JPH09288850A - Exposing device and method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To use two kinds of laser beams having a large wavelength difference between them in response to an object in simple constitution. SOLUTION: Focusing information on an exposure surface, detected based on reflected light reflected by this exposure surface at the time of focusing the 2nd laser beam 12 that is larger than the 1st laser beam 11 in wavelength difference on the exposure surface is subjected to compensation processing of an error corresponding to aberration of an objective lens 17 based on a preset compensation value to become renewed focusing information, and based on this renewed focusing information, a position of an objective lens 17 is moved to be compensated. Consequently, even when an objective lens having no aberration is used only for the 1st laser beam 11, the same focusing can be performed as in the case of using an objective lens having no aberration both for the 1st and 2nd laser beams 11 and 12.

Description

Detailed Description of the Invention

[0001]

[Table of Contents] The present invention will be described in the following order. TECHNICAL FIELD OF THE INVENTION Conventional Technology (FIG. 3) Problem to be Solved by the Invention (FIG. 4) Means for Solving the Problem Embodiments of the Invention (FIGS. 1 and 2)

[0002]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exposure apparatus and an exposure method, and is suitable for application in, for example, a stamper manufacturing process (mastering process).

[0003]

2. Description of the Related Art Conventionally, for example, in a compact disk, a master stamper is manufactured by the following procedure shown in FIGS. That is, first, in FIG.
Photoresist is applied onto the extremely smooth one surface 1A of the substrate 1 made of glass or nickel as shown in FIG. As a result, the resist layer 2 is formed on the one surface 1A of the substrate 1.

Next, as shown in FIG. 3B, this substrate 1
The resist layer 2 is exposed to light in accordance with a desired recording signal, and then developed. Specifically, the resist layer 2 is irradiated with laser light to be exposed. The intensity of the laser light is modulated in accordance with the information signal to be recorded, so that the recording signal is latently imaged on the resist layer 2. By developing the resist layer 2 thus exposed, the one surface 1A of the substrate 1 as shown in FIG.
The resist layer 2 remains on the top except the exposed portion. Due to the remaining resist layer 2, an uneven pattern corresponding to a desired recording signal is formed on the substrate 1. A resist master 3 is formed by forming the concavo-convex pattern corresponding to a desired recording signal by the resist layer 2 on one surface 1A of the substrate 1.

Subsequently, as shown in FIG. 3D, a conductive layer 4 is formed on the uneven pattern of the resist master 3.
At this time, an electroless plating method or the like is used to form the conductive layer 4. Further, as shown in FIG. 3E, an electroformed layer 5 is formed on the conductive layer 4 thus formed. The electroplating method or the like is used to form the electroformed layer 5. Next in FIG.
As shown in (F), the conductive layer 4 and the electroformed layer 5 are integrally peeled from the substrate 1 and washed. After that, the master stamper 6 is obtained by forming an opening in the central portion.

[0006]

By the way, in the master stamper 6 manufactured by the above-mentioned procedure, the spot diameter of the laser beam applied to the resist layer 2 during the exposure process (FIG. 3B). The problem is how to reduce. Because the smaller the spot diameter, the substrate 1
This is because a large number of concavo-convex patterns corresponding to recording signals can be formed in a certain area of 1A on one surface, and thus a disk on which high density recording has been performed can be manufactured.

Here, the spot diameter of the laser applied to the resist layer 2 is W, the spot radius is W, the wavelength of the laser beam is λ,
When the numerical aperture of the objective lens provided for converging the laser light on the resist layer 2 of the substrate 1 is NA,

[Equation 1] Can be represented by Here, α is a constant, and is determined according to up to what% of the central intensity of the laser light is used. As shown in the equation (1), the spot radius W is the wavelength λ of the laser light and the numerical aperture NA of the objective lens.
Is determined according to. From this, it can be seen that it is effective to reduce the wavelength of the laser light or increase the numerical aperture of the objective lens in order to reduce the spot diameter. As a concrete example of realization, short wavelength UV (Ultra Vi
olet) An exposure apparatus and an exposure method for converging a laser beam with an objective lens having a high NA can be considered. In addition to this, it is conceivable to reduce the energy within a range that does not interfere with the signal for recording the laser light to be irradiated, but in this case the exposure time becomes long and so it is not suitable in the actual manufacturing process. Therefore, it is excluded here.

However, when the short wavelength UV laser light is used, a problem occurs when focusing the laser light on a desired position of the resist layer 2, that is, focusing. Generally, in an exposure apparatus, a He-Ne laser having a wavelength at which a photosensitive material coated on the resist layer 2 is not exposed is used for focusing. For example, in the case of an exposure apparatus using a laser beam having a long wavelength such as Kr or He-Cd, first, He-Ne is used.
The position of the substrate 1 is detected by irradiating the surface of the resist layer 2 with a laser and detecting the reflected light, and the position of the objective lens is adjusted based on the detection result to perform focusing. Exposure is actually performed by irradiating the resist layer 2 with a long-wavelength laser beam such as He or Cd. In this case, since the wavelength difference between the laser light for actual exposure and the laser light for focusing is small, it is relatively easy to manufacture an objective lens without aberration.

However, when the short wavelength UV laser light is used as the exposure laser light, the wavelength difference between the exposure UV laser light and the He-Ne laser light for focusing is large, so that the NA is high and both are high. There is a problem that it is difficult to manufacture an objective lens without aberration for both lasers. In order to avoid such a problem, an exposure apparatus that irradiates a laser beam having a single wavelength using only a UV laser is considered. In this case, since the laser light to be emitted is only the UV laser light, it is easy to manufacture an objective lens having a high NA and no aberration.

However, in such an exposure apparatus, since the UV laser light is also used for focusing, spot-like burning is caused at a portion for focusing such as a recording start position by the laser light. It will occur, and the commercial value of the disk will be significantly reduced. FIG. 4
Even when recording requires a blank portion such as a charactor or a bar code as shown in (4), there is a problem that the same burning occurs at the recording start position because it is necessary to focus each time the irradiation position of the laser light moves. is there.

The present invention has been made in consideration of the above points, and proposes an exposure apparatus and an exposure method which have a simple structure and can selectively use two kinds of laser light having a large wavelength difference according to the purpose. Is.

[0012]

In order to solve such a problem, according to the present invention, when focusing is performed on an exposed surface of an exposed object by a second laser beam having a large wavelength difference with respect to the first laser beam. , The focusing information of the exposed object detected based on the reflected light reflected by the exposed surface is subjected to a correction processing of an error according to the aberration of the objective lens based on a preset correction value, and a new focusing is performed. As information, the position of the objective lens is moved and corrected based on this new focusing information.

The position of the objective lens is moved and corrected based on the new focusing information obtained by correcting the focusing error of the second laser light caused by the aberration of the objective lens. Even when an objective lens having no aberration is used, focusing can be performed in the same manner as when an objective lens having no aberration is used for both the first and second laser beams.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to the drawings.

In FIG. 1, reference numeral 10 denotes an exposure apparatus used in the mastering process as a whole, which performs focusing of a laser beam on a substrate by using laser beams of different wavelengths having a large wavelength difference, a desired recording signal and a character. , A barcode or the like is exposed to form a latent image. The exposure apparatus 10 has a main laser light source 11 and a sub laser light source 12 as laser light sources. The main laser light source 11 is a short wavelength UV (Ul
tra Violet) A light source for emitting the laser light L1. Further, the sub laser light source 12 is a He-Ne laser light L2.
It consists of a light source for firing. Here sub laser light source 1
The He-Ne laser beam L2 emitted by 2 is a laser beam having a wavelength that does not sensitize the resist layer formed on the substrate, and is used for focusing of the recording laser beam irradiated on the substrate.

UV emitted from the main laser light source 11
A quarter-wave plate 13 and a half mirror 14 are arranged on the optical axis of the laser light L1, and UV is sequentially passed through them.
The laser light L1 is applied to the mirror 15. The UV laser light L1 applied to the mirror 15 is reflected according to the incident angle and is emitted toward the substrate 16. At this time, an objective lens 17 is provided on the optical axis between the mirror 15 and the substrate 16. The objective lens 17 is arranged so that the optical axis of the UV laser light L1 passes through the center thereof, and is designed to converge the UV laser light L1 to a predetermined spot diameter. Here, the objective lens 17 is formed so as to have no aberration in the wavelength region of the UV laser light L1.

The reflected light of the UV laser light L1 applied to the substrate 16 in this manner returns to the mirror 15 via the objective lens 17. The reflected light that has entered the mirror 15 is reflected in the direction of the main laser light source 11 and becomes return light that traces the optical axis in the opposite direction. Half mirror 1 placed on the optical axis here
The return light is reflected by 4 and enters the position sensor 19 via the mirror 18. Position sensor 1
Reference numeral 9 is, for example, a four-division detector, and UV is applied to the position of the substrate 16 depending on the angle and position of the incident return light.
It is adapted to detect whether or not the laser beam L1 is in focus. Note that the quarter-wave plate 13 shifts the optical axis of the return light so that the return light transmitted through the half mirror 14 does not interfere with the UV laser light L1 emitted from the main laser light source 11. Has been done.

Further, the He-Ne laser light L2 emitted from the sub-laser light source 12 is reflected by the mirror 15 and is applied to the substrate 16 via the objective lens 17. Board 16
The reflected light of the He—Ne laser light L2 that has been irradiated onto the mirror returns to the mirror 15 via the objective lens 17. The reflected light that has entered the mirror 15 is reflected in the direction of the sub-laser light source 12 and becomes return light that traces in the opposite direction on the optical axis.
It is incident on zero. The position sensor 20 is, for example, a two-divided detector, and the He-Ne laser light L with respect to the position of the substrate 16 is determined depending on the angle and position of the incident return light.
It is adapted to detect whether or not 2 is in focus.

The position sensors 19 and 20 supply the detection result to the focus control section 21. The focus control unit 21 moves the objective lens 17 along the optical axes of the UV laser light L1 and the He-Ne laser light L2 based on the position information of the substrate 16 obtained from the provided detection result, and thus the UV laser light L1. And focusing of the He—Ne laser beam L2 on the exposed surface of the substrate 16 (focusing). When the He-Ne laser beam L2 is used for focusing, the focus control unit 21 performs a predetermined correction process on the detection result obtained by the position sensor 20. This correction process is performed based on a value obtained in advance by experiments or the like, and an error due to the aberration of the objective lens 17 with respect to the He-Ne laser light L2 is corrected.

With the above arrangement, the exposure apparatus 10 performs focusing processing by the method described below. That is, the UV laser light L1 and the He—Ne laser light L2
Are radiated to the substrate 16 through the objective lens 17 respectively, and the voltage values of the position sensors 19 and 20 in a focused state are obtained in advance by experiments or the like, and these values are set in the focusing control section 21. deep. The focusing control unit 21 having such a set value controls the focusing processing when the UV laser light L1 and the He—Ne laser light L2 are used.

As shown in FIG. 2, the focusing control procedure starts at step SP1 and then proceeds to step SP1.
In step 2, it is determined whether the focusing processing is performed by the UV laser light L1 or the He—Ne laser light L2. If the focusing processing is performed with the UV laser light L1, the process proceeds to step SP3, where the He--Ne laser light L
If the focusing process is performed in step 2, step SP
Jump to 4.

When the desired recording signal is exposed on the resist layer of the substrate 16, UV is used for exposure recording and focusing.
Laser light L1 is used. Normally, in the case of a recording signal, the exposure process is continuously performed, and the burning due to the laser beam during the focusing process is not a serious problem. Therefore, the UV laser beam L1 is used not only during recording but also during focusing. ing. In this case, the process proceeds to step SP3. In step SP3, focusing is performed by controlling the movement of the objective lens 17 so that the voltage value detected by the position sensor 19 matches the value obtained in the above-described experiment or the like. After the focusing is performed in this way, the procedure is completed in step SP6, and the actual exposure recording is started.

Further, in step SP4, processing for focusing processing with the He-Ne laser light L2 is performed.
In the exposure processing in the case where there are many blank portions such as characters and barcodes, the focusing processing is performed each time the recording position moves after the exposure is stopped at the blank portion. For this reason, in the focusing using the UV laser light L1, burning occurs each time. Therefore, after performing the focusing processing with the He—Ne laser light L2, the UV laser light L
At 1, actual exposure recording is performed. Accordingly, focusing is performed by first controlling the movement of the objective lens 17 so that the voltage value detected by the position sensor 20 matches the value obtained in the above-described experiment or the like. After the focusing control by the He-Ne laser light L2 is performed in this way, the UV laser light L1 and the He laser light are controlled by the step SP5.
An error caused by the aberration of the objective lens 17 with the -Ne laser beam L2 is corrected.

That is, the objective lens 17 uses the UV laser light L
Since it is manufactured in correspondence with only No. 1, there is an error due to the aberration between the focusing position by the UV laser light L1 and the focusing position by the He—Ne laser light L2, and it is necessary to correct this error. is there. In step SP5, the moving amount of the objective lens 17 to be corrected is obtained from the voltage value at the time of focusing obtained in the above experiment. Therefore, the bias value between the voltage value during focusing by the He-Ne laser beam L2 and the voltage value during focusing by the UV laser beam L1 is determined in step SP4.
The focusing value is applied to the voltage value obtained by the position sensor 20 to perform focusing control.
Thereby, the focusing position by the UV laser light L1 can be obtained by the focusing by the He-Ne laser light L2. After the focusing control is completed in this way, the procedure is ended in step SP6, and the exposure recording by the UV laser light L1 is started.

According to the above configuration, the voltage value obtained by the position sensor 20 can be experimentally determined in advance during focusing of the substrate 16 by the He-Ne laser light L2 having a large wavelength difference with respect to the UV laser light L1. A bias value for correcting the aberration of the obtained objective lens 17 is applied, and the focusing of the objective lens 17 is controlled by controlling the movement of the objective lens 17 based on this value. Even in the case of using the objective lens 17 having no aberration, the focusing processing can be performed in the same manner as in the case of using the objective lens having neither the UV laser light L1 nor the He-Ne laser light L2, and thus with a simple configuration. Thus, it is possible to realize the exposure apparatus 10 that can selectively use two types of laser light having a large wavelength difference according to the purpose.

In the above-mentioned embodiment, the case where the present invention is applied to the exposure apparatus 10 used in the mastering process is described, but the present invention is not limited to this, and the point is that the first and second laser light sources are used. If it is an exposure apparatus that performs focusing processing on the exposed surface of the exposed object using laser beams having different wavelengths emitted from, it can be applied to various other exposure apparatuses.

Further, in the above-mentioned embodiment, the case of the exposure apparatus 10 provided with the main laser light source 11 for emitting the UV laser light L1 and the sub laser light source 12 for emitting the He—Ne laser light L2 has been described. Is not limited to this, and since the wavelength difference between the two types of laser beams provided for focusing and signal recording is large, if the exposure apparatus can only deal with the aberration of only one of them, Any laser light may be used.

[0028]

As described above, according to the present invention, when the second laser beam having a large wavelength difference with respect to the first laser beam is focused on the exposed surface of the exposed body, New focusing information is obtained by performing a correction process of the error according to the aberration of the objective lens on the detection result indicating the focusing information of the exposed surface detected based on the reflected light reflected based on the preset correction value. Since the position of the objective lens is moved and corrected based on this new focusing information, even when the objective lens having no aberration with respect to the first laser beam is used, Focusing can be performed as in the case of using an objective lens having no aberration for both the two laser beams, and thus two types of laser beams having a large wavelength difference can be used depending on the purpose with a simple configuration. An exposure apparatus and an exposure method capable divided There can be realized.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of an exposure apparatus according to an embodiment.

FIG. 2 is a flow chart showing a procedure of an exposure method according to an example.

FIG. 3 is a flow chart of a procedure provided for explaining a manufacturing procedure when manufacturing a master stamper.

FIG. 4 is a schematic diagram used for explaining a blank portion required for recording a charactor and a barcode on a substrate.

[Explanation of symbols]

1, 16 ... Substrate, 1A ... One side of substrate, 2 ... Resist layer, 3 ... Resist master, 4 ... Conductive layer, 5 ...
... Electroformed layer, 6 ... Master stamper, 10 ... Exposure device, 11 ... Main laser light source, 12 ... Sub laser light source, 13 ... Quarter wave plate, 14 ... Half mirror, 1
5, 18 ... Mirror, 17 ... Objective lens, 19, 20
...... Position sensor, 21 ・ ・ ・ Focus control section.

Claims (4)

[Claims] 1. An exposure apparatus adapted to record a desired information pattern as a latent image on a surface to be exposed of an object to be exposed by performing an exposure process using a laser beam emitted from a laser light source. A first laser light source for emitting a first laser light for recording onto an exposed surface of the exposed body, and a second laser light for focusing having a large wavelength difference from the first laser light. Is disposed on the optical axis of the first laser light and has an aberration corresponding to only the wavelength region of the first laser light. An objective lens that does not exist, a detection unit that receives the reflected light of the second laser light reflected on the exposed surface of the exposed body, and detects the focusing state on the exposed surface, and the position detection unit. The above target obtained from the detection result The focusing information on the optical surface is subjected to error correction processing according to the aberration of the objective lens to generate new focusing information, and the objective lens is caused to emit light of the first laser beam according to the new focusing information. An exposure apparatus comprising: focusing control means for controlling movement along an axis. 2. The focusing control means has a correction value of a focusing position of the objective lens based on a correspondence relationship between the first and second laser lights obtained by learning in advance, and uses the correction value. 2. The exposure apparatus according to claim 1, wherein the focusing position of the objective lens by the second laser light is moved and corrected to the focusing position by the first laser light. 3. An exposure method in which a desired information pattern is recorded as a latent image on an exposed surface of an exposed object by performing an exposure process using a laser beam emitted from a laser light source. The second laser light for focusing, which has a large wavelength difference from the first laser light for recording, corresponds to only the wavelength region of the first laser light and has no aberration. The reflected light emitted from the exposed surface of the exposed body through the objective lens arranged on the optical axis of the light and reflected by the exposed surface of the exposed body of the second laser light is received. When the focusing state on the exposed surface is detected, the focusing information on the exposed surface obtained from the detection result is subjected to error correction processing according to the aberration of the objective lens to generate new focusing information. Both The exposure method, characterized in that the objective lens along connexion moved in the optical axis of the first laser beam in accordance with the new Fuokashingu information. 4. The first and the second obtained by learning in advance.
The focusing position of the second laser light is moved and corrected to the focusing position of the first laser light by using the correction value of the focusing position of the objective lens based on the correspondence relation of the laser light of. Item 3
Exposure method according to 1.