A molybdenum cover for a mocvd reaction chamber

Abstract

The utility model relates to a molybdenum cover for MOCVD reaction cavity, the molybdenum cover is hollow cylinder structure, the outer surface of molybdenum cover is equipped with the multiple grooves of uniform distribution around its axis, the number of groove is at least 3, the groove is recessed to one side of the axis arrangement, the groove extends along the extension direction of the axis, the utility model discloses a circle of uniform distribution groove design is set up in the molybdenum cover circumference, improves molybdenum cover surface area, increases the surface area of MgN deposition, helps to maintain the stable Mg partial pressure in the cavity in the initial period of MOCVD complex machine, the setting of groove makes the flow velocity relatively slow when airflow passes, has increased the residence time of Mg atom, makes MgN easier deposition on the surface, the setting of groove has increased the space between molybdenum cover and shutter, is favorable to the promotion of MOCVD growth cycle.

Description

Technical Field

[0001] This utility model relates to a molybdenum cover for an MOCVD reaction chamber. Background Technology

[0002] Veeco K465 / K465i is a small-cavity MOCVD machine, which has inherent limitations in terms of capacity compared to K868 and medium-to-large-cavity MOCVD machines. For small-cavity machines, the time required for furnace dismantling and restarting severely restricts the utilization rate of epitaxial capacity. The main reason for this is that the lack of Mg in the reaction chamber after furnace dismantling prevents the rapid recovery of mass production.

[0003] Currently, after disassembling and cleaning the chamber of an MOCVD machine, the reaction chamber often lacks Mg, making it difficult to restart the machine. How to improve the success rate of restarting the machine after cleaning the chamber is an important issue that needs to be addressed in LED epitaxy. Typically, a heavy Mg-doped process is performed before the machine is restarted to maintain a Mg-rich environment in the reaction chamber. The MOCVD reaction chamber uses a molybdenum shroud, whose main function is to ensure the stability of temperature and gas flow during epitaxial wafer growth. MgN is usually deposited on its surface. In MOCVD, especially when growing p-type GaN, the Mg coating deposited on the molybdenum shroud acts as a "secondary doping source" or "memory effect source." During subsequent growth, this coating slowly releases Mg, helping to maintain a stable Mg partial pressure within the chamber, thereby achieving stable p-type doping of GaN.

[0004] Please see Figures 1 to 3 The diagram shows the usage state of the molybdenum cover, which includes the molybdenum cover 1, the gas equalization ring 3, and the cover plate 2. The gas equalization ring 3 is fitted on the outside of the molybdenum cover 1, and the cover plate 2 covers the top of the circular groove on the top of the gas equalization ring 3. The molybdenum cover 1 has a regular hollow cylindrical structure, and its outer surface area is the lowest among those with the same diameter, thus providing the lowest area for MgN deposition.

[0005] The molybdenum cover is a metallic structure. The crystal structure of MgN is different from that of metallic molybdenum. The bonding force between pure molybdenum and AlN is relatively weak, which is not conducive to the adsorption of MgN. This limits the possibility of further improving the Mg-rich environment of the reaction chamber. Utility Model Content

[0006] The purpose of this invention is to address the shortcomings of existing technologies by proposing a molybdenum cover for an MOCVD reaction chamber.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: a molybdenum cover for an MOCVD reaction chamber, wherein the molybdenum cover is a hollow cylindrical structure, and the outer surface of the molybdenum cover is provided with a plurality of grooves evenly distributed around its axis, wherein the number of grooves is at least 3. The groove is recessed towards one side of the axis; The groove extends along the direction of the axis.

[0008] Furthermore, the groove is a rectangular groove.

[0009] Furthermore, the groove has a through-hole structure.

[0010] Furthermore, the groove depth H is 0. <H<1.4mm。

[0011] Furthermore, an ALN ​​coating is also applied to the outer surface of the molybdenum cover.

[0012] Furthermore, the thickness of the ALN coating is 0.5-1.5 μm.

[0013] Compared with the prior art, the beneficial effects of this utility model are as follows: 1. A uniformly distributed groove design is set around the circumference of the molybdenum cover to increase the surface area of ​​the molybdenum cover and the surface area for MgN deposition, which helps to maintain a stable Mg partial pressure in the chamber during the initial stage of MOCVD re-run; 2. The groove design slows down the airflow velocity, increases the residence time of Mg atoms, and makes it easier for MgN to deposit on the surface; 3. The groove design increases the space between the molybdenum cover and the shutter, which is beneficial to improving the MOCVD growth cycle.

[0014] 4. An ALN ​​coating with a thickness in the range of 0.5-1.5 μm is provided on the outer surface of the molybdenum cover. ALN and MgN have similar crystal structures, both having a close-packed hexagonal structure and good crystallographic matching, which is conducive to the adsorption of MgN on the AlN surface, so as to prolong the residence time of MgN on the molybdenum cover surface. Attached Figure Description

[0015] Figure 1 This is a diagram illustrating the usage status of molybdenum covers in existing technologies. Figure 2 for Figure 1 A sectional view; Figure 3 for Figure 1 Exploded view; Figure 4 This is a schematic diagram of the molybdenum cover proposed in this utility model; Figure 5 for Figure 4 Top view; Figure 6 for Figure 5 A magnified view of a portion of the image; Figure 7 This is a schematic diagram of a further embodiment of the present invention.

[0016] Legend: 1-Molybdenum cover, 2-Cover plate, 3-Gas equalizing ring; 11-groove, 12-ALN coating; H - groove depth, D - groove width. Detailed Implementation

[0017] Please see Figures 4 to 6 This utility model provides a technical solution: A molybdenum shroud for an MOCVD reaction chamber is disclosed. The molybdenum shroud 1 is installed inside the MOCVD reaction device. The installation height of the molybdenum shroud 1 is not lower than the horizontal plane of the heater in the MOCVD reaction device. The height of the molybdenum shroud 1 in this invention is 160 mm, the outer diameter of the molybdenum shroud 1 is 464 mm, the molybdenum shroud 1 is a hollow cylindrical structure, and the outer surface of the molybdenum shroud 1 is provided with at least three grooves 11 evenly distributed around its axis. The grooves 11 are rectangular grooves recessed to one side of the axis, and can also be set into other groove shapes, such as triangular or trapezoidal. In this embodiment, a rectangular groove is used as an example. In this embodiment, the groove 11 extends along the axial direction and penetrates the upper and lower surfaces of the molybdenum cover 1. The through-structure facilitates roll forming.

[0018] This design increases the surface area of ​​the molybdenum cover 1 by creating a ring of evenly distributed grooves 11 around its circumference. The increase depends on the number of grooves 11 and the depth H of each groove. The groove depth is limited by the usage conditions and is generally taken to be within the range of 0. <H<1.4mm; The width D of the groove is selected based on the outer diameter of the molybdenum cover 1, and should not exceed 1 / 3 of the circumference of the molybdenum cover 1. In this embodiment, the outer diameter is 464mm, and the calculated range is 0. <D<485mm; The groove 11 increases the surface area for MgN deposition, which helps maintain a stable Mg partial pressure in the chamber during the initial stage of MOCVD re-run. The groove 11 makes the airflow velocity relatively slower when it passes through, which increases the residence time of Mg atoms and makes it easier for MgN to be deposited on the surface. The groove 11 increases the space between the molybdenum shield and the shutter, which is beneficial for improving the MOCVD growth cycle. In order to increase the residence time of MgN on the outer surface of the molybdenum cover 1 and obtain a more sufficient reaction time, an ALN ​​coating 12 with a thickness of 0.5-1.5 μm is also coated on the outer surface of the molybdenum cover (1). The principle of setting the ALN coating 12 is that the ALN material and MgN have similar crystal structures, both having a close-packed hexagonal structure and good crystallographic matching, which is conducive to the adsorption of MgN on the AlN surface and achieves the purpose of prolonging the residence time of MgN on the outer surface of the molybdenum cover 1.

[0019] The foregoing has shown and described the basic principles, main features, and advantages of this utility model. Those skilled in the art should understand that this utility model is not limited to the above embodiments. The embodiments and descriptions in the specification are merely preferred examples and are not intended to limit the utility model. Variations and modifications made without departing from the spirit and scope of this utility model fall within the scope of the claims. The scope of protection of this utility model is defined by the appended claims and their equivalents.

Claims

1. A molybdenum shroud for an MOCVD reaction chamber, characterized in that: The molybdenum cover (1) is a hollow cylindrical structure. The outer surface of the molybdenum cover (1) is provided with a plurality of grooves (11) evenly distributed around its axis. The number of grooves (11) is at least 3. The groove (11) is recessed towards one side of the axis; The groove (11) extends along the direction of the axis.

2. The molybdenum shroud for an MOCVD reaction chamber according to claim 1, characterized in that: The groove (11) is a rectangular groove.

3. The molybdenum shroud for an MOCVD reaction chamber according to claim 1, characterized in that: The groove (11) is a through structure.

4. A molybdenum shroud for an MOCVD reaction chamber according to claim 1, characterized in that: The groove depth H of the groove (11) is 0. <H<1.4mm。 5. A molybdenum shroud for an MOCVD reaction chamber according to claim 1, characterized in that: The outer surface of the molybdenum cover (1) is also coated with an ALN ​​coating (12).

6. A molybdenum shroud for an MOCVD reaction chamber according to claim 5, characterized in that: The thickness of the ALN coating (12) is 0.5-1.5 μm.

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