JPS61220764A - Method for controlling speed of particle flow - Google Patents

Abstract

PURPOSE:To transfer fine particles under accurate control of supersonic speed by regulating the ratio of the pressures on the upstream and the down stream side of a contracting and expanding nozzle provided at the flow passage to less than the ratio of the respective critical pressures and specifying the area ratio of the openings of the throat part and the outflow part of the nozzle. CONSTITUTION:The ratio of the pressures on the upstream and the downstream side of a contracting and expanding nozzle 1 is regulated to less than the ratio of the respective critical pressures and the area ratio of the openings of the throat part 2 and the outflow part 1b of the nozzle 1 is specified. Namely, since fine particles can be independently transferred in the space as a beam of uniformly dispersed particles, the fine particles can be transferred under accurate control of supersonic speed. Accordingly, the active fine particles can be transferred to a collecting position under such conditions and the kinetic energy when the particles are blown can be precisely controlled.

Description

Detailed Description of the Invention [Industrial Field of Application] The present invention relates to a method for controlling the speed of a particle flow used in the transportation and spraying of particles, for example, in film-forming processing, composite processing, etc. using particles. It is expected that it will be applied to the formation of materials, doping processing, and new formation sites for fine particles.

In this specification, fine particles refer to atoms, molecules, ultrafine particles, and general fine particles. Here, ultrafine particles include, for example,
A gas phase reaction was used. Evaporation method in gas, plasma evaporation method,
Obtained by gas phase chemical reaction method, colloidal precipitation method, solution spray pyrolysis method, etc. using liquid phase reaction,
Refers to ultrafine (generally 0.5 #Lm or less) particles.
General fine particles refer to fine particles obtained by general methods such as mechanical crushing or precipitation precipitation treatment, and beam refers to a jet stream whose cross-sectional area is approximately constant in the flow direction.
Its cross-sectional shape does not matter.

[Prior Art] Generally, fine particles are dispersed and suspended in a carrier gas and transported by the flow of the carrier gas.

Conventionally, the speed control of the particle flow accompanying the transport of the particles is
This is simply done by dividing the entire flow path of the particles flowing together with the carrier gas using a tube or a housing, and adjusting the differential pressure between the upstream and downstream sides of the divided flow path.

Furthermore, when spraying fine particles onto a substrate, the fine particles are jetted out together with a carrier gas through a nozzle. The nozzle used to spray these particles is a simple parallel tube or tapered nozzle, and even in this case, the speed of the ejected particle flow is simply controlled by adjusting the differential pressure before and after the nozzle. .

[Problems to be Solved by the Invention] However, in the conventional flow rate control based on a mere differential pressure, the flow of particles becomes a diffusion flow with a large density distribution, making it difficult to accurately control the flow rate of the entire flow. Furthermore, in control based on differential pressure, the magnitude of the differential pressure does not necessarily lead to the magnitude of the flow velocity, and from this point of view as well, it is difficult to accurately control the flow velocity. If the flow rate cannot be controlled accurately, for example, when transporting active particles, the activity of the particles may disappear due to a delay in the transfer, or the kinetic energy of the particles may sometimes be too large. If it is too small, film formation by spraying, etc. is likely to be inhibited.

Measures for Solving the Problems c] Measures taken to solve the above problems are explained with reference to FIG. 1, which is an explanatory diagram of the basic principle of the present invention. , the speed of the particle flow is controlled by making the pressure ratio between the upstream side and the downstream side of the nozzle l equal to or less than the critical pressure ratio, and regulating the opening area ratio of the throat section 2 of the nozzle 1 and the outlet port 1b to control the speed of the particle flow. This control method solves the above problems.

The contracting/expanding nozzle l in the present invention is a throat section 2 whose opening area is gradually narrowed from the inlet 1a toward the middle section, and whose opening area is gradually expanded from the throat section 2 toward the outlet 1b. In Figure 1, the nozzle is
For convenience of explanation, the inflow side and outflow side of the contraction/expansion nozzle 1 are as follows.
It is connected to an upstream chamber 3 and a downstream chamber 4, each of which is a closed system. However, the inflow side and the outflow side of the contraction/expansion nozzle l in the present invention can be either a closed system or an open system as long as a pressure ratio can be created between the two and the particles can flow together with the carrier gas. Good too.

[Function] For example, as shown in FIG.
When the inside is evacuated by the vacuum pump 5, the pressure ratio between the upstream chamber 3 and the downstream chamber 4 is made equal to or higher than a required critical pressure ratio. The supplied carrier gas containing fine particles flows from the upstream chamber 3 through the contraction/expansion nozzle l due to the differential pressure caused by the exhaust, and flows into the downstream chamber 4.
It will flow into.

By the way, the contraction/expansion nozzle l functions not only to eject fine particles together with the carrier gas according to the pressure difference between the upstream side and the downstream side, but also to equalize the flow of the ejected carrier gas and fine particles. Therefore, by creating this uniform flow of fine particles, the overall flow velocity can be easily controlled.

In addition, when the pressure ratio P/Po between the pressure P0 of the upstream chamber 3 and the pressure P of the downstream chamber 4 is equal to or higher than the critical pressure ratio, the contraction/expansion nozzle l has an opening area AI of the throat portion 2 according to this pressure ratio PiPo.
By appropriately specifying the ratio A/A'' between the opening area A of the outflow port 1b and the opening area A of the outflow port 1b, the flow velocity of the particles ejected together with the carrier gas can be adjusted at supersonic speed.

Here, the velocity of the particle flow is U, and the sound velocity at that point is a.
, the specific heat ratio of the particle flow is γ, and assuming that the particle flow is a compressible one-dimensional flow and expands adiabatically, the Matsuha number M reached by the particle flow is expressed as follows from the pressure po in the upstream chamber and the pressure P in the downstream chamber. It is determined by the formula, especially P/P (if 1 is below the critical pressure ratio, 1
M is 1 or more.

Note that the sound velocity a can be determined by a linear equation, where T is the local temperature and R is the gas constant.

a=r〒1薯" Also, the opening area A of the outflow hole 1b and the opening area A of the throat part 2
” and Matsuha's number M have the following relationship.

Therefore, by determining the opening area ratio A/A in accordance with the Matsuzha number M determined from equation (1) by the pressure ratio P/P of the pressure Po in the upstream chamber 3 and the pressure P in the downstream chamber 4, the expansion/contraction nozzle can be The flow rate of the particulate flow ejected from 1 can be adjusted.

The velocity U of the particle flow at this time can be determined by the following equation (3).

On the other hand, when particles are ejected in a fixed direction along with carrier gas as an ultra-high-speed flow as described above, the carrier gas and particles travel straight while maintaining almost the jet cross section immediately after ejection.
Beamed. Therefore, the flow of particles carried by this carrier gas is also converted into a beam, which moves through the space within the downstream chamber 4 with minimal diffusion, in a spatially independent state without interference with the wall surface of the downstream chamber 4, and at an ultra-high speed. The speed control is therefore extremely accurate.

For this reason, it is possible, for example, to form active particles in the upstream chamber 3 and transfer them directly into a beam through the contraction/expansion nozzle 1, or to activate them within the contraction/expansion nozzle 1 or immediately after the contraction/expansion nozzle 1. If fine particles having a The particles can be collected on the substrate 6 in a good active state. Furthermore, since the particles are sprayed onto the substrate 6 as a beam whose flow velocity is controlled, the kinetic energy of the particles can be easily controlled during this spraying.

[Example] Figure 2 is a schematic diagram of an example in which the method of the present invention is used to form a film using ultrafine particles.
3 is an upstream chamber, 4a is a first downstream chamber, and 4b is a second downstream chamber.

The upstream chamber 3 and the first downstream chamber 4a are configured as an integrated unit, and the first downstream chamber 4a is equipped with a skimmer 7, a gate valve 8, and a second downstream chamber 4, which are also each unitized.
b are sequentially connected to each other so as to be connectable and separable via flanges having a common diameter (hereinafter referred to as "common flanges"). Upstream chamber 3, first downstream chamber 4a, and second downstream chamber 4
b is maintained at a high degree of vacuum in stages from the upstream chamber 3 to the second downstream chamber 4b by an exhaust system to be described later.

A gas phase excitation device 9 is attached to one side of the upstream chamber 3 via a common flange. This gas phase excitation device 9 generates active ultrafine particles using plasma, and sends out the ultrafine particles together with a carrier gas such as hydrogen, helium, argon, nitrogen, etc. to the contraction/expansion nozzle 1 located on the opposite side. It is. In order to prevent the formed ultrafine particles from adhering to the inner surface of the upstream chamber 3, adhesion prevention treatment may be applied to the inner surface.
Since the first downstream chamber 4a has a higher degree of vacuum than the upstream chamber 3, the pressure difference between the two causes the carrier gas to directly pass through the contraction/expansion nozzle l and flow to the first downstream chamber 4a. It turns out.

As shown in FIG. 3(a), the gas phase excitation device 9 includes a rod-shaped first electrode 8a disposed within a tubular second electrode 9b, and a carrier gas and a raw material gas supplied into the second electrode 8b. Thus, a discharge is caused between both electrodes 9a and 9b. Further, the gas phase excitation device 9, as shown in FIG. 3(b),
The first electrode 9a provided in the second electrode 9b may be a slotted tube to supply carrier gas and raw material gas between the electrodes 9a and 9b through the inside of the first electrode sa. ), both half-tubular electrodes 9a, 9
b are joined into a tubular shape via an insulating material 9c, and both electrodes 9a,
It is also possible to supply the carrier gas and source gas into the tube formed by 9b.

The contraction/expansion nozzle l opens an inlet port 1a to the upstream chamber 3 at the side end of the first downstream chamber 4a on the upstream chamber 3 side, and the first downstream chamber 4
The outflow port 1b is opened at a, and the upstream chamber 3 is protruded into the upstream chamber 3, and is attached via a common flange. However, this contraction/expansion nozzle l may be installed in a state where it projects into the first downstream chamber 4a.The direction in which the contraction/expansion nozzle l should be projected depends on the size, amount, nature, etc. of the ultrafine particles to be transported. You can choose accordingly.

As mentioned above, the contraction/expansion nozzle 1 has an inlet port 1a.
It is sufficient if the opening area is gradually narrowed down to form the throat part 2, and then the opening area is gradually expanded again to form the outflow port 1b, which is shown enlarged in Fig. 4(a). As such, it is preferable that the inner circumferential surface near the outlet lb is approximately parallel to the central axis. This means that the flow direction of the jetted carrier gas and ultrafine particles is to some extent Since it is affected by the direction of the surface, the purpose is to make the flow as parallel as possible to facilitate speed control.

However, as shown in FIG. 4(b), the angle α of the inner circumferential surface extending from the throat portion 2 to the outlet 1b with respect to the central axis is 7.
If the angle is preferably 5° or less, peeling phenomenon will not easily occur and the flow of the ejected carrier gas and ultrafine particles will be maintained almost uniformly. By omitting the formation of the part, the contraction/expansion nozzle 1 can be manufactured easily. Furthermore, if the contraction/expansion nozzle l is made rectangular as shown in FIG. 4(C), carrier gas and ultrafine particles can be ejected in a slit shape.

Here, the separation phenomenon is a phenomenon in which when there is a protrusion etc. on the inner surface of the contraction/expansion nozzle l, the boundary layer between the inner surface of the contraction/expansion nozzle l and the flowing fluid becomes large and the flow becomes non-uniform. The above-mentioned angle α, which is more likely to occur as the jet flow becomes faster, is preferably made smaller as the inner surface finishing precision of the contraction-expansion nozzle 1 becomes lower, in order to prevent this peeling phenomenon. Ha, Jl! 9801
It is preferable to have three or more inverted triangular marks representing the surface finishing accuracy defined in 1. Therefore, by determining the finishing accuracy with emphasis on this enlarged portion, it is possible to easily manufacture the contracting/expanding nozzle l. In addition, in order to prevent the occurrence of peeling phenomenon, the throat part 2
It is necessary to have a smooth curved surface so that the differential coefficient in the rate of change of cross-sectional area does not become a flash.

The material of the contraction/expansion nozzle 1 is, for example, iron.

In addition to stainless steel and other metals, acrylic resin,
A wide variety of materials can be used, including synthetic resins such as polyvinyl chloride, polyethylene, polystyrene, and polypropylene, ceramic materials, quartz, and glass. This material can be selected by taking into consideration non-reactivity with the generated ultrafine particles, processability, gas release properties in a vacuum system, etc. - It is also possible to plate or coat with a material that does not easily cause a reaction. Specific examples include polyfluoroethylene coating.

The length of the contraction/expansion nozzle 1 can be arbitrarily determined depending on the size of the device and the like. By the way, the contraction/expansion nozzle l
When flowing through the carrier gas and ultrafine particles, the thermal energy they possess is converted into kinetic energy. Particularly when ejected at supersonic speed, the thermal energy becomes significantly small, resulting in a supercooled state. Therefore, if the carrier gas contains condensed components, it is also possible to actively condense them by the supercooled state, thereby forming ultrafine particles. Since the formation of ultrafine particles by this is homogeneous nucleation, it is easy to obtain homogeneous ultrafine particles.In addition, in this case, in order to achieve sufficient condensation, it is preferable that the contraction/expansion nozzle 1 is long.On the other hand, the above When such condensation occurs, thermal energy increases and velocity energy decreases. Therefore, in order to maintain high-speed jetting, it is preferable that the contraction/expansion nozzle l be short.

The pressure ratio jj/ of the pressure Pa in the upstream chamber 3 and the pressure P in the downstream chamber 4
Based on Pa, the opening area Jk” of the throat 2 and the outlet 1
By appropriately determining the ratio A/A◆ of b to the opening area and causing it to flow through the contraction/expansion nozzle l, the carrier gas containing ultrafine particles is converted into a beam and flows from the first downstream chamber 4a to the second downstream chamber 4a. It flows into the chamber 4b at an extremely high speed determined from the above pressure ratio and A/A''.

The skimmer 7 is installed in the first downstream chamber 4a so that the second downstream chamber 4b can maintain a sufficiently higher degree of vacuum than the first downstream chamber 4a.
This is to enable adjustment of the opening area between the first downstream chamber 4b and the second downstream chamber 4b. Specifically, as shown in FIG. 5, two adjustment plates 11 and 11' each having dogleg-shaped notches 10 and 10' can be slid past each other with their notches 1G and 10' facing each other. It has been established in This adjustment plate 11° 11' can be slid from the outside, and depending on the overlap between the cut portions 10 and 10', it is possible to allow the beam to pass through and maintain a sufficient degree of vacuum in the second downstream chamber. The degree of opening is adjusted. Note that the shapes of the notches 1G and 10' of the skimmer 7 and the adjustment plates 11 and 11' may be semicircular or other shapes other than the shapes shown in the drawings.

The gate valve 8 has an annular valve body 13 that is raised and lowered by turning a handle 12, and is opened when the beam is traveling. By closing this gate valve 8, the unit in the second downstream chamber 4b can be replaced while maintaining the degree of vacuum in the upstream chamber 3 and the first downstream chamber 4a. Further, in the apparatus of this embodiment, the ultrafine particles are collected in the second downstream chamber 4b, but if the gate valve 8 is a pole valve or the like, especially when the ultrafine particles are metal particles that are easily oxidized, By replacing the unit of the second downstream chamber 4b together with this Pall valve, there is an advantage that the unit can be replaced without the risk of rapid oxidation.

A base body 6 is located in the second downstream chamber 4b for receiving and depositing ultrafine particles transferred as a beam, and collecting the ultrafine particles in a film-formed state. This base body 6 is attached to the second downstream chamber 4b via a common flange, and is attached to the cylinder 1.
4 is attached to a base holder 18 at the tip of a slide shaft 15 that is slid by a slide shaft 15. A shutter 17 is located on the front side of the base 6, so that the beam can be blocked whenever necessary. Further, the substrate holder 18 is configured to heat or cool the substrate 6 under optimal temperature conditions for collecting ultrafine particles.

Incidentally, glass windows 18 are attached to the upper and lower sides of the upstream chamber 3 and the second downstream chamber 4b through common flanges, respectively, as shown in the figure, so that the inside can be observed. Although not shown, the upstream chamber 3 and the first downstream chamber 4a
Similar glass windows (similar to 18 in the figure) are also installed at the front and rear of the second downstream chamber via common flanges. These glass windows 18 can be removed and replaced with various measuring devices, load lock chambers, etc. via a common flange.

Next, the exhaust system in this embodiment will be explained.

The upstream chamber 3 is connected to a main valve 20 via a pressure regulating valve 19.
connected to a. The first downstream chamber 4a is directly connected to the main valve 20a, and this main valve 20a is connected to the vacuum pump 5a.The second downstream chamber 4b is connected to the main valve 20b, and further this main valve 20b is connected to the vacuum pump 5b. Furthermore, 2
1a and 21b are main valves 20a and 20b, respectively.
The auxiliary valve 23a is connected to the immediate upstream side of the auxiliary valve 22a and 22b.

The vacuum pump 23b is connected to the vacuum pump 5a and is used to check the inside of the upstream chamber 3, the first downstream chamber 4a, and the second downstream chamber 4b. In addition, 24a-24h are each chamber 3, 4a, 4b and pump 5a, 5b, 21
The leak and purge valves 21a and 21b are leak and purge valves 21a and 21b, and the pressure regulating valve 1.
8, the upstream chamber 3, the first and second downstream chambers 4a, 4
0 The irregularities in b are performed using the vacuum pumps 20a and 20b.
Next, the auxiliary valves 23a, 23b and the main valves 20a, 2 are closed.
0b is opened and the vacuum pumps 5a and 5b are used to create a sufficient degree of vacuum in the upstream chamber 3 and the first and second downstream chambers 4a and 4b. At this time, by adjusting the opening degree of the pressure am valve L8, the degree of vacuum in the first downstream chamber 4a is made higher than that in the upstream chamber 3,
Next, the carrier gas and the raw material gas are flowed, and the skimmer 7 is used to adjust the degree of vacuum in the second downstream chamber 4b to be higher than that in the first downstream chamber 4a. This adjustment can also be performed by adjusting the opening degree of the main valve 20b. The chambers 3, 4a, and 4b are controlled to maintain a constant degree of vacuum throughout the formation of ultrafine particles and the film forming operation by beam injection. This control may be done manually, but each room 3, 4a,
This may be done by detecting the pressure inside 4b and automatically controlling the opening and closing of the pressure regulating valve 13, main valves 20a, 20b, skimmer 7, etc. based on the detected pressure.

The degree of vacuum may be controlled by separately providing the vacuum pumps 5a for the upstream chamber 3 and the first downstream chamber 4a for each chamber 3 and 4a. However, as in this embodiment, One vacuum pump 5a evacuates in the flow direction of the beam, and the upstream chamber 3
By controlling the degree of vacuum of the first downstream chamber 4a and the first downstream chamber 4a, it is easy to keep the pressure ratio between the two constant even if there is some pulsation in the vacuum pump 5a. It has the advantage of being easy to maintain a constant flow state.

The suction by the vacuum pumps 5a, 5b is preferably performed from above, especially in the first and second downstream chambers 4a, 4b.By suctioning from above, the descent of the beam due to gravity can be suppressed to some extent. can.

Although the apparatus according to this embodiment is as described above, the following modifications can be made.

First, the contraction/expansion nozzle l can be tilted vertically and horizontally, and can be scanned at regular intervals, so that film formation can be performed over a wide range. Particularly, this tilting and scanning is advantageous when combined with the rectangular nozzle shown in FIG. 4(C).

The contraction/expansion nozzle 1 is formed of an insulator such as quartz.

Microwaves are applied there to form active ultrafine particles in the contraction/expansion nozzle 1, or a transparent material is used to irradiate the flow with light having various wavelengths such as ultraviolet, infrared, and laser light. You can also do that. It is also possible to provide a plurality of contraction/expansion nozzles l to generate a plurality of beams at once. In particular, when a plurality of contraction/expansion nozzles l are provided, by connecting each to an independent upstream chamber 3, beams of different particles can be run at the same time. By crossing comrades. It is also possible to form new particles by collisions between different particles.

The base body 6 is held movably or rotatably in the vertical and horizontal directions,
It is also possible to receive the beam over a wide range. Further, by winding up the base body 6 into two rolls and receiving the beam while sequentially sending out the base body 6, the long base body 6 can also be treated with fine particles. Furthermore, the treatment with fine particles may be performed while rotating the drum-shaped base 6.

In this embodiment, the generation chamber 3, the first downstream chamber 4a, and the second downstream chamber 4b are constructed, but the second downstream chamber 4b may be omitted, or a third downstream chamber may be provided downstream of the second downstream chamber.

Fourth...downstream chambers can also be connected. Further, by pressurizing the upstream chamber 3, the first downstream chamber 4a can be made into an open system, and by reducing the pressure in the first downstream chamber 4a, the upstream chamber 3 can be made into an open system. In particular, like an autoclave, the upstream chamber 3 can be pressurized and the first downstream chamber 4a and below can be depressurized.

In this embodiment, active ultrafine particles are formed in the upstream chamber 3, but this is not necessarily necessary.

Separately formed particles may be sent to the upstream chamber 3 along with the carrier gas.Also, a valve for opening and closing the contraction/expansion nozzle 1 may be provided, and the valve may be intermittently opened and closed while temporarily storing the particles in the upstream chamber 3. , fine particles can also be obtained. If the valve is opened and closed in synchronization with energy application on the downstream side including the throat portion 2 of the contraction/expansion nozzle 1,
The load on the exhaust system is significantly reduced, and a pulsed particulate flow can be obtained while making effective use of the raw material gas. Note that under the same exhaust conditions, the above-mentioned intermittent opening and closing has the advantage that it is easier to maintain a high vacuum on the downstream side. In the case of intermittent opening and closing, a chamber may be provided between the upstream chamber 3 and the contraction/expansion nozzle 1 to temporarily store fine particles.

In addition, multiple contraction/expansion nozzles 1 are arranged in series, and the pressure ratio on the upstream side and downstream side is adjusted to maintain the beam speed, and each chamber is made spherical to minimize the generation of dead space. It can also be prevented.

[Effects of the Invention] According to the present invention, fine particles can be transported in a spatially independent state as a uniformly dispersed supersonic beam, so that fine particles can be transported under precise supersonic velocity control. be able to. Therefore, the active particles can be reliably transported as they are to the collection position, and the kinetic energy of the spraying can be accurately controlled. In addition, it becomes a focused ultra-high-speed parallel flow called a beam, and when it is made into a beam, thermal energy is converted to kinetic energy, and the particles in the beam become frozen, so we can create a new reaction field that utilizes these. I have high hopes for what I will achieve. Furthermore, according to the speed control method of the present invention, since the fluid is in the frozen state, it is also possible to define the microscopic state of molecules in the fluid and handle the transition from one state to another state. In other words, it is possible to perform chemical reactions in the gas phase using a new method in which various energy levels of molecules are defined and energy corresponding to the levels is imparted. In addition, by providing a field for energy transfer that is different from conventional methods, it is possible to support intermolecular compounds formed by relatively weak intermolecular forces such as hydrogen bonds and van der Waals bonds.

It can also be easily produced.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram of the basic principle of the present invention, Fig. 2 is a schematic diagram showing an example in which the method of the present invention is applied to film formation using ultrafine particles, and Figs. 3 (a) to (c). 4(a) to 4(c) are diagrams each showing an example of the shape of a contraction/expansion nozzle, and FIG. 5 is an explanatory diagram of a skimmer. 1: contraction/expansion nozzle, 1a: inlet, lb=outlet, 2: throat, 3: upstream chamber, 4: downstream chamber,
4a: first downstream chamber, 4b=second downstream chamber, 5, 5a, 5b: vacuum pump,
6: Base, 7: Skimmer, 8: Gate valve. 9: Gas phase excitation device, 8a: First electrode. 8b: second electrode, 10.10': notch. 11, 11': Adjustment plate, 12: Handle, 13: Valve body, 14 Niji cylinder, 15 Ni slide shaft, 16 Bi base holder, 17: Shutter, 18 Ni glass window, 19: Pressure adjustment valve, 20a, 20b: Main valve . 21a, 21b: Decompression pump, 22a, 22b: Arabiki valve. 23a, 23b: Auxiliary valves, 24a to 24h: Leak and purge valves.

Claims (1)

[Claims] 1) A contraction/expansion nozzle is provided in the flow path, the pressure ratio on the upstream side and the downstream side of this nozzle is made equal to or less than the critical pressure ratio, and the opening area ratio between the throat and the outlet of the nozzle is defined to control the velocity of the particulate flow. A method for controlling the velocity of a particulate flow, characterized by controlling the velocity of a particulate flow.