A device for improving uniformity of MOCVD thin film growth

Abstract

The application discloses a device for improving MOCVD thin film growth uniformity. The device is provided with a gas shielding shunt cover, and regular distribution of air holes is formed on the shunt cover; the flow conductance of each part of the gas passage is adjusted by using the change of the air hole area and its distribution, so that more uniform and stable laminar flow is formed when the gas in the MOCVD reaction cavity flows on the surface of the epitaxial substrate, and finally the improvement of the MOCVD thin film growth uniformity is assisted. In addition, the gas shielding shunt cover has a heat shielding function, can reduce the temperature gradient in the MOCVD reaction cavity, can reduce the heat loss of the MOCVD reaction cavity, and realizes energy saving and consumption reduction.

Description

TECHNICAL FIELD

[0001] The present application relates to a metal-organic chemical vapor deposition equipment for semiconductor material growth, in particular to a device for improving the uniformity of MOCVD thin film material growth. BACKGROUND

[0002] Metal-organic chemical vapor deposition (MOCVD) is a device for growing thin films on the surface of a substrate by epitaxy to form a semiconductor device structure. After the gas carrying metal-organic sources and other reaction gases enter the reaction chamber of the MOCVD system, they are guided to flow through the surface of the substrate, and the thin film material is grown on the substrate surface according to the process design. The metal-organic sources, reaction gases and reaction by-products that do not undergo chemical reaction form MOCVD exhaust gas, which is collected and flows to the exhaust port of the MOCVD reaction chamber, and is discharged from the MOCVD reaction chamber through the exhaust pipe connected to the outlet. The gas transport structure in the MOCVD reaction chamber and the epitaxy process comprehensively determine the flow state of various reaction sources in the chamber, which directly determines the thickness uniformity and growth rate of the thin film material, and ultimately determines the best quality and production yield of the product.

[0003] In the existing MOCVD exhaust gas structure, the gas at different positions in the MOCVD reaction chamber is different in distance from the inlet of the exhaust pipe during the entire process from inflow to outflow. Without a special gas shunt shield, the difference in gas flow rate at different positions in the chamber can be seen from the white growth deposition marks after the opening of the chamber. This difference will cause negative disturbance to the MOCVD reactant flow state near the upper surface of the graphite carrier disc, resulting in differences in flow rate and concentration of the reactants flowing through the epitaxial substrate placed on the upper surface of the graphite carrier disc, which will affect the epitaxial thin film deposition growth rate, and ultimately reduce the epitaxial thin film thickness uniformity. Therefore, improving the exhaust gas structure to assist in improving the MOCVD thin film material growth uniformity is a practical and continuous work for MOCVD equipment research and development. SUMMARY

[0004] In view of the deficiencies in the prior art, the purpose of the present application is to provide a device for improving the uniformity of MOCVD thin film growth, which can improve the uniformity of MOCVD thin film growth.

[0005] The purpose of the present application is achieved as follows:

[0006] The utility model provides a device for promoting MOCVD thin film growth uniformity, including MOCVD reaction cavity cavity wall, the shower head on MOCVD reaction cavity cavity wall, the graphite carrier disc under the shower head, the graphite disc support ring of supporting graphite carrier disc, the gas shunting shield around the lateral wall of graphite carrier disc and graphite disc support ring, the regular distribution of gas hole on gas shunting shield, the gas collection cavity that is linked with gas hole, the tail gas pipe under gas collection cavity, MOCVD reaction cavity cavity wall surrounds MOCVD reaction cavity, and is equipped with the spray hole on the shower head, and the distribution regularity of gas hole corresponds with the MOCVD equipment of growth corresponding thin film material.

[0007] Preferably, the distribution regularity of the gas hole is that the gas area of the gas hole increases or decreases at equal intervals, or the gas area of the gas hole is arranged periodically at equal intervals.

[0008] Preferably, in the MOCVD equipment for growing gallium nitride, the distribution regularity of the gas hole is that the gas area of the gas hole decreases at equal intervals in a clockwise direction.

[0009] Preferably, the gas shunting shield is provided with a gas hole adjusting baffle, which is used for adjusting the gas area of the gas hole to realize the flow conductance of the transport path of the reaction tail gas to the inlet of the tail gas pipe.

[0010] Further, the gas hole adjusting baffle is connected with the gas shunting shield through a latch, and the up-down sliding or rotation of the gas hole adjusting baffle realizes the adjustment of the gas area of the gas hole.

[0011] Preferably, the gas shunting shield has a heat shielding function, which can reduce the temperature gradient in the MOCVD reaction cavity, reduce the heat loss of the MOCVD reaction cavity, and realize energy saving and consumption reduction.

[0012] Beneficial effects: 1. The device for promoting MOCVD thin film growth uniformity is simple and easy to operate, and is convenient for equipment research and development and process debugging. The gas shunting shield can obtain a reaction tail gas transport path with different flow conductances, and the best gas hole setting scheme of the MOCVD equipment suitable for growing corresponding thin film materials can be obtained quickly through experiments, including the position, size and gas area change regularity of the gas hole. After the best gas hole setting scheme is determined, the result is solidified into a gas shunting shield with a non-adjustable hole size, which is used for the MOCVD equipment for growing corresponding thin film materials, thereby helping to simplify the manufacturing of MOCVD reaction tube parts, reducing process debugging parameters, and facilitating thin film material growth process debugging.

[0013] 2、The gas shielding shunt cover device for improving the uniformity of MOCVD thin film growth provided by the application also has the function of a heat shield, in addition to improving the uniformity of gas flow in the MOCVD reaction cavity through the flow guide adjustment of the gas transport passage, as a heat shield, the device can significantly reduce the heat loss of the MOCVD reaction cavity through the cavity wall, reduce the temperature gradient in the MOCVD reaction cavity, make the chemical reaction rate more uniform, and reduce the temperature difference between the front and back of the graphite wafer and the warpage, thereby promoting the improvement of the uniformity of thin film growth thickness, and achieving energy saving and consumption reduction by reducing heat dissipation. BRIEF DESCRIPTION OF DRAWINGS

[0014] In order to more clearly illustrate the technical solutions of the embodiments of the application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiment or prior art description. Obviously, the drawings in the following description are only some embodiments of the application, and other drawings can also be obtained by those skilled in the art without creative effort.

[0015] Figure 1 is a device structure schematic diagram for improving the uniformity of MOCVD thin film growth.

[0016] Figure 2 is a gas shielding shunt cover structure schematic diagram of embodiment 2 with adjustable air holes.

[0017] Figure 3 is a gas shielding shunt cover structure schematic diagram of embodiment 3 with solidified air holes.

[0018] Figure 4 is a shunt shielding cover setting schematic diagram when growing GaN material in embodiment 3, and A-E in the figure are five sampling points from the edge to the center of the graphite wafer disc.

[0019] Figure 5 is an experimental result diagram of the uniformity of thin film thickness when growing thin film by using the device of the application in embodiment 3.

[0020] In the figure, 1 is a MOCVD shower head, 2 is a graphite wafer disc, 3 is a graphite disc support ring, 4 is an air hole adjusting baffle, 5 is a gas shunt shielding cover, 6 is a gas and dust collecting cavity, 7 is an exhaust pipe, 8 is a MOCVD reaction cavity wall, and 9 is an air hole. DETAILED DESCRIPTION

[0021] The following will further illustrate a device and a control method for improving the uniformity of MOCVD thin film growth of the application in combination with the drawings and specific embodiments. Embodiment 1

[0022] As Figure 1As shown, an apparatus for improving the uniformity of MOCVD thin film growth includes an MOCVD reaction chamber wall 8, a spray head 1 on the upper wall of the MOCVD reaction chamber wall 8, a graphite substrate disk 2 below the spray head 1, a graphite disk support ring 3 supporting the graphite substrate disk 2, a gas diversion shield 5 surrounding the side walls of the graphite substrate disk 2 and the graphite disk support ring 3, vent holes 9 on the gas diversion shield 5, a gas and dust collection chamber 6 connected to the vent holes 9, and a tail gas pipe 7 below the gas and dust collection chamber 6. The MOCVD reaction chamber wall 8 forms the MOCVD reaction chamber, and the spray head 1 is provided with spray holes.

[0023] During the growth of thin film materials within the device, various required MOCVD gaseous reactants are transported to the spray head 1 and enter the MOCVD reaction chamber through the spray holes of the spray head 1. Within the MOCVD reaction chamber, they flow from top to bottom, reaching the upper surface of the graphite substrate 2 and reacting to grow the thin film material on the epitaxial substrate of the graphite substrate 2. The reaction exhaust gas flows sequentially through the slit channel formed by the sidewall of the graphite substrate 2, the sidewall of the graphite substrate support ring 3, and the gas diversion shield 5. It then flows through the vent holes 9 of the gas diversion shield 5 to the gas and dust collection chamber 6, and finally collects in the exhaust pipe 7 and exits the MOCVD reaction chamber. In this invention, a gas diversion shield 5 is added at the inlet of the gas and dust collection chamber 6, and regularly distributed vent holes 9 are formed on the gas diversion shield 5. The arrangement of the vent holes 9 is such that the vent area at the orifice increases or decreases at equal intervals, or the vent area at the orifice is periodically arranged with equal intervals of varying sizes.

[0024] By utilizing the changes in the ventilation area and distribution of the vent 9, the flow conductance at various points in the gas passage can be adjusted. During the exhaust gas extraction process, due to the different distances from the exhaust pipe 7 inlet, the gas in different regions of the MOCVD reaction chamber experiences significant differences in disturbance. Reducing this disturbance can make the flow field more uniform and stable during the process of transporting gas from the spray head 1 to the exhaust pipe 7 inlet in the MOCVD reaction chamber, making it easier to obtain uniform and stable reactant laminar flow on the surface of the epitaxial liner. Furthermore, experiments have confirmed that it has a good effect on improving the uniformity of film growth thickness. Example 2

[0025] The device structure in this embodiment is the same as that in Embodiment 1, except that the ventilation area of ​​the gas diversion shield vent is adjustable in this embodiment. Figure 2 As shown, a vent adjustment baffle 4 is provided on the gas diversion shield 5. The vent adjustment baffle 4 is connected to the gas diversion shield 5 by a pin. The ventilation area of ​​the vent can be adjusted by sliding up and down or rotating the vent adjustment baffle 4. Example 3

[0026] The device structure in this embodiment is the same as that in Embodiment 1, the difference being that this embodiment uses an MOCVD device for growing gallium nitride, and the size of the vent orifice has been fixed to an optimal setting.Figure 3 The ventilation area of ​​the vents decreases clockwise with equal spacing. For example... Figure 4 As shown, using Figure 3 The ventilation distribution pattern of the vents is as follows: initially, the vent with the largest ventilation area coincides with the exhaust port of the tailpipe, which is recorded as a 0° rotation of the diversion shield. Then, the vents clockwise adjacent to the largest vent in the initial position are set as the largest vents, with the ventilation area decreasing clockwise at equal intervals. The angle between the largest vent and the tailpipe is recorded as the rotation angle of the diversion shield. This process is repeated until the angle between the largest vent and the tailpipe is 180°, which is recorded as a 180° rotation of the diversion shield. Figure 5 As shown, by comparing the results of five sampling points on the graphite substrate disk, when the gas shunt shield is rotated clockwise by 180° sequentially, the film thickness uniformity can be transformed from "thick epitaxial film at the center of the graphite substrate disk and thin epitaxial film at the edges" to "thin epitaxial film at the center of the graphite substrate disk and thick epitaxial film at the edges"; this has been verified by experiments. Figure 5 The design of the shunt shield and the vent holes can effectively improve the growth uniformity of gallium nitride thin films.

[0027] The solutions described in the embodiments are not intended to limit the scope of patent protection of this invention. All equivalent implementations or modifications that do not depart from the scope of this invention are included in the patent scope of this case.

Claims

1. An apparatus for improving the uniformity of MOCVD thin film growth, characterized in that: It includes the MOCVD reaction chamber wall, the spray head on the MOCVD reaction chamber wall, the graphite slide disk below the spray head, the graphite disk support ring supporting the graphite slide disk, the gas diversion shield surrounding the side walls of the graphite slide disk and the graphite disk support ring, the regularly distributed vent holes on the gas diversion shield, the gas and ash collection chamber connected to the vent holes, and the tail gas pipe below the gas and ash collection chamber. The MOCVD reaction chamber is enclosed by the chamber walls, and the spray head is equipped with spray holes. A vent adjustment baffle is provided on the gas diversion shield. The vent adjustment baffle is connected to the gas diversion shield by a pin. The ventilation area of ​​the vent is adjusted by sliding up and down or rotating the vent adjustment baffle. The distribution pattern of the vents is that the ventilation area of ​​the vents increases or decreases at equal intervals, or the ventilation areas of the vents are arranged periodically with equal intervals of large and small ventilation areas.

2. The apparatus for improving the uniformity of MOCVD thin film growth as described in claim 1, characterized in that: The gas diversion shield also has a thermal shielding function, reducing the temperature gradient inside the MOCVD reaction chamber and reducing heat loss in the MOCVD reaction chamber, thus achieving energy saving and consumption reduction.

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