JP2011151400A - Laser peeling device, laser peeling method, and method of manufacturing self-supporting group iii nitride semiconductor substrate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress the breakage of a group III nitride semiconductor film when the group III nitride semiconductor film is peeled from a base substrate by laser irradiation. <P>SOLUTION: This leaser peeling device peels a GaN film 12 from a sapphire/GaN structure W including a sapphire substrate 11 and a GaN film 12 formed on the substrate 11 by laser irradiation. The laser peeling device includes a substrate holding base 14 which holds the sapphire/GaN structure W without coming into contact with the surface of the GaN film 12 in a state where the GaN film 12 is directed downward or sideward, and a laser irradiation section which irradiates the sapphire/GaN structure W with a laser beam. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a laser peeling apparatus, a laser peeling method, and a method for manufacturing a group III nitride semiconductor free-standing substrate.

  In fabricating a semiconductor device using gallium nitride (GaN), it is desirable to use a substrate made of a bulk GaN crystal of the same material as the epitaxial GaN layer to be grown. Attempts to produce bulk crystals of GaN-based crystals have been made by many research institutions. However, in crystals such as GaN, it is difficult to obtain a wafer with a large area due to the high dissociation pressure of nitrogen, and since there are many impurities, it is very difficult to produce a GaN-based bulk crystal that can be used industrially. It was.

Therefore, to manufacture a GaN semiconductor substrate, first, a GaN thin film (film thickness of about 2 μm) is formed on a sapphire (Al ₂ O ₃ ) substrate using an MOCVD apparatus, and an HVPE apparatus is formed on the GaN thin film. Is used to grow a GaN film (film thickness of about 400 μm) to obtain an Al ₂ O ₃ —GaN composite substrate material (hereinafter appropriately referred to as a sapphire / GaN structure), and then the GaN film is formed from the sapphire / GaN structure. By separating, a GaN semiconductor substrate for producing a semiconductor device is produced.

  As a conventional method for separating a GaN film from a sapphire / GaN structure, there is a method described in Patent Document 1. In this method, as shown in FIG. 9, the sapphire / GaN structure W is placed on the hot plate 53 so that the GaN film 52 side is downward (the sapphire substrate 51 side is upward). Then, the hot plate 53 is heated to about 800 ° C., and the laser beam LB is irradiated from the sapphire substrate 51 side while heating the GaN film 52. At this time, the means for holding the laser light source or the sapphire / GaN structure W is moved relatively vertically and horizontally in the horizontal plane of the sapphire substrate 51 by a driving device (not shown), so that the laser beam LB has a sapphire / GaN structure. The body W is irradiated without any damage.

  As the laser beam LB, a YAG laser having a wavelength of 355 nm is used. The laser beam LB having a wavelength of 355 nm passes through the sapphire substrate 51 and is absorbed by the GaN film 52. The output of the laser beam LB is set to an intensity that raises the GaN film 52 in the vicinity of the interface between the sapphire substrate 51 and the GaN film 52 to a temperature at which it is decomposed into gallium (Ga) and nitrogen (N). For this reason, the GaN film 52 in the vicinity of the interface between the sapphire substrate 51 and the GaN film 52 is thermally decomposed by heating with the hot plate 53 and the laser beam LB. As a result, the GaN film 52 is peeled from the sapphire substrate 51.

  However, in the method described in Patent Document 1, the GaN film 52 is easily damaged in the process of peeling the GaN film 52 from the sapphire substrate 51.

JP 2002-57119 A

  The present inventors examined the cause of the GaN film being easily damaged as described above, and found that the method described in Patent Document 1 has the following problems.

  First, in the method described in Patent Document 1, the sapphire / GaN structure W is installed in a manner that the GaN film 52 is below, so that the GaN film 52 supports the weight of the sapphire substrate 51. At this time, in the process of peeling of the GaN film 52 from the sapphire substrate 51, the fulcrum of the load of the sapphire substrate 51 supported by the GaN film 52, that is, the boundary between the peeling region SA and the non-peeling region changes every moment. Accordingly, the stress state is likely to be unstable locally, and the GaN film 52 is likely to be damaged.

  Second, in the method described in Patent Document 1, when the sapphire / GaN structure W is heated up to the vicinity of the growth temperature of the GaN film 52, the surface of the GaN film 52 is likely to be thermally decomposed. For this reason, it is difficult to raise the temperature near the growth temperature of the GaN film 52, which is ideal as a peeling condition. Therefore, peeling is performed at an insufficient temperature, and when the GaN film 52 is peeled from the sapphire substrate 51, an excessive force is easily applied to the GaN film 52, so that the GaN film 52 is easily damaged.

  Thirdly, in the method described in Patent Document 1, the sapphire / GaN structure W is warped so that the GaN film 52 side is convex, and therefore, when heated on the hot plate 53, the hot plate 53 There may be a place where the contact is made and a place where a gap is generated, and temperature spots (uneven temperature distribution) may occur. When temperature spots occur in the sapphire / GaN structure W, the sapphire substrate 51 moves toward the GaN film 52 so far while the GaN film 52 is peeled off from the sapphire substrate 51 by irradiation with the laser beam LB. The temperature spot is further enlarged by deforming from the convex shape to the concave shape. For this reason, the GaN film 52 is not easily peeled off, and the GaN film 52 may be damaged.

  The present invention has been made in view of the above circumstances, and an object thereof is to suppress breakage of a group III nitride semiconductor film when the group III nitride semiconductor film is peeled off from a base substrate by laser irradiation.

  According to the present invention, there is provided a laser peeling apparatus for peeling a group III nitride semiconductor film by laser irradiation from a structure including a base substrate and a group III nitride semiconductor film provided on the base substrate. Irradiating the surface of the structure with a substrate holding portion for holding the structure without contacting the group III nitride semiconductor film with the group III nitride semiconductor film facing downward or sideward. It is possible to provide a laser peeling device including a laser irradiation unit.

  According to this configuration, the group III nitride semiconductor film supports its own load in the process of peeling off the group III nitride semiconductor film, but hardly supports the load of the base substrate. For this reason, stress concentration can be prevented from occurring at the load supporting point at the boundary between the peeled region and the unpeeled region of the group III nitride semiconductor film, and the group III nitride semiconductor film may be damaged. Can be reduced.

  According to the invention, there is provided a laser peeling apparatus for peeling a group III nitride semiconductor film by laser irradiation from a structure including a base substrate and a group III nitride semiconductor film provided on the base substrate. A container, a nitrogen gas supply unit that fills the container with a nitrogen-containing gas, a substrate holding unit that is provided in the container and holds the structure, and laser irradiation that irradiates the structure with laser And a laser peeling apparatus including the unit.

  According to this configuration, it is possible to raise the temperature while suppressing the decomposition reaction of the group III nitride semiconductor film surface other than the portion irradiated with the laser while the container is filled with the nitrogen-containing gas. Further, the stress acting on the group III nitride semiconductor film can be reduced by reducing the warpage of the structure. For this reason, the possibility that the group III nitride semiconductor film is damaged is reduced.

  According to the invention, there is provided a laser peeling apparatus for peeling a group III nitride semiconductor film by laser irradiation from a structure including a base substrate and a group III nitride semiconductor film provided on the base substrate. A laser comprising: a substrate holding unit that holds the structure; a heater that is provided at a position away from the structure, and that heats the structure; and a laser irradiation unit that irradiates the structure with laser. A peeling device can be provided.

  According to this configuration, since the structure is heated as a whole, the temperature of the structure is increased uniformly compared to the case where the structure is heated by heat conduction. For this reason, peeling occurs reliably at the laser irradiation point. As a result, the group III nitride semiconductor film can be prevented from being damaged during the expansion of the separation region due to the movement of the laser irradiation point.

  According to the present invention, there is provided a laser peeling method for peeling a group III nitride semiconductor film by laser irradiation from a structure including a base substrate and a group III nitride semiconductor film provided on the base substrate. A step of holding the structure without contacting the surface of the group III nitride semiconductor film with the group III nitride semiconductor film facing downward or sideward, and irradiating the structure with laser A laser peeling method including a step and a step of peeling a group III nitride semiconductor film from a structure can be provided.

  According to this method, the group III nitride semiconductor film supports its own load in the process of peeling off the group III nitride semiconductor film, but hardly supports the load of the base substrate. For this reason, stress concentration can be prevented from occurring at the load supporting point at the boundary between the peeled region and the unpeeled region of the group III nitride semiconductor film, and the group III nitride semiconductor film may be damaged. Can be reduced.

  According to the present invention, there is provided a laser peeling method for peeling a group III nitride semiconductor film by laser irradiation from a structure including a base substrate and a group III nitride semiconductor film provided on the base substrate. There are a step of holding the structure, a step of replacing the atmosphere gas of the structure with a nitrogen-containing gas, a step of irradiating the structure with a laser, and peeling the group III nitride semiconductor film from the structure. And a laser peeling method including the steps.

  According to this method, while suppressing the decomposition reaction of the group III nitride semiconductor film surface other than the portion irradiated with the laser while the container is filled with the nitrogen-containing gas, the warpage of the structure is reduced. The stress acting on the group III nitride semiconductor film can be reduced. For this reason, the possibility that the group III nitride semiconductor film is damaged is reduced.

  According to the present invention, there is provided a laser peeling method for peeling a group III nitride semiconductor film by laser irradiation from a structure including a base substrate and a group III nitride semiconductor film provided on the base substrate. A step of holding the structure, a step of heating the structure with a heater provided at a position away from the structure, a step of irradiating the structure with a laser, and a group III from the structure And a step of peeling off the nitride semiconductor film.

  According to this method, since the structure is heated as a whole, the temperature of the structure is uniformly increased as compared with the case where the structure is heated by heat conduction. For this reason, peeling occurs reliably at the laser irradiation point. As a result, the group III nitride semiconductor film can be prevented from being damaged during the expansion of the separation region due to the movement of the laser irradiation point.

  In the present invention, the base substrate means a substrate serving as a base for crystal growth of the group III nitride semiconductor film. In the present invention, the structure means a three-dimensional structure including one or more film structures.

  According to the present invention, in order to irradiate the structure including the base substrate and the group III nitride semiconductor film with a laser by a specific method, the group III nitride semiconductor film is peeled off from the base substrate by laser irradiation. , Damage to the group III nitride semiconductor film can be suppressed.

It is sectional drawing which shows typically the whole laser peeling apparatus which concerns on Embodiment 1. FIG. FIG. 3 is a top view and a cross-sectional view of a substrate holding unit provided in the laser peeling apparatus according to the first embodiment. It is sectional drawing of the board | substrate holding part with which the laser peeling apparatus which concerns on Embodiment 2 is equipped. FIG. 6 is a process cross-sectional view for explaining the laser peeling method according to the first embodiment. 10 is a process cross-sectional view for explaining a laser peeling method according to Example 2. FIG. 6 is a process cross-sectional view for explaining a laser peeling method according to Example 3. FIG. It is process sectional drawing for demonstrating the laser peeling method which concerns on Example 4. FIG. It is sectional drawing which shows typically the whole laser peeling apparatus which concerns on Embodiment 3. FIG. It is explanatory drawing of a conventionally well-known laser peeling method.

  In the present invention, the substrate holding portion can be configured to support the structure in a region where the group III nitride semiconductor film is not provided on the surface of the base substrate.

  According to this configuration, since the group III nitride semiconductor film does not need to support the load on the base substrate in the process of peeling off the group III nitride semiconductor film, the possibility that the group III nitride semiconductor film is damaged can be reduced. .

  In this invention, the said laser peeling apparatus may further be provided with the buffer material provided in the lower part of the board | substrate holding part.

  According to this configuration, the group III nitride semiconductor film that has been peeled off from the underlying substrate can be received while suppressing damage.

  The laser peeling method may further include a step of forming a protective film having a heat resistant temperature equal to or higher than the growth temperature of the group III nitride semiconductor film on the surface of the group III nitride semiconductor film in the structure.

  According to this method, since the protective film is formed on the surface of the group III nitride semiconductor film, the surface of the group III nitride semiconductor film is decomposed even when the structure is heated by a heater or laser irradiation. The reaction can be suppressed.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In all the drawings, the same reference numerals are given to the same components, and the description will be omitted as appropriate.

<Embodiment 1>
FIG. 1 is a cross-sectional view schematically showing the entire laser peeling apparatus according to this embodiment. 2A and 2B are a top view and a cross-sectional view of the substrate holding unit provided in the laser peeling apparatus according to the present embodiment.

  The laser peeling apparatus 1 according to the present embodiment applies a laser to a sapphire / GaN structure W (FIG. 2A) in which a GaN film 12 (Group III nitride semiconductor film) is formed on a sapphire substrate 11 (underlying substrate). The GaN film 12 is peeled off from the sapphire substrate 11 by irradiation with light LB. In the present embodiment, the sapphire / GaN structure means a three-dimensional structure in which a GaN film is formed on a sapphire substrate.

  As shown in FIG. 1, the laser peeling device 1 includes a laser oscillation device 3, a laser oscillation device holding table 4, a substrate holding unit 10, a holding table driving device 8, a mirror 5, and a mirror lifting / lowering in a case 9 on a frame 2. The device 6 and the slit 7 are arranged.

  FIG. 2B is a diagram illustrating a detailed structure of the substrate holding unit 10. As illustrated, the substrate holding unit 10 includes a quartz container 15. In the quartz container 15, a substrate holder 14 is provided for holding only the sapphire substrate 11 portion of the sapphire / GaN structure W with the GaN film 12 surface facing downward. The outer periphery (side surface and bottom surface) of the quartz container 15 excluding the quartz lid 16 (laser transmitting surface) is covered with heaters 17 and 18 (heating means).

  The laser peeling apparatus 1 heats the entire quartz container 15 with heaters 17 and 18. Further, the laser peeling apparatus 1 is configured to be able to irradiate the laser beam LB from above while heating the GaN film 12 so as to raise the temperature near the growth temperature by the heaters 17 and 18.

A buffer material 19 made of quartz cloth or quartz wool is provided below the GaN film 12 (below the substrate holding table 14). A thermocouple 20 is provided in the quartz container 15. The surface of the GaN film 12 is coated with a protective film 13 (silicon dioxide (SiO ₂ ) film) having heat resistance equal to or higher than the growth temperature of the GaN film 12.

  Although the protective film 13 is coated on the surface of the GaN film 12, the protective film 13 may not be provided when the sapphire / GaN structure W is not heated to the GaN film growth temperature as will be described later.

  The peeling method according to this embodiment will be described below.

  First, the sapphire / GaN structure W is set on the substrate holding base 14 so as to hold only the sapphire substrate 11 with the GaN film 12 surface facing downward. Next, the inside of the quartz container 15 is heated by the heaters 17 and 18, and the sapphire / GaN structure W is heated to about 800 ° C.

  Then, the laser oscillation device 3 irradiates the sapphire / GaN structure W with a laser beam LB having a wavelength of 355 nm. At this time, the substrate holding unit 10 is moved in the horizontal plane by the driving device 8 to irradiate the entire sapphire / GaN structure W with the laser beam LB. By this laser irradiation, thermal decomposition of the GaN film 12 occurs in the vicinity of the interface between the GaN film 12 and the sapphire substrate 11, and as a result, the GaN film 12 is peeled from the sapphire substrate 11.

  The effect by the peeling method which concerns on this embodiment is demonstrated below.

  In the present embodiment, the substrate holder 14 is configured to hold the sapphire / GaN structure W in a region where the GaN film 12 is not provided on the surface of the sapphire substrate 11. For this reason, in the process in which the GaN film 12 is peeled from the sapphire / GaN structure W, the GaN film 12 does not have to support the load of the sapphire substrate 11 at all. For this reason, the stress applied to the load support point (the boundary between the peeling region SA and the non-peeling region) is suppressed, and damage to the GaN film 12 is suppressed.

  In the present embodiment, ammonia gas is flow purged into the quartz container 15 by a gas supply means (not shown). By performing flow purge of ammonia gas, decomposition of the GaN film 12 can be suppressed when the temperature is raised to a high temperature. For this reason, since the temperature of the GaN film 12 at the time of laser irradiation can be raised to a high temperature, the warp of the GaN film 12 can be removed and the stress acting on the GaN film can be reduced. As a result, the risk of damage to the GaN film 12 is further reduced. Therefore, since the decomposition reaction of the surface of the GaN film 12 other than the peeling site can be suppressed, the decomposition of the GaN film 12 after peeling can be suppressed.

  In the present embodiment, the sapphire / GaN structure W is uniformly heated by the entire heating during peeling by laser irradiation. For this reason, it is difficult for the GaN film 12 to have temperature spots, and the occurrence of local strain can be reduced, so that damage to the GaN film 12 can be suppressed.

In addition to the above-described effects, the method of the present embodiment also has the following effects.
In the present embodiment, since the buffer material 19 is provided below the GaN film 12 (below the substrate holding table 14), it can be received while suppressing damage to the GaN film 12 that has been peeled off and dropped. .

  At this time, as described later in Example 2, before the GaN film 12 is peeled from the sapphire substrate 11, the upper surface of the buffer material 19 is brought into contact with the surface of the GaN film 12. Further, after the GaN film 12 is peeled from the sapphire substrate 11, a slight gap is formed between the GaN film 12 and the sapphire substrate 11 due to the elastic deformation of the buffer material 19 downward and the upward deformation of the sapphire substrate 11. Occurs. If the buffer material 19 is filled in this manner, the amount of deformation accompanying the peeling of the GaN film 12 is reduced, and the stress at the load support point can be relaxed.

  In the present embodiment, the surface of the GaN film 12 is coated with a protective film 13 having heat resistance equal to or higher than the growth temperature of the GaN film 12. For this reason, when the temperature of the GaN film 12 is raised to the growth temperature, the warp can be removed and the stress acting on the GaN film 12 can be reduced. As a result, the risk of damage to the GaN film 12 is further reduced.

  In the present embodiment, the sapphire / GaN structure W during the peeling operation is preferably heated to a temperature near the growth temperature of the GaN film 12 as described later in Example 3.

  This is because there is little thermal strain between the sapphire substrate 11 and the GaN film 12 when the GaN film 12 is grown. That is, the growth of the GaN film 12 is completed, and the thermal strain increases due to the difference in thermal expansion coefficient between the sapphire substrate 11 and the GaN film 12 with the subsequent temperature drop. For this reason, when the sapphire / GaN structure W is heated to the growth temperature of the GaN film 12, the sapphire / GaN structure W can be returned to a state with less warpage. For this reason, the stress acting on the GaN film 12 as the GaN film 12 is peeled off from the sapphire substrate 11 can be greatly reduced.

  Another reason is that when the sapphire / GaN structure W reaches the vicinity of the growth temperature of the GaN film 12, the GaN film 12 can be easily peeled off with a low-power laser beam.

In this embodiment, since the surface of the GaN film 12 is coated with the protective film 13, even if the sapphire / GaN structure W is heated, the decomposition reaction on the surface of the GaN film 12 other than the peeled portion can be suppressed. The deterioration of quality is suppressed. When SiO ₂ is used for the protective film 13, it may be removed with a hydrofluoric acid solution after peeling.

  In the present embodiment, the sapphire / GaN structure W does not have to be kept completely horizontal. When the sapphire / GaN structure W is held in an inclined state from the horizontal, the stress concentration at the load supporting point of the GaN film 12 can be relaxed.

<Embodiment 2>
FIG. 3 is a cross-sectional view of the substrate holding unit 100 provided in the laser peeling apparatus 1 according to this embodiment. The basic configuration of the substrate holding unit 100 is the same as that of the substrate holding unit 10 of the first embodiment, and the same reference numerals are used in FIG.

  In the substrate holding unit 100, an ammonia gas introduction port 116 a and an exhaust port 116 b are provided on the laser transmission surface 116, and a vent hole 114 a is provided in the substrate holding table 114 so that the purge gas can reach the GaN film 12 side. The gas inlet 116a and the gas outlet 116b may be provided at a place other than the laser transmission surface 116.

  Also in this embodiment, when the inside of the quartz container 15 is heated by the heaters 17 and 18 and the sapphire / GaN structure W is irradiated with the laser as in the case of the first embodiment, heat is generated at the interface between the GaN film 12 and the sapphire substrate 11. Decomposition occurs and the GaN film 12 peels from the sapphire substrate 11. At this time, the sapphire / GaN structure W is heated uniformly. For this reason, peeling occurs reliably at the laser irradiation point. As a result, the group III nitride semiconductor film can be prevented from being damaged during the expansion of the separation region due to the movement of the laser irradiation point.

  Also in the present embodiment, as in the case of the first embodiment, the sapphire / GaN structure W in which the GaN film 12 is formed on the sapphire substrate 11 is irradiated with a laser to peel the GaN film 12 from the sapphire substrate 11. In the laser peeling apparatus 1, the sapphire substrate 11 of the sapphire / GaN structure W is held with the GaN film 12 facing downward in the quartz container 15, and the quartz container 15 is heated from the upper side while heating the entire quartz container 15. The GaN film 12 is peeled from the sapphire substrate 11 by irradiation with light.

  At this time, in the process in which the GaN film 12 is peeled from the sapphire substrate 11, the GaN film 12 can reduce the stress concentrated on the load support point (the boundary between the peeled area and the non-peeled area) and can suppress the damage of the GaN film 12. .

  In the present embodiment, since the ammonia gas inlet 116a and the outlet 116b are provided, the quartz container 15 can be flow purged with ammonia gas. In this state, the warp of the sapphire / GaN structure W can be removed by raising the temperature to the growth temperature of the GaN film 12. For this reason, the stress which acts on the GaN film | membrane 12 can be reduced, and the possibility of a damage can further be suppressed. At this time, since the ammonia gas is purged, the decomposition reaction on the surface of the GaN film 12 other than the peeled portion can be suppressed, so that deterioration of the quality of the GaN film 12 after peeling can be suppressed.

<Embodiment 3>
FIG. 8 is a cross-sectional view schematically showing the entire laser peeling apparatus 31 according to the present embodiment. The basic configuration of the laser peeling apparatus 31 is the same as that of the laser peeling apparatus 1 of the first embodiment, but is different in that it has a specific configuration for holding the sapphire / GaN structure W in a state inclined from the horizontal. Yes.

  In the laser peeling device 31, a laser oscillation device 33, a laser oscillation device holding table 34, a substrate holding unit 35, a holding table driving device (horizontal direction) 36, and a holding table driving device (vertical direction) are placed in a case 58 on the gantry 32. 37 is arranged. A substrate holder (not shown) of the substrate holder 35 is configured so that the sapphire / GaN structure W can be fixed so as not to fall down.

  According to this laser peeling apparatus 31, since the sapphire / GaN structure W is held vertically and the GaN film 12 is peeled from the sapphire substrate 11, the stress concentration at the load support point can be alleviated.

  Also in this embodiment, as in the first embodiment, when the surface of the GaN film 12 is coated with the protective film 13 having a heat resistance equal to or higher than the growth temperature of the GaN film 12 and the temperature is raised to the vicinity of the growth temperature of the GaN film 12, sapphire / The warpage of the GaN structure W can be removed. For this reason, since the stress acting on the GaN film 12 can be reduced, the risk of damage to the GaN film 12 is further reduced. At this time, since the decomposition reaction on the surface of the GaN film 12 other than the part to be peeled can be suppressed, deterioration of the quality of the GaN film 12 after peeling can be suppressed.

  That is, also in the present embodiment, the temperature of the sapphire / GaN structure W can be raised uniformly as in the first embodiment. At this time, since the load of the sapphire substrate 11 supported by the GaN film 12 is reduced, the possibility that the GaN film 12 is broken during the peeling is reduced. Furthermore, when the temperature of the sapphire / GaN structure W is raised to the vicinity of the growth temperature of the GaN film 12, it is possible to suppress deterioration in the quality of the GaN film 12. As a result, damage to the GaN film 12 can be suppressed during peeling.

  As mentioned above, although embodiment of this invention was described with reference to drawings, these are the illustrations of this invention, Various structures other than the above are also employable.

  For example, in the laser peeling apparatus 31 of the third embodiment, the substrate holding unit 35 is arranged vertically, but the laser oscillation apparatus holding base 34 and the holding base driving apparatuses 36 and 37 are installed at a predetermined angle. You may arrange | position in the state inclined to. Also with this configuration, the sapphire / GaN structure W is held inclined from the horizontal and the GaN film 12 is peeled off from the sapphire substrate 11, so that stress concentration at the load support point can be alleviated. As a result, deterioration of the quality of the GaN film 12 after peeling can be suppressed.

  In the first embodiment, the sapphire / GaN structure W is heated to the vicinity of the film formation temperature of the GaN film 12. Even if the temperature is lower than that, it is sufficient that the GaN film 12 can be peeled from the sapphire / GaN structure W.

<Example 1>
Example of peeling GaN film 12 from sapphire / GaN structure W in which GaN film 12 having a thickness of 250 μm is formed on sapphire substrate 11 using laser peeling apparatus 1 and the laser peeling method described in the first embodiment Will be described with reference to FIGS. 1, 2, and 4.

  FIG. 4 is a process cross-sectional view for explaining the laser peeling method according to the present embodiment.

First, the sapphire / GaN structure W is formed by MOCVD using an organic metal and ammonia (NH ₃ ), and gallium chloride (GaCl) and ammonia (NH ₃ ) by the reaction of gallium (Ga) and hydrogen chloride (HCl). A GaN film 12 was epitaxially grown on the sapphire substrate 11 at a temperature of 1020 ° C. by the hydride VPE method used.

  Next, the buffer material 19 is inserted into the bottom of the substrate holder 14, and the sapphire / GaN structure W is placed on the substrate holder 14 with the GaN film 12 surface facing downward (the sapphire substrate 11 surface side is upward). did. At this time, the substrate holder 14 was configured to hold only the sapphire substrate 11 portion of the sapphire / GaN structure W. The substrate holder 14 on which the sapphire / GaN structure W was placed was housed in a quartz container 15 and a laser transmission surface (quartz lid) 16 was attached. The quartz container 15 was housed in an electric furnace composed of heaters 17 and 18.

  The temperature of the sapphire / GaN structure W was raised to 850 ° C. by the heaters 17 and 18. The heating rate was 850 ° C./25 minutes. When the temperature of the thermocouple 20 in the quartz container 15 is stabilized, the laser oscillation device 3 generates a laser beam LB having a wavelength of 355 nm, and the mirror 5 changes the angle of the optical axis from the horizontal direction to the vertical direction ( In the drawing, the direction of the laser beam LB is not shown for convenience in drawing. The same applies hereinafter.) The sapphire / GaN structure W was irradiated (FIG. 4A).

The intensity of the laser beam LB was set to 0.25 J / cm ² , the moving speed of the holding table driving device 8 was set to 0.5 cm / sec, and the entire surface of the sapphire / GaN structure W was irradiated while scanning. When the sapphire / GaN structure W is irradiated with the laser beam LB, the laser beam LB transmitted through the sapphire substrate 11 dissolves the GaN film 12 in the vicinity of the interface between the sapphire substrate 11 and the GaN film 12, and a separation region SA is generated. (FIG. 4B).

  At this time, the sapphire substrate 11 and the GaN film 12 were warped due to the difference between the growth temperature and the peeling temperature, but the occurrence of temperature spots (uneven temperature distribution) in the sapphire / GaN structure W was suppressed. The exfoliation area SA was smoothly expanded. In addition, since the GaN film 12 hardly supports the load of the sapphire substrate 11 in the process of peeling off the GaN film 12, stress concentration occurs at the load support point (the boundary between the peeling area SA and the non-peeling area). The GaN film 12 was hardly damaged.

  By irradiating the entire surface of the sapphire / GaN structure W with the laser beam LB, the entire GaN film 12 was peeled off and dropped (FIG. 4C). At this time, the GaN film 12 was able to suppress breakage because the shock of dropping was buffered by the buffer material 19.

  After the GaN film 12 was peeled off, the heaters 17 and 18 were turned off, and the quartz container 15 was cooled. After the temperature was lowered to room temperature, the quartz container 15 was taken out. The laser transmitting surface (quartz lid) 16 was removed, the sapphire substrate 11 was taken out, and then the GaN film 12 was taken out.

  When the surface of the extracted GaN film 12 was observed with a microscope, almost no cracks were generated in the GaN film 12, the decomposition of the surface was suppressed, and the flat state was maintained.

<Example 2>
Example of peeling GaN film 12 from sapphire / GaN structure W in which GaN film 12 having a thickness of 300 μm is formed on sapphire substrate 11 using laser peeling apparatus 1 and laser peeling method described in the first embodiment Will be described with reference to FIGS. 1, 2, and 5.

  FIG. 5 is a process cross-sectional view for explaining the laser peeling method according to the present embodiment. The laser peeling method of this example is basically the same as that of Example 1, except that the buffer material 19 is provided in the substrate holder 14 so as to be in contact with the GaN film 12.

  That is, before the GaN film 12 is peeled off from the sapphire substrate 11, the upper surface of the buffer material 19 is brought into contact with the surface of the GaN film 12, and after the GaN film 12 is peeled off from the sapphire substrate 11, elasticity below the buffer material 19. The buffer material 19 is filled in the quartz container 15 so that a slight gap is generated between the GaN film 12 and the sapphire substrate 11 due to the deformation and the upward deformation of the sapphire substrate 11.

First, the sapphire / GaN structure W includes an MOCVD method using an organic metal and ammonia (NH ₃ ), and gallium chloride (GaCl) and ammonia (NH ₃ ) by a reaction of gallium (Ga) and hydrogen chloride (HCl). A GaN film 12 was epitaxially grown on the sapphire substrate 11 at a temperature of 1000 ° C. by a hydride VPE method using a silane.

  Next, the buffer material 19 is inserted into the bottom of the substrate holding table 14, and the sapphire / GaN structure W is mounted on the substrate holding table 14 with the GaN film 12 surface facing downward (the sapphire substrate 11 surface side is upward). I put it. At this time, the substrate holder 14 is configured to hold only the sapphire substrate 11 portion of the sapphire / GaN structure W. The buffer material 19 was provided in the substrate holder 14 so as to be bulky enough to contact the surface of the GaN film 12. The substrate holder 14 on which the sapphire / GaN structure W was placed was housed in a quartz container 15 and a laser transmission surface (quartz lid) 16 was attached. The quartz container 15 was housed in an electric furnace composed of heaters 17 and 18.

  The temperature of the sapphire / GaN structure W was raised to 850 ° C. by the heaters 17 and 18. The heating rate was 850 ° C./25 minutes. When the temperature of the thermocouple 20 in the quartz container 15 is stabilized, the laser oscillation device 3 generates a laser beam LB having a wavelength of 355 nm, and the mirror 5 changes the angle of the optical axis from the horizontal direction to the vertical direction. The sapphire / GaN structure W was irradiated (FIG. 5A).

The intensity of the laser beam LB was set to 0.25 J / cm ² , the moving speed of the holding table driving device 8 was set to 0.5 cm / sec, and the entire surface of the sapphire / GaN structure W was irradiated while scanning. When the sapphire / GaN structure W is irradiated with the laser beam LB, the laser beam LB transmitted through the sapphire substrate 11 dissolves the GaN film 12 in the vicinity of the interface between the sapphire substrate 11 and the GaN film 12, and a separation region SA is generated. (FIG. 5B).

  At this time, the sapphire substrate 11 and the GaN film 12 were warped due to the difference between the growth temperature and the peeling temperature, but the temperature spots (unevenness in temperature distribution) of the sapphire / GaN structure W could be suppressed. The SA was expanded smoothly. Further, in the process of peeling off the GaN film 12, the GaN film 12 is supported by the cushioning material 19 with most of its own load. Therefore, stress concentration occurs at the load support point (between the peeling area SA and the non-peeling area). Generation | occurrence | production of was suppressed and the GaN film | membrane 12 was hardly damaged.

  By irradiating the entire surface of the sapphire / GaN structure W with laser, the entire GaN film 12 was peeled off, and a slight gap was formed between the GaN film 12 and the sapphire substrate 11 (FIG. 5C). ). At this time, the GaN film 12 was hardly damaged because the shock of dropping was buffered by the buffer material 19.

  After the GaN film 12 was peeled off, the heaters 17 and 18 were turned off, and the quartz container 15 was cooled. After the temperature was lowered to room temperature, the quartz container 15 was taken out. The laser transmitting surface (quartz lid) 16 was removed, the sapphire substrate 11 was taken out, and then the GaN film 12 was taken out.

  When the surface of the extracted GaN film 12 was observed with a microscope, almost no cracks were generated in the GaN film 12, the decomposition of the surface was suppressed, and the flat state was maintained.

<Example 3>
Example of peeling GaN film 12 from sapphire / GaN structure W in which GaN film 12 having a thickness of 300 μm is formed on sapphire substrate 11 using laser peeling apparatus 1 and the laser peeling method described in the second embodiment Will be described with reference to FIGS. 1, 3, and 6. FIG.

  FIG. 6 is a process cross-sectional view for explaining the laser peeling method according to the present embodiment. The laser peeling method of this example is basically the same as that of Example 2, except that ammonia gas is flow purged into the quartz container and the temperature is raised to the GaN film growth temperature.

First, the sapphire / GaN structure W includes an MOCVD method using an organic metal and ammonia (NH ₃ ), and gallium chloride (GaCl) and ammonia (NH ₃ ) by a reaction of gallium (Ga) and hydrogen chloride (HCl). A GaN film 12 was epitaxially grown on the sapphire substrate 11 at a temperature of 1000 ° C. by a hydride VPE method using

  Next, the buffer material 19 is inserted into the bottom of the substrate holding table 14, and the sapphire / GaN structure W is mounted on the substrate holding table 114 with the GaN film 12 surface facing downward (the sapphire substrate 11 surface side is upward). I put it. At this time, the substrate holder 114 was configured to hold only the sapphire substrate 11 portion of the sapphire / GaN structure W. The substrate holder 114 on which the sapphire / GaN structure W was placed was housed in a quartz container 15 and a laser transmitting surface (quartz lid) 116 was attached. The quartz container 15 was accommodated in an electric furnace composed of heaters 17 and 18.

Nitrogen (N ₂ ) gas was supplied from the gas inlet 116 a to purge the quartz container 15. The purged N ₂ gas was discharged from the exhaust port 116b.

The heaters 17 and 18 were heated up so that the entire sapphire / GaN structure W reached 1040 ° C. At this time, the supply of ammonia (NH ₃ ) gas was started from the time when the temperature reached 500 ° C. At this time, it heated up over 500 minutes to 500 to 1040 degreeC.

  When the temperature of the thermocouple 20 in the quartz container 15 is stabilized, the laser oscillation device 3 generates a laser beam LB having a wavelength of 355 nm, and the mirror 5 changes the angle of the optical axis from the horizontal direction to the vertical direction. The sapphire / GaN structure W was irradiated. At this time, since the sapphire / GaN structure W was heated to the vicinity of the growth temperature of the GaN film 12, the thermal strain was released and the plate was in a flat state (FIG. 6A).

The intensity of the laser beam LB was 0.28 J / cm ² , the moving speed of the holding base driving device 8 was 0.2 cm / sec, and the entire surface of the sapphire / GaN structure W was irradiated while scanning. When the sapphire / GaN structure W is irradiated with the laser beam LB, the laser beam LB transmitted through the sapphire substrate 11 dissolves the GaN film 12 in the vicinity of the interface between the sapphire substrate 11 and the GaN film 12, and a separation region SA is generated. (FIG. 6B).

  At this time, since the thermal strain was released between the sapphire substrate 11 and the GaN film 12, almost no warping occurred. Further, since the buffer material 19 is filled in advance so as to contact the GaN film 12, the GaN film hardly bends due to the weight of the peeled GaN film, and a stress is locally applied to a part of the GaN film 12. Concentration was suppressed.

  By irradiating the entire surface of the sapphire / GaN structure W with laser, the entire GaN film 12 was peeled off, but since the buffer material 19 was filled so as to contact the GaN film 12, the GaN film 12 dropped. The drop impact was buffered, and damage to the GaN film 12 could be suppressed (FIG. 6C).

After the GaN film 12 was peeled off, the heaters 17 and 18 were turned off, and the quartz container 15 was cooled. NH ₃ gas and N ₂ gas were supplied until the temperature in the furnace reached around 500 ° C., and only N ₂ gas was supplied when the temperature became 500 ° C. or lower, and the temperature was lowered to room temperature. The supply of N ₂ gas was stopped, and the quartz container 15 was taken out. After removing the laser transmission surface (quartz lid) 116 and taking out the sapphire substrate 11, the GaN film 12 was taken out.

  When the surface of the extracted GaN film 12 was observed with a microscope, almost no cracks were generated in the GaN film 12, the decomposition of the surface was suppressed, and the flat state was maintained.

<Example 4>
Example in which the GaN film 12 is peeled from the sapphire / GaN structure W in which the GaN film 12 having a thickness of 400 μm is formed on the sapphire substrate 11 by using the laser peeling apparatus 1 and the laser peeling method described in the first embodiment. Will be described with reference to FIG. 1, FIG. 2, and FIG.

FIG. 7 is a process cross-sectional view for explaining the laser peeling method according to the present embodiment. The laser peeling method of this example is basically the same as that of Example 1, except that a silicon dioxide (SiO ₂ ) film 13 is formed on the surface of the GaN film 12.

First, the sapphire / GaN structure W includes an MOCVD method using an organic metal and ammonia (NH ₃ ), and gallium chloride (GaCl) and ammonia (NH ₃ ) by a reaction of gallium (Ga) and hydrogen chloride (HCl). A GaN film 12 was epitaxially grown on the sapphire substrate 11 at a temperature of 1040 ° C. by a hydride VPE method using Next, a silicon dioxide (SiO ₂ ) film 13 was formed on the surface of the GaN film 12 of the sapphire / GaN structure W. The formation of the SiO ₂ film 13 includes a thermal decomposition method (CVD method) by a reaction between silane (SiH ₄ ) and oxygen (O ₂ ) and an electron beam (EB) vapor deposition method using a SiO ₂ raw material. Either one can be used. The thickness of the SiO ₂ film 13 was 0.5 μm.

Next, the buffer material 19 is inserted into the bottom of the substrate holder 14 and the sapphire / GaN structure W on which the SiO ₂ film 13 is formed, with the GaN film 12 surface facing downward (the sapphire substrate 11 surface side is upward). Then, the substrate was placed on the substrate holder 14. At this time, the substrate holder 14 is configured to hold only the sapphire substrate 11 portion of the sapphire / GaN structure W. The substrate holder 14 on which the sapphire / GaN structure W was placed was housed in a quartz container 15 and a laser transmission surface (quartz lid) 16 was attached. The quartz container 15 was housed in an electric furnace composed of heaters 17 and 18.

  The heaters 17 and 18 were heated up so that the entire sapphire / GaN structure W reached 1050 ° C. At this time, it heated up to room temperature -1050 degreeC over 30 minutes.

  When the temperature of the thermocouple 20 in the quartz container 15 is stabilized, the laser oscillation device 3 generates a laser beam LB having a wavelength of 355 nm, and the mirror 5 changes the angle of the optical axis from the horizontal direction to the vertical direction. The sapphire / GaN structure W was irradiated. At this time, since the sapphire / GaN structure W was heated to the GaN film growth temperature, the thermal strain was released and it was in a flat state (FIG. 7A).

The intensity of the laser beam LB was 0.18 J / cm ² , the moving speed of the holding table driving device 8 was 0.15 cm / sec, and irradiation was performed while scanning the entire surface of the sapphire / GaN structure W. When the laser beam LB is irradiated to the sapphire / GaN structure W, the laser beam LB transmitted through the sapphire substrate 11 dissolves the GaN film 12 in the vicinity of the interface between the sapphire substrate 11 and the GaN film 12, and the separation region SA is formed. It occurred (FIG. 7 (b)).

  At this time, in the sapphire substrate 11 and the GaN film 12, the thermal strain was released and almost no warping occurred, so that local concentration of stress on a part of the GaN film 12 was suppressed.

  By irradiating the entire surface of the sapphire / GaN structure W with laser, the entire GaN film 12 was peeled off (FIG. 7C). However, since the impact of the fall was buffered by the buffer material 19, it was possible to suppress the GaN film 12 from being damaged (FIG. 7D).

After the GaN film 12 was peeled off, the power source of the heaters 17 and 18 was shut off and the temperature inside the quartz container 15 was lowered. When the temperature was lowered to room temperature, the quartz container 15 was taken out. After removing the lid 16 and taking out the sapphire substrate 11, the GaN film 12 was taken out. The extracted GaN film 12 was immersed in a mixed solution of hydrogen fluoride (HF) and water, and the SiO ₂ film 13 was removed. After removing the SiO ₂ film 13, it was sufficiently washed with running water and dried.

When the surface of the extracted GaN film 12 was observed with a microscope, almost no cracks were generated in the GaN film 12, the decomposition of the surface was suppressed, and the flat state was maintained. Further, almost no damage on the surface of the GaN film 12 due to the formation of the SiO ₂ film was observed.

  In the above, this invention was demonstrated based on the Example. It is to be understood by those skilled in the art that this embodiment is merely an example, and that various modifications are possible and that such modifications are within the scope of the present invention.

For example, when a SiO ₂ film is provided on the surface of the GaN film, the thickness of the SiO ₂ film is not particularly limited as long as the decomposition of the GaN film surface can be suppressed. Further, the material of the heat resistant film provided on the surface of the GaN film is not limited to SiO ₂ , as long as it is a material capable of suppressing the decomposition of the surface of the GaN film, that is, a material having heat resistance equal to or higher than the GaN film growth temperature. Other materials may be used.

DESCRIPTION OF SYMBOLS 1 Laser peeling apparatus 2 Base 3 Laser oscillation apparatus 4 Laser oscillation apparatus holding stand 5 Mirror 6 Mirror raising / lowering apparatus 7 Slit 8 Holding stand drive apparatus 9 Case 10 Substrate holding part 100 Substrate holding part 11 Sapphire substrate 12 GaN film 13 Protective film 14 Substrate Holding table 114 Substrate holding table 114a Vent 15 Quartz container 16 Quartz lid 116 Quartz lid 116a Gas inlet 116b Gas outlet 17 Heater 18 Heater 19 Buffer material (quartz cloth, quartz wool)
20 Thermocouple 31 Laser Peeling Device 32 Base 33 Laser Oscillator 34 Laser Oscillator Holding Table 35 Substrate Holding Unit 36 Holding Table Drive Device (Horizontal Direction)
37 Holding stand drive device (vertical direction)
38 Case LB Laser light SA Peeling area W Sapphire / GaN structure

Claims (13)

A laser peeling apparatus for peeling a group III nitride semiconductor film by laser irradiation from a structure including a base substrate and a group III nitride semiconductor film provided on the base substrate,
A substrate holding unit for holding the structure without contacting the group III nitride semiconductor film in a state where the group III nitride semiconductor film is directed downward or laterally;
A laser irradiation unit for irradiating the surface of the structure with a laser;
A laser peeling apparatus comprising: In the laser peeling apparatus of Claim 1,
The laser separation apparatus, wherein the substrate holding unit is configured to support the structure in a region of the surface of the base substrate where the group III nitride semiconductor film is not provided. In the laser peeling apparatus of Claim 1 or 2,
A container for storing the substrate holder;
A nitrogen gas supply unit for filling the container with a nitrogen-containing gas;
A laser peeling apparatus, further comprising: In the laser peeling apparatus in any one of Claims 1 thru | or 3,
A heater for heating the structure;
The laser peeling apparatus, wherein the heater is provided at a position away from the structure. A laser peeling apparatus for peeling a group III nitride semiconductor film by laser irradiation from a structure including a base substrate and a group III nitride semiconductor film provided on the base substrate,
A container,
A nitrogen gas supply unit for filling the container with a nitrogen-containing gas;
A substrate holder that is provided in the container and holds the structure;
A laser irradiation unit for irradiating the structure with a laser;
A laser peeling apparatus comprising: A laser peeling apparatus for peeling a group III nitride semiconductor film by laser irradiation from a structure including a base substrate and a group III nitride semiconductor film provided on the base substrate,
A substrate holder for holding the structure;
A heater provided at a position away from the structure, and heating the structure;
A laser irradiation unit for irradiating the structure with a laser;
A laser peeling apparatus comprising: In the laser peeling apparatus in any one of Claims 1 thru | or 6,
A laser peeling apparatus, further comprising a buffer material provided at a lower portion of the substrate holding portion. A laser peeling method for peeling a group III nitride semiconductor film by laser irradiation from a structure including a base substrate and a group III nitride semiconductor film provided on the base substrate,
Holding the structure without contacting the surface of the group III nitride semiconductor film, with the group III nitride semiconductor film facing downward or laterally;
Irradiating the structure with a laser;
Peeling the group III nitride semiconductor film from the structure;
A laser peeling method comprising: In the laser peeling method of Claim 8,
The step of holding the structure includes a step of supporting the structure in a region of the surface of the base substrate where the group III nitride semiconductor film is not provided. A laser peeling method for peeling a group III nitride semiconductor film by laser irradiation from a structure including a base substrate and a group III nitride semiconductor film provided on the base substrate,
Holding the structure;
Replacing the atmospheric gas of the structure with a nitrogen-containing gas;
Irradiating the structure with a laser;
Peeling the group III nitride semiconductor film from the structure;
A laser peeling method comprising: A laser peeling method for peeling a group III nitride semiconductor film by laser irradiation from a structure including a base substrate and a group III nitride semiconductor film provided on the base substrate,
Holding the structure;
Heating the structure with a heater provided at a position away from the structure;
Irradiating the structure with a laser;
Peeling the group III nitride semiconductor film from the structure;
A laser peeling method comprising: In the laser peeling method in any one of Claims 8 thru | or 11,
Before the step of irradiating the laser,
The laser peeling method characterized by further including the process of forming the protective film which has the heat resistant temperature more than the growth temperature of the said group III nitride semiconductor film on the surface of the said group III nitride semiconductor film among the said structures. A group III nitride semiconductor including at least a part of the group III nitride semiconductor film by peeling the group III nitride semiconductor film from the structure by the laser peeling method according to claim 8. A method of manufacturing a group III nitride semiconductor free-standing substrate, comprising a step of obtaining a free-standing substrate.

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