CN205821448U - A cleaning system for MOCVD reaction chamber - Google Patents

Abstract

The utility model discloses a cleaning system for an MOCVD reaction chamber, comprising a gas pipeline with a temperature control function, a filtering device with a temperature control function, and a cold trap with a temperature control function; wherein the outlet of the MOCVD reaction chamber is connected to the inlet of the gas pipeline, the outlet of the gas pipeline is connected to the filtering device, the cold trap is arranged downstream of the filtering device, and a throttle valve and a vacuum pump are also connected downstream of the cold trap, the pressure in the reaction chamber is adjustable through the throttle valve, and at the same time, in order to be able to adjust a specific pressure range below atmospheric pressure, the vacuum pump is located behind the throttle valve; during cleaning, a gas containing chloride or halide is mainly introduced into the interior of the MOCVD reaction chamber to remove the deposits in situ. The use of the cleaning system does not require the MOCVD reaction chamber to be opened, and has good repeatability and high cleaning efficiency.

Description

A cleaning system for MOCVD reaction chamber

technical field

The utility model relates to the technical field of MOCVD reaction chamber cleaning, in particular to a cleaning system for MOCVD reaction chambers.

Background technique

MOCVD is a new type of vapor phase epitaxial growth technology developed on the basis of vapor phase epitaxial growth (VPE). MOCVD uses organic compounds of group III and group II elements and hydrides of group V and group VI elements as crystal growth source materials, and performs vapor phase epitaxy on the substrate in a thermal decomposition reaction mode to grow various group III-V, group II - Thin-layer single-crystal materials of group VI compound semiconductors and their multi-component solid solutions. The reaction in the reaction chamber is very complicated, and redundant gaseous and non-gaseous by-products will be formed after each reaction step, and non-gaseous deposits will be deposited inside the reaction chamber (such as the inner wall, etc.), resulting in equipment process parameter errors, reaction Chamber performance is reduced, and impurities such as particles are easily formed on the surface of the substrate during the preparation of semiconductor compounds, and these impurities will affect semiconductor performance. Therefore, the reaction chamber needs to be cleaned during use.

Contents of the invention

The purpose of the utility model is to overcome the deficiencies and shortcomings of the prior art, and provide a simple and reliable cleaning system for the MOCVD reaction chamber. The cleaning system does not need to open the MOCVD reaction chamber, and has good repeatability and high cleaning efficiency.

In order to achieve the above purpose, the technical solution provided by the utility model is: a cleaning system for MOCVD reaction chamber, including a gas pipeline with temperature control function, a filter device with temperature control function, a cooling system with temperature control function Trap; wherein, the outlet of the MOCVD reaction chamber is connected to the inlet of the gas pipeline, the outlet of the gas pipeline is connected to the filter device, the cold trap is arranged downstream of the filter device, and is also connected downstream of the cold trap There is a throttle valve and a vacuum pump through which the pressure in the reaction chamber is made adjustable, while in order to be able to adjust a certain pressure range below atmospheric pressure, the vacuum pump is located behind the throttle valve; when cleaning, mainly will contain Chloride or halide gas is passed into the interior of the MOCVD chamber to remove deposits in situ.

The filter medium of the filter device is a porous material, so that the non-gaseous and solid reaction products are blocked and only the gaseous reactants pass through.

Compared with the prior art, the utility model has the following advantages and beneficial effects:

Chlorides or halides are used in the cleaning process, which combine with by-products of the reaction chamber to form gallium chloride or similar. As purge gas eg _Cl2 or HCl can be used. In order to achieve the purpose of cleaning, a dry etching method is used to introduce an etching gas (such as Cl ₂ ) into the reaction chamber with hydrogen, nitrogen or an inert gas as a carrier gas. The deposition on the reaction chamber wall and Cl ₂ form volatile gallium compounds at high temperature, such as GaCl ₃ , Ga ₂ CL ₆ , GaCl, GaCl ₂ , Ga ₂ Cl. In a word, the structure of the cleaning system is simple and reliable, and the MOCVD reaction chamber does not need to be opened when using the cleaning system, which has good repeatability and high cleaning efficiency.

Description of drawings

Figure 1 is a schematic diagram of the cleaning system used in the MOCVD reaction chamber.

Figure 2 is a graph showing the vapor pressure of the reaction product GaCl ₃ .

detailed description

Below in conjunction with specific embodiment the utility model is further described.

The cleaning system for the MOCVD reaction chamber described in this embodiment includes a gas pipeline with a temperature control function, a filter device with a temperature control function, and a cold trap with a temperature control function; wherein, the outlet of the MOCVD reaction chamber It is connected to the inlet of the gas pipeline, the outlet of the gas pipeline is connected to the filter device, the cold trap is arranged downstream of the filter device, and a throttling valve and a vacuum pump are also connected downstream of the cold trap. The gas lines are temperature controlled to prevent condensation of the gaseous emissions from the reaction chamber. The filter medium of the filter device is a porous material, so that non-gaseous and solid reaction products are blocked when passing through, and only gaseous reactants pass through. The filter device has a temperature regulating function. It is especially important from the perspective of efficiency that the filter device is arranged before the cold trap device. After the gaseous discharge leaves the reactor, the temperature of the filter device is adjusted so that the temperature in the filter device is higher than the condensation temperature of the gaseous discharge to avoid condensation. The gaseous reaction products condense on a downstream cold trap. During the deposition process solid reaction products are produced and the etching gas reacts to convert them into gaseous chemical compounds. For example, gallium compounds are converted to volatile gallium chloride compounds by chlorine gas, and the volatile reaction products are condensed in a cold trap. Downstream of the cold trap, a throttle valve is provided to make the pressure adjustable in the reaction chamber. In order to be able to adjust a specific pressure range below atmospheric pressure, the vacuum pump is located behind the throttle valve. Moreover, the reaction chamber, the filter device, the connecting pipe between the reactor and the filter device itself all have the function of temperature regulation, so that the internal gaseous components can be kept at a stable temperature above the condensation temperature.

As shown in FIG. 1 , the carrier gas and processing gas enter the reactor 1 through the gas supply pipeline 3 . Inside the reactor 1 there is a gas inlet element 14 with a plurality of gas outlet holes into the process chamber 2 . The gas inlet element 14 is connected in series with the gas supply line 3 . The bottom of the processing chamber 2 is formed by a susceptor support 17 on which a wafer substrate is placed. On the base 17 there is a temperature control device 4 . It is mainly used for heating, for example, radio frequency heating, radiation heating or resistance heating so that the susceptor 17 and the processing chamber 2 can be heated to a high temperature. When the deposition process takes place in the reaction chamber, it is accompanied by the formation of gaseous and non-gaseous reaction products.

15 in FIG. 1 is a gas outlet, and the remaining gas and reaction products are discharged through the gas outlet 15 and connected to the gas pipeline 5 .

The gas line 5 passes through a chamber collar 9 filled with a heat transfer liquid. The chamber collar 9 has an inlet 5" and an outlet 5', which has a temperature control function, and can use water as a heat medium to make it have a temperature of 90°C.

The filter device 7 is arranged upstream of the cold trap 6, and a filter cartridge 16 is arranged inside, and the filter medium is made of porous material. The exhaust gas passes through the filter cartridge 16 through the gas pipeline 5 to intercept the solid particles in the exhaust gas. The housing of the filter unit 7 is temperature controlled by a jacket 8 . The heat medium of the jacket 8 can be water, the inlet is 8', and the outlet is 8". In addition, the temperature control can also be formed by resistance heating, for example, heating the jacket. Commonly used methods generally consist of electric heating with temperature control.

Cold trap 6 has a shell, and it also has temperature control function. Again, its temperature control device forms a chamber in the form of a sleeve 13, and the temperature control medium enters and exits the chamber through the inlet 13' and the outlet 13 ". The temperature control medium is a coolant, such as glycol water, so that the cold trap 6 can maintain a temperature of minus 5°C. The gaseous reaction product can be condensed in the cold trap 6. A cooling coil 18 can also be arranged inside the cold trap 6. The cooling coil forms a spiral channel, and the coolant circulates inside the coil.

There is a throttling valve 11 downstream of the cold trap 6, and the opening of the valve core 12 can be adjusted to make the pressure of the processing chamber 2 controllable. A vacuum pump 10 is connected downstream of the throttle valve 11 .

The specific cleaning process is as follows: in the processing chamber 2 , the group III-V semiconductor is deposited on the semiconductor substrate on the base 17 . The carrier gas and processing gas enter the processing chamber 2 through the gas supply line 3 and the gas inlet element 14, so that the III-V semiconductor layer is formed on the surface of the substrate. For example, trimethylgallium and NH 3 and hydrogen are fed into the process chamber 2 through the gas inlet element 14 to cause the reaction. The deposition process forms a gallium-containing chemical coating on the chamber 2 and susceptor 17 . Cleaning of these coatings can be done by introducing an etching gas through the gas supply line 3 . _In this process, the gas is preferably Cl2. The introduction of Cl ₂ causes the internal coating of the processing chamber 2 at high temperature to form a gaseous gallium chloride compound.

The carrier gas carries the gaseous reactants in the cleaning process through the gas pipeline 5 and passes through the filter device 7 . In order not to generate condensed GaCl ₃ during this transport, it is ensured that the gas line 5 and the filter device 7 are kept at the temperature TA. Figure 2 shows the vapor pressure curve of GaCl ₃ , TK is an abbreviation for critical temperature. The working temperature of the gaseous reaction product passing through the filter 7 is TA, which is higher than the critical temperature TK.

A chemical reaction in the filter device 7, wherein the etching gas reacts with the solid residue in the filter cartridge 16. The gallium-containing filter residue can be converted, for example, into gallium chloride compounds in gaseous form, and transported to the cold trap 6 together with the carrier gas. Filter cartridge 16 is a porous media, such as filter paper or the like. The filter cartridge 16 has the task of filtering particles during the sedimentation process or cleaning process. During the cleaning process, such solid residues can be preferentially filtered by the filter device 7 , but this also reduces the service life of the filter cartridge 16 .

The temperature control devices 8 and 9 are all in the form of cavities, and the heat medium filled inside can be water, oil, silicone oil or similar substances. Preferably the same heat medium is used for the temperature control of the gas line 5 and the filter device 7, so that the temperature of these two chambers can be controlled together. In addition, it is avoided that the filter device 7 is not adjusted to the required temperature and starts to filter.

The cold trap 6 is kept at a temperature TB (condensing temperature), which is lower than the critical temperature TK, for example minus 5°C. The purpose of the cold trap 6 is to condense compounds in the exhaust gas so that downstream equipment, especially the vacuum pump 10 and the throttle valve 11 , do not form condensed products.

Vacuum pump 10 and throttle valve 11, can also provide an additional heater, no condensation of reaction products occurs when the interior of the equipment contacts the exhaust gas.

The implementation examples described above are only preferred embodiments of the present utility model, and are not intended to limit the scope of implementation of the present utility model, so all changes made according to the shape and principle of the present utility model should be covered by the scope of the present utility model. within the scope of protection.

Claims (2)

1. the cleaning systems for MOCVD reative cell, it is characterised in that: include the gas tube with temp. control function Road, there is the defecator of temp. control function, there is the cold-trap of temp. control function；Wherein, the going out of described MOCVD reative cell Mouth is connected to the entrance of gas piping, and the outlet of described gas piping is connected to defecator, and described cold-trap is arranged on filtration dress The downstream put, and it is also associated with a choke valve and vacuum pump in this cold-trap downstream, make pressure in reaction by described choke valve Room scalable, simultaneously in order to the particular pressure range adjusted under subatmospheric, described vacuum pump is positioned at after choke valve； During cleaning, mainly the gas containing chloride or halogenide is passed through inside MOCVD reative cell to carry out deposit going in situ Remove.

A kind of cleaning systems for MOCVD reative cell the most according to claim 1, it is characterised in that: described filtration fills The filter medium put is porous material, and on-gaseous and solid reaction product can be made through out-of-date being blocked only to pass through vapor reaction Thing.