JP2000150497A - Film forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a film forming device which can protect a formed film from deteriorating caused by deposition which is inevitably generated on a vaporizer or on its downstream side and form a high quality film. SOLUTION: A vaporizer 10 which vaporizes liquid raw material, an airtight film forming chamber 12 in which a film is formed on a substrate by using raw material gas generated by the vaporizer 10 and a raw material gas conveying flow path 16b which links the vaporizer 10 with the film forming chamber are provided. Filters 32a and 32b which capture particles contained in the raw material gas are provided in the flow path 16b at positions immediately before the film forming chamber.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a film forming apparatus,
In particular, the present invention relates to a film forming apparatus used for forming a high dielectric or ferroelectric thin film such as barium titanate / 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,
A capacitor element that can obtain 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 (Ta ₂ O ₅ ) thin film 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. Or, a metal oxide thin film material such as barium titanate (BaTiO ₃ ), strontium titanate (SrTiO ₃ ), or barium strontium titanate having a dielectric constant of about 300 is considered promising. Further, PZT, PLZT, and Y having higher dielectric constants
Ferroelectric thin film materials such as 1 are also promising.

As a method for forming such a material, chemical vapor deposition (CVD) is considered to be promising. FIG. 4 is a diagram showing the overall 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, which is located downstream of a vaporizer 110 for vaporizing a liquid raw material. A film formation chamber (film formation chamber) 114 that can be hermetically sealed via a raw material gas transfer channel 112 is provided, and a vacuum pump 116 is disposed in an exhaust flow channel 118 on the downstream side. 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 the substrate holding / heating table 124, and the nozzle holes 126 of the gas supply head 128 are maintained while the substrate W is maintained at a predetermined temperature.
Then, a mixed gas of a source gas and an oxidizing gas is jetted toward the substrate W to grow a thin film on the surface of the substrate W. In this case, it is necessary to stably supply the source gas to the deposition target substrate in the deposition chamber. The raw material gas is Ba which is solid at room temperature.
(DPM) ₂ , Sr (DPM) _2, etc. are dissolved, and tetrahydrofuran (T
It is generated by heating a liquid raw material mixed with an organic solvent such as HF) by a vaporizer and vaporizing the raw material.

[0005]

However, the above-mentioned liquid raw materials generally have a vaporization temperature and a decomposition temperature close to each other, and have a difference between the vaporization temperature and the vaporization temperature of the organic solvent.
It has characteristics that make vaporization difficult, such as extremely low vapor pressure, easy change in quality due to the presence of trace amounts of oxygen and water vapor, and the like. Metal oxides, metal salts, and the like may be generated inside the vessel and on the downstream side thereof and adhere to the wall surface.
Such deposits not only block the passage inside the vaporizer and hinder stable operation, but also form particles when separated by a small amount, and flow into the deposition chamber to deteriorate the quality of the deposition. I will.

In order to prevent this, the inside of the vaporizer or the downstream pipe is cleaned as necessary or periodically using a solvent of the raw material liquid or an organic solvent similar thereto as a cleaning liquid. However, in such a method,
Although organic stains can be washed, inorganic substances such as metal oxides and metal salts are difficult to dissolve in a solvent, so that washing is difficult.

It is conceivable to clean the vaporizer and its downstream side by using an acid or the like which also dissolves inorganic substances as a cleaning liquid. In this case, the vaporizer made of metal such as stainless steel or the downstream side is used. The problem of corroding the piping arises. In addition, it is conceivable to forcibly or forcibly drain the deposits on the vaporizer and the downstream pipe with a fluid, but it is difficult to completely remove inorganic substances, and the flow rate and pressure of the fluid are excessive. It is not realistic.

The present invention has been made in view of the above-mentioned problems, and prevents a film from deteriorating due to an inevitably generated deposit on a vaporizer and a downstream side thereof, thereby performing high-quality film formation. It is an object of the present invention to provide a film forming apparatus capable of performing the above.

[0009]

According to a first aspect of the present invention, there is provided a vaporizer for vaporizing a liquid raw material, and a hermetic film formation for forming a film on a substrate using the raw material gas generated by the vaporizer. Chamber, and a source gas transfer channel that communicates the vaporizer and the film formation chamber, and a filter that captures particles contained in the source gas at a position immediately before the film formation chamber of the source gas transfer channel. The film forming apparatus is provided.

Thus, even if the deposits and the like adhering to the vaporizer and the piping are separated and contained as particles in the source gas transported in the source gas transport passage, these particles are removed by the filter. Therefore, it is possible to prevent particles from flowing into the film formation chamber and mixing with the film on the substrate, thereby deteriorating the film formation quality. In addition, since the filter is provided immediately before the film forming chamber, even if particles are generated on the downstream side of the filter, the amount can be reduced to such a small amount that does not affect the quality of film formation.

According to a second aspect of the present invention, there is provided an opening and closing means for providing a cleaning liquid to the filter to clean the filter, and for restricting a flow of the cleaning liquid between the filter and the film forming chamber. The film forming apparatus according to claim 1, further comprising a valve. Thus, the particles captured by the filter are removed by performing the cleaning step, and the operation can be continued without replacing the filter. In addition, it is possible to regulate the flow of the cleaning liquid into a place where cleaning is unnecessary or inappropriate.

The cleaning liquid can be appropriately selected according to the type of the adhered substance to be treated. By using the same solvent as that used for preparing the liquid material, the dissolution of the adhered substance is promoted, and the cleaning liquid is vaporized. Or inside the filter, it does not hinder the vapor phase growth and quality of the metal oxide thin film. It is desirable to control the temperature of the cleaning liquid to a predetermined temperature in order to promote the dissolution of the adhered substance, whereby the temperature of the vaporizer or the like can be prevented from decreasing and the time required for restarting the apparatus can be shortened. The cleaning liquid may be introduced at a high pressure in order to keep the cleaning liquid in a liquid state, or a part of the cleaning liquid may be intentionally vaporized to promote the cleaning by stirring.

[0013] The invention according to claim 3 is characterized in that the on-off valve is provided with a cleaning liquid port for rotating a cleaning liquid through a valve body and / or a valve seat, and the cleaning flow path is connected to this cleaning liquid port. The film forming apparatus according to claim 2, wherein Thus, the deposits on the valve body of the on-off valve and the like are washed, and the generation of particles in the on-off valve and the malfunction of the valve are prevented.

According to a fourth aspect of the present invention, there is provided a vaporizer for vaporizing a liquid raw material, an airtight film forming chamber for forming a film on a substrate by using the raw material gas generated by the vaporizer, and the vaporizer. A source gas transfer channel that communicates with the film forming chamber; and an on-off valve that opens and closes the source gas transfer channel. And a filter for capturing particles contained in the film forming apparatus. Accordingly, it is possible to prevent solid matter from adhering to a valve seat or the like of the on-off valve, and prevent malfunction of the on-off valve and generation of particles.

According to a fifth aspect of the present invention, in the filter according to any one of the first to fourth aspects, a heat medium flow path for circulating a heat medium for heating is provided in the filter. It is a film forming apparatus. Thus, the temperature of the source gas is prevented from changing by maintaining the filter at a predetermined temperature.

[0016]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a schematic configuration of a film forming apparatus according to a first embodiment of the present invention, in which a vaporizer 10 having a heater 14 for heating a liquid raw material to a vaporization temperature or higher.
And an airtight film forming chamber 12 disposed downstream of the vaporizer 10.
It has. The vaporizer 10 is connected to a liquid source (not shown) via a liquid source channel 16a having an on-off valve 30a. In the film forming chamber 12, a substrate holding table 20 for holding and heating the substrate W, and a source gas supplied from the vaporizer 10 and an oxidizing gas supplied from the oxidizing gas supply channel 18 are mixed to form a nozzle hole. And a gas supply head 22 for jetting from 24 toward the substrate W. Exhaust pipe 25 of film forming chamber 12
Is provided with a trap 26 and an exhaust pump 28.

The downstream pipe of the vaporizer 10 is branched into a raw material gas transfer passage 16 b toward the film forming chamber 12 and a cleaning liquid return pipe 40 a descending toward the cleaning liquid tank 42. A first filter 32a is provided in the source gas transfer passage 16b near a branch point from the cleaning liquid return pipe 40a, and further includes an on-off valve 30b and a film forming chamber 1 downstream thereof.
2, a second filter 32b is provided. In each of these filters 32a and 32b, for example, a heat medium flow path 34a through which a heat medium for heating such as heating oil flows.
34b are provided.

The film forming apparatus includes a cleaning system for cleaning the vaporizer 10 and fluid pipes before and after the vaporizer 10 (part of the liquid raw material flow path 16a and the raw material gas transfer flow path 16b including the filters 32a and 32b). Is provided. this is,
Cleaning liquid tank 42 provided downstream of cleaning liquid return pipe 40a
A main cleaning channel 40 having a circulation pump 44 and a filter 46 from an outlet of the cleaning liquid tank 42, and first and second cleaning channels 40b and 40c branched from the main cleaning channel 40 downstream of the filter 46. And

The first washing flow path 40b is connected to the on-off valve 30a of the liquid material flow path 16a and the vaporizer 1 via the on-off valve 30c.
0, and passes through the vaporizer 10 and returns to the cleaning liquid return pipe 40a. The second cleaning flow path 40c is connected to the source gas transport flow via the on-off valve 30e. It merges into a portion of the passage 16b between the on-off valve 30b and the first filter 32a, passes through the first filter 32a, and returns to the cleaning liquid return pipe 40a.

The main cleaning channel 40 is provided with an accumulator 50 for containing a pressurized gas for pressurizing the entire channel. The cleaning liquid tank 42 has a heater 5 for heating the cleaning liquid 48 to the operating temperature of the vaporizer 10, for example, 250 ° C.
2 are provided. As the cleaning liquid 48, for example, TH
By using the same solvent as used in the preparation of the liquid raw material such as F, the dissolution of the deposit is promoted, and even if the cleaning liquid remains inside the vaporizer 10 or the filter 32a, the metal oxide thin film It does not hinder vapor phase growth. Each of the cleaning channels 40, 40b, and 40c may also be provided with a heater or the like for preventing the temperature of the cleaning liquid flowing inside from decreasing.

Next, the operation of the film forming apparatus of this embodiment will be described. In the film forming process, the three on-off valves 30c, 30d, and 30e in the cleaning channel 40 are closed, and the two on-off valves 3c in the liquid source channel 16a and the source gas transport channel 16b are closed.
0a and 30b are opened, the liquid raw material supplied from the liquid raw material flow path 16a is vaporized by the vaporizer 10, and the raw material gas transport flow path 1
The film is sent to the film forming chamber 12 through 6b. In the film forming chamber 12, a gas mixture of a source gas and an oxidizing gas is generated in the gas supply head 22, and the mixed gas is injected from the nozzle hole 24 toward the substrate W placed on the substrate holder 20 to form a film.

At this time, inorganic substances and the like which adhere to the vaporizer 10 and the downstream side thereof and are not removed even in the cleaning step are peeled off.
Even if the particles are contained in the vaporized source gas, the particles are removed by the filters 32a and 32b in the source gas transfer passage 16b. Therefore, this is the film forming chamber 1
2 and mixed into the coating on the substrate to prevent deterioration in quality. By flowing a heating medium such as a heating oil heated to about 250 ° C. into the heating medium passages 34a and 34b of the filters 32a and 32b, the raw material gas is prevented from condensing in the filters 34a and 34b, and is stable. Operation is performed.

When cleaning the vaporizer 10 and the first filter 32a in the source gas transfer passage 16b, the two on-off valves 30a and 30b in the liquid source passage 16a and the source gas transfer passage 16b are closed. Then, the three open / close valves 30c, 30d, and 30e in the cleaning flow path 40 are opened to make the cleaning flow path 40 a closed system. The cleaning liquid 48 is preliminarily heated to about 250 ° C., which is the operating temperature of the vaporizer 10, by the heater 52, and the accumulator 50 is used to set the cleaning flow path to the vapor pressure of the cleaning liquid at the operating temperature of the vaporizer, for example, 41 kg / c.
while pressing the m ² or more, to operate the circulation pump 44.

After the solid components have been removed by the filter 46, the cleaning liquid 48 has a temperature of about 250.degree.
While maintaining a liquid state at a high pressure of not less than kg / cm ^{2, the} gas flows into the vaporizer 10 and the inside of the first filter 32 a in the raw material gas transfer passage 16 b, and deposits (dirt) or raw material gas The first filter 32 in the transport channel 16b
The inside of the first filter 32a in the vaporizer 10 and the raw material gas transfer passage 16b is washed by dissolving or accompanying the particles and solids trapped by a. The cleaning liquid 48 that has cleaned the first filter 32a in the vaporizer 10 and the raw material gas transfer flow path 16b returns to the tank 42 from the cleaning flow path 40. In this manner, the cleaning liquid can be supplied to the vaporizer or the like while maintaining the liquid state of the cleaning liquid under high pressure, and can be efficiently cleaned.

In this cleaning step, the second filter 32b in the raw material gas transfer passage 16b is not cleaned. This second filter 32b is already the first filter 32a
This is because particles contained in the raw material gas that has passed through are trapped, and the amount of trapped particles is small. For example, it is sufficient to replace the particles during regular maintenance.

When the cleaning step is completed, the three on-off valves 30c, 30d and 30e in the cleaning flow path 40 are closed, and the two on-off valves 30a and 30b in the liquid raw material flow path 16a and the raw material gas transport flow path 16b are opened. To restart the film forming process. In this embodiment, since the cleaning liquid 48 is heated to the operating temperature of the vaporizer 10, the temperature of the vaporizer 10 does not decrease in the cleaning process, and therefore, the startup time of the vaporizer 10 is minimized. Can be. The cleaning liquid may be flowed at a lower temperature than the operating temperature, for example, at normal temperature. Although the temperature of the vaporizer decreases to a certain extent, if the temperature decreases only slightly, the time required for reheating is short, and the time loss is small.

In the above-described process, the accumulator 50 controls the pressure of the cleaning channels 40b and 40c to 4 pressure.
Although the pressure is set to 1 kg / cm ² or more, the pressure may be set lower than this, and the cleaning may be performed under a condition that allows partial vaporization. In this case, especially when the temperature of the cleaning liquid is set lower than the temperature of the vaporizer 10, the cleaning liquid boils inside the vaporizer 10 on the inner wall portion thereof, thereby generating turbulence and agitating the adhering substances. Removal, dissolution or removal by entrainment is efficient. Further, instead of the pressure holding means by the accumulator 50, a pressure regulating valve may be provided at the end of the cleaning area, and the primary pressure may be maintained at a pressure higher than the cracking pressure of the pressure regulating valve.

Further, in this embodiment, an example is shown in which two filters 32a and 32b are provided in the raw material gas transport passage 16b, but only one of them may be provided. For example, the first filter 3 upstream of the on-off valve 30b
When only 2a is provided, the downstream side of the on-off valve 30b of the raw material gas transfer passage 16b is completely kept warm so that no deposit is generated on the downstream side of the on-off valve 30b. On the other hand, when the generation of particles as a whole is small and the amount captured by the filters is small, only the second filter 32b downstream of the on-off valve 30b may be used.

FIG. 2 shows a second embodiment of the present invention. This embodiment is different from the first embodiment in that the film forming chamber 12 of the source gas transfer passage 16b is formed. A filter 32 having a heat medium flow path 34 and an on-off valve 30b on the downstream side of the filter 32 are provided immediately before, and a second washing flow path 40c is connected between the filter 32 and the on-off valve 30b. .

According to this embodiment, the filter 32 is provided immediately before the film forming chamber 12 at the end of the material gas transfer passage 16b, thereby removing particles from the source gas supplied to the film forming chamber. In the cleaning process, the filter 32
The washing liquid can be washed by flowing a washing liquid inside.

FIG. 3 shows a third embodiment.
The difference from the second embodiment is that the on-off valve 6 with a cleaning liquid port is used instead of the on-off valve 30b downstream of the filter 32.
0 is provided in the source gas transport channel 16b, and the second cleaning channel 40c of the cleaning channel 40 is connected to the cleaning port 60a of the on-off valve 60 with the cleaning liquid port. As a result, the cleaning liquid can also be circulated through the valve seat 62 and the valve body 64 of the on-off valve 60 to clean them, and it is possible to prevent leakage due to deposits and the like adhering thereto. It goes without saying that the on-off valve 60 with the cleaning liquid port may be used for the on-off valve 30b of the first embodiment.

[0032]

As described above, according to the present invention,
Particles generated by exfoliating deposits and the like adhering to the vaporizer and piping are removed by the filter, so the particles flow into the film formation chamber and mix into the film on the substrate, deteriorating the quality of film formation. Is prevented. Therefore, it is possible to form a film of a material such as a high-ferroelectric material, for which it is difficult to obtain the stability of the source gas, smoothly and with high quality.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a film forming apparatus according to a first embodiment of the present invention.

FIG. 2 is a diagram illustrating a film forming apparatus according to a second embodiment of the present invention.

FIG. 3 is an enlarged view showing a part of a film forming apparatus according to a third embodiment of the present invention.

FIG. 4 is a view showing the whole of a conventional film forming apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Vaporizer 12 Film-forming chamber 16a Liquid source flow path 16b Source gas transfer flow path 20 Substrate holder 22 Gas supply head 30a, 30b, 30c, 30d, 30e Open / close valve 32, 32a, 32b Filter 34, 34a, 34b Heat medium Flow path 40 Main cleaning flow path 40b, 40c Cleaning flow path 48 Cleaning liquid

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification FI FI Theme Court ゛ (Reference) H01L 21/822 (72) Inventor Yuji Araki 11-1 Haneda Asahimachi, Ota-ku, Tokyo Inside Ebara Corporation (72) Inventor Mitsunao Shibasaki 11-1 Haneda Asahimachi, Ota-ku, Tokyo F-term in Ebara Corporation (reference) 4K030 AA11 BA42 EA01 KA22 KA45 KA49 5F038 AC15 EZ14 EZ20 5F045 BB15 DP01 EC07 EE03 EE04 EE10 5F083 AD00 FR01 JA06 JA14 JA15 PR21

Claims (5)

[Claims] 1. A vaporizer for vaporizing a liquid raw material, an airtight film forming chamber for forming a film on a substrate using the raw material gas generated by the vaporizer, and a communication between the vaporizer and the film forming chamber. And a filter for trapping particles contained in the source gas at a position immediately before the film forming chamber in the source gas transport channel. 2. A cleaning flow path for supplying a cleaning liquid to the filter to clean the filter, and an on-off valve for restricting a flow of the cleaning liquid between the filter and the film forming chamber is provided. The film forming apparatus according to claim 1, wherein: 3. The cleaning valve according to claim 2, wherein the on-off valve is provided with a cleaning liquid port for rotating a cleaning liquid through a valve body and / or a valve seat, and the cleaning flow path is connected to the cleaning liquid port. A film forming apparatus as described in the above. 4. A vaporizer for vaporizing a liquid raw material, an airtight film forming chamber for forming a film on a substrate using the raw material gas generated by the vaporizer, and a communication between the vaporizer and the film forming chamber. A source gas transfer channel, and an on-off valve for opening and closing the source gas transfer channel, and trapping particles contained in the source gas at a location on the upstream side of the on-off valve of the source gas transfer channel. A film forming apparatus provided with a filter. 5. The film forming apparatus according to claim 1, wherein the filter is provided with a heat medium passage through which a heat medium for heating flows.