JPH01269255A - Manufacture of optical memory element - Google Patents

Abstract

PURPOSE:To satisfactorily read a tracking servo signal and a guide track (GT) address signal by controlling the widths of a GT and a GT address pattern on a photo-mask and controlling the depths of a GT part and a GT address part on a substrate after etching. CONSTITUTION:A positive type resist 16 is coated on a glass substrate 12. A photo-mask 17, for which a GT pattern 17a (width l1) as a transmitting part and a GT address pattern 17b (width l2) are formed, is adhered on the resist and a ultraviolet ray 18 irradiates. The l1 is smaller than the exposing wavelength 300-400nm of the ultraviolet ray and the l2 is set to be larger. Development is executed and channels for GT part and GT address part formation are formed as a resist pattern on the resist 16. Next, dry etching is executed and a GT part 12a and a GT address part 12b are formed on the substrate 12. After that, the resist 16 on the substrate 12 is removed. A depth d1 of the GT part 12a goes to lambda/8nG and a depth d2 of the GT address part 12b goes to lambda/4nG. The lambda is the wavelength of the ultraviolet ray 18 and the nG is the refraction factor of the glass substrate 12.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to the production of an optical memory device that performs one or more of the following operations: recording, reproducing, or erasing information using light such as a laser beam. It is about the method.

[Conventional technology]

In recent years, the need for optical memory devices such as optical disks and magneto-optical disks has been increasing as high-density, large-capacity memory devices. These optical memory devices can be classified into three types depending on their usage: read-only memory, additionally recordable memory, and rewritable memory.

Among them, optical memory devices used as additional recordable memory and rewritable memory usually include a guide track section to guide a light beam used for recording or reproducing information to a predetermined position of the optical memory device. , a guide track address section storing the address of each guide track.

By the way, as methods for recording information in optical memory elements, there are a land recording method in which information is recorded in a portion other than the guide track portion formed in a groove shape, and a group recording method in which information is recorded in the guide track portion. .

FIG. 6 is a schematic perspective view of an optical memory element employing the land recording method, and FIG. 7 is a schematic perspective view of an optical memory element employing the group recording method. In FIGS. 6 and 7, the optical memory element has guide track sections 1, 1, . . . and is divided into an information recording area 3 and a guide track address recording area 4. In the guide track address recording area 4, guide track address portions 2, 2, . . . are formed. In the optical memory device shown in FIG. 6, the recording area 3
Land 5 between adjacent guide track portions i1 within
In the optical memory device shown in FIG. 7, information is recorded in the guide track portions 1, 1, . . . .

Here, the depths of each guide track section 1 and each guide track address section 2 are usually λ/8n0 and λ/4, respectively.
n, is set. However, λ is the wavelength of light such as a laser beam used for reproducing information, etc., and the wavelength of the laser beam of a commonly used semiconductor laser is 780 nm or 830 nm.
It is. Further, nc is the refractive index of a glass substrate (not shown) in the optical memory element, and is usually in the range of 1.4 to 1.6. By setting the depth of each guide track section l and each guide track address section 2 as described above, the reproduction signal from each guide track address section 2 can be maximized, and the reproduction signal from each guide track section 1 can be maximized. Tracking servo output can be maximized.

[Problem to be solved by the invention]

However, in the above-mentioned optical memory device, since a resin material is used to form the guide track section 1 and the guide track address section 2, there is a drawback that oxygen or moisture can easily reach the recording medium, resulting in a decrease in reliability. Was.

Therefore, the applicant of the present invention previously proposed a method of forming a guide track section and a guide track address section directly on a glass substrate in Japanese Patent Application No. 58-84613 entitled "Method for Manufacturing Optical Memory Element."

However, according to the above manufacturing method, since the depths of the guide track section on the glass substrate and the guide track address section are always the same, it is necessary to maximize the tracking servo output and reproduce the reproduction signal from the guide track address section. A new problem has arisen in that it is not possible to simultaneously maximize the

[Means to solve the problem]

In order to solve the above problems, a method for manufacturing an optical memory element according to the present invention forms a resist on a glass substrate of an optical memory element, and then exposes the resist to light through a photomask having a guide track pattern and a guide track address pattern, and then develops the resist. A groove for forming a guide track portion and a groove for forming a guide track address portion are formed on the resist, and then the resist is removed by etching to form a guide track portion and a guide track address portion on the glass substrate. In the method for manufacturing an optical memory device, the depths of the guide track portion and the guide track address portion on the glass substrate after etching are controlled by controlling the widths of the guide track pattern and the guide track address pattern on the photomask, respectively. It is characterized by being individually controlled.

[For production]

In an optical memory element, as described above, it is generally necessary to make the depth of the guide track portion formed on the glass substrate smaller than the depth of the guide track address portion. Therefore, when the land recording method described above is adopted in an optical memory element, when manufacturing the optical memory element by the manufacturing method according to the present invention, for example, a positive resist, that is, an area irradiated with light, is removed by development. If a resist is used, the width of the guide track pattern on the photomask should be made smaller than the wavelength of the irradiation light to reduce the amount of light irradiated to the area on the resist where the groove for forming the guide track portion will be formed. As a result, the groove for forming the guide track portion on the resist after development is made relatively shallow. On the other hand, the width of the guide track address pattern on the photomask is made larger than the wavelength of the irradiation light to increase the amount of light irradiated to the area on the resist where the groove for forming the guide track address portion is formed. , The groove for forming the guide track address portion on the resist after development is made deeper than the groove for forming the guide track and ivy portion. As a result, the depth of the guide track portion formed on the glass substrate by etching becomes smaller than the depth of the guide track address portion.

Furthermore, when a group recording method is adopted in an optical memory element, for example, if the above-mentioned positive resist is used, the interval between adjacent guide track patterns can be increased by widening the width of the guide track patterns on the photomask. This allows light to interfere with the light passing through adjacent guide track patterns so that a certain amount of light is irradiated onto the area between the areas on the resist where the grooves for forming the guide track portion are formed, and then the development process is performed. The wall portions between adjacent guide track forming grooves on the subsequent resist are removed to some extent so that the guide track forming grooves on the resist become relatively shallow. On the other hand, by narrowing the width of the guide track address pattern on the photomask,
Increase the spacing between adjacent guide track address patterns.
This prevents light from being irradiated to the area between the regions where the grooves for forming guide track address portions on the resist are formed, and allows the grooves for forming guide track address portions on the resist to become deep after development. do. As a result, the guide track portion on the glass substrate after etching becomes shallower than the guide track address portion.

[Example 1] An example of the present invention will be described below based on FIGS. 1 and 2.

As shown in FIG. 2, the optical memory element 11 manufactured by the manufacturing method of this embodiment employs a land recording method and includes a glass substrate 12. A plurality of groove-shaped guide track portions 12a, 12a, . . . are formed on the glass substrate 12 at predetermined intervals.

The surface of the glass substrate 12 is divided into an information recording area 13 and a guide track address recording area 14, and a groove-shaped guide track is formed between adjacent guide track parts 12a in the guide track address recording area 14. Address portions 12b, 12b, . . . are formed. Further, adjacent guide track portions 12a/1 in the recording area 13
Information is recorded on the lands 15 between the two a. Note that the guide track address portions 12b and 12
A recording medium (not shown) is provided on the surface of the glass substrate 12, including the inside and the like.

Next, the manufacturing procedure of the optical memory element 11 will be explained with reference to FIGS. 1(a) to 1(e).

First, as shown in FIG. 1(a), a positive resist 16 is coated on a glass substrate 12, that is, a resist 16 of a type in which the area irradiated with light is removed by development.

Subsequently, as shown in FIG. 1(b), guide track patterns 17a and 17 as transparent parts are formed on the resist 16.
Cr, on which guide track address patterns 17b, 17b, .
A photomask 17 made of Ta or the like is brought into close contact with the resist 16 through the photomask 17, and ultraviolet rays 18, 18, . . . are applied to the resist 16.
irradiate.

Note that the width ll of each guide track pattern 17a in the photomask 17 corresponds to the exposure wavelength of ultraviolet rays 18 of 300 to 4
On the other hand, the width 12 of each guide track address pattern 17b is set to be larger than the exposure wavelength of the ultraviolet ray 18. As a result, each guide track pattern 17a on the resist 16 is irradiated with only a small amount of ultraviolet light 18, 18..., while the portion corresponding to each guide track address pattern 17b on the resist 16 is irradiated with ultraviolet rays 18, ...is sufficiently irradiated.

Next, as shown in FIG. 1C, development is performed to form grooves 16a, 16a, . . . for forming guide track portions as a resist pattern on the resist 16.
Grooves 16b, 16b, . . . for forming guide track address portions are formed as resist patterns. Here, since each guide track portion forming groove 16a was insufficiently exposed to the ultraviolet rays 18, 18, . . ., the resist 16 remained without being completely removed. On the other hand, since each guide track address forming groove 16b has been sufficiently exposed, the resist 16 is almost completely removed to the extent that the glass substrate 12 is exposed.

Subsequently, as shown in FIG. 1(d), CF, CHF3
Dry etching is performed in a gas such as
2, guide track portions 12a, 12a, . . . and guide track address portions 12b, 12b, . Here, each guide track address portion forming groove 16b on the resist 16 is deeper (formed) than each guide track portion forming groove 16a, so each guide track address portion 1
2b is formed deeper than each guide track portion 12a.

Subsequently, as shown in FIG. 1(e), the resist 16 remaining on the glass substrate 12 after dry etching is removed by sputtering in a solvent such as acetone or in 0□. The depth d of each guide track portion 12a is, for example, λ/8n0, and the depth d of each guide track portion 12a is, for example, λ/8n0.
The depth dt of 2b is, for example, λ/4n6. however,
λ is the wavelength of the ultraviolet light 18, and n is the refractive index of the glass substrate 12.

[Embodiment 2] Next, a second embodiment will be described with reference to FIGS. 3 to 5.

The optical memory device 21 of the second embodiment employs a group recording method, and has a glass substrate 21 as shown in FIG.
It is equipped with 2. This glass substrate 22 is divided into an information recording area 23 and a guide track address recording area 24. In the recording area 23, groove-shaped guide track portions 22a, 22a, . . . are formed in parallel, and information is recorded in each guide track portion 2a. Further, within the guide track address recording area 24, groove-shaped guide track address portions 22b, 22b, . . . are formed on the same line as the guide track portions 22a, 22a, .
is provided. Note that a recording medium (not shown) is formed on the surface of the glass substrate 22, including inside each guide track portion 2a and inside each guide track address portion 22b.

Below, Figures 3 (a) to (e) and Figures 4 (a) to (e)
The manufacturing procedure of the optical memory element 21 will be explained with reference to . However, FIGS. 3(a) to 3(e) are sectional views corresponding to the section AA in FIG. 5, and FIGS. 4(a) to 4(e) are sectional views corresponding to the section BB in FIG. 5, respectively. FIG.

First, as shown in FIGS. 3(a) and 4(a), a positive resist 25 is applied onto the glass substrate 22. As shown in FIG.

Subsequently, as shown in FIG. 3(b) and FIG. 4(b),
A photomask 26 on which guide track address patterns 26b, 26b, . . . as transparent portions and guide track patterns 26a, 26a, . Ultraviolet rays 18, 18... are applied to the resist 25 through the photomask 26
Perform exposure. Note that each guide track pattern 26a in the photomask 26 is formed to have a relatively wide width, so that adjacent guide track patterns 26a, 26a
The interval 13 between them corresponds to the exposure wavelength of ultraviolet rays 18 of 300 to 400n.
Set it small so that it is about the same as m or less,
When exposing the resist 25 through the photomask 26, the ultraviolet rays 18 passing through the adjacent guide track patterns 26a are arranged so as to cause interference with each other.

On the other hand, each guide track address pattern 26b in the photomask 26 is formed to have a relatively narrow width, so that the interval l between adjacent guide track address patterns 26b is equal to or slightly larger than the width of the guide track address pattern 26b. The ultraviolet rays 18 are set to be larger than that so that the ultraviolet rays 18 passing through adjacent guide track address patterns 26b do not interfere with each other during exposure of the ultraviolet rays 18.

Next, as shown in FIGS. 3(C) and 4(c), development is performed to form guide track address portion forming grooves 25b, 25b, . . . and guide track portion forming grooves 25a on the resist 25.・25a... is formed. Here, ultraviolet ray 1
8, the ultraviolet rays 18 pass through the adjacent guide track patterns 26a, 26a on the photomask 26.
Due to interference between the two, the portion between the adjacent guide track forming grooves 25a and 25a is exposed to ultraviolet rays.
As a result of being exposed to a certain amount of light, the portion between the adjacent guide track forming grooves 25a is removed to some extent during development, and the depth d of each guide track forming groove 25a is reduced.
, will be relatively small.

On the other hand, since the ultraviolet rays 18 passing through the adjacent guide track address patterns 26b and 26b on the photomask 26 do not interfere with each other during exposure of the ultraviolet rays 18, the adjacent guide track address forming grooves 2 on the resist 25
The portion between the grooves 5b and 25b is hardly exposed to the ultraviolet light 18, and therefore the portion between the adjacent guide track address forming grooves 25b and 25b is not removed during development. For this reason, each guide track address forming groove 25b
The depth d4 is greater than the depth d3 of each guide track portion forming groove 25a.

After development, dry etching is performed in a gas such as CF4 or CHF3 to obtain the results shown in FIGS. 3(d) and 4(d).
), guide track address portions 22b, 22b, . . . and guide track portions 22a are formed on the glass substrate 22.
・22a... is formed.

Here, since each guide track address portion forming groove 25b on the resist 25 was formed deeply, the depth of each guide track address portion 22b becomes sufficiently large. On the other hand, since each guide track portion forming groove 25a was formed shallowly, the depth of each guide track portion 22a becomes small.

Next, as shown in FIGS. 3(e) and 4(e), the resist 25 remaining on the glass substrate 22 after dry etching is removed by sputtering in a solvent such as acetone or in 02. Remove.

In each of the above embodiments, the positive photomask 17.
26 is used, however, a negative type photomask can also be used when manufacturing the optical memory elements 11 and 21. In that case, by appropriately adjusting the width of the light shielding area corresponding to the guide track section 12a and the guide track address section 12b in the photomask, the depth of the guide track section 12a and the guide track address section 12b can be adjusted by one round, respectively. It can be divided into sections.

〔Effect of the invention〕

As described above, the method for manufacturing an optical memory element according to the present invention includes forming a resist on a glass substrate of an optical memory element, then exposing the resist to light through a photomask having a guide track pattern and a guide track address pattern, and then developing the resist. A groove for forming a guide track portion and a groove for forming a guide track address portion are formed on the resist, and then the resist is removed by etching to form a guide track portion and a guide track/address portion on the glass substrate. In the method for manufacturing an optical memory device according to the present invention, by controlling the widths of the guide track pattern and the guide track address pattern on the photomask,
This configuration allows the depths of the guide track portion and the guide track address portion on the glass substrate after etching to be individually controlled.

As a result, in an optical memory device in which the guide track portion and the guide track address portion are directly formed on the glass substrate, the depths of the guide track portion and the guide track address portion can be adjusted individually. This has the effect that both the tracking servo signal and the guide track address signal can be read out satisfactorily.

Furthermore, by forming the guide track section and the guide track address section directly on the glass substrate, oxygen, moisture, etc. can be prevented from reaching the recording medium, and a highly reliable optical memory element can be manufactured. Play along.

[Brief explanation of the drawing]

1 and 2 show a first embodiment of the present invention, FIGS. 1(a) to 2(e) are schematic vertical cross-sectional views showing the manufacturing procedure of an optical memory element, and FIG. 2 is a glass The schematic perspective views of the substrate, FIGS. 3 to 5, show the second embodiment of the present invention, and FIGS. 3(a) to 3(e) show the guide track address portions at each manufacturing stage of the optical memory element. 4(a) to 4(e) are schematic longitudinal sectional views showing the guide track portion at each manufacturing stage of the optical memory element, FIG. 5 is a schematic perspective view of the glass substrate, and FIGS. FIG. 7 is a schematic perspective view showing each conventional example of a land recording type and a group recording type. 11 and 21 are optical memory elements, 12 and 22 are glass substrates,
12a and 22a are guide track parts, 12b and 22b are guide track address parts, 16 and 25 are resists, and 16a
・25a is a groove for forming a guide track portion, 16b・25b
17 is a guide track address forming groove, 17 and 26 are photomasks, 17a and 26a are guide track patterns, 17
b.26b is a guide track address pattern. /S/
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Claims (1)

[Claims] 1. A resist is formed on the glass substrate of the optical memory element, and then exposed through a photomask having a guide track pattern and a guide track address pattern, and then developed to form grooves for forming guide track portions and guide track addresses on the resist. In the method for manufacturing an optical memory element, the guide track pattern and the guide track address part on the photomask are formed on the glass substrate by forming a groove for forming the part, and then removing the resist by etching to form a guide track part and a guide track address part on the glass substrate. By controlling the width of each guide track address pattern,
1. A method of manufacturing an optical memory element, characterized in that the depths of a guide track section and a guide track address section on a glass substrate after etching are individually controlled.