JP2009132944A - Method for forming film-deposited body by aerosol deposition method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for forming a dense film-deposited body which does not form any green compact even at the thickness exceeding 100 μm by an aerosol deposition method. <P>SOLUTION: Raw fine particles such as alumina are mixed with carrier gas to form aerosol, which is jetted from a nozzle 11 to a substrate 21 for deposition such as a quartz glass to perform the film deposition. The aerosol is jetted while changing the angle of incidence of the raw fine particles 13 in the aerosol when being jetted to the substrate 21 for deposition by a method of turning the substrate 21 or the like. Formation of any green compact is prevented, and a dense film-deposited body is formed. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for forming a thick film-formed body using an aerosol deposition method.

  In the aerosol deposition method (hereinafter referred to as AD method), a raw material composed of ceramic or metal fine particles having a particle size of several tens of nanometers to several μm is mixed with gas to form an aerosol, which is sprayed onto a substrate through a nozzle. Is a technology to form In recent years, the AD method has attracted attention as a method capable of forming a dense film having a crystal structure similar to that of fine particles as a raw material at a low substrate temperature and at a high film formation rate.

  A film forming apparatus using the AD method will be described with reference to FIG. FIG. 6 is a schematic diagram showing the basic configuration of the film forming apparatus. In the figure, 61 is a deposition substrate, 62 is an XY stage for moving the deposition substrate 61, 63 is a nozzle, 64 is a deposition chamber, 65 is a classifier, 66 is an aerosol generator, and 67 is a high-pressure gas supply source. , 68 is a mass flow controller, 69 is a pipeline, and arrows in the figure schematically show the substrate scanning direction. Raw material fine particles made of ceramics or metal are mixed with a carrier gas (not shown) supplied via a mass flow controller 68 inside the aerosol generator 66 to be aerosolized. The inside of the film forming chamber 64 is decompressed to about 50 Pa by a vacuum pump (not shown), and the raw material fine particles aerosolized by the gas flow generated by the differential pressure between this pressure and the pressure inside the aerosol generator 66. Is introduced into the film forming chamber 64 through the classifier 65, accelerated through the nozzle 63, and sprayed onto the film formation substrate 61. The raw material fine particles conveyed by the gas are accelerated to several hundred m / s by passing through a nozzle having a minute opening of 1 mm or less.

  The accelerated raw material fine particles collide with the deposition target substrate 61, and the kinetic energy is released at a stretch, so that a film is formed. However, even if all the kinetic energy of the accelerated raw material fine particles is spent on raising the temperature of the raw material fine particles that have collided with the substrate, the temperature is about an order of magnitude compared to the temperature necessary for sintering ceramics, for example. There are many unclear points about the mechanism by which a low and dense film body can be obtained. However, it is considered that the crushing generated at the time of substrate collision of raw material fine particles plays an important role in the film forming process. Note that “crushing of raw material fine particles” means both crushing of raw material fine particles that have come to the substrate and crushing of raw material fine particles that have already adhered to the substrate surface.

That is, in Japanese Patent Application Laid-Open No. 2003-73855, in the case of raw material fine particles made of a brittle material, the average particle diameter of the fine particles is 50 nm or more, and the shape thereof is an aspherical irregular shape, at least at one or more corners. It is disclosed that a dense film-formed body can be obtained as a result of having a shape having, because the impact force at the time of substrate collision is concentrated on the corner portion and the crushing of the raw material fine particles is promoted.
JP 2003-73855 A

  However, as a result of systematic examination for forming a film-forming body having a large film thickness by our AD method, although a film-forming body of about 10 to 20 μm is relatively easily formed, For example, it has been found that it is difficult to stably form a film-forming body having a film thickness exceeding 100 μm. That is, in the initial stage of film formation, in other words, in a state where the film thickness is as thin as about 20 μm or less, a dense film body is obtained, but as the film thickness increases, a dense film body is not formed, and the green compact is formed. It became clear that there was a problem that only

To solve the above problem,
The first means provided by the present invention include:
An aerosol deposition method in which raw material fine particles are mixed with a carrier gas to form an aerosol, and together with the carrier gas, the raw material fine particles are accelerated through a nozzle and sprayed toward the deposition target substrate surface to form a film-deposited body in a decompression chamber. A method of forming a film-forming body by an aerosol deposition method, wherein film formation is performed while changing an incident angle of raw material fine particles ejected from the nozzle onto a deposition surface of the deposition substrate. .
The second means provided by the present invention includes
In the first means, the change in the incident angle is continuous and periodic, and is a method of forming a film formation by an aerosol deposition method.

Furthermore, the third means provided by the present invention includes:
In the first means, the change in the incident angle is intermittent and periodic, and is a method of forming a film formation by an aerosol deposition method.

  As a result of observing the structure of the film formed by the AD method, which is a dense film formation in the initial stage of film formation and becomes a green compact as the film thickness increases, using an electron microscope, for example, as schematically illustrated in FIG. It became clear that it has an organization as shown. FIG. 7 is a schematic view schematically showing a cross-sectional structure of a film formed under a condition in which the carrier gas flow rate is constant, in which 71 is a substrate, 72 is a film-forming body layer, and 73 is a green compact layer. is there. That is, the structure of the film prepared under the condition that the carrier gas flow rate is constant and the substrate incident angle of the raw material fine particles substantially coincides with the normal direction of the surface of the substrate 71 is as shown in FIG. In 72, a dense film was formed, and the diameter of the particles constituting the film-forming body layer 72 was about 1/10 to 1/5 of the diameter of the raw material fine particles. On the other hand, in the green compact layer 73, as the distance from the substrate 71 increases (as the film thickness increases), the number and size of the voids increase, and the diameter of the particles constituting the green compact layer As a result, it was clarified that the particle size of the raw material fine particles finally became approximately the same. Further, the boundary between the film formation layer 72 and the green compact layer 73 is not clearly distinguishable, and it is also clear that the structural change from the film formation body layer to the green compact layer occurs continuously. became.

  From this observation result, the cause of the formation of the green compact layer 73 is that the raw material fine particles are crushed as the film thickness is increased (as described above, “crushing the raw material fine particles” is the crushing of the raw material fine particles themselves that have come to the substrate). It means that both the raw material fine particles already adhered to the substrate surface are not easily generated).

  On the other hand, the cause of the crushing of the raw material fine particles is an impact force accompanying the release of the kinetic energy of the raw material fine particles at the time of the substrate collision, and the kinetic energy of the raw material fine particles is determined by the substrate collision speed. By the way, since the substrate collision speed of the raw material fine particles is determined by the flow rate of the carrier gas, the substrate collision speed of the raw material fine particles is always constant when the film is formed under a condition where the carrier gas flow rate is constant. Sometimes the kinetic energy solved is also constant. Therefore, ideally, crushing of the raw material fine particles should occur regardless of the formed film thickness.

  However, as described above, as a result of observing the cross-sectional structure of the film formed by the AD method with an electron microscope, as the film thickness increases, the number and size of the voids both increase. It is assumed that such a phenomenon occurs.

  FIG. 8 is a diagram schematically showing the relationship between the pressure generated by the substrate collision of the raw material fine particles and the strain generated in the film forming body layer and the green compact layer. In general, pressure (stress) and strain, as shown in the figure, in a region where the pressure is small, the strain increases linearly with the pressure (in the figure, elastic deformation region), but then the pressure The amount of strain does not follow the rise, and eventually crushes (the crushing point in the figure). In the green compact layer, since there are many voids, it is easier to deform than a dense film-formed body layer, and it is considered that the elastic deformation region is wide. It is estimated that the critical pressure is also increasing. That is, if the pressure generated by the substrate collision of the raw material fine particles exceeds the critical pressure in the film formation layer, but lower than the critical pressure of the green compact layer, once the green compact layer is formed, the substrate is no longer The raw material fine particles adhering to the surface are not crushed, and the green compact layer continues to be formed.

  In order to prevent the formation of the green compact layer, the raw material fine particles adhering to the substrate surface or the fine particles that are not sufficiently crushed are removed. It will be necessary. In addition, uncrushed raw material fine particles or fine particles that are not sufficiently crushed are considered to have a low adhesion force to the substrate surface or a film formed on the substrate, and can be removed relatively easily. It is done.

  That is, the present invention focuses on the etching effect of raw material fine particles incident on the substrate described below, and forms a dense film formation while removing uncrushed raw material fine particles or fine particles that are not sufficiently crushed. It is.

  3 to 5 show the influence of the incident direction of the raw material fine particles, in other words, the incident angle.

  FIG. 3 a is a schematic diagram showing the relationship between the incident direction and the incident angle of the raw material fine particles, in which 31 is a substrate, 32 is a film formed, 33 is a nozzle, 34 is a nozzle opening, and 35 is a nozzle opening 34. It is the raw material fine particle injected from. FIG. 3b schematically shows the shape of the film-formed body formed for a fixed time with the substrate position fixed. In the figure, 36 is the shape of the film-forming body, 37 is a uniform film thickness line, and P is the point where the thickest point is projected onto the substrate. When the substrate 31 is fixed and the raw material fine particles are sprayed toward the substrate surface for a certain period of time, the raw material fine particles 35 are incident on the substrate with a certain degree of directional distribution. It becomes a mountain shape as shown in FIG. Here, the incident direction of the raw material fine particles means a direction parallel to a straight line connecting the point P and the center of the nozzle opening 34 and toward the point P from the nozzle opening 34. In general, it is understood as the direction shown by the arrow shown in FIG. 3a and the block arrow. Further, the substrate incident angle referred to here means the angle Θ formed by the normal direction of the substrate surface and the incident direction, as shown in FIG. 3A.

  FIG. 4 shows the relationship between the substrate incident angle and the film thickness of the film-formed body formed for a certain time. In the figure, the mark ● corresponds to the case where the carrier gas flow rate is small, and the symbol □ corresponds to the case where the carrier gas flow rate is large. In any case, the film thickness is standardized by the film thickness obtained when the film is formed at a substrate incident angle of 0 degree. As shown in the figure, when the substrate incident angle exceeds 20 degrees, the film thickness of the film-deposited body starts to decrease sharply, and when the carrier gas flow rate is small, the decrease amount is when the flow rate is large. Smaller than that. It is estimated that this is because the etching effect of particles incident on the substrate becomes obvious as the substrate incident angle increases.

  FIG. 5 shows the relationship between the amount of decrease in film thickness and the incident angle after the raw material fine particles are allowed to enter the substrate for a certain period of time after the film formation body having a constant film thickness is formed. As in FIG. 5, the mark ● corresponds to the case where the carrier gas flow rate is small, and the symbol □ corresponds to the case where the carrier gas flow rate is large. In the same figure, the film thickness reduction amount of 0 means both when the film thickness does not decrease and when the material fine particles incident on the substrate are deposited and the film thickness increases.

  As shown in the figure, when the carrier gas flow rate is large, the decrease in film thickness becomes apparent from the vicinity where the incident angle exceeds 25 degrees, whereas when the carrier gas flow rate is small, the incident angle is 40 degrees. The decrease in film thickness becomes apparent from around this point.

  From the above results, it is understood that in the AD method, the etching effect of the raw material fine particles can be controlled by appropriately selecting the substrate incident angle of the raw material fine particles and the carrier gas flow rate.

  That is, the present invention harmonizes the above-mentioned etching effect and deposition effect by forming the film while changing the substrate incident angle of the raw material fine particles ejected from the nozzle, and becomes a source of forming the green compact layer. While removing uncrushed raw material fine particles adhering to the substrate surface, or fine particles that are not sufficiently crushed, a film having a large film thickness and excellent denseness is formed.

  According to the present invention, it is possible to stably form a thick film-formed body having a thickness of ultra 100 μm using the AD method.

Embodiments of the present invention will be described below.
1 and 2 are schematic views showing an embodiment of the present invention.

  FIG. 1 is a diagram schematically showing how the angle between the nozzle and the substrate changes during film formation. In the figure, 11 is a nozzle, and 13 is raw material fine particles ejected from the first nozzle. In addition, the arrows and block arrows in the figure indicate the incident direction of the raw material fine particles 13 to the substrate, and (1), (2), (3), and (4) are added to the block arrows to indicate the order in which the substrates rotate. It is a thing. That is, at the start of film formation, as shown in FIG. 1a, the raw material fine particles 13 are incident from a direction substantially orthogonal to the film formation surface of the substrate 21, and film formation is performed for a certain time. Thereafter, the substrate 21 rotates clockwise and stops when a desired angle is reached, and film formation is performed for a certain time in this state (corresponding to FIG. 1b). After that, the substrate 21 is rotated again counterclockwise, is stationary in the state shown in FIG. 1a, and film formation is performed for a certain time. Thereafter, the substrate 21 rotates counterclockwise, stops when reaching a desired angle, and film formation is performed for a certain time in this state (corresponding to FIG. 1c). Thereafter, the substrate 21 rotates again in the clockwise direction, stops in the state shown in FIG. 1a, and film formation is performed for a certain time. By repeating the above cycle, the film formation is formed. FIG. 2 shows the state as the relationship between the film formation time and the incident angle of the raw material fine particles 13. In the figure, “0” corresponds to the case of FIG. 1 a in which the raw material fine particles are incident on the substrate from the direction orthogonal to the substrate surface, and the positive and negative maximum corresponds to, for example, the cases of FIG. 1 b and FIG. FIG. 2a shows the case where the substrate incident angle changes intermittently, and FIG. 2b shows the case where the same angle changes continuously. In particular, in the case of FIG. 2a, the film formation may be continued or interrupted while the substrate rotates.

  Thus, by rotating the substrate during the film formation, the substrate incident angle of the raw material fine particles 13 is changed, and the state in which the film is preferentially deposited and the state in which the etching effect is manifested are alternately repeated. As a result, a film is formed while removing uncrushed raw material fine particles adhering to the surface of the film formation body or particles that are not sufficiently crushed, so that formation of a green compact is prevented and a dense film formation body is formed. Will be. Here, “the etching effect is manifested” means not only the case where the film is not deposited at all, but only the case where etching occurs, but also the case where the deposition rate starts to decrease. Which region is selected as the maximum or minimum value of the substrate incident angle, in other words, the film is not deposited at all, and the angle at which only etching occurs is selected, or etching occurs, but the film is still Whether to select the angle at which the deposition is also generated should be selected as appropriate depending on the kind of raw material fine particles or the ease of generation of the green compact.

  Hereinafter, embodiments of the present invention will be described in more detail using examples.

Comparative example

Film formation was performed using alumina particles having an average particle size of 0.7 μm as raw material fine particles and air as a carrier gas. The nozzle opening of the nozzle is 5 nm × 0.3 nm, and the substrate used is quartz glass. When the carrier gas flow rate is 4 l / min, the substrate collision speed of the alumina fine particles injected from the nozzle at this time is 240 m / s, and when the substrate incident angle of the alumina fine particles is 0 degree, the deposition speed is 10 μm / min. Met.
As a result of film formation under the same conditions, the formation of a green compact was remarkably observed around the film thickness exceeding 30 μm, and a film formed with a film thickness exceeding 100 μm could not be formed.

  As in the comparative example, film formation was performed using alumina particles having an average particle diameter of 0.7 μm as raw material fine particles and air as a carrier gas. The nozzle opening of the nozzle is 5 nm × 0.3 nm, and the substrate used is quartz glass. The carrier gas flow rate is 4 l / min. At this time, the substrate collision speed of the alumina fine particles injected from the nozzle is 240 m / s, and when the substrate incident angle of the alumina fine particles is 0 degree, the deposition speed is 10 μm / min. When the angle was 25 degrees, it was 7 μm / min.

  The substrate incident angle at the start of film formation was set to 0 degree, and the substrate incident angle was changed in the manner shown in FIG. 2a. That is, the substrate incident angle is kept at 0 degree, the film is formed for 2 minutes, the substrate incident angle is set to 25 degrees, the film is similarly formed for 2 minutes, and then the substrate incident angle is set to 0 degree again. A cycle of film formation for 2 minutes was repeated to form a 130 μm thick alumina film. The time required for changing the incident angle was about 10 seconds.

  A 110 μm-thick alumina film was formed under the same conditions as in Example 1. However, the substrate incident angle was changed to a sine wave shape as shown in FIG. The amplitude was 30 degrees (in this case the deposition rate was 5 μm / min) and the period was 3 minutes.

  The film-forming method according to the present invention is useful for forming a film-forming body having a thickness exceeding 100 μm using the AD method, and can be used in the industrial field related to parts and materials using the film-forming body. It is.

It is the figure which showed typically the mode of the change of the substrate incident angle at the time of film-forming. It is a schematic diagram which shows the relationship between film-forming time and a substrate incident angle. It is a schematic diagram for demonstrating a substrate incident angle. It is a figure which shows the relationship between the film thickness of a film-forming body, and a substrate incident angle. It is a figure which shows the relationship between a film thickness reduction amount and a substrate incident angle. It is the schematic which showed the basic composition of the film-forming apparatus using AD method. It is the schematic which showed typically the cross-sectional structure | tissue of the sample formed by AD method. It is the figure which showed typically the relationship between the pressure which generate | occur | produces by the board | substrate collision of raw material fine particles, and the distortion which generate | occur | produces in a film-forming body layer and a green compact layer.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Nozzle 13 Raw material fine particle ejected from nozzle 31 Substrate 32 Film formed 33 Nozzle 34 Nozzle opening 35 Raw material fine particle ejected from nozzle opening 44 36 Form of film forming body 37 Equivalent film thickness 61 Deposited film Substrate 62 XY stage 63 Nozzle 64 Deposition chamber 65 Classifier 66 Aerosol generator 67 High-pressure gas supply source 68 Mass flow controller 69 Pipeline 71 Substrate 72 Deposition body layer 73 Green compact layer P Projected point

Claims (3)

  An aerosol deposition method in which raw material fine particles are mixed with a carrier gas to form an aerosol, and together with the carrier gas, the raw material fine particles are accelerated through a nozzle and sprayed toward the surface of the substrate to be deposited to form a film formation in a decompression chamber. A method for forming a film-forming body by an aerosol deposition method, wherein film formation is performed while changing an incident angle of raw material fine particles ejected from the nozzle onto a deposition surface of the deposition substrate.   2. The method of forming a film-forming body by an aerosol deposition method according to claim 1, wherein the change in the incident angle is continuous and periodic.   2. The method of forming a film-forming body by an aerosol deposition method according to claim 1, wherein the change in the incident angle is intermittent and periodic.

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