JP2633088B2 - Manufacturing method of stamper - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a stamper. Particularly, it is used for manufacturing a plastic substrate for an optical disk.

[0002]

2. Description of the Related Art A method of manufacturing a conventional stamper used for injection molding of a substrate for a magneto-optical disk and a write-once optical disk is as follows.

First, as shown in FIGS. 2 (a) to 2 (c), a photoresist 2 is applied to a glass substrate 1, cut by a laser beam 7, and then developed to form a resist pattern 2a having a desired shape. To form

Next, as shown in FIGS. 2 (d) to 2 (e), a nickel conductive film 4 is formed on the surface on which the resist pattern 2a is formed by a method such as sputtering or vapor deposition, and an electroforming process is performed to perform nickel electroforming. The cast film 5 is formed with a desired thickness. Thereafter, the nickel conductive film 4 is peeled off from the glass substrate 1 and FIG.
A stamper 6 as shown in FIG.

In the above-described conventional method of manufacturing a stamper, the master master has the photoresist pattern as it is.

In order to form a fine pattern shape with high precision, it is necessary to apply a photoresist uniformly and with good reproducibility. For this purpose, application conditions (photoresist liquid temperature, viscosity, spinner rotation speed, etc.) Production conditions such as coating environment (environmental temperature, humidity, etc.), development conditions (developer temperature, drop volume, etc.) and process control must be thoroughly carried out.

When the master master and the conductive film are peeled off, the photoresist remains on the conductive film side, so a step of removing the remaining photoresist is required. For example, the photoresist is ashed by spraying oxygen plasma onto the photoresist. Removing dry ash method or removing method using photoresist stripping solution may not be enough to remove residual photoresist,
There was a risk that the quality of the stamper would be degraded.

In order to solve the above-mentioned problems,
As the master master, one obtained by directly forming a concavo-convex pattern on a glass substrate by sputter etching, ion etching, or plasma etching is used. FIG. 3 shows a general manufacturing method of this type of stamper. First, as shown in FIGS. 3A to 3C, a photoresist 2 is applied to a glass substrate 1, cut by a laser beam 7, and then developed to form a resist pattern 2a having a desired shape. Next, as shown in FIGS. 3D to 3E, the glass substrate 1 is etched into a predetermined pattern by means of sputter etching, ion etching, plasma etching or the like using the resist pattern 2a as a mask, and the photoresist is removed. Get master master. Further, as shown in FIGS. 3 (f) to 3 (g), a nickel conductive film 4 is formed on the glass substrate 1 which has been etched into a predetermined pattern by a method such as sputtering or vapor deposition, and is subjected to an electroforming process to perform electroforming of nickel. The film 5 is formed with a desired thickness. Thereafter, the nickel electroformed film 5 is peeled off from the glass substrate 1 and FIG.
The stamper 6 is as follows.

[0009]

As described above, in the case where a master material having a concavo-convex pattern directly formed on a glass material by sputter etching, ion etching, or plasma etching is used as the master master, a conductive film for electroforming is used. A nickel film is formed by means such as sputtering and vapor deposition. However, this nickel film has poor adhesion to quartz glass and soda glass, which are often used as glass substrates,
In particular, when quartz glass is used as a substrate, there is a problem that adhesion between the nickel film and the nickel film is very poor due to a large difference in linear expansion coefficient between the substrates and the nickel film peels off from the glass substrate during electroforming. The present invention has been made in order to solve the above problem, and provides a stamper manufacturing method capable of releasing a master from a master master without peeling off a conductive film from a glass substrate and producing a stamper with high accuracy. What you want to do.

[0010]

According to the present invention, a predetermined uneven pattern is formed by etching a flat quartz or glass substrate surface by photolithography.
A tantalum thin film and a nickel thin film are sequentially laminated along the surface of the uneven pattern to form a two-layer conductive film,
A master master having a concavo-convex pattern of a conductive film covered with a nickel passivation film is produced by performing a nickel passivation process, and a nickel electroformed layer is formed on this pattern surface until at least the concavo-convex pattern is embedded by electroforming. Is formed, and a nickel stamper having an uneven surface is produced by releasing the nickel electroformed layer from the master master, thereby providing a stamper manufacturing method.

In the present invention, a predetermined uneven pattern is formed on the surface of a flat quartz or glass substrate by etching using a photolithography method. The quartz or glass substrate is used to constitute a master master for manufacturing a stamper, and can be manufactured by performing a surface flattening process so that the surface roughness is usually 5 Å to 20 Å. . The concavo-convex pattern is a pattern in which the size of the concave portion is larger than the concavity and convexity of the surface of the stamper intended to be manufactured and is as large as the film thickness of a conductive film (a tantalum thin film and a nickel thin film (surface passivation)) to be described later. Can be used. The formation of the concavo-convex pattern is, for example, by coating a photoresist on the quartz or glass substrate to form a photoresist film, performing cutting by laser light and developing to form a photoresist pattern, and using this resist pattern as a mask, For example, sputter etching, ion etching,
The quartz or glass substrate can be etched by plasma etching or the like.

In the present invention, a nickel passivation film is formed by sequentially laminating a tantalum thin film and a nickel thin film along the surface of the concavo-convex pattern to form a two-layer conductive film, and performing a nickel passivation treatment. A master master having a concavo-convex pattern of a conductive film covered by the above is manufactured. The tantalum thin film constitutes a conductive film for electroforming and prevents peeling of a nickel thin film formed along the surface of the uneven pattern of the upper quartz or glass substrate, and is used for forming the nickel thin film. It is used by being formed along the surface of a concavo-convex pattern of a quartz or glass substrate beforehand. This formation is performed by, for example, a sputtering method, an evaporation method, or the like. This film thickness is usually 100 to 400 angstroms. The nickel thin film is used to form a conductive film for electroforming and to form a nickel passivation film. The nickel thin film is formed on the tantalum thin film along the surface of the concavo-convex pattern. This formation is performed by, for example, a sputtering method, an evaporation method, or the like. This film thickness is usually 200 to 500 angstroms. The nickel passivation film is for releasing the nickel electroformed film deposited thereon from the master master, and is made of quartz or glass in which a tantalum thin film and a nickel thin film are sequentially formed along an uneven pattern. The substrate can be formed and used by subjecting the substrate to a treatment such as a potassium dichromate aqueous solution immersion treatment and an oxygen plasma treatment. The aqueous solution of potassium bichromate can be immersed in, for example, a 5 wt% aqueous solution of potassium dichromate for one minute. The oxygen plasma treatment is performed, for example, at an oxygen gas pressure of 6 mmTorr.
r, the substrate can be processed at a power of 150 W for 3 minutes.

In the present invention, a nickel electroformed layer is formed on this surface by electroforming until at least an uneven pattern is buried, and the electroformed layer is released from the master master using the nickel to form the uneven surface. A nickel stamper is prepared. Also, the master master is
Since the nickel passivation film is easily damaged in the release process and the cleaning process after the release, the substrate is washed with a nitric acid aqueous solution or the like to dissolve and remove the nickel thin film having the nickel passivation film for each release. It is preferable that the nickel passivation film be renewed and used by forming a nickel thin film and passivating the nickel thin film. The concentration of the aqueous nitric acid solution is usually about 20% by weight.

[0014]

The tantalum thin film is interposed between the quartz or glass substrate and the nickel thin film and adheres well to both the substrate and the nickel thin film. The nickel passivation film reduces the adhesion with the nickel electroformed film, and facilitates the release of the nickel electroformed layer (stamper) from the master master.

[0015]

An embodiment of the present invention will be described with reference to the drawings.

Embodiment 1 First, as shown in FIGS. 1 (a) to 1 (c), a photoresist 2 is applied to a glass substrate 1, cut by a laser beam 7, developed, and developed to a desired shape. Is formed. Next, FIG.
As shown in (e), the glass substrate 1 is etched into a predetermined pattern by means of sputter etching using the resist pattern 2a as a mask, and thereafter the resist pattern 2a is removed.

Next, as shown in FIG. 1 (f), a tantalum thin film 3 is formed by means of sputtering. The thickness of the tantalum thin film is about 300 angstroms. Next, FIG.
As shown in (g), a nickel thin film 4 is formed by means of sputtering. The thickness of the nickel thin film forming the nickel thin film 4 is about 300 angstroms. Thereafter, the substrate is immersed in a 5% by weight aqueous solution of potassium dichromate for 1 minute to form a nickel passivation film on the surface of the nickel thin film, thereby producing a master master for stamper production.

Next, as shown in FIG. 1 (h), an electroforming process is performed on the master master to form a nickel electroformed layer 5 having a thickness of 0.3 m.
It is formed with a thickness of m. Thereafter, only the nickel electroformed layer is peeled off to obtain a stamper 6 as shown in FIG.

Embodiment 2 The case of reusing the master master used in Embodiment 1 will be described.

The nickel master passivation film, once used, may be damaged in a cleaning step or the like at the time of peeling off the electroformed film, so that the nickel passivation film and the nickel thin film are removed by washing with nitric acid. I do.

The concentration of nitric acid is 20% by weight. Thereafter, a nickel thin film and a nickel passivation film are formed in the same process as in the first embodiment, a master master is manufactured, and a stamper is manufactured.

The obtained stamper is of good quality without deterioration of the S / N ratio because the nickel passivation film of the master master on which the signal surface of the stamper is formed is updated each time it is used. It can be obtained repeatedly from one master master.

[0023]

According to the present invention, the nickel electroformed layer can be peeled from the master master without peeling the conductive film on the surface of the master master, and a high-quality stamper without deterioration of the S / N ratio can be obtained. A method of manufacturing a stamper that can be repeatedly obtained from one master master can be provided.

[Brief description of the drawings]

FIG. 1 is an explanatory view of a method of manufacturing a stamper manufactured in an embodiment of the present invention,

FIG. 2 is an explanatory view of a conventional stamper manufacturing method.

FIG. 3 is an explanatory view of a conventional stamper manufacturing method.

[Explanation of symbols]

 1 glass substrate, 2a uneven pattern, 3 tantalum thin film, 4 nickel thin film, 5 nickel electroformed layer, 6 stamper, 7 laser beam.

Claims (1)

(57) [Claims] 1. A flat quartz or glass substrate is etched by photolithography to form a predetermined concavo-convex pattern, and a tantalum thin film and a nickel thin film are sequentially laminated along the surface of the concavo-convex pattern. A master master having a concavo-convex pattern of a conductive film covered with a nickel passivation film is formed by forming a conductive film composed of layers and performing a nickel passivation process, and at least the concavo-convex pattern is formed on the pattern surface by electroforming. A method for producing a stamper, comprising: forming a nickel electroformed layer until a pattern is embedded; and releasing the nickel electroformed layer from a master master to produce a nickel stamper having an uneven surface.