Exposure mask and exposure method using the same

Details Exposure mask and exposure method using the same Exposure mask and exposure method using the same

2000-09-19

2003-10-28

Huff, Mark F. (Department: 1756)

Radiation imagery chemistry: process, composition, or product th

Registration or layout process other than color proofing

C430S005000, C430S319000, C430S320000

Reexamination Certificate

active

06638670

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an exposure mask which is used, for example, when an etching pattern of an air bearing surface (ABS) is exposed to the surface of a resist layer formed on the surface, that is opposed to a recording medium, of a substrate such as a slider bar, and more particularly, the invention relates to an exposure mask capable of securely aligning itself with the slider bar and to an exposure method using the exposure mask.
2. Description of the Related Art
A magnetic head device mounted on a hard disk drive or the like includes a slider provided on the tip of gimbals composed of a spring material, and on the edge of the slider, a thin film element for recording and reproducing is deposited.
The slider has a flying surface, i.e., a so-called “ABS”, which is opposed to the recording medium, and the slider flies above the recording medium by means of air that flows over the surface of the recording medium. While the slider is flying over the recording medium, recording or reproducing is performed on the recording medium by the thin film element provided on the slider.
In order to fabricate the slider, first, a circular ceramic material is formed, and a plurality of thin film elements are formed in parallel on the ceramic material by sputtering. The ceramic material is then sliced to produce a plurality of slender slider bars.
Next, a plurality of slider bars
20
are arrayed in parallel so that surfaces
21
that are opposed to a recording medium are aligned as shown in
FIG. 5
, and the slider bars
20
are retained by a jig or the like.
As shown in
FIG. 5
, a plurality of thin film elements
22
appear on the surface
21
of the slider bar
20
.
A photosensitive resist layer (not shown on the drawing) is formed on the surface
21
.
Next, a plurality of etching patterns of an ABS are exposed onto the surface of the resist layer by using an exposure mask.
FIGS. 6 and 7
show steps in an exposure method using a conventional exposure mask.
First, an exposure mask
23
shown in
FIG. 6
is aligned with a slider bar
20
that is disposed on the uppermost or lowermost side shown in FIG.
5
.
The exposure mask
23
has a plurality of light transmission sections
24
having the same shape as that of the ABS pattern, and a window
26
having alignment keys (marks)
25
and
25
is provided at least between two light transmission sections
24
and
24
.
The exposure mask
23
shown in
FIG. 6
is provided with, for example, three light transmission sections
24
and one window
26
.
As shown in
FIG. 6
, a region (diagonally shaded in the drawing) excluding the light transmission sections
24
and the window
26
is deposited with, for example, chromium (Cr) so as not to transmit light. The alignment keys
25
are also composed of a Cr film.
As shown in
FIG. 6
, the exposure mask
23
is moved up and down from side to side so that the thin film element
22
formed on the slider bar
20
is positioned in the center between the two alignment keys
25
and
25
formed in the window
26
of the exposure mask
23
.
After the thin film element
22
is positioned in the center between the alignment keys
25
and
25
, the exposure mask
23
is slid to the left by a predetermined distance as shown in FIG.
7
.
By sliding the exposure mask
23
to the left, the thin film element
22
is aligned at a predetermined position within the light transmission section
24
formed on the exposure mask
23
.
After the slider bar
20
and the light transmission sections
24
of the exposure mask
23
are aligned as described above, the photosensitive resist layer formed on the slider bar
20
is exposed through the light transmission sections
24
.
Furthermore, the exposure mask
23
is slid to the left and upward or downward in the drawing and on the unexposed surface
21
of the slider bar
20
, the thin film element
22
of the slider bar
20
and the light transmission section
24
of the exposure mask
23
are aligned as described with reference to
FIGS. 6 and 7
, and then, the photosensitive resist layer formed on the slider bar
20
is exposed.
In this way, a plurality of etching patterns of the ABS are exposed onto the resist layer formed on the surface
21
of all the slider bars
20
shown in FIG.
5
.
Since the photosensitive resist layer is of a negative type, the exposed resist layer remains on the surface
21
of the slider bar
20
in the development process and the unexposed resist layer is removed by a developer.
In
FIG. 7
, the resist layer on the slider bar
20
corresponding to the light transmission sections
24
is left in the same shape as that of the light transmission sections
24
by exposure and the resist layer other than the above is removed.
Although the resist layer on the slider bar
20
corresponding to the window
26
shown in
FIG. 7
is also left by exposure, since the slider bar
20
in this section is finally cut along lines A and B shown in FIG.
7
and removed, the shape of the window
26
will not remain on finished sliders.
After exposure and development, a dry etching step is carried out. Then, the slider bar
20
is cut along the lines A and B in
FIG. 7
to obtain a plurality of sliders.
The exposure mask
23
shown in
FIG. 6
, however, gives rise to the following problems.
The alignment keys
25
and
25
formed in the window
26
of the exposure mask
23
are provided only for aligning the light transmission section
24
of the exposure mask
23
and the thin film element
22
of the slider bar
20
, and therefore, the shape of the window
26
must not be left by the exposure and development process on finished sliders.
Consequently, as shown in
FIGS. 6 and 7
, the window
26
is formed between the light transmission sections
24
and
24
, and finally, a portion of the slider bar
20
corresponding to the window
26
is removed by being cut along the cutoff lines A and B (refer to FIG.
7
).
However a space between the cutoff lines A and B shown in
FIG. 7
is very small, and in particular, since sliders are miniaturized as the recording density increases, the space between the cutoff lines A and B is required to be narrowed as much as possible so that the portion of slider bar
20
to be removed is minimized.
Therefore, as the space between the cutoff lines A and B is narrowed, the size of the window
26
in the exposure mask
23
must be decreased. If the window
26
is made smaller, when the exposure mask
23
is slid up and down to align the exposure mask
23
with the slider bar
20
, the thin film element
22
fails to be fitted into the window
26
, resulting in decrease in alignment accuracy (alignment accuracy of the exposure mask).
Furthermore, when a plurality of slider bars
20
are arrayed in parallel as shown in
FIG. 5
, etching patterns of the ABS are formed on the slider bar
20
in the exposure step as shown in
FIGS. 6 and 7
, and then, the exposure mask is slid upward or downward in the drawing to perform the exposure step onto an unexposed slider bar
20
.
However, as shown in
FIG. 5
, there is a possibility that a thin film element
22
A on a slider bar
20
disposed uppermost and a thin film element
22
B on a slider bar
20
disposed under the above slider bar
20
are not properly arranged in the longitudinal direction in the drawing, and even if the exposure mask
23
is slid downward in the drawing with the thin film element
22
A being aligned with the alignment keys
25
and
25
in the window
26
of the exposure mask
23
shown in
FIG. 6
, the thin film element
22
B is not fitted into the window
26
of the exposure mask
23
.
Thus, if the thin film element
22
B does not appear in the window
26
, there is difficulty in determining the correct direction in which the exposure mask
23
is moved, and thus the alignment with the slider bar
20
cannot be performed properly, resulting in decrease in operating efficiency and alignment accuracy.
In order to increase the operating efficiency and the like by using the exposure mask
23
shown in
FIGS. 6

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