Patent Application
20210249238
This application is based upon and claims the benefit of priority from Japanese Patent Application No. 2020-019685 filed on Feb. 7, 2020 in Japan, the entire contents of which are incorporated herein by reference.
Embodiments described herein relate generally to an exhaust pipe device.
In a film forming apparatus represented by a chemical vapor deposition (CVD) apparatus, raw material gas is introduced into a film forming chamber, and a desired film is formed on a substrate disposed in the film forming chamber. Then, the raw material gas remaining in the film forming chamber is exhausted by a vacuum pump via an exhaust pipe. At that time, products resulting from the raw material gas may be deposited in the exhaust pipe to close the exhaust pipe, or the products may be deposited in the vacuum pump on the downstream side of the exhaust pipe to stop the vacuum pump. To remove the deposited products, cleaning processing is performed by a remote plasma source (RPS) device. However, since the RPS device generally focuses on cleaning in the film forming chamber, cleaning performance is insufficient to clean the products deposited in the exhaust pipe near the vacuum pump distant from the
RPS device and the vacuum pump.
An exhaust pipe device according to an embodiment includes a pipe body, a coil, an inner pipe, and a plasma generation circuit. The coil is disposed inside the pipe body. The inner pipe is a dielectric and is disposed inside the coil. The plasma generation circuit is configured to generate plasma inside the inner pipe using the coil. The exhaust pipe device functions as a part of an exhaust pipe disposed between a film forming chamber and a vacuum pump for exhausting an inside of the film forming chamber.
In the following embodiments, an exhaust pipe device capable of removing products deposited in an exhaust pipe near a vacuum pump will be described.
In the cleaning step, cleaning gas such as nitrogen trifluoride (NF3) gas or purge gas such as argon (Ar) gas is supplied to remote plasma source (RPS) devices 300 disposed on the upstream side of the film forming chambers 202, and fluorine (F) radicals are generated by plasma. Then, by supplying (diffusing) the F radicals to the inside of the film forming chamber 202 and the side of the exhaust pipe 150, cleaning of the deposited products is performed. For example, silicon tetrafluoride (SiF4) generated after decomposition of the deposited products by cleaning is highly volatile, so that it is exhausted by the vacuum pump 400 through the exhaust pipes 150 and 152.
However, it may be difficult for the F radicals to reach portions of the exhaust pipes 150 and 152 distant from the film forming chamber 202, and cleaning performance may be degraded. In particular, since a pressure is lowered at a position close to a suction port of the vacuum pump 400, a cleaning rate may be lowered. As a result, the exhaust pipes 150 and 152 may be closed by the deposited products. In addition, a gap between a rotor and a casing may be filled with the products deposited in the vacuum pump 400 to thereby enter an overload state, and the vacuum pump 400 may be stopped. Therefore, in the first embodiment, as shown in
In
Flanges are disposed at both ends of the pipe body 102, one end of the pipe body 102 is connected to the exhaust pipe 150 on which a flange having the same size is disposed, and the other end thereof is connected to the exhaust pipe 152 on which a flange having the same size is disposed. In
The plasma generation circuit 106 uses the coil 104 to generate inductively coupled plasma inside the inner pipe 190 made of the dielectric, in the pipe body 102.
The inner pipe 190 is disposed so as to form a space between an inner wall of the pipe body 102 and the inner pipe 190. The material of the dielectric being the inner pipe 190 may be a material having a dielectric constant higher than that of air. As the material of the inner pipe 190, for example, quartz, alumina (Al2O3) , yttria (Y2O3), hafnia (HfO2) , zirconia (ZrO2) , magnesium oxide (MgO), or aluminum nitride (AlN) is preferably used. The thickness of the inner pipe 190 may be appropriately set as long as it does not hinder the exhaust performance.
As shown in
In the examples of
Specifically, an introduction terminal 111 (an example of a radio-frequency introduction terminal) is introduced into the pipe body 102 from an introduction terminal port 105 connected to an outer circumferential surface of the pipe body 102, and the introduction terminal 111 is connected to one of both ends of the coil 104. The introduction terminal 111 is used to apply a radio-frequency electric field to one of both ends of the coil 104. Further, an introduction terminal 116 is introduced into the pipe body 102 from an introduction terminal port 115 connected to the outer circumferential surface of the pipe body 102, and the introduction terminal 116 is connected to the other of both ends of the coil 104. The introduction terminal 116 is used to apply a ground potential to the other of both ends of the coil. In
Then, the plasma generation circuit 106 uses the coil 104 to generate plasma inside the inner pipe 190. The plasma generation circuit 106 applies a radio-frequency voltage between both ends of the coil 104. Specifically, the plasma generation circuit 106 applies a radio-frequency (RF) voltage to one of both ends of the coil 104 via the introduction terminal 111 with the pipe body 102 and the other of both ends of the coil 104 grounded, thereby generating inductively coupled plasma (ICP) in the dielectric inner pipe 190 disposed inside the coil 104.
Further, in a cleaning step, since the above-described cleaning gas such as NF3 gas is supplied on the upstream side, the rest thereof is used to generate F radicals by the plasma inside the inner pipe 190. Then, the products deposited inside the inner pipe 190 are removed by the F radicals. As a result, high cleaning performance can be exhibited in the exhaust pipe.
Thereafter, for example, SiF4 generated after decomposition of the deposited products by the F radicals is highly volatile, so that it is exhausted by the vacuum pump 400 through the exhaust pipe 152. Further, a part of the radicals generated by the exhaust pipe device 100 enters the vacuum pump 400 through the exhaust pipe 152 and cleans the products deposited in the vacuum pump 400. As a result, an amount of the products deposited in the vacuum pump 400 can be reduced. For example, F radicals generated by plasma generated in a part of an inner wall surface on the lower end side of the inner pipe 190 can be caused to enter the vacuum pump 400 with small consumption inside the pipe body 102.
On the other hand, in the first embodiment, as shown in
In the disk 10a, a ring-shaped convex portion is formed on the surface of the side (upstream side) of the pipe body 102 in the two surfaces of the upstream and downstream sides. Similarly, in the disk 10b, a ring-shaped convex portion is formed on the surface of the side (downstream side) of the pipe body 102 in the two surfaces of the upstream and downstream sides. Each ring-shaped convex portion is inserted and disposed in the space between the pipe body 102 and the inner pipe 190.
Therefore, an inner diameter of the convex portion is larger than an outer diameter of the inner pipe 190, and an outer diameter of the convex portion is smaller than an inner diameter of the pipe body 102.
On the lower side of the pipe body 102, the pipe body 102 is connected to the disk 10a via the O-ring 12a. The atmosphere inside the pipe body 102 is shielded from the atmosphere by the O-ring 12a. Further, the inner pipe 190 is supported on the disk 10a, and the O-ring 14a is disposed between the outer circumference of the inner pipe 190 and the ring-shaped convex portion of the disk 10a. As a result, the atmosphere inside the inner pipe 190 is shielded from the space between the pipe body 102 and the inner pipe 190 by the O-ring 14a. Similarly, on the upper side of the pipe body 102, the pipe body 102 is connected to the disk 10b via the O-ring 12b. The atmosphere inside the pipe body 102 is shielded from the atmosphere by the O-ring 12b. Further, an upper end face of the inner pipe 190 is covered with the disk 10b, and the O-ring 14b is disposed between the outer circumference of the inner pipe 190 and the ring-shaped convex portion of the disk 10b. As a result, the atmosphere inside the inner pipe 190 is shielded from the space between the pipe body 102 and the inner pipe 190 by the O-ring 14b.
The introduction terminal 111 is connected to one of both ends of the coil 104 in the space between the pipe body 102 and the inner pipe 109, which is shielded from the atmosphere and the space in the inner pipe 190, and applies a radio-frequency electric field to one of both ends when plasma is generated. Similarly, the introduction terminal 116 is connected to the other of both ends of the coil 104 in the space between the pipe body 102 and the inner pipe 190, which is shielded from the atmosphere and the space in the inner pipe 190, and applies (grounds) a ground potential to the other of both ends when plasma is generated.
Further, a bypass pipe 20 connected to the pipe 152 on the downstream side is connected to the outer circumferential side of the pipe body 102. In the bypass pipe 20, a valve 22 is disposed in the middle of a pipe 21. Then, in a state where the valve 22 is opened, the film forming chamber 202 is exhausted by the vacuum pump 400 before flowing the process gas into the film forming chamber 202, so that a pressure in the space between the pipe body 102 and the inner pipe 190 can be caused to become a pressure under vacuum. By closing the valve 22 in this state, the pressure in the space between the pipe body 102 and the inner pipe 190 can be maintained at a pressure under vacuum.
After that, a film forming process or the like is performed. As described above, since the space between the pipe body 102 and the inner pipe 190 is shielded from the atmosphere and the space inside the inner pipe 190 by the sealing mechanisms 16a and 16b, the cleaning gas or the like does not pass through the space between the pipe body 102 and the inner pipe 190. When plasma is generated in the exhaust pipe device 100, as described above, the cleaning gas or the like flows through the inner pipe 190, so that the pressure in the space between the pipe body 102 and the inner pipe 190 can be caused to be sufficiently lower than the pressure inside the inner pipe 190. As a result, it is possible to suppress plasma from being generated in the space between the pipe body 102 and the inner pipe 190. Note that the pressure in the space between the pipe body 102 and the inner pipe 190 is not limited to the above example. The pressure may be maintained at the atmospheric pressure. The plasma can be suppressed from being generated, even at the atmospheric pressure.
In the first embodiment, by forming a sealed double pipe structure of the pipe body 102 and the inner pipe 190 described above, even when the inner pipe 190 made of the dielectric is damaged, the gas flowing through the exhaust pipe can be prevented from leaking into the atmosphere. Similarly, it is possible to prevent the atmosphere from rushing (flowing) into the exhaust pipe. Note that, even when the space between the pipe body 102 and the inner pipe 190 is controlled to the atmospheric pressure, the volume of the space between the pipe body 102 and the inner pipe 190 is small, so that it is possible to prevent the inflow of the atmosphere enough to cause the damage of the vacuum pump 400.
As described above, according to the first embodiment, it is possible to remove the products deposited in the exhaust pipe near the vacuum pump 400 distant from the film forming chamber 202. Further, the products deposited in the vacuum pump 400 can be reduced. Further, an installation area of the device for removing the deposited products can be reduced.
In the first embodiment, a configuration in which a space between a pipe body 102 and an inner pipe 190 is shielded from the atmosphere and a space inside the inner pipe 190 by sealing mechanisms 16a and 16b has been described. However, the present disclosure is not limited thereto. In a second embodiment, a configuration in which sealing is not performed between the space inside the pipe body 102 and the space inside the inner pipe 190 will be described. Further, points that are not particularly described below are the same as those in the first embodiment.
The inner pipe 190 is disposed in the space inside the pipe body 102. In the example of
Then, the plasma generation circuit 106 uses the coil 104 to generate plasma inside the inner pipe 190. Specifically, the plasma generation circuit 106 applies a radio-frequency (RF) voltage to one of both ends of the coil 104 via an introduction terminal 111 with the pipe body 102 and the other of both ends of the coil 104 grounded (or the other of both ends of the coil 104 is grounded via a capacitor), thereby generating inductively coupled plasma (ICP) in the dielectric inner pipe 190 disposed inside the coil 104. Then, the rest of the cleaning gas is used to generate F radicals by the plasma, and products deposited in the inner pipe 190 are removed by the F radicals. As a result, high cleaning performance can be exhibited in the exhaust pipe.
Thereafter, for example, SiF4 generated after decomposition of the deposited products by the F radicals is highly volatile, so that it is exhausted by the vacuum pump 400 through the exhaust pipe 152. Further, by using a part of the radicals generated in an exhaust pipe device 100, the products deposited in the vacuum pump 400 are cleaned. As a result, an amount of the products deposited in the vacuum pump 400 can be reduced. For example, F radicals generated by plasma generated in a part of an inner wall surface on the lower end side of the inner pipe 190 can be caused to enter the vacuum pump 400 with small consumption inside the pipe body 102.
Here, a pressure outside the inner pipe 190 and a pressure inside the inner pipe 190 in the pipe body 102 are substantially the same, and products may also be deposited between the pipe body 102 and the inner pipe 190, similarly to an inner wall of the inner pipe 190. In the second embodiment, by disposing the inner pipe 190 made of the dielectric inside the coil 104 in which plasma is generated at a high density, even if the coil 104 is not covered with a dielectric or the like, it is possible to reduce degradation such as erosion of the coil 104 due to plasma. Further, since the products can be removed by the plasma inside the inner pipe 190, closing in the pipe can be avoided. The other contents are the same as those in the first embodiment.
Further, in the second embodiment, even when the inner pipe 190 being the dielectric is damaged, it is possible to prevent the gas flowing through the exhaust pipe from leaking into the atmosphere, by a double pipe structure of the pipe body 102 and the inner pipe 190. Similarly, it is possible to prevent the atmosphere from rushing (flowing) into the exhaust pipe.
As described above, according to the second embodiment, even when a space between double pipes is not sealed, similarly to the first embodiment, it is possible to remove the products deposited in the exhaust pipe near the vacuum pump 400 distant from the film forming chamber 202. Further, the products deposited in the vacuum pump 400 can be reduced. Further, an installation area of the device for removing the deposited products can be reduced.
In a third embodiment, a configuration in which an ignition electrode is disposed on the upstream side of a plasma generation region will be described. Further, points that are not particularly described below are the same as those in the first embodiment.
A plasma generation circuit 144 (radio-frequency circuit) generates plasma 2 on an exposed surface of the introduction electrode 142 in the pipe 140 by applying a radio-frequency (RF) voltage to the introduction electrode 142 with the pipe 140 grounded. The plasma generation circuit 144 applies a radio-frequency voltage having a Vpp(Peak-to-Peak Voltage) of 5 kV or more and a repetition frequency of 5 kHz or more to the introduction electrode 142. An applied voltage waveform is preferably a sine wave or a rectangular wave. This makes it to function as an ignition agent or a plasma maintenance stabilizer for plasma 1 generated in the inner pipe 190. The rest of structure is identical to those in
In the example of
A temperature of an inner pipe 190 being a dielectric increases due to plasma generation. In addition, the inner pipe 190 may be damaged due to the temperature increasing too high. Therefore, in a fourth embodiment, a configuration in which a cooling mechanism is further mounted on the configuration shown in
One of both ends of the coil 104 is inserted into an introduction terminal port 105 from the inside. Further, the other of both ends of the coil 104 is inserted into an introduction terminal port 115 from the inside. The introduction terminal 111 is inserted from the introduction terminal port 105 connected to an outer circumferential surface of the pipe body 102, and is connected to one of both ends of the coil 104 inside the introduction terminal port 105. The introduction terminal 116 is inserted from the introduction terminal port 115 connected to the outer circumferential surface of the pipe body 102, and is connected to the other of both ends of the coil 104 inside the introduction terminal port 115. In the fourth embodiment, cooling water (an example of a refrigerant) is supplied from the introduction terminal 116 of the lower side to the inside of the coil 104, flows through the coil 104, and is exhausted from the introduction terminal 111 of the upper side.
Further, a wire for applying a radio-frequency (RF) voltage from a plasma generation circuit 106 is electrically connected to a surface of the introduction terminal 111. A wire for applying a ground potential from the plasma generation circuit 106 is electrically connected to a surface of the introduction terminal 116. Then, in a state in which the cooling water flows through the introduction terminal 116, the coil 104, and the introduction terminal 111, the plasma generation circuit 106 uses the coil 104 to generate plasma inside the inner pipe 190. The plasma generation circuit 106 applies a radio-frequency voltage between both ends of the coil 104.
Specifically, the plasma generation circuit 106 applies a radio-frequency (RF) voltage to one of both ends of the coil 104 via the introduction terminal 111 with the pipe body 102 and the other of both ends of the coil 104 grounded, thereby generating inductively coupled plasma (ICP) in the dielectric inner pipe 190 disposed inside the coil 104. At this time, the cooling water flowing through the coil 104 is used to cool the inner pipe 190, which is a dielectric whose temperature increases due to plasma generation, and the space between the inner pipe 109 and the pipe body 102. The inner pipe 109 is cooled by the cooling water, so that the inner pipe 109 can be suppressed from being damaged. Note that, from the viewpoint of cooling efficiency, the coil 104 is preferably disposed to contact the outer circumferential surface of the inner pipe 190.
Further, the cooling mechanism according to the fourth embodiment has a gas introduction port 41, a valve 40 (or a check valve 42), a gas exhaust port 43, and a valve 44 (or a check valve 46), as shown in
The cooling gas is introduced into the space between the inner pipe 109 and the pipe body 102 at a pressure higher than an atmospheric pressure. Therefore, a pressure in the space between the inner pipe 109 and the pipe body 102 is controlled to a pressure higher than a pressure in the space inside the inner pipe 109 and the atmospheric pressure. The pressure in the space between the inner pipe 109 and the pipe body 102 is measured by a pressure sensor 48 via a vent 47 disposed on the outer circumferential surface of the pipe body 102, and a pressure variation in the space is monitored. Here, when the inner pipe 190, which is the dielectric whose temperature increases due to plasma generation, is damaged, the cooling gas flows into the vacuum side and vacuum breakage occurs. Therefore, breakage of the inner pipe 190 is detected by the pressure sensor 48.
Specifically, when a pressure drop is detected by the pressure sensor 48, the valves 40 and 44 are controlled to be shut off. As a result, the inflow of the cooling gas into an exhaust line can be minimized. When the check valve 42 is used instead of the valve 40, the check valve 42 is used in which a cracking pressure is set so that the check valve 42 is shut off at a pressure in which a differential pressure between a primary pressure and a secondary pressure is a pressure higher than 0.1 MPa and which is lower than a supply pressure of the cooling gas. If the supply of the cooling gas is stopped at a supply source, the primary pressure (primary side of the check valve) is an atmospheric pressure, the secondary pressure (inside the pipe body 102) is the atmospheric pressure or less (pressure is lower than the atmospheric pressure due to damage), and the differential pressure is 0.1 MPa or less. For this reason, the cooling gas does not flow in a case of 0.1 MPa<cracking pressure<supply pressure. Therefore, if the supply of the cooling gas is stopped at the supply source in response to the detection of the damage of the inner pipe 190, the atmosphere can be prevented from flowing into the pipe body 102 even when the primary side is opened to the atmosphere. Further, in a case of using the check valve 46 instead of the valve 44, if the inner pipe 190 is damaged, the primary pressure becomes lower than the secondary pressure, so that a flow passage can be blocked. Therefore, the atmosphere can be prevented from flowing into the inside of the pipe body 102.
The rest of structure is identical to that in
Note that, in the example of
The embodiments have been described above with reference to the specific examples. However, the present disclosure is not limited to these specific examples.
In addition, all exhaust pipe devices that include the elements of the present disclosure and can be appropriately changed in design by those skilled in the art are included in the scope of the present disclosure.
While certain embodiments have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the inventions. Indeed, the novel methods and devices described herein may be embodied in a variety of other forms; furthermore, various omissions, substitutions and changes in the form of the methods and devices described herein may be made without departing from the spirit of the inventions. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the inventions.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2020-019685 | Feb 2020 | JP | national |
