JP2006252686A - Manufacturing method of glass original disk - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of a glass original disk in which the roughness of the side wall of a concave part is reduced. <P>SOLUTION: The method comprises of a process in which after a photoresist 2 is applied on a quartz glass substrate 1 and the photoresist 2 is exposed using a laser beam, development is performed and a photoresist pattern 4 is formed, a process in which the photoresist pattern 4 is irradiated with ultraviolet rays in an inert gas state in which oxygen does not exist, a process in which after the quartz substrate 1 irradiated with ultraviolet rays is placed on one side of a pair of electrodes arranged oppositely in a reactive ion etching apparatus and evacuated, and a process in which a fluorocarbon system gas and an Ar gas mixed at a prescribed rate are introduced, high frequency power is applied between the pair of electrodes, dry etching is performed making the photoresist pattern 4 as a mask in a state of prescribed gas pressure, a concave part 5 is formed on the surface of the quartz glass substrate 1. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method of manufacturing a glass master used for forming an optical disc such as a CD or a DVD.

In general, an optical disc capable of storing high-density data as audio, image applications, or a computer memory is manufactured using a glass master.
A method for manufacturing an optical disk using a conventional glass master is described in Patent Document 1.

That is, after applying a photoresist on a glass substrate, a laser beam is irradiated to form a latent image of the photoresist pattern, and the latent image of the photoresist pattern is developed using an alkaline developer. A recess is formed. Next, ultraviolet rays having a wavelength of 150 nm to 400 nm are irradiated from above the photoresist pattern in an oxygen or air atmosphere, and the upper ridge line portion adjacent to the concave portion of the photoresist pattern is curved. Next, anisotropic etching is performed by reactive ion etching using the photoresist pattern as a mask, so that the glass substrate surface has a predetermined depth. Next, the photo resist pattern is removed to produce a glass master having a recess on the surface. Next, after forming a nickel film on the glass master, nickel is plated by electroplating to produce a stamper. Next, this stamper is used as a mold, and the concave / convex pattern of the stamper is transferred onto a substrate on which an ultraviolet curable resin has been formed on the surface in advance to produce a disk substrate. Next, an optical disk is manufactured by forming a recording layer and a protective layer on the concave-convex pattern of the disk substrate.
JP 2003-281787 A

However, since the laser light has a high Gaussian distribution at the center and a low Gaussian distribution on the outside, the bottom of the recess in the glass master is flat, but the side wall of the recess is rough. It was happening.
In particular, in DWDD (Domain Wall Displacement Detection) that can increase the capacity of an optical disk, it is necessary to reduce the side wall roughness and suppress the groove noise so that the domain wall can move smoothly.

  Then, this invention is proposed in view of the above-mentioned subject, Comprising: It aims at providing the manufacturing method of the glass original disc which reduced the roughness on the side wall of a recessed part.

According to a first aspect of the present invention, there is provided a first step of applying a photoresist on a quartz glass substrate, exposing the photoresist using a laser beam, and then developing to form a photoresist pattern. A second step of irradiating the photoresist pattern with ultraviolet rays having a wavelength of 150 nm to 200 nm in an inert gas atmosphere without oxygen, and the quartz glass substrate irradiated with the ultraviolet rays is disposed oppositely in a reactive ion etching apparatus. A third step of evacuating after being placed on one of the pair of electrodes, and introducing a fluorocarbon-based gas and an Ar gas mixed in a predetermined ratio into the vacuum chamber, thereby providing a predetermined gas pressure. In this state, a predetermined high frequency power is applied to the pair of electrodes, and dry etching is performed using the photoresist pattern as a mask. Te, to provide a method of manufacturing a glass master, wherein a fourth step of forming a recess in the quartz glass substrate surface, in that it consists of.
In the second invention, the ratio of the Ar gas to the fluorocarbon-based gas is 5 to 80%, the predetermined gas pressure is 0.5 Pa to 5 Pa, and the DC component Vdc of the predetermined high-frequency power is 50 to 50%. The glass master disc manufacturing method according to claim 1, wherein the predetermined high frequency power is 500 to 200 W.

  According to the present invention, a first step of applying a photoresist on a quartz glass substrate, exposing the photoresist using laser light, and developing to form a photoresist pattern; and A second step of irradiating the resist pattern with ultraviolet rays having a wavelength of 150 nm to 200 nm in an inert gas atmosphere without oxygen, and a pair of quartz glass substrates irradiated with the ultraviolet rays facing each other in a reactive ion etching apparatus A third step of evacuating after placing on one of the electrodes, and introducing a fluorocarbon-based gas and an Ar gas mixed at a predetermined ratio into the vacuum chamber to obtain a predetermined gas pressure Then, a predetermined high frequency power is applied to the pair of electrodes, dry etching is performed using the photoresist pattern as a mask, and the quartz A fourth step of forming recesses in the glass substrate surface, since the glass master with a reduced roughness on the side wall of the recess is obtained.

Hereinafter, an embodiment of a method for producing a glass master according to the present invention will be described in detail with reference to FIGS. 1 to 4.
1A and 1B are cross-sectional views illustrating a method for producing a glass master according to an embodiment of the present invention, wherein FIG. 1A is a (latent image forming step), FIG. 1B is a (photoresist pattern forming step), and FIG. (UV irradiation process), (D) shows (etching process), and (E) shows (ashing process). FIG. 2 is an oblique sectional view of the SEM of the glass master in the embodiment of the present invention. FIG. 3 is an oblique sectional view of an SEM of a glass master in conventional etching. FIG. 4 is an oblique cross-sectional view of an SEM of a glass master that has been etched without mixing Ar gas with excimer light irradiation in the presence of oxygen and a fluorocarbon-based gas.

(Latent image forming process)
As shown in FIG. 1A, the quartz glass substrate 1 that has been optically polished is washed and dried, and then a photoresist 2 is applied, and then a laser beam is condensed by a lens to form a latent image 3. To do. The photoresist 2 is for G-line (absorption wavelength is 436 nm), and the wavelength of the laser beam is 405 nm.

(Photoresist pattern formation process)
Thereafter, as shown in FIG. 5B, exposure and development of the latent image 3 are performed to form a photoresist pattern 4 including uneven portions 4A and 4B. As described above, since the laser light has a high Gaussian distribution at the center and a low Gaussian distribution on the outside, the center of the recess 4A of the photoresist pattern 4 is etched as designed. The side wall 4a is rough and causes jaggedness (side wall roughness).

(UV irradiation process)
Next, as shown in FIG. 6C, the photoresist pattern 4 is irradiated with ultraviolet rays (excimer laser light) having a wavelength of 172 nm and an irradiation energy of 1620 mJ in an N ₂ atmosphere in which oxygen does not exist, The knurled side wall 4a is shrunk and smoothed.
The environmental temperature at this time is 25 ° C., for example. The wavelength of the ultraviolet light is 150 nm to 200 nm.

(Etching process)
Next, as shown in FIG. 4D, the quartz glass substrate 1 on which the photoresist pattern 4 is formed is introduced into a vacuum chamber (not shown), and a pair arranged in a reactive ion etching apparatus (not shown) facing each other. On one of the electrodes.
Thereafter, the vacuum chamber is evacuated to 2 × 10 ⁻⁶ Torr.
A mixed gas having a flow ratio of 1: 1 between fluorocarbon-based CHF ₃ gas and Ar gas is flowed into the vacuum chamber at 5 sccm. Next, when a frequency of 13.56 MHz and a high frequency power of 100 W are applied between the pair of electrodes (not shown) from a high frequency power source, Vdc between the pair of electrodes becomes 150 V and plasma is generated.

Using the photoresist pattern 4 as a mask, the inside of the vacuum chamber is set to 4 Pa, and highly anisotropic dry etching is performed to form the recess 5. At this time, the same effect can be obtained by adjusting the flow rate of the mixed gas so that the pressure in the vacuum chamber is changed from 0.5 Pa to 5 Pa and the flow rate ratio between CHF ₃ gas and Ar gas is changed in the range of 5 to 80%. Is obtained.

The reason why the mixed gas is flowed into the vacuum chamber to be in the range of 0.5 Pa to 5 Pa is that the side wall of the recess 5 is rough at 0.5 Pa or less, and the etching rate does not increase at 5 Pa or more, and etching is performed. It is because there is almost no. As the fluorocarbon-based gas, CF ₄ , C ₃ F ₈ and C ₄ F ₈ can be used in addition to CHF ₃ . Moreover, the same effect can be acquired even if Vdc is 50-500V.

(Ashing process)
Next, as shown in FIG. 5E, the flow of the mixed gas into the vacuum chamber is stopped, 14.7 Pa of oxygen is introduced into the vacuum chamber, high-frequency power of 100 W, and oxygen for 3 minutes. Ashing is performed to remove the photoresist pattern 4 to produce a glass master 6 having a recess 5.
A stamper and an optical disk using the glass master 6 can be manufactured by a known manufacturing method.

Here, samples 1 to 3 in which the presence / absence of ultraviolet irradiation in the (ultraviolet irradiation process) and the type of etching gas in the (etching process) were changed were prepared, and the side wall roughness was evaluated. The results are shown in FIGS.
Sample 1 is a glass master produced according to an embodiment of the present invention, Sample 2 is a glass master produced without UV irradiation and etching gas is CHF ₃ , Sample 3 is produced with UV irradiation and etching gas is oxygen. This is a glass master. The irradiation energy of ultraviolet rays used for these samples was 16200 mJ, and ashing was performed in an oxygen atmosphere gas of 14.7 Pa at a high frequency power of 100 W for 300 seconds.

  As shown in FIG. 2, it can be seen that the sample 1 according to the embodiment of the present invention has no side wall roughness of the recess 5. As shown in FIGS. 3 and 4, the samples 2 and 3 have no shrinkage effect due to ultraviolet irradiation, and thus the side walls of the recesses 5 are roughened. In contrast to FIG. 4, FIG. 2 shows that when Ar is mixed with a fluorocarbon-based gas, the photoresist pattern 4 is soft-etched and smoothed by Ar gas, and then the quartz glass substrate 1 is etched with the fluorocarbon-based gas. It can be seen that 4a is smooth.

  As described above, according to the embodiment of the present invention, after forming the photoresist pattern 4 on the quartz glass substrate 1, the photoresist pattern is irradiated with ultraviolet rays having a wavelength of 150 nm to 200 nm, and the quartz irradiated with the ultraviolet rays is irradiated. After placing the glass substrate 1 on one of a pair of electrodes opposed to each other in the reactive ion etching apparatus, vacuuming is performed, and Vdc is 50 to 500 V, 100 W to 200 W between the pair of electrodes. Is applied, and the ratio of Ar gas to fluorocarbon gas is 5 to 80%, and dry etching is performed under an atmosphere gas of 0.5 Pa to 5 Pa. can get. As a result, an optical disk manufactured using this glass master 6 can obtain a good tracking error and reduce groove noise.

It is sectional drawing which shows the manufacturing method of the glass original disk concerning embodiment of this invention, (A) is (latent image formation process), (B) is (photoresist pattern formation process), (C) is (ultraviolet irradiation) (Process), (D) shows (etching process), (E) shows (ashing process). It is a diagonal sectional view of SEM of the glass original disk in embodiment of this invention. It is SEM diagonal sectional drawing of the glass original disc in the conventional etching. FIG. 3 is an oblique cross-sectional view of an SEM of a glass master that is etched without mixing Ar gas with excimer light irradiation in the presence of oxygen and a fluorocarbon-based gas.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Quartz glass substrate, 2 ... Photoresist, 3 ... Latent image, 4 ... Photoresist pattern, 4A, 5 ... Concave, 4a ... Side wall, 4B ... Convex part, 6 ... Glass master

Claims (2)

A first step of applying a photoresist on a quartz glass substrate, exposing the photoresist using a laser beam, and developing to form a photoresist pattern;
A second step of irradiating the photoresist pattern with ultraviolet light having a wavelength of 150 nm to 200 nm in an inert gas atmosphere without oxygen;
A third step of evacuating after placing the quartz glass substrate irradiated with ultraviolet light on one of a pair of electrodes opposed to each other in a reactive ion etching apparatus;
A predetermined high frequency power is applied to the pair of electrodes in a state where a fluorocarbon-based gas and an Ar gas mixed at a predetermined ratio in the vacuum chamber are introduced and a predetermined gas pressure is applied, and the photoresist pattern is formed. As a mask, a fourth step of performing a dry etching to form a recess in the surface of the quartz glass substrate;
A method for producing a glass master, comprising: The ratio of the Ar gas to the fluorocarbon-based gas is 5 to 80%, the predetermined gas pressure is 0.5 Pa to 5 Pa, the direct current component Vdc of the predetermined high frequency power is 50 to 500 V, and the predetermined high frequency The method for producing a glass master according to claim 1, wherein the electric power is 100 to 200W.