JP2000144432A - Gas injection head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a gas injection head capable of uniformly injecting a gaseous mixture uniform in the concn. and components toward a substrate in a stable state while early reaction is prevented. SOLUTION: This injection head has an injection head body 66 forming at least two gas spaces 70 and 72 separately stored with at least two kinds of reaction gases, plural gas injection holes 78 arranged at the lower face of the injection head body and coaxial multi-stream nozzles respectively arranged at the gas injection holes, separately introduced with at least two kinds of reaction gases from at least two gas spaces and injecting them.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas injection head for use in a vapor phase growth apparatus, and more particularly, to a barium titanate / gas injection head.
The present invention relates to a gas injection head suitable for vapor-phase growth of a high dielectric or ferroelectric thin film such as strontium.

[0002]

2. Description of the Related Art In recent years, the degree of integration of integrated circuits in the semiconductor industry has been remarkably improved, and research and development of DRAMs from the current megabit order to the future gigabit order have been conducted. To manufacture such a DRAM,
An element capable of obtaining a large capacity with a small area is required. As a dielectric thin film used for manufacturing such a large-capacity element, a tantalum pentoxide (T) having a dielectric constant of about 20 is used instead of a silicon oxide film or a silicon nitride film having a dielectric constant of 10 or less.
a ₂ O ₅ ) thin film or a metal oxide thin film material such as barium titanate (BaTiO ₃ ), strontium titanate (SrTiO ₃ ) having a dielectric constant of about 300, or barium strontium titanate which is a mixture thereof is promising. Have been. When such a metal oxide thin film is vapor-phase grown, a gas source of one or a plurality of organometallic compounds and an oxidizing gas are mixed and sprayed onto a deposition target substrate heated to a certain temperature.

FIG. 8 is a diagram showing an entire configuration of a film forming apparatus for forming a high-dielectric or ferroelectric thin film of barium / strontium titanate or the like of this type, and a vaporizer 110 for vaporizing a liquid raw material. Downstream of the source gas transport passage 112
A film forming chamber 114 that can be hermetically sealed is provided, and a vacuum pump 116 is disposed in an exhaust flow path on the downstream side thereof to form an exhaust pipe 118. An oxidizing gas pipe 120 for supplying an oxidizing gas such as oxygen is connected to the film forming chamber 114.

[0004] With the film forming apparatus having such a configuration, the substrate W
Is placed on a heating plate provided on the substrate holding table 124, and the substrate W
Is maintained at a predetermined temperature, a mixed gas of a source gas and an oxidizing gas is injected toward the substrate W from the gas injection holes 126 of the gas injection head 128 to grow a thin film on the surface of the substrate W.

[0005]

The temperature range in which a mixed gas of an organometallic compound gas and an oxidizing gas can be stably present is generally narrow. If the temperature is uneven during the introduction to the substrate, the gas condenses or decomposes. Is easy to occur. Therefore, when the flow path of the mixed gas is long, a precipitate is easily generated by an early reaction before reaching the substrate. The precipitate thus generated closes the gas injection holes or flows downstream to become a source of particles in the film formation chamber.

Further, if the mixing of the raw material gas and the oxidizing gas is performed after the nozzle exits, the clogging in the nozzle hole can be eliminated, but a uniform mixing state can be obtained in a short process up to the substrate. difficult. In order to obtain a sufficient mixing state, it is necessary to finely distribute the nozzle holes or to increase the distance to the substrate, which makes the apparatus complicated and bloated, which is not practical.

The present invention has been made in view of the above-mentioned circumstances, and is a gas capable of uniformly injecting a mixed gas having a uniform concentration and components toward a substrate in a stable state while preventing an early reaction. An object is to provide an ejection head.

[0008]

According to a first aspect of the present invention, there is provided an ejection head body which forms at least two gas spaces for individually accommodating at least two kinds of reaction gases, and is disposed on a lower surface of the ejection head body. A plurality of gas injection holes, and a coaxial multi-fluid nozzle arranged in each of the gas injection holes and individually introducing and injecting the at least two types of reaction gases from the at least two gas spaces. Gas injection head. Here, the “coaxial multi-fluid nozzle” is a nozzle in which a plurality of flow paths are formed coaxially. The term "reactive gas" as used herein is a concept including, in addition to the raw material gas and the oxidizing gas, an inert gas and the like which are supplementarily added thereto.

[0009] Since the plurality of reaction gases are mixed in the outer nozzle or after leaving the nozzle, reaction products are less likely to adhere to the nozzle side. Moreover, since the reaction gas is injected from the coaxial nozzle, one of the reaction gases is injected so as to surround the other reaction gas, and is uniformly and efficiently mixed downstream by the diffusion action at the nozzle opening. In the mixing process, turbulence hardly occurs, and therefore, generation of particles due to an early reaction due to a change in state is prevented. When three or more gases are used, triple or more nozzles may be used,
Further, double nozzles may be used in multiple stages.

According to a second aspect of the present invention, the coaxial multi-fluid nozzle has an outer nozzle hole and an inner nozzle inserted into the outer nozzle hole for a predetermined length. Gas injection head. By appropriately adjusting the insertion length, the mixing efficiency and the like can be appropriately adjusted according to the properties of the reaction gas. For example, a portion of the outer nozzle hole downstream of the inner nozzle can be defined as a mixing region, and by taking this sufficiently, the mixing efficiency can be improved (see FIG. 3). When the inner nozzle is extended to the end of the shower head, the gas is completely mixed outside the shower head (see FIG. 4).

The invention according to claim 3 is characterized in that the coaxial multi-fluid nozzle is provided with a resistor for providing a flow path resistance at a junction of the outer nozzle hole with the inner nozzle hole or at an upstream side of the junction. The gas injection head according to claim 1. Thereby, the gas distribution of the outer nozzle can be improved. Since the ring-shaped flow path has a larger area than the flow path having a circular cross section, the action as a resistor is insufficient. Therefore, the insertion length of the inner nozzle into the outer nozzle is sufficiently long, a filter such as a sintered body is inserted, a labyrinth structure is formed, a groove is formed in a flow path, and a flow is guided to this groove. The means can impart a flow path resistance to improve the equal distribution of gas in the outer nozzle (see FIG. 5).

According to a fourth aspect of the present invention, there is provided the gas injection head according to the second aspect, wherein a throttle portion is formed in the outer nozzle hole on the downstream side of the inner nozzle. Thereby, the mixing efficiency can be improved by restricting the flow of the reaction gas from the outer nozzle hole and applying it to the flow from the inner nozzle.

According to a fifth aspect of the present invention, there is provided an airtight film forming chamber having the gas ejecting head according to any one of the first to fourth aspects, a gas supply source for supplying a reactive gas to the gas ejecting head, and the film forming head. A film forming apparatus comprising: a substrate holding table disposed in a room so as to face the gas injection head.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below with reference to FIGS. The thin-film vapor phase growth apparatus according to the first embodiment includes a container main body 12 forming an airtight film-forming chamber 10 and a substrate holding table (up and down) inside a cylindrical portion 16 opened at the center of a container bottom portion 14. Susceptor) 1
8 and a gas injection head (shower head) 20 attached to the top of the container body 12.

Heat medium flow paths 22, 24, 26, 28 through which a heat medium such as oil flows are passed through the container body 12, the container bottom portion 14, the cylindrical portion 16, and the gas injection head 20.
a and 28 c are formed, and these flow paths are circulated through an external pipe 30 to a heat medium unit 36 including a drawing means 32 such as a pump and a heating means 34 such as a heater.
In addition, a cooling water circulation unit is provided for cooling required parts (not shown). An exhaust hole 38 for exhausting the generated gas is opened in the container bottom 14, and this is connected to a vacuum pump (not shown).

The substrate holding table 18 is connected via a support shaft 40 to an elevating device 42 disposed below the film forming chamber 10, and thereby moves up and down in the cylindrical portion 16. A robot chamber 4 having a transfer robot 44 is provided at a predetermined height of the cylindrical portion 16.
A substrate transfer port 48 is opened at a position toward 6, and is connected to a gate 52 of the robot chamber 46 via a passage 50. A purge gas supply port 54 is opened at the substrate transfer port 48. The substrate holding table 18 is provided with a heater 56 for heating the substrate W, and the heater 56 is heated based on a detection value of a substrate temperature sensor attached at a predetermined position.
To maintain the substrate temperature constant.

The gas injection head 20 is provided with a substrate W to be formed.
The nozzle head 60 includes a jet disk main body 66 formed in a hollow disk shape by a back plate 62 and a peripheral wall 64. Inside the ejection head body 66, a disk-shaped hollow body 68 is provided with a nozzle plate 60 and a back plate 62.
And a first gas space 70 between the ejection head main body 66 and the hollow body 68.
Are formed. A disk-shaped partition plate 69 is also arranged inside the hollow body 68 at a distance from the upper and lower walls and the side walls of the hollow body 68, and a second gas space 72 is formed here.

A gas supply pipe 74 for individually supplying a reaction gas to each of the gas spaces 70 and 72 is connected to the back plate 62 side of the injection head body 66. The gas supply pipe 74 is a coaxial multi-pipe, and a thermocouple (temperature sensor) 76 reaching the nozzle board is inserted at the center, and a second reaction gas flow path 98 communicating with the second gas space is provided outside the thermocouple (temperature sensor) 76. Further, a first reaction gas flow path 9 communicating with the first gas space 70 outside the first gas space 70.
6 are formed.

The nozzle board 60 is provided with a large number of gas injection holes (outer nozzle holes) 78 at predetermined intervals.
A heat medium flow path 28a is formed so as to surround each gas injection hole 78, and the heat medium is supplied to the heat medium flow path 28b from the inlet 28b and discharged from the outlet 28b 'to the outside. An opening 86 is formed in the bottom plate 80 of the hollow body 68 at a position facing each gas injection hole 78 of the nozzle board 60, and an upper end of a cylindrical nozzle member (inner nozzle) 88 is fixed to this. . Therefore, between the gas injection hole 78 and the outer surface of the nozzle member 88, a tubular flow passage 70a connected to the first gas space 70 is formed. Each nozzle member 8
3 is formed as a venturi type having an upper constricted portion and a lower enlarged portion as shown in FIG. 3, and the lower end of this nozzle member 88 is inserted into the gas injection hole 78 by a predetermined length. As a result, a coaxial two-fluid nozzle is formed.

Each gas space 70, 7 of the injection head body 66
2 are vertically divided by a hollow body 68 and a partition plate 69, respectively, and the first and second reactant gases respectively supplied from the reactant gas passages 96 and 98 of the gas supply pipe 74 are located on the upper side. After flowing radially outward through the gas space,
It turns over at the side walls 64 and 84 and flows into the lower gas space from the outer edge. Thereby, in each lower gas space, a gas flow rate distribution according to the arrangement density of the nozzles is achieved, and the flow rates from the nozzles are equalized.

The shape of the injection head body 66 is not limited to this, and the two gas spaces may be formed as a simple two-layer disc-shaped space. May be used. Further, the entirety of the ejection head main body 66 may be formed in a trumpet shape whose diameter is increased downward.

An outer cover 92 is provided so as to cover the inner surface of the peripheral wall 64, the upper surface of the back plate 62, and the outer surface of the gas supply pipe 74. A seal ring 94 is disposed between the outer cover 92 and the peripheral wall 64 to seal the inside. ing. As shown in FIG. 2, a heating medium passage 28 c is formed between the outer cover 92 and the upper surface of the back plate 62 and the outer surface of the gas supply pipe 74, and the gas supply pipe 74 and the inside of the ejection head body 66 are formed. The reaction gas flowing through is heated.

The gas injection head 20 constructed as described above
The operation of will be described. A reaction gas, that is, a raw material gas and an oxidizing gas in this example, are respectively introduced into a gas supply pipe 74 from a supply source (not shown). The source gas is, for example, B
a (DPM) ₂ , Sr (DPM) ₂ and Ti (i-OC ₃ H
₇ ) An organometallic compound such as ₄ is dissolved in a solvent and vaporized.
The oxidizing gas is, for example, an oxygen-containing gas such as O ₂ , N ₂ O, or H ₂ O;
Alternatively, the ozone generated by the ozonizer (O
₃ ).

The oxidizing gas of the reaction gas is supplied from the first gas supply passage 96 of the gas supply pipe 74 to the first gas space 70.
First, the raw material gas flows from the second gas supply path 98 of the gas supply pipe 74 to the second gas space 72, once flowing outward in the upper gas space, and then flows toward the center in the lower gas space and is introduced. Is done. The oxidizing gas is supplied to the nozzle board 60
The raw material gas is injected from the respective gas injection holes 78 toward the substrate W, and the source gas is injected from the nozzle members 88 provided in the respective through holes 86 of the bottom plate 80.

The raw material gas is injected from the nozzle member 88 into the gas injection holes 78, while the oxidizing gas is injected into the gas injection holes 7.
The gas is injected so as to wrap the source gas inside the gas injection holes 78 through the cylindrical flow path 70 a between the nozzle member 8 and the nozzle member 88. The two are uniformly mixed in the process of further descending a region (mixing region) below the nozzle member 88 in the gas injection hole 78, and exits the gas injection hole 78 to further direct the space inside the film forming chamber 10 toward the substrate W. And descend. Thus, 2 which is mixed
Since the two reaction gases are injected from the coaxial nozzle, turbulence is hardly generated in the mixing process, and the generation of particles due to early reaction is prevented. In addition, since the liquid passes through the narrow mixing area after being injected, the mixing efficiency is higher than when the liquid is directly injected into the film forming chamber 10.

As in this embodiment, the source gas flows from the inner nozzle member and the oxidizing gas flows along the peripheral wall of the gas injection hole 78, thereby forming an oxidizing gas layer on the peripheral wall of the gas injection hole 78. By forming it, it is possible to minimize the adhesion of deposits and the like to the wall surfaces of the gas injection holes 78. The heat medium is supplied from the heat medium unit 36 to the nozzle board 60, the peripheral wall 64, and the heat medium flow path 28 between the outer cover 92 and the back plate 62 through the heat medium pipe 30, so that each part is maintained at a predetermined temperature. Thus, adhesion of deposits and the like to these portions including the nozzle member is suppressed.

FIG. 4 shows a gas injection head according to a second embodiment of the present invention, in which a nozzle member 88 is formed to extend to the end of a gas injection hole 78. in this case,
The mixing of the gases takes place outside the showerhead. this is,
This is used when the reaction product of the two gases is very likely to adhere to the gas injection holes 78. In the case where the nozzle member 88 is more easily attached, the nozzle member 88 may be made to protrude from the tip of the gas injection hole 78.

FIG. 5 shows a gas injection head according to a third embodiment of the present invention. A nozzle member 88 extends halfway through a gas injection hole 78 and is located downstream of the nozzle member 88 of the gas injection hole 78. A step surface 78b is formed at the side position, and a filter 99 made of a sintered body of a predetermined mesh or the like is mounted on the step surface 78b so as to close the tubular channel 70a.
Thereby, the gas distribution property of the gas injection holes (outer nozzle holes) 78, which have a ring-like shape and do not sufficiently function as a resistor, can be improved. In the above description, the filter 99 is provided on the upstream side of the junction of the two gases.
However, the present invention is not limited to this, and an annular filter may be attached to the junction of the two gases in the gas injection port 78.

FIG. 6 shows a gas injection head according to a fourth embodiment of the present invention. The gas injection head is provided on the inner peripheral surface of a gas injection hole 78 of a nozzle board 60 at a position facing the lower end of a nozzle member 88. A throttle portion 78a whose diameter gradually decreases downward is formed. With this configuration, the gas injection holes 7
The oxidizing gas injected from the nozzle 8 is directed toward the center along the throttle portion 78a and collides with the source gas injected from the nozzle member 88, so that the mixing efficiency can be increased.

FIG. 7 shows a gas injection head according to a fifth embodiment of the present invention, which is suitable for mixing three kinds of reaction gases. That is, above the second gas space 72, the third gas space 104 into which the third reaction gas is introduced.
Are defined by the bottom plate 100 and the top plate 102. A nozzle member 108 is attached to the bottom plate 100 at an opening 106 formed at a position opposed to the nozzle member 88, and a lower end thereof is inserted into the nozzle member 88 located below by a predetermined distance to allow the nozzle member 88 to communicate with the nozzle member 88. A tubular flow path 72a is formed therebetween. In this example, both the first and second nozzle members 108 and 88 have the throttle portions 78a and 8a.
8a are formed.

With this configuration, the first reaction gas,
The second reaction gas and the third reaction gas are individually introduced into the first gas space 70, the second gas space 72, and the third gas space 104. Then, the third reaction gas is injected from the third nozzle member 108 into the second nozzle member 88, and descends while mixing with the second reaction gas supplied from outside the third nozzle member 108. And the first nozzle member 7
8, further descends while mixing with the first reaction gas supplied from the outside of the second nozzle member 88, and finally is injected into the space in the film forming chamber 10.

In this manner, a uniform mixed gas can be injected by sequentially mixing the three gases. In this case, the order in which the respective reactive gases are mixed can be determined according to the type of the reaction performed in the film forming chamber 10. For example, a reactive gas such as an oxidizing gas is preferably supplied last, that is, to the first gas space in order to prevent a pre-reaction.

[0033]

As described above, according to the present invention, a gas mixture having a uniform concentration and components is uniformly directed toward a substrate in a stable state while suppressing early reaction and preventing generation of particles. This makes it possible to perform stable and high-quality film formation using a relatively unstable source gas such as a high / ferroelectric substance in a vapor phase growth apparatus.

[Brief description of the drawings]

FIG. 1 is a sectional view schematically showing a vapor phase growth apparatus according to a first embodiment of the present invention.

FIG. 2 is a sectional view of the gas injection head according to the first embodiment of the present invention.

FIG. 3 is an enlarged cross-sectional view of a main part of FIG.

FIG. 4 is an enlarged sectional view showing a main part of a gas injection head according to a second embodiment of the present invention.

FIG. 5 is an enlarged sectional view showing a main part of a gas injection head according to a third embodiment of the present invention.

FIG. 6 is an enlarged sectional view showing a main part of a gas injection head according to a fourth embodiment of the present invention.

FIG. 7 is an enlarged sectional view showing a main part of a gas injection head according to a fifth embodiment of the present invention.

FIG. 8 is a diagram showing an overall configuration of a film forming apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Film-forming chamber 18 Substrate holding stand 28a, 28c Heat medium flow path 60 Nozzle board 66 Injection head main body 70, 72, 104 Gas space 74 Gas supply piping 78 Gas injection hole 78a, 88a Restriction part 80, 100 Bottom plate 86, 106 communication Hole 88,108 Nozzle member

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Isamu Tsukamoto 11-1 Haneda Asahimachi, Ota-ku, Tokyo Inside Ebara Corporation (72) Inventor Yuji Abe 11-1 Asahicho, Haneda, Ota-ku, Tokyo EBARA F term (reference) 4G035 AB02 AC48 AE13 4K030 AA11 AA14 BA01 BA42 BA46 EA05 EA06 GA02 KA25 LA01 LA15 5F045 AA03 AB31 AC07 AC11 DP03 DQ10 EF05 EF08 EM10 EN04 5F058 BA20 BB06 BG03 BG06 BG03 BG06 BG03

Claims (5)

[Claims] 1. An injection head body that forms at least two gas spaces for individually storing at least two types of reaction gases, a plurality of gas injection holes arranged on a lower surface of the injection head body, and the gas injection holes. Respectively, said at least two
A coaxial multi-fluid nozzle for separately introducing and injecting the at least two types of reaction gases from two gas spaces. 2. The gas injection head according to claim 1, wherein the coaxial multi-fluid nozzle has an outer nozzle hole and an inner nozzle inserted into the outer nozzle hole for a predetermined length. 3. The multi-fluid nozzle according to claim 1, wherein the coaxial multi-fluid nozzle is provided with a resistor for providing a flow path resistance at a junction of the outer nozzle hole with the inner nozzle hole or at an upstream side of the junction. The gas injection head as described. 4. The gas injection head according to claim 2, wherein a throttle portion is formed in the outer nozzle hole on a downstream side of the inner nozzle. 5. An airtight film-forming chamber having the gas injection head according to claim 1, a gas supply source for supplying a reaction gas to the gas injection head, and a gas supply head in the film-forming chamber. A film forming apparatus, comprising: a substrate holding table disposed to face the same.