JPH05205321A - Manufacture of stamper - Google Patents

Abstract

PURPOSE:To prevent peeling defects by performing an electroforming working, after a Ni thin film having tensile internal stress is formed on a master disk. CONSTITUTION:After a photoresist mask 2a is applied on a flat glass substrate 1, for example a sputtering etching is carried out. The resist mask is burnt to ash by O2 plasma and the master disk 1a is made. By using Ar in a vacuumed room at 8X10<-3>Torr vacuum, a 200-350Angstrom Ni thin film 3 is sputtered by 1KW electric power and the >=7X10<-9> dyne/cm<2> Ni thin film in tensile internal stress is formed. Thereafter, using a specific electrolytic solution, a nearly 300mum electroformed Ni film in thickness is deposited and the Ni film 3 is stripped from the master disk 1a to prepare the stamper 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used for producing a plastic substrate having a sub-micron order pattern such as a tracking guide groove of an optical disk, a prepit indicating a sector address, a hologram diffraction grating pattern, etc. by an injection molding method or the like. The present invention relates to a method of manufacturing a stamper used.

[0002]

2. Description of the Related Art In a magneto-optical disk or a write-once optical disk, it is necessary to previously form on a disk substrate a prepit formed of fine irregularities indicating information such as a guide groove for tracking or a sector address. A method of manufacturing a stamper used when a substrate of such an optical disc is manufactured by injection molding will be briefly described.

First, as shown in FIG. 5 (a), a photoresist 2 is applied to a glass substrate 1, cut by a laser beam 6, and then developed to form an uneven pattern 2a having a desired shape (see FIG. 5 (b) and FIG. 5 (c)).
Next, as shown in FIG. 5D, a conductive film 3 of nickel, silver or the like is formed on the glass substrate 1 having the concavo-convex pattern 2a by a method such as sputtering or vapor deposition, and then electroforming is performed to form a metal, For example, an electroformed film 4 of nickel is formed to have a desired thickness (FIG. 5E). After that, the electroformed film 4 is peeled from the glass substrate 1 to form a stamper 5 as shown in FIG. In the stamper manufacturing method described above, the master master has the photoresist pattern 2a as it is. In the stamper production by such a method, in order to produce a fine pattern shape with high accuracy, it is necessary to apply the photoresist uniformly and with good reproducibility. Therefore, the application conditions (photoresist solution temperature, viscosity , Spinner speed, etc.), coating environment (environmental temperature, humidity, etc.), development conditions (developer temperature, drop volume, etc.)
Manufacturing conditions and process control must be thoroughly performed.

In addition, since the photoresist remains on the electroformed film side when it is peeled off from the electroformed film such as the master master, a step of removing the residual photoresist is required. For example, oxygen plasma is sprayed on the photoresist. In some cases, the residual ash resist may not be removed sufficiently by the dry ash method of removing by ashing and the removal method using the photoresist stripping solution, which may cause deterioration of the stamper quality.

Therefore, in order to solve the above-mentioned problems,
As a master disk, a method is used in which an uneven pattern is directly formed on a glass material by sputter etching, ion etching, or plasma etching. FIG. 6 shows a general manufacturing method of this type of stamper.

First, as shown in FIG. 6A, the glass substrate 1
Photoresist 2 is applied to the substrate, cut with laser light 6, and then developed to form a concavo-convex pattern 2a having a desired shape (FIGS. 6B and 6).
(C)).

Next, FIG. 6 (c) is etched by a method such as sputter etching, ion etching or plasma etching (FIG. 6 (d)), and after removing the photoresist, a master master 1a is obtained (FIG. 6 (e)). ). Further, a conductive film 3 of nickel or silver is formed on the master master 1a by a method such as sputtering or vapor deposition, and electroforming is performed to form an electroformed film 4 of metal, such as nickel, with a desired thickness (FIG. 6). (F) and (g)). Incidentally, as the conductive film 3, in addition to a single layer film of nickel or silver, it is also possible to use the method described in JP-A-2-7759.
The silver-nickel two-layer film and the nickel-silver-nickel three-layer film described in Japanese Patent No. 4 are conventionally used.

After that, the master master 1a and the electroformed film 4 are separated to form a stamper 5.

[0009]

As described above, when a glass substrate for a master master having a concave-convex pattern directly formed by sputter etching, ion etching, or plasma etching is used, a conductive film for electroforming is used. As a single layer film of nickel or silver, a two-layer film of silver-nickel, or a three-layer film of nickel-silver-nickel is formed by means of sputtering, vapor deposition or the like. However, quartz glass and soda glass, which are often used as glass substrates, do not have very strong adhesion to metal thin films, such as nickel and silver, which are conventionally used as conductive films for electroforming, and as shown in FIG. There was a defect that the conductive film 3 was separated from the glass substrate 1.

When quartz glass is used as the glass substrate, the surface properties are superior to those of soda glass, and when etching is performed by methods such as sputter etching, ion etching, and plasma etching, the etching rate is larger than that of soda glass. It is advantageous. Moreover, the surface quality of the etched surface after etching is also superior to that of soda glass. However, quartz glass has a linear expansion coefficient of 5 to 6 × 10 ⁻⁷ / ° C., which is 8% that of soda glass.
It is an order of magnitude smaller than 5 to 92 × 10 ^-7 / ° C, and the linear expansion coefficient of nickel is 197 × 10 ^-7 / ° C. The degree of expansion of the conductive film with respect to the glass substrate when heated is larger when quartz glass is used as the glass substrate than when soda glass is used as the glass substrate. Therefore, as shown in FIG. Peeling of the conductive film from the glass substrate caused by the internal stress of the compression of the initial electroformed film is more likely to occur with quartz glass than with soda glass, and good electroforming is performed. Was difficult.

The present invention has been made in consideration of the above circumstances. The internal stress of compression of the electroformed film at the initial stage of electroforming is canceled by the internal stress of tension of the conductive film, and the conductivity from the glass substrate is reduced. An object of the present invention is to provide a stamper manufacturing method capable of preventing peeling of a film and producing a high-quality stamper with high yield.

[0012]

In order to achieve the above object, the present invention provides a photoresist pattern on a surface of a substrate, exposing a predetermined portion of the photoresist and developing it to form a photoresist pattern, After etching the substrate using the photoresist pattern as a mask, the photoresist pattern is removed to create a master master from the substrate, and a conductive film made of a nickel thin film having an internal tensile stress is formed on the master master. After that, the stamper is manufactured by performing electroforming on the master master. Further, the conductive film made of the nickel thin film is characterized in that the tensile internal stress is 7 × 10 ⁻⁹ dyn / cm ² or more.

[0013]

When the direct cause of peeling of the conductive film 3 from the glass substrate 1 is investigated, the electroformed film deposited when a current having a low current density is applied at the beginning of electroforming causes internal stress of compression. As a result, it was found that the conductive film was peeled off from the glass substrate as a result.

FIG. 2 shows the relationship between the energization current density and the energization time during electroforming and the time when the conductive film peels off. FIG. 3 shows the relationship between the current density and the internal stress of the electroformed film. It shows the relationship. It can be seen from FIGS. 2 and 3 that the peeling of the conductive film occurs when the internal density of compression is generated in the electroformed film having a current density of 6 to 7 A / dm ² .

In FIG. 4, an argon gas was introduced into the vacuum chamber, the degree of vacuum was 8 × 10 ^-3 torr and the incident power was 1.
It shows the relationship between the film thickness and internal stress when a nickel thin film is formed by sputtering with KW, and the presence or absence of peeling defects during electroforming. From this figure, it is understood that when electroforming is performed using a nickel thin film having an internal tensile stress of 7 × 10 ⁹ dyn / cm ² or more as a conductive film, peeling of the conductive film during electroforming does not occur. The internal tensile stress can be set to a desired value by adjusting the gas pressure during film formation, the incident power, and the film thickness.

[0016]

Embodiments of the present invention will be described below with reference to the drawings, but the present invention is not limited to the following embodiments.

FIG. 1 is a manufacturing process diagram showing an embodiment of the present invention.

First, as shown in FIG. 1A, a photoresist 2, which is a photoconductor, is applied to a flat quartz glass substrate 1, and a laser beam 6 is applied to a predetermined position of the photoresist 2.
To irradiate and expose (FIG. 1 (b)). Then, the photoresist 2 is developed to form a fine pattern 2a (see FIG.
(C)) Using the photoresist pattern 2a as a mask, the quartz glass substrate is etched to a predetermined depth, for example, 800 Å (FIG. 1 (d)). Examples of the etching method include sputter etching and plasma etching.

When the etching is completed, the photoresist pattern used as the mask is removed by ashing by spraying oxygen plasma to produce a master master 1a (FIG. 1).
(E)).

Next, the conductive film 3 is formed on the surface of the master disk 1a by the sputtering method (FIG. 1 (f)).
Sputtering is performed in a vacuum chamber adjusted to a vacuum degree of 8 × 10 ⁻³ torr using argon gas with an incident power of 1 KW, and the thickness of the conductive film is 200 to 350 Å.

Thereafter, the electroformed film 4 is formed on the conductive film 3 by electroforming by the energizing method shown in FIG. 2 (FIG. 1).
(G)). In the electroforming process, nickel may be formed to a thickness of 300 μm using an electrolytic solution having the composition shown in Table 1, for example. Then, the conductive film is peeled off from the master master 1a (FIG. 1 (h)) to form a stamper 5.

[0022]

[Table 1]

[0023]

According to the present invention, a nickel thin film having an internal tensile stress of 7 × 10 ⁹ dyn / cm ² or more is electrically conductive on a glass substrate having a concavo-convex pattern formed by sputter etching, ion etching or plasma etching. Since it is formed as a film, and then an electroformed film is formed by electroforming to produce a stamper, as a result, peeling of the conductive film from the glass substrate at the initial stage of electroforming is eliminated, and a high-quality stamper with good yield It can be made.

[Brief description of drawings]

FIG. 1 is a diagram illustrating a stamper manufacturing method of the present invention.

FIG. 2 is a diagram showing a relationship between an energization current density and an energization time during electroforming.

FIG. 3 is a diagram showing a relationship between an energization current density and an electroformed film internal stress.

FIG. 4 is a diagram showing a relationship between a film thickness of a nickel thin film and internal stress.

FIG. 5 is a diagram illustrating a conventional stamper manufacturing method.

FIG. 6 is a diagram illustrating a conventional stamper manufacturing method.

FIG. 7 is a diagram showing a peeled state of a conductive film from a glass substrate.

[Explanation of symbols]

 1 Glass substrate 2 Photoresist 2a Concavo-convex pattern 3 Conductive film 4 Electroformed film 5 Stamper 6 Laser light

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kenji Ota 22-22 Nagaike-cho, Abeno-ku, Osaka, Osaka Prefecture

Claims (2)

[Claims] 1. A photoresist is applied on the surface of a substrate, a photoresist pattern is formed by exposing and developing a predetermined portion of the photoresist, and the photoresist is etched after the substrate is etched using the photoresist pattern as a mask. A pattern is removed to form a master master from the substrate, a conductive film made of a nickel thin film having a tensile internal stress is formed on the master master, and the master master is electroformed to form a stamper. A method for manufacturing a stamper, which comprises manufacturing the stamper. 2. The stamper manufacturing method according to claim 1, wherein the conductive film made of the nickel thin film has a tensile internal stress of 7 × 10 ⁹ dyn / cm ² or more.