JPS62115699A - Vapor phase exciter - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a gas phase excitation device using microwaves, and particularly relates to microwave guidance and prevention of microwave introduction failure due to adhesion of active particles to the inlet. .

In this specification, fine particles refer to atoms, molecules, ultrafine particles, and general fine particles. Here, ultrafine particles are, for example,
Evaporation method in gas, plasma evaporation method using gas phase reaction,
It can be obtained by a gas phase chemical reaction method, a colloidal precipitation method, a solution spray pyrolysis method, etc. that utilize a liquid phase reaction.

Refers to ultrafine (generally 0.5 p-trr or less) particles. General fine particles refer to fine particles obtained by general methods such as mechanical crushing and precipitation treatment.

[Prior Art] Conventionally, an electron cyclotron resonance device (hereinafter referred to as rEcRJ) is known as a gas phase excitation device using microwaves. In this ECR, microwaves guided by a waveguide are introduced into a plasma generation chamber, which is a cavity resonator, through a microwave introduction part made of a microwave-transparent material such as quartz, and plasma is generated. (Japanese Unexamined Patent Publication No. 177975/1983). When this ECR is used, for example, for film formation, the plasma is further led to a collection chamber, where the raw material gas is brought into contact with the plasma, and the generated active particles are collected by adhering to the substrate surface.

[Problems to be Solved by the Invention] However, in the above ECR, since the microwave introduction part is exposed in the plasma generation chamber where plasma is generated, some of the active particles flowing back from the collection chamber are in an activated state. There is a problem that it can easily flow back into the microwave introduction section and become attached there. In addition, the size of the plasma generation chamber in ECR is determined by the microwave used, so the size of the plasma generation chamber can be changed by changing the plasma sending position, the distance from the source gas supply position to the microwave introduction part, etc. It cannot be adjusted and is inconvenient in terms of design.

[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. The present invention is to provide a gas phase excitation device having a wave antenna 2. Note that the microwave antenna l in the present invention refers to an antenna that sends out microwaves into free space.

[Function] The microwaves sent into the plasma generation chamber 3 via the microwave introduction section 1 are further sent out into the free space within the plasma generation chamber 3 via the microwave antenna 2.

In principle, the length of the microwave antenna 2 can be arbitrarily determined, so that it is possible to easily adjust the sending position of the plasma sent out from the microwave antenna 2 and the distance from the raw material gas supply position to the microwave introduction part l. I can do it.

On the other hand, inside the microwave antenna 2, it is easy to suppress the discharge of microwaves sent from the microwave introduction part l, and it is possible to suppress plasma generation inside the microwave antenna 2, especially near the microwave introduction part l. can. Therefore, some of the raw material gas and active particles are absorbed by the microwave antenna 2.
Even if the microwave backflows into the interior, by adjusting the length of the microwave antenna 2 and suppressing plasma generation, it is possible to prevent the microwave from flowing back into the microwave introducing section 1 with activity. Therefore, the active fine particles to be formed into a film will not adhere to the microwave introduction section 1 and the introduction of microwaves will not be hindered.

[Example] As shown in FIG. 1, a plasma generation chamber 3 that also serves as a collection chamber is provided with microwaves through a microwave introduction part l made of a material that can transmit microwaves, such as quartz. In order to introduce waves, a waveguide 4 whose tip is a microwave introduction part l is connected. A microwave antenna 2 is attached to the microwave introduction section 1 at the tip of the waveguide 4.

The microwave antenna 2 in this embodiment is generally referred to as a slot antenna, and usually has a slot 5 having a length of approximately the wavelength of the microwave in a direction perpendicular to the electric surface.
It is a cut. The slot 5 may be provided on only one surface as shown in FIG. 2(a), but may be provided across multiple surfaces as shown in FIG. 2(b). .

The microwave antenna 2 is provided with three stubs 6 and has a microwave power matching function.

It is preferable that the three stubs 6 have a choke structure shown in FIG. 3 in order to prevent the wall current from leaking to the outside. A short circuit plate 8 having a choke groove 7 on the circumferential surface is provided at the sliding contact part with the microwave antenna 2.
This is approximately % of the inner wavelength input.

As shown in FIG. 4, the microwave antenna 2 can also be a horn antenna whose tip is expanded into a trumpet shape. If this horn antenna is used as the microwave antenna 2, plasma can be sent out over a wide range.

The base of the microwave antenna 2, that is, the microwave introduction part l
Immediately after, a non-film-forming gas that does not produce a film-forming ability by itself can be supplied.

In front of the microwave antenna 2, raw material gas can be supplied. The raw material gas is ejected inward from a large number of holes formed on the inner periphery of the annular raw material gas supply pipe 9. A base body 10 is located behind the source gas supply pipe 9, and the inside of the plasma generation chamber 3 is evacuated from the rear side of the base body 10 by a vacuum pump.

While supplying a non-film-forming gas, microwaves are sent from the waveguide 4 through the microwave introduction part 1 into the microwave antenna 2, and when matching is achieved with the three stubs 6, the microwaves are sent out from the slot 5. As a result, plasma is generated in the vicinity. A raw material gas is supplied from the raw material gas supply pipe 9 and brought into contact with this plasma to generate active fine particles. The active fine particles flow toward the substrate 10 by the suction of the vacuum pump 11 together with the excited carrier gas, and the active particles flow toward the substrate 10.
The film is formed by adhering to the zero surface.

Next, other embodiments will be described.

In FIG. 5, 3 is a plasma generation chamber, 12 is a transport chamber,
13 is a collection chamber.

The plasma generation chamber 3 and the transport chamber 12 are configured as an integrated unit, and the transport chamber 12 includes a skimmer 14, a gate valve 15, and a collection chamber 13, which are also each unitized.
However, all flanges have a common diameter (hereinafter referred to as "common flange")
) are sequentially connected to each other so that they can be connected and separated. Plasma generation chamber 3, transport chamber 12 and collection chamber 13
In this case, the degree of vacuum is maintained at a high degree in steps from the plasma generation chamber 3 to the collection chamber 13 by an exhaust system to be described later.

A microwave antenna 2 similar to that described in FIGS. 1 to 4 is attached to one side of the plasma generation chamber 3 via a common flange.

A carrier gas supply valve 18 is connected to the base of the microwave antenna 2.
A source gas supply pipe 9 to which a source gas supply valve 17 is connected is located in front of the source gas supply pipe 9 .

Plasma is generated near the tip of the microwave antenna 2 by the discharge of the transmitted microwave, and when the raw material gas supplied from the raw material gas supply pipe 9 comes into contact with this plasma, active fine particles are generated. Then, the active fine particles flow into the contraction/expansion nozzle 18 together with the non-film forming gas and flow into the transport chamber 12.
It will be ejected to.

The contraction/expansion nozzle 18 is connected to the plasma generation chamber 3 of the transport chamber 12.
An inlet 18a is opened to the plasma generation chamber 3 and an outlet 18b is opened to the transport chamber 12 at the side end of the side, and the plasma generator is attached via a common flange so as to protrude into the plasma generation chamber 3. . However, the contraction/expansion nozzle 18 may be installed in a state in which it projects into the transport chamber 12.

The direction in which the contraction/expansion nozzle should be projected may be selected depending on the size, amount, properties, etc. of the particles to be transferred.

As shown in FIG. 6, the contraction/expansion nozzle 18 has an opening area gradually narrowed from the inlet 18a to the throat portion 1.
9, and the opening area gradually expands again to become the outlet 18b.
However, as shown in (a), it is preferable that the inner circumferential surface is approximately parallel to the central axis at the outlet 18b position. This is because the flow direction of the ejected non-film-forming gas and fine particles is influenced to some extent by the direction of the inner circumferential surface of the outlet 18b, so that it is possible to make the flow parallel to each other as easily as possible. However, (b
), if the angle α of the inner circumferential surface from the throat portion 19 to the outlet 18b with respect to the central axis is set to 7° or less, preferably 5° or less, the peeling phenomenon is less likely to occur and the non-formed film that spouts out. Since the gas and particulate flows are maintained substantially uniform, in this case they do not particularly need to be parallel as described above. By omitting the formation of the parallel portion, the contraction/expansion nozzle 18 can be manufactured easily. Also, the reduction/expansion nozzle 1
If 8 is made rectangular as shown in (C), non-film forming gas and fine particles can be ejected in a slit shape.

Here, the separation phenomenon is a phenomenon in which when there is a protrusion or the like on the inner surface of the reduction/expansion nozzle 18, the boundary layer between the inner surface of the reduction/expansion nozzle 18 and the flowing fluid becomes large, resulting in non-uniform flow. The faster 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 finish accuracy of the contraction/expansion nozzle 18 is inferior. The inner surface of the contraction/expansion nozzle 18 is JIS
80801, three or more inverted triangle marks indicating surface finish accuracy, optimally four or more are preferred.
In particular, since the peeling phenomenon at the enlarged part of the contraction/expansion nozzle 18 greatly affects the subsequent flow of non-film-forming gas and fine particles, by determining the finishing accuracy with emphasis on this enlarged part, it is possible to can be easily produced. Further, in order to prevent the occurrence of a peeling phenomenon, the throat portion 19 needs to have a smooth curved surface so that the differential coefficient in the rate of change in cross-sectional area does not become (1).

The contracting/expanding nozzle 18 has a pressure ratio P/Po between the pressure PO of the plasma generation chamber 3 and the pressure P of the transport chamber 12, and a ratio A/A of the opening area A'' of the throat portion 19 and the opening area A of the outlet 18b.
By adjusting ``, the flow of fine particles ejected together with the non-film-forming gas can be sped up.If the pressure ratio P/PO in the plasma generation chamber 3 and the transport chamber 12 is larger than the critical pressure ratio, the reduction and expansion The exit flow velocity of the nozzle 18 becomes subsonic flow, and the fine particles are decelerated and ejected together with the non-film forming gas.Also, if the pressure ratio is equal to or less than the critical pressure ratio, the exit flow velocity of the contraction/expansion nozzle 18 becomes a supersonic flow. Therefore, fine particles can be ejected at supersonic speed together with the non-film forming gas.

Here, the velocity of the particle flow is U, and the sound velocity at that point is a.
, the specific heat ratio of the particulate flow is γ, and assuming that the particulate flow is a compressible one-dimensional flow and adiabatically expanded, the Matsuha number M reached by the particulate flow can be 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 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='7112 Furthermore, the following relationship exists between the opening area A of the outlet 18b and the opening area A of the throat portion 19, and the Matsusha number M.

Therefore, the pressure P in the plasma generation chamber 3. and the pressure ratio P/PO of the pressure P in the transport chamber 12.
” By adjusting P/Pa according to M determined from equation (2), l'Jt from the enlargement/contraction nozzle 18
- The fine particles can be ejected as an appropriately expanded flow. The velocity U of the particle flow at this time can be determined by the following equation (3).

When the pressure ratio is less than the critical pressure ratio as mentioned above, the ejected non-film-forming gas and fine particles form a uniform diffusion flow, making it possible to uniformly spray the fine particles over a relatively wide area at once. Become.

When the fine particles are ejected in a fixed direction together with the non-film forming gas as a properly expanded flow at supersonic speed as described above, the non-film forming gas and the fine particles travel straight while almost maintaining the jet cross section immediately after being ejected, and are turned into a beam. Therefore, the flow of particles carried by this non-film-forming gas is also turned into a beam, and the flow of particles into the transport chamber 1 with minimal diffusion.
2 to the collection chamber 13 in a spatially independent state without interference with the wall surface of the transport chamber 12 and at supersonic speed.

As for the material of the contraction/expansion nozzle 18, a wide variety of materials can be used, such as iron, stainless steel, and other metals, as well as synthetic resins such as acrylic resin, polyvinyl chloride, polyethylene, polystyrene, and polypropylene, ceramic materials, quartz, and glass. . This material may be selected in consideration of non-reactivity with generated fine particles, workability, gas release properties in a vacuum system, etc. Also, the reduction/expansion nozzle 1
The inner surface of 8 can also be plated or coated with a material that is less likely to cause adhesion and reaction of fine particles. Specific examples include polyfluoroethylene coating.

The length of the contraction/expansion nozzle 18 can be arbitrarily determined depending on the size of the device and the like. By the way, when flowing through the contraction/expansion nozzle 18, the thermal energy of the non-film forming gas and the fine particles 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 non-film-forming gas contains condensed components, it is also possible to condense them by 1M in the supercooled state, thereby forming fine particles. Further, in this case, in order to achieve sufficient condensation, it is preferable that the contraction/expansion nozzle is used for a long day. On the other hand, when condensation occurs as described above, thermal energy increases and velocity energy decreases. Therefore, in order to maintain high-speed jetting, it is preferable that the contraction/expansion nozzle 18 be short.

The skimmer 14 connects the transport chamber 12 and the collection chamber I so that the collection chamber 13 can maintain a sufficiently higher degree of vacuum than the transport chamber 12.
This is to enable adjustment of the opening area between 3 and 3. Specifically, as shown in FIG. 7, two adjustment plates 21. each have a dogleg-shaped notch 20, 20'.
21'' is provided so that the notches 20 and 20' face each other so that they can slide past each other.This adjustment plate 2
1.21' can be slid from the outside, and the overlapping condition of both central portions 20 and 20' allows the beam to pass through and maintains a sufficient degree of vacuum in the collection chamber 13. It will be adjusted. Note that the notch 2 of the skimmer 14
The shapes of the 0.20' and adjustment plates 21.21'' may be semicircular or other shapes other than the illustrated shapes.

The gate valve 15 has a valve body 23 that can be raised and lowered by turning a handle 22, and is open when the beam is traveling. This gate valve 1
By closing 5, the unit of the collection chamber 13 can be replaced while maintaining the degree of vacuum in the plasma generation chamber 3 and the transport chamber 12. In addition, in the apparatus of this embodiment, fine particles are collected in the collection chamber 13, but if the gate valve 15 is a pole valve etc., this pole valve can be used especially when the fine particles are metal fine particles that are easily oxidized. By simultaneously replacing the unit of the collection chamber 13, there is an advantage that the unit can be replaced without the risk of rapid oxidation.

A base body 10 is located within the collection chamber 13 for receiving and depositing fine particles transferred as a beam, and collecting the fine particles in a film-formed state. This base body 10 is attached to the collection chamber 13 via a common flange, and is attached to a base body holder 26 at the tip of a rod 25 that can be slid back and forth by a cylinder 24. The substrate holder 26 is capable of heating or cooling the substrate 10 under optimal temperature conditions for collecting fine particles. Furthermore, a shutter 27 is located in front of the base body 10.

Incidentally, glass windows 28 are attached to the upper and lower sides of the plasma generation chamber 3 and the collection chamber 13 through common flanges, respectively, as shown in the figure, so that the inside can be observed. In addition, a plasma generation chamber 3, a transport chamber 12, and a collection chamber 13
Similar glass windows 28 are attached to the front and rear of the frame via common flanges. These glass windows 28 and 29 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 plasma generation chamber 3 is connected to a main valve 31a via a pressure regulating valve 30. The transport chamber 12 is directly connected to the main valve 31a.
a is connected to a vacuum pump lla. The collection chamber 13 is connected to a main valve 31b, and this main valve 31b is further connected to a vacuum pump llb. In addition, 32a and 32b are the main valves 31a and 32b, respectively.
There are parallel valves 33a and 33b immediately upstream of 31b.
and an auxiliary valve 34a,
A vacuum pump connected to the vacuum pump lla via 34b is used to check the inside of the plasma generation chamber 3, transport chamber I2, and collection chamber 13. In addition, 35a to 35f are the respective chambers 3, 12.13 and the pump 11a.

11b, 32a, and 32b are leak and purge valves.

First, the interference valves 33a, 33b and the pressure regulating valve 3
0 is opened, and the insides of the plasma generation chamber 3, transport chamber 12, and collection chamber 13 are checked using the vacuum pumps 32a and 32b.

Next, the auxiliary valves 34a, 34b and the main valves 31a, 3 are closed.
1b is opened and vacuum pumps lla and llb are used to create a sufficient degree of vacuum in the plasma generation chamber 3, transport chamber 12, and collection chamber 13. At this time, by adjusting the opening degree of the pressure control valve 30, the degree of vacuum in the transport chamber 12 is made higher than that in the plasma generation chamber 3, and then the non-film-forming gas and source gas are flowed, and then collected from the transport chamber 12. The skimmer 14 is used to adjust the degree of vacuum in the chamber 13 to be high. This adjustment is performed by the main valve 31a
, 31b can also be adjusted. Each chamber 3, 12, 13 is controlled to maintain a constant degree of vacuum throughout the formation of fine particles and the film forming operation by beam injection. This control may be done manually, but each room 3.1
2.13 may be detected and the pressure regulating valve 30, main valves 31a, 31b, skimmer 14, etc. may be automatically opened and closed based on the detected pressure. If the non-film-forming gas supplied to 3 and the generated active particles are directly transferred to the downstream side via the contraction/expansion nozzle 18, the exhaust gas during transfer will be transferred to the downstream side, that is, the transport chamber. 12 and collection chamber 13 only.

The degree of vacuum may be controlled by separately providing vacuum pumps lla for the plasma generation chamber 3 and transport chamber 12 for each chamber 3 and 12, but as in this embodiment,
Exhaust in the direction of beam flow with one vacuum pump lla,
By controlling the degree of vacuum in the plasma generation chamber 3 and transport chamber 12, even if there is some pulsation in the vacuum pump lla,
There is an advantage that it is easy to keep the pressure difference between the two constant, and therefore it is easy to keep the flow state, which is susceptible to fluctuations in this differential pressure, constant.

The suction by the vacuum pumps lla and llb is preferably performed from above, especially in the transport chamber 12 and the collection chamber 13. By suctioning from above, it is possible to prevent the beam from falling due to gravity to some extent.

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

First, the contraction/expansion nozzle 18 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. 6(C).

It is also possible to irradiate the flow with light having various wavelengths such as ultraviolet, infrared, and laser light by forming at least a part of the contraction/expansion nozzle 18 into a transparent material (-).
It is also possible to provide a plurality of beams B and generate a plurality of beams at once. In particular, when a plurality of contraction/expansion nozzles 18 are provided, by connecting each to an independent plasma generation chamber 3, beams of different particles can be run simultaneously, and different particles can be layered or mixed and collected. It is also possible to form new particles by collision of different particles by crossing the beams.

In this embodiment, the plasma generation chamber 3. Although it is composed of a transport chamber 12 and a collection chamber 13, it is possible to omit the transport chamber 12 or
It is also possible to further connect second, third, . . . transport chambers 12, 12, etc. to the downstream side of the transport chamber 12.

Furthermore, by pressurizing the plasma generation chamber 3, the transport chamber 12 and below can be made into an open system, and by reducing the pressure in the transport chamber 12 and below, the plasma generation chamber 3 can be made into an open system. In particular, like an autoclave, the plasma generation chamber 3 can be pressurized and the transport chamber 12 and below can be depressurized.

It is also possible to provide a valve for opening and closing the contraction/expansion nozzle 18, and to obtain fine particles by intermittently opening and closing the valve while temporarily storing fine particles and non-film-forming gas in the plasma generation chamber 3 side. By opening and closing the valve in synchronization with the energy application performed on the downstream side including the throat portion 19 of the contraction/expansion nozzle 8, the load on the exhaust system can be significantly reduced, and the pulse can be made while effectively utilizing the raw material gas. It is possible to obtain a particle flow of .

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 addition, a plurality of contraction/expansion nozzles 18 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, when forming a film using gas phase excitation using microwaves, even if there is some backflow of raw material gas or active particles, they will not adhere to the microwave introduction part. Therefore, even if the microwave is operated continuously for a long period of time, excitation failure due to fine particles adhering to the microwave introduction part is less likely to occur, and film formation can be performed efficiently. In addition, it is easy to adjust the plasma generation position, and it is easy to prevent waste of raw material gas.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of an embodiment of the present invention, FIG. 2(a),
3(b) is an enlarged perspective view of the tip of an example of the microwave antenna, FIG. 3(a) is a vertical cross-sectional view of another example of the microwave antenna, and FIG. 3(b) is an explanatory diagram of its choke structure.
FIG. 4 is a vertical cross-sectional view showing another microwave antenna,
FIG. 5 is an explanatory diagram showing another embodiment of the present invention, and FIG.
) to (C) are diagrams each showing an example of the shape of a reduction/enlargement nozzle, and FIG. 7 is an explanatory diagram of a skimmer. 2 microwave introduction section, 2 microwave antenna, 3: plasma generation chamber, 4: waveguide, 5 slot, 6: three stub, 7: choke groove, 8: shorting plate, 9: source gas supply pipe, 10: Substrate, 11, lla, Ilb: Vacuum pump, 12: Transport chamber, 13: Collection chamber, 14: Skimmer, 15: Gate valve, 16: Non-film forming gas supply valve, 17: Raw material gas supply valve, 18 : Reduction and expansion nozzle, 18a: Inlet, 18b = Outlet, 18: Throat, 20, 20': Notch, 21.21': Adjustment plate, 2
2: Handle, 23: Valve body, 24 Niji cylinder-125:
Rod, 26: Substrate holder, 27: Shutter, 28, 29 double glass window, 30: Pressure adjustment valve, 31a, 31b: Main valve, 32a,
32b: Decompression pump, 33a, 33b: Arabiki valve, 34a, 34b: Auxiliary valve, 35a to 35f: Leak and purge valve.

Claims (1)

[Claims] 1) A gas phase excitation device characterized by having a microwave antenna in a microwave introduction section.