JP2011068927A - Method for depositing silicon carbide film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for depositing a SiC film which is very thin and excellent in wear resistance and corrosion resistance. <P>SOLUTION: The method for depositing the SiC film includes: a step (S10) of depositing Si film on the surface to be deposited by a sputter deposition process applying no heating; a first step (S20) of etching the Si film on the surface to be deposited to the extent that an initial defect layer is exposed; a second step (S40) of depositing a Si particle on the Si film etched at the first step by the sputter deposition process applying no heating to obtain the Si film having the predetermined thickness; and a third step (S50) of irradiating the Si film having the predetermined thickness with a carbon ion to transform the Si film into the SiC film. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a method for forming an extremely thin SiC film.

  Silicon carbide (SiC) is a material having excellent mechanical strength, heat resistance, and corrosion resistance, and is effective as a high-temperature material such as a high-temperature semiconductor. Further, due to its corrosion resistance, it is also effective as a corrosion-resistant protective film that prevents corrosion from water, acid, etc. in an extremely thin region of about several nm. For example, it is used as a protective film for a magnetic head. The protective film of the magnetic head is required to be thin and have wear resistance and corrosion resistance.

  A CVD method or a sputtering method is used to form the silicon carbide film. When the CVD method is used, film formation is usually performed by heating the substrate to a high temperature of 1000 ° C. or higher (see Patent Document 1). Also in a sputtering method in which a silicon carbide (SiC) target is directly sputtered to form a film, it is necessary to heat the substrate to 400 to 600 ° C.

JP-A-9-221395

  However, it is difficult to apply the high-temperature SiC film forming method as described above to materials whose characteristics deteriorate at high temperatures, for example, magnetic materials. In addition, it is possible to perform sputter deposition without heating, but the formed film becomes an amorphous SiC film, and there is a problem that sufficient performance cannot be obtained in terms of corrosion resistance and wear resistance. .

In the SiC film forming method according to the first aspect of the present invention, after the silicon film is formed on the film formation surface by the sputtering film formation method without heating, the initial defect layer is exposed on the Si film on the film formation surface. A first step of etching until deposition, and Si particles are deposited on the Si film etched in the first step by a sputtering deposition method without heating, and the Si film is formed into a Si film having a predetermined thickness. And a third step of irradiating the Si film having a predetermined thickness with carbon ions to turn the Si film into SiC.
The invention of claim 2 is the SiC film forming method according to claim 1, wherein the step of irradiating at least one of nitrogen ions and oxygen ions is performed between the second step and the third step, or the third step. Provided after the step, any one of a layer in which SiC is nitrided, a layer in which SiC is oxidized, and a layer in which SiC is oxynitrided is formed in the SiC film.
According to a third aspect of the present invention, in the SiC film forming method according to the first or second aspect, the second step is performed after the first step is repeated a plurality of times.
According to the SiC film forming method of the invention of claim 4, after the SiC film is formed on the film formation surface by the sputtering film formation method without heating, the initial defect layer is exposed on the SiC film on the film formation surface. A first step of etching until SiC is deposited, and SiC particles are deposited on the SiC film etched in the first step by a sputtering film forming method without heating, and the SiC film is formed into a SiC film having a predetermined thickness. And a second step.
According to a fifth aspect of the present invention, in the SiC film forming method according to the fourth aspect, the step of irradiating at least one of nitrogen ions and oxygen ions is provided after the second step. One of the oxidized layer and the layer obtained by oxynitriding SiC is formed on the SiC film.
The invention according to claim 6 is the SiC film forming method according to claim 4 or 5, wherein the second step is performed after the first step is repeated a plurality of times.
The SiC film forming method according to the invention of claim 7 includes a step of forming a Si film on a film formation surface by a sputtering film forming method without heating, and a step of etching the Si film until an initial defect layer is exposed. And the step of forming an SiC layer by irradiating the etched Si film with carbon ions to form SiC, thereby forming a SiC film having a predetermined thickness in which a plurality of SiC layers are stacked. .
The invention of claim 8 is the SiC film forming method according to claim 7, wherein at least one of nitrogen ions and oxygen ions is irradiated before or after the last SiC layer forming step among the repeated SiC layer forming steps. The SiC film is characterized in that any one of a layer in which SiC is nitrided, a layer in which SiC is oxidized, and a layer in which SiC is oxynitrided is formed on the SiC film.

  According to the present invention, it is possible to form a SiC film that is extremely thin and excellent in wear resistance and corrosion resistance.

1 is a diagram showing a schematic configuration of a magnetic head slider 1. FIG. It is a flowchart which shows the procedure of SiC film formation. It is sectional drawing explaining the film | membrane structure in the formation process of a SiC film. It is sectional drawing explaining the film | membrane structure in the formation process of a SiC film. It is a flowchart which shows the procedure of SiC film formation in the 2nd formation method. It is sectional drawing explaining the film | membrane structure in the SiC film formation process of the 2nd formation method. It is sectional drawing explaining the film | membrane structure in the SiC film formation process of the 2nd formation method. It is a flowchart which shows the procedure of SiC film formation in the 3rd formation method. It is a figure explaining a film quality adjustment process.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing a schematic configuration of a magnetic head slider 1 to which an SiC film formed by the SiC film forming method according to the present embodiment is applied as a protective film. The magnetic head slider 1 is obtained by forming a laminated body of thin film magnetic heads on a slider substrate 11 of AlTiC (Al2O3TiC).

  The multilayer body includes a lower magnetic layer 12 and an upper magnetic layer 15, a coil conductor 14 formed therebetween, and an insulating layer 13, and is covered with an insulating protective film 16 that protects the multilayer body. The magnetic recording medium is disposed on the lower side of the magnetic head slider 1 in the figure, and a wear-resistant protective film 20 is formed on the surface of the magnetic head slider 1 facing the magnetic recording medium. The SiC film formed by the SiC film forming method of the present embodiment is used as this protective film 20.

(First forming method)
Next, a method for forming the SiC film will be described. FIG. 2 is a diagram for explaining an embodiment of the SiC film forming method, and is a flowchart showing a procedure for forming the SiC film. 3 and 4 are views for explaining the film structure in the process of forming the SiC film, and schematically show the cross section of the film.

  In step S10 of FIG. 2, the Si layer 200 is formed on the recording medium facing surface of the magnetic head slider 1 to be formed by sputtering such as ion beam sputtering or magnetron sputtering. Hereinafter, this recording medium facing surface is referred to as a substrate surface 1a. Not only the Si film formation in step S10, but also in the film formation of the present embodiment, in order to avoid the thermal influence on the magnetic material of the magnetic head, the film is formed without performing substrate heating (heating of the film formation target). Form.

  Here, the thickness t1 from the substrate surface 1a of the Si layer 200 is set to be approximately the same as the final thickness t3 (1 nm or less) of the SiC film, but is not limited thereto. In the magnetic head, it is preferable that the gap between the magnetic head and the recording medium is small in order to improve detection performance. Therefore, it is preferable that the SiC film formed as a protective film of the magnetic head is as thin as possible within a range in which functions such as corrosion resistance can be exhibited. The SiC film forming method of the present embodiment is proposed for forming an ultrathin film having a thickness of 1 nm or less. Since the diameter of Si atoms is about 2.4 angstroms, the number of atomic layers of a Si layer having a thickness of 1 nm corresponds to approximately five layers. In the following description, it is assumed that the number of atomic layers of the Si layer 200 to be formed is approximately five.

  Conventionally, substrate heating during SiC film formation has the effect of promoting not only SiC crystallization but also migration immediately after SiC deposition on the substrate. In the case where migration immediately after SiC is not sufficiently performed, the film thickness that changes from an island shape to a continuous shape tends to increase in the initial growth process of the film. In addition, the lack of migration contributes to the generation of defects in the film as well as the initial layer. That is, in the initial layer of atoms forming the film, the number of atomic layers in a non-reachable state in which the film is not completely continuous depends on the migration immediately after deposition.

  On the other hand, since the substrate is not heated in the formation of the Si layer 200 in step S10, the migration of Si atoms attached by sputtering is not sufficiently performed, and the atomic layer in the non-reachable state is not formed in the initial layer of the Si layer 200. Arise. FIG. 3A schematically shows a cross section of the Si layer 200. The atomic layer close to the substrate surface 1a has a large number of gaps 200a and is a discontinuous atomic layer. . Here, such an atomic layer is referred to as an initial defect layer.

  In step S20, the Si layer 200 formed on the substrate surface 1a is subjected to an etching process using a sputter etching method, an ECR etching method, an ion beam etching method, or the like, and the Si layer 200 is formed to a thickness t2 at which the initial defect layer is exposed. Etch layer 200. FIG. 3B shows the Si layer 200 after the etching process, and etching is performed up to 1 to 2 atomic layers so that the gap 200a of the initial defect layer is exposed. That is, the thickness t2 is a thickness corresponding to 1 to 2 atomic layers. By performing such etching, the migration of Si atoms is promoted by the energy when etching ions enter the Si layer 200, and defects in the 1-2 atomic layer are improved. Therefore, the gap 200a after etching is smaller than that in the case of FIG.

  In step S30, it is determined whether or not the Si film forming process in step S10 and the etching process in step S20 have been performed a predetermined number of times. Until the number of etching and film formation processes reaches a predetermined number, NO is determined in step S30, the process returns to step S10, and the processes in steps S10 and S20 are repeated a predetermined number of times.

  As described above, the initial defect layer of the Si layer is improved by performing the etching in step S20, and when the Si sputter film formation is further performed after the initial defect layer is exposed, Si atoms enter the gap 200a, A denser Si film can be formed. Such an improvement effect on the initial defect layer is further enhanced by repeatedly performing film formation and etching. How many times the predetermined number is set depends on the film forming conditions, etching conditions, and the like, and is set by actually performing film forming experiments.

  If NO is determined in step S30, the process returns to step S10, and Si particles (Si atoms or Si atoms are formed by sputtering on the substrate surface 1a that is etched as shown in FIG. A particle composed of a plurality of Si atoms) is deposited, and a Si layer 200 having a thickness t1 is formed again. FIG. 3C shows the Si layer 200 after returning to step S10 and performing the second sputtering film formation. By this Si film formation, Si atoms enter the exposed gap 200a. As a result, defects in the 1-2 layers are further improved. In addition, since the defects of the first and second layers are improved, the layered structure of the third and higher layers is also better in the laminated state than the first Si layer 200.

  Then, it progresses to step S20 and the 2nd etching is performed. FIG. 4A shows the result of the second etching process. In the example shown in FIG. 3C, the gap 200a remains in the 1-2 layer region, and by performing etching up to 1-2 layers as shown in FIG. 4A, Si migration is promoted. The gap 200a is reduced.

  On the other hand, if “YES” is determined in the step S30, the process proceeds to a step S40, and the third Si sputter film formation as shown in FIG. 4B is performed. Also during this film formation, Si deposition proceeds while Si atoms enter the gap 200a exposed by etching. As a result, the ratio of the gap 200a in the first and second layers is further reduced, and the Si layer 200 is formed in a dense state from the first and second layers close to the substrate surface 1a. In the sputtering in step S40, the final thickness adjustment of the Si layer 200 is performed. That is, assuming that the finally required thickness of the SiC film is t3, the sputtering film formation is controlled in step S40 so that the thickness of the Si layer 200 becomes t3. Note that the thickness of the Si layer in step S40 may be set to be larger than t3, and then the thickness may be adjusted to t3 by etching. Etching for thickness adjustment may be performed immediately after step S40 or after step S50.

  In step S50, as shown in FIG. 4C, the formed dense Si film 200 having a thickness of 1 nm or less is irradiated with carbon ions. For irradiation of carbon ions, carbon ions may be irradiated by an ion beam method, or a cathodic arc ion plasma source represented by an FCVA (Filtered Cathodic Vacuum Arc) method may be used. About FCVA method, it describes in Unexamined-Japanese-Patent No. 2005-264255, for example. Moreover, you may utilize the ECR plasma source which ionizes source gas by ECR (Electron Cyclotron Resonance) method.

  When the Si layer 200 is irradiated with carbon ions in this way, the SiC layer is made SiC by the energy at the time of ion irradiation, and a SiC single layer film is formed without heating the substrate. That is, the irradiation of carbon ions in this embodiment is not for laminating a carbon film but for implanting carbon ions into the Si layer to promote SiC formation. As a result, the Si layer is converted to SiC, and a SiC single layer film can be formed. Although depending on the energy of ion irradiation, the irradiated carbon ions can enter the third to fifth layers from the surface of the Si layer 200. At the time of irradiation, if the incident speed of carbon ions is large, the carbon film is formed on the Si layer rather than making the Si layer SiC. Therefore, it is necessary to control the incident speed of the carbon ions. The incident speed of carbon ions is desirably about 1 nm in terms of the film forming speed.

(Second forming method)
5 to 7 are diagrams for explaining a second method of forming the SiC film. FIG. 5 is a flowchart showing a procedure for forming the SiC film. 6 and 7 show cross sections at each stage of the film formation procedure, as in FIGS. 6 and 7, illustration of Si atoms is omitted. Also in the second forming method, sputtering methods such as ion beam sputtering and magnetron sputtering are used for Si film formation, and ion beam method, cathodic arc ion plasma source and ECR plasma source are used for carbon ion irradiation. Is used. For etching the Si layer, sputter etching, ECR etching, ion beam etching, or the like is used.

  In step S110, the Si layer 200 is formed on the substrate surface 1a as in step S10 of FIG. 2 (see FIG. 6A). The film thickness is also t1 as described above. Although not shown in FIG. 6, similar to FIGS. 3A and 3B, gaps 200a are formed from the substrate surface 1a to several initial defect layers.

  In step S120, the Si layer 200 is etched by ion beam etching or the like to the extent that one or two layers remain from the substrate surface 1a (film thickness t2). As a result, the migration of Si atoms is promoted by the energy of etching ions, the initial defects are improved, and the ratio of the gap 200a is reduced.

  In step S130, the Si layer 200 etched to the thickness t2 is irradiated with carbon ions in the same manner as in step S50 described above. The formation of SiC is promoted by the energy at the time of carbon ion irradiation, and the SiC layer 201 is formed. In addition, the irradiated C enters the exposed gap 200a, and the initial defects generated when the Si layer is formed are improved.

  In step S140, it is determined whether the etching in step S120 and the Si film formation in step S130 have been performed a predetermined number of times set in advance. The predetermined number of times is set such that “predetermined number of times = t3 / t2” when the finally required SiC film thickness is t3. If NO is determined in step S140, the process returns to step S110 to perform the second Si film formation as shown in FIG. 7A, and the Si layer having the thickness t1 is formed on the SiC layer 201 having the thickness t2. 200 is newly formed.

  During the formation of this Si layer, Si atoms enter the defective portion (gap) of the SiC layer 201 and the density of the SiC layer 201 is improved.

  Furthermore, it progresses to step S120 and the etching process by ion beam etching etc. is performed with respect to the newly formed Si layer 200 (refer FIG.6 (b)). That is, the Si layer 200 is etched to the extent that a 1-2 atomic layer remains from the boundary with the SiC layer 201 (film thickness t2), migration of Si atoms is promoted by etching energy, and an initial defect layer of the Si layer 200 is formed. Expose.

  In step S130, the etched Si layer 200 is irradiated with carbon ions. As a result, the same process (SiC formation, initial defect improvement) as the first carbon ion irradiation described above is performed on the second Si layer 200. In this way, two SiC layers 201 are formed, and the thickness of the SiC film is twice t2. As described above, when the processes from step S110 to step S130 are performed a predetermined number of times and the thickness of the SiC film reaches t3, YES is determined in step S140, and the series of SiC film forming processes is completed.

  In the above-described second SiC film forming method, the Si layer 200 is etched to a thickness t2 (1-2 atomic layers), and the process of forming the SiC layer 201 by irradiating it with carbon ions is repeated. A SiC film having a desired thickness t1 was formed. The first forming method is a method of forming a SiC film by irradiating carbon ions after forming a Si layer having a film thickness t1, so that the concentration of carbon tends to vary in the thickness direction. That is, the carbon concentration increases toward the surface side of the SiC film. On the other hand, in the second forming method, an SiC film is formed for each thickness t2, and the SiC film having a predetermined thickness t1 is formed by performing it multiple times, so that the film quality can be made more uniform. As described above, the film quality is slightly different depending on the forming method, and they can be used properly according to the application. For example, when used as a protective film for a magnetic head, moisture resistance and lubricity are required, and therefore, a SiC film formed by the first forming method having a higher carbon concentration and excellent lubricity is suitable for the surface.

(Third forming method)
FIG. 8 is a diagram for explaining a third method of forming the SiC film. In the first and second forming methods described above, the SiC film is formed by irradiating the Si film formed on the substrate with carbon ions, but the SiC film is directly formed by sputtering using the SiC target. Also good. However, in the conventional sputter film formation, it is common to form a SiC film having a predetermined thickness t3 by heating the substrate, and it has been difficult to apply to film formation on a magnetic material.

  On the other hand, in the present embodiment, as described later, since sputtering film formation is performed without heating the substrate, it can be applied to film formation on a magnetic material that does not like heating. However, if heating is not performed, the initial defect layer is formed in the SiC layer as in the case of the Si layer formation described above. Therefore, in order to improve the initial defect layer, the SiC film is formed by the procedure shown in FIG. Form.

  In the third forming method as well, sputtering methods such as ion beam sputtering and magnetron sputtering are used for SiC film formation. Sputter etching, ECR etching, and ion beam etching are used for etching the SiC layer. Used.

  The SiC film formation is performed in the same procedure as the Si layer formation method shown in steps S10 to S40 in FIG. 2 except that the target material is SiC instead of Si. That is, in step S210 of FIG. 8, a SiC layer having a thickness t1 is formed by sputtering. Even in the case of this sputter deposition, since the substrate is not heated, an initial defect layer is formed in the boundary region with the substrate surface. Here, although a cross-sectional view of the SiC film is not shown, it can be considered that the Si atoms in FIG. 3 are replaced with SiC.

  In step S220, the SiC layer is etched by ion beam etching or the like to the extent that one or two layers of SiC remain (film thickness t2) from the substrate surface 1a, and the SiC energy is promoted by the etching energy and the SiC layer. The initial defect layer is exposed. In step S230, SiC is deposited by sputtering, and a SiC layer having a thickness t1 is formed again. By this SiC film formation, SiC is deposited while SiC enters the gaps between the initial defect layers.

  In step S240, it is determined whether or not the etching process in step S220 and the SiC film forming process in step S230 have been performed a predetermined number of times. The predetermined number of times is set similarly to the case of step S30 in FIG. Until the number of etching and film forming processes reaches a predetermined number, NO is determined in step S240, the process returns to step S210, and the processes in steps S220 and S230 are repeated a predetermined number of times. On the other hand, if it is determined as YES in step S240, the process proceeds to step S250. In step S250, a SiC film is formed by sputtering so that the final SiC film has a required thickness t3.

  As described above, the SiC film forming method of the present embodiment forms an extremely thin (for example, 1 nm or less) SiC film on a film formation object that is not subject to heating, such as a magnetic material, and includes a sputtering method. There are a type in which an SiC layer is formed by irradiating carbon ions after an Si layer is formed by sputtering, and a type in which an SiC film is formed by sputtering. Etching is performed until the initial defect layer of the sputtered Si layer or SiC layer is exposed, and migration of Si or SiC is promoted by the etching energy, and Si or SiC is added to the defective portion (gap) of the initial defect layer. The initial defect layer was improved by the entry of atoms. As a result, it is possible to form a dense SiC film that is extremely thin and excellent in corrosion resistance and wear resistance without heating the film formation target.

  Conventionally, as a protective film for a magnetic head, a method of forming a two-layer film of an adhesion layer made of an Si film and a DLC (diamond-like carbon) film is known. In order to make the performance of each film sufficiently function. Each requires a thickness of about 1 nm. Therefore, the total thickness of the protective film is at least about 2 nm. On the other hand, in the present application, since it is a single layer film obtained by irradiating a Si layer of 1 nm or less with carbon ions to form silicon carbide, a SiC film of 1 nm or less can be formed. Therefore, an extremely thin SiC film can be formed as a protective film for a magnetic head that is difficult to form while being heated.

(Modification)
In the above-described embodiment, a step of adjusting the film quality such as insulation may be added to the SiC film. For example, the following film quality adjustment process is performed after step S40 shown in FIG. 2 or after step S50.

  FIG. 9 shows a procedure when the film quality adjustment process is performed after step S40. Irradiation with nitrogen ions modifies the surface region of the Si layer 200 to SiN as shown in FIG. Thereafter, when carbon ions are irradiated in step S50, the SiN region becomes SiCN and the Si layer becomes SiC as shown in FIG. 9B. For the irradiation of nitrogen ions, an ion beam method in which a nitrogen ion beam is irradiated is used. Alternatively, nitrogen ions may be extracted from an ECR plasma source containing nitrogen ions and irradiated.

  Note that instead of nitrogen ions, oxygen ions may be irradiated, or both nitrogen ions and oxygen ions may be irradiated simultaneously or sequentially. When oxygen ions are irradiated, after SiO is formed, it becomes SiOC by carbon ion irradiation. In addition, SiON is formed when both nitrogen ions and oxygen ions are irradiated, and then SiOCN is formed when carbon ions are irradiated.

  In the case of the second forming method, the processing from step S110 to step S130 in FIG. 5 is repeatedly performed. However, after the last repetition, that is, after step S140, a film quality adjustment step may be performed. A film quality adjustment step may be inserted before the last repetition. Also in this case, at least one of nitrogen ions and oxygen ions is irradiated.

  In the case of the third forming method, the film quality adjustment is performed after performing the process of step S240 in FIG. Also in this case, at least one of nitrogen ions and oxygen ions is irradiated.

  Each of the embodiments described above may be used alone or in combination. This is because the effects of the respective embodiments can be achieved independently or synergistically. In addition, the present invention is not limited to the above embodiment as long as the characteristics of the present invention are not impaired.

  1: magnetic head slider, 1a: substrate surface, 200: Si layer, 200a: gap, 201: SiC layer

Claims (8)

A first step of etching the Si film on the film formation surface until the initial defect layer is exposed after forming a silicon film on the film formation surface by a sputtering film formation method without heating;
A second step of depositing Si particles on the Si film etched in the first step by a sputtering film-forming method without heating, thereby forming the Si film with a predetermined thickness;
And a third step of irradiating the Si film having the predetermined thickness with carbon ions to convert the Si film into SiC. The SiC film formation method according to claim 1,
A step of irradiating at least one of nitrogen ions and oxygen ions is provided between the second step and the third step or after the third step, and a layer in which SiC is nitrided, SiC is oxidized Any one of the formed layer and the layer obtained by oxynitriding SiC is formed on the SiC film. In the SiC film formation method of Claim 1 or 2,
The SiC film forming method, wherein the second step is performed after the first step is repeated a plurality of times. A first step of etching the SiC film on the film formation surface until the initial defect layer is exposed after forming the SiC film on the film formation surface by a sputtering film formation method without heating;
And a second step of depositing SiC particles on the SiC film etched in the first step by a sputtering film forming method without heating, and using the SiC film as a SiC film having a predetermined thickness. A SiC film forming method characterized by the above. In the SiC film formation method of Claim 4,
A step of irradiating at least one of nitrogen ions and oxygen ions is provided after the second step, and any one of the SiC nitrided layer, the SiC oxidized layer, and the SiC oxynitrided layer is an SiC film. A method for forming a SiC film, comprising: In the SiC film formation method of Claim 4 or 5,
The SiC film forming method, wherein the second step is performed after the first step is repeated a plurality of times.   A step of forming a Si film on the film formation surface by a sputtering film formation method without heating, a step of etching the Si film until the initial defect layer is exposed, and irradiating the etched Si film with carbon ions. A method of forming a SiC film having a predetermined thickness in which a plurality of the SiC layers are stacked, by sequentially repeating a step of forming a SiC layer by converting to SiC. In the SiC film formation method of Claim 7,
Before or after the last SiC layer forming step in the repeated SiC layer forming step, a step of irradiating at least one of nitrogen ions and oxygen ions is provided, and a layer in which SiC is nitrided, SiC is oxidized Any one of the layer and the layer in which SiC is oxynitrided is formed on the SiC film.

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