JP5179658B2 - Plasma processing apparatus and cleaning method thereof - Google Patents

Description

  The present invention relates to a plasma processing apparatus and a cleaning method thereof.

  When the film forming process is repeatedly performed in the plasma processing apparatus, reaction products may adhere to the inside of the chamber and accumulate. Such deposits are desired to be removed by a cleaning operation. In general, this cleaning operation is performed by introducing a cleaning gas into the chamber. An example of a conventional technique for improving the cleaning efficiency is described in Japanese Patent Laid-Open No. 2002-334870 (Patent Document 1). Has been.

  Patent Document 1 discloses a configuration of a high-density plasma CVD apparatus in which an opening for introducing a remote plasma cleaning gas is provided on a side surface of a chamber and a rectifying plate is attached to the lower side of the opening. At the time of cleaning, the remote plasma cleaning gas introduced from the opening is directed to the ceiling by the rectifying plate, and the reaction is promoted with the reaction product attached to the center of the ceiling. Patent Document 1 describes that the reaction product can be removed in this manner.

JP 2002-334870 A

  According to the configuration disclosed in Patent Document 1, a remote plasma cleaning gas, that is, a so-called “radical” supplied into the chamber flows into the center of the ceiling by the action of the rectifying plate. Since radicals flow so as to concentrate in the center of the ceiling, it takes time for the radicals to reach the entire chamber. Accordingly, the time required until the entire cleaning in the chamber is completed becomes long.

  Therefore, an object of the present invention is to provide a plasma processing apparatus and a cleaning method thereof that can efficiently supply radicals to the entire inner surface of a chamber.

  In order to achieve the above object, a plasma processing apparatus according to the present invention is provided outside a chamber for performing plasma processing inside and generating a radical for cleaning the inside of the chamber. A remote plasma apparatus and a radical inlet for releasing the radicals generated by the remote plasma apparatus into the chamber, and the radical inlet has a direction in which the radical proceeds in the chamber. A plurality of gas outlets for blowing the rectified gas so as to affect the flow are provided.

  According to the present invention, the direction in which radicals advance can be controlled by the flow of rectified gas from a plurality of gas outlets provided at the radical inlet, so that radicals diffuse as widely as possible in the space in the chamber. Can be adjusted to. As a result, radicals can be efficiently supplied to the entire inner surface of the chamber.

It is a conceptual diagram of the plasma processing apparatus in Embodiment 1 based on this invention. It is a partial expanded explanatory view of the plasma processing apparatus in Embodiment 1 based on this invention. It is the figure which looked at the vicinity of the radical inlet of the plasma processing apparatus in Embodiment 1 based on this invention from the inner side of the chamber. It is 1st explanatory drawing of the preferable example of the plasma processing apparatus in Embodiment 1 based on this invention. It is 2nd explanatory drawing of the preferable example of the plasma processing apparatus in Embodiment 1 based on this invention. It is a conceptual diagram of the plasma processing apparatus in Embodiment 2 based on this invention. It is the elements on larger scale of the plasma processing apparatus in Embodiment 2 based on this invention. It is the figure which looked at the vicinity of the radical inlet of the plasma processing apparatus in Embodiment 2 based on this invention from the inner side of the chamber. It is a conceptual diagram of the plasma processing apparatus in a reference example. It is the elements on larger scale of the plasma processing apparatus in a reference example. It is the figure which looked at the vicinity of the radical inlet of the plasma processing apparatus in a reference example from the inside of a chamber.

(Embodiment 1)
With reference to FIGS. 1-3, the plasma processing apparatus in Embodiment 1 based on this invention is demonstrated. The plasma processing apparatus 101 includes a chamber 1 for performing plasma processing therein, a remote plasma apparatus 2 provided outside the chamber 1 for generating radicals for cleaning the interior of the chamber 1, a remote plasma apparatus 2 And a radical inlet 3 for releasing the radicals generated in the plasma apparatus 2 into the chamber 1. The radical inlet 3 is provided with a plurality of gas outlets 4 for blowing out the rectified gas so as to affect the direction in which the radicals travel in the chamber 1.

  Furthermore, the plasma processing apparatus 101 includes an antenna 5 and a process gas inlet 6 on the ceiling of the chamber 1. A stage 7 for installing a processing object is disposed in the lower part of the chamber 1. The lower surface of the chamber 1 is provided with an exhaust port 8 for discharging various gases and reaction products used. A tube extending from the exhaust port 8 is connected to a vacuum pump 9. The remote plasma apparatus 2 and the chamber 1 are connected by a gas pipe, and a gate valve 10 is disposed in the middle thereof.

  The remote plasma apparatus 2 is for receiving a cleaning gas and generating radicals as indicated by an arrow 81. For example, fluorine radicals can be generated. The plurality of gas outlets 4 are openings for injecting the received rectified gas as indicated by an arrow 82.

  FIG. 2 shows an enlarged view of the vicinity of the radical inlet 3 in FIG. FIG. 3 shows the vicinity of the radical inlet 3 as viewed from the left side in FIG. The radical inlet 3 includes a tapered portion 3e whose cross-sectional area increases as it approaches the outlet. Radicals to be used for cleaning are supplied from the remote plasma apparatus 2 shown in FIG. 1 through the gate valve 10 in the direction of the arrow 83 shown in FIG. A rectifying gas such as Ar is supplied in the direction of arrow 82. The rectified gas is injected from the gas outlet 4 as indicated by an arrow 84 through the inside of the gas guiding portion 11.

  In the plasma processing apparatus according to the present embodiment, the radical inlet 3 is provided with a plurality of gas outlets 4 for blowing the rectified gas, and these gas outlets 4 allow radicals to proceed in the chamber 1. Since the rectifying gas can be blown out so as to affect the direction, the direction in which radicals advance can be controlled by the degree of rectifying gas blowing. This is because the flow of radicals can change the direction in which the flow of the rectifying gas collides with the flow of radicals. In the present embodiment, in this way, adjustment can be made so that radicals diffuse as widely as possible in the space in the chamber. As a result, radicals can be efficiently supplied to the entire inner surface of the chamber.

  In FIG. 1 and FIG. 2, “Ar” is indicated for the gas supplied along the arrow 82, but Ar is merely an example, and other gases may be used.

  As shown in FIG. 3, the plurality of gas outlets 4 are preferably arranged so as to surround the outer periphery of the radical inlet 3. Even if the plurality of gas outlets 4 are arranged so as not to surround the outer periphery in the vicinity of the radical inlet 3, there is a certain effect by blowing the rectified gas, but the gas outlet 4 surrounds the outer periphery of the radical inlet 3. The rectifying gas can be injected in any direction, so that the direction in which radicals flow can be controlled more flexibly.

  As shown in FIG. 2, the plurality of gas outlets 4 are preferably arranged inwardly and obliquely forward from the peripheral edge of the radical inlet 3. This is because the flow of the rectifying gas can collide with the flow of radicals traveling in the center of the radical introduction port 3 so that the direction in which the radicals travel is easily changed. In the example shown in FIG. 2, the configuration in which the gas outlet 4 is arranged on the chamfered surface is shown, but such chamfering is not essential. Even if there is no chamfering, it is preferable that the gas outlet 4 is provided so that the rectified gas can be ejected obliquely forward. Even if the plurality of gas outlets 4 are provided in the peripheral portion of the radical introduction port 3 in an inward direction other than the diagonally forward direction, that is, for example, in a direction toward the front or the center of the radical introduction port 3, As long as it can affect the direction in which the air travels in the chamber 1, a temporary effect can be achieved.

  The plurality of gas outlets 4 are preferably divided into a plurality of groups and have a structure capable of blowing the rectified gas at different timings for each group. For example, as shown in FIG. 4, the plurality of gas outlets 4 may be divided into an upper half group 40a and a lower half group 40b. When the gas outlets 4 belonging to the group 40a inject the rectified gas all at once, the rectified gas is not injected from the gas outlets 4 belonging to the group 40b, and the gas outlet 4 belonging to the group 40b injects the rectified gas all at once. When doing so, the rectified gas is not injected from the gas outlets 4 belonging to the group 40a. The injection ON / OFF switching in each group may be performed by a known technique. In this case, when the rectified gas is injected from the gas outlet 4 belonging to the group 40a, the injection from the gas outlet 4 belonging to the group 40b is not hindered, so the radicals are smoothly guided downward. can do. On the contrary, when the rectified gas is injected from the gas outlet 4 belonging to the group 40b, the injection from the gas outlet 4 belonging to the group 40a is not hindered, so that the radicals can be smoothly guided upward. The method of dividing the plurality of gas outlets 4 into a plurality of groups is not limited to this. In FIG. 4, an example of dividing into two groups is shown, but it may be divided into more groups. For example, as shown in FIG. 5, it may be divided into four groups 40c, 40d, 40e, and 40f such as upper left, upper right, lower right, and lower left. The dividing method is not necessarily divided equally for the same number of gas outlets 4. Any division method may be used depending on the situation.

A specific cleaning procedure corresponding to the present embodiment will be described. In this example, the inner diameter of the radical inlet 3 is 50 mm, and the dimensions of the chamber 1 are 1000 mm × 1100 mm × 600 mm. The exhaust port 8 had a diameter of 100 mm or more, and the vacuum pump 9 was composed of a turbo molecular pump with an exhaust speed of 3000 liters / second and a dry pump with an exhaust speed of 1000 m ³ / hour.

First, the space in the chamber 1 and the remote plasma apparatus 2 are evacuated to the order of 10 ⁻⁴ Pa by a turbo molecular pump. Next, Ar gas is supplied into the chamber 1 through the gas outlet 4. Next, NF ₃ gas is supplied to the remote plasma apparatus 2. The NF ₃ gas becomes a fluorine radical by passing through the remote plasma apparatus 2. Fluorine radicals generated by the remote plasma device 2 flow into the chamber 1 from the radical inlet 3. The flow rate of Ar gas as the rectifying gas was ₃ sccm, the flow rate of NF ₃ gas as the fluorine radical material was ₃ slm, and the high frequency power of the remote plasma apparatus 2 was 3 kW. The valve installed between the turbo molecular pump and the chamber 1 was closed, the pressure in the chamber 1 was set to 133.322 Pa (1 Torr) using a dry pump, and cleaning was performed for a predetermined time. The length of time for cleaning can be determined from the film thickness of the Si film, SiN _x film, etc., which are the deposits to be removed in the chamber, and the etching rate of the deposits due to radicals.

  By this cleaning, fluorine radicals were smoothly supplied to the entire area in the chamber 1 and the deposits could be removed efficiently.

(Embodiment 2)
With reference to FIGS. 6-8, the plasma processing apparatus in Embodiment 2 based on this invention is demonstrated. As shown in FIG. 6, the plasma processing apparatus 102 in this embodiment has the same basic configuration as the plasma processing apparatus 101 described in the first embodiment. Hereinafter, a description will be given focusing on parts different from the plasma processing apparatus 101 of the first embodiment.

  In the plasma processing apparatus 102, a diffusion member 13 for dispersing a radical flow is disposed at the center of the radical introduction port 3, and the plurality of gas outlets 14 surround the outer periphery of the diffusion member 13. Are arranged outward and obliquely forward. FIG. 7 shows an enlarged view of the vicinity of the radical inlet 3 in FIG. FIG. 8 shows the vicinity of the radical inlet 3 as viewed from the left side in FIG. The radical inlet 3 includes a tapered portion whose cross-sectional area increases as it approaches the outlet, similar to that described in the first embodiment.

  The diffusion member 13 is disposed in the center of the radical inlet 3 so as to be supported by the gas guiding portion 12 extending in a beam shape. Therefore, the outer periphery of the diffusing member 13 has a sufficient gap so that the gas can pass freely except for the portion where the gas guiding portion 12 exists. The gas guiding part 12 has a hollow structure, and the rectifying gas can pass through the inside.

  In the plasma processing apparatus according to the present embodiment, since the diffusion member 13 is disposed at the radical inlet 3, the radical flow is diffused to some extent. Further, a plurality of gas outlets 14 for blowing the rectified gas are provided so as to surround the outer periphery of the diffusion member 13, and these gas outlets 14 affect the direction in which radicals travel in the chamber 1. Since the rectifying gas can be blown out, it is possible to further control the direction in which the radicals proceed depending on how the rectifying gas is blown out. Therefore, it can be adjusted so that radicals diffuse as widely as possible in the space in the chamber. As a result, radicals can be efficiently supplied to the entire inner surface of the chamber.

  The diffusing member 13 may be appropriately supported by a member other than the gas guiding portion 12 extending in a beam shape. In addition to the gas guiding portion 12, a beam-shaped member that does not have a passage for guiding gas inside may be appropriately provided as an auxiliary to support the diffusion member 13. When the gas guiding portion 12 does not have sufficient strength, the gas guiding portion 12 may be configured only for supplying the rectifying gas by supporting the diffusing member 13 with another beam-shaped member.

  6 and 7, the diffusing member 13 has a first end 13a that is pointed and a second end 13b that is opposite to the first end 13a and is not pointed. The working member 13 is preferably arranged so that the first end 13 a faces the outside of the chamber 1 and the second end 13 b faces the inside of the chamber 1. With this configuration, the radical flow supplied to the chamber 1 is dispersed by the sharp first end 13a and is guided in different directions. Furthermore, since the second end 13b is not sharp, the radical flow that has passed around the diffusion member 13 continues to proceed in different directions rather than rejoining. Therefore, it is preferable to have such a configuration.

  The diffusion member 13 preferably has a conical shape. This is because the radical flow that is supplied to the chamber 1 and passes through the periphery of the diffusion member 13 is induced to diffuse smoothly if this configuration is provided.

  In each of the above embodiments, the term “rectifying gas” has been used. However, the rectifying gas may be any gas that does not adversely affect the cleaning action by radicals and does not adversely affect the inner surface of the chamber. . Therefore, the rectifying gas is preferably an inert gas. The rectifying gas may be obtained inexpensively. The rectifying gas is preferably Ar. As a rectifying gas, it is a realistic choice to use, for example, nitrogen instead of Ar.

  The idea described in Embodiment 1 may also be adopted in plasma processing apparatus 102 in the present embodiment. That is, for example, the plurality of gas outlets 14 may be divided into a plurality of groups, and the rectified gas may be blown out at different timings for each group.

  A specific cleaning procedure corresponding to the present embodiment will be described. In this example, conditions such as the inner diameter of the radical introduction port 3, the dimensions of the chamber 1, the diameter of the exhaust port 8, and the exhaust amount by the vacuum pump 9 are the same as those described as the specific cleaning procedure of the first embodiment. is there. The diffusion member 13 was a conical member having a bottom diameter of 20 mm and a height of 20 mm. Cleaning was performed using this plasma processing apparatus. The operation procedure is the same as that described as the specific cleaning procedure of the first embodiment.

  By this cleaning, fluorine radicals were smoothly supplied to the entire area in the chamber 1 and the deposits could be removed efficiently.

  The plasma processing apparatus cleaning method according to the present invention includes a step of preparing the plasma processing apparatus shown in each of the above embodiments, and supplying radicals from the radical inlet into the chamber using the plasma processing apparatus. And a step of adjusting the direction in which the radicals advance in the chamber by ejecting the rectified gas from the plurality of gas outlets. According to this method, since the radicals can be adjusted so as to diffuse as widely as possible in the space in the chamber, the radicals can be efficiently supplied to the entire inner surface of the chamber, and the cleaning can be performed efficiently. .

  The apparatus disclosed in Patent Document 1 has a top nozzle for introducing a process gas limited to one place on the ceiling of the process chamber and a spiral upper electrode for generating a magnetic field. As a result, the reaction product adheres more to the ceiling. It can be said that Patent Document 1 intends to intensively remove reaction generation on the ceiling on the assumption of such a configuration.

  On the other hand, in the plasma processing apparatus in each of the above embodiments, an antenna is provided so as to protrude downward on the ceiling of the chamber, and an exhaust port is provided on the bottom surface of the chamber. In such a configuration, the plasma generated by the antenna provided on the ceiling of the chamber decomposes the process gas. The decomposed process gas rides on the flow caused by the vacuum pump and goes to the exhaust outlet below. In this way, the decomposed process gas is supplied while diffusing onto the substrate installed on the stage on the way from the vicinity of the ceiling downward. As a result, film formation is performed on the surface of the substrate. Therefore, the reaction product adheres not only to the ceiling but to the entire area of the inner surface of the chamber. In the case of such a plasma processing apparatus, the invention disclosed in Patent Document 1 is not sufficient to perform cleaning truly efficiently, and the present invention is particularly useful. This is because according to the present invention, the flow of radicals can be guided in various directions, so that it can be directed to a desired portion in the chamber, and as a result, the product adhering to the entire area of the inner surface of the chamber can be efficiently removed. Because it can.

  According to the present invention, it is possible to cope with cleaning in a plasma processing apparatus configured to supply process gas from a plurality of locations on the ceiling of the chamber. According to the present invention, the radicals can be smoothly distributed over the entire inner surface of the chamber for cleaning regardless of where the process gas supply port into the chamber is located and where the antenna is located.

  In the high-density plasma CVD apparatus disclosed in Patent Document 1, a spiral upper electrode is provided outside the chamber ceiling, and a high-frequency coil is provided so as to surround the side wall of the chamber. Therefore, it is difficult to provide a remote plasma cleaning gas inlet at these positions. On the other hand, in each of the above embodiments, since the antenna is arranged inside the ceiling of the chamber, a cleaning gas or radical inlet can be freely provided on the side wall of the chamber. Therefore, the plasma processing apparatus in this embodiment is superior in design flexibility.

  In each of the above embodiments, an example in which the radical inlet is provided on the side wall of the chamber has been shown. However, as the present invention, the position where the radical inlet is provided is not limited to the side wall, and may be another location. It may be the ceiling or the bottom. This is because when the present invention is applied, the direction in which the radical proceeds can be adjusted regardless of the location of the radical inlet, and the entire region in the chamber can be efficiently distributed.

(Reference example)
The plasma processing apparatus in the reference example will be described with reference to FIGS.

  As shown in FIG. 9, the plasma processing apparatus 113 in the reference example has a part of the configuration in common with the plasma processing apparatus 101 described in the first embodiment. Hereinafter, a description will be given focusing on parts different from the plasma processing apparatus 101 of the first embodiment. FIG. 10 shows an enlarged view of the vicinity of the radical inlet 3 in FIG. FIG. 11 shows the vicinity of the radical inlet 3 as seen from the left side in FIG.

  Similar to the plasma processing apparatus 102 described in the second embodiment, the plasma processing apparatus 113 includes a diffusion member 13r. However, the plasma processing apparatus 113 has no configuration for supplying the rectifying gas. The diffusion member 13r is a simple member that does not eject any new gas. As shown in FIGS. 10 and 11, the diffusing member 13r has a conical shape. As shown in FIG. 11, the diffusing member 13r is arranged at the center of the radical inlet 3 by four beams 15 arranged around at intervals of 90 °. Although the number of beams 15 is four here, other numbers may be used as long as one or more. Further, the interval at which the beams 15 are arranged is not limited to 90 °, and may be another angle or may not be equal.

  Also by adopting this configuration, since the radical flow supplied into the chamber 1 is diffused by the diffusion member 13r, there is some effect in efficiently supplying radicals to the entire inner surface of the chamber. However, according to this reference example, since there is no action by the rectifying gas, the effect is inferior to that of the present invention.

  In addition, the said embodiment disclosed this time is an illustration in all the points, Comprising: It is not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  The present invention can be used in a plasma processing apparatus and a cleaning method thereof.

  1 chamber, 2 remote plasma apparatus, 3 radical inlet, 3e taper part, 4,14 gas outlet, 5 antenna, 6 process gas inlet, 7 stage, 8 exhaust port, 9 vacuum pump, 10 gate valve, 11, 12 gas guiding part, 13, 13r diffusion member, 13a first end, 13b second end, 15 beams, 40a, 40b, 40c, 40d, 40e, 40f group, 81, 82, 83, 84 arrow, 101, 102 113 Plasma processing equipment.

Claims (10)

A chamber (1) for performing plasma processing therein;
A remote plasma device (2) provided outside the chamber to generate radicals for cleaning the interior of the chamber;
A radical inlet (3) for releasing the radicals generated in the remote plasma device into the chamber;
The plasma processing apparatus (101), wherein the radical introduction port is provided with a plurality of gas blowing ports (4, 14) for blowing a rectified gas so as to affect the direction in which the radicals travel in the chamber.   The plasma processing apparatus according to claim 1, wherein the plurality of gas outlets are disposed so as to surround an outer periphery of the radical inlet.   2. The plasma processing apparatus according to claim 1, wherein the plurality of gas outlets are disposed inward and obliquely forward from a peripheral edge of the radical inlet.   The plasma processing apparatus according to claim 1, wherein the plurality of gas outlets are divided into a plurality of groups, and the rectified gas can be blown out at different timings for each of the groups.   A diffusion member (13, 13r) for dispersing the radical flow is disposed at the center of the radical inlet, and the plurality of gas outlets are arranged so as to surround the outer periphery of the diffusion member. The plasma processing apparatus according to claim 1, wherein the plasma processing apparatus is disposed in a direction and obliquely forward.   The diffusion member has a first end (13a) that is pointed and a second end (13b) that is opposite to the first end and is not pointed, and the diffusion member includes the first end (13b). The plasma processing apparatus according to claim 5, wherein the plasma processing apparatus is disposed such that an end faces the outside of the chamber and the second end faces the inside of the chamber.   The plasma processing apparatus according to claim 6, wherein the diffusion member has a conical shape.   The plasma processing apparatus according to claim 1, wherein the rectifying gas is an inert gas.   The plasma processing apparatus according to claim 8, wherein the rectifying gas is Ar. Preparing a plasma processing apparatus according to claim 1;
Supplying radicals from the radical inlet into the chamber using the plasma processing apparatus;
And a step of adjusting the direction in which the radicals proceed in the chamber by ejecting the rectified gas from the plurality of gas outlets.

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