JPH0453016B2 - - Google Patents

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a reproduction-only, additional recording, or rewritable optical information recording medium substrate (hereinafter referred to as (referred to as "medium substrate").

[Prior Art] FIG. 4 shows an example of this kind of media substrate commonly used. In the figure, a medium substrate 1 is made of glass and has a cylindrical center hole 1a in the center.
The recording layer is formed on the main surface 2, and the main surface 2 has concentric or guide grooves 3 ( (hereinafter referred to as "pregroup"), concentric small recesses 4 for indicating track numbers, sectors, sector numbers, etc.
(hereinafter referred to as "Prepit").
Note that the pre-group or pre-pit will be collectively referred to as an information groove hereinafter.

A medium substrate having such an information groove has conventionally been manufactured as follows. First, a pattern forming thin film deposited on the main surface of a glass substrate is subjected to photolithography and etching to form a mask serving as a reference plate having a pattern for forming information grooves. On the other hand, a resist film coated on the main surface of an original plate made of glass for a media substrate was exposed through the mask to transfer the pattern of the resist film, and after development, this pattern was formed. Information grooves are formed by etching the surface of the glass original plate using the resist film as a mask.

Next, after removing the above-mentioned resist film, the information grooves are visually observed one by one on the original plate with the information grooves formed using a reflective microscope, and the position is determined using this as a reference to determine the center position. However, a center hole 1a was provided and the outer shape was processed into a disk shape to manufacture a media substrate.

[Problem that the invention seeks to solve]

In the method described above, after forming the information groove, when processing it into a disk shape having a center hole in the center, the rotation center of the information groove pattern and the center of the center hole of the disk-shaped medium substrate are It is desirable to determine the positional relationship between the two as accurately as possible.

However, in the first place, the light reflectance of the original plate made of glass is 8%, taking into account the reflectance from the back side.
Furthermore, in such original plates, there is little difference in light reflectance between the information groove and other parts, so it requires great effort to accurately measure the position of the information groove. Therefore, it is difficult to accurately determine the position of the center hole of a plurality of original plates, and there is a problem that the position of the center hole varies among the original plates.

[Means for solving problems]

The present invention has been made in order to eliminate the above-mentioned problems, and its characteristics are that the main surface is a rectangular plate-like article, and the perpendicularity and flatness of two adjacent sides of the plate-like article are set as desired. A pattern for forming information grooves is formed in each of the resist films coated on the etching layer of two or more original plates for optical information recording medium substrates specified below a value of Developing the film, etching the layer to be etched to form information grooves, and then positioning the original plate near the center of the preliminary original plate using one of the original plates on which the information grooves were formed as a preliminary original plate. A center hole is formed by a hole forming device equipped with a holder for forming the center hole, and then the eccentricity between the information groove of the preliminary original plate and the center hole is determined and the hole forming device is corrected. This method of manufacturing a substrate for an optical information recording medium is characterized in that a center hole is formed in the original plate using the corrected hole forming device, and the original plate is processed into a disk shape.

Note that the rectangular shape of the main surface described above also includes a square shape. In addition, perpendicularity refers to the amount of deviation of the other plane part from a geometrical plane perpendicular to this reference plane, with one of them as a reference in a combination of two plane parts. Well, flatness refers to the amount of deviation of a flat part from the geometric plane.

[Effect]

According to the present invention, when a center hole is provided in a plurality of original plates in which information grooves are formed, the perpendicularity and flatness of two adjacent sides of the original plates are respectively defined to be below desired values, and A center hole was formed on one of the original sheets as a preliminary original sheet, and after determining the eccentricity between this center hole and the information groove of the preliminary original sheet, the center hole was formed on the remaining original sheets, so the center hole was The information groove can be formed accurately and the position of the information groove can be measured only after the center hole is formed in the preliminary original plate.

〔Example〕

An embodiment of the method for manufacturing a medium substrate of the present invention will be described in detail with reference to FIGS. 1 to 3. In addition,
FIG. 1 is a sectional view showing the process, FIG. 2 is a plan view showing a preliminary original plate with an information groove formed therein, which is brought into contact with a holder of a hole forming device, and FIG. 3 is a plan view of the preliminary original plate with a center hole formed therein. FIG. 3 is a plan view of the original plate.

First, the main surface is a 6 inch square, the thickness is 2.3 mm, the perpendicularity between a pair of two adjacent sides is 43 seconds, and the flatness of each of these two sides is
A chromium film with a thickness of 700 Å is laminated by a sputtering method on one main surface of a substrate 10 made of aluminosilicate glass with a thickness of 8.1 μm and 9.3 μm. next,
A positive photoresist (AZ-1350 manufactured by Hoechst) with a thickness of 1000 Å was spin-coated on this chromium film.
Next, the photoresist is exposed to light using an Ar laser to form a pattern with a width of 2 μm and a width of 1 μm on the chromium film by the method described later. Next, this photoresist is developed with an AZ developer to form a resist pattern. Using this resist pattern as a mask, the chromium film is etched using a mixture of ceric ammonium nitrate and perchloric acid. Then, the resist pattern is removed with sulfuric acid to produce a reference plate 13 having a chromium film pattern 12 with a recess 11 having a width of 1 μm (FIG. 1a).

Next, the main surface is a 6 inch square, the thickness is 1.2 mm, the perpendicularity between the two adjacent sides is 35 to 45 seconds, and the flatness of each of these two sides is in the range of 6 to 10 μm. Prepare 20 original substrates 14 made of soda lime glass. Next, a silicon oxide film 15 (layer to be etched) having a thickness of 1500 Å is laminated on one main surface of this substrate 14 by electron beam evaporation to produce a master plate 16 of a medium substrate. Next, on this silicon oxide film 15, a photoresist 17 (film thickness 6000 mm) similar to that described above is applied.
Å). Note that silicon oxide film 1
A thin film of hexamethyldisilazane (not shown) is interposed between the silicon oxide film 15 and the photoresist 17 to strengthen the adhesion between the silicon oxide film 15 and the photoresist 17. Next, the aforementioned reference plate 13 and original plate 16 are fixed to respective holders of the exposure apparatus. The two sides of the original plate holder that the two adjacent sides of the original plate 16 come into contact with have a perpendicularity of 36 seconds, and the flatness of the two sides of the holder are 7.3 μm and 9.3 μm, respectively. Next, the photoresist 17 on the original plate 16 is exposed to ultraviolet light 18 through the reference plate 13.
The chromium film pattern 12 of No. 3 is transferred (FIG. 3(b)).
This process is performed for each of the 20 original plates 16. Next, the photoresist 17 is developed with an AZ developer to form a resist pattern, the master plate 16 with the resist pattern is placed in a capacitive dry etching device, and CF ₄ gas is introduced into this device to oxidize silicon. The resist pattern was removed by dry etching the resist pattern 17 and ashing using O ₂ gas, and the width was 1 μm with an interval of 2 μm.
A patterned original plate 21 having a silicon oxide film pattern 20 with concentric information grooves 19 formed therein is manufactured (FIG. 3(c)). This process also requires 20 original plates 16
Do this for each.

Next, as shown in FIG.
Inner surfaces 22a, 22b of an L-shaped original plate positioning holder 22 provided on a moving stage 23 of a hole forming device to form a central hole of 1
Then, the two adjacent sides 21a and 21b of one of the 20 patterned original plates 21 (this is used as a preliminary original plate) are brought into contact with each other, and the vacuum suction hole 23a formed in the moving stage 23 is pressed. The preliminary original plate is adsorbed onto the moving stage 23 via 23d. Note that the inner surface 22a and the inner surface 22b of the holder 22
The perpendicularity is 42 seconds, and each inner surface 22
The flatness of a and 22b is 9.1 μm and 7.8 μm.
Further, the two side surfaces 21a and 21b of the patterned original plate 21 that come into contact with the inner surfaces 22a and 22b are surfaces having the above-described perpendicularity and flatness. Next, a core drill is used to form a center hole 24 with a diameter of 15 mm near the center of the vacuum-adsorbed preliminary original plate to produce a preliminary original plate 25 provided with the center hole 24 (the first
Figure d).

Next, as shown in FIG. 3, the distance between the center hole 24 of the preliminary original plate 25 and the innermost information groove 19 of this preliminary original plate 25 was measured using an optical microscope that can move the position in units of 1 μm. , the amount of eccentricity between the center hole 24 and the information groove 19 is determined. That is, the diameter X of the information groove 19 is measured, and X/2 is the diameter of the information groove 19.
Next, the distance _Y between the center hole 24 and the information groove 19 and the distance Z, which is the sum of this distance and the diameter of the center hole 24, are measured. And the center hole 24
Since the radius r ₂ of is (Z-Y)/2, the amount of eccentricity between the center O ₁ of the center hole 24 and the center O of the information groove 19 is determined by the deformation r ₁ , the distance Y, and the radius r ₂ . The difference is This amount of eccentricity can be determined by first finding the amount of eccentricity A in any one direction of the preliminary original plate 25, for example, the direction α shown in FIG. From the eccentricity A and B in the β direction, the eccentricity of the preliminary original plate 25 was determined from √ ² + ² .
As a result, the eccentricity of the preliminary original plate 25 provided with the center hole 24 was 1.7 mm, so in order to provide the center hole at the center position of the second and subsequent patterned original plates 21, the above-mentioned holder 22 is provided. The moving stage 23 was moved to correct its position with respect to the core drill, and patterned original plates 27 were produced in which 19 of the second and subsequent patterned original plates 21 were provided with a center hole 26 of 15 mm in diameter (Fig. 1). e). The amount of eccentricity of these 19 patterned original plates 27 could be suppressed to a range of 6 to 14 μm. Thereafter, a core rod was passed through the center hole 26, and the patterned original plate 27 provided with the 19 center holes 26 was formed into a disk shape with an outer diameter of 130 mm by rotary grinding, thereby producing a medium substrate.

The media substrate thus manufactured is then coated with a recording layer made of Te as a write-once recording material to a thickness of 300 Å on the main surface on which the information grooves have been formed, and a similar media substrate is then fabricated. Two recording layers are arranged concentrically facing each other, and a ring-shaped spacer made of nickel alloy with a thickness of 0.5 mm is interposed on the outer periphery and near the center hole, and an epoxy adhesive is applied between both substrates and the spacer. A sandwich-shaped optical information recording medium (optical memory disk) having a void inside was manufactured by sealing the same with the following materials.

As described above, according to this example, the perpendicularity and flatness of the two adjacent sides of the original plate of the media substrate are defined to desired values, and the hole forming device is corrected by the preliminary original plate, and the center of the original plate is Since the hole formation position is precisely defined, the eccentricity of the center hole with respect to the information groove can be suppressed to a small value, and the variation in eccentricity between multiple media substrates can also be suppressed. I can do it. As a result, an optical information recording medium having the medium substrate of this example can be rotated stably at high speed, and an optical information recording medium can be manufactured that has excellent followability of the optical head to the information groove during high speed rotation. Note that the reference plate of this example, the conventional original plate whose squareness and flatness are not specified (squareness of 37 to 93 seconds, flatness of 9 to 65 μm), and the media substrate manufactured using the manufacturing method 19 The eccentricity of the sheet is
It has become 50 to 750 μm.

The present invention is not limited to the above embodiments, and may be as shown below. That is, although the etched portions of the information grooves are used as information grooves, conversely, the unetched portions may be used as information grooves.
In addition, the perpendicularity and flatness of the holder of the hole forming device and the holder of the exposure device can be determined as appropriate without being limited to the above-mentioned embodiments, but it is preferable that the center hole be In order to provide this, the perpendicularity and flatness of the original plate should be less than that. Further, in the above embodiments, the pattern for forming the information grooves was formed by the contact exposure method, but the pattern is not limited to this, and may be formed by the proximity exposure method, the electron beam writing method, the direct writing method using laser light, etc. Good too. However, it is preferable to use a method of forming a pattern using a reference plate, such as a contact exposure method or a proximity exposure method, which takes a short pattern forming time. Furthermore, in the above embodiment, the center hole was formed after exposing all of the desired number of master plates coated with resist (19 plates in the above embodiment), but first, after correcting the hole forming device using a preliminary master plate, Exposure, development, and
A central hole may be provided by etching. Further, the original plate of the above embodiment is composed of a substrate for the original plate and a layer to be etched of a silicon oxide film, but other etching layers, such as group elements, groups, groups, compounds thereof, and It may also be an oxide, a nitride, or the like. Alternatively, the layer to be etched may be the surface layer of the original substrate, and the original substrate and the layer to be etched may be made of the same material. Further, the recording layer laminated on the medium substrate of the present invention is not limited to a write-once material such as Te, but may be a rewritable material such as GdFe. Further, as a medium substrate for a reproduction-only optical information recording medium, information for reproduction is recorded in a concave-convex shape on the layer to be etched according to the above embodiment, and
A reflective film made of aluminum or the like may be laminated on the layer to be etched. Further, in the above embodiment, the layer to be etched on the preliminary original plate and the layer to be etched on the original plate for accurately forming the center hole were made of the same film as the preliminary original plate, but the present invention is not limited to this. The layer to be etched in the preliminary original plate may be made of Al or Cr. Further, as a method for processing the original plate into a disk shape, a diamond cutting method, a laser processing method, or the like may be used.

〔Effect of the invention〕

As described above, according to the present invention, since the center hole can be accurately provided at the center of the pattern relative to the information groove of the medium substrate, the amount of eccentricity between the information groove and the center hole can be suppressed to a low level. moreover,
Since it is not necessary to determine the position of the center hole for each original plate, productivity of the medium substrate can be improved.

[Brief explanation of drawings]

Figures 1 to 3 are diagrams showing one embodiment of the present invention, with Figure 1 being a sectional view showing the process, and Figure 2 being an information groove in contact with a holder of a hole forming device. FIG. 3 is a plan view of the preliminary original plate with a center hole formed therein. Fourth
The figure is a perspective view showing a general media substrate provided with an information groove. 11... Concavity, 12... Chrome film pattern, 1
3... Reference plate, 14... Original plate substrate, 15... Silicon oxide film, 16... Original plate, 19... Information groove, 20... Silicon oxide film pattern, 21...
... Patterned original plate, 24... Center hole, 25... Patterned spare original plate provided with center hole, 26... Center hole, 27... Patterned original plate provided with center hole.

Claims (1)

[Scope of Claims] 1. Optical information on two or more plates, each of which has a rectangular main surface, and in which the perpendicularity and flatness of two adjacent sides of the plate are defined to be below desired values, respectively. A pattern for forming information grooves is formed in each resist film coated on the layer to be etched of the original plate of the recording medium substrate, the resist film is developed, and the layer to be etched is etched to form the information. Next, using one of the original plates on which the information grooves have been formed as a preliminary original plate, a center hole is formed near the center of the preliminary original plate using a hole forming device equipped with a holder for positioning the original plate. Then, the eccentricity between the information groove and the center hole of the preliminary original plate is determined and the hole forming device is corrected, and the corrected hole forming device is used for the second and subsequent original plates. 1. A method of manufacturing a substrate for an optical information recording medium, which comprises forming a center hole using a wafer and processing an original plate into a disk shape. 2. The method for manufacturing a substrate for an optical information recording medium according to claim 1, wherein the main surface of the original plate is square.