Radiation imagery chemistry: process – composition – or product th – Imaging affecting physical property of radiation sensitive... – Making electrical device
Reexamination Certificate
1999-05-21
2001-02-13
Baxter, Janet (Department: 1752)
Radiation imagery chemistry: process, composition, or product th
Imaging affecting physical property of radiation sensitive...
Making electrical device
C430S394000, C430S396000, C430S313000, C430S319000, C430S320000, C430S325000
Reexamination Certificate
active
06187513
ABSTRACT:
RELATED APPLICATION DATA
The present application claims priority to Japanese Application No. P10-150359 filed May 29, 1998, which application is incorporated herein by reference to the extent permitted by law.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a process for forming a mask pattern and a process for producing a thin film magnetic head.
2. Description of the Related Art
Along with the development of a hard disk unit having a small size and a large capacity in recent years, a demand for a small-sized hard disk unit, such as a 2.5-inch type, is increased particularly in a field where an application to a portable personal computer is contemplated.
A magnetoresistance effect magnetic head (hereinafter referred to as an MR head), in which a change in resistance of a magnetic film having a magnetoresistance effect (hereinafter referred to as an MR film), the resistivity of which is changed depending on a magnetic field, is detected as a reproduced output voltage, receives attention as a magnetic head realizing a large capacity in a small-sized hard disk unit because it has such characteristics that a high reproduced output level can be obtained with a low media velocity.
The MR head is produced, for example, in such a manner that an MR film, an electrode film, an insulating film and the like are formed on a non-magnetic substrate by a thin film process, and these films are etched to a desired shape by a photolithography process.
For example, in the case where a magnetoresistance effect device (hereinafter referred to as an MR device) is produced, a thin film for an MR device comprising an MR thin film is formed on a surface on which the MR device is to be formed. A resist is then coated on the thin film for an MR device. Exposure to light and development are conducted for the resist to form a resist pattern having a desired shape. Specifically, the resist pattern has such a pattern in that the resist remains in a part to be the MR device. Etching is then conducted by using the resist pattern as a mask to remove the thin film for an MR device exposed from the mask. The etching is conducted, for example, by ion etching. Finally, the resist is removed to obtain a state in that the MR device is formed at the prescribed position.
When the MR film exposed from the mask is removed by etching using the resist pattern as the mask, a problem arises in that the thin film for an MR device removed by etching is re-attached to the side surface of the resist.
When the MR film removed by etching is re-attached to the resist, the attached MR film forms burr on the side surface of the MR film on removal of the resist. The formation of burr not only greatly lowers the sensitivity of the MR device but also becomes a reason of deterioration of a yield of the MR head.
The burr has been mechanically removed by scraping the surface of the MR device with a brush and washing with water. However, the surface of the MR device is damaged by this method. Furthermore, another problem arises in that the MR device is deteriorated by water used for washing.
In order to suppress the re-attachment of removed matters by etching and the formation of the burr due to the re-attached matters, improvement of a cross sectional shape of the mask patterns has been proposed, but a satisfactory effect has not been obtained.
SUMMARY OF THE INVENTION
The invention has been developed under the circumstances described above. An object of the invention is to provide a process for forming a mask pattern in that even when removed matters formed by etching are re-attached to a resist, burr is not formed on removing the resist, and a process for producing a thin film magnetic head using the same.
The invention relates to a process for forming a mask pattern comprising a first coating step of coating a first resist on a surface, on which the mask pattern is formed; a first exposure step of forming a pattern latent image in the first resist by exposing the first resist; a second coating step of coating a second resist on the first resist, in which the pattern latent image is formed in the first exposure step; a second exposure step of forming a pattern latent image in the second resist by exposing the second resist; a first development step of forming an upper layer mask pattern by developing the second resist, in which the latent image is formed in the second exposure step, with a first developer; and a second development step of forming a lower layer mask pattern by developing the first resist, in which the latent image is formed in the first exposure step, with a second developer, the upper layer mask pattern having a resist bridge part in a resist remaining part, in which the second resist remains, the bridge part bridging over a part of the lower mask pattern, in which the first resist is removed, and a space being present between the resist bridge part and the surface, on which the mask pattern is formed.
In the process for forming a mask pattern according to the invention, the second resist is coated on the first resist, in which the prescribed pattern latent image has been formed, and then the second resist is exposed to form the prescribed pattern latent image in the second resist. Thereafter, in the process for forming a mask pattern according to the invention, the upper layer mask pattern is formed by developing the second resist, and then the lower layer mask pattern is formed by developing the first resist. Therefore, the resist bridging part, which provides a space between the resist bridging part and the mask pattern forming surface, is easily formed in the upper layer mask pattern.
The invention further relates to a process for producing a thin film magnetic head comprising a thin film forming step of forming a thin film constituting the thin film magnetic head on a surface; a mask pattern forming step of forming a mask pattern on the thin film formed in the thin film forming step; and an etching step of shaping the thin film by removing the thin film that is exposed from the mask pattern formed in the mask pattern forming step by etching, the mask pattern forming step comprising a first coating step of coating a first resist on the thin film; a first exposure step of forming a pattern latent image in the first resist by exposing the first resist; a second coating step of coating a second resist on the first resist, in which the pattern latent image is formed in the first exposure step; a second exposure step of forming a pattern latent image in the second resist by exposing the second resist; a first development step of forming an upper layer mask pattern by developing the second resist, in which the latent image is formed in the second exposure step, with a first developer; and a second development step of forming a lower layer mask pattern by developing the first resist, in which the latent image is formed in the first exposure step, with a second developer, the upper layer mask pattern having a resist bridge part in a resist remaining part, in which the second resist remains, the bridge part bridging over a part of the lower mask pattern, in which the first resist is removed, and space being present between the resist bridge part and the surface, on which the mask pattern is formed.
In the process for producing a thin film magnetic head according to the invention, the mask pattern formed in the mask pattern forming step has a two-layer structure comprising the upper layer mask pattern and the lower layer mask pattern, and the upper layer mask pattern has a resist bridge part, which provides a space between the resist bridge part and the thin film. Therefore, in the etching step of the process for producing a thin film magnetic head, deterioration of the prescribed shape of the thin film due to the re-attachment of the thin film removed by etching to the mask pattern is prevented by etching using the mask.
REFERENCES:
patent: 4582778 (1986-04-01), Sullivan
patent: 4670297 (1987-06-01), Lee et al.
patent: 5656414 (1997-08-01), Chou et al.
patent: 5744284 (1998-04-01), L
Baxter Janet
Sonnenschein Nath & Rosenthal
Sony Corporation
Walke Amanda C.
LandOfFree
Process for forming mask pattern and process for producing... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Process for forming mask pattern and process for producing..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Process for forming mask pattern and process for producing... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2574997