Method and apparatus for treating the surface of a graphite disc for mocvd equipment

Abstract

The application discloses a kind of MOCVD equipment with graphite tray surface processing method and device, the method includes: under vacuum condition, using laser to carry out pyrolytic carbon processing to the surface of graphite tray, laser frequency is 0.5-5K hertz, pulse width 1-500fs, single pulse energy 0.1-5mJ.The pyrolytic carbon with similar chemical vapor deposition method under 2000 ℃ condition can be formed by using femtosecond laser pulse to process the surface of graphite tray, and periodic microstructure is simultaneously provided, the adhesion of deposit and graphite tray surface can be greatly improved, the deposit is not easy to fall off when accumulation is relatively thick, to improve the cleanliness of reaction chamber while reducing the maintenance cycle of reaction chamber, to realize cost reduction and efficiency improvement.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of compound semiconductor materials, and in particular to a method and device for processing the surface of a graphite disc used in a MOCVD device. BACKGROUND

[0002] In the field of compound semiconductor materials, a MOCVD (metal organic chemical vapor deposition) device is a very important material growth device, which uses the principle of thermal decomposition of metal organic compounds at high temperatures to deposit thin films. The thin films grown by this principle are single crystal materials, so there are very high requirements for the reaction source materials and the reaction chamber components. In practical applications, the main components of the reaction chamber are graphite discs, supplemented by quartz pieces and other metal components. The performance of the graphite disc directly determines the growth quality of the thin films in the MOCVD reaction chamber, so the material is required to be high-purity graphite.

[0003] There are two main methods for processing the surface of a graphite disc used in a MOCVD reaction chamber on the market at present. One is to directly grow a silicon carbide coating on the surface of the graphite to improve the surface quality of the graphite disc. The other is to use chemical vapor deposition to deposit pyrolytic carbon with a certain crystal orientation at 2000°C to improve the surface quality of the graphite disc. Both methods of using pyrolytic carbon and silicon carbide coating can obtain a higher surface quality, improve the process conditions of the MOCVD reaction chamber, and improve the growth quality of the thin films. In actual use, since the surface of the graphite disc is polycrystalline or amorphous pyrolytic carbon or silicon carbide, even if it is single crystal, the crystal orientation and lattice constant of the parameters are greatly different from the single crystal thin films grown by MOCVD epitaxy. This leads to the fact that the deposited material on the surface of the graphite disc cannot adhere well to the graphite disc, and the deposited material falls off, thereby causing additional particle contamination in the MOCVD reaction chamber environment and affecting the quality of the thin films.

[0004] To solve this problem, the entire graphite disc needs to be replaced after growing several batches, and the graphite disc needs to be baked at high temperature to remove the deposited material, so as to reduce the particle contamination caused by the falling off of the deposited material.

[0005] The information disclosed in this BACKGROUND section is only for the purpose of increasing the understanding of the background of the present application and should not be taken as an acknowledgment or any form of suggestion that this information forms prior art that is publicly known. SUMMARY

[0006] The purpose of the present application is to provide a method and device for processing the surface of a graphite disc used in a MOCVD device, which can overcome the technical problem that the deposited material on the surface of the graphite disc cannot adhere well to the graphite disc and falls off.

[0007] To achieve the above object, embodiments of the present application provide a method for processing the surface of a graphite disc for MOCVD equipment, which comprises the following steps:

[0008] The laser frequency is 0.5-5 KHz, the pulse width is 1-500 fs, and the single pulse energy is 0.1-5 mJ.

[0009] In one or more embodiments of the present application, the movement of the laser spot on the surface of the graphite disc is controlled to form a periodic micro-nano structure on the surface of the graphite disc.

[0010] In one or more embodiments of the present application, the light beam of the laser is shielded by a diaphragm or a baffle before the laser spot moves from one processing position to another processing position.

[0011] In one or more embodiments of the present application, inert gas is sprayed onto the surface of the graphite disc during the process of treating the surface of the graphite disc with the laser.

[0012] In one or more embodiments of the present application, the spraying pressure of the inert gas is controlled at 0.01-2 kg, and the flow rate is 0.1-5 L / min.

[0013] In one or more embodiments of the present application, before the surface of the graphite disc is treated with the laser, the surface of the graphite disc is pretreated with oxygen plasma.

[0014] To achieve the above object, embodiments of the present application also provide a processing device for the surface of a graphite disc, which comprises:

[0015] A laser processing chamber is provided with a transparent window.

[0016] A displacement platform for supporting a graphite disc sample is arranged in the laser processing chamber and can move the graphite disc sample.

[0017] A laser is arranged outside the laser processing chamber, and its light beam can pass through the transparent window to irradiate the displacement platform. The laser frequency of the laser is 0.5-5 KHz, the pulse width is 1-500 fs, and the single pulse energy is 0.1-5 mJ.

[0018] In one or more embodiments of the present application, an inert gas nozzle is also included, the outlet of the inert gas nozzle faces the support surface of the displacement platform, and the landing point of the gas guided by the inert gas nozzle on the surface of the displacement platform is the same as the landing point of the light beam of the laser on the surface of the displacement platform.

[0019] In one or more embodiments of the present application, the aperture of the inert gas nozzle is 0.1-10 mm.

[0020] In one or more embodiments of the present invention, the linear distance between the inert gas nozzle outlet and the surface of the displacement platform is 1 mm-10 mm.

[0021] Compared with the existing technology, the present invention uses femtosecond laser pulses to process the surface of the graphite disk to form pyrolytic carbon similar to that of chemical vapor deposition under 2000°C, while also having a periodic microstructure. This can greatly improve the adhesion of the deposits to the surface of the graphite disk, making it difficult for the deposits to fall off even when they accumulate thickly, thereby improving the cleanliness of the reaction chamber while reducing the maintenance cycle of the reaction chamber, achieving cost reduction and efficiency improvement. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 3 is a schematic structural diagram of a graphite disk surface processing device according to one embodiment of the present invention. DETAILED DESCRIPTION

[0023] The specific embodiments of the present invention are described in detail below with reference to the accompanying drawings, but it should be understood that the protection scope of the present invention is not limited by the specific embodiments.

[0024] Unless expressly stated otherwise, throughout the specification and claims, the term "comprise" or variations such as "include" or "comprising", etc., will be understood to include the stated elements or components but not to exclude other elements or other components.

[0025] like Figure 1 As shown, a graphite disk surface processing device 10 according to a preferred embodiment of the present invention includes a laser processing chamber 11, a displacement platform 12 and a laser 13. The displacement platform 12 is arranged in the laser processing chamber 11 to carry the graphite disk sample 20. The laser 13 is arranged outside the laser processing chamber 11 to irradiate the graphite disk sample 20 located in the laser processing chamber 11.

[0026] The laser processing chamber 11 has an openable sealing cover 111 . The sealing cover 111 is provided with a transparent window 112 for the laser beam to pass through. The transparent window 112 is preferably made of optical glass.

[0027] In this technical solution, after the sealing cover 111 is opened, the graphite disk sample 20 can be placed in the laser processing chamber 11 .

[0028] The displacement platform 12 is a multi-axis motion platform, which can drive the graphite disc sample 20 on its surface to move in two dimensions in a horizontal plane and in a vertical direction. Preferably, the displacement platform 12 is connected to a stepper motor, which drives the graphite disc sample 20 to move to the next position after the laser beam processing at a position is completed, and then the laser beam processing is performed again.

[0029] An optical lens group 14 is further arranged between the laser 13 and the transparent window 112. The laser frequency of the laser 13 is 0.5-5 KHz, the pulse width is 1-500 fs, and the single pulse energy is 0.1-5 mJ.

[0030] An inert gas nozzle 15 is further arranged on the laser processing chamber 11, the outlet of the inert gas nozzle 15 faces the support surface of the displacement platform 12, and the landing point of the gas guided by the inert gas nozzle 15 on the surface of the displacement platform is the same as the landing point of the laser beam 131 on the surface of the displacement platform 12. That is, the gas from the inert gas nozzle 15 can directly act on the position where the laser beam 131 works, so as to ensure that the dust generated during the interaction between the laser and the graphite does not form pollution near the action point.

[0031] In an embodiment, the aperture of the inert gas nozzle 15 is 0.1-10 mm, and the linear distance between the outlet of the inert gas nozzle 15 and the surface of the displacement platform 12 is 1-10 mm. The linear distance here refers to the distance between the outlet of the inert gas nozzle 15 and the laser focusing spot.

[0032] The inert gas nozzle 15 is preferably fixed on the sealing cover 111.

[0033] The laser processing chamber 11 is connected through an inert gas inlet pipe 16, and a check valve 161 is arranged on the inert gas inlet pipe 16. The inert gas introduced can be nitrogen, helium, or other inert gases.

[0034] A vacuum pump 17 is further arranged on the laser processing chamber 11, and the laser processing chamber 11 needs to be vacuumized before the laser processing of the graphite disc sample 20.

[0035] A pressure gauge 13 for displaying the pressure inside the laser processing chamber 11 can be further arranged on the sealing cover 111.

[0036] The embodiment also provides a processing method of the processing device 10 for the surface of the graphite disc, which comprises the following steps.

[0037] In step s1, the graphite disc 20 is subjected to nitrogen blowing and oxygen plasma treatment to remove surface impurities and debris before laser processing.

[0038] Step s2, the graphite disc 20 is placed in the laser processing chamber 11, the sealing cover 111 is closed, and the inert gas such as nitrogen or helium is used to purge and replace 5-10 times to remove the water and oxygen in the reaction chamber. The inert gas is introduced to open the vacuum pump 17, and the computer is used to maintain the cavity pressure through the pressure gauge and the valve opening degree in front of the vacuum pump 17.

[0039] Step s3, the repetition frequency of the laser 13 is controlled at 0.5-5KHz, the pulse width is 1-500fs, and the single pulse energy is 0.1-5mJ according to actual needs.

[0040] In the processing process, not limited to single beam laser, but also multiple beam lasers can be used for processing at the same time.

[0041] Step s4, during the surface treatment process of the laser, the inert gas nozzle continuously sprays gas during the processing process, and the pressure is controlled at 0.01-2kg, and the flow rate is 0.1-5L / min, so that the floating dust generated during the interaction of the laser and the graphite cannot form pollution near the action point.

[0042] Step s5, according to the actual processing process parameters, after one action point is processed, the computer interrupts the laser beam through the diaphragm or baffle in the optical system, and the stepping motor moves to move the graphite 20 to the next position to be processed to the light spot, and the diaphragm or baffle in the optical system is controlled to focus the laser to continue processing, so as to form a circular pit with a diameter of 0.2-3μm, a depth of 0.5-2μm, and a period of 0.4-5μm on the surface of the graphite disc

[0043] Step s6, the processing is finished, the reaction chamber is purged with nitrogen for 10min, and the vacuum pump is closed to open the chamber.

[0044] In summary, the laser processing method is used for pyrolytic carbon treatment on the surface of the graphite disc, and a periodic micro-nano structure is formed. Good surface quality can be achieved, and the periodic micro-nano structure can increase the adhesion of the deposit and the graphite disc.

[0045] The foregoing description of specific exemplary embodiments of the application is intended to be illustrative only and is not intended to limit the application to the precise forms described. Many modifications and variations are possible in light of the above teachings without departing from the spirit or essential characteristics of the application. The exemplary embodiments were chosen and described in order to explain the principles of the application and its practical application and to allow others skilled in the art to understand the various exemplary embodiments and various permutations and combinations of the application. The scope of the application is intended to be defined by the claims and their equivalents.

Claims

1. A method for treating the surface of a graphite susceptor for use in an MOCVD apparatus, characterized by: The surface of the graphite disc is treated by pyrolytic carbon under vacuum condition by using laser, The laser frequency is 0.5-5KHz, the pulse width is 1-500fs, and the single pulse energy is 0.1-5mJ. During the process of treating the surface of the graphite disc by pyrolytic carbon by using laser, inert gas is sprayed to the surface of the graphite disc. Before treating the surface of the graphite disc by pyrolytic carbon by using laser, the surface of the graphite disc is pretreated by oxygen plasma.

2. The method of treating the surface of a graphite susceptor for MOCVD apparatus according to claim 1, wherein The movement of the laser spot on the surface of the graphite disc is controlled to form periodic micro-nano structure on the surface of the graphite disc.

3. The method of claim 2, wherein the graphite disc surface is treated by heating the graphite disc surface to a temperature of 1,000°C to 1,500°C in an atmosphere of argon gas, nitrogen gas, or hydrogen gas. Before the laser spot moves from one treatment position to another treatment position, the light beam of the laser is shielded by the diaphragm or the baffle. ​ 4. The method of claim 1, wherein the graphite disc surface is a surface of a graphite susceptor for MOCVD equipment. The spraying pressure of the inert gas is controlled at 0.01-2kg, and the flow rate is 0.1-5L / min.

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