JPS61202433A - Optical device for illuminating arcuate region - Google Patents

Abstract

PURPOSE:To utilize a light quantity from a light source on the surface to be emitted without loss by using an optical fiber bundle formed at the incident end in a circular shape and at the emitting end in an arcuate shape. CONSTITUTION:A light diverged from a light source 1 to expose a resist is converged by a condensing optical system 2 to form an ultrafine spot, and incident to an optical fiber bundle 3. The bundle 3 is formed of a fine optical fiber. Its one end is bundled in a circular shape and a luminous flux from the system 2 is incident. The other end is bundled in an arcuate shape to form an arcuate secondary light source. This secondary source emits by a focusing optical system 4 to an article 5 to be illuminated such as an IC manufacturing mask.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to an illumination optical system used in a fine pattern printing apparatus for manufacturing integrated circuits. Reflection projection optics are used to print fine patterns onto wafers to produce integrated circuits. This is an optical system that combines two uneven reflecting mirrors and uses an arcuate slit-shaped illumination beam to perform printing.

The present invention particularly relates to an optical device for creating an arcuate illumination beam for use in this catoptric projection optical system.

[Conventional technology] FIG. 2 shows a conventional arcuate area illumination optical device.

As shown in the figure, a light source (ultra-high pressure mercury lamp) 1, a condensing lens 2, a light-shielding plate 6 with arcuate slits, an imaging lens 4, and a mask 5 are arranged in this order, and the light from the light source 1 is transmitted through the light-shielding plate. An image of the circular arc slit is formed on the mask 5 by the imaging lens 4 through the circular arc slit 6.

[Problems to be Solved by the Invention] In the conventional arc-shaped area illumination optical device, only a part of the luminous flux condensed from the light source to the light shielding plate is used, and most of the remaining luminous flux is blocked, so that the light from the light source is The utilization rate of

An object of the present invention is to provide an arcuate area illumination optical device that eliminates such light borrowing loss and achieves high illumination efficiency.

[Means and operations for solving the problems] The above objects are achieved according to the present invention by using an optical fiber bundle whose input end face is circular and whose output end face is arcuate. In other words, the light flux from the light source is focused on the circular input end face of the optical fiber bundle, and the light flux emitted from the arcuate output end face of the optical fiber bundle is focused on the irradiated surface, so that the amount of light from the light source is completely lossless. can be used on the irradiated surface.

[Embodiment] FIG. 1 shows a first embodiment of the arc-shaped area illumination optical device of the present invention.

In FIG. 1, 1 is a light source for exposing the resist;
For example, an ultra-high pressure mercury lamp is used.

Reference numeral 2 denotes a condensing optical system for converging the luminous flux diverging from the light source 1 at a predetermined position, and 3 denotes an optical fiber bundle consisting of thin optical fibers, one end of which is bundled in a circle, and a condenser optical system is attached to the circular end. A light beam focused by 2 is incident. The other end is bundled into an arc shape and has two arc shapes.
Next, form a light source. Reference numeral 4 denotes an optical system for forming an image of this arc-shaped secondary light source on the irradiation surface, and is constituted by, for example, a lens or a mirror optical system. , 5 is an object to be irradiated, for example, a mask for IC manufacturing, and only a narrow arc-shaped area of the object to be irradiated is illuminated.

The light diverging from the light source 1 is converged by the condensing optical system 2 to form a minute spot, and almost all of the light beam is incident on the circular end of the optical fiber bundle 3.

Thereafter, an arc-shaped secondary light source is formed by the arc-shaped end of the optical fiber bundle, but naturally no loss of light quantity occurs at this time as well.

FIG. 3 shows a second embodiment of the invention. In FIG. 3, 1 is a light source and 7 is an elliptical mirror. Other elements are similar to the first embodiment shown in FIG.

The light emitting part of the light source is arranged at the first focal point of the elliptical mirror 7.

As a result, the light beam diverging from the light source is collected by the elliptical mirror, producing a minute spot at the second focal point of the elliptical mirror. This minute spot is connected to the optical fiber bundle 3.
The illumination light is received by the circular end face of the lamp, and the arc-shaped end face forms an arc-shaped illumination light. When an elliptical mirror is used in this manner, most of the light beam diverged from the light source is collected at the second focal point, so that the light beam from the light source can be made to enter the fiber bundle without loss.

FIG. 4 shows a third embodiment of the present invention. In this embodiment, the optical fiber bundle has two circular input end faces. The two entrance end faces are brought together on the exit side of the fiber bundle to form one arc-shaped exit end. Each input end face is illuminated by a separate light source 1 and elliptical mirror 7, and the light from these sources is combined at a single fiber exit end face to provide bright illumination. Naturally, the entrance end can also be divided into three or more if necessary.

[Effects of the Invention] As is not clear from the above, light from a light source can be converted into an arc-shaped illumination light beam without loss by using an optical fiber bundle whose one end is circular and the other end is arc-shaped.

In this way, the luminous flux from the light source can be efficiently used to illuminate the mask, so the light source can be smaller than conventional illumination optical devices to obtain the same brightness of the irradiation surface, which reduces cost, device size, and This is particularly advantageous in terms of heat generation, etc.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of a first embodiment of the invention. FIG. 2 is a schematic diagram showing a conventional arcuate area illumination optical device. FIG. 3 shows a second embodiment of the invention.゛FIG. 4 shows a third embodiment of the present invention. In the figure: 1: light source, 2: condensing optical system, 3 niobium fiber bundle, 4: imaging optical system, 5: mask, 6: light shielding plate with arc-shaped aperture, 1: elliptical mirror.

Claims (1)

[Claims] an optical means for condensing a light beam from an optical fiber bundle and a light source onto at least one input end surface of the optical fiber bundle; and an optical means for focusing a light beam from an output end surface of the optical fiber bundle on an irradiated surface. An arc-shaped area illumination optical device, characterized in that the input end face of the optical fiber is formed into a circular shape, and the output end face is formed into an arc shape.