JPH05337435A - Method for applying resist - Google Patents

Abstract

PURPOSE:To reduce the load of works for setting various kinds of conditions such as the revolution speed of a substrate and resist density when a resist of a specific film thickness is applied on a substrate by a spin coating method. CONSTITUTION:The load of works for resetting various kinds of conditions is reduced at the time of spin coating by bonding an auxiliary substrate 3 to the rear surface of the substrate to apparently increase the thickness of the substrate 1 when the resist is applied on a comparatively thin substrate 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for coating a resist (liquid) on a relatively thin substrate (glass plate).

[0002]

2. Description of the Related Art An optical disk capable of recording, reproducing or erasing is used as a high density memory for document files and data files. Optical discs require fine irregularities (for example, grooves for tracking). Therefore, in order to inexpensively manufacture a large number of optical disks,
It is preferable to use a plastic (synthetic resin) and transfer a fine concavo-convex pattern onto the plastic using a mold (die) called Ni stamper to prepare an optical disk substrate.

To manufacture this Ni stamper, a photosensitive resin (photoresist; hereinafter abbreviated as resist) is applied on a thick glass substrate (for example, about 5.85 mm), and a predetermined pattern (for example, concentric circles or After the spiral-shaped track pattern) is exposed to the laser beam, the laser irradiation portion (or the other portion) is removed due to a phenomenon to form a resist pattern on the glass substrate. A glass substrate having a resist pattern is called a glass master. Ni is dry-plated on the surface of the glass master on which the resist pattern is formed, and then wet plating is performed. After that, an adhesive is applied to the plated surface to adhere a glass plate, and then the glass plate is peeled off to manufacture a Ni stamper in which the pattern on the glass master is transferred to the Ni layer.

By the way, in another type of optical disk manufacturing process, a predetermined pattern (for example, a concentric or spiral track pattern) is directly formed on a thin glass substrate (about 1.2 mm). In this step, a resist pattern is formed on the substrate by applying a resist on the substrate, exposing a predetermined pattern to the resist, and causing a phenomenon. After that, etching is performed to form a groove having a predetermined pattern on the substrate,
Finally, the resist pattern is removed to obtain the target substrate.

In any case, it is necessary to apply a resist to the glass master or the glass substrate. A spin coating method is often used as a method for coating a resist on a substrate as described above. The reason why the spin coating method is used is that a resist layer having a smooth surface and a uniform film thickness can be efficiently formed. In this method, the coating operation is completed simply by dropping the resist on the substrate rotating at a high speed.

[0006]

When a resist having a predetermined film thickness is applied onto a substrate by the spin coating method, it is necessary to strictly set various conditions such as the rotation speed of the substrate and the resist concentration. These conditions differ depending on the thickness of the glass substrate, and after applying the resist to the thick glass substrate first, when trying to apply the resist to the next thin glass substrate, the conditions must be set again. .. However, resetting the conditions is a troublesome task.
In particular, changing the resist concentration is an extremely troublesome task. When applying to a thin substrate after applying to such a thick substrate, it is necessary to reset various conditions.

An object of the present invention is to solve such a problem.

[0008]

The inventor of the present invention can make constant various conditions at the time of spin coating if the thickness of the substrate is constant. Therefore, when applying a resist to a thin glass substrate, an auxiliary substrate is formed on the back surface of the substrate. It was found that if the glass substrate is adhered to increase the apparent thickness of the glass substrate, resetting of various conditions during spin coating can be reduced, and the present invention has been completed.

Therefore, according to the present invention, first, the first step of adhering the substrate to the auxiliary substrate with an adhesive, the substrate to which the auxiliary substrate is adhered is attached to a spin coater, and a resist is applied onto the substrate by spin coating. And a third step of peeling the substrate from the adhesive, to provide a resist coating method. Secondly, the present invention provides a coating method characterized in that the refractive index of the adhesive is equal to or substantially equal to the refractive indexes of the substrate and the auxiliary substrate.

[0010]

EXAMPLES Specific examples of the present invention will be described below with reference to FIG. (1) Glass auxiliary substrate 3 (305mmφ) with thickness (5.8mm)
Prepare and place it on a laminating rotary table, and apply UV curable adhesive 2 (maker name: Nippon Kayaku). The thickness of the adhesive layer is about 50 μm.

(2) Next, a transparent glass substrate 1 (305 mmφ) having a thickness of (1.2 mm) is placed on the auxiliary substrate 3 and the adhesive layer 2 is formed.
Sandwich. (3) In this state, ultraviolet rays are irradiated to cure the adhesive. (4) Place the integrated substrate 1 and auxiliary substrate 3 on the chuck table of the spin coater with the surface of the substrate facing up, vacuum chuck, and then rotate at 600 rpm to drop the resist solution from above. Apply. The thickness of the resist layer is about 1100Å.

(5) After coating, the substrate 1 and the auxiliary substrate 3 integrated with each other are removed from the spin coater and prebaked (humidity 100 ° C., time 30 minutes). (6) The substrate 1 is peeled off from the adhesive layer 2. Although the adhesive 2 has a refractive index nd = 1.5 here, it has the same refractive index as the substrate glass 1 and the glass auxiliary substrate 3. When measuring the film thickness of the resist layer with an ellipsometer, the laser light is radiated at an oblique incidence and the reflected light is used.
If it is as thin as mm, it cannot be measured. However, the adhesive 2 having the same or substantially the same refractive index as that of the substrate 1 and the auxiliary substrate 3 is used, and the auxiliary substrate 3 is adhered without peeling the substrate 1 from the adhesive layer 2 (that is, the above-mentioned (5) After the process), the measurement is possible.

[0013]

According to the present invention, when the resist layer is formed by the spin coating method, it is possible to reduce re-setting of various conditions during spin coating when switching from a thick glass substrate to a thin glass substrate.

[Brief description of drawings]

FIG. 1 is a schematic vertical cross-sectional view of a substrate and an auxiliary substrate which are bonded and integrated in an embodiment of the present invention.

[Explanation of symbols]

 1 substrate 2 adhesive 3 auxiliary substrate 4 vacuum chuck table

Claims (2)

[Claims] 1. A first substrate for adhering a substrate to an auxiliary substrate with an adhesive.
A step of attaching the substrate to which the auxiliary substrate is adhered to a spin coater, applying a resist on the substrate by a spin coating method, and a third step of peeling the substrate from the adhesive. How to apply resist. 2. The coating method according to claim 1, wherein a refractive index of the adhesive is equal to or substantially equal to a refractive index of the substrate and the auxiliary substrate.