CN103774114B - The preparation method of oxide film - Google Patents

Abstract

A method for preparing an oxide film, comprising the following steps: step S1: mixing oxide powder and graphite powder, putting them into a reaction boat, and putting the reaction boat into a quartz reaction tube; step S2: washing and drying the liner Put the bottom on the substrate holder and put it into the quartz reaction tube; step S3: feed inert gas into the quartz reaction tube and the reaction boat respectively; step S4: heat the quartz reaction tube; step S5: adjust the reaction boat and the substrate The working temperature is adjusted, the working pressure in the quartz reaction tube is adjusted, the oxygen-containing gas is introduced into the quartz reaction tube, the growth time is set, and the oxide film is deposited on the substrate to complete the preparation. The invention expands the preparation scope of the oxide film, and can be used not only for the preparation of metal oxide films, but also for the preparation of non-metal oxide films, especially some oxide films which are currently difficult to prepare by other methods.

Description

Preparation method of oxide film

technical field

The invention relates to the technical field of semiconductors, in particular to a preparation method of an oxide film.

Background technique

Oxide materials are the first compound materials recognized and utilized by humans. Oxide materials cover superconductors, conductors, semiconductors and insulators, and are widely used in many fields such as industry, agriculture, space, and medicine. Especially in recent years, it has outstanding performance in flat panel displays, light emitting devices, solar cells, gas sensors, and photoelectric converters.

The usual preparation methods of oxide films are: MBE, MOCVD, pulsed laser deposition, magnetron sputtering, spray thermal decomposition, sol-gel, etc. Among them, magnetron sputtering is a commercial oxide film preparation method, and its mature process has been used for commercial production of ITO thin films, but this method has the disadvantages of large equipment investment and low deposition efficiency; spraying thermal decomposition technology and sol -The gel method can greatly reduce the preparation cost, but the performance of the film is not ideal. MBE and MOCVD are currently the mainstream semiconductor material preparation methods. They can precisely control the crystalline quality, doping concentration, interface flatness, and film thickness of thin films. But both have the problems of complicated and expensive equipment, high growth cost and high maintenance cost. Moreover, MOCVD uses organometallic sources, which will inevitably cause certain harm to the human body and the environment.

Chinese patent CN200710118635.1 "Oxide Chemical Vapor Deposition Preparation Device and Preparation Method" proposes a chemical vapor deposition technology. work under pressure or low pressure. Patent CN102181921A "Method for Preparing Polarity Controllable Zinc Oxide Using Metal Source Chemical Vapor Deposition Technology" uses the above chemical vapor deposition technology to prepare a polarity controllable zinc oxide film. Patent CN201010141024.0 "Method for Preparing Doped Zinc Oxide Using Metal Source Chemical Vapor Deposition Technology" uses the above-mentioned chemical vapor deposition technology to prepare a zinc oxide thin film with controllable doping. However, due to the lack of metals with suitable vapor pressure, the metal oxide films that can be prepared by this method are limited.

The present invention proposes a chemical vapor deposition method to prepare an oxide film, which is characterized in that: a mixture of oxide powder and high-purity graphite powder (C) is used as a source material, and a reduction reaction occurs under an inert gas to generate an intermediate valence state oxide The gas is carried to the substrate along with the inert gas, and reacts with the oxygen-containing gas on the surface of the substrate to form an oxide film. It can also be used to prepare doped oxide films. Due to the strong reducibility of graphite (C), the vapor partial pressure of the oxide or the intermediate valence state of the oxide increases, thereby expanding the range of oxide films that can be prepared, especially some oxide films that are currently difficult to prepare by other methods . Since the vapor pressure of graphite (C) is very small, it is only 1e-8mmHg at 1600 degrees Celsius. In an oxidizing atmosphere, a small amount of graphite vapor pressure generates gaseous carbon monoxide or carbon dioxide, which is discharged as exhaust gas. Therefore, the use of graphite, especially high-purity graphite (C) has no effect on the purity and crystal quality of the oxide film. Moreover, this method for preparing an oxide film has the following advantages: directly use oxide powder and graphite (C) powder as source materials, use inert as carrier gas, and can work at room temperature or low pressure without using an ultra-high vacuum environment. The method has the advantages of low preparation cost, simple process and environmental protection, and can well meet the requirements of energy saving and environmental protection.

Contents of the invention

The object of the present invention is to provide a method for preparing an oxide film, which directly uses oxide powder and graphite powder as source materials, uses inert as carrier gas, does not need ultra-high vacuum environment, can work at room temperature or low pressure, and has The preparation cost is low, the process is simple and environmentally friendly, and can well meet the requirements of energy saving and environmental protection.

The invention provides a method for preparing an oxide film, comprising the following steps:

Step S1: mix oxide powder and graphite powder, put them into a reaction boat, and put the reaction boat into a quartz reaction tube;

Step S2: Put the cleaned and dried substrate on the substrate holder and put it into the quartz reaction tube;

Step S3: respectively injecting inert gas into the quartz reaction tube and the reaction boat;

Step S4: heating the quartz reaction tube;

Step S5: Adjust the working temperature of the reaction boat and the substrate, adjust the working pressure in the quartz reaction tube, feed oxygen-containing gas into the quartz reaction tube, set the growth time, deposit an oxide film on the substrate, and complete the preparation.

The beneficial effect of the invention is that the preparation range of the oxide film is expanded, and it can be used not only for the preparation of metal oxide films, but also for the preparation of non-metal oxide films, especially some oxide films which are currently difficult to prepare by other methods.

Description of drawings

In order to further illustrate the specific technical content of the present invention, below in conjunction with embodiment and accompanying drawing detailed description as follows, wherein:

Fig. 1 is the preparation method flowchart of the present invention;

Figure 2 is the XRD diffraction pattern of highly preferred orientation {-201} series crystal plane gallium oxide film;

Fig. 3 is the XRD diffraction pattern of polycrystalline gallium oxide thin film;

Fig. 4 is a surface topography diagram of a molybdenum-doped zinc oxide nanocavity.

detailed description

Please refer to Fig. 1, the present invention provides a method for preparing an oxide film grown in a chemical growth reaction device, comprising the following steps:

Step S1: Mix oxide powder and graphite powder and put them into a quartz reaction boat. The mixing ratio refers to the stoichiometric ratio or the amount of graphite powder is lower than the stoichiometric ratio, but not less than a quarter of the molar amount of the stoichiometric ratio . The oxide powder is an oxide powder of a metal element or an oxide powder of a non-metal element; the elements therein have multiple oxidation valence states, at least one of which is gaseous; the oxide powder and the oxide film The oxidation states are the same or different;

Step S2: Put the cleaned and dried substrate on the substrate holder and put it into the quartz reaction tube;

Step S3: feeding inert gas into the quartz reaction tube and the reaction boat respectively; the inert gas includes nitrogen, argon, helium or neon, or a mixed inert gas thereof;

Step S4: heating the quartz reaction tube;

Step S5: Adjust the working temperature of the reaction boat and the substrate, adjust the working pressure in the quartz reaction tube, the working pressure is normal pressure or low pressure, and feed oxygen-containing gas into the quartz reaction tube. The oxygen-containing gas includes oxygen, water vapor, Dinitrogen monoxide, nitrogen monoxide or nitrogen dioxide, or their mixed gases, set the growth time, deposit an oxide film on the substrate, and complete the preparation.

The non-metallic oxides described in step S1 include: silicon oxide or arsenic oxide; the prepared oxide films include: germanium oxide, aluminum oxide, gallium oxide, indium oxide, chromium oxide, copper oxide, lead oxide, antimony oxide, Tin oxide, cerium oxide, lanthanum oxide, rhodium oxide, thorium oxide or uranium oxide.

The method for cleaning the substrate in step S2 is a conventional chemical cleaning method.

During the whole preparation process, the quartz reaction tube and the reaction boat take different gas paths. Only inert gas is passed into the reaction boat, and oxygen-containing gas does not pass through the reaction boat. In the process of heating the quartz reaction tube, an inert gas is introduced into the quartz reaction tube; during the film preparation process, an inert gas and an oxygen-added gas are introduced into the quartz reaction tube; after the film is prepared, the The quartz reaction tube was cooled to room temperature.

Example 1

This specific embodiment provides a method for preparing an oxide film, specifically a non-metal oxide film, specifically silicon oxide.

Silica is thermodynamically stable at normal temperature and pressure, and it is solid. The silicon ion in it is positive tetravalent (Si ⁴⁺ ), written as SiO ₂ (s). The intermediate valence state has positive divalence (Si ²⁺ ), which is unstable and gaseous, written as SiO(g).

The whole reaction principle is as follows:

SiO ₂ (s)+C(s)--->SiO(g)+CO(g)

SiO(g)+[O](g)--->SiO ₂ (s)

C(s)--->C(g)

C(g)+[O](g)--->CO(g)

C(g)+[O](g)--->CO ₂ (g)

Note: [O] means oxygen-containing gas, which is oxygen, water vapor, nitrous oxide (N ₂ O), nitrogen monoxide (NO), nitrogen dioxide (NO ₂ ), one or more of them mixed.

Specifically include the following steps:

S1) Mix silica powder and graphite powder (C), and put them into a reaction boat.

S2) placing the chemically cleaned and dried substrate with nitrogen on the substrate holder, and putting it into the quartz reaction tube;

S3) Pass inert gas into the quartz reaction tube and the reaction boat respectively;

S4) heating the quartz reaction tube;

S5) Adjust the working temperature of the reaction boat and the substrate, adjust the working pressure in the quartz reaction tube, the working pressure is normal pressure or low pressure, feed oxygen-containing gas into the quartz reaction tube, set the growth time, and deposit on the substrate The silicon oxide film is prepared.

Specifically, in step S1, silicon oxide powder and graphite powder (C) are mixed and put into a reaction boat; wherein the purity of silicon oxide powder and graphite powder is greater than 99.999%, and the mixing ratio is 1 mole : between 1 and 4:1. In step S3), the inert gas is argon; the oxygen-containing gas in step S5 is 5% oxygen by volume after being diluted with nitrogen. In step S5, the working temperature of the reaction boat is 400-800 degrees Celsius, the working temperature of the substrate is 400-700 degrees Celsius, and the working pressure in the quartz reaction tube is normal pressure or low pressure.

Optimally, when the molar mixing ratio of silicon oxide powder and graphite powder is 2:1, the working temperature of the reaction boat is 500 degrees Celsius, the working temperature of the substrate is 580 degrees Celsius, the working pressure is normal pressure, and the growth is 10 minutes, the obtained thickness is 500 nm silicon oxide film.

Example 2

This example is used to illustrate the preparation of the metal oxide gallium oxide thin film.

The gaseous intermediate valence oxides are gallium oxide (Ga ₂ O) and gallium monoxide (GaO). The preparation principle is as follows:

Ga ₂ O ₃ (s)+2C(s)--->Ga ₂ O(g)+2CO(g)

Ga ₂ O ₃ (s)+C(s)--->2GaO(g)+CO(g)

Ga ₂ O(g)+2[O](g)--->Ga ₂ O ₃ (s)

2GaO(g)+[O](g)--->Ga ₂ O ₃ (s)

Among them, the vapor pressure of gallium oxide is greater than that of gallium monoxide, and the selection of the mixing ratio refers to the chemical reaction formula of gallium oxide.

The difference between this embodiment and embodiment 1 is: in step S1), gallium oxide powder and graphite powder (C) are mixed, put into reaction boat 4; Wherein the purity of gallium oxide powder and graphite powder is all greater than 99.999%, The mixing ratio is 1:2-2:1. In step S3), the inert gas is helium; in step S5), the oxygen-containing gas is dinitrogen monoxide (N ₂ O) with a volume percentage of 10% after being diluted with nitrogen. In step S5), the working temperature of the reaction boat is 600-1100 degrees Celsius, the working temperature of the substrate is set at 600-1100 degrees Celsius, and the working pressure in the quartz reaction tube is normal pressure or low pressure.

Optimally, when the molar mixing ratio of gallium oxide powder and graphite powder is 1:1, the substrate is a sapphire substrate with a gallium nitride template grown on it, the working temperature of the reaction boat is 850 degrees Celsius, and the working temperature of the substrate is 850 degrees Celsius , the growth pressure is normal pressure, and the growth is 1 hour, and a 300 nm-thick gallium oxide film with a highly preferred orientation {201} series crystal plane is obtained (refer to the XRD powder diffraction pattern in Figure 2).

Further, when the substrate is a sapphire substrate grown with a gallium nitride template, the working temperature of the reaction boat is 900 degrees Celsius, the working temperature of the substrate is 1000 degrees Celsius, the growth pressure is normal pressure, and the growth is 1 hour to obtain a thickness of 350 nanometers. Polycrystalline gallium oxide thin film (see XRD powder diffraction pattern in Figure 3).

Example 3

This example is used to illustrate the preparation of the metal oxide film molybdenum oxide thin film.

The gaseous intermediate valence oxide is molybdenum dioxide (MoO ₂ ). The preparation principle is as follows:

MoO ₃ (s)+C(s)--->MoO ₂ (g)+CO(g)

MoO ₂ (g)+[O](g)--->MoO ₃ (s)

The difference between this embodiment and embodiment 1 is: in step S1), molybdenum oxide powder and graphite powder (C) are mixed, put into reaction boat 4; Wherein the purity of molybdenum oxide powder and graphite powder are all greater than 99.999%; The mixing ratio is between 1:1 and 4:1 in moles. In step S3), the inert gas is nitrogen; in step S5), the oxygen-containing gas is steam of 50°C high-purity water carried by nitrogen. In step S5), the working temperature of the reaction boat is 400-750 degrees Celsius, the working temperature of the substrate is set at 400-750 degrees Celsius, and the working pressure in the quartz reaction tube is normal pressure or low pressure.

Optimally, when the working temperature of the reaction boat is 560 degrees Celsius, the working temperature of the substrate is 600 degrees Celsius, and the growth pressure is normal pressure, grow for 10 minutes to obtain a molybdenum oxide film with a thickness of 200 nm.

Example 4

This example is used to illustrate the preparation of low-dimensional nanostructures doped with oxides, specifically molybdenum-doped zinc oxide nanostructures.

The difference between this embodiment and embodiment 3 is: in step S1), there are two boats placed in the quartz reaction tube, one is to place a mixture reaction boat of molybdenum oxide powder and graphite powder mixture, and the other is to put a metal zinc reaction boat. The two reaction boats go through the gas path independently, and only inert gas is passed through, and oxygen-containing gas is not passed through. The metal zinc put in is granular, and the purity is greater than 99.999%. In step S3), the inert gas is nitrogen; in step S5), the oxygen-containing gas is a mixture of 10% oxygen by volume after nitrogen dilution and 50°C high-purity water vapor carried by nitrogen. In step S5), the working temperature of the mixture reaction boat is 400-750 degrees Celsius, the working temperature of the metal zinc reaction boat is 500-780 degrees Celsius, the working temperature of the substrate is 500-780 degrees Celsius, and the working pressure in the quartz reaction tube can be Atmospheric or low pressure.

Optimally, when the working temperature of the mixture reaction boat is 600 degrees Celsius, the working temperature of the metal zinc reaction boat is 700 degrees Celsius, the working temperature of the substrate is 750 degrees Celsius, the growth pressure is a low pressure of 200 Torr, and the cavity-shaped molybdenum-doped For the zinc oxide nanostructure, see the surface topography diagram of accompanying drawing 4.

Further, by adjusting the temperature of the reaction boat, the flow rate ratio, and the temperature of the substrate, different forms of nano-microstructures, including quantum structures, can be obtained.

As mentioned above, the oxide film materials generated by applying the technical scheme of the present invention include silicon oxide, gallium oxide, and molybdenum oxide, but are not limited to the above-mentioned oxide materials, and also include those mentioned above or those with similar properties, which have gaseous oxidation Oxides of metal elements or non-metal elements in the valence state.

By selecting appropriate growth conditions, oxide materials with low-dimensional nanostructures can also be prepared. The doped oxide materials generated by applying the technical solution of the present invention include molybdenum-doped zinc oxide nanostructures, but are not limited to the above-mentioned nanocavity structures, and also include other low-dimensional nanostructures with similar properties, including superlattices, quantum dots, Quantum wire, quantum well structure.

Although the present invention has been disclosed as above with the embodiments, it is not intended to limit the present invention. Anyone with ordinary knowledge in the technical field can still modify the specific implementation of the present invention without departing from the spirit and scope of the present invention. Or perform equivalent replacements on some technical features without departing from the spirit of the technical solutions of the present invention, and all of them should be covered by the scope of the technical solutions claimed in the present invention.

Claims (6)

1. A preparation method of an oxide film, comprising the steps of: Step S1: mix oxide powder and graphite powder, put them into a reaction boat, put the reaction boat into a quartz reaction tube, the oxide powder is in multiple oxidation valence states, at least one of which is gaseous; Step S2: Put the cleaned and dried substrate on the substrate holder and put it into the quartz reaction tube; Step S3: respectively injecting inert gas into the quartz reaction tube and the reaction boat; Step S4: heating the quartz reaction tube; Step S5: Adjust the working temperature of the reaction boat and the substrate, adjust the working pressure in the quartz reaction tube, feed oxygen-containing gas into the quartz reaction tube, set the growth time, deposit an oxide film on the substrate, During the whole preparation process, the quartz reaction tube and the reaction boat take different gas paths, and only the inert gas passes into the reaction boat, and the oxygen-containing gas does not pass through the reaction boat. 2. The method for preparing an oxide film according to claim 1, wherein the oxide powder is an oxide powder of a metal element or an oxide powder of a non-metal element. 3. The preparation method of the oxide film as claimed in claim 2, wherein the element in the oxide powder of the metal element or the oxide powder of the non-metal element has multiple oxidation valence states, wherein at least one oxidation valence state is Gas state; the oxidation valence states of the oxide powder and the prepared oxide film are the same or different. 4. The method for preparing an oxide film according to claim 1, wherein said inert gas is nitrogen, argon, helium or neon, or a mixture of inert gases thereof. 5. The method for preparing an oxide film as claimed in claim 1, wherein said working pressure is normal pressure or low pressure. 6. The method for preparing an oxide film according to claim 1, wherein the oxygen-containing gas is oxygen, water vapor, nitrous oxide, nitrogen monoxide or nitrogen dioxide, or a mixture thereof.