JPH10168572A - Injection head of reactive gas - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an injection head for a reactive gas which can uniformly inject a gaseous mixture having uniform concentration and component in a stable state to a substrate while preventing an early stage reaction. SOLUTION: This injection head is provided with an injection head main body 68 forming a gas mixing space 66 between a nozzle plate 60 having a number of gas injection holes 74 and a back plate 62, gas supplying pipes 70 supplying at least two kinds of reaction gases to the gas mixing space 66 by being joined to the injection head main body 68 from the back plate side. Gas distributing flow passages 90 individually guiding at least two kinds of reaction gases from the gas supplying pipes 70 to the peripheral part of the gas mixing space 66 are formed between the nozzle plate 60 and the background plate 62.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[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.

[0003]

Generally, the temperature range in which a mixed gas of an organometallic compound gas and an oxidizing gas can be stably supplied is narrow. If the temperature is uneven during the introduction to the substrate, the gas condenses or decomposes. Cheap. Here, for example, when the flow path of the mixed gas becomes long, the mixed gas of the raw material gas and the oxidizing gas is easily affected by the temperature fluctuation of the flow path, and precipitates are easily generated by an early reaction before reaching the substrate. The precipitates generated in this way block the gas discharge holes or flow downstream to contaminate the substrate.

In addition, if the mixing of the source gas and the oxidizing gas is performed after leaving the nozzle, clogging in the nozzle hole can be reduced, but a uniform mixed state can be obtained in a short process up to the substrate. Is 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.

[0005] The present invention has been made in view of the above-mentioned circumstances, and a reaction in which a mixed gas having a uniform concentration and components can be uniformly jetted toward a substrate in a stable state while preventing an early reaction. It is an object to provide a gas injection head.

[0006]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and the invention according to claim 1 has a gas mixing space between a nozzle plate having a number of gas injection holes and a back plate. And a gas supply pipe connected to the ejection head body from the back plate side to supply at least two types of reaction gases to the gas mixing space, and between the nozzle plate and the back plate. And a gas distribution channel for individually guiding the at least two types of reaction gases from the gas supply pipe to a peripheral portion of the gas mixing space.

As the shape of the gas distribution channel, an appropriate one, for example, a radial shape is adopted, and it may be formed simply by a gap between flat plates. With such a configuration, at least 2
The seed reaction gases are independently introduced into the peripheral portion of the gas mixing space by the gas distribution channels, and further flow toward the center of the gas mixing space. In this peripheral portion, the directions of each gas change by approximately 180 degrees toward the center while diffusing in the circumferential direction, so that the flow is violently disturbed, and mixing is efficiently performed. In the process of flowing into the gas mixing space, the gas flowing into the mixing space flows from the edge of the disc-shaped space toward the center at the same time as the gas flows into the mixing space. And uniform gas injection can be obtained.

According to a second aspect of the present invention, at least two distribution plates are disposed between the nozzle plate and the back plate.
The reactive gas injection head according to claim 1, wherein the gas distribution channel is formed between the back plate and the distribution plate. Thereby, for example, by forming a groove or a ridge in these members, a gas distribution channel of an arbitrary shape can be formed with a simple configuration, and a gap between these may be used as it is. . If the back plate and the distribution plate and the distribution plate are kept in close contact with each other, the heat conduction between the distribution plate and the back plate can be improved, and the temperature of the distribution plate can be indirectly controlled by the back plate. Therefore, it is possible to precisely control the temperature of the gas distribution channel without forming a heat medium channel therein, thereby suppressing the condensation and decomposition of the reaction gas in the gas distribution channel.

According to a third aspect of the present invention, a dispersion plate having a large number of gas dispersion holes is provided between the distribution plate and the nozzle plate in the gas mixing space. 1. The reactive gas injection head according to 1, wherein a gas dispersion space is formed upstream of the nozzle board, and the gas distribution is promoted and the pressure distribution is made uniform on the upstream side of the nozzle board, thereby making the pressure distribution uniform from the nozzle board to the substrate. Gas injection toward the target is made uniform.

According to a fourth aspect of the present invention, the peripheral wall of the gas mixing space is inclined so as to be inward toward the center of the gas mixing space from the outlet of the gas distribution channel. Since the reactive gas injection head according to claim 1, a strong turbulent flow is generated in the peripheral portion of the gas mixing space, and the respective gases mix while diffusing in the circumferential direction. In addition, the sharp edge deflection at the edge can generate a uniform gas flow having a uniform concentration distribution toward the center of the gas mixing space.

The invention according to claim 5 is characterized in that a temperature maintaining means for maintaining the gas distribution flow path and the nozzle panel at a predetermined temperature is provided. It is a gas injection head. As a result, the temperature of the gas distribution channel and the nozzle panel is precisely controlled, and as a result, the gas distribution channel and each nozzle flow including the mixing space and the gas distribution plate heated indirectly by radiation and heat transfer. Condensation and decomposition of the reaction gas in the passage can be suppressed.

The cross-sectional area of the flow path of the reaction gas may be reduced as it goes downstream. That is, the cross-sectional area of each flow path of the supply pipe, the gas distribution flow path, the gas dispersion holes, and the gas injection holes (sum at each point) is represented by S ₁ , S ₂ , S ₃ ,
When _{S 4, S 1> S 2} , S 3> relation S ₄ are so satisfied. Accordingly, the gas can be uniformly distributed to the surrounding mixing space through the distribution plate, and the pressure of the mixing space can be made uniform so that the gas jet from the gas injection holes can be made uniform. Further, a narrow portion extending in the circumferential direction may be formed between a peripheral portion of the gas mixing space and a central portion of the gas mixing space.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIGS. This thin film vapor phase growth apparatus includes a kettle-shaped container body 1 constituting a film forming chamber 10.
2, a susceptor (substrate holding means) 18 capable of moving up and down in a cylindrical portion 16 opened at the center of the container bottom 14, and a container body 1
2 is provided with a shower head (raw material gas injection nozzle) 20 attached to the top.

Heat medium flow paths 22, 24, 26, 28a, and 2 through which a heat medium such as oil flows are provided in the container body 12, the bottom portion 14, the cylindrical portion 16, and the shower head 20.
8 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 susceptor 18 is connected via a support shaft 40 to an elevating device 42 disposed below the film forming chamber 10, thereby moving up and down in the cylindrical portion 16. A robot chamber 46 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 the robot chamber 46, and is connected to a gate 52 of the robot chamber 46 via a bellows (passage) 50. A purge gas supply port 54 is opened at the substrate transfer port 48. The susceptor 18 is provided with a heater 56 for heating the substrate W, and adjusts electric power to the heater 56 based on a detection value of a substrate temperature sensor attached at a predetermined position to maintain a constant substrate temperature. I have to.

The shower head 20 includes a substrate W on which a film is to be formed.
An injection head body 68 that forms a substantially disk-shaped gas mixing space 66 by a nozzle plate 60, a back plate 62, and a peripheral wall 64 that are disposed opposite to the nozzle plate 60, and is connected to the injection head body 68 from the back plate 62 side. A gas supply pipe 70 for supplying at least two kinds of reaction gases to the gas mixing space 66. The gas supply pipe 70 is a coaxial multiple pipe,
Thermocouple (temperature sensor) 72 reaching the nozzle board at the center
Is inserted.

The nozzle board 60 has a diameter slightly larger than the substrate W and is formed integrally with the peripheral wall 64 extending upward, thereby forming a recess on the upper side of the nozzle board 60. As shown in FIG. 6, the nozzle board 60 is provided with nozzle elements 76 having a large number of gas nozzles 74 in the form of jet nozzles, and the heating medium flow path 28a is formed so as to surround each nozzle element 76. I have. 28b, 2
Reference numeral 8b 'denotes an entrance of each heat medium to the nozzle board 60. As described below, a plurality of flat members are sequentially mounted in the recess.

A dispersion plate 80 having a large number of gas dispersion holes 78 is arranged above the nozzle plate 60, and a gas dispersion space 82 is formed between the dispersion plate 80 and the nozzle plate 60. Dispersion plate 80
A vertically extending cylindrical wall 84 is formed at the edge of the upper surface, and a gas mixing space is formed above and below. The gas dispersion holes 78 are arranged so as to be alternated with the gas injection holes 74 of the nozzle board 60, and the total flow path cross-sectional area S ₃ is different from the gas injection holes 74.
It has largely been set than the total flow path cross-sectional area S ₄ of the. The back plate 62 is mounted so as to be in contact with the upper end of the cylindrical wall 84 of the dispersion plate 80, and the gas supply pipe, which is a coaxial multiple pipe, is inserted into the center of the back plate 62.

An outer cover 86 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 70. A seal ring 88 is disposed between the outer cover and the peripheral wall 64 to seal the inside. ing. As shown in FIG. 5, a heat medium flow path 28c is formed between the outer cover 86, the upper surface of the back plate 62, and the outer surface of the gas supply pipe 70, and the gas supply pipe 70, the distribution plates 92, 94 Is heating.

In the space between the back plate 62 and the dispersion plate 80, as shown in FIG. 2, upper and lower two distribution plates 92 and 94 each having a radial groove (gas distribution channel) 90 formed on the upper surface. Is installed. In this example, the same number of these grooves 90 is formed axially symmetrically at the same position in the circumferential direction in each of the distribution plates 92 and 94. Gas supply path 9 outside gas supply pipe 70
6 is a groove 90 between the upper distribution plate 92 and the back plate 62, and an inner gas supply passage 98 is a groove 9 between the upper and lower distribution plates 92 and 94.
0 through the gas distribution recess 100 at the center of the distribution plates 92 and 94, respectively.

An annular first mixing space 66a is formed between the outer peripheries of the distribution plates 92 and 94 and the cylindrical wall 84 of the dispersion plate 80, and a disc-shaped space is formed between the lower distribution plate 94 and the dispersion plate 80. Are formed, and these first mixing spaces 6b are formed.
6a and the second mixing space 66b constitute a gas mixing space 66. In this example, the inner surface of the cylindrical wall 84 is an inclined surface 102 that faces inward toward the dispersion plate 80, and mixes and reflects the gas discharged from the grooves 90 of the distribution plates 92 and 94 to form the second mixing surface. The space 66b is smoothly guided to the space 66b. Note that the upper distribution plate 92 and the back plate 62 and the distribution plates 92 and 94 are in close contact with each other at locations other than the grooves.
The thermal conductivity with the back plate 62 is improved. Since the back plate 62 is maintained at a predetermined temperature by the heat medium flow path 28c, the temperature of the distribution plates 92 and 94 is also maintained at a temperature at which condensation or decomposition of the raw material gas does not occur.

In this shower head, the flow path of the reactant gas, ie, the raw material gas and the oxidizing gas, is set such that the cross-sectional area of the pipe gradually decreases toward the downstream. That is, the sum S ₁ of the cross-sectional areas of the two supply passages 96 and 98 of the gas supply pipe 70 and the two distribution plates 92 and 9
The sum S ₂ of the cross-sectional area of the groove 90 of _{No. 4} , the sum S ₃ of the cross-sectional area of the gas dispersion hole 78 of the dispersion plate 80, and the sum S ₄ of the cross-sectional area of the gas injection hole 74 of the nozzle board 60 are represented by S _1. > S ₂ , S ₃ > S ₄ . Thereby, control is performed so as to maintain the back pressure of the gas in each of the flow paths, that is, in each of the grooves 90 of the distribution plates 92 and 94 and the gas dispersion space to suppress the pressure fluctuation, and to control the in-plane from the gas injection holes 74. A uniform gas injection is obtained.

The number of grooves in the distribution plates 92 and 94 is preferably large in order to ensure uniform distribution of the gas amount in the circumferential direction, but is preferably small in terms of the number of processing steps. In this example, it has been found that there is no problem at all if the interval between the openings of the grooves 90 at the peripheral edge of the distribution plate is smaller than 45 mm in circumference.

The operation of the thus-configured reactive gas injection head will be described. The reaction gas, that is, the raw material gas and the oxidizing gas are respectively introduced into the gas supply pipe 70 from a supply source (not shown). The source gas is, for example, Ba (DP
M) ₂ , Sr (DPM) ₂ and Ti (i-OC ₃ H ₇ ) _{4 and} other organic metal compounds dissolved in a solvent are mixed and vaporized and transported to a carrier gas such as Ar. The oxidizing gas is, for example, an oxygen-containing gas such as O ₂ , N ₂ O, or H ₂ O, or a gas containing ozone (O ₃ ) generated by an ozonizer.

The reaction gas is introduced from a gas supply pipe 70 (in this example, the source gas is supplied from a supply path 96 and the oxidizing gas is supplied from a supply path 98). The liquid is injected into the first mixing space 66a, deflects on the inclined surface 102, and deflects.
b flows toward the center. The source gas and the oxidizing gas are diffused and mixed in this process.
In the above, a complicated flow descending along the inclined surface 102 where the outlet is narrowed while expanding in the circumferential direction from the tip of the groove 90 is formed, so that the turbulence of the flow is formed and the mixture is sufficiently stirred,
Evenly mixed.

On the other hand, in the second mixing space 66b, the gas flows from the surroundings toward the center, and in the process, flows from the gas dispersion holes 78 of the dispersion plate 80 into the dispersion space 82 sequentially. In the dispersion space 82, the flow path cross-sectional area is large in the peripheral part where the flow rate is high, and the flow path cross-sectional area is small in the central part where the flow rate is low. In the dispersion space 82, the back pressure is maintained by the action of the cross-sectional area change (S ₃ > S ₄ ) by the dispersion plate 80 and the nozzle element 76, and a substantially uniform and stable pressure distribution is achieved. The uniform injection of the reaction gas is performed from the gas injection holes 74.

In the above, the heat medium is the heat medium unit 3
6 through the heat medium pipe 30, the nozzle panel 60, the peripheral wall 6
4 and the heat medium flow path 28 between the jacket 86 and the back plate 62, thereby maintaining each part at a predetermined temperature. Back plate 62, upper distribution plate 92, and distribution plates 92, 9
The four plates are adhered to each other at locations other than the groove 90, and the heat conduction between the distribution plate 92 and the back plate 62 and the distribution plates 92 and 94 is in a good state. Therefore, the distribution plate 9
The temperature of the gas distribution channel 9 is controlled indirectly by the back plate 62 and the temperature of the gas distribution channel 90 is precisely controlled.
It is possible to suppress the condensation and decomposition of the reaction gas at zero.

FIG. 7 shows another embodiment of the present invention. In this embodiment, a narrow portion 104 is formed at the boundary between the first mixing space 66a and the second mixing space 66b. That is, in the embodiment of FIG. 7A, a convex portion 106 extending in the circumferential direction is formed on the lower surface edge of the lower distribution plate 94, while in the embodiment of FIG. A projection 108 extending in the circumferential direction is formed below the inclined wall 102 on the upper surface of the projection 80. The flow path cross-sectional area of the narrow portion 104 selects an appropriate value equal to or smaller than that of the first mixing space 66a.

With such a configuration, the first mixing space 66
a, the inflow of gas into the second mixing space 66b from the outer periphery toward the center is uniformly controlled in the circumferential direction while maintaining the back pressure of
A uniform and stable pressure distribution can be formed in the mixing space 66b. Therefore, the dispersion space 82
, The in-plane uniformity of the gas flow leading to the nozzle plate 60 can be secured in advance, and the in-plane uniformity of the gas flow from each of the injection holes 74 of the nozzle board 60 can be finally improved.

[0030]

As described above, according to the present invention, at least two kinds of reaction gases are independently introduced into the peripheral portion of the gas mixing space by the gas distribution flow path, and then are introduced toward the center of the gas mixing space. In addition, during the inflow process into the gas mixing space, the flow is directed from the edge of the disc-shaped space to the center, so that pressure fluctuations and turbulence do not easily occur, and the reaction and decomposition of the mixed gas Is suppressed. Therefore, a reaction gas having a uniform concentration and components and a reaction gas containing no impurities can be jetted toward the substrate from the nozzle hole to stably perform high-quality film formation.
It is also easy to cope with the formation of a dielectric thin film having a high dielectric constant, which has a severe stability condition with respect to the reaction gas temperature.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view schematically showing a thin film vapor phase growth apparatus according to an embodiment of the present invention.

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

FIG. 3 is an exploded perspective view showing a reactive gas injection head of the present invention.

FIG. 4 is a view showing a distribution plate of the reactive gas injection head of the present invention.

FIG. 5 is a view taken in the direction of arrows AA in FIG. 2;

FIG. 6 is a sectional view of a main part of a nozzle element.

FIG. 7 is a sectional view of a reactive gas injection head according to another embodiment of the present invention.

[Explanation of symbols]

 28 Heat medium passage 36 Heat medium unit 60 Nozzle panel 62 Back plate 66 Gas mixing space 68 Injection head main body 70 Gas supply pipe 74 Gas injection hole 78 Gas dispersion hole 80 Dispersion plate 90 Gas distribution passage 92,94 Distribution plate 102 Inclined Wall 104 narrow part

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Masao Saito 11-1 Haneda Asahimachi, Ota-ku, Tokyo Inside the Ebara Corporation

Claims (5)

[Claims] 1. An injection head main body that forms a gas mixing space between a nozzle plate having a large number of gas injection holes and a back plate, and at least two types of gas mixing spaces connected to the injection head main body from the back plate side. A gas supply pipe for supplying a reaction gas of the type described above, and a gas distribution flow for guiding the at least two kinds of reaction gases from the gas supply pipe to a peripheral portion of the gas mixing space between the nozzle board and the back plate. A reaction gas injection head having a passage formed therein. 2. The gas distribution channel according to claim 1, wherein at least two distribution plates are arranged between the nozzle panel and the back plate, and the gas distribution passage is formed between the back plate and the distribution plate. The reaction gas injection head according to item 1. 3. The reactive gas injection according to claim 1, wherein a dispersion plate having a large number of gas dispersion holes is provided between the distribution plate and the nozzle plate in the gas mixing space. head. 4. The gas mixing space according to claim 1, wherein a wall at a peripheral portion of the gas mixing space is inclined inward from a gas distribution channel outlet toward a central portion of the gas mixing space. The reaction gas injection head according to item 1. 5. The reactive gas injection head according to claim 1, further comprising temperature maintaining means for maintaining said gas distribution channel and said nozzle panel at a predetermined temperature.