JP4595207B2 - Manufacturing method of nitride semiconductor substrate - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for manufacturing a nitride semiconductor substrate used for a visible light emitting diode device and a blue-violet laser device, and a base material substrate for manufacturing the nitride semiconductor substrate.
[0002]
[Prior 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. As a substrate for growing a nitride semiconductor, a sapphire substrate (for example, disclosed in Japanese Patent No. 3091593) is conventionally known, but in the growth of a nitride semiconductor on a different substrate such as sapphire, a nitride semiconductor and It is known that a difference in thermal expansion coefficient from a different material substrate causes warpage of the substrate, generation of cracks, and deterioration of crystallinity associated therewith.
[0003]
Thus, in recent years, attempts have been made to solve the above problems by fabricating devices on nitride semiconductor substrates. As one method for manufacturing a nitride semiconductor substrate, a nitride semiconductor layer is formed thick on a base material substrate, and the nitride semiconductor layer is locally heated and sublimated by a laser beam at the base material substrate interface, thereby generating a base material. It has been studied to remove the nitride semiconductor layer from the substrate.
[0004]
[Problems to be solved by the invention]
However, when peeling is performed using laser light, the irradiation size of the laser light is smaller than the area of the substrate, and it is necessary to scan the laser light. At this time, the following problems existed.
[0005]
During the scanning of the laser beam, a part of the nitride semiconductor layer and the base material substrate is peeled off and remains in contact with the other part. At that time, the nitride semiconductor layer and the base material substrate are in contact with each other. There is a problem that stress concentrates on the portion where the contact remains, and cracks occur in the nitride semiconductor layer. Therefore, it has been difficult to produce a nitride semiconductor substrate with high yield by laser light irradiation near room temperature. In order to avoid this, a technique for raising the substrate temperature is known. However, it takes time to raise and lower the substrate, and there is a problem in mass productivity.
[0006]
Furthermore, since the laser beam is condensed to be 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 a light 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 beam diameter of the laser light is small and condensed. . Therefore, the beam diameter is smaller than the substrate area, and it is necessary to scan with laser light. 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 time, and in addition, so-called batch processing is not possible in which many wafers are processed at once. . Therefore, it has been necessary to provide a method of performing laser irradiation more efficiently than in the past in the irradiation process while preventing the occurrence of cracks.
[0007]
In view of the above, the present invention significantly reduces the time required for laser light irradiation in the manufacture of a nitride semiconductor substrate by laser light irradiation, and provides a nitride semiconductor substrate without generating cracks in the nitride semiconductor layer. It aims to provide a means to obtain.
[0008]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, a method for manufacturing a nitride semiconductor substrate according to the present invention comprises the following configuration.
[0009]
The method for manufacturing a nitride semiconductor substrate according to the present invention is provided on a main surface of a base material substrate. By hydrogen or silicon ion implantation A first step of providing a region in which an atomic bond of a material constituting the base material substrate is cut; a second step of forming a nitride semiconductor layer on the base material substrate; and the base material substrate and the nitriding A third step of irradiating the interface with the physical semiconductor layer with laser light
It is characterized by having.
[0010]
By doing so, the stress generated in the nitride semiconductor layer during the laser irradiation is released by peeling off the region where the atomic bond is broken, so that cracks and cracks are generated in the nitride semiconductor layer. There is nothing. Furthermore, since the nitride semiconductor layer can be peeled off without laser scanning the entire surface of the nitride semiconductor layer by peeling the nitride semiconductor layer due to the stress described above, the mass productivity of the nitride semiconductor substrate is improved. be able to.
[0012]
In the method of manufacturing a nitride semiconductor substrate according to the present invention, the first step includes a first region ion-implanted into the main surface of the base material substrate and a smaller amount of ion implantation than the first region or no ion implantation. Preferably, the second region is provided, and the third step is preferably a step of irradiating at least the second region with the laser light. By doing so, the nitride semiconductor layer can be more reliably peeled off without irradiating the entire surface of the nitride semiconductor layer, so that the mass productivity of the nitride semiconductor substrate can be improved.
[0013]
In such a configuration, it is preferable that the second region with a small ion implantation amount is continuous in a linear shape, and the third step is a step of scanning the laser beam along the second region. By doing so, the nitride semiconductor layer can be peeled off by efficient scanning of the optical axis.
[0014]
In such a configuration, the second region with a small amount of ion implantation is disposed in a plurality of locations, and the third step scans the optical axis of the laser beam in synchronization with the second region. However, the step of irradiating the laser beam with pulses is preferable. By doing so, the nitride semiconductor layer can be peeled off by scanning the optical axis efficiently using a pulse laser.
[0015]
In such a configuration, the second region with a small amount of ion implantation is disposed in a plurality of locations, and the third step irradiates the plurality of second regions by one irradiation of the laser beam. It is preferable to set it as a process. By doing so, the nitride semiconductor layer can be peeled in a shorter irradiation time.
[0016]
In the method for manufacturing a nitride semiconductor substrate of the present invention, the base material substrate is sapphire and Do . By doing in this way, the sapphire atom bond can be cut and a region with a weak atom bond can be formed without causing contamination that deteriorates the characteristics of the nitride semiconductor layer.
[0017]
Manufacturing method of nitride semiconductor substrate of the present invention On the main surface of the base material substrate. By plasma irradiation A first step of providing a region where an atomic bond of a material constituting the base material substrate is cut, a second step of forming a nitride semiconductor layer on the base material substrate, and the base material substrate, And a third step of irradiating the interface with the nitride semiconductor layer with laser light. .
[0018]
In the method for manufacturing a nitride semiconductor substrate according to the present invention, the first step includes a first region irradiated with plasma on a main surface of the base material substrate, and a plasma irradiation amount is smaller than that of the first region or plasma irradiation is not performed. Preferably, the second region is provided, and the third step is preferably a step of irradiating at least the second region with the laser light. By doing so, the nitride semiconductor layer can be more reliably peeled off without irradiating the entire surface of the nitride semiconductor layer with laser, so that the mass productivity of the nitride semiconductor substrate can be improved.
[0019]
In such a configuration, it is preferable that the second region with a small amount of plasma irradiation is linear, and the third step is a step of scanning the laser light along the second region. By doing so, the nitride semiconductor layer can be peeled off by efficient scanning of the optical axis.
[0020]
In such a configuration, the second region with a small amount of plasma irradiation is disposed in a plurality of locations, and the third step scans the optical axis of the laser beam in synchronization with the second region. However, the step of irradiating the laser beam with pulses is preferable. By doing so, the nitride semiconductor layer can be peeled off by scanning the optical axis efficiently using a pulse laser.
[0021]
In such a configuration, the second region with a small amount of plasma irradiation is disposed in a plurality of dispersed manners, and the third step irradiates the plurality of second regions by one irradiation of the laser beam. It is preferable to set it as a process. By doing so, the nitride semiconductor layer can be peeled in a shorter irradiation time.
[0022]
In the method for manufacturing a nitride semiconductor substrate according to the present invention, the base material substrate is sapphire. Do . By doing in this way, the sapphire atom bond can be cut and a region with a weak atom bond can be formed without causing contamination that deteriorates the characteristics of the nitride semiconductor layer.
[0023]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0024]
(Embodiment 1)
A method for manufacturing a GaN substrate in the first embodiment of the present invention will be described with reference to FIG.
[0025]
The substrate 1 in FIG. 1A is sapphire (a single crystal of aluminum oxide) having a diameter of 2 inches and a thickness of 700 microns, and has a mirror finish on both the front and back surfaces. The surface orientation is the (0001) plane.
[0026]
Since the substrate 1 is made of sapphire, and the band gap of sapphire is 8.7 eV, light having a wavelength larger than 142.5 nm of energy corresponding to the band gap is transmitted. Therefore, KrF excimer laser light having a wavelength of 248 nm and third harmonic light of an Nd: YAG laser having a wavelength of 355 nm can be transmitted.
[0027]
First, an ion implantation process which is a first process is performed.
[0028]
Hydrogen ions are implanted into the sapphire substrate 1 (FIG. 1B). By ion implantation, a region 1a in which atomic bonds are cut (hereinafter referred to as ion-implanted region 1a or simply region 1a until Embodiment 5) is formed. Injection volume is 1x10 ¹⁶ ion / cm ² The implantation was performed by tilting the substrate by 5 °. The acceleration voltage was 200 keV. By implanting hydrogen into the sapphire substrate, the bond between Al and O, which are constituent elements of sapphire, is cut. Hydrogen may be introduced between the cut atoms. As a result, the average atomic bonding force of the ion-implanted region can be relatively weak compared to the region where ions are not implanted.
[0029]
In addition, when the injection amount is small, the amount of bond breakage between atoms near the substrate surface and weakening of the atomic bond is reduced, and the separation of the nitride semiconductor layer 2 and the base material substrate 1 during the laser irradiation described later is efficient. It is difficult to do it automatically. On the other hand, when the amount of implantation is large, a part of the base substrate is peeled off before the substrate surface grows the nitride semiconductor layer, and the fine particles peeled off reattach to the surface, adversely affecting the growth of the nitride semiconductor layer. May affect. For this reason, when considering the range of preferable injection amount, 1 × 10 ¹⁴ ion / cm ² To 1x10 ¹⁸ ion / cm ² It is.
[0030]
In addition, as for the implantation angle at the time of ion implantation, in order to prevent hydrogen implanted due to the channeling effect from being implanted deeply, ions are preferably incident from a surface inclined by 2 ° or more from the (0001) plane of sapphire.
[0031]
The acceleration voltage at the time of ion implantation is not particularly limited. However, if the acceleration voltage is low, damage near the surface of the sapphire increases. Therefore, the acceleration voltage is preferably 20 keV or more.
[0032]
Next, a nitride semiconductor layer growth step, which is a second step, is performed. GaN was grown by a hydride vapor phase epitaxy method (hereinafter referred to as HVPE method) using ammonia, GaCl produced by reacting Ga metal and HCl at a high temperature of about 900 ° C. as raw materials. The pressure was grown under atmospheric pressure.
[0033]
In order to increase the nucleation density of GaN on sapphire, the substrate temperature is maintained at 1000 ° C. and only GaCl is supplied for 15 minutes prior to the growth of GaN (this process is hereinafter referred to as GaCl treatment). For the purpose of increasing the nucleation density, the sapphire may be nitrided with a low temperature buffer layer or ammonia instead of the GaCl treatment, or a combination thereof may be used.
[0034]
After the GaCl treatment, ammonia is introduced to start the growth of the GaN layer 2. Growth was performed until the thickness of the GaN layer 2 reached 200 μm, the substrate temperature was lowered to room temperature, and the substrate was taken out (FIG. 1C).
[0035]
As a result of growing the GaN layer 2 on the sapphire substrate 1 at a high temperature and lowering the temperature to room temperature, warping due to the difference in thermal expansion coefficient between sapphire and GaN occurs. Since sapphire has a larger thermal expansion coefficient than GaN, the GaN layer 2 side is convex and warps. In the present embodiment, the radius of curvature is about 60 cm. In the present embodiment, since the base material substrate 1 is thicker than the GaN layer 2, the radius of curvature is large and the warp is not so great as to cause a crack.
[0036]
Since the sapphire substrate 1 is ion-implanted, the bonds of Al and O are cut, and these elements are likely to diffuse into the GaN layer 2 at a high temperature of 1000 ° C. during growth. Al in GaN forms an isoelectronic trap, and 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 in the device active region can be sufficiently reduced.
[0037]
Next, a substrate separation step by laser light irradiation, which is a third step, is performed. Laser irradiation was performed using the optical system and stage shown in FIG. When irradiating the GaN layer 2 with the laser beam 10 emitted from the laser device 3, the rotation mechanism 4 rotates the laser beam 10 and scans the optical axis with the scan lens 5, thereby irradiating the entire substrate with the laser beam. It has a configuration that makes it possible. Further, the spot diameter of the laser beam on the GaN layer 2 can be controlled by the light condensing means 6.
[0038]
The stage may be provided with heating means such as a resistance heater for adjusting the warp of the base material substrate 1. Further, a cooling means such as a Peltier element for promoting peeling due to a difference in thermal expansion coefficient may be provided.
[0039]
The laser device 3 is a device that generates the third harmonic laser beam of the Nd: YAG laser beam. The pulse frequency was 10 Hz, and the pulse width of one pulse was 5 ns. Using the condensing means 6, the laser beam is focused on the GaN layer 2 in a circular shape with a diameter of 1 mm. The energy per pulse was 0.1 J in the sapphire substrate 1.
[0040]
The energy of the laser that reaches the GaN layer 2 is attenuated by receiving reflection from the surface of the substrate 1 and the interface between the substrate 1 and the GaN layer 2 and absorption by defects in the substrate 1. Therefore, it is necessary to adjust the energy per one pulse or the beam diameter so that GaN is decomposed depending on the substrate thickness, the finish of the back surface of the substrate, the substrate characteristics, and the like. The beam energy density required for GaN sublimation decreases as the substrate temperature increases. Further, since the peak energy increases as the pulse width decreases, the peak energy changes depending on the energy density per pulse necessary for GaN sublimation. For pulses of several ns to several tens of ns near room temperature, approximately 0.1 J / cm ² That's it. In the present embodiment, sufficient pulse energy is obtained even in consideration of scattering and attenuation.
[0041]
Since the GaN layer 2 is warped, it is preferable to control the focal position according to the irradiation position, for example, by controlling the light converging means 6 so that the size of the laser light 10 at the position of the GaN layer 2 is constant.
[0042]
When the focal position is not controlled by the irradiation position, it is preferable to make the focal length of the light converging means 6 close to the radius of curvature of the GaN layer. By doing in this way, the size in the position of the GaN layer 2 of the laser beam 10 can be made constant without using a special lens.
[0043]
The laser beam 10 was applied to the GaN layer 2 from the sapphire substrate 1 side. The laser irradiation was performed in a room temperature atmosphere (about 20 ° C.) without particularly heating and cooling the substrate. Laser irradiation was performed from the peripheral part toward the central part. 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 distance in the rotation direction and the center distance 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 the irradiation was performed. As an adjustment method, the interval in the rotation direction of the spots can be changed by changing the rotation speed of the substrate or the pulse frequency of the laser device 3. Further, the radial interval can be changed by changing the scanning speed of the optical axis in accordance with the rotational speed.
[0044]
The GaN layer 2 irradiated with the laser beam 10 absorbs the laser beam 10 in the vicinity of the interface with the sapphire substrate 1 and is heated. Since the pulse width is as short as 5 ns, the heated portion is concentrated in the vicinity of 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.
[0045]
FIG.1 (e) is sectional drawing in the middle of an irradiation process. For the sake of clarity, FIG. 1 (e) is not hatched.
[0046]
A portion of the GaN layer 2 that has been irradiated with the laser beam 10 has metallic Ga11. Metal Ga is a liquid at 25 ° C. or higher, and is very soft even at 25 ° C. or lower. Therefore, the bond between the sapphire substrate 1, Ga 11 and GaN layer 2 is about the surface tension and is extremely weak. For this reason, the stress due to the difference in thermal expansion coefficient concentrates on the portion not irradiated with the laser.
[0047]
Further, decomposition of the GaN layer 2 generates nitrogen gas together with the metal Ga11. The generated nitrogen pressure is applied in the direction of peeling the sapphire substrate 1 and the GaN layer 2. In the region not irradiated with the laser, the bonds between the atoms in sapphire are weakened by ion implantation, so that it cannot withstand the stress concentration due to the difference in thermal expansion coefficient and the pressure of nitrogen, and the crack 12 is formed in the ion implantation region 1a. Arise. At this time, nitrogen generated by the decomposition of the GaN layer 2 is diffused through the crack 12.
[0048]
From the above situation, the ion implantation amount is 1 × 10. ¹⁴ ion / cm ² To 1x10 ¹⁸ ion / cm ² Therefore, the crack is generated only in the ion implantation region 1a having a weak atomic bond, and the sapphire substrate 1 and the GaN layer 2 are not cracked or cracked.
[0049]
Further, when the laser beam irradiation process is continued, the stress is concentrated near the center of the substrate at the stage where the laser is irradiated about 1 cm from the surroundings without the laser irradiation to the center, and the crack 12 is formed in the ion implantation region 1a. Extended to the whole. As a result, the GaN layer 2 was peeled from the sapphire substrate 1 (FIG. 1 (f)). Due to the peeling, the warpage of both the sapphire substrate 1 and the GaN layer 2 was eliminated.
[0050]
In this manner, the automatic peeling due to internal stress without performing laser beam irradiation or the like is referred to as automatic peeling. Ga11 and sapphire pieces 13 are attached to the main surface on the back side of the GaN layer 2.
[0051]
Note that the point at which the GaN layer 2 is peeled varies depending on the ion implantation amount, the interval between irradiation spot centers, the pitch, and the like. As the ion implantation amount was larger and the laser was more densely irradiated, automatic peeling occurred at an earlier stage of laser irradiation. Further, when the substrate is cooled from room temperature with a Peltier element or liquid nitrogen, automatic peeling occurs at an early stage.
[0052]
When irradiating the entire substrate as in the case of conventional GaN peeling by laser irradiation, a 1 mm diameter circular beam requires a pitch or spot interval of about 0.8 mm or less, and irradiation of one wafer is performed. It takes about 5 minutes. In addition, it is necessary to add time for raising and lowering the substrate temperature to this time.
[0053]
On the other hand, as in the present embodiment, in the irradiation with the spot interval or pitch separated, the number of laser irradiation spots can be reduced to approximately 1/6 even if the laser irradiation is performed up to the center of the substrate. The time for irradiating the wafer can be significantly reduced to about 50 seconds. In addition, in the present embodiment, the GaN layer 2 starts to be peeled off automatically when irradiated from the periphery to the inside by about 1 cm, and the scan time is only about 20 seconds.
[0054]
Finally, Ga11 was dissolved by immersing the GaN layer 2 in a 35% HCl solution for 30 minutes. Moreover, the sapphire piece 13 and the irregularities formed by the presence of Ga11 were removed by polishing, and the GaN substrate 2 consisting of a single element was obtained (FIG. 1 (g)).
[0055]
In the first embodiment, in place of the Nd: YAG laser light, light that is absorbed by GaN, passes through sapphire, and has sufficient power to sublimate GaN may be used. Needless to say. Examples of such a light source include a KrF excimer laser (248 nm), an ArF excimer laser (193 nm), a XeCl excimer laser (308 nm), a XeF excimer laser (351 nm), and a nitrogen laser (337 nm).
[0056]
In this embodiment, the laser beam is irradiated without overlapping, but it goes without saying that the GaN substrate 2 can be obtained without generation of cracks and cracks even when the laser beam is irradiated repeatedly.
[0057]
(Embodiment 2)
Hereinafter, the second embodiment will be described with reference to FIG. The second embodiment is exactly the same as the first embodiment except that the implanted ions are replaced with hydrogen to form silicon.
[0058]
The substrate 1 in FIG. 3A is a (0001) plane sapphire having a diameter of 2 inches and a thickness of 700 microns, and has a mirror finish on both the front and back surfaces.
[0059]
Silicon ions are implanted into the sapphire substrate 1 (FIG. 3B). The region 1a is a silicon implantation region. Injection volume is 1x10 ¹⁶ ion / cm ² The implantation was performed by tilting the substrate by 5 °. The acceleration voltage was 200 keV. By ion-implanting silicon into the sapphire substrate, like hydrogen, the bond between Al and O, which are constituent elements of sapphire, is broken, or silicon is introduced between atoms. As a result, it is possible to form a region in which the average atomic bonding force of the ion-implanted region is relatively weaker than that in a region where ions are not implanted.
[0060]
As in the case of hydrogen ions, a preferable range of silicon ion implantation amount is 1 × 10 ¹⁴ ion / cm ² To 1x10 ¹⁸ ion / cm ² It is.
[0061]
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 silicon implanted by the channeling effect from being implanted deeply.
[0062]
The acceleration voltage at the time of ion implantation is not particularly limited. However, 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 tends to concentrate near the surface, and is preferably 50 keV or more.
[0063]
Next, a nitride semiconductor layer growth step, which is a second step, is performed. GaN was grown by the HVPE method using ammonia, Ga metal and HCl as raw materials. After the GaCl treatment for 15 minutes, ammonia is introduced to grow the GaN layer 2. Growth was performed until the thickness of the GaN layer 2 reached 200 μm, the substrate temperature was lowered to room temperature, and the substrate was taken out (FIG. 3C).
[0064]
Next, a substrate separation step by laser irradiation, which is a third step, is performed. For the laser irradiation, the same apparatus and irradiation method as those in Embodiment 1 were used. As a result, the GaN layer 2 was peeled from the sapphire substrate 1 (FIG. 3 (d)). Ga11 and sapphire pieces 13 were attached to the back surface of the GaN layer 2.
[0065]
Finally, Ga11 was dissolved with HCl, and the unevenness of the sapphire piece 13 and the GaN layer 2 was removed by polishing to obtain a single GaN substrate 2 (FIG. 3 (e)).
[0066]
From the 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, leading to deterioration of characteristics. Needless to say, such problems do not occur with silicon or hydrogen.
[0067]
(Embodiment 3)
The third embodiment will be described below with reference to FIG. Embodiment 3 shows an example in which linear patterning is performed during ion implantation.
[0068]
The substrate 1 in FIG. 4A is (0001) plane sapphire having a diameter of 2 inches and a thickness of 700 microns, and has a mirror finish on both the front and back surfaces.
[0069]
A step of implanting hydrogen ions into the sapphire substrate 1 is performed (FIGS. 4B, 4C, and 4D).
[0070]
First, a resist mask 7 is provided as shown in FIG. The shape of the mask 7 is a spiral spiral as shown in the schematic diagram of FIG. The pitch of the spiral spiral was 2 mm and the width was 0.5 mm.
[0071]
Note that, after 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 spiral can be confirmed at the orientation flat position or the like.
[0072]
Next, hydrogen ions were implanted as shown in FIG. The amount of hydrogen ions implanted is 1 x 10 ¹⁶ ion / cm ² The implantation was performed by tilting the substrate by 5 °. The acceleration voltage was 200 keV. In the main surface of the sapphire substrate 1 where the mask 7 does not exist, a region 1a into which ions are implanted is formed. In the portion where the mask 7 is present, hydrogen ions are blocked, so that the amount of hydrogen ions implanted is reduced. More preferably, almost no implantation is performed and the region 1b in which atomic bonds are substantially preserved (hereinafter referred to as implementation). Up to Form 5, regions 1b that are not ion-implanted or simply referred to as region 1b) are formed.
[0073]
By removing the mask 7, the base material substrate is completed (FIG. 4D).
[0074]
Next, a nitride semiconductor layer growth step, which is a second step, is performed. The GaN layer 2 was grown to 200 μm by the HVPE method in the same manner as in the first embodiment, the substrate temperature was lowered to room temperature, and the substrate was taken out (FIG. 4E).
[0075]
Next, a substrate separation step by laser irradiation, which is a third step, is performed. Laser irradiation was performed at room temperature using the same apparatus as in the first embodiment. Laser irradiation was performed from the periphery toward the center while adjusting the irradiation start position, the rotation speed, and the scanning speed of the optical axis so that the region 1b that was not ion-implanted was irradiated without gaps. 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 is constant. Also, the scanning speed of the optical axis is adjusted so that the pitch of the substrate is 2 mm.
[0076]
Although there is no significant change in appearance in the ion-implanted region 1a, the ion implantation position has a slightly different refractive index and absorption coefficient, so that it can be confirmed by adjusting how light is applied even with visible light. Is possible. Since the absorption coefficient at the ion implantation position becomes remarkable in the ultraviolet region of about 200 nm, the determination becomes easier if it is confirmed by a camera that detects ultraviolet rays.
[0077]
FIG. 4F is a cross-sectional view during the irradiation process. To clearly show the figure, hatching is not applied. Ga11 formed by the decomposition of the GaN layer 2 is formed in the region irradiated with the laser beam. Further, a crack 12 is generated in the ion-implanted region 1a due to the pressure of nitrogen gas generated by the decomposition of the GaN layer 2 and the stress concentration due to the difference in thermal expansion coefficient.
[0078]
On the other hand, since the sapphire is strong in the region 1b where ions are not implanted, the crack 12 does not extend. Therefore, even if the substrate 12 is irradiated with the laser beam and the crack 12 is generated, the crack 12 stops in the region 1 b and does not lead to automatic peeling over the entire GaN layer 2.
[0079]
In the present embodiment, complete peeling occurred only when laser irradiation was completed to the center, and the GaN layer 2 was separated from the sapphire substrate 1 (FIG. 4G).
[0080]
Finally, Ga11 was dissolved by HCl, and the irregularities on the back surface of the sapphire piece 13 and the GaN layer 2 were removed by polishing to obtain the GaN substrate 2 (FIG. 4 (h)).
[0081]
Note that when the GaN layer 2 is automatically peeled off during laser irradiation as in the first embodiment, the stage at which the peeling occurs is not constant, so the shape of the sapphire piece 13 attached to the back surface of the GaN layer 2 is It will be different every time. In the polishing process of the back surface for removing the sapphire piece 13 on the back surface of the GaN layer 2, the back surface of the GaN layer 2 that has been peeled off automatically is polished one by one under the conditions according to the individual GaN layer 2 and the sapphire piece 13. Need to do. On the other hand, in the present embodiment, since the back surface has a substantially constant shape, it is possible to polish the back surface of the plurality of GaN substrates 2 by the same batch process. Therefore, the construction method of this embodiment is suitable for mass production.
[0082]
Note that it is preferable that the region 1b in which the ion implantation is not performed has a continuous shape because the laser beam can be easily scanned. For example, a pattern such as a radial pattern or a stripe pattern is preferable. Furthermore, it is most preferable to use a pattern that allows one-stroke writing such as the spiral spiral of the present embodiment.
[0083]
Note that there is a preferable area relationship between the region 1a in which ion implantation is performed and the region 1b in which ion implantation is not performed. Specifically, when the region 1b is too narrow as compared with the region 1a, peeling becomes difficult to occur, and it becomes difficult to obtain a nitride semiconductor wafer. On the contrary, when the region 1b is too wide as compared with the region 1a, since the area where the automatic peeling is possible, that is, the area of the region 1a is small, the stress is not released by the automatic peeling, and the GaN layer 2 is irradiated during the irradiation. Cracks and cracks may occur. Under such circumstances, in the room temperature irradiation, the preferable area relationship is that the area of the region 1a is between 1/5 and 50 times the area of the region 1b.
[0084]
(Embodiment 4)
Hereinafter, the fourth embodiment will be described with reference to FIG. Embodiment 4 shows an example in which patterning is performed in a plurality of dispersed shapes during ion implantation.
[0085]
The substrate 1 in FIG. 5A is sapphire similar to that in the first embodiment.
[0086]
A step of implanting hydrogen ions into the sapphire substrate 1 is performed (FIGS. 5B, 5C, and 5D).
[0087]
First, as shown in FIG. 5B-1, a pattern using a mask 7 is provided. The shape of the mask 7 is a circular dot shape as shown in the schematic diagram of FIG. A dot by the mask 7 is positioned at each vertex of an equilateral triangle having a side of 2 mm covering the plane. The distance between the centers of adjacent masks 7 is 2 mm, and the diameter of one mask 7 is 0.5 mm.
[0088]
Note that, after removing the mask 7 after ion implantation, it is preferable to perform mask alignment so that the position and direction of the mask 7 can be confirmed at the orientation flat position, etc., in order to facilitate discrimination of the ion implantation region.
[0089]
The shape of each mask 7 may be a polygon or an indefinite shape as long as it fits in the spot size of the later laser.
[0090]
When the mask 7 is provided at the substrate end, the substrate 7 is preferably not provided at the substrate end since the laser beam is not uniformly irradiated at the substrate end in a laser light irradiation process described later. Preferably, the mask 7 is provided on the inner side of the substrate edge by 50 μm or more.
[0091]
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.
[0092]
By removing the mask 7, the base material substrate is completed (FIG. 5D).
[0093]
Next, as in Embodiment 1, the GaN layer 2 was grown to 200 μm, the substrate temperature was lowered to room temperature, and the substrate was taken out (FIG. 5E).
[0094]
Next, a substrate separation step by laser light irradiation, which is a third step, is performed. Laser light irradiation was performed at room temperature using an apparatus capable of two-dimensional optical axis scanning. As for the laser irradiation position, optical axis scanning was performed so that a region not subjected to ion implantation was irradiated.
[0095]
For example, irradiation can be performed by the following method.
[0096]
The region 1b where ions are not implanted is arranged in the same manner 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 where ions are not implanted at the substrate end, the substrate is not rotated, and the linear velocity is 2 cm per second in the direction in which the nearest region 1b is aligned. When the optical axis is scanned in step 1, laser irradiation is performed in synchronization with the region 1b. Thereafter, if the same irradiation is repeated, the entire surface of the substrate can be irradiated.
[0097]
In this embodiment mode, irradiation was performed from the outside to the inside of the substrate. Since the regions 1b are arranged in 6-fold symmetry, a regular hexagon including the outermost region 1b is considered, optical axis scanning and laser light irradiation are performed along this regular hexagon, and irradiation is gradually performed on the inner hexagon. Just do it.
[0098]
Depending on the size and interval of the mask 7, the outer peripheral region 1 b may not necessarily be arranged in a hexagonal shape. However, the pattern of the mask 7 may be extrapolated and scanned assuming a hexagonal shape.
[0099]
Since the region 1b can be regarded as three-fold symmetry, the optical axis may be scanned in an equilateral triangle.
[0100]
Since the region 1b can be regarded as two-fold symmetry, the above-described pair of hexagonal opposite sides may be alternately scanned from the outside to the inside.
[0101]
FIG. 5F is a cross-sectional view during the laser irradiation process. To clearly show the figure, hatching is not applied. 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. .
[0102]
On the other hand, the crack 12 does not extend in the region 1b where ions are not implanted, stops in the region 1b, and does not lead to automatic peeling over the entire GaN layer 2.
[0103]
In the present embodiment, separation was completely caused only when the laser irradiation was completed up to the center, and the GaN layer 2 was separated from the sapphire substrate 1 (FIG. 5G).
[0104]
Finally, Ga11 was dissolved with HCl, and the sapphire piece 13 was removed by polishing to obtain a single GaN substrate 2 (FIG. 5 (h)).
[0105]
In addition, not only the shape of the ion implantation region and the laser irradiation method of the present embodiment, but also a plurality of ion implantation regions are arranged in a distributed manner, and laser irradiation is performed in synchronization with the arranged ion implantation regions. Needless to say, laser irradiation can be performed well. More preferably, as in this embodiment, the region 1b that is not ion-implanted is periodically arranged to scan the optical axis more efficiently and to irradiate the region 1b with laser light. it can.
[0106]
Also in the present embodiment, since the back surface having a substantially constant shape is obtained, it is possible to polish the back surface of the plurality of GaN substrates 2 by the same batch process.
[0107]
(Embodiment 5)
The fifth embodiment will be described below with reference to FIG. The fifth embodiment shows a modification of the fourth embodiment in which the laser irradiation method is changed.
[0108]
The substrate 1 in FIG. 6A is sapphire similar to that in the fourth embodiment.
[0109]
A step of implanting hydrogen ions into the sapphire substrate 1 is performed (FIGS. 6B, 6C, 6D).
[0110]
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 distance between adjacent masks 7 is 2 mm, and the diameter of each mask 7 is 0.5 mm.
[0111]
Next, hydrogen ions were implanted as shown in FIG. The implantation amount and implantation conditions of hydrogen ions are the same as those in the fourth embodiment. A region 1a into which ions were implanted and a region 1b into which ions were not implanted were formed.
[0112]
By removing the mask 7, the base material substrate is completed (FIG. 6D).
[0113]
Next, as in Embodiment 4, the GaN layer 2 was grown to 200 μm, the substrate temperature was lowered to room temperature, and the substrate was taken out (FIG. 6E).
[0114]
Next, a substrate separation step by laser irradiation, which is a third step, is performed. The optical system and the rotation mechanism used the apparatus shown in FIG. However, a KrF excimer laser device with a large laser power was used, the beam diameter was 5 mm, and the beam power was 3 J. The pulse width is 30 ns. Also in the KrF excimer laser device, the power required to sublimate 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 that is the square of 5. Therefore, the light density is not lower than that in the first embodiment, and is sufficient for sublimating GaN.
[0115]
In the present embodiment, the irradiation spot interval in the rotation direction and the pitch of 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.
[0116]
FIG. 6F is a cross-sectional view during the laser irradiation process. The GaN layer 2 is decomposed into Ga11 and nitrogen gas in the vicinity of the interface with the sapphire substrate 1 by laser light irradiation. For this reason, stress is concentrated and cracks 12 are generated in the ion-implanted region around the laser spot. Since Ga11 and sapphire substrate 1 and GaN11 and GaN layer 2 are weakly bonded, and particularly weakly bonded to sapphire substrate 1, GaN layer 2 is separated from sapphire substrate 1. At that time, nitrogen is released to the outside. However, since sapphire that is not ion-implanted is strong, it does not lead to automatic peeling across the entire substrate.
[0117]
Therefore, in the present embodiment, the GaN layer 2 is completely peeled from the sapphire substrate 1 only when the entire region 1b that has not been ion-implanted is irradiated (FIG. 6G).
[0118]
Finally, Ga11 was removed by HCl to obtain a single GaN substrate 2 (FIG. 6 (h)).
[0119]
In the present embodiment, the entire substrate is irradiated, but the laser beam diameter is four times larger and the beam area is 16 times larger. Therefore, the plurality of regions 1b are irradiated at a time. By irradiating the 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 it is possible to implement with relatively inexpensive equipment other than the laser. In addition, even when irradiating a plurality of dots with one irradiation, it is needless to say that peeling can be performed with a smaller number of irradiations by irradiating the laser in synchronization with the dots.
[0120]
(Embodiment 6)
A method for manufacturing a GaN substrate in the sixth embodiment of the present invention will be described with reference to FIG. This embodiment is exactly the same as Embodiment 1 except that plasma irradiation is used instead of ion implantation.
[0121]
The substrate 1 in FIG. 7A is the same sapphire substrate 1 as in the first embodiment.
[0122]
First, a plasma irradiation process which is a first process is performed.
[0123]
This sapphire substrate 1 is irradiated with oxygen plasma for 10 minutes to obtain a region 1a (hereinafter referred to as plasma irradiation region 1a or simply referred to as region 1a) in which atomic bonds are cut by the plasma irradiation (FIG. 7B). The irradiation time required for plasma irradiation differs depending on conditions such as plasma density and pressure. In the case of plasma irradiation, the plasma state greatly depends on the plasma generation method and apparatus, and unlike ion implantation, it cannot be uniquely defined.
[0124]
For example, in this embodiment, the electrode area is 1000 cm. ² The parallel plate RF plasma with a circular electrode is considered 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 it is less than 30 seconds, the amount of weakening the atomic bonding force in the plasma-irradiated region is insufficient, and if it is longer than 2 hours, the surface is damaged and it is difficult to grow a single-crystal GaN layer thereon. It becomes.
[0125]
Next, a nitride semiconductor layer growth step, which is a second step, is performed. A GaN layer 2 having a thickness of 200 μm 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).
[0126]
Next, a substrate separation step by laser irradiation, which is a third step, is performed. Regarding the laser irradiation, the method, apparatus, and conditions are exactly the same as those in the first embodiment. As shown in the schematic diagram of FIG. 7D, the center distance in the rotation direction and the center distance in the radial direction of the irradiation spot are set to 2 mm. The rotation speed and the scanning speed of the optical axis were adjusted so that the light was irradiated.
[0127]
As in the first embodiment, if laser irradiation is continued, the stress is concentrated near the center of the substrate at the stage of laser irradiation about 1 cm from the periphery without irradiating the laser to the center, and the sapphire substrate The GaN layer 2 was peeled from 1 to obtain a GaN substrate 2 to which Ga11 and sapphire pieces 13 were attached (FIG. 7E).
[0128]
Finally, Ga11 was dissolved with HCl, and the unevenness of the sapphire piece 13 and the GaN layer 2 was removed by polishing to obtain a single GaN substrate 2 (FIG. 7 (f)).
[0129]
From the above, it was shown that the same effect as ion implantation can be obtained even if the sapphire bond is weakened by plasma irradiation.
[0130]
(Embodiment 7)
The seventh embodiment will be described with reference to FIG. The seventh embodiment is exactly the same as the sixth embodiment except that the irradiation plasma is hydrogen, helium, argon, xenon, or krypton.
[0131]
The substrate 1 in FIG. 8A is a (0001) plane sapphire substrate having a diameter of 2 inches and a thickness of 700 microns, which is exactly the same as in the sixth embodiment.
[0132]
Five sapphire substrates 1 were prepared and irradiated with plasma of hydrogen, helium, argon, xenon, and krypton for 10 minutes, respectively, to obtain a plasma irradiation region 1a (FIG. 8B).
[0133]
Next, a nitride semiconductor layer growth step, which is a second step, is performed. Each sapphire substrate 1 was grown until the thickness of the GaN layer 2 reached 200 μm as in the sixth embodiment, the substrate temperature was lowered to room temperature, and the substrate was taken out (FIG. 8C).
[0134]
Next, a substrate separation step by laser irradiation, which is a third step, is performed. For the laser irradiation, the same apparatus and irradiation method as those in Embodiment 6 were used. As a result, when any plasma was irradiated, the GaN layer 2 was peeled from the sapphire substrate 1, and the GaN substrate 2 to which Ga11 and sapphire pieces 13 were attached was obtained (FIG. 8 (d)).
[0135]
Finally, Ga11 was dissolved by HCl, and the unevenness of the sapphire piece 13 and the GaN layer 2 was removed by polishing, whereby a GaN substrate 2 was obtained (FIG. 8 (e)).
[0136]
From the above, it was confirmed that the same effect as that of oxygen plasma can be obtained even with plasma of hydrogen, helium, argon, xenon, and krypton. Moreover, even if a device is formed on the obtained GaN substrate 2, problems such as deterioration of characteristics do not occur as in the case where heavy metal or the like is introduced into the nitride semiconductor device. Further, a 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.
[0137]
(Embodiment 8)
Hereinafter, the eighth embodiment will be described with reference to FIG. In the eighth embodiment, plasma irradiation is performed instead of ion implantation in the third embodiment, and SiO is used as a mask. ₂ The same as the third embodiment except that is used.
[0138]
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 has a mirror finish on both the front and back surfaces.
[0139]
A step of irradiating the sapphire substrate 1 with oxygen plasma is performed (FIGS. 9B, 9C, 9D).
[0140]
First, as shown in FIG. ₂ A mask 7 is provided. SiO ₂ The shape of the mask 7 is the same spiral as the resist mask 7 in the third embodiment. In addition, SiO ₂ Layer patterning was performed by photolithography and etching with hydrofluoric acid. SiO ₂ The layers are formed by RF sputtering. In addition, SiO ₂ The layer may be formed by other methods such as thermal CVD or vapor deposition, or may be SiN or the like as long as it is a material or manufacturing method that can withstand plasma irradiation described later.
[0141]
Next, as shown in FIG. 9C, oxygen plasma was irradiated for 10 minutes. The plasma conditions are the same as in the sixth embodiment. A plasma irradiation region 1a is formed on the main surface of the sapphire substrate 1 where the mask 7 does not exist. A region 1b (hereinafter referred to as a plasma non-irradiated region 1b or simply referred to as a region 1b) in which the atomic plasma is hardly preserved and the atomic bonds are substantially preserved is formed in the portion where the mask 7 is present because the oxygen plasma is blocked. Is done. Since oxygen plasma etches resist, SiO ₂ However, it goes without saying that a resist may be used as a mask in the case of plasma of hydrogen or a rare gas.
[0142]
By removing the mask 7, the base material substrate is completed (FIG. 9D).
[0143]
Next, a nitride semiconductor layer growth step, which is a second step, is performed. The GaN layer 2 was grown by 200 μm by the HVPE method in the same manner as in the third embodiment, the substrate temperature was lowered to room temperature, and the substrate was taken out (FIG. 9 (e)).
[0144]
Next, a substrate separation step by laser irradiation, which is a third step, is performed. For the laser irradiation, the same apparatus and method as in Embodiment 3 were used, and the plasma non-irradiation region 1b was irradiated. Only when the laser irradiation was completed to the center, complete automatic peeling occurred, and the GaN layer 2 to which Ga11 and sapphire pieces 13 were completely attached was peeled from the sapphire substrate 1 (FIG. 9F).
[0145]
Finally, Ga11 was dissolved with HCl, and the sapphire piece 13 and the unevenness were removed by polishing to obtain a single GaN substrate 2 (FIG. 9 (g)).
[0146]
As described above, it was confirmed that the same effect can be obtained by plasma irradiation instead of ion implantation. The most preferable shape of the plasma non-irradiation region 1b is a pattern that can be drawn with a single stroke like the spiral spiral of the present embodiment, but it goes without saying that it may be a radial pattern, a stripe pattern, or another pattern.
[0147]
The plasma irradiation region 1a and the plasma non-irradiation region 1b have a preferable area relationship similar to ion implantation. When laser light irradiation is performed at room temperature, as a preferable area relationship, the area of the region 1a is preferably between 1/5 and 50 times the area of the region 1b.
[0148]
(Embodiment 9)
The ninth embodiment will be described below with reference to FIG. The ninth embodiment shows a case where plasma irradiation is performed instead of the ion implantation of the fourth embodiment.
[0149]
The substrate 1 in FIG. 10A is sapphire similar to that in the fourth embodiment.
[0150]
This sapphire substrate 1 is irradiated with oxygen plasma.
[0151]
First, as shown in FIG. ₂ A pattern by the layer mask 7 is provided. The shape of the mask 7 is the same as that of the fourth embodiment.
[0152]
Next, oxygen plasma was irradiated as shown in FIG. The amount of oxygen plasma irradiation and the implantation conditions are the same as in the sixth embodiment.
[0153]
By removing the mask 7, the base material substrate is completed (FIG. 10D).
[0154]
Next, as in Embodiment 4, the GaN layer 2 was grown to 200 μm, the substrate temperature was lowered to room temperature, and the substrate was taken out (FIG. 10E).
[0155]
Next, a substrate separation step by laser irradiation, which is a third step, is performed. The laser irradiation method and the like are exactly the same as those in the fourth embodiment.
[0156]
In the present embodiment, the GaN layer 2 to which Ga11 and sapphire pieces 13 are attached is peeled off from the sapphire substrate 1 only after the irradiation of all the dots has been completed (FIG. 10 (f)).
[0157]
Finally, Ga11 was dissolved using HCl, and the sapphire piece 13 and unevenness were removed by polishing to obtain a single GaN substrate 2 (FIG. 10 (g)).
[0158]
As described above, the same effect as that of ion implantation was obtained even when a periodic plasma non-irradiation region was used.
[0159]
(Embodiment 10)
Hereinafter, the tenth embodiment will be described with reference to FIG. The tenth embodiment shows a case where plasma irradiation is performed in place of the ion implantation of the fifth embodiment.
[0160]
The substrate 1 in FIG. 11A is sapphire similar to that of the fifth embodiment.
[0161]
A step of irradiating the sapphire substrate 1 with oxygen plasma is performed (FIGS. 11B, 11C, 11D).
[0162]
First, as shown in FIG. ₂ A pattern by the mask 7 is provided. The shape of the mask 7 is the same as that of the fifth embodiment, and the center interval between adjacent dots is 2 mm, and the dot diameter is 0.5 mm.
[0163]
Next, as shown in FIG. 11C, oxygen plasma was irradiated for 10 minutes. The oxygen plasma irradiation conditions are the same as in the sixth embodiment. A plasma irradiation region 1a and a plasma non-irradiation region 1b were formed.
[0164]
By removing the mask 7, the base material substrate is completed (FIG. 11D).
[0165]
Next, as in Embodiment 5, the GaN layer 2 was grown to 200 μm, the substrate temperature was lowered to room temperature, and the substrate was taken out (FIG. 11E).
[0166]
Next, a substrate separation step by laser irradiation, which is a third step, is performed. In exactly the same manner as in the fifth embodiment, the GaN layer 2 to which Ga11 was adhered could be peeled from the sapphire substrate 1 using a KrF excimer laser (FIG. 11 (f)).
[0167]
Finally, Ga11 on the back surface was dissolved with HCl to obtain a single GaN substrate 2 (FIG. 11 (g)).
[0168]
As described in the sixth to tenth embodiments, plasma irradiation can provide almost the same effect as ion implantation. In the case of plasma irradiation, there is a device dependency of the plasma generation source, and there is a problem that conditions such as preferable irradiation time slightly change depending on the device, but weaken the atomic bond of sapphire with a relatively simple device than ion implantation. There is an advantage that you can.
[0169]
In the above embodiment, it goes without saying that an AlGaN, InGaN, or AlInGaN substrate can be obtained by growing an AlGaN layer, an InGaN layer, or an AlInGaN layer instead of the GaN layer 2.
[0170]
In the above embodiments, ions are implanted into a base material substrate such as sapphire, but ion implantation may be performed using a substrate in which a GaN layer or the like is previously provided on sapphire or the like as a base material substrate. Needless to say. That is, it goes without saying that the same effect can be obtained by growing a GaN layer on sapphire, performing ion implantation on the GaN / sapphire substrate, and then growing the GaN layer thickly thereon, followed by laser irradiation. .
[0171]
【The invention's effect】
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 manufactured with high productivity by using the peeling of the nitride semiconductor layer from the base substrate by laser irradiation. it can.
[Brief description of the drawings]
FIGS. 1 (a) to (c) and (e) to (g) are cross-sectional views illustrating a method for manufacturing a nitride semiconductor substrate according to a first embodiment of the present invention.
(D) Top view showing the method for manufacturing the nitride semiconductor substrate in the first embodiment of the present invention.
FIG. 2 is a cross-sectional view showing a laser irradiation mechanism in Embodiment 1 of the present invention.
FIG. 3 is a cross-sectional view showing a method for manufacturing a nitride semiconductor substrate in a second embodiment of the present invention.
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.
(B-2) Top view showing the method for manufacturing the nitride semiconductor substrate in the third embodiment of the present invention.
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.
(B-2) Top view showing the method for manufacturing the nitride semiconductor substrate in the fourth embodiment of the present invention.
FIG. 6 is a sectional view showing a method for manufacturing a nitride semiconductor substrate in a fifth embodiment of the present invention.
FIGS. 7A to 7C are cross-sectional views showing a method for manufacturing a nitride semiconductor substrate according to a sixth embodiment of the present invention.
(D) Top view showing the method for manufacturing the nitride semiconductor substrate in the sixth embodiment of the present invention.
FIG. 8 is a sectional view showing a method for manufacturing a nitride semiconductor substrate in a seventh embodiment of the present invention.
FIG. 9 is a sectional view showing a method for manufacturing a nitride semiconductor substrate in an eighth embodiment of the present invention.
FIG. 10 is a sectional view showing a method for manufacturing a nitride semiconductor substrate in a ninth embodiment of the present invention.
FIG. 11 is a sectional view showing a method for manufacturing a nitride semiconductor substrate according to the tenth embodiment of the present invention.
[Explanation of symbols]
1 Base material board
1a A region where atomic bonds are broken
1b Region where atomic bonds are preserved
2 Nitride semiconductor layer
3 Laser equipment
4 Rotating mechanism
5 Scan lens
6 Condensing means
7 Mask
8 Laser irradiation position
10 Laser light
11 Ga
12 crack
13 Sapphire pieces

Claims (12)

On the main surface of the base material substrate ,
A first step of providing a region where an atomic bond of a material constituting the base substrate is cut by ion implantation of hydrogen or silicon ;
A second step of forming a nitride semiconductor layer on the base material substrate;
A method for manufacturing a nitride semiconductor substrate, comprising: a third step of irradiating a laser beam onto an interface between the base material substrate and the nitride semiconductor layer. The first step is a step of providing a first region in which ions are implanted into a main surface of a base material substrate and a second region in which an ion implantation amount is smaller than that in the first region or is not implanted. The method for manufacturing a nitride semiconductor substrate according to claim 1, wherein the third step is a step of irradiating at least the second region with the laser beam. 3. The nitride semiconductor according to claim 2 , wherein the second region is continuous in a linear shape, and the third step is a step of scanning the laser beam along the second region. A method for manufacturing a substrate. The second region is arranged in a plurality of dispersed manners, and the third step is a step of irradiating the laser beam in pulses while scanning the optical axis of the laser beam in synchronization with the second region. The method for producing a nitride semiconductor substrate according to claim 2 , wherein: The second region is placed distributed over multiple, claim 2, wherein the third step is characterized by a step of irradiating a plurality of said second regions with one irradiation of the laser beam The manufacturing method of the nitride semiconductor substrate as described in any one of Claims 1-3. Nitride semiconductor substrate manufacturing method according to claim 1, wherein the base substrate is sapphire. On the main surface of the base material substrate,
A first step of providing a region in which an atomic bond of a material constituting the base material substrate is cut by plasma irradiation with hydrogen, oxygen, or a rare gas ;
A second step of forming a nitride semiconductor layer on the base material substrate;
A method for manufacturing a nitride semiconductor substrate , comprising: a third step of irradiating a laser beam onto an interface between the base material substrate and the nitride semiconductor layer . The first step is a step of providing a first region irradiated with plasma on the main surface of the base material substrate and a second region where the amount of plasma irradiation is smaller than that of the first region or is not irradiated with the plasma, The method for manufacturing a nitride semiconductor substrate according to claim 7 , wherein the third step is a step of irradiating at least the second region with the laser beam. 9. The nitride semiconductor according to claim 8 , wherein the second region is continuous in a linear shape, and the third step is a step of scanning the laser beam along the second region. A method for manufacturing a substrate. The second region is arranged in a plurality of dispersed manners, and the third step is a step of irradiating the laser beam in pulses while scanning the optical axis of the laser beam in synchronization with the second region. The method for manufacturing a nitride semiconductor substrate according to claim 8 , wherein: The second region is placed distributed over multiple, claim 8, wherein the third step is characterized by a step of irradiating a plurality of said second regions with one irradiation of the laser beam A method for producing a nitride semiconductor substrate as described in 1. above. Nitride semiconductor substrate manufacturing method according to claim 7, wherein the base substrate is sapphire.

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