JPH10312063A - Method of forming photoresist pattern for lift-off - Google Patents

Abstract

(57) Abstract: Provided is a method for forming a lift-off photoresist pattern that can easily perform high-precision patterning when forming a lead electrode forming a thin-film magnetic head. SOLUTION: A first photoresist layer 11 is formed so as to leave an exposed portion 32a of a predetermined pattern on an electrode formation target surface 32.
Forming the first photoresist layer 11, exposing the first photoresist layer 11, exposing the second photoresist layer on the first photoresist layer 11 and the exposed portion 32a, and covering the exposed portion 32a. The step of exposing the second photoresist layer so as to form the unexposed portion 13 having such a shape, and the step of removing the exposed portions 11 and 12 of the first and second photoresist layers are lifted off. A photoresist pattern for use.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a lead electrode constituting a thin-film magnetic head for recording and reproducing data on and from a magnetic recording medium such as a magnetic disk, and more particularly to a method for forming a lead electrode pattern. The present invention relates to a method for forming a lift-off photoresist pattern.

[0002]

2. Description of the Related Art Various methods have been used for forming lead electrodes constituting a thin film magnetic head and the like. The most common formation method is to form a mask layer of photoresist in a desired pattern after forming a thin film layer, and perform physical etching such as ion milling or chemical etching such as wet etching. In this method, an unnecessary thin film layer is removed, and the thin film layer below the mask layer is formed in a desired pattern (lead electrode pattern).

However, in this method, after an unnecessary thin film layer to be etched is removed, a further lower layer may be removed or deteriorated. Therefore, for example, when a lead electrode is formed on a magnetoresistive film of a magnetoresistive thin film magnetic head, the thickness of the magnetoresistive film is usually as small as several tens to several hundred angstroms. It is difficult to use the above-described method in which the layer may be removed or deteriorated.

Therefore, conventionally, a method of forming a lead electrode pattern by a general lift-off method has been adopted. In this method, an unnecessary thin film on the photoresist pattern is formed by forming a photoresist pattern of a desired pattern on the magnetoresistive film, forming a thin film layer to be a lead electrode, and then removing the photoresist pattern. This is a method of forming an electrode pattern by removing a layer. When a lead electrode pattern is formed using this lift-off method, the cross-sectional shape of the photoresist pattern is made to be an overhang shape (also referred to as an inverted tapered shape), so that the lead electrode layer adheres to the sidewall of the photoresist pattern. This prevents the film edge from remaining at the pattern edge after lift-off.

As a method of making the cross-sectional shape of the photoresist pattern an overhang shape, the photoresist surface is subjected to ammonia treatment or chlorobenzene treatment,
The surface layer of the resist is altered to form a different solubility in the developer between the surface layer and the inner layer, and the inner layer is dissolved more than the surface layer in the photoresist development process,
There is a method of forming an overhang shape (hereinafter, this method of forming an overhang shape is referred to as “reverse taper processing”).
Also called).

[0006]

However, in the method of forming a lead electrode pattern by the lift-off method (the cross-sectional shape of the photoresist pattern is made to be an overhang shape) according to the above-mentioned prior art, variations in ammonia treatment or chlorobenzene treatment occur. Therefore, variations and the like also occur in the subsequent photoresist development process, making it difficult to improve the dimensional accuracy of patterning. In particular, in the case of manufacturing a magnetoresistive head, the interval between the lead electrodes on the magnetoresistive layer is the reproduction track width of the thin-film magnetic head, and today, the reproduction track width is becoming several microns or less. The dimensional accuracy of patterning when forming a lead electrode is an important factor. That is, since it is required to control this interval with high accuracy, it is a serious problem that the patterning accuracy at the time of forming the lead electrode is low.

SUMMARY OF THE INVENTION The present invention has been made to solve such a problem, and a lift-off photoresist pattern capable of easily performing high-precision patterning when forming a lead electrode constituting a thin-film magnetic head. It is an object of the present invention to provide a method for forming a film.

[0008]

According to a first aspect of the present invention, there is provided a method of forming a photoresist pattern for lift-off used in forming an electrode on a surface on which an electrode is to be formed. Forming a first photoresist layer in a pattern of, a step of exposing a predetermined portion of the first photoresist layer, and a second photoresist of a predetermined pattern on the first photoresist layer Forming a layer, exposing a predetermined portion of the second photoresist layer, and removing the exposed portion of the first and second photoresist layers, the electrode forming A photoresist pattern having an overhang shape is formed on the target surface. According to the method of forming a photoresist pattern for lift-off according to the present invention, the first and second photoresist layers are formed, predetermined areas are respectively exposed, and the exposed portions are removed, so that over exposure can be easily performed. A hang-shaped photoresist pattern can be formed. That is, according to the present invention, it is not necessary to perform an ammonia treatment, a chlorobenzene treatment, or the like which is conventionally required to form an overhang-shaped photoresist pattern. Therefore, it is possible to eliminate variations in the photoresist development process caused by variations in the ammonia treatment or the chlorobenzene treatment, thereby improving the dimensional accuracy of the lift-off photoresist pattern.

In the method of forming a photoresist pattern for lift-off according to the present invention, a step of forming a first photoresist layer so as to leave an exposed portion of a predetermined pattern on the surface on which the electrode is to be formed; Exposing one photoresist layer, forming a second photoresist layer on the first photoresist layer and the exposed portion, and exposing an unexposed portion shaped to cover the exposed portion. Preferably, the method further comprises the steps of exposing the second photoresist layer to form and removing the exposed portions of the first and second photoresist layers.
According to this preferred example, by forming the unexposed portion of the second photoresist layer so as to cover the exposed portion, a photoresist pattern having an overhang shape can be obtained relatively easily. Further, when the first photoresist layer is formed into a predetermined pattern or when the first photoresist layer is exposed, the dimensions of the photoresist pattern are determined, so that a lift-off photoresist pattern with high dimensional accuracy can be formed.

In the method of forming a photoresist pattern for lift-off according to the present invention, a step of forming a first photoresist layer on the surface on which the electrode is to be formed, and forming an unexposed portion of the first photoresist layer. Exposing the first photoresist layer, forming a second photoresist layer on the first photoresist layer, and covering the unexposed portion of the first photoresist layer. Exposing the second photoresist layer so as to form a second photoresist layer unexposed portion of a different shape,
Removing the exposed portions of the first and second photoresist layers. According to this preferred example, by forming the second photoresist layer unexposed portion in a shape that covers the first photoresist layer unexposed portion, the overhang-shaped photoresist pattern can be relatively easily formed. Can be obtained. In addition, since the dimensions of the photoresist pattern are determined when exposing the first photoresist layer and the second photoresist layer, a lift-off photoresist pattern with high dimensional accuracy can be formed.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 3 is a cross-sectional view of a magnetoresistive thin-film magnetic head having a lead electrode formed using a lift-off photoresist pattern according to the present invention.

As shown in FIG. 3, aluminum oxide (Al ₂ O ₃ ) or the like is formed by sputtering on a lower shield layer 30 formed by plating or sputtering a soft magnetic film such as permalloy. A lower gap insulating layer 31 is laminated, and a magnetoresistive film 32 formed by sputtering permalloy or the like is laminated thereon.

A lead electrode layer 33 made of, for example, gold (Au), copper (Cu), or tungsten (W) is formed on the magnetoresistive film 32 by sputtering and then patterned by lift-off described later. The upper gap insulating layer 34 is further formed thereon by sputtering Al ₂ O ₃ or the like. An upper shield layer 35 is formed on the upper gap insulating layer 34 by plating or sputtering a soft magnetic film such as permalloy.

Hereinafter, a method of forming a lift-off photoresist pattern when forming the lead electrode layer 33 will be specifically described. (First Embodiment) FIG. 1 is a sectional view showing a method for forming a lift-off photoresist pattern in a lead electrode forming step according to a first embodiment of the present invention. Hereinafter, a method of forming a lift-off photoresist pattern will be described with reference to FIGS. 1 (a) to 1 (f).

First, the magnetoresistive film 32 shown in FIG. 1A is formed on a lower gap insulating layer (not shown, see FIG. 3). The magnetoresistive film 32 is formed by sputtering permalloy or the like.

Next, as shown in FIG. 1B, a first photoresist 32a is left on the magnetoresistive film 32, leaving an exposed portion (hereinafter referred to as an "exposed portion") 32a of the magnetoresistive film 32. Using the first photoresist pattern 11
Is formed in a tapered shape. As for the shape of the taper, as shown in this figure, a case where the angle between the tapered object forming the taper and the end face of the tapered object is an acute angle is referred to as a “forward taper”, and a case where the angle is an obtuse angle. It is called "reverse taper". As shown in this figure, in the present embodiment, the first photoresist pattern 11 is formed with a forward taper without performing reverse taper processing as in the prior art. Therefore, the control when forming the side wall of the first photoresist pattern 11 is very easy, and the patterning accuracy of the first photoresist pattern 11 is extremely high. Next, the first photoresist pattern 11 is exposed to ultraviolet light to make it soluble in a developing solution.

Next, as shown in FIG. 1C, a second photoresist is applied on the first photoresist pattern 11. At this time, the second photoresist is applied not only on the first photoresist pattern 11 but also on the exposed portion 32a. Next, by exposing a part of the second photoresist, the unexposed part 13 of the second photoresist including the exposed part 32a and having a larger pattern shape including the exposed part 32a, The exposed portion 12 of the second photoresist, which is a portion, is formed. By doing so, the exposed portion 12 of the second photoresist is in a state of being soluble in the developing solution.

Next, as shown in FIG. 1D, the exposed first photoresist pattern 11 and the exposed portion 12 of the second photoresist are dissolved and removed using a developing solution. By doing so, an overhang-shaped lift-off photoresist pattern is formed by the unexposed portion 13 of the second photoresist.

Next, as shown in FIG. 1E, a lead electrode layer 33 is formed by sputtering Au or the like on the magnetoresistive film 32 on which the overhanging photoresist pattern for lift-off is formed. .

Next, as shown in FIG. 1 (f), the unexposed portion 13 of the second photoresist is removed together with an unnecessary electrode layer formed thereon, together with an organic solvent (eg, a solvent such as acetone) or the like. Remove with. At this time, if necessary, the unexposed portion 13 of the second photoresist may be dissolved and removed by applying ultrasonic waves or the like. Thus, the unexposed portion 13 of the second photoresist is removed, and lift-off is performed.

In this embodiment, the lead electrode layer 33 having a predetermined shape can be formed on the magnetoresistive film 32 by performing the above steps. As previously mentioned,
According to the present embodiment, when forming the lift-off photoresist pattern, there is no need to perform reverse taper processing,
Since the pattern size can be controlled with high precision by the first photoresist pattern 11, a photoresist pattern for lift-off can be formed with high precision.
Therefore, the lead electrode layer 33 formed by the lift-off photoresist pattern can also be formed with high precision.

(Second Embodiment) FIG. 2 is a sectional view showing a method of forming a lift-off photoresist pattern in a lead electrode forming step according to a second embodiment of the present invention. Hereinafter, a method for forming a lift-off photoresist pattern will be described with reference to FIGS. 2A to 2F.

First, the magnetoresistive film 32 shown in FIG. 2A is formed on a lower gap insulating layer (not shown, see FIG. 3). The magnetoresistive film 32 is formed by sputtering permalloy or the like.

Next, as shown in FIG. 2B, a first photoresist is applied on the magnetoresistive film 32.
Then, the first photoresist is exposed so as to have a predetermined pattern, and the exposed portion 21 of the first photoresist is exposed.
And an unexposed portion 22 of the first photoresist are formed.
By doing so, the exposed portion 2 of the first photoresist
1 is in a state of being soluble in the developer.

Next, as shown in FIG. 2C, a second photoresist is applied on the first photoresist. By exposing a part of the second photoresist, an unexposed portion 24 of the second photoresist having a larger pattern shape including the unexposed portion 22 of the first photoresist, The other portion, that is, the exposed portion 23 of the second photoresist is formed. By doing so, the exposed portion 23 of the second photoresist
Becomes soluble in the developing solution.

Next, as shown in FIG. 2D, the exposed portion 21 of the first photoresist and the exposed portion 23 of the second photoresist are dissolved and removed using a developing solution. In this manner, the unexposed portion 22 of the first photoresist and the unexposed portion 24 of the second photoresist form a lift-off photoresist pattern having an overhang shape.

Then, as shown in FIG. 2E, a lead electrode layer 33 is formed by sputtering Au or the like on the magnetoresistive film 32 on which the overhang-shaped photoresist pattern for lift-off is formed. .

Next, as shown in FIG. 2F, the unexposed portion 22 of the first photoresist and the unexposed portion 24 of the second photoresist are placed on the unexposed portion 24 of the second photoresist. Along with the unnecessary electrode layer formed as described above, it is removed using an organic solvent (for example, a solvent such as acetone). At this time, as in the first embodiment, an ultrasonic wave may be applied as necessary. Thus, the unexposed portions 22 of the first photoresist and the unexposed portions 24 of the second photoresist are removed, and lift-off is performed.

In this embodiment, as described above, since the unexposed portion 24 of the second photoresist is formed larger than the unexposed portion 22 of the first photoresist, the overhang-shaped lift-off photo is easily formed. A resist pattern can be formed. Therefore, in the present embodiment, similarly to the first embodiment, it is not necessary to perform a reverse taper process when forming the lift-off photoresist pattern, so that the lift-off photoresist pattern is formed with high precision. Becomes possible. Also, the lead electrode layer 33 having a predetermined shape formed by the lift-off photoresist pattern can be formed with high precision.

In each of the above embodiments, when forming a lift-off photoresist pattern on a magnetoresistive film in order to form a lead electrode constituting a magnetoresistive thin film magnetic head, a so-called magnetoresistive film is used. Although the case where the effect film is used as an electrode formation target surface has been described, the present invention is not limited to this. May be used.

[0031]

As described above, according to the present invention,
When forming the lead electrodes constituting the thin-film magnetic head,
A method of forming a photoresist pattern for lift-off that can easily perform highly accurate patterning can be obtained. Further, according to the present invention, it is also possible to prevent a film residue at a pattern edge after lift-off.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a method of forming a lift-off photoresist pattern in a lead electrode forming step according to a first embodiment of the present invention.

FIG. 2 is a sectional view showing a method for forming a lift-off photoresist pattern in a lead electrode forming step according to a second embodiment of the present invention;

FIG. 3 is a cross-sectional view of a magnetoresistive thin-film magnetic head having a lead electrode formed by using a lift-off photoresist pattern according to the present invention;

[Explanation of symbols]

 REFERENCE SIGNS LIST 11 first photoresist pattern 21 exposed portion of first photoresist 12, 23 exposed portion of second photoresist 13, 24 unexposed portion of second photoresist 22 unexposed portion of first photoresist 30 Lower shield layer 31 Lower gap layer 32 Magnetoresistive film 32a Exposed portion 33 Lead electrode layer 34 Upper gap layer 35 Upper shield layer

Claims (3)

[Claims] 1. A method for forming a lift-off photoresist pattern used when forming an electrode on a surface on which an electrode is to be formed, comprising: forming a first photoresist layer having a predetermined pattern on the surface on which the electrode is to be formed; Exposing a predetermined portion of the first photoresist layer, forming a second photoresist layer in a predetermined pattern on the first photoresist layer, and exposing the second photoresist layer Exposing a predetermined portion and having a step of removing the exposed portions of the first and second photoresist layers, forming an overhang-shaped photoresist pattern on the surface on which the electrode is to be formed. A method for forming a lift-off photoresist pattern, which is characterized by the following. 2. A step of forming a first photoresist layer so as to leave an exposed portion of a predetermined pattern on the surface on which the electrode is to be formed, exposing the first photoresist layer, and exposing the first photoresist layer to light. Forming a second photoresist layer over the photoresist layer and the exposed portion, and exposing the second photoresist layer to form an unexposed portion shaped to cover the exposed portion 2. The method for forming a lift-off photoresist pattern according to claim 1, further comprising: removing an exposed portion of the first and second photoresist layers. A step of forming a first photoresist layer on the surface on which the electrode is to be formed, and a step of exposing the first photoresist layer so as to form a first photoresist layer unexposed portion; Forming a second photoresist layer on the first photoresist layer, and forming a second photoresist layer unexposed portion shaped to cover the first photoresist layer unexposed portion. Forming a photoresist pattern for lift-off according to claim 1, comprising the steps of: exposing the second photoresist layer to light; and removing exposed portions of the first and second photoresist layers. Method.