JPS62247836A - Gaseous phase exciter - Google Patents

Abstract

PURPOSE:To transfer a gas at an accurately controlled supersonic speed by providing a nozzle at the tip of an induction pipe for supplying a plasma forming gas, and furnishing an exciting means for exciting the gas in the induction pipe. CONSTITUTION:The plasma forming gas is supplied into the induction pipe 2, a downstream chamber 4 on the downstreamside of the nozzle 1 is evacuated by a vacuum pump 5, and hence a difference in the pressure between the upstream side and the downstream side of the nozzle 1 is caused. Accordingly, the supplied plasma forming gas passes through the nozzle 1 from the induction pipe 2, and flows into the downstream chamber. Since the plasma forming gas supplied in the induction pipe 2 is excited by the exciting means 3, gaseous plasma is blown off from the nozzle 1. When the gas is blown off from the nozzle 1, the blowing region is throttled by the nozzle 1, and the gas can be blown off at a high speed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a gas phase excitation device used for film formation, etching, doping, surface modification, and the like.

[Prior Art] Conventionally, as a gas phase excitation device, a box-shaped cavity resonator is capable of injecting microwave waves through a window made of quartz or the like that can transmit microwaves, and electronic cyclotron resonance is generated. There are known devices that can be used to form plasma. When this apparatus is used for film-forming processing, etc., processing chambers are connected, and plasma induced in the cavity resonator is sent to the processing chambers using an electromagnet.

[Problems to be Solved by the Invention] However, in the conventional device described above, the plasma is sent out through a mere opening formed in the cavity resonator, so the sent out plasma is in a diffused state. , precise plasma spraying is difficult to control over the area. Furthermore, since the plasma delivery speed cannot be made very high, the short-lived active species tend to lose their activity before reaching the processing position, and furthermore, a box-shaped cavity resonator and electromagnet are required. Therefore, there is also the problem that the device becomes large.

[Means for solving the problems] The means taken to solve the above problems will be explained with reference to FIG. 1, which corresponds to an embodiment of the present invention.
A nozzle 1 is provided at the tip of the guide tube 2 to which plasma forming gas is supplied, and an excitation means 3 for exciting the gas within the guide tube 2 is provided.

The nozzle 1 in the present invention refers to, for example, a parallel tube nozzle, a tapered nozzle, a contracting/expanding nozzle, or the like. In addition, a contraction/expansion nozzle is a nozzle that gradually opens from the inlet 1d toward the middle part.
This refers to a nozzle in which the area is narrowed to form a throat 1b, and the area of the opening 11 gradually increases from this throat 1b toward the outflow [11c].

In the present invention, gas is a general term for not only gas but also anything that can be transported substantially as a gas phase flow, such as a suspension of fine particles such as droplets or powder in gas.

Further, in the present invention, the excitation means 3 may be any device that can excite the plasma forming gas to turn it into plasma, and may be excited by microwaves, which will be described later, as well as other electromagnetic waves, ultraviolet light, infrared light, and visible light.

Light of various wavelengths such as laser light, electron beam, etc. may be irradiated.

[Function] For example, as shown in FIG.
When the inside of the flow chamber 4 is evacuated by the vacuum pump 5, a pressure difference is generated between the upstream side of the nozzle I and the F flow side. Therefore, the supplied plasma forming gas flows through the nozzle 1 from the guide pipe 2 and flows into the downstream chamber 4 .

By the way, since the plasma forming gas supplied into the guide tube 2 is excited within the guide tube 2 by the excitation means 3,
” - From the nozzle 1, plasma gas is ejected. If this plasma gas is ejected from the nozzle 1, the ejection area can be narrowed by the nozzle 1, and the gas can be ejected at high speed. In addition, the guide tube 2
A resonator is literally a circular or rectangular tube that guides and guides gas efficiently, and because it is not box-shaped like a cavity resonator, the device can be made smaller.

] - When a contracting/expanding nozzle is used as the nozzle 1, the pressure Po on the L flow side and the pressure P on the downstream side ftP/P
By adjusting o in accordance with the ratio A/A'' of the opening area A' of the throat portion 1b and the opening area A of the outlet IC, the flow of ejected particles can be increased to supersonic speed.

Here, if we assume that the velocity of the flowing gas is U, the ff speed at that point is a, and the specific heat ratio of the gas flow is γ, and that the gas flow is a compressible one-dimensional flow and expands adiabatically, then the gas flow reaches The Matsuha number M is determined by the following formula from the pressure Po in the upstream chamber and the pressure P in the downstream chamber. In particular, 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.

In addition, the following relationship exists between the opening area A of the outflow opening 10 and the opening area A of the throat 1b and the Matsuhaka number M.

Therefore, by adjusting the pressure ratio P/PO according to M determined from equation (2) based on the opening area ratio A/A,
The gas ejected from the nozzle can be ejected as a supersonic expansion flow. This proper expansion flow is a flow in which the pressure of the gas flow at the outlet IC is equal to the pressure P on the downstream side, and the velocity U of the gas flow at this time is - If the temperature on the flow side is TO, then C3) It can be obtained by formula.

When gas is ejected in a fixed direction as a properly expanded flow at supersonic speed as described in L, the gas flow travels straight while maintaining almost the jet cross section immediately after ejection, and becomes a beam. Therefore, the gas is transported 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 supersonic speed. This facilitates control of the area and long-distance transport of active species.

[Example] As shown in FIG. 1, an inlet 1a of a nozzle 1 is connected to one end of a guide tube 2 to which plasma forming gas is supplied from the other end, and an outlet 1c is connected to a downstream Chambers 4 are connected.

A waveguide is provided as an excitation means 3 at the center of the guide tube 2, intersecting with the guide tube 2. On the distal end side of the excitation means 3, the guide tube 2 can be moved by sliding inside the excitation means 3.
A regulating plate 6 is provided therein to efficiently form plasma. This excitation means 3 excites the gas in the guide tube 2 with microwaves, and in particular, when excitation is performed with microwaves, instead of the waveguide as in this embodiment,
A coaxial waveguide may also be used. The former is suitable for high energy input, and the latter is suitable for low energy input.

The guide tube 2 is made of an insulating material that can transmit microwaves, such as quartz, so that the microwaves sent by the excitation means 3 can be guided inside to form plasma. . However, the entire guide tube 2 need not be made of the above-mentioned insulating material, but only the portion intersecting with the excitation means 3 may be made of the above-mentioned insulating material.

Furthermore, when using light, electron beams, etc. for excitation, these sources may be built-in or may be made of a transparent material.

The inside of the downstream chamber 4 can be evacuated by a vacuum pump 5, and a base body 7 is provided in the downstream chamber 4 at a position opposite to the outlet 1c of the nozzle 1.

According to this device, plasma can be formed in the guide tube 2, and this can be sent directly to the substrate 7 as a jet through the nozzle 1, and can be used for film formation, etching, surface modification, doping, etc. on the substrate 1. It can be performed. The plasma-forming gas may be any gas that can be excited by microwaves or other energy and turned into plasma, and may be selected depending on the application. Specifically, when forming a film, for example, silicon hydrides such as silane, disilane, and trisilane, hydrocarbons such as methane, ethane, propane, and acetylene, aromatic hydrocarbons such as benzene, toluene, and xylene, and tetrafluorocarbons are used. Methane, tetrachloromethane, CH2
Film-forming gases such as halogenated hydrocarbons such as F2 and CHsF, and mixed gases of the above-mentioned film-forming gases and non-film-forming gases such as hydrogen, argon, helium, and nitrogen are used. In addition, when performing etching, for example, tetrafluoromethane, tetrachloromethane, 0H2F2, C)
Halogenated hydrocarbons such as 13F, S F 6+ N
An etching gas such as a fluoride such as F 3 or a mixed gas of the above-mentioned etching gas and an additive gas for improving etching selectivity such as oxygen, hydrogen, or nitrogen is used.

When a contracting/expanding nozzle is used as the nozzle l, as described above, the opening area is gradually narrowed from the inlet 1a to become the throat part 1b, and the opening area is gradually expanded again to become the outlet 1c.
However, as shown in an enlarged view in FIG. 2(a), it is preferable that the inner circumferential surface near the outlet IC be substantially parallel to the central axis. this is,
Since the flow direction of the ejected gas is influenced to some extent by the direction of the inner circumferential surface near the outlet IC, this is to make the flow as parallel as possible to facilitate speed control. However, as shown in FIG. 2(b), the angle α of the inner peripheral surface from the throat portion 1b to the outlet 1c with respect to the central axis is 7°.
Preferably, if the angle is 5° or less, peeling phenomenon is less likely to occur and the flow of ejected gas is maintained almost uniformly.
In this case, it is not necessary to form the above-mentioned parallel portion.

By omitting the formation of the parallel portion, it becomes easy to manufacture the contraction/expansion nozzle. In addition, the contraction/expansion nozzle is shown in Figure 2 (C
) If the shape is rectangular as shown in ), gas can be ejected in a slit shape.

Here, the above-mentioned separation phenomenon refers to a phenomenon in which when there is a protrusion on the inside of the contraction/expansion nozzle, the boundary layer between the inside of the contraction/expansion nozzle and the flowing gas becomes large, resulting in uneven flow. Yes, the faster the jet flow, the more likely it is to occur. In order to prevent this peeling phenomenon, it is preferable that the above-mentioned angle α is made smaller as the inner surface finishing precision of the contraction/expansion nozzle is inferior. The inner surface of the contraction/expansion nozzle has three or more inverted triangular marks representing surface finish accuracy defined in JIS B 0801.4-1 Optimally, four or more are preferred. In particular, since the peeling phenomenon in the enlarged part of the contraction-expansion nozzle greatly affects the subsequent gas flow, by determining the finishing accuracy with emphasis on this enlarged part, the production of the contraction-expansion nozzle can be facilitated. Further, in order to prevent the occurrence of a peeling phenomenon 1F, the throat portion 1b needs to have a smooth curved surface so that the differential coefficient in the rate of change in cross-sectional area does not become unsightly.

Materials for the nozzle l include, for example, iron, stainless steel and other metals, as well as acrylic resin, polyvinyl chloride,
A wide variety of materials can be used, including synthetic resins such as polyethylene, polystyrene, and polypropylene, ceramic materials, quartz, and glass. This material may be selected in consideration of non-reactivity with flowing gas, workability, gas release properties in a vacuum system, etc. Furthermore, the inner surface of the nozzle 1 can be coated or coated with a material that is less likely to react with deposits or gas. A specific example is a coating of polyethylene ethylene.

The length of the nozzle l can be arbitrarily determined depending on the size of the device and the like. By the way, when the gas flows through the nozzle 1, the thermal energy it possesses is converted into kinetic energy. In particular, when ejecting at a sonic speed using a contraction/expansion nozzle, the thermal energy becomes extremely small, resulting in a supercooled state.

Therefore, when condensed components are contained in the gas stream passing through, it is also possible to actively condense them by the supercooled state and thereby form fine particles. Further, in this case, in order to perform 1-minute condensation, it is preferable that the contraction/expansion nozzle be long. On the other hand, when condensation occurs as described above, thermal energy increases and velocity energy decreases. Therefore, in order to maintain high-speed ejection, it is preferable that the contraction/expansion nozzle be short.

FIG. 3 shows another embodiment of the present invention, in which the guide tube 2 described in FIG. 1 is housed in a four-flow chamber 8. Note that the same reference numerals as in FIG. 1 indicate the same members (same also in FIG. 4 and subsequent figures). In this way, the plasma formation position is covered by the flow chamber 8, so that the safety in operating the apparatus can be improved.

In the device shown in FIG. 4, an inner tube 9 made of a conductive material or an insulating material that does not transmit microwaves is inserted into the guide tube 2, and the guide tube 2 portion has a double tube structure. . Then, an inactive plasma forming gas is supplied between the guide tube 2 and the inner tube 9, and an active gas is supplied into the inner tube 9, and the two merge from the inlet 18 of the nozzle l. It is intended to be ejected into the downstream chamber 4. Here, the above-mentioned inactive plasma-forming gas refers to a gas that does not cause any substances to adhere to the device wall surface even if it is turned into plasma, and specifically refers to the non-film-forming gas and the addition of etching selectivity. gas etc. Further, the active gas refers to a gas that can cause substances to adhere to the wall surface of the apparatus when turned into plasma, and specifically includes the film forming gas, etching gas, and the like.

1- By doing as described above, the plasma formed by the inactive plasma forming gas comes into contact with the active gas after the nozzle 1, so that it can be activated and sent to the base 7. That is, if the guide tube 2 is made of a conductive material, microwaves will be blocked, and even if it is made of an insulating material, most of the microwaves will be absorbed by the plasma forming gas around the guide tube 2. Since activation of the active gas within the guide tube 2 is unlikely to occur, there is no possibility that deposits will form on the inner wall of the guide tube 2 and prevent the introduction of microwaves. Also, inside the nozzle l, the gas flow becomes a high-speed flow, so
Adherence to the inner surface of the nozzle 1 is less likely to occur.

FIG. 5 shows the guide tube 2 shown in FIG. 4 housed in the -L flow chamber 8 to improve safety during operation.

The one shown in FIG. 6 has a large diameter inner tube 9 and a nozzle l.
A communication hole is connected to the inlet 1a of the nozzle 1, and the guide tube 2 is also made large in diameter and extends so that the tip thereof covers the outer periphery of the nozzle 1, and further opens into the acceleration region on the inlet 1a side from the throat 1b of the nozzle 1. 10 is provided to communicate between the guide pipe 2 and the inside of the nozzle 1. In this way, the position where the active gas comes into contact with the plasma will be the region where the flow velocity within the nozzle 1 is relatively high, and the generation of deposits on the inner surface of the nozzle 1 can be further prevented. It becomes easier. Furthermore, since the activation position of the active gas is closer to the base 7, it becomes easier to maintain its activity.

In FIG. 7, the guide pipe 2 shown in FIG. 6 is housed in the upstream chamber 8 to improve operational safety.

In what is shown in FIG. 8, the guide pipe 2 is further extended toward the downstream chamber 4, and its tip is opened at the outlet IC portion of the nozzle l. In this way, the plasma can be brought into contact with the active gas ejected as a beam stream from the nozzle 1, and the generation of deposits within the nozzle 1 can be reliably prevented. Furthermore, the activation position of the active gas is closer to the base 7, making it extremely easy to maintain a good activated state.

In FIG. 9, the guide pipe 2 shown in FIG. 8 is housed in the upstream chamber 8 to improve operational safety.

FIG. 1θ shows a state in which the tip of the guide tube 2 shown in FIG. 8 is extended further downstream, and a nozzle 1' is formed at the tip. In particular, if this nozzle 1' is a contraction/expansion nozzle, both the plasma forming gas and the active gas can be made into a beam and sprayed onto the substrate 7.

In FIG. 11, the guide tube 2 shown in FIG. 10 is housed in the upstream chamber 8 to improve operational safety.

Next, an example of a film forming apparatus using the present invention will be explained with reference to FIG.

In the figure, 1 is the nozzle, 8 is the upstream chamber, 4a is the first downstream chamber, 4b
is the second downstream chamber.

The upstream chamber 8 and the first downstream chamber 4a are configured as an integrated unit, and the skimmer 11, gate valve 12, and second downstream chamber 4b, which are also each unitized, are all common to the first downstream chamber 4a. They are sequentially connected to each other so that they can be connected and separated via a diameter flange (hereinafter referred to as a "common flange"). The first downstream chamber 4a and the second downstream chamber 4b are
A high degree of vacuum is maintained in stages from the first downstream chamber 4a to the second downstream chamber 4b by an exhaust system to be described later.

A guide tube 2 for introducing plasma forming gas through the upstream chamber 8 is connected to the nozzle 1, and furthermore, an excitation means 3 for injecting microwaves into the guide tube 2 is installed to intersect with the guide tube 2. ing.

The gas introduced into the guide tube 8 is turned into plasma by the microwave, and is transferred to the first downstream chamber 4a in a high degree of vacuum.
The pressure difference causes the liquid to flow through the nozzle l.

The pressure ratio in the guide pipe 2 and the first downstream chamber 4a, and the throat part 1
Ratio A/A of the opening area a of b and the opening area of the outlet 1c
From the relationship, the gas jet stream is formed into a beam and flows at supersonic speed from the first downstream chamber 4a to the second downstream chamber 4b.

The skimmer 11 is installed in the first downstream chamber 4 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 the opening area between the second downstream chamber 4b and the second downstream chamber 4b to be adjusted. Specifically, as shown in FIG. 13, two adjustment plates 14.14', each having a letter-shaped notch 13.13', are slid together with their cutout centers 13.13' facing each other. This has been made possible. This adjustment plate 14° 14' can be slid from the outside, and allows the beam flow to pass through depending on the overlap between the two central portions 13 and 13', and maintains a sufficient degree of vacuum in the second downstream chamber 4b. The degree of opening can be adjusted as desired. Note that the notch 13.13' of the skimmer 11 and the adjustment plate 14.
．． In addition to the illustrated shape, the shape of 14' may be semicircular or other shapes.

The gate valve 12 has a weir-shaped valve body 16 that is raised and lowered by turning a handle 15, and is opened when the beam is traveling. This gate valve 1
By closing 2, the unit in the second downstream chamber 4b can be replaced while maintaining the degree of vacuum in the first downstream chamber 4a. In addition, in the apparatus of this embodiment, gas is used for film formation in the second downstream chamber 4b, but if the gate valve 12 is a pole valve or the like, especially when the film is a metal film that is 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 7 is located in the second downstream chamber 4b for receiving the gas transferred as a beam and forming a film thereon. This base body 7 is attached to the first downstream chamber 4a via a common flange, and is attached to a base body holder 18 at the tip of a slide shaft 18 that is slid by a cylinder 17. A shutter 20 is located on the entire surface of the base 7, so that the beam can be blocked whenever necessary. Further, the substrate holder 19 is capable of heating or cooling the substrate 7 under optimum temperature conditions for film formation.

Note that the 1-stream chamber 8 and the first and second downstream chambers 4a, 4
As shown in the figure, a glass window 21 is attached to each part via a common flange, so that the inside can be observed. By removing these glass windows 21, various measuring devices,
The load lock chamber etc. can be replaced.

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

The first downstream chamber 4a is connected to a main valve 22a, and this main valve 22a is connected to a vacuum pump 5a. The second downstream chamber 4b is connected to a main valve 22b, and this main valve 22b is further connected to a vacuum pump 5.
connected to b. Note that 23a and 23b are connected to the immediate upstream side of main valves 22a and 22b, respectively, via row valves 24a and 24b, and
This is a roughing pump connected to the vacuum pump 5a via auxiliary valves 25a and 25b, and is used to check the inside of the first downstream chamber 4a and the second downstream chamber 4b.

Note that 26a to 26g are leak and purge valves.

First, open the control valves 24a and 24b and
And the second downstream chambers 4a, 4b are checked by the check pumps 22a, 22b. Next, the Arabiki valve 2
4a, 24b are closed, the auxiliary valves 25a, 25b and the main valves 22a, 22b are turned on, and the first and second downstream chambers 4a, 4b are brought to a 1-minute vacuum level using the vacuum pumps 5a, 5b. Next, a plasma-forming phase gas is caused to flow, and the skimmer 11 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 valves 22a, 22b. During the film forming operation by activating the gas and injecting it into a beam, the first and second downstream chambers 4a, 4b are opened.
is controlled to maintain a constant degree of vacuum. This control may be done manually, but the pressure in the first and second downstream chambers 4a, 4b is detected and the main valve 22 is controlled based on the detected pressure.
A, 22b, skimmer 11, etc. may be automatically opened/closed.

The suction by the vacuum pumps 5a, 5b is preferably performed from above. By suctioning from above, it is possible to prevent the beam from falling due to gravity to some extent.

The nozzle 1 can be tilted vertically, horizontally, and scanned at regular intervals, and can also be configured to form a film over a wide range. Especially this tilting and scanning,
It is advantageous to combine it with the rectangular nozzle of FIG. 2C.

It is also possible to form the nozzle 1 from a transparent material and irradiate the flow with light having various wavelengths such as ultraviolet, infrared, and Caesar light. It is also possible to provide a plurality of nozzles 1 to generate a plurality of beams at a time. In particular, when a plurality of nozzles 1 are provided, by connecting each nozzle to an independent guide pipe 2, beams of different gases can be run simultaneously, and fine layers or mixed collection of different films or substances can be performed. By crossing the beams, it is also possible to form new substances through collisions between different gases.

The base body 7 is held movably or rotatably in the vertical and horizontal directions,
It is also possible to receive the beam over a wide range. Further, it is also possible to process a long substrate 6 by winding the substrate 7 into a roll and sending it out one after another so as to receive the beam. Furthermore, the treatment may be performed while rotating the drum-shaped base 7.

In this embodiment, it is composed of an upstream chamber 8, a first downstream chamber 4a, and a second downstream chamber 4b, but the second downstream chamber 4b may be omitted, or a third downstream chamber and a four······
Downstream chambers can also be connected. Furthermore, by pressurizing the inside of the guide tube 2, the first downstream chamber 4a can be made into an open system.
In particular, like an autoclave, the inside of the guide tube 2 is pressurized and $
- It is also possible to reduce the pressure in the downstream chamber 4a and below. In such a usage mode, it is preferable to provide an upstream chamber 8 for safety in case the guide pipe 2 is damaged. In addition, it is also preferable from the viewpoint of safety to make the inside of the upstream chamber 8 pressurized or depressurized so that the pressure inside the guide pipe 2 and the external pressure are balanced.

[Effects of the Invention] According to the present invention, gas can be transported spatially independently as a uniformly dispersed supersonic beam, so gas can be transported under accurate supersonic velocity control. be able to. Therefore, the active gas can be reliably transported as it is 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 each component in the beam becomes a frozen state, so new reaction field using these We also have great expectations that we will be able to obtain the following. Furthermore, according to the present invention, since the frozen state is achieved, the microscopic state of molecules in the fluid is defined,
It is also possible to handle transitions from one state to another.

In other words, it also defines the various energy levels of molecules,
It is possible to perform chemical reactions in the gas phase using a new method of imparting energy corresponding to that level. Furthermore, by providing a field for energy exchange different from conventional ones, it is also possible to easily create intermolecular compounds formed by relatively weak intermolecular forces such as hydrogen bonds and van der Waals bonds.

In addition, since activation is performed using a guide tube, there is no need to separately provide a large gas phase excitation device unlike conventional devices, and the entire device can be made considerably smaller. Since the particles are transferred in the form of a beam without being diffused, high-speed and highly efficient flow control can be achieved.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of one embodiment of the present invention, and FIGS. 2(a) to (
C) is a diagram showing an example of the shape of a reduction/enlargement nozzle, FIGS. 3 to 11 are explanatory diagrams of other embodiments of the present invention, and FIG.
Figure 2 is a diagram showing an example of a film forming apparatus using the present invention.
Figure 3 is an explanatory diagram of the skimmer. l: contraction/expansion nozzle, la: inlet, lb: throat, IC: outlet, 2: guide tube. 3: Microwave supply means, 4: Downstream chamber, 5; Pump, 6
: adjustment plate, 7-substrate, 8: upstream chamber, 9: inner pipe, 10: communication hole.

Claims (1)

[Claims] 1) A gas phase excitation device characterized in that a nozzle is provided at the tip of a guide tube to which plasma forming gas is supplied, and an excitation means for exciting the gas in the guide tube is provided.