JP4851060B2 - Manufacturing method of semiconductor laser device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a semiconductor laser device manufacturing method and a semiconductor laser device.
[0002]
[Prior art]
In recent years, when a semiconductor laser device is manufactured, a wafer having a laminated structure in which an n-type semiconductor layer, an active layer, a p-type semiconductor layer, and the like are crystal-grown on a substrate made of, for example, GaAs is cut to obtain an active layer. There is a need for a technique for forming a smooth resonance surface on the side surface. The resonance surface is formed, for example, by cleaving the active layer along a surface orthogonal to the laser resonance direction.
[0003]
For example, in the cleaving apparatus and the cleaving method disclosed in Patent Document 1, a substrate is cleaved by using a diamond scribe method on the substrate surface of the wafer and then thrusting up from the back surface of the substrate with a blade. In another manufacturing method, a groove is formed from the back surface of the substrate to a predetermined depth by using a blade dicing method, and a portion where the substrate is thin is cleaved, and at the same time, the active layer is cleaved to form a resonance surface. is there. In addition to these conventional examples, there is also a method of forming the resonance surface by etching the active layer using, for example, dry etching or wet etching.
[0004]
Here, the diamond scribe method is a method in which a scribe line is provided on the front surface of the wafer with a diamond point tool, a knife edge is pressed against the back surface of the wafer along the scribe line, and the wafer is broken and cut. On the other hand, the blade dicing method is a method of cutting a wafer by a diamond blade or the like.
[0005]
[Patent Document 1]
Japanese Patent Publication No. 7-32281
[0006]
[Problems to be solved by the invention]
However, each of the above methods has the following problems. That is, in the method of cleaving the wafer including the active layer using the diamond scribe method, the wafer surface on which the active layer is laminated cannot be damaged, and therefore the back surface of the wafer is damaged. Then, the active layer located on the opposite side of the scratch on the substrate is cleaved, and it becomes difficult to control the stress when cleaving, so that it is difficult to cleave with high accuracy.
[0007]
In the method of cleaving the wafer including the active layer after thinning the substrate using the blade dicing method, it takes a certain time to cut the substrate. In this method, a large amount of dust is generated when the substrate is cut, and a cleaning step for cleaning and removing the dust is necessary. As described above, when the blade dicing method is used, the required time becomes longer than other methods.
[0008]
Further, in the method of forming the resonance surface in the active layer by etching, it is difficult to form the resonance surface smoothly compared to the above methods, and therefore, the reflectance of the laser beam on the resonance surface can be kept low. In addition, it is difficult to accurately make the resonance plane orthogonal to the longitudinal direction of the stripe structure.
[0009]
Therefore, the present invention has been made in view of such circumstances, and a semiconductor laser element that can solve the above-described problems and can efficiently and accurately form a resonance surface by cleaving the active layer. An object of the present invention is to provide a manufacturing method and a semiconductor laser device.
[0010]
[Means for Solving the Problems]
  In order to achieve the above object, a semiconductor laser device manufacturing method according to the present invention includes a first conductive semiconductor layer, an active layer, and a second conductive semiconductor layer on a surface of a substrate made of a III-V group compound semiconductor. A method of manufacturing a semiconductor laser device having a stripe structure in which a first conductive type semiconductor layer, an active layer, and a second conductive type semiconductor layer are stacked on a surface of a substrate, and on a surface excluding a planned cutting line In addition, a modified region by multiphoton absorption is formed only inside the substrate by aligning the focal point with the inside of the wafer substrate on which the electrodes are formed in the regions on the back surface and irradiating with pulsed laser light. By the quality region, a cutting origin region is formed at a predetermined distance inside from the laser light incident surface of the wafer along a planned cutting line extending in a direction perpendicular to the longitudinal direction of the stripe structure,By growing cracks from the cutting origin region to the front and back surfaces of the substrateSubstrate along the cutting origin area, First conductive type semiconductor layer and second conductive type semiconductor layerAnd a step of cleaving the active layer, and the peak power density at the focal point of the pulsed laser beam is 1 × 10⁸(W / cm²), The pulse width of the pulsed laser light is 1 μs or less, and the portion where no electrode is provided on the back surface of the wafer is the laser light incident surface.
[0011]
  The method of manufacturing a semiconductor laser device according to the present invention also includes a stripe in which a first conductive semiconductor layer, an active layer, and a second conductive semiconductor layer are stacked on a surface of a semiconductor substrate made of a III-V compound semiconductor. A method of manufacturing a semiconductor laser device having a structure, wherein a first conductivity type semiconductor layer, an active layer, and a second conductivity type semiconductor layer are stacked on a surface of a semiconductor substrate, and on a front surface and a back surface except for a line to be cut. The melt processing region is formed only inside the semiconductor substrate by aligning the focal point with the inside of the semiconductor substrate of the wafer on which the electrodes are formed in each region and irradiating the pulse laser beam. A cutting start region is formed at a predetermined distance inside from the laser light incident surface of the wafer along a planned cutting line extending in a direction orthogonal to the longitudinal direction ofBy growing cracks from the cutting origin region to the front and back surfaces of the semiconductor substrateSemiconductor substrate along the cutting origin area, First conductive type semiconductor layer and second conductive type semiconductor layerAnd a step of cleaving the active layer, and the peak power density at the focal point of the pulsed laser beam is 1 × 10⁸(W / cm²), The pulse width of the pulsed laser light is 1 μs or less, and the portion where no electrode is provided on the back surface of the wafer is the laser light incident surface.
[0012]
  According to these methods for manufacturing a semiconductor laser device, a modified region (or a melt-processed region) formed inside a (semiconductor) substrate of a wafer (due to a phenomenon called multiphoton absorption) along a planned cutting line. A cutting starting region can be formed, and the (semiconductor) substrate can be efficiently divided and cut along the cutting starting region with a relatively small force. Then, by cutting the (semiconductor) substrate, the active layer is cleaved with high accuracy along the planned cutting line. Therefore, according to this manufacturing method, it is possible to efficiently and accurately form the resonance surface by cleaving the active layer.In these semiconductor laser element manufacturing methods, when the modified region is formed, a plurality of modified regions may be formed in the thickness direction of the substrate. Alternatively, when forming the melt processing region, a plurality of the melt processing regions may be formed in the thickness direction of the semiconductor substrate. Further, in these semiconductor laser device manufacturing methods, when the modified region is formed, the modified region is formed along a plurality of planned cutting lines, and the modified region is formed along each planned cutting line. A plurality may be formed in the direction. Alternatively, when forming the melt processing region, the melt processing region may be formed along a plurality of scheduled cutting lines, and a plurality of the melt processing regions may be formed in a direction along each planned cutting line.
[0013]
Here, the semiconductor layer such as the first conductive semiconductor layer, the active layer, and the second conductive semiconductor layer stacked on the surface of the substrate may be provided in close contact with the substrate or may be spaced from the substrate. Including what is provided. Examples include a semiconductor layer formed by crystal growth on a substrate, a semiconductor layer fixed on the substrate after being stacked separately from the substrate, and the like. In addition, the inside of the substrate includes the surface of the substrate on which the semiconductor layer is provided. Furthermore, a condensing point is a location where the laser beam is condensed. The cutting start region may be formed by continuously forming the modified region, or may be formed by intermittently forming the modified region.
[0014]
In the semiconductor laser device manufacturing method according to the present invention described above, it is preferable to apply stress to the wafer when the substrate is cut. As a result, the wafer having the cutting start region can be easily cut.
[0015]
  In the above-described method for manufacturing a semiconductor laser device according to the present invention, it is preferable that the back surface of the substrate is the laser light incident surface when the inside of the substrate is irradiated with laser light. According to this manufacturing method, even if any of the first conductive type semiconductor layer, the active layer, and the second conductive type semiconductor layer does not transmit laser light, the modified region is provided inside the wafer substrate. A cutting start region can be formed. It is further preferable that the back surface of the substrate is flat and smooth. Thereby, scattering of laser light on the back surface can be prevented.In the method for manufacturing a semiconductor laser device according to the present invention described above, when the cutting start region is formed, the cutting start region is formed along a plurality of scheduled cutting lines and the substrate is cut. It is preferable to cut the substrate into a plurality of bar-shaped members along the region, and then cut the plurality of bar-shaped members into chips. Then, when forming the cutting start region, another cutting starting region is formed along the direction intersecting with a plurality of scheduled cutting lines, and when cutting the substrate, a plurality of bar shapes are formed along the other cutting starting region. More preferably, the member is cut into chips.
[0016]
The semiconductor laser device according to the present invention is a semiconductor laser device having a stripe structure in which a first conductivity type semiconductor layer, an active layer, and a second conductivity type semiconductor layer are stacked on the surface of a substrate, and the inside of the substrate. The laser beam is irradiated with the focusing point to form a modified region by multiphoton absorption, and this modified region forms a stripe structure by a cutting starting region formed at a predetermined distance from the laser beam incident surface of the wafer. It is cut in a direction perpendicular to the longitudinal direction, and the active layer is cleaved in that direction.
[0017]
A semiconductor laser device according to the present invention is a semiconductor laser device having a stripe structure in which a first conductive type semiconductor layer, an active layer, and a second conductive type semiconductor layer are stacked on a surface of a semiconductor substrate. The melt processing region is formed by irradiating the laser beam with the condensing point inside, and the longitudinal direction of the stripe structure is formed by the cutting start region formed at a predetermined distance from the laser beam incident surface of the wafer by the melting processing region. The semiconductor substrate is cut in a direction orthogonal to the direction, and the active layer is cleaved in that direction.
[0018]
  According to this semiconductor laser device, the length of the stripe structure is reduced by the cutting origin region formed by the modified region (melting region) formed inside the (semiconductor) substrate of the wafer (by the phenomenon of multiphoton absorption). The (semiconductor) substrate is efficiently divided and cut along a direction orthogonal to the direction with a relatively small force. Then, the active layer is cleaved with high accuracy by cutting the (semiconductor) substrate. Therefore, it is possible to provide a semiconductor laser device in which the resonance surface by cleavage of the active layer is efficiently and accurately formed.In this semiconductor laser element, a plurality of modified regions (melted regions) may be formed in the thickness direction of the substrate. In this semiconductor laser device, it is preferable that the substrate is cut in a direction intersecting with the longitudinal direction of the stripe structure by a cutting start region different from the cutting start region.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
DESCRIPTION OF EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. In the semiconductor laser device manufacturing method according to the present embodiment, a laser beam is irradiated to the inside of a wafer substrate to form a modified region by multiphoton absorption. This laser processing method, particularly multiphoton absorption, will be described first.
[0020]
Band gap E of material absorption_GIf the photon energy hv is smaller than that, it becomes optically transparent. Therefore, the condition for absorption in the material is hν> E_GIt is. However, even if it is optically transparent, if the intensity of the laser beam is made very large, nhν> E_GUnder these conditions (n = 2, 3, 4,...), Absorption occurs in the material. This phenomenon is called multiphoton absorption. In the case of a pulse wave, the intensity of the laser beam is the peak power density (W / cm at the condensing point of the laser beam).²), For example, the peak power density is 1 × 10⁸(W / cm²) Multiphoton absorption occurs under the above conditions. The peak power density is determined by (energy per pulse of laser light at the condensing point) / (laser beam cross-sectional area of laser light × pulse width). In the case of a continuous wave, the intensity of the laser beam is the electric field intensity (W / cm at the focal point of the laser beam).²)
[0021]
The principle of laser processing using such multiphoton absorption will be described with reference to FIGS. 1 is a plan view of the substrate 1 during laser processing, FIG. 2 is a cross-sectional view taken along the line II-II of the substrate 1 shown in FIG. 1, and FIG. 3 is a plan view of the substrate 1 after laser processing. 4 is a cross-sectional view taken along line IV-IV of the substrate 1 shown in FIG. 3, FIG. 5 is a cross-sectional view taken along line V-V of the substrate 1 shown in FIG. 3, and FIG. It is a top view of the board | substrate 1 made.
[0022]
As shown in FIGS. 1 and 2, a desired cutting line 5 is set on the substrate 1. The planned cutting line 5 is a virtual line extending in a straight line, and in this embodiment, is a boundary line when the wafer is divided into a plurality along the cleavage plane of the active layer. It is also possible to draw a line on the wafer as the planned cutting line 5. In the present embodiment, the modified region 7 is formed by irradiating the laser beam L after aligning the condensing point P inside the substrate 1 under the condition that multiphoton absorption occurs. In addition, the condensing point P is a location where the laser beam L is condensed.
[0023]
The condensing point P is moved along the planned cutting line 5 by relatively moving the laser light L along the planned cutting line 5 (that is, along the direction of the arrow A). Thereby, as shown in FIGS. 3 to 5, the modified region 7 is formed only inside the substrate 1 along the planned cutting line 5, and the cutting start region 8 is formed by the modified region 7. This laser processing method does not form the modified region 7 by causing the substrate 1 to generate heat when the substrate 1 absorbs the laser light L. The modified region 7 is formed by transmitting the laser light L through the substrate 1 and generating multiphoton absorption inside the substrate 1. Therefore, since the laser beam L is hardly absorbed by the laser beam incident surface 6 of the substrate 1, the laser beam incident surface 6 of the substrate 1 is not melted.
[0024]
In the cutting of the substrate 1, if there is a starting point at the position to be cut, the substrate 1 breaks from the starting point, so that the substrate 1 can be cut with a relatively small force as shown in FIG. Therefore, the substrate 1 can be cut easily, accurately, and efficiently without causing unnecessary cracking such as chipping on the surface of the substrate 1.
[0025]
Note that the following two types of cutting of the substrate starting from the cutting start region can be considered. One is a case where, after the cutting start region is formed, an artificial stress is applied to the substrate, so that the substrate is cracked and the substrate is cut from the cutting start region. This is cutting when the thickness of the substrate is large, for example. The artificial stress is applied, for example, by applying bending stress or shear stress to the substrate along the cutting start region of the substrate, or generating thermal stress by giving a temperature difference to the substrate. . The other one is a case where by forming the cutting start region, the substrate is naturally cracked in the cross-sectional direction (thickness direction) of the substrate starting from the cutting start region, resulting in the substrate being cut. For example, when the substrate thickness is small, the cutting start region is formed by one row of modified regions, and when the substrate thickness is large, multiple rows are formed in the thickness direction. This can be achieved by forming a cutting start region by the modified region. In addition, even when this breaks naturally, in the part to be cut, the part corresponding to the part where the cutting starting point region is formed without cracking ahead on the surface of the part corresponding to the part where the cutting starting point region is not formed Since it is possible to cleave only, the cleaving can be controlled well. In recent years, since the thickness of a substrate such as a wafer substrate tends to be thin, such a cleaving method with good controllability is very effective.
[0026]
In the present embodiment, the modified regions formed by multiphoton absorption include the following (1) to (3).
[0027]
(1) When the modified region is a crack region including one or more cracks
For example, the focusing point is set inside a substrate made of sapphire or glass, and the electric field strength at the focusing point is 1 × 10.⁸(W / cm²) Irradiation with laser light is performed under the above conditions with a pulse width of 1 μs or less. The magnitude of this pulse width is a condition under which a crack region can be formed only inside the substrate without causing extra damage to the surface of the substrate while causing multiphoton absorption. As a result, a phenomenon of optical damage due to multiphoton absorption occurs inside the substrate. This optical damage induces thermal strain inside the substrate, thereby forming a crack region inside the substrate. As an upper limit value of the electric field strength, for example, 1 × 10¹²(W / cm²). The pulse width is preferably 1 ns to 200 ns, for example.
[0028]
The inventor obtained the relationship between the electric field strength and the size of the cracks by experiment. The experimental conditions are as follows.
(A) Substrate: Pyrex (registered trademark) glass (thickness 700 μm)
(B) Laser
Light source: Semiconductor laser pumped Nd: YAG laser
Wavelength: 1064nm
Laser beam spot cross-sectional area: 3.14 × 10^-8cm²
Oscillation form: Q switch pulse
Repeat frequency: 100 kHz
Pulse width: 30ns
Output: Output <1mJ / pulse
Laser light quality: TEM₀₀
Polarization characteristics: linearly polarized light
(C) Condensing lens
Transmittance to laser light wavelength: 60 percent
(D) Moving speed of the mounting table on which the substrate is mounted: 100 mm / second
[0029]
The laser beam quality is TEM₀₀The term “highly condensing” means that light can be condensed up to the wavelength of laser light.
[0030]
FIG. 7 is a graph showing the results of the experiment. The horizontal axis represents the peak power density. Since the laser beam is a pulsed laser beam, the electric field strength is represented by the peak power density. The vertical axis indicates the size of a crack portion (crack spot) formed inside the substrate by one pulse of laser light. Crack spots gather to form a crack region. The size of the crack spot is the size of the portion having the maximum length in the shape of the crack spot. Data indicated by black circles in the graph is for the case where the magnification of the condenser lens (C) is 100 times and the numerical aperture (NA) is 0.80. On the other hand, the data indicated by the white circles in the graph is when the magnification of the condenser lens (C) is 50 times and the numerical aperture (NA) is 0.55. Peak power density is 10¹¹(W / cm²From the above, it can be seen that crack spots are generated inside the substrate, and the crack spots increase as the peak power density increases.
[0031]
Next, in the laser processing method described above, a mechanism for cutting the substrate by forming a crack region will be described with reference to FIGS. As shown in FIG. 8, the condensing point P is set inside the substrate 1 under the condition that multiphoton absorption occurs, and the substrate 1 is irradiated with the laser light L to form a crack region 9 along the planned cutting line 5. To do. The crack region 9 is a region including one or more cracks. A cutting start region is formed by the crack region 9. As shown in FIG. 9, the crack further grows starting from the crack region 9 (that is, starting from the cutting start region), and the crack reaches both surfaces of the substrate 1 as shown in FIG. 10, and as shown in FIG. The substrate 1 is cut by breaking the substrate 1. The cracks that reach both sides of the substrate may grow naturally or may grow when a force is applied to the substrate.
[0032]
(2) When the reforming region is a melt processing region
For example, the focusing point is set inside a substrate made of a semiconductor material such as GaAs or silicon, and the electric field strength at the focusing point is 1 × 10⁸(W / cm²) Irradiation with laser light is performed under the above conditions with a pulse width of 1 μs or less. As a result, the inside of the substrate is locally heated by multiphoton absorption. By this heating, a melt processing region is formed inside the substrate. The melt treatment region is a region once solidified after melting, a region in a molten state, or a region re-solidified from a molten state, and can also be referred to as a phase-changed region or a region in which the crystal structure has changed. The melt treatment region can also be said to be a region in which one structure is changed to another structure in a single crystal structure, an amorphous structure, or a polycrystalline structure. In other words, for example, a region changed from a single crystal structure to an amorphous structure, a region changed from a single crystal structure to a polycrystalline structure, or a region changed from a single crystal structure to a structure including an amorphous structure and a polycrystalline structure. To do. When the substrate has a silicon single crystal structure, the melt processing region has, for example, an amorphous silicon structure. As an upper limit value of the electric field strength, for example, 1 × 10¹²(W / cm²). The pulse width is preferably 1 ns to 200 ns, for example. Moreover, it is possible to form the above-described melt processing region not only in silicon but also in sapphire, for example.
[0033]
The inventor has confirmed through experiments that a melt-processed region is formed inside a silicon wafer. The experimental conditions are as follows.
(A) Substrate: Silicon wafer (thickness 350 μm, outer diameter 4 inches)
(B) Laser
Light source: Semiconductor laser pumped Nd: YAG laser
Wavelength: 1064nm
Laser beam spot cross-sectional area: 3.14 × 10^-8cm²
Oscillation form: Q switch pulse
Repeat frequency: 100 kHz
Pulse width: 30ns
Output: 20μJ / pulse
Laser light quality: TEM₀₀
Polarization characteristics: linearly polarized light
(C) Condensing lens
Magnification: 50 times
N. A. : 0.55
Transmittance to laser light wavelength: 60 percent
(D) Moving speed of the mounting table on which the substrate is mounted: 100 mm / second
[0034]
FIG. 12 is a view showing a photograph of a cross section of a part of a silicon wafer cut by laser processing under the above conditions. A melt processing region 13 is formed inside the silicon wafer 11. The size in the thickness direction of the melt processing region 13 formed under the above conditions is about 100 μm.
[0035]
The fact that the melt processing region 13 is formed by multiphoton absorption will be described. FIG. 13 is a graph showing the relationship between the wavelength of the laser beam and the transmittance inside the silicon substrate. However, the reflection components on the front side and the back side of the silicon substrate are removed to show the transmittance only inside. The above relationship was shown for each of the thickness t of the silicon substrate of 50 μm, 100 μm, 200 μm, 500 μm, and 1000 μm.
[0036]
For example, when the thickness of the silicon substrate is 500 μm or less at the wavelength of the Nd: YAG laser of 1064 nm, it can be seen that the laser light is transmitted by 80% or more inside the silicon substrate. Since the thickness of the silicon wafer 11 shown in FIG. 12 is 350 μm, when the melting region 13 by multiphoton absorption is formed near the center of the silicon wafer, it is formed at a portion of 175 μm from the laser light incident surface. In this case, the transmittance is 90% or more with reference to a silicon wafer having a thickness of 200 μm. Therefore, the laser beam is hardly absorbed inside the silicon wafer 11 and almost all is transmitted. This is not because the laser beam is absorbed inside the silicon wafer 11 and the melt processing region 13 is formed inside the silicon wafer 11 (that is, the melt processing region is formed by normal heating with laser light) It means that the melt processing region 13 is formed by multiphoton absorption.
[0037]
Silicon wafers are cracked in the cross-sectional direction starting from the cutting start region formed by the melt processing region, and the cracks reach the front and back surfaces of the silicon wafer, resulting in cutting. Is done. The cracks that reach the front and back surfaces of the silicon wafer may grow spontaneously or may grow when a force is applied to the silicon wafer. In addition, when a crack naturally grows from the cutting start region to the front and back surfaces of the silicon wafer, the case where the crack grows from a state where the melt treatment region forming the cutting starting region is melted, and the cutting starting region There are both cases where cracks grow when the solidified region is melted from the molten state. However, in either case, the melt processing region is formed only inside the silicon wafer, and the melt processing region is formed only inside the cut surface after cutting as shown in FIG. If the cutting start region is formed in the substrate by the melt processing region, unnecessary cracking off the cutting start region line is unlikely to occur during cleaving, so that cleaving control is facilitated.
[0038]
(3) When the modified region is a refractive index changing region
For example, the focusing point is set inside a substrate made of glass or the like, and the electric field strength at the focusing point is 1 × 10⁸(W / cm²) Irradiation with laser light is performed under the above conditions with a pulse width of 1 ns or less. When the pulse width is made extremely short and multiphoton absorption occurs inside the substrate, the energy due to the multiphoton absorption is not converted into thermal energy, and the ionic valence change, crystallization, polarization orientation, etc. are inside the substrate. A permanent structural change is induced to form a refractive index changing region. As an upper limit value of the electric field strength, for example, 1 × 10¹²(W / cm²). For example, the pulse width is preferably 1 ns or less, and more preferably 1 ps or less.
[0039]
As described above, the cases of (1) to (3) have been described as the modified regions formed by multiphoton absorption. However, the cutting starting region is formed as follows in consideration of the crystal structure of the substrate and its cleavage property. For example, the substrate can be cut with a smaller force and with higher accuracy from the cutting start region. In addition, when an active layer is stacked on the surface of the substrate, if the cutting starting region is formed as follows in consideration of the crystal structure of the active layer and its cleavage property, the substrate starts from the cutting starting region. When being cut, the active layer can be cleaved easily and accurately.
[0040]
That is, when the substrate is made of a single crystal semiconductor having a diamond structure such as silicon, the cutting start region is formed in a direction along the (111) plane (first cleavage plane) or the (110) plane (second cleavage plane). Is preferred. In addition, when the substrate or the active layer is made of a zinc-blende-type III-V compound semiconductor such as GaAs, it is preferable to form the cutting start region in the direction along the (110) plane. Further, when the substrate has a hexagonal crystal structure such as sapphire, the (0001) plane (C plane) is the main plane, and the (1120) plane (A plane) or (1100) plane (M plane) is taken along. It is preferable to form the cutting start region in the direction.
[0041]
Note that an orientation flat (described later) along the direction in which the above-described cutting start region is to be formed (for example, the direction along the (110) plane of the GaAs substrate) or the direction perpendicular to the direction in which the cutting start region is to be formed. ), The cutting origin region can be easily and accurately formed on the substrate by using the orientation flat as a reference.
[0042]
Next, a laser processing apparatus used in the laser processing method described above will be described with reference to FIG. FIG. 14 is a schematic configuration diagram of the laser processing apparatus 100.
[0043]
The laser processing apparatus 100 includes a laser light source 101 that generates laser light L, a laser light source control unit 102 that controls the laser light source 101 to adjust the output and pulse width of the laser light L, and the reflection function of the laser light L. And a dichroic mirror 103 arranged to change the direction of the optical axis of the laser light L by 90 °, a condensing lens 105 for condensing the laser light L reflected by the dichroic mirror 103, and a condensing lens A mounting table 107 on which the substrate 1 irradiated with the laser beam L condensed by the lens 105 is mounted, an X-axis stage 109 for moving the mounting table 107 in the X-axis direction, and the mounting table 107 as the X-axis A Y-axis stage 111 for moving in the Y-axis direction orthogonal to the direction, and a Z-axis stage 113 for moving the mounting table 107 in the Z-axis direction orthogonal to the X-axis and Y-axis directions; And a stage controller 115 for controlling the movement of these three stages 109, 111 and 113.
[0044]
The converging point P is moved in the X (Y) axis direction by moving the substrate 1 in the X (Y) axis direction by the X (Y) axis stage 109 (111). Since the Z-axis direction is a direction orthogonal to the back surface 4 of the substrate 1, the Z-axis direction is the direction of the focal depth of the laser light L incident on the substrate 1. Therefore, by moving the Z-axis stage 113 in the Z-axis direction, the condensing point P of the laser light L can be adjusted inside the substrate 1. Thereby, the condensing point P can be adjusted to a desired position inside a predetermined distance from the laser light incident surface 6 of the substrate 1.
[0045]
The laser light source 101 is an Nd: YAG laser that generates pulsed laser light. Other lasers that can be used for the laser light source 101 include Nd: YVO._FourThere are lasers, Nd: YLF lasers, and titanium sapphire lasers. In this embodiment, pulsed laser light is used for processing the substrate 1, but continuous wave laser light may be used as long as multiphoton absorption can be caused.
[0046]
The laser processing apparatus 100 further includes an observation light source 117 that generates visible light to illuminate the substrate 1 mounted on the mounting table 107 with visible light, and the same optical axis as the dichroic mirror 103 and the condensing lens 105. And a beam splitter 119 for visible light. A dichroic mirror 103 is disposed between the beam splitter 119 and the condensing lens 105. The beam splitter 119 has a function of reflecting about half of visible light and transmitting the other half, and is arranged so as to change the direction of the optical axis of visible light by 90 °. About half of the visible light generated from the observation light source 117 is reflected by the beam splitter 119, and the reflected visible light passes through the dichroic mirror 103 and the condensing lens 105 and includes the planned cutting line 5 of the substrate 1. The laser light incident surface 6 is illuminated.
[0047]
The laser processing apparatus 100 further includes an imaging element 121 and an imaging lens 123 disposed on the same optical axis as the beam splitter 119, the dichroic mirror 103, and the condensing lens 105. An example of the image sensor 121 is a CCD camera. The reflected light of the visible light that illuminates the laser light incident surface 6 including the planned cutting line 5 and the like passes through the condensing lens 105, the dichroic mirror 103, and the beam splitter 119, and is imaged by the imaging lens 123 to be imaged. The image is captured at 121 and becomes captured image data.
[0048]
The laser processing apparatus 100 further includes an imaging data processing unit 125 to which imaging data output from the imaging element 121 is input, an overall control unit 127 that controls the entire laser processing apparatus 100, and a monitor 129. The imaging data processing unit 125 calculates focus data for focusing the visible light generated by the observation light source 117 on the laser light incident surface 6 of the substrate 1 based on the imaging data. The stage control unit 115 controls the movement of the Z-axis stage 113 based on the focus data so that the visible light is focused on the laser light incident surface 6 of the substrate 1. Therefore, the imaging data processing unit 125 functions as an autofocus unit. Further, the imaging data processing unit 125 calculates image data such as an enlarged image of the laser light incident surface 6 based on the imaging data. This image data is sent to the overall control unit 127, where various processes are performed by the overall control unit, and sent to the monitor 129. Thereby, an enlarged image or the like is displayed on the monitor 129.
[0049]
Data from the stage controller 115, image data from the imaging data processor 125, and the like are input to the overall controller 127. Based on these data, the laser light source controller 102, the observation light source 117, and the stage controller By controlling 115, the entire laser processing apparatus 100 is controlled. Therefore, the overall control unit 127 functions as a computer unit.
[0050]
The laser light incident surface 6 of the substrate 1 may be either the front surface or the back surface of the substrate 1. For example, when a semiconductor layer or the like that does not transmit laser light is laminated on the surface of the substrate 1, the substrate 1 may be placed on the mounting table 107 so that the back surface of the substrate 1 is on the condensing lens 105 side. . Further, the laser light incident surface 6 of the substrate 1 is preferably flat and smooth in order to prevent the laser light from being scattered on the laser light incident surface 6.
[0051]
Next, a manufacturing method of the semiconductor laser device according to the present embodiment using the laser processing method and the laser processing apparatus 100 described above will be described. FIG. 15 is a perspective view showing a wafer used in the method of manufacturing a semiconductor laser device according to this embodiment. FIG. 16 is a bottom view of the wafer shown in FIG. FIG. 17 is an enlarged view showing a VI-VI cross section of the wafer shown in FIG.
[0052]
Referring to FIGS. 15 to 17, the wafer 2 has a substantially disk shape. In the present embodiment, the wafer 2 includes an n-type semiconductor substrate 1, an n-type cladding layer 23 that is a first conductivity type semiconductor layer stacked on the surface 21 of the substrate 1, and an n-type cladding layer 23. A stacked active layer 25; a p-type cladding layer 27 which is a second conductive semiconductor layer stacked on the active layer 25; and a cap layer 29 made of a p-type semiconductor stacked on the p-type cladding layer 27; It has. Of these layers, the n-type cladding layer 23, the active layer 25, and the p-type cladding layer 27 constitute a quantum well structure. Alternatively, the active layer 25 may have a multiple quantum well structure in which a plurality of well layers having a small band gap and barrier layers having a large band gap are alternately stacked. Further, the back surface 4 of the substrate 1 is flat and smooth.
[0053]
Taking an Al-GaAs semiconductor laser element as an example, GaAs is used as the material of the substrate 1 and the cap layer 29, and the materials of the n-type cladding layer 23, the active layer 25, and the p-type cladding layer 27 are used. For example, AlGaAs is used. The semiconductor laser element is not limited to the Al—GaAs system, but may be an In—GaAs system, an AlGaInP system, or a GaN system. The thickness of each layer is, for example, 350 μm for the substrate 1, 500 mm (50 nm) for the n-type cladding layer 23, 100 mm (10 nm) for the active layer 25, 500 mm (50 nm) for the p-type cladding layer 27, and the cap layer 29. Is 500 mm (50 nm).
[0054]
Referring to FIG. 16, a plurality of cutting lines 5 are set on the back surface 4 of the wafer 2. The planned cutting line 5 is an imaginary line assumed for cutting the wafer 2 into a plurality of rod-shaped portions, and is set in a direction along the cleavage plane of the active layer 25. That is, the planned cutting line 5 is set in a direction along the (110) plane of the active layer 25 made of AlGaAs. Moreover, it is preferable that the cleaved surface of the substrate 1 is parallel to the direction along the line 5 to be cut. In other words, the active layer 25 is preferably laminated so that the direction of the (110) plane of the substrate 1 made of GaAs coincides with the direction of the (110) plane of the active layer 25 made of AlGaAs. The direction orthogonal to the planned cutting line 5 is the longitudinal direction of the stripe structure in the semiconductor laser element (that is, the resonance direction of the laser beam). Moreover, the space | interval of the cutting planned line 5 adjacent to each other is about 2 mm, for example.
[0055]
The wafer 2 has an orientation flat (hereinafter referred to as “OF”) 19. In the present embodiment, the OF 19 is formed with the direction perpendicular to the planned cutting line 5 as the longitudinal direction. The OF 19 is provided for the purpose of easily discriminating the cutting direction when the wafer 2 is cut along the scheduled cutting line 5. The OF 19 may be formed with the direction parallel to the planned cutting line 5 as the longitudinal direction.
[0056]
18 and 19 are flowcharts for explaining the method of manufacturing the semiconductor laser device according to this embodiment. 20 to 23 are cross-sectional views of the wafer 2 for explaining a method for manufacturing a semiconductor laser element.
[0057]
Referring to FIG. 18, first, the cathode electrode 31 and the anode electrode 33 are formed on the back surface 4 and the front surface 22 of the wafer 2, respectively (S1, FIG. 20). At this time, these electrodes are not formed around the planned cutting line 5. Further, the semiconductor laser device is formed to be elongated with the direction perpendicular to the planned cutting line 5 as the longitudinal direction so as to have a stripe structure. As an example of the process of forming the cathode electrode 31 and the anode electrode 33, (1) a metal film is formed on the front surface 22 and the back surface 4 of the wafer 2, (2) a resist is applied to the surface of the metal film, 3) The resist is exposed using a reticle having a desired electrode pattern, (4) the exposed portion is removed by developing the resist, and (5) the exposed portion of the metal film is removed by etching. Remove. Through these steps, the cathode electrode 31 and the anode electrode 33 are formed.
[0058]
Subsequently, a cutting start region is formed along the planned cutting line 5 inside the substrate 1 of the wafer 2 (S3, FIG. 21). That is, the portion of the back surface 4 of the substrate 1 where the cathode electrode 31 is not provided is used as a laser light incident surface, and the condensing point P inside the substrate 1 is irradiated with the laser light L to modify the inside of the substrate 1. Region 7 is formed. The modified region 7 becomes a cutting start region when the wafer 2 is cut.
[0059]
Here, FIG. 19 is a flowchart showing a method of forming a cutting start region on the wafer 2 using the laser processing apparatus 100 shown in FIG. In the present embodiment, the wafer 2 is disposed on the mounting table 107 of the laser processing apparatus 100 so that the back surface 4 of the substrate 1 faces the condensing lens 105. That is, the laser beam L is incident from the back surface 4 of the substrate 1 of the wafer 2.
[0060]
14 and 19, first, the light absorption characteristics of the substrate 1 are measured by a spectrophotometer or the like (not shown). Based on this measurement result, a laser light source 101 that generates laser light L having a wavelength transparent to the substrate 1 or a wavelength with little absorption is selected (S101).
[0061]
Subsequently, the amount of movement of the wafer 2 in the Z-axis direction is determined in consideration of the thickness, material, refractive index, and the like of the substrate 1 (S103). This is based on the condensing point P of the laser light L positioned on the back surface 4 of the substrate 1 in order to align the condensing point P of the laser light L with a desired position inside the predetermined distance from the back surface 4 of the substrate 1. This is the amount of movement of the wafer 2 in the Z-axis direction. This movement amount is input to the overall control unit 127.
[0062]
The wafer 2 is mounted on the mounting table 107 of the laser processing apparatus 100 so that the back surface 4 of the substrate 1 faces the condensing lens 105 side. Then, visible light is generated from the observation light source 117 to illuminate the back surface 4 of the substrate 1 (S105). The back surface 4 of the illuminated substrate 1 is imaged by the image sensor 121. Imaging data captured by the imaging element 121 is sent to the imaging data processing unit 125. Based on this imaging data, the imaging data processing unit 125 calculates focus data such that the visible light focus of the observation light source 117 is located on the back surface 4 of the substrate 1 (S107).
[0063]
This focus data is sent to the stage controller 115. The stage controller 115 moves the Z-axis stage 113 in the Z-axis direction based on the focus data (S109). Thereby, the focus of the visible light of the observation light source 117 is located on the back surface 4 of the substrate 1. The imaging data processing unit 125 calculates the enlarged image data of the back surface 4 including the scheduled cutting line 5 based on the imaging data. This enlarged image data is sent to the monitor 129 via the overall control unit 127, whereby an enlarged image near the planned cutting line 5 is displayed on the monitor 129.
[0064]
The movement amount data determined in advance in step S <b> 103 is input to the overall control unit 127, and this movement amount data is sent to the stage control unit 115. Based on this movement amount data, the stage controller 115 moves the wafer 2 in the Z-axis direction by the Z-axis stage 113 so that the position of the condensing point P of the laser light L is a predetermined distance from the back surface 4 of the substrate 1. Move (S111).
[0065]
Subsequently, laser light L is generated from the laser light source 101 and the back surface 4 of the substrate 1 is irradiated with the laser light L. Since the condensing point P of the laser beam L is located inside the substrate 1, the modified region 7 is formed only inside the substrate 1.
[0066]
Subsequently, the X-axis stage 109 and the Y-axis stage 111 are moved along the planned cutting line 5 to form a plurality of modified regions 7, or the modified regions 7 are continuously formed along the planned cutting line 5. By forming, a cutting start region along the planned cutting line 5 is formed inside the substrate 1 (S113).
[0067]
Here, referring again to FIG. 18, after forming the cutting start region on the substrate 1 of the wafer 2, the wafer 2 is cut into a plurality of rod-shaped members 37 along the cutting start region (S5, FIG. 22 (a) and (B)). That is, for example, a knife edge is pressed against the front surface 22 or the back surface 4 of the wafer and stress is applied to the wafer 2 on which the cutting start region is formed, thereby cutting the substrate 1 using the cutting start region as a starting point. Alternatively, the substrate 1 may be cut by applying stress using an expanding tape, a breaker device, a roller device, or the like. In addition, by irradiating the wafer surface or the back surface of the wafer with laser light having an absorptivity with respect to the wafer with energy that does not melt the surface, the wafer is cut by generating a thermal stress that causes a crack starting from the cutting start region. May be. At this time, when the substrate 1 is cut, the active layer 25 having a cleavage plane along the planned cutting line 5 is cleaved at the cleavage plane, so that the two resonance surfaces facing each other with the active layer 25 interposed therebetween. 35 is formed in each rod-shaped member 37. In addition, the n-type cladding layer 23, the p-type cladding layer 27, and the cap layer 29 are also cut at the same time as the substrate 1 is cut.
[0068]
Subsequently, the rod-shaped member 37 is cut into chips (S7, FIG. 23 (a)). That is, the rod-shaped members 37 are cut at equal intervals on a plurality of cutting surfaces orthogonal to the cutting start region. Thereby, the chip-shaped semiconductor laser element 39 is obtained. As a method of cutting the rod-shaped member 37, blade dicing, dry etching, wet etching, or the like can be used in addition to the laser processing method described above.
[0069]
FIG. 23B is a perspective view showing the configuration of the semiconductor laser element 39 obtained through the above steps. In this semiconductor laser device 39, a cathode electrode 31 is provided on the back surface 4 of the substrate 1 with the direction orthogonal to the cutting start region 8 as the longitudinal direction. On the surface of the substrate 1, an n-type cladding layer 23, an active layer 25, a p-type cladding layer 27, and a cap layer 29 are stacked. The cap layer 29 is provided with an anode 33 with the direction perpendicular to the cutting start region 8 as the longitudinal direction. Of the side surfaces of the substrate 1, two side surfaces intersecting with the longitudinal direction of the stripe structure include the cutting start region 8, and each of the two resonance surfaces 35 on the same plane as each of these side surfaces is an active layer. 25 cleaved.
[0070]
As shown in FIG. 23B, according to the manufacturing method of the semiconductor laser device according to the present embodiment, the semiconductor laser device 39 is obtained in which the direction perpendicular to the cutting start region 8 is the longitudinal direction of the stripe structure. That is, since the width of the cathode electrode 31 and the anode electrode 33 in the direction intersecting the longitudinal direction is narrower than the width of the active layer 25, the drive current flowing through the active layer 25 is at the center of the active layer 25. Gather in stripes. Since the stripe portion is sandwiched between the resonance surfaces 35, laser oscillation occurs along the stripe portion in the active layer 25.
[0071]
As described above, in the method of manufacturing a semiconductor laser device and the semiconductor laser device according to this embodiment, the planned cutting line 5 is formed in the modified region formed by the phenomenon of multiphoton absorption inside the substrate 1 of the wafer 2. A cutting start area along the cutting start area can be formed, and the substrate 1 can be efficiently divided and cut along the cutting start area with a relatively small force. Then, the active layer 25 is cleaved along the scheduled cutting line 5 with high accuracy by cutting the substrate 1. Therefore, according to this manufacturing method, the resonance surface 35 by cleavage of the active layer 25 can be easily and accurately formed.
[0072]
In the method for manufacturing a semiconductor laser device according to this embodiment, stress is applied to the wafer 2 when the substrate 1 is cut. Since the wafer 2 having the cutting start region can be cut by a relatively small force, the wafer 2 can be easily cut by applying stress to the wafer 2.
[0073]
In the method for manufacturing a semiconductor laser device according to this embodiment, when the laser light L is irradiated inside the substrate 1, the back surface 4 of the substrate 1 is used as the laser light incident surface. According to this manufacturing method, even if any of the semiconductor layers stacked on the substrate 1 such as the n-type cladding layer 23, the active layer 25, and the p-type cladding layer 27 does not transmit the laser beam L, the wafer A cutting start region can be formed in the second substrate 1 by the modified region 7. If the back surface 4 of the substrate 1 is flat and smooth, scattering of the laser light L on the back surface 4 can be prevented.
[0074]
The modified region 7 may be formed by irradiating the condensing point P with the laser beam L with the surface 22 of the wafer 2 as the laser beam incident surface. However, in this case, the transmittance of the semiconductor layer such as the active layer 25 stacked on the substrate 1 with respect to the laser light L needs to be equal to or higher than a predetermined transmittance. Further, in order to form the cutting start region inside the predetermined distance from the laser light incident surface, the Z-axis direction position of the wafer 2 in the laser processing apparatus 100 is determined in consideration of the refractive index of each semiconductor layer stacked on the substrate 1. It is necessary to determine.
[0075]
FIG. 24 is a cross-sectional view for explaining a modification of the method of manufacturing the semiconductor laser device according to the present embodiment. In this modification, a plurality of modified regions 7 are formed in the thickness direction of the substrate 1 inside the substrate 1. In order to form the modified region 7 in this way, step S111 (moving the wafer 2 in the Z-axis direction) and step S113 (forming the modified region 7) in the flowchart shown in FIG. It is good to do. Alternatively, the modified region 7 may be formed continuously in the thickness direction of the substrate 1 by simultaneously moving the wafer 2 in the Z-axis direction and forming the modified region 7.
[0076]
By forming the modified region 7 as in this modification, a cutting start region extending in the thickness direction of the substrate 1 can be formed. Accordingly, the wafer 2 can be cut with a smaller force. Furthermore, if a crack due to the modified region 7 is grown in the thickness direction of the substrate 1, the wafer 2 can be separated without requiring an external force.
[0077]
As mentioned above, although embodiment and the modification of this invention were described in detail, it cannot be overemphasized that this invention is not limited to the said embodiment and modification.
[0078]
For example, in the above-described embodiments and examples, the first conductivity type is n-type and the second conductivity type is p-type. However, the first conductivity type may be p-type and the second conductivity type may be n-type. . Of course, the stripe structure includes a structure in which a high resistance layer is embedded around the active layer.
[0079]
【The invention's effect】
As described above, in the semiconductor laser device manufacturing method and the semiconductor laser device according to the present invention, the planned cutting line 5 is formed in the modified region 7 formed by the phenomenon of multiphoton absorption inside the substrate 1 of the wafer 2. A cutting start area along the cutting start area can be formed, and the substrate 1 can be efficiently divided and cut along the cutting start area with a relatively small force. Then, the active layer 25 is cleaved along the scheduled cutting line 5 with high accuracy by cutting the substrate 1. Therefore, according to this manufacturing method, the resonance surface 35 by cleavage of the active layer 25 can be efficiently and accurately formed.
[Brief description of the drawings]
FIG. 1 is a plan view of a substrate during laser processing.
2 is a cross-sectional view taken along line II-II of the substrate shown in FIG.
FIG. 3 is a plan view of a substrate after laser processing.
4 is a cross-sectional view taken along line IV-IV of the substrate shown in FIG.
5 is a cross-sectional view taken along line VV of the substrate shown in FIG.
FIG. 6 is a plan view of a cut substrate.
FIG. 7 is a graph showing the relationship between electric field strength and crack spot size in the laser processing method used in the present embodiment.
FIG. 8 is a cross-sectional view of a substrate in a first step of a laser processing method used in the present embodiment.
FIG. 9 is a cross-sectional view of a substrate in a second step of the laser processing method used in the present embodiment.
FIG. 10 is a cross-sectional view of a substrate in a third step of the laser processing method used in the present embodiment.
FIG. 11 is a cross-sectional view of a substrate in a fourth step of the laser processing method used in the present embodiment.
FIG. 12 is a view showing a photograph of a cross section of a part of a silicon wafer cut by the laser processing method used in this embodiment.
FIG. 13 is a graph showing the relationship between the wavelength of laser light and the transmittance inside a silicon substrate in the laser processing method used in the present embodiment.
FIG. 14 is a schematic configuration diagram of a laser processing apparatus.
FIG. 15 is a perspective view showing a wafer used in the method for manufacturing a semiconductor laser device according to the embodiment.
16 is a bottom view of the wafer shown in FIG. 15. FIG.
17 is an enlarged view showing a VI-VI cross section of the wafer shown in FIG. 16;
FIG. 18 is a flowchart for explaining a manufacturing method of the semiconductor laser element according to the embodiment.
FIG. 19 is a flowchart showing a method for forming a cutting start region on a wafer using the laser processing apparatus shown in FIG. 14;
FIG. 20 is a cross-sectional view of a wafer for explaining the method of manufacturing a semiconductor laser element.
FIG. 21 is a cross-sectional view of a wafer for explaining the method of manufacturing a semiconductor laser element.
22A is a cross-sectional view of a wafer for explaining a method of manufacturing a semiconductor laser element. FIG. (B) It is a perspective view of the wafer for demonstrating the manufacturing method of a semiconductor laser element.
FIG. 23A is a perspective view showing a rod-shaped member cut into a chip shape. (B) It is a perspective view which shows the structure of the semiconductor laser element obtained through said process.
FIG. 24 is a cross-sectional view illustrating a modification of the method for manufacturing the light emitting device according to the embodiment.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Substrate, 2 ... Wafer, 4 ... Back surface, 5 ... Planned cutting line, 7 ... Modified area, 8 ... Cutting origin area, 9 ... Crack area, 11 ... Silicon wafer, 13 ... Melting process area, 19 ... Orientation flat 21 ... surface, 23 ... n-type cladding layer, 25 ... active layer, 27 ... p-type cladding layer, 29 ... cap layer, 31 ... cathode electrode, 33 ... anode electrode, 35 ... resonance surface, 37 ... rod-like member, 39 DESCRIPTION OF SYMBOLS ... Semiconductor laser element, 100 ... Laser processing apparatus, 101 ... Laser light source, 102 ... Laser light source control part, 103 ... Dichroic mirror, 105 ... Condensing lens, 107 ... Mounting stand, 109 ... X-axis stage, 111 ... Y-axis Stage 113 113 Z-axis stage 115 Stage control unit 117 Light source for observation 119 Beam splitter 121 Image sensor 123 Image forming stage 'S, 125 ... imaging data processing unit, 127 ... overall control unit, 129 ... monitor, L ... laser light, P ... converging point.

Claims (9)

A manufacturing method of a semiconductor laser device having a stripe structure in which a first conductive semiconductor layer, an active layer, and a second conductive semiconductor layer are stacked on a surface of a substrate made of a III-V compound semiconductor,
A wafer in which the first conductive type semiconductor layer, the active layer, and the second conductive type semiconductor layer are stacked on the front surface of the substrate, and electrodes are formed in regions on the front surface and the back surface, respectively, excluding the planned cutting line. A modified region by multiphoton absorption is formed only inside the substrate by aligning a condensing point with the inside of the substrate and irradiating a pulsed laser beam, and this modified region allows the longitudinal direction of the stripe structure to be A cutting start region is formed on the inner side by a predetermined distance from the laser light incident surface of the wafer along the planned cutting line extending in a direction perpendicular to the wafer, and cracks are grown from the cutting start region to the front and back surfaces of the substrate. Cutting the substrate , the first conductive type semiconductor layer, and the second conductive type semiconductor layer along the cutting start region, and cleaving the active layer,
The peak power density at the condensing point of the pulse laser beam is 1 × 10 ⁸ (W / cm ² ) or more, and the pulse width of the pulse laser beam is 1 μs or less,
A method for manufacturing a semiconductor laser device, wherein a portion of the back surface of the wafer where the electrode is not provided is the laser light incident surface.   The method for manufacturing a light-emitting element according to claim 1, wherein when the modified region is formed, a plurality of the modified regions are formed in a thickness direction of the substrate.   When forming the modified region, the modified region is formed along a plurality of the planned cutting lines, and a plurality of the modified regions are formed in a direction along each planned cutting line. 3. A method for producing a semiconductor laser device according to 2. A manufacturing method of a semiconductor laser device having a stripe structure in which a first conductive semiconductor layer, an active layer, and a second conductive semiconductor layer are stacked on a surface of a semiconductor substrate made of a III-V compound semiconductor,
The first conductive type semiconductor layer, the active layer, and the second conductive type semiconductor layer are stacked on the surface of the semiconductor substrate, and electrodes are formed in regions on the front surface and the back surface, respectively, excluding the planned cutting line. A melting processing region is formed only inside the semiconductor substrate by aligning a condensing point with the inside of the semiconductor substrate of the wafer and irradiating a pulse laser beam, and this melting processing region is orthogonal to the longitudinal direction of the stripe structure. By forming a cutting start region in a predetermined distance from the laser beam incident surface of the wafer along the planned cutting line extending in the direction to be cut, the crack is grown from the cutting start region to the front surface and the back surface of the semiconductor substrate. cleaving said active layer with said cutting the semiconductor substrate, the first conductive semiconductor layer and the second conductive semiconductor layer along the cutting start region It includes the step of,
The peak power density at the condensing point of the pulse laser beam is 1 × 10 ⁸ (W / cm ² ) or more, and the pulse width of the pulse laser beam is 1 μs or less,
A method for manufacturing a semiconductor laser device, wherein a portion of the back surface of the wafer where the electrode is not provided is the laser light incident surface.   The method for manufacturing a light-emitting element according to claim 4, wherein when forming the melt processing region, a plurality of the melt processing regions are formed in a thickness direction of the semiconductor substrate.   5. When forming the melt treatment region, the melt treatment region is formed along a plurality of the planned cutting lines, and a plurality of the melt processing regions are formed in a direction along each planned cut line. 6. A method for producing a semiconductor laser device according to 5.   The method for manufacturing a semiconductor laser device according to claim 1, wherein stress is applied to the wafer when the substrate is cut.   The method for manufacturing a semiconductor laser device according to claim 7, wherein the back surface of the substrate is flat and smooth.   When forming the cutting starting region, the cutting starting region is formed along a plurality of scheduled cutting lines, and when cutting the substrate, the substrate is formed into a plurality of rod-shaped members along the cutting starting region. The method for manufacturing a semiconductor laser device according to claim 1, wherein the plurality of rod-shaped members are cut into chips after cutting.

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