JPS62158329A - Device for spraying fine particle - Google Patents

Abstract

PURPOSE:To realize spraying of a complicated pattern and that of constant distribution in a spraying amount without requiring masking process or the like, by applying a potential difference with regulated distribution between a base installed on the side downstream from an acceleration electrode and the acceleration electrode. CONSTITUTION:When fine particles are injected as a supersonic proper expansion flow through a reduction/enlargement nozzle 1, the flow of the fine particles advance directly, with a cross section of the injected flow nearly kept after the injection, becoming beams. When the fine particles are made to become ionic particles inside the reduction/enlargement nozzle 1 or so, they are sent as beam-shaped flow to an acceleration electrode 2, accelerated by potential difference between the acceleration electrode 2 and the base 4 to be sprayed at the base 4. Regulating a distribution of the potential difference between the acceleration electrode 2 and the base 4 enables the ionic particles to be sprayed according to the distribution of the potential difference at the base 4.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a fine particle spraying device used for, for example, film forming, etching, forming composite materials, doping, etc., by spraying fine particles onto a substrate. .

[Prior Art] Conventionally, a device for spraying fine particles has been known in which an activation means, an accelerating electrode, and a base are sequentially provided in a flow path for fine particles, and a power source is connected to apply a potential difference between the accelerating electrode and the base. It is being This conventional device uses a pressure difference between the upstream and downstream sides to send the fine particles toward the activation means, first converting them into ion particles, and then moving them between the accelerating electrode and the substrate. Accelerated by the potential difference between
Ion particles are sprayed onto the substrate as a translational flow.

[Problems to be Solved by the Invention] However, in the conventional device described above, fine particles are sent from the activation means to the accelerating electrode as an irregular flow due to a mere differential pressure between the upstream and downstream sides. Acceleration due to this can only make this a regular translational flow, and delicate adjustment of the spray area of fine particles is impossible. Also,
It is also impossible to create a specific concentration distribution in the flow of particles in order to provide a specific distribution in the amount of particles sprayed onto the substrate. Therefore, when spraying fine particles only on a specific area of the substrate, masking must be applied, and when distributing the spray amount, the process must be performed in batches while replacing the mask, which makes the work extremely complicated.

[Means for Solving the Problems] The means taken in the present invention to solve the above problems will be explained with reference to FIG. 1, which corresponds to an embodiment of the present invention. A contraction/expansion nozzle l provided in the path, an acceleration electrode 2 provided downstream of the contraction/expansion nozzle 1, an activation means 3 for converting flowing fine particles into ion particles upstream of the acceleration electrode 2, and an acceleration The above-mentioned problems are solved by providing a particle spraying device having a power source 5 that applies a potential difference with an adjusted potential difference distribution between the base 4 and the accelerating electrode 2, which are provided downstream of the electrode 2.

In the present invention, fine particles include atoms, molecules, clusters,
Ultrafine particles refer to ultrafine particles and general fine particles.Ultrafine particles include, for example, evaporation in gas, plasma evaporation, and gas phase chemical reaction methods that utilize gas phase reactions, as well as colloidal methods that utilize liquid phase reactions. Refers to ultrafine particles (generally 0.5 p-m or less) obtained by precipitation methods, solution spray pyrolysis methods, etc. General fine particles refer to fine particles obtained by general methods such as mechanical crushing and precipitation treatment.

The contracting/expanding nozzle l in the present invention is a throat portion 1b in which the opening area is gradually narrowed from the inlet 1a toward the middle portion, and the opening area is gradually expanded from the throat portion 1b toward the outlet IC. This refers to the nozzle that is

In addition to general ionic molecules and cluster ions, ionic particles include molecules that are not ions but have polarity, polymers, and even partially charged molecules and polymers.

Further, the potential difference distribution refers to both the strength distribution of the potential difference and the distribution area of the potential difference.

[Function] The contraction/expansion nozzle l has a pressure ratio P/Pa between the pressure PO on its upstream side and the pressure P on its downstream side, and the opening area A of the throat portion 1b.
By adjusting the ratio A/A'' between the opening area A of the outflow port 1c and the opening area A of the outflow port 1c, the flow of ejected particles can be increased to 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 given by the following equation from the upstream pressure Po and the downstream pressure P. It is determined by the formula, especially when P/Po is less than the critical pressure ratio, M
is 1 or more.

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

a=E711 ``Furthermore, the opening area A of the outflow hole 1c and the opening area A of the throat portion 1b'' and the Matsuha number M have the following relationship.

Therefore, the pressure ratio P between the upstream pressure P0 and the downstream pressure P
/Po determines the opening surface ratio A/A'' according to the number M determined from equation (1), and A/A'' determines (
2) By adjusting P/PG according to M determined from the equation, fine particles ejected from the expansion/contraction nozzle 1 can be ejected as a properly expanded flow at supersonic speed. The velocity U of the particle flow at this time can be determined by the following equation (3).

When fine particles are ejected from the contraction/expansion nozzle l as a properly expanded flow at supersonic speed as described above, the fine particle flow travels straight while almost maintaining the cross section of the jet after ejection.

Beamed. Therefore, if fine particles are ionized before and after the contraction/expansion nozzle 1, the particles can be sent to the accelerating electrode 2 as a beam-like flow. Then, the ion particles sent as a beam-like flow are accelerated by the potential difference between the accelerating electrode 2 and the base body 4, and are blown onto the base body 4.

In the present invention, as described above, the ion particles are sent to the accelerating electrode 2 as a regular beam stream, so by adjusting the potential difference distribution between the accelerating electrode 2 and the substrate 4, this potential difference distribution can be adjusted. The ion particles can be sprayed onto the substrate 4 according to the conditions. For example, by applying a voltage to a small area on the base 4, ion particles can be sprayed in a concentrated manner onto the small area. Moreover, if a strength distribution is given to the potential difference between the accelerating electrode 2 and the base 4,
Depending on the strength distribution, the amount of ion particles sprayed onto the base 4 can be distributed.

[Example] Fig. 1 shows an example in which the particle spraying device according to the present invention is used as a film forming device, in which an upstream chamber 6 and a downstream chamber 7 are connected via a contraction/expansion nozzle l. It has become something that has been done.

In the upstream chamber 6, activation means is provided at a position facing the inlet 1a of the contraction/expansion nozzle 1. The activation means 3 is for converting the supplied fine particles into ion particles, such as a gas phase excitation device using microwave discharge, direct current or high frequency discharge, or irradiation with laser light, ultraviolet light or other wavelength light. etc. can be used.

The above-mentioned ionization of the fine particles can also be performed within the contraction/expansion nozzle l or on the downstream side thereof. When performing ion particle formation in the contraction/expansion nozzle l, for example, the contraction/expansion nozzle 1 is
An upper and lower nozzle can be integrated with an electrical insulator in between, and the upper and lower halves can be used as electrodes to act as activation means 3 for generating a discharge between the two, or a translucent material or an electrical insulator can be used to reduce and expand the nozzle 1. An example of this is to configure the activation means 3 to act on light or microwaves. Moreover, when performing ionization on the downstream side of the contraction/expansion nozzle 1, 1i!
This can be done by using the activation means 3 that causes plasma or light to act on the flow of fine particles ejected from the small enlarged nozzle l.

The contraction/expansion nozzle 1 has its inlet port 1a opened into the upstream chamber 6, and its outlet IC opened into the downstream chamber 7, thereby communicating the two chambers. This contraction/expansion nozzle l is shown in Fig. 2(a).
As shown in the enlarged view, it is preferable that the inner circumferential surface is approximately parallel to the central axis at the position of the outlet 1c. This is to make parallel flow as easy as possible since it is affected by the direction of the inner circumferential surface. However, as shown in FIG. 2(b), from the throat part 1b to the outlet 1
If the angle α of the inner circumferential surface leading to point c with respect to the central axis is set to 7° or less, preferably 5° or less, the separation phenomenon will be less likely to occur and the flow of ejected fine particles will be maintained almost uniformly. They do not have to be parallel as described above. By omitting the formation of the parallel portion, the contraction/expansion nozzle 1 can be manufactured easily.

Here, the above-mentioned separation phenomenon means that when there is a protrusion or the like on the inner surface of the contraction/expansion nozzle 1, the boundary layer between the inner surface of the contraction/expansion nozzle 1 and the flowing fluid becomes large.

This is a phenomenon in which the flow becomes non-uniform, and the higher the speed of the jet flow, the more likely it is to occur. In order to prevent this peeling phenomenon, the above-mentioned angle α is preferably made smaller as the inner surface finishing accuracy of the reducing/expanding nozzle 1 is inferior. Three or more inverted triangle marks representing , preferably four or more. In particular, since the peeling phenomenon in the enlarged part of the contraction/expansion nozzle 1 greatly affects the subsequent flow of particles, by determining the finishing accuracy with emphasis on this enlarged part, the production of the contraction/expansion nozzle 1 can be made easier. can. In addition, in order to prevent the occurrence of peeling phenomenon, the throat part 1b
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.

As the material for the contraction/expansion nozzle, a wide range of materials can be used, such as iron, stainless steel, and other metals, as well as acrylic resin, polyvinyl chloride, synthetic resins such as polyethylene, polystyrene, and polypropylene, ceramic materials, quartz, and glass.

This material may be selected by taking into consideration non-reactivity with fine particles, workability, gas release properties in a vacuum system, and the like. Furthermore, the inner surface of the contraction/expansion nozzle 1 can be plated or coated with a material that is less likely to cause adhesion or reaction of fine particles. Specific examples include polyfluoroethylene coating.

By the way, when the fine particles flow through the contraction/expansion nozzle l, the thermal energy they possess is converted into kinetic energy. In particular, when the particles are ejected at supersonic speeds, the thermal energy becomes significantly smaller, which makes it possible to fix the energy level of the particles.

When the downstream chamber 7 is evacuated and fine particles are supplied to the activation means 3 in the upstream chamber 6, the fine particles are ionized by the activation means 3 and immediately ejected from the contraction/expansion nozzle 1. Then, the pressure ratio P between the upstream pressure PG and the downstream pressure P
By adjusting the ratio A/A'' of the opening area A of the /PG and throat portion 1b to the opening area of the outlet 1c, the beam flows to the accelerating electrode 2 as a beam stream.

The accelerating electrode 2 has a tubular shape along the flow path. Further, a base body 4 is provided further downstream of the accelerating electrode 2, and a potential difference is applied between the accelerating electrode 2 and the base body 4 by a power source 5.

The ion particles ejected into the accelerating electrode 2 as a beam stream are further accelerated by the influence of the potential difference between the accelerating electrode 2 and the substrate 4, and collide with the substrate 4. That is, when the ion particles have a positive charge, the ion particles can be accelerated by applying a positive voltage to the accelerating electrode 2 and applying a negative voltage to the base 4. When the ion particles have a negative charge, the charges on the accelerating electrode 2 and the base body 4 may be reversed.
The direction of travel is also controlled by the potential difference distribution. Therefore, not only the flow is further made into a translational flow and the particle distribution in the cross-sectional direction is made uniform, but also the advancing area is controlled by the potential difference distribution. In addition, when the ion particles are 1, for example, polar molecules, polymers, etc., or elongated molecules, polymers, etc. that have an electric charge at one end, each ion particle is It becomes possible to align the directions and spray onto the substrate 4 with a specific orientation.

By the way, for example, when a positive voltage is applied to the accelerating electrode 2, ion particles with a positive potential are accelerated and adhere to the substrate 4, but ion particles with a negative potential tend to adhere to the inner wall surface of the accelerating electrode 2. For this reason, as shown by the broken line in the figure, it is preferable to insert a tubular protective electrode 8 inside the tubular accelerating electrode 2 to protect the accelerating electrode 2 from contamination due to adhesion of ion particles. If the material is made such that the attached ion particles are likely to be released by releasing the applied voltage, even if the ion particles adhere to the inner wall surface of the accelerating electrode 2, the voltages opposite to each other will be applied to the accelerating electrode 2 and the substrate 4. It is preferable that the attached ion particles can be removed by applying .

The potential difference distribution between the accelerating electrode 2 and the substrate 4 can be adjusted by, for example, as shown in FIG. 3, by providing a control electrode 9 on the substrate 4 and connecting it to the power source 5 (see FIG. 1). It can be carried out. As shown in FIG. 3(a), if the control electrode 9 is provided with a diameter smaller than the diameter of the ion particle beam particles, the ion particles can be sprayed while being focused on the control electrode 9. As shown in FIG. 3(b), if a control electrode 9 with a diameter larger than the diameter of the beam flow of ion particles is provided, the ion particles can be sprayed while being diffused according to the size of the control electrode 9. It can be carried out. Figure 3 (
If the control electrodes 9 are arranged in a certain pattern as shown in C), ion particles can be sprayed along this pattern. Furthermore, as shown in Figure 3(d),
By providing control electrodes 9, 9.9 and adjusting the strength of the voltage applied to each control electrode 9, 9.9, the ion particles sprayed can be controlled to be different for each control electrode 9, 9.9. [Effects of the Invention] According to the present invention, when spraying fine particles, not only can the spray area be controlled over a wide range from an arbitrary large area to the edge of a small surface, but also the position and distribution of the spray and amount applied can be controlled. Can be controlled in various ways. Therefore, without special masking or the like, it is possible to spray in a fine and complicated pattern and spray with a constant distribution in the amount of spray, which greatly simplifies the work.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of an embodiment of the present invention, FIG. 2(a),
(b) is an explanatory diagram of the reduction/enlargement nozzle, and Fig. 3(a) -
(d) is an explanatory diagram of potential difference distribution adjustment by the control electrode. 1: 1ili small expansion nozzle, la: inlet, lb = throat, 1c: outlet, 2: acceleration electrode, 3: activation means, 4
: Substrate, 5: Power source, 6: Upstream chamber, 7: Downstream chamber, 8: Protective electrode, 9: Control electrode.

Claims (1)

[Claims] 1) A contraction/expansion nozzle provided in a particle flow path, an acceleration electrode provided downstream of the contraction/expansion nozzle, an activation means for converting flowing particles into ion particles upstream of the acceleration electrode, and acceleration. A particulate spraying device comprising a power source that applies a potential difference with an adjusted potential difference distribution between a base body and an accelerating electrode provided downstream of the electrode.