JPH1011813A - Exposing method and exposing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an exposing method and an exposing device improving uniformity of pattern of a manufactured optical disk master disk without generating an error between desired exposing beam power and actual exposing beam power at the exposing time. SOLUTION: Driving voltage setting value and power efficiency are calculated in order to make the relationship between a driving voltage (b) and exposing beam power of an exposing beam (c) linear in the range of the desired exposing beam power. Based on this calculated driving voltage setting value, the driving voltage (b) is impressed on a power modulator 2, and based on the calculated power efficiency, the exposing beam power of the emitted exposing beam (c) from the power modulator 2 is adjusted by a beam power adjusting means 4, and the optical disk master disk, etc., are exposed by the adjusted exposing beam (e).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exposure method and an exposure apparatus, and more particularly, to an exposure method and an exposure apparatus for adjusting an exposure beam to a desired exposure beam power when exposing and manufacturing an optical disk master. About.

[0002]

2. Description of the Related Art Generally, an optical disk master is manufactured by exposing a photoresist applied on a glass substrate to an exposure beam. When the exposure is performed from the inner circumference to the outer circumference while rotating the substrate, the linear velocity is different between the inner circumference and the outer circumference of the substrate. Therefore, it is necessary to change the exposure beam power of the exposure beam.

For example, ISO (International Standard)
Organization) Standard format exposure pattern is
It is formed between an exposure radius of 30 mm to 60 mm. When the spindle on which the substrate is set is rotated so that the angular velocity becomes constant, the inner circumference of the master optical disc (with a radius of 3) is set.
Since the linear velocity of the outer periphery (radius 60 mm) is doubled with respect to the linear velocity of 0 mm), the exposure beam power must be doubled accordingly to equalize the exposure beam power per unit area at each radius. There is.

Therefore, in order to keep the exposure amount at each point on the substrate constant, several exposure methods and exposure apparatuses for controlling the exposure beam to a desired exposure beam power for exposure have been conventionally proposed.

For example, in Japanese Patent Application Laid-Open No. 60-182533, the relationship between the radius of an exposure area and the exposure power is regarded as linear, and the desired exposure power is a linear function of the exposure power at the center of the exposure area and the exposure radius. A method is disclosed in which power is controlled by setting as a driving voltage of a power modulator.

In Japanese Patent Application Laid-Open No. 2-156442, an exposure amount detecting section (optical sensor section) for detecting an exposure beam power on an optical system is provided. An exposure apparatus that controls a drive voltage of an optical modulator so that an amount detection signal coincides with the amount detection signal is disclosed.

[0007]

FIG. 3 is a graph showing a relationship between a driving voltage and an exposure beam power for explaining a conventional exposure method. In FIG. 3, the exposure beam power at the inner periphery (30 mm) is P ₀ , and the exposure beam power at the outer periphery (60 mm) is P ₁ (P ₁ = 2 × P ₀ ).

As a power modulator for applying a drive voltage and emitting an exposure beam, for example, an acousto-optic modulator using an acousto-optic effect (hereinafter referred to as A).
/ 0 modulator). Here, the acousto-optic effect is to generate ultrasonic waves by applying a drive voltage to an ultrasonic medium such as glass or crystal to form a phase-type diffraction grating and diffract an incident laser beam. The intensity of the diffracted light can be changed by changing the drive voltage. Then, for example, as an exposure beam, by using the first order diffracted light, the relationship between the driving voltage and the exposure beam power will include next L ₁ in FIG. 3, the non-linear region.

However, in the conventional exposure method, the driving voltage V
₀ in the range of ~V _1, the relationship between the drive voltage and the exposure beam power was being processed are regarded as linear as seen by a chain line L ₀ in Fig. As a result, except for the outermost peripheral portion and the innermost peripheral portion of the optical disk master, exposure is performed with power different from the desired exposure beam power.

In the exposure apparatus disclosed in Japanese Patent Application Laid-Open No. 2-156442, it takes a long time to set a drive voltage with respect to an exposure beam power in a non-linear region, and further, an exposure amount setting signal due to drift or noise of a laser beam. And the exposure amount detection signal are difficult to match and cannot converge.
Therefore, by providing an error range between the exposure setting signal and the exposure detection signal, the desired exposure power and ± ΔP
Was considered equal even if there was an error.

As described above, in the conventional exposure method and exposure apparatus, an error occurs between the desired exposure beam power and the exposure beam power at the time of actual exposure. In some cases, the height may be higher or lower than that, and the uniformity of the groove pattern of the manufactured optical disk master is deteriorated.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and there is no error between a desired exposure beam power and an exposure beam power at the time of actual exposure. An object of the present invention is to provide an exposure method and an exposure apparatus that can improve the uniformity of a groove pattern.

[0013]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, an exposure method according to the present invention is designed so that a relationship between a driving voltage and an exposure beam power becomes linear within a desired range of an exposure beam power. A voltage setting value and a power efficiency are set, a driving voltage is applied to the power modulator based on the set driving voltage setting value, and exposure of the exposure beam emitted from the power modulator is performed based on the set power efficiency. The beam power is adjusted.

An exposure apparatus according to the present invention comprises: a setting means for setting a drive voltage set value and a power efficiency such that a relationship between a drive voltage and an exposure beam power becomes linear within a desired range of an exposure beam power; A driving voltage applying unit that applies a driving voltage to the power modulator based on the driving voltage set value set by the setting unit; and an exposure of an exposure beam emitted from the power modulator based on the power efficiency set by the setting unit. And a beam power adjusting means for adjusting the beam power.

The beam power adjusting means is, for example, a variable deflection beam splitter.

The setting means measures in advance the driving voltage and power efficiency for the exposure beam power, and selects the desired driving voltage and power efficiency for the exposure beam power based on the measurement result. It is preferable to set.

In the present invention, first, a range of the driving voltage in which the change of the power modulator becomes linear is selected. Next, the power of the exposure beam output from the power modulator is adjusted so as to obtain the desired range of the exposure beam power within the range of the drive voltage, and the optical disk master is irradiated. In this way, no error occurs between the desired exposure beam power and the actual exposure beam power.

[0018]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of the present invention.

As shown in FIG. 1, the exposure apparatus of the present invention
A laser oscillator 1; a power modulator 2 for power modulating a laser beam a emitted from the laser oscillator 1; a driving voltage application unit 3 for applying a driving voltage b to the power modulator 2; Beam power adjusting means 4 for adjusting the exposure beam power of the emitted exposure beam c
And

The laser oscillator 1 emits an argon laser or the like often used for manufacturing an optical disk master.

The power modulator 2 is composed of, for example, an A / O modulator including an acousto-optic device utilizing Bragg diffraction and a driver for controlling the acousto-optic device.

The drive voltage application section 3 applies the set drive voltage b to the driver of the power modulator 2.

The beam power adjusting means 4 uses, for example, an optical component such as a variable deflection beam splitter and a lens whose surface is coated with a metal film to adjust the transmission power efficiency of the exposure beam c emitted from the power modulator 2. The adjusting means adjusts the power efficiency so that a desired exposure beam power range becomes linear.

The exposure apparatus according to the present invention also includes a head position detecting section 10 for detecting a distance between the center axis of rotation of the substrate 8 and the center axis of the head lens 7, and a head position detected by the head position detecting section 10. Setting means 13 for setting a drive voltage set value and power efficiency for outputting a desired exposure beam power from the beam power adjusting means 4 in response thereto;
Having.

FIG. 2 is a graph showing the relationship between the drive voltage and the exposure beam power obtained by the measurement. FIG.
L ₁ is a line indicating the exposure beam power with respect to the drive voltage before being adjusted by the beam power adjusting means 4,
L ₂ is a line showing an exposure beam power for driving voltage after adjusting the beam power adjustment means 4. P ₀ is a desired exposure beam power at the inner circumference (30 mm), and P ₁ is a desired exposure beam power at the outer circumference (60 mm).

As can be seen from FIG. 2, since L ₁ has a nonlinear region near the driving voltage V ₀ , a desired exposure beam power cannot be obtained as it is.

Therefore, first, a desired exposure beam power P
In the range of ₀ to P _1, such that the relationship of the drive voltage and the exposure beam power becomes linear, the drive voltage setting value V in the linear region
₀ ′ to V ₁ ′ and power efficiency (for example, 80%) are calculated. This calculation result is stored in the setting unit 13 in advance. Further, a control signal value for operating the beam power adjusting means 4 with this power efficiency is also stored in the setting means 13 in advance.

Next, the set drive voltage set value V _{0 is} set.
'~V ₁ 'based on, as well as applying a driving voltage b by the driving voltage applying unit 3 to the power modulator 2, the beam power adjusting unit 4, the driving voltage set value V _{0'~V 1'} exposure to the beam power P ₀ ′ to P ₁ ′ are attenuated by 20% to a desired exposure beam power P _{0 to} P ₁ . This can be a range P ₀ to P ₁ of desired exposure beam power and linear region.

The exposure beam e adjusted by the beam power adjusting unit 4 is supplied to the head position detecting unit 10 by the setting unit 13.
By setting a drive voltage having an exposure radius corresponding to the signal indicating the head position from the above, the desired exposure beam power P _{0 to} P ₁ corresponding to the head position is obtained, and after being reflected by the mirror 6, the head lens 7 is moved. Photoresist 8a formed on the surface of glass substrate 8 as a recording medium
Is condensed and irradiated. Thereby, the photoresist 8
is exposed to form a predetermined groove pattern. Thereafter, an optical disc master is manufactured through a developing process and a plating process.

According to the present invention, the power efficiency of the exposure beam is changed so that the relationship with the driving voltage within the range of the desired exposure beam power of the exposure beam does not include the non-linear region but becomes a linear region. An error does not occur between the exposure beam power and the exposure beam power at the time of actual exposure. Therefore, the uniformity of the groove pattern of the exposed optical disk master can be improved.

The present invention is not limited to the above embodiment, and various changes can be made within the technical scope described in the claims.

For example, in setting the driving voltage and the power efficiency, the driving voltage and the power efficiency for various exposure beam powers are measured in advance, and the results are tabulated for each desired exposure beam power. If the drive voltage setting value and the power efficiency are appropriately selected based on the table, the working efficiency can be further improved.

[0033]

According to the present invention, the driving voltage is set so that the relationship with the driving voltage in the range of the desired exposure beam power of the exposure beam does not include the non-linear region but becomes a linear region. Since the efficiency is changed, no error occurs between the desired exposure beam power and the actual exposure beam power. Therefore, the uniformity of the groove pattern of the exposed optical disk master can be improved.

[Brief description of the drawings]

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

FIG. 2 is a graph illustrating a relationship between a driving voltage and an exposure beam power for explaining an adjusting method of a beam power adjusting unit.

FIG. 3 is a graph showing a relationship between a driving voltage and an exposure beam power for explaining a conventional exposure method.

[Explanation of symbols]

 1: laser oscillator 2: power modulator 3: drive voltage application unit 4: beam power adjustment unit 6: mirror 7: head lens 8: glass substrate 8a: photoresist 10: head position detection unit 13: setting unit a: laser beam b: drive voltage c: exposure beam e: adjusted exposure beam

Claims (4)

[Claims] A drive voltage setting value and a power efficiency are set so that the relationship between the drive voltage and the exposure beam power becomes linear within a desired range of the exposure beam power. A driving voltage is applied to the power modulator, and an exposure beam power of an exposure beam emitted from the power modulator is adjusted based on the set power efficiency. 2. A setting means for setting a drive voltage set value and a power efficiency such that the relationship between the drive voltage and the exposure beam power is linear within a desired range of the exposure beam power. Driving voltage applying means for applying a driving voltage to the power modulator based on the driving voltage set value, and a power efficiency set by the setting means,
An exposure apparatus, comprising: a beam power adjusting unit configured to adjust an exposure beam power of an exposure beam emitted from the power modulator. 3. An exposure apparatus according to claim 2, wherein said beam power adjusting means has a variable deflection beam splitter. 4. The setting means preliminarily measures a driving voltage and a power efficiency with respect to an exposure beam power, and determines a driving voltage and a power efficiency with respect to a desired exposure beam power based on the measurement result. 4. The exposure apparatus according to claim 2, wherein the exposure apparatus is selected and set.