CN105296961B - The method that presoma space cellular-type prepares gallic acid bismuth thin film - Google Patents

Abstract

A method for preparing a bismuth gallate thin film by space-separating precursors. A method for preparing BiGaO ₃ thin film materials by space-separated self-limiting surface adsorption reaction of precursors. The BiGaO ₃ thin film materials are grown on the substrate material. The space group of the BiGaO ₃ thin film materials is Pcca, and the lattice constant is a=5.626 Å, b=5.081Å, c=10.339Å, the preferred orientation of the BiGaO ₃ thin film material grown on the selected substrate is (112), which is obtained by the space-separated self-limiting surface adsorption reaction of the precursor, the The surface adsorption reaction specifically refers to the irreversible chemical adsorption reaction of the Langmuir adsorption mechanism. By adopting the method for preparing the _BiGaO3 thin film material of the present invention, the precise and controllable growth thickness of the _BiGaO3 thin film can be realized, and the surface flatness of the _BiGaO3 thin film is much better than that of the prior art. Since the feeding of various gases is continuous and the flow rate is constant, the thickness of the film only depends on the number of times the substrate turns, and the process becomes extremely simple and reliable.

Description

Method for preparing bismuth gallate thin film by space separation of precursor

technical field

The invention relates to a bismuth-based oxide thin film material, in particular to a _BiGaO3 ferroelectric thin film material and a preparation method thereof.

Background technique

Recently, it has been discovered that bismuth-based ferroelectric materials such as bismuth ferrite (BiFeO ₃ ), bismuth titanate (Bi ₄ Ti ₃ O ₁₂ ), bismuth aluminate (BiAlO ₃ ) and other perovskite or pseudo-perovskite structure ferroelectric oxidation It has attracted much attention due to its characteristics of low leakage, strong fatigue resistance, high dielectric constant and environmental friendliness. In recent years, people have gained a general knowledge and understanding of the design, preparation, physical and chemical properties and application in production and life of bismuth ferrite (BiFeO ₃ ) and bismuth titanate (Bi ₄ Ti ₃ O ₁₂ ), in 2005 Baettig et al. theoretically predicted that bismuth gallate (BiGaO ₃ ) also has excellent ferroelectric properties. However, the preparation technology of bismuth gallate (BiGaO ₃ ) materials is still extremely lacking. Only reports use high temperature and high pressure solid phase The bulk material of bismuth gallate (BiGaO ₃ ) is prepared by the reaction method (the pressure is on the order of GPa and the temperature is more than 1,000 degrees Celsius). However, such high temperature and high pressure production conditions are obviously not suitable for use in the microelectronics industry for device integration. In the production of circuits, its bulk materials cannot be applied to the increasingly miniaturized and highly integrated microelectronics field, and the preparation process of bismuth gallate thin films suitable for the microelectronics field has not yet been reported.

In document CN103880078A, we have disclosed a method for preparing GaBiO ₃ thin film material by chemical solution spin coating method. However, the chemical solution spin-coating method is really powerless in the preparation of large-area high-thickness uniformity and precise controllability at the nanometer level, and it is difficult to integrate and be compatible with semiconductor manufacturing processes.

Contents of the invention

In order to solve the problems in the prior art, the object of the present invention is to provide a method for preparing BiGaO ₃ thin film material through space-separated self-limited surface adsorption reaction that can precisely control the thickness of the film. The concrete technical scheme that realizes the object of the invention is:

A preparation method of _BiGaO3 thin film material, including but not limited to the following specific steps:

A) dry the cleaned substrate material with an inert gas, and place it in a substrate tray;

B) The tray and the substrate are moved into the vacuum reaction chamber, and the vacuum pump is turned on to evacuate the vacuum reaction chamber;

C) heating the vacuum chamber so that the temperature of the tray and the substrate in the vacuum chamber is maintained at a suitable temperature window during the entire film growth process;

The selected appropriate temperature window refers to: in an appropriate temperature range, that is, when the temperature of the substrate is higher than a lower temperature limit but lower than an upper temperature limit, and the flow rate of the precursor gas supply is greater than the lower limit, the thin film The growth rate of the film is a substantially constant value, and the growth rate of the film is basically independent of the flow rate of the precursor gas supply, the flow rate of the carrier gas, that is, the inert gas, the temperature of the precursor, the temperature of the substrate, and the vacuum degree of the separated space of the vacuum chamber. , the "substantially irrelevant" mentioned here means: even if the growth rate of the film fluctuates in this temperature window, it fluctuates slightly. The rate will increase or decrease significantly;

In the temperature window, the deposition rate does not change with temperature; when the temperature is not high enough, the condensation of the precursor causes multi-layer adsorption, resulting in an excessively high deposition rate, or incomplete adsorption and poor reactivity; when the temperature is too high, the decomposition of the precursor leads to additional CVD growth, or desorption of the precursor due to excessive thermal kinetic energy;

The vacuum reaction chamber includes a plurality of separate spaces, which are respectively used to feed bismuth precursor gas, gallium precursor gas, oxygen precursor gas, and inert gas;

D) When the temperature of the vacuum chamber is constant for a period of time, the number of rotations of the tray and the substrate is set, and inert gas, tris(2,2,6,6-tetramethyl-3 , 5-heptanedionate) bismuth(III) or other bismuth precursor gas, oxygen precursor gas and trimethylgallium gas or other gallium precursor gas; all precursor gases are transported by inert gas respectively;

E) The substrate tray drives the substrate material to move together, in the separation of tris(2,2,6,6-tetramethyl-3,5-heptanedionate) bismuth (III) or other bismuth precursor gas Pass between four kinds of compartments, including space, compartment for inert gas, compartment for trimethylgallium gas or other gallium precursor gas, and compartment for oxygen precursor gas;

F) When the rotation of the tray and the substrate reaches the set number of turns, stop the rotation, the thickness of the film reaches the required value, and obtain a certain thickness of _BiGaO3 thin film material, stop feeding the bismuth precursor, gallium precursor, and oxygen precursor, Continue to feed inert gas, stop the tray and substrate, and stop the heating of the vacuum chamber for natural cooling;

G) when the vacuum chamber reaches or is close to room temperature, turn off the vacuum pump, inflate the vacuum reaction chamber so that its air pressure reaches an atmospheric pressure, and take out the substrate that has deposited the _BiGaO3 thin film material;

H) Put the substrate with BiGaO ₃ thin film material adhered obtained in step G into a rapid annealing furnace, perform rapid thermal annealing treatment, take it out after natural cooling.

Confirm through X-ray diffraction (XRD) test and structural refinement, through step H) the space group of the _BiGaO3 film material that obtains is Pcca, and lattice constant is The preferred orientation obtained by growing the BiGaO ₃ thin film material on the selected substrate is (112).

Since the method of the present invention can achieve precise and controllable thickness during film growth, but each growth can only obtain a material of one atomic layer at most, and the growth rate is low, therefore, it is usually used to grow BiGaO with a thickness of several nanometers to tens of nanometers ₃ Thin film materials, at most hundreds of nanometers, less than 500 nanometers, otherwise its too low growth rate will become unacceptable.

In the present invention, each separated space is a semi-open and semi-closed container. These containers are open for one section, and the other end is closed and provided with a gas pipeline. The gas pipeline is used to feed the precursor and/or inert gas;

The tray is disc-shaped and evenly distributed with a number of shallow grooves to accommodate the substrate. The depth of the shallow groove is basically the same as the thickness of the substrate, so as to ensure that the substrate does not collide with other parts during the movement.

During the film growth process, the tray moves with the substrate at the open end of each semi-open and semi-closed container, and the tray has a certain distance or gap from the container mouth, which is on the order of millimeters, so that The gas introduced into it can be discharged from the gap, and it is ensured that the tray will not collide with the container mouth when it moves with the substrate;

The layout rules of the aforementioned compartments are as follows:

B, G, O, and N respectively represent bismuth precursor gas, gallium precursor gas, oxygen precursor gas, and inert gas, then:

In the immediate vicinity of any compartment that is fed with tris(2,2,6,6-tetramethyl-3,5-heptanedionate) bismuth(III) gas or oxygen precursor gas or trimethylgallium gas On one or both sides, there are also one or more compartments for the inert gas, usually one or two compartments, i.e., for example: BN..., or GN..., or ON..., or …NBN…, or…NGN…, or…NON…, where the ellipsis “…” indicates other possible sequences; and if the above conditions are met,

On the second adjacent side of any separation space passing into tris(2,2,6,6-tetramethyl-3,5-heptanedionate) bismuth (III) gas or trimethylgallium gas, there is also One or more compartments, typically one compartment, into which the oxygen precursor gas is fed, i.e., for example: ...NONBN..., or ...NONGN..., or ...NBNON..., or ...NGNON... , where the ellipsis "..." indicates other possible permutation sequences; and when the above conditions are met,

Pass into the partition space of tris(2,2,6,6-tetramethyl-3,5-heptanedionate) bismuth (III), pass into the partition space of oxygen precursor gas, pass into trimethylgallium gas The separation space and the separation space of the inert gas can be arranged in any order, and there can be multiple groups of bismuth (III) The separation space of the oxygen precursor gas or the separation space of the trimethylgallium gas and the separation space of the inert gas are successively distributed, and then adjacent to one or more groups of the other precursor gases. compartments; in other words, one or more compartments into which trimethylgallium gas is fed, one or more compartments into which tris(2,2,6,6-tetramethyl-3,5-heptanedionate) bismuth The compartments of (III), one or more compartments into which the oxygen precursor gas is fed can be arranged in any order, for example, the compartments where bismuth precursor gas, oxygen precursor gas, gallium precursor gas, and inert gas are fed The sorting of several separation spaces can be...BNONBNONBNONGNONBNONGNON..., or...BNONGNONBNONBNONBNONBNONGNON..., or...GNONGNONBNONBNONBNONBNONBNONBNON..., or...GNONBNONBNONBNONBNONGNONBNON...etc.; here the ellipsis "..." means other possible permutations;

The number of separate spaces in the vacuum reaction chamber is a multiple of 4 and not less than 8, for example: 8, 12, 16, 20... and so on; the separate spaces are adjacent in turn and connected end to end to form a closed ring, the tray and the liner The bottom moves in the gas atmosphere formed by these separated spaces; each separated space is used to feed bismuth precursor gas, oxygen precursor gas, gallium precursor gas, and inert gas;

The sum of the number of separate spaces for feeding bismuth precursor gas and gallium precursor gas is equal to the number of separate spaces for feeding oxygen precursor, for feeding bismuth precursor gas, gallium precursor gas and oxygen precursor The sum of the number of separate spaces of the body is equal to the number of separate spaces used for the introduction of inert gas;

Considering the steric hindrance effect of the precursor molecules, the number of partitions used to feed the bismuth precursor gas is not necessarily equal to the number of partitions used to feed the gallium precursor gas, but are allocated according to the following principles :

When the tray and the substrate move in a closed loop formed by these separated spaces, the stoichiometric ratio of bismuth and gallium deposited on the substrate is close to 1:1, allowing a positive error of less than 10%, that is, bismuth and gallium The stoichiometric ratio is in the range of 1:1 to 1:1.1, which is due to the need to consider appropriate compensation for the easy volatilization of bismuth elements in step H) rapid thermal annealing;

Under the condition that the above requirements are met, the separated spaces for feeding the bismuth precursor gas and the gallium precursor gas are arranged in the above-mentioned closed ring as spatially uniform as possible.

In the thin film preparation process, the temperature of the vacuum reaction chamber, the speed of the substrate, the tris(2,2,6,6-tetramethyl-3,5-heptanedionate) bismuth (III), trimethyl The flow rate and pressure of gallium and inert gas make the substrate material pass through three (2,2,6,6-tetramethyl-3,5-heptanedionate) bismuth (III), trimethylgallium When the separation space of the substrate material can be completely adsorbed on the surface of a monomolecular layer of three (2,2,6,6-tetramethyl-3,5-heptanedionate) bismuth (III) or trimethyl Gallium, its adsorption mechanism is Langmuir (Langmuir) adsorption; when the substrate passes through the space separated by two precursors, a thin film deposition is completed, for example, when the substrate passes through BNON, a layer of Bi ₂ O ₃ is deposited.

During the thin film preparation process, the substrate temperature is within the aforementioned suitable temperature window. When the substrate passes through the bismuth precursor gas atmosphere, gallium precursor gas atmosphere, and oxygen precursor gas atmosphere each time, the chemical adsorption reaction on the substrate surface Both are "half-reaction"("half-reaction"), rather than a complete chemisorption reaction, only the substrate passes through the bismuth precursor gas atmosphere and the oxygen precursor gas atmosphere twice, or the gallium precursor gas atmosphere and the oxygen precursor atmosphere respectively. Precursor gas atmosphere, to complete a complete chemical adsorption reaction, respectively, to obtain an atomic layer of Bi ₂ O ₃ or Ga ₂ O ₃ ; , 5-heptanedionate) bismuth (III) atmosphere and water vapor atmosphere as examples, the substrate was passed through tris(2,2,6,6-tetramethyl-3,5-heptanedionate) bismuth (III) atmosphere The chemical adsorption reaction on the surface is:

※Bi-OH+Bi(tmhd) ₃ (g)→※Bi–O–Bi(tmhd) ₂ +Htmhd (1)

Then, when the substrate passes through the water vapor atmosphere, its surface chemical adsorption reaction is:

※Bi–tmhd+H ₂ O(g)→※Bi–OH+Htmhd (2)

Here, ※ indicates the adsorption site on the substrate surface, and the letter g in brackets indicates the gaseous state. In this way, a complete chemical adsorption reaction is completed on the substrate surface, and an atomic layer of Bi ₂ O ₃ is obtained. In fact, the actual chemisorption reaction may be more complex than described by the above two equations, for example, one Bi(tmhd) ₃ molecule may combine with more than one hydroxyl group (–OH), see Equation (1).

In the present invention, the molecular formula of tris(2,2,6,6-tetramethyl-3,5-heptanedionate) bismuth(III) is expressed as Bi(tmhd) ₃ , where tmhd represents 2,2,6 ,6-Tetramethyl-3,5-heptanedionate-group.

During the thin film preparation process, the temperature of the vacuum reaction chamber and the moving speed of the substrate were kept constant, and bismuth tris(2,2,6,6-tetramethyl-3,5-heptanedionate) passed into each compartment (III) The flow rate, pressure, and temperature of gas, trimethylgallium gas, and inert gas are also kept constant, and they are continuously fed into each compartment, and each gas pipeline is controlled by a mass flow controller (MFC). Control the gas flow rate and pressure.

In the film preparation process, the air pressures of the separated spaces fed with the same precursor are basically the same, but the air pressures of the separated spaces fed with different precursors do not have to be the same (that is, they can be the same or different). In addition, in order to ensure the growth process is accurate Controllable, when various gases are introduced, the gas flow rate of each pipeline must be adjusted so that the air pressure of each separated space must follow the following rules:

The air pressure of the partition filled with inert gas must be greater than the pressure of the adjacent partition fed with bismuth precursor gas, gallium precursor gas or oxygen precursor gas, allowing a small amount of inert gas in the partition filled with inert gas Invasion through the gap into the adjacent separation space of other precursor gases (ie bismuth precursor, gallium precursor, oxygen precursor), the opposite situation is not allowed to happen, in this case, the meaning of the "small amount" It means that although a small amount of inert gas is allowed to intrude into the adjacent separation space through the gap, it can still be ensured that each time the substrate passes through the atmosphere of bismuth precursor gas, gallium precursor gas, and oxygen precursor gas, the substrate can be made respectively A monolayer of bismuth precursor molecules, gallium precursor molecules, and oxygen precursor molecules is completely chemically adsorbed on the surface.

It is not necessary to require uniform concentrations of bismuth precursor molecules, gallium precursor molecules, and oxygen precursor molecules in each partition space where bismuth precursor gas, gallium precursor gas, and oxygen precursor gas are fed, and a certain concentration gradient is allowed. However, the distribution should be so wide that a monomolecular layer of bismuth precursor molecules, gallium precursor molecules, and oxygen precursor molecules can be completely chemically adsorbed on the substrate surface.

In the present invention, the substrate can be Si, LaNiO ₃ /Si, Pt/TiO ₂ /SiO ₂ /Si, Pt/Ti/SiO ₂ /Si, or other suitable substrates, such as TiN, _SiO2 etc.

In the present invention, the term "inert gas" not only refers to the inert gas (helium, argon, etc.) generally referred to in the chemical field, but also includes other gases that do not chemically react with the precursor during the entire film preparation process, Example: Nitrogen.

In the present invention, the oxygen precursor gas can be any one of H ₂ O, O ₂ , O ₃ , or a mixed gas of any two or three of them, wherein H ₂ O is deionized water, and O ₂ , O ₃ purity is higher than 99.999%.

In the present invention, the bismuth precursor and the gallium precursor are respectively tris(2,2,6,6-tetramethyl-3,5-heptanedionate) bismuth (III) and trimethylgallium; And in the case of meeting the actual needs, the bismuth precursor can also use triphenylbismuth, trimethylbismuth, tri-tert-butoxide bismuth, trimethylsilylbismuth, etc., and the gallium precursor can also use triethylgallium, Tri-tert-butylgallium.

Preferably, substrate sheets can be arranged on the tray to improve production efficiency.

Preferably, the main part of the vacuum reaction chamber is in the shape of a barrel except the two ends for ventilation and exhaust.

Preferably, the tray is disc-shaped and has a plurality of shallow slots evenly distributed therein to accommodate the substrates.

Preferably, the tray is driven by a motor to drive the substrate to rotate at a constant speed.

Preferably, a control system is provided, and the number of turns that the tray rotates is set and controlled by the control system, thereby controlling the thickness of the _BiGaO3 thin film material. The control system can be a customized special circuit, and can be controlled by a PLC ( Programmable Logic Controller), can be composed of FPGA (Field Programmable Gate Array), can also be composed of CPLD (Complex Programmable Logic Device), can also be composed of a single-chip computer, or a PC; pre-set before thin film deposition The number of rotations of the tray is fixed. When the film deposition starts, the system starts counting. After the tray rotates the set number of times, the motor stops and the introduction of various precursor gases is stopped.

During the implementation process, it should be designed so that the size and area of the pallet are larger than the closed ring formed by all the separated spaces. In this way, various precursor gases can be fully contacted with the substrate to complete a complete surface chemical adsorption.

Beneficial effects of the present invention:

By adopting the method for preparing the _BiGaO3 thin film material of the present invention, the precise and controllable growth thickness of the _BiGaO3 thin film can be realized, and the surface flatness of the _BiGaO3 thin film is much better than that of the prior art. At the same time, since the feeding of various gases is continuous and the flow rate is constant, the thickness of the film only depends on the number of times the substrate turns, and the process becomes extremely simple and reliable.

Description of drawings

Figure 1: Schematic diagram of the suitable temperature window for thin film growth. In the figure, L represents the lower limit of temperature, and H represents the upper limit of temperature; within the temperature window, the deposition rate does not change with temperature; when the temperature is not high enough, the condensation of the precursor causes multilayer adsorption and leads to over A high deposition rate may lead to incomplete adsorption and poor reactivity; when the temperature is too high, the decomposition of the precursor leads to additional CVD growth, or due to the high thermal kinetic energy, the precursor is desorbed.

Figure 2: Tris(2,2,6,6-tetramethyl-3,5-heptanedionate) bismuth(III), tri-tert-butylgallium, The arrangement of each partition space when H ₂ O is used, B, G, O, and N in the figure represent bismuth precursor gas, gallium precursor gas, oxygen precursor gas, and inert gas, respectively.

Figure 3: Arrangement of separate spaces when trimethylbismuth, trimethylgallium, and H ₂ O are used as bismuth precursors, gallium precursors, and oxygen precursors, respectively. B, G, O, and N represent bismuth precursors in the figure precursor gas, gallium precursor gas, oxygen precursor gas, inert gas.

Figure 4: Arrangement of separate spaces when triphenylbismuth, triethylgallium, and H ₂ O are used as bismuth precursors, gallium precursors, and oxygen precursors, respectively. B, G, O, and N represent bismuth precursors in the figure precursor gas, gallium precursor gas, oxygen precursor gas, inert gas.

detailed description

The technical solution of the present invention will be specifically introduced below in conjunction with examples.

Example 1:

The used vacuum reaction chamber includes 32 separate spaces, which are respectively used to pass through tris(2,2,6,6-tetramethyl-3,5-heptanedionate) bismuth (III) steam, tri-tertiary Butylgallium vapor, H ₂ O vapor, N ₂ (nitrogen) with a purity of more than 99.9995%; B, G, O, and N respectively represent bismuth precursor gas, gallium precursor gas, oxygen precursor gas, and high-purity nitrogen , the sequence of these partition spaces is shown in Figure 2.

Tris(2,2,6,6-tetramethyl-3,5-heptanedionate)bismuth(III) vapor was generated from a solid source vial, starting from tris(2,2,6,6-tetramethyl- Bismuth (III) 3,5-heptanedionate is heated at 170-195°C to produce bismuth (III) tris(2,2,6,6-tetramethyl-3,5-heptanedionate) steam;

H ₂ O vapor is generated from a liquid source bottle, and the raw material is at room temperature and properly cooled by a semiconductor refrigeration chip to avoid excessive vapor pressure;

Tri-tert-butylgallium vapor is generated from a liquid source bottle, and tri-tert-butylgallium is diluted and dissolved with an organic solvent to generate tri-tert-butylgallium vapor;

During the film deposition process, the pressure in the vacuum reaction chamber is maintained at 1–10hPa;

A) Blow dry the cleaned Si substrate material with high-purity nitrogen gas (purity higher than 99.9995%), and place it into a substrate tray;

B) The tray and the substrate are moved into the vacuum reaction chamber through the electric moving rod, after closing the chamber door of the vacuum chamber, turn on the vacuum pump to evacuate the vacuum reaction chamber to maintain the vacuum degree at 1-10hPa;

C) heating the vacuum chamber so that the temperature of the tray and the substrate in the vacuum chamber is maintained at 300° C. during the entire film growth process;

D) When the temperature of the vacuum chamber is constant for a period of time, set the number of rotations of the tray and the substrate to 300, and the rotation speed to 1rpm; the different compartments of the vacuum reaction chamber are respectively fed with high-purity nitrogen, three (2,2,6, 6-Tetramethyl-3,5-heptanedionate) bismuth (III), H ₂ O gas and tri-tert-butylgallium gas; all precursor gases are transported by high-purity nitrogen gas;

Pipelines for feeding tris(2,2,6,6-tetramethyl-3,5-heptanedionate) bismuth(III) vapor, tri-tert-butylgallium vapor, H ₂ O vapor, and high-purity nitrogen gas The gas flow rates are 150sccm, 150sccm, 150sccm, and 250sccm respectively; the flow rates of high-purity nitrogen gas are higher than those of other precursor gases, which can ensure that each precursor gas will not crosstalk in their separate spaces and ensure the growth rate of the film Precise and controllable;

E) The substrate tray drives the substrate material to move together. In the separated space where tris(2,2,6,6-tetramethyl-3,5-heptanedionate) bismuth (III) gas is introduced, the high The separation space of pure nitrogen gas, the separation space of tri-tert-butylgallium gas, and the separation space of H ₂ O gas pass through four kinds of separation spaces;

F) When the rotation of the tray and the substrate reaches the set number of 300 turns, stop the rotation to obtain a certain thickness of BiGaO ₃ thin film material, stop feeding bismuth precursors, gallium precursors, and oxygen precursors, and continue feeding high-purity nitrogen , stop the tray and substrate, stop the heating of the vacuum chamber, and perform natural cooling;

G) When the vacuum chamber is at or close to room temperature, turn off the vacuum pump, and inflate the vacuum reaction chamber with high-purity nitrogen to make the air pressure reach an atmospheric pressure. At this time, the air pressure inside and outside the vacuum reaction chamber reaches equilibrium, open the chamber door, and take out the deposited BiGaO ₃ film the substrate of the material;

H) The substrate obtained in the step G with the _BiGaO thin film material attached is placed in a rapid annealing furnace for rapid thermal annealing, that is, the following three rapid thermal annealing (RTA) steps are successively performed:

(a) maintaining at 180-220°C for 3 minutes;

(b) maintain at 390-400°C for 5 minutes;

(c) high temperature annealing at 700°C-750°C for 5 minutes;

Take it out after cooling naturally.

A series of tests were performed on the obtained film samples.

Example 2:

The used vacuum reaction chamber includes 32 separate spaces, which are respectively used to feed trimethylbismuth vapor, trimethylgallium vapor, H ₂ O vapor, and N ₂ (nitrogen) with a purity of more than 99.9995%; , G, O, and N respectively represent bismuth precursor gas, gallium precursor gas, oxygen precursor gas, and high-purity nitrogen gas, and the arrangement order of these separated spaces is shown in FIG. 3 .

Trimethylbismuth vapor is generated from a liquid source bottle, and trimethylbismuth is diluted and dissolved with an organic solvent to generate trimethylbismuth vapor;

Trimethylgallium vapor is generated from a liquid source bottle, and trimethylgallium is diluted and dissolved with an organic solvent to generate trimethylgallium vapor;

H ₂ O vapor is generated from a liquid source bottle, and the raw material is at room temperature and properly cooled by a semiconductor refrigeration chip to avoid excessive vapor pressure;

During the film deposition process, the pressure in the vacuum reaction chamber is maintained at 1–10hPa;

A) Blow dry the cleaned Si substrate material with high-purity nitrogen gas (purity higher than 99.9995%), and place it into a substrate tray;

B) The tray and the substrate are moved into the vacuum reaction chamber through the electric moving rod, after closing the chamber door of the vacuum chamber, turn on the vacuum pump to evacuate the vacuum reaction chamber to maintain the vacuum degree at 1-10hPa;

C) heating the vacuum chamber so that the temperature of the tray and the substrate in the vacuum chamber is maintained at 330° C. during the entire film growth process;

D) When the temperature of the vacuum chamber is constant for a period of time, set the number of rotations of the tray and the substrate to 300, and the rotation speed to 1rpm; the different compartments of the vacuum reaction chamber are respectively fed with high-purity nitrogen, trimethylbismuth, and H ₂ O gas and trimethylgallium gas; all precursor gases are transported by high-purity nitrogen;

The gas flow rates in the pipelines feeding trimethylbismuth, trimethylgallium vapor, H ₂ O vapor, and high-purity nitrogen gas are 150 sccm, 150 sccm, 150 sccm, and 250 sccm respectively; the flow rates of high-purity nitrogen gas are higher than those of other precursors The gas flow rate can ensure that each precursor gas will not crosstalk in its own separate space, and ensure that the growth rate of the film is accurately and controllable;

E) The substrate tray drives the substrate material to move together. In the partition space where trimethylbismuth gas is fed, the partition space where high-purity nitrogen gas is fed, the partition space where trimethylgallium gas is fed, and H ₂ O gas is fed Pass between the four kinds of separation spaces such as the separation space;

F) When the rotation of the tray and the substrate reaches the set number of 300 turns, stop the rotation to obtain a certain thickness of BiGaO ₃ thin film material, stop feeding bismuth precursors, gallium precursors, and oxygen precursors, and continue feeding high-purity nitrogen , stop the tray and substrate, stop the heating of the vacuum chamber, and perform natural cooling;

G) When the vacuum chamber is at or close to room temperature, turn off the vacuum pump, and inflate the vacuum reaction chamber with high-purity nitrogen to make the air pressure reach an atmospheric pressure. At this time, the air pressure inside and outside the vacuum reaction chamber reaches equilibrium, open the chamber door, and take out the deposited BiGaO ₃ film the substrate of the material;

H) The substrate obtained in the step G with the _BiGaO thin film material attached is placed in a rapid annealing furnace for rapid thermal annealing, that is, the following three rapid thermal annealing (RTA) steps are successively performed:

(a) maintaining at 180-220°C for 3 minutes;

(b) maintain at 390-400°C for 5 minutes;

(c) high temperature annealing at 700°C-750°C for 5 minutes;

Take it out after cooling naturally.

Example 3:

The used vacuum reaction chamber includes 32 separate spaces, which are respectively used to feed triphenylbismuth vapor, triethylgallium vapor, H ₂ O vapor, and N ₂ (nitrogen) with a purity of more than 99.9995%; , G, O, and N respectively represent bismuth precursor gas, gallium precursor gas, oxygen precursor gas, and high-purity nitrogen gas, and the arrangement order of these separated spaces is shown in FIG. 4 .

Triphenylbismuth vapor is generated from a liquid source bottle, and triphenylbismuth is diluted and dissolved with an organic solvent to generate triphenylbismuth vapor;

Triethylgallium vapor is generated from a liquid source bottle, and triethylgallium is diluted and dissolved with an organic solvent to generate triethylgallium vapor;

H ₂ O vapor is generated from a liquid source bottle, and the raw material is at room temperature and properly cooled by a semiconductor refrigeration chip to avoid excessive vapor pressure;

During the film deposition process, the pressure in the vacuum reaction chamber is maintained at 1–10hPa;

A) Blow dry the cleaned TiN substrate material with high-purity nitrogen (purity higher than 99.9995%), and place it into a substrate tray;

B) The tray and the substrate are moved into the vacuum reaction chamber through the electric moving rod, after closing the chamber door of the vacuum chamber, turn on the vacuum pump to evacuate the vacuum reaction chamber to maintain the vacuum degree at 1-10hPa;

C) heating the vacuum chamber so that the temperature of the tray and the substrate in the vacuum chamber is maintained at 270° C. during the entire film growth process;

D) When the temperature of the vacuum chamber is constant for a period of time, set the number of rotations of the tray and the substrate to 500, and the rotation speed to 2rpm; the different compartments of the vacuum reaction chamber are respectively fed with high-purity nitrogen, triphenylbismuth, and H ₂ O gas and triethylgallium gas; all precursor gases are transported by high-purity nitrogen;

The gas flow rates in the pipelines of triphenylbismuth, triethylgallium vapor, H ₂ O vapor, and high-purity nitrogen gas are 150 sccm, 150 sccm, 150 sccm, and 250 sccm respectively; the flow rates of high-purity nitrogen gas are higher than those of other precursors The gas flow rate can ensure that each precursor gas will not crosstalk in its own separate space, and ensure that the growth rate of the film is accurately and controllable;

E) The substrate tray drives the substrate material to move together. In the partition space where triphenylbismuth gas is fed, the partition space where high-purity nitrogen gas is fed, the partition space where triethylgallium gas is fed, and H ₂ O gas is fed Pass between the four kinds of separation spaces such as the separation space;

F) When the rotation of the tray and the substrate reaches the set number of 300 turns, stop the rotation to obtain a certain thickness of BiGaO ₃ thin film material, stop feeding bismuth precursors, gallium precursors, and oxygen precursors, and continue feeding high-purity nitrogen , stop the tray and substrate, stop the heating of the vacuum chamber, and perform natural cooling;

G) When the vacuum chamber is at or close to room temperature, turn off the vacuum pump, and inflate the vacuum reaction chamber with high-purity nitrogen to make the air pressure reach an atmospheric pressure. At this time, the air pressure inside and outside the vacuum reaction chamber reaches equilibrium, open the chamber door, and take out the deposited BiGaO ₃ film the substrate of the material;

H) The substrate obtained in the step G with the _BiGaO thin film material attached is placed in a rapid annealing furnace for rapid thermal annealing, that is, the following three rapid thermal annealing (RTA) steps are successively performed:

(a) maintaining at 180-220°C for 3 minutes;

(b) maintain at 390-400°C for 5 minutes;

(c) high temperature annealing at 700°C-750°C for 5 minutes;

Take it out after cooling naturally.

Claims (10)

1. a kind of being reacted from restricted adsorption for use presoma space cellular-type prepares BiGaO₃The method of thin-film material, BiGaO₃Thin-film material is grown on backing material, and described substrate includes Si, LaNiO₃/Si、Pt/TiO₂/SiO₂/Si、Pt/ Ti/SiO₂/Si、TiN、SiO₂, described BiGaO₃The space group of thin-film material be Pcca, lattice constant be a=5.626, b= 5.081, c=10.339, described BiGaO₃Thin-film material is in the preferred orientation that selected Grown is obtained （112）；

It is characterized in that：

The BiGaO₃Thin-film material thickness is less than 500 nanometers；

Obtained using presoma time-division formula from the reaction of restricted adsorption,

The irreversible Chemisorption of Langmuir absorption mechanism is refered in particular in the adsorption reaction；

Chemisorption is carried out in vacuum reaction chamber, and multiple compartments are included in vacuum reaction chamber, is respectively used to lead to Enter bismuth precursor gas, gallium precursor gas, oxygen precursor gas, inert gas；

Air-flow in all gas pipings is constantly passed through in whole film deposition process, and the air-flow of each pipeline Flow velocity, pressure keep invariable；

The quantity of each compartment in vacuum reaction chamber for 4 multiple and not less than 8；Each compartment is adjacent successively and head Tail is connected to form close ring, and pallet and substrate are moved in the atmosphere that these compartments are formed；For being passed through bismuth forerunner The quantity sum of the compartment of body gas and gallium precursor gas is equal to the compartment for being passed through oxygen precursor gas Quantity, is equal to for being passed through the quantity sum of the compartment of bismuth precursor gas, gallium precursor gas and oxygen precursor gas For the quantity for the compartment for being passed through inert gas；

The arrangement rule of the compartment is as follows：

In any one be passed through three (DPM dpm,dipivalomethane acid) bismuth (III) gases or oxygen precursor gas or The closest one or both sides of the compartment of trimethyl gallium gas, all also have one or more points for being passed through inert gas Every space, and in the case where meeting above-mentioned condition,

In any one (DPM dpm,dipivalomethane acid) bismuth (III) gas that are passed through three or trimethyl gallium gas The secondary adjacent side of the compartment, all also has one or more compartments for being passed through oxygen precursor gas；

The bismuth presoma used is three (2,2,6,6- tetramethyl -3,5- heptadione acid) bismuth (III), and gallium presoma is trimethyl Gallium, oxygen presoma can be H₂O、O₂、O₃Any of which or wherein any two or three of mixed gas；Institute State " inert gas " and refer to the gas that will not be chemically reacted in whole membrane-film preparation process with presoma；

In whole thin film growth process, all precursor gas are respectively transported using inert gas；

This method includes but is not limited to step in detail below：

A）The backing material of cleaning is dried up with inert gas, is placed into substrate pallet；

B）Pallet moves into vacuum reaction chamber together with substrate, opens vavuum pump and vacuum reaction chamber is vacuumized；

C）Vacuum chamber is heated, pallet and substrate temperature in vacuum chamber is maintained in whole thin film growth process One suitable temperature window；

Selected suitable temperature window refers to：Within the scope of suitable temperature, i.e., at higher than one temperature of substrate temperature Limit and less than one temperature upper limit, and the flow velocity that precursor gas is supplied, more than in the case of minimum limit value, the growth of film is fast Rate is a substantially invariable value, the growth rate of film and the stream that the flow velocity of precursor gas supply, carrier gas are inert gas Speed, the vacuum of the temperature of presoma, substrate temperature, the compartment of vacuum chamber are substantially unrelated, when growth temperature exceeds this Temperature window is i.e. less than lowest temperature or higher than temperature upper limit, and the growth rate of film then can be significantly increased or reduced；

D）Surely after cavity temperature constant a period of time, the number of turns that setting pallet is rotated together with substrate, the difference of vacuum reaction chamber The compartment each leads into inert gas, three (DPM dpm,dipivalomethane acid) bismuth (III) gases, oxygen presoma Gas and trimethyl gallium gas；

E）Substrate bracket disk drives backing material to move together, is being passed through three (2,2,6,6- tetramethyl -3,5- heptadione acid) bismuths (III) the compartment, the compartment for being passed through the compartment of inert gas, being passed through trimethyl gallium gas, it is passed through oxygen forerunner Pass through between four kinds of compartments of the compartment of body gas；

F）When pallet and substrate, which are rotated, reaches the number of turns of setting, stop operating, film thickness reaches desirable value, stopping is passed through bismuth Precursor gas, gallium precursor gas, oxygen precursor gas, continue to be passed through inert gas, stop pallet and substrate, stop vacuum The heating of chamber carries out natural cooling；

G）Vacuum chamber reaches or during close to room temperature, closes vavuum pump, vacuum reaction chamber, which is inflated, makes its air pressure reach one Atmospheric pressure, taking-up, which has been deposited, obtains BiGaO₃The substrate of thin-film material；

H）BiGaO is attached with by what is obtained in step G₃The substrate of thin-film material, is put into quick anneal oven, carries out fast speed heat and moves back Taken out after fire processing, natural cooling.

2. a kind of preparation BiGaO as claimed in claim 1₃The method of thin-film material, it is characterised in that：Bismuth precursor gas is adopted With triphenyl bismuth, trimethyl-bismuthine, three tert-butyl alcohol base bismuths or trimethylsilyl bismuth.

3. a kind of preparation BiGaO as claimed in claim 1₃The method of thin-film material, it is characterised in that：Gallium precursor gas is adopted With triethyl-gallium or tri-tert gallium.

4. a kind of preparation BiGaO as described in claim any one of 1-3₃The method of thin-film material, it is characterised in that：For leading to Enter bismuth precursor gas the compartment quantity with for be passed through gallium precursor gas the compartment quantity according to as follows Principle is allocated：

When pallet and substrate are moved one week in the close ring that these compartments are constituted, obtained bismuth, gallium are deposited on substrate Stoichiometric proportion close to 1:1, it is allowed to have the stoichiometric proportion of less than 10% positive error, i.e. bismuth, gallium 1:1~1:1.1 In the range of；Excessive bismuth will be in step H）It is middle volatilization and remove substantially.

5. a kind of preparation BiGaO as claimed in claim 4₃The method of thin-film material, it is characterised in that：Meeting claim 4 In the case of the requirement, for being passed through bismuth precursor gas, the compartment of gallium precursor gas in close ring as far as possible Ground is spatially uniformly distributed arrangement.

6. a kind of preparation BiGaO as described in claim any one of 1-3₃The method of thin-film material, it is characterised in that：

The air pressure of each compartment follows following rules：

Be passed through the compartment of inert gas air pressure have to be larger than it is neighbouring be passed through bismuth precursor gas, gallium precursor gas or The air pressure of the compartment of oxygen precursor gas, it is allowed to which the inert gas being passed through in the compartment of inert gas has a small amount of part The neighbouring compartment for being passed through bismuth precursor gas, gallium precursor gas, oxygen precursor gas is invaded by gap, conversely Situation do not allow then occur, in the case, the connotation of " a small amount of " refers to：Although allowing there is a small amount of inert gas to pass through Gap invades the neighbouring compartment, but still may insure substrate every time by bismuth precursor gas, gallium precursor gas, During oxygen precursor gas atmosphere, the bismuth precursor gas of the substrate surface intactly monolayer of chemisorbed one can be made respectively Molecule, gallium precursor gas molecule, oxygen precursor gas molecule.

7. a kind of preparation BiGaO as described in claim any one of 1-3₃The method of thin-film material, it is characterised in that：

Pallet is discoid, and has been evenly distributed multiple shallow slots to accommodate substrate, and the depth of shallow slot and the thickness of substrate are basic It is identical, to ensure that substrate does not collide with motion process with miscellaneous part.

8. a kind of preparation BiGaO as described in claim any one of 1-3₃The method of thin-film material, it is characterised in that：

Pallet is driven by motor, drives substrate evenly to rotate.

9. a kind of preparation BiGaO as claimed in claim 7₃The method of thin-film material, it is characterised in that：

The number of turns for being set by control system, controlling pallet to rotate, thus controls to obtain BiGaO₃The thickness of thin-film material, institute The special circuit that control system is customization is stated, is made up of PLC, or is made up of FPGA, or is made up of CPLD, or single-chip microcomputer is constituted, Or PC；The number of times of pallet rotation is preset before thin film deposition, system is started counting up after thin film deposition starts, pallet After the number of turns for turning over setting, stop motor and rotate and stop being passed through various precursor gas.

10. a kind of preparation BiGaO as claimed in claim 1₃The method of thin-film material, it is characterised in that：It is passed through inert gas The air pressure of the compartment is more than the gas for the compartment for being passed through gallium precursor gas or bismuth precursor gas or oxygen precursor gas Pressure.