JP2003338636A - Manufacturing method of light-emitting device, light emitting diode, and semiconductor laser element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of a light-emitting device for accurately and efficiently cutting a wafer having a laminated structure, and to provide a light emitting diode and a semiconductor laser element. <P>SOLUTION: The method is characterized by comprising procures such that: a second groove 27 that reaches the substrate 1 from the p-type semiconductor layer 17b is formed along a line 5 cut for cutting the wafer 2 in a chip shape in a wafer 2 where a p-type semiconductor layer 17a made of a III-V-group compound semiconductor and an n-type semiconductor layer 17b are laminated on the surface 3 of a substrate 1; a condensing point P is focused on the inside of the substrate 1 facing the second groove 27 for being irradiated with a laser beam L; a modified region 7 formed by multiphoton absorption is formed inside the substrate 1; a cut-off origin region is formed inside the substrate 1 at a specific distance from the incident surface of the laser beam L by the modified region 7; and the wafer 2 is cut along the cut-off origin region. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a light emitting device, a light emitting diode, and a semiconductor laser device.

[0002]

Recently, in manufacturing a semiconductor light emitting device such as a semiconductor laser element or a light-emitting diode, for example, sapphire (Al ₂ O ₃₎ such as GaN on a substrate of such III-
There is a demand for a technique for accurately cutting a wafer having a laminated structure in which a semiconductor operating layer made of a group V compound semiconductor is crystal-grown.

Further, conventionally, a blade dicing method or a diamond scribe method is generally used for cutting a wafer having this laminated structure.

The blade dicing method is a method of cutting a wafer by cutting with a diamond blade or the like. On the other hand, the diamond scribing method is a method in which a scribe line is provided on the front surface of a wafer by a diamond point tool, and a knife edge is pressed against the back surface of the wafer along the scribe line to break the wafer.

For example, in Patent Document 1 and Patent Document 2,
A semiconductor light emitting device formed by combining such a blade dicing method and a diamond scribing method is disclosed.

[0006]

[Patent Document 1] Japanese Patent No. 2780618

[Patent Document 2] Japanese Unexamined Patent Publication No. 2001-156332

[0007]

However, the method of combining the blade dicing method and the diamond scribing method has the following problems. That is, when the diamond scribe method is used for a wafer having a substrate having a high hardness such as a sapphire substrate, chipping or the like is likely to occur when the wafer is broken. In addition, when the substrate is relatively thick, scribe lines must be provided on both sides of the wafer, and there is a risk that misalignment between the scribe lines provided on both sides will cause cutting defects. Therefore, when the diamond scribing method is used in combination with the blade dicing method, there arises a problem that it is difficult to accurately cut a substrate having high hardness. On the other hand, when only the blade dicing method is used, it takes a lot of time to cut a substrate having high hardness, and the blade is worn so severely that it is necessary to frequently replace the blade. Another problem that is worse.

Therefore, the present invention has been made in view of the above circumstances, and solves the above problems.
An object of the present invention is to provide a method for manufacturing a light emitting device, a light emitting diode, and a semiconductor laser device capable of accurately and efficiently cutting a wafer having a laminated structure.

[0009]

In order to achieve the above object, a method for manufacturing a light emitting device according to the present invention comprises a wafer on which a semiconductor layer made of a III-V compound semiconductor is laminated on the surface of a substrate. By forming a groove that reaches the substrate from the semiconductor layer along the planned cutting line for cutting the wafer into chips, and irradiating laser light by aligning the focusing point inside the substrate facing the groove, multiphoton absorption The method further comprises the steps of forming a modified region, forming a cutting start region within a predetermined distance from the laser light incident surface of the substrate by the modified region, and cutting the wafer along the cutting start region.

According to this method of manufacturing a light emitting device, first,
By forming a groove in the wafer that extends from the semiconductor layer to the substrate, the semiconductor layer can be processed into a desired shape and dimension. Then, the modified starting region formed by the phenomenon of multiphoton absorption inside the substrate of the wafer can form the cutting starting region along the planned cutting line, and the substrate is relatively small along the cutting starting region. Can be cut by force. Therefore, according to this manufacturing method, a wafer having a laminated structure can be cut with high accuracy and efficiency.

The semiconductor layers laminated on the surface of the substrate include those provided in close contact with the substrate and those provided with a gap from the substrate. Examples thereof include a semiconductor operation layer formed by crystal growth on a substrate, and a semiconductor layer fixed on the substrate after being stacked separately from the substrate. The inside of the substrate is meant to include the surface of the substrate on which the semiconductor layer is provided. Further, the condensing point is a place where the laser light 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.

In the above-described method for manufacturing a light emitting device according to the present invention, it is preferable that the bottom surface of the groove is the laser light incident surface when the substrate is irradiated with the laser light. According to this manufacturing method, when the substrate is irradiated with the laser light, the planned cutting line can be easily recognized, and the laser light can be accurately irradiated in accordance with the position of the groove.

Further, in the above-described method for manufacturing a light emitting device according to the present invention, when the groove is formed on the wafer, it is preferable that the bottom surface of the groove is flat and has a smooth surface. This makes it possible to prevent the laser light from being scattered on the bottom surface of the groove.

Further, in the above-described method for manufacturing a light emitting device according to the present invention, when the modified region is formed, the width of the modified region in the direction intersecting the groove is narrower than the width of the groove in the direction. It is preferably formed. According to this manufacturing method, the modified region can be formed by entering the laser light into a range narrower than the width of the groove, so that the semiconductor layer around the groove can be prevented from being damaged by the laser light.

Further, in the above-described method for manufacturing a light emitting device according to the present invention, it is preferable that the back surface of the substrate be the laser light incident surface when the substrate is irradiated with the laser light. According to this manufacturing method, even if the bottom surface of the groove is not suitable for the incidence of laser light, the cutting start region can be formed by the modified region inside the substrate of the wafer. And it is more preferable that the back surface of the substrate is flat and smooth.
Thereby, the scattering of the laser light on the back surface can be prevented.

The light emitting diode according to the present invention is a wafer having a substrate and a first conductivity type semiconductor layer and a second conductivity type semiconductor layer which are made of a III-V group compound semiconductor and are laminated on the surface of the substrate. Is a light emitting diode formed by cutting the substrate in a chip shape along a line to be cut, the laser reaching the groove from the second conductivity type semiconductor layer to the substrate and the converging point inside the substrate facing the groove. It is characterized in that a modified region by multiphoton absorption is formed by irradiation with light, and the modified region is cut by a cutting start region formed inside a predetermined distance from the laser light incident surface of the substrate. .

According to this light emitting diode, the first conductive type semiconductor layer and the second conductive type semiconductor layer have desired shape and size by the groove reaching the substrate from the second conductive type semiconductor layer in the wafer. Then, it is formed with a modified region formed by the phenomenon of multiphoton absorption inside the substrate of the wafer,
The cutting start region along the planned cutting line breaks the substrate along the cutting start region with a relatively small force.
Therefore, it is possible to provide a light emitting diode formed by accurately and efficiently cutting a wafer having a laminated structure.

The semiconductor laser device according to the present invention is
A substrate, a first-conductivity-type semiconductor layer made of a III-V group compound semiconductor and laminated on the surface of the substrate, an active layer, and a second layer
A semiconductor laser device formed by cutting a wafer having a conductive type semiconductor layer into chips along a planned cutting line, the groove reaching the substrate from the second conductive type semiconductor layer, and the substrate facing the groove. Laser light is radiated with the condensing point aligned inside to form a modified region by multiphoton absorption,
It is characterized in that the modified region is cut by the cutting start region formed inside the laser light incident surface of the substrate by a predetermined distance.

According to this semiconductor laser device, the first groove is formed on the wafer from the second conductivity type semiconductor layer to the substrate.
The conductive type semiconductor layer, the active layer, and the second conductive type semiconductor layer have desired shapes and dimensions, and a resonance plane for laser oscillation is formed in the active layer. Then, the substrate is cut along the cutting starting region by a relatively small force by the cutting starting region along the planned cutting line formed by the modified region formed by the phenomenon of multiphoton absorption inside the substrate of the wafer. Be disconnected. Therefore, it is possible to provide a semiconductor laser device formed by accurately and efficiently cutting a wafer having a laminated structure.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION Preferred embodiments of the present invention will be described in detail below with reference to the drawings. In the method for manufacturing a light emitting device according to this embodiment, the inside of the substrate of the wafer is irradiated with laser light to form a modified region by multiphoton absorption. Therefore, this laser processing method, in particular, multiphoton absorption will be described first.

When the photon energy hν is smaller than the absorption band gap E _G of the material, it becomes optically transparent. Therefore, the condition under which absorption occurs in the material is hν> E _G. However, even if it is optically transparent, if the intensity of the laser light is made extremely high, the condition of nhν> E _G (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 light is determined by the peak power density (W / cm ² ) at the condensing point of the laser light. For example, the multiphoton is generated under the condition that the peak power density is 1 × 10 ⁸ (W / cm ² ) or more. Absorption occurs. The peak power density is (energy per pulse of laser light at the condensing point) ÷
It is calculated by (beam spot cross-sectional area of laser light × pulse width). Further, in the case of a continuous wave, the intensity of the laser light is determined by the electric field intensity (W / cm ² ) at the condensing point of the laser light.

The principle of laser processing utilizing such multiphoton absorption will be described with reference to FIGS. 1 is a plan view of the substrate 1 during laser processing, and FIG. 2 is FIG.
4 is a sectional view of the substrate 1 taken along line II-II in FIG. 3, FIG. 3 is a plan view of the substrate 1 after laser processing, and FIG. 4 is a sectional view taken along line IV-IV of the substrate 1 shown in FIG. FIG. 5 and FIG.
5 is a cross-sectional view of the substrate 1 shown in FIG. 6 along the line V-V, and FIG. 6 is a plan view of the cut substrate 1.

As shown in FIGS. 1 and 2, the substrate 1 includes
A desired planned cutting line 5 is set. The planned cutting line 5 is an imaginary line extending linearly, and is a boundary line between the chips when the wafer is divided into a plurality of chips in this embodiment. The line 5 may be actually drawn on the wafer to form the planned cutting line 5. In the present embodiment, the modified region 7 is formed by irradiating the laser light L after aligning the focusing point P inside the substrate 1 under the condition that multiphoton absorption occurs. The converging point P is a portion where the laser light L is condensed.

By moving the laser beam L relatively along the planned cutting line 5 (that is, along the direction of arrow A), the focal point P is moved along the planned cutting line 5. As a result, as shown in FIG. 3 to FIG.
Are 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. In this laser processing method, the substrate 1 does not heat the substrate 1 by absorbing the laser light L to form the modified region 7. The laser light L is transmitted through the substrate 1 to cause multiphoton absorption inside the substrate 1 to form the modified region 7. Therefore, the laser light L is hardly absorbed on the surface 3 of the substrate 1, so that the surface 3 of the substrate 1 is not melted.

In the cutting of the substrate 1, if there is a starting point at the cutting position, the substrate 1 is broken from the starting point, so that the substrate 1 can be cut with a relatively small force as shown in FIG. Therefore, it is possible to efficiently cut the substrate 1 without causing unnecessary cracks such as chipping on the surface 3 of the substrate 1.

There are two possible ways of cutting the substrate starting from the cutting starting area. One is that after the cutting starting area is formed, an artificial force is applied to the substrate,
This is a case where the substrate is broken and the substrate is cut with the cutting start region as the starting point. This is cutting, for example, when the thickness of the substrate is large. Artificial force is applied, for example,
It is to apply a bending stress or a shear stress to the substrate along the cutting starting region of the substrate, or to generate a thermal stress by giving a temperature difference to the substrate. The other one is a case where the cutting start region is formed, so that the cutting start region is a starting point and is naturally cracked in the cross-sectional direction (thickness direction) of the substrate, resulting in the cutting of the substrate. This can be achieved, for example, by forming the cutting start region by one row of the modified regions when the thickness of the substrate is small, and by forming a plurality of rows in the thickness direction when the thickness of the substrate is large. This is possible because the cutting start region is formed by the modified region thus formed. In addition, even if this naturally breaks,
The crack does not advance to the surface of the part corresponding to the part where the cutting start region is not formed, and only the part corresponding to the part where the cutting start region is formed can be cleaved, so the cleaving is well controlled. be able to. In recent years, the thickness of substrates such as wafer substrates has tended to decrease.
Such a cleaving method with good controllability is very effective.

The modified regions formed by multiphoton absorption in this embodiment include the following (1) to (3).

(1) When the modified region is a crack region containing one or a plurality of cracks: For example, a 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
Laser light is irradiated under the condition of (W / cm ² ) or more and the 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 called 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. The upper limit of the electric field strength is, for example, 1 × 10 ¹² (W / cm ² ). The pulse width is preferably 1 ns to 200 ns, for example.

The inventor of the present invention experimentally determined the relationship between the electric field strength and the crack size. The experimental conditions are as follows. (A) Substrate: Pyrex (registered trademark) glass (thickness 7
00 μm) (B) Laser light source: Semiconductor laser pumped Nd: YAG laser Wavelength: 1064 nm Laser light spot cross-sectional area: 3.14 × 10 ⁻⁸ cm ² Oscillation form: Q switch pulse repetition frequency: 100 kHz Pulse width: 30 ns Output: output <1 mJ / pulse laser light quality: TEM ₀₀ Polarization characteristics: Linearly polarized light (C) Condensing lens Laser light wavelength transmittance: 60% (D) Moving speed of the mounting table on which the substrate is mounted: 100 mm
/ Second

The laser beam quality TEM ₀₀ means that the laser beam quality is high and the laser beam can be focused up to the wavelength of the laser beam.

FIG. 7 is a graph showing the results of the above experiment. The horizontal axis represents the peak power density. Since the laser light is pulsed laser light, the electric field strength is represented by the peak power density. The vertical axis represents the size of a crack portion (crack spot) formed inside the substrate by one pulse of laser light. The crack spots gather to form a crack area. The size of the crack spot is the size of the portion having the maximum length in the shape of the crack spot. The data indicated by black circles in the graph refer to the case where the condenser lens (C) has a magnification of 100 and a numerical aperture (NA) of 0.80. On the other hand, the data indicated by the white circles in the graph are for the condenser lens (C).
Is 50 times and the numerical aperture (NA) is 0.55. From the peak power density of about 10 ¹¹ (W / cm ² ), it can be seen that crack spots occur inside the substrate, and the crack spot also increases as the peak power density increases.

Next, in the above laser processing method,
The mechanism of cutting the substrate by forming the crack region will be described with reference to FIGS. As shown in FIG.
Under the condition that multiphoton absorption occurs, the focusing point P is aligned with the inside of the substrate 1 and the substrate 1 is irradiated with the laser light L to form the crack region 9 inside along the planned cutting line. The crack region 9 is a region including one or a plurality of cracks. The crack starting region is formed by the crack region 9. Figure 9
As shown in FIG.
The crack grows further (starting from the cutting starting area),
As shown in FIG. 10, cracks are generated on the front surface 3 and the back surface 2 of the substrate 1.
1 is reached, and the substrate 1 is broken as shown in FIG. 11, whereby the substrate 1 is cut. The cracks reaching the front surface and the back surface of the substrate may grow naturally, or they may grow when a force is applied to the substrate.

(2) When the modified region is a melt-processed region A focusing point is set inside a substrate made of a semiconductor material such as silicon, and the electric field strength at the focusing point is 1 × 1.
Irradiation with laser light is performed under the condition of 0 ⁸ (W / cm ² ) or more and 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-processed region is a region that has been once melted and then re-solidified, a region that is just in a molten state, or a region that is in a state where it is re-solidified from the molten state, and can also be referred to as a phase-changed region or a region in which the crystal structure is changed. Further, the melt processed region is a single crystal structure, an amorphous structure,
It can also be said that in a polycrystalline structure, one structure is changed to another structure. That is, for example, a region in which a single crystal structure is changed to an amorphous structure, a region in which a single crystal structure is changed to a polycrystalline structure, or a region in which a single crystal structure is changed to a structure including an amorphous structure and a polycrystalline structure is meant. To do. When the substrate has a silicon single crystal structure, the melt-processed region has, for example, an amorphous silicon structure. The upper limit of the electric field strength is, for example, 1 × 10 ¹² (W / cm ² ). The pulse width is preferably 1 ns to 200 ns, for example. Further, not only silicon but also sapphire or the like can form the above-mentioned melt-processed region.

The present inventor has confirmed by 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
(B) Laser light source: Semiconductor laser pumped Nd: YAG laser wavelength: 1064 nm Laser light spot cross-sectional area: 3.14 × 10 ⁻⁸ cm ² Oscillation form: Q switch pulse repetition frequency: 100 kHz Pulse width: 30 ns Output: 20 μJ / Pulse laser light quality: TEM ₀₀ Polarization characteristic: Linearly polarized light (C) Condensing lens Magnification: 50 times A. : 0.55 Transmittance for laser light wavelength: 60% (D) Moving speed of mounting table on which substrate is mounted: 100 mm
/ Second

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-processed region 13 formed under the above conditions is 100 μm.
It is about m.

It will be described that the melt-processed region 13 is formed by multiphoton absorption. FIG. 13 is a graph showing the relationship between the wavelength of laser light and the transmittance inside the silicon substrate. However, the reflection components on the front surface side and the back surface side of the silicon substrate are removed, and the transmittance of only the inside is shown. Silicon substrate thickness t is 50μm, 100μm, 200μ
The above relationship was shown for each of m, 500 μm, and 1000 μm.

For example, when the wavelength of the Nd: YAG laser is 1064 nm, the thickness of the silicon substrate is 500 μm.
If it is less than m, the laser light will be 80 inside the silicon substrate.
It can be seen that more than% is transmitted. Since the thickness of the silicon wafer 11 shown in FIG. 12 is 350 μm, when the melt-processed region 13 by multiphoton absorption is formed near the center of the silicon wafer, it is formed 175 μm from the surface. In this case, the transmittance is 90% or more with reference to a silicon wafer having a thickness of 200 μm. Therefore, laser light is hardly absorbed inside the silicon wafer 11, and most of it is transmitted. This does not mean that the laser light is absorbed inside the silicon wafer 11 and the melt-processed region 13 is formed inside the silicon wafer 11 (that is, the melt-processed region is formed by normal heating with laser light). This means that the melt-processed region 13 is formed by multiphoton absorption.

The silicon wafer is cracked in the cross-sectional direction starting from the cutting start region formed in the melt-processed region, and the crack reaches the front and back surfaces of the silicon wafer. Be disconnected. The crack reaching the front surface and the back surface of the silicon wafer may grow naturally, 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 surface and the back surface of the silicon wafer, when the crack grows from a molten state in the melting processing region forming the cutting start region, and when the cutting start region There is also a case where cracks grow when the melt-processed region forming the is solidified from a molten state. However, in both cases, the melt-processed region is formed only inside the silicon wafer, and the cut surface after the cutting is shown in FIG.
As shown in FIG. 2, the melt-processed region is formed only inside.
When the cutting start region is formed in the substrate by the melt processing region, unnecessary cracks deviating from the cutting start region line are unlikely to occur at the time of cutting, which facilitates cutting control.

(3) When the modified region is a refractive index changing region: A focusing point is set inside a substrate made of, for example, glass, and the electric field strength at the focusing point is 1 × 10 ⁸ (W / cm ² ).
Laser light is emitted under the above conditions and a pulse width of 1 ns or less. When the pulse width is made extremely short and multiphoton absorption is caused inside the substrate, the energy due to the multiphoton absorption is not converted into thermal energy, and the ionic valence change, crystallization or polarization orientation is generated inside the substrate. The permanent structural change of is induced to form the refractive index change region. The upper limit of the electric field strength is, for example, 1 × 10 ¹² (W / cm ² ). The pulse width is, for example, preferably 1 ns or less, more preferably 1 ps or less.

The cases (1) to (3) have been described above as the modified regions formed by multiphoton absorption. The cutting origin region is set as follows in consideration of the crystal structure of the substrate and the cleavability thereof. If it is formed, it becomes possible to cut the substrate with a smaller force and more accurately with the cutting start region as the starting point.

That is, in the case of a substrate made of a single crystal semiconductor having a diamond structure such as silicon, the starting point of cutting is in the direction along the (111) plane (first cleavage plane) or the (110) plane (second cleavage plane). Are preferably formed. Also, G
In the case of a substrate made of a III-V group compound semiconductor having a zinc blende type structure such as aAs, it is preferable to form the cutting start region in the direction along the (110) plane. Further, in the case of a substrate having a hexagonal crystal structure such as sapphire, (0
The main surface is the (001) plane (C plane) and the (1120) plane (A
It is preferable to form the cutting start region in a direction along the (plane) or the (1100) plane (M plane).

The direction in which the above-mentioned cutting starting region should be formed (for example, (111) in a single crystal silicon substrate)
If the orientation flat (described later) is formed on the substrate along the direction (along the surface) or in the direction orthogonal to the direction in which the cutting start area should be formed, the cutting start area can be easily set by using the orientation flat as a reference. Moreover, it becomes possible to form the substrate accurately.

Next, a laser processing apparatus used in the above laser processing method will be described with reference to FIG. FIG. 14 is a schematic configuration diagram of the laser processing apparatus 100.

The laser processing apparatus 100 includes a laser light source 101 for generating a laser light L, a laser light source controller 102 for controlling the laser light source 101 to adjust the output and pulse width of the laser light L, and a laser light L. A dichroic mirror 103 which has a reflection function and is arranged to change the direction of the optical axis of the laser light L by 90 °, and a condenser lens 105 which condenses the laser light L reflected by the dichroic mirror 103. A mounting table 107 on which the substrate 1 irradiated with the laser light L condensed by the condensing lens 105 is mounted;
An X-axis stage 109 for moving the mounting table 107 in the X-axis direction, a Y-axis stage 111 for moving the mounting table 107 in the Y-axis direction orthogonal to the X-axis direction, and the mounting table 1
A Z-axis stage 113 for moving the 07 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, 113.

The movement of the condensing point P in the X (Y) axis direction is
The substrate 1 is moved to the X (Y) axis stage 109 (111) by the X (Y) axis stage 109 (111).
It is performed by moving in the (Y) axis direction. Since the Z-axis direction is the direction orthogonal to the surface 3 of the substrate 1, it is the direction of the focal depth of the laser light L incident on the substrate 1. Therefore, Z
By moving the axis stage 113 in the Z-axis direction,
The condensing point P of the laser light L can be aligned inside the substrate 1. Thereby, the condensing point P can be aligned at a desired position inside the predetermined distance from the surface 3 of the substrate 1 which is the laser light incident surface.

The laser light source 101 is an Nd: YAG laser which emits pulsed laser light. Other lasers that can be used for the laser light source 101 include Nd: YVO
_{There are 4} 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 it can cause multiphoton absorption.

The laser processing apparatus 100 further includes a mounting table 1
The observation light source 117 for generating visible light for illuminating the substrate 1 placed on 07 with visible light, and the beam for visible light arranged on the same optical axis as the dichroic mirror 103 and the condenser lens 105. And a splitter 119. The dichroic mirror 103 is arranged between the beam splitter 119 and the condenser lens 105.
The beam splitter 119 has a function of reflecting approximately 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 °. The visible light emitted from the observation light source 117 is reflected by the beam splitter 119.
About half of the reflected light is transmitted through the dichroic mirror 103 and the condenser lens 105, and illuminates the surface 3 of the substrate 1 including the planned cutting line 5 and the like. When the substrate 1 is mounted on the mounting table 107 such that the back surface of the substrate 1 is on the condenser lens 105 side, the “front surface” here is of course the “back surface”.

The laser processing apparatus 100 further includes the image pickup device 12 arranged on the same optical axis as the beam splitter 119, the dichroic mirror 103 and the condenser lens 105.
1 and the imaging lens 123. The image sensor 121 is, for example, a CCD camera. The reflected light of visible light that illuminates the surface 3 including the planned cutting line 5 and the like passes through the condenser lens 105, the dichroic mirror 103, and the beam splitter 119, is imaged by the imaging lens 123, and is imaged by the imaging element 121. And becomes imaging data.

The laser processing apparatus 100 further includes an imaging data processing unit 125 to which the imaging data output from the image sensor 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 surface 3 of the substrate 1 based on the imaging data. Based on this focus data, the stage control unit 115 determines that the Z-axis stage 113
Is controlled so that the visible light is focused on the surface 3 of the substrate 1. Therefore, the imaging data processing unit 12
5 functions as an autofocus unit. Also,
The imaged data processing unit 125 calculates image data such as an enlarged image of the surface 3 based on the imaged data. This image data is sent to the overall control unit 127, various processing is performed in the overall control unit 127, and sent to the monitor 129. As a result, an enlarged image or the like is displayed on the monitor 129.

The overall controller 127 includes the stage controller 1
Data from the image pickup device 15, image data from the image pickup data processing unit 125, and the like are input, and the laser light source control unit 102, the observation light source 117, and the stage control unit 115 are controlled based on these data, thereby the laser processing apparatus. Control 100 as a whole. Therefore, the overall control unit 127 functions as a computer unit.

Next, a method of manufacturing the light emitting element according to the present embodiment using the above laser processing method and laser processing apparatus 100 will be described. FIG. 15 is a perspective view showing a wafer used in the method for manufacturing a light emitting device according to this embodiment. 16 is a plan view of the wafer shown in FIG. 17 is an enlarged view showing a VI-VI section and a VII-VII section of the wafer shown in FIG. In this embodiment, a method of manufacturing a light emitting diode as a light emitting element will be described.

Referring to FIGS. 15-17, the wafer 2
Has a substantially disc shape, and has an orientation flat (hereinafter referred to as “OF”) 19. In this embodiment, the wafer 2 is a substrate 1 made of sapphire.
An n-type semiconductor layer 17a which is a first conductivity type semiconductor layer laminated on the surface 3 of the substrate 1 and a p-type semiconductor layer 17 which is a second conductivity type semiconductor layer laminated on the n-type semiconductor layer 17a.
and b. The n-type semiconductor layer 17a and the p-type semiconductor layer 17b are made of a III-V group compound semiconductor such as GaN and are pn-junctioned to each other. If the substrate 1 is thick, it becomes difficult to dissipate heat generated in the n-type semiconductor layer 17a and the p-type semiconductor layer 17b, so the thickness of the substrate 1 is 5
0 μm to 200 μm, preferably 50 μm to 150 μm
Is. In addition, the n-type semiconductor layer 17a and the p-type semiconductor layer 1
The thickness of 7b is, for example, 6 μm and 1 μm, respectively.

Further, referring to FIG. 16, a planned cutting line 5 is set on the wafer 2. Cutting line 5
Are supposed to cut the wafer 2 into chips.
In the present embodiment, a plurality of planned cutting lines 5 are set in a direction parallel to the longitudinal direction of the OF 19 and a direction perpendicular to the OF 19. In addition, as described above, OF19
Is the direction along the cleavage plane of the sapphire substrate 1,
Alternatively, it is formed in a direction orthogonal to the direction along the cleavage plane. That is, at least one direction of the planned cutting line 5 is the (1120) plane (A
Plane) or (1100) plane (M plane). The interval between the planned cutting lines 5 adjacent to each other is, for example, about 2 mm.

18 and 19 are flow charts for explaining the method of manufacturing the light emitting device according to this embodiment. 20 to 24 are cross-sectional views of the wafer 2 for explaining the method for manufacturing the light emitting device.

Referring to FIG. 18, first, the expand tape 23 is attached to the back surface of the wafer 2 (that is, the back surface 21 of the substrate 1) (S1, FIG. 20). Expand tape 2
3 is made of, for example, a material that expands by heating, and is used for separating the wafer 2 into chips in a later process.

Subsequently, the first groove 25 is formed by etching the surface of the wafer 2 on the p-type semiconductor layer 17b side along the planned cutting line 5 shown in FIG. 16 (S).
3, FIG. 21). At this time, the first groove 25 is formed such that the depth of the first groove 25 is the depth from the p-type semiconductor layer 17b to the middle of the n-type semiconductor layer 17a. Also, the groove 25
Is formed so that the p-type semiconductor layer 17b has a desired shape and dimension, and is electrically connected to the n-type semiconductor layer 17a on the bottom surface of the groove 25 after separating the wafer 2 into chips. It is formed so that a space for providing an electrode can be secured.

Then, by etching the bottom surface of the first groove 25 of the wafer 2 along the planned cutting line 5,
The second groove 27 is formed (S5, FIG. 22). At this time,
The second groove 27 is formed so that the second groove 27 reaches the surface 3 of the substrate 1. By forming in this way,
The surface 3 of the substrate 1 is exposed at the bottom surface of the second groove 27. Further, at this time, it is preferable that the bottom surface of the second groove 27 is formed to be flat and smooth. This is because in the subsequent step, the bottom surface of the second groove 27 is used as the laser light incident surface to irradiate the laser light into the inside of the substrate 1. However, if the bottom surface of the second groove 27 is rough, the laser light is scattered at the bottom surface. This is because the laser light incident on the inside of the substrate 1 does not have an appropriate intensity.

Although there are wet etching and dry etching as the etching method, any of them may be used when forming the first groove 25 and the second groove 27. Examples of wet etching include etching with a mixed acid of phosphoric acid and sulfuric acid. As the dry etching, for example, reactive ion etching (RIE),
Examples include reactive ion beam etching (RIB) and ion milling. Further, when forming the first groove 25 and the second groove 27, for example, blade dicing may be used instead of etching.

Then, the second substrate is placed inside the substrate 1 of the wafer 2.
A starting point region for cutting is formed along the groove 27 of FIG.
3). That is, the modified region 7 is formed inside the substrate 1 by irradiating the condensing point P inside the substrate 1 with the laser light L using the bottom surface of the second groove 27 as the laser light incident surface. The modified region 7 becomes a cutting start region when the wafer 2 is cut.

Here, FIG. 19 is a flow chart showing a method of forming a cutting start region on the wafer 2 by using the laser processing apparatus 100 shown in FIG. In the present embodiment, the wafer 2 is arranged on the mounting table 107 of the laser processing apparatus 100 such that the surface of the wafer 2 on the p-type semiconductor layer 17b side faces the condenser lens 105. That is, the laser light L is incident from the p-type semiconductor layer 17b side of the wafer 2.

Referring to FIGS. 14 and 19, first, the light absorption characteristics of the substrate 1 are measured by a spectrophotometer or the like (not shown). Based on the measurement result, the laser light source 101 that emits the laser light L having a wavelength transparent to the substrate 1 or a wavelength with little absorption is selected (S101). Since the laser light L is emitted from the p-type semiconductor layer 17b side of the wafer 2, even if the back surface 21 of the wafer 2 is provided with, for example, a light-shielding electrode or the like, laser processing is performed. There is nothing that hinders you.

Then, the amount of movement of the wafer 2 in the Z-axis direction is determined in consideration of the thickness, material, refractive index, etc. of the substrate 1 (S103). This is because the surface 3 of the substrate 1 (that is, the bottom surface of the second groove 27) is aligned with the focusing point P of the laser light L at a desired position inside the surface 3 of the substrate 1 by a predetermined distance.
Wafer 2 based on the condensing point P of the laser light L located at
Is the amount of movement in the Z-axis direction. This movement amount is the total control unit 1
27 is input.

The wafer 2 is mounted on the mounting table 107 of the laser processing apparatus 100 so that the surface of the wafer 2 on the p-type semiconductor layer 17b side faces the condensing lens 105 side. Then, visible light is generated from the observation light source 117 to illuminate the surface of the wafer 2 (S105). The bottom surface of the second groove 27 on the surface of the illuminated wafer 2 is imaged by the imaging element 121. The image data captured by the image sensor 121 is sent to the image data processing unit 125. Based on this imaged data, the imaged data processing unit 125 calculates focus data such that the focus of the visible light of the observation light source 117 is located on the bottom surface of the second groove 27 of the wafer 2 (S107).

This focus data is sent to the stage controller 115. The stage control unit 115 moves the Z-axis stage 113 in the Z-axis direction based on this focus data (S109). As a result, the focus of visible light from the observation light source 117 is located on the bottom surface of the second groove 27 of the wafer 2. In addition, the imaging data processing unit 125, based on the imaging data,
Enlarged image data of the surface of the wafer 2 including the second groove 27 is calculated. This magnified image data is sent to the monitor 129 via the overall control unit 127, whereby the magnified image near the second groove 27 is displayed on the monitor 129.

In step S10, the overall control unit 127 is set in advance.
The movement amount data determined in 3 is input, and the movement amount data is sent to the stage control unit 115. Based on this movement amount data, the stage controller 115 causes the Z-axis stage 113 to move the wafer 2 in the Z-axis direction so that the position of the focus point P of the laser light L is inside the surface 3 of the substrate 1 by a predetermined distance. It is moved (S111).

Then, the laser light L from the laser light source 101
Is generated to irradiate the bottom surface of the second groove 27 of the wafer 2 with the laser light L. Since the condensing point P of the laser light L is located inside the substrate 1, the modified region 7 is formed only inside the substrate 1. At this time, the laser light L is applied to the second groove 2
The width of the modified region 7 in the direction crossing the longitudinal direction of the second groove 27 is smaller than the width of the second groove 27.
It is preferable to form the width narrower than the width in the direction. In order to make the laser light L enter in this way, the refractive index of the laser light L on the bottom surface of the second groove 27, the second groove 27
, And the position of the condensing point P inside the substrate 1 must be adjusted to each other.

Then, the X-axis stage 109 and the Y-axis stage 111 are moved along the second groove 27 to make the second
A plurality of modified regions 7 are formed along the groove 27, or are continuously formed in the longitudinal direction of the second groove 27, and a cutting start region along the planned cutting line 5 is formed inside the substrate 1. (S113).

Here, referring to FIG. 18 again, after the cutting start region is formed on the substrate 1 of the wafer 2, the wafer 2 is cut into a plurality of chips along the cutting start region (S9,
Figure 24). That is, the expanding tape 23 is stretched in a direction parallel to the back surface 21 of the wafer 2 to thereby obtain the substrate 1
Wafer 2 starting from the cutting start region formed inside the wafer
Is cut and divided into a plurality of chips. Thus
p between the n-type semiconductor layer 17a and the p-type semiconductor layer 17b
A light emitting diode 31 having an n-junction is formed.

As described above, in the method for manufacturing a light emitting device and the light emitting diode according to this embodiment, first, the first groove 25 and the second groove 27 which reach the substrate 1 from the p-type semiconductor layer 17b on the wafer 2 are formed. Are formed, the n-type semiconductor layer 17a and the p-type semiconductor layer 17b are processed into desired shapes and dimensions. Then, a cutting start region along the planned cutting line 5 is formed by the modified region 7 formed inside the substrate 1 of the wafer 2 by a phenomenon called multiphoton absorption, and the substrate 1 is cut along the cutting start region. It is cut by breaking with a relatively small force such as the expanding tape 23. Therefore, according to this manufacturing method and the light emitting diode, n
The wafer 2 having a laminated structure such as the type semiconductor layer 17a and the p-type semiconductor layer 17b can be cut with high precision and efficiency.

Further, when only the blade dicing method is used for cutting the wafer, a large-scale cleaning step for cleaning the wafer being cut is required, and large equipment is required. On the other hand, according to the method for manufacturing a light emitting element according to the present embodiment, most of the thickness of the wafer 2 is cut by the cutting start region, so that such a cleaning step is not necessary and the light emitting element is manufactured. Equipment can be simplified.

Further, in the method of manufacturing the light emitting device according to this embodiment, when the substrate 1 is irradiated with the laser light L, the bottom surface of the second groove 27 is used as the laser light incident surface. According to this manufacturing method, when the substrate 1 is irradiated with the laser light L,
The expected cutting line 5 on the wafer 2 can be easily recognized, and the laser beam L is applied to the second groove 27.
Irradiation can be performed accurately according to the position of.

Further, in the method of manufacturing the light emitting device according to this embodiment, when the second groove 27 is formed in the wafer 2, it is preferable that the bottom surface of the second groove 27 is flat and has a smooth surface. . Thereby, when the bottom surface of the second groove 27 is used as the laser light incident surface, the scattering of the laser light L on the bottom surface of the second groove 27 can be prevented.

In the method of manufacturing the light emitting device according to this embodiment, the second groove 2 is formed when the modified region 7 is formed.
The width of the modified region 7 in the direction intersecting the longitudinal direction of 7 is
The groove 27 is formed to be narrower than the width in that direction. According to this manufacturing method, the modified region 7 can be formed by making the laser light L enter a range narrower than the width of the second groove 27, so that the n-type semiconductor layer 17a around the second groove 27 is formed. It is possible to prevent damage by the laser light L.

The modified region 7 may be formed by irradiating the condensing point P with the laser light L with the back surface 21 of the substrate 1 as the laser light incident surface. In this way, even if the bottom surface of the second groove 27 is not suitable for the incidence of the laser light L due to a rough bottom surface or the like, the cutting start region is formed inside the substrate 1 of the wafer 2 by the modified region 7. Can be formed. As described above, the surface of the substrate 1 on which the laser light L is incident is preferably flat and smooth, but the back surface 21 of the substrate 1 is more preferable than the bottom surface of the relatively narrow second groove 27. It may be flat and easy to form on a smooth surface. In such a case, if the laser beam L is incident after the back surface 21 of the substrate 1 is polished, for example, the cutting start region can be easily formed. When the laser light L is incident from the back surface 21 of the substrate 1 as described above, the expanding tape 23 may be attached to the surface of the wafer 2 on the p-type semiconductor layer 17b side.

FIG. 25 is a sectional view for explaining a modification of the method for manufacturing the light emitting device according to the present embodiment. In this modification, a plurality of modified regions 7 are formed inside the substrate 1 in the thickness direction of the substrate 1. To form the modified region 7 in this way, step S111 (moving the wafer in the Z-axis direction) and step S1 of the flowchart shown in FIG. 19 are performed.
13 (formation of the modified region) may be alternately performed a plurality of times.
Alternatively, the modified region 7 may be formed continuously in the thickness direction of the substrate 1 by moving the wafer in the Z-axis direction and forming the modified region at the same time.

By forming the modified region 7 as in this modification, it is possible to form the cutting start region extending in the thickness direction of the substrate 1. Therefore, the wafer 2 can be cut with a smaller force. Furthermore, if a crack is formed by the modified region 7 in the thickness direction of the substrate 1, the wafer 2 can be separated without the need for external force.

FIG. 26 is a sectional view for explaining another modification of the method for manufacturing the light emitting device according to the present embodiment. In this modification, the groove 28 is formed in the wafer 2. This groove 28
And the first groove 25 and the second groove 27 described above are different in that (1) the depth of the groove is formed deeper than the surface 3 of the substrate 1, and (2) the first groove. 25 and the second groove 2
It is formed in one step instead of two steps as in No. 7. The groove formed on the wafer 2 may have such a shape, and the same effect as that of the above-described embodiment can be obtained.

27 and 28 are cross-sectional views for explaining another modification of the method for manufacturing the light emitting device according to the present embodiment. In this modification, a method of manufacturing a semiconductor laser as a light emitting element will be described.

Referring to FIG. 27, a wafer 2a used in this modification is a substrate 1 made of sapphire and a substrate 1 made of sapphire.
N-type semiconductor layer 33a that is a first-conductivity-type semiconductor layer laminated on the surface 3 of the active layer 33, an active layer 33b that is laminated on the n-type semiconductor layer 33a, and a second-conductivity type layer that is laminated on the active layer 33b. And a p-type semiconductor layer 33c which is a semiconductor layer.
In this modification, the n-type semiconductor layer 33a and the active layer 33 are formed.
The b and p-type semiconductor layers 33c are made of, for example, II such as GaN.
It is made of a group IV compound semiconductor and constitutes a quantum well structure. In addition, the wafer 2a in the present modification is shown in FIG.
And has the same outer shape as the wafer 2 of the above embodiment shown in FIG.

In the method of manufacturing the light emitting device according to this modification,
First, the expand tape 23 is formed on the back surface 21 of the wafer 2a.
Paste. Then, the groove 28 is formed on the surface of the wafer 2a on the p-type semiconductor layer 33c side. At this time, the groove 28 is formed along the cutting line 5 (see FIG. 16) along with the p-type semiconductor layer 33c.
To reach the substrate 1. In this modification, the groove 28 is formed deeper than the surface 3 of the substrate 1. At this time, the sidewall of the groove 28 forms the resonance surface 35 in the active layer 33b. The resonance surface 35 is the active layer 33b.
Are formed on both sides of, and these two surfaces face each other.

Subsequently, the modified region 7 is formed by irradiating the condensing point P inside the substrate 1 with the laser light L with the bottom surface of the groove 28 as the laser light incident surface. Then, while forming the modified region 7, the focal point P is formed along the longitudinal direction of the groove 28.
By moving the, a starting point region for cutting is formed inside the substrate 1. Then, as shown in FIG. 28, by expanding the expanding tape 23, the wafer 2a is cut into chips along the cutting start region to obtain the semiconductor laser element 37.

The semiconductor laser device 37 obtained according to the present modification has the n-type semiconductor layer 33a, the active layer 33b, the active layer 33b, and the groove 2 reaching the substrate 1 from the p-type semiconductor layer 33c on the wafer 2.
The p-type semiconductor layer 33c and the p-type semiconductor layer 33c have desired shapes and dimensions, and the resonance surface 35 for laser oscillation is formed in the active layer 33b. Then, the substrate 1 is compared with the cutting start region by the cutting start region along the planned cutting line 5 formed by the modified region 7 formed by the phenomenon of multiphoton absorption inside the substrate 1 of the wafer 2. It is cut with a small force. Therefore, it is possible to provide the semiconductor laser element 37 in which the wafer 2 having a laminated structure of the n-type semiconductor layer 33a, the active layer 33b, the p-type semiconductor layer 33c, etc. is cut with high precision and efficiency.

Although the embodiments and modifications of the present invention have been described above in detail, it goes without saying that the present invention is not limited to the above-mentioned embodiments and modifications.

Although sapphire is used as the material of the substrate in the above-described embodiments and modifications, other materials such as SiC, Si, ZnO, AlN, and GaAs can be used. Further, GaN is used as the material for the p-type semiconductor layer, the active layer, and the n-type semiconductor layer, but other than this, for example, GaAlAs, GaAlAsP, G
A III-V group compound such as aAlInP can be used.

In addition, among the III-V group compounds, for example, In _X Al _Y Ga _1-XY N (X ≧ 0, Y ≧ 0, X + Y ≦
1) a nitride-based III-V group compound (Ga)
In general, a semiconductor layer made of N (including N) is generally laminated on a sapphire substrate. Sapphire has a higher hardness than other materials, and the time required for etching and blade dicing becomes long. Moreover, sapphire has a smaller cleavage property than GaAs and the like, and therefore, Patent Document 1
If the diamond scribing method disclosed in US Pat. Therefore, when a wafer in which a nitride-based III-V group compound semiconductor is laminated on a sapphire substrate is cut, by applying the method for manufacturing a light emitting device according to the present invention, the cutting accuracy is significantly improved and Manufacturing efficiency can be improved.

Further, before forming the modified region 7 in the above-described embodiments and examples, the back surface may be polished so that the substrate becomes thin. 29A to 29C are views showing an example of a method of polishing the back surface 21 of the substrate 1 of the wafer 2 in the above-described embodiment. First, as shown in FIG. 29A, the tape 2 is applied to the surface of the wafer 2 on the p-type semiconductor layer 17b side.
Paste 4. Then, as shown in FIG. 29B, the back surface 21 of the substrate 1 is polished to reduce the thickness of the substrate 1. At this time, the back surface 21 side of the wafer 2 is facing upward,
FIG. 29 (b) is an upside down view of the actual state. Subsequently, as shown in FIG. 29C, the tape 24 is removed, and the expand tape 23 is attached to the back surface 21 of the substrate 1.

When the substrate is relatively thin, the precision in cutting the substrate is further improved. Further, when the laser light is incident from the back surface of the substrate, the position of the groove can be confirmed from the back surface by thinning the substrate. Further, by growing cracks in the thickness direction of the substrate from the modified region, it becomes easy to separate the wafer into chips without requiring external force.

Further, in the above-described embodiments and examples, the p-type semiconductor layer, the active layer, and the n-type semiconductor layer are laminated on the substrate as semiconductor layers. Other than this, as the semiconductor layer, a contact layer or the like for electrical connection with the electrode may be further laminated. Although the first conductivity type is n-type and the second conductivity type is p-type, the first conductivity type may be p-type and the second conductivity type may be n-type.

Further, in the above embodiment, the expanding tape is used to cut the wafer in which the cutting starting point region is formed. In addition to this, in order to cut the wafer in which the cutting start region is formed, for example, a method of cutting by pressing a knife edge against the bottom surface of the groove or the back surface of the wafer, a method of cutting using a breaker device, or a roller device. and so on.

[0090]

As described above, in the method for manufacturing a light emitting device, the light emitting diode, and the semiconductor laser device according to the present invention, first, a groove reaching from the semiconductor layer to the substrate is formed in the wafer to form the semiconductor layer. Is processed into a desired shape and dimension. Then, in the modified region formed by the phenomenon of multiphoton absorption inside the substrate of the wafer, the cutting start region is formed along the planned cutting line, and the substrate is moved along the cutting start region with a relatively small force. It is cut and cut. Therefore, according to the method for manufacturing a light emitting device, the light emitting diode, and the semiconductor laser device according to the present invention, a wafer having a laminated structure can be cut with high accuracy and efficiency.

[Brief description of drawings]

FIG. 1 is a plan view of a substrate 1 during laser processing.

2 is a cross-sectional view taken along the line II-II of the substrate shown in FIG.

FIG. 3 is a plan view of a substrate after laser processing.

FIG. 4 is a sectional view taken along line IV-IV of the substrate shown in FIG.

5 is a cross-sectional view taken along the line VV of the substrate shown in FIG.

FIG. 6 is a plan view of the cut substrate.

FIG. 7 is a graph showing the relationship between the electric field strength and the size of a crack spot in the laser processing method used in this embodiment.

FIG. 8 is a cross-sectional view of the substrate in the first step of the laser processing method used in this embodiment.

FIG. 9 is a sectional view of a substrate in a second step of the laser processing method used in this embodiment.

FIG. 10 is a cross-sectional view of a substrate in a third step of the laser processing method used in this embodiment.

FIG. 11 is a cross-sectional view of a substrate in a fourth step of the laser processing method used in this embodiment.

FIG. 12 is a view showing a photograph of a cross section of a part of a silicon wafer cut by a laser processing method used in the present embodiment.

FIG. 13 is a graph showing the relationship between the wavelength of laser light and the internal transmittance of the silicon substrate in the laser processing method used in this 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 light emitting device according to the present embodiment.

16 is a plan view of the wafer shown in FIG.

17 is a VI-VI cross section and VI of the wafer shown in FIG.
FIG. 7 is an enlarged view showing a cross section taken along line I-VII.

FIG. 18 is a flowchart illustrating a method for manufacturing a light emitting device according to this embodiment.

FIG. 19 is a flowchart showing a method of forming a cutting start region on a wafer by using the laser processing apparatus shown in FIG.

FIG. 20 is a cross-sectional view of the wafer for explaining the method for manufacturing the light emitting device.

FIG. 21 is a cross-sectional view of the wafer for explaining the method for manufacturing the light emitting device.

FIG. 22 is a cross-sectional view of the wafer for explaining the method for manufacturing the light emitting device.

FIG. 23 is a cross-sectional view of the wafer for explaining the method for manufacturing the light emitting device.

FIG. 24 is a cross-sectional view of the wafer for explaining the method for manufacturing the light emitting device.

FIG. 25 is a sectional view illustrating the modification of the method for manufacturing the light emitting device according to the present embodiment.

FIG. 26 is a cross-sectional view for explaining another modification of the method for manufacturing the light emitting device according to the present embodiment.

FIG. 27 is a cross-sectional view for explaining another modification of the method for manufacturing the light emitting device according to the present embodiment.

FIG. 28 is a cross-sectional view illustrating another modification of the method for manufacturing the light emitting device according to the present embodiment.

FIG. 29 is a diagram showing an example of a method of polishing the back surface of the substrate of the wafer.

[Explanation of symbols]

1 ... Substrate, 2 2a ... Wafer, 3 ... Surface, 5 ... Planned cutting line, 7 ... Modified area, 8 ... Cutting starting area, 9 ... Crack area, 11 ... Silicon wafer, 13 ... Melt processing area,
17a ... N-type semiconductor layer, 17b ... P-type semiconductor layer, 19 ...
Orientation flat, 21 ... Back surface, 23 ... Expanded tape, 24 ... Tape, 25 ... First groove, 27
... second groove, 28 ... groove, 31 ... light emitting diode, 33a
... n-type semiconductor layer, 33b ... active layer, 33c ... p-type semiconductor layer, 35 ... resonant surface, 37 ... semiconductor laser element, 100 ...
Laser processing device 101 ... Laser light source 102 ... Laser light source control unit 103 ... Dichroic mirror 105 ...
Condensing lens, 107 ... Mounting table, 109 ... X-axis stage, 111 ... Y-axis stage, 113 ... Z-axis stage, 1
15 ... Stage control unit 117 ... Observation light source 119 ...
Beam splitter, 121 ... Image sensor, 123 ... Image forming lens, 125 ... Imaging data processing unit, 127 ... Overall control unit, 129 ... Monitor, L ... Laser light, P ... Focus point.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Naoki Uchiyama             1 Hamamatsuho, 1126 Nomachi, Hamamatsu City, Shizuoka Prefecture             Tonics Co., Ltd. F-term (reference) 4E068 AE01 DA10                 5F041 AA31 AA41 AA42 CA40 CA46                       CA75 CA77                 5F072 AB02 JJ08 JJ12 JJ20 PP07                       QQ20 RR01 YY06                 5F073 AA74 CA02 CA17 CB05 DA23                       DA25 DA31 DA34 DA35 EA29

Claims (8)

[Claims] 1. A wafer in which a semiconductor layer made of a III-V group compound semiconductor is laminated on the surface of a substrate, and the semiconductor layer is transferred from the semiconductor layer to the substrate along a cutting line for cutting the wafer into chips. A groove reaching the groove is formed, and a laser beam is irradiated by irradiating a laser beam with the converging point inside the substrate facing the groove, thereby forming a modified region by multiphoton absorption. A method of manufacturing a light emitting device, comprising the steps of forming a cutting start region inside a predetermined distance from an incident surface and cutting the wafer along the cutting start region. 2. The method for manufacturing a light emitting device according to claim 1, wherein the bottom surface of the groove is used as the laser light incident surface when the substrate is irradiated with the laser light. 3. The method for manufacturing a light emitting device according to claim 2, wherein when the groove is formed on the wafer, the bottom surface of the groove is formed to be flat and smooth. 4. The method according to claim 2, wherein, when forming the modified region, a width of the modified region in a direction intersecting with the groove is formed narrower than a width of the groove in the direction. Manufacturing method of the light emitting device. 5. The method for manufacturing a light-emitting element according to claim 1, wherein the back surface of the substrate is the laser light incident surface when the substrate is irradiated with the laser light. 6. The method for manufacturing a light emitting device according to claim 5, wherein the back surface of the substrate is flat and has a smooth surface. 7. A wafer having a substrate and a first-conductivity-type semiconductor layer and a second-conductivity-type semiconductor layer which are made of a III-V group compound semiconductor and are laminated on the surface of the substrate, and a chip is cut along a line to cut. It is a light emitting diode formed by cutting into a shape, and a laser beam is irradiated to a groove reaching the substrate from the second conductivity type semiconductor layer and a focusing point inside the substrate facing the groove. A modified region is formed by multiphoton absorption,
A light emitting diode, which is cut by the modified region and a cutting start region formed inside a predetermined distance from the laser light incident surface of the substrate. 8. A line for cutting a wafer having a substrate, a first conductivity type semiconductor layer made of a III-V group compound semiconductor and laminated on the surface of the substrate, an active layer, and a second conductivity type semiconductor layer. A semiconductor laser device formed by cutting the semiconductor laser device in a chip shape along a groove, the groove reaching the substrate from the second conductivity type semiconductor layer, and a converging point inside the substrate facing the groove. Laser light is irradiated to form a modified region by multiphoton absorption,
A semiconductor laser device cut by the modified region and a cutting start region formed inside a predetermined distance from the laser light incident surface of the substrate.