TWI502764B - The processing method of the substrate with LED pattern - Google Patents

Description

Method for processing substrate with LED pattern

The present invention relates to a processing method for singulating a patterned substrate formed by repeatedly arranging a plurality of unit patterns on a substrate.

An LED (Light Emitting Diode) element is manufactured by processing a unit pattern of LED elements repeatedly on a substrate (wafer, mother substrate) such as sapphire, for example. The patterned substrate (substrate with LED pattern) is divided (divided) and segmented (wafered) at a breaking position called a slab which is arranged in a lattice shape. A laser scribing method such as an ablation method or an LMA (Laser Melting Alteration) method is known as a method of forming a starting point of the dividing starting point at the time of the breaking (for example, refer to the patent document) 1 and patent document 2).

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open Publication No. 2004-165226

[Patent Document 2] International Publication No. 2006/062017

When using the laser scribing method to form the starting point of the segmentation and then breaking it, whether using the ablation method or using the LMA (laser melting metamorphism) method, the substrate is irradiated with the laser light. A work-affected layer is formed on the surface. If the work-affected layer remains, there is a problem that light from the light-emitting portion of the LED element is absorbed, and light-emitting efficiency is obtained. (ie brightness) is reduced.

There has also been proposed a method of suppressing the decrease in luminance by reducing the formation volume of the work-affected layer as much as possible. However, as long as a certain degree of the work-affected layer remains, a slight decrease in brightness is inevitably caused.

The present invention has been made in view of the above problems, and an object thereof is to provide a method for processing a patterned substrate in which an altered layer is not left on the LED wafer after the division.

In order to solve the above problems, the invention of claim 1 is a method for processing a substrate having an LED pattern, which is characterized in that an LED pattern is formed by repeatedly arranging a plurality of LED unit patterns on a base substrate. a method of processing a substrate, and the processing method includes: a scribing step of illuminating the substrate with the LED pattern on the substrate with the LED pattern by arranging the laser light along a predetermined dividing line; a step of removing the processed metamorphic layer by immersing the substrate with the LED pattern subjected to the scribing step in an etching solution; and a breaking step of causing the substrate with the LED pattern to pass through the etching step The substrate was separated by scribe lines.

According to a method of processing a substrate having an LED pattern according to claim 1, the invention of claim 2 is characterized in that the step of forming the protective film is performed after the step of forming a protective film, and the step of forming the protective film is performed on the substrate having the LED pattern. A protective film is formed on the pattern forming surface; and the breaking step is performed after the protective film removing step of removing the protective film.

A method for processing a substrate with an LED pattern according to claim 2, a technical method The invention of claim 3 is characterized in further comprising an electrode forming step of forming an electrode corresponding to each of the plurality of LED unit patterns on the substrate having the LED pattern through the protective film removing step; In the above-described breaking step, the substrate having the LED pattern on which the electrode is formed is divided.

The method of processing an LED pattern substrate according to any one of claims 1 to 3, wherein the base substrate is a sapphire substrate; and the etching solution is hot phosphoric acid, hot phosphoric acid and hot sulfuric acid. Mixing either acid or hot melt potassium hydroxide.

The method for processing a substrate having an LED pattern according to any one of claims 1 to 4, wherein the invention of claim 5 is characterized in that, in the scribing step, the self-designated one is irradiated by scanning and along the predetermined dividing line Forming the processed region by the pulsed laser light emitted from the light source, wherein the processed region includes a portion continuous in the first direction, but a state of the cross section perpendicular to the first direction changes in the first direction; and The processed region in the etching step is the scribe line.

The method for processing a substrate having an LED pattern according to any one of claims 1 to 4, wherein the invention of claim 6 is characterized in that, in the scribing step, the self-designated one is irradiated by scanning and along the predetermined dividing line a pulsed laser beam emitted from a light source, wherein the processed region is formed on a surface of the substrate having the LED pattern, the processed region including: a first region continuous in a first direction; and a second region including a portion that is connected to the first region but is discontinuous in the first direction; and the processed region that has passed through the etching step is the scribe line.

The method of processing an LED pattern substrate according to any one of claims 1 to 4, wherein the invention of claim 7 is characterized in that, in the scribing step, the self-designated one is irradiated by scanning and along the predetermined dividing line Forming the processed region by pulsed laser light emitted from a light source, wherein the processed region is formed by connecting a plurality of substantially elliptical tapered or substantially wedge-shaped unit processed regions in a first direction; The processed area becomes the above-mentioned scribe line.

The method for processing a substrate having an LED pattern according to any one of claims 5 to 7, wherein the invention of claim 8 is characterized in that: the beam point of each unit pulse of the pulsed laser light is along the first direction The pulsed laser light is scanned under discrete illumination conditions to modulate the illumination range on the surface of the substrate having the LED pattern.

According to a seventh aspect of the present invention, in a method of processing an LED pattern substrate, the invention of claim 9 is characterized in that the LED pattern is modulated by scanning the pulsed laser light in the first direction under the following irradiation conditions. An irradiation range on the surface of the substrate, wherein the irradiation condition is: when the repetition frequency of the pulsed laser light is R (kHz), the relative movement speed of the pulsed laser light with respect to the substrate having the LED pattern is set to V (mm/sec), when the predetermined formation width in the direction orthogonal to the first direction of the processed region on the surface of the substrate having the LED pattern is W (μm), 10 (kHz) ≦ R ≦200 (kHz) and 30 (mm/sec) ≦V ≦ 1000 (mm/sec), indicating that the V/R of the center interval of the beam point of the above-mentioned pulsed laser light satisfies V/R ≧ 1 (μm) and W/4 (μm) ≦V / R ≦ W / 2 (μm) relationship.

According to the inventions of the first aspect to the ninth aspect of the invention, the substrate having the LED pattern is subjected to the scribe processing by the laser light, followed by the wet etching treatment to remove the processed altered layer, and then the substrate is separated by a single The chipping, and thus, can effectively and surely obtain light-emitting efficiency superior to that of the prior LED elements.

In particular, according to the inventions of the fifth aspect to the ninth aspect of the invention, by forming irregularities in the processed region which becomes the end portion of the LED wafer after singulation, an LED element having more excellent light efficiency can be obtained.

<Summary order of singulation processing>

First, the procedure of the singulation processing of the substrate having the LED pattern including the method for processing the substrate having the LED pattern of the present embodiment will be briefly described. Fig. 1 is a view showing an outline of a procedure for processing a substrate having an LED pattern in the embodiment.

As shown in FIG. 1, first, a substrate (hereinafter, also simply referred to as a substrate) 10 having an LED pattern is prepared (step S1). Fig. 2 is a schematic cross-sectional view showing the configuration of the substrate 10 before the processing for singulation in the present embodiment. In the substrate 10, an LED pattern 102 is provided on one main surface of a sapphire substrate (sapphire single crystal substrate) 101.

Further, a substrate having a thickness of 400 μm to 700 μm is used as the sapphire substrate 101. A preferred example uses a sapphire substrate 101 having a thickness of 500 μm. Further, the LED pattern 102 is usually formed to a thickness of several μm. In addition, the LED pattern 102 may have irregularities.

The LED pattern 102 has a configuration in which a plurality of unit patterns UP (unit patterns) constituting one LED chip are individually arranged in a single element. The LED pattern 102 is formed by epitaxial formation of a light-emitting layer including, for example, a group III nitride semiconductor including GaN (gallium nitride) and a plurality of other thin film layers. The boundary portion of each unit pattern UP becomes a divided position of the substrate 10 and is a dicing street ST that irradiates laser light. The scribe line ST is usually set to have a width of about several tens of μm, and is set so as to form a lattice shape when the LED pattern 102 is viewed in plan. Further, it is also possible to continuously form the film layer constituting the LED pattern 102 without exposing the sapphire substrate 101 to the portion of the scribe line ST. Further, an electrode pattern for externally electrifying is provided on the LED element (LED wafer). However, in the case of the present embodiment, no electrode is provided on each unit pattern UP on the substrate 10 before the processing. The electrode system is formed by the treatment of the latter stage.

Next, a protective film 103 is formed on the LED pattern 102 of the prepared substrate 10 (step S2). FIG. 3 is a view showing the substrate 10 on which the protective film 103 is formed. The protective film 103 is provided to protect the LED pattern 102 during the etching process in the subsequent stage. A preferred example of the protective film 103 is a SiO ₂ thick film or a resist film having a thickness of about several μm. The protective film can be formed by a well-known thick film forming technique such as a coating method (printing method).

After the protective film 103 is formed, a scribe process (step S3) is subsequently performed to form a scribe line at the position of the scribe line ST of the substrate 10. Further, in general, an alignment process for finely adjusting the arrangement position of the substrate having the LED pattern is performed before the scribe processing. The alignment action can be performed using well-known techniques, as long as it is appropriate according to the processing pattern The situation can be carried out. By performing the above-described alignment operation, the position of the processing position in the scribe processing, that is, the position of the scribe line ST can be accurately determined.

Fig. 4 is a view schematically showing a state of the scribing process. The scribing process is performed by scanning and irradiating the laser beam LB along the position of the scribe line ST by the laser processing apparatus. In the scribing process, the laser light LB is irradiated to the position of the scribe line ST through the protective film 103 in a state where the substrate 10 is covered by the protective film 103. Fig. 5 is a view showing the substrate 10 after the scribing process. Fig. 6 is a partially enlarged view centering on the broken line portion A of Fig. 5. By performing the dicing processing, the processed region RE, which is a substantially triangular or wedge-shaped groove portion, is formed at a position where the leading end portion reaches the sapphire substrate 101 at the position of the scribe line ST of the substrate 10. Further, the width d1 of the processed region RE on the surface of the substrate 10 is about 5 μm to 20 μm, and the depth d2 is about 10 μm to 30 μm. The depth d2 is preferably 20 μm or more. The details of the scribing process and the specific configuration of the laser processing apparatus will be described below.

After the scribe processing is completed, an etching process is subsequently performed (step S4). The etching treatment is performed by immersing the substrate 10 after the scribe processing in the etching solution. The etching treatment is performed in order to purify the processed region RE of the substrate 10 after the scribe processing.

Although not shown in FIG. 5, as shown in FIG. 6, after the scribe processing, the heating is caused by the irradiation of the laser light LB and the subsequent cooling, so that the side of the processed region RE is attached. A process-affected layer TR is formed. The processed metamorphic layer TR is a polycrystalline or amorphous material formed by metamorphism of a constituent material of the substrate 10 (mainly sapphire) or a mixture of the polycrystalline or amorphous materials. An optical opaque layer is formed. If the processed altered layer TR of the LED element obtained by singulation remains, the light from the light-emitting layer is absorbed by the processed altered layer TR, so that the light-emitting efficiency (ie, brightness) is lowered, so that it is necessary to remove the processing deterioration. Layer TR. In the present embodiment, the work-affected layer TR is removed by an etching process before singulation. Then, only the processed region RE after the processing of the altered layer TR is removed becomes the scribe line SC. The etching treatment is performed by wet etching in which the entire substrate 10 is immersed in an etching solution. Details of the etching process will be described below.

The substrate 10 after the etching treatment is appropriately subjected to a cleaning process. Further, when the etching process is performed, the other main surface (back surface) of the sapphire substrate 101 on which the LED pattern 102 is not formed is also etched. Therefore, for the sapphire substrate 101, it is preferable to use a substrate having a larger thickness than the previous substrate.

As described above, by etching the processed region RE, the work-affected layer TR which is a cause of lowering the light-emitting efficiency among the LED elements is appropriately removed.

After the etching process is completed, the protective film is removed (step S5). The removal of the protective film is carried out by immersion in hydrofluoric acid in the case of forming a thick film of SiO ₂ , and by immersion in hydrogen peroxide in the case of forming a resist film.

After the removal of the protective film is completed, the electrode is formed on the substrate 10 which has been subjected to a process such as washing, drying, etc. (step S6). The electrode formation is performed by a well-known method such as a photolithography process or a printing process for a predetermined position on the LED pattern 102. As the electrode forming material, a metal material which is usually used for forming an electrode such as Al, Ni, Ti, Pt, Au, or Pd can be appropriately selected and used. material.

After the electrode formation is completed, the substrate 10 is next divided (divided) along the scribe line SC (step S7). Further, when the thickness of the sapphire substrate 101 after the etching process is large, the back surface 101a (see FIG. 7) of the sapphire substrate 101 on which the LED pattern 102 is not formed may be polished before the breaking. The thickness of the sapphire substrate 101 is reduced (for example, the thickness is 100 μm or less).

Fig. 7 is a view showing a state in which the substrate 10 is divided. The breaking of the substrate 10 can be performed by a three-point support method. In other words, in the state in which the substrate 10 is placed on the lower side of the processed region RE, and the two lower-side breaking bars B1 and B2 are supported on both sides of the scribe line SC, the upper-side breaking bar B3 is provided. The breaking position BP which is directed toward the back surface 101a of the sapphire substrate 101 and directly below the front end portion of the scribe line SC (directly above in FIG. 7) is lowered, whereby the substrate 10 can be divided.

By performing the above-described division on all the scribe lines SC formed on the substrate 10, the substrate 10 is diced (wafered) into individual LED elements.

<Details of scribing processing>

The above-described scribe processing for forming a scribe line can be performed in two processing modes of a continuous processing (overlap processing) mode and a discrete processing mode. In a nutshell, the continuous processing mode is a mode in which a uniform processed region RE is formed along the scribe line ST, and is subjected to a normal laser processing mode. In the case of the continuous machining mode, the cross-sectional shape of the scribe line is substantially the same regardless of the position. On the other hand, the discrete processing mode is a mode in which the processed region RE having a concavo-convex shape is formed along the scribe line ST. These modes can be changed by Ray The illumination of the light LB is switched. Further, in the following description, the center line of the scribe line ST is also referred to as a predetermined dividing line.

8 is a view for explaining the difference in the processing mode of the scribing process, the repetition frequency of the laser light LB used in the scribing process, the moving speed of the stage on which the substrate 10 is placed, and the laser light LB. The relationship between the center spacing of the beam spots is explained.

When the repetition frequency of the laser light LB is R (kHz), one laser pulse is emitted from the laser light source in units of 1/R (msec). When the stage on which the substrate with the LED pattern is placed is moved at the speed V (mm/sec), the substrate with the LED pattern moves by V×(1/R) from the time a pulse is emitted until the next laser pulse is emitted. ) = 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 emitted, that is, the center distance of the beam point Δ (μm) is Δ = V / R decided.

Therefore, if the beam diameter (beam waist diameter) D of the laser light LB on the surface of the substrate 10 is larger than Δ=V/R, the respective laser pulses overlap, but when the beam diameter D is smaller than Δ=V/R, each The laser pulses do not overlap. Therefore, according to the relationship between the beam diameter D and the center distance Δ of the beam spot, processing in different processing modes can be realized. Specifically, in the case of the continuous processing mode, the substrate 10 is irradiated with the laser light LB under the condition that D>Δ is satisfied. On the other hand, in the case of the discrete processing mode, the substrate 10 is irradiated with the laser light LB under the condition that D < Δ is satisfied. For example, when the beam diameter D is about 3 μm, processing in the discrete processing mode can be realized as long as about Δ > 3 μm. Processing in the continuous processing mode can be achieved as long as approximately Δ<1 μm.

The processing system in the continuous processing mode can also be as disclosed in Patent Document 2 Since the well-known processing processing performed by the prior laser processing apparatus is performed, the detailed description is abbreviate|omitted in this embodiment. Hereinafter, the processing in the discrete processing mode will be described in detail.

9 and 10 are diagrams schematically showing the relationship between the irradiation pattern of the laser light LB in the discrete processing mode and the formed region RE to be formed. In FIGS. 9 and 10, for the sake of convenience, a three-dimensional coordinate is shown in which the direction of the predetermined dividing line L is set to the x-axis direction, and the direction orthogonal to the x-axis on the surface of the substrate 10 is set to the y-axis direction. The direction orthogonal to the surface of the substrate 10 is set to the z-axis direction (the same applies to the following figures). Figure 9 is a perspective view. Figure 10 is an XY top view (center view), A-A' cross-sectional view (right side view), B-B', C-C', and D-D' cross-sectional view of the processed area RE (left side view) . The A-A' sectional view is a sectional view on a plane parallel to the predetermined dividing line L. The B-B', C-C', and D-D' cross-sectional views are cross-sectional views on the surface perpendicular to the predetermined dividing line L at different positions on the predetermined dividing line L.

In the discrete processing mode, the laser light LB is irradiated under irradiation conditions in which the beam spot BS of each unit pulse of the laser light LB is discretely distributed in the direction of the predetermined dividing line L. As described above, this is achieved by the relationship between the beam diameter D and the beam spot center interval Δ=V/R satisfying D < Δ. Preferably, at 10 (kHz) ≦ R ≦ 200 (kHz), 30 (mm/sec) ≦ V ≦ 1000 (mm / sec), D < V / R and W / 4 (μm) ≦ V / R ≦ The irradiation conditions of the laser light and the driving conditions of the platform are set within the range of W/2 (μm). Here, W is a predetermined width of the processing of the scribe line in the direction perpendicular to the predetermined dividing line L.

Further, the discrete distribution of the beam spot BS when the laser light LB is scanned in the direction of the predetermined dividing line L means that there is a thunder in the direction of the predetermined dividing line L. The portion where the light LB is irradiated and the portion where the laser light LB is not irradiated, the scribed processing in the discrete processing mode is equivalent to modulating the irradiation range on the surface of the substrate having the LED pattern to illuminate the laser light of the LB light. Variable processing.

When the laser beam LB is scanned under such conditions, the processed region RE having the shape shown in Figs. 9 and 10 is formed. In summary, although the beam points of the respective laser pulses are discrete, the processed region RE has a shape in which a plurality of unit processed regions of a substantially elliptical cone shape (or a substantially wedge shape) formed by respective laser pulses are formed. REu is formed by connecting in the direction in which the dividing line L is predetermined.

In more detail, the processed region RE is continuous on the surface of the substrate 10, and on the other hand, as shown in the cross-sectional views of B-B', C-C', and DD' of FIGS. 9 and 10, The width and the cross-sectional shape in the direction perpendicular to the predetermined dividing line L differ depending on the position of the predetermined dividing line L direction (x-axis direction). In other words, the processed region RE may include a portion continuous in the direction (x-axis direction) of the predetermined dividing line L, but has a shape in which the state perpendicular to the x-axis direction (yz cross-section) is in the x-axis direction. There is a change in it. Further, in the case shown in FIG. 10, the processed region RE is formed in such a manner that the processing width in the y-axis direction near the surface of the substrate 10 changes between w1 and w3 in the x-axis direction. Assuming that the processing width w2 on the C-C' section is equal to the processing predetermined width W, the processing in the discrete processing mode may also be repeatedly formed alternately with a region having a processing width greater than the processing predetermined width W and having a processing width smaller than the processing width. The aspect of the W width processing area. However, in the actual processing, there are also cases of w1≒w2, w3≒w2.

In addition, according to another insight, as shown in the cross-sectional view of A-A' of FIG. 10, The processed region RE includes a continuous region RE1 continuous in the x-axis direction near the surface of the substrate 10, and a discontinuous region RE2 connected to the continuous region RE1 in the y-axis direction but discontinuous in the x-axis direction.

In either case, the XY section and the zx section of the processed region RE have irregularities in the x-axis direction. Although the pitch between the bumps differs depending on the irradiation conditions of the laser light LB or the driving conditions of the stage 7, it is in the range of several μm to several tens of μm.

The provision of the concavities and convexities corresponds to the provision of irregularities in one of the end faces of the LED chips obtained by the breaking, and this has an effect of improving the light-emitting efficiency from the light-emitting layer for the LED chips. The reason is that it is easier to cause the light from the light-emitting layer to be totally reflected and penetrated to the outside when the end surface of the wafer has irregularities as compared with the case where the end surface is flat.

The specific value of V or R can be appropriately determined in consideration of the material of the substrate 10, the absorptivity, the thermal conductivity, the melting point, and the like. Further, the irradiation energy of the pulse can be appropriately determined within the range of 10 μJ to 1000 μJ.

Further, when V/R<W/4 (μm), the overlap of the unit processed region REu becomes large, and the difference between the predetermined processing width and the actual processing width becomes small, thereby substantially eliminating the problem with the continuous processing mode. The difference in processing. On the other hand, when V/R>W/2 (μm), since the distance between adjacent beam spots becomes too large, eventually the respective unit processed regions REu become unconnected, and therefore, the processed region RE becomes It is not continuous and cannot form a line.

<Laser processing device>

Fig. 11 is a schematic view showing the configuration of a laser processing apparatus 50 which can perform the processing in the above-described continuous processing mode and discrete processing mode. Laser The processing device 50 mainly includes a platform 7 on which the substrate 10 is placed, and a controller 1 that performs various operations (observation operation, alignment operation, processing operation, and the like) of the laser processing device 50, and can be placed by the pair The substrate 10 on the stage 7 is configured to irradiate the laser light LB and process the substrate 10.

The platform 7 is configured to be movable in the horizontal direction by the moving mechanism 7m. The moving mechanism 7m moves the stage 7 in the horizontal direction of the designated XY in the horizontal plane by the action of a driving mechanism (not shown). Thereby, the movement of the laser light irradiation position or the like can be achieved. Further, the moving mechanism 7m may perform a rotation (θ rotation) operation in a horizontal plane centering on the designated rotation axis independently of the horizontal driving.

Further, in the laser processing apparatus 50, the front side observation or the self-loading can be directly observed from the irradiation of the substrate 10 to the side of the laser light (this side is referred to as the front side) by an imaging unit (not shown). The side on the side of the stage 7 (this side is referred to as the back side) is observed from the back side of the stage 7 and the like.

As described above, the stage 7 is formed of a transparent member such as quartz, and a suction pipe (not shown) as an intake passage for adsorbing and fixing the substrate 10 is provided inside. The suction piping is provided by drilling a hole at a specified position of the platform 7 by, for example, machining.

In the state in which the substrate 10 is placed on the stage 7, the suction pipe is sucked by a suction mechanism 11 such as a suction pump, and the front end of the stage 7 on the stage 7 provided on the suction pipe is placed. The suction holes impart a negative pressure, thereby fixing the substrate 10 (and the transparent substrate protection sheet 4) to the stage 7. In addition, in FIG. 11, the case where the substrate 10 to be processed is adhered to the transparent substrate protective sheet 4 is exemplified, but it is not necessary to adhere the transparent substrate protective sheet 4.

More specifically, in the laser processing apparatus 50, the laser light LB is emitted from the laser light source SL, and is reflected by a dichroic mirror 51 provided in a lens barrel (not shown), and the condensing lens is used. The laser light LB is condensed so as to be focused on the processed portion of the substrate 10 placed on the stage 7, and is irradiated onto the substrate 10. By combining the irradiation of the above-described laser light LB and the movement of the stage 7, the substrate 10 can be processed while the laser light LB is relatively scanned on the substrate 10. For example, in order to divide the substrate 10, processing for performing groove processing (scratching) or the like can be performed on the surface of the substrate 10.

Further, in the laser processing apparatus 50, when processing is performed, the laser light LB may be irradiated in a defoucs state in which the focus position is intentionally shifted to the surface of the substrate 10 as needed. In the present embodiment, it is preferable to set the defocus value (the amount of shift of the focus position from the surface of the substrate 10 toward the inside) to a range of 10 μm or more and 40 μm or less.

A suitable aspect is to use a Nd:YAG (Neodymium-doped Yttrium Aluminium Garnet) laser as the laser source SL. Alternatively, it may be a state in which a Nd:YVO ₄ (Neodymium doped Yttrium Orthovanadate) laser or other solid laser is used. Further, the laser light source SL preferably has a Q switch.

Further, the wavelength or power of the laser light LB emitted from the laser light source SL, the repetition frequency of the pulse, the adjustment of the pulse width, and the like are realized by the illumination control unit 23 of the controller 1. When the processing control unit 25 issues a designated setting signal obtained by the irradiation control unit 23 in accordance with the processing mode setting data D2, the irradiation control unit 23 sets the irradiation conditions of the laser light LB in accordance with the setting signal.

In this embodiment, it is preferable that the wavelength of the laser light LB belongs to a wavelength range of 150 nm to 563 nm, and in the case where the Nd:YAG laser is set as the laser light source SL, the preferred aspect is to use the same. 3 times higher frequency harmonics (wavelength approx. 355 nm). Further, the repetition frequency of the pulse is preferably 10 kHz or more and 200 kHz or less, and the pulse width is preferably 10 nsec or more and 200 nsec or less. The peak power is preferably 1.5 W or more and 10 W or less.

The laser light LB is preferably irradiated by the condenser lens 52 to a beam diameter of about 1 μm to 10 μm. In the above case, the peak power density in the irradiation of the laser light LB is about 1 GW/cm ² to 10 GW/cm ² .

Further, the polarization state of the laser light LB emitted from the laser light source SL may be either circularly polarized or linearly polarized. In the case of linearly polarized light, it is preferable that the polarization direction is substantially parallel to the scanning direction from the viewpoint of the bending of the processed cross section and the energy absorption rate in the crystalline material to be processed, for example, the angle formed by the two is ± Within 1 °. Further, when the emitted light is linearly polarized, it is preferable that the laser processing apparatus 50 includes an attenuator (not shown). The attenuator is disposed at an appropriate position on the optical path of the laser light LB, and functions to adjust the intensity of the emitted laser light LB.

The controller 1 further includes a control unit 2 that controls the operations of the above-described respective units to realize processing of the substrate 10 in the following various aspects; and a program 3p that controls the operation of the laser processing apparatus 50; or the storage unit 3 It stores various materials that are referred to during processing.

The control unit 2 is realized by a general-purpose computer such as a personal computer or a micro computer, and the program 3p stored in the storage unit 3 is read and executed by the computer, thereby The component is realized as a functional component of the control unit 2.

Specifically, 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 7 by the moving mechanism 7m or the focusing operation of the collecting lens 52; The control unit 22 controls imaging of the substrate 10 by an imaging unit (not shown), an illumination control unit 23 that controls illumination of the laser light LB from the laser light source SL, and an adsorption control unit 24 that controls the suction mechanism 11 The substrate 10 is adsorbed and fixed to the stage 7; and the processing unit 25 performs processing processing at the processing target position in accordance with the given processing position data D1 and the machining mode setting data D2.

The storage unit 3 is realized by a storage medium such as a ROM (Read Only Memory), a RAM (Random Access Memory), or a hard disk. Further, the aspect of the storage unit 3 may be realized by realizing the components of the computer of the control unit 2, and may be provided separately from the computer when it is a hard disk or the like.

Further, various input instructions for giving an operation to the laser processing apparatus 50 are preferably performed using a GUI (Graphical User Interface) implemented in the controller 1. For example, a menu for processing processing is provided on the GUI in accordance with the action of the processing unit 25.

The laser processing apparatus 50 having the above configuration can selectively perform processing in the above-described continuous processing mode and processing in a discrete processing mode. This is achieved by changing the irradiation conditions of the laser light LB from the laser light source SL and the combination of the scanning conditions of the substrate 10 by the laser light LB generated by moving the stage 7.

The processing mode is preferably selected, for example, in accordance with a processing menu provided in the controller 1 in a manner available in operation in accordance with the action of the processing unit 25. The storage unit 3 of the controller 1 stores processing position data D1 describing the position of the predetermined dividing line L (FIG. 9) of the substrate 10, and storing processing mode setting data D2, which is set in the processing mode. The data D2 describes the conditions of the respective parameters of the laser light or the driving conditions of the stage 7 (or the settable range of the conditions) corresponding to the laser processing aspect in each processing mode. The processing unit 25 acquires the machining position data D1 and acquires conditions corresponding to the selected machining mode from the machining mode setting data D2, and controls the corresponding portions by the drive control unit 21 or the illumination control unit 23 or other components. Acting so that each part performs an action corresponding to the condition.

<Details of etching treatment>

The etching treatment is preferably performed by using hot phosphoric acid heated to, for example, about 200 ° C, a mixed acid of hot phosphoric acid and hot sulfuric acid, or hot-melted potassium hydroxide as an etching solution. The etching time can be appropriately set depending on the size of the substrate 10.

FIG. 12 is an SEM (Scanning Electron Microscope) image of a cross section of the substrate 10 before the etching process along the processed region RE. Fig. 13 is an SEM image of a cross section of the substrate 10 along the processed region RE after the etching treatment. Further, in order to observe the processed region RE, any of the substrates 10 of the two SEM images is formed by being separated from the normal order described below. Further, although the substrate 10 to be imaged and the imaging position of the two SEM images are different, the common point is that either one is on the sapphire substrate 101. The square portion forms the processed region RE. Further, the lower end portion of the processed region RE has a wedge-shaped (or comb-like) concavity and convexity because the scribing process is performed in the discrete processing mode. Further, the substantially central portion of Fig. 13 serves as the intersection of the scribe lines ST, and the processed region RE intersecting the processed region RE constituting the cross-section is observed.

Regarding the substrate 10 before the etching treatment shown in FIG. 12, the work-affected layer TR is closely formed in the processed region RE.

On the other hand, with respect to the substrate 10 after the etching treatment shown in FIG. 13, the work-affected layer TR was not found at all. This means that the work-affected layer TR which is a main cause of the decrease in light-emitting efficiency has been completely removed by the etching treatment. Further, the removal of the work-affected layer TR includes not only the singulation of the work-affected layer TR adhering to the processed region RE but also the dissolution of the amorphous or polycrystalline sapphire constituting the work-affected layer TR by the etchant. The situation.

As a result of the above, it is shown that the processed region RE formed by the scribe processing can be appropriately removed by performing the etching treatment after forming the processed region RE by the dicing processing, thereby exposing the end surface of the sapphire substrate 101. Thereby, in the LED element finally obtained, light from the light-emitting layer is not absorbed by the work-affected layer TR, so that high light-emitting efficiency can be achieved.

Further, in FIG. 13, the unevenness formed by the cleavage surface of the submicron-order periodic fine concavo-convex sapphire substrate 101 which is formed in the wedge-shaped processed region RE formed on the sapphire substrate 101, and the uneven portion itself Optically transparent. The formation of such irregularities in the processed region RE constituting the end portion of the LED wafer is the same as the uneven shape of the processed region RE itself. The reflectance in the end faces of the LED elements is lowered to have an effect of improving the light extraction efficiency. Further, the above cleavage plane itself can also be formed by processing in a continuous processing mode.

12 and FIG. 13 show the substrate 10 after the dicing process by the discrete processing mode. However, the substrate 10 after the dicing process by the continuous processing mode may of course be etched. The work-affected layer TR formed in the processed region RE is appropriately removed.

Further, in the present embodiment, wet etching is performed using an etching solution, and it can be said that such a method is preferably a method in which the etching liquid is spread over a width of only several μm to several tens of μm or The entire processed region RE is deep, and the work-affected layer TR can be completely removed. This effect is remarkable particularly in the case where the processed region RE which is tapered toward the front end portion is formed as in the discrete processing mode.

The method of removing the processed altered layer TR by wet etching may also be performed after forming a processed region (scribe line) having an aspect ratio higher than that of the conventional (depth greater than the width). That is, the method of the present embodiment also contributes to an improvement in the breaking accuracy or a decrease in the width of the scribe line, thereby increasing the number of cuts of the wafer.

Further, in the present embodiment, since the LED chip is not subjected to the etching process as the object of the etching process, the substrate having the LED pattern after the dicing process is used as the etching process, and thus the dicing processing can be performed. All of the formed areas are formed to remove the altered layer at one time. That is, the affected layer can be effectively and surely removed as compared with the case where the affected layer is removed from each wafer.

As described above, according to the present embodiment, the substrate having the LED pattern before the electrode formation is subjected to the dicing process by the laser light, and then the wet etching process is performed to remove the processed modified layer, and thereafter the electrode is formed. Further, by singulating the substrate having the LED pattern, it is possible to obtain the light-emitting efficiency more effectively than the previous LED element efficiently and surely.

<Modification>

In the above-described embodiment, a process of singulating (dividing into individual wafers) a substrate having an LED pattern formed by repeating formation of a plurality of LED patterns on a sapphire substrate (mother substrate) will be described. However, the processing method of the present embodiment can also be actively applied to singulation and division of substrates for other applications.

Further, when a substrate having an LED pattern is used as a base substrate other than the sapphire substrate, an etching liquid corresponding to the substrate may be used in the etching process.

The processing in the discrete processing mode is not limited to the processing shown in the above embodiment. Generally, the larger the irradiation energy E of the irradiated laser pulse is, the more the region in the thickness direction of the substrate 10 is processed, and the processing range on the surface is also enlarged. The modification shown below is a processing method using this point. The processing in the above discrete processing mode is characterized by V/R > D, but the processing shown below can be performed under the condition of V / R ≦ D. In other words, even when the laser light LB is irradiated in a state where the adjacent beam spot has an overlapping portion, the processed region RE having the uneven shape along the scribe line ST can be formed.

Fig. 14 is a view for explaining the discrete processing method of the modification. Fig. 14 schematically shows the relationship between the irradiation energy E and the size of the beam spot BS and the shape of the processed region RE.

In this modification, when the laser beam LB is scanned along the predetermined dividing line L, the processing unit 25 processes the irradiation energy of the laser beam LB between the minimum value _Emin and the maximum value _Emax as shown in FIG. The way of sexual change controls the actions of each department. That is, the laser processing apparatus 50 is controlled to scan the laser light while modulating the irradiation energy. As a result, the size of the beam spot BS of the laser light LB on the surface of the substrate 10 varies depending on the value of the irradiation energy. 14, the beam spot BS (BS2) beam spot BS (BS1) to the time of E = E _min and E = E _max time for the embodiment shown, but may take such an intermediate size of the beam spot. Thereby, the processed region RE of the same shape as that of Fig. 10 is finally formed.

Specifically, E _min and E _max are set so as to satisfy 5 (μJ) ≦ E _min ≦ 100 (μJ) and 20 (μJ) ≦ E _max ≦ 1000 (μJ). Further, the values of R and V are set so as to satisfy the range of 50 (kHz) ≦ R ≦ 200 (kHz) and 50 (mm/sec) ≦ V ≦ 1000 (mm/sec). Further, the modulation period is preferably set to about 2 μm to 20 μm. These setting ranges are described in the machining mode setting data D2.

As can be seen from FIG. 14, the modulated illumination energy E is the final modulation of the substantial beam spot diameter effective for the processing. Therefore, the processing of the modification is equivalent to modulating the illumination range on the surface of the workpiece to illuminate the laser beam LB. The way.

1‧‧‧ controller

4‧‧‧Transparent substrate protection sheet

7‧‧‧ platform

7m‧‧‧mobile agencies

10‧‧‧ (with LED pattern) substrate

50‧‧‧ Laser processing equipment

101‧‧‧Sapphire substrate

102‧‧‧LED pattern

103‧‧‧Protective film

B1‧‧‧Bottom break bar

B2‧‧‧Bottom break bar

B3‧‧‧Upper splitter

BP‧‧‧Disconnected position

BS‧‧‧beam point

L‧‧‧Predetermined dividing line

LB‧‧‧Laser light

RE‧‧‧Processed area

SC‧‧‧

SL‧‧‧Laser light source

ST‧‧‧ cutting road

TR‧‧‧Processing metamorphic layer

1 is a view showing the processing of a substrate 10 having an LED pattern. Slightly sequential diagram.

2 is a schematic cross-sectional view showing the configuration of a substrate 10 having an LED pattern before processing.

3 is a view showing a substrate 10 having an LED pattern in which a protective film 103 is formed.

Fig. 4 is a view schematically showing a state of the scribing process.

Fig. 5 is a view showing a substrate 10 having an LED pattern after the dicing process.

Fig. 6 is a partially enlarged view centering on the broken line A of Fig. 5.

Fig. 7 is a schematic view showing a state in which the substrate 10 having the LED pattern is broken.

8 is a view for explaining the relationship between the repetition frequency of the laser light LB used in the scribing process, the moving speed of the stage on which the LED pattern substrate is placed, and the center distance of the beam spot of the laser light LB.

Fig. 9 is a perspective view schematically showing the relationship between the irradiation pattern of the laser light LB in the discrete processing mode and the formed region RE to be formed.

Fig. 10 is a plan view and a cross-sectional view schematically showing the relationship between the irradiation pattern of the laser light LB in the discrete processing mode and the formed region RE to be formed.

Fig. 11 is a schematic view showing the configuration of a laser processing apparatus 50 which can perform processing in the continuous processing mode and the discrete processing mode.

Fig. 12 is an SEM image of a cross section along the processed region RE of the substrate 10 having the LED pattern before the etching process.

Figure 13 is a view of the edge of the substrate 10 with the LED pattern after the etching process SEM image of the cross section of the processed area RE.

Fig. 14 is a view for explaining the discrete processing method of the modification.

Claims (11)

A method for processing a substrate having an LED pattern, characterized in that it is a method of processing a substrate having an LED pattern in which a plurality of LED unit patterns are repeatedly arranged on a base substrate, and the processing method includes a scribing step of illuminating the substrate having the LED pattern along a predetermined dividing line to form a grid on the substrate having the LED pattern; and an etching step by performing the scribing step The substrate having the LED pattern is immersed in the etching solution to remove the processed altered layer; and the breaking step is performed by singulating the substrate with the LED pattern passing through the etching step along the scribe line; Performing the above-described scribing step after the protective film forming step, the protective film forming step is to form a protective film on the pattern forming surface of the substrate having the LED pattern; and performing the above-described protective film removing step of removing the protective film a step of separating; further comprising an electrode forming step on the substrate with the LED pattern passing through the protective film removing step to form a plurality of LEDs Each of the opposing electrode should be of a pattern; to the breaking step, the substrate formed with the pattern of the electrodes of the LED breaking. The method for processing a substrate having an LED pattern according to claim 1, wherein the base substrate is a sapphire substrate; The etching solution is any one of hot phosphoric acid, a mixed acid of hot phosphoric acid and hot sulfuric acid, or hot-melted potassium hydroxide. The method for processing a substrate having an LED pattern according to claim 1 or 2, wherein in the scribing step, the processed region is formed by scanning and irradiating pulsed laser light emitted from a specified light source along the predetermined dividing line, The processed region includes a portion continuous in the first direction, and a state of the cross section perpendicular to the first direction changes in the first direction; and the processed region that has passed through the etching step becomes the scribe line. The method for processing a substrate having an LED pattern according to claim 1 or 2, wherein in the scribing step, the laser light emitted from the specified light source is irradiated along the predetermined dividing line, and the LED pattern is formed thereon. Forming the processed region on the surface of the substrate, the processed region including: a first region continuous in the first direction; and a second region including the first region but not in the first direction a continuous portion; the processed region that has passed through the etching step is the scribe line. The method for processing a substrate having an LED pattern according to claim 1 or 2, wherein in the scribing step, the processed region is formed by scanning and irradiating pulsed laser light emitted from a specified light source along the predetermined dividing line, The processed region is formed by connecting a plurality of substantially elliptical tapered or substantially wedge-shaped unit processed regions in the first direction; and the processed region that has passed through the etching step becomes the scribe line. The method for processing a substrate having an LED pattern according to claim 3, wherein the pulse laser light is modulated by scanning the pulsed laser light at a beam spot of each unit pulse of the pulsed laser light in a direction separated by the first direction The range of illumination on the surface of the substrate with the LED pattern. The method for processing a substrate having an LED pattern according to claim 6, wherein the irradiation range on the surface of the substrate with the LED pattern is modulated by scanning the pulsed laser light in the first direction under the following irradiation conditions The irradiation condition is such that when the repetition frequency of the pulsed laser light is R (kHz), the relative movement speed of the pulsed laser light with respect to the substrate having the LED pattern is set to V (mm/sec), and When the predetermined formation width in the direction orthogonal to the first direction of the processed region on the surface of the substrate having the LED pattern is W (μm), 10 (kHz) ≦ R ≦ 200 (kHz) and 30 ( Mm/sec) ≦V≦1000 (mm/sec), indicating that the V/R of the center interval of the beam point of the above-mentioned pulsed laser light satisfies V/R≧1 (μm) and W/4 (μm) ≦V/R≦ The relationship of W/2 (μm). The method for processing a substrate having an LED pattern according to claim 4, wherein the pulsed laser light is scanned by irradiating the beam spot of each unit pulse of the pulsed laser light in the first direction. The illumination range on the surface of the substrate with the LED pattern described above is modulated. The method for processing a substrate having an LED pattern according to claim 8, wherein the irradiation range on the surface of the substrate with the LED pattern is modulated by scanning the pulsed laser light in the first direction under the following irradiation conditions The irradiation condition is such that when the repetition frequency of the pulsed laser light is R (kHz), the relative movement speed of the pulsed laser light with respect to the substrate having the LED pattern is set to V (mm/sec), and When the predetermined formation width in the direction orthogonal to the first direction of the processed region on the surface of the substrate having the LED pattern is W (μm), 10 (kHz) ≦ R ≦ 200 (kHz) and 30 ( Mm/sec) ≦V≦1000 (mm/sec), indicating that the V/R of the center interval of the beam point of the above-mentioned pulsed laser light satisfies V/R≧1 (μm) and W/4 (μm) ≦V/R≦ The relationship of W/2 (μm). The method for processing a substrate having an LED pattern according to claim 5, wherein the pulse laser light is modulated by scanning the pulsed laser light at a beam spot of each unit pulse of the pulsed laser light along the first direction. The range of illumination on the surface of the substrate with the LED pattern. A method of processing a substrate having an LED pattern according to claim 10, wherein said pulsed laser light is applied along said first one under the following irradiation conditions Scanning the direction to modulate the illumination range on the surface of the substrate with the LED pattern, wherein the irradiation condition is: when the repetition frequency of the pulsed laser light is R (kHz), the pulsed laser light is relative to the above The relative movement speed of the substrate of the LED pattern is V (mm/sec), and the predetermined formation width in the direction orthogonal to the first direction on the surface of the substrate having the LED pattern is set to W. (μm), 10 (kHz) ≦ R ≦ 200 (kHz) and 30 (mm / sec) ≦ V ≦ 1000 (mm / sec), indicating that the V/R of the center interval of the beam point of the above-mentioned pulsed laser light satisfies v /R≧1 (μm) and W/4 (μm) ≦ V / R ≦ W / 2 (μm).