JP4164797B2 - Film forming apparatus and film forming method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a film forming apparatus and a film forming method, and more specifically, is characterized in that the suction force between gels is increased when a sol that is a solution of a metal compound is sprayed to deposit the gel on a substrate. The present invention relates to a film forming apparatus and a film forming method.
[0002]
[Prior art]
Conventionally, a thin film formed by a film formation method using a solution of a metal compound or a sol solution is used as an electronic material such as a superconducting material, an ionic conductive material, or a capacitor material, or a heat resistant coating or wear resistance. As functional materials such as coatings and antireflection films, they are widely used as sensors, actuators, optical waveguides and the like using piezoelectricity and pyroelectricity.
[0003]
In the film forming method using the metal compound solution and the sol solution, the sol solution is applied to the substrate using a method such as spin coating, dip coating, or spraying.
[0004]
However, in these methods, when the sol applied to the substrate is gelled, gelation does not occur uniformly, and it is difficult to efficiently produce a uniform film.
In addition, when trying to create a denser film, a planar suction force (capillary force) acts between the gelled portions, causing problems such as cracks on the surface.
[0005]
In order not to generate this suction force (capillary force) on the substrate, the solvent is almost evaporated before the spray pyrolysis method (see, for example, Patent Document 1) or the atomized sol solvent is attached to the substrate. A manufacturing method (for example, refer to Patent Document 3) such as a method for making it (for example, refer to Patent Document 2) and an Aerosol Deposition Method (ADM) have been developed.
[0006]
In these methods, since the sol is sprayed in the air to evaporate the solvent almost completely and gel it, the dried gel is stacked on the substrate, and suction force (capillary force) works between the gels on the substrate. Therefore, a dense and uniform film can be formed.
[0007]
[Patent Document 1]
Japanese Patent Laid-Open No. 5-294661 [Patent Document 2]
JP-A-7-173634 [Patent Document 3]
Japanese Patent Application Laid-Open No. 11-1312247
[Problems to be solved by the invention]
However, since the stacked dried gels have no adsorptive power, it is necessary to devise a method to increase the density by vigorously striking the gel against the substrate by increasing the spraying speed. There has been a problem that film defects such as oxygen vacancies and small scattering points occur.
[0009]
Accordingly, an object of the present invention is to form a uniform and dense film without causing film defects.
[0010]
[Means for Solving the Problems]
FIG. 1 is a block diagram showing the principle of the present invention. Means for solving the problems in the present invention will be described with reference to FIG.
See FIG. 1 In order to achieve the above object, the present invention provides, in a film forming apparatus, a spray unit 1 that sprays a solution 4 containing a substance to be gelled as a mist sol without providing a charging mechanism, and the spray unit 1 An atmosphere control mechanism is provided in which the atmosphere in the space with the substrate 3 is an atmosphere that suppresses evaporation of the solvent in the atomized sol.
[0011]
Thus, by providing an atmosphere control mechanism that makes the atmosphere in the space between the spray unit 1 and the substrate 3 an atmosphere that suppresses evaporation of the solvent in the mist sol , gelation can be performed in the solvent atmosphere, Thereby, since a suction force acts between the gels, a uniform and dense film can be formed.
In addition, since the dried gel is not struck, film defects such as oxygen vacancies and small scattering points do not occur in the formed thin film.
[0012]
In order to control the atmosphere in the space between the spray unit 1 and the substrate 3, it is desirable to provide a mechanism for adjusting the space between the spray port 2 and the substrate 3 to an atmosphere containing water, alcohol, or a solvent.
[0013]
In this case, it is desirable to provide a mechanism for accelerating gelation of the mist sol by irradiating the mist sol with electromagnetic waves in the wavelength range from ultraviolet to microwave, thereby depositing in a gel state containing a solvent. Therefore, a three-dimensional suction force can be applied between the gels.
[0014]
Further, by providing a pH adjusting mechanism for adjusting the pH of the atmosphere in the chamber 6 of the film forming apparatus, the shape of the gel can be controlled from a chain shape to a spherical shape.
When it is acidified, it becomes a chain, and when it is basic, it becomes a sphere.
[0015]
In addition, as an atmosphere control mechanism for controlling the atmosphere in the space between the spray unit 1 and the substrate 3, it is desirable to provide a liquid tank that contains a solvent in the chamber 6 separately from the raw material supply mechanism. The atmosphere can be controlled more strictly.
[0016]
Moreover, since the spraying part 1 can be attached without changing the structure of the conventional apparatus by orienting the injection port of the spraying part 1 in the vertical direction, the device creation is simplified.
In this case, it is possible to homogenize the thin film in the surface of the substrate 3 by providing a plurality of injection ports.
[0017]
Further, by directing the spray port of the spray unit 1 in the horizontal direction, only a mist-like sol having a uniform particle size of droplets can be deposited on the substrate 3, thereby facilitating uniformization of the thin film. .
[0018]
In addition, the solution 4 containing the substance to be gelled is sprayed as a mist sol without providing a charging mechanism , and partially gelated in a state where the amount of solvent evaporation in the space between the spraying part 1 and the substrate 3 is suppressed. By depositing the sol solution 5 on the substrate 3, a minute suction force is exerted between the gels, and the gels can be adsorbed to each other, so that a dense thin film can be formed. .
[0019]
In this case, the droplet diameter of the mist sol is preferably 100 μm or less, more preferably 1 to 5 μm. If the droplets are too large, it is difficult to obtain a uniform film.
[0020]
The solution 4 containing the substance to be gelled is desirably partially gelled in advance, so that the gel can be deposited in a state containing the solvent.
In this case, the solution 4 containing the substance to be gelled may be mixed in advance with a powder of the substance to be gelled having a fine particle diameter.
[0021]
DETAILED DESCRIPTION OF THE INVENTION
Here, the first embodiment of the present invention will be described with reference to FIGS.
2 is a conceptual configuration diagram of the film forming apparatus according to the first embodiment of the present invention. A heater 13 is accommodated in the chamber 11, a stage 12 on which a substrate 14 is placed, a sol A spray nozzle 15 for spraying the solution, a plurality of gas introduction ports 16 for introducing the above to control the atmosphere inside the chamber 11, a vacuum pump 23 for evacuating the inside of the chamber 11, an atmosphere and a reaction product An exhaust port 24 for discharging the gas etc. is attached.
The heater 13 may be a heater capable of heating up to 400 ° C.
[0022]
The spray nozzle 15 in this case may be any one that can spray a mist sol of droplets of 100 μm or less, but an ultra fine mist generating fluid capable of spraying a mist sol of droplets in the range of 1 to 5 μm. A nozzle is desirable.
[0023]
The spray nozzle 15 is supplied with a sol solution containing a substance that gels from a sol solution supply device 17 through a pipe 18.
Here, in order to form PZT (PbZr _0.52 Ti _0.48 O ₃ ), which is a piezoelectric material, a PZT sol-gel solution is used as the sol solution.
[0024]
This PZT sol-gel solution is prepared by using lead acetate, zirconium propoxide, and titanium tetrapropoxide as precursors, dissolving them in 2-methoxyethanol as a solvent, and refluxing.
[0025]
In addition, a plurality of gas inlets 16 are connected to a water vapor generating device 19, an alcohol vapor generating device 20, and a solvent vapor generating device 21 through a pipe 22, such as Ar gas or N ₂ gas. Water vapor, alcohol vapor, or solvent vapor bubbled by the carrier gas is introduced into the chamber 11 from the gas inlet 16 together with the carrier gas, and the atmosphere in the space between the spray nozzle 15 and the substrate 14 is controlled.
[0026]
Next, referring to FIG. 3 as well, the film forming process of the first embodiment of the present invention will be described.
Reference to FIGS. 3A and 3B FIG. 3A is a schematic explanatory view of a film forming state in the first embodiment of the present invention, and FIG. 3B is a partially enlarged view thereof. FIG.
First, the PZT sol / gel solution is sprayed from the spray nozzle 15 as a mist of 1-5 μm droplets without heating the substrate 14 made of SrTiO ₃ .
[0027]
At this time, by introducing at least one of water vapor, alcohol vapor, or solvent vapor from the gas introduction port 16 to control the amount of solvent evaporation in the atomized sol, the atomized sol floating in the chamber 11 is removed. Gelation partially progresses inside to form a mist-like sol 25 containing gel. In this state, the gel is deposited on the substrate 14 for a predetermined time to obtain a desired film thickness.
[0028]
The gel 27 is sequentially deposited on the substrate 14 in a state containing the solvent, but the solvent is placed between the fluid gel 27 and the already aligned gel 27 on the surface of the sol solution 26 deposited on the substrate. Since the minute suction force 28 acts and adsorbs uniformly in the three-dimensional direction, a highly dense film can be obtained.
[0029]
Next, after the substrate 14 is heated to, for example, 100 ° C. by the heater 13 and further gelation proceeds, the substrate 14 is taken out from the chamber 11 and then heated to 400 ° C. to remove residual organic components in the thin film. Evaporate.
Finally, for example, PZT having a perovskite structure (PbZr _0.52 Ti _0.48 O ₃ ) is obtained by sintering at 650 ° C. in an oxygen atmosphere.
[0030]
4 (a) and 4 (b) FIG. 4 (a) is an X-ray diffraction (XRD) pattern of the sample surface formed according to the first embodiment of the present invention, and FIG. It is the X-ray diffraction pattern of the sample surface formed into a film by this film forming method.
As can be seen by comparing the figures, in the first embodiment of the present invention, the peak of the [001] plane near 2θ≈22 ° and the peak of the [002] plane near 2θ≈44 ° are shown in FIG. It can be seen that the strength is larger than the peak of), and oriented grains are grown on the substrate.
[0031]
As described above, in the first embodiment of the present invention, by controlling the atmosphere in the chamber, the gelation is partially progressed and deposited on the substrate 14 in the state of the atomized sol 25 containing the gel. Therefore, a suction force acts between the gels, whereby a dense and excellent film can be obtained.
[0032]
Further, since the suction force acts uniformly in the three-dimensional direction, the surface cracks which have been a problem in the conventional method are not generated.
Further, since the mist solution is joined by a chemical reaction, film defects such as vacancies do not occur.
[0033]
Next, the film forming apparatus according to the second embodiment of the present invention will be described with reference to FIG. 5, but is the same as the film forming apparatus according to the first embodiment except for the arrangement of the spray nozzle. Only the arrangement of the spray nozzle will be described.
FIG. 5 is a conceptual plan view of a film forming apparatus according to a second embodiment of the present invention. Here, four spray nozzles 15 are arranged on the circumference at equal intervals.
As described above, by providing the plurality of spray nozzles 15, the in-plane distribution of the atomized sol deposited on the substrate 14 is made uniform.
[0034]
That is, among the mist sol sprayed from the spray nozzle 15, large droplets do not spread so much but accumulate in the vicinity of the spray nozzle 15, and small droplets spread and leave the spray nozzle 15. When the number of nozzles is one, the droplets are distributed in the radial direction with respect to the substrate 14 in the order of the size of the droplets.
However, by disposing a plurality of spray nozzles 15, the droplet distribution is overlapped, so that the in-plane distribution of the atomized sol is made uniform.
[0035]
Next, a film forming apparatus according to a third embodiment of the present invention will be described with reference to FIG. 6. The film forming apparatus according to the first embodiment described above except that a liquid tank is provided at the bottom of the chamber. Since it is the same as the apparatus, only the changed part will be described.
FIG. 6 is a conceptual configuration diagram of a film forming apparatus according to a third embodiment of the present invention. A liquid tank section 29 is provided at the bottom of the chamber 11, and a solvent 30 is accommodated in the liquid tank section 29. It is a thing.
[0036]
The solvent 30 accommodated in the liquid tank portion 29 is heated to, for example, 150 ° C. to generate solvent vapor, and the atmosphere in the chamber 11 is controlled by the generated amount of the solvent vapor.
[0037]
As described above, in the third embodiment of the present invention, the atmosphere in the chamber 11 is more strictly controlled by a simple configuration in which a part of the chamber 11 is deformed and the liquid tank portion 29 is provided. Can do.
[0038]
Next, a film forming apparatus according to a fourth embodiment of the present invention will be described with reference to FIGS. 7 and 8, except that the spray nozzle is mounted in such a manner that the spray direction is a horizontal direction. Since it is the same as that of the film forming apparatus of 1 embodiment, only a changed part is demonstrated.
FIG. 7 is a conceptual block diagram of a film forming apparatus according to a fourth embodiment of the present invention, in which a spray nozzle 15 is attached to a side wall portion of a chamber 11 and a mist sol 25 containing gel is horizontally oriented. To be sprayed.
[0039]
FIG. 8 is an explanatory view of the deposition state in the fourth embodiment of the present invention. Of the mist sol 25 containing the gel sprayed from the spray nozzle 15, the mist having a large droplet diameter The sol 31 falls quickly, while the mist sol 33 having a small droplet diameter does not fall on the substrate 14 because the fall is slow.
[0040]
On the other hand, since only the mist sol 33 having an intermediate particle size and the same particle size of the droplets is deposited on the substrate 14, the mist sol 33 is made of a uniform mist sol 33 and has a flatter surface. A deposited film can be obtained.
[0041]
Although the embodiments of the present invention have been described above, the present invention is not limited to the configurations and conditions described in the embodiments, and various modifications can be made.
For example, in each of the above embodiments, gelation is performed from the inside by controlling the atmosphere in a state where the mist-like sol is suspended. A sol solution may be used.
In addition, in order to gelatinize to some extent in advance, the sol solution may be heated or water may be added before spraying.
[0042]
Alternatively, PZT powder or the like may be included in the sol solution, and the sol solution may be sprayed.
[0043]
Further, in order to promote gelation from the inside of the atomized sol after spraying, the atomized sol may be irradiated with infrared rays, microwaves, ultraviolet rays or the like.
In this case, the configuration of the infrared irradiation device, the microwave irradiation device, or the ultraviolet irradiation device is not particularly limited, and an infrared lamp or an ultraviolet lamp is used, or microwave irradiation is performed through a microwave waveguide. You may make it do.
[0044]
In addition, an acid such as HCl or HNO ₃ or a base such as NH ₃ may be introduced into the chamber in order to control the attractive force acting between the gels when deposited on the substrate or the shape of the gel. It is.
When an acid is introduced, the gel becomes a two-dimensional chain, and when a base is introduced, it becomes a three-dimensional sphere.
[0045]
In each of the above embodiments, the film is formed without heating the substrate. However, the mist sol may be deposited in advance with the substrate heated to 100 ° C., for example.
[0046]
In the second embodiment, four spray nozzles are arranged. However, the number of spray nozzles is arbitrary, and it is desirable to arrange them as rotationally symmetrical as possible with respect to the center point.
[0047]
In each of the above embodiments, the PZT film forming method has been described. However, the present invention is not limited to PZT, and can be applied to other metal oxide film deposition methods. Furthermore, it is applied in each field where the sol-gel method is conventionally employed.
[0048]
Here, the detailed features of the present invention will be described again with reference to FIG.
See FIG. 1 again. (Supplementary note 1) The spray part 1 that sprays the solution 4 containing the substance to be gelled as a mist sol without providing a charging mechanism, and the atmosphere in the space between the spray part 1 and the substrate 3 is mist-like. A film-forming apparatus comprising an atmosphere control mechanism that makes an atmosphere that suppresses evaporation of a solvent in a sol.
(Additional remark 2) The film forming apparatus of Additional remark 1 provided with the mechanism which irradiates the electromagnetic wave of the wavelength range of a microwave from an ultraviolet-ray to the said misty sol, and accelerates | stimulates gelatinization of the misty sol.
(Additional remark 3) The film forming apparatus of Additional remark 1 or 2 provided with the pH adjustment mechanism which adjusts the pH of the atmosphere in the chamber 6 of the said film forming apparatus.
(Additional remark 4) The liquid which accommodates the solvent in which the atmosphere control mechanism for controlling the atmosphere in the space of the said spray part 1 and the board | substrate 3 was provided in the chamber 6 of the said film forming apparatus separately from the raw material supply mechanism 4. The film forming apparatus according to any one of appendices 1 to 3, wherein the film forming apparatus is a tank.
(Supplementary note 5) The film forming apparatus according to any one of supplementary notes 1 to 4, wherein the spray port of the spray unit 1 is directed in a vertical direction.
(Supplementary note 6) The film forming apparatus according to supplementary note 5, wherein a plurality of the injection ports are provided.
(Supplementary note 7) The film forming apparatus according to any one of supplementary notes 1 to 4, wherein the spray port of the spray unit 1 is oriented in the horizontal direction.
(Additional remark 8) While spraying the solution 4 containing the substance to be gelatinized as a mist-like sol without providing a charging mechanism, and suppressing the amount of evaporation of the solvent in the space between the spray part 1 and the substrate 3, it is partially A film forming method comprising depositing a gelled sol solution 5 on the substrate 3 and adsorbing the gels with a minute suction force acting between the gels.
(Additional remark 9) The droplet diameter of the said mist-like sol is 100 micrometers or less, The film forming method of Additional remark 8 characterized by the above-mentioned.
(Supplementary note 10) In Supplementary note 8 or 9, wherein the solution 4 containing the substance to be gelated is partially gelled in advance to generate a mist-like sol composed of droplets containing a polymer gel inside. The film forming method described.
(Additional remark 11) The film forming method of any one of Additional remarks 8 thru | or 10 which mix | blends the powder of the substance to be gelatinized of a fine particle diameter previously with the solution 4 containing the substance to be gelatinized.
[0049]
【The invention's effect】
According to the present invention, in a film forming method using a metal compound solution or sol as a raw material, gels are partially gelled inside in a droplet state, and gels are sucked and deposited in a solvent atmosphere. In addition, a uniform and dense thin film can be formed without generating film defects such as oxygen vacancies and minute scattering points, which greatly contributes to improving the performance of various devices.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram of a basic configuration of the present invention.
FIG. 2 is a conceptual configuration diagram of a film forming apparatus according to a first embodiment of the present invention.
FIG. 3 is a schematic explanatory view of a film forming state in the first embodiment of the present invention.
FIG. 4 is an explanatory diagram of an X-ray diffraction pattern of a sample surface formed according to the first embodiment of the present invention.
FIG. 5 is a conceptual plan view of a film forming apparatus according to a second embodiment of the present invention.
FIG. 6 is a conceptual configuration diagram of a film forming apparatus according to a third embodiment of the present invention.
FIG. 7 is a conceptual configuration diagram of a film forming apparatus according to a fourth embodiment of the present invention.
FIG. 8 is an explanatory diagram of a deposition state in the fourth embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Spraying part 2 Spraying port 3 Substrate 4 Gel containing substance 5 Partially gelled sol solution 6 Chamber 11 Chamber 12 Stage 13 Heater 14 Substrate 15 Spray nozzle 16 Gas inlet 17 Sol solution supply device 18 Piping DESCRIPTION OF SYMBOLS 19 Steam generator 20 Alcohol vapor generator 21 Solvent vapor generator 22 Piping 23 Vacuum pump 24 Exhaust port 25 Mist sol 26 containing gel 27 Sol solution 27 deposited on substrate 27 Gel 28 Suction power 29 Liquid tank part 30 Solvent 31 Droplet Mist sol with a large particle size 32 mist sol with a uniform droplet size 33 mist sol with a small particle size

Claims (5)

A spray part that sprays a solution containing a substance to be gelled as a mist sol without providing a charging mechanism, and an atmosphere in the space between the spray part and the substrate is an atmosphere that suppresses evaporation of the solvent in the mist sol. A film forming apparatus comprising an atmosphere control mechanism.   2. The film forming apparatus according to claim 1, further comprising a mechanism for irradiating the atomized sol with electromagnetic waves in a wavelength range from ultraviolet to microwave to promote gelation of the atomized sol.   The film forming apparatus according to claim 1, further comprising a pH adjusting mechanism that adjusts a pH of an atmosphere in a chamber of the film forming apparatus.   The atmosphere control mechanism for controlling the atmosphere in the space between the spray unit and the substrate is a liquid tank containing a solvent provided separately from the raw material supply mechanism in the chamber of the film forming apparatus. The film forming apparatus according to any one of claims 1 to 3. A solution containing a substance to be gelled is sprayed as a mist sol without providing a charging mechanism, and a partially gelled sol solution is prepared in a state where the evaporation amount of the solvent in the space between the spray part and the substrate is suppressed. A film forming method comprising depositing on the substrate and adsorbing the gels with a minute suction force acting between the gels.

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