Deposition-free HVPE gas conveying structure for improving crystal growth uniformity

Abstract

The utility model discloses a deposition-free HVPE gas conveying structure for improving crystal growth uniformity, which comprises a shielding gas conveying pipeline, a metal gas conveying pipeline and a nitrogen-containing gas conveying pipeline, the metal gas conveying pipeline is positioned in the shielding gas conveying pipeline, and the nitrogen-containing gas conveying pipeline is positioned in the shielding gas conveying pipeline. The tail end of the metal gas conveying pipeline is located in the shielding gas conveying pipeline, the nitrogen-containing gas conveying pipeline is a square pipe and located above the shielding gas conveying pipeline, and the nitrogen-containing gas conveying pipeline is closer to a substrate relative to the shielding gas conveying pipeline. The gas conveying structure has the beneficial effects that by optimizing the geometrical shape and size design of the gas conveying structure, mixed precursor gas is prevented from being attached to the outer wall of the gas conveying pipeline, so that the structure is prevented from being broken; and meanwhile, the airflow uniformity of the process gas is optimized, so that the precursor gas is more uniformly distributed on the surface of the substrate.

Description

Technical Field

[0001] The utility model relates to the technical field of gallium nitride production, in particular to a horizontal HVPE deposition-free gas delivery structure, which can improve the uniformity of gallium nitride crystal growth. Background Art

[0002] The typical structure of the reaction chamber for growing nitride semiconductor materials by hydride vapor phase epitaxy (HVPE) is a two-temperature zone structure, that is: the gallium boat is placed in the low-temperature zone, using metallic gallium as the group III gallium source, the reaction gas hydrogen chloride (HCl) and its carrier gas (hydrogen or nitrogen) pass through the gallium boat, react with metallic gallium to generate gallium chloride (GaCl), GaCl is carried by the carrier gas (hydrogen or carrier gas) to the high-temperature zone, and reacts with ammonia (NH3) in the high-temperature zone to generate gallium nitride (GaN), and GaN single crystals are deposited on the substrate. The main chemical reactions are as follows:

[0003] 2HCl(g) + 2Ga(l) = 2GaCl(g) + H2(g);

[0004] GaCl(g) + NH3(g) = GaN (s) + HCl(g) + H2(g)

[0005] The conventional horizontal HVPE reaction gas path is that the nitrogen-containing precursor gas, the metal-containing precursor gas path, and the inert dilution shielding gas delivery pipeline are arranged in layers. The above gases diffuse into the mixing zone within a similar range, in order to make the reaction sources mix evenly after reaching the substrate surface and form a deposition on the substrate. However, the horizontal HVPE reaction source gas is different from the vertical HVPE. The effect of gravity in the vertical direction on gas transmission in the horizontal HVPE structure is more obvious, making it difficult to control the position of the gas mixing zone, and it is easy to cause parasitic deposition of the reaction structure due to premature mixing, or reduce the utilization rate due to delayed mixing. Another common method is that the metal-containing precursor gas delivery structure directly reaches near the substrate, and the reaction gases are directly mixed near the substrate. This design makes the outlet of the metal-containing precursor gas path surrounded by the NH3 atmosphere, resulting in a large amount of deposition in this structure. The problem of parasitic deposition in the reaction chamber is a major difficulty in HVPE technology. The deposition at the outlet not only affects the quality of the epitaxial layer but also reduces the utilization rate of raw materials. Summary of the Utility Model

[0006] The technical problem to be solved by the utility model is the parasitic deposition of the existing horizontal HVPE reaction chamber structure and the difficulty in controlling the uniformity of crystal growth. Therefore, a reaction gas delivery structure for preparing nitride semiconductor materials by hydride vapor phase epitaxy is provided, which can control the flow direction of process gases and improve the utilization rate of process gases.

[0007] The technical solution of the present utility model is: a deposition-free HVPE gas delivery structure for improving the uniformity of crystal growth, including: a shielding gas delivery pipeline, a metal gas delivery pipeline, and a nitrogen-containing gas delivery pipeline. The metal gas delivery pipeline is located inside the shielding gas delivery pipeline, and the end of the metal gas delivery pipeline is located inside the shielding gas delivery pipeline. The nitrogen-containing gas delivery pipeline is a square pipe and is located above the shielding gas delivery pipeline. The nitrogen-containing gas delivery pipeline is closer to the substrate than the shielding gas delivery pipeline.

[0008] In the above solution, the distance between the end of the metal gas delivery pipeline and the end of the shielding gas delivery pipeline is 1 mm - 50 mm.

[0009] In the above solution, the distance between the nitrogen-containing gas delivery pipeline and the shielding gas delivery pipeline is 10 mm - 60 mm.

[0010] In the above solution, the end of the nitrogen-containing gas delivery pipeline extends 1 mm - 50 mm beyond the end of the shielding gas delivery pipeline.

[0011] In the above solution, the shielding gas delivery pipeline and the metal gas delivery pipeline are circular pipes.

[0012] The beneficial effect of the present utility model is that by optimizing the geometric shape and size design of this gas delivery structure, it avoids the precursor gas mixture from adhering to the outer wall of the gas delivery pipeline, resulting in structural fragmentation; at the same time, it optimizes the gas flow uniformity of the process gas, making the precursor gas more evenly distributed on the substrate surface. Description of the Drawings

[0013] Figure 1 is a schematic diagram of the present utility model;

[0014] Figure 2 is Figure 1 the side view of;

[0015] Figure 3 is a photo of the substrate thickness obtained from the comparative example;

[0016] Figure 4 is a deposition photo of the outlet of the nitrogen-containing gas delivery pipeline obtained from the comparative example;

[0017] Figure 5 is a photo of the substrate thickness obtained from the present utility model;

[0018] Figure 6 is a deposition photo of the outlet of the nitrogen-containing gas delivery pipeline obtained from the present utility model;

[0019] In the figure, 1. shielding gas delivery pipeline, 2. metal gas delivery pipeline, 3. nitrogen-containing gas delivery pipeline. Detailed Embodiments

[0020] The technical solutions in the embodiments of the present utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present utility model, rather than all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the protection scope of the present utility model.

[0021] As Figure 1-2 shown, the present utility model includes: a shielding gas delivery pipeline 1, a metal gas delivery pipeline 2, and a nitrogen-containing gas delivery pipeline 3. The metal gas delivery pipeline is located inside the shielding gas delivery pipeline, and the end of the metal gas delivery pipeline is located inside the shielding gas delivery pipeline. The nitrogen-containing gas delivery pipeline is a square pipe and is located above the shielding gas delivery pipeline, and the nitrogen-containing gas delivery pipeline is closer to the substrate than the shielding gas delivery pipeline.

[0022] Specifically, the shielding gas delivery pipeline 1 containing inert gas has a circular structure for its pipeline;

[0023] The metal gas delivery pipeline 2 containing metal precursors has a circular structure for its pipeline and is sleeved inside the shielding gas delivery pipeline 1. The length of this gas delivery pipeline is shorter than that of the shielding gas delivery pipeline, that is, the distance between the end of the metal gas delivery pipeline and the end of the shielding gas delivery pipeline is 1 mm - 50 mm, which can be 1 mm, 10 mm, 20 mm, or 50 mm;

[0024] The nitrogen-containing gas delivery pipeline 3 containing nitrogen precursors has a square structure for its pipeline, is located above the above-mentioned circular structure, and maintains a certain distance from the shielding gas delivery pipeline. The distance is 10 mm - 60 mm, which can be 10 mm, 20 mm, or 60 mm, and the length of this nitrogen-containing gas delivery pipeline is longer than that of the shielding gas delivery pipeline, that is, the end of the nitrogen-containing gas delivery pipeline extends beyond the end of the shielding gas delivery pipeline by a distance of 1 mm - 50 mm, which can be 1 mm, 10 mm, 20 mm, or 50 mm.

[0025] Through research, it is found that in the horizontal HVPE gallium nitride layered gas delivery structure, the circular nitrogen-containing gas delivery pipeline has poor delivery effect, and the obtained substrate thickness is uneven. As Figure 3 shown, the thickness of the uppermost side of the circular substrate is 41 μm, the thickness of the lowermost side is 33 μm, the thickness of the leftmost side is 122 μm, and the thickness of the rightmost side is 76 μm, and the overall thickness is extremely uneven. And before the optimization of this pipeline, parasitic deposition is likely to occur at its gas outlet. As Figure 4 shown. And after changing the circular nitrogen-containing gas delivery pipeline to a square and optimizing the corresponding distance parameters, as Figure 5As shown, nine points are sampled outward from the center of the circular substrate for measurement, and the measured thicknesses are 30μm, 28μm, 27μm, 33μm, 30μm, 23μm, 30μm, 35μm, and 29μm. It can be seen that after changing the shape, the overall thickness of the substrate tends to be uniform. As Figure 6 shown, there is almost no deposition at the air outlet after overall optimization.

Claims

1. A deposition-free HVPE gas delivery structure for improving crystal growth uniformity, comprising: A shielding gas delivery pipeline (1), a metal gas delivery pipeline (2) and a nitrogen-containing gas delivery pipeline (3), characterized in that: the metal gas delivery pipeline is located inside the shielding gas delivery pipeline, the end of the metal gas delivery pipeline is located inside the shielding gas delivery pipeline, the nitrogen-containing gas delivery pipeline is a square tube and is located above the shielding gas delivery pipeline, and the nitrogen-containing gas delivery pipeline is closer to the substrate than the shielding gas delivery pipeline.

2. A deposition-free HVPE gas delivery structure for improving crystal growth uniformity as claimed in claim 1, characterized in that: The distance between the end of the metal gas delivery pipeline and the end of the shielding gas delivery pipeline is 1mm-50mm.

3. A deposition-free HVPE gas delivery structure for improving crystal growth uniformity as claimed in claim 1, characterized in that: The distance between the nitrogen-containing gas delivery pipeline and the shielding gas delivery pipeline is 10mm-60mm.

4. A deposition-free HVPE gas delivery structure for improving crystal growth uniformity as claimed in claim 1, characterized in that: The end of the nitrogen-containing gas delivery pipeline extends beyond the end of the shielding gas delivery pipeline by 1 mm to 50 mm.

5. A deposition-free HVPE gas delivery structure for improving crystal growth uniformity as claimed in claim 1, characterized in that: The shielding gas delivery pipeline and the metal gas delivery pipeline are round tubes.

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