CVD APPARATUS AND METHOD FOR CLEANING CHAMBER OF CVD APPARATUS

A CVD apparatus includes a chamber, a susceptor, an entry/takeout port for a substrate, and a gate valve provided at the entry/takeout port, in which the susceptor has a mounting plate and a support, the entry/takeout port is provided on a part of a side of the chamber, and is provided in a range from an inner bottom surface of the chamber to a position corresponding to the lower surface of the mounting plate when the susceptor is located at an upper end in the vertical direction, and the inner bottom surface of the chamber, the range from the inner bottom surface of the chamber to the position corresponding to the lower surface of the mounting plate when the susceptor is located at the upper end in the vertical direction, the lower surface of the mounting plate, and the outer side surface of the support are coated with ceramic liners.

BACKGROUND OF THE INVENTION

Field of the Invention

The present disclosure relates to a CVD apparatus and a method for cleaning a chamber of a CVD apparatus.

Description of Related Art

The CVD apparatus is known as a thin film forming apparatus that forms a thin film by depositing a substance generated by a chemical reaction of a source gas containing a thin film component on the surface of a substrate. As the CVD apparatus, a plasma CVD apparatus is widely used. In a plasma CVD apparatus, a chemical reaction is promoted by exciting a source gas into a plasma state and generating active excited molecules, radicals, and ions. In the plasma CVD apparatus, a susceptor for supporting a substrate (for example, a silicon wafer) to be film-deposited is arranged in a chamber. A shower head for supplying a source gas to the inside of the chamber is arranged above the susceptor. Plasma is generated by applying a radio frequency (RF) voltage between the shower head and the susceptor.

In the CVD apparatus, film components may be deposited on the inner wall surface of the chamber and the surface of the susceptor due to the film formation. When the film thickness of the deposits of this film component becomes thick, the deposits may be separated from the inner wall surface of the chamber or the surface of the susceptor to become particles and adhere to the substrate to be treated or the thin film formed. Therefore, in order to remove the deposits inside the chamber, it is necessary to clean the chamber. As a chamber cleaning method, a method using two types of cleaning gases, a first cleaning gas and a second cleaning gas, is known (see, U.S. Pat. No. 6,843,858). As the first cleaning gas, a gas containing a fluorine compound is used, and as the second cleaning gas, a gas containing hydrogen, argon, an oxygen source, a fluorine compound and the like is used.

As a method of removing deposits in the chamber of the CVD apparatus, a method of using a cleaning gas containing a fluorine compound is effective. However, since the chamber is formed using a metal material such as aluminum, when a cleaning gas containing a fluorine compound is used, the metal inside the chamber reacts with the cleaning gas to generate a metal compound such as metal fluorides. When repeated cleaning is performed using a cleaning gas, metal compounds may be accumulated on the inner wall surface of the chamber, and the accumulated metal compounds may be separated from the inner wall surface of the chamber to become particles to adhere to the substrate to be processed or the thin film formed.

SUMMARY OF THE INVENTION

A first aspect of the present disclosure provides a CVD apparatus including a chamber, a cleaning gas supply pipe that supplies a cleaning gas to the chamber and an oxygen-containing gas supply pipe that supplies an oxygen-containing gas to the chamber, wherein the cleaning gas supply pipe has a first valve, the oxygen-containing gas supply pipe has a second valve, after the first valve is opened to supply the cleaning gas to the inside of the chamber, the second valve is opened to supply the oxygen-containing gas to the inside of the chamber with the first valve closed.

The CVD apparatus according to the aspect may include a source gas supply pipe that supplies a source gas to the chamber, wherein the source gas supply pipe, the cleaning gas supply pipe, and the oxygen-containing gas supply pipe may be each connected to the chamber via a gas supply pipe.

In the CVD apparatus according to the aspect, the cleaning gas supply pipe and the oxygen-containing gas supply pipe may include a remote plasma unit.

In the CVD apparatus according to the aspect, the oxygen-containing gas may contain oxygen and an inert gas.

In the CVD apparatus according to the aspect, the oxygen concentration of the oxygen-containing gas may be in the range of 40% by volume or more and 60% by volume or less.

In the CVD apparatus according to the aspect, the cleaning gas may be a fluorine-containing gas.

In the CVD apparatus according to the aspect, the fluorine-containing gas may contain a fluorine compound gas and an inert gas.

In the CVD apparatus according to the aspect, a gas outlet may be arranged along the inner wall surface of the chamber.

A second aspect of the present disclosure provides a method for cleaning a chamber of a CVD apparatus, including the following steps, a step of supplying a cleaning gas to the chamber, a step of stopping the supply of the cleaning gas to the chamber and supplying the oxygen-containing gas to the chamber.

In the method for cleaning a chamber of a CVD apparatus, the oxygen-containing gas may be supplied at a flow rate equal to or higher than the flow rate of the cleaning gas.

In the method for cleaning a chamber of a CVD apparatus, the oxygen-containing gas may be supplied for 50% or less of the supply time of the cleaning gas.

DETAILED DESCRIPTION OF THE INVENTION

Hereinafter, the present disclosure will be described in detail with reference to the drawings as appropriate. The drawings used in the following description may be enlarged for convenience in order to make the features of the present disclosure easy to understand, and the dimensional ratio of each component may differ from the actual one. The materials, dimensions, etc. exemplified in the following description are examples, and the present disclosure is not limited thereto and it is possible to appropriately change and implement the present disclosure within a range in which the effects of the present disclosure can be obtained.

FIG.1is a schematic configuration diagram of a CVD apparatus according to an embodiment of the present disclosure. As shown inFIG.1, the CVD apparatus100of the present embodiment includes a chamber10, a source gas supply pipe35that supplies a source gas to the chamber10, a cleaning gas supply pipe40that supplies a cleaning gas to the chamber10, and an oxygen-containing gas supply pipe50that supplies an oxygen-containing gas to the chamber10. InFIG.1, the chamber10is a partial cross-sectional view.

The chamber10is a substantially cylindrical body. The chamber10includes a chamber body11and a lid member19. The chamber body11and the lid member19are made of a metal material. As the metal material, for example, aluminum can be used.

An entry/takeout port12for a substrate1to be processed is provided on the side of the chamber body11. The entry/takeout port12can be opened and closed by a door member13. A recess14is provided on the inner wall surface of the chamber body11above the entry/takeout port12. A shower head fixing member15is arranged in the recess14. The shower head fixing member15is a ring-shaped member having a reversed conical opening16in which the diameter below is smaller than the diameter above. As the material of the shower head fixing member15, for example, a ceramic material such as Al2O3can be used.

The shower head20has a large number of vents21at the bottom thereof. The upper portion of the shower head20has a flange portion22which diameter is larger than the diameter of the opening of the shower head fixing member15. In the shower head20, the side portion below the flange portion22has a reversed conical side surface23having a lower outer peripheral diameter smaller than the upper outer peripheral diameter. The side surface23of the shower head20and the opening16of the shower head fixing member15are formed so as to be in close contact with each other. As the material of the shower head20, for example, a metal such as aluminum can be used.

A high-frequency shielding plate17is arranged between the shower head20and the lid member19. As the material of the high frequency shielding plate17, for example, a ceramic material such as Al2O3can be used.

The upper center of the shower head20is connected to a gas supply pipe30. The side portion of the gas supply pipe30is connected to the source gas supply pipe35. The upper portion31of the gas supply pipe30is connected to a RPU (remote plasma unit)60. The RPU60is connected to the cleaning gas supply pipe40and the oxygen-containing gas supply pipe50. The RPU60turns the cleaning gas and the oxygen-containing gas into plasma. The cleaning gas activates its cleaning power by being turned into plasma. The oxygen-containing gas activates its oxidizing power by being turned into plasma. The cleaning gas supply pipe40has a first valve41, and the oxygen-containing gas supply pipe50has a second valve51. The opening and closing of the first valve41and the second valve51is controlled by the controller70. The controller70controls to open the first valve41to supply cleaning gas to the inside of the chamber10, and then to open the second valve51to supply oxygen-containing gas to the inside of the chamber10with the first valve41closed.

As the cleaning gas flowing through the cleaning gas supply pipe40, for example, a fluorine-containing gas can be used. The fluorine-containing gas may be a mixed gas containing a fluorine compound gas and an inert gas. As the fluorine compound gas, for example, nitrogen trifluoride gas (NF3) and fluorocarbon gas (CxFy) can be used. As the inert gas, for example, helium gas, argon gas, and nitrogen gas can be used. The cleaning gas may contain oxygen. Each of these fluorine compound gas and the inert gas may be used alone or in combination of two or more.

The oxygen-containing gas flowing through the oxygen-containing gas supply pipe50may be a mixed gas containing oxygen and an inert gas. The oxygen concentration of the oxygen-containing gas may be in the range of 40% by volume or more and 60% by volume or less. As the inert gas, for example, helium gas, argon gas, and nitrogen gas can be used. These inert gases may be used alone or in combination of two or more.

A susceptor80is arranged inside the chamber10. The susceptor80has a mounting plate81and a support rod82that supports the mounting plate81. The substrate1to be processed is mounted on the upper surface of the mounting plate81. A lift mechanism83is provided below the support rod82, and the lift mechanism83is configured to move the susceptor80in the vertical direction. The mounting plate81and the support rod82of the susceptor80are made of a metal material such as aluminum.

A gas exhaust pipe90having a gas discharge port91is arranged inside the chamber10. The gas discharge port91is arranged along the inner wall surface of the chamber10.

A method of forming a thin film using the CVD apparatus100ofFIG.1will be described. The substrate1to be processed is placed on the upper surface of the mounting plate81of the susceptor80, and the susceptor80is moved to a predetermined position by using the lift mechanism83. Next, the source gas is supplied from the source gas supply pipe35to the shower head20via the gas supply pipe30, and the source gas is discharged from the ventilation holes21toward the substrate1to be processed. Next, a high frequency (RF) voltage is applied between the shower head20and the mounting plate81of the susceptor80using a high frequency power source (not shown) to bring the source gas into a plasma state. As a result, active excited molecules, radicals, and ions are generated, the chemical reaction is promoted, and a thin film is formed on the surface of the substrate1to be treated.

After the thin film is formed on the surface of the substrate1to be processed, the supply of the source gas is stopped. Next, the susceptor80is lowered by the lift mechanism83, and the mounting plate81is moved to the position of the entry/takeout port12. After that, the door member13is moved to open the entry/takeout port12, and the substrate1to be processed is taken out from the entry/takeout port12.

Next, a method for cleaning the chamber10of the present embodiment will be described.FIG.2is a schematic configuration diagram showing a state of an example when cleaning the chamber of the CVD apparatus shown inFIG.1.FIG.3is a cross-sectional view taken along the line ofFIG.2. InFIG.2, the cleaning of the chamber10is performed in a state where the substrate1to be processed is taken out from the entry/takeout port12, that is, in a state where the susceptor80is lowered. Cleaning of the chamber10is performed as follows.

First, the first valve41is opened to supply the cleaning gas2to the inside of the chamber10as shown inFIG.2. By opening the first valve41, the cleaning gas is sent from the upper portion31of the gas supply pipe30to the gas supply pipe30in a state where the cleaning gas is turned into plasma by the RPU60and the cleaning power is activated. The cleaning gas2sent to the gas supply pipe30is supplied to the shower head20and discharged into the chamber10through the ventilation holes21. The cleaning gas2released into the chamber10flows along the inner wall surface of the chamber10and the surface of the susceptor80. As a result, the cleaning gas2removes the deposits of the thin film components deposited on the inner wall surface of the chamber10and the surface of the susceptor80, and a part of the metal contained in the inner wall surface of the chamber10and the susceptor80reacts with the cleaning gas2to generate a metal compound. After that, the cleaning gas2flows to the gas exhaust pipe90through the gas discharge port91, and is then taken out from a gas outlet92(seeFIG.3). Since the gas discharge port91is arranged along the inner wall surface of the chamber10, the cleaning gas2easily flows along the inner wall surface of the chamber10.

The flow rate of the cleaning gas2supplied to the inside of the chamber10is, for example, in the range of 0.1 slpm (standard liter per minute) or more and 10 slpm or less. The supply time of the cleaning gas2is, for example, in the range of 20 seconds or more and 300 seconds or less.

Next, with the first valve41closed and the supply of the cleaning gas2to the inside of the chamber10stopped, the second valve51is opened to supply the oxygen-containing gas to the inside of the chamber10. By opening the second valve51, the oxygen-containing gas is turned into plasma by the RPU60and sent to the gas supply pipe30via the upper portion31of the gas supply pipe30in a state where the oxidizing power is activated. The oxygen-containing gas sent to the gas supply pipe30is supplied to the shower head20and is discharged into the chamber10through the ventilation holes21. The oxygen-containing gas released into the chamber10flows along the inner wall surface of the chamber10and the surface of the susceptor80, as in the case of the cleaning gas2shown inFIG.2. As a result, the metal compound formed on the inner wall surface of the chamber10and the surface of the susceptor80is partially oxidized. Therefore, in the chamber10cleaned by the cleaning method of the chamber10of the present embodiment, a complex oxide such as a fluoride oxide is generated on the inner wall surface and the surface of the susceptor80.

The flow rate of the oxygen-containing gas supplied to the inside of the chamber10is, for example, in the range of 2 times or more and 10 times or less the flow rate of the cleaning gas. The flow rate of the oxygen-containing gas may be equal to or higher than the flow rate of the cleaning gas. The supply time of the oxygen-containing gas is, for example, within the range of 1/10 or more and ½ or less of the cleaning time.

As described above, after the chamber10is cleaned, the door member13is moved to open the entry/takeout port12, and the substrate1to be processed is arranged on the mounting plate81of the susceptor80from the entry/takeout port12. Next, the susceptor80is moved to a predetermined position using the lift mechanism83to carry out film formation. The cleaning of the chamber10may be performed every time the film formation is performed, or may be performed after the film formation is performed a plurality of times.

In the CVD device100of the present embodiment having the above configuration, since the oxygen-containing gas can be supplied to the chamber10after the cleaning gas is supplied, even if the inside of the chamber is repeatedly cleaned with the cleaning gas, particles of the metal compound generated by the cleaning gas are less likely to be generated. It is considered that this is because the metal compound produced by the reaction between the chamber10and the cleaning gas is partially oxidized by the oxygen-containing gas.

In the CVD apparatus100of the present embodiment, in the configuration in which it has a source gas supply pipe35for supplying the source gas to the chamber10, and the source gas supply pipe35, the cleaning gas supply pipe40, and the oxygen-containing gas supply pipe50are connected to the chamber10via the gas supply pipe30, respectively, since the flow paths of the source gas and the cleaning gas inside the chamber10are the same, the efficiency of removing the deposits of the film components generated at the time of film formation tends to be improved. Further, since the flow paths of the cleaning gas and the oxygen-containing gas are the same, the effect of suppressing the generation of particles of the metal compound generated by the cleaning gas tends to be improved.

In the CVD apparatus100of the present embodiment, in the configuration in which the cleaning gas supply pipe40includes an RPU60, since the cleaning gas is activated and the cleaning power becomes higher, the efficiency of removing deposits of film components generated during film formation tends to be improved. Further, in the configuration in which the oxygen-containing gas supply pipe50includes an RPU60, since the oxygen-containing gas is activated and the oxidizing power becomes higher, the effect of suppressing the generation of particles of the metal compound generated by the cleaning gas tends to be improved.

In the CVD apparatus100of the present embodiment, when the oxygen-containing gas contains oxygen and an inert gas, it tends to be easy to partially oxidize the metal compound produced by the cleaning gas. Further, when the oxygen concentration of the oxygen-containing gas is in the range of 40% by volume or more and 60% by volume or less, the metal compound tends to be more easily oxidized.

In the CVD apparatus100of the present embodiment, when the cleaning gas is a fluorine-containing gas, the efficiency of removing deposits of film components generated during film formation tends to be further improved. Further, when the fluorine-containing gas contains a fluorine compound gas and an inert gas, the amount of metal compounds produced by the reaction of the metal with the cleaning gas inside the chamber10tends to decrease.

In the CVD apparatus100of the present embodiment, when the gas discharge port91is arranged along the inner wall surface of the chamber10, the cleaning gas easily flows along the inner wall surface of the chamber10. Therefore, the efficiency of removing the deposits of the film components deposited on the inner wall surface of the chamber10at the time of film formation tends to be improved.

Further, according to the method for cleaning the chamber10of the CVD apparatus100of the present embodiment, since the step of supplying the oxygen-containing gas to the chamber10is performed after performing the step of supplying the cleaning gas to the chamber10, even if the inside of the chamber is repeatedly cleaned with the cleaning gas, particles of the metal compound generated by the cleaning gas are less likely to be generated.

According to the method for cleaning the chamber10of the CVD apparatus100of the present embodiment, when the oxygen-containing gas in the step of supplying the oxygen-containing gas is supplied at a flow rate higher than the flow rate of the cleaning gas in the step of supplying the cleaning gas, oxidation of the metal compound generated by the cleaning gas tends to proceed uniformly, and the effect of suppressing the generation of particles tends to be improved.

According to the method for cleaning the chamber10of the CVD apparatus100of the present embodiment, when the oxygen-containing gas is supplied for 50% or less of the supply time of the cleaning gas, since excessive oxidation of the metal compound generated by the cleaning gas is suppressed, particles of the metal oxide tend to be less likely to be generated.

The embodiments of the present disclosure have been described so far with reference to the drawings. The present disclosure is not limited to the above-described embodiment, and can be appropriately modified without departing from the technical idea of the present disclosure. For example, in the present embodiment, the opening and closing of the first valve41and the second valve51is controlled by using the controller70, but the present disclosure is not limited to this. For example, the first valve41and the second valve51may be opened and closed manually.

Further, in the present embodiment, the cleaning gas supply pipe40and the oxygen-containing gas supply pipe50are connected to the same RPU60, respectively, and the cleaning gas and the oxygen-containing gas are supplied to the chamber10by the same path, but the present disclosure is not limited to this. For example, the cleaning gas supply pipe40and the oxygen-containing gas supply pipe50may be connected to different RPUs, or the cleaning gas and the oxygen-containing gas may be supplied to the chamber10by different paths.

Further, in the present embodiment, the chamber10is cleaned with the susceptor80lowered, but the present disclosure is not limited to this. For example, the chamber10may be cleaned with the susceptor80raised.

Further, in the present embodiment, the gas discharge port91is arranged along the inner wall surface of the chamber10, but the present disclosure is not limited to this. For example, the gas discharge port91may be arranged around the support rod82of the susceptor80at the bottom of the chamber10.

A CVD apparatus100having the configuration shown inFIG.1was prepared. The materials of the chamber body11of the chamber10, the lid material19, the shower head20, the mounting plate81of the susceptor80, and the support rod82are each made of aluminum. The inner diameter of the chamber10is 425 mm and the capacity is 15 L.

The substrate1to be processed was placed on the mounting plate81of the susceptor80, and a thin film was formed on the surface of the substrate1to be processed by the CVD method. A silicon wafer was used as the substrate1to be processed, and an organosilane-based material was used as the source gas. After the film formation, the susceptor80was lowered to take out the substrate1to be processed from the chamber10.

With the susceptor80lowered, the first valve41was opened, and plasma-generated cleaning gas (NF3) was supplied to the inside of the chamber10at a flow rate of 0.5 slpm for 30 seconds. After that, with the first valve41closed, the second valve51is opened, and the inside of the chamber10was cleaned with the oxygen-containing gas (oxygen/argon, oxygen concentration: 50% by volume) plasma-generated as the oxygen amount at a flow rate of 2 slpm for 5 seconds.

1000 cycles were carried out, with the operation of performing film formation once and cleaning once as one cycle. After that, (1) deposits adhering to the surface around the ventilation hole21of the shower head20, (2) deposits adhering to the side surface of the gas exhaust pipe90, (3) deposits adhering to the circumference of the support rod82of the susceptor80on the bottom surface of the chamber10, and (4) deposits adhering to the periphery of the gas exhaust pipe90at the bottom surface of the chamber10were taken out, and the deposits were elementally analyzed using TOF-SIMS (time-of-flight secondary ion mass spectrometry). The result (mass spectrum) is shown inFIG.4. As shown in the mass spectrum ofFIG.4, aluminum fluoride oxide was detected in each of the deposits at each of the locations (1) to (4). Moreover, when the surface of the thin film obtained by the film formation at the 1000th cycle was observed, no particles were observed on the surface of the thin film. It is considered that the reason why the particles were not generated is that the adhesion with aluminum constituting the base material was improved because the aluminum fluoride produced by the cleaning gas was partially oxidized by the oxygen-containing gas to form a passivation film containing fluoride oxide on the surface.

Comparative Example 1

In the cleaning of Example 1, the same procedure as in Example 1 was carried out except that the oxygen-containing gas was not supplied after the plasma-generated cleaning gas was supplied to the inside of the chamber10, 1000 cycles were carried out, with the operation of performing film formation once and cleaning once as one cycle. Then, in the same manner as in Example 1, the deposits adhering at each of the locations (1) to (4) were elementally analyzed. As a result, the deposits at each of the locations (1) to (4) were all aluminum fluoride. Moreover, when the surface of the thin film obtained by the film formation at the 1000th cycle was observed, slight adhesion of particles was observed on the surface of the thin film. From this result, it was confirmed that the aluminum fluoride has low adhesion to aluminum constituting the base material and is easily desorbed from the aluminum.