Method for manufacturing magnetic thin film laminate and apparatus used therefor

Abstract

To provide a method and apparatus for manufacturing a magnetic thin film laminate, capable of reducing a film deposition time than before.SOLUTION: A method for manufacturing a magnetic thin film laminate including a magnetic film layer 10 and an oxide film layer 11 includes: a magnetic film formation step of depositing a magnetic film 13 on a film-deposition object 12 by electrolytic plating or electroless plating to form the magnetic film layer 10; and an oxide film formation step of forming the oxide film layer 11 on the film-deposition object 12. The oxide film formation step includes: film-deposition step of depositing a film 14 to be oxidized by the electrolytic plating or electroless plating on the magnetic film 13; and an oxidation step of oxidizing the film 14 to be oxidized at an approximately atmospheric pressure to deposit the oxide film 15.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a method and an apparatus for manufacturing a magnetic thin film laminate, and more particularly to a method and an apparatus for manufacturing a magnetic thin film laminate having a magnetic film layer and an oxide film layer. [Background technology]

[0002] Conventionally, there is a magnetic thin film laminate in which magnetic film layers are stacked and oxide film layers are formed between the magnetic film layers (see, for example, Patent Document 1). Such magnetic thin film laminates are used, for example, in inductors that require high-frequency characteristics.

[0003] In the magnetic thin film laminate disclosed in Patent Document 1, a multilayer film consisting of a magnetic film layer and an oxide film layer is obtained by repeatedly forming a magnetic film layer by a vacuum deposition technique such as sputtering or an electroplating technique, and then forming an oxide film layer by a vacuum deposition technique such as chemical vapor deposition (CVD) or physical vapor deposition (PVD). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Special Publication No. 2019-527476 Summary of the Invention [Problem to be solved by the invention]

[0005] If the deposition methods for the magnetic film layer and the oxide film layer are different, it is difficult to deposit both the magnetic film layer and the oxide film layer in the same chamber, so the deposition of the magnetic film layer and the deposition of the oxide film layer are carried out in different chambers.

[0006] Furthermore, even when both the magnetic film layer and the oxide film layer are formed by sputtering, the magnetic film, which is a conductive film, is formed by DC sputtering, while the oxide film, which is an insulating film, is formed by RF sputtering. Since it is usually difficult to perform DC sputtering and RF sputtering in the same chamber, each film is formed in a separate chamber. Therefore, in either case, the film-forming target must be moved between the chambers.

[0007] When at least one of the magnetic film layer and the oxide film layer is deposited in a vacuum, each time the object to be deposited is moved between chambers, at least one of the following steps is required: leaking the chamber to return it to atmospheric pressure, or evacuating the chamber. Both of these steps require a certain amount of time, and the required time is multiplied by the number of films to be deposited, so both steps hinder efforts to reduce the deposition time. This is even more true when both the magnetic film layer and the oxide film layer are deposited in a vacuum.

[0008] For example, when forming an oxide film layer by vacuum deposition, the chamber is heated to 10- 4 ~10- 5 It is necessary to reduce the pressure to about 100 Pa and maintain it there, and this reduction in pressure usually takes about 40 to 50 minutes. After film formation, it usually takes about 10 to 20 minutes for the pressure in the chamber to return to atmospheric pressure by leaking the gas into the chamber. On the other hand, a magnetic thin film laminate may have 19 or more layers of magnetic film layers and oxide film layers stacked alternately, in which case this process will be repeated at least nine times.

[0009] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a method and apparatus for manufacturing a magnetic thin film laminate that can shorten the film formation time compared to conventional methods. [Means for solving the problem]

[0010] The present invention is a method for manufacturing a magnetic thin film laminate having a magnetic film layer and an oxide film layer, comprising: a magnetic film formation step of depositing a magnetic film on an object by electrolytic plating or electroless plating to form the magnetic film layer; and an oxide film formation step of forming the oxide film layer on the object, wherein the oxide film formation step comprises a film formation step of depositing an oxidizable film on the magnetic film by electrolytic plating or electroless plating, and an oxidation step of oxidizing the oxidizable film under approximately atmospheric pressure to form an oxide film.

[0011] The present invention also provides a manufacturing apparatus for a magnetic thin film laminate used in the manufacturing method described above, characterized in that it comprises a first plating means for performing the magnetic film formation process, a second plating means for performing the film deposition process, an oxidation treatment means for performing the oxidation process, and a transport means for transporting the film-forming object to each of the means.

[0012] Furthermore, in the present invention, the oxidation step can be a step of anodizing the film to be oxidized. Also, in the present invention, the oxidation step can be a step of oxidizing the film to be oxidized with elemental oxygen and / or oxygen-derived radicals or ions and / or hydrogen peroxide. Also, in the present invention, the oxidation step can be performed under light irradiation.

[0013] The present invention may further include a pretreatment step for ensuring wettability of the film-forming object. The present invention may also include a pretreatment means for performing the pretreatment step, in which the second plating means also serves as the oxidation treatment means.

[0014] In addition, although the expressions "first" and "second" are used in the present invention, these expressions are used merely to distinguish between the respective configurations of the present invention, and the order or number thereof has no particular significance. [Effects of the Invention]

[0015] The present invention provides a method and apparatus for manufacturing a magnetic thin film laminate having an oxide film layer, which includes a magnetic film formation step of forming a magnetic film on an object by electrolytic plating or electroless plating to form a magnetic film layer, and an oxide film formation step of forming the oxide film layer on the object, wherein the oxide film formation step includes a film formation step of forming an oxidizable film on the magnetic film by electrolytic plating or electroless plating, and an oxidation step of oxidizing the oxidizable film under approximately atmospheric pressure to form an oxide film, thereby making it possible to provide a method and apparatus for manufacturing a magnetic thin film laminate that can shorten the film formation time compared to conventional methods. [Brief explanation of the drawings]

[0016] [Figure 1] 1 is a schematic diagram illustrating a magnetic thin film stack according to an embodiment of the present invention. [Figure 2] 1 is a schematic diagram showing a manufacturing apparatus according to an embodiment of the present invention. [Figure 3] 4 is a schematic diagram illustrating an example of an oxide film forming step in an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0017] An embodiment of the present invention will be described with reference to Figures 1 to 3. A magnetic thin film laminate 1 has magnetic film layers 10 and oxide film layers 11. In this embodiment, the magnetic film layers 10 and oxide film layers 11 are alternately stacked, and the oxide film layers 11 are provided as insulating layers or high-resistance layers. The magnetic thin film laminate 1 is used, for example, in inductors and capacitors.

[0018] The method for manufacturing the magnetic thin film laminate 1 mainly includes a magnetic film formation step of forming a magnetic film layer 10 on a film-forming object 12, such as a wafer, by electrolytic plating or electroless plating, and an oxide film formation step of forming an oxide film layer 1 on the film-forming object 12. In this embodiment, the method further includes a pretreatment step.

[0019] The magnetic film forming step can employ any known method as appropriate, and the magnetic film 13 to be formed can be, for example, a NiFe film or a NiFeCr film. The pretreatment step is carried out as a preliminary step to the magnetic film forming step, and is carried out to ensure the wettability of the surface of the film-forming object 12, such as by removing an oxide film on the surface of the film-forming object 12.

[0020] The oxide film forming process includes a film-forming process in which an oxidizable film 14 is formed on the magnetic film 13 by electrolytic plating or electroless plating, and an oxidation process in which the oxidizable film 14 is oxidized under approximately atmospheric pressure to form an oxide film 15. The oxidation process can be, for example, a process of anodizing the oxidizable film 14, or a process of oxidizing the oxidizable film 14 with elemental oxygen, oxygen molecules O2, ozone O3, or oxygen-derived radicals or ions (including plasma), and the latter can be performed under irradiation with light, such as ultraviolet light. The oxidizable film 14, which is the source of the oxide film 15, can be an Al film, a Ti film, a W film, a NiP film, or the like.

[0021] The manufacturing apparatus 2 used in the manufacturing method includes a plating means 20, such as a plating tank, for carrying out the magnetic film formation process, a plating means 21, such as a plating tank, for carrying out the film formation process within the oxide film formation process, an oxidation treatment means 22 for carrying out the oxidation process within the same process, and a transfer means 23, such as a transfer robot, for transferring the film-forming object 12 to each means.

[0022] In this embodiment, the manufacturing apparatus 2 further includes a loading / unloading means 24 for placing the film-forming object 12 in the manufacturing apparatus 2, a pre-treatment means 25 for pre-treating the placed film-forming object 12, for example, a plating pre-treatment tank, and a cleaning means 26 for rinsing away the plating solution.

[0023] A plating tank having the same structure as a known plating tank can be appropriately used for the plating means 20 and the plating means 21. In this embodiment, the plating means 20 and / or the plating means 21 are configured to pass a minimum current (hereinafter referred to as a weak current) that does not cause deposition from the plating solution but still allows current to flow through the plating solution.

[0024] When forming the magnetic film 13 on the oxide film layer 11, the oxide film layer 11 is usually very thin, with a thickness of about 10 to 20 nm. Therefore, there is a possibility that the oxide film layer 11 may be etched simply by immersing it in a plating solution with a relatively low pH (for example, about pH 1.8 to 3.9). However, this etching can be prevented by passing a weak current through the plating solution.

[0025] Furthermore, the plating means 21 can be configured to block moisture and oxygen, particularly when an Al film is used as the oxidizable film 14, so that the water and oxygen in the atmosphere do not affect the plating.

[0026] The pretreatment means 25 is provided to ensure the wettability of the surface of the object to be film-formed before plating, and has the function of supplying a liquid such as an acidic solution and / or pure water and / or degassed water to the surface of the object to be film-formed.

[0027] The cleaning means 26 is, for example, a rinse and dry tank, and has a cleaning section (not shown) for cleaning the film-forming object 12 with pure water, acid, or the like, and a drying section (not shown) for drying the film-forming object 12. The cleaning section may be the same as a known cleaning section for wafers. The drying section may be, for example, one that dries by a spin drying method.

[0028] In this embodiment, the transfer means 23 has the function of supplying liquid such as pure water (including ultrapure water, the same applies below) and / or degassed water (e.g., pure water degassed to a dissolved oxygen content of 2 ppm or less) to the surface of the film-forming object 12 in order to maintain the wettability of the surface of the film-forming object 12 during transfer.

[0029] The oxidation treatment means 22 can be configured, for example, as follows. (A) The oxidation treatment means 22 can be configured as a UV ashing device. In this case, the oxidation treatment means 22 has a light irradiation means 27, for example, an ultraviolet irradiation means, and is configured to be able to generate ozone from oxygen molecules. In some cases, the oxidation treatment means 22 can be connected to an oxygen supply source (not shown) and can receive a supply of oxygen from the oxygen supply source.

[0030] (B) The oxidation treatment means 22 can be configured as an anodizing device. This configuration is particularly applicable when an Al film is used as the film to be oxidized 14. In this case, the oxidation treatment means 22 is configured as an anodizing bath, configured to apply electrolysis reverse to plating in a predetermined electrolytic solution, and the object to be film-formed can be placed thereon as an anode. When the plating means 21 is an electroplating bath, the anodizing bath is similar to the plating bath in that it is a device that applies electrolysis to an electrolytic solution, and therefore the plating means 21 can also serve as the oxidation treatment means 22. [Example]

[0031] Example 1 A first embodiment of the present invention will be described below. In this embodiment, UV ashing is applied to the oxidation step of the oxide film formation process. In this embodiment, a Ni oxide film is used as the oxide film 15, but the present invention can also be applied to cases where a Ti oxide film, a W oxide film, a NiP oxide film, or the like is used.

[0032] (0) If necessary, as a preliminary step, a Cu film or the like is formed in advance as a non-magnetic base film 16 on a wafer, which is the film-forming target 12. A resist film is then coated or laminated on the wafer 12, and patterned using an exposure device. Furthermore, to make the hydrophobic resist hydrophilic, the wafer 12 is subjected to UV ashing or plasma O2 ashing at 250 W for 1 minute or less.

[0033] (1) The film-forming target 12 is placed on the load / unload means 24. Thereafter, the transfer means 23 transfers the placed film-forming target 12 to the pre-processing means 25.

[0034] Pretreatment process (2) In a plating pretreatment tank, which is a pretreatment means 25, sulfuric acid with a concentration of 1 to 5 v% is used to remove the surface oxide film of the film-forming object 12. Thereafter, the film-forming object 12 is transferred to a plating tank, which is a plating means 20 for forming a magnetic film, while degassed water is sprayed on the surface by a transfer means 23 to prevent oxidation of the surface of the film-forming object 12 and maintain wettability. Hereinafter, unless otherwise specified, the film-forming object 12 is transferred to each means by the transfer means 23 while degassed water is sprayed on its surface, from the viewpoint of maintaining wettability.

[0035] Magnetic film formation process (3) A plating solution adjusted to the required Fe / Ni ratio is prepared in the plating means 20, and the film-forming target 12 is immersed in the plating solution. Then, deposition of the magnetic film 13 begins by applying a direct current under current conditions in which the current density is controlled based on the pattern density. Thereafter, plating is terminated when the film thickness of the magnetic film layer 10 reaches a target value (for example, set between 100 nm and 1000 nm). While the magnetic film 13 is being formed, it is preferable to control the current density to increase over time, which allows for more uniform crystal grain size. As a result, a magnetic film layer 10 with a thickness of 100 nm to 1000 nm is formed on the film-forming target 12.

[0036] (4) The film-forming object 12 on which the magnetic film layer 10 has been formed is transferred by the transfer means 23 to a rinsing and drying tank, which is a cleaning means 26. There, the film-forming object 12 is cleaned with pure water and / or acid, etc. In this embodiment, the magnetic film 13 is a NiFe film, the oxidized film 14 is a Ni film, and the adhesion between these films is sufficiently good, so they are cleaned with pure water only. Then, the film-forming object 12 is transferred to a plating tank, which is a plating means 21, for forming the oxide film 15.

[0037] Oxide film formation process 1 (film formation process) (5) The plating means 21 contains, for example, a Ni plating solution, and the film-forming object 12 is immersed in the plating solution. The oxide film layer 11 requires a film thickness of 10 nm to 20 nm, so the current density is smaller, for example, 10 -1 mA / cm 2 The plating is performed slowly at a temperature of about 1000 K. Immediately after the formation of the Ni oxidizable film 14 is completed, preferably within 1 minute, the weak current is controlled to flow through the plating solution and applied to the film-forming object in order to prevent etching of the oxidizable film 14 by the plating solution. Thereafter, the film-forming object 12 is removed from the plating solution and transferred to cleaning means 26 by transfer means 23. Note that when the oxidizable film 14 is a Ti film or a W film, the oxidizable film 14 is formed by electroless plating rather than electrolytic plating as described above.

[0038] Oxide film formation process 2 (cleaning process) (6) After the film-forming target 12 is thoroughly washed with pure water or the like by the washing means 26, the film-forming target 12 is dried. Thereafter, the film-forming target 12 is transferred to the oxidation treatment means 22 by the transfer means 23. At this time, the film-forming target 12 is kept dry, and degassed water or the like is not sprayed on the surface during transfer.

[0039] Oxide film formation process 3 (oxidation process) (7) The object 12 to be film-formed is placed on the oxidation treatment means 22 with the film 14 to be oxidized on its surface. Then, the film 14 to be oxidized is irradiated with ultraviolet light from the ultraviolet light irradiation means, which is the light irradiation means 27. The irradiation of ultraviolet light generates ozone O3 from oxygen molecules O2 in the atmosphere, and the film 14 to be oxidized is oxidized by the ozone O3, forming an oxide film 15. The oxidation of the film 14 to be oxidized increases the thickness of the oxide film 15 in approximately proportion to the irradiation time of ultraviolet light, and is completed when the oxide film 15 reaches the required thickness over the entire surface of the film 14 to be oxidized. The oxidation of the film 14 to be oxidized by this UV ashing is carried out at approximately atmospheric pressure.

[0040] At this time, it is preferable to introduce oxygen into the oxidation treatment means 22. By introducing oxygen, the time required to form the oxide film layer 11 in the atmosphere, which would normally take about 10 minutes, is reduced to about 3 minutes. In this embodiment, a NiO film is formed as the oxide film 15.

[0041] Magnetic film formation process (8) The film-forming object 12 on which the oxide film layer 11 has been formed is transferred again to the plating means 20 by the transfer means 23, and the film-forming object 12 is immersed in the plating solution of the plating means 20. At this time, the weak current is passed through the plating solution, and by applying the weak current the moment the film-forming object 12 comes into contact with the plating solution, etching of the oxide film layer 11 by the plating solution can be prevented.

[0042] After the film-forming object 12 is immersed in the plating solution, the formation of the magnetic film 13 begins on the oxide film layer 11. Because the formation of the oxide film layer 11 increases the surface resistance of the film-forming object 12, plating is initiated at a current density 2 to 5 times higher than in step (3) above. After 1 to 15 seconds have elapsed, the current density is returned to the same level as in step (3) above, and plating continues. Thereafter, when the film thickness of the magnetic film 13 reaches the target value, plating is terminated.

[0043] (9) The above steps (4) to (8) are repeated a predetermined number of times to form the required number of magnetic film layers 10 and oxide film layers 11. Thereafter, if necessary, the resist pattern on the surface of the film-forming target 12 is stripped with a resist stripper and washed with pure water. The pure water used here is preferably degassed water. Stripping the resist pattern exposes the cross section of the laminated film, where the magnetic film layer 10 and the oxide film layer 11 have different ionization tendencies. This can lead to galvanic corrosion due to dissolved oxygen, which can cause crevice corrosion at the interface between the magnetic film layer 10 and the oxide film layer 11. Using degassed water can prevent galvanic corrosion.

[0044] <Example 2> Next, as Example 2, an example in which anodic oxidation is applied in the oxidation step of the oxide film forming step will be described. This example is an example in which an Al oxide film is applied as the oxide film 15, but it can also be applied to cases in which other oxide films such as a Ti oxide film, a W oxide film, and a NiP oxide film are applied. The steps other than the oxide film forming step are the same as in Example 1, so their explanation will be omitted.

[0045] Oxide film formation process 1 (film formation process) (i) The film-forming object 12 on which the magnetic film layer 10 has been formed is immersed in an electrolyte containing AlCl3, and electrolytic plating is performed to form an Al film as an oxidized film 14 on the magnetic film 13. At this time, the presence of oxygen and water in the atmosphere hinders the formation of the Al film, so it is necessary to remove as much oxygen and water as possible from the atmosphere. Therefore, in this embodiment, the manufacturing apparatus 2 is configured so that the plating means 21 can block oxygen and water.

[0046] Oxidation treatment process 2 (oxidation process) (ii) The film-forming target 12 on which the oxidized film 14 has been formed is transferred to the oxidation treatment means 22, and the film-forming target 12 is placed as an anode in the oxidation treatment means 22. The oxidation treatment means 22 contains a predetermined electrolytic solution, for example, an oxalic acid solution or an acetic acid solution, and by applying reverse electrolysis to plating to the film-forming target 12 in the electrolytic solution, the Al in the oxidized film 14 is oxidized to Al2O3, and the oxide film 15 is formed.

[0047] In this embodiment, the film formation process of the magnetic film formation process and the oxide film formation process is performed by electrolytic plating or electroless plating, and the plating can be performed at approximately atmospheric pressure. In addition, the oxidation process of the oxide film formation process can also be performed at approximately atmospheric pressure. Since the series of processes can be performed at approximately atmospheric pressure, there is no need to evacuate and then leak, and it is therefore possible to provide a manufacturing method and manufacturing apparatus for a magnetic thin film laminate that can shorten the film formation time compared to conventional methods.

[0048] The present invention has been described based on the above-mentioned embodiments and examples, but the present invention is not limited to the above-mentioned embodiments and examples and can be modified as appropriate within the scope of the invention.

[0049] (A) When the oxidation step of the oxide film forming process is performed by oxidation with oxygen alone or oxygen-derived radicals or ions, oxygen molecules O2 may be converted into plasma under approximately atmospheric pressure and the oxidized vessel 14 may be oxidized by the O2 plasma, or natural oxidation by oxygen alone in the atmosphere may be performed. Usually, the former method can form a thicker oxide film layer 11 than UV ashing, and the latter method can form a thinner oxide film layer 11 than UV ashing.

[0050] (b) The oxidation step in the oxide film formation process can be performed using hydrogen peroxide (including that dissolved in water or other solvents) instead of oxidation using oxygen alone or oxygen-derived radicals or ions. The oxidation step can also be performed using a combination of oxidation using oxygen alone, oxidation using oxygen-derived radicals or ions, and oxidation using hydrogen peroxide. [Explanation of symbols]

[0051] 1 Magnetic thin film laminate 10 Magnetic film layer 11 Oxide film layer 12 wafer; 13 magnetic film; 14 oxidized film 15 Oxide film 16 Non-magnetic base film 2 Manufacturing equipment 20 plating means 21 plating means 22 oxidation treatment means 23 Transfer means 24 Loading / unloading means 25 Pre-processing means 26 Cleaning means 27 Light irradiation means

Claims

1. 1. A method for manufacturing a magnetic thin film laminate having a magnetic film layer and an oxide film layer, comprising: a magnetic film forming step of forming a magnetic film on a film-forming object by electrolytic plating or electroless plating to form a magnetic film layer; an oxide film forming step of forming the oxide film layer on the film-forming target, The method for manufacturing a magnetic thin film laminate is characterized in that the oxide film formation process includes a film formation process of forming an oxidizable film on the magnetic film by electrolytic plating or electroless plating, and an oxidation process of oxidizing the oxidizable film under approximately atmospheric pressure to form an oxide film.

2. 2. The method for manufacturing a magnetic thin film laminate according to claim 1, wherein the oxidation step is a step of anodizing the film to be oxidized.

3. 2. The method for producing a magnetic thin film laminate according to claim 1, wherein the oxidation step is a step of oxidizing the film to be oxidized with elemental oxygen and / or radicals or ions derived from oxygen and / or hydrogen peroxide.

4. 4. The method for producing a magnetic thin film laminate according to claim 3, wherein the oxidation step is carried out under light irradiation.

5. 2. The method for manufacturing a magnetic thin film laminate according to claim 1, further comprising a pretreatment step for ensuring wettability of the object to be film-formed.

6. 6. An apparatus for manufacturing a magnetic thin film laminate for use in the manufacturing method according to any one of claims 1 to 5, comprising: a first plating means for performing the magnetic film forming step; a second plating means for performing the film forming step; an oxidation treatment means for performing the oxidation step; a transport means for transporting the object to be film-formed to each of the means;

7. 7. The apparatus for manufacturing a magnetic thin film laminate according to claim 6, wherein said second plating means also serves as said oxidation treatment means.

8. 7. The apparatus for manufacturing a magnetic thin film laminate according to claim 6, further comprising a pre-treatment means for carrying out said pre-treatment step.

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