JP5333156B2 - Vapor growth equipment - Google Patents

Description

The present invention relates to a vapor phase growth apparatus for epitaxially growing an Al _x Ga _y In _z N (where x + y + z = 1) film on a substrate by a metal organic chemical vapor deposition (MOCVD) method. _x Ga y _In z _N film can be obtained, relating to vapor phase growth apparatus which can improve productivity.

Group III-V nitride semiconductor films, especially Al _x Ga _y In _z N (where x + y + z = 1) films are used as materials for electronics and optoelectronics. As an epitaxial growth method of Al _x Ga _y In _z N film, MOCVD method or MOVPE (Metalorganic Vapor Phase Epitaxy) method are generally known, chloride vapor-phase epitaxial recently (Hydride Vapor Phase Epitaxy: HVPE) method is also Proposed.

  When a GaN film is formed by the HVPE method, gallium metal is loaded into a reaction furnace in which a sapphire substrate having a GaN thin film formed on the surface is held, and hydrochloric acid gas is introduced into the reaction furnace to generate gallium chloride gas. This is reacted with ammonia gas to deposit a GaN film. This HVPE method has a higher deposition rate than the MOCVD method and the MOVPE method. For example, the typical film formation rate of the GaN film by the MOVPE method is several μm / hour, but the typical film formation rate of the GaN film by the HVPE method is several hundred μm / hour. Therefore, the HVPE method is advantageous when forming a group III-V nitride semiconductor film having a large film thickness.

However, the HVPE method has a problem that it is difficult to obtain a good Al _x Ga _y In _z N (where x + y + z = 1) film, and the film thickness variation in the substrate is relatively large. Further, the MOVPE method has a problem that the film forming speed is slow and the cost is high. Therefore, the MOCVD method is used for epitaxial growth of the Al _x Ga _y In _z N (where x + y + z = 1) film.

The inner wall of the reactor of the apparatus using the MOCVD method is generally made of quartz (SiO ₂ ). And the top plate (attachment plate) attached to the inner wall of the ceiling part of the reactor so as to face the substrate is also made of quartz (for example, see Patent Document 1). Since a deposit film is deposited on the top plate during crystal growth, it is necessary to periodically replace the top plate on which the deposit film is deposited with a cleaned top plate.

JP-A-5-144734

The difference in the growth temperature of the Al _x Ga _y In _z N (where x + y + z = 1) film is larger than that of other III-V group semiconductor films. Therefore, the top plate bends greatly during the growth of the Al _x Ga _y In _z N (where x + y + z = 1) film. For this reason, a crack is generated in the deposition film deposited on the top plate, and the deposition film is peeled off from the crack and dropped onto the substrate, and the characteristics of the Al _x Ga _y In _z N (x + y + z = 1) film are remarkably increased. There was a problem of deterioration. In order to prevent this, it is necessary to replace the top plate in a short cycle, and there is a problem that productivity is deteriorated.

The present invention has been made in order to solve the above-described problems, and an object of the present invention is to obtain a high-quality Al _x Ga _y In _z N film and to improve the productivity by vapor phase growth. Get the device.

The present invention relates to a vapor phase growth apparatus for epitaxially growing an Al _x Ga _y In _z N (x + y + z = 1) film on a substrate by MOCVD, a reaction furnace, a susceptor holding the substrate in the reaction furnace, An introduction part for introducing a source gas into the reaction furnace; a deposition plate attached to the inner wall of the reaction furnace so as to face the substrate; and a surface of the deposition plate on the substrate side, GaN A vapor phase growth apparatus comprising a multilayer film in which films and AlN films are alternately stacked.

According to the present invention, a high-quality Al _x Ga _y In _z N film can be obtained, and productivity can be improved.

It is a figure which shows the vapor phase growth apparatus which concerns on Embodiment 1 of this invention. It is a figure which shows the vapor phase growth apparatus which concerns on Embodiment 2 of this invention. It is a figure which shows the vapor phase growth apparatus which concerns on Embodiment 3 of this invention. It is a perspective view which shows the adhesion prevention board which concerns on Embodiment 3 of this invention.

Embodiment 1 FIG.
FIG. 1 is a diagram showing a vapor phase growth apparatus according to Embodiment 1 of the present invention. A susceptor 14 that holds the substrate 12 horizontally is provided in the reaction furnace 10. The heating device 16 heats the substrate 12 to a predetermined temperature via the susceptor 14.

  The introduction unit 18 introduces an introduction pipe 22 for introducing an organometallic raw material 20 that is trimethylaluminum, trimethylgallium, trimethylindium, or a mixed gas of two or more of these, and an introduction of ammonia 24 that is a nitrogen raw material. Connected to the tube 26. The introduction unit 18 introduces these raw material gases into the reaction furnace 10 together with a carrier gas such as hydrogen or nitrogen. A gas exhaust port 28 is provided in the outer periphery of the reaction furnace 10, and the gas exhaust port 28 is connected to an exhaust system.

A top plate 30 (a deposition plate) made of quartz (SiO ₂ ) is attached to the inner wall of the ceiling of the reaction furnace 10 so as to face the substrate 12. A multilayer film 32 in which 20 layers of GaN films and AlN films are alternately laminated is formed on the surface of the top plate 30 on the substrate 12 side. The film thickness of one layer of the GaN film and the AlN film is 200 nm.

This vapor phase growth apparatus MOCVDs an Al _x Ga _y In _z N (where x + y + z = 1) film, that is, an AlN film, a GaN film, an InN film, an AlGaN film, an AlInN film, a GaInN film, or an AlGaInN film on a substrate 12. Epitaxially grown by the method. That is, the metal nitride generated by the reaction between the organometallic raw material 20 introduced into the reaction furnace 10 and the ammonia 24 is deposited on the heated substrate 12. At this time, a deposition film made of Al _x Ga _y In _z N (x + y + z = 1) is also deposited on the surface of the top plate 30.

As described above, the multilayer film 32 includes a GaN film (thermal expansion coefficient: 5.59 × 10 ⁻⁶ / K) and an AlN film (thermal expansion coefficient: 4.15 × 10 ⁻⁶ / K) having a large difference in thermal expansion coefficient. ) Are alternately stacked. Therefore, the internal stress generated between the deposition film and the top plate 30 is relieved by the multilayer film 32.

Thereby, it can suppress that a deposit film peels from the top plate 30. FIG. Therefore, a good quality Al _x Ga _y In _z N film can be obtained uniformly in the plane. Moreover, since the replacement cycle of the top plate 30 can be greatly extended, productivity can be improved.

  Note that the first layer of the multilayer film 32 may be either a GaN film or an AlN film, and the film thickness and the number of stacked layers are not limited to the above example. In order to form the multilayer film 32, the temperature in the reactor 10 is raised to 1000 ° C., trimethylgallium and ammonia gas are introduced into the reactor 10 to deposit a GaN film, and trimethylaluminum and ammonia gas are introduced. AlN is deposited.

Embodiment 2. FIG.
FIG. 2 is a diagram showing a vapor phase growth apparatus according to Embodiment 2 of the present invention. Instead of the quartz top plate 30 of the first embodiment, a top plate 34 made of alumina (Al ₂ O ₃ ) is provided. Other configurations are the same as those of the first embodiment.

The thermal expansion coefficient of GaN is 5.59 × 10 ⁻⁶ / K, the thermal expansion coefficient of AlN is 4.15 × 10 ⁻⁶ / K, the thermal expansion coefficient of SiO ₂ is 8 × 10 ⁻⁶ / K, and Al ₂ O. The coefficient of thermal expansion of ₃ is 5.3 × 10 ⁻⁶ / K. Therefore, since the difference in coefficient of thermal expansion between the top plate 34 and the deposition film is smaller than that in the first embodiment, it is possible to further suppress peeling of the deposition film.

Even when the top plate 34 is made of silicon carbide (SiC) (thermal expansion coefficient: 4.2 × 10 ⁻⁶ / K), a certain degree of effect can be obtained. However, it is preferable to use a top plate 34 made of alumina.

Embodiment 3 FIG.
FIG. 3 is a diagram showing a vapor phase growth apparatus according to Embodiment 3 of the present invention. FIG. 4 is a perspective view showing a deposition preventing plate according to Embodiment 3 of the present invention. A top plate 36 is provided instead of the top plate 30 of the first embodiment. Other configurations are the same as those of the first embodiment.

A lattice-shaped groove 38 is formed on the surface of the top plate 36 made of quartz (SiO ₂ ) by cutting or blast polishing. Thereby, since the adhesiveness of a deposition film and the top plate 30 improves compared with Embodiment 1, it can further suppress that a deposition film peels.

  However, it is not preferable to apply extreme irregularities in order to prevent turbulent flow from being generated in various gases flowing during crystal growth. Therefore, the depth and width of the groove 38 are set to about 1/5 to 1/10 of the thickness of the top plate 36. Moreover, it is preferable that the space | interval of the groove | channel 38 is smaller than the size of the deposit film which peels, for example, is about 5 mm.

  The depth, width, and interval of the groove 38 are not limited to the above example. Moreover, it is preferable that the top plate 36 is made of alumina as in the second embodiment.

10 Reactor 12 Substrate 14 Susceptor 18 Introduction part 30, 34, 36 Top plate (protection plate)
32 Multilayer film 38 Groove

Claims (3)

In a vapor phase growth apparatus for epitaxially growing an Al _x Ga _y In _z N (where x + y + z = 1) film on a substrate by MOCVD,
A reactor,
A susceptor for holding the substrate in the reaction furnace;
An introduction part for introducing a raw material gas into the reaction furnace;
A deposition plate attached to the inner wall of the reactor so as to face the substrate;
A vapor phase growth apparatus, comprising: a multilayer film formed on a surface of the deposition preventing plate on the substrate side, wherein GaN films and AlN films are alternately laminated.   The vapor deposition apparatus according to claim 1, wherein the deposition preventing plate is made of alumina.   The vapor phase growth apparatus according to claim 1 or 2, wherein a groove is formed on a surface of the deposition preventing plate.

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