JPS62116771A - Film forming device - Google Patents

Abstract

PURPOSE:To effectively utilize light beam energy by using reducing and expanding nozzles to supply a gaseous raw material onto a substrate in a reaction chamber and to supply a non-reactive gas to a light beam incident window. CONSTITUTION:The reducing and expanding nozzle 1 is disposed to a flow passage connecting a gaseous raw material generating chamber 3 and the reaction chamber 5 and the outflow port thereof is directed to the substrate 10. The other reducing and expanding nozzle 11 is disposed to a flow passage connecting a non-reactive gas generating chamber 4 and the reaction chamber 5 and the outflow port thereof is directed to an incident window 9 of the light beam. The gaseous raw material blown onto the substrate 10 is excited by the light beam irradiated from a light source 6 and the thin film is formed by the decomposition and reaction thereof. Since the non-reactive gas is constantly blown to the incident window 9, the contamination of the incident window 9 by the gaseous raw material is prevented. The respective gases can be transformed in the form of a beam by the above-mentioned mechanism and therefore, the diffusion of the gases is prevented.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a film forming apparatus used for forming a thin film, and particularly relates to a film forming apparatus that promotes a film forming reaction by energy irradiation with a light beam. .

[Prior Art] This type of conventional apparatus introduces a raw material gas (reactive gas) into a reaction chamber in which a substrate for film deposition is arranged, and then introduces the raw material gas into the atmosphere of the raw material gas and then externally through an entrance window. A light beam is irradiated from a light source toward a substrate to activate source gas molecules on the surface of the substrate, and a thin film is formed by decomposition and reaction caused by this activation.

[Problems to be Solved by the Invention] However, in the above-mentioned conventional apparatus, as the film forming operation progresses, a film is also formed on the light beam entrance window, and the adhesion of this film causes dirt, which reduces the energy of the light beam. It has the disadvantage that it cannot be applied effectively to the substrate.

SUMMARY OF THE INVENTION An object of the present invention is to provide a film forming apparatus that can eliminate the drawbacks of the conventional apparatus described above and can effectively utilize the energy of a light beam.

[Means for Solving the Problems] The present invention supplies a raw material gas onto the surface of a substrate in a reaction chamber using a first contraction/expansion nozzle, and also supplies a non-reactive gas to a light beam entrance window in the reaction chamber. It is characterized in that the gas is supplied by a second contraction/expansion nozzle.

To introduce each gas into the reaction chamber, first reduce the pressure in the reaction chamber with a vacuum pump, and then introduce the gas into the reaction chamber using the pressure difference between the generation chamber of each gas and the reaction chamber. That is. The gas that has passed through the contraction/expansion nozzle flows into the reaction chamber in the form of a high-speed beam.

In addition, the inflow side and the outflow side of the contraction/expansion nozzle in the present invention can be an open system even if it is a closed system, as long as a pressure difference is generated between the two and the gas can flow through while being exhausted on the downstream side. There may be.

An example of the contraction/expansion nozzle used in the present invention is shown in FIG. In FIG. 2, the contraction/expansion nozzle l is the inlet port 1a.
The opening area is gradually narrowed from the middle part to the throat part 2.
This is a nozzle whose opening area gradually increases from the throat portion 2 toward the outlet 1b.

As the non-reactive gas in the present invention, in addition to commonly used inert gases, gases that are non-reactive with respect to the raw material gas are used. Further, as a light source, ultraviolet, infrared, laser, etc. are used.

[Function] Supplying raw material gas and non-reactive gas to each generation chamber - Method 1
When the reaction chambers are evacuated using a vacuum pump, a pressure difference is created between each generation chamber and the reaction chamber. Therefore, the supplied gas flows from each generation chamber through the contraction/expansion nozzle and flows into the reaction chamber at high speed.

In the reaction chamber, a high-velocity beam of raw material gas is blown onto the substrate surface, and a high-velocity beam of non-reactive gas is blown onto a light beam entrance window. The gas reflected from the substrate and the entrance window is immediately pumped out of the reaction chamber by the vacuum pump described above.

By the way, the contraction/expansion nozzle calculates the pressure ratio P/Pa between the pressure Po in the generation chamber and the pressure P in the reaction chamber, and the ratio A/A'' between the opening area A of the throat section 2 and the opening area A of the outlet 1b. By adjusting the flow rate of the ejected gas, it is possible to increase the speed of the ejected gas.If the pressure ratio P/Pa in the generation chamber and the reaction chamber is greater than the critical pressure ratio, the flow velocity at the exit of the contraction-expansion nozzle becomes a subsonic flow, The gas is ejected at a reduced speed.If the pressure ratio is less than or equal to the critical pressure ratio, the outlet flow velocity of the contraction/expansion nozzle becomes a supersonic flow, and the gas can be ejected at an ultrahigh 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 gas flow is γ, and assuming that the gas flow is a compressible one-dimensional flow and expands adiabatically, the reached Matzha number M of the gas flow is
is determined by the following equation from the pressure Po in the generation chamber and the pressure P in the reaction chamber. In particular, when P/Po is below 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 = "71 薯" In addition, the opening area A of the outflow hole 1b and the opening area A of the throat part 2
The relationship between ° and Matsuha's number M is as follows.

Therefore, the pressure P in the generation chamber. and the pressure ratio P of the reaction chamber pressure P
/Pa determines the opening area ratio A/A'' according to Matsuha fiM determined from equation (1), and A/Aψ determines (
2) By adjusting P/P according to M determined from the equation, the flow velocity of the gas flow ejected from the expansion/contraction nozzle can be adjusted. The velocity U of the gas flow at this time can be determined by the following equation (3).

If the temperature in the generation chamber is constant, the flow state of the gas flow is the pressure ratio P/Po of the pressure Po in the generation chamber and the pressure P in the reaction chamber.
By keeping constant, a constant state determined by the opening area ratio A/A'' is maintained.

In the above-mentioned ejection where the pressure ratio is less than the critical pressure ratio, the ejected gas becomes a uniform diffusion flow, making it possible to uniformly spray the gas over a relatively wide range at once.

On the other hand, when gas is ejected in a fixed direction as a supersonic flow as described above, the gas travels straight while maintaining almost the jet cross section immediately after ejection, and becomes a beam.

Therefore, it is transported through the space within the reaction chamber with minimal diffusion, in a spatially independent state without interference with the walls of the reaction chamber, and at supersonic speed.

For these reasons, 1. For example, the raw material gas is excited in the generation chamber and transferred directly into a beam through the contraction/expansion nozzle, or the raw material gas is excited in the contraction/expansion nozzle or immediately after the contraction/expansion nozzle, and then the source gas is excited. If the beam is transferred as it is, it can be transferred as a spatially independent beam at supersonic speed, and can be sprayed, for example, onto a substrate provided in a reaction chamber. Therefore, it becomes possible to feed the raw material gas in a good activated state.

Furthermore, since the jet is sprayed onto the substrate as a beam whose cross section is substantially constant in the flow direction, the area of the spray can be easily controlled.

[Embodiment] FIG. 1 is a schematic configuration diagram of an apparatus showing an embodiment of the present invention.

In FIG. 1, the contraction/expansion nozzle l is the raw material gas generation chamber 3.
The outflow nozzle 11 is arranged in a flow path connecting the non-reactive gas generation chamber 4 and the reaction chamber 5, and its outflow "I" is directed toward the base 10. ,
Its outlet is directed towards the entrance window 9 of the light beam. Note that FIG. 1 shows the vertical positional relationship of each nozzle, and the two nozzles are arranged at positions that do not overlap in terms of plane. An exhaust port is provided at a position facing the contraction/expansion nozzles 1 and 11, and a vacuum pump 12 is disposed. By exhausting the vacuum pump 12, the reaction chamber 5 is always kept at a low pressure. A light source 6 is disposed in the upper part of the reaction chamber 5, and a substrate 10 is illuminated through a projection lens 7, a mask plate 8 for forming a thin film in a predetermined pattern, and an entrance window 9 provided on the upper wall of the reaction chamber 5. It is configured so that the light beam is irradiated to the area.

As mentioned above, the contraction/expansion nozzle l is the inlet 1a.
The opening area gradually narrows down from the throat? It is sufficient if the area gradually expands to the outflow t+lb, but the opening area of the throat 2 is determined by the required pressure and temperature of the generation chamber from the exhaust flow rate of the vacuum pump 12. The nozzle flow rate at the bottom is set to be small. As a result, the outlet tb is properly expanded, and the outlet 1
It is possible to prevent deceleration, etc. at b. Further, as shown in an enlarged view in FIG. 2, it is preferable that the inner circumferential surface near the outlet lb is substantially parallel to the central axis. This is because the flow direction of the ejected gas is influenced to some extent by the direction of the inner circumferential surface near the outlet 1b, so the purpose is to make parallel flow as easy as possible. However, as shown in FIG. 3, if the angle α of the inner circumferential surface from the throat portion 2 to the outlet 1b with respect to the central axis is set to 7° or less, preferably 5° or less, the peeling phenomenon will be less likely to occur, and no jetting will occur. Since the flow of gas is maintained substantially uniformly, it is not necessary to form the above-mentioned parallel portion in this case. By omitting the formation of the parallel portion, the contraction/expansion nozzle 1 can be manufactured easily.

Here, the separation phenomenon is a phenomenon in which when there is a protrusion etc. 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 and the flow becomes non-uniform. 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 finish accuracy of the contraction/expansion nozzle l becomes lower. The inner surface of the contraction/expansion nozzle l conforms to JIS 8080.
It is preferable to have two or more inverted triangular marks representing the surface finish accuracy determined by +, and optimally four or more. In particular, the peeling phenomenon at the enlarged part of the contraction/expansion nozzle l greatly affects the subsequent gas flow, so the above finishing accuracy is
By placing emphasis on this enlarged portion, it is possible to easily manufacture the contracting/expanding nozzle l. In addition, in order to prevent the occurrence of peeling phenomenon, the throat portion 2 is made into a smooth curved surface, and the throat portion 2 is made of a smooth curved surface. It is necessary to prevent the differential coefficient in the i product change rate from becoming ■.

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

In addition to stainless steel and other metals, acrylic resin,
A wide variety of materials can be used, including synthetic resins such as polyvinyl chloride, polyethylene, polystyrene, and polypropylene caps, ceramic materials, quartz, and glass. This material may be selected by taking into consideration non-reactivity with the generated reactant, workability, gas release properties in a reduced pressure system, and the like. Furthermore, the inner surface of the contraction/expansion nozzle 1 may be plated or coated with a material that is less likely to cause gas adhesion or reaction. A specific example is a polyfluoroethylene coating.

The length of the contraction/expansion nozzle 1 can be arbitrarily determined depending on the size of the device, etc., but in order to maintain high-speed jetting, it is preferable that the contraction/expansion nozzle 1 is short.

Next, the operation will be explained with reference to FIG. First, predetermined gases are supplied into the raw material gas generation chamber 3 and the non-reactive gas generation chamber 4, respectively, and at the same time, a vacuum pump is used to supply the reaction chamber 5.
Evacuate the inside and create a reduced pressure state. In this case, the pressure ratio P/PO of the pressure Po of each generation chamber and the pressure P of the reaction chamber 5 is set in advance.
By appropriately adjusting the relationship between the opening area A° of the throat section 2 and the ratio A/A'' of the opening area of the outlet 1b, each gas flowing through the contraction/expansion nozzle ■ is converted into a beam. , will flow at supersonic speed from the generation chamber to the reaction chamber.

The source gas blown onto the substrate 10J is excited by the light beam irradiated from the light source 6, decomposes and reacts, and forms a thin film. On the other hand, since the non-reactive gas is constantly blown onto the entrance window 9 during the film-forming operation, the entrance window is prevented from becoming contaminated due to adhesion of the source gas. Furthermore, each gas blown onto the substrate 10 and the entrance window 9 is immediately exhausted outside by the vacuum pump 12, so that film formation can be continued without the gas remaining in one reaction chamber.

FIG. 4 is a block diagram of an apparatus showing another embodiment of the present invention. In this embodiment, an excitation device 21 using microwaves, high frequencies, etc. is provided in the raw material gas generation chamber 3 to excite the raw material gas in advance and spray it onto the substrate as an excited gas beam.

The other configurations are the same as in FIG.

By exciting the raw material gas in advance in this way, it becomes possible to carry out the reaction on the substrate more efficiently.

[Effects of the Invention] As explained above, according to the present invention, by supplying the raw material gas and the non-reactive gas using a plurality of contraction/expansion nozzles, the gas can be transferred in a beam shape. gas diffusion can be prevented. In particular, when used for raw material gas, it can be transported in a straight and focused state from the contraction/expansion nozzle to the surface of the substrate, making it easy to control the reaction area on the substrate. . Moreover, the spraying of the non-reactive gas and the above-mentioned beam forming effect can prevent unnecessary film from adhering to parts other than the substrate, such as the light beam entrance window, the inner wall of the device, etc., and the light beam energy can be used effectively.

In addition, by exciting the raw material gas in advance,
The film formation reaction can be made more efficient, and the deposition rate of the thin film can be improved.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing one embodiment of the present invention, FIGS. 2 and 3 are diagrams showing an example of the shape of a contraction/expansion nozzle, and FIG. 4 is a block diagram showing another embodiment of the present invention. be. 1.11... Reduction/expansion nozzle, 3... Raw material gas generation chamber, 4... Non-reactive gas generation chamber, 5... Reaction chamber, 6...
- Light source, 9...Incidence window, IO...Base.

Claims (1)

[Claims] 1) A film forming apparatus characterized in that a first contraction/expansion nozzle supplies a source gas into a reaction chamber, and a second contraction/expansion nozzle supplies a non-reactive gas to a light beam entrance window in the reaction chamber.