JPH11328745A - Exposure device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an exposure device stably adjusting focus even when an optical axis of a sub-beam of an outward route is shifted. SOLUTION: This device is provided with an out-of-focus amount detection part 16 detecting an out-of-focus amount for a focal surface of this optical disk master disk surface by detecting an inward route out-of-focus amount of an optical axial position of the sub-beam of an inward route after reflecting on the optical disk master disk surface 14 as a skew beam, an optical axis out-of-focus amount detection part 20 detecting an outward route out-of-focus amount of the optical axial position of the sub-beam of the outward route, an operation part 24 obtaining an out-of-offset amount due to the outward route out-of-focus amount between the out-of-focus amounts, an offset adjustment part 26 obtaining a net out-of-focus amount subtracting the out-of-offset amount from the outward route out-of-focus amount and a focus adjustment part 18 adjusting focus based on the net out-of-focus amount. In this device, the outward route out-of-focus amount between the optical axial position and the design position of the sub-beam of the outward route is detected by the optical axis out-of-focus amount detection part 20. Then, the out-of-offset amount due to the detected outward route out-of-focus amount in the inward route out-of-focus amount is corrected by a correction part 22. Thus, even when the optical axis of the sub-beam of the outward route is shifted, the focal adjustment is performed stably by this device.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exposure apparatus for performing focus adjustment using a skew beam method (eccentric auxiliary light beam method).

[0002]

2. Description of the Related Art Conventionally, in an exposure apparatus, focus adjustment is performed using a skew beam method. For example, in an optical disk master exposure apparatus (also referred to as a “mastering apparatus”) for cutting an optical disk master, an exposure beam is intermittently irradiated with modulation data.
The focus error signal due to the exposure beam could not be continuously detected. For this reason, in the optical disk master exposure apparatus, the distance between the objective lens and the optical disk master surface has been adjusted by continuously detecting the focus error signal by the skew beam method.

Prior to the description of the present invention, a conventional example of an exposure apparatus using a skew beam method will be briefly described prior to the description of the present invention with reference to FIG. FIG. 3 is a configuration diagram of a conventional exposure apparatus.

A conventional exposure apparatus 200 includes an objective lens 10 for converging an exposure beam R on an optical disk master surface 14 to be exposed. The optical axis of the exposure beam R coincides with the optical axis of the objective lens 10. Then, the auxiliary beam enters the objective lens 10 as a skew ray of the objective lens 10. The auxiliary beam is applied to the objective lens 10
And is reflected by the optical disk master surface 14. A dichroic mirror 30 is provided to separate the exposure beam R from the auxiliary beam r. The dichroic mirror 30 transmits the exposure beam R and reflects the auxiliary beam r.

Since the auxiliary beam is a skew ray, the position of the optical axis of the reflected auxiliary beam on the return path changes depending on the distance between the objective lens 10 and the optical disk master surface 14. For example, if the position of the optical disk master surface 14 is
The position of the optical axis of the auxiliary beam r0 on the return path when it coincides with the focal plane F1 of the exposure beam of the objective lens 10 is different from the position rf of the optical axis of the auxiliary beam on the return path when they do not match. FIG.
Here, the optical axis of the auxiliary beam on the return path when the optical disk master surface 14 is at the position F2 shifted from the focal plane of the objective lens by ΔL is indicated by a broken line rf.

Therefore, in the skew beam method, it is possible to continuously detect whether or not the optical disk master surface 14 is located at the focal plane by detecting the position of the return path of the auxiliary beam. Therefore, the exposure apparatus 200
Then, the amount of deviation of the optical axis position of the auxiliary beam rf on the return path from the design position (that is, the optical axis position when the focal point coincides) r0 is detected, thereby detecting the amount of deviation of the master surface of the optical disk from the focal plane. A defocus amount detection unit 16 is provided.

Further, the exposure apparatus 200 includes a focus adjusting section 18 for adjusting the distance between the objective lens 10 and the optical disk master surface 14 based on the amount of deviation detected by the defocus amount detecting section 16. I have.

[0008]

However, in the above-described conventional exposure apparatus 200, even if the position of the optical axis of the auxiliary beam on the outward path deviates from the design position, the position of the optical axis of the auxiliary beam on the return path can be adjusted. Will deviate from the design position. That is, even when the exposure surface such as the optical disk master surface and the focal plane coincide with each other, the optical axis deviation is detected by the defocus detection unit 16. In this case, as a result of the focus adjustment by the skew beam method, the optical disk master surface 1
4 is incorrectly adjusted to the non-focal plane. in this way,
When the optical axis of the outward path is shifted, there is a problem that the master surface does not coincide with the focal plane. For this reason, conventionally, the presence or absence of a focus shift due to a shift in the optical axis has been checked at regular intervals using an SEM (scanning electron microscope).

SUMMARY OF THE INVENTION The present invention has been made to solve the above problem, and has as its object to provide an exposure apparatus capable of performing stable focus adjustment even when the optical axis of an auxiliary beam on the outward path is shifted. .

[0010]

To achieve this object, according to an exposure apparatus of the present invention, an objective lens for converging an exposure beam on an exposure surface to be exposed, and a skew ray of the objective lens Defocus amount detection for detecting the defocus amount of the exposure surface with respect to the focal plane of the objective lens by detecting the departure amount of the optical axis position of the auxiliary beam on the return path after being reflected by the exposure surface with respect to the design position Department and
In an exposure apparatus including a focus adjustment unit that adjusts a distance between an objective lens and an exposure surface based on the amount of defocus,
An optical axis shift amount detection unit that detects a shift amount of the optical axis position of the auxiliary beam on the forward path incident on the objective lens with respect to the design position, and a correction that corrects an offset shift amount due to the forward shift amount among the focus shift amounts. And a unit.

As described above, according to the exposure apparatus of the present invention, the optical axis deviation amount detection unit detects the outward deviation amount of the optical axis position of the outward auxiliary beam from the design position. Then, the offset deviation amount caused by the forward path deviation amount is corrected.
As a result, focus adjustment can be performed based on the net defocus amount that does not include the offset deviation amount. Therefore, according to the exposure apparatus of the present invention, stable focus adjustment can be performed even when the optical axis position of the outward auxiliary beam deviates from the design position.

In the exposure apparatus according to the present invention, preferably, as a correction unit, a calculation unit for obtaining an offset deviation amount based on a forward deviation amount, and a net defocus amount obtained by subtracting the offset deviation amount from the defocus amount. It is preferable to provide an offset adjusting unit for calculating the amount of the defocus and inputting the net defocus amount to the focus adjusting unit.

In the exposure apparatus having this configuration, when correcting the offset deviation amount, first, the calculation unit determines the offset deviation amount caused by the forward path deviation amount. Then, the adjustment unit obtains a net defocus amount obtained by subtracting the offset deviation amount from the return path deviation amount. Then, the focus adjustment unit performs focus adjustment based on the net defocus amount. Therefore, even when the optical axis position of the auxiliary beam on the outward path deviates from the design position, stable focus adjustment can be performed.

In the exposure apparatus of the present invention, preferably, a deflecting unit for deflecting the forward beam before entering the optical axis shift amount detecting unit as the correcting unit, and an offset shift amount based on the forward shift amount. And a driving unit for controlling the amount of deflection by the deflecting unit so as to eliminate the problem.

In the exposure apparatus having this configuration, when correcting the offset shift amount, the deflection unit deflects the forward auxiliary beam to correct the optical axis shift. That is, by deflection, the optical axis position of the outward auxiliary beam at the stage of entering the objective lens is made to coincide with the design position. As a result, the return path shift amount detected by the focus shift amount detection unit is a net focus shift amount that does not include the offset shift amount. Therefore, a net defocus amount is input to the focus adjustment unit. Therefore, even when the optical axis position of the auxiliary beam on the outward path deviates from the design position, stable focus adjustment can be performed.

In practicing the present invention, it is preferable that each of the defocus amount detecting unit and the optical axis deviation amount detecting unit is constituted by a two-part sensor.

As described above, when a two-part sensor is used,
When the optical axis coincides with the design position, the detected light intensities of the two split sensors constituting the two-split sensor are made equal to each other, and the difference between the detected light intensities of the two split sensors is determined. The deviation amount and the return path deviation amount can be respectively detected.

In practicing the present invention, preferably, a dichroic mirror that transmits an exposure beam and reflects an auxiliary beam, guides a part of the auxiliary beam to an optical axis deviation amount detection unit, And an isolator for guiding another part of the mirror to the dichroic mirror.

As described above, by using the dichroic mirror, the exposure beam and the auxiliary beam can be easily separated. Further, if an isolator is used, a part of the outward auxiliary beam can be easily separated and taken out. Therefore, a device that does not transmit light can be used as the optical axis shift amount detection unit.

In practicing the present invention, it is preferable that the exposure surface is an optical disk master surface. INDUSTRIAL APPLICABILITY The exposure apparatus of the present invention is suitable for use as an optical disk original plate exposure apparatus that is used when cutting an optical disk master and requires high-precision focus adjustment.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of an exposure apparatus according to the present invention will be described with reference to the drawings. The drawings referred to merely schematically show the size, shape, and arrangement of each component so that the present invention can be understood. Therefore, the present invention is not limited only to the illustrated example.

<First Embodiment> In a first embodiment, an example of an optical disk exposure apparatus 100 in which a master surface of an optical disk is exposed will be described. FIG. 1 is a block diagram for explaining the configuration of an exposure apparatus 100 according to the first embodiment. As shown in FIG. 1, an exposure apparatus 100 according to this embodiment includes an objective lens 10, a defocus amount detection unit 16,
The apparatus includes a focus adjustment unit 18, an optical axis shift amount detection unit 20, a correction unit 22, a dichroic mirror 28, and an optical axis shift amount detection unit 20.

The exposure beam R for irradiating the optical disk master surface 14 to be exposed passes through the dichroic mirror 28 and enters the objective lens 10. The optical axis of the exposure beam R coincides with the optical axis of the objective lens 10. Then, the exposure beam is focused on the optical disk master surface 14 by the objective lens 10.

Also, in this exposure apparatus, the focal plane of the objective lens 10 and the optical disk master 1
Focus adjustment is performed so as to match 4. For this reason, the auxiliary beam r0 as a skew beam is
Is irradiated.

The auxiliary beam r1 is supplied to the isolator 30
Is guided to the dichroic mirror 28. And
The auxiliary beam r0 is reflected by the dichroic mirror 28 and enters the objective lens 10. Auxiliary beam r0
Enter the objective lens 10 as a skew ray. The auxiliary beam r0 that has passed through the objective lens 10 is reflected by the optical disk master surface 14.

In order to distinguish the auxiliary beam r0 before entering the optical disk master surface 14 from the auxiliary beam reflected on the optical disk master surface 14, it is also referred to as an outward auxiliary beam. In addition, the auxiliary beam r0 reflected by the optical disk master surface 14 is also referred to as a return path auxiliary beam to distinguish it from the auxiliary beam before reflection.

The auxiliary beam r0 reflected by the optical disk master surface 14 passes through the objective lens 10 again and enters the dichroic mirror 28. Then, the auxiliary beam r on the return path is reflected by the dichroic mirror 28 and enters the defocus amount detection unit 16. This defocus amount detection unit 16
Is composed of a two-part sensor 16.

When the optical axis of the auxiliary beam r0 on the return path coincides with the design position, that is, when the master surface 14 of the optical disk coincides with the focal plane F1 of the objective lens 10, the split sensor 16 splits the sensor into two. The sensors are installed so that the detection light intensities of two split sensors (not shown) constituting the sensor are equal to each other. In FIG. 1, the optical path of the auxiliary beam whose optical axis coincides with the design position is indicated by a solid line r0.

The irradiation position of the auxiliary beam as the skew light beam on the optical disk master surface 14 differs depending on the distance between the optical disk master surface 14 and the objective lens 10.
For this reason, when the optical disk master surface 14 does not coincide with the focal plane, the optical axis of the auxiliary beam on the return path deviates from the design position (that is, the optical axis when coincident with the focal plane). The amount of this deviation is referred to as a return path deviation amount.

The two-split sensor 16 detects the deviation of the return path by calculating the difference between the light intensities of the auxiliary beams on the return path detected by the two split sensors. Further, the defocus amount detection unit 16 constituted by the two-part sensor 16 detects the defocus amount of the optical disk master surface 14 with respect to the focal plane based on the return path deviation.

Then, the focus adjusting section 18 adjusts the distance between the master surface 14 of the optical disc and the objective lens 10 to perform focusing so that the defocus amount becomes zero.

However, if the optical axis of the auxiliary beam on the outward path deviates from the design position, the apparent deviation amount of the return path will be detected by the defocus amount detecting section 16 even if the focus is in focus. In FIG. 1, an auxiliary beam whose optical axis is shifted from the design position is indicated by a broken line r1 as an optical axis shifted auxiliary beam.

Then, the position of the optical disk original plate surface 14 is changed to F shown in FIG.
When the optical disk is moved to the position 2, the optical disk master surface 14 and the focal plane 14 do not coincide with each other. In FIG.
The optical axis of the auxiliary beam when the apparent return path deviation amount is set to zero is indicated by a chain line rf. As described above, if the optical axis of the auxiliary beam on the outward path is shifted, accurate focus adjustment cannot be performed by detecting only the shift amount on the return path.

Therefore, in the exposure apparatus 100, a part of the forward auxiliary beam incident on the objective lens is separated and extracted by the isolator 30. Then, the separated auxiliary beam on the outward path is made incident on the optical axis deviation amount detection unit 20. The optical axis deviation amount detection unit 20 detects the amount of deviation of the optical axis position r1 of the auxiliary beam on the outward path with respect to the design position r0. In this embodiment, the optical axis shift amount detection unit 20 is configured by a two-division sensor 20 as in the case of the focus shift amount detection unit 16.

When the optical axis of the auxiliary beam on the outward path coincides with the design position r0, that is, when there is no deviation of the optical axis, the split sensor 20 is divided into two split sensors (not shown). ) Are installed so that the detected light intensities are equal to each other. This two-part sensor 20
The difference between the light intensities of the auxiliary beams on the outward path respectively detected by the two divided sensors is obtained, thereby detecting the deviation amount on the outward path.

Then, based on the forward deviation detected by the optical axis deviation detector 20, the correction unit 22 corrects the offset deviation of the return deviation caused by the forward deviation. In the first embodiment, the correction unit 22 is
And an offset adjusting unit 26. The calculation unit 24 calculates the offset deviation amount based on the forward deviation amount.

Then, the offset adjusting unit 26 obtains a net defocus amount obtained by subtracting the offset deviation amount from the return path deviation amount. For example, when the focus is initially set, the offset shift amount is equal to the apparent focus shift amount detected by the focus shift amount detection unit 16. Therefore, in this case, the net defocus amount becomes zero. Further, for example, even if the apparent defocus amount detected by the defocus amount detection unit 16 is zero, the net defocus amount is zero if the optical axis of the outward auxiliary beam is deviated. Not be.

Then, the offset adjusting section 26 inputs the net defocus amount to the focus adjusting section 18. The focus adjustment unit 18 to which the net defocus amount is input performs focus adjustment based on the net defocus amount. For example, when the net defocus amount is zero, the focus adjustment unit 18 keeps the distance between the original optical disk surface 14 and the objective lens 10 as it is.

In adjusting the focus by the focus adjusting section 18, the relative distance between the original optical disk surface 14 and the objective lens 10 is adjusted. Therefore, for example, the objective lens 10 may be fixed and the optical disk master surface 14 may be displaced. Further, for example, the position of the optical disk master surface 14 may be fixed, and the objective lens 10 may be displaced.

As described above, according to the exposure apparatus 100 of the first embodiment, the forward shift amount is obtained, and the forward shift amount is calculated based on the return shift amount.
Subtract the offset deviation amount due to the forward path deviation amount,
Find the net defocus amount. Then, focus adjustment is performed based on the net shift amount. Therefore, even when the optical axis position of the auxiliary beam on the outward path deviates from the design position, stable focus adjustment can be performed.

<Second Embodiment> Next, an exposure apparatus 102 according to a second embodiment will be described with reference to FIG. FIG. 2 is a block diagram for explaining the configuration of the exposure apparatus 102 according to the second embodiment. The exposure apparatus 102 according to the second embodiment has the same configuration as the exposure apparatus 100 according to the first embodiment except that a deflection unit 32 and a driving unit 34 are provided as the correction unit 22a. . Therefore, in the second embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted.

The exposure apparatus 102 according to the second embodiment includes an A / O deflector 32 as a deflecting unit 32 as a correcting unit 22a. This A / O deflector 32
Has a function of deflecting the auxiliary beam r on the outward path before entering the optical axis shift amount detection unit 20.

The amount of deflection is controlled by the drive unit 34. The drive unit 34 controls the amount of deflection by the deflecting unit based on the amount of forward deviation detected by the optical axis deviation detection unit 20 so that the offset deviation is eliminated. That is,
With this control, the optical axis position of the auxiliary beam on the outward path at the stage of entering the objective lens matches the design position. As a result, the return path shift amount detected by the focus shift amount detection unit is a net focus shift amount that does not include the offset shift amount.

Therefore, a net defocus amount is input to the focus adjustment unit 18. Therefore, even when the optical axis position r of the auxiliary beam on the outward path deviates from the design position, stable focus adjustment can be performed.

[0045]

As described above in detail, according to the exposure apparatus of the present invention, the optical axis shift amount detecting section detects the forward shift amount between the optical axis position of the forward auxiliary beam and the design position. . Then, the correction unit corrects the offset deviation amount due to the detected forward deviation amount among the return deviation amounts. Therefore, according to the present invention, stable focus adjustment can be performed even when the optical axis of the auxiliary beam on the outward path is shifted.

[Brief description of the drawings]

FIG. 1 is a block diagram for explaining an exposure apparatus according to a first embodiment.

FIG. 2 is a block diagram for explaining an exposure apparatus according to a second embodiment.

FIG. 3 is a block diagram for explaining a conventional exposure apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Objective lens 14 Optical disk master surface 16 Defocus amount detection part 18 Focus adjustment part 20 Optical axis deviation amount detection part 22 Correction part 24 Operation part 26 Offset adjustment part 28 Diclock mirror 30 Isolator 32 A / O deflector 34 Drive part 100, 102,200 Exposure device R Exposure beam r, rf Auxiliary beam r0 Design auxiliary beam r1 Optical axis shift auxiliary beam

Claims (6)

[Claims] 1. An objective lens for converging an exposure beam on an exposure surface to be exposed, and a design of an optical axis position of a return path auxiliary beam after being reflected by the exposure surface as a skew ray of the objective lens. A defocus amount detection unit that detects a defocus amount of the exposure surface with respect to a focal plane of the objective lens by detecting a return path deviation amount with respect to a position; and the objective lens and the exposure surface based on the defocus amount. An exposure apparatus comprising: a focus adjustment unit that adjusts a distance between the optical axis shift amount detection unit that detects a forward path deviation amount with respect to a design position of an optical axis position of a forward path auxiliary beam incident on the objective lens; An exposure apparatus, comprising: a correction unit that corrects an offset shift amount caused by the forward shift amount among the focus shift amounts. 2. The exposure apparatus according to claim 1, wherein, as the correction unit, a calculation unit that calculates the offset shift amount based on the forward shift amount, and the offset shift amount is subtracted from the focus shift amount. An exposure apparatus, comprising: an offset adjustment unit that calculates a net defocus amount and inputs the net defocus amount to the focus adjustment unit. 3. The exposure apparatus according to claim 2, wherein, as the correction unit, a deflecting unit that deflects the forward path auxiliary beam before entering the optical axis deviation amount detection unit; A driving unit for controlling the amount of deflection by the deflecting unit so that the amount of offset deviation is eliminated. 4. The exposure apparatus according to claim 1, wherein the defocus amount detection unit and the optical axis deviation amount detection unit include:
An exposure apparatus, wherein each of the exposure apparatuses comprises a two-part sensor. 5. The exposure apparatus according to claim 1, wherein: a dichroic mirror that transmits the exposure beam and reflects the auxiliary beam; An exposure apparatus, comprising: an isolator that guides a part of the auxiliary beam to the optical axis shift amount detection unit and guides another part of the auxiliary beam to the dichroic mirror. 6. The exposure apparatus according to claim 1, wherein the exposure surface is a master optical disk.