JP2800091B2 - Terminal forming method for thin film magnetic head - Google Patents

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 conductor portion serving as a lead-out terminal on a thin-film magnetic head. More specifically, the present invention relates to a method for adding a surfactant to a developer.
Alternatively, by applying ultrasonic vibration during development,
The present invention relates to a method for forming terminals of a thin-film magnetic head for forming vertical terminals having a small pattern size with high yield.

[0002]

2. Description of the Related Art A thin-film magnetic head for a hard disk includes two upper and lower magnetic films 52 provided on a ceramic substrate 50 serving as a slider, as shown in FIG.
54 are separated by a gap film 56, and a coil film 58 for generating a magnetic field and for inducing an induced current is formed therebetween. In practice, an insulating film or the like is interposed between the layers, and the coil film is also formed in a plurality of layers, so that the entire head body portion has a thickness of about 20 to 40 μm. Finally, the head body is protected by covering it with an alumina protective film 60 having a thickness of about 10 to 20 μm.

It is necessary to form a lead extraction terminal at an end of the coil film for electrical connection with an external circuit. This terminal is connected at its lower part to the coil film on the ceramic substrate, and its upper part must be exposed on the alumina protective film. When the height of the alumina protective film is added to the height of the head body, the final product has a thickness of about 30 to 60 μm. Actually, since the alumina protective film is polished last, it is necessary to increase the terminal height by an amount corresponding to the height. Moreover,
The terminal pattern shape is becoming smaller and smaller as the thin film magnetic head is downsized, and it is necessary to form a high conductor portion with high precision in a narrow width pattern.

[0004] The lead extraction terminals are formed by photolithography. When the terminal pattern is large, the resist film thickness is increased to about 60 μm, and exposure and development are repeated several times (about four times) to form a deep recess in the resist film so as to penetrate the resist film. A terminal is formed by depositing a conductor portion by plating.

[0005]

Recently, with the miniaturization of thin-film magnetic heads, the terminal pattern size has become 50 × 100.
A size as small as μm is also required. However, if the pattern width of the terminal is reduced to less than 100 μm, the above-described method can develop the pattern up to a depth of about 30 μm,
If it exceeds 0 μm, development cannot be performed at all. In a region having a depth of 30 to 60 μm, there are some which can be developed and some which cannot, and even if it can be manufactured, the yield is extremely poor. In other words, there is no problem when the terminal pattern width is wide, but when the terminal pattern width is narrow, it becomes difficult to develop the resist to the deep portion, and as a result, a narrow and tall conductor cannot be formed.

Therefore, as shown in FIG. 5, a thin (approximately 5 .mu.m) resist 72 is applied on a substrate 70, a mask 74 having a terminal pattern is placed thereon, exposed, and developed to penetrate the resist film. After forming the recess 76,
A method has been devised in which the conductor portion 78 is formed to a desired height beyond the thickness of the resist by plating, and then the resist 72 is removed. The height (thickness) of the conductor portion 78 is 50
Since about 60 μm is required, as shown, the formed conductor portion 78 has a mushroom shape when the resist is removed.

However, in such a method, since the lead extraction terminals have a mushroom shape, the terminal dimensions vary greatly, and an abnormal portion occurs in the alumina protective film formed after removing the resist. That is, the terminal dimensions are larger than the terminal pattern formed on the exposure mask, and it is difficult to make the terminals smaller in a thinner magnetic head that is becoming increasingly finer. In addition, because of the swollen upper portion, it is difficult to form a protective film around a thin portion that becomes a shadow below the upper portion, and the mechanical strength of the terminal is reduced.

An object of the present invention is to remove a terminal pattern even if it is small, so that the resist can be completely removed to the depth of a thick resist so as to penetrate the resist. It is another object of the present invention to provide a method for forming a lead extraction terminal extending straight upward.

[0009]

According to the present invention, a resist having a substantially rectangular cross section is formed so as to penetrate the resist by applying a thick resist on a substrate and repeating photolithography a plurality of times. And a method of forming a conductor portion serving as a lead extraction terminal in the recess by plating. In the present invention, when the thickness of the resist to be applied is h and the width of the concave portion is a, h / a ≧ 0.6, a ≦ 90 μm, and when h> 30 μm, the depth is 30 μm from the upper surface of the resist. When developing a deeper portion, a developer to which a surfactant is added is used. Alternatively, an ordinary developer is used, and the developer is subjected to ultrasonic vibration. Of course, a method may be used in which both are combined and a developer to which a surfactant is added is used, and the developer is subjected to ultrasonic vibration.

Here, the thickness h of the resist is usually 50 μm.
m ≦ h ≦ 80 μm. In the present invention, h / a
The reason that ≧ 0.6, a ≦ 90 μm, and h> 30 μm is based on experimental results, and is to clarify the effective range of the present invention. That is, the resist film thickness h
However, when the pattern width a is 0.6 times or more the pattern width a, the pattern width a is 90 μm or less, and the resist film thickness exceeds 30 μm, a beautiful vertical terminal can be formed by the method of the present invention.

[0011]

As the pattern width of the lead-out terminal becomes narrower, the reason why the thick resist film cannot be developed to the bottom part is that the developing solution is formed on the resist due to the surface tension of the developing solution. Because it becomes difficult to enter. Specifically, when the terminal pattern width is less than 100 μm, if the resist depth exceeds 30 μm, it becomes difficult to enter the developing solution, and if it exceeds 60 μm, the developing solution does not enter at all. However, when a suitable amount of surfactant is mixed in the developer, the developer can easily enter even at a depth of more than 30 μm and can be developed to every corner. It can be formed to penetrate. Further, when ultrasonic vibration is applied to the developing solution in the developing step, the developing solution vibrates finely and enters into a narrow concave portion, so that the bottom portion can be completely developed.

[0012]

FIG. 1 is an explanatory view showing the steps of an embodiment of the method of the present invention, in which a developer containing a surfactant is used. First, a resist 12 having a thickness of 60 μm is formed on a substrate 10. For this purpose, resist application and
Repeat drying. Next, a mask 14 having a lead extraction terminal pattern is placed and exposed, and an alkali developing solution (KOH aqueous solution: pH 1) which is usually used for a positive resist is used.
3) to form a concave portion 16 in the terminal pattern portion. By repeating this operation twice, the depth 3
Develop to 0 μm (exposure / development and).

Further, a mask 14 having a pattern of a lead take-out portion is placed thereon and exposed, and a portion deeper than 30 μm from the upper surface of the resist is developed using an alkali developing solution containing a surfactant. Here, 5 to 10 ml of sodium n-dodecyl sulfate (10% by weight aqueous solution) as a surfactant was added to 18 liters of an alkali developing solution usually used for the positive resist, and the mixture was stirred well. I have. This exposure and development operation
By repeating the process a number of times, the bottom portion of the resist film is developed so as to penetrate the resist film to form a concave portion 16 having a substantially rectangular longitudinal section (exposure and development).

Next, a conductor 18 serving as a lead extraction terminal is formed in the recess 16 by copper plating to a thickness of about 50 μm (slightly thinner than the thickness of the resist film 60 μm), and then the resist is removed. I do. In the actual manufacturing process of the thin-film magnetic head, a process of forming an alumina protective film or the like on such a substrate and polishing the surface continues.

By this operation, the bottom of the resist film having a thickness of 60 μm is developed neatly, and a concave portion having a depth of approximately 60 μm having a substantially rectangular longitudinal section can be formed. It is possible to form a lead extraction terminal extending straight.

FIG. 2 is a process explanatory view showing another embodiment of the present invention, in which ultrasonic vibration is applied at the time of development.
A resist film 12 having a thickness of 60 μm is formed on a substrate 10. Then, in the same manner as in the above embodiment, this operation is repeated twice to develop to a depth of 30 μm.

Thereafter, a mask 14 having a pattern of a lead-out portion is placed and exposed, and a portion deeper than 30 μm from the upper surface of the resist is developed while applying ultrasonic vibration to the developing solution. Here, the measurement was performed using an apparatus as shown in FIG. Water 32 is put into the ultrasonic cleaning machine 30, and the developing container 34 is set therein. A developing solution 36 is put in the developing container 34. The substrate 38 is gripped with tweezers 40 and immersed in the developer 36, and is subjected to ultrasonic vibration to perform development.
The developer may be an alkali developer commonly used for positive resists. By repeating this exposure / development operation twice, it is possible to cleanly develop the resist film up to the bottom and to form the recess 18 having a substantially rectangular longitudinal section. Therefore, it is possible to form a lead extraction terminal that extends straight and perpendicular to the substrate surface without expanding in a mushroom shape.

Next, the results of attempts to form terminals under various terminal pattern conditions will be described. Resist thickness h is 60μ
m, and the dimensions of various elongated terminal patterns (width a
An experiment was conducted to determine whether the exposure and development operations can cleanly develop the bottom of the resist film with respect to the length b). As a developing solution, a KOH aqueous solution having a pH of about 13 was used. Table 1 shows the results. In the table, 〇 indicates a yield of 99% or more,
The crosses indicate a yield of less than 99%.

[0019]

[Table 1]

In the conventional method, when the width a is 90 μm or less (h / a ≧ 0.6), the yield is deteriorated. In particular, when the width is as large as 50 μm, development to the bottom of the resist film cannot be performed.
In contrast, both methods A and B of the present invention have a width of 50 μm.
However, it is possible to form a recess having a substantially vertical cross section and a beautiful vertical section up to the bottom of the resist film with a yield of 99% or more. Note that when the width a is 100 μm, the method is blank in the methods A and B of the present invention, but this can be performed by the conventional method, which indicates that it is not necessary to adopt the method of the present invention. .

In the above embodiment, in the case of the second embodiment in which ultrasonic vibration is applied, a normal developer is used.
As in the first embodiment, it goes without saying that a method may be used in which a developer containing a surfactant is used and ultrasonic vibration is applied thereto.

[0022]

As described above, the present invention is a method of mixing a surfactant into a developer or performing development while applying ultrasonic vibration, so that the resist film becomes thicker and the terminal pattern size becomes narrower. However, the developing solution can sufficiently spread to the deep portion of the resist concave portion and can be developed. Therefore, even if the terminal pattern is narrow, it is possible to form a terminal that is not mushroom-shaped but extends neatly in the vertical direction with good yield, and it is possible to further reduce the size of the thin-film magnetic head.

[Brief description of the drawings]

FIG. 1 is a process explanatory view showing one embodiment of a terminal forming method according to the present invention.

FIG. 2 is a process explanatory view showing another embodiment of the terminal forming method according to the present invention.

FIG. 3 is an explanatory diagram illustrating an example of a developing device used in the present invention.

FIG. 4 is an enlarged sectional view of a main part of the thin-film magnetic head.

FIG. 5 is a process explanatory view showing an example of a conventional method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Substrate 12 Resist film 14 Mask 16 Depression 18 Conductor

Continuation of the front page (56) References JP-A-5-12624 (JP, A) JP-A-3-154214 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) G11B 5 / 31

Claims (3)

(57) [Claims] 1. A resist is applied on a substrate, and a photolithography method is repeated a plurality of times to form a recess having a substantially rectangular cross section so as to penetrate the resist, and a lead is taken out of the recess by plating. In the method of forming a conductor portion serving as a terminal, when the thickness of a resist to be applied is h and the width of a concave portion is a, h / a ≧ 0.6 and a ≦ 9
A method for forming a terminal of a thin-film magnetic head, characterized in that a developing solution to which a surfactant is added is used when developing a portion deeper than 30 μm from the resist upper surface when h> 30 μm and h> 30 μm. . 2. A resist is applied on a substrate, and a photolithography method is repeated a plurality of times to form a recess having a substantially rectangular cross section so as to penetrate the resist, and a lead is taken out by plating in the recess. In the method of forming a conductor portion serving as a terminal, when the thickness of a resist to be applied is h and the width of a concave portion is a, h / a ≧ 0.6 and a ≦ 9
0 h and when h> 30 μm, when developing a portion deeper than 30 μm from the resist upper surface, the development is performed while applying ultrasonic vibration to the developing solution, wherein the terminal formation is performed. Method. 3. The resist has a thickness h of 50 μm ≦ h ≦ 8.
The method according to claim 1, wherein the thickness is 0 μm.