Film formation method and film formation apparatus

Abstract

To provide a film formation method and a film formation apparatus that improve the in-plane uniformity of the characteristics of a film formed by magnetron sputtering while suppressing an increase in the size of the apparatus.SOLUTION: A film formation method uses a film formation apparatus to form a film on a substrate by sputtering of a target. During the film formation step, a magnet unit oscillates in a predetermined direction along the target held by a target holder, serial communication is performed with the power supply for switching of the power supplied to the target holder, such that the power supplied to the target holder increases when the magnet unit faces an end of the target, while the power decreases when the magnet unit faces the center of the target. The serial communication monitoring stops at least from a predetermined time before the time point when the magnet unit reaches the power switching position until the serial communication for switching the power is completed.SELECTED DRAWING: Figure 6

Description

Technical Field

[0001] The present disclosure relates to a film forming method and a film forming apparatus.

Background Art

[0002] Patent Document 1 discloses a magnetron sputtering method in which a magnet is moved along the back surface of a plate-shaped target provided on a cathode, and a constant discharge power is applied to the cathode while generating a leakage magnetic field for magnetron discharge that moves on the surface of the target by the magnet to sputter the target. In this method, the magnet is moved in a direction perpendicular to the surface of the target in accordance with an increase or decrease in the voltage of the magnetron discharge during its movement to maintain the discharge voltage substantially constant.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The technology according to the present disclosure improves the in-plane uniformity of the characteristics of a film formed by magnetron sputtering while suppressing an increase in the size of the apparatus.

Means for Solving the Problems

[0005] One aspect of the present disclosure is a film forming method for forming a film on a substrate by sputtering a target using a film forming apparatus. The film forming apparatus includes a substrate support unit that supports the substrate, a target holder that holds the target so that the target faces the substrate support unit and is supplied with power from a power source, and a magnet unit provided on the side of the holder opposite to the substrate support unit and having a magnet. The method includes a step of forming a film on the substrate by magnetron sputtering of the target, and a step of performing serial communication monitoring to repeatedly acquire information regarding the power from the power source by serial communication during the film forming step. During the film forming step, the magnet unit is swung in a predetermined direction along the target held by the target holder, and when the magnet unit faces an end portion of the target in the predetermined direction, the power supplied to the holder increases, and when the magnet unit faces a central portion of the target in the predetermined direction, the power supplied to the target holder decreases. When the magnet unit reaches a predetermined power switching position during the swing, serial communication is performed with the power source regarding switching of the power supplied to the target holder, and at least from a time point a predetermined time before the magnet unit reaches the power switching position until serial communication regarding switching of the power supplied to the target holder is completed, the serial communication monitoring is interrupted.

Effect of the Invention

[0006] According to the present disclosure, it is possible to improve the in-plane uniformity of the characteristics of the film formed by magnetron sputtering while suppressing the increase in size of the apparatus.

Brief Description of the Drawings

[0007]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Embodiments for Carrying Out the Invention

[0008] In the manufacturing process of semiconductor devices and the like, a film-forming process for forming a desired film such as an alloy film is performed on a substrate such as a semiconductor wafer (hereinafter referred to as "wafer"). The film-forming process is performed, for example, by sputtering of a target.

[0009] In a film-forming apparatus for forming a film on a substrate by sputtering of a target, for example, a substrate support portion for supporting the substrate and a target holder for holding the target so that the target faces the substrate support portion and to which power is supplied are provided.

[0010] In addition, when magnetron sputtering is employed as sputtering, in order to effectively utilize the entire target, a magnet smaller than the target may be provided on the side opposite to the substrate support portion of the target holder and swung in a predetermined direction along the target. However, in such magnetron sputtering, the characteristics of the formed film (for example, the composition ratio and film thickness in an alloy film) may not be sufficiently uniform within the substrate plane. Further, as in Patent Document 1, if the magnet is movable not only in the direction along the target but also in the direction perpendicular to the surface of the target, the apparatus becomes large-sized.

[0011] Therefore, the technology according to the present disclosure improves the in-plane uniformity of the characteristics of the film formed by magnetron sputtering while suppressing the increase in size of the apparatus.

[0012] Hereinafter, the film forming method and film forming apparatus according to the present embodiment will be described with reference to the drawings. In the present specification, elements having substantially the same functional configuration are denoted by the same reference numerals, and redundant description is omitted.

[0013] <Film forming apparatus> FIG. 1 is a longitudinal sectional view showing an outline of the configuration of a film forming apparatus 1 according to the present embodiment. FIG. 2 is a perspective view of a magnet unit described later. FIG. 3 is a view for explaining the configuration around a cathode described later.

[0014] The film forming apparatus 1 in FIG. 1 forms a film on a wafer W as a substrate by sputtering a target 20. Specifically, an alloy film containing, for example, a plurality of elements is formed on the wafer W by magnetron sputtering of the target 20. Hereinafter, it is assumed that the film forming apparatus 1 forms an alloy film, that is, an IGZO film composed of indium (In), gallium (Ga), zinc (Zn), and oxygen (O).

[0015] The film forming apparatus 1 includes a processing container 10. The processing container 10 is configured to be depressurized and houses the wafer W. For example, it is formed of aluminum and is connected to the ground potential. An exhaust device 11 for depressurizing the space S in the processing container 10 is connected to the bottom of the processing container 10 via an APC valve 12. Further, a transfer inlet / outlet 13 for the wafer W is formed in the side wall of the processing container 10, and a gate valve 13a for opening and closing the transfer inlet / outlet 13 is provided at the transfer inlet / outlet 13.

[0016] A mounting table 14 as a substrate support part for supporting the wafer W is provided in the processing container 10. The wafer W is horizontally mounted on the mounting table 14. The mounting table 14 has a base part 14a and an electrostatic chuck 14b.

[0017] The base part 14a is formed in a disk shape using, for example, aluminum. A heater (not shown) for heating the wafer W may be provided in the base part 14a. Instead of the heater, a cooling mechanism may be provided, or both the heater and the cooling mechanism may be provided.

[0018] The electrostatic chuck 14b has, for example, a dielectric film and an electrode provided as an inner layer of the dielectric film, and is provided on the base part 14a. A DC power supply 15 is connected to the electrode of the electrostatic chuck 14b. The wafer W placed on the electrostatic chuck 14b is adsorbed and held by the electrostatic adsorption force generated by applying a DC voltage from the DC power supply 15 to the electrode. Hereinafter, the upper surface 14c of the electrostatic chuck 14b as a substrate adsorption surface is referred to as a wafer adsorption surface 14c.

[0019] Furthermore, the mounting table 14 is connected to a drive mechanism 16 as a rotation drive part. The drive mechanism 16 has, for example, a support shaft 16a and a drive part 16b. The support shaft 16a extends in the vertical direction so as to penetrate the bottom wall of the processing container 10. A sealing member SL1 is provided between the support shaft 16a and the bottom wall of the processing container 10. The sealing member SL1 is a member that seals the space between the bottom wall of the processing container 10 and the support shaft 16a so that the support shaft 16a can rotate and move up and down, and is, for example, a magnetic fluid seal. The upper end of the support shaft 16a is connected to the center of the lower surface of the mounting table 14, and the lower end is connected to the drive unit 16b.

[0020] The drive unit 16b has a drive source such as a motor, for example, and generates a driving force for rotating and moving the support shaft 16a up and down. With the driving force generated by the drive unit 16b, as the support shaft 16a rotates about its axis AX1, the mounting table 14 rotates about the axis AX1. Further, with the driving force generated by the drive unit 16b, as the support shaft 16a moves up and down, the mounting table 14 moves up and down. Note that the drive mechanism 16 (specifically, the drive unit 16b) is controlled by a control unit U1 described later.

[0021] Above the mounting table 14, a target holder 20a (hereinafter referred to as "holder 20a") formed of a conductive material that holds a target 20 that emits sputter particles is provided.

[0022] The holder 20a is attached to the ceiling portion of the processing container 10. A through-hole is formed at the attachment position of the holder 20a in the processing container 10. Further, an insulating member 20b is provided on the inner wall surface of the processing container 10 so as to surround the through-hole. Through this insulating member 20b, the holder 20a is attached to the processing container 10 so as to close the through-hole. The holder 20a holds the target 20 so that the target 20 is located inside the processing container 10 and faces the mounting table 14.

[0023] The target 20 is made of, for example, an alloy composed of In, Ga, Zn, and O, namely IGZO. Further, the target 20 is formed, for example, in a rectangular shape in plan view. In a state where the target 20 is held by the holder 20a, its longitudinal direction extends in the depth direction of the apparatus (Y direction in FIG. 1). Further, the length of the target 20 in the depth direction of the apparatus is, for example, 150 mm to 200 mm.

[0024] A power supply 21 is connected to the holder 20a. The power supply 21 supplies power to the holder 20a. The power supply 21 is, for example, a DC power supply. The power supply 21 is connected to the power control unit U2 via a serial communication cable 21a.

[0025] The power supply 21 and the power control unit U2 perform transmission and reception of information including data, commands, etc. by serial communication. For example, the power supply 21 transmits, by serial communication, the magnitude, current, voltage, etc. of the power output from the power supply 21 to the power control unit U2. On the other hand, the power control unit U2 transmits, by serial communication, a command for designating the magnitude of the power output from the power supply 21 to the power supply 21. The command for designating the magnitude of the power output from the power supply 21 is, for example, a command for designating the reference value of the power output from the power supply 21 (hereinafter referred to as "base power"), or a command for designating the ratio of the magnitude of the power actually output from the power supply 21 to the base power (hereinafter referred to as "output ratio"). Note that the above-mentioned base power and output ratio are input by an operator via an input unit included in the control unit U1 described later.

[0026] The power control unit U2 includes a processor and a memory, and a program including commands for controlling the power supply 21 is stored in the memory.

[0027] Also, a magnet unit 22 is provided at a position on the side opposite to the mounting table 14 of the holder 20a, that is, the back side, and outside the processing container 10. The magnet unit 22 forms a magnetic field that leaks to the front side of the target 20 held by the holder 20a. The magnet unit 22 is configured, for example, as shown in FIG. 2, by arranging a rectangular parallelepiped-shaped central magnet 102 and an outer peripheral magnet 103 having an annular shape in plan view on a flat yoke 101. The central magnet 102 is provided along the longitudinal direction of the yoke 101, and the outer peripheral magnet 103 is provided so as to surround the four sides of the central magnet 102 in plan view. Also, the central magnet 102 and the outer peripheral magnet 103 are magnetized in opposite directions to each other in a direction perpendicular to the surface of the yoke 101 on the central magnet 102 side.

[0028] The magnet unit 22 is formed smaller than the target 20. For example, the length in the depth direction of the apparatus (specifically, the length in the depth direction of the apparatus of the outer peripheral magnet 103) is about 1 / 3 of the target 20. This magnet unit 22 is connected to a moving mechanism 23. The moving mechanism 23 swings, that is, reciprocates, the magnet unit 22 in a predetermined direction along the target 20 held by the holder 20a. Specifically, the moving mechanism 23 swings, that is, reciprocates, the magnet unit 22 along the back surface of the holder 20a in the depth direction of the apparatus (the Y direction in FIGS. 1 and 3), which is the longitudinal direction of the target 20.

[0029] The moving mechanism 23 has, for example, a rail 23a extending along the depth direction of the apparatus (Y direction in FIGS. 1 and 3) and a driving unit 23b including a driving source such as a motor. Due to the driving force generated by the driving unit 23b, the magnet unit 22 moves along the rail 23a in the depth direction of the apparatus (Y direction in FIGS. 1 and 3). Specifically, due to the driving force generated by the driving unit 23b, the magnet unit 22 moves so as to reciprocate between a position facing one end of the target 20 in the depth direction of the apparatus (negative side end in the Y direction in FIGS. 1 and 3) and a position facing the other end (positive side end in the Y direction in FIGS. 1 and 3). Thereby, it is possible to prevent the target 20 from being locally consumed and to utilize substantially the entire target 20. Note that the moving mechanism 122 (specifically, the driving unit 23b) is controlled by a control unit U1 described later.

[0030] The film forming apparatus 1 further includes a gas supply unit 30 that supplies gas into the processing chamber 10. The gas supply unit 30 has, for example, a gas source 30a, a flow rate controller 30b such as a mass flow controller, and a gas introduction unit 30c. The gas source 30a stores a gas (for example, Ar gas) that is excited in the processing chamber 10. The gas source 30a is connected to the gas introduction unit 30c via the flow rate controller 30b. The gas introduction unit 30c is a member that introduces the gas from the gas source 30a into the processing chamber 10.

[0031] When gas is supplied from this gas supply unit 30 and power is supplied to the target 20 by the power supply 21, the gas supplied into the processing chamber 10 is excited. Further, a magnetic field is generated in the vicinity of the front surface of the target 20 by the magnet unit 22, and plasma is concentrated in the vicinity of the front surface of the target 20. Then, positive ions in the plasma collide with the target 20, and the substance constituting the target 20 is released as sputtered particles from the target 20. Thereby, for example, an IGZO film is formed on the wafer W.

[0032] The film forming apparatus 1 also includes a head 40. The head 40 is a member that injects an oxidation gas for oxidizing the film formed on the wafer W toward the mounting table 14. The head 40 is formed, for example, in a circular shape in plan view, and the area in its plan view is larger than the wafer adsorption surface 14c of the mounting table 14.

[0033] This head 40 moves between a processing position and a retracted position along with the operation of a drive mechanism 50 described later. The processing position is a position above the mounting table 14 and is a position within the processing space S1 between the target 20 and the mounting table 14. Further, the retracted position P2 is a position away from the processing space S1 within the processing container 10 and is a position where the head 40 does not overlap the mounting table 14 in top view within another space S2 different from the processing space S1.

[0034] One end of a connecting portion 41 extending in a direction orthogonal to the axis AX2 of the support shaft 50a of the drive mechanism 50 is connected to the peripheral portion of the head 40. The support shaft 50a is connected to the other end of the connecting portion 41. A gas line GL1 for the oxidation gas is formed in the head 40, the connecting portion 41, and the support shaft 50a. The end portion of the gas line GL on the side opposite to the head 40 is located outside the processing container 10, and the gas supply unit 31 is connected thereto. The gas supply unit 31 has, for example, a gas source 31a and a flow controller 31b such as a mass flow controller. The gas source 31a stores an oxidation gas (for example, O2 gas). The gas source 31a is connected to the gas line GL via the flow controller 31b.

[0035] The gas line GL1 is connected to a plurality of gas injection ports 40a provided in the head 40 within the head 40. The plurality of gas injection ports 40a open downward, that is, toward the mounting table 14.

[0036] Furthermore, the film forming apparatus 1 has a drive mechanism 50 as a retracting mechanism. The drive mechanism 50 has, for example, a support shaft 50a and a drive unit 50b.

[0037] The support shaft 50a extends along the axis AX2. This axis AX2 is substantially parallel to the axis AX1 and extends vertically on the side of the mounting table 14. Also, the support shaft 50a extends in the vertical direction so as to penetrate the bottom wall of the processing container 10. A sealing member SL2 is provided between the support shaft 50a and the bottom wall of the processing container 10. The sealing member SL2 is a member that seals the space between the bottom wall of the processing container 10 and the support shaft 50a so that the support shaft 50a can rotate and move vertically, and is, for example, a magnetic fluid seal. A drive unit 50b is connected to the lower end of the support shaft 50a.

[0038] The drive unit 50b generates a driving force for rotating and vertically moving the support shaft 50a. As the support shaft 50a rotates about the axis AX2, the head 40 rotates about the axis AX2, and as the support shaft 50a moves vertically, the head 40 moves vertically.

[0039] Furthermore, the film forming apparatus 1 includes a control unit U1. The control unit U1 is constituted by a computer including a processor such as a CPU and a memory, and has a program storage unit (not shown). The program storage unit stores a program including commands for controlling the power control unit U2, the drive units 16b, 23b, 50b, etc. to realize the wafer processing described later using the film forming apparatus 1. Note that the above program may be recorded on a computer-readable storage medium and installed from the storage medium to the control unit U1. Also, the above storage medium may be a temporary storage medium or a non-temporary storage medium.

[0040] The control unit U1 further has an input unit for an operator to input various information. The input unit includes, for example, at least one of a keyboard, a mouse, or a touch panel.

[0041] <Wafer Processing> Next, an example of wafer processing including a film forming process using the film forming apparatus 1 will be described with reference to FIGS. 4 to 6. FIG. 4 is a diagram for explaining the operation of the magnet unit 22 during wafer processing. FIG. 5 is a diagram showing the relationship between the position (horizontal axis) of the magnet unit 22 during wafer processing and the power supplied to the holder 20a (vertical axis). FIG. 6 is a diagram for explaining the period during which the serial communication monitoring described later is interrupted. In FIG. 6, the horizontal axis indicates time, and the vertical axis indicates the position of the magnet unit 22. Also, in FIG. 6, the position "x0" is the position where the magnet unit 22 faces the center of the target 20 in the swinging direction of the magnet unit 22. The position "x1" is the position where the magnet unit 22 faces one end of the target 20 in the swinging direction of the magnet unit 22. The position "-x1" is the position where the magnet unit 22 faces the other end of the target 20 in the swinging direction of the magnet unit 22. Note that each of the following steps is performed under the control of the control unit U1.

[0042] (Step S1: Loading) First, the wafer W is loaded into the processing chamber 10. Specifically, the gate valve 13a is opened, and a transfer mechanism (not shown) holding the wafer W is inserted into the processing chamber 10 through the transfer port 13 from a transfer chamber (not shown) in a vacuum atmosphere adjacent to the processing chamber 10 that has been adjusted to a desired pressure by the exhaust device 11. Next, the wafer W is transferred from the transfer mechanism onto the raised support pins (not shown), and then the transfer mechanism is withdrawn from the processing chamber 10, and the gate valve 13a is closed. At the same time, the support pins are lowered, and the wafer W is placed on the mounting table 14 and adsorbed and held by the electrostatic adsorption force of the electrostatic chuck 14b.

[0043] Subsequently, an IGZO film is formed on the wafer W by magnetron sputtering of the target 20. In this step, for example, the following steps S2 to S4 are performed.

[0044] (Step S2: Start of Magnetron Sputtering) Specifically, first, magnetron sputtering of the target 20 is started. Magnetron sputtering is performed in a state where the magnet unit 22 is oscillated by the moving mechanism 23, specifically, in a state where the magnet unit 22 is oscillated at a constant speed (excluding the turning-back part) by the moving mechanism 23. Further, magnetron sputtering may be performed in a state where the mounting table 14 is rotated by the driving mechanism 16.

[0045] In magnetron sputtering, for example, Ar gas is supplied into the processing container 10 from the gas supply unit 30 as a sputtering gas, and a magnetic field is generated by the magnet unit 22. Further, in magnetron sputtering, electric power is supplied from the power supply 21 to the target 20. Due to the electric power from the power supply 21, the Ar gas in the processing container 10 is ionized, and the electrons generated by the ionization drift due to the magnetic field formed by the magnet unit 22 and the electric field due to the electric power from the power supply 21, and high-density plasma is generated. The surface of the target 60 is sputtered by the Ar ions in this plasma, and the sputtered particles are deposited on the wafer W. Thereby, an IGZO film is formed on the wafer W.

[0046] (Step S3: Serial communication monitoring) Also, at least during the period from the start to the end of magnetron sputtering, that is, during magnetron sputtering, serial communication monitoring is performed by the power control unit U2.

[0047] Serial communication monitoring means repeatedly acquiring information regarding the electric power output by the power supply 21 from the power supply 21 by serial communication. The information acquired by serial communication monitoring is specifically at least one of the magnitude of the electric power output from the power supply 21, current, or voltage, and can be used for determining the state of the plasma in the processing container 10. Further, the information acquired by the power control unit U2 is transmitted to the control unit U1.

[0048] (Step S4: End of Magnetron Sputtering) When a predetermined condition is satisfied (for example, when a predetermined time has elapsed since the start of magnetron sputtering), the magnetron sputtering of the target 20 is terminated. Specifically, the gas supply from the gas supply unit 30, the power supply from the power supply 21 to the target 20, and the oscillation of the magnet unit 22 are stopped. Also, if the mounting table 14 was rotating, this rotation is also stopped. Serial communication monitoring may also be stopped.

[0049] In the wafer processing using the film forming apparatus 1, during the above-described magnetron sputtering, when the magnet unit 22 reaches a predetermined power switching position during oscillation, serial communication with the power supply 21 regarding the switching of the power supplied to the holder 20a (hereinafter referred to as "serial communication for power switching") is performed by the power supply control unit U2 so that the following (a) and (b) are achieved. Hereinafter, the "end portion of the target 20" means the end portion of the target 20 in the depth direction of the apparatus (Y direction in FIG. 1 etc.), that is, in the oscillation direction of the magnet unit 22, and the "central portion of the target 20" means the central portion of the target 20 in the depth direction of the apparatus (Y direction in FIG. 1 etc.), that is, in the oscillation direction of the magnet unit 22.

[0050] (a) As shown in FIGS. 4(A) and 4(C), when the magnet unit 22 faces the end portion of the target 20, the power supplied to the holder 20a increases (specifically, as shown in FIG. 5, when the magnet unit 22 is located in the region R1 facing the end portion of the target 20, the power supplied to the holder 20a becomes PW1). (b) As shown in FIG. 4(B), when the magnet unit 22 faces the central portion of the target 20, the power supplied to the holder 20a decreases (specifically, as shown in FIG. 5, when the magnet unit 22 is located in the region R2 facing the central portion of the target 20, the power supplied to the holder 20a becomes PW2 (<PW1)).

[0051] For example, PW1 is the base power × 100%, and PW2 is the base power × 30 - 70%. In the serial communication for power switching here, a command for specifying the above output ratio is transmitted to the power supply 21. Note that a command for specifying the base power is transmitted to the power supply 21 in advance. The reason for switching the power (magnitude) in this way will be described later.

[0052] In addition, in the wafer processing using the film forming apparatus 1, during the above-described magnetron sputtering, at least during the following (c), the above-described serial communication monitoring by the power control unit U2 is interrupted.

[0053] (c) As shown in FIG. 6, from a predetermined time T1 before the time points t1 and t2 when the magnet unit 22 becomes the power switching position during the swinging, until the serial communication for power switching is completed (that is, from the time point t3 until the serial communication for power switching is completed and from the time point t4 until the serial communication for power switching is completed)

[0054] The above-described predetermined time T1 is longer than the time T2 required to acquire information regarding the power output by the power supply 21 once in the serial communication monitoring. The above-described predetermined time T1 is, for example, 2 times or more and 3 times or less of the above time T2.

[0055] The reason for interrupting the serial communication monitoring in this way will be described later. The period during which the serial communication monitoring is interrupted during magnetron sputtering may be only from a predetermined time T1 before the time when the magnet unit 22 becomes the power switching position until the serial communication for power switching is completed.

[0056] (Step S5: Unloading) After the formation of the IGZO film by magnetron sputtering, the wafer W is unloaded from the processing container 10. Specifically, in an operation reverse to the loading at step S1, the wafer W is unloaded outside the processing container 10. Then, it returns to the above-described loading process, and the next wafer W to be film-formed is similarly processed.

[0057] Note that, before the unloading in step S5, a step of oxidizing the film formed by magnetron sputtering may be performed. Specifically, before the unloading in step S5, a step of oxidizing the film formed by magnetron sputtering using the head 40 may be performed. When such an oxidation step is not performed, the head 40 and the components related thereto may be omitted from the film-forming apparatus 1.

[0058] <Reason for switching power> Subsequently, the reason for switching the power (magnitude) supplied to the holder 20a during magnetron sputtering as described above will be described with reference to FIGS. 7 to 11. FIGS. 7 to 9 are diagrams conceptually showing the angular distribution of metal elements emitted by sputtering from the target 20 made of IGZO. Further, FIGS. 7 to 9 conceptually show the angular distributions of In, Ga, and Zn, respectively. FIGS. 10 and 11 are diagrams for explaining the relationship between the position of the magnet unit 22 and the deposition position of Zn on the wafer W. Note that the "normal direction of the target surface of the target 20" hereinafter is the normal direction of the target surface of the target 20 passing through the magnet unit 22 (specifically, its center).

[0059] The angle of the metal element emitted from the target 20 by sputtering varies depending on the sputtering conditions (e.g., pressure, etc.), and also varies depending on the type of the metal element even under the same sputtering conditions.

[0060] For example, under the sputtering conditions generally used for the target 20 made of IGZO, as shown in FIGS. 7 to 9, the angular distribution of Zn is different from the angular distributions of In and Ga.

[0061] Specifically, as shown in FIGS. 7 and 8, the angular distributions DIn of In and DGa of Ga have a high frequency in the direction normal to the target surface of the target 20. That is, In and Ga are mainly emitted in the direction normal to the target surface of the target 20. Therefore, when the power supplied to the holder 20a is constant, In and Ga are deposited more on the central portion of the wafer W when the central portion of the target 20 faces the magnet unit 22, and are deposited more on the peripheral portion of the wafer W when the end portion of the target 20 faces the magnet unit 22.

[0062] On the other hand, as shown in FIG. 9, the angular distribution DZn of Zn has a high frequency in a direction inclined with respect to the direction normal to the target surface of the target 20. That is, Zn is mainly emitted in a direction inclined from the direction normal to the target surface of the target 20. Therefore, when the power supplied to the holder 20a is constant, Zn is deposited more on the peripheral portion of the wafer W when the central portion of the target 20 faces the magnet unit 22, as shown in gray in FIG. 10. Also, Zn is deposited more on the central portion of the wafer W when the end portion of the target 20 faces the magnet unit 22, as shown in gray in FIG. 11.

[0063] In addition, the magnet unit 22 is located in the region facing the central portion of the target 20 for a longer time than in the region facing the peripheral portion of the target 20. Furthermore, in a configuration where the distance between the magnet unit 22 and the target 20 is constant as in the present embodiment, when the power supplied to the holder 20a is constant, the plasma density generated near the surface of the target 20 also becomes constant. Therefore, if the power supplied to the holder 20a is kept constant, the deposition amount of Zn will vary significantly between the central part and the peripheral part of the wafer W. As a result, the composition ratio of the IGZO film may become non-uniform within the plane of the wafer W. Specifically, if the power supplied to the holder 20a is kept constant, the density of Zn in the IGZO film on the wafer W may be low at the central part of the wafer W and high at the peripheral part of the wafer W.

[0064] In view of this point, in the wafer processing using the film forming apparatus 1, during magnetron sputtering, the power (magnitude) supplied to the holder 20a is switched. When the magnet unit 22 faces the end portion of the target 20, the power is increased, and when the magnet unit 22 faces the central portion of the target 20, the power is decreased. Thereby, while maintaining the deposition amount of Zn on the central part of the wafer W, the deposition amount of Zn on the peripheral part of the wafer W can be suppressed. As a result, while maintaining the density of Zn in the IGZO film at the central part of the wafer W, the density of Zn in the IGZO film at the peripheral part of the wafer W can be decreased. Therefore, the in-plane uniformity of the composition ratio in the IGZO film, that is, the Zn density in the IGZO film, can be improved.

[0065] Also, as described above, by switching the power (magnitude) supplied to the holder 20a during magnetron sputtering, while maintaining the deposition amounts of In and Ga on the peripheral part of the wafer W, the deposition amounts of In and Ga on the central part of the wafer W can be suppressed. Thereby, while maintaining the densities of In and Ga in the IGZO film at the peripheral part of the wafer W, the densities of In and Ga in the IGZO film at the central part of the wafer W can be decreased. As a result, the density of Zn in the IGZO film at the peripheral part of the wafer W can be relatively decreased. From this perspective as well, the in-plane uniformity of the composition ratio in the IGZO film, that is, the Zn density in the IGZO film, can be improved.

[0066] <Reasons for interrupting serial communication monitoring> Next, the reasons for interrupting the serial communication monitoring as described above will be explained. In serial communication monitoring, the time T2 required for the power control unit U2 to acquire information regarding the power output by the power supply 21 once by serial communication is relatively long. For example, it is about 1% of the oscillation period of the magnet unit 22 (that is, when the oscillation period is 4 s, it is about 40 ms). Therefore, if serial communication monitoring is being performed at the time points t1 and t2 when the magnet unit 22 becomes the power switching position during oscillation, serial communication for power switching cannot be performed at the time points t1 and t2, and there may be a situation where the in-plane uniformity of the Zn density in the IGZO film cannot be sufficiently improved.

[0067] Therefore, in wafer processing using the film forming apparatus 1, serial communication monitoring is interrupted from a predetermined time T1 before the time points t1 and t2 when the magnet unit 22 becomes the power switching position during oscillation until serial communication for power switching is completed. Thereby, serial communication for power switching can be performed at the time points t1 and t2. As a result, the in-plane uniformity of the Zn density in the IGZO film can be surely improved.

[0068] <Main effects of the present embodiment> As described above, according to the present embodiment, the in-plane uniformity of the characteristics of the film formed by magnetron sputtering (specifically, the Zn density in the IGZO film) can be improved. Further, in the present embodiment, since there is no need to provide a mechanism for moving the magnet unit 22 in a direction perpendicular to the surface of the target 20, an increase in the size of the film forming apparatus 1 can be suppressed. That is, according to the present embodiment, it is possible to improve the in-plane uniformity of the characteristics of the film formed by magnetron sputtering while suppressing an increase in the size of the apparatus.

[0069] In accordance with this embodiment, in the form of moving the magnet unit 22 in the direction perpendicular to the surface of the target 20 in order to improve the in-plane uniformity of the density distribution of Zn, it takes time to change the emission characteristics of Zn from the target 20. This has no effect on the in-plane uniformity of the characteristics of the film to be formed if the target 20 is large like that for a glass substrate, but may have an effect if it is small like that for the wafer W. On the other hand, in this embodiment, by switching the power (magnitude) supplied to the holder 20a, the emission characteristics of Zn from the target 20 are changed, so the time required for this change is short. Therefore, even if the target 20 is small like that for the wafer W, the in-plane uniformity of the characteristics of the film to be formed can be sufficiently improved.

[0070] Also, as described above, the period during which the serial communication monitoring is interrupted during film formation by magnetron sputtering may be only from a predetermined time T1 before the time when the magnet unit 22 reaches the power switching position to the completion of the serial communication for power switching. Thereby, while suppressing the time for which the serial communication monitoring is interrupted, the serial communication for power switching can be performed when the magnet unit 22 reaches the power switching position.

[0071] <Modification Example> In the above example, the power supply 21 was a DC power supply, but it may be an AC power supply. Also, in the above example, the power supply control unit U2 is provided independently of the control unit U1, but the control unit U1 may also serve as the power supply control unit U2.

[0072] In the above example, an IGZO film was formed using a target 20 made of IGZO. However, the technology according to the present disclosure can also be applied to the case of forming a Zn film other than the IGZO film using a target containing Zn other than the IGZO target if the frequency of the angular distribution of Zn is high in a direction inclined with respect to the normal direction of the target surface of the target. Also in this case, the in-plane uniformity of the characteristics of the film formed by magnetron sputtering (specifically, the film composition and film thickness) can be improved. Further, the technology according to the present disclosure can be applied also when using a target other than Zn in which the frequency is high in a direction inclined with respect to the normal direction of the target surface.

[0073] The embodiments disclosed this time should be considered to be illustrative in all respects and not restrictive. The above embodiments may be omitted, substituted, or changed in various forms without departing from the scope and gist of the appended claims. For example, the constituent elements of the above embodiments can be arbitrarily combined. From such an arbitrary combination, the actions and effects of each constituent element related to the combination can be naturally obtained, and other actions and other effects obvious to those skilled in the art can be obtained from the description of this specification.

[0074] Also, the effects described in this specification are merely illustrative or exemplary and not restrictive. That is, the technology according to the present disclosure can exhibit other effects obvious to those skilled in the art from the description of this specification together with, or instead of, the above effects.

[0075] Note that the following configuration examples also belong to the technical scope of the present disclosure. (1) A film forming method of forming a film on a substrate by sputtering a target using a film forming apparatus, wherein the film forming apparatus includes a substrate support portion for supporting a substrate, a target holder that holds the target so that the target faces the substrate support portion and is supplied with power from a power source, A magnet unit provided on the side of the target holder opposite to the substrate support portion and having a magnet; A step of forming a film on a substrate by magnetron sputtering of the target; A step of performing serial communication monitoring for repeatedly acquiring information regarding the power from the power supply by serial communication during the film forming step; and During the film forming step, Swinging the magnet unit in a predetermined direction along the target held by the target holder; When the magnet unit faces an end portion of the target in the predetermined direction, the power supplied to the target holder increases, and when the magnet unit faces a central portion of the target in the predetermined direction, the power supplied to the target holder decreases. When the magnet unit reaches a predetermined power switching position during swinging, serial communication is performed with the power supply regarding switching of the power supplied to the target holder; A film forming method, wherein serial communication monitoring is interrupted at least from a predetermined time before the magnet unit reaches the power switching position until serial communication regarding switching of the power supplied to the target holder is completed. (2) The film forming method according to (1), wherein the predetermined time is longer than the time required to acquire information regarding the power once in the serial communication monitoring. (3) The film forming method according to (1) or (2), wherein serial communication monitoring is interrupted only from a predetermined time before the magnet reaches the power switching position until serial communication regarding switching of the power supplied to the target holder is completed during the film forming step. (4) A film forming apparatus for forming a film on a substrate by sputtering a target, A substrate support portion for supporting a substrate; A target holder that holds the target so that the target faces the substrate support portion and is supplied with power from a power supply; A magnet unit provided on the side of the target holder opposite to the substrate support portion and having a magnet, and a moving mechanism for swinging the magnet unit in a predetermined direction along the target held by the target holder, a control unit, and the control unit performs a step of forming a film on a substrate by magnetron sputtering of the target, and a step of causing a power supply control unit to perform serial communication monitoring for repeatedly acquiring information regarding the power from the power supply by serial communication during the film forming step, during the film forming step, swing the magnet unit in the predetermined direction, when the magnet unit faces an end portion of the target in the predetermined direction, the power supplied to the target holder increases, and when the magnet unit faces a central portion of the target in the predetermined direction, the power supplied to the target holder decreases. When the magnet unit reaches a predetermined power switching position during swinging, the power supply control unit is caused to perform serial communication with the power supply regarding switching of the power supplied to the target holder, A film forming apparatus that interrupts the serial communication monitoring by the power supply control unit at least from a predetermined time before the magnet unit reaches the power switching position until serial communication regarding switching of the power supplied to the target holder is completed.

Explanation of Reference Numerals

[0076] 1 Film forming apparatus 14 Mounting table 20 Target 20a Target holder 21 Power supply 22 Magnet unit 23 Moving mechanism U1 Control unit U2 Power supply control unit W wafer

Claims

1. A film forming method for forming a film on a substrate by sputtering a target using a film forming apparatus, comprising: The film forming apparatus includes: a substrate support portion for supporting a substrate; a target holder that holds the target so that the target faces the substrate support portion and is supplied with power from a power source; a magnet unit provided on the side of the target holder opposite to the substrate support portion and having a magnet; a step of forming a film on the substrate by magnetron sputtering of the target; a step of performing serial communication monitoring for repeatedly acquiring information regarding the power from the power source by serial communication during the film forming step; During the film forming step, oscillating the magnet unit in a predetermined direction along the target held by the target holder; when the magnet unit faces an end portion of the target in the predetermined direction, the power supplied to the target holder increases, and when the magnet unit faces a central portion of the target in the predetermined direction, the power supplied to the target holder decreases. When the magnet unit reaches a predetermined power switching position during oscillation, serial communication is performed with the power source regarding switching of the power supplied to the target holder; A film forming method, wherein serial communication monitoring is interrupted at least from a predetermined time before the magnet unit reaches the power switching position until serial communication regarding switching of the power supplied to the target holder is completed.

2. The film forming method according to claim 1, wherein the predetermined time is longer than the time required to acquire information regarding the power once in the serial communication monitoring.

3. The film forming method according to claim 1 or 2, wherein serial communication monitoring is interrupted only from a predetermined time before the magnet reaches the power switching position until serial communication regarding switching of the power supplied to the target holder is completed during the film forming step.

4. A film forming apparatus for forming a film on a substrate by sputtering a target, comprising: a substrate support portion for supporting a substrate; a target holder that holds the target so that the target faces the substrate support portion and is supplied with power from a power source; A magnet unit provided on the side of the target holder opposite to the substrate support portion and having a magnet; A moving mechanism that swings the magnet unit in a predetermined direction along the target held by the target holder; A control unit, and The control unit Performs a step of forming a film on a substrate by magnetron sputtering of the target; Performs a step of causing a power supply control unit to perform serial communication monitoring for repeatedly acquiring information regarding the power from the power supply by serial communication during the film forming step; During the film forming step, The magnet unit is swung in the predetermined direction, When the magnet unit faces an end portion of the target in the predetermined direction, the power supplied to the target holder increases, and when the magnet unit faces a central portion of the target in the predetermined direction, the power supplied to the target holder decreases. When the magnet unit reaches a predetermined power switching position during swinging, the power supply control unit is caused to perform serial communication with the power supply regarding switching of the power supplied to the target holder; A film forming apparatus that interrupts the serial communication monitoring by the power supply control unit at least from a predetermined time before the magnet unit reaches the power switching position until serial communication regarding switching of the power supplied to the target holder is completed.

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