JPH01147516A - Beam position controller - Google Patents

Abstract

PURPOSE:To correct the position of a beam without changing its direction by providing parallel plane plates transmissive to the beam in this approximately parallel beam so that they can be rotated around axes perpendicular to the beam. CONSTITUTION:Two parallel plane plates 2-a and 2-b are arranged in the laser beam from a laser light source 3 so that respective revolving shafts 20 and 21 are orthogonal to each other (in twisting positions), and the beam is displaced upward, downward, and perpendicularly on the surface of paper. Antireflection films for the laser wavelength are provided on both faces of two parallel plane plates. Revolving shafts 20 and 21 are arranged perpendicularly to the beam; and in a projection type semiconductor exposure device 4, the beam from the laser light source 3 is made incident on a fly-eye lens 9 and is turned downward by a mirror 10 and is uniformly projected to a reticle 12, where a negative pattern is drawn, by a condenser lens 11, and the image is transferred to a wafer 14 mounted on a stage 15 by a projection optical system 13. Angles of inclination of parallel plane plates are calculated by a computer 6 and parallel plane plates are rotated by actuators to correct the positional deviation of the beam.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of the Invention] The present invention relates to a beam position control device in an apparatus using a parallel beam as a light source such as a laser, and particularly relates to a beam position control device in a semiconductor exposure device or the like using a laser as a light source. .

[Prior Art] In precision optical equipment such as semiconductor exposure equipment that uses a parallel beam such as a laser as a light source, when a pulsed laser or other such device that generates heat and vibrates as a light source, the straightness of the parallel beam is utilized to direct the light source. In some cases, the equipment and equipment may be arranged separately. that time,
The relative positional relationship between the light source and the device may change due to vibrations, changes over time, etc., and the position of the beam incident on the device may shift, resulting in problems such as a decrease in pattern accuracy.

To solve this problem, a device is known in which a mirror is placed in the parallel beam and the angle of the mirror is adjusted to align the device with the beam position. However, when adjusting the angle of the mirror, the angle of the beam moves twice that angle by 8, so it is difficult to adjust the angle, especially when the light source and the device are far apart.
It is difficult to perform highly accurate matching.

In addition, although the application of ultraviolet lasers has been progressing in various places in recent years, the reflectance of mirrors in the ultraviolet region is generally low.Especially, high-power ultraviolet lasers such as excimer lasers, which are most commonly applied among ultraviolet lasers, In consideration of damage caused by the laser, the mirror coating is made of a dielectric material, but in such a case, it is difficult to achieve a reflectance of 98% or more and the cost is also high. Therefore, 100
The remainder after subtracting the reflectance from the % becomes a loss of light quantity, resulting in a decrease in the efficiency of the device.

[Object of the Invention] As described above, the present invention is capable of controlling a semiconductor exposure apparatus or the like that uses a laser as a light source so that the position of beam incidence on the apparatus does not shift even if the relative positional relationship between the light source and the apparatus changes. The purpose is to provide a beam position control device.

[Structure and operation of the invention] FIG. 1 is a diagram showing the principle of the invention. A parallel plane plate 2 which is transparent (for example transparent) to the parallel beam 1 is provided in the parallel beam 1 so as to be rotatable as shown by an arrow A around an axis (not shown) perpendicular to the beam. If the thickness of the parallel plane plate 2 is d1 and the refractive index is n, and if it is tilted by an angle θ as shown in the figure, the direction of the beam 1 will not change but will be displaced by X. This displacement amount X is expressed by .

For example, when n=1.5 and d=10 mm, a tilt of 1 minute gives x w 1 μm, allowing extremely high resolution position control.

Further, by applying an anti-reflection film for the beam wavelength on both sides of the parallel plane plate 2, it is easy to suppress the light amount loss to 0.4% or less.

[Example] Fig. 2 shows an example in which the beam position control device according to the present invention is applied to a projection type semiconductor exposure apparatus using a laser light source. The parallel plane plates 2-a and 2-b are arranged so that their rotational axes 20.21 are perpendicular to each other (in the twisted position), and the beams are configured to be displaceable in the vertical direction of the plane of the paper and in the direction perpendicular to the plane of the paper. There is. Both surfaces of these two parallel plane plates are coated with an antireflection film for the laser wavelength. An antireflection film with a one-sided reflectance of 0.2X or less and excellent laser strength can be easily obtained. Therefore, the light amount loss per parallel plane plate is less than 0.4.The zero rotation axes 20.degree. 21 are both arranged perpendicular to the beam.

Although the rotational axes 20 and 21 are schematically shown in the plane parallel plate, the positions of these axes are not limited, and may be at any position as long as they are perpendicular to the beam and orthogonal to each other. 4 is a projection type semiconductor exposure apparatus, in which a beam from a laser light source 3 enters a fly's eye lens 9, is bent downward by a mirror IO, and is uniformly irradiated by a condenser lens 11 onto a reticle 12 on which an original pattern is drawn. The image is projected onto the wafer 1 mounted on the stage 15 by the projection optical system 13.
Transfer onto 4. Each member (9 to 1) constituting the exposure device 4
5) are all mounted on surface plate 1B. If the position of the laser beam incident on the fly's eye lens 9 shifts due to vibration or the like, the illuminance on the wafer 14 surface will decrease, or in severe cases, the printed image of the pattern will deteriorate.5 is a gyro fixed to the surface plate 16. be. A gyro 5 detects vertical and horizontal displacements of the exposure device 4. Based on this detected amount of displacement, the computer 6 calculates the angle at which the parallel plane plates 2-a, 2-b should be tilted, and an actuator (not shown) moves the parallel plane plates 2-a, 2-b by the calculated amount. - Rotate b around the rotation axis 20.21. As a result, each parallel plane plate 2-a, 2-b is tilted by the amount necessary to correct the amount of deviation of the laser beam relative to the exposure device 4, and the position of the laser beam entering the fly-eye lens 9 is always kept constant. Can be done.

FIG. 3 shows a gyro 5 used to detect the displacement of the exposure device 4.
7 shows how to directly monitor beam position without using
is a half mirror that partially reflects the beam heading toward the fly-eye lens 9 and takes it out and guides it to the photoelectric position sensor 8. Since the half mirror and sensor 8 are fixed in the exposure device 4, the beam on the position sensor 8 is By sending position information to a computer, the amount of inclination of the parallel plane plates 2-a and 2-b can be controlled so that the beam position does not shift. This method is particularly effective when the laser is continuous wave.

[Effects of the Invention] As explained above, the beam position control device according to the present invention has a simple configuration in which a parallel plane plate is placed in the beam and is tilted by the necessary amount, so that the beam position can be controlled without changing the direction of the beam. The position can be corrected. Therefore, when a light source that emits a parallel beam and a device that uses this beam are placed separately, the beam irradiation position can always be kept constant even if the position of the light source relative to the device is shifted due to vibration or the like.

Furthermore, loss of light amount can also be minimized.

[Brief explanation of the drawing]

FIG. 1 is a principle diagram of the present invention, FIG. 2 is a configuration diagram of an embodiment of the present invention, and FIG. 3 is an explanatory diagram of another example of the position displacement sensor according to the present invention. 1; Beam, 2.2-a, 2-b; Parallel plane plate, 3; Laser light source, 4; Exposure device, 20.21.30, Rotation axis.

Claims (8)

[Claims] (1) A beam position control device characterized in that a parallel plane plate transparent to the beam is provided in a substantially parallel beam so as to be rotatable around an axis perpendicular to the beam. (2) The beam position control device according to claim 1, characterized in that the two parallel plane plates are provided, and the rotational axes of both parallel plane plates are orthogonal to each other. (3) A position displacement sensor is provided for detecting the relative position of the beam with respect to a beam using device that uses the beam, and the rotation angle of the parallel flat plate is controlled in accordance with the output of the position displacement sensor. A beam position control device according to claim 1 or 2, characterized in that: (4) The beam position control device according to claim 3, wherein the position displacement sensor is a gyro sensor. (5) The beam position control device according to claim 3, wherein the position displacement sensor is a photoelectric position sensor. (6) The beam position control device according to any one of claims 1 to 5, wherein the parallel beam is a laser beam. (7) The beam position control device according to claim 6, wherein the laser light is an ultraviolet laser light. (8) The beam position control device according to claim 7, wherein the ultraviolet laser light is an excimer laser light.