JPH05251309A - Lighting optical system - Google Patents

Abstract

PURPOSE:To provide a lighting optical system which is used for a semiconductor exposing device using laser light as a lighting source and can more uniformly illuminate the surface of a reticle by solving the problems of a decline in resolution and ununiformity of illumination caused by speckles and leakage light from a laser. CONSTITUTION:The title optical system is constituted of a light source image generating means which generates a large number of light source images by using laser beams emitted from a laser light source 2, light shielding mask 9 which has the shape corresponding to the light source image generating means near the emitting surface of the generating means and intercepts leakage light from the generating means, reflecting mirror 6 for reflecting the laser light, and condenser lens 11 through which the surface of a reticle is irradiated with beams emitted from the generating means in a state where the beams are superimposed upon another so that a decline in light quantity can be reduced and more uniform illumination can be obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical illumination system, and more particularly to an illumination optical system for uniformly illuminating a reticle surface using a laser beam as a light source in a semiconductor exposure apparatus.

[0002]

2. Description of the Related Art In recent years, the miniaturization of circuit patterns of semiconductor devices, especially super LSIs, and the progress of high integration have been remarkable,
The line width of the circuit pattern is advancing to submicron of 1 μm or less. A semiconductor exposure apparatus capable of obtaining high resolution is required to enable finer patterns and higher integration.

Generally, the shorter the wavelength used is, the better the resolution becomes. Therefore, conventionally, an ultrahigh pressure mercury lamp or a xenon mercury lamp has been used as a light source for illumination.
Since the light fluxes from these light sources have no directivity and have low luminance, the exposure time becomes long and it is difficult to obtain high throughput.

On the other hand, recently, a semiconductor exposure apparatus using an excimer laser having a wavelength of 250 nm or less in the far ultraviolet region as a light source for illumination has been put into practical use.

The illumination optical system of the conventional semiconductor exposure apparatus will be described below. FIG. 4 is a schematic configuration diagram of a conventional semiconductor exposure apparatus, which is shown in JP-A-64-37837. In FIG. 4, reference numeral 41 is an exposure mechanism section. Four
An illumination light source 2 is a light source such as an excimer laser. 43 is a mirror, 44 is a concave lens, and 45 is a convex lens. These lenses 44 and 45 have a role as a beam expander, and expand the beam diameter of the laser to the size of the fly-eye integrator 47. To do.

Reference numeral 46 is a mirror, and 47 is a fly-eye integrator for uniformly illuminating the reticle. 48 is a mirror, 49 is a condenser lens,
The lens 49 collimates the beam emitted from the fly-eye integrator 47. Reference numeral 50 is a reticle on which a circuit pattern is drawn, 51 is a reticle holder that attracts and holds the reticle 50, 52 is a projection lens that projects the pattern of the reticle 50, and 53 is a wafer on which the pattern of the reticle 50 is printed.

Reference numeral 54 denotes an XY stage, which moves in the XY directions when the wafer 53 is adsorbed, held, and baked. Reference numeral 55 is a surface plate of the exposure mechanism section.

The operation of the semiconductor exposure apparatus configured as described above will be described below.

First, the beam emitted from the excimer laser light source 42 is reflected by the mirror 43 and expanded by the beam expanders 44 and 45. Expanded beam is mirror 4
The light is reflected at 6, and the fly-eye integrator 47 generates a large number of light source images.

A large number of light source images emitted from the fly-eye integrator 47 are reflected by the mirror 48, collimated by the condenser lens 49 in a superposed state, and uniformly illuminate the reticle 50. Then, the circuit pattern drawn on the reticle 50 is projected onto the wafer 53 by the projection lens 52, and the pattern of the reticle 50 is printed.

FIG. 5 is a schematic diagram of an illumination optical system, which is shown in Japanese Patent Laid-Open No. 59-226317.

In FIG. 5, reference numeral 61 is an illumination light source, which is a light source such as an excimer laser. The laser beam emitted from the laser light source 61 is condensed in a spot shape by the scanning optical device 62 and is two-dimensionally scanned on the scanning surface 63. The light beam from the scanning surface 63 is converted into a parallel light beam by the collimator lens 64 having a focal point on the scanning surface 63 and is incident on the fly-eye lens 65.

The beam emitted from the fly-eye lens 65 illuminates a reticle 67 on which a circuit pattern is drawn by a condenser lens 66, and the projection lens 6
8, the pattern is printed on the wafer 69.

[0014]

However, in the above-mentioned conventional configuration, with the recent increase in the degree of integration of VLSI, the uniformity of illumination is required to be more uniform. When laser light is used, since the laser light has high straightness, part of the laser light leaks from the gap of the fly-eye integrator, and the leaked laser light remains on the reticle surface with its intensity distribution. It has become difficult to reach and obtain sufficient uniformity.

In addition, there is a problem that if a high resolution of submicron of 1 μm or less is obtained, the resolution is lowered due to the influence of the intensity distribution and the like.

An object of the present invention is to solve the above-mentioned problems of the prior art, and an object thereof is to provide an illumination optical system which suppresses leaked light from a fly-eye integrator and illuminates the reticle surface more uniformly.

[0017]

In order to achieve this object, the present invention provides a light source image generating means for generating a large number of light source images using a beam emitted from a laser light source, and an emission surface of the light source image generating means. And a light-shielding mask for irradiating the surface to be irradiated with the beams emitted from the light source image generating means in a superposed state.

[0018]

According to the present invention, according to the above construction, the N lenslets forming the fly-eye integrator, which is the light source image generating means, and the corresponding light-shielding masks are used. At the same time when the light is separated into beams, the light-shielding mask corresponding to the light source image generating means suppresses the generation of leaked light from the light source image generating means, so that the uniformity of illumination can be improved.

[0019]

(Embodiment 1) Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a schematic configuration diagram of a semiconductor exposure apparatus in one embodiment of the present invention. In FIG. 1, reference numeral 1 is an exposure mechanism section. An illumination light source 2 is, for example, an excimer laser light source.

The exposure mechanism section 1 will be described in detail. Three
Is a mirror, 4 is a concave lens, 5 is a convex lens,
Numerals 4 and 5 have a role as a beam expander, and expand the laser beam diameter to approximately the size of the convex lens 6.

Reference numeral 6 is a mirror, 7 is a convex lens, and 8 is a fly-eye integrator for uniformly illuminating the reticle. This fly-eye integrator 8
2A, as shown in the plan view of FIG. 2A, a large number of quadrangular prisms are joined together.
As shown in the side view of (b), each is formed into a convex spherical surface and has the function of a positive lens.

Reference numeral 9 denotes a light-shielding mask. The light-shielding mask 9 has a shape corresponding to the fly-eye integrator 8 as shown in the perspective view of FIG. 3, and has a role of preventing light leaking from the joint surface. .. Reference numeral 10 is a reflection mirror that reflects the beam emitted from the fly-eye integrator 8. A condenser lens 11 collimates the beam emitted from the fly-eye integrator 7.

Reference numeral 12 is a reticle on which a circuit pattern is drawn, 13 is a reticle holder for adsorbing and holding the reticle 12, 14 is a projection lens for projecting the pattern of the reticle 12, and 15 is a wafer on which the pattern is printed. 16
Is an XY stage, which moves in the XY directions when the wafer 15 is adsorbed, held, and baked. Reference numeral 17 is a surface plate of the exposure mechanism section.

The operation of the semiconductor exposure apparatus having the above structure will be described below.

First, the beam emitted from the excimer laser light source 2 is reflected by the mirror 3, and the beam expander 4,
Expanded by 5. The expanded beam enters a fly-eye integrator 8 which is a light source image generating means. Since the focal length of the convex surface on the incident surface side of the fly-eye integrator 8 is almost equal to the thickness of the fly-eye integrator 8, the beam incident on the fly-eye integrator 8 is separated by the quadrangular prism lens elements from each side on the exit surface side. N spot images are formed in the vicinity of the convex surface. The beam leaking from the joint surface of the fly-eye integrator 8 is cut by a light-shielding mask 9 having a shape corresponding to that of the fly-eye integrator 8.

The formed spot image is reflected by the reflection mirror 10, and the N spot images reflected by the reflection mirror 10 are collimated by the condenser lens 11 in a superposed state and uniformly illuminate the reticle 12. .. The circuit pattern drawn on the reticle 12 is projected onto the wafer 15 by the projection lens 14 and the pattern is printed.

As described above, according to this embodiment, since the light-shielding mask is provided in the vicinity of the exit surface of the fly-eye integrator, the leaked light does not directly reach the reticle surface, so that the decrease in the light amount is small. Such uniform illumination can be obtained.

[0029]

As described above, according to the present invention, by providing the light-shielding mask in the vicinity of the exit surface of the fly-eye integrator, the leaked light does not reach the reticle surface directly. Uniform illumination can be obtained.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a semiconductor exposure apparatus according to an embodiment of the present invention.

FIG. 2A is a plan view of a fly-eye integrator in the embodiment. FIG. 2B is a side view of a fly-eye integrator in the embodiment.

FIG. 3 is a perspective view of a light-shielding mask in the example.

FIG. 4 is a schematic configuration diagram of a conventional semiconductor exposure apparatus.

FIG. 5 is a schematic configuration diagram of the illumination optical system.

[Explanation of symbols]

 1 exposure mechanism part 2 illumination light source part 3 reflection mirror 4 beam expander 5 beam expander 6 reflection mirror 7 fly eye integrator 8 fly eye integrator 9 light shielding mask 10 reflection mirror 11 condenser lens 12 reticle 13 reticle holder 14 projection lens 15 Wafer 16 XY stage 17 Surface plate

Continuation of front page (51) Int.Cl. ⁵ Identification number Office reference number FI Technical display location G03F 7/20 505 7818-2H 521 7818-2H (72) Inventor Yoshihito Nakanishi Higashimita, Tama-ku, Kawasaki-shi, Kanagawa 3-10-1 Matsushita Giken Co., Ltd.

Claims (3)

[Claims] 1. A light source which emits pulsed laser light for illuminating an object, and a light source image generating means which generates a large number of light source images by using a beam emitted from the light source.
Illumination comprising: a light-shielding mask means provided in the vicinity of the emission surface of the light source image generating means; and an irradiation means for irradiating the surface to be irradiated with the beams from the light source image generating means in a superposed state. Optical system. 2. The illumination optical system according to claim 1, wherein the light source image generating means comprises a condenser lens and a fly-eye integrator. 3. The illumination optical system according to claim 1, wherein the light source emits pulsed laser light.