JP2807674B2 - Processing apparatus and cleaning method for processing apparatus - Google Patents

Description

The present invention relates to a processing apparatus and a method for cleaning the processing apparatus.

(Prior Art) Conventionally, as a method of forming a thin film on a substrate such as a semiconductor wafer, CVD (chemical vapor deposition) is often used. This CVD is performed using, for example, a cold wall type CVD apparatus. Cold wall type CVD
The apparatus heats a substrate via a susceptor in order to suppress a reaction in a gas phase. FIG. 4 shows an example of a cold wall type CVD apparatus. This apparatus includes a stepped cylindrical processing container 1 and a cylindrical high-frequency electrode 5 inserted into the processing container 1 through an opening provided on the bottom surface of the processing container 1 and connected to a high-frequency power supply 6. I have it. A flange is provided on the lower circumference of the cylindrical high-frequency electrode 5, and the flange is fixed to the bottom surface of the processing chamber 1 via a ring-shaped insulating member 8. The upper small cylindrical part of the stepped cylindrical processing vessel 1 is a gas introduction chamber 1a, and the lower large cylindrical part is a processing chamber 1b. A gas introduction pipe 4 for introducing a source gas is provided on the upper surface of the gas introduction chamber 1a. Further, a gas discharge pipe 9 for discharging the raw material gas is provided on a side surface of the processing chamber 1b. further,
In the processing chamber 1b, a susceptor 3 for mounting and heating the substrate 2 as a processing target is provided.

The formation of a thin film using the cold wall type CVD apparatus shown in FIG. 4 is performed as follows. First, the pressure inside the processing container 1 is reduced to a predetermined pressure in advance. Next, a source gas for forming a thin film is introduced into the processing chamber 1b from the gas introduction pipe 4 through the gas introduction chamber 1a. After introducing the raw material gas into the processing chamber 1b, a thin film is formed by ordinary thermal CVD. After forming the thin film, the gas is discharged from the gas discharge pipe 9.

In the cold-wall type CVD apparatus, a cleaning process using plasma is usually performed on a surface of an object to be processed, for example, a semiconductor wafer, as a pre-process.
This is to remove a natural oxide film or the like formed on the surface of the substrate. Since the natural oxide film formed on the surface of the wafer electrically acts as an insulating film, it is desirable to remove the natural oxide film as it is highly integrated with 4M and 16M. Similarly, it is desirable to remove undesired impurities deposited on the inner wall of the reaction vessel and the surface of the susceptor. This is because when forming a thin film on the wafer surface, there is a possibility that these impurities are peeled off and adhere to the wafer. The cleaning process can be used to remove impurities deposited not only on the wafer surface but also on portions other than the wafer. This cleaning process is generally performed as follows. First, a chemically stable cleaning gas is introduced into the processing container 1 instead of the source gas. Thereafter, a high-frequency current is supplied to the high-frequency electrode 5 and the processing vessel 1
The gas introduced into the chamber is brought into a plasma state. Next, the object to be cleaned is cleaned by etching with this plasma. Such a cleaning technique is disclosed in, for example, JP-A-59-142839.

(Problems to be Solved by the Invention) Meanwhile, the above-described CVD apparatus generally takes a large space on a wafer. This improves the flow of source gas by increasing the space on the wafer,
In addition, the ratio of the amount of the source gas supplied into the processing container to the amount of the source gas consumed in the processing container is increased. Thereby, uniform film thickness and film quality can be secured. Therefore, the CVD apparatus is usually performed by applying a high-frequency electric field between the high-frequency electrode and the inner wall of the processing vessel corresponding to the ground electrode. For this reason, the distance between the electrodes becomes longer, the intensity of the electric field generated between the high-frequency electrode and the processing vessel becomes weaker, and it becomes difficult to obtain a plasma of high energy required for performing etching. As a result, cleaning of the wafer surface, the susceptor surface, and the like cannot be performed completely. In addition, since the energy of the generated plasma is low, there is a problem that the time required for cleaning becomes longer and the time required for the entire operation becomes longer.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned points, and performs a complete cleaning of the inside of a processing container and an object to be processed before performing the processing, thereby performing processing and cleaning of a processing apparatus capable of performing a good processing. Get the way.

[Configuration of the invention]

(Means for Solving the Problems) The present invention provides a process for introducing a cleaning gas of SF ₆ , NF ₃ , or CF ₄ into a processing vessel; Cleaning the inside of the processing container by converting the cleaning gas into plasma.

The invention according to claim 2 is a step of reducing the pressure in the processing container to a predetermined pressure, a step of introducing a cleaning gas into the processing container, a step of forming a magnetic field in the processing container, A step of applying a high-frequency voltage between an electrode to be mounted and an electrode or a processing container disposed so as to face the electrode to form an electric field in the processing container to generate plasma. Features.

The invention according to claim 3 is the cleaning method of the processing apparatus according to claim 1 or 2, wherein the cleaning of the inside of the processing device is performed in advance each time the object to be processed is loaded into the processing container.

According to a fourth aspect of the present invention, there is provided a processing device for receiving and processing an object to be processed, a magnetic field forming means provided outside the processing device and for forming a magnetic field inside the processing device, Microwave introduction means for introducing microwaves into the inside of the processing device from the outside, and a processing gas or SF ₆ , NF ₃ , CF ₄ connected to the vicinity of the microwave introduction portion of the processing device inside the processing device. A gas introduction pipe for introducing any one of the cleaning gases therein, and a discharge pipe for discharging a gas inside the processing apparatus, wherein the cleaning gas is introduced from the gas introduction pipe,
A plasma is generated inside the processing vessel by the microwave introducing means and the magnetic field forming means, and the inside of the processing vessel is cleaned.

(Function and Effect) That is, according to the present invention, a step of introducing a cleaning gas into a processing container and a step of cleaning the processing container by turning the cleaning gas into plasma in an electric field and a magnetic field atmosphere in the processing container. Is provided, high-energy plasma is generated, and the inside of the processing container and the like can be completely and quickly cleaned.

Further, every time the object to be processed is carried into the processing container, by performing cleaning in the processing container in advance, after completely removing impurities that hinder processing from the processing container,
An object to be processed can be processed.

(Example) Next, an example of the present invention will be described with reference to the drawings.

FIG. 1 is a diagram schematically showing a cross section of an apparatus that can be used in the method of the present invention. As shown in FIG. 1, a vacuum vessel 11 which is a cylindrical processing vessel having a step has an upper small cylindrical portion and a lower large cylindrical portion. The upper small cylindrical part is a gas introduction chamber 11a, and the lower large cylindrical part is a processing chamber 11b. A gas introduction pipe 14 for introducing a gas is provided on the upper surface of the gas introduction chamber 11a. A cleaning gas is introduced from the gas introduction pipe 14 when performing a cleaning process, and a raw material gas is introduced when performing a thin film formation. Further, a plurality of gas discharge pipes 20 for discharging gas are provided on the same circumference on the side surface of the lower large cylindrical portion 11b. The gas after each processing is discharged through the gas discharge pipe 20. Furthermore, processing room 11
Inside b, a susceptor 13 for mounting and heating an object to be processed, for example, a semiconductor wafer 12, is provided.

An annular magnetic coil 15 is provided on the outer surface of the gas introduction chamber 11a, substantially parallel to the susceptor 13 disposed inside the vacuum vessel 11. This annular magnetic coil 15
Generates a magnetic field in the vacuum chamber 11.

An opening 11c is formed on the lower surface of the vacuum vessel 11. The cylindrical high-frequency electrode 17 is inserted into the inside of the vacuum vessel 11 through the opening 11c. Cylindrical high-frequency electrode 17
A flange is provided on a lower circumference of the vacuum container 11, and the flange is fixed to the bottom surface of the vacuum vessel 11 via a ring-shaped insulating member 18. This high-frequency electrode 17 has a high-frequency power supply 16
Is connected. The susceptor 13 is on the upper surface of the high-frequency electrode 17
Is placed. Further, inside the high-frequency electrode 17, a heating mechanism for heating the susceptor 13, for example, a heater 19 is housed.

The method of forming a thin film according to the invention using such an apparatus will be described below.

First, the inside of the vacuum vessel 11 is reduced to a predetermined pressure, for example, 10 ⁻⁶ Torr by an exhaust device not shown. Thereafter, a cleaning gas, for example, NF ₃ is supplied to the gas introduction pipe 14.
From the gas introduction chamber 11a.

Next, a current is applied to the annular magnetic coil 15 to form a magnetic field A in the vacuum chamber 11. Further, high-frequency power is supplied to the high-frequency electrode 17 to form an electric field B in the vacuum vessel 11. The frequency of the high-frequency power supplied to the high-frequency electrode 17 is, for example, 13.5
6 MHz. The lines of magnetic force of the magnetic field A and the lines of electric force of the electric field B are orthogonal to each other in a certain region. In a region where the lines of magnetic force of the magnetic field A and the lines of electric force of the electric field B are orthogonal to each other, the electrons of the gas existing in the region cause cycloidal motion due to the interaction. The kinetic energy of the electrons generated by this cycloidal motion becomes the energy for converting the cleaning gas (NF ₃ ) into plasma. In this way, a high energy plasma region is formed. The generated high-energy plasma accelerates along the lines of magnetic force of the magnetic field A and collides with the inner wall of the vacuum vessel 11, the susceptor 13, and the like.
The inside of the vacuum vessel 11 is cleaned by the collision of the plasma and the chemical reaction.

When cleaning the surface of the wafer, after cleaning the inside of the vacuum vessel 11 by the above procedure,
First, the gas used for cleaning is discharged through the gas discharge pipe 20. Next, the substrate 12 is placed on the susceptor 13 in the vacuum vessel 11. Thereafter, the cleaning gas is again introduced into the vacuum vessel 11 from the gas introduction pipe. After introducing the gas, cleaning is performed in the same procedure as described above.

After the cleaning, the gas used for cleaning is discharged from the gas discharge pipe 20.

Next, a source gas corresponding to the thin film to be formed is introduced into the vacuum vessel 11 from the gas introduction pipe. Thereafter, a film forming process which is usually performed is performed. For example, using a heater 19 housed inside the high-frequency electrode 17, the susceptor 13
The substrate 12 placed thereon is heated to perform thermal CVD. Further, the film can be formed by plasma CVD.

According to such a method, the inside of the vacuum vessel 11 is completely cleaned in a short time, so that a good thin film can be efficiently formed on the substrate surface. The reason why the inside of the vacuum vessel 11 is completely cleaned in a short time is that the energy of the plasma formed by the above method is high. This high-energy plasma is formed by the interaction between the magnetic field A and the electric field B formed in the vacuum vessel 11. For this reason, the distance between the high-frequency electrode 17 and the vacuum vessel 11, which is a ground electrode, which is an important element in the conventional cleaning using plasma, does not cause a significant problem in the method of the present invention.

In the thin film forming method of the present invention, other devices can also be used. FIG. 2 shows a cross-sectional view of one such device. The apparatus shown in FIG. 1 has a cylindrical high-frequency electrode 17 at the bottom of the vacuum vessel 11, whereas the apparatus shown in FIG. 21 are provided. The high-frequency power supply 16 is connected to the high-frequency electrode 21. By arranging the plate-like electrodes in this manner, a stronger electric field can be formed. Therefore, the apparatus shown in FIG. 2 can generate higher-energy plasma. In addition, by disposing the movable ground electrode 41 above the susceptor 13 as shown in FIG. 2, the electric field formed by the high-frequency electrode 21 can be further increased. The movable ground electrode 41 becomes unnecessary when forming a film by CVD or the like. Therefore, it is necessary to remove the film from above the susceptor 13 during film formation.

FIG. 3 is a diagram showing a cross section of still another apparatus that can be used in the thin film forming method of the present invention. While the device shown in FIG. 1 includes a high-frequency electrode 17 for forming an electric field and an annular magnetic coil 15 for forming a magnetic field, this device has an electron cyclotron resonance (EC).
R) A plasma generation mechanism is provided. The details will be described below. In FIG. 3, the gas introduction chamber
One end of a microwave waveguide 31 is connected to the upper surface of 11a. The other end of the microwave waveguide 31 is connected to a microwave generating mechanism 32. The microwaves output from the microwave generation mechanism 32 travel through the microwave waveguide 31 and are guided into the vacuum vessel 11.

Next, an embodiment of the method of the present invention using the apparatus shown in FIG. 3 will be described.

First, the inside of the vacuum vessel 11 is reduced to a predetermined pressure, for example, 10 ⁻⁶ Torr by an exhaust device not shown. Thereafter, a cleaning gas, for example, NF ₃ is added to the gas introduction pipe 14.
From the gas introduction chamber 11a.

Next, a microwave of, for example, 2.45 GHz is output from the microwave generation mechanism 32. The output microwave is a waveguide
It is introduced into the vacuum vessel 11 through 31.

Next, a current is caused to flow through the annular magnetic coil 15 while introducing microwaves into the vacuum vessel 11 to form a magnetic field in the vacuum vessel 11. At this time, when the frequency of the microwave and the strength of the magnetic field satisfy certain conditions, the electrons of the gas present in the vacuum vessel 11 cause cyclotron resonance. For example, when the frequency of the microwave is 2.45 GHz and the strength of the magnetic field is 875 Gauss, this condition is satisfied, and the electrons of the gas cause cyclotron resonance. Electrons that have undergone cyclotron resonance obtain high kinetic energy and generate high-energy plasma. The inside of the vacuum chamber 11 is cleaned using the high-energy plasma.

When cleaning the surface of the substrate, after cleaning the inside of the vacuum vessel 11 by the above procedure, first, the gas used for cleaning is discharged through the gas discharge pipe 20. Next, the wafer 12 is placed on the susceptor 13 in the vacuum vessel 11. Thereafter, the cleaning gas is again introduced into the vacuum vessel 11 from the gas introduction pipe. After introducing the gas, cleaning is performed in the same procedure as described above.

After the cleaning, the gas used for cleaning is discharged from the gas discharge pipe 20.

Next, a source gas corresponding to the thin film to be formed is introduced into the vacuum vessel 11 from the gas introduction pipe. Thereafter, a film forming process which is usually performed is performed.

The provision of the ECR plasma generating means eliminates the need for the high-frequency electrode 17 in the apparatus shown in FIG. Therefore, the degree of freedom in design near the susceptor 13 increases. For example, as shown in FIG. 3, a vacuum chamber 34 closed with quartz glass 33 or the like may be provided on the back surface of the susceptor 13, and a light heat source 35 such as a halogen lamp or an infrared lamp may be provided outside the vacuum vessel 11. . In this case, light source 35
Heats the susceptor 13 through the quartz glass 33.

In the thin film forming method of the present invention, a chemically stable inert gas or etching gas can be used as the cleaning gas. Usually, Ar (argon gas) is used as the inert gas. As an etching gas, SF ₆ , NF ₃ ,
CF _{4 and the} like can be used, and NF ₃ is particularly preferred.

In the cleaning step of the thin film forming method of the present invention, a high-energy plasma is generated by the interaction between the electric field and the magnetic field generated in the reaction vessel.

The formation of the electric field in the processing container can be performed, for example, by providing two electrodes in the processing container. These electrodes may be two plate-shaped electrodes, or the processing container itself may be used as the electrodes. The electric power supplied to the electrodes when forming an electric field is 50-1K
It is preferably w. Further, instead of forming an electric field using electrodes, microwaves can be used.
In this case, a microwave is generated outside the processing container and introduced into the processing container.

In the processing container, the magnetic field is formed such that at least a part of the magnetic field lines (magnetic field lines) is orthogonal to the electric field lines (electric lines of force). This magnetic field can be formed by, for example, a permanent magnet, an electromagnet, or the like. The strength of the magnetic field formed is usually between 30 and 300 Gauss. When a microwave having a frequency of 2.45 GHz is used as the electric field, the strength of the magnetic field is most preferably 875 gauss.

In a system in which a magnetic field is formed together with an electric field in this manner, cycloidal motion of electrons of gas molecules existing in the region where the lines of magnetic force and the lines of electric force are orthogonal to each other occurs. This electron kinetic energy is converted into energy for converting gas into plasma. Thereby, high-energy plasma is generated.

In this cleaning step, the inside of the processing container such as the inner wall of the processing container and the susceptor can be cleaned. In particular, it is important to completely clean the susceptor supporting the object to form a better thin film.

In this cleaning step, it is desirable to heat the object to be cleaned in advance to a high temperature state. The higher the temperature, the better, but 500
C. or higher, preferably 800 ° C. or higher if possible.

After the cleaning is completed, the gas used for cleaning is discharged from the processing container, and then, a raw material gas for forming a thin film is introduced into the processing container. Various gases can be used as the source gas depending on the type of the thin film to be formed. For example, when forming a Si film on a workpiece,
SiH ₄ , Si (OCH) ₄ or the like can be used.

The thin film can be formed on the surface of the object to be processed by a method similar to a usual film forming method.

In the thin film forming method of the present invention, not only the inside of the processing container such as the inner wall of the processing container and the susceptor, but also the surface of the object to be processed can be cleaned. In this case, in the above-mentioned cleaning step, after cleaning the inside of the processing container, the object to be processed, for example, a semiconductor wafer, is carried into the processing container, and soft etching of the surface of the object to be processed is performed similarly to the cleaning of the inside of the processing container. Do.

In the above embodiment, the processing after cleaning is described as CVD, but the present invention is not limited to this. For example, similar effects can be obtained by processing such as etching, ashing, and sputtering.

As described above, according to this embodiment, the step of introducing the cleaning gas into the processing container, and the cleaning gas is turned into plasma in an electric and magnetic field atmosphere in the processing container to clean the processing container. By performing this step, the inside of the processing container and the surface of the object to be processed can be completely and quickly cleaned.

In addition, every time the object to be processed is carried into the processing container, by performing cleaning in the processing container in advance, after completely removing impurities that hinder processing from the processing container,
The processing of the object can be performed, and the yield can be improved.

[Brief description of the drawings]

FIG. 1 is a block diagram of a CVD apparatus for explaining one embodiment of the method of the present invention, FIGS. 2 and 3 are explanatory views of another embodiment of the method of the present invention, and FIG. 4 is a conventional cold wall type. It is a block diagram of a CVD apparatus. 11 Vacuum container, 12 Wafer 13 Susceptor, 14 Gas inlet tube 15 Magnetic coil, 16 High frequency power supply 17 High frequency electrode, 19 Coil 21 High frequency electrode, 31 … Microwave waveguide 32 …… Microwave generation mechanism

Continuation of the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) H01L 21/31 H01L 21/205 H01L 21/302 C23C 16/44 C23F 4/00

Claims (4)

(57) [Claims] 1. A step of introducing a cleaning gas of SF ₆ , NF ₃ , or CF ₄ into a processing container, and processing the cleaning gas into plasma in an electric field and a magnetic field atmosphere in the processing container. Cleaning the inside of the container. A step of reducing the pressure in the processing container to a predetermined pressure; a step of introducing a cleaning gas into the processing container; a step of forming a magnetic field in the processing container; And applying a high-frequency voltage between the electrode and the processing container arranged so as to face the electrode to form an electric field in the processing container to generate plasma. Cleaning method for processing equipment. 3. The cleaning method for a processing apparatus according to claim 1, wherein the cleaning of the processing equipment is performed in advance each time the object to be processed is loaded into the processing container. 4. A processing device for receiving and processing an object to be processed, a magnetic field forming means provided outside the processing device and for forming a magnetic field inside the processing device, Microwave introduction means for introducing microwaves into the processing device, and a processing gas or any one of SF ₆ , NF ₃ , and CF ₄ connected near the microwave introduction portion of the processing device and inside the processing device A gas introduction pipe for introducing a cleaning gas, and a discharge pipe for discharging gas inside the processing vessel. The cleaning gas is introduced from the gas introduction pipe, and the microwave introduction means and the magnetic field forming means are provided. A plasma is generated inside the processing tool to clean the inside of the processing tool.