JPS62120477A - Film forming device - Google Patents

Abstract

PURPOSE:To control the region and form of plasma and to obtain a good film forming condition by impressing a voltage to a nozzle disposed in a film forming gas flow passage and forming an electric field between the nozzle and a plasma generator by the microwaves on the upper stream side thereof. CONSTITUTION:This film forming device is constituted by connecting a plasma chamber 4 disposed with the plasma generator 2 provided with a cavity resonator 6 having a waveguide 8 and microwave introducing window 7 and having an opening 9 and a film forming chamber 5 disposed with a substrate 12 by the nozzle 1 of a reducing and expanding type. A non-film forming gas is supplied into the cavity resonator 6 of the above-mentioned device and at the same time the microwaves are introduced therein to generate the plasma which is delivered from the opening 9. The plasma is supplied together with the film forming gas from a supply ring 10 via the nozzle 1 into the film forming chamber 5. The voltage is at the same time impressed from a power source 3 to the above-mentioned nozzle 1 to form the electric field between the plasma generator 2 on the upper stream side thereof and the nozzle 1. The plasma is thereby effectively converged and the good film formation is executed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a film forming apparatus that utilizes plasma generated by microwave discharge, and more particularly to improving the utilization efficiency of plasma and film forming gas.

[Conventional technology] Conventionally, a film forming apparatus that uses plasma generated by microwave discharge uses an electromagnet to send the plasma generated in a plasma generator using a cavity resonator to a film forming chamber, where the film forming gas is A method is known in which a film is formed on a substrate by bringing it into contact with plasma.

[Problems to be Solved by the Invention] However, when sending out plasma using an electromagnet, it is difficult to sufficiently control the area of the sent plasma, and there is a problem in that the contact of the film forming gas is likely to be uneven. Furthermore, it is difficult to control the form of the extracted plasma, such as the concentration and type of ions and radicals, and it is also difficult to control the plasma depending on the type of film-forming gas.

[L stage to solve the problem] The L stage taken in the present invention to solve the above problem will be explained with reference to FIG. 1, which corresponds to an embodiment of the present invention. The purpose of the present invention is to provide a film forming apparatus having a plasma generating device 2 using microwaves, which forms an electric field between the nozzle 1 and the nozzle 1, on the h flow side of the nozzle 1 capable of applying a voltage.

[Function] The plasma generated by the plasma generator 2 is drawn toward the nozzle 1 by an electric field formed between the plasma generator 2 and the nozzle 1 located on the downstream side thereof. Since the plasma is drawn out in a limited direction L7, the drawing area can be controlled extremely easily. Therefore, it is easy to bring the film-forming gas into contact with the plasma, and uniform and efficient contact is possible.

On the other hand, the form of the plasma can be controlled by applying a positive or negative voltage to the nozzle 1 using the power source 3 as a direct current, or by alternately applying positive and negative voltages using the power source 3 as an alternating current. be. Furthermore, by generating a discharge between the plasma generator 2 and the nozzle l, plasma formation can be promoted.

[Example] As shown in FIG. 1, a plasma chamber 4 and a film forming chamber 5 are communicated through a nozzle l.

In the plasma chamber 1, a plasma generator 2 is provided at a position facing the inlet 1d of the nozzle 1. The plasma generator 2 in this embodiment has a cavity resonance 'X6 that forms a 2-'' plasma using electric f-cyclotron resonance (EGR).
The resonator 6 is equipped with EC so that plasma can be formed efficiently.
It is preferable that the R condition is satisfied.

A waveguide 8 is connected to the rear wall of the cavity resonator 6 via a microwave introduction window 7 formed of a material such as quartz that allows microwave transmission. Furthermore, non-film-forming scum is supplied into the cavity resonator 6. Here, □j [Sei 11! ,! The gas refers to a gas that is turned into plasma by microwave discharge, and does not produce a film-forming ability by itself. Specifically, for example, N2. , N2. It is a gas such as Ar.

When a non-film-forming gas is supplied into the cavity resonator 6 and microwaves are introduced through the microwave introduction window 7, plasma is formed within the cavity resonator 6, and this is drawn out from the opening 9 on the front surface. It turns out.

A supply ring 10 for supplying film-forming gas is located between the opening 9 of the cavity resonator 6 and the inflow +2]la of the nozzle 1. The supply ring 10 is an annular pipe having a large number of small holes, and supplies the film forming gas toward the plasma extracted from the cavity resonator 5.

Here, the film-forming gas is a gas that produces a film-forming ability when activated, and is, for example, disilane gas.

The nozzle l has its inlet port 1a opened into the plasma chamber 4, and its outflow port o1b opened into the film forming chamber 5, thereby communicating the two chambers 4.5. A power source 3 is connected to this nozzle l, so that an electric field can be formed between the nozzle l and the plasma generator 2.

Further, an insulating material 11 is interposed between the attachment parts of the nozzle 1 to the plasma generation chamber 4 and the film forming chamber 5, respectively, to provide electrical insulation, while the plasma chamber 4 and the film forming chamber 5 are Each of them is grounded. The illustrated power supply 3 is a direct current and is capable of applying a positive voltage to the nozzle 1, but a negative upper pressure may be applied to the nozzle 1, or the power supply 3 may be an alternating current. .

The plasma generated by the plasma generator 2 is actively drawn toward the nozzle 1 by the electric field between the nozzle 1 and the plasma generator 2, and a film forming gas is supplied to it from the supply ring 10. The supplied film-forming gas is activated by contacting the plasma, and is ejected into the film-forming chamber 5 through the nozzle 1.

The nozzle 1 may be a y-row nozzle or a tapered nozzle, but is preferably a contracting/expanding nozzle as shown in FIG. This contraction/expansion nozzle is a nozzle that gradually opens from the inflow C11a [-1 area is narrowed and the throat part 1
c, and the opening area has expanded again to form 11 streams 11b.

The contraction/expansion nozzle has a pressure ratio P/Po between the pressure PO in the plasma chamber 4 and the pressure P in the membrane chamber 5, and a ratio A/Po between the opening area A' of the throat portion 1c and the opening area A of the outflow []lb. A'', the flow of the activated and ejected film forming gas can be sped up.
If the internal pressure ratio P/PO is larger than the critical pressure ratio, the output flow velocity of the contraction/expansion nozzle becomes a flow below the sub-RF velocity,
The film forming gas is ejected at a deceleration rate. In addition, if the distribution pressure ratio is the critical pressure ratio device f, the outlet flow velocity of the contraction/expansion nozzle is greater than 1.
1 speed, and the film forming gas can be ejected at supersonic speed.

Here, assuming that the velocity of the flow is U, the sound velocity at that point is a, the specific heat ratio of the flow is γ, and the flow is a compressible one-dimensional flow with adiabatic expansion, the Matsuha number M reached by the flow is It is determined by the following equation from the pressure P0 of 4 and the pressure P of the film forming chamber 5. In particular, when P/P is a 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 = "7] U" Further, the following relationship exists between the opening area A of the outflow port ib and the opening area A of the throat IC and the Matsuha number M.

Therefore, the pressure p in the plasma chamber 4. 11! Pressurization of the pressure P in the second chamber 5 P / P (l determines the opening area ratio A/A according to the Matsuha number M determined from equation (1), or by ^/A・ (2) P/ according to M determined from the formula
By adjusting PO, the film forming gas ejected from the expansion/contraction nozzle can be ejected as an appropriately expanded flow. The flow velocity U at this time can be determined by the first-order equation (3).

When the film-forming gas is ejected in a fixed direction as a proper expansion flow at supersonic speed as described in 2.-, the film-forming gas travels straight while maintaining almost the jet cross section immediately after ejection, and becomes a beam. This allows the film-forming gas to be ejected through the space within the film-forming chamber 5 with minimal diffusion, in a spatially independent state with no interference with the wall surface of the film-forming chamber 5, and at the speed of sound. become.

When using a contraction/expansion nozzle as the nozzle l, as shown in Fig. 2 (
As shown in a), it is preferable that the inner circumferential surface is substantially parallel to the central axis at the position of the outlet 1b. This is because the flow direction of the ejected film-forming gas is influenced by the direction of the inner circumferential surface of the outlet 1b, so that it can be made to flow as easily as possible. However, as shown in FIG. 2(b), the angle α of the inner peripheral surface from the throat IC to the outlet 1b with respect to the central axis is set to 7° or less, preferably 5°.
If the conditions are as follows, the peeling phenomenon will hardly occur and the flow of the ejected film-forming gas will be maintained almost uniformly, so in this case, it is not necessary to carry out the flow as described above. By omitting the formation of the movable part, it becomes easy to manufacture the contraction/expansion nozzle. Further, if the contraction/expansion nozzle is made rectangular as shown in FIG. 2(C), the film forming gas can be ejected in a slit shape.

Here, the separation phenomenon refers to a phenomenon in which when there is a protrusion etc. on the inner surface of the contraction/expansion nozzle, the boundary layer between the inside of the contraction/expansion nozzle and the flowing fluid becomes large and the flow becomes non-uniform. , 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 set as small as +17 (#: l) among contraction/expansion nozzles with inferior peeling precision.The inner surface of the contraction/expansion nozzle is JIS 8
080I, it is preferable to have 3 or more L, and optimally 4 or more in the inverted E-gon mark indicating the surface roughness accuracy. In particular, the peeling phenomenon at the enlarged part of the condensing/expanding nozzle greatly affects the subsequent flow of the film-forming gas. Easy to manufacture.

Also, it prevents the occurrence of peeling phenomenon! 1- because of throat l
It is necessary that c be a smooth curved surface so that the differential coefficient in the cross-sectional area change rate does not become (1).

As the material for the contraction/expansion nozzle, a wide range of materials can be used, such as iron, stainless steel and other metals, acrylic resin, synthetic resins such as polyvinyl chloride, polyethylene, polystyrene, and polypropylene, ceramic materials 1, quartz, and glass.

This material may be selected in consideration of non-reactivity with the generated active film-forming gas, processability, gas release properties in a vacuum system, and the like. Furthermore, the inner surface of the contraction/expansion nozzle can be plated or coated with a material that is less likely to cause adhesion or reaction with the active film forming gas. 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, contraction/expansion nozzle 1
When flowing through the carrier gas and ultrafine particles, the thermal energy they possess is converted into kinetic energy. In particular, when ejected at a sonic speed, the thermal energy becomes extremely small, resulting in a supercooled state. Utilizing such a low temperature state, it is also possible to fix the energy of the activated film-forming gas and eject it.

A base 12 is provided in the film forming chamber 5 at a position facing the outlet 1b of the nozzle 1. Therefore, the activated film forming gas ejected from the nozzle l collides with this substrate 12,
A film is formed on the base 12. Further, the film forming chamber 5 is evacuated by, for example, a vacuum pump, and surplus gas, reaction gas, etc. are directly exhausted.

By the way, the nozzle 1 is assumed to be a contraction/expansion nozzle, and the pressure P in the plasma chamber 4. and the pressure ratio P/Po of the pressure P in the film forming chamber 5,
By appropriately adjusting the relationship between the opening area A of the throat portion 1c and the ratio A/A'' of the opening area of the outlet ib, the film-forming gas ejected from the nozzle 1 becomes a beam and is directed to the substrate 12. Therefore, scattering of the film-forming gas into the film-forming chamber 5 can be easily prevented, and waste of the film-forming gas due to film adhesion to the inner surface of the film-forming chamber 5 can be prevented.

As shown in FIG. 3(a), the plasma generator 2 includes a slot antenna 13 inserted into the waveguide 8 through the microwave introduction window 7, and the slot antenna 13 inserted into the plasma chamber 4. It may be made to protrude. Also,
As shown in (b), I-slot antenna 13
A horn antenna 14 can also be provided instead.

Furthermore, in this embodiment, the film-forming gas is supplied through the supply ring 10 just before the nozzle l, but the film-forming gas may also be supplied into the nozzle l or immediately after the nozzle l and brought into contact with the plasma. You can also do it. In particular, when supplying the film forming gas into the contraction/expansion nozzle, it is preferable that the supply position be in the acceleration region between the throat IC and the inlet la so as not to disturb the flow.

[Effects of the Invention] According to the present invention, it is possible to control the area and form of the plasma drawn from the plasma generator, so that the film forming gas can be uniformly brought into contact with the plasma in a state suitable for film forming. It is possible to obtain a film-forming state.

[Brief explanation of drawings]

Figure 1 is an explanatory diagram showing one embodiment of the present invention, Figure 2 (a)
~(C) are diagrams showing examples of shapes of contraction/enlargement nozzles, respectively.
Figures (a) and (b) are diagrams showing other plasma generators. l: nozzle, 1a: inlet, lb=outlet, 1c: throat, 2: plasma generator, 3: power supply, 4: plasma chamber, 5: film forming chamber, 6: cavity resonator, 7: micro Wave introduction window, 8: Waveguide, 9: Open 1 piece, 10: Supply ring, 11: Insulating material, 12: Substrate, 13 Nislot antenna, 14: Horn antenna.

Claims (1)

[Claims] 1) A film forming apparatus characterized by having a plasma generating device using microwaves, which forms an electric field between the nozzle and the nozzle, on the upstream side of a nozzle provided in a flow path and capable of applying a voltage.