Sputtering device

Abstract

This sputtering device comprises: a chamber; a substrate holding section provided in the chamber to hold a substrate; a target holding section that holds a target so as to face the substrate in the chamber; and a control section that controls a negative bias state in which the potential of the target holding section relative to the substrate holding section is negative, and a positive bias state in which the potential of the target holding section relative to the substrate holding section is positive. The control section, by supplying a pulse voltage, periodically performs control to activate the negative bias state. A plurality of periods between adjacent pulse voltages include a first period in which control is performed to activate the positive bias state and a second period in which control is not performed to activate the positive bias state.

Description

Sputtering Equipment

[0001] An embodiment of the present invention relates to a sputtering apparatus.

[0002] Display devices using liquid crystal or organic light-emitting diodes (OLEDs) have already been commercialized for small and medium-sized display devices such as smartphones. In particular, OLED display devices using OLEDs, which are self-emissive elements, have the advantage of high contrast and no need for backlighting compared to liquid crystal display devices. However, because the organic compounds that make up OLEDs are prone to degradation due to moisture, it is difficult to ensure high reliability for OLED display devices.

[0003] In recent years, development of so-called micro LED or mini LED displays, in which tiny LED chips are mounted within the pixels of a circuit board, has been progressing as next-generation display devices. LEDs are self-emitting elements similar to OLEDs; however, unlike OLEDs, LEDs are composed of stable inorganic compounds containing gallium (Ga) or indium (In). Therefore, compared to OLED display devices, micro LED display devices are more likely to ensure high reliability. Furthermore, LED chips have high luminous efficiency and can achieve high brightness. Therefore, micro LED or mini LED display devices are expected to be next-generation display devices with high reliability, high brightness, and high contrast.

[0004] Gallium nitride films used in micro LEDs and the like are generally formed on sapphire substrates using metal organic chemical vapor deposition (MOCVD) or hydride vapor phase epitaxy (HVPE) at high temperatures of 800° C. to 1000° C. However, in recent years, methods for forming gallium nitride films by sputtering, which allows film formation at relatively low temperatures, have been developed (see, for example, Patent Document 1).

[0005] JP 2012-119569 A

[0006] If the gallium nitride layer that constitutes the micro-LED could be deposited at low temperatures, it would be possible to form the micro-LED directly on a glass substrate. However, when the gallium nitride layer is deposited using conventional sputtering equipment, there is a problem in that the nitrogen contained in the gallium nitride layer is deficient, making it impossible to form a gallium nitride layer with high crystallinity. As a result, it has been difficult to obtain sufficient performance from micro-LEDs using the gallium nitride layer.

[0007] In view of the above problems, one object of one embodiment of the present invention is to provide a new sputtering apparatus.

[0008] A sputtering apparatus according to one embodiment of the present invention comprises a chamber, a substrate holder provided within the chamber for holding a substrate, a target holder for holding a target in the chamber so as to face the substrate, and a control unit configured to control a negative bias state in which the potential of the target holder relative to the substrate holder is negative, and a positive bias state in which the potential of the target holder relative to the substrate holder, wherein the control unit is configured to periodically control to the negative bias state by supplying a pulse voltage, and to control multiple periods between adjacent pulse voltages among multiple pulse voltages into a first period in which the positive bias state is controlled and a second period in which the positive bias state is not controlled.

[0009] A sputtering apparatus according to one embodiment of the present invention comprises a chamber, a substrate holder provided within the chamber for holding a substrate, a target holder for holding a target in the chamber so as to face the substrate, and a control unit configured to control a negative bias state in which the potential of the target holder relative to the substrate holder is negative, and a positive bias state in which the potential of the target holder relative to the substrate holder is positive, wherein the control unit is configured to control the positive bias state in the first period, the negative bias state in the second period, and the positive bias state in the third period, for a first period, a second period, and a third period that are consecutive on a time axis.

[0010] A sputtering apparatus according to one embodiment of the present invention comprises a chamber, a substrate holder provided within the chamber for holding a substrate, a target holder for holding a target within the chamber so as to face the substrate, a magnet provided on the opposite side of the substrate holder relative to the target holder, and a control unit configured to control a negative bias state in which the potential of the target holder relative to the substrate holder is negative and a positive bias state in which the potential of the target holder relative to the substrate holder, and configured to control the magnetic field formed between the target holder and the substrate holder by the magnet, wherein the control unit is configured to control the magnet so that the magnetic field in the positive bias state is smaller than the magnetic field in the negative bias state.

[0011] FIG. 1 is a top view showing an overview of a sputtering apparatus according to an embodiment of the present invention; FIG. 2 is a diagram showing a method for controlling a voltage supplied to a sputtering apparatus according to an embodiment of the present invention; FIG. 3 is a functional block diagram of a control unit of a sputtering apparatus according to an embodiment of the present invention; FIG. 4 is a diagram showing a phenomenon occurring in a negative bias state in a sputtering apparatus according to an embodiment of the present invention; FIG. 5 is a diagram showing a method for controlling a voltage supplied to a sputtering apparatus according to an embodiment of the present invention; FIG. 6 is a diagram showing a method for controlling a voltage supplied to a sputtering apparatus according to an embodiment of the present invention; FIG. 7 is a diagram showing a state in a negative bias state in a sputtering apparatus according to an embodiment of the present invention; FIG. 8 is a diagram showing a state in a positive bias state in a sputtering apparatus according to an embodiment of the present invention; FIG. 9 is a diagram showing a state in a negative bias state in a sputtering apparatus according to an embodiment of the present invention;

[0012] Each embodiment of the present invention will be described below with reference to the drawings. The following disclosure is merely an example. Configurations that a person skilled in the art can easily arrive at by appropriately modifying the configuration of the embodiment while maintaining the gist of the invention are naturally included within the scope of the present invention. For clarity of explanation, the width, thickness, shape, etc. of each part in the drawings may be shown schematically compared to the actual embodiment. However, the illustrated shapes are merely examples and do not limit the interpretation of the present invention. In this specification and each drawing, elements similar to those described above with respect to the previous drawings will be given the same reference numerals, and detailed descriptions may be omitted as appropriate.

[0013] In each embodiment of the present invention, the direction from the first member to the second member is referred to as "up" or "upper." Conversely, the direction from the second member to the first member is referred to as "down" or "downward." For convenience of explanation, the terms "up" and "downward" are used in the description. However, for example, the vertical relationship between the first member and the second member may be reversed from that illustrated. In the following description, for example, the expression "second member above the first member" merely describes the vertical relationship between the first member and the second member as described above; other members may be disposed between the first member and the second member. "Above" or "below" refers to the stacking order in a structure in which multiple layers are stacked. When referring to a second member above a first member, the first member and the second member may not overlap in a planar view. On the other hand, when referring to a second member vertically above the first member, the first member and the second member may overlap in a planar view. For example, the first member may be the backing plate 220, and the second member may be the target 210.

[0014] In this specification, unless otherwise specified, expressions such as "α includes A, B, or C," "α includes any of A, B, and C," and "α includes one selected from the group consisting of A, B, and C" do not exclude cases where α includes multiple combinations of A to C. Furthermore, these expressions do not exclude cases where α includes other elements.

[0015] In the following description, "voltage" refers to the potential difference between two terminals, but may also refer to a potential relative to a reference voltage VSS. The reference voltage VSS is a voltage that serves as a reference in a circuit system, and is, for example, 0 V or ground potential.

[0016] The following embodiments can be combined with each other unless a technical contradiction occurs.

[0017] 1. First Embodiment A sputtering apparatus 10 according to one embodiment of the present invention and a sputtering method using the sputtering apparatus 10 will be described with reference to FIGS.

[0018] [1-1. Configuration of Sputtering Apparatus] FIG. 1 is a top view showing an overview of a sputtering apparatus according to one embodiment of the present invention. As shown in FIG. 1, the sputtering apparatus 10 includes a chamber 100, a target unit 200, a substrate holding unit 300, a control unit 600, a position control unit 610, a movement mechanism 620, and a holding mechanism 630. FIG. 1 shows only a portion of the chamber 100. The chamber 100 forms a closed space. The target unit 200, the substrate holding unit 300, the position control unit 610, the movement mechanism 620, and the holding mechanism 630 are provided within the chamber 100. Although not shown, the chamber 100 is provided with an exhaust port and a process gas supply port. The pressure within the chamber 100 can be reduced via the exhaust port. Gases such as argon and nitrogen required for sputtering can be supplied into the chamber 100 via the process gas supply port.

[0019] A substrate 310, which is an object to be film-formed, is held by the substrate holding unit 300. In the example of FIG. 1 , the substrate 310 is held by the substrate holding unit 300 so that its main surface (film-forming surface) extends in the X-axis direction and the Z-axis direction. In other words, the substrate 310 is held by the substrate holding unit 300 in a vertically placed state. In the present embodiment, as described above, a configuration in which the substrate 310 is arranged so that its main surface extends in the X-axis direction and the Z-axis direction has been exemplified, but this configuration is not limiting. The target unit 200 and the substrate 310 may be arranged so that the main surface extends in the X-axis direction and the Y-axis direction.

[0020] The target unit 200 is disposed opposite the substrate holding unit 300. In other words, the target unit 200 is located in the Y-axis direction of the substrate 310 during film formation. The target unit 200 includes a target 210, a backing plate 220, a central magnet 240, a peripheral magnet 250, and a yoke 260. These components are shaped such that their elongated sides extend in the Z-axis direction. Although details are omitted, the target 210 is a flat target that extends in the Z-axis direction.

[0021] At least one of the backing plate 220 and the holding mechanism 630 may be referred to as a "target holding unit." In this case, the target holding unit can be said to be provided in the chamber 100 and to hold the target 210. In the following description, the backing plate 220 corresponds to the target holding unit.

[0022] The target 210 is made of a material having the same composition as the thin film to be formed on the deposition surface of the substrate 310, or containing elements contained in the thin film. For example, when a gallium nitride (GaN) thin film is formed on the deposition surface, the target 210 is made of GaN or gallium (Ga). In the target unit 200, the side facing the substrate holding unit 300 is referred to as the front side, and the side opposite the front side is referred to as the back side. The target 210 is fixed to the front side of the backing plate 220 by, for example, indium or the like.

[0023] A yoke 260 is fixed on the holding mechanism 630. The central magnet 240 and the peripheral magnets 250 are fixed to the front surface of the yoke 260. When the central magnet 240 and the peripheral magnets 250 are not particularly distinguished from each other, they may be simply referred to as "magnets." In this case, the magnets can be said to be located on the opposite side of the substrate holder 300 with respect to the backing plate 220. The central magnet 240 has a polarity (magnetic pole) different from that of the peripheral magnets 250. In other words, these magnets form a magnetic field on the front side of the target 210 from the central magnet 240 toward the peripheral magnets 250 (or vice versa). These magnets confine electrons in the plasma, forming a highly concentrated plasma region on the front side of the target 210. In this plasma region, the process gas is ionized. The process gas is, for example, argon, and the ionized argon is accelerated toward the target 210 in a sheath region formed between the plasma region and the target 210. The argon ions thus accelerated collide with the target 210, sputtering the target material.

[0024] During sputtering, a voltage is supplied to the substrate holding unit 300 and the backing plate 220 (target holding unit), and the sputtering apparatus 10 is controlled to a negative bias state or a positive bias state. The negative bias state is a state in which the potential of the backing plate 220 is negative relative to the substrate holding unit 300. The positive bias state is a state in which the potential of the backing plate 220 is positive relative to the substrate holding unit 300. The above-mentioned negative bias state and positive bias state are controlled by the control unit 600. In other words, the control unit 600 controls the voltages supplied to the substrate holding unit 300 and the backing plate 220.

[0025] In addition to the above-mentioned GaN and Ga, materials such as aluminum, aluminum nitride, indium, indium nitride, silicon, and magnesium are used as the target 210. Materials obtained by doping the above-mentioned materials with impurities (dopants) may also be used as the target 210. For example, materials obtained by doping gallium nitride with magnesium or silicon as a dopant may also be used. Gallium nitride containing magnesium as a dopant functions as a P-type semiconductor. Gallium nitride containing silicon as a dopant functions as an N-type semiconductor.

[0026] The holding mechanism 630 is connected to the moving mechanism 620. The moving mechanism 620 controls the positions of the holding mechanism 630 and the target unit 200 in the X-axis direction. A rail mechanism, for example, is used as the moving mechanism 620. However, other mechanisms may be used as the moving mechanism 620. The moving mechanism 620 is controlled by a position control unit 610. The position control unit 610 detects the positions in the X-axis direction of the holding mechanism 630 and the target unit 200 moved by the moving mechanism 620. A rotary encoder, for example, is used as the position control unit 610.

[0027] The position control unit 610 is connected to the control unit 600. Based on a control signal from the control unit 600, the position control unit 610 controls the moving mechanism 620, thereby determining the positions of the holding mechanism 630 and the target unit 200 in the X-axis direction. Furthermore, the control unit 600 obtains from the position control unit 610 information on the current positions of the holding mechanism 630 and the target unit 200 in the X-axis direction.

[0028] In this embodiment, the position of the substrate holding unit 300 is fixed in the X-axis direction, and the position of the target unit 200 is moved. The movement of the target unit 200 in the X-axis direction may be a swing (reciprocating or repeating in the positive and negative directions on the X-axis) or a passage in one direction (the positive or negative direction on the X-axis). However, the position of the target unit 200 may be fixed in the X-axis direction, and the position of the substrate holding unit 300 may be moved, or both the target unit 200 and the substrate holding unit 300 may move as described above. In other words, the position control unit 610 controls the relative positional relationship between the substrate holding unit 300 and the target unit 200 in the X-axis direction.

[0029] [1-2. Sputtering Method] When sputtering is performed using the sputtering apparatus 10, after the substrate 310 is held by the substrate holder 300, a process gas is introduced into the chamber 100, a voltage is supplied to the substrate holder 300 and the backing plate 220, and a plasma region is formed, thereby performing sputtering. In this embodiment, nitrogen gas or a mixed gas of nitrogen and argon is used as the process gas to form a GaN layer on the substrate 310. Therefore, nitrogen ions or nitrogen ions and argon ions are generated in the plasma region. Both the nitrogen ions and the argon ions are positive ions.

[0030] Normally, the backing plate 220 functions as a negative electrode (cathode) during sputtering, and therefore both nitrogen ions and argon ions are attracted to the backing plate 220. However, as will be described in detail later, in this embodiment, a period during sputtering is provided in which the substrate holding unit 300 functions as a cathode, and during this period, nitrogen ions are attracted to the substrate 310. When the nitrogen ions reach the substrate 310, nitrogen is supplied to the GaN layer formed on the substrate 310, and therefore nitrogen deficiency in the GaN layer can be suppressed.

[0031] A sputtering method using the sputtering apparatus 10 according to this embodiment will be described with reference to Fig. 2A. Fig. 2A is a diagram showing a method for controlling a voltage supplied to the sputtering apparatus according to one embodiment of the present invention. The lower graph shown in Fig. 2A is a timing chart of the voltage V1 supplied to the backing plate 220. The upper graph shown in Fig. 2A is a timing chart of the voltage V2 supplied to the substrate holder 300.

[0032] As shown in FIG. 2A , a negative pulse voltage PL1 (PL11 to PL14) is periodically supplied to the voltage V1. When the negative pulse voltage PL1 is supplied to the voltage V1, a reference voltage (e.g., 0 V) ​​is supplied to the substrate holding unit 300, and therefore the potential of the backing plate 220 relative to the substrate holding unit 300 is negative. In other words, the control unit 600 periodically controls the sputtering apparatus 10 to a negative bias state by supplying the pulse voltage PL1 to the backing plate 220. One period is defined as the interval at which the pulse voltage PL1 is supplied to the voltage V1. Specifically, as shown in FIG. 2A , one period is defined as the period (period P1) from when the first pulse voltage PL11 rises in the negative direction to when the second pulse voltage PL12, which follows the first pulse voltage PL11, rises in the negative direction. Each of the periods P1 to P3 shown in FIG. 2A is one period.

[0033] A negative pulse voltage PL2 (PL21 to PL22) is supplied to voltage V2 at a timing different from the timing at which the negative pulse voltage PL1 is supplied to voltage V1. When the negative pulse voltage PL2 is supplied to voltage V2, a reference voltage (e.g., 0 V) ​​is supplied to the backing plate 220, and therefore the potential of the backing plate 220 relative to the substrate holding unit 300 is positive. In other words, the control unit 600 periodically controls the sputtering apparatus 10 to a positive bias state by supplying pulse voltage PL2 to the substrate holding unit 300. Although multiple pulse voltages PL2 are supplied to voltage V2, the pulse voltages PL2 supplied to voltage V2 are supplied at different periods from the pulse voltage PL1 supplied to voltage V1. In other words, there are periods (periods P1 and P3) when pulse voltage PL2 is supplied to voltage V2 and periods (period P2) when it is not supplied. In other words, the control unit 600 controls the sputtering apparatus 10 to a negative bias state in each cycle (all periods P1 to P3). On the other hand, the control unit 600 controls the sputtering apparatus 10 to a positive bias state in periods P1 and P3, but does not perform this control in period P2. Periods P1 and P3 may be referred to as the "first period." Period P2 may be referred to as the "second period."

[0034] 2B is a functional block diagram of a control unit of a sputtering apparatus according to one embodiment of the present invention. As shown in FIG. 2B, the control unit 600 includes a first pulse power supply 601, a second pulse power supply 602, and a synchronization circuit 603. The first pulse power supply 601 is connected to the backing plate 220 and outputs a pulse voltage PL1. The second pulse power supply 602 is connected to the substrate holder 300 and outputs a pulse voltage PL2. The synchronization circuit 603 is connected to the first pulse power supply 601 and the second pulse power supply 602. The synchronization circuit 603 adjusts the timing at which the first pulse power supply 601 outputs the pulse voltage PL1 and the timing at which the second pulse power supply 602 outputs the pulse voltage PL2.

[0035] 3 and 4, the phenomena occurring in the negative bias state and the positive bias state will be described. In the following description, a configuration in which a mixed gas of nitrogen and argon is used as the process gas will be described.

[0036] 3 is a diagram illustrating a phenomenon that occurs in a negative bias state in a sputtering apparatus according to an embodiment of the present invention. As shown in FIG. 3, in a negative bias state, the backing plate 220 (target holder) functions as a cathode, and the substrate holder 300 functions as an anode. In a negative bias state, the negative voltage supplied to the backing plate 220 is also transmitted to the target 210, and the backing plate 220 and the target 210 function as cathodes.

[0037] A plasma region 400 is formed between the target 210 and the substrate holder 300. Nitrogen ions and argon ions are generated in the plasma region 400. These are positive ions and are attracted to the target 210, which functions as a cathode. The positive ions (e.g., argon ions and nitrogen ions) attracted to the target 210 are accelerated toward the target 210 by a sheath region 401 between the plasma region 400 and the target 210, and collide with the target 210. This collision causes sputtered particles to be emitted from the target 210 toward the substrate 310.

[0038] 4 is a diagram illustrating a phenomenon that occurs in a positive bias state in a sputtering apparatus according to an embodiment of the present invention, in which the substrate holder 300 functions as a cathode and the backing plate 220 functions as an anode.

[0039] 4, nitrogen ions and argon ions in the plasma region 400 are attracted to the substrate holder 300, which functions as a cathode. The positive ions (e.g., nitrogen ions) attracted to the substrate holder 300 are accelerated toward the substrate 310 by the sheath region 402 between the plasma region 400 and the substrate holder 300, and reach the substrate 310. The nitrogen ions that have reached the substrate 310 come into contact with a thin film formed on the substrate 310, thereby supplying nitrogen to the thin film.

[0040] As described above, with the sputtering apparatus 10 according to this embodiment, a thin film is formed on the substrate 310 by sputtering when the sputtering apparatus 10 is in a negative bias state, and the thin film formed on the substrate 310 is nitrided when the sputtering apparatus 10 is in a positive bias state. For example, when a GaN layer is formed using the sputtering apparatus 10, the GaN layer formed on the substrate 310 is nitrided when the sputtering apparatus 10 is in a positive bias state, which makes it possible to suppress nitrogen deficiency in the GaN layer.

[0041] Although the present embodiment has been described with reference to a case where a GaN layer is formed, the configuration to which the present embodiment is applicable is not limited to the formation of a GaN layer, and the present embodiment may also be applied when forming a layer containing other nitrides or compounds.

[0042] [1-3. Modified Example of Sputtering Apparatus] A modified example of this embodiment will be described with reference to FIG. 5. FIG. 5 is a diagram showing a method for controlling the voltage supplied to the sputtering apparatus according to one embodiment of the present invention. As shown in FIG. 5, in the modified example, similar to the first embodiment, a negative pulse voltage PL1 is supplied to the backing plate 220 and a reference voltage (e.g., 0 V) ​​is supplied to the substrate holding unit 300, thereby controlling the sputtering apparatus 10 to a negative bias state. On the other hand, unlike the first embodiment, a positive pulse voltage PL2 is supplied to the backing plate 220 and a reference voltage (e.g., 0 V) ​​is supplied to the substrate holding unit 300, thereby controlling the sputtering apparatus 10 to a positive bias state.

[0043] As described above, the bias state of the sputtering apparatus 10 may be controlled only by the voltage supplied to the backing plate 220. The sputtering apparatus 10 according to the above-described modified example can also achieve the same effects as those of this embodiment.

[0044] In the present embodiment and its modified example, the control unit 600 controls the sputtering apparatus 10 to a negative bias state once per cycle and a positive bias state once per two cycles. However, this configuration is not limiting. For example, the control unit 600 may control the sputtering apparatus 10 to a negative bias state once per cycle and to a positive bias state n times (n < m) during m cycles. In other words, while the backing plate 220 is supplied with a negative pulse voltage PL1 m times, the substrate holding unit 300 may be supplied with a negative pulse voltage PL2 n times. Alternatively, the control unit 600 may control the sputtering apparatus 10 to a negative bias state once per cycle and to a positive bias state once per k cycles (k is an integer greater than or equal to 2). In other words, while the backing plate 220 is supplied with a negative pulse voltage PL1 k times, the substrate holding unit 300 may be supplied with a negative pulse voltage PL2 once.

[0045] 6, a sputtering method using a sputtering apparatus 10A according to one embodiment of the present invention will be described. The configuration of the sputtering apparatus 10A according to the second embodiment is the same as the configuration of the sputtering apparatus 10 according to the first embodiment, and therefore a description thereof will be omitted. In the following description, when describing a configuration similar to that of the first embodiment, reference will be made to FIGS. 1 to 4, and the letter "A" will be added after the reference numerals shown in these figures.

[0046] [2-1. Sputtering Method] The sputtering method according to the second embodiment is similar to the sputtering method according to the first embodiment. In the following description, the same method as in the first embodiment will be omitted, and differences from the first embodiment will be mainly described.

[0047] 6 is a diagram showing a method for controlling voltages supplied to a sputtering apparatus according to one embodiment of the present invention. The lower graph in FIG. 6 is a timing chart of voltage V1 supplied to backing plate 220A. The upper graph in FIG. 6 is a timing chart of voltage V2 supplied to substrate holder 300A.

[0048] As shown in FIG. 6 , a negative pulse voltage PL1 is periodically supplied to voltage V1. In this embodiment, a negative pulse voltage PL3 is supplied to voltage V2 for at least two periods. In other words, a continuous negative pulse voltage PL3 is supplied to voltage V2 for at least two adjacent periods (periods P1-P2). In the example of FIG. 6 , a continuous negative pulse voltage PL3 is supplied to voltage V2 for three adjacent periods (periods P1-P3). In other words, while pulse voltage PL1 is supplied to voltage V1, pulse voltage PL3 is also supplied to voltage V2. The absolute value of the voltage supplied to voltage V1 is greater than the absolute value of the voltage supplied to voltage V2. In other words, even when pulse voltage PL3 is supplied to voltage V2, the sputtering apparatus 10A is in a negative bias state while pulse voltage PL1 is supplied to voltage V1. On the other hand, while the pulse voltage PL1 is not supplied to the voltage V1 and the pulse voltage PL3 is supplied to the voltage V2, the sputtering apparatus 10A is in a positive bias state.

[0049] As shown in FIG. 6 , the period during which the negative pulse voltage PL3 is supplied to voltage V2 can be divided into subperiods T1 to T5. During subperiods T1, T3, and T5, pulse voltage PL3 is supplied to voltage V2, and a reference voltage (0 V) is supplied to voltage V1. That is, during subperiods T1, T3, and T5, the sputtering apparatus 10A is controlled to a positive bias state. Meanwhile, during subperiods T2 and T4, pulse voltage PL1 is supplied to voltage V1, and pulse voltage PL3 is supplied to voltage V2. As described above, because the absolute value of the voltage supplied to voltage V1 is greater than the absolute value of the voltage supplied to voltage V2, the sputtering apparatus 10A is controlled to a negative bias state during subperiods T2 and T4.

[0050] In Figure 6, subperiods T1, T2, and T3 are consecutive periods on the time axis. In this embodiment, the state is switched between a positive bias state and a negative bias state during these consecutive periods. In the case of Figure 6, the sputtering apparatus 10A is controlled to a positive bias state during subperiod T1, a negative bias state during subperiod T2, and a positive bias state during subperiod T3. In other words, the control unit 600A supplies a negative voltage to the backing plate 220A during the central subperiod T2 of the consecutive subperiods T1 to T3, and supplies a negative voltage to the substrate holding unit 300 throughout the consecutive subperiods T1 to T3.

[0051] As described above, the sputtering apparatus 10A according to this embodiment can achieve the same effects as the sputtering apparatus 10 according to the first embodiment. Furthermore, in the case of the sputtering apparatus 10A, it is not necessary to synchronize the timing of the pulse voltage PL3 (voltage V2) supplied to the substrate holding part 300A with the timing of the pulse voltage PL1 (voltage V1) supplied to the backing plate 220A, and therefore the circuitry of the sputtering apparatus 10A can be simplified.

[0052] [2-2. Modified Example of Sputtering Apparatus] A modified example of this embodiment will be described with reference to FIG. 7 . FIG. 7 is a diagram illustrating a method for controlling a voltage supplied to a sputtering apparatus according to an embodiment of the present invention. As shown in FIG. 7 , in the modified example, during sub-periods T1, T3, and T5, a positive pulse voltage PL3 is supplied to the backing plate 220A, and a reference voltage (e.g., 0 V) ​​is supplied to the substrate holding unit 300A, thereby controlling the sputtering apparatus 10A to a positive bias state. During sub-periods T2 and T4, during which the sputtering apparatus 10A is controlled to a negative bias state, a negative pulse voltage PL1 (PL12, PL13) is supplied to the backing plate 220A, and a reference voltage (e.g., 0 V) ​​is supplied to the substrate holding unit 300A, thereby controlling the sputtering apparatus 10A to a negative bias state.

[0053] The absolute values ​​of the negative pulse voltages PL12 and PL13 supplied to the voltage V1 during periods P2 and P3 (sub-periods T2 and T4) are smaller than the absolute value of the negative pulse voltage PL11 supplied to the voltage V1 during period P1. The difference DF between these absolute values ​​is the same as the absolute value PP of the positive pulse voltage PL3 supplied to the voltage V1 during sub-periods T1, T3, and T5. In other words, in Figure 7, the voltage applied between the backing plate 220A and the substrate holding part 300A is the same as in Figure 6.

[0054] As described above, the bias state of the sputtering apparatus 10A may be controlled only by the voltage supplied to the backing plate 220A. The sputtering apparatus 10A according to the above-described modified example can also achieve the same effects as those of this embodiment.

[0055] 8 and 9, a sputtering method using a sputtering apparatus 10B according to one embodiment of the present invention will be described. The configuration of the sputtering apparatus 10B according to the third embodiment is similar to the configuration of the sputtering apparatus 10 according to the first embodiment. In the following description, a description of the same configuration as the sputtering apparatus 10 according to the first embodiment will be omitted, and differences will be mainly described. In the following description, when describing the same configuration as the first embodiment, reference will be made to FIGS. 1 to 4, and the alphabet "B" will be added after the reference numerals shown in these figures.

[0056] [3-1. Configuration of the Sputtering Apparatus] Figure 8 is a diagram showing a sputtering apparatus according to one embodiment of the present invention in a negative bias state. Unlike Figure 3, Figure 8 shows the central magnet 240B, peripheral magnet 250B, and yoke 260B below the backing plate 220B, but the configuration shown in Figure 8 is the same as the configuration shown in Figure 1. In other words, the configuration shown in Figure 8 is substantially the same as the configuration shown in Figure 3. However, as will be described in detail later, the central magnet 240B, peripheral magnet 250B, and yoke 260B are movable. The movement of these members is controlled by the control unit 600.

[0057] FIG. 9 is a diagram illustrating a sputtering apparatus according to an embodiment of the present invention in a positive bias state. As shown in FIG. 9 , in the positive bias state, the central magnet 240B, the peripheral magnet 250B, and the yoke 260B move away from the target 210B. The movement of the magnets reduces the magnetic field formed in front of the target 210B. Because this magnet movement is controlled by the control unit 600B, it can be said that the control unit 600B controls the magnetic field formed between the target 210B and the substrate holder 300B. Furthermore, in other words, the above configuration can be said to control the magnets so that the magnetic field in the positive bias state is smaller than the magnetic field in the negative bias state.

[0058] 8, when the magnet is close to the target 210B, the magnetic field formed on the surface of the target 210B is relatively strong, trapping many electrons in the plasma. As a result, a high-density plasma is formed in the region close to the target 210B, and more argon ions collide with the target 210B. As a result, the sputtering efficiency (film formation rate) is improved.

[0059] On the other hand, when the magnet is farther from the target 210B as shown in Figure 9, the magnetic field formed in front of the target 210B is relatively weak, reducing the effect of confining electrons in the plasma. As a result, the plasma density in the region near the target 210B decreases. Therefore, the concentration of nitrogen ions near the substrate 310B is relatively higher in the state shown in Figure 9 than in the state shown in Figure 8, which promotes the nitriding process of the thin film formed on the substrate 310B.

[0060] In other words, the control unit 600B controls the position of the magnet so that the distance between the backing plate 220B and the magnet when the sputtering apparatus 10B is controlled to a positive bias state is greater than the distance between the backing plate 220B and the magnet when the sputtering apparatus 10B is controlled to a negative bias state.

[0061] 10 and 11, a sputtering method using a sputtering apparatus 10C according to one embodiment of the present invention will be described. The configuration of the sputtering apparatus 10C according to the fourth embodiment is similar to the configuration of the sputtering apparatus 10 according to the first embodiment. In the following description, a description of the configuration similar to that of the sputtering apparatus 10 according to the first embodiment will be omitted, and differences will be mainly described. In the following description, when describing the configuration similar to that of the first embodiment, reference will be made to FIGS. 1 to 4, and the alphabet "C" will be added after the reference numerals shown in these figures.

[0062] [4-1. Configuration of the sputtering apparatus] Fig. 10 is a diagram showing a sputtering apparatus according to one embodiment of the present invention in a negative bias state. The sputtering apparatus 10C shown in Fig. 10 is similar to the sputtering apparatus 10 shown in Fig. 1 and Fig. 3, but differs from the sputtering apparatus 10 in that a movable magnetic field attenuation member 420C is provided between the backing plate 220C (target holding portion) and the magnets (central magnet 240C and peripheral magnet 250C).

[0063] The magnetic field attenuation member 420C shields the magnetic field formed by the magnet or attenuates the strength of the magnetic field. A magnetic shield or the like can be used as the magnetic field attenuation member 420C. The magnetic field attenuation member 420C is moved under the control of the control unit 600C. In other words, the control unit 600C controls the magnetic field attenuation member 420C so that the magnetic field when the sputtering apparatus 10C is controlled to a positive bias state is smaller than the magnetic field when the sputtering apparatus 10C is controlled to a negative bias state.

[0064] 10, when the sputtering apparatus 10C is controlled to a negative bias state, the magnetic field attenuation member 420C moves to a position outside the area between the backing plate 220C and the magnet. This control causes the magnet to form a magnetic field in front of the target 210C, resulting in the formation of a highly concentrated plasma in an area close to the target 210C. As a result, the sputtering efficiency (film formation rate) is improved.

[0065] On the other hand, as shown in Figure 11, when the sputtering apparatus 10C is controlled to a positive bias state, the magnetic field attenuation member 420C moves to the region sandwiched between the backing plate 220C and the magnet. This control causes the magnetic field generated by the magnet to be attenuated by the magnetic field attenuation member 420C. As a result, the plasma density in the region near the target 210C decreases. Therefore, the concentration of nitrogen ions near the substrate 310C is relatively higher in the state shown in Figure 11 than in the state shown in Figure 10, thereby accelerating the nitriding process of the thin film formed on the substrate 310C.

[0066] 12 and 13, a sputtering method using a sputtering apparatus 10D according to one embodiment of the present invention will be described. The configuration of the sputtering apparatus 10D according to the fifth embodiment is similar to the configuration of the sputtering apparatus 10 according to the first embodiment. In the following description, a description of the same configuration as the sputtering apparatus 10 according to the first embodiment will be omitted, and differences will be mainly described. In the following description, when describing the same configuration as the first embodiment, reference will be made to FIGS. 1 to 4, and the alphabet "D" will be added after the reference numerals shown in these figures.

[0067] [5-1. Configuration of the Sputtering Apparatus] Figure 12 is a diagram showing a sputtering apparatus according to one embodiment of the present invention in a negative bias state. The sputtering apparatus 10D shown in Figure 12 is similar to the sputtering apparatus 10 shown in Figures 1 and 3, but differs from the sputtering apparatus 10 in that a central electromagnet 430D and a peripheral electromagnet 440D are provided on the back surface of the backing plate 220D. A control unit 600D controls the current supplied to the central electromagnet 430D and the peripheral electromagnet 440D.

[0068] The central electromagnet 430D and the peripheral electromagnet 440D each include a coil. The winding direction of the coil of the central electromagnet 430D is opposite to that of the peripheral electromagnet 440D. Therefore, when current is supplied to these electromagnets, magnetic forces (magnetic poles) of opposite polarities are generated at the upper ends of the central electromagnet 430D and the peripheral electromagnet 440D. As a result, the same effect as that of the central magnet 240 and the peripheral magnet 250 shown in FIG. 1 can be obtained. The state shown in FIG. 12 is a state in which current is supplied to the central electromagnet 430D and the peripheral electromagnet 440D (ON state). Therefore, a magnetic field directed from the central electromagnet 430D toward the peripheral electromagnet 440D (or in the opposite direction) is formed on the front side of the target 210D. Because electrons in the plasma are confined by these electromagnets, a highly concentrated plasma region is formed on the front side of the target 210D.

[0069] FIG. 13 is a diagram illustrating a positive bias state in a sputtering apparatus according to an embodiment of the present invention. In FIG. 13, no current is supplied to the central electromagnet 430D and the peripheral electromagnet 440D, or the amount of current is smaller than that in the state shown in FIG. 12. By limiting the current supply to the central electromagnet 430D and the peripheral electromagnet 440D as shown in FIG. 13, the magnetic field formed in front of the target 210D is reduced. In other words, the control unit 600D controls these electromagnets so that the magnetic field in the positive bias state is smaller than that in the negative bias state. As a result, the plasma density in the region near the target 210D is reduced. Therefore, the concentration of nitrogen ions near the substrate 310D is relatively higher in the state shown in FIG. 13 than in the state shown in FIG. 12, thereby facilitating nitriding of the thin film formed on the substrate 310D.

[0070] The above-described embodiments of the present invention can be combined as appropriate as long as they are not mutually inconsistent. A product in which a person skilled in the art appropriately adds or deletes components or modifies designs, or adds or omits steps or modifies conditions, based on each embodiment, is also included within the scope of the present invention as long as it includes the gist of the present invention.

[0071] Even if there are other effects and advantages different from those brought about by the aspects of each of the above-mentioned embodiments, those that are clear from the description in this specification or that can be easily predicted by a person skilled in the art are naturally understood to be brought about by the present invention.

[0072] 10: Sputtering apparatus, 100: Chamber, 200: Target section, 210: Target, 220: Backing plate, 240: Central magnet, 250: Peripheral magnet, 260: Yoke, 300: Substrate holder, 310: Substrate, 400: Plasma region, 401402: Sheath region, 420C: Magnetic field attenuation member, 430D: Central electromagnet, 440D: Peripheral electromagnet, 600: Control section, 610: Position control section, 620: Moving mechanism, 630: Holding mechanism, P1, P2, P3: Period, PL1, PL2, PL3: Pulse voltage, T1, T2, T3, T4, T5: Sub-period

Claims

1. A sputtering apparatus comprising: a chamber; a substrate holder provided within the chamber for holding a substrate; a target holder for holding a target within the chamber so as to face the substrate; and a control unit configured to control a negative bias state in which the potential of the target holder relative to the substrate holder is negative, and a positive bias state in which the potential of the target holder relative to the substrate holder, wherein the control unit is configured to periodically control to the negative bias state by supplying a pulse voltage, and to control multiple periods between adjacent pulse voltages among multiple pulse voltages into a first period in which the positive bias state is controlled, and a second period in which the positive bias state is not controlled.

2. The sputtering apparatus of claim 1, wherein the control unit is configured to control the negative bias state once per cycle, and to control the positive bias state n times (n<m) during m cycles.

3. The sputtering apparatus of claim 1, wherein the control unit is configured to control the negative bias state once per cycle, and to control the positive bias state once per k cycles (k is an integer of 2 or more).

4. A sputtering apparatus as described in any one of claims 1 to 3, wherein the control unit is configured to supply a negative voltage to the target holding unit in the negative bias state, and to supply a negative voltage to the substrate holding unit in the positive bias state.

5. A sputtering apparatus as described in any one of claims 1 to 3, wherein the control unit is configured to supply a negative voltage to the target holding unit in the negative bias state, and to supply a positive voltage to the target holding unit in the positive bias state.

6. A sputtering apparatus comprising: a chamber; a substrate holder provided within the chamber for holding a substrate; a target holder for holding a target within the chamber so as to face the substrate; and a control unit configured to control a negative bias state in which the potential of the target holder relative to the substrate holder is negative, and a positive bias state in which the potential of the target holder relative to the substrate holder is positive, wherein the control unit is configured to control the positive bias state in the first period, the negative bias state in the second period, and the positive bias state in the third period, for a first period, a second period, and a third period that are consecutive on a time axis.

7. The sputtering apparatus according to claim 6, wherein the control unit is configured to supply a negative voltage to the target holding unit during the second period, and to supply a negative voltage to the substrate holding unit over the first period through the third period.

8. A sputtering apparatus according to claim 6 or 7, wherein the control unit is configured to supply a positive voltage to the target holding unit during the first period, to supply a negative voltage to the target holding unit during the second period, and to supply a positive voltage to the target holding unit during the third period.

9. A sputtering apparatus comprising: a chamber; a substrate holder provided within the chamber for holding a substrate; a target holder for holding a target within the chamber so as to face the substrate; a magnet provided on the opposite side of the substrate holder with the target holder as a reference; and a control unit configured to control a negative bias state in which the potential of the target holder relative to the substrate holder is negative and a positive bias state in which the potential of the target holder relative to the substrate holder, and configured to control the magnetic field formed between the target holder and the substrate holder by the magnet, wherein the control unit is configured to control the magnet so that the magnetic field in the positive bias state is smaller than the magnetic field in the negative bias state.

10. A sputtering apparatus as described in claim 9, wherein the control unit is configured to control the position of the magnet so that the distance between the target holder and the magnet in the positive bias state is greater than the distance between the target holder and the magnet in the negative bias state.

11. A sputtering apparatus as described in claim 9, further comprising a magnetic field attenuation member provided between the target holder and the magnet for attenuating the magnetic field generated by the magnet, and the control unit configured to control the magnetic field attenuation member so that the magnetic field in the positive bias state is smaller than the magnetic field in the negative bias state.

12. The sputtering apparatus according to claim 9, wherein the magnet includes an electromagnet, and the control unit is configured to control the electromagnet so that the magnetic field in the positive bias state is smaller than the magnetic field in the negative bias state.

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