mirror 71 can be observed while the upper illumination light L1 is being irradiated.

Further, the lower illumination system 8 includes a lower illumination light source S2, a half mirror 81, and a collecting lens 82. In other words, in the laser processing apparatus 100, the lower illumination light source S2 can be emitted and reflected by the half mirror 81, and the illumination light L2 can be irradiated to the workpiece 4 by the condensing lens 82. For example, when the lower illumination system 8 is used, the optical system 6 can observe the transmitted light in the upper portion while the lower illumination light L2 is irradiated onto the workpiece 10.

Further, as shown in FIG. 1, the laser processing apparatus 100 may be provided with an optical system 16 for observing the lower portion of the workpiece 10 as viewed from below. The lower observation optical system 16 includes a CCD camera 16a provided below the half mirror 81 and a monitor 16b connected to the CCD camera 16a. In the lower observation optical system 16, for example, the observation of the transmitted light can be performed while the upper illumination light L1 is irradiated onto the workpiece 10.

Further, the controller 1 further includes a control unit 2 that controls the operation of each part of the apparatus to realize the processing of the workpiece 10 in the later-described aspect, and a program 3p that stores the operation of the laser processing apparatus 100 or is referred to during processing. The memory part of various materials 3.

The control unit 2 is realized by, for example, a general-purpose computer such as a personal computer or a microcomputer, and reads and executes the program 3p stored in the storage unit 3 by the computer, and uses various components as functional components of the control unit 2. achieve.

The memory unit 3 is realized by a memory medium such as a ROM, a RAM, or a hard disk. Further, the memory unit 3 may be realized by realizing the components of the computer of the control unit 2, and may be separately provided separately from the computer such as a hard disk.

In addition to the storage program 3p, the memory unit 3 stores and stores the workpiece 10 Processing position data D1 of the machining position, and storing the conditions for each parameter of the laser light corresponding to the laser processing aspect in each processing mode or the driving condition of the stage 4 (or the set possible range) The machining mode setting data D2.

The control unit 2 mainly includes a drive control unit 21 that controls the operation of various driving portions related to the processing such as the driving of the stage 4 or the focusing operation of the collecting lens 52 by the moving mechanism 4m, and the imaging control unit 22 controls the upper observation. The optical system 6 or the lower observation optical system 16 observes and photographs the workpiece 10; the irradiation control unit 23 controls the irradiation of the laser light LB from the laser light source SL; and the adsorption control unit 24 controls the workpiece of the suction device 11. The suction fixing operation of the pair of stages 4 is performed; and the processing unit 25 performs processing for processing the processing target position based on the supplied machining position data D1 and the machining mode setting data D2.

In the laser processing apparatus 100 having the controller 1 configured as described above, the machining processing unit 25 acquires the machining after the operator has given an instruction to execute the machining in the predetermined machining mode in which the machining position is described in the machining position data D1. The position data D1 is obtained from the machining mode setting data D2, and the conditions corresponding to the selected machining mode are obtained, and the operations of the respective units are controlled by the drive control unit 21 or the illumination control unit 23 to perform an operation corresponding to the condition. For example, the wavelength or output of the laser light LB emitted from the laser light source SL, the repetition frequency of the pulse, and the adjustment of the pulse width are realized by the irradiation control unit 23. Thereby, the processing of the specified machining mode is realized in the machining position to be the object.

Preferably, the laser processing apparatus 100 is configured to be capable of selecting a processing mode corresponding to various processing contents in the controller 1 by the machining processing unit 25 in accordance with the machining processing menu provided by the controller. In this case, the processing menu is preferably provided by the GUI.

With the above configuration, the laser processing apparatus 100 can perform various laser processing very suitably.

<Principles of crack stretching processing>

Next, the cracking extension of one of the processing methods that can be realized in the laser processing apparatus 100 will be described. work. Fig. 2 is a view for explaining an irradiation state of the laser light LB in the crack stretching process. More specifically, FIG. 2 shows the repetition frequency R (kHz) of the laser light LB during the crack stretching process and the moving speed V (mm/sec) of the stage on which the workpiece 10 is placed during the irradiation of the laser light LB. ) is related to the center distance Δ (μm) of the beam spot of the laser light LB. In addition, in the following description, it is assumed that the above-described laser processing apparatus 100 is used, and the projection source of the laser light LB is fixed, and the stage 4 on which the workpiece 10 is placed is moved to realize the laser light. The LB scans the workpiece 10 in the opposite direction. However, even if the workpiece 10 is in a stationary state and the emission source of the laser beam LB is moved, the crack stretching process can be similarly performed.

As shown in Fig. 2, in the case where the repetitive frequency of the laser light LB is R (kHz), a laser pulse (also referred to as unit pulse light) is emitted from the laser light source every 1/R (msec). In the case where the stage 4 on which the workpiece 10 is placed is moved at the speed V (mm/sec), the workpiece 10 is moved by V × during the period from the issuance of a certain laser pulse to the emission of the next laser pulse. (1/R)=V/R(μm), so the distance between the center position of the beam of a certain laser pulse and the center position of the beam of the next laser pulse, that is, the center distance of the beam point Δ(μm) is Δ =V/R decision.

As described above, the beam diameter (also referred to as the beam waist diameter and the dot size) Db of the laser light LB of the workpiece 10 and the center point of the beam spot Δ satisfy the condition of Δ>Db (Expression 1). In the following, each laser pulse does not overlap during the scanning of the laser light.

Further, when the irradiation time of the unit pulse light, that is, the pulse width is set to be extremely short, a phenomenon occurs in the irradiation position of each unit pulse light, that is, the point size narrower than the point of the laser light LB is irradiated. The substance in the approximate central region of the position will scatter or deteriorate in the direction perpendicular to the illuminated surface due to the kinetic energy obtained from the irradiated laser light, and on the other hand, the unit pulse including the reaction force generated by the scattering. The impact or stress generated by the irradiation of light acts around the illuminated position.

Using the above points, if laser pulses are emitted from the laser source (unit When the pulsed light is sequentially and discretely irradiated along the planned line, a minute processing mark is sequentially formed at the irradiated position of each unit pulsed light along the planned line, and the turtle is continuously formed between the respective processing marks. crack. In this way, the crack formed continuously by the crack stretching process becomes the starting point of the division when the workpiece 10 is divided.

Then, the workpiece 10 can be divided by a cracking step of stretching the crack formed by the crack stretching process to the opposite surface of the patterned substrate W by using, for example, a known cracking device. Further, in the case where the workpiece 10 is completely broken in the thickness direction by the crack extension, although the above-described cracking step is not required, even if a part of the crack reaches the opposite surface, the crack is stretched by the crack alone. It is rare for the workpiece 10 to be completely dichotomous, so it is generally accompanied by a breaking step.

In the breaking step, for example, the main surface of the workpiece 10 having the side on which the machining mark is formed is in the lower side, and the two lower side split rods are supported to support both sides of the predetermined line, and the other main The surface is placed next to the fracture position above the predetermined line to lower the upper split rod, thereby performing.

Further, if the center distance Δ of the beam spot corresponding to the pitch of the processing mark is too large, the cracking characteristics are deteriorated and the crack along the planned line cannot be obtained. When cracking and stretching is performed, this point must be taken into consideration to determine the processing conditions.

In view of the above, the optimum conditions for forming the crack stretching process for forming the crack as the starting point of the workpiece 10 are as follows. The specific conditions can be appropriately selected depending on the material or thickness of the workpiece 10 and the like.

Pulse width τ: 1 psec or more and 50 psec or less; beam diameter Db: 1 μm or more and 10 μm or less; stage moving speed V: 50 mm/sec or more and 3000 mm/sec or less; pulse repetition frequency R: 10 kHz or more and 200 kHz or less; Pulse energy E: 0.1 μJ to 50 μJ.

<Substrate with pattern>

Next, a substrate W having a pattern as an example of the workpiece 10 will be described. 3 is a schematic plan view and a partial enlarged view of a substrate W having a pattern.

The substrate W having a pattern is formed by laminating a predetermined element pattern on one main surface of a single crystal substrate (wafer, mother substrate) W1 (see FIG. 4) such as sapphire. The element pattern has a configuration in which a plurality of unit patterns UP each constituting one element wafer are repeatedly arranged two-dimensionally after being singulated. For example, an LED element or the like is a two-dimensionally repeated unit pattern UP as an optical element or an electronic element.

Further, the patterned substrate W has a substantially circular shape in plan view, but has a linear orientation flat OF at one of the outer circumferences. Hereinafter, the direction in which the orientation plane OF is in the plane of the patterned substrate W is referred to as the X direction, and the direction orthogonal to the X direction is referred to as the Y direction.

As the single crystal substrate W1, a thickness of 70 μm to 200 μm is used. The use of a single crystal of sapphire having a thickness of 100 μm is a very suitable example. Further, the element pattern is usually formed to have a thickness of about several μm. Further, the element pattern may have irregularities.

For example, as long as it is a patterned substrate W for LED wafer fabrication, a light-emitting layer composed of a group III nitride semiconductor including GaN (gallium nitride) or other plural thin film layers is epitaxially formed on a single sapphire crystal. Further, the thin film layer is formed by forming an electrode pattern constituting a current-carrying electrode in the LED element (LED wafer).

Further, when the substrate W having the pattern is formed, as the single crystal substrate W1, the plane direction of the crystal face such as the c-plane or the a-plane may be used as the axis in the Y-direction perpendicular to the orientation plane in the main surface. A substrate (also referred to as an off substrate) that imparts an off angle by tilting the normal direction of the principal surface by a few degrees.

The boundary portion of each unit pattern UP, that is, the narrow width region is called cutting Road ST. The dicing street ST is placed at a predetermined position of the substrate W having the pattern, and the laser beam is irradiated along the scribe line ST in a later-described manner, whereby the patterned substrate W is divided into individual element wafers. The scribe line ST is usually a width of about several tens of μm, and is set to have a lattice shape when the element pattern is viewed in plan. However, in the portion of the scribe line ST, the single crystal substrate W1 does not need to be exposed, and the film layer constituting the element pattern at the position of the scribe line ST may be continuously formed.

<Segmentation of patterned substrate W using off substrate>

In the following, the case where the off substrate is used as the single crystal substrate W1 and the patterned substrate W is divided along the scribe line ST, and the crack propagation processing is performed along the processing planned line PL (PL1, PL2) set at the center of the scribe line ST.

Further, in the present embodiment, when the crack propagation processing of the above-described aspect is performed, the surface of the substrate W having the pattern on the side where the element pattern is not provided, that is, the main surface Wa on which the single crystal substrate W1 is exposed is exposed (refer to Figure 4) Irradiation of the laser light LB. In other words, the main surface Wb (see FIG. 4) on the side where the element pattern is formed is placed on the stage 4 of the laser processing apparatus 100 as the surface to be mounted, and the laser light LB is irradiated. Further, in more detail, although the surface of the element pattern has irregularities, since the unevenness is sufficiently smaller than the thickness of the entire substrate W having the pattern, it is substantially regarded as being provided on the side of the patterned substrate W on which the element pattern is formed. There is no problem with the flat main surface. Alternatively, the main surface of the single crystal substrate W1 provided with the element pattern may be regarded as the main surface Wb of the substrate W having the pattern.

This point is not essential in the implementation of the crack stretching process, but in the case where the width of the scribe line ST is small or the film layer is formed to the portion of the scribe line ST, the irradiation of the laser light is reduced. A preferred aspect is the point of view of the effect of the component pattern or the fact that the segmentation is actually achieved. In addition, in FIG. 3, the unit pattern UP or the scribe line ST is indicated by a broken line in order to show that the main surface Wa exposed by the single crystal substrate is the irradiation target surface of the laser light, and the main surface Wb provided with the element pattern faces the opposite side. .

Figure 4 shows the setting of the crack propagation in the laser processing apparatus 100. After the irradiation condition, the schematic cross-sectional view of the crack (crack) CR0 in the thickness direction of the substrate W having the pattern when the crack stretching process is performed along the processing planned line PL1 extending in the X direction. More specifically, it is shown that the patterned substrate W is stretched by the crack CR0 of the cross section perpendicular to the X direction.

In this case, the crack CR0 extends from the processing mark M to the vertical direction, that is, from the processing planned line PL1 along the surface P1 extending in the thickness direction of the patterned substrate W. Therefore, as long as the cracking step is performed, the patterned substrate W is vertically divided at the plane P1 in the X direction. That is, the angle formed by the divided surface and the main surface Wb is 90°.

On the other hand, FIG. 5 is a schematic cross-sectional view showing a state in which a crack (crack) CR1 or CR2 in the thickness direction of the substrate W having a pattern is formed during the crack stretching process along the planned line PL2 extending in the Y direction. More specifically, Fig. 5 shows how the patterned substrate W is stretched by the crack CR1 or CR2 in the cross section perpendicular to the Y direction. 6 is a schematic plan view of the element wafer obtained by combining the pattern shown in FIG. 4 and the pattern shown in FIG. 5 to divide the substrate W having the pattern.

First, FIG. 5(a) shows a crack stretching process along the line to be processed PL2 extending in the Y direction for comparison, which is substantially the same as the crack stretching process in the X direction as shown in FIG. A schematic cross-sectional view of the state of the cracked CR1 of the patterned substrate W in the thickness direction when the processing conditions are performed. Here, the processing in the Y direction is performed under substantially the same processing conditions as the processing in the X direction, and includes not only the case where the irradiation conditions of the two are completely the same, but also the peak power of the laser light LB when the former is processed. (or pulse energy) is set to be 90% or more and 100% or less of the peak power (pulse energy) at the time of the latter processing.

As shown in FIG. 5(a), when the crack stretching processing along the processing planned line PL2 extending in the Y direction is performed under substantially the same processing conditions as the processing in the X direction, the crack CR1 is not from the processing mark M. Straight downward, that is, from the processing planned line PL2, extending along the surface P2 extending in the thickness direction of the patterned substrate W, and the more away from the processing mark M, the more from the surface P2 Stretched away from the situation. As a result, in the main surface Wb on the side including the element pattern, the end position T1 of the crack CR1 is obtained from the surface P2 by the distance w0. Next, when the patterned substrate W in which the crack CR1 is formed in such a manner is broken, the divided surface is in a state in which the opposing surface P2 is inclined. Specifically, the angle of the foot formed by the divided surface and the main surface Wb is also within a maximum of about 83°.

Further, the stretching of the crack CR1 in this aspect is remarkable when the off substrate is used as the single crystal substrate W1, but may be generated without using the off substrate, and the reason may not necessarily be specified. In addition, in FIG. 5(a), the terminal position T1 is located on the left side when the viewing surface is viewed from the surface P1, but the arrangement relationship between the surface P1 and the terminal position T1 is not limited thereto, and the terminal position T1 may be located on the surface P1. By the right side of the picture.

6(a) shows the element wafer CP obtained by combining the aspect shown in FIG. 4 with the aspect shown in FIG. 5(a), but the division plane in the Y direction is offset from the processing planned line PL2. The unit pattern UP is in a state of being deviated in the left-right direction when viewing the drawing.

In the case shown in Fig. 5 (a), the case where the end position T1 of the crack CR1 is received in the scribe line ST is exemplified, but the case where the scribe line ST is narrow or the inclination of the crack CR1 is large is large. There is also a case where the terminal position T1 is not received in the cutting path ST. In this case, the obtained component wafer may become a defective product. Therefore, it is preferable that the inclination of the inclined CR1 connected to the split surface is suppressed as much as possible.

On the other hand, Fig. 5(b) shows the state of the crack CR2 in the thickness direction of the patterned substrate W which is subjected to the crack stretching process extending in the Y-direction processing line PL2 in the present embodiment. Schematic cross-sectional view. In the present embodiment, the peak power (or pulse energy) of the laser beam LB when the crack stretching process is performed along the planned processing line PL2 extending in the Y direction is set in the X direction processing as shown in FIG. The peak power (or pulse energy) of the laser light LB is 50% or more and 70% or less.

Similarly, the crack CR2 generated in this case is similar to the crack CR1 shown in Fig. 5(a), and the crack CR2 does not extend from the processing mark M to the vertical direction, that is, from the processing planned line PL2. The surface P2 in the thickness direction of the patterned substrate W is stretched to extend from the surface P2 as it goes away from the processing mark M. However, the crack CR2 does not reach the opposite side of the patterned substrate W, and its end position T2 stops inside the substrate. This is the effect of making the peak power (or pulse energy) of the laser light LB at the time of performing the crack stretching processing weaker than the processing in the X direction. In other words, in the present embodiment, the peak power (or pulse energy) of the laser beam LB during the crack propagation processing in the Y direction is set so that the crack CR2 does not reach the opposite side of the irradiated surface of the substrate W having the pattern. Value.

Hereinafter, such a crack stretching process for the Y direction is particularly referred to as a partial crack stretching process.

Part of the crack propagation process is performed in the Y direction, and after the crack CR2 is stopped in the inside of the patterned substrate W, the cracking step is performed, but a new crack CR3 is generated in the cracking step. As shown in Fig. 5(b), the terminal position T2 extends in the vertical direction, that is, in parallel with the surface P2. In this case, in the main surface Wb having the element pattern side, the distance W1 from the surface P2 is the end position T3 of the crack CR3, but the distance w1 between the end position T3 and the surface P2 becomes smaller than that of FIG. The distance w0 shown in (a) is small. The dividing surface formed in this case has irregularities strictly, but as a whole, the degree of inclination of the opposing surface P2 is smaller than when the laser beam LB is irradiated with the same irradiation condition as the X direction. Specifically, the angle formed by the divided surface and the main surface Wb is about 85 to 87 degrees.

Fig. 6(b) is an element wafer CP obtained by combining the aspect shown in Fig. 4 with the aspect shown in Fig. 5(b), as compared with the case shown in Fig. 6(a), since Since the deviation of the division plane from the machining planned line PL2 is small, the deviation of the unit pattern UP in the left-right direction when viewing the drawing is suppressed.

In other words, in the case of the present embodiment, by performing the partial crack stretching process in the Y direction, the inclination of the split surface can be more compared with the case where the Y direction cracking and stretching process is performed under the same irradiation conditions as the X direction. Suppressed, not easy to produce stretched cracks from the cutting track ST super Out.

However, the division of the patterned substrate W to which the partial crack stretching is applied is effective even when the single crystal substrate W is not the off substrate as described above. The reason for this is that, as described above, the inclination of the split surface may occur even when the substrate is not off, and the same effect can be exerted at this time. Alternatively, as long as the crack CR2 extends from the processing mark to the vertical direction and stops inside the patterned substrate W, in the subsequent cracking step, the crack CR3 is directly extended vertically downward, and the inclination of the split surface does not occur. As a result, it has become a good division.

As described above, according to the present embodiment, the substrate W having the pattern is cut along the scribe line ST in the X direction parallel to the orientation plane OF and the scribe line ST in the Y direction perpendicular thereto by the crack stretching process. When the division is performed, the crack propagation in the Y direction is set to be 50% or more and 70% or less of the peak power of the laser light imparted by the crack propagation processing in the X direction, that is, partial cracking is performed. Stretching processing. Thereby, the division of the inclination of the division surface can be sufficiently and surely suppressed.

The sapphire single crystal which is a substrate on which the crystal plane is inclined with respect to the main surface in the Y direction is referred to as a single crystal substrate W1, and a plurality of scribe lines ST in two directions of XY are prepared on the single crystal substrate W1. The patterned substrate W is subjected to a normal crack stretching process in the X direction and partially cracked in the Y direction, thereby singulating it. At this time, the processing conditions are different in two ways (more specifically, even if the combination of the processing conditions in the X direction and the processing conditions in the Y direction are different), the first and second embodiments are respectively .

Further, for comparison, the processing conditions in the Y direction of the first embodiment and the second embodiment were processed in substantially the same manner as the processing conditions in the X direction, and were respectively Comparative Example 1 and Comparative Example 2.

For the samples obtained after the processing in each of the examples and the comparative examples, the cross section perpendicular to the Y direction was observed with an optical microscope in order to observe the inclination of the divided surface along the Y direction. Further, the angle of inclination of the divided surface along the Y direction with respect to the main surface Wb is calculated from the observed image. In addition, the calculation of the inclination angle is performed by obtaining an angle between the line segment connecting the main surface Wa and the end surface of the main surface Wb on the same end side in the X direction and the main surface Wb in the optical microscope.

The calculation results of the processing conditions and the tilt angle of Example 1 and Comparative Example 1 are shown in Table 1. Moreover, the calculation results of the processing conditions and the inclination angle of Example 2 and Comparative Example 2 are shown in Table 2.

Further, in Tables 1 and 2, the repetition frequency and the pulse width (beam spot interval) and the peak power and the pulse energy are expressed as values in the X direction of each of the first embodiment (displayed in the column of "common" Ratio). Further, the defocus value was 13 μm.

Further, in FIGS. 7 to 10, optical microscope images of the cross sections perpendicular to the Y direction of Example 1, Comparative Example 1, Example 2, and Comparative Example 2 are shown. In addition, FIG. 7 to FIG. 10 are the photographers who hold the sample in a substantially horizontal posture and view both sides of the left and right directions when viewing the drawing. The division is obtained by machining in the Y direction. Further, in FIGS. 7 to 10, for the sake of reference, a dotted line extending vertically upward and downward is added.

From the calculation results of the inclination angles shown in FIGS. 7 to 10 and Tables 1 and 2, it is understood that the samples of the examples of the partial crack stretching process in which the power ratio shown in FIGS. 7 and 9 is about 60% are obtained. Compared with the sample of the comparative example in which the power ratio shown in Figs. 8 and 10 was (substantial) 100%, the degree of inclination of the divided surface along the Y direction was small.

This result shows that the partial crack propagation process can effectively suppress the inclination of the split surface in the Y direction.

CR1~CR3‧‧‧ crack

P2‧‧‧ face

PL, PL2‧‧‧ processing line

ST‧‧‧ cutting road

Terminal position of T1, T3‧‧ (crack)

UP‧‧‧ unit pattern

W‧‧‧patterned substrate

W1‧‧‧Single crystal substrate

Claims (5)

A method for processing a patterned substrate, wherein the patterned substrate is formed by repeatedly arranging a plurality of unit patterns two-dimensionally on a single crystal substrate, and includes: a dividing starting point forming step along the substrate having the pattern The first predetermined dividing line extending in the first direction along the orientation flat surface and the second predetermined dividing line extending in the second direction orthogonal to the first direction are irradiated with the laser light, thereby having the pattern The substrate is formed in a lattice shape to form a plurality of division starting points; and the breaking step is performed by singulating the patterned substrate along the dividing starting point; the dividing starting point forming step includes a crack stretching processing step, The crack stretching processing step is performed by scanning the laser beam along the first and second division lines, and forming a processing mark on the workpiece by the pulse light of each unit of the laser light along the first and The second division planned line is located at a discrete portion, and the crack is stretched from the respective processing marks to the workpiece; in the crack stretching processing step, the first division is along the first division When the dividing line forms the starting point of the division, the laser beam is irradiated to the first processing condition in which the crack reaches the main surface of the substrate having the pattern opposite to the main surface on which the processing mark side is formed, and the second division is performed along the second division. When the predetermined line forms the starting point of the division, the laser beam is irradiated with the second processing condition in which the crack stops in the inside of the patterned substrate. The processing method of the patterned substrate according to the first aspect of the invention, wherein the peak power of the laser beam when the dividing start point is formed along the second dividing line is formed as described above along the first dividing line The peak power at the time of starting the division is 50% or more and 70% or less. The method of processing a substrate having a pattern according to the first or second aspect of the invention, wherein the main surface of the substrate having the pattern on which the unit pattern is not formed is the thunder The illuminated surface of the light. The method for processing a patterned substrate according to claim 1 or 2, wherein the single crystal substrate has a predetermined crystal in a direction perpendicular to an orientation plane in a main surface of the patterned substrate. The surface of the face is inclined a few degrees away from the normal direction of the main surface. The method for processing a patterned substrate according to the third aspect of the invention, wherein the single crystal substrate has a predetermined crystal plane by using a direction perpendicular to the orientation plane in a main surface of the patterned substrate. The off-plane is inclined a few degrees from the normal direction of the main surface.