Film deposition apparatus and film deposition method

Abstract

To provide a film deposition apparatus and a film deposition method capable of relieving stress differences in films deposited by magnetron sputtering.SOLUTION: A film deposition apparatus comprises a chamber, a plurality of magnets, and a control part. The plurality of magnets are arranged on the opposite side to a film deposition object of a target having a target surface facing the film deposition object in the chamber, extended in a first direction parallel to the target surface, and arrayed along in a second direction parallel to the target surface and perpendicular to the first direction. The control part switches between a first state where the plurality of magnets form a magnetic field which confines plasma of a sputter gas at the central part in the second direction of the target surfaces and a second state where the plurality of magnets form a magnetic field which confines plasma of a sputter gas at both ends in the second direction of the target surfaces, by moving the plurality of magnets.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to a film formation apparatus and a film formation method using magnetron sputtering. [Background technology]

[0002] In sputtering, a sputtering gas introduced into a vacuum is turned into plasma by discharging the sputtering gas, and the generated ions collide with a target to generate sputtered particles, which are then deposited on the object to be deposited. Magnetron sputtering uses a magnet placed near the target to enclose electrons in a magnetic field, creating a high-density plasma region near the target, allowing ions to efficiently collide with the target, thereby enabling high-speed deposition (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2020-200520 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in magnetron sputtering systems such as those described in Patent Document 1, the stress distribution in the deposited film becomes a problem. If the object to be deposited is deformed, such as warped, due to uneven stress distribution, it may interfere with a mask or equipment for subsequent processes, or cause misalignment during subsequent processes. This can affect the reliability of display panels, for example.

[0005] In view of the above circumstances, an object of the present invention is to provide a film deposition apparatus and a film deposition method that can reduce the stress difference in a film deposited by magnetron sputtering. [Means for solving the problem]

[0006] To achieve the above object, a film forming apparatus according to one aspect of the present invention includes a chamber, a plurality of magnets, and a control unit. The multiple magnets are positioned on the opposite side of the target to be film-formed within the chamber, having a target surface facing the target to be film-formed, and are extended in a first direction parallel to the target surface and arranged along a second direction parallel to the target surface and perpendicular to the first direction. The control unit switches between a first state in which the multiple magnets form a magnetic field that confines the plasma of the sputtering gas at the center of the target surface in the second direction, and a second state in which the multiple magnets form a magnetic field that confines the plasma of the sputtering gas at both ends of the target surface in the second direction, by moving the multiple magnets.

[0007] The control unit may switch between the first state and the second state by moving the plurality of magnets along the second direction.

[0008] The control unit may place the plurality of magnets on the opposite side of the central portion from the film-forming target to set the first state, and place the magnets on the opposite side of the end portions from the film-forming target to set the second state.

[0009] The control unit may switch between the first state and the second state by moving the magnet along a direction perpendicular to the first direction and the second direction.

[0010] The control unit may set the magnets located at both ends in the second direction among the plurality of magnets to the first state by moving them further away from the target surface than the magnets located in the center in the second direction among the plurality of magnets, and may set the magnet located in the center to the second state by moving it further away from the target surface than the magnets located at the both ends.

[0011] The control unit may arrange the multiple magnets so that in the first state, the distance between the magnet located in the center and the target surface is 100 mm or less and the distance between the magnets located at both ends and the target surface is 120 mm or more, and may arrange the multiple magnets so that in the second state, the distance between the magnet located in the center and the target surface is 120 mm or more and the distance between the magnets located at both ends and the target surface is 100 mm or less.

[0012] In order to achieve the above object, one aspect of the present invention provides a film formation method for sputtering a film on a film formation target using a film formation apparatus including: a chamber; and a plurality of magnets that are disposed in the chamber on an opposite side of the film formation target from a target having a target surface facing the film formation target, the magnets extending in a first direction parallel to the target surface, and arranged along a second direction parallel to the target surface and perpendicular to the first direction, The magnets are switched between a first state in which they form a magnetic field that confines the plasma of the sputtering gas at the center of the target surface in the second direction, and a second state in which they form a magnetic field that confines the plasma of the sputtering gas at both ends of the target surface in the second direction. [Effects of the Invention]

[0013] As described above, according to the present invention, it is possible to provide a film deposition apparatus and a film deposition method that can reduce the stress difference in a film deposited by magnetron sputtering. [Brief explanation of the drawings]

[0014] [Figure 1] 1 is a schematic diagram of a film forming apparatus according to an embodiment of the present invention. [Figure 2] FIG. 2 is a schematic diagram illustrating a partial configuration of the film forming apparatus. [Figure 3] FIG. 2 is a schematic diagram illustrating a partial configuration of the film forming apparatus. [Figure 4] FIG. 2 is a schematic diagram showing film formation by the film formation apparatus. [Figure 5] FIG. 2 is a schematic diagram of the film forming apparatus in a first state. [Figure 6] FIG. 4 is a schematic diagram of the film forming apparatus in a second state. [Figure 7] FIG. 3 is a schematic view of a film formed in the first state of the film forming apparatus. [Figure 8] FIG. 4 is a schematic view of a film formed in the second state of the film forming apparatus. [Figure 9] FIG. 4 is a schematic diagram illustrating another example of the first state of the film forming apparatus. [Figure 10] FIG. 4 is a schematic diagram illustrating another example of the second state of the film forming apparatus. [Figure 11] This is a simulation result of electron tracking when the distance between the magnet and the target surface is 100 mm in the above film deposition apparatus. [Figure 12] The results are simulation results of electronic tracking when the distance is 120 mm. [Figure 13] The results are simulation results of electronic tracking when the distance is 130 mm. [Figure 14] The results are simulation results of electronic tracking when the distance is 150 mm. [Figure 15] FIG. 2 is a schematic diagram of another configuration of the film forming apparatus. [Figure 16] FIG. 2 is a schematic diagram of another configuration of the film forming apparatus. [Figure 17] FIG. 2 is a schematic diagram of another configuration of the film forming apparatus. DETAILED DESCRIPTION OF THE INVENTION

[0015] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0016] [About the deposition equipment] A film formation apparatus according to this embodiment will be described. FIG. 1 is a schematic diagram of a film formation apparatus 100 according to this embodiment, and FIGS. 2 and 3 are schematic diagrams of a portion of the film formation apparatus 100. As shown in FIG. 1, the film formation apparatus 100 includes a vacuum chamber 101, a target 102, a backing plate 103, a magnet unit 104, an adhesion prevention plate 105, a gas supply unit 106, and a control unit 107. A film formation target 150 is disposed in the vacuum chamber 101. Hereinafter, the surface of the film formation target 150 will be referred to as a film formation target surface 150a.

[0017] Vacuum chamber 101 defines a sputtering space 111 therein. A gas supply unit 106 and an exhaust unit (not shown) are connected to vacuum chamber 101. Gas supply unit 106 supplies sputtering gas to sputtering space 111. The exhaust unit includes exhaust means such as a vacuum pump, and evacuates sputtering space 111 to a vacuum.

[0018] The target 102 is placed in the sputtering space 111 and generates sputtered particles. The target 102 is plate-shaped as shown in Fig. 2, and faces a film-forming target surface 150a of the film-forming target 150. Hereinafter, the surface of the target 102 facing the film-forming target surface 150a will be referred to as the target surface 102a, and the opposite surface will be referred to as the back surface 102b.

[0019] The target surface 102a is planar, and hereinafter, a direction parallel to the target surface 102a is referred to as the X direction, and a direction parallel to the target surface 102a and perpendicular to the X direction is referred to as the Y direction. The direction perpendicular to the X and Y directions is referred to as the Z direction. As shown in FIG. 2, the target 102 may be rectangular with the X direction as the short side direction and the Y direction as the long side direction, but may have other shapes. The material of the target 102 is not particularly limited, and may be molybdenum (Mo), aluminum (Al), titanium (Ti), copper (Cu), or the like.

[0020] The backing plate 103 is located on the back side of the target 102 and supports the target 102. Note that the backing plate 103 is not shown in Fig. 2. As shown in Fig. 1, the target 102 is fixed with its back surface 102b in contact with the backing plate 103. The backing plate 103 is conductive, is connected to a sputtering power supply 171, and functions as a cathode.

[0021] The magnet unit 104 is disposed on the opposite side of the backing plate 103 from the target 102, as shown in Fig. 3. The number of magnet units 104 is not particularly limited, and may be determined according to the size of the film-forming target 150. As shown in Figs. 2 and 3, the magnet unit 104 includes a yoke 121 and magnets 122. The magnets 122 extend in the Y direction and are arranged along the X direction, forming a magnetic field on the target surface 102a.

[0022] Specifically, the magnet 122 includes an N-pole magnet 123 and an S-pole magnet 124, and as shown in FIG. 2, the N-pole magnet 123 surrounds the S-pole magnet 124. Note that the magnetic poles of the N-pole magnet 123 and the S-pole magnet 124 may be opposite. The magnet units 104 are configured so that their positions can be moved by a drive mechanism (not shown). The drive mechanism is not particularly limited, but may be, for example, a ball screw and its rotation drive source. As shown in FIG. 3, the distance between the magnet 122 and the target surface 102a is defined as distance L.

[0023] 1, the adhesion shield 105 is disposed between the target 102 and the inner wall of the vacuum chamber 101, and prevents sputtered particles from adhering to the inner wall of the vacuum chamber 101. The adhesion shield 105 is also connected to a sputtering power supply 171 and functions as an anode.

[0024] The gas supply unit 106 discharges sputtering gas supplied from a gas source into the sputtering space 111. This sputtering gas includes a sputtering gas and a reactive gas. The sputtering gas is a gas that is ionized by discharge, such as argon (Ar). The reactive gas is a gas that undergoes a chemical reaction with particles of the target material resulting from the collision of the ions, such as oxygen (O2). The gas supply unit 106 is preferably arranged so that the sputtering gas is supplied onto the film formation target surface 150a, as shown in FIG. 1.

[0025] The control unit 107 includes a sputtering power supply 171 and a magnet driving unit 172. The sputtering power supply 171 is a power supply for discharging power supplied between the anode and the cathode, and may be a DC (Direct Current) power supply, or a high frequency power supply such as an RF (Radio Frequency) power supply or a VHF (Very High Frequency) power supply.

[0026] The magnet driving unit 172 moves the position of the magnet unit 104. Specifically, the magnet driving unit 172 controls the rotation angle of the rotation driving source to operate the ball screw by a predetermined distance, thereby moving the position of the magnet unit 104. The magnet driving unit 172 may also move the position of the magnet unit 104 by other methods. Details of the operation of the magnet driving unit 172 will be described later.

[0027] The film forming apparatus 100 has the above-described configuration. The film forming apparatus 100 may have other configurations instead of or in addition to the above-described configurations.

[0028] [Film formation method] A film formation method using the film formation apparatus 100 will be described. Fig. 4 is a schematic diagram showing the film formation method using the film formation apparatus 100. In this film formation method, first, the sputtering space 111 is evacuated to a vacuum by an exhaust unit (not shown). After the sputtering space 111 is sufficiently depressurized, a sputtering gas is supplied to the sputtering space from the gas supply unit 106.

[0029] Next, while each magnet unit 104 is oscillated by the magnet driving unit 172 as shown by the arrows, the sputtering power supply 171 starts to supply discharge power between the cathode (target 102, etc.) and the anode (adhesion shield 105). This discharge power converts the sputtering gas into plasma. This plasma is confined within the magnetic field generated by the magnet 122, and high-density plasma P is formed on the target surface 102a at a position close to each magnet unit 104, as shown in FIG.

[0030] The ions forming the high-density plasma P collide with the target surface 102a, scattering sputter particles, which are particles of the target material. The scattered sputter particles react with the reactive gas and deposit on the film-forming surface 150a, forming a film. The supply of discharge power is continued in this state until the desired film thickness is reached. By performing sputtering while oscillating the magnet unit 104 as described above, it is possible to evenly erode the target surface 102a due to sputtering and to homogenize the film quality.

[0031] [Switching between the first and second states] The film deposition apparatus 100 performs film deposition as described above, but film deposition can be performed while switching between the "first state" and "second state" described below as necessary.

[0032] FIG. 5 is a schematic diagram of the first state. As shown in the figure, the first state is a state in which the magnet 122 confines plasma of the sputtering gas at the center of the target surface 102a in the X direction, forming a magnetic field that generates high-density plasma P. As shown in FIG. 5, the first state can be achieved by arranging the magnet unit 104 at the center of the back surface 102b in the X direction, facing the backing plate 103 therebetween. Note that magnet units 104 other than the four magnet units 104 illustrated in FIG. 5 may not be provided, and may not function as magnets that generate high-density plasma P, as will be described later. Furthermore, the number of magnet units 104 that form the first state is not limited to four, and may be one or more.

[0033] FIG. 6 is a schematic diagram of the second state. As shown in the figure, the second state is a state in which magnets 122 confine plasma of the sputtering gas at both ends of the target surface 102a in the X direction, forming a magnetic field that generates high-density plasma P. As shown in FIG. 6, the second state can be achieved by arranging magnet units 104 at both ends of the back surface 102b in the X direction in positions facing each other with the backing plate 103 interposed therebetween. Note that magnet units 104 other than the four magnet units 104 shown in FIG. 6 may not be provided, and may not function as magnets that generate high-density plasma P, as will be described later. Furthermore, the number of magnet units 104 that form the second state is not limited to two, but may be one or more.

[0034] The magnet driver 172 can switch between the first state and the second state by moving the magnet unit 104 along the X direction. Specifically, as shown in FIG. 5, the magnet driver 172 positions the magnet unit 104 at the center in the X direction to set the first state. In this state, the magnet driver 172 oscillates the magnet unit 104 as shown by the arrows in FIG. 5, and film formation is performed. After film formation for a predetermined time, the magnet driver 172 moves the magnet unit 104 along the X direction to both ends in the X direction, and sets the second state as shown in FIG. 6. In this state, the magnet driver 172 oscillates the magnet unit 104 as shown by the arrows in FIG. 6, and film formation is further performed. After film formation for a predetermined time, film formation is completed.

[0035] As shown in Fig. 4, if the discharge power and power density are 100% when eight magnet units 104 are used, then even if the discharge power is 100% when four magnet units 104 are used, the power density will be 200% as shown in Fig. 5 and Fig. 6. Furthermore, if the oscillation speed when eight magnet units 104 are used is 100%, then the oscillation speed when four magnet units 104 are used is preferably 100 to 200%.

[0036] It is possible to reduce the difference in stress (hereinafter referred to as film stress) of the film formed on the film formation target surface 150a by switching the film formation apparatus 100 between the first state and the second state. The reason for this is that the film stress of a film formed by magnetron sputtering depends on the ratio of the incident angle components incident on the film formation target surface in the early stage of film formation, and if the oblique incident component is greater than the perpendicular incident component, it becomes tensile stress, and if the perpendicular incident component is greater than the oblique incident component, it becomes compressive stress.

[0037] In general magnetron sputtering, tensile stress occurs at the center of the film because sputtered particles arrive from all around, while compressive stress occurs at the periphery of the film because the direction in which the sputtered particles arrive is limited. Note that the oblique incidence component is the component at an angle of incidence to the film-forming surface of more than 60°, and the perpendicular incidence component is the component at an angle of incidence of less than 60°.

[0038] In contrast, in the film formation method according to the present invention, film formation proceeds as follows: Figures 7 and 8 are schematic diagrams of a film formed on the film formation target surface 150a, with (a) showing the central portion of the film formation target surface 150a and (b) showing the film on the outer periphery thereof.

[0039] By first performing film formation in the first state, a film M1 is formed in the center of the film formation target surface 150a, as shown in FIG. 7(a). In the first state, the magnet unit 104 is positioned in the center, so the sputtered particles incident on the center of the film formation target surface 150a have a large perpendicular incidence component, and the film M1 becomes a film with compressive stress. Furthermore, as shown in FIG. 7(b), no film is formed on the outer periphery of the film formation target surface 150a. This is because in the first state, the magnet unit 104 is separated from the outer periphery of the film formation target surface 150a, so the sputtered particles do not reach the outer periphery of the film formation target surface 150a.

[0040] Next, by performing film formation in the second state, as shown in FIG. 8(a), a film M2 is formed on a film M1 in the center of the film formation target surface 150a. In the second state, because the magnet units 104 are located at both ends, the sputtered particles incident on the center of the film formation target surface 150a have a large oblique incidence component, and film M2 becomes a film with tensile stress. However, because the magnet units 104 are separated from the center of the film formation target surface 150a in the second state, the film M2 has a small thickness. Furthermore, as shown in FIG. 8(b), a film M3 is formed on the outer periphery of the film formation target surface 150a. Because the sputtered particles incident on the outer periphery of the film formation target surface 150a have a large perpendicular incidence component, film M3 becomes a film with compressive stress.

[0041] In this manner, a film M4 is formed in the center of the film-forming target surface 150a, with film M2 stacked on film M1. Film M1 has compressive stress, and film M2 has tensile stress, but because film M1 is thick and is the lower layer, film M4 has compressive stress. On the other hand, film M3 is a film with compressive stress as described above. Therefore, the film formed on the film-forming target surface 150a has compressive stress as a whole, and the stress difference within the surface is small.

[0042] [Other ways to switch between the first and second states] The first state and the second state can also be switched as follows.

[0043] 9 is a schematic diagram of the first state. As shown in the figure, the first state can also be achieved by positioning the magnet units 104 facing both ends of the back surface 102b in the X direction farther from the target 102 than the magnet unit 104 facing the center of the back surface 102b. When the magnet units 104 are positioned farther from the target 102, the magnetic field generated by the magnets 122 does not reach the target surface 102a, and the magnets 122 no longer function as magnets for generating high-density plasma P. As shown in the figure, the distance between the magnet 122 approaching the target 102 and the target surface 102a is defined as distance L1, and the distance between the magnet 122 distant from the target 102 and the target surface 102a is defined as distance L2.

[0044] 10 is a schematic diagram of the second state. As shown in the figure, the second state can also be achieved by positioning the magnet unit 104 facing the center of the back surface 102b in the X direction farther from the target 102 than the magnet units 104 facing both ends of the back surface 102b. As in FIG. 9, the distance between the magnet 122 approaching the target 102 and the target surface 102a is defined as distance L1, and the distance between the magnet 122 distant from the target 102 and the target surface 102a is defined as distance L2.

[0045] In the first and second states, the distance L1 is preferably 100 mm or less, and the distance L2 is preferably 120 mm or more. Figures 11 to 14 show simulation results of electron tracking on the target surface 102a for each distance L between the magnet 122 and the target surface 102a, with each figure (a) showing a view from the Y direction and each figure (b) showing a view from the Z direction. In each figure, the electron trajectory is shown with a white line. The potential of the target 102 is -600 V in all cases. Figure 11 shows the results when the distance L is 100 mm. It can be seen that electrons are focused on the target surface 102a, and a magnetic field is formed on the target surface 102a by the magnet 122.

[0046] Figure 12 shows the results when the distance L is 120 mm. It can be seen that the electrons are not sufficiently focused on the target surface 102a, and that the magnetic field generated by the magnet 122 is not sufficient on the target surface 102a. Figure 13 shows the results when the distance L is 130 mm, and it can also be seen that the magnetic field generated by the magnet 122 is not sufficient on the target surface 102a.

[0047] 14 shows the results when the distance L is 150 mm, and it can be seen that no magnetic field is formed on the target surface 102a by the magnet 122. From the above, by setting the distance L1 to 100 mm or less and the distance L2 to 120 mm or more, it is possible to switch the magnet 122 whose magnetic field reaches the target surface 102a.

[0048] In this way, the magnet driving unit 172 can switch between the first state and the second state by moving the magnet unit 104 along the Z direction. Specifically, as shown in Fig. 9, the magnet driving unit 172 brings the central magnet unit 104 closer to the target 102 and moves the magnet units 104 at both ends away from the target 102 to establish the first state. In this state, the magnet driving unit 172 oscillates the magnet unit 104 as shown by the arrows in Fig. 9, and film formation is performed.

[0049] After a predetermined period of film formation, the magnet driving unit 172 moves the central magnet unit 104 away from the target 102 and moves the magnet units 104 at both ends closer to the target 102, thus entering the second state as shown in Figure 10. In this state, the magnet driving unit 172 continues to oscillate the magnet units 104 as shown by the arrows in Figure 10, and further film formation is carried out. After a predetermined period of film formation, film formation is completed.

[0050] In this way, the magnet driving unit 172 can switch between the first state and the second state by moving the magnet unit 104 along the Z direction. In this case as well, due to the incident angle of the sputtered particles incident on the film-forming target surface 150a as shown in Figures 7 and 8, the film formed on the film-forming target surface 150a has compressive stress as a whole, and the stress difference within the surface can be reduced.

[0051] [Other arrangements of the magnet unit] In the film formation apparatus 100, the magnet unit 104 can also be arranged as follows. Figures 15 to 17 are schematic diagrams showing the arrangement of the magnet unit 104. The magnet driving unit 172 moves the magnet unit 104 in the X direction, thereby switching between the arrangement of the magnet unit 104 shown in Figure 15 and the arrangement of the magnet unit 104 shown in Figure 16. With this configuration, the film formed on the film formation target surface 150a has compressive stress as a whole, and the stress difference within the surface is small.

[0052] 17, the magnet driving section 172 can widen the interval between the magnet units 104, thereby halving the pitch of the magnet units 104. This configuration can improve the controllability of the distribution of the film formed on the film formation target surface 150a.

[0053] [Embodiments of the present invention] Although the embodiments of the present invention have been described above, it is needless to say that the present invention is not limited to the above-described embodiments and various modifications can be made. At least two of the characteristic features described in the above-described embodiments can be arbitrarily combined. [Explanation of symbols]

[0054] 100...Film deposition equipment 101...Vacuum chamber 102...Target 103...Backing plate 104...Magnet unit 105…Adhesion prevention plate 106...Gas supply unit 107...Control unit 111...Sputter space 121…York 122...Magnet 123...North pole magnet 124…S pole magnet 150...Film formation target 171...Sputter power supply 172...Magnet drive unit

Claims

1. a chamber; a plurality of magnets disposed in the chamber on an opposite side of a target having a target surface facing the target, the magnets extending in a first direction parallel to the target surface and arranged along a second direction parallel to the target surface and perpendicular to the first direction; a control unit that switches between a first state in which the plurality of magnets form a magnetic field that confines plasma of the sputtering gas at a central portion of the target surface in the second direction and a second state in which the plurality of magnets form a magnetic field that confines plasma of the sputtering gas at both ends of the target surface in the second direction, by moving the plurality of magnets; A film forming apparatus comprising:

2. 2. The film forming apparatus according to claim 1, The control unit switches between the first state and the second state by moving the plurality of magnets along the second direction. Film deposition equipment.

3. 3. The film forming apparatus according to claim 2, The control unit places the plurality of magnets in the first state by arranging them on the opposite side of the film-forming target at the center portion, and places them on the opposite side of the film-forming target at both ends, and places them in the second state. Film deposition equipment.

4. 2. The film forming apparatus according to claim 1, The control unit switches between the first state and the second state by moving the magnet along a direction perpendicular to the first direction and the second direction. Film deposition equipment.

5. 5. The film forming apparatus according to claim 4, The control unit sets the magnets located at both ends in the second direction among the plurality of magnets to be farther away from the target surface than a magnet located at a center in the second direction among the plurality of magnets, to be in the first state, and sets the magnet located at the center to be farther away from the target surface than the magnets located at the both ends, to be in the second state. Film deposition equipment.

6. 6. The film forming apparatus according to claim 5, The control unit arranges the magnets so that in the first state, the distance between the magnet located in the center and the target surface is 100 mm or less and the distance between the magnets located at both ends and the target surface is 120 mm or more, and arranges the magnets so that in the second state, the distance between the magnet located in the center and the target surface is 120 mm or more and the distance between the magnets located at both ends and the target surface is 100 mm or less. Film deposition equipment.

7. A film formation method for sputtering a film on a film formation target using a film formation apparatus including: a chamber; and a plurality of magnets disposed in the chamber on an opposite side of the film formation target from a target having a target surface facing the film formation target, the magnets extending in a first direction parallel to the target surface, and arranged along a second direction parallel to the target surface and perpendicular to the first direction, a first state in which the plurality of magnets form a magnetic field that confines the plasma of the sputtering gas at a central portion of the target surface in the second direction, and a second state in which the plurality of magnets form a magnetic field that confines the plasma of the sputtering gas at both ends of the target surface in the second direction; Film formation method.

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