JP3569009B2 - Method for manufacturing magnetic device - Google Patents

Description

[0001]
[Industrial applications]
The present invention relates to a magnetic device such as a thin film magnetic head and a thin film magnetic sensor, and more particularly to a magnetic device having a fine magnetic thin film pattern.
[0002]
[Prior art]
In recent years, with the trend of miniaturization and weight reduction of systems, devices are becoming lighter and shorter, and the demand is expected to increase in the future. Lighter and thinner devices have been innovatively developed by thinning functional materials. The thinning of functional materials is mainly active in the field of electronic devices, but in the field of magnetic devices, thin film magnetic heads are also the mainstays, and it is expected that other magnetic devices will be developed into thin films in the future. Have been.
[0003]
However, the difficulty of fine processing of magnetic materials is one of the factors that hinder the thinning of magnetic devices. This is because a magnetic thin film can be formed relatively easily by using a sputtering method or the like, but when a magnetic thin film is finely processed, a technique such as reactive ion etching (RIE) used in a semiconductor device process is used. This is because it is difficult to apply the conditions without changing the conditions such as the type of gas used. For this reason, only magnetic devices that do not require fine processing of the magnetic thin film itself, such as magnetic disks, magneto-optical disks, and parts of magnetic heads (MIG heads, laminate heads, etc.), have been targeted for thinning. I was
[0004]
For example, the magnetic thin film of the HDD magnetic head is currently formed by a wet plating method, and its tip is as fine as several microns, but the wet plating method achieves further miniaturization and higher density. It is difficult.
[0005]
A method of finely processing a magnetic thin film using a dry process is described in, for example, IEEE Trans. Mag. , 27 (6) 1991, pp. 139-157. Attempts disclosed in U.S. Pat. Nos. 4,888 to 4,890 have been made, and a fine pattern of a magnetic thin film has been successfully formed. However, in this method, there is a trade-off between removing the etching residue and avoiding side etching. In this case, just etching is performed to avoid side etching and the pattern accuracy is improved, so that a residue remains, and a special post-treatment is required to remove the residue, which is not practical.
[0006]
At present, there is almost no report on microfabrication of magnetic thin films, and this is a bottleneck for future miniaturization and weight reduction of magnetic devices. Be further possible fine pattern formation of the magnetic thin film, considering the incorporation of the pattern of the magnetic thin film magnetic device, the magnetic material such as generally Fe from poor in corrosion resistance than that of the semiconductor material, and its surrounding magnetic thin film pattern Practical demands include good adhesion with an insulating film and the like, and low deterioration of the magnetic thin film pattern itself due to oxidation and the like.
[0007]
[Problems to be solved by the invention]
The present invention has been made to solve the above problems, and has excellent adhesion to surrounding insulating films and the like, excellent reliability against deterioration, a high processing speed, a high selectivity to a mask, and a small residue. It is an object of the present invention to provide a magnetic device having a magnetic thin film pattern that can be easily processed into a good anisotropic shape with high precision.
[0008]
[Means and Actions for Solving the Problems]
The magnetic device according to the present invention includes a pattern of a magnetic thin film containing at least one element selected from Fe, Co, and Ni, and a first deposition film directly deposited on a side wall of the pattern of the magnetic thin film. And a second deposition film deposited outside of the first deposition film , wherein the angle between the side wall of the pattern of the magnetic thin film and the underlayer is greater than the angle of the first deposition film. The taper angle formed between the substrate and the base is gentle .
[0009]
The magnetic thin film targeted in the present invention is not particularly limited as long as it is a material containing at least one element selected from Fe, Co and Ni as a main component, and is a single metal made of Fe, Co or Ni. , NiFe, and CoFe, and alloys such as FeSiAl, CoZrNb, FeTaN, FeB, FeCoSiB, and FeCoZr. The material of the first deposited film directly deposited on the side wall of the pattern of the magnetic thin film is not particularly limited, but is usually an insulating material, typically, carbon, hydrocarbon, silicon oxide, aluminum oxide, At least one selected from the group consisting of silicon nitride and boron nitride is used. The thickness of the first deposited film is preferably 1 to 200 nm, more preferably 50 nm or less. Further, a second deposition film having a different material or structure from the first deposition film is deposited outside the first deposition film.
[0010]
In the present invention, the method for forming the magnetic thin film is not particularly limited, but evaporation or sputtering is typical. As the sputtering, various methods such as magnetron sputtering, ion beam sputtering, and reactive sputtering can be used. It should be noted that MBE, ICB, and in rare cases, MOCVD or the like can be used in addition to vapor deposition or sputtering.
[0011]
To form a pattern of the magnetic thin film, a predetermined mask material is formed on the magnetic thin film and etched. At this time, the masking material for patterning is preferably a material that causes little thermal damage in the etching process and can have a certain selectivity with the magnetic thin film, and is determined in consideration of an etching gas and an etching temperature. Specifically, in addition to the resist used for processing thin films other than ordinary magnetic thin films, oxides, nitrides, carbides, borides, and other materials that are heat resistant and have a high selectivity with magnetic thin films, For example, Al ₂ O ₃ , SiO ₂ , Si ₃ N _{4 and the} like can be typically used. However, they need not have a stoichiometric composition.
[0012]
When a resist is used as a mask material, ordinary PEP may be performed. When an oxide or a nitride is used as a mask material, a magnetic thin film and a film of the mask material are used. A step of sequentially forming the resist, patterning a resist on the mask material by PEP, and etching the mask material can be used. At this time, the mask material may be wet-etched. However, since the wet etching is isotropic, it is not preferable that the magnetic thin film itself is etched at this time. Also, if the selectivity between the magnetic thin film and the mask is not so good at the time of etching the magnetic thin film in a later step, the anisotropic shape of the magnetic thin film is damaged. It is desirable to apply an anisotropic etching process such as RIE, in particular. More specifically, for example, the mask material can be processed by RIE using BCl ₃ , CF ₄ , CHF ₃ or the like. When the anisotropic etching is applied to the processing of the mask material as described above, the underlying magnetic thin film may be slightly etched. When a mask material other than the resist is used, the resist on the mask material is desirably removed, and this can be performed by oxygen plasma ashing, removal with a solvent using a stripper, or a combination thereof. . The above process is a stage before processing the magnetic thin film itself.
[0013]
In the present invention, in forming the magnetic thin film pattern, (1) a method of forming the first deposited film on the side wall of the magnetic thin film pattern simultaneously with the patterning of the magnetic thin film during processing of the magnetic thin film may be adopted. Then, (2) a method of processing the magnetic thin film first and then forming the first deposition film on the side wall of the magnetic thin film pattern may be adopted. In any of these methods, the first deposited film is deposited on the side wall of the magnetic thin film pattern, whereby sufficient adhesion to the periphery of the magnetic thin film pattern is obtained, The reliability of the thin film pattern can be effectively improved. In addition, in the method (1), since the incidence of radicals and ions on the side walls can be prevented even during the processing of the magnetic thin film, the reliability during the processing can be improved, and the processed shape of the magnetic thin film pattern, particularly, the anisotropic shape can be improved. It is also preferable from the viewpoint of controlling the taper angle of the first deposition film.
[0014]
As a more specific method (1), (a) a mask material made of a material other than a resist is mainly physically gently etched at the time of magnetic thin film processing, and is re-adhered to the side wall of the magnetic thin film pattern being etched. And (b) a method of adding an appropriate amount of a polymerizable gas typified by CH ₄ or the like to an etching gas for the magnetic thin film to form a product such as a polymerizable substance only on the side wall of the magnetic thin film. . In the method (b), since there is an ion bombardment effect on the film surface to be etched, the formation state of a polymerizable substance or the like can be controlled between the side wall and the film surface. As described above, the material of the first deposited film is not particularly limited. However, in the method (a), oxide, nitride, carbide, boride, and the like, typically, SiO ₂ , Al ₂ O ₃ , and Si _{3 are used.} N ₄ and BN are formed. However, it is not necessary that these materials have a stoichiometric composition. Examples of the polymerizable substance used in the method (b) include an organic substance containing carbon or hydrocarbon, and these polymers are formed as the first deposition film. Further, if an appropriate amount of SiCl ₄ and O ₂ , SiCl ₄ and N ₂ , TiCl ₄ and O ₂ , TiCl ₄ and N ₂ or BCl ₃ and N ₂ are added to the etching gas, Si— O, Si-N, Ti-O, Ti-N, and BN can also be formed.
[0015]
On the other hand, as a method of forming the first deposited film on the side wall of the magnetic thin film pattern after processing the magnetic thin film as in (2), for example, oblique sputtering can be mentioned. That is, the processed magnetic thin film pattern is placed in a sputtering chamber, and sputtering is performed with the film surface inclined with respect to the sputter incident direction so that the first deposited film is efficiently formed on the magnetic thin film pattern side wall. In this case, in order to uniformly form the first deposition film on the side wall of the magnetic thin film pattern, the film surface is rotated while being inclined with respect to the sputter incidence direction. Also in this method, the material of the first deposited film is not particularly limited, but typically, SiO ₂ , Al ₂ O ₃ , Si ₃ N ₄ or the like is used as in the method (1). Also in this case, it is not necessary that these substances have a stoichiometric composition. In particular, the method (2) is disadvantageous in terms of the deposition rate of the first deposited film, so that the first deposited film is thick enough to obtain a sufficient protective effect and thin enough not to deteriorate the production efficiency. Is preferred.
[0016]
As described above, the thickness of the first deposited film in the present invention is preferably 1 to 200 nm, more preferably 50 nm or less, from the viewpoint of sufficiently increasing the reliability without lowering the productivity.
[0017]
Further, in the present invention, setting the taper angle between the base on which the magnetic thin film pattern is formed and the first deposition film to be not more than 80 ° improves the step coverage of the insulating film and the like around the magnetic thin film pattern. Above. However, since it is difficult to form the first deposition film having a taper angle of less than 45 ° in terms of manufacturing, a more preferable taper angle is 45 to 80 ° from the viewpoint of productivity.
[0018]
In the present invention, after the formation of the first deposition film, a second deposition film is formed outside the first deposition film for a post-process and device formation. In order to form the second deposited film, a normal sputtering method is typically used, and the film surface is formed to be perpendicular to the incident direction of the sputter in order to obtain a high deposition rate. The second deposited film material is also generally an insulating material, but is not particularly limited. However, in the magnetic thin film pattern of the present invention, it is important that the first deposited film and the second deposited film are made of different materials, or that the same material has a different film structure. . The structure of the film includes a crystal state, a microscopic morphology, a chemical bonding state, a nearest atom arrangement, and the like. These can be detected by analysis of ED, section SEM, TEM, XPS, EXAFS, and the like.
According to the present invention as described above, it is possible to provide a magnetic device having a magnetic thin film pattern having a good shape and high reliability in element characteristics, and can be manufactured with high productivity.
[0019]
【Example】
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
Example 1
FIG. 1 is a sectional view showing an example of a magnetic thin film pattern constituting a magnetic device according to the present invention. In FIG. 1, a pattern of a base insulating film 2 and a magnetic thin film 3 is formed on a substrate 1. A first deposition film 4 is directly deposited on the side wall of the pattern of the magnetic thin film 3, and a second deposition film 5 is formed outside the first deposition film 4. Further, an upper insulating film 6 is formed on these upper surfaces.
[0020]
Here, a prototype of the recording magnetic pole tip of the magnetic recording head was simulated. Note that this embodiment was performed for the purpose of clarifying the effects of the present invention, and silicon was used as the substrate 1. However, it goes without saying that the substrate material is appropriately selected according to the intended magnetic device. For example, in a practical magnetic recording head, ferrite, non-magnetic ceramic, or the like is used as the substrate material.
[0021]
2 and 3 are cross-sectional views showing one example of a method for forming the magnetic thin film pattern shown in FIG. Hereinafter, a detailed description will be given with reference to these drawings.
First, the substrate 1 made of cleaned Si is fixed to a substrate support of a multi-source sputtering apparatus, and while rotating the substrate support relative to the target, an SiO ₂ target is sputtered to form a 200 nm thick SiO _2. The underlying insulating film 2 was formed. Thereafter, a CoZrNb target was continuously sputtered to form a magnetic thin film 3 made of CoZrNb having a thickness of 2 μm. Further, the SiO ₂ target was continuously sputtered to form a mask material 11 made of SiO ₂ having a thickness of 200 nm, and then the substrate was taken out ((a) illustration).
[0022]
Next, after forming a pattern of the resist 12 on the mask material 11 by PEP, the mask material 11 is set in a dry etching apparatus and etched using CHF ₃ gas to thereby form a mask material on the magnetic thin film 3. Eleven patterns were formed ((b) illustration).
[0023]
Next, the resist 12 was removed by oxygen plasma ashing. Subsequently, a sample in which the patterns of the base insulating film 2, the magnetic thin film 3, and the mask material 11 are formed on the substrate 1 is placed in an RIE apparatus, and chlorine, carbon monoxide, a small amount of methane, and a small amount of hydrogen are mixed. The magnetic thin film 3 was subjected to RIE using gas plasma. The action of each reactive gas used here is as follows. Chlorine has a function of forming a magnetic chloride on the surface of the magnetic thin film. Carbon monoxide has a function of reacting with the magnetic chloride formed on the surface to form a high-vapor-pressure magnetic carbonyl complex and evaporating it. Methane has the function of forming the first deposited film 4 on the side wall of the magnetic thin film. Hydrogen mainly has an action of preventing a plasma decomposition product of carbon monoxide, particularly an oxygen-based radical, from reacting with the surface of the magnetic thin film to form an oxide. Plasma plays a role of imparting reactivity by dissociating or exciting / ionizing each gas, and a role of realizing anisotropic processing by injecting ions perpendicularly to the film surface. In this embodiment, the processing temperature at the time of etching was set to 200 ° C. by focusing the infrared lamp on the sample.
[0024]
In this etching process, the surface of the magnetic thin film 3 which is subjected to the ion bombardment is removed by the reaction, evaporation and physical sputter etching. At the same time, the dissociation products of methane are mainly plasma-polymerized on the side walls of the magnetic thin film 3 and the mask material 11, and the first deposition film 4 adheres. FIG. 2C is a diagram showing a stage during the etching of the magnetic thin film.
[0025]
The etching was further advanced from this state, and the etching was continued (over-etched) for twice as long as the just-etched time of the magnetic thin film measured in advance, and a sample was taken out ((d) illustrated).
[0026]
Here, in the prior art, it is reported that the magnetic thin film is finished by just etching in order to obtain an anisotropic shape, and that the residue is generated when the process is completed by just etching. On the other hand, in the present invention, since the first deposition film is formed on the side wall of the magnetic thin film pattern, a favorable anisotropic shape is not impaired even by overetching, and the process margin is greatly increased. This is extremely important even in the case of etching a magnetic thin film in which no residue is generated. Even if the uniformity of plasma during etching is somewhat poor, the uniformity over a large area can be significantly improved as a magnetic device. .
[0027]
Next, the sample was set in a sputtering apparatus, and a SiO ₂ target was sputtered to form a _second deposition film 5 on the entire surface (illustrated in (e)). At this time, since the first deposition film 4 is formed on the pattern side wall of the magnetic thin film 3, the anisotropic shape of the magnetic thin film pattern itself is as steep as 85 ° or more between the pattern side wall and the base. Nevertheless, since the taper angle formed between the first deposition film 4 and the base is gentle at about 75 °, the step coverage of the second deposition film 5 is improved. This has the effect of improving the adhesion between the films, improving the degree of freedom in the subsequent steps, and improving the reliability of the device.
[0028]
Further, the sample on which the second deposition film 5 was formed was polished until the magnetic thin film 3 was exposed, and the upper surface was flattened ((f) illustration).
Finally, an upper insulating film 6 made of SiO ₂ having a thickness of 100 nm was formed by sputtering to obtain a simulated pattern at the tip of the magnetic pole of the magnetic recording head as shown in FIG. The portion shown in FIG. 1 corresponds to a one-sided magnetic pole pattern of an in-plane magnetic recording head, and a magnetic thin film pattern similar to that shown in FIG. 1 is further formed thereon to be used as a magnetic recording head for in-plane recording. it can. In this case, the upper insulating film 6 corresponds to a magnetic gap that plays an important role in recording, but as is clear from the above description, according to the present embodiment, the magnetic gap can be formed with high accuracy.
[0029]
Example 2
In this embodiment, a case where SiO ₂ is used for both the first deposition film and the second deposition film will be described. The following description focuses on the differences from the first embodiment. The process before the RIE process of the magnetic thin film is the same as that of the first embodiment except that the thickness of the mask material 11 is 400 nm. In the RIE process of the magnetic thin film, a mixed gas of chlorine, carbon monoxide, boron trichloride and argon was used. The roles of chlorine and carbon monoxide are as described above. Boron trichloride has a function of capturing decomposition products of carbon monoxide, a function of mainly capturing oxygen-based decomposition products generated by physical etching of the mask material, and a function of capturing water-based impurities remaining in the RIE chamber. Argon plays a role of physically etching the mask material to form the first deposition film 4 on the side wall of the magnetic thin film pattern.
[0030]
In this embodiment, physical etching of the mask material 11 and reattachment to the side wall of the magnetic thin film pattern are simultaneously advanced in parallel with RIE of the magnetic thin film 3, and SiO ₂ is used as the first deposition film 4. Formed. At this time, the angle between the side wall of the magnetic thin film pattern and the base was 85 ° or more, and the taper angle formed between the first deposition film 4 and the base was about 75 °.
[0031]
In the present embodiment, both the first and second deposition films are made of SiO ₂ . However, a sample was taken out after forming the first and second deposited films, respectively, and micro-Auger analysis was performed on these deposited films, and the results of the two analyzes were compared. The content ratio of O compared to Si was smaller than that of the deposited film, and magnetic chloride and boron were detected, though in trace amounts, and both were clearly different in film quality.
[0032]
Example 3
In the present embodiment, a case will be described in which the first deposited film is formed after processing the magnetic thin film without forming the first deposited film during processing of the magnetic thin film. The steps before the RIE step of the magnetic thin film are the same as those in the first embodiment. In the RIE step of the magnetic thin film, a mixed gas of chlorine, carbon monoxide, and hydrogen was used to prevent the first deposition film from being formed on the side wall of the magnetic thin film during RIE. That is, the pattern after the RIE of the magnetic thin film is in a state without the first coating film 4 in FIG.
[0033]
Next, the first deposition film 4 was formed on the side wall of the magnetic thin film 3 by tilting the sample with respect to the direction of incidence of the sputter from the SiO ₂ target, and further rotating the sample to perform oblique sputtering. The advantage of oblique sputtering is that the first deposition film 4 can be formed with good step coverage even for the pattern of the magnetic thin film 3 having a steep anisotropic shape. On the other hand, the disadvantage is that the formation rate is extremely slow. Therefore, from a practical point of view, the angle of the first deposition film 4 with respect to the underlayer is gentler (about 65 to 75 °) than the pattern side wall (85 ° or more) of the magnetic thin film 3, and The pattern is formed as thin as possible to sufficiently protect the pattern, and the process ends.
[0034]
Next, the second deposition film 5 was formed by ordinary sputtering capable of high-speed formation. Also in this embodiment, similarly to the above embodiment, the overall step coverage is improved, and the effects of improving the process margin in the post-process and improving the reliability as a device can be obtained.
[0035]
Further, for comparison, a sample formed with a magnetic thin film pattern having an angle between the side wall and the base of 85 ° or more was formed on the sample without forming the first film by oblique sputtering, and the second film was formed on the sample by ordinary sputtering. The deposited film was formed directly.
[0036]
FIG. 4 schematically shows the result of cross-sectional SEM observation of the obtained sample. As shown in the figure, in the sample (FIG. 4A) in which the taper angle of about 60 to 75 ° is provided to the pattern side wall of the magnetic thin film 3 to form the first deposition film 4, the pattern of the magnetic thin film 3 The adhesion between the first deposition film 4 and the second deposition film 5 was good. On the other hand, in the sample in which the first deposited film was not formed (FIG. 4B), a gap was observed between the pattern of the magnetic thin film 3 and the second deposited film 5. However, if there is a gap between the magnetic thin film pattern and the surroundings, the deterioration of the magnetic thin film pattern made of a magnetic material, which generally does not have high resistance to corrosion, due to intrusion of moisture into the gap, etc., proceeds. Therefore, it is expected that the reliability of the device will decrease.
[0037]
Also in this embodiment, both the first deposited film and the second deposited film are made of SiO ₂ , but the film quality is different due to the difference in the formation process between the oblique sputtering and the normal sputtering. It can be revealed by analysis. In this example, the first deposited film contained more oxygen than the second deposited film, and had a higher surface roughness.
[0038]
On the other hand, when a film material which is not easily crystallized such as SiO ₂ used in the above-described embodiment and which has crystallinity even at room temperature sputtering, such as AlN, is used, the crystallographic method can be used. The difference between the first deposited film and the second deposited film can be clarified.
[0039]
In addition, the materials and forming steps of both the first deposited film and the second deposited film can be changed without departing from the spirit of the present invention, and it is obvious that all of them are included in the present invention.
[0040]
Further, in the above embodiment, the case where the present invention is applied to a magnetic recording head having a magnetic thin film pattern has been described. However, the present invention can be applied to other magnetic devices such as a magnetic sensor requiring a magnetic thin film of a predetermined pattern. Of course.
[0041]
【The invention's effect】
As described above in detail, according to the present invention, the adhesion between the magnetic thin film pattern and the insulating film around the magnetic thin film pattern is good, and the reliability of the magnetic device having the fine pattern of the magnetic thin film against the deterioration is improved. In addition, the productivity is remarkably improved.
[Brief description of the drawings]
FIG. 1 is a sectional view showing an example of a magnetic thin film pattern constituting a magnetic device according to the present invention.
FIG. 2 is a sectional view showing an example of a method of forming the magnetic thin film pattern of FIG.
FIG. 3 is a sectional view showing an example of a method of forming the magnetic thin film pattern of FIG.
FIG. 4 is a schematic view showing a cross section of a side wall portion of a magnetic thin film pattern manufactured in Example 3 of the present invention and a comparative example thereof.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... board | substrate, 2 ... base insulating film, 3 ... magnetic thin film, 4 ... 1st adhesion film, 5 ... 2nd adhesion film, 6 ... upper insulating film, 11 ... mask material, 12 ... resist.

Claims (3)

Forming a magnetic thin film containing at least one element selected from the group consisting of Fe, Co, and Ni on the lower ground; forming a pattern of the magnetic thin film by processing the magnetic thin film; And a taper angle formed between the first deposition film and the base becomes gentler than an angle formed between the side wall of the pattern of the magnetic thin film and the base. And a step of depositing a second deposition film outside the first deposition film. Wherein during the processing of the magnetic thin film, was added to the etching gas in the polymerizable gas, according to claim 1, characterized in that forming the first of the film deposition of the polymerizable material on the sidewalls of the magnetic thin film pattern A method for manufacturing a magnetic device. At the time of processing the magnetic thin film, etching is performed using at least one selected from oxides, nitrides, carbides and borides as a mask material on the magnetic thin film, and a mask is formed on sidewalls of the magnetic thin film pattern during etching. The method according to claim 1 , wherein the first deposition film is formed by re-adhering a material.

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