KR101312427B1 - Laser processing apparatus, method of processing products to be processed, and method of dividing products to be processed - Google Patents

Abstract

(Problem) Provided is a laser processing apparatus in which formation of a processing trace is suppressed and formation of a division starting point where division of a workpiece can be realized more reliably is realized.
(Solution means) The laser processing apparatus including a light source for emitting a pulsed laser light and a stage on which the workpiece is placed further includes a cooling mechanism for cooling the mounting surface of the workpiece placed on the stage. In order to place the workpiece and cool the mounting surface by the cooling mechanism, the stage so that the irradiated area for each unit pulsed light of the pulse laser light is formed discretely on the workpiece surface facing the mounting surface. By irradiating the workpiece with pulsed laser light while moving, the cleavage or fissure of the workpiece is sequentially generated between the irradiated regions, thereby forming a starting point for dividing the workpiece.

Description

LASER PROCESSING APPARATUS, METHOD OF PROCESSING PRODUCTS TO BE PROCESSED, AND METHOD OF DIVIDING PRODUCTS TO BE PROCESSED}

TECHNICAL FIELD This invention relates to the laser processing method which irradiates a laser beam, and processes a to-be-processed object, and the laser processing apparatus used for this.

Various techniques are already known as a technique for processing a workpiece by irradiating pulsed laser light (hereinafter, also referred to simply as laser processing or laser processing technology) (see, for example, Patent Documents 1 to 4).

Patent Document 1 discloses that when dividing a die, which is a workpiece, a groove having a V-shaped cross section (break groove) is formed along a division scheduled line by laser ablation, and this groove is formed. It is a method of dividing a die starting at. On the other hand, what is disclosed in patent document 2 is a substantially V-shaped cross section in which the laser beam of a defocused state was irradiated along the dividing line of a to-be-processed object (divided body) in the crystallized state rather than the surroundings to an irradiation area | region. This is a method of generating a modified reformed region (modified region), and dividing the workpiece from the lowest point of the fused modified region.

In the case where the dividing origin is formed using the techniques disclosed in Patent Literature 1 and Patent Literature 2, since subsequent dividing is performed satisfactorily, a uniform shape is formed along the dividing scheduled line direction, which is the scanning direction of the laser beam. It is important to form a V-shaped cross section (groove cross section or altered region cross section). As a countermeasure therefor, for example, irradiation of the laser beam is controlled so that the irradiated area (beam spot) of the laser beam per pulse is overlapped back and forth.

For example, when the repetition frequency (unit kHz), which is the most basic parameter of laser processing, is set to R, and the scanning speed (unit mm / sec) is set to V, the ratio V / R of both is a beam spot. In the technique disclosed in Patent Literature 1 and Patent Literature 2, the laser beam is irradiated and scanned on the condition that V / R is 1 µm or less so that beam spots overlap with each other.

In addition, Patent Literature 3 discloses an embodiment in which a modified region is formed inside a substrate by irradiating a laser beam with a focusing point inside the substrate having a laminated portion on its surface, and the modified region is a starting point for cutting.

Further, Patent Document 4 repeats a plurality of laser beam scans for one separation line, and forms grooves and reforming portions that are continuous in the separation line direction, and internally modified portions that are not continuous in the separation line direction, above and below the depth direction. Is disclosed.

On the other hand, Patent Document 5 describes a processing technique using a laser beam of ultra-short pulses whose pulse width is psec order, by adjusting the condensed spot position of the pulsed laser light to reach the surface from the surface layer portion of the workpiece (plate). Embodiments are disclosed in which microcracks form microscopic dissolution traces and form a linear separation ease region in which these dissolution traces are connected.

Japanese Laid-Open Patent Publication No. 2004-9139 International Publication No. 2006/062017 Japanese Laid-Open Patent Publication No. 2007-83309 Japanese Laid-Open Patent Publication No. 2008-98465 Japanese Laid-Open Patent Publication 2005-271563

The method of forming a division origin by a laser beam and then performing division | dividing by a breaker is automatic, high speed, stability, and high precision compared with the diamond scribing which is a mechanical cutting method conventionally performed. It is advantageous in terms of conductivity.

However, when formation of the division origin by a laser beam was performed by the conventional method, it was inevitable that what was called a process trace (laser process trace) was formed in the part to which the laser beam was irradiated. A processing trace is a deterioration area | region in which the material and a structure changed with the before irradiation as a result of the laser beam irradiation. The formation of the processing trace usually adversely affects the characteristics of each of the divided workpieces (divided fragments) and the like, and therefore is preferably suppressed as much as possible.

For example, the conventional laser processing of the to-be-processed object which formed the light emitting element structure, such as LED structure, on the board | substrate which consists of hard brittle and optically transparent materials, such as sapphire, is disclosed by patent document 2, In the edge portion of the light emitting element obtained by dividing by chip into units (parts irradiated with laser light at the time of dividing), processing traces of several micrometers in width and several micrometers to several tens of micrometers in depth are formed continuously. . Such processing traces have a problem of absorbing the light generated inside the light emitting element and reducing the light extraction efficiency from the element. In particular, this problem is remarkable in the case of a light emitting device structure using a sapphire substrate having a high refractive index.

The inventors of the present invention have intensively studied and, by using laser cleavage or thermal cleavage of the workpiece, in order to form a division point by irradiating a laser beam to the workpiece, The recognition that the formation of processing traces is suppressed very suitably. In addition, the recognition that it is very suitable to use the laser beam of an ultra short pulse for such a process was acquired.

In Patent Literatures 1 to 5, no disclosure or suggestion has been made regarding the embodiment of formation of the divided starting point using cleavage or thermal cleavage of the workpiece.

In addition, on the other hand, after forming a division origin using a laser beam, in performing the process of dividing a workpiece by a chip unit, the tip part of a division origin reaches as deep as possible to a workpiece, It is preferable to have one because the certainty of division becomes high. The same applies to the case of using the ultra short pulsed laser light.

This invention is made | formed in view of the said subject, The formation method of the to-be-divided body which can suppress formation of a process trace and can form the division origin which implements division | segmentation of a workpiece more reliably, and the laser processing used for this are It is an object to provide a device.

In order to solve the said subject, invention of Claim 1 is a laser processing apparatus provided with the light source which emits a pulse laser beam, and the stage on which the to-be-processed object which formed the light emitting element structure is mounted, The said to-be-processed object put on the said stage In the state which further equipped with the cooling mechanism for cooling the whole mounting surface of the said mounting surface, the said to-be-processed object was mounted on the said stage, and the said mounting surface was cooled by the said cooling mechanism, Irradiating the surface of the workpiece with the pulsed laser light while moving the stage so that the irradiated area for each unit pulse light of the pulsed laser light is discretely formed in the workpiece surface opposite to the mounting surface; In the irradiated area for each unit pulsed light, a direct deteriorated area extending from the surface portion in the depth direction is formed. By sequentially generating cleavage or decay of the workpiece between the irradiated regions, a starting point for dividing the workpiece is formed, and the respective unit pulsed light is irradiated to the irradiated region. The cleavage or the cleavage may be generated between the irradiated position of the unit pulsed light irradiated immediately or simultaneously by the impact or stress at the time.

The invention of claim 2 is the laser processing apparatus according to claim 1, wherein the pulse laser light is ultrashort pulsed light having a pulse width of psec order.

The invention according to claim 3 is the laser processing device according to claim 1 or 2, wherein at least at the time of irradiation of the pulsed laser light to the workpiece, the cooling mechanism is disposed below the stage, and the cooling mechanism is The mounting surface is cooled by cooling the stage from below.

The invention according to claim 4 is the laser processing apparatus according to claim 3, wherein the cooling mechanism includes a Peltier element, and at least at the time of irradiation of the pulsed laser beam to the workpiece, the Peltier element is disposed close to the stage. The mounting surface is cooled by cooling the stage by the Peltier element in a state.

According to a fifth aspect of the present invention, there is provided a laser processing apparatus according to claim 3, wherein a recess is formed below the stage, and the cooling mechanism is arranged to be close to the stage at the recess.

According to a sixth aspect of the present invention, there is provided the laser processing apparatus according to claim 1 or 2, wherein at least two irradiated regions formed by different unit pulse light are formed when the starting point for the division is formed in the workpiece. It is characterized in that the cleavage or cleavage of the workpiece is formed to be adjacent to each other in an easy direction.

According to a seventh aspect of the present invention, in the laser processing apparatus of claim 6, the formation of the at least two irradiated regions is alternately performed in a direction in which two different cleavages or dehisces of the workpiece are easy. .

Invention of Claim 8 is a laser processing apparatus of Claim 6, Comprising: All the said irradiated area | region is formed along the direction in which cleavage or cleavage of the said workpiece | work is easy.

According to a ninth aspect of the present invention, in the laser processing apparatus according to claim 1 or 2, when the starting point for the division is formed in the workpiece, the two irradiated regions or the two different cleavages of the workpiece are easily formed. It is characterized by forming in the direction equivalent to one direction.

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According to the eleventh aspect of the present invention, there is provided a processing method for forming a divided starting point in a workpiece having a light emitting element structure, the placing step of placing a workpiece on a stage, and the workpiece for the stage of the workpiece. In the state where the entire tooth surface is cooled, the pulsed laser light is irradiated onto the surface of the workpiece so that the irradiated area for each unit pulse light is formed discretely on the workpiece surface facing the placement surface, and the By forming a direct deterioration region extending from the surface portion in the depth direction in the irradiated region for each unit pulsed light, the cleavage or ten pieces of the workpiece are sequentially generated between the irradiated regions. An irradiation step of forming a starting point for dividing into the workpiece, and in the irradiation step, the individual units Seugwang is characterized in that provided between the shock or stress or immediately before by the said unit at the same time, irradiation of light pulses irradiated position when irradiated to the irradiated area to generate the cleavage or the dehiscence.

According to a twelfth aspect of the present invention, there is provided the processing method according to claim 11, wherein the pulse laser light is ultrashort pulsed light having a pulse width of psec order.

Invention of Claim 13 is a processing method of Claim 11 or 12 WHEREIN: In the said irradiation process, the said mounting surface is arrange | positioned by arrange | positioning the said cooling mechanism below the said stage, and cooling the said stage from below by the said cooling mechanism. It characterized in that the cooling.

The invention according to claim 14 is the processing method according to claim 13, wherein the cooling mechanism comprises a Peltier element, and in the irradiation step, the stage is formed by the Peltier element in a state in which the Peltier element is disposed close to the stage. By cooling, the said mounting surface is cooled.

The invention according to claim 15 is the machining method according to claim 11 or 12, wherein at least two irradiated areas formed by the different unit pulsed light are adjacent to each other in a direction where cleavage or cleavage of the workpiece is easy. It is characterized by forming.

According to a sixteenth aspect of the present invention, there is provided a processing method according to claim 15, wherein the formation of the at least two irradiated regions is alternately performed in a direction in which two different cleavages or dehisces of the workpiece are easy.

According to a seventeenth aspect of the present invention, there is provided the processing method according to claim 16, wherein all the irradiated regions are formed along a direction in which cleavage or cleavage of the workpiece is easy.

Invention of Claim 18 is a processing method of Claim 11 or 12, Comprising: The said irradiated area | region is formed in the direction equivalent to the direction in which two different cleavage or dehission of the said workpiece is easy. .

According to a nineteenth aspect of the present invention, there is provided the processing method according to claim 11 or 12, wherein the emission direction of the pulsed laser beam is periodically moved within a plane perpendicular to the relative movement direction while relatively moving the emission source of the pulsed laser beam and the workpiece. The plurality of irradiated areas satisfying the arrangement relationship of the zigzag shape is formed in the workpiece by changing to.

The invention according to claim 20 is a processing method according to claim 11 or 12, wherein the irradiation timing of the unit pulse light from each of the plurality of emission sources is adjusted while relatively moving the plurality of emission sources of the pulsed laser light and the workpiece. By periodically changing, a plurality of said irradiated area | region which satisfy | fills the arrangement relationship of a zigzag shape is formed in the said to-be-processed object, It is characterized by the above-mentioned.

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According to a twenty-second aspect of the present invention, there is provided a method of dividing a workpiece having a light emitting element structure, the placing step of placing a workpiece on a stage, and the pulsed laser beam in a state in which the entire mounting surface of the workpiece is cooled. The light is irradiated onto the surface of the workpiece so that the irradiated area for each unit pulsed light is formed discretely on the workpiece surface facing the placing surface, and the irradiated area for each unit pulsed light By forming a direct deterioration region extending from the surface portion in the depth direction to the surface, the cleavage or dehiscence of the workpiece is sequentially generated between the irradiated regions, thereby forming a starting point for dividing the workpiece. A process of dividing the workpiece formed by the irradiation step and the division starting point by the irradiation step along the division origin In the irradiation step, in the irradiation step, between the irradiation position of the unit pulse light irradiated immediately before or simultaneously by the impact or stress when the individual unit pulse light is irradiated to the irradiation area. And generating the cleavage or the cleavage.

According to the invention of Claims 1 to 22, the formation of processing traces due to the deterioration of the workpiece, the scattering of the workpiece, etc. are localized, and the cleavage or dehiscence of the workpiece is actively generated. At a much higher speed, the division origin can be formed for the workpiece. In addition, by cooling the mounting surface of the workpiece, the energy of the pulsed laser light can be more effectively contributed to the formation of the division starting point, so that the tip portion of the division starting point can be reached deeper.

In particular, according to the inventions of claims 7, 9, 16, and 18 to 20, cleavage adjacent to each other in the vicinity of the surface of the workpiece as a divided cross section when the workpiece is divided along the division origin formed; Dividing origin can be formed so that unevenness | corrugation by dehisced surfaces may be formed. In the case where the workpiece is formed of a light emitting element structure such as an LED structure on a substrate made of a hard brittle and optically transparent material such as sapphire, the uneven shape is formed on a divided cross section of the substrate, thereby The luminous efficiency can be improved.

1 is a diagram for explaining processing by a first processing pattern.
FIG. 2 is an optical microscope image of the surface of the workpiece | part of which the division origin was formed by cleavage / knitting in a 1st process pattern.
3 is an SEM image from the surface (plane c) to the cross section after the sapphire C-plane substrate having the divided starting point formed by the processing according to the first processing pattern is divided along the divided starting point.
4 is a diagram schematically illustrating a machining embodiment according to the second machining pattern.
FIG. 5 is an optical microscope image of the surface of the workpiece in which split origin is formed by cleavage / decoupling in the second machining pattern.
6 is an SEM image from the surface (plane c) to the cross section after the sapphire c-plane substrate having the divided starting point formed by processing according to the second processing pattern is divided along the divided starting point.
It is a figure which shows typically the process embodiment by a 3rd process pattern.
It is a figure which shows the relationship between the process planned line in a 3rd process pattern, and the planned position of formation of an irradiated area | region.
9 is a schematic diagram schematically showing the configuration of a laser processing apparatus 50 according to an embodiment of the present invention.
10 is a schematic diagram illustrating the configuration of the optical system 5.
FIG. 11: is a figure which shows typically the structure of the optical path setting means 5c.
12 is a diagram illustrating a configuration and an arrangement position of the cooling mechanism 60.

(Mode for carrying out the invention)

<Principle of processing>

First, the principle of the process implemented in embodiment of this invention shown below is demonstrated. Roughly speaking, the processing performed in the present invention is irradiated to the upper surface (working surface) of the workpiece while scanning the pulsed laser light (hereinafter also referred to simply as laser light), so that the irradiated areas for each pulse are separated from each other. By sequentially generating cleavage or cleavage of the workpiece, the starting point (division starting point) for dividing is formed as a continuous surface of cleavage surface or cleavage surface formed between each of the irradiated areas.

In addition, in this embodiment, a dehisce refers to the phenomenon which the to-be-processed object splits regularly along crystal planes other than a cleaved surface, and is called the cleaved surface. In addition to cracks and fissures that are microscopic phenomena along the crystal plane, cracks that are macroscopic cracks may occur along a nearly constant crystal orientation. Depending on the substance, only one of the cleavage, fissures, or cracks may occur, but in the following, the cleavage, fissures, and cracks are generally referred to as cleavages / coales without distinguishing the fissures in order to avoid confusion. In addition, the process of embodiment mentioned above may also be called simply a cleavage / coupling process.

In the following, the workpiece is a hexagonal single crystal material, and the axial directions of the a1 axis, the a2 axis, and the a3 axis are directions in which cleavage and dehiscing are easy. For example, c-plane sapphire substrate and the like. The hexagonal a1 axis, the a2 axis, and the a3 axis are symmetrical with each other at an angle of 120 ° in the c plane. In the process of this invention, there exist some patterns according to the relationship between the direction of these axes, and the direction (processing direction) of a process plan line. Hereinafter, these are demonstrated. In the following description, the laser light irradiated for each individual pulse is referred to as a unit pulse light.

<The first processing pattern>

The first processing pattern is an embodiment of cleavage / coiling processing in which the processing schedule line is parallel to any one of the a1 axis direction, the a2 axis direction, and the a3 axis direction. More generally speaking, it is the embodiment of processing in the case where the direction in which cleavage / decomposition is easy coincides with the direction of the machining schedule line.

FIG. 1: is a figure which shows typically the process embodiment by a 1st process pattern. In FIG. 1, the case where a1-axis direction and the process plan line L are parallel is illustrated. FIG.1 (a) is a figure which shows the azimuth relationship of the a1 axis direction, a2 axis direction, a3 axis direction in this case, and the process plan line L. In FIG. FIG.1 (b) has shown the state in which the unit pulse light of the 1st pulse of a laser beam was irradiated to the irradiated area RE1 of the edge part of the process plan line L. In FIG.

In general, since irradiation of unit pulse light imparts high energy to the ultra-small area of the workpiece, such irradiation is equivalent to the area of irradiation of the unit pulse light (laser light) or wider than the area to be irradiated on the irradiated surface. In the range, deterioration, melting and evaporation of substances are caused.

By the way, when the irradiation time of the unit pulse light, that is, the pulse width is set very short, the substance existing in the substantially center region of the irradiated area RE1, which is narrower than the spot size of the laser light, obtains the kinetic energy from the irradiated laser light. While scattered or deteriorated in a direction perpendicular to the slope, impacts or stresses generated by irradiation of unit pulsed light, including reaction forces generated by such scattering, are affected by the periphery of the irradiated area, in particular, cleavage. It acts in the a1-axis direction, the a2-axis direction, and the a3-axis direction which are easy directions of dehission. Accordingly, along the direction, a small cleavage or dehiscence partially occurs while maintaining a contact state, or a state in which thermal distortion is inherent even though the cleavage or dehiscence does not reach. In other words, it can also be said that irradiation of the unit pulse light of the ultrashort pulse acts as a driving force for forming a substantially straight weak strength portion when viewed from the upper surface facing the cleavage / detachability easily direction.

In FIG.1 (b), the weak strength part in + a1 direction matching with the extension direction of the process plan line L among the weak strength parts formed in the direction which each said cleavage / dehiscing is easy. (W1) is shown typically by a broken arrow.

Subsequently, as shown in Fig. 1 (c), the unit pulsed light of the second pulse of the laser light is irradiated, and the irradiated area is located at a position separated from the irradiated area RE1 by a predetermined distance on the processing target line L. When RE2 is formed, similarly to the first pulse, the weak strength portion along the direction in which cleavage / opening is easy also is formed in the second pulse. For example, the weak strength portion W2a is formed in the -a1 direction, and the weak strength portion W2b is formed in the + a1 direction.

However, at this point in time, the weak strength portion W1 formed by the irradiation of the unit pulse light of the first pulse exists in the extending direction of the weak strength portion W2a. That is, the extending direction of the weak strength portion W2a is a location where cleavage or cleavage can occur with less energy than other locations. Therefore, in reality, when the second pulse of unit pulsed light is irradiated, the impact or stress generated at that time is propagated in the direction in which cleavage / opening is easy and the weak strength portion existing in front of it, and the weak strength portion W2a. ), Complete cleavage or cleavage occurs almost at the moment of irradiation over the weak strength portion W1. Thereby, the cleavage / cleavage surface C1 shown in FIG.1 (d) is formed. In addition, the cleavage / opening surface C1 may be formed to a depth of several micrometers to several tens of micrometers in the vertical direction when viewed in the drawings of the workpiece. In addition, as will be described later, on the cleavage / dehistory surface C1, sliding of the crystal surface occurs as a result of being subjected to a strong impact or stress, and undulation occurs in the depth direction.

Then, as shown in Fig. 1 (e), the unit pulsed light is sequentially sequentially irradiated to the irradiated areas RE1, RE2, RE3, and RE4 ... by scanning the laser light along the processing schedule line L thereafter. When irradiated with, cleavage / dehiscence surfaces C2 and C3 ... are formed sequentially. In this embodiment, it is the cleavage / cleavage process in a 1st process pattern which continuously forms a cleavage / cleavage surface.

That is, in a 1st process pattern, the some to-be-irradiated area which exists discretely along the process plan line L, and the cleavage / dehiscence surface formed between these some to-be-irradiated area as a whole are to-be-processed objects It becomes a division origin at the time of dividing along the process schedule line L. As shown to FIG. After formation of such a starting point of division | segmentation, a to-be-processed object can be divided | segmented into embodiment generally followed by the process schedule line L by performing division | segmentation using a predetermined jig | tool and apparatus.

In addition, in order to realize such cleavage / decay processing, it is necessary to irradiate a short pulse laser light. Specifically, it is necessary to use a laser beam having a pulse width of 100 psec or less. For example, it is very suitable to use a laser beam having a pulse width of about 1 psec to 50 psec.

On the other hand, the irradiation pitch of the unit pulsed light (center interval of the irradiated spot) may be determined in the range of 4 µm to 50 µm. If the irradiation pitch is larger than this, the formation of the weak strength portion in the direction in which cleavage / decay is easy does not proceed to the extent that the cleavage / decay surface can be formed. It is unpreferable from a viewpoint of forming the division origin which consists of faces surely. In terms of scanning speed, processing efficiency, and product quality, the larger the irradiation pitch is, the more preferable it is. It is more suitable that it is about 15 micrometers.

Now, when the repetition frequency of the laser light is R (kHz), unit pulsed light is emitted from the laser light source every 1 / R (msec). When the laser beam is moved at a speed V (mm / sec) relative to the workpiece, the irradiation pitch Δ (μm) is determined as Δ = V / R. Therefore, the scanning speed V and the repetition frequency of the laser beam are determined so that Δ becomes about several μm. For example, the scanning speed V is about 50 mm / sec-3000 mm / sec, and it is very suitable that the repetition frequency R is 1 kHz-200 kHz, especially about 10 kHz-200 kHz. Specific values of V and R may be appropriately determined in consideration of the material, water absorption rate, thermal conductivity, melting point, and the like of the workpiece.

It is preferable that a laser beam is irradiated with the beam diameter of about 1 micrometer-about 10 micrometers. In this case, the peak power density in the irradiation of the laser beam is approximately 0.1 TW / cm 2 to several 10 TW / cm 2.

The irradiation energy (pulse energy) of the laser light may be appropriately determined within the range of 0.1 μJ to 50 μJ.

FIG. 2 is an optical microscope image of the surface of the workpiece | part of which the division origin was formed by cleavage / knitting in a 1st process pattern. Specifically, a process in which a sapphire c-plane substrate is used as a work piece and discretely forms irradiated spots on the c-plane at intervals of 7 μm with the a1 axis direction as the extending direction of the processing schedule line L. The result of performing is shown. The result shown in FIG. 2 suggests that the actual to-be-processed object is processed by the mechanism mentioned above.

3 is a SEM (scanning electron microscope) from the surface (plane c) to the cross section after the sapphire c-plane substrate having the divided starting point formed by the processing according to the first processing pattern is divided along the divided starting point. It is a prize. In addition, in FIG. 3, the boundary part of a surface and a cross section is shown with the broken line.

An elongated triangular or needle-shaped region having a longitudinal direction inside the surface of the workpiece, which is present at approximately equal intervals in the range of about 10 μm from the surface, observed in FIG. 3, is used for irradiation of unit pulsed light. This is a region (hereinafter referred to as a direct alteration region) in which a phenomenon such as alteration or scattering removal occurs directly. And, the region observed as the stripe-shaped part which has a longitudinal direction in the left-right direction in the figure which exists between those direct alteration areas are connected in the up-down direction when it sees in the figure by submicron pitch is cleaved, It is ten sides. The division surface formed by division | segmentation below these direct deterioration area | regions and a cleavage / opening surface is divided.

Since the area | region in which the cleavage / dehiscence surface was formed is not the area | region which was irradiated with the laser beam, in the process according to this 1st process pattern, only the direct alteration area | region formed discretely is a process trace. In addition, the size at the surface to be processed of the directly deteriorated region is only a few hundred nm to about 1 μm. That is, by performing a process in a 1st process pattern, formation of the division origin in which formation of a process trace was suppressed much more suitably compared with the past is realized.

In addition, what is observed as a stripe-shaped part in SEM image is the micro unevenness | corrugation which has the height difference of about 0.1 micrometer-about 1 micrometer actually formed in a cleavage / cove surface. Such unevenness is formed when a strong impact or stress acts on the workpiece by irradiating unit pulsed light when cleaving / deglaring the hard brittle inorganic compound such as sapphire, thereby causing slippage on a specific crystal surface. .

Although such fine unevenness exists, from FIG. 3, since it is judged that the surface and a cross section are orthogonal orthogonally crossing the broken line part, as long as fine unevenness | corrugation is permissible as a processing error, by a 1st processing pattern It can also be said that the workpiece can be divided substantially vertically with respect to the surface by forming a division origin and dividing the workpiece along the division origin.

In addition, as described later, it is sometimes desirable to actively form such fine irregularities. For example, the effect of the improvement of the light extraction efficiency acquired remarkably by the process by the 2nd process pattern described below can be brought to some extent also by the process by a 1st process pattern.

<Second processing pattern>

The second processing pattern is an embodiment of cleavage / coiling processing in which the processing schedule line is perpendicular to any one of the a1 axis direction, the a2 axis direction, and the a3 axis direction. In addition, the conditions of the laser beam used in a 2nd process pattern are the same as that of a 1st process pattern. More generally, it is a processing embodiment in the case where the direction (direction which becomes the axis of symmetry of the direction in which two cleavage / cleavage is easy) equivalent to the direction in which two different cleavage / cleavage becomes easy becomes a direction of a process plan line.

It is a figure which shows typically the process embodiment by a 2nd process pattern. In FIG. 4, the case where a1 axis direction and a process plan line L orthogonally cross is illustrated. FIG.4 (a) is a figure which shows the azimuth relationship of the a1 axis direction, a2 axis direction, a3 axis direction in this case, and the process plan line L. In FIG. FIG.4 (b) has shown the state which the unit pulse light of the 1st pulse of a laser beam irradiated to the irradiated area | region RE11 of the edge part of the process plan line L. In FIG.

Also in the case of a 2nd process pattern, a weak intensity part is formed similarly to a 1st process pattern by irradiating the unit pulse light of an ultrashort pulse. In FIG.4 (b), the weak strength part in the -a2 direction and + a3 direction which are close to the extending | stretching direction of the process plan line L among the weak strength parts formed in the direction which each said cleavage / dehiscing is easy. (W11a, W12a) is shown typically by a broken arrow.

As shown in FIG. 4C, the unit pulsed light of the second pulse of the laser light is irradiated, and the irradiated area is located at a position separated from the irradiated area RE11 by a predetermined distance on the processing line L. FIG. When RE12 is formed, similarly to the first pulse, the weak strength portion along the direction in which cleavage / opening is easy also is formed in the second pulse. For example, the weak strength portion W11b is formed in the -a3 direction, the weak strength portion W12b is formed in the + a2 direction, the weak strength portion W12c is formed in the + a3 direction, and the -a2 direction is formed in the -a2 direction. The weak strength portion W11c is formed.

Also in this case, similarly to the case of the first processing pattern, the weak strength portions W11a and W12a formed by the irradiation of the unit pulse light of the first pulse exist in the extending direction of the weak strength portions W11b and W12b, respectively. Therefore, in reality, when the second pulse of unit pulsed light is irradiated, the impact or stress generated at that time is propagated in the direction in which cleavage / opening is easy and the weak strength portion existing in front of it. That is, as shown in FIG.4 (d), cleavage / cleavage surface C11a, C11b is formed. Also in this case, the cleavage / opening surfaces C11a and C11b can be formed to a depth of several micrometers to several tens of micrometers in the vertical direction when viewed in the drawings of the workpiece.

Subsequently, as shown in Fig. 4E, the laser beam is scanned along the processing target line L, and the unit pulsed light is sequentially irradiated to the irradiated areas RE11, RE12, RE13, and RE14 ... Due to the impact or stress generated at the time of irradiation, the straight cleavage / opening surfaces C11a and C11b, C12a and C12b, C13a and C13b, C14a and C14b ) Will be formed sequentially.

As a result, a state in which the cleavage / opening surface is located symmetrically with respect to the machining schedule line L is realized. In a 2nd process pattern, the some to-be-irradiated area which exists discretely along the process schedule line L, and the cleavage / cleavage surface which exist in those zigzag shapes as a whole process a workpiece to be processed (L). Is the starting point of division when dividing along

FIG. 5 is an optical microscope image of the surface of the workpiece in which split origin is formed by cleavage / decoupling in the second machining pattern. Specifically, the sapphire C-plane substrate is called a workpiece, and the irradiated spot is discretely spaced at intervals of 7 μm on the C plane with the direction orthogonal to the a1 axis direction as the extending direction of the machining scheduled line L. The result of having performed the process to form is shown. From Fig. 5, even in the actual workpiece, a zigzag cleaved / coated surface is observed in the same manner as shown schematically in Fig. 4E. These results suggest that the actual workpiece is processed by the mechanism mentioned above.

6 is a SEM image from the surface (plane c) to a cross section after dividing the sapphire C surface substrate which formed the division origin by the process according to a 2nd processing pattern along the said division origin. 6, the boundary part of a surface and a cross section is shown with the broken line.

From FIG. 6, in the range around 10 micrometers from the surface of the cross section of the to-be-processed object after a division | segmentation, it exists that the cross section of a to-be-processed object has the unevenness | corrugation corresponding to the zigzag arrangement typically shown in FIG. It is confirmed. It is cleavage / dehiscence which forms such unevenness | corrugation. In addition, the pitch of the unevenness | corrugation in FIG. 6 is about 5 micrometers. In the same manner as in the case of processing with the first processing pattern, the cleavage / opening surface is not flat, and sub-micron pitch unevenness is generated due to slippage on a specific crystal surface due to irradiation of unit pulsed light.

In addition, it is a cross section of a direct alteration region extending from the surface portion in the depth direction corresponding to the position of the convex portion of the unevenness. Compared with the direct deterioration area | region formed by the process by the 1st process pattern shown in FIG. 3, the shape is made nonuniform. And below these direct deterioration area | regions and cleavage / cleavage surface, it is the division surface formed by division.

Also in the case of a 2nd process pattern, it is the same as a 1st process pattern in that only the direct alteration area | region formed discretely became a process trace. And the size in the to-be-processed surface of a deterioration area | region is only about several hundred nm-about 2 micrometers. That is, even when performing the process in a 2nd process pattern, formation of the division origin by which formation of a process trace became more suitable than before is implement | achieved.

In the case of the process by a 2nd process pattern, in addition to the unevenness | corrugation of the submicron pitch formed in a cleavage / corrugation surface, mutually adjacent cleavage / cortication surfaces form the unevenness | corrugation in the pitch of about several micrometers. In an embodiment in which a cross section having such a concave-convex shape is formed, a workpiece formed of a light emitting element structure such as an LED structure on a substrate made of a hard brittle and optically transparent material such as sapphire is divided into chips (divided fragments). It is valid if you do. In the case of the light emitting element, when light generated inside the light emitting element is absorbed at the location of the processing trace formed on the substrate by laser processing, the extraction efficiency of the light from the element is reduced, but the processing by the second processing pattern By intentionally forming irregularities as shown in Fig. 6 in the processing cross section of the substrate, the total reflectance at the position is lowered, and higher light extraction efficiency is realized in the light emitting device. .

<Third processing pattern>

The 3rd processing pattern is the point which uses the laser beam of a very short pulse, and which is planar perpendicular | vertical to any of a1-axis direction, a2-axis direction, and a3-axis direction (it is equivalent to the direction in which two different cleavages / dehisces are easy). Although the direction becomes the direction of a process plan line, it is the same as that of a 2nd process pattern, but embodiment of irradiation of a laser beam differs from a 2nd process pattern.

FIG. 7: is a figure which shows typically the process embodiment by a 3rd process pattern. In FIG. 7, the case where a1 axis direction and a process plan line L orthogonally cross is illustrated. FIG.7 (a) is a figure which shows the azimuth relationship of the a1 axis direction, a2 axis direction, a3 axis direction in this case, and the process plan line L. In FIG.

In the above-mentioned 2nd process pattern, under the same azimuth relationship as shown to FIG. 7 (a), the laser beam is the center direction (a2) of the a2 axis direction and a3 axis direction which are the extending | stretching direction of the process plan line L. Scanning was performed linearly along the axial direction and the a3 axis direction). In the third processing pattern, instead, as shown in FIG. 7B, each irradiated area alternately follows a direction in which two cleavages / dehistorys sandwiching the processing scheduled line L are easily alternated. The unit pulsed light which forms each irradiated area | region is irradiated so that it may be formed in a zigzag shape in embodiment. In the case of FIG. 7, irradiated areas RE21, RE22, RE23, RE24, and RE25 ... are formed along the -a2 direction and the + a3 direction alternately.

Even in the case where the unit pulse light is irradiated in this embodiment, the cleavage / provided surface is formed between the irradiated areas with the irradiation of the unit pulse light in the same manner as in the first and second processing patterns. In the case shown in Fig. 7 (b), the irradiated areas RE21, RE22, RE23, RE24, and RE25 ... are formed in this order, and thus the cleavage / open surface (C21, C22, C23, C24 ...) This is formed sequentially.

As a result, in the third processing pattern, a plurality of irradiated areas which are present discretely in a zigzag arrangement with the machining scheduled line L as an axis, and cleavage / coales formed between each irradiated area. As a whole, a surface becomes a division origin at the time of dividing a to-be-processed object along the process schedule line L. As shown in FIG.

And when dividing | distributing actually along the said division origin, in the range about 10 micrometers from the surface of the cross section of the to-be-processed workpiece after division | segmentation, the unevenness | corrugation of several micrometers pitch by a cleavage / dehiscence surface is carried out. Is formed. In addition, in each cleavage / dehistory surface, similarly to the case of the first and second processing patterns, unevenness of sub-micron pitch accompanying the occurrence of sliding on a specific crystal plane due to irradiation of unit pulse light occurs. In addition, embodiment of formation of a direct alteration region is also the same as that of a 2nd process pattern. That is, also in a 3rd process pattern, formation of a process trace is suppressed to the same extent as a 2nd process pattern.

Therefore, also in the case of the process by such a 3rd process pattern, in addition to the unevenness | corrugation of the submicron pitch formed in the cleavage / cove surface similarly to the process by a 2nd pattern, the pitch of about several micrometers by cleavage / cove surface is mutually Since unevenness | corrugation of is formed, even when the process by a 3rd process pattern is performed for a light emitting element, the obtained light emitting element becomes a more suitable thing from a viewpoint of the improvement of the extraction efficiency of light as mentioned above.

In addition, depending on the type of work piece, the irradiated area RE21 and the irradiated area RE22 of FIG. 7 (b), which are all positions on the projected line L, for generating the cleavage / corrosion more reliably. Middle point, middle point of irradiated area RE22 and irradiated area RE23, middle point of irradiated area RE23 and irradiated area RE24, middle irradiated area RE24 and irradiated area ( The irradiated area may be formed in the middle point of RE25).

By the way, the arrangement | positioning position of the to-be-exposed area | region in 3rd process pattern is along the direction which cleavage / dehiscing is easy in part. As described above, the same applies to the case where the irradiated region is also formed at the midpoint position on the machining schedule line L. FIG. That is, the third processed pattern can be said to be common to the first processed pattern in that at least two irradiated areas are formed adjacent to each other in a direction in which cleavage / opening of the workpiece is easy. Therefore, if the viewpoint is changed, it can also grasp that the 3rd process pattern is processing by the 1st process pattern, changing a direction which scans a laser beam periodically.

In addition, in the case of the 1st and 2nd processing pattern, since the to-be-exposed area is located in a straight line, whenever the emission source of a laser beam moves to a straight line along a process schedule line, and reaches a predetermined formation target position every time, What is necessary is just to irradiate a unit pulse light, and to form a to-be-irradiated area, and such formation embodiment is the most efficient. By the way, in the case of the third processing pattern, since the irradiated area is formed in a zigzag shape rather than in a straight line, the irradiated area can be formed by various methods as well as a method of actually moving the emission source of the laser light in a zigzag shape. have. In addition, in this embodiment, the movement of an attendant means the relative movement between a workpiece and an attendant, and not only a case where a workpiece is fixed and an attendant moves, but an attendant is fixed and a workpiece It also includes an embodiment that moves (actually, the stage on which the workpiece is placed moves).

For example, the zig-zag shape as described above may be changed by periodically changing the emission direction of the laser beam in a plane perpendicular to the processing schedule line while relatively moving the emission source and the stage in parallel with the processing schedule line. It is also possible to form an irradiated area | region in embodiment which satisfy | fills an arrangement relationship.

Alternatively, the irradiated region in the embodiment that satisfies the above-described zigzag arrangement relationship by periodically changing the irradiation timing of the unit pulsed light from the individual emission sources while relatively moving the plurality of emission sources in parallel at the same speed. It is also possible to form

FIG. 8 is a diagram showing a relationship between a machining scheduled line in these two cases and a planned scheduled position of the irradiated area. In any case, as shown in FIG. 8, it is going to finish processing the formation planned position (P21, P22, P23, P24, P25 ...) of irradiation area RE21, RE22, RE23, RE24, RE25 ... Formed alternately on straight lines Lα and Lβ parallel to the line L, formation of the irradiated area at the formation scheduled positions P21, P23, and P25 ... along the straight line Lα, and a straight line It can be understood that the formation of the irradiated area at the formation scheduled positions P22 and P24 along the Lβ is performed in parallel at the same time.

In addition, when the emitter is moved in a zigzag shape, whether the laser beam is relatively scanned by directly moving the source of the laser light or by moving the stage on which the workpiece is placed, the movement of the source or the stage is biaxial. It is a simultaneous operation. On the other hand, the operation | movement which moves only an exit employee or a stage parallel to a process schedule line is a 1-axis operation. Therefore, it can be said that the latter is more suitable in realizing high-speed movement of an emission source, that is, improvement of processing efficiency.

As shown in each of the above-described processing patterns, the cleavage / cutting process performed in the present embodiment imparts a shock or a stress for generating discrete cleavage / coiling mainly for discrete irradiation of unit pulsed light. It is the processing embodiment used as a means. The deterioration of the workpiece (that is, the formation of processing traces), scattering, and the like in the irradiated region are only incidental and occur only locally. The cleavage / dehiring process of this embodiment which has such a characteristic has the mechanism inherent with the conventional processing method which processes by generating deterioration, melting, and evaporation removal continuously or intermittently, overlapping the irradiation area of a unit pulse light. To be different.

In addition, since a strong impact or stress may be instantaneously applied to each irradiated region, it is possible to irradiate a laser beam while scanning at high speed. Specifically, a very high speed scanning, i.e., high speed processing of up to 1000 mm / sec can be realized. Considering that the processing speed in the conventional processing method is at most about 200 mm / sec, the difference is remarkable. Naturally, it can be said that the processing method realized in this embodiment improves productivity significantly compared with the conventional processing method.

In addition, the cleavage / cleavage processing in the present embodiment is particularly performed when the crystal orientation (the orientation in the direction in which cleavage / cleavage is easy) of the workpiece and the processing schedule line are in a predetermined relationship as in the above-described processing patterns. Although it is effective, the application target is not limited to this, and in principle, it is applicable also to the case where both are in arbitrary relationship or the workpiece is a polycrystal. In these cases, since the direction in which cleavage / degeneration occurs with respect to the machining schedule line is not necessarily constant, irregular irregularities may occur at the starting point of division, but the irradiation conditions of the laser beam including the interval of the irradiated area and the pulse width may be appropriately adjusted. By setting, it is possible to perform processing in which such unevenness is not practically a problem which is limited within the allowable range of processing error.

<Outline of Laser Processing Apparatus>

Next, the laser processing apparatus which can implement the process by the above-mentioned various processing patterns is demonstrated.

FIG. 9: is a schematic diagram which shows roughly the structure of the laser processing apparatus 50 which concerns on this embodiment. The laser processing apparatus 50 consists of a laser beam irradiation part 50A, the observation part 50B, transparent members, such as quartz, for example, the stage 7 which mounts the to-be-processed object 10 on it, The controller 1 which mainly controls the various operation | movement (observation operation | movement, alignment operation | movement operation | movement operation, etc.) of the laser processing apparatus 50 is mainly provided. 50 A of laser beam irradiation parts are the site | parts which irradiate a laser beam to the to-be-processed object 10 mounted on the stage 7, equipped with the laser light source SL and the optical system 5, The laser beam emission source mentioned above Corresponds to Observation part 50B is the surface observation which observes the said to-be-processed object 10 directly from the side to which the laser beam is irradiated (it is called a surface or a to-be-processed surface), and the side mounted on the stage 7 (this is the back surface ( It is a site | part which performs backside observation observed through the said stage 7 from the back surface or the mounting surface).

The stage 7 is made to be movable in the horizontal direction between the laser beam irradiation part 50A and the observation part 50B by the moving mechanism 7m. The moving mechanism 7m moves the stage 7 in a predetermined XY 2 -axis direction within a horizontal plane by the action of a driving means (not shown). Thereby, the movement of the laser beam irradiation position in the laser beam irradiation part 50A, the movement of the observation position in the observation part 50B, or the stage 7 between the laser beam irradiation part 50A and the observation part 50B. ), Etc. are realized. Moreover, about 7 m of movement mechanisms, the rotation ((theta rotation) operation in a horizontal plane centering on a predetermined rotation axis can also be performed independently of a horizontal drive.

Moreover, in the laser processing apparatus 50, surface observation and back surface observation can be switched suitably. Thereby, optimal observation according to the material and state of the to-be-processed object 10 can be performed flexibly and quickly.

The stage 7 is formed of a transparent member such as quartz, but a suction pipe (not shown) serving as an intake passage for adsorption-fixing the workpiece 10 is formed therein. The suction pipe is formed, for example, by machining a hole in a predetermined position of the stage 7 by machining.

In the state where the workpiece 10 is placed on the stage 7, the suction pipe 11 is sucked by the suction means 11 such as a suction pump, and the stage 7 material of the suction pipe is sucked. The workpiece 10 (and the fixing sheet 4) is fixed to the stage 7 by applying a negative pressure to the suction hole formed in the tooth surface side tip. In addition, although the case where the to-be-processed object 10 adhere | attaches the fixed sheet 4 is illustrated in FIG. 9, Preferably, the said fixed sheet 4 is attached to the outer edge part of the fixed sheet 4; A fixing ring (not shown) for fixing is arranged.

In addition, although illustration is abbreviate | omitted in FIG. 9, the cooling mechanism 60 (refer FIG. 12) is provided in 50 A of laser beam irradiation parts below the stage 7. As shown in FIG. The laser processing apparatus 50 which concerns on this embodiment is characteristic at the point which comprises such a cooling mechanism 60. FIG. The detail about the cooling mechanism 60 is mentioned later.

<Lighting system and observation system>

Observation part 50B irradiates and falls on the fall illumination light L1 from the fall illumination light source S1 from the upper part of the stage 7 with respect to the to-be-processed object 10 mounted on the stage 7. Surface observation by the surface observation means 6 from the upper side of the stage 7, and the lower side of the stage 7, while irradiating the oblique light transmission illumination light L2 from the illumination light source S2 in an overlapping manner. It is comprised so that backside observation by the backside observation means 16 from the can be performed.

Specifically, the fall illumination light L1 emitted from the fall illumination light source S1 is reflected by the half mirror 9 provided in the lens barrel which does not show in figure, and is irradiated to the to-be-processed object 10. FIG. . In addition, the observation unit 50B includes a CCD camera 6a provided above the half mirror 9 (above the barrel) and a surface observation means 6 including a monitor 6b connected to the CCD camera 6a. It is possible to observe the bright field of view of the workpiece 10 in real time in the state of irradiating the fallen illumination light L1.

In the observation unit 50B, the CCD camera 16a and the CCD camera 16a provided below the stage 7 and more preferably below the half mirror 19 (below the barrel) which will be described later. It is provided with the back | surface observation means 16 containing the monitor 16b connected to it. In addition, the monitor 16b and the monitor 6b provided in the surface observation means 6 may be common.

Moreover, the coaxial illumination light L3 emitted from the coaxial illumination light source S3 provided below the stage 7 is reflected by the half mirror 19 provided in the barrel which abbreviate | omits illustration, and condensing lens 18 ), The workpiece 10 may be irradiated to the workpiece 10 through the stage 7. More preferably, the oblique illumination light source S4 is provided below the stage 7, and the oblique illumination light L4 may be irradiated to the workpiece 10 through the stage 7. . When the coaxial illumination light source S3 or the projection light source S4 has an opaque metal layer or the like on the surface side of the workpiece 10, and the observation from the surface side is difficult because the reflection from the metal layer occurs. Etc., when observing the to-be-processed object 10 from the back surface side, it can utilize suitably.

<Laser light source>

As the laser light source SL, those having a wavelength of 500 nm to 1600 nm are used. In addition, in order to implement | achieve the process in the process pattern mentioned above, the pulse width of the laser beam LB needs to be 1psec-about 50psec. The repetition frequency R is suitably about 10 kHz to 200 kHz, and the irradiation energy (pulse energy) of the laser light is about 0.1 μJ to 50 μJ.

The polarization state of the laser light LB emitted from the laser light source SL may be circularly polarized light or linearly polarized light. However, in the case of linearly polarized light, in view of the bending of the processed cross section in the crystalline workpiece and the energy absorption rate, for example, the angle formed by both is within ± 1 ° so that the polarization direction is substantially parallel to the scanning direction. It is preferable.

<Optical system>

The optical system 5 is a site | part which sets the optical path when a laser beam is irradiated to the to-be-processed object 10. FIG. A laser beam is irradiated to a predetermined irradiation position (position to be formed of a region to be irradiated) of the workpiece along the optical path set by the optical system 5.

10 is a schematic diagram illustrating the configuration of the optical system 5. The optical system 5 mainly includes a beam expander 51 and an objective lens system 52. In the optical system 5, an appropriate number of mirrors 5a may be formed at appropriate positions for the purpose of changing the direction of the optical path of the laser beam LB. In FIG. 10, the case where two mirrors 5a are provided is illustrated.

In addition, when the emitted light is linearly polarized light, it is preferable that the optical system 5 includes an attenuator 5b. The attenuator 5b is arrange | positioned at the suitable position on the optical path of the laser beam LB, and plays the role of adjusting the intensity of the laser beam LB emitted.

In addition, in the optical system 5 illustrated in FIG. 10, the laser light LB emitted from the laser light source SL is formed to be irradiated to the workpiece 10 while the optical path is fixed during the processing. . In addition, a plurality of optical paths of the laser light LB when the laser light LB emitted from the laser light source SL is irradiated to the workpiece 10 are set in actual or virtual manner, and the optical path setting means ( According to 5c) (FIG. 11), the optical path when the individual unit pulsed light of the laser beam LB is irradiated to the to-be-processed object may be comprised so that it can switch sequentially among the set several optical paths. In the latter case, a state where simultaneous parallel scanning is performed at a plurality of locations on the upper surface of the workpiece 10 or a state virtually regarded as such is realized. In other words, it can be said that the optical path of the laser beam LB is multiplexed.

In addition, although FIG. 9 illustrates the case where scanning is performed at three places by three laser beams LB0, LB1, and LB2, embodiments of the multiplexing of the optical path by the optical system 5 are necessarily limited thereto. It doesn't work. The specific structural example of the optical system 5 is mentioned later.

<Controller>

The controller 1 controls the operations of the control unit 2 and the laser processing apparatus 50 for controlling the operations of the above-described parts to realize the processing of the workpiece 10 in various embodiments described later. It further includes a storage unit 3 for storing a program 3p and various data to be referred to at the time of processing.

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

Specifically, the control unit 2 controls driving of various drive parts related to the processing, such as driving the stage 7 by the moving mechanism 7m and focusing operation of the condenser lens 18. The control part 21, the imaging control part 22 which controls the imaging by CCD cameras 6a and 16a, the irradiation of the laser beam LB from the laser light source SL, and the optical path in the optical system 5 Irradiation control part 23 which controls setting embodiment, the suction control part 24 which controls the adsorption | suction fixing operation | movement of the to-be-processed object 10 to the stage 7 by the suction means 11, and given processing position data ( In accordance with D1) (described later) and machining mode setting data D2 (described later), a machining processing unit 25 which mainly performs a machining process to a machining target position is provided.

The storage unit 3 is realized by a storage medium such as a ROM, a RAM, and a hard disk. In addition, the memory | storage part 3 may be embodiment implement | achieved by the component of the computer which implements the control part 2, and even if it is embodiment provided separately from the said computer, such as a hard disk. good.

In the storage unit 3, the machining position data D1 describing the position of the machining target line set for the workpiece 10 is provided from the outside and stored. In the storage unit 3, the conditions for the individual parameters of the laser light, the setting conditions of the optical paths in the optical system 5, the driving conditions of the stage 7 (or their settable ranges), etc. are described for each processing mode. The processing mode setting data D2 is stored in advance.

Moreover, it is preferable that the various input instruction | commands which an operator gives with respect to the laser processing apparatus 50 are performed using the GUI implemented by the controller 1. For example, the menu for a process process is provided to GUI by the action of the process process part 25. FIG. The operator selects a machining mode to be described later, inputs processing conditions, and the like based on such a menu for processing.

<Alignment operation>

In the laser processing apparatus 50, the alignment part which fine-adjusts the arrangement | positioning position of the to-be-processed object 10 can be performed in the observation part 50B before processing. The alignment operation is a process performed to match the XY coordinate axis defined in the workpiece 10 with the coordinate axis of the stage 7. Such alignment processing is important for ensuring that the crystallographic position of the workpiece and the scanning direction of the processing target line and the laser beam satisfy the predetermined relationship required for each processing pattern when processing in the processing pattern described above. .

The alignment operation can be performed by applying a known technique, and may be performed in an appropriate embodiment according to the processing pattern. For example, in a case where a repeating pattern is formed on the surface of the workpiece 10, for example, when a plurality of device chips manufactured by using one mother substrate are cut off, a method such as pattern matching is used. Appropriate alignment operation is realized. In this case, roughly speaking, the CCD camera 6a or 16a acquires the picked-up images of the plurality of alignment marks formed in the workpiece 10, and is processed based on the relative relationship between the picked-up positions of those picked-up images. (25) specifies the alignment amount, and the drive control part 21 moves the stage 7 by the movement mechanism 7m according to the alignment amount, and alignment is implement | achieved.

By performing such an alignment operation, the machining position in a machining process is exactly specified. In addition, after completion of the alignment operation, the stage 7 on which the workpiece 10 is placed is moved to the laser beam irradiation unit 50A, and then the processing by irradiating the laser beam LB is performed. In addition, the movement of the stage 7 from the observation part 50B to the laser beam irradiation part 50A is ensured so that the actual planned position may not shift | deviate from the process planned position assumed at the time of alignment operation.

<Outline of Processing>

Next, the processing process in the laser processing apparatus 50 which concerns on this embodiment is demonstrated. In the laser processing apparatus 50, by combining the irradiation of the laser beam LB emitted from the laser light source SL and passing through the optical system 5 with the movement of the stage 7 on which the workpiece 10 is placed and fixed. The workpiece 10 can be processed while relatively scanning the laser beam passing through the optical system 5 with respect to the workpiece 10.

In the laser processing apparatus 50, the mode (machining mode) of the processing by scanning (relatively) the laser beam LB is characterized in that the basic mode and the multi-mode can be selectively selected. to be. These processing modes are formed according to the embodiment of setting the optical path in the optical system 5 mentioned above.

The basic mode is a mode in which the optical path of the laser light LB emitted from the laser light source SL is fixed. In the basic mode, the laser beam LB always passes one optical path, and moves the stage 7 on which the workpiece 10 is placed at a predetermined speed so that the laser beam scans the workpiece 10 in one direction. Processing in the embodiment is realized. In the case of the optical system 5 illustrated in FIG. 10, only processing in such a basic mode is possible.

The basic mode is suitably used in the case of processing in the above-mentioned first and second processing patterns. That is, with respect to the workpiece | work 10 in which the process plan line L was set in parallel in the direction which cleaved easily or a cleavage, the workpiece | work ( After alignment of 10), the processing in the basic mode can be performed to process the first processing pattern. On the other hand, with respect to the workpiece | work 10 in which the process plan line L was set perpendicularly to the direction which cleaved / opened easily, the workpiece | work ( After alignment of 10), the processing in the basic mode can be performed to process the second processing pattern.

Moreover, in principle, it can apply also to the process in a 3rd process pattern by changing the movement direction of the stage 7 suitably.

On the other hand, the multi-mode is a mode in which a plurality of optical paths are set by multiplying the optical path of the laser light LB substantially or virtually. This is, for example, a plurality of laser beams substantially or virtually along the straight lines Lα and Lβ parallel to the machining schedule line L or the machining schedule line L itself, as shown in FIG. 8. As a result, it is the mode which implements the process similar to the case where the laser beam was scanned in embodiment which intersects the process schedule line L as a result. In addition, virtually scanning a plurality of laser beams is actually a case of irradiating a laser beam with a plurality of optical paths by irradiating the laser beam with a single optical path as in the basic mode but changing the optical path in time. It is said that the same scanning embodiment as is realized.

The multi-mode is suitably used in the case of processing in a 3rd processing pattern. That is, in the same manner as in the case of the second machining pattern, with respect to the workpiece 10 in which the machining schedule line L is set vertically in the direction in which cleavage / decoction is easy, the direction and stage 7 in which cleavage / decay are easy are easy. After alignment of the to-be-processed object 10 so that the moving direction of () is orthogonal, processing in a multi mode can process a 3rd process pattern.

It is very suitable to select the processing mode according to the processing process menu provided to the operator in the controller 1 so that it can be used, for example by the action of the processing process part 25. FIG. The machining processing unit 25 acquires the machining position data D1 and acquires a condition corresponding to the selected machining pattern from the machining mode setting data D2 so that the operation according to the condition is executed. And the irradiation control unit 23 and others to control the operations of the corresponding units.

For example, adjustment of the wavelength and output of the laser light LB emitted from the laser light source SL, the repetition frequency of the pulse, the pulse width, and the like are realized by the irradiation control unit 23 of the controller 1. When the predetermined setting signal according to the processing mode setting data D2 is emitted from the processing processing unit 25 to the irradiation control unit 23, the irradiation control unit 23 irradiates the laser beam LB in response to the setting signal. Set the condition.

Moreover, especially when processing in a multi mode, the irradiation control part 23 makes the timing of switching of the optical path by the optical path setting means 5c synchronized with the emission timing of the unit pulsed light from the laser light source SL. . Thereby, unit pulsed light is irradiated to the optical path corresponding to the said planned formation position among the several optical paths in which the optical path setting means 5c was set with respect to the formation planned position of each to-be-radiated area | region.

Moreover, in the laser processing apparatus 50, it is also possible to irradiate a laser beam LB in the defocused state which deliberately shifted the focusing position from the surface of the to-be-processed object 10 as needed at the time of a processing process. It is. This is realized by adjusting the relative distance between the stage 7 and the optical system 5, for example.

<Configuration example of optical path setting means and its operation>

Next, the concrete structure of the optical path setting means 5c and the example of the operation | movement are demonstrated mainly for operation | movement in a multi mode.

In the following description, in the processing, the processing is performed while moving the stage 7 on which the workpiece 10 is placed along the movement direction D coinciding with the extending direction of the processing schedule line L. Shall be.

In operation in the multi-mode, it is the laser beam LB0 that is irradiated at the time of formation of the irradiated area RE on the machining target line L, and the straight line parallel to the machining schedule line L ( What is irradiated at the time of formation of the to-be-irradiated area RE onto L (alpha) is the laser beam LB1, similarly, the straight line which is parallel to a process line L and symmetrical with respect to a process line L What is irradiated at the time of formation of the to-be-irradiated area | region RE on (L (beta)) is called laser beam LB2.

Further, the processing of the third processing pattern in the multi-mode is realized by having a plurality of irradiated areas formed sequentially or simultaneously located along a direction in which cleavage / detachment is easy.

FIG. 11: is a figure which shows typically the structure of the optical path setting means 5c. The optical path setting means 5c is provided as one component of the optical system 5. The optical path setting means 5c includes a plurality of half mirrors 53, mirrors 54, and an optical path selection mechanism 55.

The half mirror 53 and the mirror 54 branch the optical paths of the laser light LB emitted from the laser light source SL in an in-plane direction perpendicular to the moving direction D of the stage 7 to thereby provide a plurality of optical paths ( And light paths of the laser beams LB0, LB1, LB2). The number of half mirrors 53 is determined according to the number of optical paths. In Fig. 11, two half mirrors 53 are provided to obtain three optical paths. By providing these half mirrors 53 and the mirror 54, the state by which the several laser beams scan the to-be-processed object 10 is realized by moving the stage 7 while emitting the laser beam LB.

The optical path selection mechanism 55 is provided for controlling the emission timing of the laser beam to the workpiece 10 in the plurality of optical paths. More specifically, the optical path selection mechanism 55 is provided with the optical switch SW in the middle of the optical path of each laser beam branched by the half mirror 53 and the mirror 54. The optical switch SW consists of, for example, AOM (acoustic optical modulator), EOM (electro-optic), etc., and passes an incident laser beam in an ON state, and blocks an incident laser beam in an OFF state. Or attenuate (pass) state. As a result, in the optical path selection mechanism 55, only the laser light passing through the optical switch SW in the ON state is irradiated to the workpiece 10.

In the multi-mode operation of the laser processing apparatus 50 including the optical path setting means 5c having such a configuration, the irradiation control unit 23 performs unit pulses of the laser beam LB corresponding to the repetition frequency R. FIG. It is realized by controlling the ON / OFF operation of each optical switch SW such that the optical switch SW on the optical paths of the laser lights LB0, LB1, LB2 is turned ON sequentially and periodically in accordance with the light emission timing. . By this control, only when each laser beam LB0 LB1, LB2 reaches the timing at which the irradiated area is formed, the respective laser beams LB0, LB1, LB2 pass through the optical path selection mechanism 55 and the workpiece ( 10).

That is, a plurality of optical paths of the laser light irradiated to the workpiece 10 are actually formed, and the plurality of laser lights are operated in a multi-mode by simultaneously and simultaneously scanning the plurality of laser lights at different timings of unit pulse light irradiation. This is done.

In operation in the basic mode, for example, only the optical switch SW on any one of the laser beams LB0, LB1, and LB2 is always turned ON to emit the laser beam LB, and the stage ( By moving 7).

<High efficiency of cooling work and cleavage / cutting work>

The above cleavage / corrosion processing is a method of generating cleavage / corrugation in the workpiece by using an impact or stress generated by irradiation of unit pulsed light. Therefore, as the cleavage / corrugation surface is formed with less energy consumption at the time of irradiating the individual unit pulsed light, the cleavage / corrugation occurs to the deeper portion of the workpiece even if the energy applied is the same, The leading end portion of the starting point of division reaches to the portion, whereby the cleavage / opening surface is formed more efficiently.

In view of the above, in the present embodiment, the pulsed laser light is irradiated in a state where the tensile stress is applied to the surface to be processed in advance, so that more efficient cleavage / dehiring processing can be realized. Specifically, by cooling the mounting surface of the workpiece, a temperature difference is generated between the mounting surface and the workpiece surface. When such a temperature difference occurs, in the workpiece, since the side on the mounting surface side is in a more contracted state than the processing surface side, the tensile stress acts on the processing surface side as a result. When the pulsed laser light is irradiated in this state, the energy consumed at the time of forming the cleavage / cleavage surface is reduced as much as the tensile stress acts, and as a result, the cleavage / cleavage surface is easily developed.

Moreover, generally, the fracture toughness value of a solid will become low when temperature falls. And, the lower the fracture toughness value, the easier the cleavage / open surface is formed. Therefore, by cooling the mounting surface in the above-described embodiment, in the workpiece, the fracture toughness value is lower on the mounting surface side, that is, in a state where cleavage / detachment surface tends to develop. Cooling of the mounting surface of a workpiece also contributes to the high efficiency of cleavage / cutting processing.

That is, in the present embodiment, by cooling the mounting surface of the workpiece, two events, namely, the application of tensile stress to the workpiece and the lowering of the fracture toughness value on the placement surface side, are simultaneously generated. Since the cleavage / coiling process is performed, the cleavage / coagulation surface can be formed more efficiently.

<Cooling apparatus>

Next, in the laser processing apparatus 50, the cooling mechanism 60 which charges cooling from the mounting surface side of the above-mentioned to-be-processed object is demonstrated. 12 is a diagram illustrating a configuration and an arrangement position of the cooling mechanism 60. In addition, in FIG. 12, the case where the to-be-processed object 10 consists of the sapphire substrate 101 and the LED structure 102 formed by group III nitride etc. on it is illustrated.

As shown in FIG. 12, the cooling mechanism 60 is formed in the embodiment continuous to the Peltier element 61 which is a cooling member, the support part 62a which supports the Peltier element 61, and the said support part 62a. And a heat dissipation part 62 formed of a fin part 62b having a plurality of fins, and a fan part 63 disposed adjacent to the fin part 62b to blow air to the fin part 62b by driving a fan provided therein. .

The cooling mechanism 60 is the back surface 7b on the opposite side to the upper surface 7a on which the workpiece 10 is placed on the stage 7 when at least the stage 7 is positioned at the laser beam irradiation unit 50A. ), So that the Peltier element 61 is close to each other. In this arrangement state, when electricity is supplied to the Peltier element 61 by an energization means (not shown), heat absorption occurs on the surface 61a. By this endotherm, the mounting surface 10a of the workpiece 10 placed on the stage 7 and on it is cooled. In addition, since the heat generation on the opposite surface cannot be avoided when the Peltier element 61 performs heat absorption on the surface 61a, the cooling mechanism 60 emits heat generated to the outside. The heat dissipation part 62 and the fan part 63 are formed. Such a cooling mechanism 60 is realized by combining a well-known member.

When the laser beam irradiation unit 50A irradiates a pulsed laser beam to perform cleavage / decoupling, by cooling the mounting surface 10a of the workpiece 10 from the stage 7 side with the cooling mechanism 60, The high efficiency of the above-mentioned cleavage / decalation process is realized. In addition, it is preferable that the cooling process by the cooling mechanism 60 is integrally controlled with the processing process by the processing process part 25. FIG.

By the way, what is shown in FIG. 12 is the structure in which the stage 7 has the recessed part 71 in the center part of the back surface 7b on the opposite side to the upper surface 7a on which the to-be-processed object 10 is mounted. And the cooling mechanism 60 is arrange | positioned so that the Peltier element 61 may approach the stage 7 in the said recessed part 71. FIG. That is, the stage 7 is thinner than other portions only in the formation portion of the recessed portion 71. In this case, the mounting surface 10a of the workpiece 10 is more efficiently cooled by the Peltier element 61.

In this case, the stage 7 is viewed from at least one of the stage 7 and the cooling mechanism 60 so as not to interfere with the cooling mechanism 60 when the stage 7 moves to the observation unit 50B. In this case, a moving mechanism in the vertical direction is provided.

Alternatively, the embodiment perpendicular to the drawing may be the moving direction of the stage 7 by the moving mechanism 7m, and the embodiment is formed by the embodiment in which the recess 71 extends in the direction.

<Modifications>

Embodiment which generate | occur | produces a temperature difference between a mounting surface and a to-be-processed surface is not limited to embodiment mentioned above. For example, the same effect can be obtained also by heating the workpiece surface instead of cooling the mounting surface.

1: Controller
2:
3:
4: fixed sheet
5: optical system
5c: light path setting means
7: stage
7m: Moving mechanism
10: Workpiece
10a: mounting face (workpiece)
50: laser processing device
50A: laser light irradiation unit
51: beam expander
52: objective lens system
53: half mirror
5a, 54: mirror
55: optical selection mechanism
60: cooling mechanism
61: Peltier Element
C1 to C3, C11a, C11b, C21 to C24: cleavage / open surface
D: direction of movement
L: Line to be processed
LB, LB0, LB1, LB2: laser light
RE, RE1-RE4, RE11-RE15, RE21-RE25: irradiated area
SL: Laser light source
SW: Optical Switch

Claims (22)

A light source emitting pulsed laser light,
A laser processing apparatus having a stage on which a workpiece formed on a light emitting element structure is placed,
Further provided with a cooling mechanism for cooling the entire mounting surface of the workpiece placed on the stage,
The work surface on which the workpiece is placed on the stage and the irradiated area for each unit pulsed light of the pulsed laser light is opposed to the mounting surface in a state where the mounting surface is cooled by the cooling mechanism. Direct deterioration region which irradiates the surface of the workpiece with the pulsed laser light while moving the stage so as to be discretely formed, and extends from the surface portion to the irradiated region for each unit pulse light in the depth direction By forming a cleavage or cleavage of the workpiece sequentially between the irradiated regions, thereby forming a starting point for dividing the workpiece,
The cleavage or dehiscence is generated between the irradiated areas of the unit pulsed light irradiated immediately or simultaneously by the impact or stress when the individual unit pulsed light is irradiated to the irradiated area. Laser processing device. The method of claim 1,
And said pulsed laser beam is ultra-short pulsed light of pulse width psec order. 3. The method according to claim 1 or 2,
At least at the time of irradiation of the said pulsed laser beam to the said to-be-processed object, the said cooling mechanism is arrange | positioned below the said stage, The said cooling surface cools the said mounting surface by cooling the said stage from below, The laser processing characterized by the above-mentioned. Device. The method of claim 3,
The cooling mechanism comprises a Peltier element,
At least at the time of irradiation of the said pulsed laser beam to the said to-be-processed object, the said mounting surface is cooled by cooling the said stage by the said Peltier element in the state which arrange | positioned the said Peltier element close to the said stage, The laser processing apparatus characterized by the above-mentioned. . The method of claim 3,
A recess is formed below the stage, and the cooling mechanism is arranged to be close to the stage at the recess. 3. The method according to claim 1 or 2,
When forming a starting point for the dividing in the workpiece, forming at least two irradiated areas formed by the different unit pulsed light so as to be adjacent to each other in the direction in which cleavage or decoction of the workpiece is easy. Laser processing device characterized in that. The method according to claim 6,
The formation of the at least two irradiated regions is alternately performed in a direction in which the two different cleavage or cleavage of the workpiece is easily performed. The method according to claim 6,
And all the irradiated regions are formed along a direction in which cleavage or cleavage of the workpiece is easy. 3. The method according to claim 1 or 2,
When forming a starting point for the division of the workpiece, the irradiated region is formed in a direction equivalent to a direction in which two different cleavage or dehission of the workpiece is easy. . delete As a processing method for forming a division origin in the to-be-processed object in which the light emitting element structure was formed,
A wit process of placing the work on the stage,
In the state where the whole mounting surface with respect to the said stage of the to-be-processed object is cooled, the pulsed laser beam is formed so that the irradiated area for each unit pulse light is formed discretely on the workpiece surface facing the mounting surface. Irradiating the surface of the workpiece, and forming a direct deterioration region extending from the surface portion in the depth direction in the irradiated region for each unit pulse light, so that the workpiece is between the irradiated regions. An irradiation step of forming a starting point for dividing the workpiece by generating cleavage or dehiscing sequentially;
In the irradiation step, the cleavage or the cleavage between the irradiated areas of the unit pulsed light irradiated immediately or simultaneously by the impact or stress when the individual unit pulsed light is irradiated to the irradiated area. The processing method of the to-be-processed object characterized by generating. 12. The method of claim 11,
The said pulsed laser beam is ultrashort pulsed light of a pulse width of psec order, The processing method of the to-be-processed object characterized by the above-mentioned. 13. The method according to claim 11 or 12,
In the said irradiation process, the said mounting surface is arrange | positioned below the said stage, and the said mounting surface is cooled by cooling the said stage from below with the said cooling mechanism, The processing method of the to-be-processed object characterized by the above-mentioned. The method of claim 13,
The cooling mechanism comprises a Peltier element,
In the said irradiation process, the said mounting surface is cooled by cooling the said stage by the said Peltier element in the state which arrange | positioned the said Peltier element close to the said stage. 13. The method according to claim 11 or 12,
At least two irradiated areas formed by different unit pulsed lights are formed so as to be adjacent to each other in a direction where cleavage or cleavage of the workpiece is easy. 16. The method of claim 15,
The processing method of the to-be-processed object characterized by the above-mentioned formation of the at least two to-be-exposed area | regions alternately in the direction which the said two different cleavage or ten pieces of the to-be-processed object are easy. 17. The method of claim 16,
All the said irradiated area | region is formed along the direction to which cleavage or cleavage of the said workpiece | work is easy, The manufacturing method of the to-be-processed object characterized by the above-mentioned. 13. The method according to claim 11 or 12,
The said irradiated area | region is formed in the direction equivalent to the direction in which two different cleavage or ten pieces of the to-be-processed object are easy, The processing method of the to-be-processed object characterized by the above-mentioned. 13. The method according to claim 11 or 12,
Arrangement relationship of the zigzag shape to the to-be-processed object by changing the emission direction of the said pulsed laser beam periodically in the plane perpendicular | vertical to the said relative movement direction, moving the emission source of the said pulsed laser beam and the to-be-processed object relatively. Forming a plurality of the irradiated region that satisfies the processing method of the workpiece. 13. The method according to claim 11 or 12,
By periodically changing the irradiation timing of the unit pulsed light from each of the plurality of emission sources while relatively moving the plurality of emission sources of the pulsed laser light and the workpiece, the arrangement relationship of the zigzag shape is satisfied in the workpiece. A plurality of said irradiated areas are formed, The processing method of the to-be-processed object characterized by the above-mentioned. delete As a method of dividing a workpiece having a light emitting element structure,
A wit process of placing the workpiece on the stage,
In the state where the whole mounting surface with respect to the said stage of the to-be-processed object is cooled, the pulsed laser beam is formed so that the irradiated area for each unit pulse light is formed discretely on the workpiece surface facing the mounting surface. Irradiating the surface of the workpiece and forming a direct deterioration region extending from the surface portion in the depth direction in the irradiated region for each unit pulsed light, so that the workpiece is between the irradiated regions. An irradiation step of forming a starting point for dividing the workpiece by generating cleavage or dehiscing sequentially;
A dividing step of dividing the workpiece formed at the dividing origin by the irradiation step along the dividing origin;
In the irradiation step, the cleavage or the cleavage between the irradiated areas of the unit pulsed light irradiated immediately or simultaneously by the impact or stress when the individual unit pulsed light is irradiated to the irradiated area. A method of dividing a workpiece, which is generated.

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