JP2002222772A - Method for manufacturing nitride semiconductor substrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent cracking and splitting when nitride semiconductor is grown on a base material substrate and it is separated from the nitride semiconductor by using laser irradiation. SOLUTION: Atomic bond of the base material substrate is weakened by ion implantation or the like. The nitride semiconductor is grown on the base material substrate, and it is separated from the nitride semiconductor by using laser irradiation. As a result, a nitride semiconductor substrate is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for manufacturing a nitride semiconductor substrate used for a visible light emitting diode device or a blue-violet laser device, and a base material substrate for manufacturing a nitride semiconductor substrate.

[0002]

2. Description of the Related Art Nitride semiconductors such as GaN, InN, and AlN are suitable as materials used for blue and green LEDs, blue semiconductor lasers, high-speed transistors that can operate at high temperatures, and the like. Conventionally, a sapphire substrate (for example, Japanese Patent No. 3091) has been used as a substrate for growing a nitride semiconductor.
593) is known, but in the growth of a nitride semiconductor on a dissimilar substrate such as sapphire, the difference in thermal expansion coefficient between the nitride semiconductor and the dissimilar material substrate causes warpage and cracking of the substrate. It is known that the deterioration of crystallinity accompanying the above occurs.

In recent years, attempts have been made to solve the above-mentioned problems by fabricating devices on a nitride semiconductor substrate. As one method for manufacturing a nitride semiconductor substrate, a thick nitride semiconductor layer is formed over a base material substrate, and the nitride semiconductor layer is locally heated and sublimated at a base material substrate interface by laser light. It has been studied to peel off the nitride semiconductor layer from the substrate.

[0004]

However, when peeling is performed by laser light, the irradiation size of laser light is smaller than the area of the substrate, and it is necessary to scan with laser light. At this time, the following problems existed.

[0005] During the scanning of the laser beam, the nitride semiconductor layer and a part of the base material substrate are peeled off and remain in contact with each other at that time. There is a problem that stress is concentrated on a portion where the contact of the base material substrate remains, and cracks occur in the nitride semiconductor layer. Therefore, it has been difficult to manufacture a nitride semiconductor substrate with good yield by laser light irradiation at around room temperature. A technique of increasing the substrate temperature to avoid this is known, but it takes time to raise and lower the temperature of the substrate, and there is a problem in mass productivity.

Further, since the laser light is condensed small, it is necessary to provide a method for performing efficient laser irradiation in order to peel the entire substrate. Specifically, the laser light needs to have an optical density of about 0.1 J or more per square centimeter in order to cause sublimation of the nitride semiconductor, and in order to achieve this, the laser beam is condensed with a small beam diameter. . Therefore, the beam diameter is smaller than the substrate area, and it is necessary to scan with a laser beam. In order to peel off the entire nitride semiconductor layer, it is necessary to irradiate the entire nitride semiconductor layer with a beam while scanning the substrate finely over a long period of time, and it is not possible to perform so-called batch processing in which a large number of substrates are processed at once. . Therefore, it is necessary to provide a method for performing laser irradiation more efficiently in the irradiation step than before, while preventing the occurrence of cracks.

In view of the above, it is an object of the present invention to significantly reduce the time required for laser light irradiation in the manufacture of a nitride semiconductor substrate by laser light irradiation, and to reduce nitrides without generating cracks or the like in the nitride semiconductor layer. It is an object to provide means for obtaining a semiconductor substrate.

[0008]

Means for Solving the Problems In order to solve the above problems, a method for manufacturing a nitride semiconductor substrate of the present invention has the following configuration.

The method for manufacturing a nitride semiconductor substrate according to the present invention comprises:
First to provide a region where an atomic bond has been cut on the main surface of a base material substrate
And a second step of forming a nitride semiconductor layer on the base material substrate; and a third step of irradiating a laser beam to the interface between the base material substrate and the nitride semiconductor layer. And

[0010] By doing so, the stress generated in the nitride semiconductor layer during laser irradiation is released by the peeling of the region where the atomic bonds have been cut, so that cracks and cracks are generated in the nitride semiconductor layer. Does not occur. Furthermore, by the peeling of the nitride semiconductor layer due to the aforementioned stress,
Since the nitride semiconductor layer can be separated without performing laser scanning over the entire surface of the nitride semiconductor layer, mass productivity of the nitride semiconductor substrate can be improved.

In the method for manufacturing a nitride semiconductor substrate according to the present invention, the region where the atomic bonds have been cut can be formed by ion implantation.

In the method for manufacturing a nitride semiconductor substrate according to the present invention, the first step includes the step of: ion-implanting a first region into the main surface of the base material substrate; Preferably, a step of providing a second region not ion-implanted is provided, and the third step is a step of irradiating at least the second region with the laser light. This makes it possible to more reliably peel off the nitride semiconductor layer without irradiating the entire surface of the nitride semiconductor layer, so that mass productivity of the nitride semiconductor substrate can be improved.

In this configuration, the second region having a small ion implantation amount is linearly connected, and the third step is a step of scanning the laser beam along the second region. Is preferred. By doing so, the nitride semiconductor layer can be peeled by efficient scanning of the optical axis.

In this configuration, the above-mentioned second region having a small amount of ion implantation is dispersedly provided, and the third step is to synchronize the optical axis of the laser beam with the second region. And irradiating the laser light with a pulse while scanning. By doing so, the nitride semiconductor layer can be peeled by efficient scanning of the optical axis using a pulse laser.

In this configuration, the second region having a small amount of ion implantation is dispersedly provided, and the third step is performed by irradiating the laser beam with a plurality of the second regions. It is preferable to irradiate the surface. By doing so, the nitride semiconductor layer can be separated in a shorter irradiation time.

In the method for manufacturing a nitride semiconductor substrate of the present invention, it is preferable that the base material substrate is sapphire and the ions to be implanted are hydrogen or silicon. By doing so, it is possible to cut a sapphire atomic bond and form a region where the atomic bond is weak without causing contamination that deteriorates the characteristics of the nitride semiconductor layer.

In the method for manufacturing a nitride semiconductor substrate according to the present invention, the region where the atomic bonds have been cut can be formed by plasma irradiation.

In the method of manufacturing a nitride semiconductor substrate according to the present invention, the first step includes: a first region in which a main surface of the base material substrate is irradiated with plasma; and a plasma irradiation amount smaller or larger than the first region. Preferably, a step of providing a second region that is not irradiated with plasma is performed, and the third step is a step of irradiating at least the second region with the laser light. This makes it possible to more reliably peel off the nitride semiconductor layer without irradiating the entire surface of the nitride semiconductor layer with a laser, so that mass productivity of the nitride semiconductor substrate can be improved.

In this configuration, the second region having a small amount of plasma irradiation is linearly connected, and the third step is a step of scanning the laser beam along the second region. Is preferred. By doing so, the nitride semiconductor layer can be peeled by efficient scanning of the optical axis.

In such a configuration, the above-mentioned second region having a small amount of plasma irradiation is distributed and installed in a plurality.
Preferably, the third step is a step of irradiating the laser beam with a pulse while scanning the optical axis of the laser beam in synchronization with the second region. By doing so, the nitride semiconductor layer can be peeled by efficient scanning of the optical axis using a pulse laser.

In such a configuration, the above-mentioned second region having a small amount of plasma irradiation is distributed and provided in plural.
Preferably, the third step is a step of irradiating the plurality of second regions by one irradiation of the laser light.
By doing so, the nitride semiconductor layer can be separated in a shorter irradiation time.

In the method for manufacturing a nitride semiconductor substrate according to the present invention, it is preferable that the base material substrate is sapphire and the plasma to be irradiated is hydrogen, oxygen, or a rare gas. By doing so, it is possible to cut a sapphire atomic bond and form a region where the atomic bond is weak without causing contamination that deteriorates the characteristics of the nitride semiconductor layer.

[0023]

Embodiments of the present invention will be described below with reference to the drawings.

(Embodiment 1) A method for manufacturing a GaN substrate according to a first embodiment of the present invention will be described with reference to FIG.

The substrate 1 shown in FIG. 1A is sapphire (single crystal of aluminum oxide) having a diameter of 2 inches and a thickness of 700 microns, and the front and rear surfaces are mirror-finished. The plane orientation of the surface is the (0001) plane.

The substrate 1 is made of sapphire,
Since the band gap of sapphire is 8.7 eV,
142.5 nm of energy corresponding to band gap
Larger wavelength light is transmitted. Therefore, the wavelength 248
nm KrF excimer laser light or 355 nm wavelength N
d: Third harmonic light of a YAG laser can be transmitted.

First, an ion implantation step as a first step is performed.

Hydrogen ions are implanted into the sapphire substrate 1 (FIG. 1B). By the ion implantation, a region 1a in which atomic bonds have been cut (hereinafter, referred to as an ion-implanted region 1a or simply a region 1a up to the fifth embodiment) is formed. The injection amount was 1 × 10 ¹⁶ ions / cm ² , and the injection was performed while tilting the substrate by 5 °. Accelerating voltage is 200 keV
And By implanting hydrogen ions into the sapphire substrate, bonds between Al and O, which are constituent elements of sapphire, are broken. Hydrogen may be introduced between the cut atoms. As a result, the average atomic bonding force in the ion-implanted region can be made relatively weaker than in the region into which the ions have not been implanted.

When the injection amount is small, the bond between atoms breaks near the surface of the substrate and the amount of weakening of the atomic bond decreases, and the amount of the nitride semiconductor layer 2 and the base material substrate 1 during laser irradiation described later decreases. It becomes difficult to efficiently perform peeling. On the other hand, when the implantation amount is large, a part of the base material substrate is peeled off before the substrate surface grows the nitride semiconductor layer, and fine particles that are peeled off adhere to the surface and adversely affect the growth of the nitride semiconductor layer. May be exerted. Under these circumstances, considering the preferable range of the injection amount, 1 × 10 ¹⁴ ions / cm ²
From 1 × 10 ¹⁸ ions / cm ² .

The ion implantation angle is preferably such that ions are incident from a plane inclined at least 2 ° from the (0001) plane of sapphire in order to prevent implanted hydrogen from being implanted deeply due to the channeling effect. .

The accelerating voltage at the time of ion implantation is not particularly limited. However, if the accelerating voltage is low, damage near the sapphire surface is increased.

Next, a second step of growing a nitride semiconductor layer is performed. GaN was grown by a hydride vapor phase epitaxy method (hereinafter referred to as HVPE method) using ammonia, Ga metal, and GaCl produced by reacting HCl at a high temperature of about 900 ° C. The pressure was grown at atmospheric pressure.

In order to increase the nucleation density of GaN on sapphire, the substrate temperature must be increased by 100% prior to GaN growth.
Keep at 0 ° C. and supply only GaCl for 15 minutes (hereinafter, referred to as “GaCl”).
This process is called GaCl treatment). For the purpose of increasing the nucleation density, a process of nitriding sapphire with a low-temperature buffer layer or ammonia may be performed instead of the GaCl process, or a combination thereof.

After the GaCl treatment, ammonia is introduced to add G
The growth of the aN layer 2 is started. The thickness of the GaN layer 2 is 200
The substrate was grown to a thickness of μm, the substrate temperature was lowered to room temperature, and the substrate was taken out (FIG. 1C).

A GaN layer 2 was grown at a high temperature on a sapphire substrate 1 and cooled to room temperature.
Warpage due to the difference in thermal expansion coefficient between the two. Since sapphire has a larger coefficient of thermal expansion than GaN, warpage is caused by making the GaN layer 2 side convex. In the present embodiment, the radius of curvature is 6
It was about 0 cm. In the present embodiment, the base material substrate 1 is G
Since it is thicker than the aN layer 2, it has a large radius of curvature and is not warped enough to cause cracking.

Since the sapphire substrate 1 has been ion-implanted, the bond between Al and O is broken, and the
At a high temperature of 00 ° C., these elements easily diffuse into the GaN layer 2. Al in GaN forms an isoelectronic trap,
O acts as a donor. Therefore, when a device is formed on a GaN substrate, it is preferable that these elements do not diffuse into the active region of the device. Preferably, by setting the thickness of the GaN layer 2 to 30 μm or more, Al and O diffused into the device active region can be sufficiently reduced.

Next, a third step of substrate separation by laser beam irradiation is performed. The laser irradiation was performed using the optical system and the stage shown in FIG. When irradiating the GaN layer 2 with the laser light 10 emitted from the laser device 3, the laser light is irradiated over the entire substrate by rotating the rotating mechanism 4 and scanning the optical axis with the scan lens 5. It is configured so that Further, the spot diameter of the laser beam on the GaN layer 2 can be controlled by the condensing means 6.

The stage may be provided with a heating means such as a resistance heater for adjusting the warpage of the base material substrate 1. Further, a cooling means such as a Peltier element for promoting separation due to a difference in thermal expansion coefficient may be provided.

The laser device 3 is a device for generating the third harmonic laser light of the Nd: YAG laser light. The pulse frequency was 10 Hz, and the pulse width of one pulse was 5 ns. Using the focusing means 6, the laser beam is focused on the GaN layer 2 to have a circular shape and a diameter of 1 mm. The energy per pulse was 0.1 J on the sapphire substrate 1.

The energy of the laser beam reaching the GaN layer 2 is reflected by the surface of the substrate 1, the interface between the substrate 1 and the GaN layer 2, and absorbed by defects in the substrate 1.
Decay. Therefore, the thickness of the board, the finish of the back of the board,
It is necessary to adjust the energy per pulse or the beam diameter depending on the substrate characteristics and the like so that GaN is decomposed. The beam energy density required for GaN sublimation decreases as the substrate temperature increases. Also, since the peak energy increases as the pulse width decreases, the GaN
It changes depending on the energy density per pulse required for sublimation. For a pulse of several ns to several tens of ns near room temperature, it is about 0.1 J / cm ² or more. In the present embodiment, the pulse energy is sufficient even in consideration of scattering and attenuation.

Since the GaN layer 2 is warped, the focal position is controlled depending on the irradiation position by controlling the light condensing means 6, and the size of the laser beam 10 at the position of the GaN layer 2 is kept constant. Is preferred.

When the focal position is not controlled by the irradiation position, it is preferable that the focal length of the light condensing means 6 be close to the radius of curvature of the GaN layer. By doing this,
The size of the laser beam 10 at the position of the GaN layer 2 can be made constant without using a special lens.

The GaN layer 2 was irradiated with the laser beam 10 from the sapphire substrate 1 side. The laser irradiation was performed in a room temperature atmosphere (about 20 ° C.) without particularly heating or cooling the substrate. Laser irradiation was performed from the periphery to the center. At this time, instead of irradiating the entire GaN layer 2 without gaps, as shown in the schematic diagram of the upper surface of FIG. 1D, the center interval in the rotation direction and the center interval in the radial direction of the irradiation position 8 are separated by 2 mm. The rotation speed of the rotation mechanism 4 and the scanning speed of the scan lens 5 were adjusted so that irradiation was performed. As an adjustment method, the interval in the rotation direction of the spot can be changed by changing the rotation speed of the substrate or the frequency of the pulse of the laser device 3. Further, by changing the scanning speed of the optical axis according to the rotation speed, the interval in the radial direction can be changed.

The GaN layer 2 irradiated with the laser beam 10 absorbs the laser beam 10 near the interface with the sapphire substrate 1 and is heated. Since the pulse width is as short as 5 ns, the portion to be heated is concentrated near the very interface with the sapphire substrate 1, and only GaN at the interface with the sapphire substrate 1 is sublimated and decomposed into Ga and nitrogen.

FIG. 1E is a sectional view in the middle of the irradiation step. In order to clearly show the drawing, hatching is not applied to FIG.

In the portion of the GaN layer 2 irradiated with the laser beam 10, metal Ga11 is generated. Metal Ga is
Since it is liquid at 25 ° C. or higher and very soft at 25 ° C. or lower, the bond between the sapphire substrate 1, the Ga 11 and the GaN layer 2 is about the surface tension, and is extremely weak. Therefore, the stress due to the difference in thermal expansion coefficient concentrates on a portion that is not irradiated with the laser.

Further, the decomposition of the GaN layer 2 generates nitrogen gas together with the metal Ga11. The pressure due to the generated nitrogen is applied in a direction in which the sapphire substrate 1 and the GaN layer 2 are peeled off. Since the bond between atoms in sapphire is weakened by ion implantation in the region not irradiated with the laser, the region cannot withstand the concentration of stress due to the difference in thermal expansion coefficient and the pressure of nitrogen. Occurs. At this time, nitrogen generated by decomposition of the GaN layer 2 diverges through the cracks 12.

It should be noted that, based on the above-described circumstances, the ion implantation amount is set to 1
Since it is from x10 ¹⁴ ion / cm ² to 1 × 10 ¹⁸ ion / cm ² , cracks occur only in the ion-implanted region 1a where the atomic bond is weak, and the sapphire substrate 1 and the GaN layer 2
Has no cracks or cracks.

When the laser irradiation process is further continued, the stress is concentrated near the center of the substrate when the laser is irradiated from the periphery to about 1 cm inward without laser irradiation to the center. It extended to the whole injection region 1a. As a result, the GaN layer 2 was separated from the sapphire substrate 1 (FIG. 1F). Due to the peeling, the warpage of both the sapphire substrate 1 and the GaN layer 2 was eliminated.

As described above, automatic peeling due to internal stress without laser beam irradiation is called automatic peeling. Ga11 and sapphire pieces 13 are adhered to the main surface on the back side of the GaN layer 2.

The point at which the GaN layer 2 is peeled off varies depending on the ion implantation amount, the center distance and the pitch of the irradiation spots, and the like. As the amount of ion implantation was increased and the laser was densely irradiated, automatic peeling occurred at an earlier stage of laser irradiation. When the substrate is cooled from room temperature with a Peltier element or liquid nitrogen, automatic peeling occurs at an early stage.

In the case of irradiating the entire substrate as in the case of GaN peeling by conventional laser irradiation, a circular beam having a diameter of 1 mm requires a pitch or spot interval of about 0.8 mm or less. It takes about 5 minutes to irradiate the wafer. Moreover, it is necessary to add a time for raising and lowering the substrate temperature to this time.

On the other hand, in the irradiation in which the spot interval and the pitch are separated as in this embodiment, even if the laser is irradiated to the center of the substrate, the number of laser irradiation spots is reduced to about 1 /.
6, and the time for irradiating one wafer can be remarkably reduced to about 50 seconds. In addition, in the present embodiment, the GaN layer 2 automatically starts peeling at a stage where the irradiation is performed about 1 cm from the periphery, and the scan time is only about 20 seconds.

Finally, Ga11 was dissolved by immersing the GaN layer 2 in a 35% HCl solution for 30 minutes. Further, the sapphire piece 13 and the unevenness formed by the presence of Ga11 are removed by polishing, and the GaN substrate 2 made of a single substance is completely removed.
Was obtained (FIG. 1 (g)).

In the first embodiment, Nd: Y
It goes without saying that, instead of the AG laser light, light having a power sufficient to absorb light, transmit through sapphire, and sublimate GaN may be used. As an example of such a light source, a KrF excimer laser (248
nm), ArF excimer laser (193 nm), XeC
1 Excimer laser (308 nm), XeF excimer laser (351 nm), nitrogen laser (337 nm) and the like.

In the present embodiment, the laser beam is irradiated without overlapping, but the laser beam is irradiated without overlapping,
It goes without saying that the GaN substrate 2 can be obtained without cracks or cracks.

(Embodiment 2) Hereinafter, Embodiment 2 will be described with reference to FIG. The second embodiment is the same as the first embodiment except that silicon is used instead of implanted ions.
Is exactly the same as

The substrate 1 shown in FIG. 3A is a (0001) plane sapphire having a diameter of 2 inches and a thickness of 700 microns, and both the front and rear surfaces are mirror-finished.

Silicon ions are implanted into the sapphire substrate 1 (FIG. 3B). The region 1a is a silicon implantation region. The injection amount was 1 × 10 ¹⁶ ions / cm ² , and the injection was performed while tilting the substrate by 5 °. Acceleration voltage is 200 ke
V. By ion-implanting silicon into a sapphire substrate, the bond between Al and O, which are constituent elements of sapphire, is cut or silicon is introduced between atoms, similarly to hydrogen. As a result, it is possible to form a region in which the average atomic bonding force in the region into which ions are implanted is relatively weaker than that in the region into which ions are not implanted.

[0060] As with the hydrogen ions, when considering the range of the injection amount of the preferred silicon ions, 1x10 ¹⁴ ion / c
m ² to 1 × 10 ¹⁸ ions / cm ² .

The implantation angle at the time of ion implantation is preferably inclined by 2 ° or more from the (0001) plane of sapphire in order to prevent the implanted silicon from being implanted deeply due to the channeling effect.

The acceleration voltage at the time of ion implantation is not particularly limited, but if the acceleration voltage is low, damage near the sapphire surface increases. However, since silicon has an atomic weight larger than that of hydrogen, damage is likely to concentrate near the surface, and is preferably 50 keV or more.

Next, a second step of growing a nitride semiconductor layer is performed. GaN was grown by HVPE using ammonia, Ga metal and HCl as raw materials. 1
After the GaCl treatment for 5 minutes, ammonia is introduced and Ga
The N layer 2 is grown. 200 μm thick GaN layer 2
m, the substrate temperature was lowered to room temperature, and the substrate was taken out (FIG. 3C).

Next, a third step of separating the substrate by laser irradiation is performed. Laser irradiation was performed using the same apparatus and irradiation method as in Embodiment 1. As a result, the GaN layer 2 was separated from the sapphire substrate 1 (FIG. 3).
(D)). On the back surface of the GaN layer 2, Ga11 and sapphire pieces 13 were adhered.

Finally, Ga11 is dissolved by HCl,
The irregularities of the sapphire piece 13 and the GaN layer 2 were removed by polishing to obtain a single GaN substrate 2 (FIG. 3E).

As described above, it was confirmed that the same effect as that of hydrogen ion implantation can be obtained by silicon ion implantation.
It is known that, when a heavy metal such as gold or silver is injected, when a nitride semiconductor device is formed, gold or silver penetrates into the device and forms a deep level to cause deterioration of characteristics. Needless to say, such a problem does not occur in silicon or hydrogen.

Embodiment 3 Hereinafter, Embodiment 3 will be described with reference to FIG. The third embodiment shows an example in which linear patterning is performed at the time of ion implantation.

The substrate 1 in FIG. 4A is a (0001) plane sapphire having a diameter of 2 inches and a thickness of 700 microns, and both the front and rear surfaces are mirror-finished.

A step of implanting hydrogen ions into the sapphire substrate 1 is performed (FIGS. 4B, 4C and 4D).

First, a resist mask 7 is provided as shown in FIG. The shape of the mask 7 is shown in FIG.
As shown in the schematic diagram of (b-2), the shape is a spiral spiral.
The spiral spiral had a pitch of 2 mm and a width of 0.5 mm.

After the ion implantation, in order to easily determine the ion implantation region after removing the mask 7, it is preferable to perform mask alignment so that the starting point of the spiral can be confirmed at the orientation flat position or the like.

Next, hydrogen ions were implanted as shown in FIG. The injection amount of hydrogen ions is 1 × 10 ¹⁶ ion /
cm ² and implantation was performed with the substrate tilted at 5 °. The acceleration voltage was 200 keV. A portion of the main surface of the sapphire substrate 1 where the mask 7 does not exist is a region 1a into which ions have been implanted.
Is formed. In the portion where the mask 7 exists, the amount of implanted hydrogen ions is reduced by blocking the hydrogen ions,
More preferably, a region 1b where almost no implantation is performed and where atomic bonds are substantially preserved (hereinafter referred to as a region 1b not ion-implanted or simply a region 1b up to the fifth embodiment) is formed.

The base material substrate is completed by removing the mask 7 (FIG. 4D).

Next, a second step of growing a nitride semiconductor layer is performed. In the same manner as in Embodiment 1, HVPE
The GaN layer 2 was grown to 200 μm by the method, the substrate temperature was lowered to room temperature, and the substrate was taken out (FIG. 4E).

Next, a third step of separating the substrate by laser irradiation is performed. Laser irradiation was performed at room temperature using the same apparatus as that in Embodiment 1. The laser irradiation was performed from the periphery to the center while adjusting the irradiation start position, the rotation speed, and the scanning speed of the optical axis so that the region 1b not ion-implanted was irradiated without a gap. Specifically, since the laser spot size is 1 mm, in order to irradiate the spiral spiral region 1b without a gap, the rotation speed is adjusted so that the spot interval is approximately 0.8 mm. More preferably, the rotation is performed so that the linear velocity becomes constant. Further, the scanning speed of the optical axis is also adjusted so that the pitch becomes 2 mm in one round of the substrate.

Although the ion-implanted region 1a has no significant change in appearance, the ion-implanted position has a slightly different refractive index and absorption coefficient. It is possible to do. Since the absorption coefficient at the ion implantation position becomes significant in the ultraviolet region of about 200 nm, the determination can be made easier by confirming with a camera or the like that detects ultraviolet rays.

FIG. 4F is a sectional view in the middle of the irradiation step. The figures are not hatched for clarity.
Ga11 generated by the decomposition of the GaN layer 2 is formed in the region where the laser beam irradiation has been performed. In addition, cracks 12 occur in the ion-implanted region 1a due to the pressure of the nitrogen gas generated by the decomposition of the GaN layer 2 and the stress concentration due to the difference in thermal expansion coefficient.

On the other hand, the region 1b not ion-implanted
The crack 12 does not extend because sapphire is strong. Therefore, the substrate is irradiated with laser light, and cracks 1
2, crack 12 stops at region 1b and G
Automatic peeling over the entire aN layer 2 does not occur.

In the present embodiment, complete peeling occurred only after the laser irradiation was completed to the center, and the GaN layer 2 was separated from the sapphire substrate 1 (FIG. 4G).

Finally, Ga11 was dissolved with HCl, and the sapphire pieces 13 and the irregularities on the back surface of the GaN layer 2 were removed by polishing to obtain a GaN substrate 2 (FIG. 4 (h)).

When the GaN layer 2 is automatically peeled off during laser irradiation as in the first embodiment, the sapphire pieces 13 attached to the back surface of the GaN layer 2 are not fixed because the stage at which the peeling occurs is not constant. Is different every time. G
In the back surface polishing step for removing the sapphire pieces 13 on the back surface of the aN layer 2,
It is necessary to polish the back surface of each GaN layer 2 and the sapphire pieces 13 one by one under the conditions suitable for the GaN layers 2 and the sapphire pieces 13. On the other hand, in the present embodiment, since the shape of the back surface is almost constant, a plurality of GaN substrates 2
Was able to be polished on the back surface of the substrate. Therefore, the method of the present embodiment is suitable for mass production.

In the region 1 where the ion implantation has not been performed,
It is preferable that b has a continuous shape, because the laser beam can be easily scanned. For example, radial, striped,
And the like. Further, it is most preferable that the pattern be one-stroke drawing such as a spiral spiral of the present embodiment.

The region 1a where the ion implantation is performed
There is a preferable area relationship between the region 1b where the ion implantation is not performed. Specifically, as compared with the region 1a, the region 1
If b is too narrow, peeling is unlikely to occur, making it difficult to obtain a nitride semiconductor wafer. Conversely, area 1
If the area 1b is too wide compared to the area a, the stress is not released by the automatic peeling because the area of the area where the automatic peeling is possible, that is, the area of the area 1a is small.
Cracks and cracks may occur. Under such circumstances, in room temperature irradiation, the preferable area relationship is that the area of the region 1a is 1/5 to 5 times the area of the region 1b.
It is between 0 times.

(Embodiment 4) Hereinafter, Embodiment 4 will be described with reference to FIG. Embodiment 4 shows an example in which patterning of a plurality of shapes is performed at the time of ion implantation.

The substrate 1 in FIG. 5A is the same sapphire as in the first embodiment.

A step of implanting hydrogen ions into the sapphire substrate 1 is performed (FIGS. 5B, 5C and 5D).

First, a pattern by the mask 7 is provided as shown in FIG. The shape of the mask 7 is shown in FIG.
As shown in the schematic diagram of (b-2), it has a circular dot shape. The dots by the mask 7 are positioned at each vertex of an equilateral triangle having a side of 2 mm and laying a plane. The center spacing between adjacent masks 7 is 2 mm, and the diameter of one mask 7 is 0.5 mm.

After the ion implantation, if the mask 7 is removed, it is preferable to perform the mask alignment so that the position and the direction of the mask 7 can be confirmed at the orientation flat position, etc., in order to easily determine the ion implantation region.

The shape of each mask 7 may be a polygon or an irregular shape as long as it fits in the spot size of the laser beam to be described later.

When the mask 7 is provided at the edge of the substrate, the mask 7 is preferably not provided at the edge of the substrate, because the laser beam is not uniformly applied to the edge of the substrate in a laser beam irradiation step described later. Preferably, the mask 7 is provided at least 50 μm inside the substrate edge.

Next, hydrogen ions were implanted as shown in FIG. The implantation amount and implantation conditions of hydrogen ions are the same as in the first embodiment.

By removing the mask 7, a base material substrate is completed (FIG. 5D).

Next, as in the first embodiment, the GaN layer 2 is
The substrate was grown to a thickness of 00 μm, the substrate temperature was lowered to room temperature, and the substrate was taken out (FIG. 5E).

Next, a third step of substrate separation by laser beam irradiation is performed. Irradiation with laser light was performed at room temperature using an apparatus capable of two-dimensional optical axis scanning. The optical axis scan was performed at the laser irradiation position so that a region not ion-implanted was irradiated.

For example, the irradiation can be performed by the following method.

The region 1b into which the ions have not been implanted has the same arrangement as the mask 7 in FIG. 5B-2. Therefore, when a 10 Hz laser is used, the initial irradiation position is set to the region 1b of the substrate edge where ions are not implanted, and the substrate is not rotated. If the optical axis is scanned by, laser irradiation is performed in synchronization with the region 1b. Thereafter, by repeating the same irradiation, the entire surface of the substrate can be irradiated.

In this embodiment mode, the irradiation is performed from outside to inside the substrate. Since the region 1b is arranged six times symmetrically, a regular hexagon including the outermost region 1b is considered, and the optical axis scanning and laser beam irradiation are performed along the regular hexagon, and the inner hexagon is gradually irradiated. Just do it.

Depending on the size and the interval of the mask 7, the peripheral region 1b may not always be arranged in a hexagon, but the pattern of the mask 7 may be temporarily extrapolated and scanning may be performed assuming a hexagon. .

Since the region 1b can be regarded as three-fold symmetric, the optical axis may be scanned in an equilateral triangle.

Since the region 1b can be regarded as two-fold symmetrical, the pair of opposite sides of the hexagon may be alternately scanned from the outside to the inside.

FIG. 5F is a cross-sectional view during the laser irradiation step. For clarity, the hatching is not used. As in the third embodiment, Ga11 generated by the decomposition of the GaN layer 2 is formed, and a crack 12 is generated in the ion-implanted region 1a due to generation of nitrogen gas and stress concentration due to a difference in thermal expansion coefficient. .

On the other hand, the crack 12 does not extend in the region 1b into which the ions have not been implanted, and stops at the region 1b to stop the Ga.
Automatic peeling over the entire N layer 2 does not occur.

In the present embodiment, peeling completely occurred only after the laser irradiation was completed up to the center, and the GaN layer 2 was separated from the sapphire substrate 1 (FIG. 5 (g)).

Finally, Ga11 was dissolved with HCl and polished to remove the sapphire pieces 13, thereby obtaining a single GaN substrate 2 (FIG. 5 (h)).

The present invention is not limited to the shape of the ion implantation region and the laser irradiation method according to the present embodiment. It goes without saying that laser irradiation can be performed efficiently. More preferably, as in the present embodiment, by periodically arranging the regions 1b in which the ions are not implanted, it is possible to scan the optical axis more efficiently and irradiate the regions 1b with laser light. it can.

Also in the present embodiment, since the shape of the back surface is substantially constant, the back surface of a plurality of GaN substrates 2 can be polished by the same batch processing.

Embodiment 5 Hereinafter, Embodiment 5 will be described with reference to FIG. Embodiment 5 shows a modification of Embodiment 4 in which the laser irradiation method is changed.

The substrate 1 in FIG. 6A is sapphire similar to that of the fourth embodiment.

The step of implanting hydrogen ions into the sapphire substrate 1 is performed (FIGS. 6B, 6C, and 6D).

First, as shown in FIG. 6B, a pattern using a mask 7 is provided. The shape of the mask 7 is the same as that of the fourth embodiment. The center interval between adjacent masks 7 is 2 mm, and the diameter of each mask 7 is 0.5 mm.

Next, hydrogen ions were implanted as shown in FIG. The implantation amount and implantation conditions of hydrogen ions are the same as in the fourth embodiment. An ion-implanted region 1a and a non-ion-implanted region 1b were formed.

The base material substrate is completed by removing the mask 7 (FIG. 6D).

Next, as in the fourth embodiment, the GaN layer 2 is
The substrate was grown to a thickness of 00 μm, the substrate temperature was lowered to room temperature, and the substrate was taken out (FIG. 6E).

Next, a third step of separating the substrate by laser irradiation is performed. The optical system and the rotation mechanism used the apparatus of FIG. However, a KrF excimer laser device having a large laser power was used, the beam diameter was 5 mm, and the beam power was 3J. The pulse width is 30 ns. KrF
Also in the excimer laser device, the power required for sublimating GaN has almost the same tendency as that of the Nd: YAG laser. In the present embodiment, the beam diameter is 5 times, but the beam power is also 30 times, which is 25 times or more, which is the square of 5 times. Therefore, the light density is not lower than that of the first embodiment, and is sufficient for sublimating GaN.

In this embodiment, the intervals between the irradiation spots in the rotation direction and the pitch between the irradiation spots in the radial direction are set to 4 mm so that the irradiation spots overlap each other. According to this method, a plurality of non-implanted regions 1b are irradiated by one irradiation. Irradiation was performed from outside to inside.

FIG. 6F is a sectional view in the middle of the laser irradiation step. The GaN layer 2 is decomposed into Ga11 and nitrogen gas near the interface with the sapphire substrate 1 by the irradiation of the laser beam. Therefore, stress is concentrated in the ion-implanted region around the laser spot, and a crack 12 is generated. Ga
11 and sapphire substrate 1 and GaN 11 and GaN layer 2
The GaN layer 2 is separated from the sapphire substrate 1 because the bond with the sapphire substrate 1 is weak. The nitrogen is then released to the outside. However, sapphire not ion-implanted is so strong that it cannot be automatically peeled over the entire substrate.

For this reason, in the present embodiment, the GaN layer 2 was completely peeled off from the sapphire substrate 1 only when the entire region 1b not ion-implanted was irradiated (FIG. 6G).

Finally, Ga11 was removed with HCl to obtain a single GaN substrate 2 (FIG. 6 (h)).

In this embodiment, the entire substrate is irradiated, but the beam diameter of the laser is as large as 4 times and the beam area is as large as 16 times. Therefore, a plurality of areas 1b at a time
Has been irradiated. By irradiating a plurality of regions 1b with one irradiation, the number of irradiations can be reduced to about 1/4 in the fifth embodiment as compared with the fourth embodiment. In this embodiment mode, since the entire substrate is irradiated, there is no need for special alignment or the like, and the apparatus can be implemented with relatively inexpensive equipment other than the laser. Note that, even when a plurality of dots are irradiated by one irradiation, it is needless to say that peeling can be performed with a smaller number of irradiations by irradiating a laser in synchronization with the dots.

(Embodiment 6) A method of manufacturing a GaN substrate according to a sixth embodiment of the present invention will be described with reference to FIG. This embodiment is exactly the same as the first embodiment except that plasma irradiation is used instead of ion implantation.

The substrate 1 in FIG. 7A is the same sapphire substrate 1 as in the first embodiment.

First, a plasma irradiation step as a first step is performed.

The sapphire substrate 1 is exposed to oxygen plasma
Irradiation is performed for 0 minutes to obtain a region 1a in which atomic bonds have been cut by plasma irradiation (hereinafter, referred to as a plasma irradiation region 1a or simply a region 1a) (FIG. 7B). The irradiation time required for plasma irradiation varies depending on conditions such as plasma density and pressure. In the case of plasma irradiation, the state of the plasma greatly depends on the plasma generation method and apparatus, and cannot be unambiguously defined unlike ion implantation.

For example, in this embodiment, the electrode area 10
A parallel plate RF plasma with a 00 cm ² circular electrode,
The study is being conducted with an RF power of 200 W, an oxygen flow rate of 10 sccm, and a pressure of 5 Pa. At this time, the time required for plasma irradiation was 30 seconds to 2 hours. If the time is less than 30 seconds, the amount of weakening the atomic bonding force in the region irradiated with the plasma is insufficient, and if the time is longer than 2 hours, the surface is damaged, and it is difficult to grow a single-crystal GaN layer thereon. Becomes

Next, a second step of growing a nitride semiconductor layer is performed. A 200 μm-thick GaN layer 2 was grown by the same HVPE method as in the first embodiment, the substrate temperature was lowered to room temperature, and the substrate was taken out (FIG. 7C).

Next, a third step of separating the substrate by laser irradiation is performed. Regarding the laser irradiation, the method, apparatus and conditions are exactly the same as those in the first embodiment, and as shown in the schematic diagram of FIG. The rotation speed and the scanning speed of the optical axis were adjusted so that the light was released.

As in the first embodiment, when laser irradiation is continued, stress is concentrated near the center of the substrate when laser irradiation is performed about 1 cm from the periphery without laser irradiation to the center. Then, the GaN layer 2 was peeled off from the sapphire substrate 1, and the GaN substrate 2 on which the Ga11 and the sapphire pieces 13 were adhered was obtained (FIG. 7E).

Finally, Ga11 was dissolved by HCl,
Irregularities of the sapphire pieces 13 and the GaN layer 2 were removed by polishing to obtain a single GaN substrate 2 (FIG. 7 (f)).

As described above, it was shown that the same effect as ion implantation can be obtained even when the bonding of sapphire is weakened by plasma irradiation.

(Embodiment 7) Embodiment 7 will be described with reference to FIG. Embodiment 7 is exactly the same as Embodiment 6 except that the irradiation plasma is hydrogen or helium, argon, xenon, or krypton.

The substrate 1 shown in FIG. 8A has the same size as that of the sixth embodiment.
1) A planar sapphire substrate.

Five sapphire substrates 1 were prepared, and each of them was irradiated with plasma of hydrogen, helium, argon, xenon, and krypton for 10 minutes to form a plasma irradiation region 1a.
(FIG. 8 (b)).

Next, a second step of growing a nitride semiconductor layer is performed. Each sapphire substrate 1 was grown until the thickness of the GaN layer 2 became 200 μm as in the sixth embodiment, the substrate temperature was lowered to room temperature, and the substrates were taken out (FIG. 8C).

Next, a third step of separating the substrate by laser irradiation is performed. The same device and irradiation method as those in Embodiment 6 were used for laser irradiation. As a result, no matter which plasma is irradiated, the sapphire substrate 1
The aN layer 2 was peeled off, and the GaN substrate 2 on which the Ga11 and the sapphire pieces 13 were adhered was obtained (FIG. 8D).

Finally, Ga11 was dissolved with HCl, and the sapphire pieces 13 and the GaN layer 2 were removed by polishing to obtain the GaN substrate 2 (FIG. 8 (e)).

As described above, hydrogen, helium, argon,
It was confirmed that the same effect as oxygen plasma was obtained with xenon and krypton plasmas. Further, even if a device is formed on the obtained GaN substrate 2, there is no problem such as deterioration of characteristics such as when a heavy metal or the like is introduced into the nitride semiconductor device. The preferable irradiation time for plasma of hydrogen, helium, argon, xenon, and krypton is 30 seconds to 2 hours under the same circumstances as in the sixth embodiment.

Embodiment 8 Embodiment 8 will be described below with reference to FIG. Embodiment 8 is the same as Embodiment 3 except that plasma irradiation is performed instead of ion implantation in Embodiment 3, and SiO ₂ is used as a mask.

The substrate 1 shown in FIG. 9A is a (0001) plane sapphire having a diameter of 2 inches and a thickness of 700 microns, and the front and rear surfaces are mirror-finished.

A step of irradiating the sapphire substrate 1 with oxygen plasma is performed (FIGS. 9B, 9C and 9D).

First, as shown in FIG.
Providing a SiO ₂ mask 7. The shape of the SiO ₂ mask 7 is the same spiral spiral as the resist mask 7 in the third embodiment. The patterning of the SiO ₂ layer was performed by photolithography and etching using hydrofluoric acid or the like. The formation of the SiO ₂ layer is performed by RF sputtering. The SiO ₂ layer may be formed by another method such as thermal CVD or vapor deposition, or may be made of, for example, SiN or the like if it is a material or a manufacturing method that can withstand the plasma irradiation described below.

Next, as shown in FIG. 9C, oxygen plasma was applied for 10 minutes. Embodiment 6
Is the same as A plasma irradiation region 1a is formed in a portion of the main surface of the sapphire substrate 1 where the mask 7 does not exist. The portion where the mask 7 is present is hardly irradiated with oxygen plasma because the oxygen plasma is blocked, and a region 1b where atomic bonds are almost preserved (hereinafter referred to as a plasma non-irradiated region 1b).
Or simply referred to as a region 1b). In addition, since oxygen plasma etches the resist, SiO ₂ is used as a mask. However, it goes without saying that the resist may be used as a mask if the plasma is hydrogen or a rare gas.

By removing the mask 7, the base material substrate is completed (FIG. 9D).

Next, a second step of growing a nitride semiconductor layer is performed. In the same manner as in Embodiment 3, HVPE
The GaN layer 2 was grown to 200 μm by the method, the substrate temperature was lowered to room temperature, and the substrate was taken out (FIG. 9E).

Next, a third step of separating the substrate by laser irradiation is performed. Laser irradiation was performed on the non-plasma-irradiated region 1b using the same apparatus and method as in the third embodiment. Only when the laser irradiation has been completed to the center, complete automatic exfoliation occurs, and G11 in which Ga11 and sapphire pieces 13 are completely adhered from the sapphire substrate 1.
The aN layer 2 was peeled off (FIG. 9F).

Finally, Ga11 was dissolved with HCl, and the sapphire pieces 13 and the irregularities were removed by polishing to obtain a single GaN substrate 2 (FIG. 9 (g)).

As described above, it was confirmed that the same effect can be obtained by plasma irradiation instead of ion implantation.
In addition, the most preferable shape of the plasma non-irradiation area 1b is as follows.
Although a single-stroke pattern such as a spiral spiral of the present embodiment is possible, it goes without saying that a radial pattern, a stripe pattern, or another pattern may be used.

It should be noted that the plasma irradiation region 1a and the plasma non-irradiation region 1b have the same preferable area relationship as in ion implantation. When laser light irradiation is performed at room temperature, as a preferable area relationship, the area of the region 1a is preferably set to be 1/5 to 50 times the area of the region 1b.

Embodiment 9 Hereinafter, Embodiment 9 will be described with reference to FIG. Embodiment 9
This shows a case where plasma irradiation is performed instead of the ion implantation of the fourth embodiment.

The substrate 1 shown in FIG. 10A is sapphire similar to that of the fourth embodiment.

This sapphire substrate 1 is irradiated with oxygen plasma.

First, as shown in FIG.
A pattern using the _two- layer mask 7 is provided. The shape of the mask 7 is the same as in the fourth embodiment.

Next, oxygen plasma was applied as shown in FIG. The irradiation amount of oxygen plasma and injection conditions are the same as those in the sixth embodiment.

By removing the mask 7, a base material substrate is completed (FIG. 10D).

Next, as in the fourth embodiment, the GaN layer 2 is
The substrate was grown to a thickness of 00 μm, the substrate temperature was lowered to room temperature, and the substrate was taken out (FIG. 10E).

Next, a third step of separating the substrate by laser irradiation is performed. The laser irradiation method and the like are exactly the same as those in the fourth embodiment.

In this embodiment, the Ga1 is removed from the sapphire substrate 1 only after the irradiation of all the dots is completed.
1 and the GaN layer 2 to which the sapphire pieces 13 were adhered were peeled off (FIG. 10F).

Finally, the Ga11 was dissolved using HCl, and the sapphire pieces 13 and the irregularities were removed by polishing to obtain a single GaN substrate 2 (FIG. 10 (g)).

As described above, the same effect as the ion implantation was obtained even when the periodic plasma non-irradiation region was used.

(Embodiment 10) Hereinafter, Embodiment 10 will be described with reference to FIG. Embodiment 1
0 indicates the case where plasma irradiation is performed instead of the ion implantation of the fifth embodiment.

The substrate 1 shown in FIG. 11A is sapphire similar to that of the fifth embodiment.

A step of irradiating the sapphire substrate 1 with oxygen plasma is performed (FIGS. 11B, 11C and 11D).

[0162] First, SiO ₂ as shown in FIG. 11 (b)
A pattern by the mask 7 is provided. The shape of the mask 7 is
As in the fifth embodiment, the center interval between adjacent dots is 2
mm and the diameter of the dot were 0.5 mm.

Next, as shown in FIG. 11C, oxygen plasma was applied for 10 minutes. The irradiation conditions of the oxygen plasma are the same as in the sixth embodiment. The plasma irradiation area 1a and the plasma non-irradiation area 1b were formed.

The base material substrate is completed by removing the mask 7 (FIG. 11D).

Next, as in the fifth embodiment, the GaN layer 2 is
The substrate was grown to a thickness of 00 μm, the substrate temperature was lowered to room temperature, and the substrate was taken out (FIG. 11E).

Next, a third step of separating the substrate by laser irradiation is performed. Just as in the fifth embodiment, K
Using an rF excimer laser, the sapphire substrate 1
The GaN layer 2 to which the GaN layer 11 adhered could be peeled off (FIG. 11).
(F)).

Finally, the Ga11 on the back surface was dissolved with HCl to obtain a single GaN substrate 2 (FIG. 11 (g)).

As described in the sixth to tenth embodiments, almost the same effects as those of the ion implantation can be obtained by the plasma irradiation. In the case of plasma irradiation, although there is a problem that conditions such as a preferable irradiation time slightly change depending on the apparatus due to the dependence of the plasma generation apparatus on the apparatus, etc., the atomic bond of sapphire is weakened by an apparatus relatively simpler than ion implantation. There is a merit that can be.

In the above embodiment, GaN
AlGaN layer, InGaN layer, AlIn
By growing a GaN layer, AlGaN and In
It goes without saying that a GaN or AlInGaN substrate can be obtained.

In the above embodiment, ions are implanted into a base material substrate such as sapphire. However, ion implantation is performed using a substrate provided with a GaN layer or the like on sapphire or the like in advance as a base material substrate. Needless to say, this is acceptable. That is, a GaN layer is grown on sapphire and G
aN / sapphire substrate is ion-implanted and G
It goes without saying that the same effect can be obtained even if the laser irradiation is performed after the aN layer is grown thick.

[0171]

As described above, according to the method for manufacturing a nitride semiconductor substrate of the present invention, a nitride semiconductor substrate free from cracks and cracks is formed by peeling a nitride semiconductor layer from a base material substrate by laser irradiation. Can be manufactured with good mass productivity.

[Brief description of the drawings]

FIGS. 1A to 1C are cross-sectional views illustrating a method for manufacturing a nitride semiconductor substrate according to a first embodiment of the present invention; FIG. View showing a method of manufacturing a semiconductor substrate

FIG. 2 is a cross-sectional view illustrating a laser irradiation mechanism according to the first embodiment of the present invention.

FIG. 3 is a cross-sectional view illustrating a method for manufacturing a nitride semiconductor substrate according to a second embodiment of the present invention.

FIGS. 4 (a), (b-1), (c) to (h) are cross-sectional views illustrating a method for manufacturing a nitride semiconductor substrate according to a third embodiment of the present invention. Top view showing the method for manufacturing a nitride semiconductor substrate in form 3.

FIGS. 5 (a), (b-1), (c) to (h) are cross-sectional views illustrating a method for manufacturing a nitride semiconductor substrate according to a fourth embodiment of the present invention. Top view showing a method for manufacturing a nitride semiconductor substrate in form 4.

FIG. 6 is a sectional view illustrating a method for manufacturing a nitride semiconductor substrate according to a fifth embodiment of the present invention.

7 (a) to 7 (c), (e), (f) are cross-sectional views illustrating a method for manufacturing a nitride semiconductor substrate according to a sixth embodiment of the present invention. (D) nitridation according to the sixth embodiment of the present invention. View showing a method of manufacturing a semiconductor substrate

FIG. 8 is a sectional view illustrating a method for manufacturing a nitride semiconductor substrate according to a seventh embodiment of the present invention.

FIG. 9 is a sectional view illustrating a method for manufacturing a nitride semiconductor substrate according to an eighth embodiment of the present invention.

FIG. 10 is a sectional view illustrating a method for manufacturing a nitride semiconductor substrate according to a ninth embodiment of the present invention.

FIG. 11 is a cross-sectional view illustrating a method for manufacturing a nitride semiconductor substrate according to a tenth embodiment of the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 base material substrate 1 a region where atomic bonds are cut 1 b region where atomic bonds are preserved 2 nitride semiconductor layer 3 laser device 4 rotation mechanism 5 scan lens 6 focusing means 7 mask 8 laser irradiation position 10 laser beam 11 Ga 12 Crack 13 Sapphire pieces

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) // B23K 26/00 B23K 26/00 HF term (reference) 4E068 CA03 CE03 DA09 4K029 AA04 CA10 5F041 AA41 AA43 CA64 CA71 CA74 CA77 5F045 AB14 AC12 AC13 AD13 AD14 AF09 BB13 CA09 CA11 HA05 HA18 5F072 AA06 AB02 HH07 MM17 QQ02 YY06

Claims (13)

[Claims] A first step of providing a region on a main surface of a base material substrate in which an atomic bond of a material constituting the base material substrate has been cut;
A nitride semiconductor substrate, comprising: a second step of forming a nitride semiconductor layer on the base material substrate; and a third step of irradiating a laser beam to an interface between the base material substrate and the nitride semiconductor layer. Manufacturing method. 2. The method for manufacturing a nitride semiconductor substrate according to claim 1, wherein the region in which the atomic bonds have been cut is an ion-implanted region. 3. The first step includes providing a first region implanted on the main surface of the base material substrate and a second region having a smaller amount of ion implantation than the first region or not ion-implanted. 2. The method according to claim 1, wherein the third step is a step of irradiating at least the second region with the laser light. 3. 4. The apparatus according to claim 3, wherein said second area is linearly continuous, and said third step is a step of scanning said laser beam along said second area. The method for producing a nitride semiconductor substrate according to the above. 5. The method according to claim 1, wherein the second area is disposed in a plurality of places, and the third step is to scan the optical axis of the laser light in synchronization with the second area while scanning the laser light. The method for manufacturing a nitride semiconductor substrate according to claim 3, wherein the method is a step of performing pulse irradiation. 6. The method according to claim 1, wherein the second area is provided in a plurality of areas, and the third step is a step of irradiating the plurality of second areas by one irradiation of the laser light. The method for manufacturing a nitride semiconductor substrate according to claim 3. 7. The method for manufacturing a nitride semiconductor substrate according to claim 2, wherein said base material substrate is sapphire, and ions to be implanted are hydrogen or silicon. 8. The method for manufacturing a nitride semiconductor substrate according to claim 1, wherein the region where the atomic bonds are broken is a plasma irradiation region. 9. The first step includes providing a first region on the main surface of the base material substrate irradiated with plasma, and a second region having a smaller or smaller amount of plasma irradiation than the first region. 2. The method according to claim 1, wherein the third step is a step of irradiating at least the second region with the laser light. 3. 10. The second region is linearly continuous,
The method according to claim 9, wherein the third step is a step of scanning the laser beam along the second region. 11. The method according to claim 11, wherein the second region is disposed in a plurality of positions, and the third step includes scanning the optical axis of the laser beam in synchronization with the second region while scanning the laser beam. The method for manufacturing a nitride semiconductor substrate according to claim 9, wherein the method is a step of performing pulse irradiation. 12. The method according to claim 11, wherein the second area is provided in a plurality of areas, and the third step is a step of irradiating the plurality of second areas by one irradiation of the laser light. The method for manufacturing a nitride semiconductor substrate according to claim 9. 13. The method for manufacturing a nitride semiconductor substrate according to claim 8, wherein said base material substrate is sapphire, and plasma to be irradiated is hydrogen, oxygen, or a rare gas. .