A growth apparatus and method for GaN

Abstract

The application discloses a GaN growth device and a preparation method. The application provides a GaN growth device which is divided into two parts, an inner part and an outer part. The outer part is a guide growth ring with a circular through hole block structure in the middle, and the inner part is a suppression growth ring with a hollow cylindrical structure. According to the structure, a GaN preparation method is provided. The outer periphery of the guide growth ring is away from the central through hole area, and the solid-gas boundary is extended, so that the GaN defects generated by the solid-gas boundary can effectively grow on the GaN polycrystal outside the quartz tray, and the growth of the bad GaN polycrystal is carried out outside the quartz tray. The material of the suppression growth ring is a material with small specific heat capacity and small heat conductivity. During work, the temperature of the material is obviously higher than the GaN single crystal growth temperature in the reaction cavity, so that the temperature difference of the edge of the GaN thick film substrate is large enough, and the edge growth rate can be completely inhibited.

Description

Technical Field

[0001] This invention relates to the field of semiconductors, and more specifically to a GaN growth apparatus and preparation method. Background Technology

[0002] GaN is an important wide-bandgap semiconductor material, widely used in the fabrication of high-brightness LEDs, semiconductor lasers, and high-power electronic devices. Currently, hydride vapor phase epitaxy (HVPE) is the primary method for preparing GaN single-crystal thick-film substrates. This method is typically carried out in a atmospheric pressure heated quartz reactor. The basic chemical reaction involves gaseous HCl reacting with liquid metallic Ga at a low temperature to generate gaseous GaCl. GaCl then reacts with NH3 at a high temperature to form a GaN thin film. The reaction byproducts HCl and H2 can be recovered as gases. The preparation of GaN via HVPE requires two chemical steps: a low-temperature reaction and a high-temperature reaction. Therefore, the HVPE reactor needs to be divided into low-temperature and high-temperature zones. Furthermore, many parameters need to be adjusted during this process to achieve controllable GaN film deposition.

[0003] Because of the edge effect at the boundary between two substances—that is, the phenomenon of resource competition always exists at the boundary between different substances—the boundary of material growth always exhibits a completely abrupt growth phenomenon compared to the interior of the substance. For example... Figure 1 As shown, traditional HVPE reactor trays exhibit a sudden increase in the edge growth rate (far exceeding that at the film center) during GaN single crystal growth, resulting in an edge thickness greater than the center thickness of the prepared GaN single crystal thick film substrate. Furthermore, GaN growth defects also occur at the solid-gas boundary during GaN single crystal growth, i.e., GaN polycrystalline growth at the edge, which severely affects the quality of the single-crystal GaN thick film. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides a GaN growth apparatus and a preparation method.

[0005] A GaN growth apparatus, comprising:

[0006] The growth suppression ring is cylindrical and provides the space required for GaN single crystal growth. The material of the growth suppression ring is such that it has a higher temperature than the internal space under heating conditions, so that the region closer to the growth suppression ring has a lower growth rate during GaN single crystal growth.

[0007] A guide growth ring is fitted onto at least a portion of the inhibit growth ring. One surface of the guide growth ring and the end face of the inhibit growth ring are on the same horizontal plane. The guide growth ring is made of GaN polycrystalline material, and its edge shape is designed to make it easier for GaN polycrystalline material to grow on the guide growth ring.

[0008] Preferably, the material of the growth inhibition ring is one or more of the following: tantalum carbide, tungsten carbide, molybdenum carbide, osmium carbide, iridium carbide, rhenium carbide, niobium carbide, titanium carbide, zirconium carbide, yttrium carbide, and tantalum nitride.

[0009] Preferably, the edge shape of the guiding growth ring is a discontinuous outward protruding structure.

[0010] Preferably, the connection method at the junction of the growth inhibition ring and the growth guide ring includes high-temperature bonding with BCB adhesive, mechanical fixation, and high-temperature welding.

[0011] Preferably, the height of the growth inhibition ring is 2-3 mm and the inner diameter is 50.8-101.6 mm.

[0012] Preferably, it further includes an automatic lifting device configured to raise the height of the GaN growth equipment, such that the surfaces of the guide growth ring and the inhibition growth ring, which are flush with each other, are always at a height close to the surface of the GaN single crystal being grown.

[0013] A method for preparing GaN, using the GaN growth apparatus described above, includes:

[0014] A seed crystal for GaN crystal growth is placed, the diameter and height of which are equal to the inner diameter and height of the confining growth ring;

[0015] The GaN growth equipment is nested around the seed crystal;

[0016] Initiate GaN growth;

[0017] During GaN single crystal growth, the temperature of the suppression growth ring is higher than that of the GaN single crystal growth in the reaction chamber, thereby suppressing the sudden increase in the edge growth rate; the guide growth ring extends the solid-gas boundary to the outside of the GaN single crystal growth region, thereby effectively guiding the growth of GaN defects generated by the solid-gas boundary to occur on the GaN polycrystalline material outside the quartz tray.

[0018] Preferably, the substrate is sapphire, silicon, silicon carbide, gallium oxide, or gallium nitride.

[0019] Preferably, the GaN preparation method further includes: after GaN growth is completed, cleaning the GaN growth equipment to remove parasitic deposits on the surface of the GaN growth equipment during the growth process.

[0020] Preferably, the GaN preparation method further includes: when the GaN thick film is grown on the tray, the auxiliary equipment effectively detects the distance between the automatic lifting device and the surface of the GaN thick film and gives a signal indication, and the automatic lifting device raises the height accordingly as the film thickness grows.

[0021] The beneficial effects of this invention are as follows: This invention discloses a GaN growth apparatus and preparation method. The GaN growth apparatus consists of two parts: an outer block-shaped guide growth ring with a central circular through-hole, and an inner hollow cylindrical suppression growth ring. The inner diameter of the guide growth ring is the same as the outer diameter of the suppression growth ring, and the guide growth ring is nested on the upper part of the suppression growth ring. The periphery of the guide growth ring is far from the central through-hole region, extending the solid-gas boundary, thereby effectively guiding the growth of GaN growth defects generated at the solid-gas boundary to the GaN polycrystalline material outside the GaN growth apparatus, allowing unfavorable GaN polycrystalline defects to grow on the GaN polycrystalline material outside the quartz tray. The suppression growth ring is made of a material with low specific heat capacity and low thermal conductivity. During operation, the temperature of this material is significantly higher than the GaN single crystal growth temperature inside the reaction chamber, ensuring a sufficiently large temperature difference at the edge of the GaN thick film substrate, which can completely suppress sudden increases in the edge growth rate. Attached Figure Description

[0022] Figure 1 It is a GaN single crystal (symmetrical half) grown in a conventional HVPE reactor tray.

[0023] Figure 2 This is a schematic diagram of the GaN growth equipment of the present invention.

[0024] Figure 3 The XRD test results are of the GaN growth equipment of this invention and the GaN single crystal grown when not in use.

[0025] Figure 4 This is a comparison of the Raman spectra of GaN single crystals grown using the GaN growth equipment of this invention and those grown without it.

[0026] The labels in the figure are as follows: 101, tray; 102, substrate; 103, growth inhibition ring; 104, growth guide ring. Detailed Implementation

[0027] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, so that those skilled in the art can better understand and implement the present invention. However, the embodiments described are not intended to limit the present invention.

[0028] In traditional HVPE reactor trays, GaN growth is hampered by edge effects at the boundary between the two materials. This leads to a sudden increase in the edge growth rate, resulting in edge protrusions and abnormal GaN growth defects at the solid-gas boundary, causing polycrystalline GaN growth at the edge. This severely affects the quality of thick films on single-crystal GaN substrates. To improve and reduce these defects, this invention provides a GaN growth apparatus and preparation method.

[0029] like Figure 1 As shown, the GaN growth apparatus of the present invention is divided into two parts: an inner growth inhibition ring 103 and an outer growth guide ring 104.

[0030] The growth suppression ring 103 is cylindrical, and its interior is a reserved GaN single-crystal growth region. The height of the growth suppression ring 103 is H1, and its inner diameter is D. 11 The outer diameter of the growth inhibition ring 103 is D. 12 The seed crystal used for GaN crystal growth has a height of h and a diameter of d, satisfying H1 = h, D 11 =d,D 12 >D 11 Typically, H1 is 2–3 mm; D 11 The diameter is 50.8–101.6 mm.

[0031] The growth suppression ring 103 is made of a material that does not decompose at high temperatures and has good thermal stability, such as one or more of tantalum carbide, tungsten carbide, molybdenum carbide, osmium carbide, iridium carbide, rhenium carbide, niobium carbide, titanium carbide, zirconium carbide, yttrium carbide, and tantalum nitride. This material has a low specific heat capacity and low thermal conductivity. During operation, the temperature of this material is significantly higher than the GaN single crystal growth temperature in the reaction chamber, ensuring a sufficiently large temperature difference at the edge of the GaN thick film substrate, which can completely suppress the sudden increase in the edge growth rate. Since the uniformity of the grown GaN thickness deteriorates as the temperature in the reaction chamber increases, and the lower-temperature areas grow thicker, a higher edge growth temperature can effectively suppress the sudden increase in the edge growth rate.

[0032] The guiding growth ring 104 is sleeved on at least a portion of the inhibiting growth ring 103. One surface of the guiding growth ring 104 and the end face of the inhibiting growth ring 103 are on the same horizontal plane. The height of the guiding growth ring 104 is H2, and the inner diameter of the guiding growth ring 104 is D. 21 The outer diameter of the growth ring 104 is D. 22 Satisfying H2 21 =D 12 D 22 >D 21 .

[0033] ​The growth guide ring 104 is made of GaN polycrystalline. The periphery of the growth guide ring 104 is far from the GaN single-crystal growth region, extending the solid-gas boundary. This effectively guides the growth of GaN defects generated at the solid-gas boundary to occur on the GaN polycrystalline surface outside the quartz tray, allowing these defective GaN polycrystalline deposits to grow outside the quartz tray. This effectively ensures stable and high-quality growth of the GaN single-crystal block inside the GaN growth equipment.

[0034] The growth guide ring 104 is nested outside the growth inhibitor ring 103. The upper surface of the growth guide ring 104 is flush with the upper surface of the growth inhibitor ring 103. They are connected by high-temperature bonding, mechanical fixation, high-temperature welding, etc. with BCB adhesive.

[0035] During operation, the GaN growth equipment is placed in the growth zone of the HVPE reactor. A seed crystal for GaN crystal growth is placed in the growth zone of the HVPE reactor, with the growth suppression ring 103 of the GaN growth equipment nested around the seed crystal. At this time, the upper surface of the seed crystal is flush with the upper surface of the GaN growth equipment.

[0036] The present invention also provides a method for preparing GaN, using the GaN growth equipment described above, comprising: placing a seed crystal for GaN crystal growth; nesting the GaN growth equipment around the seed crystal; starting GaN growth; during GaN single crystal growth, since the temperature of the growth ring 103 is higher than the GaN single crystal growth temperature in the reaction chamber, the sudden increase in the edge growth rate is suppressed; and the growth ring 104 extends the solid-gas boundary to the outside of the GaN single crystal growth region, thereby effectively guiding the GaN growth abnormal defects generated by the solid-gas boundary to grow onto the GaN polycrystalline material outside the GaN growth equipment.

[0037] After one crystal growth cycle, the GaN growth equipment is removed from the growth zone of the HVPE reactor. Temperature and pressure are controlled, and a cleaning gas is used to perform a thermal cleaning process to remove the parasitic deposits on the surface of the GaN growth equipment during the growth process, so that the GaN growth equipment can be reused.

[0038] In an optional embodiment, the GaN growth apparatus of the present invention further includes an automatic lifting device. The lower surface of the growth ring 104 is used as a support surface by the GaN growth apparatus. When the GaN thick film is grown on the tray, the automatic lifting device can be quickly responded to by the auxiliary equipment effectively detecting the distance between the automatic lifting device and the surface of the GaN thick film and giving a signal indication. The height is raised accordingly as the film thickness grows, so that the surface of the guide growth ring 104 and the inhibition growth ring 103 is always at a similar height to the surface of the growing GaN single crystal.

[0039] In this embodiment, the inhibition growth ring 103 of the GaN growth apparatus is cylindrical with a circular through-hole at the center. The height of the inhibition growth ring 103 is H1 = 2 mm, and the inner diameter of the inhibition growth ring 103 is D. 11 = 50.8mm, the outer diameter of the growth inhibition ring 103 is D 12 =52mm; the guiding growth ring 104 is a discontinuous outward protruding structure with a circular through hole in the center. The height of the guiding growth ring 104 is H2 = 0.5mm, and the inner diameter of the guiding growth ring 104 is D. 21 =52mm, the outer diameter of the growth inhibition ring 103 is D 22 =55mm. In the process of GaN polycrystalline growth, the sharp part requires less energy for nucleation and crystal growth compared to other regions, both kinetically and thermodynamically. Therefore, the discontinuous outward protruding structure design can better guide the GaN polycrystalline growth to the outermost position away from the GaN single crystal block.

[0040] In this embodiment, the substrate layer is selected from sapphire, silicon, silicon carbide, gallium oxide, or gallium nitride.

[0041] like Figure 2 As shown, the left figure is a side view of the GaN growth apparatus of this embodiment, and the right figure is a top view of the GaN growth apparatus of this embodiment. The tray 101 has a groove in its center, and a sapphire substrate 102 is disposed in the groove. A seed crystal for GaN crystal growth is placed on the sapphire substrate 102 within the groove of the tray 101, and the GaN growth apparatus is nested around the seed crystal. The seed crystal is located within the central through-hole of the inhibition growth ring 103 of the GaN growth apparatus, and its upper surface is flush with the upper surfaces of both the inhibition growth ring 103 and the guide growth ring 104 of the GaN growth apparatus.

[0042] When tray 101 is placed in the growth zone of the HVPE reactor, the sudden increase in edge growth rate is suppressed because the temperature of the growth suppression ring 103 is higher than the GaN single crystal growth temperature inside the reaction chamber. The guide growth ring 104 extends the solid-gas boundary to the outside of the GaN single crystal growth zone, thereby effectively guiding the growth of GaN defects generated at the solid-gas boundary to occur on the GaN polycrystalline material outside the quartz tray. This ultimately yields a high-quality GaN single crystal block inside the GaN growth equipment.

[0043] Under the same growth parameters, comparing single crystals grown using the growth equipment of the present invention with guide growth rings and inhibit growth rings with single crystals grown without the growth equipment of the present invention, it can be seen that without the GaN growth equipment, there are a large number of GaN polycrystals at the edge of the GaN thick film and the edge thickness is greater than the center thickness, with many unevenly distributed polycrystals and protrusions at the edge; while with the GaN growth equipment, the growth of polycrystals and protrusions at the edge of the GaN thick film can be effectively suppressed, forming a GaN thick film with uniform edge thickness and center thickness.

[0044] To objectively demonstrate the effect of adding GaN growth equipment on suppressing polycrystalline growth and protrusions at the edges of thick GaN films, the half-width at half-maximum (WWHM) of single crystals grown using the equipment of this invention and those grown without this invention was measured. Figure 3 As shown, a narrower half-width (FWHM) indicates better crystal quality. The GaN single crystal grown without GaN (sample B) has a significantly larger FWHM than the GaN single crystal grown with GaN (sample A), demonstrating the effectiveness of the GaN growth equipment in suppressing polycrystalline growth and protrusions at the edges of thick GaN films. The GaN single crystal grown using GaN growth equipment exhibits sharper peaks because the GaN growth equipment effectively controls the defects of polycrystalline GaN transport at the edges of the GaN single crystal.

[0045] like Figure 4 The results shown are Raman spectroscopy measurements obtained using a Raman spectrometer. The left curve represents the Raman spectrum of a GaN single crystal (sample A) grown using a GaN-added growth device, while the right curve represents the Raman spectrum of a GaN single crystal (sample B) grown using a GaN-free growth device. As can be seen from the figure, the Raman spectrum peaks red-shift after adding GaN growth equipment. During the GaN single crystal growth process, it is easy to guide the growth of polycrystalline GaN at the edge outside the quartz tray and to relax the residual stress inside the GaN single crystal. These experimental data confirm that using GaN growth equipment can improve the growth quality of GaN single crystals.

[0046] The above-described embodiments are merely preferred embodiments provided to fully illustrate the present invention, and the scope of protection of the present invention is not limited thereto. Equivalent substitutions or modifications made by those skilled in the art based on the present invention are all within the scope of protection of the present invention. The scope of protection of the present invention is defined by the claims.

Claims

1. A GaN growth apparatus, characterized in that: include: The growth suppression ring is cylindrical and provides the space required for GaN single crystal growth. The material of the growth suppression ring is such that it has a higher temperature than the internal space under heating conditions, so that the region closer to the growth suppression ring has a lower growth rate during GaN single crystal growth. A guide growth ring is fitted onto at least a portion of the inhibit growth ring. One surface of the guide growth ring and the end face of the inhibit growth ring are on the same horizontal plane. The guide growth ring is made of GaN polycrystalline material, and its edge shape is designed to make it easier for GaN polycrystalline material to grow on the guide growth ring. The edge shape of the guiding growth ring is a discontinuous, outward-protruding structure.

2. The GaN growth apparatus as described in claim 1, characterized in that: The growth inhibition ring is made of one or more of the following materials: tantalum carbide, tungsten carbide, molybdenum carbide, osmium carbide, iridium carbide, rhenium carbide, niobium carbide, titanium carbide, zirconium carbide, yttrium carbide, and tantalum nitride.

3. The GaN growth apparatus as described in claim 1, characterized in that: The connection methods at the junction of the growth inhibition ring and the growth guide ring include high-temperature bonding with BCB adhesive, mechanical fixation, and high-temperature welding.

4. The GaN growth apparatus as described in claim 1, characterized in that: The height of the growth inhibition ring is 2-3 mm, and the inner diameter is 50.8-101.6 mm.

5. The GaN growth apparatus as described in claim 1, characterized in that: It also includes an automatic lifting device configured to raise the height of the GaN growth equipment, such that the surfaces of the guide growth ring and the inhibition growth ring, which are flush with each other, are always at a height close to the surface of the GaN single crystal being grown.

6. A method for preparing GaN, characterized in that: Using the GaN growth apparatus as described in any one of claims 1-5, comprising: A seed crystal for GaN crystal growth is placed, the diameter and height of which are equal to the inner diameter and height of the inhibition growth ring; The GaN growth equipment is nested around the seed crystal; Initiate GaN growth; During GaN single crystal growth, the temperature of the suppression growth ring is higher than that of the GaN single crystal growth in the reaction chamber, thereby suppressing the sudden increase in the edge growth rate; the guide growth ring extends the solid-gas boundary to the outside of the GaN single crystal growth region, thereby effectively guiding the growth of GaN defects generated by the solid-gas boundary to occur on the GaN polycrystalline material outside the quartz tray.

7. The method for preparing GaN as described in claim 6, characterized in that: The substrate is made of sapphire, silicon, silicon carbide, gallium oxide, or gallium nitride.

8. The method for preparing GaN as described in claim 6, characterized in that: Also includes: After GaN growth is completed, the GaN growth equipment is cleaned to remove parasitic deposits on the surface of the GaN growth equipment during the growth process.

9. The method for preparing GaN as described in claim 6, characterized in that: Also includes: When GaN thick films are grown on a tray, the auxiliary equipment effectively detects the distance between the automatic lifting device and the surface of the GaN thick film and gives a signal indication. The automatic lifting device raises its height accordingly as the film thickness grows.

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