CN112041478A

CN112041478A - Film forming apparatus and film forming method

Info

Publication number: CN112041478A
Application number: CN201980028062.4A
Authority: CN
Inventors: 藤井博文
Original assignee: Kobe Steel Ltd
Current assignee: Kobe Steel Ltd
Priority date: 2018-04-27
Filing date: 2019-04-23
Publication date: 2020-12-04
Anticipated expiration: 2039-04-23
Also published as: WO2019208551A1; JP7130593B2; PT2019208551B; JP2019194354A; BR112020021943A2; CN112041478B

Abstract

The invention provides a film forming apparatus and a film forming method capable of accurately controlling the film thickness distribution of a coating film formed on a workpiece in the circumferential direction. The film forming method and apparatus include a case where a total amount of electric energy applied to the first evaporation source is made larger than a total amount of electric energy applied to the second evaporation source during the formation of the coating film so that a portion formed by the particles flying from the emission surface of the first evaporation source is thicker in the coating film formed on the film formation surface of the workpiece than a portion formed by the particles flying from the emission surface of the second evaporation source.

Description

Film forming apparatus and film forming method

Technical Field

The present invention relates to a film deposition apparatus and a film deposition method for forming a film on a film deposition surface of a workpiece.

Background

Conventionally, in order to improve the wear resistance of a workpiece such as a piston ring of an engine, a hard coating such as chromium nitride has been formed on a film formation surface of the workpiece, for example, an outer peripheral surface thereof by a film formation method such as PVD.

For example, the piston ring is a metal member having a shape in which a part of a ring is broken, and has a pair of opposite end portions facing each other with a space as the broken portion interposed therebetween. The piston ring is inserted into a cylinder of an engine and used while being deformed in a direction in which an outer diameter of the piston ring is reduced, that is, in a direction in which the pair of opposite end portions approach each other. In this use state, the force applied to the pair of opposing end portions that expands outward is the greatest. That is, the pair of opposite end portions are most strongly pressed against the cylinder inner wall, and therefore are most likely to be worn when the engine is used.

In contrast, in order to prevent the pair of opposite end portions from being worn, it is conceivable to form a hard coating on the outer circumferential surface of the piston ring and locally increase the thickness of the hard coating at the opposite end portions.

Conventionally, a film forming method described in patent document 1 is known as a film forming method for making the film thickness of a hard coating at a pair of opposed end portions of a piston ring larger than the film thickness of a hard coating at other portions.

The film forming method includes: placing the piston ring on a rotary table; driving the rotary table by a motor to rotate and revolve the piston ring; and controlling the motor so that a rotation speed of the piston ring is reduced when the pair of opposite end portions of the piston ring are substantially aligned with the evaporation source by giving a speed command to the motor. The motor control may be such that the thickness of the hard coating at the pair of opposing end portions is greater than the thickness of the hard coating at the other portion.

However, in the film deposition method in which the motor is controlled to change the rotation speed of the piston ring as described above, there is a time lag from when the speed command is issued to the motor until the actual rotation speed of the piston ring on the rotary table reaches the target rotation speed. This time lag varies during the film forming process depending on the weight of a workpiece such as a piston ring, the state of a turntable, the temperature, and the like, and therefore, the reproducibility of the control of the rotation speed of the piston ring is low. That is, it is difficult to reliably perform speed control for slowing down the rotation speed of the piston ring when the opposite end of the piston ring faces the evaporation source. This makes it difficult to accurately control the film thickness of the facing end portions. This problem similarly occurs in film formation in which the film thickness formed on the surface of a workpiece other than a piston ring is different in the circumferential direction.

Documents of the prior art

Patent document

Patent document 1: japanese patent publication No. 4680380

Disclosure of Invention

The invention aims to provide a film forming device and a film forming method which can accurately control the thickness distribution of a coating film formed on a film forming surface of a workpiece in the circumferential direction.

Provided is a film forming apparatus for forming a coating film on a side surface of a workpiece facing a direction perpendicular to a prescribed revolution central axis while revolving the workpiece around the revolution central axis. The film forming apparatus includes: at least one first evaporation source having an emission surface from which particles as a material for forming the coating film are flown, the first evaporation source being arranged symmetrically with respect to a reference line passing through the revolution central axis and perpendicular to a boundary line extending in a radial direction of an orbital circle drawn by the workpiece revolving around the revolution central axis when viewed in a direction in which the revolution central axis extends; at least one second evaporation source located on the opposite side of the first evaporation source with respect to the boundary line and symmetrically arranged with respect to the reference line; a first power supply that applies, to the first evaporation source, electric energy for flying particles for forming the coating film from an emission surface of the first evaporation source; a second power supply that applies, to the second evaporation source, electric energy for flying particles for forming the coating film from an emission surface of the second evaporation source; a workpiece rotating device that revolves the workpiece around the revolution central axis while supporting the workpiece in such a manner that a specific region of a side surface of the workpiece, on which the coating film is to be formed thicker than other regions, faces a posture in a specific radial direction selected from the radial directions of the orbital circle; and a control device that controls the electric energy applied from the first power supply to the first evaporation source and the electric energy applied from the second power supply to the second evaporation source so that a first coating portion, which is a portion formed by the particles flying off from the emission surface of the first evaporation source, in the coating film formed on the workpiece is thicker than a second coating portion, which is a portion formed by the particles flying off from the emission surface of the second evaporation source.

Also provided is a film forming method for forming a film on a film formation surface of a workpiece. The film forming method includes the following steps: a work arranging step of arranging the work so that a specific region of the film formation surface of the work, in which the coating film is to be formed thicker than other regions, faces a specific direction, the specific direction being a direction intersecting a boundary line defining a boundary between a first arrangement region and a second arrangement region, the first arrangement region being a region in which at least one first evaporation source having an emission surface on which particles as a material for forming the coating film are emitted into the first arrangement region is arranged, the second region being a region in which at least one second evaporation source having an emission surface on which particles as a material for forming the coating film are emitted into the second arrangement region is arranged; and a film forming step of forming the coating film on the film formation surface of the workpiece by causing the total amount of electric energy applied to the first evaporation source to cause the particles for forming the coating film to fly out from the emission surface of the first evaporation source to be larger than the total amount of electric energy applied to the second evaporation source to cause the particles for forming the coating film to fly out from the emission surface of the second evaporation source and causing the specific region on the film formation surface of the workpiece to face the specific direction so that a first coating portion, which is a portion of the coating film formed by the particles flying out from the emission surface of the first evaporation source, is thicker than a second coating portion, which is a portion of the coating film formed by the particles flying out from the emission surface of the second evaporation source.

Drawings

Fig. 1 is a plan view of a film deposition apparatus according to an embodiment of the present invention.

Fig. 2 is a plan view showing a piston ring as a workpiece on which film formation is performed by the film forming apparatus.

Fig. 3 is a plan view showing a work handling mechanism for rotating each of a plurality of rotation tables in accordance with the rotation of a revolution table of the film deposition apparatus.

Fig. 4 is a side view showing the work handling mechanism.

Fig. 5 is a flowchart illustrating a film formation method performed by the film formation apparatus shown in fig. 1.

Fig. 6 is a plan view of a film deposition apparatus according to modification 3 of the embodiment of the present invention.

Fig. 7 is a plan view of a film deposition apparatus according to modification 4 of the embodiment of the present invention.

Detailed Description

Embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

Fig. 1 is a plan view showing a film deposition apparatus 10 according to an embodiment of the present invention.

The film forming apparatus 10 is an apparatus for forming the coating film 90 shown in fig. 2 on each side surface of the plurality of piston rings 100 by a physical vapor deposition method such as arc ion plating or sputtering, while revolving the plurality of piston rings 100, each being a workpiece, around a predetermined revolution center axis CL 1. The side surface of each of the plurality of piston rings 100 is an outer peripheral surface 110 of the piston ring 100 facing in a direction perpendicular to the revolution center axis CL1 (in the present embodiment, in a horizontal direction), and is a film formation surface on which a film is formed. The outer peripheral surface 110 is substantially cylindrical in this embodiment.

The film forming apparatus 10 includes a chamber 20, a first target 30 (first evaporation source), a second target 40 (second evaporation source), a first arc power supply 50 (first power supply) for supplying an arc current to the first target 30, a second arc power supply 60 (second power supply) for supplying an arc current to the second target 40, a workpiece rotating device 70 for revolving the plurality of piston rings 100, and a control device 80 for controlling the currents of the first arc power supply 50 and the second arc power supply 60.

In the following description, a direction in which the first target 30 and the second target 40 face each other, that is, a target facing direction (in the present embodiment, a horizontal direction, which is an up-down direction on the paper surface of fig. 1) is a Y direction, a horizontal direction perpendicular to the Y direction (in the left-right direction on the paper surface of fig. 1) is an X direction, and directions perpendicular to the X direction and the Y direction (in the present embodiment, the up-down direction, which is a direction perpendicular to the paper surface of fig. 1) are Z directions.

The chamber 20 is a housing that houses the plurality of piston rings 100, the first target 30, and the second target 40, which are workpieces to be film-formed. The chamber 20 has a plurality of side walls, a top wall joined to respective upper edges of the plurality of side walls 22, and a bottom wall joined to respective lower edges of the plurality of side walls. In this embodiment, the plurality of side walls include a pair of

side walls

22A and 22B facing each other in the Y direction and a pair of

side walls

22C and 22D facing each other in the X direction. The plurality of side walls 22A-22D, the top wall and the bottom wall enclose an interior space 24. The plurality of piston rings 100, the first target 30, and the second target 40 are located within the interior space 24.

The first target 30 as the first evaporation source and the second target 40 as the second evaporation source each contain a film forming material for forming a coating film 90 shown in fig. 2 on the outer peripheral surface 110 of the piston ring 100. The film forming material is a material for forming a hard film in this embodiment, and for example, chromium or titanium is used when a hard film such as chromium nitride or titanium nitride is formed. The first target 30 and the second target 40 according to the present embodiment are formed of the same material. That is, the materials constituting the coating film 90 formed on the outer peripheral surface 110 of the piston ring 100 by the first target 30 and the second target 40 are the same as each other.

The first target 30 has a first emission surface 32, and particles to be the coating material, that is, the material of the coating 90 to be formed on the outer peripheral surface 110 are ejected from the first emission surface 32. The second target 40 has a second emission surface 42, and particles to be the material constituting the coating material, that is, the material of the coating 90 to be formed on the outer peripheral surface 110 are ejected from the second emission surface 42. The first target 30 is attached to one side wall 22A of a pair of

side walls

22A, 22B facing each other in the Y direction among the plurality of side walls 22A to 22D. The second target 40 is attached to the other side wall (that is, the side wall located on the opposite side of the side wall 22A to which the first target 30 is attached) 22B of the pair of

side walls

22A, 22B facing in the Y direction. The second emission surfaces 42 of the second target materials 40 and the first emission surfaces 32 of the first target materials 30 face each other in the Y direction. In other words, the second emission surfaces 42 face the first emission surfaces 32 in a direction perpendicular to the height direction of the cavity 20 (a direction perpendicular to the paper surface in fig. 1, that is, a Z direction). The first emission surface 32 and the second emission surface 42 are parallel to the revolution center axis CL1, which is a rotation center of a later-described revolution table 74.

The first target 30 is disposed on the opposite side of the second target 40 with the boundary line BL therebetween. The boundary line BL defines a boundary between a first arrangement region and a second arrangement region of the internal space 24 of the chamber 20, as viewed from above the chamber 20 (that is, as viewed along a direction in which a revolution center axis CL1 of the revolving stage 74 described later) in fig. 1. The first arrangement region is a region in which the first target 30 is arranged, and the second arrangement region is a region in which the second target 40 is arranged. The boundary line BL passes through the revolution center axis CL1 as a rotation center of the revolution table 74 when viewed from above the chamber 20. That is, the boundary line BL extends in the rotation radial direction of the revolution table 74.

The first target 30 and the second target 40 are arranged such that a reference line SL passes through the center of each of the first target 30 and the second target 40. That is, the first target 30 and the second target 40 are respectively arranged to be symmetrical about the reference line SL (symmetrical in the X direction). The reference line SL is perpendicular to the boundary line BL in fig. 1, i.e., when viewed from above the chamber 20 (i.e., when viewed from a direction in which the revolution central axis CL1 extends). The reference line SL passes through the revolution center axis CL 1.

The first arc power supply 50 as the first power supply applies electric energy for causing particles to fly out of the first emission surface 32 to the first target 30. Specifically, the first arc power supply 50 according to this embodiment supplies an arc current corresponding to the electric energy to the first target 30. The second arc power supply 60 as the second power supply applies electric energy for flying particles from the second emission surface 42 to the second target 40. Specifically, the second arc power supply 60 according to this embodiment supplies the second target 40 with an arc current corresponding to the electric energy. The first arc power supply 50 and the second arc power supply 60 have a cathode and an anode, respectively. The cathode of the first arc power supply 50 is connected to the first target 30, and the anode of the first arc power supply 50 is connected to the chamber 20. The cathode of the second arc power supply 60 is connected to the second target 40, and the anode of the second arc power supply 60 is connected to the chamber 20.

Each of the plurality of piston rings 100 as the workpiece is explained with reference to fig. 2. Fig. 2 is a plan view showing the piston ring 100.

The piston ring 100 is a member having a shape in which a part of a ring is broken, that is, a shape extending substantially 360 ° in the circumferential direction. That is, the piston ring 100 has a pair of

opposite end portions

102, 102 that face each other with a space 101 as a portion of a ring broken. Therefore, the outer peripheral surface 110 of the piston ring 100 has a substantially circular arc shape in plan view.

The coating film 90 is formed on the outer peripheral surface 110 by the film forming apparatus 10 so as to prevent the outer peripheral surface 110 from being abraded. The coating film 90 includes a first coating portion 92 formed by particles from the first target 30 and a second coating portion 94 formed by particles from the second target 40. The second coating portion 94 covers at least a region of the outer peripheral surface 110 of the piston ring 100 that is not covered by the first coating portion 92. At least a part of the first coating portion 92 formed by the particles from the first target 30 in the coating 90 has a thickness larger than that of the second coating portion 94 formed by the particles from the second target 40.

The outer peripheral surface 110 of the piston ring 100 includes a specific region as a partial region in the circumferential direction thereof. The specific region is a region where a coating film having a thickness larger than that of a coating film formed in a region other than the specific region is to be formed. The specific region corresponds to a portion which is most worn in the cylinder of the engine when the piston ring 100 is used in the engine, and generally corresponds to the outer peripheral surface 110 of each of the pair of

opposite end portions

102, 102.

At least a part of the first coating portion 92, which is a portion of the coating 90 formed on the outer peripheral surface 110 and formed by the particles from the first target 30, covers a region of the outer peripheral surface 110 of the piston ring 100 corresponding to each of the pair of opposite end portions 102, 102 (i.e., the specific region). That is, the first coating portion 92 is a portion of the coating 90 formed on the outer peripheral surface 110, is a portion formed by the particles from the first target 30, has a thickness larger than that of the second coating portion 94 formed by the particles from the second target 40, and covers the outer peripheral surfaces of the pair of opposing

end portions

102, 102 in the outer peripheral surface 110.

The workpiece rotating apparatus 70 shown in fig. 1 revolves the plurality of piston rings 100 around the revolution center axis CL1 so that each of the plurality of piston rings 100 sequentially passes through the reference line SL connecting the first emission surface 32 and the second emission surface 42. During the revolution of the plurality of piston rings 100, the workpiece rotating device 70 supports each of the plurality of piston rings 100 as follows: as shown in fig. 2, a specific region of the outer peripheral surface 110 of each of the plurality of piston rings 100, that is, a region where the coating film 90 (see fig. 2) thicker than the region other than the specific region is to be formed, that is, a region corresponding to each of the pair of opposite end portions 102, is always directed in the Y direction, that is, a side (upper side of the paper surface of fig. 1; hereinafter referred to as "first target side") where the first emission surface 32 of the first target 30 is present along the target facing direction (vertical direction of the paper surface of fig. 1) which is a direction in which the first target 30 and the second target 40 face each other. That is, the workpiece rotating device 70 supports each of the plurality of piston rings 100 so that each of the pair of

opposite end portions

102, 102 of the outer peripheral surface 110 of the piston ring 100 faces the first target side (the side where the first emission surface 32 is present; the upper side of the paper surface in fig. 1) in the Y direction, which is a direction intersecting the boundary line BL (the direction perpendicular to the example shown in fig. 1), when viewed from above the chamber 20 (that is, when viewed from the direction in which the revolution center axis CL1 extends). In short, each of the pair of

opposed end portions

102, 102 of the outer peripheral surface 110 of the piston ring 100 is oriented in a specific radial direction selected from the radial directions of the revolution table 74.

The state in which the outer peripheral surfaces of the pair of

opposite end portions

102, 102 face the first target side in the target facing direction, i.e., the Y direction, is a state in which the pair of

opposite end portions

102, 102 of the piston ring 100 are positioned on the first target side in the target facing direction, i.e., the Y direction, with respect to the center of the piston ring 100 (for example, the center in the case where the piston ring 100 is in a complete annular shape). In this state, it is more preferable that the pair of

opposite end portions

102 and 102 exist at a position where a straight line extending in the Y direction passes between the pair of

opposite end portions

102 and 102, for example, passing through the center of the piston ring 100.

The workpiece rotating device 70 includes a rotary table 72 and a drive source, not shown. The rotary table 72 is disposed so as to be rotatable about the revolution center axis CL1, and supports the plurality of piston rings 100 so that each of the plurality of piston rings 100 revolves around the revolution center axis CL1 in association with the rotation. The revolution center axis CL1 extends in the Z direction at a position between the first target 30 and the second target 40.

The rotary table 72 includes the revolving table 74 and a plurality of self-revolving tables 76. The revolution table 74 is disposed so as to be rotatable about the revolution center axis CL1 extending in the Z direction in a revolution direction indicated by an arrow AR1 in fig. 1. The plurality of self-turning tables 76 are arranged so as to be aligned in the circumferential direction of the revolution table 74, and the plurality of self-turning tables 76 support the piston rings 100 thereon, respectively, and rotate in the rotation direction indicated by an arrow AR2 in fig. 1 about the rotation center axis CL2 in the Z direction passing through the center of the self-turning table 76 with respect to the revolution table 74.

The revolution table 74 is supplied with a driving force from the driving source and rotates around the revolution center axis CL 1. The revolution center axis CL1 extends in the Z direction, which is the height direction of the chamber 20, and passes through the center of the revolution table 74 when viewed in the height direction of the chamber 20. The revolution table 74 has a circular plate shape. The revolution table 74 is disposed between the first emission surface 32 and the second emission surface 42.

The plurality of revolving tables 76 each revolve around the revolution center axis CL1 as the revolving table 74 revolves around the revolution center axis CL2 while rotating around the rotation center axis CL2 while supporting the piston ring 100 on the revolving table 76. That is, the rotation center axis CL2 is a rotation center axis set for each of the plurality of rotation tables 76, and the revolution center axis CL1 is a rotation center axis of the revolution table 74 and is also a revolution center axis of each of the plurality of rotation tables 76. The rotation center axis CL2 set for each of the plurality of self-turn tables 76 from the turn table extends in the Z direction, which is the height direction of the chamber 20, and passes through the center of the self-turn table 76 when viewed from the height direction of the chamber 20. Therefore, the rotation center axis CL2 is parallel to the revolution center axis CL 1.

A rotational driving force is applied to each of the plurality of self-rotating tables 76 in accordance with the rotation of the revolution table 74, and each of the plurality of self-rotating tables 76 rotates about the rotation center axis CL2 while revolving around the revolution center axis CL1 by the rotational driving force. This makes it possible to revolve the plurality of piston rings 100 on the plurality of self-turning tables 76 while keeping the postures of the facing

end portions

102, 102 of the piston rings 100 facing the first target material side at all times in accordance with the revolution of the revolution table 74.

A work handling mechanism as a mechanism for realizing the operation of the plurality of piston rings 100 will be described with reference to fig. 3 and 4.

The work handling mechanism has a plurality of guided members 77 and guide members 78 as shown in fig. 4. The plurality of guided members 77 are provided on each of the plurality of self-rotating tables 76, and the guide member 78 is disposed so as to collectively guide each of the plurality of guided members 77.

Each of the plurality of guided members 77 has a rotation shaft 771, a coupling piece 773, and a guided projection 772. The rotation shaft 771 extends in the Z direction, and is connected to a central portion of the self-turntable 76 so as to rotate integrally with the self-turntable 76, and is supported by the revolution table 74. The rotary shaft 771 is inserted into a through hole 741 formed to penetrate the revolution table 74 in the thickness direction, i.e., the Z direction, and has an upper side coupling portion coupled to the self table 76 on the upper side of the revolution table 74 and a lower side protruding portion protruding downward from the revolution table 74. The connecting piece 773 extends from the lower protruding portion of the rotary shaft 771 in the radial direction of rotation of the self-turn table 76 (in the horizontal direction in this embodiment). The connecting piece 773 is located on the back side of the revolution table 74, that is, on the opposite side (lower side in this embodiment) of the self-turn table 76 with the revolution table 74 therebetween in the Z direction which is the thickness direction of the revolution table 74. The guided projection 772 projects downward from a distal end portion, which is an end portion on the opposite side of the rotary shaft 771, of both end portions of the connecting piece 773. That is, the guided projection 772 extends parallel to the rotation axis 771 and toward the opposite side of the revolution table 74.

The guide member 78 is fixed to the bottom wall of the chamber 20. The guide member 78 is formed with a guide groove 781 engageable with the guided projection 772 of the plurality of guided members 77. The guide groove 781 is opened upward, and the guided projection 772 is embedded in the guide groove 781. As shown in fig. 3, the guide groove 781 is annular and has a diameter substantially equal to the diameter of the revolution orbit circle C1 of the rotation table 76, and the center thereof is offset from the center of the revolution orbit circle C1 in the direction (in the X direction) in which the boundary line BL extends when viewed from the direction (in the Z direction) in which the revolution central axis CL1 extends. The revolution orbit circle C1 is a trajectory drawn by the center of the rotation table 76 (the rotation center axis CL2) along with the revolution of the rotation table 76. The diameter of the guide groove 781 is the diameter of a guide base circle that is a circle passing through the center of the guide groove 781 in the width direction.

Each of the plurality of rotation tables 76 revolves around the revolution center axis CL1 in accordance with the rotation of the revolution table 74 around the revolution center axis CL1 while being supported by the revolution table 74 so as to be rotatable around the rotation center axis CL2 corresponding to the center axis of the rotation shaft 771 in a state where the rotation shaft 771 is inserted through the through-hole 741. At this time, the guided projection 772 coupled to the rotary shaft 771 by the coupling piece 773 is moved along the guide groove 781, that is, guided along the guide base circle, whereby the distal end portion (the end portion coupled to the guided projection 772) of the coupling piece 773 can be maintained in a state of being directed toward one side (the left direction in fig. 4) in the X direction regardless of the revolution of the plurality of turntables 76. This makes it possible to rotate each of the plurality of self-turn tables 76 about the rotation center axis CL2 in association with the revolution of the plurality of self-turn tables 76 about the revolution center axis CL1, and thereby maintain the state in which the pair of

opposed end portions

102, 102 of the plurality of piston rings 100 are each directed toward the first target side (upper side in fig. 1) in the Y direction, which is the target opposed direction, during the revolution of the plurality of self-turn tables 76. That is, each of the plurality of self-turn tables 76 rotates about the respective rotation center axis CL2 with respect to the revolution table 74 in accordance with the revolution of the revolution table 74 about the revolution center axis CL2, whereby the pair of

opposed end portions

102, 102 of the plurality of piston rings 100 supported by each of the plurality of self-turn tables 76 can be maintained in a state of always facing the first target material side.

In the example shown in fig. 3, the facing ends 102, 102 of the plurality of piston rings 100 are located on the first target side than the guided projection 772. However, the positional relationship between the facing ends 102, 102 and the guided projection 772 is not limited. The relative position of the opposite ends 102 of the guided projection 772 can be appropriately changed according to the positions of the first target 30 and the second target 40.

The plurality of self-rotating tables 76 are arranged so as to be aligned in the circumferential direction of the revolution table 74, that is, the rotation direction of the revolution table 74. The plurality of self-turn tables 76 each have a circular plate shape. The plurality of self-turn tables 76 are arranged between the first emission surface 32 and the second emission surface 42.

The plurality of self-turning tables 76 each have an upward workpiece mounting surface on which each of the plurality of piston rings 100 is mounted. A single piston ring 100 may be placed on the workpiece placement surface, or a plurality of piston rings 100 stacked in the Z direction parallel to the rotation center axis CL2, which is the thickness direction of the self-turn table 76, may be placed on the workpiece placement surface.

Each of the plurality of free-wheeling tables 76 is provided with a workpiece holding member for holding the piston ring 100 placed on the free-wheeling table 76. The work holding member has a strut 762 and a rib 763. The support 762 extends upward from the workpiece mounting surface along the revolution center axis CL2, and supports the piston ring 100 in a state of being inserted inside the piston ring 100. The rib 763 is a positioning member for determining a position of the pair of

opposite end portions

102 and 102 with respect to the rotation table 76 in the rotation direction of the rotation table 76. The rib 763 protrudes from a specific position in the circumferential direction of the outer circumferential surface of the strut 762 in the radial direction of rotation of the self-turn table 76, and extends in the vertical direction (the Z direction). The rib 763 is interposed between the pair of

opposite end portions

102, 102 of the piston ring 100 in a state where the strut 762 is positioned inside the piston ring 100, so that the piston ring 100 is positioned relative to the rotation table 76 in such a manner that the pair of

opposite end portions

102, 102 are respectively maintained by the rotation of the rotation table 76 in a state where the pair of

opposite end portions

102, 102 are directed toward the first target side (upper side of the paper surface of fig. 1) in the target facing direction (vertical direction of the paper surface of fig. 1).

The control device 80 controls the driving of the first arc power supply 50 and the second arc power supply 60 such that the first coating portion 92 formed by the particles flying from the first emission surface 32 of the first target 30 in the coating 90 formed on the outer peripheral surface 110 of the piston ring 100 is thicker than the second coating portion 94 formed by the particles flying from the second emission surface 42 of the second target 40. More specifically, the controller 80 causes the arc current flowing from the first arc power supply 50 to the first target 30 to be larger than the arc current flowing from the second arc power supply 60 to the second target 40 so that the total amount of particles that fly from the first emission surface 32 and adhere to the outer circumferential surfaces of the piston rings 100 is larger than the total amount of particles that fly from the second emission surface 42 and adhere to the outer circumferential surfaces of the piston rings 100. This makes it possible to make a portion of the coating film 90 formed on the outer peripheral surface 110 that covers each of the outer peripheral surfaces of the pair of opposing end portions 102, 102 (that is, at least a portion of the first coating portion 92) have a thickness greater than that of the second coating portion 94.

As long as the thickness of the first film portion 92 can be made larger than the thickness of the second film portion 94, the first power supply operation period during which the first arc power supply 50 applies the arc current to the first target 30 may be the same as or different from the second power supply operation period during which the second arc power supply 60 applies the arc current to the second target 40.

Specifically, the control device 80 includes a first current control unit 82 and a second current control unit 84 as shown in fig. 1. The first current control unit 82 controls the current of the first arc power supply 50. The second current control unit 84 controls the current of the second arc power supply 60.

A film formation method using such a film formation apparatus 10 will be described with reference to fig. 5. Arc Ion Plating (AIP) is used in the film formation method.

The film forming method includes a preparation step S11, a work arrangement step S12, and a film forming step S13. These steps are explained below.

The preparation step S11 is a step of preparing the film formation apparatus 10.

The workpiece arranging step S12 is a step of arranging the plurality of piston rings 100 on the workpiece mounting surfaces of the plurality of free turntables 76. As shown in fig. 1, the piston ring 100 supported by each of the plurality of self-turning tables 76 is positioned in the circumferential direction by the rib 763 on the self-turning table 76 so that the pair of

opposed end portions

102 and 102 of the piston ring 100 are directed toward the first target side (upper side of the paper surface of fig. 1) in the direction in which the first target 30 and the second target 40 are opposed to each other, that is, the target opposed direction (vertical direction of the paper surface of fig. 1).

The film forming step S13 is a step of forming the coating film 90 on each outer peripheral surface 110 of the plurality of piston rings 100 as shown in fig. 2. The coating film 90 is formed in a shape that is such that the coating film is formed while each of the plurality of piston rings 100 revolves around the revolution center axis CL1, and regardless of the revolution, the coating film is formed while rotating around the rotation center axis CL2 so that the pair of

opposed end portions

102, 102 of each piston ring 100 always face the first target side in the target opposed direction. The film forming step S13 is performed in an atmosphere in which the pressure in the chamber 20 is reduced.

A bias potential is applied to each of the plurality of piston rings 100 by the workpiece rotating device 70 from a bias potential applying device not shown. Thereby, in a state where a bias potential is applied to each of the plurality of piston rings 100, the first arc power supply 50 flows an arc current to the first target 30, and the second arc power supply 60 flows an arc current to the second target 40. Accordingly, arc discharge occurs between the first target 30 and the inner surface of the chamber 20, and the material of the first target 30 evaporates from the first emission surface 32 of the first target 30 and flies high-energy particles. The particles collide with the outer peripheral surface 110 of the piston ring 100. Further, arc discharge occurs between the second target 40 and the inner surface of the chamber 20, and the material of the second target 40 evaporates from the second emission surface 42 of the second target 40 and flies high-energy particles. The particles also collide with the outer peripheral surface 110 of the piston ring 100. Thereby, the coating film 90 shown in fig. 2 is formed on the outer peripheral surface 110 of the piston ring 100. Therefore, the coating film 90 includes the first coating portion 92 formed by the particles from the first target 30 and the second coating portion 94 formed by the particles from the second target 40.

In the film forming step S13, each of the plurality of piston rings 100 alternately passes in front of the first output surface 32 and in front of the second output surface 42 in a state where the pair of

opposed end portions

102, 102 of the piston ring 100 face toward the first target in the target facing direction. Thereby, the coating film 90 shown in fig. 2 is formed on the entire outer peripheral surface 110 of each of the plurality of piston rings 100.

The control device 80 controls the operations of the first arc power supply 50 and the second arc power supply 60 so that the arc current applied to the first target 30 by the first arc power supply 50 is larger than the arc current applied to the second target 40 by the second arc power supply 60. This makes it possible to make the thickness of the first film portion 92 formed per unit time by the particles from the first target 30 larger than the thickness of the second film portion 94 formed per unit time by the particles from the second target 40, as shown in fig. 2. Therefore, the first coating portion 92 of the coating film 90 finally formed on the outer peripheral surface of the piston ring 100 is thicker than the second coating portion 94. The first coating portion 92 covers the outer peripheral surface of each of the pair of opposing

end portions

102, 102 in the outer peripheral surface 110 of the piston ring 100, and the second coating portion 94 covers the outer peripheral surface of a portion of the outer peripheral surface 110 that is located on the opposite side of the pair of opposing

end portions

102, 102 with the center of the piston ring 100 in the radial direction of the piston ring 100.

The period during which the arc current applied to the first target 30 by the first arc power supply 50 is made larger than the arc current applied to the second target 40 by the second arc power supply 60 (hereinafter referred to as "current difference application period") may be equal to or a part of the total film period, which is a period for forming the coating film 90. The current difference application period is a part of the total film formation period, and for example, the total film formation period includes a plurality of current difference application periods. In short, the length of the current difference application period may be arbitrarily set within a range that satisfies a condition that the thickness of the coating film formed per unit time by the particles from the first target 30 is larger than the thickness of the coating film formed per unit time by the particles from the second target 40.

In the film forming apparatus 10 and the film forming method using the film forming apparatus 10 described above, the thickness of the first film portion 92 formed by the particles flying out from the first emission surface 32 in the film 90 can be made larger than the thickness of the second film portion 94 formed by the particles flying out from the second emission surface 42 by the drive control of the first arc power source 50 and the second arc power source 60 without adjusting the revolution speed of the piston ring 100 as in the conventional art. The control, that is, the power supply control for locally thickening the coating film 90 formed on the outer peripheral surface 110 of the piston ring 100, is more reproducible than the control of the revolution speed. This makes it possible to accurately control the film thickness distribution in the circumferential direction of the coating film 90 formed on the outer peripheral surface 110.

In the film forming apparatus 10, the turntable 72 of the workpiece rotating apparatus 70 is disposed so as to be rotatable around the revolution center axis CL1 extending in the Z direction between the first target 30 and the second target 40, and supports the plurality of piston rings 100 so that each of the plurality of piston rings 100 revolves around the revolution center axis CL1 in accordance with the rotation. That is, the film formation method using the film formation apparatus 10 includes a step of revolving each of the plurality of piston rings 100 around the revolution center axis CL1 extending in the Z direction between the first target 30 and the second target 40, that is, a step of moving each of the plurality of piston rings 100 on a predetermined revolution trajectory circle located between the first target 30 and the second target 40. In other words, the moving range of the plurality of piston rings 100 is defined on the revolution trajectory circle. This can reduce the space required for moving the plurality of piston rings 100 for the purpose of the film formation.

In the film forming apparatus 10 and the film forming method using the film forming apparatus 10, the formation of the second purslane film portion 94, which is the formation of the film 90 by the second target material 40, may be performed after the formation of the first film portion 92, which is the formation of the film 90 by the first target material 30, is completed. Alternatively, the formation of the second film portion 94 may begin during the formation of the first film portion 92, i.e., before the formation is complete.

[ modification 1 of embodiment ]

The first target 30 and the second target 40 of the film formation apparatus 10 according to the above-described embodiment are formed of the same material, but the present invention also includes modification 1 in which the first target 30 and the second target 40 are formed of different materials.

In modification 1, the properties of the first coating portion 92 formed by the particles flying off from the first emission surface 32 of the first target 30 and the properties of the second coating portion 94 formed by the particles flying off from the second emission surface 42 of the second target 40 in the coating 90 formed on the outer peripheral surface of the piston ring 100 may be different from each other. For example, by forming the first target 30 of a material harder than the material constituting the second target 40, the hardness of the first coating portion 92 can be made higher than the hardness of the second coating portion 94. This can suppress wear of the portion of the coating film 90 that covers the outer peripheral surfaces of the pair of

opposite end portions

102, 102 of the piston ring 100 (i.e., the first coating portion 92).

[ modification 2 of embodiment ]

The controller 80 of the film forming apparatus 10 according to the embodiment makes the arc current applied to the first target 30 by the first arc power supply 50 larger than the arc current applied to the second target 40 by the second arc power supply 60 so that the first film portion 92 is thicker than the second film portion 94, but the method for making the first film portion 92 thicker than the second film portion 94 is not limited to this. The present invention further includes modification 2 in which the first power supply operation period, which is a period in which the first arc power supply 50 applies the arc current to the first target 30, is longer than the second power supply operation period, which is a period in which the second arc power supply 60 applies the arc current to the second target 40. According to modification 2, the entire period of forming the coating film 90, that is, the entire film forming period, includes a period of forming the coating film 90 only by the first target 30. This makes it possible to make the first coated portion 92 formed by the particles that fly out from the first emission surfaces 32 of the first target 30 thicker than the second coated portion 94 formed by the particles that fly out from the second emission surfaces 42 of the second target 40.

When the first power supply operation period, i.e., the film formation period using the first target 30, is longer than the second power supply operation period, i.e., the film formation period using the second target 40, it is preferable that at least a part of the second power supply operation period overlaps with a part of the first power supply operation period. That is, it is preferable that a period in which the first target 30 and the second target 40 are simultaneously used exist in the entire period for forming the coating film 90, that is, the entire film period. This can shorten the assembly film period.

The second power supply operation period may be started after the first power supply operation period is ended. Alternatively, the first power supply operation period may be started after the second power supply operation period is ended.

The first power supply operation period may be present in the assembly film period. For example, the first power supply operation period and the second power supply operation period may be started simultaneously, and the coating film 90 may be formed only by the first target 30 at the end of the assembly film period. That is, only the first power supply operation period exists at the end of the assembly film period. Alternatively, the first power supply operation period may be started before the second power supply operation period, so that the first film assembly period may be a period during which only the first target 30 is used to form the coating film 90. That is, only the first power supply operation period may exist initially during assembly of the film. Alternatively, the first power supply operation period and the second power supply operation period may be started and ended simultaneously, but the second power supply operation period may be interrupted halfway, that is, a period during which the coating film 90 is formed only by the first target 30 exists halfway in the integrated film period, whereby the first power supply operation period can be made longer than the second power supply operation period.

In the film forming apparatus and the film forming method using the film forming apparatus according to modification 1 or 2, the film thickness distribution of the coating film 90 formed on the outer peripheral surface of the piston ring 100 in the circumferential direction can be accurately controlled by the drive control of the first arc power supply 50 and the second arc power supply 60, as in the above-described embodiment.

That is, as long as the first coating portion 92 is thicker than the second coating portion 94, the arc current applied to the first target 30 by the first arc power supply 50 may be the same as or different from the arc current applied to the second target 40 by the second arc power supply 60.

[ modification 3 of embodiment ]

The film formation apparatus 10 shown in fig. 1 includes a single first target 30, but the film formation apparatus 10 according to modification 3 shown in fig. 6 includes two first targets 30. The two first targets 30 are arranged symmetrically with respect to the reference line SL. The two first targets 30 are connected to two first arc power supplies 50 independent of each other, respectively. The two first arc power supplies 50 are connected to a common first current control unit 82, and the first current control unit 82 controls the arc currents applied to the two first targets 30 by the two first arc power supplies 50, respectively.

[ modification 4 of embodiment ]

The film formation apparatus 10 shown in fig. 1 includes a single second target 40, but the film formation apparatus 10 according to modification 4 shown in fig. 7 includes two second targets 40. The two second targets 40 are arranged symmetrically with respect to the reference line SL. The two second targets 40 are connected to two second arc power supplies 60 independent of each other, respectively. The two second arc power supplies 60 are connected to a common second current control unit 84, and the second current control unit 84 controls the arc currents applied to the two second targets 40 by the two second arc power supplies 60, respectively.

The embodiments and their modifications described above are merely examples. The present invention is not limited to the embodiments described above.

In the above embodiment, the electric energy applied to the evaporation source is the arc current applied to the target material as the AIP evaporation source, but the electric energy applied to the evaporation source is not limited to the arc current in the present invention. The electric energy applied to the evaporation source may be, for example, sputtering power supplied to the evaporation source for sputtering.

In the above embodiment, the workpiece to be formed into a film is a piston ring, but the workpiece according to the present invention is not limited to a piston ring. If a workpiece has an outer peripheral surface in which a specific region in which a coating film is to be formed thick is set, the film forming apparatus according to the present invention can form a film in which the coating film in the specific region is locally thickened. For example, the workpiece may be a tool used for cutting. In such a cutting tool, for example, a portion of the outer peripheral surface of the cutting tool that is in contact with a cutting target rotating at a high speed (i.e., a cutting surface) is set as a specific region in which a coating film is to be formed thick.

The film formation apparatus 10 according to the above-described embodiment includes the first target 30 and the second target 40, but the film formation apparatus according to the present invention may further include a target that assists film formation using the first and second targets.

As described above, a film forming apparatus and a film forming method capable of accurately controlling a film thickness distribution in a circumferential direction of a coating film formed on a side surface of a workpiece are provided.

In the film forming apparatus, the first coating portion can be made thicker than the second coating portion with high accuracy by controlling the electric energy applied to the first evaporation source and the second evaporation source. The thickness control of the coating film can be achieved by adjusting the rotation speed of the workpiece, but response delay is likely to occur in such mechanical operation control. In contrast, in the control of the electric energy applied to each of the first evaporation source and the second evaporation source, a response delay is less likely to occur. This makes it possible to control the coating film formed on the side surface of the workpiece to be locally thick with good reproducibility. As a result, the film thickness distribution of the coating film formed on the side surface of the workpiece in the circumferential direction can be accurately controlled.

The control device preferably makes a total amount of electric energy applied to the first evaporation source larger than a total amount of electric energy applied to the second evaporation source during the formation of the coating film.

The control device, for example, makes the amount of electric energy applied to the first evaporation source per unit time larger than the amount of electric energy applied to the second evaporation source per unit time.

The control device may be configured to make a first power supply operation period, which is a period in which the first power supply supplies power to the first evaporation source, longer than a second power supply operation period, which is a period in which the second power supply supplies power to the second evaporation source, so that a total amount of power supplied to the first evaporation source is larger than a total amount of power supplied to the second evaporation source during the period in which the coating film is formed.

The control device preferably controls the start and end of the first power supply operation period and the second power supply operation period so that at least a part of the second power supply operation period overlaps with a part of the first power supply operation period.

Such partial overlapping of the first and second power supply operation periods can shorten the total film formation period required for forming the entire coating film, as compared with the case where one of the first and second power supply operation periods is started after the other one is ended.

The workpiece rotating apparatus preferably further comprises: a revolution table capable of revolving around the revolution central axis; at least one rotation table disposed in a radial direction of the revolution table apart from the revolution center axis in the radial direction of the revolution table, and disposed to be rotatable about a rotation center axis parallel to the revolution center axis with respect to the revolution table; a guide member having an annular guide groove formed at a position shifted from the orbital circle in a direction in which the boundary line extends, when viewed in a direction in which the revolution central axis extends; and a guided member that is coupled to the rotation table so as to rotate around the rotation center axis integrally with the rotation table, and that engages with the guide groove so as to move in the guide groove along with the revolution of the revolution table and maintain the posture of the specific region of the side surface of the workpiece facing the specific radial direction.

In this aspect, by revolving the workpiece around the revolution central axis while maintaining the posture in which the specific region of the side surface of the workpiece faces the specific radial direction, it is possible to perform film formation in which the film formed on the side surface of the workpiece is locally thickened in a small space on at least one workpiece.

The second evaporation source may be formed using a material different from a material constituting the first evaporation source.

This makes it possible to make the characteristics of the first coating portion formed by the particles flying off from the emission surface of the first evaporation source and the characteristics of the second coating portion formed by the particles flying off from the emission surface of the second evaporation source different from each other.

Also provided is a film forming method for forming a film on a film formation surface of a workpiece. The film forming method includes the following steps: a work arranging step of arranging the work so that a specific region of the film formation surface of the work, in which the coating film is to be formed thicker than other regions, faces a specific direction, the specific direction being a direction intersecting a boundary line defining a boundary between a first arrangement region and a second arrangement region, the first arrangement region being a region in which at least one first evaporation source having an emission surface on which particles as a material for forming the coating film are emitted into the first arrangement region is arranged, the second region being a region in which at least one second evaporation source having an emission surface on which particles as a material for forming the coating film are emitted into the second arrangement region is arranged: and a film forming step of forming the coating film on the film formation surface of the workpiece by causing the total amount of electric energy applied to the first evaporation source to cause the particles for forming the coating film to fly out from the emission surface of the first evaporation source to be larger than the total amount of electric energy applied to the second evaporation source to cause the particles for forming the coating film to fly out from the emission surface of the second evaporation source and causing the specific region in the film formation surface of the workpiece to face the specific direction so that a first coating portion, which is a portion of the coating film formed by the particles flying out from the emission surface of the first evaporation source, is thicker than a second coating portion, which is a portion of the coating film formed by the particles flying out from the emission surface of the second evaporation source.

In the film forming method, the first coating portion can be made thicker than the second coating portion with high accuracy by controlling the electric energy applied to the first evaporation source and the second evaporation source, respectively. The thickness control of the coating film can be achieved by adjusting the rotation speed of the workpiece, but response delay is likely to occur in such mechanical operation control. In contrast, in the control of the electric energy applied to each of the first evaporation source and the second evaporation source, a response delay is less likely to occur, and this makes it possible to perform control for locally thickening the coating film formed on the film formation surface of the workpiece with good reproducibility. As a result, the film thickness distribution of the coating film formed on the side surface of the workpiece in the circumferential direction can be accurately controlled.

The film forming step includes, for example, a step of increasing the amount of electric energy applied to the first evaporation source per unit time to be larger than the amount of electric energy applied to the second evaporation source per unit time.

The film forming step may further include a step of making a first power source operation period, which is a period in which electric energy is applied to the first evaporation source, longer than a second power source operation period, which is a period in which electric energy is applied to the second evaporation source.

The film forming step preferably includes a step of making the first power supply operation period longer than the second power supply operation period so that at least a part of the second power supply operation period overlaps with a part of the first power supply operation period.

The overlap of the first and second power supply operation periods can shorten the total film formation period required for forming the entire coating film, as compared with the case where one of the first power supply operation period and the second power supply operation period is started after the other is ended.

The film forming step preferably includes the steps of: when forming the coating film on the film formation surface of the workpiece, the workpiece is rotated about a rotation central axis parallel to the rotation central axis while being revolved about a revolution central axis extending in a direction parallel to an emission surface of the first evaporation source so that the specific region of the film formation surface of the workpiece faces the specific direction.

In such a film forming step, the workpiece is revolved around the revolution central axis while maintaining the posture in which the specific region of the film formation surface of the workpiece faces a specific radial direction, whereby the film forming process for locally thickening the coating film formed on the film formation surface of the workpiece can be performed on the workpiece in a small space.

Claims

1. A film forming apparatus for forming a film on a side surface of a workpiece facing a direction perpendicular to a predetermined revolution central axis while revolving the workpiece around the revolution central axis, the film forming apparatus comprising:

at least one first evaporation source having an emission surface from which particles as a material for forming the coating film are flown, the first evaporation source being arranged symmetrically with respect to a reference line passing through the revolution central axis and perpendicular to a boundary line extending in a radial direction of an orbital circle drawn by the workpiece revolving around the revolution central axis when viewed in a direction in which the revolution central axis extends;

at least one second evaporation source located on the opposite side of the first evaporation source with respect to the boundary line and symmetrically arranged with respect to the reference line;

a first power supply that applies, to the first evaporation source, electric energy for flying particles for forming the coating film from an emission surface of the first evaporation source;

a second power supply that applies, to the second evaporation source, electric energy for flying particles for forming the coating film from an emission surface of the second evaporation source;

a workpiece rotating device that revolves the workpiece around the revolution central axis while supporting the workpiece in such a manner that a specific region of a side surface of the workpiece, on which the coating film is to be formed thicker than other regions, faces a posture in a specific radial direction selected from the radial directions of the orbital circle; and the number of the first and second groups,

and a control device that controls the electric energy applied from the first power supply to the first evaporation source and the electric energy applied from the second power supply to the second evaporation source so that a first coating portion, which is a portion formed by the particles flying off from the emission surface of the first evaporation source, in the coating film formed on the workpiece is thicker than a second coating portion, which is a portion formed by the particles flying off from the emission surface of the second evaporation source.

2. The film forming apparatus according to claim 1,

the control device makes the total amount of electric energy applied to the first evaporation source larger than the total amount of electric energy applied to the second evaporation source during the formation of the coating film.

3. The film forming apparatus according to claim 2,

the control device makes the amount of electric energy applied to the first evaporation source per unit time larger than the amount of electric energy applied to the second evaporation source per unit time.

4. The film forming apparatus according to claim 2,

the control device makes a first power supply operation period, which is a period in which the first power supply supplies power to the first evaporation source, longer than a second power supply operation period, which is a period in which the second power supply supplies power to the second evaporation source, so that the total amount of power supplied to the first evaporation source is larger than the total amount of power supplied to the second evaporation source during the period in which the coating film is formed.

5. The film forming apparatus according to claim 4,

the control device controls the start and end of the first power supply operation period and the second power supply operation period so that at least a part of the second power supply operation period overlaps with a part of the first power supply operation period.

6. The film forming apparatus according to any one of claims 1 to 5, wherein the workpiece rotating means further comprises;

a revolution table capable of revolving around the revolution central axis;

at least one rotation table disposed in a radial direction of the revolution table apart from the revolution center axis in the radial direction of the revolution table, and disposed to be rotatable about a rotation center axis parallel to the revolution center axis with respect to the revolution table;

a guide member having an annular guide groove formed at a position shifted from the orbital circle in a direction in which the boundary line extends, when viewed in a direction in which the revolution central axis extends; and the number of the first and second groups,

and a guided member that is coupled to the self-rotation table so as to rotate around the self-rotation central axis integrally with the self-rotation table, and that engages with the guide groove so as to move in the guide groove along with the revolution of the revolution table and maintain the posture of the specific region of the side surface of the workpiece facing the specific radial direction.

7. The film forming apparatus according to any one of claims 1 to 6,

the second evaporation source is formed using a material different from a material constituting the first evaporation source.

8. A film forming method for forming a film on a film formation surface of a workpiece, comprising:

a work arranging step of arranging the work so that a specific region of the film formation surface of the work, in which the coating film is to be formed thicker than other regions, faces a specific direction, the specific direction being a direction intersecting a boundary line defining a boundary between a first arrangement region and a second arrangement region, the first arrangement region being a region in which at least one first evaporation source having an emission surface on which particles as a material for forming the coating film are emitted into the first arrangement region is arranged, the second region being a region in which at least one second evaporation source having an emission surface on which particles as a material for forming the coating film are emitted into the second arrangement region is arranged; and the number of the first and second groups,

and a film forming step of forming the coating film on the film formation surface of the workpiece by causing the total amount of electric energy applied to the first evaporation source to cause the particles for forming the coating film to fly out from the emission surface of the first evaporation source to be larger than the total amount of electric energy applied to the second evaporation source to cause the particles for forming the coating film to fly out from the emission surface of the second evaporation source and causing the specific region on the film formation surface of the workpiece to face the specific direction so that a first coating portion, which is a portion of the coating film formed by the particles flying out from the emission surface of the first evaporation source, is thicker than a second coating portion, which is a portion of the coating film formed by the particles flying out from the emission surface of the second evaporation source.

9. The film forming method according to claim 8,

the film formation step is performed such that the amount of electric energy applied to the first evaporation source per unit time is larger than the amount of electric energy applied to the second evaporation source per unit time.

10. The film forming method according to claim 8,

the film forming step is performed such that a first power supply operation period, which is a period in which electric energy is applied to the first evaporation source, is longer than a second power supply operation period, which is a period in which electric energy is applied to the second evaporation source.

11. The film forming method according to claim 10,

the film forming step is configured to make the first power supply operation period longer than the second power supply operation period so that at least a part of the second power supply operation period overlaps with a part of the first power supply operation period.

12. The film forming method according to any one of claims 8 to 11,

the film forming step includes the steps of: when forming the coating film on the film formation surface of the workpiece, the workpiece is rotated about a rotation central axis parallel to the rotation central axis while being revolved about a revolution central axis extending in a direction parallel to an emission surface of the first evaporation source so that the specific region of the film formation surface of the workpiece faces the specific direction.