JP3314832B2 - Pattern formation method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pattern forming method using ion milling.

[0002]

2. Description of the Related Art A pattern forming method using ion milling is used in a process for forming a magnetic transducer of a thin film magnetic head or a process for forming a semiconductor device. In this type of pattern forming method, a cover is attached to the surface of a film to be milled, and the film to be milled is ion-milled using the cover as a mask. The cover is often formed by patterning a positive or negative photoresist using a photolithography technique.

[0003]

In a cover by photolithography used in the prior art, the side wall surface rising from the surface of the film to be milled is a wall surface substantially perpendicular to the surface of the film to be milled.

For this reason, when the film to be milled is etched by using the ion milling method, the particles scattered by the etching are reattached to the cover, and grow so as to continue from the side wall surface to the surface of the film to be milled. There is. For this reason, when the cover is removed, there is a problem that the re-adhesion layer remains as minute projections on the surface of the film to be milled.

Conventionally, it has been attempted to avoid the formation of protrusions by changing the conditions for applying, exposing, or developing the resist for forming the cover. However, it is difficult to set conditions for obtaining good results.

An object of the present invention is to provide a pattern forming method in which a region covered by a cover is left, and a region outside the region is etched with high precision.

Another object of the present invention is to provide a pattern forming method capable of avoiding the formation of protrusions due to reattachment during etching.

Another object of the present invention is to provide a pattern forming method capable of easily and reliably avoiding the formation of protrusions.

[0009]

In order to solve the above-mentioned problems, in a pattern forming method according to the present invention, a cover is attached to a surface of a film to be milled, and the film to be milled is ion-milled using the cover as a mask. The method
The cover has an inversely tapered side wall surface in which a bottom surface in contact with the film to be milled is narrow and a surface on the opposite side is wide.

[0010]

A cover is attached to the surface of the film to be milled, and the film to be milled is ion-milled using the cover as a mask. Can be etched.

The cover has a reverse tapered side wall surface in which the bottom surface in contact with the film to be milled is narrow and the opposite surface surface is wide, so that even if particles etched by ion milling adhere to the side wall surface of the cover. Due to the inverted tapered shape, the growth does not continue from the side wall surface to the surface of the film to be milled. For this reason, projections (burrs) due to reattachment do not remain on the cover removal mark.

In addition, the formation of projections due to reattachment is prevented by selecting the cross-sectional shape of the cover, and it is not necessary to change the resist application conditions, exposure conditions, and development conditions for forming the cover. The process can be simplified.

The problem of over-etching can be avoided by including a step of applying an insulating film after ion milling and before removing the cover, and then removing the cover by a lift-off method.

[0014]

1 to 3 are views showing a pattern forming method according to the present invention. As shown in FIG. 1, a cover 2 is attached to the surface of the film 1 to be milled, and then, as shown in FIG.
The film to be milled 1 is ion-milled using the cover 2 as a mask. 3 is a support layer. Magnetoresistance effect (hereinafter MR
In the case of a thin film magnetic head using an element as a read element, the film to be milled 1 is an MR film and the support layer 3
Has a surface made of an insulating film. Support layer 3 in this case
Can be obtained by forming a lower shield film on a base constituting the majority of the slider and then attaching an insulating film thereon.

In the ion milling step, a region outside the film to be milled 1 covered with the cover 2 is etched with high precision.

The cover 2 has two side walls 23, 24 between a bottom surface 21 in contact with the film 1 to be milled and an opposite surface 22.
Are reverse tapered surfaces. A method of forming the cover 2 having such a cross-sectional shape is well known. For example, when the cover 2 is formed by a photolithography process, an ammonia inversion processing method, a chlorobenzene processing method, a heat inversion resist method, or the like is known as a cover forming means having an inverted tapered cross-sectional shape.

Here, the cover 2 is provided on both side walls 2 between a bottom surface 21 in contact with the film 1 to be milled and an opposite surface 22.
Since the particles 3 and 24 have reverse tapered surfaces, the scattered particles etched by the ion milling adhere to the side walls 23 and 24 of the cover 2 and even if the redeposition film 4 is formed, the side walls 23 and 24 are formed. Does not grow so as to be continuous from the side wall surfaces 23 and 24 to the surface of the film to be milled 1 because of the inverted tapered shape. Therefore, as shown in FIG. 3, when the cover 2 is removed, the re-adhesion film 4 is removed together with the cover 2, so that protrusions (burrs) due to the re-adhesion do not remain on the cover removal marks.

In addition, the formation of protrusions due to re-adhesion is prevented by selecting the cross-sectional shape of the cover 2, and there is almost no need to change the resist application conditions, exposure conditions, and development conditions for forming the cover. The process can be simplified.

In the etching step by ion milling, the film 1 to be milled may be excessively etched. The problem of such over-etching should be avoided by including a step of applying an insulating film on the surface of the cover and the film to be milled after ion milling, before removing the cover, and then removing the cover by a lift-off method. Can be. 4 to 6 show an example thereof. As shown in FIG. 4, the film to be milled 1 is ion-milled using the cover 2 as a mask. Next, as shown in FIG. 5, before removing the cover 2, insulating films 51 to 53 are applied to the surfaces of the cover 2 and the film 1 to be milled. Next, as shown in FIG. 6, the cover 2 and the insulating film 52 attached thereon are removed by a lift-off method. The insulating films 51 and 53 attached to the etching traces of the film to be milled 1 are not removed by the lift-off method but remain as they are. Therefore, insulation failure due to over-etching can be avoided. In addition, since the cover 2 has the side walls 23 and 24 of reverse taper, the lift-off method can be applied without fail.

The present invention can be widely applied to a pattern formation of a metal thin film in a process of forming a magnetic conversion element or a semiconductor element of a thin film magnetic head.

[0021]

As described above, according to the present invention, the following effects can be obtained. (A) It is possible to provide a pattern forming method of leaving a region covered by a cover and etching a region outside the region with high accuracy. (B) It is possible to provide a pattern forming method capable of avoiding the formation of protrusions due to reattachment during etching. (C) It is possible to provide a pattern forming method capable of easily and reliably avoiding the formation of protrusions.

[Brief description of the drawings]

FIG. 1 is a view showing one step included in a pattern forming method according to the present invention.

FIG. 2 is a view showing a step after the step shown in FIG. 1 in the pattern forming method according to the present invention.

FIG. 3 is a view showing a step after the step shown in FIG. 2 in the pattern forming method according to the present invention.

FIG. 4 is a view showing one step in another example of the pattern forming method according to the present invention.

FIG. 5 is a view showing a step subsequent to the step shown in FIG. 4 in the pattern forming method according to the present invention.

FIG. 6 is a view showing a step after the step shown in FIG. 5 in the pattern forming method according to the present invention.

[Explanation of symbols]

 Reference Signs List 1 film to be milled 2 cover 3 support layer 4 redeposition film

Continuation of front page (58) Field surveyed (Int.Cl. ⁷ , DB name) C23F 4/04 G11B 5/31

Claims (2)

(57) [Claims] 1. After attaching a cover to a surface of a film to be milled made of a metal thin film, ion milling the film to be milled around the cover using the cover as a mask. It has a reverse tapered side wall surface where the bottom surface side in contact with the film is narrow and the opposite surface side is wide, and after ion milling, before removing the cover,
An insulating film is applied to the bar and its surroundings, and then the cover is removed by a lift-off method.
Pattern forming method including a step . 2. After the cover is attached to the surface of the magnetoresistive film, the periphery of the magnetoresistive film is ion-milled using the cover as a mask, and the cover is in contact with the magnetoresistive film. The bottom surface side is narrow, and has a reverse tapered side wall surface in which the opposite surface side is wide, and after ion milling, before removing the cover, applying an insulating film to the cover and the periphery thereof, A pattern forming method including a step of removing the cover by a lift-off method.