JP4576765B2 - Protective film forming method, protective film forming apparatus and protective film - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a protective film forming method, a protective film forming apparatus, and a protective film for forming a protective film having excellent corrosion resistance and peeling resistance formed on a magnetic head or the like.
[0002]
[Prior art]
In a magnetic head (GMR head) used in a hard disk device, a protective film is formed to protect the head surface from abrasion and corrosion. In general, an Si film intermediate layer is formed on an Al ₂ O ₃ TiC base material of a magnetic head, and a carbon film (DLC thin film or ta-C thin film) is formed thereon. The protective film made of the Si film and the carbon film is very thin, about several nanometers, and the intermediate layer (Si film) is formed to improve the peel resistance of the carbon film and increase the adhesion.
[0003]
However, it is difficult to completely prevent the carbon film from being peeled off, and there is a problem in that pinholes are generated along with the peeling of the carbon film, and the Si film in that portion is easily corroded. For example, if there is a steep step on the base material, the carbon film is relatively easily peeled off at that portion, which is likely to cause corrosion. In addition, corrosion may occur due to insufficient density of the carbon film itself.
[0004]
For this reason, the intermediate layer is required to have the property of being chemically stable and resistant to corrosion in addition to improving the adhesion. For example, it is attempted to use a SiO ₂ film instead of the Si film because it is chemically stable.
[0005]
[Problems to be solved by the invention]
However, since the SiO ₂ film is chemically stable, conversely, the adhesion between the carbon film and the carbon film is easily peeled off. Therefore, the method of forming a SiO ₂ film by sputtering using a SiO ₂ target and forming a carbon film thereon has a problem that the formed carbon film is easily peeled off.
[0006]
The objective of this invention is providing the film-forming method and film-forming apparatus which can form the protective film excellent in corrosion resistance and peeling resistance.
[0007]
[Means for Solving the Problems]
A description will be given in association with FIGS.
(1) Referring to FIGS. 1 and 2, the invention of claim 1 forms a Si adhesion layer 2 on the film formation target 1 by a sputtering method using a Si target 13, and This is applied to a protective film forming method for forming the carbon film 3 on the surface, and after the oxygen gas is introduced into the sputter process chamber 10 for a predetermined time, the Si adhesion layer 2 is formed. Achieve.
(2) Referring to FIGS. 1 and 3, the invention of claim 2 supplies oxygen gas into the sputter process chamber 10 for a predetermined time before starting the film formation, and then sputters using the Si target 13. A sputtering apparatus 22 for depositing the Si adhesion layer 2 on the deposition target S, 1 by a method and a carbon film deposition apparatus 24 for depositing the carbon film 3 on the Si adhesion layer 2 are provided for the above purpose. Achieve.
(3) Describing in association with FIG. 1, the invention of claim 3 is a protective film comprising an adhesion layer 2 formed on the film formation target 1 and a carbon film 3 formed on the adhesion layer 2. The adhesion layer 2 achieves the above-mentioned object by being composed of a Si adhesion layer having a high concentration of the SiO _X component on the film formation target side and a high concentration of the Si component on the carbon film side.
[0008]
In the section of means for solving the above problems, the drawings of the embodiments of the invention are used for easy understanding of the present invention. However, the present invention is not limited to the embodiments of the invention. Absent.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a view showing a protective film formed by the protective film forming method according to the present invention. 1A is a cross-sectional view showing the intermediate layer 2 and the carbon film 3 formed on the base material 1 of the magnetic head element, and FIG. 1B is a cross-sectional view of Si component distribution and SiO _{X in} the intermediate layer 2. The distribution is shown. An intermediate layer 2, which is a mixed layer of Si and SiO 2 _X , is formed on the base material 1. A carbon film 3 having excellent corrosion resistance and wear resistance is formed on the intermediate layer 2. As the carbon film 3, a DLC (Diamondlike Carbon) film, a ta-C (tetrahedral amorphous carbon) film, or the like is used.
[0010]
<< About the film-forming method of the intermediate | middle layer 2 >>
FIG. 2 is a diagram for explaining a method of forming the intermediate layer 2 shown in FIG. 1A, and is a schematic configuration diagram of a DC magnetron sputtering apparatus. 2A shows an oxygen gas introduction process, and FIG. 2B shows a sputtering process. When the intermediate layer 2 is formed, the processes are performed in the order of (a) and (b). In the DC magnetron sputtering apparatus, the Si target 13 is provided on the target holder 14 on the cathode side, and the substrate S on which the intermediate layer 2 is formed is provided on the anode side (ground). A magnetic head element is formed on the substrate S. A bias power supply 11 is connected to the target holder 14, and a DC voltage of several kV is applied to the target holder 14 by the bias power supply 11. The target holder 14 is provided with a magnet 15. The magnet 15 generates a parallel magnetic field near the surface of the target 13. Reference numeral 18 denotes magnetic lines of force due to the magnet 15. Argon gas and oxygen gas can be introduced into the chamber 10 of the sputtering apparatus through open / close valves 16 and 17.
[0011]
When the intermediate layer 2 is formed on the substrate S, the chamber 10 is evacuated by an unillustrated evacuation device, and then the on-off valve 17 is opened and closed as shown in FIG. It is introduced into the chamber 10. When oxygen gas is introduced, oxygen molecules 19 are adsorbed on the inner wall surface of the chamber 10, the surface of the target 13, and the like. When the opening / closing valve 17 is closed after the oxygen gas is introduced, the chamber 10 is evacuated, so that the oxygen gas in the chamber space is easily evacuated, but the oxygen molecules 19 adsorbed on the inner wall surface of the chamber are easily evacuated. Not.
[0012]
Next, the open / close valve 16 is opened to introduce argon gas into the chamber 10 to set the pressure in the chamber to a sputtering process pressure (several Pa), and a bias voltage is applied to the target holder 14 to start magnetron sputtering. When a bias voltage is applied to the target holder 14, glow discharge is generated, and argon gas is turned into plasma by the glow discharge. Reference numeral 20 in FIG. 2B denotes a plasma region. Argon ions in the plasma region 20 are attracted to the Si target 13 on the cathode side, and the Si target 13 is sputtered. Sputtered particles sputtered in the direction of the substrate S are deposited on the substrate S, and a Si film is formed on the surface of the substrate S.
[0013]
Since a parallel magnetic field is formed near the target surface in the magnetron sputtering apparatus, secondary electrons knocked out of the target surface during sputtering are captured by the magnetic field by Lorentz force and perform a cyclotron motion. As a result, ionization of argon gas is promoted by secondary electrons that perform cyclotron motion.
[0014]
When magnetron sputtering is started, oxygen molecules adsorbed on the inner wall of the chamber and the target surface are radicalized by glow discharge or ion bombardment. The radicalized oxygen molecules and oxygen ions are taken into the Si film being formed on the substrate S. Although the radicalization of the oxygen adsorbed at the beginning of sputtering is actively performed, the radicalized oxygen molecules and oxygen ions decrease with time.
Therefore, as shown in FIG. 1B, the oxygen concentration in the Si film gradually decreases, and finally a substantially pure Si film is formed. The introduction of oxygen gas into the chamber 10 is performed every time a sputtering process is performed.
[0015]
FIG. 1B qualitatively shows the concentration change in the film thickness direction of the Si component and the SiO _X component of the intermediate layer 2, the horizontal axis indicates the concentration (%), and the vertical axis indicates the film of the intermediate layer 2. Each thickness is shown. As described above, since radicalization of oxygen is active at the beginning of sputtering, the SiO _X concentration in the portion near the base material 1 of the intermediate layer 2 is considerably higher than the Si concentration. However, as the sputter deposition proceeds, that is, as the thickness of the intermediate layer 2 increases, the SiO _x concentration decreases, and conversely, the Si concentration increases. In the vicinity of the surface of the intermediate layer 2 on the carbon film side, the SiO _X concentration is very small and can be regarded as a substantially pure Si film, so that the adhesion with the carbon film 3 is kept good.
[0016]
FIG. 1B shows an example of the distribution of the SiO _X concentration. Not only this, but the same effect can be obtained if the Si concentration is large on the base material side and the SiO _X concentration is large on the carbon film side. Can do.
[0017]
<Description of protective film deposition system>
FIG. 3 schematically shows a schematic configuration of the protective film forming apparatus. In addition to the DC magnetron sputtering apparatus 22 described above, the protective film forming apparatus includes a cleaning device 23, a carbon film forming device 24, and a transfer chamber 25. The DC magnetron sputtering device 22, the cleaning device 23, and the carbon film forming device 24 are connected to the transfer chamber 25 through gate valves 26A, 26B, and 26C, respectively. A transfer robot 21 is provided in the transfer chamber 25, and the substrate S is taken into and out of each apparatus by the transfer robot 21. The inside of the transfer chamber 25 is evacuated by a rotary vacuum pump 32 connected via an opening / closing valve 31.
[0018]
The DC magnetron sputtering apparatus 22 has the same configuration as that shown in FIG. 2 and includes an oxygen gas supply unit 27 and an argon gas supply unit 28. The oxygen gas supply unit 27 is provided with a gas supply source 27a, and the oxygen gas is supplied into the chamber 10 through the needle 27b and the opening / closing valve 27c. The oxygen gas flow rate is set to a constant amount by the needle 27b. On the other hand, in the case of the argon gas supply unit 28, the argon gas from the gas supply source 28a is supplied to the chamber 10 via the mass flow controller 28b and the open / close valve 28c. The argon gas flow rate is controlled by the mass flow controller 28b so that the pressure in the chamber during sputtering becomes the predetermined process pressure. Reference numeral 29 denotes an evacuation apparatus for evacuating the chamber 10.
[0019]
The cleaning device 23 is a device that removes foreign matter (oxide film or the like) on the surface of the substrate S by etching or the like. For example, the substrate surface is sputter etched using magnetron sputtering. In the sputter etching, the substrate surface is sputtered by the generated argon ions obtained by converting the argon gas into plasma. Reference numeral 30 denotes an evacuation apparatus including a turbo molecular pump 30a. A rotary vacuum pump 30b is used as an auxiliary pump of the turbo molecular pump 30a. The turbo molecular pump 30a is connected to the process chamber of the cleaning device 23 through a mechanical opening / closing valve 30c and an electromagnetic control valve 30d. The vacuum evacuation device 29 of the DC magnetron sputtering device 22 and the vacuum evacuation device 33 of the carbon film deposition device 24 described later have the same configuration as the vacuum evacuation device 30. The carbon film forming apparatus 24 is an apparatus for forming the carbon film 3 of FIG. 1A, and an ECR-CVD apparatus or an FCVA apparatus using an FCVA (Filtered Cathodic Vacuum Arc) method is used.
[0020]
《Explanation of protective film formation procedure》
Next, a film forming procedure for forming the intermediate layer 2 and the carbon film 3 in FIG. 1A using the protective film forming apparatus in FIG. 3 will be described with reference to FIG. In step 1, the substrate S is carried into the transfer chamber 25. The substrate S carried into the transfer chamber 25 is transferred to the cleaning device 23 by the transfer robot 21. In step 2, the surface of the substrate S is cleaned by sputter etching in the cleaning device 23. When the substrate cleaning is completed, the substrate S is transferred from the cleaning device 23 to the DC magnetron sputtering device 22 by the transfer robot 21.
[0021]
In step 3, the intermediate layer 2 is formed on the substrate S using the DC magnetron sputtering apparatus 22. First, when the substrate S is transferred into the DC magnetron sputtering apparatus 22, the gate valve 26A is closed, and oxygen gas is introduced into the chamber 10 by the oxygen gas supply apparatus 27 for a predetermined time. By introducing this oxygen gas, oxygen molecules 19 are adsorbed on the inner wall of the chamber and the target surface as shown in FIG. When the supply of oxygen gas is stopped, argon gas is introduced by the argon gas supply device 28 and a bias voltage is applied to the target holder 14 to perform the sputtering operation. As a result, the intermediate layer 2 having a concentration distribution as shown in FIG. 1B is formed on the substrate S.
[0022]
When the intermediate layer 2 is formed on the substrate S, the substrate S is transferred from the DC magnetron sputtering apparatus 22 to the carbon film forming apparatus 24 by the transfer robot 21. Next, in step 4, the carbon film 3 is formed on the intermediate layer 2 using the carbon film forming apparatus 24. If the carbon film 3 having a predetermined thickness is formed, the substrate S is transferred from the carbon film forming apparatus 24 to the transfer chamber 25 and then unloaded from the transfer chamber 25 to the outside of the apparatus.
[0023]
As described above, the medium layer 2 formed by the film forming method of the present embodiment has a high SiO _X component concentration on the base material 1 side as shown in FIG. In the vicinity of the interface with 3, the concentration of the Si component increases. As a result, the corrosion resistance of the intermediate layer 2 can be improved without reducing the adhesion between the carbon film 3 and a protective film having excellent peeling resistance and corrosion resistance can be formed.
[0024]
In the embodiment described above, the intermediate layer 2 is formed by the DC magnetron sputtering apparatus. However, it may be formed by using an RF magnetron sputtering apparatus or an ion beam sputtering apparatus. In the case of forming a film using any apparatus, oxygen gas is introduced into the process chamber for a predetermined time before the film formation is started, and oxygen molecules are adsorbed on the inner wall of the chamber, the target surface, or the like. Then, when the Si film (intermediate layer 2) is formed after adsorbing oxygen molecules, the intermediate layer 2 in which the SiO _x component is mixed is formed on the same principle as the DC magnetron sputtering described above.
[0025]
In the correspondence between the embodiment described above and the elements of the claims, the base material 1 and the substrate S constitute a film formation target, and the intermediate layer 2 constitutes a Si adhesion layer.
[0026]
【The invention's effect】
As described above, according to the first and second aspects of the invention, oxygen remaining in the process chamber at the time of sputtering is radicalized and mixed into the Si adhesion layer being formed. As a result, large concentrations of SiO _X component in Si adhesion layer deposition target side which is formed in a sputter initial, SiO _X component as compared to the concentration of the Si component in the Si adhesion layer of the carbon film side, which is formed in a sputter end The concentration of becomes smaller. Therefore, the corrosion resistance of the Si adhesion layer can be improved without lowering the peel resistance of the carbon film, and a protective film having excellent corrosion resistance and peel resistance can be formed.
According to the invention of claim 3, since the adhesion layer is a Si adhesion layer in which the concentration of the SiO _X component is large on the film formation target side and the concentration of the Si component is large on the carbon film side, the peeling resistance of the carbon film is reduced. Therefore, the corrosion resistance of the adhesion layer can be improved, and a protective film having excellent corrosion resistance and peeling resistance can be formed.
[Brief description of the drawings]
FIG. 1 is a diagram showing an embodiment of a film forming apparatus according to the present invention.
FIGS. 2A and 2B are diagrams illustrating a method of forming an intermediate layer 2, in which FIG. 2A is an oxygen gas introduction step and FIG. 2B is a sputtering step.
FIG. 3 is a schematic diagram showing a schematic configuration of a protective film forming apparatus.
FIG. 4 is a diagram showing a procedure for forming a protective film.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Base material 2 Intermediate | middle layer 3 Carbon film 11 Bias power supply 13 Si target 14 Target holder 22 DC magnetron sputtering apparatus 23 Cleaning apparatus 24 Carbon film formation apparatus 25 Transfer chamber 27 Oxygen gas supply part 28 Argon gas supply part

Claims (3)

In a protective film forming method of forming a Si adhesion layer on a film formation target by a sputtering method using a Si target, and forming a carbon film on the Si adhesion layer,
A method of forming a protective film, wherein the Si adhesion layer is formed after oxygen gas is introduced into the sputtering process chamber for a predetermined time. A sputtering apparatus that supplies oxygen gas into the sputtering process chamber for a predetermined time before the start of film formation, and then forms a Si adhesion layer on the film formation target by a sputtering method using an Si target;
A protective film forming apparatus comprising a carbon film forming apparatus for forming a carbon film on the Si adhesion layer. In a protective film composed of an adhesion layer formed on a film formation target and a carbon film formed on the adhesion layer,
2. The protective film according to claim 1, wherein the adhesion layer comprises a Si adhesion layer having a high concentration of SiO _X component on the film formation target side and a high concentration of Si component on the carbon film side.

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