JP2007326062A - Film forming device and method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To correctly control the film thickness in a film forming device using an aerosol deposition process. <P>SOLUTION: This film forming device employs an aerosol deposition process which forms a film by blasting/accumulating a raw material powder to a substrate. In addition, the device comprises aerosol formation parts 1 to 4 which form the aerosol by dispersing the feedstock powder by gas, a film forming chamber 6, a substrate stage 8 arranged inside the film forming chamber 6, a nozzle 7 which jets the aerosol of the feedstock powder formed by the aerosol formation parts 1 to 4, to the substrate arranged on the substrate stage 8, an optical fiber for colorimetry 10 which optically measures the thickness of the film formed on the substrate on realtime, a colorimetric part 11 and a film thickness calculation part 12. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a film forming apparatus and a film forming method using an aerosol deposition method in which an aerosol in which raw material powder is dispersed in a gas is sprayed toward a substrate to form a film containing the raw material.

  2. Description of the Related Art In recent years, an aerosol deposition (AD) method, which is one of film forming techniques using a collisional adhesion phenomenon of solid particles, has attracted attention as a method for forming a film of ceramics or metal. The AD method is a film-forming method in which an aerosol in which raw material powder is dispersed is sprayed from a nozzle toward a substrate and the raw material powder collides with the substrate, thereby depositing the raw material on the substrate. That is. In the AD method, the raw material powder sprayed at a high speed collides with the lower layer such as the substrate or the previously formed deposit, and the crushing surface generated by crushing the powder at the time of the collision. The film is formed by a mechanochemical reaction that adheres to the lower layer.

  Here, aerosol refers to a colloidal system in which solid or liquid particles are suspended (dispersed) in a gas. In the present application, the particles dispersed in the aerosol are also referred to as aerosols in a broad sense. In the aerosol generated when the aerosol deposition method is performed, the size of the particles (raw material powder) dispersed in the gas varies. For example, when forming a ceramic film such as PZT, the diameter Is about 0.1 μm to 10 μm.

  Such an AD method has an advantage that a dense and strong film containing no impurities can be formed by its characteristic film formation mechanism. For this reason, the AD method is applied to insulating film coating, ceramic coating as moisture-resistant film (moisture barrier), optical material formation, magnetic material formation, catalyst carrier formation, and coloring with inorganic coloring material It can be widely used. In addition, with the development of micro electrical mechanical system (MEMS) related devices, application of the AD method to the formation of elements such as multilayer ceramic capacitors and piezoelectric actuators is also expected. Conventionally, such an element has been mainly manufactured using a bulk material. However, as the miniaturization and integration of the element progress, research for producing a functional material by a film forming technique is actively performed. Because. Here, the functional material is a material constituting a main part (usually, a layer sandwiched between electrodes) that exerts the function of the element, such as a dielectric layer in a multilayer capacitor or a piezoelectric layer in a piezoelectric actuator. That is.

  By the way, in an apparatus in which a large number of elements are integrated, it is necessary to make the characteristics of those elements uniform. For this purpose, the thickness of the functional material film (hereinafter also referred to as functional film) must be uniform between these elements. Therefore, when using the AD method, it is necessary to keep the concentration of aerosol sprayed onto the substrate uniform.

  As a related technique, Patent Document 1 discloses an aerosol generating apparatus including a powder storage unit, an aerosol generating unit, and a rotary table disposed between them as a circulating transport unit. An annular groove is formed on the horizontal upper surface of the rotary table, and powder is supplied from the hopper into the groove in the powder container, and then the powder overflows upward from the groove by the downstream squeegee plate. The body is removed. By rotating the rotary table in this state, the powder in the groove is sent to the aerosolization means, and is supplied as an aerosol to the nozzle (first page).

  However, even if a certain amount of powder is supplied to the aerosolization means, not all of the supplied powder is uniformly dispersed in the gas. For example, in general, the raw material powder (primary particles) is more likely to aggregate due to electrostatic force, van der Waals force, etc., as it is finer. However, the large aggregated particles formed by the aggregation of the primary particles have a large mass, so that they accumulate on the bottom of the container and are difficult to disperse in the gas. In addition, the powder once dispersed in the gas may agglomerate or adhere to the inner wall of the supply path before being supplied from the aerosolization means to the nozzle. Therefore, it is difficult to keep the concentration of aerosol sprayed from the nozzle constant by controlling the amount of powder supplied to the aerosolization means.

  Further, Patent Document 2 discloses that an aerosol is generated in a ceramic structure manufacturing apparatus for manufacturing a ceramic structure by causing an aerosol in which ceramic fine particles are dispersed in a gas to collide with a substrate at a high speed, and generating an aerosol having a drive unit. A ceramic structure fabrication comprising a container, a nozzle for injecting aerosol and means for adjusting the height of the ceramic structure is disclosed. In this ceramic structure manufacturing apparatus, the amount of ceramic fine particles in the aerosol is sensed by a sensor, and a signal output from the sensor is fed back to the ceramic structure manufacturing apparatus to adjust the height of the ceramic structure. (Pages 1 and 2).

  However, in practice, not all the powders contained in the aerosol ejected from the nozzle contribute to the formation of the ceramic structure (film). For example, when the aerosol contains aggregated particles, the kinetic energy of the aggregated particles when they are ejected from the nozzle is resolved when the aggregated particles collide with the substrate. It will be consumed as energy to be crushed. Accordingly, the primary particles generated thereby are already insufficient in kinetic energy, and therefore cannot be further crushed and attached to the lower layer. Therefore, it is difficult to accurately estimate the deposition height of the ceramic structure based on the concentration of the aerosol ejected from the nozzle.

  Further, Patent Document 3 holds a container in which raw material powder is placed, a gas introducing means for generating aerosol by blowing up the raw material powder in the container, and a substrate on which a structure is formed. A holding means, a nozzle for injecting the aerosol generated in the container toward the substrate, and a raw material powder contained in the aerosol injected from the nozzle, the substrate or a structure formed on the substrate. There has been disclosed a film forming apparatus including detection means for determining the amount of raw material powder that contributed to film formation by collision.

  In Patent Document 3, the amount of powder that actually contributed to film formation is obtained by detecting a phenomenon (discharge, light emission, or color change) that occurs when primary particles collide with the lower layer and are crushed. Therefore, it is possible to estimate the deposition height of the structure relatively accurately. However, since there is still a slight difference between the estimated height of the structure and the actual height, it is desirable to be able to detect the height of the structure more accurately.

On the other hand, Non-Patent Document 1 describes that in a vacuum deposition method, the film thickness is generally monitored by using a crystal resonator. In the sputtering method, the process is stable and the film formation rate can be controlled relatively well. Therefore, the film thickness is usually controlled based on the film formation time.
JP 2003-275631 A (first page) JP 2001-348659 A (first and second pages) Japanese Patent Laying-Open No. 2005-154894 (first page) Kanehara, “Basic Technology of Thin Films”, 2nd edition, University of Tokyo Press, August 2002, p. 109-114

  In the AD method, since the process is not as stable as the sputtering method, it is difficult to control the film thickness by the film formation time. In the AD method, since aerosol is collided with the substrate, vibration noise is always generated by the impact. Therefore, it is difficult to measure the film thickness on the spot using a crystal resonator. Furthermore, an optical film thickness measurement method such as a spectroscopic ellipsometer is also known as a measurement method that is not significantly affected by vibration. Here, a spectroscopic ellipsometer measures film thickness, optical constants, and material properties by observing changes in the polarization state between incident light and reflected light when light is reflected on the surface of the material. It is a method to do. However, the spectroscopic ellipsometer can measure only a thin film having an upper limit of 5 μm at most, and it is difficult to measure a film having irregularities on the surface or an optically opaque film. Therefore, it is not appropriate to apply such a film thickness measurement method to the AD method that can form a thicker film.

  In view of the above points, an object of the present invention is to accurately control the film thickness in a film forming apparatus and a film forming method using the AD method.

  In order to solve the above problems, a film forming apparatus according to one aspect of the present invention is a film forming apparatus using an aerosol deposition method in which a film is formed by spraying and depositing raw material powder on a substrate, An aerosol generating means for generating an aerosol by dispersing the gas with a gas, a film forming chamber, a substrate stage disposed in the film forming chamber, and an aerosol of the raw material powder generated by the aerosol generating means on the substrate stage And a nozzle for spraying toward the substrate, and a measuring means for optically measuring the thickness of the film formed on the substrate in real time.

  A film forming method according to one aspect of the present invention is a film forming method by an aerosol deposition method in which a raw material powder is sprayed and deposited on a substrate to form a film, and the raw material powder is dispersed by a gas. The aerosol of the raw material powder generated in step (a) is jetted toward the substrate while optically measuring the thickness of the film formed on the substrate (a) and the thickness of the film formed on the substrate in real time. A step (b) of depositing the raw material powder on the substrate.

  According to the present invention, since the film is formed by grasping the currently formed film thickness by optically monitoring the film, a desired film thickness can be obtained.

Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to the drawings. The same constituent elements are denoted by the same reference numerals, and the description thereof is omitted.
FIG. 1 is a schematic diagram showing a configuration of a film forming apparatus according to the first embodiment of the present invention. As shown in FIG. 1, the film forming apparatus includes an aerosol generating unit that generates aerosol and a film forming unit.

The aerosol generation unit includes an aerosol generation chamber 1, a vibration table 2, a hoisting gas nozzle 3, and a pressure adjusting gas nozzle 4.
The aerosol generation chamber 1 is a container in which raw material powder (raw material powder) 15 is arranged, and aerosol is generated here. The aerosol generation chamber 1 is installed on a vibration table 2 that vibrates at a predetermined frequency in order to efficiently generate aerosol by stirring the raw material powder 15.

The winding gas nozzle 3 generates a cyclone flow by introducing a carrier gas supplied from an external gas cylinder into the aerosol generation chamber 1. Thereby, the raw material powder 15 arrange | positioned in the aerosol production | generation chamber 1 is wound up and disperse | distributed, and an aerosol is produced | generated.
The pressure adjusting gas nozzle 4 adjusts the gas pressure in the aerosol generating chamber 1 by introducing a carrier gas supplied from an external gas cylinder into the aerosol generating chamber 1. Thereby, the difference between the pressure in the aerosol generation chamber 1 and the pressure in the film forming chamber 6 is adjusted.

Examples of the carrier gas supplied by the hoisting gas nozzle 3 and the pressure adjusting gas nozzle 4 include helium (He), oxygen (O ₂ ), nitrogen (N ₂ ), argon (Ar), a mixed gas thereof, or dry air. Etc. are used.
Such an aerosol generating unit is connected to the film forming unit by the aerosol transport pipe 5, and the aerosol generated in the aerosol generating chamber 1 is disposed in the film forming chamber 6 through the aerosol transport pipe 5. Is supplied to the injection nozzle 7.

On the other hand, the film forming unit includes a film forming chamber 6, an injection nozzle 7, a substrate stage 8, an exhaust pipe 9, a color measuring optical fiber 10, a color measuring unit 11, a film thickness calculating unit 12, and a display. The unit 13 and the control unit 14 are included.
The injection nozzle 7 has an opening having a predetermined shape and size, and injects the aerosol of the raw material powder supplied from the aerosol generation chamber 1 via the aerosol transport pipe 5 toward the substrate 16. The velocity of the aerosol ejected from the ejection nozzle 7 is determined by the pressure difference between the aerosol generation chamber 1 and the film forming chamber 6.

The substrate stage 8 on which the substrate 16 is fixed is a three-dimensionally movable stage for controlling the relative position and relative speed between the substrate 16 and the injection nozzle 7. By adjusting this relative speed, the thickness of the film formed per reciprocation is controlled.
The inside of the film forming chamber 6 is evacuated by an exhaust pump connected to an exhaust pipe 9, thereby maintaining a predetermined degree of vacuum.

The color measuring optical fiber 10 to the film thickness calculator 12 perform in-situ observation on the thickness of the film being formed in real time.
Here, the inventor of the present application repeated the film formation experiment by the AD method, and found that the surface color of the film being formed changed from black to yellow. This phenomenon is considered to be caused by the following principle. That is, immediately after the start of film formation and in the initial stage of film formation, the raw material powder sprayed from the nozzle 7 collides with the relatively hard substrate 16, and oxygen defects are likely to occur on the surface of the film 17. Accordingly, the surface of the film 17 becomes close to black. On the other hand, after the middle stage of film formation, the raw material powder sprayed from the nozzle 7 collides with the film 17 previously formed on the substrate 16. Since this film 17 (for example, a ceramic film such as PZT) is usually softer than the substrate 16, the impact caused by the collision of the raw material powder becomes gentler than the initial stage of film formation. As a result, oxygen defects are less likely to occur on the surface of the film 17, and other hues appear on the surface of the film 17.
Therefore, the inventor of the present application has arrived at the present invention in which the film thickness is observed in situ during AD film formation based on the color of the film surface.

The color measuring optical fiber 10 is arranged so that one end face (film-side end face) faces the film 17 on the substrate 16 and the other end face (device-side end face) is connected to the color measuring unit 11.
The color measurement unit 11 spectroscopically analyzes a light source (for example, a halogen light source) that generates light that irradiates a detection target via the color measurement optical fiber 10 and a device-side end surface of the color measurement optical fiber 10. And a determination unit for determining the color of the surface of the film 17 based on the intensity distribution of the spectral light.

  The light generated in the light source enters the device-side end face of the color measuring optical fiber 10, propagates through the color measuring optical fiber 10, and exits from the film-side end face toward the detection target. This light is reflected from the surface of the detection target and is incident on the film-side end surface, propagates again through the color measurement optical fiber 10 and enters the color measuring unit 11 from the device-side end surface. This incident light is split into a plurality of wavelength components in the spectroscopic unit.

FIG. 2 is a diagram for explaining the L ^* a ^* b ^* color system used for color determination in the color measurement unit 11. As shown in FIG. 2, the L ^* a ^* b ^* color system is composed of an a ^* axis and a b ^* axis that are orthogonal to each other, and an L ^* axis that is orthogonal to those axes and extends from the origin. . Of these, the L ^* axis indicates lightness, and L ^* = 0 is the darkest state (black), and L ^* = 100 is the brightest state (white). Further, tan (b ^* / a ^* ) represents a hue. The positive direction of the a ^* axis indicates the red direction, and the negative direction of the a ^* axis indicates the complementary green direction. On the other hand, the positive direction of b ^* axis represents the yellow direction, the negative direction of the b ^* axis represents blue direction which is the complementary color. In the color measurement unit 11, components on each axis are obtained based on a plurality of wavelength components of reflected light from the detection target.

Normally, a color measuring device including the color measuring optical fiber 10 and the measuring unit 11 is commercially available. As the color system, in addition to the L ^* a ^* b ^* color system, any of those used in the color design field such as the XYZ color system and the L ^* U ^* V ^* color system. The color system may be applied.

Referring again to FIG. 1, the film thickness calculation unit 12 calculates the thickness of the film 17 based on the color of the film 17 obtained by the color measurement unit 11. The film thickness calculation unit 12 stores a conversion table or a conversion formula for converting a component on each axis in the L ^* a ^* b ^* color system to a film thickness.
The conversion table is created, for example, by preparing multiple types of films with different film thicknesses as samples, and measuring the surface color (ie, L ^* axis, a ^* axis, b ^* axis values) and film thickness. Is done. The conversion formula is created by performing regression analysis or the like on the color (value of each axis) and film thickness of the film surface obtained in the same manner. Here, since the tendency of the color of the film surface to change changes depending on the film forming material and film forming conditions, the conversion table or the conversion formula is prepared according to such conditions. In each conversion table or conversion expression, all color system elements (for example, a ^* axis, b ^* axis, and L ^* axis values) may be used, or only one characteristic element (for example, , B ^* axis value only).

The display unit 13 displays the thickness of the film 17 calculated by the film thickness calculation unit 12 on the screen in real time.
The control unit 14 adjusts the moving speed of the substrate stage 8 so that the film 17 is formed at a desired rate based on the thickness of the film 17 calculated by the film thickness calculation unit 12, or the film 17 is desired. Each part is controlled so that the film formation is stopped when the thickness of the film is reached.

In such a film forming apparatus, the raw material powder 15 is disposed in the aerosol generation chamber 1, and the substrate 16 is disposed on the substrate stage 8. Examples of the raw material powder include inorganic piezoelectric materials such as PZT (lead zirconate titanate), heat-resistant materials such as MgO, high-strength materials such as Al ₂ O ₃ , magnetic materials such as Fe ₂ O ₃ , BaTiO _{3 and the} like. including a dielectric material, a semiconductor material such as ZrO _2, a conductive material such as IrO _2, optical material such as SiO _{2, as Al} 2 _{O 3} or an insulating material such as SiO _2, the moisture material such as _Al 2 _{O 3} or SiO ₂ Ceramic powder is used. When the film forming apparatus is driven, the aerosol generated in the aerosol generation chamber 1 is sprayed from the nozzle 7 and sprayed onto the substrate 16. Thereby, ceramics are deposited on the substrate 16 to form the film 17. While performing such a film forming operation, the color measuring optical fiber 10 and the measuring unit 11 measure the color of the surface of the film 17 on the spot, and the film thickness calculating unit 12 determines the color based on the color. The thickness of the film 17 is calculated. Then, when the thickness of the film 17 calculated by the film thickness calculation unit 12 reaches a desired value, the control unit 14 stops the film forming operation at each unit, thereby obtaining the film 17 having a desired thickness. It is done.

As described above, according to the present embodiment, film formation is performed while measuring the film thickness on the spot, so that the film thickness can be accurately controlled. Further, since an optical means is used at that time, the film thickness can be accurately grasped even if vibration occurs during the film formation.
In the present embodiment, the film-side end surface of the color measuring optical fiber 10 is disposed near the substrate 16, so that the raw material powder reflected from the substrate 16 adheres to the end surface, so It may be concerned that the amount of incident light is reduced. However, the film formation temperature in the AD method is not particularly limited, but is often performed at a temperature higher than room temperature (for example, about 200 ° C. to 800 ° C.). In this case, the end face of the optical fiber 10 is also heated, As a result, there is no problem because the raw material powder does not easily adhere to the end face. Alternatively, a mechanism for heating the vicinity of the end face of the optical fiber 10 may be provided separately.

  In the present embodiment described above, the color of the film 17 is determined by using the color system, but the film thickness is determined based on the shape of the spectral spectrum, that is, the peak wavelength in the spectral spectrum and the ratio of a plurality of wavelength components. May be determined. In that case, a conversion table or a conversion formula in which a peak wavelength value, a ratio of a plurality of wavelength components, and a film thickness are associated with each other may be stored in the film thickness calculation unit 12 in advance.

  Moreover, in this embodiment, although the display part 13 and the control part 14 are provided, you may provide only any one. For example, instead of performing automatic film thickness control by the control unit 14, the operator may manually control the film thickness while checking the film thickness displayed on the display unit 13.

  Furthermore, in the present embodiment, the aerosol is generated by rolling up the raw material powder arranged in the container with the gas, but the mechanism of the aerosol generation unit is not limited to such a configuration. That is, various configurations can be used as long as the raw material powder can be dispersed in the gas. For example, instead of introducing gas into a container (storage container) in which raw material powder is stored, a predetermined amount of raw material powder may be taken out from the storage container, and the extracted raw material powder may be aerosolized. Specifically, a raw material powder storage container, and a raw material powder supply unit (powder supply board) that continuously receives and feeds raw material powder at a predetermined rate (supply speed) from the storage container by being driven to rotate. ) And an aerosol generation unit (aerosolization unit) that generates an aerosol by dispersing the raw material powder conveyed by the raw material powder supply unit with a gas. In such a configuration, a stable amount of raw material powder can be supplied and the raw material powder supply unit can be rotated by forming a groove of a predetermined width into which the raw material powder is charged in the raw material powder supply unit. By adjusting the driving speed, the supply amount of the raw material powder can be controlled. An aerosol having a stable concentration can be generated by dispersing the raw material powder by introducing a gas at the destination of the raw material powder or by directly spraying the carrier gas into the groove of the powder supply board.

  Moreover, the raw material powder is stirred in the raw material container, and a predetermined amount of the raw material powder mixed with the compressed gas is taken out from the storage container by introducing the compressed gas into the storage container. The structure which disperse | distributes raw material powder | flour using expansion | swelling of compressed gas is also mentioned by discharging | emitting. Furthermore, a configuration in which the raw material powder is dispersed in the carrier gas by continuously supplying the raw material powder to the carrier gas flow path may be used.

Example 1
First, in order to create a table for converting the color of the film surface into the film thickness, the film thickness is varied under the following conditions using the film forming apparatus shown in FIG. Three types of films were formed.
Raw material powder: PNN-PZT powder (manufactured by Furuuchi Chemical Co., Ltd., average particle size: 1 μm)
Substrate: YSZ (yttria stabilized zirconia) substrate
(Nippon Fine Ceramics Co., Ltd.)
Substrate temperature: 400 ° C
Carrier gas: oxygen (O ₂ ) 6 liters / minute Pressure in film formation chamber: 50 Pa
Further, a color measuring device manufactured by Spectra Corp. was incorporated as the color measuring optical fiber 10 and the color measuring unit 11 shown in FIG.

  For the three types of films thus obtained, the color of the film surface immediately after film formation was measured in the film formation chamber 6. Thereafter, these films were taken out from the film forming chamber 6 and the film thicknesses were measured using a stylus type surface shape measuring instrument Dektak 6M manufactured by ULVAC, Inc.

Thereby, the following relationship was obtained between each value of the L ^* a ^* b ^* color system and the film thickness.
Average film thickness L ^* a ^* axis b ^* axis 1 μm 52.5 0.4 3.3
5 μm 59.3 -2.1 10.4
10 μm 63.2 -4.4 15.2
Of these results, the value of the b ^* axis increases as the film thickness increases, so it is considered that there is a significant correlation with the film thickness. This corresponds to the color of the film surface changing to yellow as the film thickness increases. Therefore, in this embodiment, as shown in FIG. 3, the relationship between the value of the b ^* axis and the film thickness is obtained, and conversion is performed by converting the desired film thickness into the value of the b ^* axis using the relationship. Created a table.

Next, as Example 1, the target film thickness is set to 10 μm, film formation is performed with reference to the b ^* -axis value calculated by the film thickness calculation unit 12, and the b ^* -axis value is set to 15. At that time, the film formation was stopped. Five such samples were prepared.
On the other hand, as Comparative Example 1, a film was formed by reciprocating the substrate stage 8 10 times without referring to the value of the b ^* axis. Here, the number of reciprocations is a value set to form the target film of 10 μm based on the formation of a film of about 1 μm per reciprocation in the preliminary experiment. Five such samples were prepared.

As a result, the following results were obtained.
Average film thickness Film thickness variation Example 1 10 μm ± 20%
Comparative Example 1 18 μm ± 50%

  From the above results, it was found that in the examples, by controlling the film thickness based on the color of the film surface, the desired film thickness can be obtained with high accuracy and the variation can be suppressed to a relatively small level. . On the other hand, in the comparative example, the film thickness variation was as large as ± 50%, and it was confirmed that it was difficult to obtain a desired film thickness.

Next, a film forming apparatus according to the second embodiment of the present invention will be described.
FIG. 4 is a schematic diagram showing a configuration of a film forming unit in the film forming apparatus according to the present embodiment. In addition, about the aerosol production | generation part, the structure shown in FIG. 1 may be used, and other aerosol production | generation mechanisms may be used as mentioned above.

  As shown in FIG. 4, the film forming apparatus according to the present embodiment includes a CCD instead of the color measurement optical fiber 10, the color measurement unit 11, the film thickness calculation unit 12, and the control unit 14 shown in FIG. 1. A camera 20, a display unit 21, a film thickness measurement unit 22, and a control unit 23 are included. An optically transparent window 24 is formed in the film forming chamber 6. Other configurations are the same as those shown in FIG.

  The CCD camera 20 is disposed outside the film forming chamber 6 and photographs the film 17 being formed through the window 24 in real time. As shown in FIG. 4, the CCD camera 20 may be arranged so as to be perpendicular to the side surface of the film 17, or face the side surface of the film 17 at a predetermined angle (for example, 45 degrees). It may be arranged. In the former case, the thickness of the film 17 can be measured with high accuracy. In the latter case, not only the thickness of the film 17 but also the surface state can be observed.

The display unit 21 displays the image of the film 17 taken by the CCD camera 20 on the screen in real time.
The film thickness measurement unit 22 measures the thickness of the film 17 based on the image of the film 17 displayed on the screen of the display unit 21. Specifically, the thickness of the film 17 displayed on the screen of the display unit 21 is measured with a scale, and the value is converted into an actual film thickness in consideration of the position, angle, and magnification of the CCD camera 20. . Note that the thickness of the film 17 measured by the film thickness measuring unit 22 may be displayed on the display unit 21.

  The control unit 23 adjusts the moving speed of the substrate stage 8 so that the film 17 is formed at a desired rate based on the thickness of the film 17 measured by the film thickness measuring unit 22, or the film 17 is desired. Each part is controlled so that the film formation is stopped when the thickness of the film is reached.

  Thus, according to the present embodiment, the CCD camera 20 is installed outside the film forming chamber 6 and the film 17 is observed from outside the chamber, so that there is no possibility that the raw material powder adheres to the film observation apparatus. . Thereby, the film 17 can be accurately observed over a long period of time, and the labor for maintenance of the observation apparatus can be saved.

  Here, in the present embodiment, there is a possibility that the raw material powder adheres to the inside of the window 24 and the window 24 becomes cloudy during film formation for a long time. Therefore, it is desirable to wipe the window 24 regularly by providing a wiper inside the window 24. Moreover, since it becomes difficult for raw material powder to adhere by heating the window 24, a heating mechanism may be provided for the window 24. Note that the film formation temperature in the AD method is not particularly limited, but is often performed at a temperature higher than room temperature (for example, about 200 ° C. to 800 ° C.). In that case, since the window 24 is also heated according to the temperature in the film forming chamber 6, an effect of suppressing the adhesion of the raw material powder can be obtained without providing a heating mechanism.

  In the present embodiment, the film thickness is automatically controlled by the control unit 23, but the operator displays the image of the film 17 taken by the CCD camera 20 and the film thickness obtained by the film thickness measurement unit 22. The film thickness may be manually controlled while checking on the screen of the unit 21.

(Example 2)
In the film forming apparatus shown in FIG. 4, a CCD camera 20 capable of obtaining a magnification of 100 times was installed at a position and an angle facing the side surfaces of the substrate 16 and the film 17 from the vertical direction. Further, a wiper was attached to the window 24 so that the field of view of the CCD camera 20 was not obstructed, and the raw material powder adhering to the window 24 was wiped by operating the wiper during film formation.
The film forming conditions such as the type of raw material powder and the flow rate of the carrier gas are the same as those in the first embodiment.

In Example 2, the target film thickness is set to 100 μm, film formation is performed while visually confirming the film thickness displayed on the screen of the display unit 21, and the film thickness is reached when the film thickness reaches 100 μm. The membrane was stopped. Five such samples were prepared.
On the other hand, as Comparative Example 2, a film was formed by reciprocating the substrate stage 8 100 times without observing the film thickness. Here, the number of reciprocations is a value set to form the target film of 100 μm based on the formation of a film of about 1 μm per reciprocation in the preliminary experiment. Five such samples were prepared.

The film thicknesses of the samples obtained in Example 2 and Comparative Example 2 were measured by using a stylus type surface shape measuring instrument Dektak 6M manufactured by ULVAC, Inc. As a result, the following results were obtained.
Average film thickness Variation in film thickness Example 2 98 μm ± 8%
Comparative Example 2 130 μm ± 40%

  From the above results, it was found that in the examples, by observing the film thickness on the spot, the desired film thickness can be obtained with high accuracy and the variation can be suppressed small. On the other hand, in the comparative example, the film thickness variation was as large as ± 40%, and it was confirmed that it was difficult to obtain a desired film thickness.

Next, a film forming apparatus according to a third embodiment of the present invention will be described.
FIG. 5 is a schematic diagram showing a configuration of a film forming unit in the film forming apparatus according to the present embodiment. In addition, about the aerosol production | generation part, the structure shown in FIG. 1 may be used, and other aerosol production | generation mechanisms may be used as mentioned above.

  As shown in FIG. 5, the film forming apparatus according to the present embodiment includes a laser level gauge 30 and a film thickness calculation instead of the color measurement unit 11, the film thickness calculation unit 12, and the control unit 14 shown in FIG. 1. The unit 31, the display unit 32, and the control unit 33 are included. Further, an optically transparent window 34 is formed in the film forming chamber 6. Other configurations are the same as those shown in FIG.

The laser level meter 30 is a displacement meter using the principle of confocal. Here, the principle of detection of displacement by the laser level gauge 30 will be described with reference to FIG.
As shown in FIG. 6, the laser step meter 30 includes a light source 40 such as a semiconductor laser, half mirrors 41 and 42, lenses 43 to 46 forming an optical system having a confocal point, a reflection mirror 47, and a CCD camera. 48, a pinhole plate 49, a light receiving element 50, an amplifier 51, a tuning fork 52, a tuning fork position detection sensor 53, and an amplifier 54. The lenses 43 and 45 are collimating lenses, and the lenses 44 and 46 are objective lenses.

  The laser beam emitted from the light source 40 is transmitted through the half mirrors 41 and 42, is transmitted through the lenses 43 to 46, is incident on the surface of the detection target 55, and is reflected there, thereby again passing through the lenses 46 to 43. Comes back through. A part of the laser light transmitted through the lens 43 is reflected by the half mirror 42 and enters the CCD camera 48 via the reflection mirror 47. The remaining laser beam is transmitted through the half mirror 42, and a part of the laser beam is reflected by the half mirror 41 and guided toward the pinhole plate 49.

  The objective lens 44 moves up and down at a predetermined cycle by the vibration of the tuning fork 52. Therefore, the position of the focal point formed by the lenses 43 to 46 changes in accordance with the period of the tuning fork 52. The tuning fork position detection sensor 53 detects the vibration of the tuning fork 52 and generates a detection signal. This detection signal is amplified by the amplifier 54 and output as a signal representing the position of the objective lens 44 (objective lens position signal).

  The CCD camera 48 is disposed at a position substantially corresponding to one focal point formed by the lenses 43 to 46. When another focal point formed by the lenses 43 to 46 coincides with the surface of the detection target 55, the diameter of the reflected light from the detection target 55 detected by the CCD camera 48 is the smallest and the resolution is the highest.

  The pinhole plate 49 is arranged so that the pinhole is aligned with the other focus when one focus formed by the lenses 43 to 46 is aligned with the surface of the detection target 55. That is, at that time, the reflected light from the detection target can pass through the pinhole. This light is detected by the light receiving element 50, amplified by the amplifier 51, and output.

  When reflected light from the detection target 55 enters the pinhole of the pinhole plate 49, a detection signal is output from the light receiving element 50. The timing at which this detection signal is generated is the timing at which one focus of the lenses 43 to 46 matches the surface of the detection target 55. Therefore, the position of the surface of the detection target 55 can be obtained by obtaining the position of the objective lens 44 at that time based on the objective lens position signal output from the amplifier 54. Alternatively, the position of the surface of the detection target 55 may be measured based on the reflected light image captured by the CCD camera 48 instead of the detection signal output from the light receiving element 50 or together with the detection signal.

  Referring again to FIG. 5, the film thickness calculation unit 31 calculates the film thickness based on the height of the surface of the film 17 measured by the laser level gauge 30. The film thickness is obtained, for example, by subtracting the current measurement result of the laser level difference meter 30 from the measurement result of the laser level difference level 30 in the initial state (zero film thickness).

The display unit 32 displays the thickness of the film 17 calculated by the film thickness calculation unit 31 on the screen in real time.
The control unit 33 adjusts the moving speed of the substrate stage 8 so that the film 17 is formed at a desired rate based on the thickness of the film 17 calculated by the film thickness calculation unit 31, or the film 17 is desired. Each part is controlled so that the film formation is stopped when the thickness of the film is reached.

  Thus, according to this embodiment, since the thickness of the film | membrane 17 is measured from the exterior of the film-forming chamber 6, there is no possibility that raw material powder will adhere to the film thickness measuring device. As a result, it is possible to accurately measure the thickness of the film 17 over a long period of time, and it is possible to save labor for maintenance of the measuring device.

Also in this embodiment, it is desirable to provide a wiper for wiping the raw material powder adhering to the inside of the window 34 or to suppress the adhesion of the raw material powder by heating the window 34.
Also in the present embodiment, instead of automatically controlling the film thickness by the control unit 33, the operator may manually control the film thickness while checking the film thickness displayed on the display unit. In that case, the control unit 33 may be omitted.

(Example 3)
In the film forming apparatus shown in FIG. 5, a high-precision laser focus type displacement measuring instrument LT-8100 manufactured by Keyence Corporation was attached as the laser level gauge 30. In addition, a wiper was attached to the window 34 so that the visibility of the laser level gauge 30 was not obstructed, and the wiper was operated during film formation, so that the raw material powder adhering to the window 34 was wiped off.
The film forming conditions such as the type of raw material powder and the flow rate of the carrier gas are the same as those in the first embodiment.

As Example 3, the target film thickness is set to 20 μm ± 20%, and film formation is performed while checking the film thickness calculated by the film thickness calculation unit 31 on the screen of the display unit 32, so that the film thickness becomes 20 μm. At that point, the film formation was stopped. Ten such samples were prepared.
On the other hand, as Comparative Example 3, a film was formed by reciprocating the substrate stage 8 20 times without measuring the film thickness. Here, the number of reciprocations is a value set to form the target film of 20 μm based on the formation of a film of about 1 μm per reciprocation in the preliminary experiment. Ten such samples were prepared.

The film thicknesses of the samples obtained in Example 3 and Comparative Example 3 were measured by using a stylus-type surface shape measuring instrument Dektak 6M manufactured by ULVAC, Inc. Then, evaluation was performed by counting the number of samples out of the target range (20 μm ± 20%). As a result, the following results were obtained.
Number of defective samples (/ total number)
Example 3 3 pieces (/ 10 pieces)
Comparative Example 3 8 pieces (/ 10 pieces)

  In Example 3, although the film was formed while wiping the window 34 with a wiper, the amount of reflection from the film was reduced due to contamination of the window 34, so it was difficult to perform high-precision measurement. . Therefore, three defective samples were generated. However, considering that most of the results of Comparative Example 3 were defective samples, it can be said that the results are good. From this, it was confirmed that the film thickness can be controlled by measuring the film thickness in situ during the film formation.

  The present invention is used in a film forming apparatus and a film forming method using an aerosol deposition method for forming a film containing the above raw material by spraying an aerosol in which the raw material powder is dispersed in a gas toward the substrate. Possible

It is a schematic diagram which shows the structure of the film-forming apparatus which concerns on the 1st Embodiment of this invention. It is a figure for demonstrating L ^* a ^* b ^* color system. b ^* is a diagram showing the relationship between the axis of the value and the film thickness. It is a schematic diagram which shows a part of film-forming apparatus which concerns on the 2nd Embodiment of this invention. It is a schematic diagram which shows a part of film-forming apparatus which concerns on the 3rd Embodiment of this invention. It is a figure for demonstrating the displacement detection principle in the displacement meter using the principle of a confocal.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Aerosol production | generation chamber 2 Shaking table 3 Hoisting gas nozzle 4 Pressure control gas nozzle 5 Aerosol conveyance pipe 6 Deposition chamber 7 Injection nozzle 8 Substrate stage 9 Exhaust pipe 10 Color measurement optical fiber 11 Color measurement part 12, 31 Film thickness calculation part 13, 21, 32 Display unit 14, 23, 33 Control unit 15 Raw material powder 16 Substrate 17 Film 20 CCD camera 22 Film thickness measurement unit 24, 34 Window 30 Laser step meter

Claims (21)

A film forming apparatus using an aerosol deposition method for forming a film by spraying and depositing raw material powder on a substrate,
Aerosol generating means for generating an aerosol by dispersing raw material powder with gas;
A deposition chamber;
A substrate stage disposed in the deposition chamber;
A nozzle for injecting an aerosol of the raw material powder generated by the aerosol generating means toward the substrate disposed on the substrate stage;
Measuring means for optically measuring the thickness of the film formed on the substrate in real time;
A film forming apparatus comprising:   The film forming apparatus according to claim 1, wherein the measuring unit measures the thickness of the film based on a spectral spectrum of a surface of the film formed on the substrate.   The film forming apparatus according to claim 2, wherein the measuring unit measures the thickness of the film by measuring the color of the surface of the film.   The film forming apparatus according to claim 3, wherein the measuring unit measures a color of the surface of the film and converts the color into a thickness of the film. The measuring means is
An optical fiber at least partially disposed in the film forming chamber, wherein the optical fiber causes light reflected from the surface of the film to be incident from the first end face and emitted from the second end face;
Means for measuring the color of light emitted from the second end face of the optical fiber based on a color system;
Having
The film forming apparatus according to claim 3 or 4. A window that transmits light is provided in a part of the film forming chamber,
The measurement means includes a camera for photographing the film through the window, and a display means for displaying an image of the film photographed by the camera.
The film forming apparatus according to claim 1.   The film forming apparatus according to claim 6, wherein the measuring unit further includes a unit that obtains the thickness of the film based on an image displayed on the display unit. A window that transmits light is provided in a part of the film forming chamber,
The measuring means is provided outside the film forming chamber, and measures the displacement of the film surface based on the optical path length of the light beam irradiated onto the film surface and reflected from the film surface. ,
The film forming apparatus according to claim 1.   The measurement means includes a light source that generates a light beam irradiated on the film, an optical system having a confocal point, and a detection means that detects a light beam reflected from the surface of the film and passed through the optical system. The film forming apparatus according to claim 8.   The film forming apparatus according to claim 6, further comprising a wiper that is provided on the window and wipes the window.   The film forming apparatus according to claim 5, further comprising means for heating at least the first end face of the optical fiber or the window.   The film forming apparatus according to claim 1, further comprising a control unit that stops film formation when the thickness of the film reaches a desired thickness. A film formation method by an aerosol deposition method in which a film is formed by spraying and depositing raw material powder on a substrate,
A step (a) of generating an aerosol by dispersing raw material powder with a gas;
The raw material powder is deposited on the substrate by spraying the aerosol of the raw material powder generated in step (a) toward the substrate while optically measuring the thickness of the film formed on the substrate in real time. Step (b), and
A film forming method comprising:   The film forming method according to claim 13, wherein step (b) includes measuring the thickness of the film based on a spectral spectrum of the surface of the film.   The film forming method according to claim 14, wherein step (b) includes measuring the color of the surface of the film.   The film forming method according to claim 15, wherein step (b) includes measuring a color of light reflected from the surface of the film based on a color system.   The film forming method according to claim 16, wherein the step (b) includes measuring the thickness of the film by converting the color of the surface of the film into the thickness of the film.   In step (b), the film is photographed from outside the film forming chamber using a camera through a window provided in a part of the film forming chamber, and the thickness of the film is measured based on the image. The film-forming method of Claim 13 including carrying out.   In step (b), the surface of the film is irradiated from the outside of the film forming chamber through a window provided in a part of the film forming chamber, and the optical path length of the light beam reflected from the surface of the film is set. The film-forming method of Claim 13 including measuring the displacement of the surface of the said film | membrane based on.   The film forming method according to claim 19, wherein step (b) includes measuring a displacement of the surface of the film based on a confocal principle. The film forming method according to claim 13, wherein the step (b) includes stopping the film formation when the thickness of the film reaches a desired thickness.