JPS63229815A - Exposure system - Google Patents

Abstract

PURPOSE:To freely arrange a laser system for exposure use either longitudinally or transversely by a method wherein a reflection mirror to send the alignment light is installed en bloc on the side of a rear mirror of the laser system for exposure use. CONSTITUTION:A reflection mirror 4 is installed en bloc at the back part of a rear mirror 3 of a laser tube 1 in such a way that it is tilted by 45 deg. with reference to the direction of laser radiation. A laser beam, for alignment use, from a laser system 5 for alignment use enters the mirror 3 via the mirror 4 and goes out from a front mirror 2. Accordingly, if the position of the center of gravity of an exposure system is to be lowered, it is possible to constitute the system in such a way that the laser tube 1 is arranged transversely so that the laser beam enters a projection optical system 6 through mirrors 7a-7c. In addition, if it is not possible to obtain a sufficiently large area for installation of the laser system for exposure use, it is possible to constitute the system in such a way that the laser tube 1 is arranged longitudinally so that the laser beam enters the optical system 6 through mirrors 9, 10.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an exposure apparatus that exposes an object to be exposed, such as a semiconductor wafer, with laser light.

[Prior Art] Exposure apparatuses that project and print circuit patterns onto semiconductor wafers such as tC and LSI require extremely high resolution, and therefore laser apparatuses are used as exposure light sources.

In exposure equipment using such a laser device, when printing a mask pattern on the wafer surface, alignment light is scanned to match the relative positional relationship between the mask pattern and the wafer, and the mask pattern and the wafer are printed. A step of matching the relative positions of the alignment marks made is performed for each printing operation.

On the other hand, in this type of exposure equipment, there are two types: a vertical type in which the exposure laser device is arranged so that the laser oscillation direction is vertical, and a horizontal type in which the laser device is arranged so that the laser oscillation direction is horizontal. There is something.

Therefore, when performing the above alignment work, in the horizontal type, as shown in Fig. 5 (a), it is necessary to place a
A folding mirror 4 having an inclination angle of 1.5 degrees is provided, and the alignment laser beam generated from the alignment laser device 5 is incident on the rear mirror 3 from a direction perpendicular to the laser beam vibration direction of the laser tube 1. The beam is emitted toward the projection optical system through the beam, and alignment work is thereby performed. Similarly, for vertically mounted models, the 5th
As shown in Figure (b), a folding mirror 4 is provided at the rear of the rear mirror 3 of the laser tube 1, and the alignment light incident from the direction perpendicular to the laser oscillation direction is bent by the folding mirror 4 and then enters the rear mirror 3. , the alignment work is performed by emitting the light toward the projection optical system via the front mirror 2.

[Problems to be Solved by the Invention] However, in the configuration in which the folding mirror 4 is installed outside the exposure laser device as described above, this folding mirror 4
The problem is that whether the exposure laser device is placed vertically or horizontally is determined depending on the relationship between the two, and there is no flexibility in terms of configuration.

An object of the present invention is to provide an exposure apparatus in which a laser device for exposure can be freely arranged in both the vertical and horizontal directions.

[Means for solving problems]

The present invention achieves the above object by integrating and incorporating a folding mirror into which alignment light is incident on the rear mirror side of an exposure laser device.

(Function) The optical path of the alignment light is bent at right angles by the folding mirror in the exposure laser device and enters the rear mirror.Therefore, the exposure laser device can be freely placed in both the vertical and horizontal directions. Can be done.

〔Example〕

FIG. 1 is a schematic configuration diagram showing an embodiment of the main part of the present invention. FIG. 1(a) shows an example in which a laser device for exposure is arranged vertically, and FIG. An example is shown below. In both configurations, a folding mirror 4 is attached to the rear of the rear mirror 3 of the laser tube 1 at a angle of 44 mm with respect to the laser oscillation direction.
It is integrally installed with an inclination angle of 5 degrees. The alignment laser beam from the alignment laser device 5 passes through this folding mirror 4 to the rear mirror 3.
It is configured so that the light enters the front mirror 2 and exits from the front mirror 2.

Therefore, when it is desired to lower the center of gravity of the exposure apparatus, the laser tube 1 is placed horizontally as shown in the perspective view of FIG. It can be configured to be bent to enter the projection optical system 6. .

If the installation area of the exposure laser device cannot be increased, the laser tube 1 may be placed vertically as shown in the perspective view of FIG. The light may be configured to enter the projection optical system 6 by bending its optical path.

Incidentally, in both the configurations shown in FIG. 2 and FIG.
3 and is incident on the surface of the wafer 15 via the optical system 14, but when performing alignment work using the alignment light 12, part of the excimer laser light generated from the exposure laser tube 1 There is a system that generates a dye laser and uses this dye laser light as the alignment light 12, but since the excimer laser light itself is pulsed light, position detection information for alignment can only be obtained for a short period of time. , alignment work becomes difficult, and optical system 1
There is a problem in that an achromatic lens must be incorporated as the fourth lens.

Therefore, in this embodiment, the argon ion laser beam (wavelength = 496.5r++++) is converted to a wavelength of 248.2 by using a harmonic crystal (for example, β-BaB204) for the excimer laser beam for exposure (wavelength = 248.25n+n).
Convert it to the second harmonic of 4nl and send it to the alignment light 1.
I am trying to use it as 2.

By using such alignment light, there is no need to generate excimer laser light for exposure during alignment, and its life can be extended. Furthermore, since the alignment light has a wavelength very similar to that of the exposure laser light, there is no need to incorporate a tinting lens into the optical system.

Furthermore, since the argon ion laser beam itself is continuous light, position detection information for alignment can be extracted over a long period of time, making alignment easier. Furthermore, by lowering the intensity of the argon ion laser beam serving as the alignment light, it is possible to prevent the wafer 15 from being exposed by the alignment light.

In this case, laser light other than the argon ion laser can be used to the same extent by suitably harmonics, as long as it includes harmonics corresponding to the wavelength of the excimer laser.

[Effects of the Invention] As described above, according to the present invention, the laser device for exposure can be freely arranged in either the vertical direction or the horizontal direction.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram of main parts showing an embodiment of the present invention;
2, 13, and 3 are perspective views showing examples of the overall configuration of the exposure apparatus, and FIG. 4 is a diagram showing the principle configuration of the projection optical system.
FIG. 5 is a configuration diagram of a conventional example. 1... Laser tube, 2... Front mirror, 3...
Rear mirror, 4... Returning mirror, 5... Laser device for alignment, 6... Projection optical system. Figure 2 Figure 3 Figure 4

Claims (3)

[Claims] (1) A laser device including a front mirror and a rear mirror, which outputs laser light by resonating it between these mirrors, and a projection optical system which irradiates the object to be exposed with the laser light output from the laser device. An exposure apparatus characterized in that a folding mirror for inputting an alignment laser beam input from a direction perpendicular to a laser oscillation direction of the laser apparatus to the rear mirror is integrated into the laser apparatus. Device. (2) The exposure apparatus according to claim (1), wherein harmonics of a laser beam oscillated from another laser device are used as the alignment laser beam. (3) The exposure apparatus according to claim (1), wherein the laser device is an excimer laser, and the second harmonic of another laser beam is used as the alignment laser beam.