JPH071389B2 - Photomask manufacturing method - Google Patents

Description

TECHNICAL FIELD The present invention relates to a photomask, and more particularly to a method for manufacturing a photomask used in manufacturing a substrate for an optical memory device.

(Technical Background of the Invention and Problems Thereof) In recent years, the need for optical memory devices as high-density and large-capacity memory devices has increased year by year. This optical memory device can be classified into three types, a read-only memory, an additional recordable memory, and a rewritable memory, depending on the usage form.

Among them, an optical memory device used as an additional recordable memory and a rewritable memory usually uses a guide track and a track number thereof to guide a light beam for recording / reproducing / erasing information to a predetermined position of the optical memory device. And an address for identifying that. Further, when trying to manage information by dividing the same track into a plurality of sectors, a sector number and the like are often provided on the track.

One of the methods for manufacturing this guide track is the method disclosed in Japanese Patent Laid-Open No. 60-105751. The outline will be described with reference to FIG. As shown in FIG. 4 (a), a glass disk (3) is coated with a resist film (4) by a spinner or the like,
As shown in (b), a photomask (5) in which a guide track, a guide address, or a sector address is formed in advance is used, and light (7) such as ultraviolet rays is applied to the photomask to guide the guide track, the track address, or the sector address. Etc. ((6) in FIG. 2 (b), a thin film of Cr, Ta, etc., which does not transmit light, is formed, and this film is partially removed to form a desired pattern. ) Is transferred to the resist (4) and the resist is developed as shown in (c). (D) CF ₄ or CHF ₃
Do reactive ion etching in gas such as
Alternatively, by performing wet etching in HF solution, directly engrave guide tracks, track addresses, sector addresses, etc. on the glass disk (e), and finally remove the resist remaining in step (d) (ashing in O ₂ plasma. Alternatively, it may be washed with a solvent such as acetone).

In this method, the photomask used in the step (b) is manufactured by the method shown in FIG. That is, the film (9) which does not transmit light of the disk-shaped photomask substrate (8)
A spiral or concentric guide is applied on the resist by the light (12) such as Ar laser focused on the objective lens (11) while applying the resist (10) on the disk and rotating it around the central axis of the disk. Record the track.

FIG. 6 shows sectional structures of various photomasks conventionally used in the semiconductor industry. That is, FIG. 6 (a) is an example in which a Cr single layer film (9) is provided on the mask substrate 8, and (b) is Cr.
The double layer film of (9) and CrOx (13) has a structure in which the reflection of Cr is suppressed by CrOx. This is because when the master mask is made with a photorepeater and the reflectance is high, the resolution of the created pattern may drop, and to prevent it, when transferring the pattern to the resist film on the silicon wafer, Cr and the wafer This is an example in which a CrOx antireflection film is used to prevent the resolution of the pattern from being deteriorated due to multiple reflection in. (C) is an antistatic layer between Cr and the glass substrate
In this example, an InO ₃ film (14) is provided.

When recording a guide track, a track number, a sector number, etc. by using the mask shown in FIG. 6 by the method shown in FIG. 5, light such as Ar laser used for recording is absorbed in the Cr film, The temperature of the resist film rises (especially remarkable in the antireflection film as shown in FIG. 7B), the resist is destroyed, and the end face (15) of the resist recorded as shown in FIG. 7 becomes uneven.

FIG. 7 shows the guide track formed by the resist (10) remaining after laser recording and development. When Cr is etched using this resist as a mask and an optical memory element is manufactured in the process of FIG. Due to the scattering, a large noise is generated in the signal recorded in the optical memory element.

(Object) The present invention provides a photomask for an optical disk memory, which can prevent the temperature rise of the photoresist when the photomask is manufactured and can smooth the end faces of patterns such as guide tracks formed in the mask. The purpose is to

That is, the present invention does not transmit light near the wavelength of 400 nm, but 450
A method for manufacturing a photomask, characterized in that a pattern for an optical memory element is recorded on a mask substrate (1) provided with a dielectric multilayer film (2) which transmits light in the vicinity of nm by using an argon laser. To do.

(Example) Hereinafter, an example of a photomask for an optical memory device according to the present invention will be described in detail with reference to the drawings.

FIG. 1 is a partially enlarged view of a cross section of a photomask according to the present invention.

The mask substrate (1) used in the present invention is usually made of glass, acrylic resin, epoxy resin or the like.

As the dielectric, SiO ₂ , Ceo, TiO ₂ , Al ₂ O ₃ , MgF or the like is usually used. The dielectric multilayer film (2) is formed by sputtering, vacuum evaporation or the like. This film (2) has a wavelength of 400 nm
It does not transmit near light, but transmits light near 450 nm.
In particular, those having a transmission characteristic as shown in FIG. 2 are preferable.

The dielectric multilayer film (2) of the present invention is used when manufacturing a mask.
Laser light such as Ar laser (for example, 4579 shown in FIG. 2a)
It is characterized in that it has a spectral characteristic such that it transmits the wavelength of Å) and does not transmit the ultraviolet light used for pattern transfer (the light in the region indicated by b in FIG. 2). When a pattern is recorded on the photomask with a laser beam such as an Ar laser, light other than the light amount used for resist exposure (the amount absorbed by the resist) is transmitted through the mask substrate. As described above, the temperature rise of the resist film due to the laser light absorption in the Cr film does not occur.
Further, when the mask pattern is transferred to the optical memory element substrate using this mask, this film is sufficiently reflected with respect to the mask pattern transfer light (it is not always necessary to reflect the light,
Since it has the property of not transmitting ultraviolet light), it functions as a mask.

The wavelength characteristic of the transmittance shown in FIG. 2 is an extreme example, but it does not always adhere to the characteristic of FIG.
It does not need to be 100% transmissive and 100% reflective of ultraviolet light. If the light used for pattern transfer has the output characteristics as shown in FIG. 3, the g-line and h-line of this light are not transmitted and i
If a filter that transmits a lot of rays is installed in the middle of the ultraviolet light (7) in FIG. 4 and most of the light irradiating the mask is only i rays, the spectral characteristics of the dielectric film provided on the mask Means that ultraviolet rays may be slightly transmitted as shown by the line f in FIG.

The gist of the present invention is to form a mask with a dielectric multi-layered film that has the characteristics of preventing the temperature rise of the resist due to absorption of laser light during mask fabrication and sufficiently blocking the ultraviolet light during pattern transfer. is there.

(Effects) According to the present invention, a pattern such as a guide track having a smooth end face can be formed by light such as Ar laser light, and finally, an increase in noise due to the guide track of an optical memory element manufactured using the mask. Can be suppressed.

[Brief description of drawings]

FIG. 1 is an embodiment of the present invention, FIG. 2 is a spectral characteristic of transmittance of a mask according to the present invention, and FIG. 3 is a light output of a light source used when transferring a mask pattern to an optical memory device and a mask. The spectral characteristic in other Examples is shown. FIG. 4 is a manufacturing process of an optical memory device, FIG. 5 is a basic diagram when a pattern is recorded on the mask of the present invention, FIG. 6 is a conventional mask structure, and FIG. 7 is a conventional mask with guide tracks. The tracks produced when recorded and then developed are shown. The numbers in the figure are as follows: (1) ... mask substrate, (2) ... dielectric multilayer film,
(3) …… Glass disk, (4) …… Resist film,
(5) ... Photomask, (6) ... Light-impermeable film, (7) ... Light, (8) ... Photomask substrate,
(9) …… A film that does not transmit light, (10) …… A resist,
(11) …… Objective lens, (12) …… Light, (13) …… CrOx
Film, (14) …… InO ₃ film, (15) …… Resist end face

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hiroyuki Katayama 22-22 Nagaike-cho, Abeno-ku, Osaka-shi, Osaka Within Sharp Corporation (72) Akira Takahashi 22-22 22 Nagaike-cho, Abeno-ku, Osaka, Osaka Incorporated (56) Reference JP 59-3436 (JP, A) JP 60-194457 (JP, A) JP 49-15961 (JP, A)

Claims (1)

[Claims] 1. Light of wavelength near 400 nm is not transmitted, but 450 nm
A method of manufacturing a photomask, characterized in that a pattern for an optical memory element is recorded by using an argon laser on a mask substrate (1) provided with a dielectric multilayer film (2) which transmits light in the vicinity thereof.