CN118685742A - Film forming apparatus - Google Patents

Abstract

The film forming apparatus includes: a turntable disposed in the cavity; a processing unit configured to perform plasma processing on the workpiece conveyed by the turntable; an inner wall configured to define a processing space in which plasma processing is performed, and having an opening facing the turntable in a noncontact manner; an outer wall configured to cover a periphery of the inner wall with a gap, and configured to form an exhaust space having an opening facing the turntable in a noncontact manner; and an exhaust port connected to an exhaust device configured to perform exhaust from the processing space to the outside of the chamber, wherein the processing unit is a film forming portion configured to form a film by sputtering, and both ends of the outer wall are in contact with the side surface of the chamber, and a portion of the outer periphery of the inner wall is partitioned from the side surface of the chamber so that the reaction gas does not circulate in the exhaust space.

Description

Film forming equipment

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based upon and claims the benefit of priority of Japanese Patent Application No. 2023-045751 filed on March 22, 2023, Japanese Patent Application No. 2024-006287 filed on January 18, 2024, and Japanese Patent Application No. 2024-044726 filed on March 21, 2024, the entire contents of which are incorporated herein by reference.

Technical Field

The present disclosure relates to a film-forming apparatus.

Background Art

In the manufacturing process of various products such as semiconductors, displays, and optical disks, thin films such as protective films, conductive films, functional films, and optical films may be formed on a workpiece such as a wafer or a glass substrate. The thin films may be produced by repeatedly performing film formation of forming a metal film or the like on the workpiece and performing film processing such as etching, oxidation, or nitridation on the formed film.

Film formation and film processing can be performed by using various methods, one of which is a method using plasma processing. For example, in film formation, a sputtering gas is introduced into a chamber which is a vacuum container and in which a target made of a material for forming a film is placed, and a voltage is applied to the target. Film formation is performed as follows: sputtering gas ions generated when the sputtering gas is ionized and plasmatized collide with the target so that the material ejected from the target is deposited on the workpiece. In film processing, a processing gas is introduced into a chamber where an electrode is placed, and a voltage is applied to the electrode. Film processing is performed by causing ions of the plasmatized processing gas to collide with the film on the workpiece.

In order to continuously perform film formation and film processing (hereinafter, referred to as "plasma processing", which includes film formation and film processing), there is a film forming apparatus in which a turntable is installed inside a chamber, and a plurality of film forming parts and film processing parts are arranged on the ceiling of the chamber (i.e., above the turntable) in the circumferential direction (see, for example, Patent Document 1). With this configuration, various films can be formed by holding and conveying a workpiece on the turntable and passing the workpiece directly under the film forming part and the film processing part.

Prior art documents

Patent Documents

Patent Document 1: Japanese Patent Application Publication No. 2018-3152

Summary of the invention

The above-mentioned film forming apparatus has a processing chamber inside a chamber, and the processing chamber is a space for performing plasma processing. For example, a portion of the processing chamber is constructed by surrounding the processing area in a cylindrical shape by a shielding member (inner wall) extending from the ceiling of the chamber toward the turntable. The shielding member is provided to prevent the film forming material from scattering from the target and adhering to the inner wall of the chamber, and to prevent the introduced sputtering gas and processing gas (hereinafter, referred to as "reactive gas", including both sputtering gas and processing gas) from flowing out of the processing chamber.

The shielding member has an opening on the side opposite to the ceiling of the chamber, and the edge of the shielding member is arranged close to the workpiece held on the turntable, and there is a gap between the edge of the shielding member and the workpiece to allow the workpiece to pass. For example, a gap of approximately several millimeters is formed between the edge of the shielding member and the workpiece.

However, leakage of the reaction gas cannot be completely prevented due to the gap and the flow of the reaction gas between the inside and the outside of the shield member caused by the rotation of the turntable and the movement of the workpiece being conveyed.

In addition, in some cases, multiple processing chambers may be provided in order to increase the film deposition rate as the amount of film deposited per unit time, or to perform plasma treatment with multiple types of materials. When there are multiple processing chambers as described above, there is a pressure difference between the multiple processing chambers. Therefore, between adjacent processing chambers, the reaction gas flows from one processing chamber to another processing chamber, or the reaction gas flows from another processing chamber to one processing chamber, thereby mixing the reaction gases. When this mixing occurs, the in-plane uniformity of the material to be formed into the film may be deteriorated.

The reaction gas leaked from the process chamber to the cavity further diffuses away from the process chamber and is easily mixed into another process chamber. However, even when trying to exhaust the reaction gas, since the space inside the cavity other than the process chamber has a shape that is difficult to smoothly perform exhaust or a shape that is diffused over a large area, it is necessary to set a large number of exhaust positions or expand the exhaust area, making it difficult to achieve efficient exhaust.

The embodiments of the present disclosure are proposed to solve the above-mentioned problems and suppress mixing of reaction gases between processing parts.

According to one embodiment of the present disclosure, a film forming device includes: a chamber having an interior capable of becoming a vacuum; a turntable, which is arranged in the chamber and is configured to rotate to circulate and transport a workpiece along a circumferential transport path; a plurality of processing units, which are configured to perform plasma processing on the workpiece transported by the turntable by plasmatizing a reaction gas introduced into the processing units; an inner wall, which is arranged in at least one of the processing units to define a processing space, the reaction gas is introduced into the processing space to perform the plasma processing in the processing space, and the inner wall has an opening facing the turntable in a non-contact manner; an outer wall, which is configured to cover the periphery of the inner wall with a gap interposed between the inner wall and the outer wall, and is configured to form an array An exhaust space having an opening facing the turntable in a non-contact manner and being closed on the opposite side of the opening; and an exhaust port, which is communicated with the exhaust space and connected to an exhaust device, the exhaust device being configured to suck the reaction gas leaked from the gap between the opening in the inner wall and the turntable and discharge the reaction gas to the outside of the chamber, wherein one or more of the processing units is a film forming part, the film forming part being configured to form a film by depositing a film forming material on the workpiece by means of sputtering, and wherein both ends of the outer wall are in contact with the side surface of the chamber, and a portion of the outer periphery of the inner wall is separated from the side surface of the chamber, so that the reaction gas cannot circulate through the opposite ends of the exhaust space.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the present disclosure and, together with the general description given above and the detailed description of the embodiments given below, serve to explain the principles of the present disclosure.

FIG. 1 is a perspective plan view schematically illustrating a configuration of a film forming apparatus according to an embodiment.

Fig. 2 is a cross-sectional view taken along line A-B in Fig. 1 , and illustrates the internal configuration viewed from one side of the film-forming apparatus.

Fig. 3 is a cross-sectional view taken along line A-C in Fig. 1 , and illustrates the internal configuration viewed from one side of the film-forming apparatus.

4A and 4B illustrate a nitrided portion, wherein FIG. 4A is a perspective plan view and FIG. 4B is a cross-sectional view taken along line D-D in FIG. 4A .

FIG. 5 is a flowchart of a process performed by the film forming apparatus according to the embodiment.

6A and 6B schematically illustrate a modification of the embodiment, wherein FIG. 6A is a perspective plan view and FIG. 6B is a cross-sectional view taken along line E-E in FIG. 6A .

7A and 7B illustrate variations in which a single exhaust port is provided, wherein Fig. 7A is a perspective plan view illustrating the solution of Fig. 4A , and Fig. 7B is a perspective plan view illustrating the solution of Fig. 6A .

8 is a perspective plan view of the nitriding portion, and illustrates the flow of a process gas leaking from the inner wall in an area near the exhaust port and an area far from the exhaust port in the exhaust space.

FIG. 9 is a cross-sectional view illustrating a modification in which a buffer space is provided by covering an outer wall with a second outer wall.

Figures 10A and 10B schematically illustrate the construction of a film forming device according to a variation in which a second outer wall and a buffer space are arranged in the film forming part, wherein Figure 10A is a perspective plan view and Figure 10B is a cross-sectional view taken along line F-F in Figure 10A.

11A and 11B illustrate a nitrided portion according to a modification in which a mask is provided at an opening of an exhaust space, wherein FIG. 11A is a perspective plan view and FIG. 11B is a cross-sectional view taken along line H-H in FIG. 11A .

FIG. 12 illustrates a modification in which the shape of the outer wall is the same as the shape of the inner wall, and is a perspective plan view illustrating the scheme of FIG. 4A .

13A and 13B illustrate a variation in which the shape of the inner wall is the same as that of the outer wall, wherein FIG. 13A is a perspective plan view illustrating the scheme of FIG. 4A , and FIG. 13B is a perspective view illustrating the inner wall, the outer wall, and the partition plate.

14 is a perspective plan view schematically illustrating a configuration of a film forming apparatus according to a modification in which an exhaust space is provided in two film forming portions adjacent to a nitriding portion.

Figures 15A and 15B illustrate variations in which a partition plate is set in an exhaust space, wherein Figure 15A is a perspective plan view of the scheme of Figure 4A in which one partition plate is set, and Figure 15B is a perspective plan view of the scheme of Figure 4A in which multiple partition plates are set.

FIG. 16 illustrates a modification in which the height of the outer wall is reduced, and is a perspective plan view illustrating the scheme of FIG. 4B .

17 illustrates a modification in which the opening of the exhaust space has different sizes on the upstream side and the downstream side of the conveying path, and is a perspective plan view illustrating the scheme of FIG. 4A .

FIG. 18 illustrates a modification in which a conductance valve is provided between the exhaust port and the exhaust device, and is a perspective plan view illustrating the scheme of FIG. 4A .

DETAILED DESCRIPTION

Reference will now be made in detail to various embodiments, examples of which are illustrated in the accompanying drawings. In the following detailed description, many specific details are set forth in order to provide a comprehensive understanding of the present disclosure. However, it will be apparent to one of ordinary skill in the art that the present disclosure may be implemented without these specific details. In other cases, well-known methods, procedures, systems, and components are not described in detail in order to avoid unnecessarily obscuring the schemes of the various embodiments. It should be noted that the accompanying drawings are schematic diagrams, and the dimensions, proportions, etc. of the various components may include portions that are exaggerated for ease of understanding.

(Overview)

The film forming apparatus 1 illustrated in FIGS. 1 to 3 includes a plurality of processing units PU, each of which is configured to plasmatize a reaction gas introduced into the processing unit and perform plasma processing on a workpiece 10 transported to the processing unit by a turntable 31. At least one of the processing units PU is a film forming portion 40, which is configured to form a film by depositing a film forming material on the workpiece 10 by sputtering. In the present embodiment, an example will be given in which a gallium nitride (GaN) film is formed on the workpiece 10 by the film forming apparatus 1. Therefore, the film forming portion 40 forms a GaN film on the workpiece 10 as a film formation object by sputtering. In addition, the film forming apparatus 1 includes a nitriding portion 50 as a processing unit PU, which is configured to nitride a film formed on the workpiece 10 by plasma processing. In the present embodiment, a double-wall exhaust space 60 is formed in the nitriding portion 50 by covering an inner wall 511 defining a processing space 59 with an outer wall 61. A double-wall exhaust space 60 can also be defined in the film forming portion 40 by covering the processing space 41 in the film forming portion 40 with the inner wall 511 and the outer wall 61. In the following description, the reaction gas used in the film forming portion 40 will be referred to as sputtering gas G1, and the reaction gas used in the nitriding portion 50 will be referred to as processing gas G2.

The workpiece 10 to be film-formed is, for example, a silicon (Si) wafer, a silicon carbide (SiC) wafer, a sapphire substrate, a glass substrate, etc. The workpiece 10 is placed on a tray 11 and conveyed. The tray 11 is a plate body held on a turntable 31 .

The film forming apparatus 1 includes a chamber 20, a conveying section 30, a film forming section 40, a nitriding section 50, an exhaust space 60, a surface treatment section 70, a conveying chamber 80, a cooling chamber 90, and a control device 100. The chamber 20 is a container having an interior that can be made into a vacuum. The chamber 20 is cylindrical, and the interior of the chamber is divided into a plurality of sections. The film forming section 40 is arranged in three sector-shaped sections divided by a partition 22. The nitriding section 50 and the surface treatment section 70 are arranged in sections other than the section where the film forming section 40 is arranged.

Each film forming section 40 includes a plasma generator P1 configured to plasmatize a sputtering gas G1 introduced into a space between a target 42 made of a film forming material containing GaN and the turntable 31 , and deposit particles of the film forming material on the workpiece 10 circulated and transported by the turntable 31 by sputtering to form a film.

The nitriding part 50 includes a processing space 59 surrounded by an inner wall 511 not in contact with the turntable 31, and a plasma generator P2 configured to plasmatize a processing gas G2 containing nitrogen (N ₂ ) introduced into the processing space 59. The nitriding part 50 nitridates particles of a film forming material deposited on the workpiece 10 circulated and transported by the turntable 31 by the film forming part 40.

When the workpiece 10 rotates multiple times in the circumferential direction inside the chamber 20, the workpiece 10 alternately and cyclically passes through the film forming part 40 and the nitriding part 50. Therefore, since the formation of the GaN film on the workpiece 10 and the nitridation of the non-nitrided Ga in the GaN film are alternately repeated, a GaN film having a desired thickness is grown.

The reason why a material containing GaN is used as the target 42 and the nitriding portion 50 is further provided to nitride Ga in the formed GaN film is as follows: Since Ga has a low melting point and is liquid at normal temperature and pressure, in order to obtain a solid target 42, the target 42 needs to contain nitrogen.

Here, DC discharge sputtering can increase the film forming rate relative to RF discharge sputtering. However, when the target 42 contains a large amount of nitrogen, the surface of the target 42 acts as an insulator, and in the target 42 having the surface acting as an insulator as described above, DC discharge may not occur.

In other words, when DC discharge sputtering is used in consideration of the film formation rate, there is a limit to the amount of nitrogen that can be contained in the GaN target 42. Therefore, nitridation of Ga in the target 42 is still insufficient, and the target 42 containing GaN contains Ga atoms that are not bonded to nitrogen (N) atoms.

When a GaN film is formed by using such a target 42, the formed GaN film has a low nitrogen content, and there are nitrogen defects (non-nitrided state) in the formed GaN film, so that the crystallinity of the film deteriorates and the flatness of the film deteriorates. Therefore, it is necessary to supplement the insufficient nitrogen. In this regard, it is conceivable to perform sputtering by adding nitrogen to the sputtering gas introduced into the film forming portion 40, but the surface of the target 42 will be nitrided and act as an insulator. Therefore, nitrogen cannot be added to the sputtering gas in the film forming portion 40 in order to supplement the insufficient nitrogen.

Therefore, in the present embodiment, in order to compensate for insufficient nitrogen in the GaN film formed by the film forming part 40, a nitriding process is further performed in the nitriding part 50 after the GaN film is formed by the film forming part 40. By performing the nitriding process during the film formation as described above, it is possible to increase the nitrogen content in the film formed on the workpiece 10 and form a GaN film without nitrogen defects.

(Cavity)

As shown in FIG. 2 , the cavity 20 is a container having an interior that can be made into a vacuum. The cavity 20 is cylindrical, and the interior of the cavity is divided into a plurality of sections. The cavity 20 is surrounded by a disc-shaped ceiling surface 20a, a disc-shaped bottom surface 20b, and an annular side surface 20c. The partition 22 is a rectangular wall plate that is radially arranged from the center of the cylindrical shape and extends from the ceiling surface 20a toward the bottom surface 20b, but does not reach the bottom surface 20b. That is, a cylindrical space is ensured on the bottom surface 20b side.

A turntable 31 configured to convey the workpiece 10 is arranged in the cylindrical space. The lower end of the partition 22 faces the placement surface of the workpiece 10 on the turntable 31 with a certain gap, and the gap is for the workpiece 10 placed on the turntable 31 to pass. A processing space 41 in which the workpiece 10 is processed by the film forming part 40 is partitioned by the partition 22. That is, the film forming part 40 has a processing space 41 smaller than the chamber 20. The partition 22 suppresses the sputtering gas G1 of the film forming part 40 from diffusing into the chamber 20. In the film forming part 40, since it is necessary to adjust the pressure in the processing space 41 partitioned to be smaller than the chamber 20, pressure adjustment can be easily performed, and plasma discharge can be stabilized.

In addition, an exhaust port 21 is provided in the chamber 20. The exhaust port 21 is connected to an exhaust section 23. The exhaust section 23 has a pipe, a pump, and a valve (not shown), etc. The interior of the chamber 20 can be decompressed to a vacuum by exhausting the gas through the exhaust port 21 by the exhaust section 23. In order to suppress the oxygen concentration to a low level, the exhaust section 23 performs exhaust until the vacuum degree reaches, for example, 10 ^-4 Pa.

(Conveying part)

The conveying section 30 has a turntable 31 and a motor 32. The turntable 31 is provided in the cavity 20, and rotates to circulate and convey the workpieces 10 along the circular conveying path L. The turntable 31 of the present embodiment holds and conveys a plurality of workpieces 10. The turntable 31 is a disc-shaped member arranged inside the cavity 20, and widely extends to the extent that the turntable 31 does not contact the inner side of the side surface 20c.

The turntable 31 is supported by a rotating shaft 33 coaxial with the center of the circle via a fastening member. The rotating shaft 33 passes through the bottom surface 20b of the chamber 20 in an airtight manner and protrudes to the outside. The motor 32 is arranged outside the chamber 20 and rotates the rotating shaft 33 via a coupling member, thereby rotating the turntable 31 continuously at a predetermined rotation speed. The turntable 31 rotates at a speed of, for example, 1 to 150 rpm.

As shown in Fig. 1, a film forming area FA for forming films on a plurality of workpieces 10 is provided in the turntable 31. As shown by the double-dashed line in Fig. 1, the film forming area FA in a plan view is an area excluding the rotation axis 33 of the turntable 31, and is an annular area facing the film forming section 40 and the nitriding section 50. In the film forming area FA, holding areas HA for holding the respective workpieces 10 are provided at equal intervals in the circumferential direction.

In each holding area HA, a holding portion such as a groove, a hole, a protrusion, a clamp or a holder is provided, and a tray 11 on which the workpiece 10 is placed is held by a mechanical chuck or an adhesive chuck. For example, a plurality of workpieces 10 are placed on the tray 11, and six holding areas HA are arranged on the turntable 31 at intervals of 60 degrees. In other words, the film forming apparatus 1 can form a film together on a plurality of workpieces 10 held in a plurality of holding areas HA, and therefore has very high productivity. In addition, the tray 11 can be omitted, and the workpiece 10 can be directly held in the holding area HA of the turntable 31. In addition, although not shown, a heater for heating the workpiece 10 is provided in each holding area HA. As the heater, a heater that generates heat when powered on can be used. In addition, the tray 11 and the workpiece 10 in the holding area HA are arranged so that their top surfaces are flush with the top surface of the turntable 31.

[Film formation part]

The film forming part 40 generates plasma and exposes the target 42 made of a film forming material to the plasma. Therefore, the film forming part 40 deposits particles (hereinafter, referred to as "sputtered particles") of the target 42 ejected by causing ions contained in the plasma to collide with the target 42 on the workpiece 10 to form a film. The film forming part 40 includes a plasma generator P1 configured to plasmatize the sputtering gas G1 introduced into the space between the target 42 made of the film forming material and the turntable 31.

As shown in FIG. 2 , the plasma generator P1 includes a sputtering source, a power source 46 , and a sputtering gas introduction portion 49 . The sputtering source includes a target 42 , a backing plate 43 , and an electrode 44 .

The target 42 is a plate-like member made of a film-forming material that is deposited on the workpiece 10 to form a film. The target 42 is kept at a distance from the conveying path L of the workpiece 10 placed on the turntable 31. The surface of the target 42 is held on the ceiling surface 20a of the chamber 20 in a manner facing the workpiece 10 placed on the turntable 31. One or more targets 42 are provided for one film-forming portion 40. In the present embodiment, three targets 42 are provided, and the three targets 42 are arranged at positions arranged on the vertices of a triangle in a plan view.

The backing plate 43 is a supporting member for holding the target 42. The target 42 is held on the ceiling surface 20a of the chamber 20 via the backing plate 43. The backing plate 43 holds each target 42 separately. The electrode 44 is a conductive member for applying power to each target 42 separately from the outside of the chamber 20, and is electrically connected to the target 42. The power applied to each target 42 can be changed separately. In addition, the sputtering source is appropriately equipped with a magnet, a cooling mechanism, etc. as needed.

The power source 46 is, for example, a DC power source that generates a high voltage, and is electrically connected to the electrode 44. The power source 46 applies the generated power to the target 42 via the electrode 44. The turntable 31 has the same potential as the grounded chamber 20, and by applying a high voltage to the target 42, a potential difference is generated between the target 42 and the turntable 31.

The sputtering gas introduction part 49 introduces the sputtering gas G1 into the chamber 20, as shown in FIG2. The sputtering gas introduction part 49 has a source (not shown) of the sputtering gas G1 such as a cylinder, a pipe 48, and a gas introduction port 47. The pipe 48 is connected to the source of the sputtering gas G1, passes through the chamber 20 in an airtight manner, and extends into the chamber 20. One end of the pipe 48 is opened as the gas introduction port 47. The sputtering gas introduction part 49 of the present embodiment introduces the sputtering gas G1 into the processing space 41 so that the pressure in the processing space 41 becomes, for example, above 0.3 Pa and below 1.0 Pa.

The gas introduction port 47 opens at the space between the turntable 31 and the target 42, and introduces the sputtering gas G1 for film formation into the processing space 41 formed between the turntable 31 and the target 42. A rare gas can be used as the sputtering gas G1, and the sputtering gas G1 can be argon (Ar) gas or the like. The sputtering gas G1 is a gas that does not contain nitrogen ( _N2 ), and can be a single argon (Ar) gas. The rare gas does not react with particles of the film forming material. For example, even when the sputtering gas G1 is a single Ar gas, the sputtering gas G1 is included in the reaction gas. In other words, even when the gas itself does not react with other substances, a gas such as a rare gas that indirectly promotes the reaction of other substances is included in the reaction gas.

In the film forming part 40 as described above, when the sputtering gas G1 is introduced from the sputtering gas introduction part 49 and the power supply 46 applies a high voltage to the target 42 via the electrode 44, the sputtering gas G1 introduced into the processing space 41 formed between the turntable 31 and the target 42 is plasmatized and active components such as ions are generated. The ions in the plasma collide with the target 42 and start to knock out sputtered particles.

In addition, the workpiece 10 circulated and transported by the turntable 31 passes through the processing space 41. When the workpiece 10 passes through the processing space 41, the ejected sputtered particles are deposited on the workpiece 10, and a film made of the sputtered particles is formed on the workpiece 10. The workpiece 10 is circulated and transported by the turntable 31, and repeatedly passes through the processing space 41, thereby performing a film forming process. The thickness of the film deposited each time the film passes through the film forming part 40 varies according to the processing rate of the nitriding part 50, but the film can be, for example, a thin film of the order of 1 to 2 atoms (less than 5nm). By circulating and transporting the workpiece 10 multiple times, the film thickness is increased, and a film with a predetermined thickness is formed on the workpiece 10.

In the present embodiment, the film forming device 1 includes a plurality of (here, 3) film forming parts 40, and one film forming part 40 is provided in each of the three sections separated by the partition 22. The plurality of film forming parts 40 form a film consisting of layers of a plurality of film forming materials by selectively depositing film forming materials. In particular, in the present embodiment, the film forming part 40 includes a sputtering source corresponding to different types of film forming materials, and selectively deposits film forming materials to form a film consisting of layers of a plurality of types of film forming materials. The sputtering sources corresponding to different types of film forming materials include: a case where the film forming materials of all the film forming parts 40 are different from each other, and a case where one film forming material is shared by a plurality of film forming parts 40, but other film forming materials are different from the shared film forming material. Selectively depositing film forming materials one by one means that while the film forming part 40 for one film forming material forms a film, other film forming parts 40 for other film forming materials do not perform film formation.

In the present embodiment, the film-forming material of the targets 42 of the two film-forming portions 40 is a material containing Ga and GaN, and the targets 42 serve as a source of sputtered particles containing Ga atoms to be deposited on the workpiece 10. The targets 42 contain GaN and incomplete nitrogen-deficient GaN, i.e., Ga atoms that are not bonded to nitrogen (N).

The film-forming material of the target 42 of one film-forming portion 40 is a material containing Al, and the target 42 serves as a source of sputtered particles containing Al atoms to be deposited on the workpiece 10. In addition, the target 42 for sputtering may contain substances other than Ga, Al, and nitrogen (N) as long as the target 42 can supply sputtered particles containing Ga atoms and sputtered particles containing Al atoms.

As shown in Figure 1, in order to distinguish two types of film forming parts 40, the two film forming parts 40 having targets 42 made of Ga and GaN materials will be referred to as film forming parts 40A (GaN film forming parts), and the film forming part 40 having a target 42 made of Al-containing material will be referred to as film forming part 40B (Al film forming part).

(Nitriding part)

The nitriding part 50 generates inductively coupled plasma in the processing space 59 into which the processing gas G2 containing nitrogen is introduced. That is, the nitriding part 50 plasmatizes the nitrogen gas to generate chemical components. Nitrogen atoms contained in the generated chemical components collide with the film containing Ga atoms and the film containing Al atoms formed on the workpiece 10 by the film forming part 40 to bond with Ga atoms not bonded to nitrogen in the film containing Ga atoms and with Al atoms in the film containing Al atoms. As a result, a GaN film or an AlN film free of nitrogen defects can be obtained.

As shown in FIG. 2 , the nitriding part 50 includes a plasma generator P2 , and the plasma generator P2 includes an inner wall 511 , a cover 512 , a window 52 , an antenna 53 , an RF power source 54 , a matching box 55 , and a process gas introduction portion 58 .

The inner wall 511 is a member covering the periphery of the processing space 59. That is, the inner wall 511 is provided in the processing unit PU, the inner wall 511 partitions and defines the processing space 59 for introducing the processing gas G2 and performing plasma processing, and has an opening 511a facing the turntable 31 in a non-contact manner. As shown in Figures 1 and 2, the inner wall 511 is cylindrical. One end of the inner wall 511 is fitted into the opening 21b provided in the ceiling surface 20a of the chamber 20. The inner wall 511 protrudes into the internal space of the chamber 20 in such a manner that the opening 511a at the other end of the inner wall 511 faces the turntable 31. However, the inner wall 511 does not contact the turntable 31. In addition, the inner wall 511 contacts the side surface 20c of the chamber 20. Therefore, the space around the outer periphery of the inner wall 511 is partitioned by the side surface 20c of the chamber 20. In addition, the inner wall 511 and the side surface 20 c do not necessarily need to directly contact each other, and a partition member may be interposed between the outer circumference of the inner wall 511 and the side surface 20 c of the cavity 20 to partition the space around the outer circumference of the inner wall 511 .

The cover 512 is a cylindrical member. One end of the cover 512 is installed to align with the opening 21b of the chamber 20 in such a way that the cover 512 protrudes outward and upward from the ceiling surface 20a of the chamber 20. The window 52 is a flat plate made of a dielectric material such as quartz, and its shape is substantially similar to the horizontal cross-section of the cover 512. The window 52 is arranged inside the cover 512 so as to close the opening 21b and separate the inside of the cover 512 from the processing space 59 in the chamber 20 where the processing gas G2 containing nitrogen is introduced. At this time, it is necessary to suppress oxidation caused by oxygen flowing into the processing space 59. For example, the required oxygen concentration is very low, 10 ¹⁹ atoms/cm ³ or less. In order to solve this problem, the surface of the window 52 is coated. For example, by coating the surface of the window 52 with yttrium oxide (Y ₂ O ₃ ), it is possible to suppress the release of oxygen from the surface of the window 52, while suppressing the consumption of the window 52 due to plasma, thereby maintaining the oxygen concentration low.

A processing space 59 is formed in the nitriding part 50 by being surrounded by the turntable 31 and the inner wall 511. The workpiece 10 circulated and conveyed by the turntable 31 repeatedly passes through the processing space 59, thereby performing the nitriding process.

The antenna 53 is a conductor wound into a coil shape, and is arranged in an inner space of the cover 512 isolated from the processing space 59 in the chamber 20 by the window 52. When an alternating current is passed through the antenna 53, the antenna 53 generates an electric field. The antenna 53 can be placed near the window 52 so that the electric field generated from the antenna 53 is effectively introduced into the processing space 59 via the window 52. An RF power supply 54 that applies an RF voltage is connected to the antenna 53. A matching box 55 as a matching circuit is connected in series to the output side of the RF power supply 54. The matching box 55 stabilizes plasma discharge by matching the impedance of the input side and the output side.

2 , the process gas introduction part 58 introduces the process gas G2 containing nitrogen into the process space 59. The process gas introduction part 58 has a source (not shown) of the process gas G2 such as a cartridge, a pipe 57, and a gas introduction port 56. The pipe 57 is connected to the source of the process gas G2, passes through the chamber 20 while sealing the chamber 20 in an airtight manner, and extends into the chamber 20. The end opening of the pipe 57 is the gas introduction port 56.

The gas introduction port 56 opens at the processing space 59 between the window 52 and the turntable 31, and introduces the processing gas G2. A rare gas can be used as the processing gas G2, and the processing gas G2 can be argon gas, nitrogen gas, etc. In addition, for example, the processing gas G2 can be supplied in a supply amount that maintains the pressure in the processing space 59 at 5 Pa.

The processing space 59 in which the nitriding process is performed by the nitriding part 50 is partitioned by the inner wall 511. That is, the nitriding part 50 has the processing space 59 which is smaller than the chamber 20 and is spaced apart from the processing space 41. Since it is necessary to adjust the pressure in the processing space 59 partitioned into a space smaller than the chamber 20, the pressure can be easily adjusted and the plasma discharge can be stabilized.

In the nitriding part 50 as described above, an RF voltage is applied to the antenna 53 from the RF power supply 54. Therefore, an RF current flows through the antenna 53, and an electric field is generated due to electromagnetic induction. An electric field is generated in the processing space 59 via the window 52, and inductively coupled plasma is generated in the processing gas G2. At this time, a chemical component of nitrogen containing nitrogen atoms is generated, and collides with the film on the workpiece 10, thereby bonding with the atoms constituting the film. As a result, the film on the workpiece 10 is nitrided to form a nitride film as a composite film.

As described above, the nitriding part 50 has a function of producing a composite film by plasmatizing nitrogen gas to produce chemical components containing nitrogen atoms and causing a chemical reaction with a film formed on the workpiece 10. In the nitriding part 50, by using inductively coupled plasma having a high plasma density, a chemical reaction between the chemical components in the plasma and the film formed on the workpiece 10 by the film forming part 40 is effectively caused, thereby making it possible to produce a composite film.

(Exhaust space)

The inner wall 511 is provided in at least one processing unit PU, and the exhaust space 60 is a space formed by a double wall consisting of an outer wall 61 and an inner wall 511, and the outer wall 61 covers the periphery of the inner wall 511 with a gap between the outer wall 61 and the inner wall 511, and has an opening 61a facing the turntable 31 in a non-contact manner. The opposite side of the opening 61a of the exhaust space 60 is closed. In the case of such a configuration, the processing gas G2 leaked from the processing space 59 through the gap between the opening 511a of the inner wall 511 and the turntable 31 flows into the exhaust space 60 provided on the periphery of the inner wall 511.

The outer wall 61 is a U-shaped plate-like body covering the inner wall 511 in a plan view (see FIG. 1 ). The outer wall 61 is bent along the surface of the inner wall 511 on the side of the rotation shaft 33 (the side opposite to the side surface 20 c), and both ends of the outer wall 61 are in contact with the side surface 20 c of the cavity 20. The two ends of the outer wall 61 are opposite ends of the U-shape, that is, two ends located on the opening side of the U-shape. The ends are end faces extending in the vertical direction, that is, in the direction orthogonal to the rotation plane of the turntable 31 (in the direction parallel to the rotation shaft 33).

In addition, the outer wall 61 covers the inner wall 511 in a side view (see FIG. 2 ). The end of the outer wall 61 on the opening 61a side is at the same height position as the end of the inner wall 511 on the opening 511a side, or at a height position covering the end of the inner wall 511 on the opening 511a side. The side of the outer wall 61 opposite to the opening 61a is closed by a plate parallel to the rotation plane of the turntable 31. However, the upper part of the outer wall 61 may be closed by the ceiling surface 20a of the cavity 20.

As described above, in the case where the gap is interposed between the inner wall 511 and the outer wall 61, the space around the inner wall 511 is partitioned by covering the space with the outer wall 61 to form the exhaust space 60. In addition, a portion of the inner wall 511 is in contact with the side surface 20c of the chamber 20. By this contact portion, the exhaust space 60 is partitioned over the entire circumference of the inner wall 511 in a plan view. As a result, opposite ends through which the process gas G2 in a plan view does not circulate around the entire circumference of the inner wall 511 are formed in the exhaust space 60. More specifically, the exhaust space 60 having a U-shaped horizontal cross section is formed around the inner wall 511, and the side surface 20c of the chamber 20 serves as the opposite ends of the exhaust space 60.

As shown in FIG. 2 , the distance d1 between the opening 511a of the inner wall 511 and the turntable 31 and the distance d2 between the opening 61a of the outer wall 61 and the turntable 31 are distances that do not hinder the rotation of the turntable 31. In addition, the end of the outer wall 61 facing the turntable 31 is closer to the turntable 31 than the end of the inner wall 511 facing the turntable 31. In other words, the lower end (opening 61a) of the outer wall 61 is located closer to the turntable 31 than the lower end (opening 511a) of the inner wall 511. Without being limited to this, the distance d1 and the distance d2 may be equal to each other.

As shown in FIG. 4A , an exhaust port 62 is provided in the exhaust space 60. The exhaust port 62 is communicated with the exhaust space 60 and is connected to an exhaust device 63, which sucks the processing gas G2 leaked from the gap between the opening 511a of the inner wall 511 and the turntable 31, and discharges the processing gas G2 to the outside of the chamber 20. As the exhaust device 63, for example, a turbo pump can be used, which includes a rotor blade and a fixed blade having a turbine-type blade, and generates an airflow by rotating the rotor blade at a high speed. A plurality of exhaust ports 62 are provided. The exhaust ports 62 of the present embodiment are formed on both sides of the side surface 20c of the chamber 20 corresponding to the opposite ends of the exhaust space 60. The exhaust flow rate can be, for example, more than 300L/min. When two exhaust devices 63 are used, each exhaust device 63 can have an exhaust flow rate of more than 150L/min.

[Surface treatment part]

The surface processing section 70 processes the surface of the workpiece 10 circulated and conveyed by the turntable 31 and the surface of the film deposited by the film forming section 40. The processing performed by the surface processing section 70 is to remove the oxide film from the surface of the workpiece 10 before the film is deposited by the film forming section 40, and to flatten the surface of the film formed on the workpiece 10. The film formed on the workpiece 10 is a film formed on the workpiece 10 until the film reaches a desired thickness.

Specifically, the film being formed is a composite film on the workpiece 10 that has been processed by the nitriding section 50 or a film that has been formed on the workpiece 10 by the film forming section 40. In other words, the conveying section 30 circulates and conveys the workpiece 10 so that the workpiece 10 passes through the film forming section 40, the nitriding section 50, and the surface treatment section 70, whereby the surface treatment section 70 emits ions onto the composite film on the workpiece 10 that has been processed by the nitriding section 50. Alternatively, when the film forming section 40, the surface treatment section 70, and the nitriding section 50 are arranged in sequence along the conveying direction relative to the respective sections 40, 50, and 70, the conveying section 30 circulates and conveys the workpiece 10 so that the workpiece 10 passes through the film forming section 40, the surface treatment section 70, and the nitriding section 50, whereby the surface treatment section 70 emits ions onto the film formed on the workpiece 10 by the film forming section 40.

The surface processing part 70 is arranged in a section other than the section where the film forming part 40 and the nitriding part 50 are arranged. The surface processing part 70 includes a plasma generator P3 including a cylindrical electrode 71, a shield 72, a process gas introduction part 75, and an RF power supply 76.

As shown in Fig. 1 and Fig. 3, the surface treatment part 70 includes a box-shaped cylindrical electrode 71 extending from above the cavity 20 to the inside of the cavity 20. In the present embodiment, the shape of the cylindrical electrode 71 is not particularly limited, but is basically fan-shaped in a plan view. The cylindrical electrode 71 has an opening 71a at the bottom. The outer edge of the opening 71a, that is, the lower end of the cylindrical electrode 71 faces the top surface of the workpiece 10 on the turntable 31, wherein there is a small gap between the lower end of the cylindrical electrode 71 and the top surface of the workpiece 10 on the turntable 31.

The cylindrical electrode 71 is in a rectangular cylindrical shape, has an opening 71a at one end, and is closed at the other end. The cylindrical electrode 71 is installed in the opening 21a provided in the ceiling surface 20a of the chamber 20 via an insulator 71c in such a manner that the end of the cylindrical electrode 71 having the opening 71a faces the turntable 31. The side wall of the cylindrical electrode 71 extends into the interior of the chamber 20.

A flange 71b extending outward is provided at the end of the cylindrical electrode 71 opposite to the opening 71a. An insulator 71c is fixed between the flange 71b and the periphery of the opening 21a of the cavity 20 in such a manner that the interior of the cavity 20 is maintained airtight. The material of the insulator 71c is not particularly limited as long as the insulator 71c has insulating properties. For example, the insulator 71c may be made of a material such as polytetrafluoroethylene (PTFE).

The opening 71a of the cylindrical electrode 71 is arranged at a position facing the conveying path L of the turntable 31. The turntable 31 serves as the conveying section 30 and conveys the tray 11 on which the workpiece 10 is placed through the position facing the opening 71a. In addition, in a plan view, the opening 71a of the cylindrical electrode 71 has a size to accommodate the workpiece 10 placed on the tray 11.

As described above, the cylindrical electrode 71 passes through the opening 21a of the cavity 20, and a portion of the cylindrical electrode 71 is exposed to the outside of the cavity 20. The portion of the cylindrical electrode 71 exposed to the outside of the cavity 20 is covered by the outer shell 71d, as shown in FIG3. The space inside the cavity 20 is maintained airtight by the outer shell 71d. The portion of the cylindrical electrode 71 located inside the cavity 20, that is, the periphery of the side wall of the cylindrical electrode 71, is covered by the shielding member 72.

The shield 72 is a fan-shaped rectangular cylinder concentric with the cylindrical electrode 71, and its size is larger than the cylindrical electrode 71. The shield 72 is connected to the cavity 20. Specifically, the shield 72 stands upright from the edge of the opening 21a of the cavity 20, and the end extending toward the inside of the cavity 20 is located at the same height as the opening 71a of the cylindrical electrode 71. Since the shield 72 acts as a cathode like the cavity 20, the shield 72 can be made of a conductive metal member with low resistance. The shield 72 can be integrally formed with the cavity 20, or can be installed in the cavity 20 by using a fixed metal member or the like.

The shield 72 is configured to stably generate plasma in the cylindrical electrode 71. In the case where there is a predetermined gap between each side wall of the shield 72 and each side wall of the cylindrical electrode 71, each side wall of the shield 72 is configured to extend substantially parallel to each side wall of the cylindrical electrode 71. When the gap becomes too large, the capacitance decreases or the plasma generated in the cylindrical electrode 71 enters the gap. Therefore, the gap can be as small as possible. However, when the gap becomes too small, the capacitance between the cylindrical electrode 71 and the shield 72 increases, which is not preferred. The size of the gap can be appropriately set according to the capacitance required to generate plasma. Although FIG. 3 only illustrates two side wall surfaces extending in the radial direction of the shield 72 and the cylindrical electrode 71, a gap having the same size as the side wall surface extending in the radial direction is also provided between the two side wall surfaces extending in the circumferential direction of the shield 72 and the cylindrical electrode 71.

In addition, the process gas introduction part 75 is connected to the cylindrical electrode 71. In addition to the pipeline, the process gas introduction part 75 also includes a gas source, a pump, a valve, etc. (not shown) for the process gas G3. The process gas G3 is introduced into the cylindrical electrode 71 through the process gas introduction part 75. The process gas G3 can be appropriately changed according to the processing purpose. For example, the process gas G3 can contain oxygen or nitrogen, an inert gas plus oxygen or nitrogen, or an inert gas such as argon.

The RF power supply 76 is connected to the cylindrical electrode 71 to apply an RF voltage. A matching box 77 as a matching circuit is connected in series to the output side of the RF power supply 76. The RF power supply 76 is also connected to the chamber 20. When a voltage is applied from the RF power supply 76, the cylindrical electrode 71 acts as an anode, and the chamber 20, the shield 72, the turntable 31 and the tray 11 act as cathodes, that is, they function as electrodes for reverse sputtering. Therefore, as described above, the turntable 31 and the tray 11 have conductivity and are in contact with each other to be electrically connected.

The matching box 77 stabilizes the discharge of plasma by matching the impedance of the input side and the output side. The chamber 20 or the turntable 31 is grounded. The shield 72 connected to the chamber 20 is also grounded. Both the RF power supply 76 and the process gas introduction part 75 are connected to the cylindrical electrode 71 via a through hole provided in the housing 71d.

When argon gas as the process gas G3 is introduced into the cylindrical electrode 71 from the process gas introduction portion 75 and an RF voltage is applied to the cylindrical electrode 71 from the RF power supply 76, capacitively coupled plasma is generated, and the argon gas is plasmatized to generate electrons, ions, radicals, etc. The ions in the generated plasma are emitted onto the film being formed on the workpiece 10.

That is, the surface processing section 70 includes a cylindrical electrode 71, one end of which is provided with an opening 71a into which the processing gas G3 is introduced, and an RF power supply 76, which applies an RF voltage to the cylindrical electrode 71. When the conveying section 30 conveys the workpiece 10 passing directly below the opening 71a, ion irradiation is performed by introducing ions into a film formed on the workpiece 10. In the surface processing section 70, in order to introduce ions into the film formed on the workpiece 10, a negative bias voltage is applied to the tray 11 and the turntable 31 on which the workpiece 10 is placed.

By using the cylindrical electrode 71 as in the surface processing section 70, ions can be introduced into the formed thin film by applying a desired negative bias voltage to the tray 11 and the turntable 31 on which the workpiece 10 is placed, which are at a ground potential, even when an RF voltage is not applied to the tray 11 and the turntable 31. With this configuration, since it is not necessary to add a structure for applying an RF voltage to the tray 11 and the turntable 31 or to consider the ratio of the area of the electrode serving as an anode to the area of other members around the electrode serving as a cathode in order to obtain a desired bias voltage, the device design becomes easy.

Therefore, even when film formation and ion irradiation are repeated while the workpiece 10 is moved to flatten a film being formed on the workpiece 10 , ions can be introduced into the film formed on the workpiece 10 with a simple structure.

The processing space 74 in which the surface treatment is performed by the surface treatment part 70 is divided by the cylindrical electrode 71. The cylindrical electrode 71 can suppress the diffusion of the processing gas G3 into the chamber 20. That is, the surface treatment part 70 has a processing space 74, which is smaller than the chamber 20 and is spaced apart from the processing spaces 41 and 59. In addition, in the surface treatment part 70, the cylindrical electrode 71 can be regarded as the inner wall 511. When the outer wall 61 is provided in the surface treatment part 70, the outer wall 61 can cover the periphery of the cylindrical electrode 71 in the case where the gap is between the outer wall 61 and the cylindrical electrode 71, so that the outer wall 61 does not contact the shield 72. In this case, the shield 72 is arranged between the outer wall 61 and the cylindrical electrode 71. Since it is necessary to adjust the pressure in the processing space 74 divided into a space smaller than the chamber 20, the pressure can be easily adjusted and the plasma discharge can be stabilized. The arrangement order and number of the film forming part 40, the nitriding part 50 and the surface treatment part 70 are not particularly limited.

The surface processing section 70 has a function of flattening a thin film by applying a negative bias voltage to the tray 11 and the turntable 31 on which the workpiece 10 is placed and introducing ions into the film formed on the workpiece 10. In the surface processing section 70, by using the cylindrical electrode 71, ions can be simply introduced into the film formed on the workpiece 10 and the film can be flattened.

(Transportation Room)

The conveying chamber 80 is a container configured to load and unload the workpiece 10 relative to the chamber 20 via the gate valves GV1 and GV2. As shown in FIG. 1 , the conveying chamber 80 has an internal space in which the workpiece 10 before being loaded into the chamber 20 is accommodated. The conveying chamber 80 is connected to the chamber 20 via the gate valve GV1. Although not shown in the figure, a conveying mechanism configured to load and unload the tray 11 on which the workpiece 10 is placed relative to the chamber 20 is provided in the internal space of the conveying chamber 80. The conveying chamber 80 is depressurized by an exhaust mechanism such as a vacuum pump (not shown), and when the chamber 20 maintains a vacuum, the conveying mechanism loads the tray 11 on which the unprocessed workpiece 10 is placed into the chamber 20, and unloads the tray 11 on which the processed workpiece 10 is placed from the chamber 20.

The loading cabinet 81 is connected to the conveying chamber 80 via a gate valve GV2. The loading cabinet 81 is a device by which, when the conveying chamber 80 is maintained in vacuum, the tray 11 on which the unprocessed workpiece 10 is placed is loaded from the outside into the conveying chamber 80 by using a conveying mechanism (not shown), and the tray 11 on which the processed workpiece 10 is placed is unloaded from the conveying chamber 80. In addition, the loading cabinet 81 switches between a vacuum state in which the loading cabinet 81 is decompressed by an exhaust mechanism such as a vacuum pump (not shown) and an atmosphere-open state in which the vacuum is broken.

(Cooling room)

The cooling chamber 90 cools the workpiece 10 unloaded from the chamber 20. The cooling chamber 90 includes a container connected to the conveying chamber 80, and has a cooling mechanism configured to cool the workpiece 10 placed on the tray 11 unloaded from the conveying chamber 80. As the cooling mechanism, for example, a blower configured to blow out a cooling gas can be used. As the cooling gas, for example, Ar gas from a source of the sputtering gas G1 can be used. The cooling temperature can be a temperature that allows conveyance in air, for example, 30°C. In addition, the tray 11 arranged in the conveying chamber 80 and on which the processed workpiece 10 is placed is loaded into the cooling chamber 90 by a conveying mechanism (not shown).

(Control device)

The control device 100 controls the various components of the film forming apparatus 1, such as the exhaust section 23, the sputtering gas introduction section 49, the process gas introduction section 58, the exhaust devices 63 and 73, the power supply 46, the RF power supplies 54 and 76, the motor 32, the exhaust device 63, the conveying chamber 80, the loading cabinet 81, and the cooling chamber 90. The control device 100 is a processing device including a programmable logic controller (PLC) and a central processing unit (CPU), and stores a program describing the control content.

Specific examples of the control contents may include the initial exhaust pressure of the film forming apparatus 1, the power applied to the target 42, the antenna 53 and the cylindrical electrode 71, the flow rate of the sputtering gas G1 and the processing gases G2 and G3, the introduction time, the exhaust flow rate and the number of exhaust times, the film forming time, the surface processing time, the rotation speed of the motor 32, the cooling temperature, the cooling time, etc. Therefore, the control device 100 can handle a wide variety of film forming technical parameters.

[operate]

Next, the operation of the film forming device 1 controlled by the control device 100 will be explained. A film forming method for forming a film by using the film forming device 1 as described below is also an aspect of the present disclosure. FIG. 5 is a flow chart of a film forming process performed by the film forming device 1 of the present embodiment. The film forming process is a process of alternately stacking AlN films and GaN films on the workpiece 10 and further forming a GaN layer. Since the lattices of silicon wafers and sapphire substrates are different from those of GaN, there is a problem that the crystallinity of GaN will deteriorate when a GaN film is formed directly on a silicon wafer and a sapphire substrate. In order to eliminate this lattice mismatch, a buffer layer is formed by alternately stacking AlN films and GaN films, and a GaN layer is formed on the buffer layer. For example, this method can be used when a GaN layer is formed on a silicon wafer via a buffer layer in the manufacture of a horizontal MOSFET or LED.

First, the interior of the chamber 20 is exhausted from the exhaust port 21 through the exhaust section 23, and the pressure in the chamber 20 is always reduced to a predetermined pressure. In addition, along with the exhaust, the heater starts heating to heat the turntable 31 (step S01). When the turntable 31 starts to rotate, the entire interior of the chamber 20 is heated by radiation from the heated turntable 31. By heating along with the exhaust, the desorption of residual gases such as water molecules and oxygen molecules in the chamber 20 is promoted. Therefore, it becomes difficult for the residual gas to mix as an impurity during film formation, thereby improving the crystallinity of the film. After a gas analyzer (such as Q-Mass) detects that the oxygen concentration in the chamber 20 has dropped below a predetermined value, the rotation of the turntable 31 is stopped.

The pallet 11 on which the workpiece 10 is placed is loaded into the conveying chamber 80 by the conveying mechanism via the loading cabinet 81 and the gate valve GV2, and is sequentially loaded into the cavity 20 via the gate valve GV1 (step S02). In step S02, the turntable 31 sequentially moves the empty holding areas HA to the loading position of the pallet 11 loaded from the conveying chamber 80. Each holding area HA holds the pallet 11 loaded by the conveying mechanism, respectively. As described above, the pallet 11 on which the workpiece 10 is placed is placed in all the holding areas HA on the turntable 31.

When the turntable 31 starts rotating again, the workpieces 10 are heated by the heater, and the oxide film on the surface of each workpiece 10 is removed by the surface processing portion 70 (step S03). That is, as the turntable 31 rotates, the workpieces 10 repeatedly pass under the surface processing portion 70. In the surface processing portion 70, the process gas G3 is introduced into the cylindrical electrode 71 from the process gas introduction portion 75, and an RF voltage is applied to the cylindrical electrode 71 from the RF power supply 76. The process gas G3 is plasmatized by applying the RF voltage, and ions in the plasma collide with the surface of the workpiece 10 passing under the opening 71a, thereby removing the oxide film.

Then, a buffer layer is formed by alternately repeating the formation of an AlN film by the film forming portion 40B and the nitriding portion 50 and the formation of a GaN film by the film forming portion 40A and the nitriding portion 50 .

First, an AlN film is formed on the workpiece 10 in the film forming part 40B and the nitriding part 50 (step S04). That is, in the film forming part 40B, the sputtering gas introduction part 49 supplies the sputtering gas G1 via the gas introduction port 47. The sputtering gas G1 is supplied around the target 42 made of Al. The power supply 46 applies a voltage to the target 42. Therefore, the sputtering gas G1 is plasmatized. The ions generated by the plasma collide with the target 42 and knock out sputtering particles containing Al atoms.

When the unprocessed workpiece 10 passes through the film forming portion 40B, a thin film on which sputtered particles containing Al atoms are deposited is formed on the surface of the workpiece 10. In the present embodiment, a thin film having a thickness of one to two Al atoms is deposited each time the workpiece passes through the film forming portion 40B.

The workpiece 10 that has passed through the film forming part 40B by the rotation of the turntable 31 passes through the nitriding part 50, and in the process of passing through the nitriding part 50, the Al atoms in the film are nitrided. That is, in the nitriding part 50, the process gas introduction part 58 supplies the process gas G2 containing nitrogen to the processing space 59 between the window 52 and the turntable 31 via the gas introduction port 56. At the same time, the exhaust device 63 starts to exhaust the exhaust space 60. In the processing space 59, a nitrogen atmosphere at a predetermined pressure (for example, 5Pa) is formed by supplying the process gas G2. The process gas G2 leaked from the processing space 59 through the gap between the opening 511a in the inner wall 511 and the turntable 31 is sucked by the exhaust device 63 to flow into the exhaust space 60 and discharged from the exhaust port 62. Therefore, the process gas G2 is prevented from leaking into the cavity 20 and flowing into the film forming part 40 and the surface treatment part 70.

The RF power supply 54 applies an RF voltage to the antenna 53. The electric field generated by the antenna 53, in which the RF current flows due to the application of the RF voltage, reaches the processing space 59 via the window 52. The electric field excites the processing gas G2 containing nitrogen gas supplied to the processing space 59 to generate plasma. The nitrogen chemical components generated by the plasma collide with the Al thin film on the workpiece 10 and bond with the Al atoms, and the Al atoms are nitrided to form an AlN film.

The workpiece 10, which has passed through the nitriding part 50 and on which the AlN film is formed by the rotation of the turntable 31, is directed toward the surface treatment part 70 where the AlN film is irradiated with ions (step S05). That is, in the surface treatment part 70, the treatment gas introduction part 75 supplies the treatment gas G3 containing argon gas to the treatment space 74 surrounded by the cylindrical electrode 71 and the turntable 31 inside the cylindrical electrode 71 via a pipeline. When a voltage is applied to the cylindrical electrode 71 by the RF power supply 76, the cylindrical electrode 71 acts as an anode, the chamber 20, the shield 72, the turntable 31 and the tray 11 act as cathodes, and the treatment gas G3 supplied to the space inside the cylindrical electrode 71 is excited to generate plasma. Further, the argon ions generated by the plasma collide with the AlN film formed on the workpiece 10, so that the particles move to the sparse portion in the film and the film surface is flattened.

As described above, in steps S04 to S05, when the workpiece 10 passes through the processing space 41 of the film forming section 40B in operation, the film forming process is performed, and when the workpiece 10 passes through the processing space 59 of the nitriding section 50 in operation, the nitriding process is performed. Then, when the workpiece 10 passes through the space in the cylindrical electrode 71 of the surface processing section 70 in operation, the AlN film formed on the workpiece 10 is flattened. The term "in operation" has the same meaning as the plasma generating operation of generating plasma performed in the processing space of each section 40, 50, and 70.

The turntable 31 continues to rotate until an AlN film having a predetermined thickness is formed on the workpiece 10, that is, until a predetermined time obtained in advance by simulation or experiment has passed (step S06: "No"). In other words, the workpiece 10 continues to circulate between the film forming part 40 and the nitriding part 50 until an AlN film having a predetermined thickness is formed. Since the nitriding process can be performed each time Al is deposited to have a thickness at the atomic level, in order to maintain a balance between film formation and nitriding, the rotation speed of the turntable 31 is set to a relatively slow speed of 50 to 60 rpm.

After the predetermined time has passed (step S06: Yes), the film formation and nitridation of the GaN film are continued. Specifically, first, the voltage application of the power source 46 to the target 42 is stopped, and the operation of the film forming section 40B is stopped.

Next, a GaN film is formed on the workpiece 10 by the film forming part 40A and the nitriding part 50 (step S07). Then, the flattening of the GaN film is performed (step S08). That is, in the film forming part 40A, the sputtering gas introduction part 49 supplies the sputtering gas G1 around the target 42 made of Ga and GaN, and the power supply 46 applies a voltage to the target 42 to plasmatize the sputtering gas G1. The ions generated by the plasma collide with the target 42, and sputtering particles containing Ga atoms are knocked out.

Thus, a thin film on which sputtered particles containing Ga atoms are deposited is formed on the surface of the AlN film. In the present embodiment, each time the workpiece 10 passes through the film forming portion 40A, a film is deposited to have a film thickness of one to two Ga atoms level.

The workpiece 10 that has passed through the film forming part 40A by the rotation of the turntable 31 passes through the nitriding part 50, and in the process of passing through the nitriding part 50, Ga atoms in the thin film are nitrided. That is, in the nitriding part 50, the process gas introduction part 58 supplies the process gas G2 containing nitrogen gas to the process space 59 between the window 52 and the turntable 31 through the gas introduction port 56 to form a nitrogen atmosphere of a predetermined pressure in the process space 59. At the same time, the exhaust device 63 starts to exhaust the exhaust space 60. The process gas G2 leaked from the process space 59 through the gap between the inner wall 511 and the turntable 31 is sucked by the exhaust device 63 to flow into the exhaust space 60 and is exhausted from the exhaust port 62. Therefore, the process gas G2 is prevented from leaking into the chamber 20 and flowing into the film forming part 40 and the surface treatment part 70.

An electric field generated by the antenna 53 through which an RF current flows due to application of an RF voltage is generated in the processing space 59 via the window 52. In addition, due to the electric field, the processing gas G2 containing nitrogen and supplied to the processing space 59 is excited to generate plasma. The nitrogen chemical component generated by the plasma collides with the nitrogen-deficient GaN (non-nitrided state) thin film deposited on the workpiece 10 by sputtering and is bonded with Ga atoms, so that a fully nitrided GaN film is formed.

The workpiece 10, which has passed through the nitriding section 50 and on which the GaN film is formed by the rotation of the turntable 31, is directed toward the surface processing section 70, and the GaN film is irradiated with ions in the surface processing section 70 (step S08). When the ions collide with the GaN film formed on the workpiece 10, particles are moved to a sparse portion in the film and the film surface is flattened.

As described above, in steps S07 to S08, when the workpiece 10 passes through the processing space 41 of the film forming part 40A in operation, the film forming process of forming a Ga-containing film is performed, and when the workpiece 10 passes through the processing space 59 of the nitriding part 50 in operation, the nitriding process is performed, thereby forming a GaN film. Then, when the workpiece 10 passes through the space in the cylindrical electrode 71 of the surface processing part 70 in operation, the GaN film formed on the workpiece 10 is flattened.

After the time period obtained by simulation or experiment has passed (as the time period for forming a GaN film having a predetermined thickness on the workpiece 10), the formation of the Al film is continued again so that the Al film and the GaN film are stacked. That is, after the predetermined time period has passed (step S09: "Yes"), the power supply 46 stops applying the voltage to the target 42, and stops the operation of the film forming section 40A.

The formation of the AlN film and the GaN film as described above is repeated until the number of stacked layers reaches a predetermined number (step S10: “No”). When the number of stacked layers reaches a predetermined number (step S10: “Yes”), the formation of the buffer layer is terminated.

Furthermore, a GaN layer is formed on the buffer layer (step S11). The formation of the GaN layer is performed in the same manner as the formation of the GaN film in the buffer layer described above, but is performed for a period of time that allows the GaN layer to reach a predetermined thickness set for the GaN layer.

After the buffer layer and the GaN layer are formed as described above, the tray 11 on which the film-formed workpiece 10 is placed is unloaded into the cooling chamber 90 by the conveying mechanism via the conveying chamber 80. In the cooling chamber 90, the workpiece 10 is cooled to a predetermined temperature and then discharged from the loading cabinet 81 (step S12).

In the above description, the nitriding section 50 and the surface treatment section 70 are continuously operated during the film formation of the buffer layer (steps S04 to S11), but the operation of the nitriding section 50 or the surface treatment section 70 may be stopped each time the respective steps S04 to S11 are terminated. In this case, the operation of the nitriding section 50 is stopped after the operation of the film forming section 40B and the operation of the film forming section 40A are stopped. With this configuration, the surface of the film formed on the workpiece 10 can also be sufficiently nitrided, so that an AlN film or a GaN film without nitrogen defects can be obtained.

(Effect)

(1) The film forming apparatus 1 of the embodiment includes: a chamber 20 having an interior capable of being made into a vacuum; a turntable 31 disposed in the chamber 20 and configured to rotate to circulate and transport the workpiece 10 along a circumferential transport path L; a plurality of processing units PU configured to perform plasma processing on the workpiece 10 transported by the turntable 31 by plasmatizing a reaction gas introduced into the processing units PU; an inner wall 511 disposed in at least one processing unit PU to define a processing space 41 into which a reaction gas is introduced to perform plasma processing in the processing space, and having a non-contact manner. an outer wall 61, which is constructed to cover the periphery of the inner wall 511 with a gap between the inner wall 511 and the outer wall 61, and is constructed to form an exhaust space 60, the exhaust space 60 having the opening 61a facing the turntable 31 in a non-contact manner and being closed on the opposite side of the opening 61a; and an exhaust port 62, which is communicated with the exhaust space 60 and is connected to an exhaust device 63, the exhaust device 63 is constructed to suck the reaction gas leaked from the gap between the opening 511a in the inner wall 511 and the turntable 31, and discharge the reaction gas to the outside of the chamber 20.

In addition, at least one processing unit PU is a film forming part 40 configured to form a film by depositing a film forming material on the workpiece 10 by sputtering, and both ends of the outer wall 61 are in contact with the side surface 20c of the cavity 20, and a portion of the outer periphery of the inner wall 511 is separated from the side surface 20c of the cavity 20, so that the reaction gas cannot circulate through the opposite ends of the exhaust space 60.

As described above, since the exhaust space 60 along the inner wall 511 is formed between the double walls composed of the inner wall 511 and the outer wall 61 covering the inner wall 511, the reaction gas leaked from the gap between the inner wall 511 and the turntable 31 can be directly sucked by the exhaust device 63 through the opening 61a in the outer wall 61 and the gap between the turntable 31 and flow into the exhaust space 60, and can be discharged from the exhaust port 62. That is, by sucking and discharging the reaction gas leaked from the opening 511a in the inner wall 511 substantially from the entire circumference of the inner wall 511, it is possible to suppress the reaction gas from flowing into the chamber 20. Therefore, it is possible to prevent the reaction gas from entering other processing units PU in the chamber 20. In particular, by setting the opposite ends of the exhaust space 60 so that the reaction gas cannot circulate therethrough, the area exhausted by the exhaust device 63 can be suppressed within a narrow range, thereby making the exhaust efficiency better than the case where the opposite ends are connected to each other.

Furthermore, when the distance d1 between the opening 511a in the inner wall 511 and the turntable 31 and the distance d2 between the opening 61a in the outer wall 61 and the turntable 31 illustrated in FIG. 2 are too large, the amount (pressure) of the process gas G2 required by the process space 59 cannot be retained in the process space 59. In contrast, when the distances d1 and d2 are too small, the end of the outer wall 61 facing the turntable 31 contacts the turntable 31, restricting the circulation and transportation through the turntable 31. Therefore, the distances d1 and d2 are distances that allow the process gas G2 supplied to the process space 59 to remain in the process space 59 at a predetermined pressure (e.g., 5 Pa) without restricting the rotation of the turntable 31. Since the process gas G2 leaking from the inner wall 511 is sucked into the exhaust space 60 adjacent thereto, the process gas G2 does not leak to the outside of the outer wall 61. That is, by setting the supply of the process gas G2 and the suction of the process gas G2 to be balanced with each other to maintain the internal pressure at a predetermined pressure, the distances d1 and d2 can be set to leave a sufficient margin to avoid contact.

Furthermore, the distances d1 and d2 are the distances between the inner wall 511 and the turntable 31 and between the outer wall 61 and the turntable 31 over the entire circumference. In addition, in the present embodiment, since the turntable 31 and the workpiece 10 are flush with each other, the distance between the inner wall 511 and the turntable 31 and the distance between the outer wall 61 and the turntable 31 are the same as the distance between the inner wall 511 and the workpiece 10 and the distance between the outer wall 61 and the workpiece 10. When the workpiece 10 protrudes beyond the turntable 31, the above distances are the distances from the workpiece 10.

(2) The end of the outer wall 61 facing the turntable 31 is closer to the turntable 31 than the end of the inner wall 511 facing the turntable 31. Therefore, the reaction gas leaked from the gap between the inner wall 511 and the turntable 31 easily flows into the exhaust space 60 and is blocked by the outer wall 61, thereby preventing the reaction gas from leaking to the outside. In addition, even when the turntable 31 is deformed due to heat, the reaction gas is prevented from leaking to the outside of the outer wall 61.

More specifically, as shown in FIG. 2 , the distance d2 is smaller than the distance d1. For example, by setting the distance d1 to be less than 10 mm and the distance d2 to be less than 5 mm, the difference between the distance d1 and the distance d2 can be 1 mm to 5 mm. When the distance d2 is smaller than the distance d1, the conductivity of the reaction gas when passing through the distance d2 is smaller than the conductivity of the reaction gas when passing through the distance d1. Therefore, when d1>d2, the reaction gas is less likely to leak from the outer wall. Therefore, the suction of the reaction gas can be set to be weak. This results in a reduction in the amount of gas supplied, thereby maintaining the internal pressure at a predetermined pressure. That is, the consumption of gas can be reduced.

(3) A plurality of exhaust ports 62 are provided. Therefore, exhaust can be performed at a high speed by exhausting from a plurality of positions.

(4) The exhaust port 62 is provided in the side surface 20c of the chamber 20. Therefore, exhaust can be performed via a short path without being hindered by the members in the process unit PU or the turntable 31.

(5) The exhaust ports 62 are provided at opposite ends of the exhaust space 60 having a U-shaped horizontal cross section. Therefore, the entire exhaust space 60 can be exhausted at high speed from the opposite ends.

(6) At least one film forming part 40 has a target 42 made of a film forming material containing GaN, and at least one processing unit PU is a nitriding part 50, which is configured to nitridate particles of the film forming material deposited by the film forming part 40 by plasmatizing a nitrogen-containing reaction gas introduced into the processing space.

Therefore, by supplying the process gas G2 containing nitrogen to perform the nitriding process in the nitriding part 50, even when the pressure of the process gas G2 in the nitriding part 50 becomes high, the process gas G2 leaking from the process space 59 through the gap between the inner wall 511 and the turntable 31 is sucked into the exhaust space 60 and exhausted from the exhaust port 62. Therefore, the process gas G2 is prevented from flowing into the film forming part 40 and nitriding the surface of the target 42 to turn the surface into an insulator that hinders the generation of plasma by discharge. In addition, since exhaust is not performed directly from the process space 59 but is performed from the exhaust space 60 around the periphery of the process space 59, the pressure in the process space 59 can be easily maintained.

[Variation]

The present disclosure is not limited to the above-described embodiment. Although the basic configuration is the same as that of the above-described embodiment, the following modifications are also applicable.

(1) As shown in FIGS. 6A and 6B , a plurality of vent holes 61 b may be provided in the outer wall 61, and a buffer flow path 64 may be provided around the outer wall 61 to cover the vent holes 61 b. An exhaust port 62 is provided in the buffer flow path 64. As shown in FIG. 6A , the buffer flow path 64 is airtightly connected to the exhaust port 62 via a seal 64 a. Since the exhaust port 62 is provided in the buffer flow path 64, the exhaust device 63 can exhaust the buffer flow path 64 from the exhaust port 62, and at the same time exhaust the exhaust space 60 connected to the buffer flow path 64 via the vent holes 61 b. Therefore, the processing gas G2 can be uniformly exhausted from the periphery of the outer wall 61.

Here, when there is no buffer flow path 64, a comparison is made between a region A1 near the exhaust port 62 in the exhaust space 60 and a region A2 far from the exhaust port 62 in the exhaust space 60. As illustrated in FIG. 8 , the process gas G2 leaking from the inner wall 511 to the region A1 near the exhaust port 62 is immediately exhausted to the outside of the chamber 20 by the exhaust device 63. In contrast, the process gas G2 leaking from the inner wall 511 to the region A2 far from the exhaust port 62 flows in the exhaust space 60 and reaches the region A1 near the exhaust port 62. Therefore, the process gas G2 leaking from the inner wall 511 to the region A1 near the exhaust port 62 is more easily exhausted by the exhaust device 63 than the process gas G2 leaking to the region A2 far from the exhaust port 62. Therefore, there is a possibility that the distribution of the process gas G2 in the process space 59 becomes uneven. When the distribution of the process gas G2 in the process space 59 becomes uneven, the quality of the film formed on the workpiece 10 will also become uneven, which is not preferable.

As shown in Figures 6A and 6B, when the exhaust port 62 is provided in the buffer flow path 64, the process gas G2 in the exhaust space 60 is exhausted via the vent hole 61b. Therefore, the process gas G2 leaking from the inner wall 511 to the area A1 near the exhaust port 62 is difficult to be exhausted by the exhaust device 63. That is, the buffer flow path 64 plays a role in reducing (relieving) the exhaust amount of the process gas G2 leaking from the inner wall 511 to the area A1 near the exhaust port 62. As a result, the amount of the process gas G2 exhausted in the area A1 near the exhaust port 62 and the amount of the process gas G2 exhausted in the area A2 away from the exhaust port 62 become equal to each other, so that the distribution of the process gas G2 in the processing space 59 can be uniform. Therefore, the quality of the film formed on the workpiece 10 can be made uniform.

In addition, the vent 61b may be a through hole. In this case, the diameter of the through hole at a position near the region A1 close to the exhaust port 62 may be small, and the diameter of the through hole at a position near the region A2 far from the exhaust port 62 may be large. Alternatively, the through hole at a position near the region A2 far from the exhaust port 62 may be larger than the through hole at a position near the region A1 close to the exhaust port 62. In addition, the through hole may be slit-shaped. In this case, the through hole at a position near the region A2 far from the exhaust port 62 may also be larger than the through hole at a position near the region A1 close to the exhaust port 62. In addition, as the vent 61b, a single through hole or a slit-shaped hole may be provided. In this case, the through hole or the slit-shaped hole may be configured so that the aperture increases from the region A1 close to the exhaust port 62 toward the region A2 far from the exhaust port 62. In addition, as shown in this scheme, the exhaust port 62 does not have to be directly connected to the exhaust space 60, and the exhaust port 62 may be indirectly connected to the exhaust space 60.

9 , a second outer wall 65 may be provided to cover the outer wall 61, and the exhaust port 62 may be provided in a buffer space 66 formed by covering the outer wall 61 with the second outer wall 65. In this case, the exhaust amount of the process gas G2 leaking from the inner wall 511 to the area A1 near the exhaust port 62 can also be reduced. In particular, the second outer wall 65 and the buffer space 66 in which the exhaust port 62 is provided may be provided in the film forming portion 40. Since the process gas G2 leaking from the nitriding portion 50 can be exhausted in the buffer space 66, the process gas G2 leaking from the nitriding portion 50 can be suppressed from entering the film forming portion 40.

Furthermore, when the outer wall 61, the second outer wall 65, and the buffer space 66 provided with the exhaust port 62 are provided in the film forming portion 40, the partition 22 has a trapezoidal shape in a plan view, as illustrated in FIG10A. That is, in the film forming portion 40, the partition 22 can be regarded as the inner wall 511. As illustrated in FIG10B, since the process gas G2 leaked from the nitriding portion 50 can be exhausted in the buffer space 66, the process gas G2 leaked from the nitriding portion 50 can be suppressed from entering the film forming portion 40. In addition, when the partition 22 is a rectangular wall plate as shown in FIG1, the exhaust space 60 can be formed by regarding the outer wall 61 and the second outer wall 65 as the inner wall 511 and the outer wall 61, respectively.

In addition, as shown in FIG. 11B , a mask 68 may be provided in the opening 60a of the exhaust space 60, the opening 60a being formed by the opening 511a in the inner wall 511 and the opening 61a in the outer wall 61. The mask 68 has a plurality of through holes 68a, as shown in FIG. 11A . The diameter of the through hole 68a may increase from the region A1 close to the exhaust port 62 toward the region A2 far from the exhaust port 62. With this configuration, the process gas G2 leaking from the inner wall 511 to the region A1 close to the exhaust port 62 becomes difficult to be discharged by the exhaust device 63. As a result, the amount of the process gas G2 discharged in the region A1 close to the exhaust port 62 and the amount of the process gas G2 discharged in the region A2 far from the exhaust port 62 may become equal to each other, thereby making the distribution of the process gas G2 in the process space 59 uniform.

In addition, as shown in FIG. 12 , the outer wall 61 may be C-shaped in a plan view. In the above embodiment, as shown in FIG. 8 , there is a region A3 where the distance between the inner wall 511 and the outer wall 61 is reduced between the region A1 close to the exhaust port 62 and the region A2 far from the exhaust port 62. When the region A3 having a reduced distance exists, the conductivity is reduced in the region A3, making it difficult for the process gas G2 in the exhaust space 60 to flow. As shown in FIG. 12 , when the outer wall 61 is C-shaped in a plan view, the distance between the inner wall 511 and the outer wall 61 becomes constant. As a result, since there is no portion in the exhaust space 60 where the conductivity is reduced, the process gas G2 in the exhaust space 60 can be easily discharged to the outside of the chamber 20 by the exhaust device 63. That is, the outer wall 61 may have the same shape as the inner wall 511.

In addition, like the blackened portion in FIG. 12 , a portion where the distance between the inner wall 511 and the outer wall 61 is not constant is generated near the exhaust port 62. In this case, the mask 68 may be provided at a portion corresponding to the blackened portion of the opening 60a of the exhaust space 60. With this configuration, the amount of the process gas G2 exhausted in the region A1 near the exhaust port 62 and the amount of the process gas G2 exhausted in the region A2 far from the exhaust port 62 may become equal to each other, thereby making it possible to make the distribution of the process gas G2 in the process space 59 uniform.

Alternatively, the profile of the inner wall 511 may be the same as the profile of the outer wall 61, so that the distance between the inner wall 511 and the outer wall 61 becomes constant. For example, as shown in FIG. 13B , a partition plate 67a may be provided in the inner wall 511, so that the distance between the inner wall 511 and the outer wall 61 becomes constant. In FIG. 13B , in order to avoid complication, the illustration of the chamber 20, the exhaust port 62, and the exhaust device 63 is omitted. By providing the partition plate 67a in the inner wall 511, an exhaust space 69 surrounded by the inner wall 511, the partition plate 67a, and the chamber 20 is formed, as shown in FIG. 13A . By forming the exhaust space 69, a portion of the process gas G2 leaking from the inner wall 511 to the area A1 near the exhaust port 62 flows into the exhaust space 69. A portion of the process gas G2 that has flowed into the exhaust space 69 flows into the exhaust space 60 and is then discharged to the outside of the chamber 20 by the exhaust device 63. Therefore, the amount of the processing gas G2 exhausted in the area A1 close to the exhaust port 62 and the amount of the processing gas G2 exhausted in the area A2 far from the exhaust port 62 can become equal to each other, thereby making the distribution of the processing gas G2 in the processing space 59 uniform.

(2) The exhaust port 62 may be provided at at least one of the opposite ends of the exhaust space 60. For example, as shown in FIG. 7A , the exhaust port 62 may be provided at one end of the exhaust space 60, or as shown in FIG. 7B , the exhaust port 62 may be provided at one end of the buffer flow path 64.

14 , when the exhaust space 60 is provided in the film forming portion 40 adjacent to the nitriding portion 50, the partition 22 may be regarded as the inner wall 511, and the outer wall 61 may cover the periphery of the partition 22. In this case, the exhaust port 62 may be provided at one end of the exhaust space 60 located near the nitriding portion 50. With this configuration, it is possible to further suppress the mixing of the process gas G2 into the film forming portion 40. The exhaust port 62 (exhaust device 63) may be provided at each of the opposite ends of the exhaust space 60.

(3) A partition plate 67 may be provided in the exhaust space 60 to divide the exhaust space 60 into a plurality of sections, and an exhaust port 62 may be provided in each section. That is, as illustrated in FIG. 15A , at least one partition plate 67 may be provided in the exhaust space 60, and the exhaust port 62 may be provided in a region continuous with the exhaust space 60. In this case, since the exhaust space 60 may be divided into two sections, the volume of the space exhausted via one exhaust port 62 is reduced. As a result, the process gas G2 in the exhaust space 60 may be exhausted more easily. In addition, the partition plate 67 may be connected to the outer wall 61 and/or the inner wall 511.

Furthermore, as illustrated in FIG. 15B , when the inside of the exhaust space 60 is divided into a plurality of sections, the exhaust port 62 may be located in the upper portion of the exhaust space 60 or in the side surface of the outer wall 61 inside the chamber 20. With this configuration, since the volume of the space exhausted by one exhaust port 62 (exhaust device 63) can be reduced, the process gas G2 in the exhaust space 60 can be exhausted more easily. In addition, since the exhaust port 62 is also provided at a position near the area A2 far from the exhaust port 62, the amount of the process gas G2 exhausted in the area A1 near the exhaust port 62 and the amount of the process gas G2 exhausted in the area A2 far from the exhaust port 62 can become equal to each other, thereby making it possible to make the distribution of the process gas G2 in the process space 59 uniform. Furthermore, the exhaust device 63 does not need to be directly connected to the exhaust port 62. The exhaust port 62 may be connected to the exhaust device 63 via a pipe connected to the exhaust port 62.

In addition, as shown in FIG. 16 , the height of the exhaust space 60 may be low. For example, the ceiling height of the exhaust space 60 may be set to be the same as the height of the upper portion of the opening of the exhaust port 62. With this configuration, the volume of the exhaust space 60 may be reduced so that the process gas G2 in the exhaust space 60 may be more easily discharged through the exhaust port 62 (exhaust device 63). In addition, when the height of the exhaust space 60 is low, the outer wall 61 may be connected to the inner wall 511. Alternatively, the opening 61a of the outer wall 61 may be supported by a member (not shown) that supports the opening 61a from below.

(4) As shown in FIG. 17 , the opening 60a of the exhaust space 60 may have different sizes on the upstream side and the downstream side of the transport path L. For example, in the nitriding portion 50, since the process gas G2 leaking from the inner wall 511 is affected by the rotation of the turntable 31, more process gas G2 leaks from the exhaust space 60 on the downstream side of the transport path L than on the upstream side of the transport path L. Therefore, the size of the opening (downstream side opening) 60a2 of the exhaust space 60 on the downstream side of the transport path L is set to be larger than the size of the opening (upstream side opening) 60a1 of the exhaust space 60 on the upstream side of the transport path L. By setting the downstream side opening 60a2 to be larger, the conductivity in the rising direction can be increased with respect to the process gas G2 leaking from the inner wall 511. As a result, the rising amount of the process gas G2 leaking from the inner wall 511 increases, and the process gas G2 leaking from the inner wall 511 becomes difficult to leak from the exhaust space 60. Therefore, it is possible to further suppress the process gas G2 from mixing into the film forming portion 40.

Furthermore, when the outer wall 61 is provided in the film forming part 40, the opening 61a of the exhaust space 60 on the side adjacent to the nitriding part 50 can be set large. In particular, the film forming part 40 arranged downstream of the nitriding part 50 in the transport path L can have a large opening 61a on the upstream side.

(5) A valve may be provided between the exhaust port 62 and the exhaust device 63 to adjust the exhaust amount of the reaction gas. For example, as shown in FIG. 18 , a conductance valve 62a may be provided between the exhaust port 62 and the exhaust device 63. The exhaust amount in the exhaust space 60 may be adjusted by the conductance valve 62a. As a result, since the amount of the process gas G2 leaking from the inner wall 511 may also be adjusted, the pressure in the process space 59 inside the inner wall 511 may be adjusted. In particular, the exhaust amount in the exhaust space 60 may be reduced by using the conductance valve 62a. With this configuration, the pressure in the process space 59 may be maintained even when the flow rate of the process gas G2 is small.

In addition, the opening of the conductance valve 62a on the downstream side of the conveying path L can be set to be larger than the opening of the conductance valve 62a on the upstream side of the conveying path L. With this configuration, the exhaust amount of the downstream side opening 60a2 can be increased. Therefore, it is difficult for the process gas G2 to leak from the downstream side opening 60a2. Therefore, it is possible to further suppress the process gas G2 from mixing into the film forming portion 40.

In this case, the amount of the process gas G2 leaking from the inner wall 511 to the area A1 near the exhaust port 62 can be reduced by using a mask 68 or a partition plate 67a having a through hole 68a. In addition, a buffer flow path or a buffer space as shown in Figures 6A and 6B can be provided. In addition, a structure in which the distance between the inner wall 511 and the outer wall 61 is constant can be adopted, or the height of the exhaust space 60 can be low. In addition, the opening 60a of the exhaust space 60 can have different sizes on the upstream side and the downstream side of the conveying path L.

(6) In the above scheme, the surface processing part 70 is provided in the chamber 20, but the surface processing part may be further provided outside the chamber 20. Like the surface processing part 70, the surface processing part may be provided with a cylindrical electrode 71, an RF power supply 76, and a processing gas introduction part 75, and the oxide film removal process may be performed on the workpiece 10 loaded in the surface processing part in a stationary state. In this scheme, during the film forming process performed on the workpiece 10 inside the chamber 20, the oxide film removal process may be performed on the workpiece 10 waiting outside the chamber 20. Therefore, the processing time inside the chamber 20 can be shortened. In addition, in the case where the flattening of the surface of the film being formed on the workpiece 10 is not performed, the film forming apparatus 1 may not include the surface processing part 70 in the chamber 20. In this case, since the surface processing part 70 is not present, the degree of freedom in design is improved when the outer wall 61 is provided in the film forming part 40 and the nitriding part 50, or when the buffer flow path 64 or the second outer wall 65 is provided in the outer wall 61. For example, without increasing the footprint of the apparatus, the outer wall 61 may be provided in the film forming part 40 and the nitriding part 50 , or the buffer flow path 64 or the second outer wall 65 may be provided in the outer wall 61 .

(7) The type and number of the processing units PU provided in the chamber 20 are not limited to the above-mentioned scheme. For example, the type and number of the film forming part 40, the nitriding part 50, and the surface treatment part 70 are not limited to the above-mentioned scheme. The number of the film forming part 40 may be one, two, or four or more. A plurality of nitriding parts 50 and surface treatment parts 70 may be provided. In addition, with respect to the film forming part 40, for example, the film forming apparatus 1 may be configured as a film forming apparatus that forms a GaN film by using only the film forming part 40A. In addition, in addition to the above-mentioned film forming part 40, a film forming part 40 different from the above-mentioned film forming part 40 in terms of target material type, a film forming part 40 the same as the above-mentioned film forming part 40 in terms of target material type, or a nitriding part 50 may be added. Instead of the nitriding part 50, an oxidation part that oxidizes the material formed on the workpiece 10 may be provided. In addition, the film forming material (target) used in the film forming chamber is not limited to GaN or Al, but may be any desired film forming material, such as Cu or Si.

(8) The arrangement order of the processing units PU that perform various processes such as film formation, nitriding, and surface treatment relative to the path for circulating and conveying the workpiece 10, that is, the arrangement order of the processing units PU can be appropriately set according to the process to be applied.

(9) In addition to the above scheme, an impurity adding section may be provided to add n-type or p-type impurities (dopants) to the formed GaN film. In this case, the film forming section, the nitriding section, and the impurity adding section are arranged in this order on the circulation and transport path. The impurity adding section has a similar configuration to the film forming section 40.

In this scheme, when a GaN film is formed, the impurity adding portion can form a layer including a p-channel (p-type semiconductor) obtained by adding Mg ions to the GaN layer together with the film forming portion 40A and the nitriding portion 50. In addition, when a GaN film is formed, the impurity adding portion can form a layer including an n-channel (n-type semiconductor) obtained by adding Si ions to the GaN layer together with the film forming portion 40A and the nitriding portion 50.

The n-type impurities or p-type impurities added to the GaN layer by the impurity adding part are not limited to those exemplified above. For example, the n-type impurities may include Ge or Sn. In this case, the film-forming material constituting the target set in the impurity adding part may be a film-forming material containing Ge or Sn instead of Si.

[Other embodiments]

According to the embodiments of the present disclosure, mixing of reaction gases between processing parts can be suppressed.

Although certain embodiments have been described, these embodiments are presented only by way of example and are not intended to limit the scope of the present disclosure. In fact, the embodiments described herein may be implemented in various other forms. In addition, various omissions, substitutions, combinations, and changes may be made to the forms of the embodiments described herein without departing from the spirit of the present disclosure. The accompanying claims and their equivalents are intended to cover such forms or variations that are within the scope and spirit of the present disclosure.

Description of Reference Numerals

1: film forming apparatus, 10: workpiece, 11: tray, 20: chamber, 20a: ceiling surface, 20b: bottom surface, 20c: side surface, 21: exhaust port, 21a, 21b: opening, 22: partition, 23: exhaust portion, 30: conveying portion, 31: turntable, 32: motor, 33: rotating shaft, 40, 40A, 40B: film forming portion, 41: processing space, 42: target, 43: back plate, 44: electrode, 46: power supply, 47: gas introduction port, 48: pipeline, 49: sputtering gas introduction portion, 50: nitriding portion, 511: inner wall, 511a: opening, 512: cover, 52: window, 53: ceiling line, 54: RF power supply, 55: matching box, 56: gas introduction port, 57: pipeline, 58: processing gas introduction part, 59: processing space, 60: exhaust space, 61: outer wall, 61a: opening, 61b: vent hole, 62: exhaust port, 63: exhaust device, 64: buffer flow path, 70: surface treatment part, 71: cylindrical electrode, 71a: opening, 71b: flange, 71c: insulator, 71d: shell, 72: shielding member, 74: processing space, 75: processing gas introduction part, 76: RF power supply, 77: matching box, 80: conveying room, 81: loading cabinet, 90: cooling room, 100: control device

Claims (9)

1. A film forming device comprising: a cavity having an interior capable of being a vacuum; a turntable disposed in the cavity and configured to rotate to circulate and transport the workpiece along a circumferential transport path; a plurality of processing units configured to perform plasma processing on the workpiece conveyed by the turntable by plasmatizing a reaction gas introduced into the processing units; an inner wall provided in at least one of the processing units to define a processing space into which the reaction gas is introduced to perform the plasma processing in the processing space, and having an opening facing the turntable in a non-contact manner; an outer wall configured to cover the periphery of the inner wall with a gap interposed therebetween and configured to form an exhaust space having an opening facing the turntable in a non-contact manner and closed on an opposite side of the opening; and an exhaust port communicating with the exhaust space and connected to an exhaust device configured to suck the reaction gas leaking from a gap between the opening in the inner wall and the turntable and exhaust the reaction gas to the outside of the chamber, wherein one or more of the processing units is a film forming section configured to form a film by depositing a film forming material on the workpiece by means of sputtering, and Both ends of the outer wall are in contact with the side surface of the chamber, and a portion of the outer periphery of the inner wall is separated from the side surface of the chamber, so that the reaction gas cannot circulate through opposite ends of the exhaust space. 2 . The film-forming apparatus according to claim 1 , wherein an end portion of the outer wall facing the turntable is closer to the turntable than an end portion of the inner wall facing the turntable. 3 . The film-forming apparatus according to claim 1 , wherein the exhaust port comprises a plurality of exhaust ports. 4 . The film-forming apparatus according to claim 1 , wherein the exhaust port is provided in a side surface of the chamber. 5. The film-forming apparatus according to claim 1, wherein a plurality of vent holes are provided in the outer wall, and Wherein, a buffer flow path configured to cover the vent hole is arranged around the outer wall. 6 . The film-forming apparatus according to claim 1 , wherein the exhaust port is provided at least one of opposite ends of the exhaust space. 7 . The film-forming apparatus according to claim 1 , wherein the exhaust port is provided at each of opposite ends of the exhaust space. 8 . The film-forming apparatus according to claim 6 , wherein a valve is provided between the exhaust device and the exhaust port to adjust an exhaust amount of the reaction gas. 9. The film-forming apparatus according to claim 1, wherein the film-forming portion has a target made of a film-forming material containing GaN, and At least one of the processing units is a nitriding section configured to nitridate particles of the film-forming material deposited by the film-forming section by plasmatizing a processing gas containing nitrogen and introduced into the processing space.