Thin-film patterning method, manufacturing method of thin-film device and manufacturing method of thin-film magnetic head

A method of patterning a thin film includes a step of forming at least one strippable conductive film on a surface of a thin film to be patterned, a step of forming a mask on the at least one strippable conductive film, a step of patterning the thin film to be patterned by dry etching using the mask, and a step of removing the at least one strippable conductive film.

FIELD OF THE INVENTION

The present invention relates to a method of patterning a thin film by using a dry etching technique or patterning a resist film by using an electron beam (EB) writing or pattern generation technique, to a method of manufacturing a thin-film device using this patterning method, and to a method of manufacturing a thin-film magnetic head using this patterning method.

DESCRIPTION OF THE RELATED ART

FIGS. 1ato1gillustrate processes, in a conventional thin-film patterning method, of forming a resist pattern on a thin-film to be patterned by using an EB writing device and of dry etching the thin-film using the resist pattern as a mask.

First, on a substrate10shown inFIG. 1a, a thin film to be patterned11is deposited by for example sputtering as shown inFIG. 1b.

Then, as shown inFIG. 1c, after a resist film12for EB writing is coated on the thin film to be patterned11, desired regions to be remained of the resist film12are radiated with EB from the EB writing device.

Then, as shown inFIG. 1d, the radiated resist film is developed by a developing solution and thus a patterned resist film12′ is obtained.

The above-mentioned resist-patterning process is applicable in case that the resist film12is made of a negative type resist material. If a positive type resist material is used, portions of the resist film other than desired regions to be remained are radiated with EB.

Thereafter, as shown inFIG. 1e, dry etching such as ion milling or reactive ion etching (RIE) is performed with respect to the thin film to be patterned11using the patterned resist film12′ as an etching mask and thus a patterned thin film11′ is obtained as shown inFIG. 1f.

Then, as shown inFIG. 1g, the patterned resist mask12′ is removed by an organic solvent to remain only the patterned thin film11′.

However, according to the above-mentioned conventional resist patterning method using the EB writing device, if the resist film12is radiated with EB, the thin film to be patterned11under the film12may be breakdown by electrostatic charge causing an entire loss of its inherent characteristics due to a high EB acceleration voltage of for example 50 kV. Particularly, this tendency is strong in case that a thin film to be patterned is a multi-layered structure thin film such as a giant magnetoresistive effect (GMR) thin-film used in a thin-film magnetic head. Therefore, it is quite difficult to use the EB writing technique in a resist patterning process of such multi-layered structure thin film.

Even if a charge-prevention film is formed on the resist film12, it is difficult to prevent the thin film to be patterned11from breakdown by electrostatic charge due to radiation of EB.

If the resist film12is patterned by using an optical patterning technique, the breakdown due to static charge will not occur during the resist patterning process. However, during a dry etching process performed after the resist patterning process, the thin film to be patterned11may sometimes be breakdown by electrostatic charge causing an entire loss of its inherent characteristics. Particularly, this tendency is strong in case that a thin film to be patterned is a multi-layered structure thin film such as a GMR thin-film. This is because bias voltage and/or charge of etching ions may be applied to the thin film to be patterned11during dry etching.

SUMMARY OF THE INVENTION

It is therefore an object of the present invention to provide a thin-film patterning method, a method of manufacturing a thin-film device and a method of manufacturing a thin-film magnetic head, whereby a substrate, a film or a thin film to be patterned on which a resist pattern is formed can be prevented from being damaged due to electrostatic charge applied by EB.

Another object of the present invention is to provide a thin-film patterning method, a method of manufacturing a thin-film device and a method of manufacturing a thin-film magnetic head, whereby a thin film to be patterned can be prevented from being damaged due to electric charge applied by dry etching.

According to the present invention, a method of patterning a thin film includes a step of forming at least one strippable conductive film on a surface of a thin film to be patterned, a step of forming a mask on the at least one strippable conductive film, a step of patterning the thin film to be patterned by dry etching using the mask, and a step of removing the at least one strippable conductive film. In a method of manufacturing a thin-film device and in a method of manufacturing a thin-film magnetic head, at least a part of a thin-film pattern is fabricated by using this thin-film patterning method.

After the strippable conductive film is formed on the thin film to be patterned and then the mask is formed on the strippable conductive film, the dry etching is performed. Thus, electric charge due to the bias and/or charged ions of the dry etching will escape to the strippable conductive film, and therefore the thin film to be patterned will never be damaged by electrostatic discharge.

It is preferred that the at least one strippable conductive film is a conductive organic film.

It is also preferred that the at least one strippable conductive film is an insulating organic film and a conductive film such as a metallic material film or a conductive organic film, formed on the insulating organic film. In this case, preferably, the mask is formed by forming a resist film on the conductive film and then by patterning the resist film using EB writing method.

It is preferred that the conductive film is a grounded film. If the conductive film is grounded, more reliable prevention of the breakdown due to electrostatic discharge can be expected.

According to the present invention, also, a method of patterning a thin film includes a step of forming at least an insulating organic film and a conductive film on a surface on which a resist pattern is to be formed, a step of forming a resist film on the conductive film, and a step of patterning the resist film using EB writing method.

Since such the two layers is deposited on a surface on which a resist pattern is to be formed, charge due to EB will escape to the conductive film resulting that the thin film to be patterned will never be charged and a breakdown of this thin film due to electrostatic discharge can be effectively prevented. Thus, the EB writing method can be adopted to form a resist pattern on a thin film and therefore it is possible to greatly increase resolution of patterning and to extremely improve the patterning precision.

According to the present invention, furthermore, a method of patterning a thin film includes a step of forming at least an insulating organic film and a conductive film on a surface of a thin film to be patterned, a step of forming a resist film on the conductive film, a step of patterning the resist film using EB writing method, a step of patterning the thin film to be patterned by dry etching using the patterned resist film as a mask, and a step of removing the at least insulating organic film and conductive film.

After depositing such the two layers on the thin film to be patterned and the resist film is deposited on the two layers, the resist film is cured for patterning by EB writing. Thus, charge due to EB will escape to the conductive film resulting that the thin film to be patterned will never be charged and a breakdown of this thin film due to electrostatic discharge can be effectively prevented. Therefore, the EB writing method can be adopted to form a resist pattern on a thin film and then it is possible to greatly increase resolution of patterning and to extremely improve the patterning precision.

It is preferred that the conductive film is a metallic material film or a conductive organic film.

Preferably, the conductive film is a grounded film. If the conductive film is grounded, more reliable prevention of the breakdown due to electrostatic discharge can be expected.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIGS. 2ato2iillustrate processes of a thin-film patterning in a preferred embodiment according to the present invention. In this embodiment, a resist film is cured by EB to form a resist pattern and then a thin film to be patterned is patterned by using the formed resist pattern. The thin film to be patterned may be any film applicable in a thin-film device. In a thin-film magnetic head, the thin film to be patterned may be a thin film of a magnetic pole, or a thin film or a multi-layered film of a magnetoresistive effect (MR) element for example.

As shown inFIG. 2a, first, a substrate or an under layer20on which a thin film to be patterned will be formed is prepared. On this substrate or under layer20, a thin film to be patterned21is deposited by sputtering for example as shown inFIG. 2b.

Then, as shown inFIG. 2c, an insulating organic film22as a strippable film is coated on the thin film21, and, as shown inFIG. 2d, a conductive film23is formed on the film22by sputtering or coating.

Thereafter, as shown inFIG. 2e, a resist film24for EB writing is coated on the conductive film23and then desired regions to be remained of the resist film24are radiated with EB from the EB writing device.

Then, as shown inFIG. 2f, the radiated resist film is developed by a developing solution and thus a patterned resist film24′ is obtained.

The above-mentioned resist-patterning process is applicable in case that the resist film24is made of a negative type resist material. If a positive type resist material is used, portions of the resist film other than desired regions to be remained are radiated with EB.

Thereafter, as shown inFIG. 2g, dry etching such as ion milling using Ar ions or RIE using Ar ions is performed with respect to the thin film to be patterned21using the patterned resist film24′ as an etching mask, so that a patterned conductive film23′, a patterned insulating organic film22′ and a patterned thin film21′ are obtained as shownFIG. 2h.

Then, the patterned insulating organic film22′ is melted by an organic solvent to remove this melted film22′ and also the patterned conductive film23′ and the resist film24′ on the film22′. As a result, as shown inFIG. 2i, only the patterned thin film21′ is remained.

The strippable film is not limited to the aforementioned insulating organic film. Any film is applicable as the strippable film if it can be formed as a thin film by coating for example and melted by an organic solvent. For example, a conductive organic film which will be mentioned later is applicable.

As for the insulating organic film22, an organic resin film material such as resist film material may be used. More specifically, the resist film material may be negative resist materials such as polyglycidyl methacrylate, polymer of glycidyl methacrylate and ethyl acrylate, chloromethylation polystyrene, polyvinylphenol and azide compound, and novolak resin with cross linking agent and acid generating agent, or positive resist materials such as polymethyl methacrylate, poly(butene-1-sulfone), novolak resin with solubilizing inhibitor of for example PMPS (poly(2-methylpentene-1-sulfone), poly(2,2,2-trifluoroethyl-2-chloroacrylate), copolymer of α-methyl styrene and α-chloro acrylic acid, and novolak resin with quinonediazide.

As for the conductive film23, any kind of metallic film material may be used. Instead of the metallic film material, carbon film material or conductive organic film material may be used. More specifically, the conductive organic film material may be poly(isothianaphthenedil sulfonate), TCNQ chain polymer, poly(3-thienylalkanesulfonic acid compound), or ammoniate of polyaniline sulfonate.

According to this embodiment, after depositing two layers of the insulating organic film22that is the strippable film and the conductive film23on the thin film to be patterned21, the resist film24is deposited on the two layers and then the resist film24is cured for patterning by EB writing. Thus, electric charge due to the EB will escape to the conductive film23with a larger area, and therefore the thin film to be patterned21will never be charged resulting that a breakdown of the thin film21due to electrostatic discharge can be effectively prevented. As a result, since the EB writing method can be adopted to form a resist pattern on a thin film, it is possible to greatly increase resolution of patterning and to extremely improve the patterning precision.

In addition, after depositing the two layers of the insulating organic film22and the conductive film23on the thin film to be patterned21and the resist film24is patterned, the dry etching is performed. Thus, electric charge due to the bias and/or charged ions of the dry etching will escape to the conductive film23with a larger area, and therefore the thin film to be patterned21will never be charged resulting that a breakdown of the thin film21due to electrostatic discharge can be effectively prevented.

If the conductive film23is grounded, more reliable prevention of the breakdown due to electrostatic discharge can be expected.

In the aforementioned embodiment ofFIGS. 2ato2i, the two layers of the insulating organic film22and the conductive film23are deposited on the thin film to be patterned21and then the resist pattern is formed on the two layers. However, in modification, an additional film may be deposited on the two layer and then the resist pattern is formed on the two layers. Furthermore, in another modification, a charge-prevention film may be formed over the resist film24and then the radiation of EB is executed.

FIGS. 3ato3iillustrate processes of a thin-film patterning in another embodiment according to the present invention. In this embodiment, a resist film is cured by a normal optical exposure to form a resist pattern and then a thin film to be patterned is patterned by using the formed resist pattern. The thin film to be patterned may be any film applicable in a thin-film device. In a thin-film magnetic head, the thin film to be patterned may be a thin film of a magnetic pole, or a thin film or a multi-layered film of a MR element for example.

As shown inFIG. 3a, first, a substrate or an under layer30on which a thin film to be patterned will be formed is prepared. On this substrate or under layer30, a thin film to be patterned31is deposited by sputtering for example as shown inFIG. 3b.

Then, as shown inFIG. 3c, an insulating organic film32as a strippable film is coated on the thin film31, and, as shown inFIG. 3d, a conductive film33is formed on the film32by sputtering or coating.

Thereafter, as shown inFIG. 3e, a resist film34is coated on the conductive film33and then desired regions to be remained of the resist film34are exposed by an optical exposure device using an exposure mask.

Then, as shown inFIG. 3f, the exposed resist film is developed by a developing solution and thus a patterned resist film34′ is obtained.

The above-mentioned resist-patterning process is applicable in case that the resist film34is made of a negative type resist material. If a positive type resist material is used, portions of the resist film other than desired regions to be remained are exposed.

Thereafter, as shown inFIG. 3g, dry etching such as ion milling using Ar ions or RIE using Ar ions is performed with respect to the thin film to be patterned31using the patterned resist film34′ as an etching mask, so that a patterned conductive film33′, a patterned insulating organic film32′ and a patterned thin film31′ are obtained as shownFIG. 3h.

Then, the patterned insulating organic film32′ is melted by an organic solvent to remove this melted film32′ and also the patterned conductive film33′ and the resist film34′ on the film32′. As a result, as shown inFIG. 3i, only the patterned thin film31′ is remained.

The strippable film is not limited to the aforementioned insulating organic film. Any film is applicable as the strippable film if it can be formed as a thin film by coating for example and melted by an organic solvent. For example, a conductive organic film which will be mentioned later is applicable.

As for the insulating organic film32, an organic resin film material such as resist film material may be used. More specifically, the resist film material may be negative resist materials such as polyglycidyl methacrylate, polymer of glycidyl methacrylate and ethyl acrylate, chloromethylation polystyrene, polyvinylphenol and azide compound, and novolak resin with cross linking agent and acid generating agent, or positive resist materials such as polymethyl methacrylate, poly(butene-1-sulfone), novolak resin with solubilizing inhibitor of for example PMPS (poly(2-methylpentene-1-sulfone), poly(2,2,2-trifluoroethyl-2-chloroacrylate), copolymer of α-methyl styrene and α-chloro acrylic acid, and novolak resin with quinonediazide.

As for the conductive film33, any kind of metallic film material may be used. Instead of the metallic film material, carbon film material or conductive organic film material may be used. More specifically, the conductive organic film material may be poly(isothianaphthenedil sulfonate), TCNQ chain polymer, poly(3-thienylalkanesulfonic acid compound), or ammoniate of polyaniline sulfonate.

According to this embodiment, after depositing the two layers of the insulating organic film32and the conductive film33on the thin film to be patterned31and the resist film34is patterned, the dry etching is performed. Thus, electric charge due to the bias and/or charged ions of the dry etching will escape to the conductive film33with a larger area, and therefore the thin film to be patterned31will never be charged resulting that a breakdown of the thin film31due to electrostatic discharge can be effectively prevented.

If the conductive film33is grounded, more reliable prevention of the breakdown due to electrostatic discharge can be expected.

In the aforementioned embodiment ofFIGS. 3ato3i, the two layers of the insulating organic film32and the conductive film33are deposited on the thin film to be patterned31and then the resist pattern is formed on the two layers. However, in modification, an additional film may be deposited on the two layer and then the resist pattern is formed on the two layers. Also, in another modification, only a single strippable conductive film may be deposited on the substrate and then the patterning of the resist film is performed. In a further modification, a charge-prevention film may be formed over the resist film34and then the patterning of the resist film is executed.