Surface treatment device

Abstract

A magnetron sputtering device (10) comprises: a target (20) for discharging particles for forming a film; an insulating material (30a) in contact with the outer peripheral edge of the target; a case (40) that holds the outer peripheral edge of the insulating material and forms a ground potential; and a processed material (14) that is provided at a position facing the target and on which a film is formed by the particles discharged by the target. The insulating material has a first region (31) in contact with the outer peripheral edge of the target, a second region (32) that forms a step bottom section in which a side facing the processed material on a side in contact with the case is notched at a predetermined step depth over the entire circumference of the case, and a third region (33) in contact with the inner peripheral edge of the case.

Description

Surface Treatment Equipment

[0001] The present invention relates to a surface treatment apparatus for forming a film on a material to be treated, such as resin or glass.

[0002] 2. Description of the Related Art In a film forming apparatus using a magnetron sputtering method, an electrode equipped with a sputtering target (hereinafter simply referred to as a target) is used (see, for example, Patent Document 1).

[0003] Japanese Patent Application Laid-Open No. 2023-183725

[0004] In magnetron sputtering, insulation must be maintained between the target, to which a high voltage is applied, and the grounded case that holds the target in the deposition chamber. Therefore, a structure that maintains insulation by placing an insulating material between the target and the case is adopted. However, during the deposition process, particles (e.g., copper) ejected from the target may deposit on the surface of the insulating material, forming a conductive thin film (see Figure 7). This occurs because particles ejected from the same location on the target surface have a distribution of ejection angles, and therefore not all of the ejected particles are directed toward the target material, but rather scatter to the surrounding area and adhere to areas other than the target material. When a conductive film is formed on the insulating material that insulates the target from the case, current flows from the target to the case through this film, resulting in a so-called current leak. Furthermore, because the thickness of the current path (film thickness) is very thin, the current density increases, leading to abnormal discharges. If such abnormal discharges occur during the deposition process, the quality of the resulting film becomes unstable, resulting in quality variations.

[0005] The present invention has been made in consideration of the above, and aims to provide a surface treatment device that can prevent conduction between the target and the case due to the deposition of a film on the surface of an insulating material provided between the target and the case, thereby suppressing the occurrence of current leakage.

[0006] In order to solve the above-mentioned problems and achieve the object, the surface treatment apparatus of the present invention comprises a target that emits particles to be deposited, an insulating material that contacts the outer periphery of the target, a holding member that holds the outer periphery of the insulating material and is at ground potential, and a treated material that is positioned opposite the target and on which a film is formed by the particles emitted by the target, wherein the insulating material has a first region that contacts the outer periphery of the target, a second region on the side that contacts the holding member and faces the treated material, forming a step bottom that is cut out at a predetermined step depth around the entire circumference of the holding member, and a third region that contacts the inner periphery of the holding member.

[0007] The surface treatment device according to the present invention has the effect of preventing deposition of a film on the surface of an insulating material provided between a target and a case, thereby suppressing the occurrence of current leakage.

[0008] FIG. 1 is a diagram showing an example of a schematic configuration of a magnetron sputtering apparatus. FIG. 2 is a perspective view showing an example of a target electrode used in the magnetron sputtering apparatus of the embodiment. FIG. 3 is a cross-sectional view showing an example of the structure of the target electrode. FIG. 4 is a diagram showing the structure of bolts used to fasten various parts of the target electrode. FIG. 5 is a diagram showing an example of the shape of an insulating material provided in the target electrode. FIG. 6 is a side view and a top view showing an example of the overall shape of a target and an insulating material surrounding the target. FIG. 7 is a diagram showing an example of the shape of an insulating material provided in a target electrode of a comparative example. FIG. 8 is a diagram showing an example of a simulation result of the step depth of the insulating material. FIG. 9 is a diagram showing a modified example of a target holding structure.

[0009] Hereinafter, embodiments of a surface treatment device according to the present disclosure will be described in detail with reference to the drawings. Note that the present invention is not limited to these embodiments. Furthermore, the components in the following embodiments include those that are replaceable and easily conceivable by those skilled in the art, or those that are substantially the same.

[0010] (Schematic Configuration of Magnetron Sputtering Apparatus) A schematic configuration of a magnetron sputtering apparatus 10 according to an embodiment of the present disclosure will be described with reference to Fig. 1. Fig. 1 is a diagram showing an example of the schematic configuration of a magnetron sputtering apparatus.

[0011] The magnetron sputtering apparatus 10 deposits target particles 18 emitted from a target 20 placed opposite the workpiece 14 on the surface of the workpiece 14 placed inside a vacuum chamber 12, thereby producing a thin film of the target particles 18. The magnetron sputtering apparatus 10 is an example of a surface treatment apparatus in the present disclosure.

[0012] In the magnetron sputtering apparatus 10, the material to be processed 14 is, for example, a glass substrate, a silicon (Si) wafer, etc. The material to be processed 14 is held by a positive electrode 13.

[0013] The target 20 contains elements such as copper and aluminum, which are materials for the thin film. A magnet 22 is installed on the rear side of the target 20 opposite the surface facing the workpiece 14, and the target 20 and the magnet 22 are held in a case 40. The case 40 is an example of a holding member in the present disclosure.

[0014] A DC power supply 15 of, for example, about minus 700 volts is connected between the grounded positive electrode 13 and the target 20 (hereinafter referred to as the target electrode 50) held in an insulated state in the grounded case 40 on the target electrode 50 side.

[0015] An inert gas (e.g., argon gas) is supplied to the inside of the vacuum chamber 12 through a gas supply line 16. The supplied inert gas is excited by plasma generated by a high voltage applied between the positive electrode 13 and the target electrode 50, and becomes argon ions.

[0016] At this time, a magnet 22 installed on the back side of the target 20 generates a magnetic field in a direction perpendicular to the electric field near the electrode on the case 40 side. The generated magnetic field attracts electrons in the plasma, creating a space with high electron density near the target 20. Argon ions collide with the thus-created space with high electron density, further promoting ionization of the argon. The generated argon ions then collide with the surface of the target 20, knocking out target particles 18 (atoms and molecules) that make up the target 20, a process known as sputtering.

[0017] The target particles 18 ejected by sputtering reach the surface of the material 14 to be treated on the side of the positive electrode 13 and form a thin film of the target particles 18 on the surface of the material 14 to be treated.

[0018] After the thin film has been formed, the magnetron sputtering apparatus 10 opens the exhaust path 17 to exhaust the remaining gases in the chamber 12 and return the pressure inside the chamber 12 to atmospheric pressure.

[0019] Note that openable and closable valves and shutters (not shown) are installed between the gas supply path 16 and the chamber 12, and between the exhaust path 17 and the chamber 12. In the magnetron sputtering apparatus 10, first, the gas supply path 16 is closed and the exhaust path 17 is opened to evacuate the interior of the chamber 12. Then, both the gas supply path 16 and the exhaust path 17 are opened to supply, for example, argon gas into the interior of the chamber 12. Then, even while sputtering of the workpiece 14 is being performed, both the gas supply path 16 and the exhaust path 17 are opened to maintain the supply of argon gas. After sputtering of the workpiece 14 is completed, the gas supply path 16 is closed and the exhaust path 17 is opened to exhaust any remaining gas from the interior of the chamber 12. Then, after the residual gas has been exhausted, the gas supply path 16 is opened and the exhaust path 17 is closed, and air is introduced into the interior of the chamber 12, returning the interior of the chamber 12 to atmospheric pressure.

[0020] (General Structure of Target Electrode) The general structure of the target electrode 50 will be described with reference to Fig. 2. Fig. 2 is a perspective view showing an example of a target electrode used in the magnetron sputtering apparatus of the embodiment.

[0021] The target electrode 50 includes a target 20 , an insulating material 30 a , and a case 40 .

[0022] The target 20 is, for example, a rectangular plate containing target particles 18 that will be the material of the thin film to be formed on the surface of the workpiece 14. The target 20 contains, for example, copper, aluminum, or the like.

[0023] The insulating material 30a is formed so as to be in contact with the outer periphery of the target 20 and surrounds the outer periphery of the target 20. The insulating material 30a is, for example, Teflon (registered trademark) or the like. The shape of the insulating material 30a will be described in detail later (see FIG. 5).

[0024] The case 40 holds the periphery of the target 20 via the insulating material 30a and provides a ground potential. The case 40 is made of, for example, an aluminum alloy or stainless steel (SUS). Since the magnet 22 is installed near the case 40, the case 40 is made of a non-magnetic material that is not affected by the magnet 22. The connection structure between the target 20, insulating member 30, and case 40 will be described in detail below (see FIG. 3).

[0025] (Detailed Structure of Target Electrode) The detailed structure of the target electrode 50 will be described with reference to Fig. 3 and Fig. 4. Fig. 3 is a cross-sectional view showing an example of the structure of the target electrode. Fig. 4 is a diagram showing the structure of bolts used to fasten each part of the target electrode.

[0026] The case 40 and the insulating material 30a are fastened together by bolts 24a.

[0027] The target 20 is attached to the case 40 via the magnet case 23 that houses the magnet 22. More specifically, the target 20 is fastened to the magnet case 23 by bolts 24b. The magnet case 23 is fastened to the case 40 by bolts 24c. Therefore, the outer periphery of the target 20 is only in contact with the insulating material 30a and is not directly fastened to the insulating material 30a.

[0028] An insulating material 30b is inserted between the magnet case 23 and the case 40. The insulating material 30b is fastened to the case 40 by a bolt 24d.

[0029] Bolt 24a fastening insulator 30a to case 40, bolt 24d fastening insulator 30b to case 40, and bolt 24c fastening magnet case 23 to case 40 are all made of a thermoplastic resin called PEEK (Poly Ether Ether Ketone) to prevent electrical current from flowing through them. As shown in FIG. 4 , bolt 24a has a through hole 25 to allow air trapped in an air reservoir 26 formed at the bottom of the bolt hole to be discharged. Bolts 24b, 24c, and 24d also have through holes 25, just like bolt 24a.

[0030] (Detailed Shape of Insulator) The detailed shape of the insulator 30a used in the magnetron sputtering apparatus 10 will be described with reference to Fig. 5 and Fig. 6. Fig. 5 is a diagram showing an example of the shape of the insulator provided in the target electrode. Fig. 6 is a side view and a top view showing an example of the overall shape of the insulator provided in the target electrode.

[0031] Fig. 5 is a cross-sectional view in the thickness direction of the plate-shaped target 20. A first region 31 of an insulating material 30a shown in Fig. 6 is arranged on the outer periphery of the target 20 so as to be in complete contact with the target 20 throughout the thickness direction.

[0032] In addition, the insulating material 30a has a second region 32 formed on the side that contacts the case 40, that is, the side facing the workpiece 14 (see Figure 1), i.e., the positive side of the Z axis, which is cut out at a predetermined step depth D around the entire circumference, as shown in Figures 5 and 6.

[0033] The step depth D is determined so that when some of the target particles 18 slammed from the target 20 are deposited on the insulating material 30a to form a thin film 60a, the thin film 60a does not wrap around the depth of the step from the position of point Q in Figure 5 to the back of the step and reach the position of point S in Figure 5, which is the deepest position of the step depth D. More specifically, the step formed in the insulating material 30a is formed deeper than point R, the deepest point reached by the thin film 60a that has wrapped around the step. The method for determining the step depth D will be described in detail later (see Figure 8).

[0034] Furthermore, a third region 33 that contacts the inner peripheral edge of the case 40 is formed on the insulating material 30 a around the entire periphery outside the step.

[0035] When sputtering of the workpiece 14 is performed using the target electrode 50 formed including such insulating material 30a, a thin film 60a is formed on the surface of the insulating material 30a, as shown in Fig. 5. Also, a thin film 60b is formed on the surface of the case 40. Since the step is formed in the insulating material 30a as described above, the thin films 60a and 60b do not come into contact with each other. In other words, there is no electrical connection between the target 20 and the case 40 via the insulating material 30a. This ensures insulation between the target 20 and the case 40.

[0036] (Description of Target Electrode of Comparative Example) The operation of the target electrode 50a of the comparative example will be described with reference to Fig. 7. Fig. 7 is a diagram showing an example of the shape of the insulating material provided in the target electrode of the comparative example.

[0037] The insulating material 30c of the target electrode 50a does not have the steps that the insulating material 30a has. Therefore, some of the target particles 18 that are knocked out from the target 20 are deposited across the insulating material 30c and the case 40, thereby forming a thin film 60.

[0038] The thin film 60 thus formed provides electrical continuity between the target 20 and the case 40, and the thin film 60 forms a current path, which may cause current leakage.

[0039] As explained in FIG. 5, the magnetron sputtering apparatus 10 of this embodiment forms a step in the insulating material 30a to prevent current leakage due to accumulation of the target particles 18.

[0040] (Simulation of Step Depth) An example of the simulation result of the step depth D formed in the insulating material 30a will be described with reference to Fig. 8. Fig. 8 is a diagram showing an example of the simulation result of the step depth of the insulating material.

[0041] The horizontal axis in Fig. 8 represents the surface position of the insulating material 30a. More specifically, the horizontal axis in Fig. 8 represents the surface position of the insulating material 30a along points P, Q, R, and S in Fig. 5.

[0042] The vertical axis of Figure 8 shows the film formation rate (nm / min), i.e., the film thickness generated per unit time, calculated by the inventors of the present disclosure when using a target 20 containing copper (Cu). Since the film thickness generated per unit time is used, it is possible to infer the maximum continuous operation time that is acceptable. Note that the vertical axis of Figure 8 is a logarithmic scale to make the calculation results easier to understand.

[0043] As conditions for the calculation, argon gas was introduced into the chamber 12 at a flow rate of 116 sccm, and the pressure inside the chamber 12 was set to 0.41 Pa. The voltage applied between the positive electrode 13 and the target electrode 50 was set to −732 V.

[0044] The results of the calculations will be described below with reference to FIGS.

[0045] In the step upper region da (the region between points P and Q), which is the surface region of the insulating material 30a, copper knocked out from the target 20 is deposited almost uniformly, so that a thin film is formed at a film formation rate exceeding 1 nm / min.

[0046] In the upper region of the side surface of the step of the insulating material 30a, i.e., the region between points Q and R, the film formation rate monotonically decreases toward the depth of the step. This region forms a film formation wraparound region db where copper knocked out from the target 20 wraps around the side surface of the step to form a thin film.

[0047] In the lower region of the side surface of the step of the insulating material 30a, i.e., the region between point R and point S, which is the deepest part of the step, the film formation rate is below approximately 0.01 nm / min. This region can be regarded as a region where almost no thin film is formed, so a film deposition prevention region dc is formed.

[0048] At the bottom of the step of the insulating material 30a, i.e., the region on the positive side of the X axis from point S, deposition beyond the deposition prevention region dc is expected to occur. Note that the side and bottom of the step in Figure 8 correspond to the second region 32 described above.

[0049] Based on these calculation results, the inventors of the present disclosure concluded that if the step depth D is set deeper than the position of point R (for example, approximately 22 mm or more), it is possible to form a film deposition prevention area dc in which almost no thin film is formed.

[0050] These calculation results are merely examples, and will differ depending on the conditions set when performing the film formation process. Therefore, it is necessary to perform calculations according to the conditions under which the film is actually formed.

[0051] (Modification of the embodiment) A modification of the embodiment will be described with reference to Fig. 9. Fig. 9 is a diagram showing a modification of the target holding structure.

[0052] In the previous embodiment, an example was described in which a step was formed in the insulating material 30a that holds the target 20 in the case 40, but the same effect can be obtained by providing a step in the case itself.

[0053] 9 includes a target 20, an insulating material 30c, and a case 40a. The insulating material 30c is disposed on the outer periphery of the target 20 so as to be in complete contact with the target 20 throughout its thickness.

[0054] The outer periphery of the insulating material 30c is positioned in contact with the case 40a, but the side of the case 40a that contacts the insulating material 30c, facing the workpiece 14 (see FIG. 1), i.e., the positive Z-axis side, is notched along the entire periphery to form a step. A target electrode 50b having this structure also achieves the same effects as those described in the embodiment. That is, a thin film 60a is formed on the insulating material 30c and a thin film 60b is formed on the case 40a, but the thin film 60a and the case 40a do not contact each other, thereby preventing current leakage between the target 20 and the case 40a. The depth of the step is appropriately determined by performing a simulation similar to that described above. Alternatively, a notch may be provided on the side of the insulating material 30c facing the case 40a to form a single notch integrated with the notch in the case 40a.

[0055] It is possible to form a step by forming a space between the target 20 and the case 40 where no insulating material exists, but this configuration is not desirable because the target 20 and the case 40, which are conductive to each other, would be facing each other with a gap between them, which could cause discharge between the tip of the target 20 and the tip of the case 40, for example.

[0056] Furthermore, in the previous embodiment, an example of a magnetron sputtering apparatus 10 that sputters the workpiece 14 has been described, but the scope of application of the surface treatment apparatus of the present disclosure is not limited to this. For example, the present disclosure may be applied to a so-called plasma treatment apparatus that uses plasma generated inside a chamber 12 to modify, clean, or otherwise modify the surface of a workpiece placed at the position of the target 20 described in the embodiment.

[0057] (Operation and Effects of the Embodiment) As described above, the magnetron sputtering apparatus 10 (surface treatment apparatus) of the embodiment includes the target 20 that emits particles to be used for film formation, the insulating material 30a in contact with the outer periphery of the target 20, the case 40 (holding member) that holds the outer periphery of the insulating material 30a and provides ground potential, and the workpiece 14 on which a film is formed by the particles emitted by the target 20. The insulating material 30a has a first region 31 in contact with the outer periphery of the target 20, a second region 32 on the side that contacts the case 40 and faces the workpiece 14, the second region 32 forming a stepped bottom portion cut out at a predetermined step depth D around the entire circumference of the case 40, and a third region 33 in contact with the inner periphery of the case 40. Therefore, electrical conduction between the target 20 and the case 40 due to deposition of a film on the surface of the insulating material 30a provided between the target 20 and the case 40 can be prevented, and the occurrence of current leakage can be suppressed.

[0058] Furthermore, in the magnetron sputtering apparatus 10 (surface processing apparatus) of the embodiment, the step depth D is set to be deeper than the wraparound amount of the thin film formed in the second region 32 when a film is formed on the workpiece 14 by the target 20. Therefore, electrical conduction between the target 20 and the case 40 due to deposition of a film on the surface of the insulating material 30a provided between the target 20 and the case 40 is prevented, and the occurrence of current leakage can be suppressed.

[0059] Furthermore, the surface treatment apparatus of the embodiment is a device for performing plasma treatment or sputtering treatment, and therefore can be widely applied to various types of surface treatment apparatus.

[0060] A magnetron sputtering apparatus 10 (surface treatment apparatus) according to a modified embodiment includes a target 20 that emits particles to be deposited, an insulating material 30c that contacts the outer periphery of the target 20, a case 40a (holding member) that holds the outer periphery of the insulating material 30c and establishes ground potential, and a workpiece 14 that is disposed opposite the target 20 and on which a film is formed by the particles emitted by the target 20. The side of the case 40a that contacts the insulating material 30c and faces the workpiece 14 forms a stepped bottom that is cut out at a predetermined step along the entire inner periphery of the case 40a. This prevents electrical continuity between the target 20 and the case 40a due to deposition of a film on the surface of the insulating material 30c disposed between the target 20 and the case 40a, thereby suppressing current leakage.

[0061] Although the embodiments of the present invention have been described above, the above-described embodiments are presented as examples and are not intended to limit the scope of the present invention. This novel embodiment can be embodied in various other forms. Furthermore, various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. Furthermore, this embodiment is included within the scope and spirit of the invention, and is also included in the scope of the invention and its equivalents as defined in the claims.

[0062] REFERENCE SIGNS LIST 10 Magnetron sputtering apparatus (surface treatment apparatus) 12 Chamber 13 Positive electrode 14 Material to be treated 15 DC power supply 16 Gas supply path 17 Exhaust path 18 Target particles 20 Target 22 Magnet 23 Magnet case 24a, 24b, 24c, 24d Bolt 25 Through hole 26 Air reservoir 30a, 30b, 30c Insulating material 31 First region 32 Second region 33 Third region 40, 40a Case (holding member) 50, 50a, 50b Target electrode 60, 60a, 60b Thin film D Step depth da Step upper region db Film formation wraparound region dc Film deposition prevention region

Claims

1. A surface treatment apparatus comprising: a target that emits particles to be used for film formation; an insulating material in contact with the outer periphery of the target; a holding member that holds the outer periphery of the insulating material and is at ground potential; and a treated material that is provided opposite the target and on which a film is formed by the particles emitted by the target, wherein the insulating material has a first region in contact with the outer periphery of the target, a second region on the side that contacts the holding member and faces the treated material, forming a step bottom that is cut out at a predetermined step depth around the entire circumference of the holding member, and a third region in contact with the inner periphery of the holding member.

2. The surface processing apparatus according to claim 1, wherein the depth of the step is set to be deeper than the wrap-around amount of a thin film formed in the second region when a film is formed on the processing object by the target.

3. A surface treatment device comprising: a target that emits particles to be used for film formation; an insulating material in contact with the outer periphery of the target; a holding member that holds the outer periphery of the insulating material and is at ground potential; and a treated material that is provided opposite the target and on which a film is formed by the particles emitted by the target, wherein the side of the holding member that comes into contact with the insulating material and faces the treated material forms a stepped bottom that is cut out at a predetermined step around the entire inner periphery of the holding member.

4. The surface treatment device according to claim 1 or 2, wherein the surface treatment device performs plasma treatment or sputtering treatment.

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