JPH0638912B2 - Method and apparatus for producing fine particles - Google Patents

Description

TECHNICAL FIELD The present invention relates to improvements in a method and an apparatus for producing fine particles represented by ceramic fine particles by a gas reaction using laser light as a heat source.

[Prior Art] Due to the rise of various so-called fine ceramic technologies, the particle size of each is as small as sub-micron or less, and each particle size is very smiling and the spherical shape is good. Ceramic fine particles having a small variation in particle size and high purity have begun to be demanded.

Therefore, various fine particle manufacturing techniques have been developed in the past to satisfy all of these many demands. Among them, as a conventional example which belongs to the relatively successful category, a document published in 1982 was cited. : “Journal of the American Ce
“Sinterable Ceram” in ramic Society; Vol.65, No.7 ”
There is a gas-phase reaction type using laser light disclosed by Cannon et al. in the title of "ic Powders from Laser-Driven Reactions: I".

Here, the energy “hν” of the laser light is used as a notation to indicate that the laser light is involved in the reaction, and unnecessary hydrogen gas and the like generated as a result of the gas phase reaction are omitted for simplicity. In summary, in this document,
The following particle formation relationship is disclosed.

SiH ₄ + hν → Si SiH ₄ + NH ₃ + hν → Si ₃ N ₄ SiH ₄ + C ₂ H ₄ + hν → SiC SiH ₄ + CH ₄ + hν → SiC …… And, in the same literature, such a reaction As a device for causing it to occur, a configuration as shown in FIG. 7 is schematically shown.

To explain this, a parallel laser beam 51 from a laser light source 50 is used as a heat source for causing a gas phase reaction, and this is introduced into a reaction chamber 52 kept at an appropriate vacuum degree. At this time, a window 53 made of KCl is provided at the introduction portion of the laser beam so as not to break the hermeticity inside the reaction chamber 52.

The raw material gas component G _r in the above equation is also introduced into the reaction chamber 52 in the same manner.
It is supplied so as to cross the beam due to the relationship orthogonal to 51, and in practice, the structure of this source gas introduction part is a characteristic part of this conventional example.

That is, by traversing the laser beam 51, a portion (hereinafter, referred to as a portion where thermal energy is generated and a gas phase reaction occurs)
Designations to) the reaction section 58, for reasons described below, to limit the limited volume region, the raw material gas G _r in the reaction chamber 52
While a small-diameter nozzle 54 is used to introduce, the outer circumference of this nozzle 54 is concentrically surrounded by an outer cylinder pipe 55.
An inert gas G _i such as argon is supplied into the 55.

In other words, in this conventional example, by the inert gas G _i , a donut-shaped barrier which is not visible as a tangible member, but which is not visible to the eye, is constructed, and only in the central hole portion of the donut-shaped barrier, By restraining the raw material gas G _r , the substantial volume of the reaction part 58 is restricted.

After doing so, the fine particles generated in the reaction part 58 are
Generally, in order to maintain an appropriate degree of vacuum in the reaction chamber 52, the reaction chamber 52 is sucked out from an outlet 56 which also serves as an intake pipe connected to a suction mechanism (not shown), which is also not shown but is adsorbed by an appropriate filter. , It is taken out as a product after each step.

Further, in the case of this conventional example, the parallel laser beam 51 is incident on the laser energy absorber 57 having a water-cooled copper plate structure, is absorbed there, and is irradiated with laser energy to other structures, thereby damaging the influence. The fear that it might give is eliminated.

[Problems to be Solved by the Invention] In the above-mentioned conventional documents, as described above, the inert gas is used.
G _i surrounds the reaction gas (raw material gas) G _r and tries to cross the laser beam 51 while maintaining a small diameter.

However, according to the document, the reaction part 58 can be limited to a narrow area and the laser beam 51 can be used.
On the other hand, it is said that it was possible to obtain a steep temperature gradient by suddenly putting in and out, and as a result, 10-100 nm
It is described that it succeeded in obtaining ceramic fine particles with little variation within a particle size range of a certain degree.

In addition, the reason why the laser beam is used as the heating source is that the radiation efficiency is good, the spectrum range is narrow, and the wavelength band that can be well absorbed in the raw material gas can be selected, and in the end, high efficiency can be achieved. Therefore, for the source gas G _r shown in the above equation, the carbon dioxide laser is considered to be the most suitable in view of its wavelength.

Certainly, the use of a laser beam is an advantageous judgment, not limited to the above carbon dioxide gas laser. This is because the design is good and the optimum wavelength range can be effectively used due to the narrow spectral characteristics.

On the other hand, it must be a very desirable consideration to limit the reaction part 58 to a narrow region (volume region), as the purpose of the above document. This is because the narrower the limit, the higher the efficiency can be obtained even with a low laser energy, and the less room for impurities to enter, and the higher the purity can be achieved.

However, when the above-mentioned conventional example was examined, it was found that satisfactory results were not necessarily obtained as described in the document. Although it was visible, there was considerable variation in the particle size, and I could not wipe out the feeling that there was still room for improvement.

Therefore, the present inventor further conducted a study to investigate the cause, but the progress and findings were, in short,
The inert gas G _i to form a donut-shaped barrier that completely confine the raw material gas G _r in this, there is a defect in the first place the characteristic portion of this conventional method, the raw material gas G _r with inert gas G _i The confinement function of is not perfect, and in fact, the raw material gas G _r has spread so as to enter the inert gas G. It was also confirmed that the extent and distribution of the spread were not always uniform and the reproducibility was poor.

That is, in the above-mentioned conventional literature, the aim of narrowing the reaction section was good, but it left a problem in the concept of the method for realizing this and the device configuration.

The present invention has been made from this point of view, and provides a method and an apparatus for producing fine particles based on a new idea so that the principle of limiting the reaction part to a narrow confined space part can be realized as it is. To do.

[Means for Solving the Problems] In the present invention, it is common to use an inert gas for sweeping the generated fine particles from the reaction gas in the field for practicing the present invention or in the apparatus for practicing the present invention. However, as in the past, indeterminate factors such as confining the raw material gas with this inert gas are rejected, and at least physical and mechanical shapes are required for the geometrical limitation of the reaction blow. A certain "wall" member is intended to create a space which is at least immovably confined in some direction of the wall.

To restate this idea as the basic configuration of the present invention, it is as follows.

First, the space enclosed by the tangible wall as above
At least one axial through hole is formed in a linear shape, and a laser beam is passed through the through hole from one end side toward the other end side in the axial direction.

In other words, a through hole forming member having linear through holes opened at both ends in the axial direction is prepared, and the through hole forming member is arranged in the reaction chamber and is provided outside the reaction chamber through an appropriate window member. A laser beam from the inside of the through hole.

Then, the tip of the raw material gas supply path provided so as to penetrate the through hole forming member is opened in a part of the inner wall surface of the through hole so that the raw material gas is directly injected into the through hole. To do.

That is, the raw material gas is surely transported to the position near or in contact with the laser beam, and the presence of the inner wall surface of the through hole assists the spatial expansion of the raw material gas.

Although this is the basic configuration of the present invention, preferably the above-mentioned through hole diameter is within a range through which the laser beam can pass, and also within a range in which the generated fine particles are unlikely to be clogged within at least an excessively short time. , Make it thin enough.

Of course, the other end of the raw material gas may be linked to a raw material gas supply source outside the reaction chamber, if necessary, together with an appropriate sealing means, as seen in the conventional technique of utilizing a vacuum reaction chamber of this kind. The means for maintaining the inside of the reaction chamber at an appropriate degree of vacuum, the filter means for adsorbing the generated fine particles, and the like may be the same as those found in the above-mentioned conventional example.

Further, in the present invention, the raw material gas supply passage for passing through the through hole forming member is simply provided in the direction orthogonal to the optical axis of the laser beam passing through the through hole under the above-mentioned basic structure. Instead, a configuration in which it is provided diagonally is also proposed.

It may be slanted so as to face the opposite direction to the traveling direction of the laser beam, but it is preferably slanted along the traveling direction of the laser beam.

Similarly, the geometric shape of the entrance of the through hole where the laser beam is incident is also taken into consideration, and the diameter of the laser beam may be thicker at the entrance of the through hole than the diameter of the through hole. Also, the tapered entrance surface reflects the laser beam and directs the inside of the through hole in the forward direction. In that sense, the inclination angle of the tapered surface with respect to the optical axis of the laser beam is preferably 45 ° or less, and optimally about 30 °.

Further, a structure in which the raw material gas supply paths are opposed to each other in the radial direction and provided in a plurality of pairs or more is also proposed, and as described above, also in this case, not only from the direction orthogonal to the through hole through which the laser beam passes, It is also possible to adopt a configuration that is provided from an oblique direction.

Further, when the through-hole forming member is viewed from the front, the raw material gas flow supplied through the opening of the raw material gas supply path is not ejected toward the central axis of the through hole, but is directed to the central axis. It is also proposed to inject the fluid toward the off-set position and form a vortex inside the through hole.

And finally, in any of the above cases, the laser
Apply a converging lens system to the beam so that the beam has a focal point with an appropriate diameter at one point in the length direction in the through hole, and is slightly off toward this focal point or in the plane containing the focal point. -It is also proposed to provide a feed passage opening so that the raw material gas flow is fed toward the set position.

Conversely speaking, it is not limited to parallel beams as in the past,
Rather, a convergent beam is preferably used.

[Operation and Effect] In the present invention, as described above, the through-hole forming member having the through-hole that is closed by the tangible wall and has an opening only in the uniaxial direction is used, and the gas reaction is not promoted in the through-hole. In addition to passing a laser beam as a heat energy source to assist, the tip of the feed passage of the raw material gas is opened on the inner wall surface of the through hole that closes the circumferential direction of the through hole, so that the raw material gas flow If the portion where the laser beam collides is the gas phase reaction part for producing fine particles, in the present invention, the raw material gas can be injected in the immediate vicinity of the reaction part or directly into the reaction part. In addition to being able to suppress the spread, the inner wall surface of the through hole also assists the physical space limitation function, so that the reaction portion can be substantially limited to a very limited volume region.

In this way, as the most basic effect of the present invention,
The reaction efficiency is limited to an extremely narrow volume region, and unlike the conventional example, there is no fluctuation factor, and it is possible to obtain a reaction part that is mechanically limited to a substantially constant volume, so the utilization efficiency of the thermal energy of the laser beam is extremely high. In addition to the effect of increasing, the following effects can be obtained.

By changing the position of the through-hole forming member, the spatial alignment operation of the laser beam and the reaction section is simple and reliable. Even when the optical axis of the laser beam is adjusted, the reaction part is inside the through hole and the adjustment work can be performed while looking at the one end opening part of the through hole, so the workability can be improved. . If the alignment is accurate,
Naturally, the reaction efficiency is also improved.

Since the reaction part cross-sectional area as viewed in the cross-sectional direction of the raw material gas can be arbitrarily set with good designability by adjusting the cross-sectional area of the raw material gas supply passage passing through the through hole forming member and the through hole diameter,
The optimum reaction part volume can be set with good reproducibility, which also contributes to the improvement of reaction efficiency. The cross-sectional area of the through hole is
As a general rule, the narrower the laser beam is and the sharper the laser beam is, the higher the efficiency is. However, since clogging is likely to occur, the optimum diameter range can be determined by a trade-off between the two.

For the above reasons, the unreacted components are extremely reduced, so that high purification is achieved.

To put it higher efficiency, the finer particles can be obtained with the same degree of efficiency even with a laser beam having a smaller power than in the past.

Further, in the present invention, the raw material gas supply passage for passing through the through-hole forming member is simply provided in the direction orthogonal to the traveling direction of the laser beam passing through the through-hole under the above-mentioned basic structure. Instead, it proposes a configuration in which it is provided obliquely.

In particular, when the laser beam is inclined along the traveling direction of the laser beam, the following effects can be further obtained while maintaining the condition that the reaction portion is narrow and limited in designability and reproducibility as described above.

The energy of the laser beam can be effectively used.

The generated fine particles can be swept out quickly from the through holes. Even when an inert gas is used for scavenging, its function can be honed.

Also, by adopting a through hole inlet and taper structure, the degree of inclination of the tapered surface with respect to the optical axis is preferably 45 ° or less, and most preferably 30 °.
Even if the laser beam is reflected here, the reflected light will be directed to the inside of the through hole, and thus the above effect will be further reinforced, and the light will not be slightly misaligned. Even with axis misalignment, this may be acceptable.

Further, if a plurality of source gas supply paths are provided so as to face each other in the radial direction with respect to the laser beam or the through hole, and a plurality of them are provided,
When these plural source gas supply passages are provided from the orthogonal direction, the following effects can be obtained in addition to the above-mentioned effects, and when they are provided from an oblique direction, in addition to the above-described effects.

Since the raw material gases collide with each other in the reaction section, the raw material gas can be concentrated in the central portion of the laser beam,
It is possible to achieve higher efficiency and higher purity.

In addition to these, according to a further feature of the present invention, when the through hole forming member is viewed from the front, the raw material gas flow supplied through the opening of the raw material gas supply passage is ejected toward the central axis of the through hole. However, if a structure is adopted in which the gas is injected toward an off-set position with respect to the center axis, a vortex flow can be generated in the reaction section, and therefore, the source gas to be used and the generation conditions can be changed. Depending on how the raw material gas can be circulated in the reaction part for a long time, high efficiency and high purification can be further promoted.

Finally, as a consideration for the laser beam, in any of the above cases, the laser beam is focused by using a converging lens system or the like so that a focal point of a desired diameter is generated at one point in the through hole length direction. If a feed passage opening is provided so that the raw material gas flow is fed from the orthogonal direction or the oblique direction toward this focus or toward a position slightly set off in the plane including the focus, The partial effect and the effective use of the laser beam are maximized.

In other words, since the laser beam is focused and focused, the energy density at the focal point becomes extremely large. On the other hand, if necessary, even for the reaction part that can be converged to almost one point, According to the above-described configuration of the present invention, the raw material gas can be injected with high positioning accuracy, and therefore the above-described effects of high efficiency and high purification are maximized.

However, of course, the degree of convergence, that is, how to set the focal diameter is a matter of arbitrary design.

[Examples] The method and apparatus for producing fine particles of the present invention, which can expect various effects as described above, will be further understood through the following examples.

To put it in advance, the fine particles to which the present invention is applied are not limited to the fine particles having a ceramic diameter as found in the above-mentioned conventional example, but for convenience, the energy notation “hν” of the laser beam used is used. As in the above equation, if the laser beam is involved in the gas phase reaction, it is preferable to use the method and apparatus of the present invention for the reaction relation represented by the following equation. You can

SiH ₄ + hν → Si SiH ₄ + NH ₃ + hν → Si ₃ N ₄ SiH ₄ + C ₂ H ₄ + hν → SiC SiH ₄ + C ₄ + hν → SiC TiCl ₄ + NH ₃ + hν → TiN TiI ₄ + CH ₄ + hν → TiC ZrCl ₄ + NH ₃ + hν → ZrN .. As an apparatus configuration example suitable for carrying out the present invention, first, its outline is shown in FIG. 1 and explained. The reaction chamber 12 that is generally isolated from the surrounding environment such as the vacuum gas environment and the source gas species and the gas phase reaction relationship is shown in FIGS. 2 to 6 in accordance with the concept of the present invention. A through hole forming member 20 that can take various forms is stored.

In other words, the through-hole forming member 20 shown in the first drawing is also the simplest one corresponding to FIG. 2 among the through-hole forming member configurations that can take various forms in consideration of convenience for simplifying the drawing. However, it is possible to replace it with the one shown in FIGS. 3 to 6. Details will be given later individually.

The through-hole forming member 20 has a linear through-hole 21 with both ends open, but in this case, in the illustrated case, a parallel laser emitted from the laser light source 10 provided outside the reaction chamber 12 is emitted. The beam 11 is preferably passed through a laser beam 11 'which is converged by a converging lens system (only a single convex lens is shown, but it may have a plurality of lens configurations) 23, and this through hole is used. The convergent laser beam 11 'exiting 21 enters the laser energy absorber 17 made of a carbon plate in the experimental apparatus of the present inventor, and is absorbed there.

The laser energy absorber 17 is not limited to the above-mentioned material, and as in the above-mentioned conventional example, a water-cooled steel plate type or any other suitable form proposed in this type of laser energy absorption technology can be used. Can be adopted,
At the very least, if such a laser energy absorbing member is provided, as will become apparent later, the laser beam
It is possible to avoid in advance a possibility that the component 11 'may be damaged by accidentally entering some component member in a portion other than the reaction portion 18 in the through hole which should perform the original function.

Further, in the case shown in the figure, on the wall surface of the reaction chamber behind the lens system 23 for converging the parallel laser beam 11, there is provided a window 13 made of an appropriate material such as KC1 for maintaining a vacuum of the internal environment. Even if the window 13 or the lens system 23 is damaged, leakage of the raw material gas G _r is prevented.

However, the focused laser beam 11 'is
f _o is positioned at one point in the length direction of the through hole 21, and the diameter of the focus can be set to a desired spot diameter depending on the design of the lens system, the positional relationship with the laser light source 10, and the like. .

When referred to as the raw material gas G _r collectively gas group shown in the left term in the formula, the reaction chamber the raw material gas G _r from the source of the raw material gas G _r that is provided outside the reaction chamber 12 The raw material gas supply path 14 leading to the inside of the reaction chamber 12 may be subjected to a piping process known in this type of reaction chamber utilization technique until it enters the inside of the reaction chamber, but the characteristic feature of the present invention is that it enters the reaction chamber. The raw material gas supply path 14 after being penetrated further penetrates the thick portion of the through hole forming member 20, and the tip thereof is opened to the inner wall surface of the through hole 21, particularly as shown in the illustrated embodiment. in the case of using a 11 'converging beam to the laser beam, it is in this way opening 22 comes to face the above-mentioned focus f _o.

However, this is reversed, so that the most recently focus f _o of the opening 22 of the raw material gas supply passage 14 comes, may be positioned towards the laser optical system, rather, the person is usually. This is because it is extremely troublesome to make a mechanism for finely adjusting the position of the through hole forming member 20 in the reaction chamber (although this is not the case).

In any case, with the above configuration, the source gas G _r is transported to a position in the immediate vicinity of or directly in contact with the laser beam 11 ′, where it is released all at once, and the The phase reaction part 18 is limited to a very narrow space area.

More specifically, in the present invention, as described above, a perforation forming member 20 having a perforation 21 that is closed by a tangible wall and has an opening 21 that is open only in one axial direction is used. A laser beam 11 'serving as a heat energy source that promotes or assists the reaction is passed, and a feed gas tip opening 22 for the source gas is opened on the inner wall surface of the through hole 21 which is closed in the circumferential direction. Therefore, if the part where the raw material gas flow and the laser beam collide is defined as the gas reaction part 18 for producing fine particles, the raw material gas G _r is provided in the immediate vicinity of the reaction part 18 or directly to the reaction part 18. It is possible to inject and suppress the spread of the raw material gas G _r , while at the same time, the inner wall surface of the through hole also assists physically and stably with a space limiting function, so that the reaction part 18 is substantially limited. It can be limited to the volumetric area.

In this embodiment, the composition of fine particles that can be generated in the through holes 21 is expelled from the through holes 21 and solidified to obtain desired fine particles, so that a suitable inert gas such as argon is used as a transport gas or a scavenging gas. Since the use of G _i is considered, the supply path 25 for introducing this inert gas G _i is
It is possible to enter the reaction chamber 12 beyond the wall of 12 and release the inert gas G _i through the protective nozzle 25 of the window 13.

Further, in the middle of the passage from the outlet 16 connected to an appropriate intake source (suction pump or the like) not shown, this is not shown either, but as described in connection with the prior art, it is appropriate. The filter means is inserted to capture the produced fine particles, and the fine particles as a product can be obtained by taking out the filter means at the end of each unit process having an appropriate time width as one process. can do. Of course, the installation position of the filter means is a matter of arbitrary design, and the filter means may be detachably provided at a position different from the intake passage.

Further, the aluminum (Al) plate 19 provided in the middle of the path from the through hole forming member 20 to the outlet 16 adsorbs solid matter generated during the gas phase reaction and enhances the particle recovery rate.

Now, regarding the constitutional example or the form example of the through hole forming member 20 which is representatively shown in FIG. 1, various concrete examples are given in a little more detail. First, it is considered to be the most basic. Is the one shown in the second illustration.

The second illustrated through hole forming member 20 with respect to straight holes 21, one of the raw material gas supply path 14 is arranged in an orthogonal relationship, the focus f _o of the opening 22 converges laser beam 11 ' Facing. Therefore, in this case, the focal point f _o or its vicinity can be defined as the reaction part 18.

Next to the focused laser beam code 11 ', there is also a code 11 without the dashes, which is simply the code of the parallel laser beam, but this is certainly the best way to focus the laser beam 11. Although desired, but not limited to, the parallel laser beam 11 (first
This is because it is shown that at least the basic effects of the present invention can be exerted even if they are left as they are.

Therefore, hereinafter, although not specifically shown in this point in the drawings from FIG. 3 to FIG. 6, it should be considered as including such consideration. In this case, of course, the convergent lens system 23 is in principle unnecessary.

On the other hand, in the through hole forming member 20 shown in FIG. 2, the entrance and exit portions of the through hole 21 are tapered, but in particular, the tapered surface 24 at the entrance portion may be used efficiently depending on the laser beam. Acts to further increase.

This means that the diameter of the laser beam at the entrance of the through hole 21 may be somewhat larger than the diameter of the through hole 21 that is designed and fixed, or the through hole axis and the laser -If there is a slight misalignment with the beam optical axis, and if the through-hole entrance is a raised surface, the cross-section portion protruding from the through-hole area area of the laser beam will be reflected at this through-hole entrance. However, if it is tapered,
This is because it can be introduced into the through hole and participate in the reaction through a structure such that it is reflected inward and is again reflected by the tapered surfaces 24 facing each other in the radial direction.

For that purpose, as shown in FIG. 4 which will be described later, the inclination angle θ _t of the reflecting tapered surface 24 with respect to the laser beam is desirably 45 ° or less, preferably 30 °. It is a degree. This point is also described later in the third to sixth aspects.
The same applies to the illustrated embodiment.

However, first, even when the through hole forming member 20 according to the second illustrated embodiment is used, the most basic effect of the present invention is that it is limited to an extremely narrow volume region, and there are fluctuation factors like the conventional example. Therefore, it is possible to obtain the reaction section 18 which is mechanically always limited to a substantially constant volume. For this,
As described above in the section of the action and effect of the present invention, the ripple effect thereof is included and the effect is described.

The hole forming member 20 according to an embodiment of the third illustrated, compared to that of the second illustrated, the raw material gas supply passage 14 has become a two, with respect to the reaction unit 18 to focus f _o in the hole 21, The raw material gas G _r can be blown out from a pair of openings 22, 22 that are opened at positions facing each other in the radial direction.

Therefore, as described above, since the raw material gases collide with each other in the reaction part 18, the raw material gas is laser
Can concentrate on the central portion to the focal part f _o of the beam,
It is possible to achieve higher efficiency and higher purity.

Further, in the present invention, the laser beam 11 ′ passing through the through hole 21 through the raw material gas supply passage 14 through the through hole forming member 20.
It is also proposed that the structure be provided not only in a direction orthogonal to the traveling direction of (11) but also obliquely.

Even if this is shown as a modification to the configuration using a single source gas supply passage 14 as in the second illustrated configuration, it is also tilted so as to face the direction opposite to the traveling direction of the laser beam. However, as already explained,
Effect: Energy of laser beam can be effectively used,
Effect: The effect that the generated fine particles can be swept out from the through hole promptly can be obtained, and even when the inert gas G _i is used for scavenging, as can be seen in the first illustrated configuration, Although the function can be assisted, it is particularly desirable to adopt this oblique configuration as a modified example of the third illustrated configuration, and further to obliquely feed the source gas G _{r in the} forward direction of the laser beam 11 ′ (11). When the through hole forming member 20 as shown in FIG. 4 is provided so that it can be blown out, various effects can be enhanced synergistically.

As can be seen from FIG. 4, it is clear that the feed path 14 for the source gas G _r
Are shown at positions opposite to each other in the radial direction of the through hole 21 in the sectional configuration, and each has an angle θ _I with respect to the axis of the through hole or the optical axis of the laser beam.

This angle θ _I is arbitrary in principle, but in general, when the tapered surface 24 for reflection is provided at the entrance of the through hole as described above, it is designed to incline along the tapered surface 24. It is convenient both in terms of manufacturing and manufacturing. Therefore, it is preferably 45 ° or less, and most preferably about 30 °.

In this way, as described above, the diagonal structure that can substantially extend the length across the laser beam and the raw material from the opposite direction, which has a strong concentration action and a strong scavenging action for the generated fine particles. The synergistic effect of the collision action of the gases G _r and G _r can further enhance the reaction promotion effect, the laser / energy utilization efficiency improving effect, and the generated fine particle removing effect.

When viewed from the front side of the through hole 21, the configurations shown in FIGS.
Either of the configurations shown in FIGS. 5 and 6 can be arbitrarily adopted.

In the configuration shown in FIG. 5, the two raw material gas supply passages 14, 14 are arranged so as to be mounted on the diameter of the through hole, and therefore the raw material gas G _r emitted from the openings 22, 22 directly passes through the central axis of the through hole. However, in the configuration shown in FIG. 6, the two source gas supply passages 14 and 14 are placed on straight lines that are translated from right to left with respect to the diameter line of the through hole. As a result, the source gases G _r and G _r emitted from the openings 22 and 22 are directed in a direction that is slightly deviated radially outward from the central axis of the through hole.

Even with the configuration shown in the fifth illustration, of course, as described above,
The effect of hitting the raw material gas G _r can be expected, but according to the configuration shown in FIG. 6, a swirl flow can be further created in the through hole 21 according to the purpose, as indicated by the arrow f _t . Since the raw material gas G _r can be retained in the reaction section 18 for a long time, it is suitable for applications in which the laser beam is used more effectively and heating to a high temperature region is required.

In addition, in FIGS. 5 and 6, a pair of raw material gas supply passages 14 and 14 are further drawn by imaginary lines to show that two or more raw material gas supply passages 14 may be provided as a representative. However, more source gas supply passages 14 may be provided, and conversely, three supply passages 14 may be provided at 120 ° intervals.

However, in general, these plural source gas supply paths 14 are
It is preferable that one is provided for each position in the circumferential direction obtained by dividing 0 ° into equal intervals by the number of supply paths. That is,
It is desirable that θ _H = 360 ° / n ..., where θ _H is the circumferential angle of the adjacent ones and n is the number of source gas supply paths used.

The material of the through hole forming member 20, aluminum, copper,
Suitable materials such as ceramics and quartz can be used, and in practice, there are few restrictions, so any of them can be adopted, but for example, when using a reflection mechanism at the entrance of a through hole, high reflectance is required. In this case, copper or the like is preferable, and if it is not desirable because it easily reacts with ammonia gas, aluminum or the like is preferable. Ceramics, quartz, etc. are slightly disadvantageous in terms of workability, but are most excellent in terms of stability.

Finally, an experimental example by the present inventor is given for reference.

The through hole forming member 20 used has a structure similar to that shown in FIGS. 4 and 5, and is made of aluminum.

The diameter d _H of the through hole 21 drilled in this is 6 mmφ, and the source gas supply passage 14
Has an inner diameter d _I of 2 mmφ, the inclination angle θ _I of the source gas supply passage 14 shown in FIG. 4 is 30 °, and the angular interval θ _H between the pair of opposing source gas supply passages 14 and 14 is exactly the same. It is 180 degrees.

The degree of vacuum in the reaction chamber 12 accommodating the through hole forming member 20 is set to about 300 Torr, a 100 W carbon dioxide gas laser is used as the laser light source 10, and the function of the converging lens system 23 causes the focus position in the through hole 21 at the focal position. Silane gas (2% + Ar) and ethylene gas (20%) are placed at the spot diameter of 0.5 mmφ.
+ Ar) mixed gas was supplied at a flow rate of 100 cc / min.

As a result, the effect of using the through-hole forming member according to the present invention was sufficiently exhibited, and silicon carbide fine particles having a particle diameter of 0.1 μm or less were produced with high purity and considerable uniformity. Although visually confirmed, it is apparent that fine particles having uniform particles were produced in a shorter time than when the conventional method described above was followed.

Of course, from the principle and the nature of the present invention, it is obvious that the present invention effectively functions also in the production of other fine particles.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing an embodiment of a fine particle production apparatus of the present invention, and FIGS. 2 to 6 are schematic diagrams showing various configuration examples of a through hole forming member that can be adopted in the present invention. FIG. 7 is a schematic diagram of a conventional laser-assisted gas phase reaction fine particle production apparatus. In the figure, 10 is a laser light source, 11 is a parallel laser beam, and 11 '.
Is a focused laser beam, 12 is a reaction chamber, 14 is a source gas supply path, 18 is a reaction part, 20 is a hole forming member, 21 is a hole,
Reference numeral 22 is an opening of the raw material gas supply path, 23 is a convergent lens system, 24 is a tapered surface at the entrance of the through hole, G _r is a raw material gas, and G _i is an inert gas.

Claims (14)

[Claims] 1. A method for producing fine particles, which comprises introducing a raw material gas into a reaction chamber, applying heat energy by a laser beam to the raw material gas to cause a gas phase reaction, and then solidifying to produce fine particles. A through hole forming member having through holes opened at both ends is arranged in the reaction chamber; the laser beam is passed through the through hole; and the through hole is formed on a part of an inner wall surface of the through hole. A tip of a raw material gas supply path provided so as to penetrate through the hole forming member is opened, and the raw material gas is supplied to the laser beam in the vicinity of the laser beam or at a position in contact with the laser beam; A method for producing fine particles. 2. The method for producing fine particles according to claim 1, wherein the raw material gas supply passage passing through the through hole forming member is orthogonal to the optical axis of the laser beam passing through the through hole. A method for producing fine particles, comprising: 3. The method for producing fine particles according to claim 1, wherein the raw material gas supply path passing through the through hole forming member is oblique with respect to the optical axis of the laser beam passing through the through hole. The method for producing fine particles, wherein: 4. The method for producing fine particles according to any one of claims 1 to 3, wherein a through hole entrance through which a laser beam is incident is provided on the optical axis of the laser beam. On the other hand, it is processed into a taper shape of 45 ° or less so that the light reflected by the taper surface is also guided into the through hole. 5. The method for producing fine particles according to any one of claims 1 to 4, wherein the raw material gas supply passage for passing through the through hole forming member is provided with the through holes. A plurality of pairs are provided in opposition to each other in the radial direction. 6. The method for producing fine particles according to any one of claims 1 to 5, wherein the fine particles are supplied through an opening of a raw material gas supply passage when the through holes are viewed from the front. The raw material gas flow to be emitted is not directed toward the central axis of the through hole, but is directed toward a position that is off-set with respect to the central axis. The raw material gas is caused to generate a swirl flow; 7. A method for producing fine particles according to any one of claims 1 to 6, wherein the laser beam is focused and one point in the length direction in the through hole. And a source gas flow is incident on the laser beam within the focal point or a plane including the focal point. 8. A fine particle production apparatus for producing fine particles by introducing a raw material gas into a reaction chamber, applying heat energy by a laser beam to the raw material gas to cause a gas phase reaction, and then solidifying to produce fine particles. A through hole forming member provided in the reaction chamber and having through holes open at both ends; a laser light source for generating the laser beam so as to pass through the through hole; and the raw material gas in the vicinity of the laser beam or In order to supply the laser beam at a position where it comes into contact with the laser beam, a source gas supply path which is opened in a part of the inner wall surface of the through hole and is provided so as to penetrate the through hole forming member A fine particle manufacturing apparatus having. 9. The apparatus for producing fine particles according to claim 8, wherein the raw material gas supply path provided in the through hole forming member is provided on the optical axis of the laser beam passing through the through hole. On the other hand, it is orthogonal to each other; 10. The apparatus for producing fine particles according to claim 8, wherein the raw material gas supply path provided in the through hole forming member is located at the optical axis of the laser beam passing through the through hole. On the other hand, it is provided obliquely; 11. The apparatus for producing fine particles according to any one of claims 8 to 10, wherein a transparent entrance through which a laser beam is incident is provided on the optical axis of the laser beam. On the other hand, the fine particle manufacturing apparatus is characterized in that it is processed into a taper shape of 45 ° or less so that the light reflected by the taper surface is also guided into the through hole. 12. The fine particle production apparatus according to any one of claims 8 to 11, wherein the raw material gas supply passage provided in the through hole forming member is a through hole. 2. A fine particle production apparatus comprising a plurality of pairs, which are opposed to each other in the radial direction. 13. A fine particle production apparatus according to any one of claims 8 to 12, wherein the fine particles are supplied through an opening of a raw material gas supply passage when the through hole is viewed from the front. The source gas flow to be generated is not emitted toward the central axis of the through hole, but is emitted toward a position off-set with respect to the central axis so that a vortex flow is generated inside the through hole. The axis of the raw material gas supply passage is arranged so as to be displaced from the central axis of the through hole, and the fine particle manufacturing apparatus. 14. The fine particle production apparatus according to any one of claims 8 to 13, wherein the raw material gas is supplied at one point in the length direction in the through hole. A fine particle production apparatus comprising: a convergent lens system for narrowing a parallel laser beam emitted from a laser source so that a focal point having a desired diameter is produced at a position.