JPH0233914A - Lighting optical apparatus - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention is applicable to, for example, super LSI! The present invention relates to an illumination optical device mounted on a stepper used in an exposure process during the manufacture of a semiconductor memory.

[Prior Art] FIG. 2 is an explanatory diagram showing a schematic configuration of the main parts of a conventional illumination optical device and an illumination optical device according to the present invention used in an exposure process during LSI manufacturing. In FIG. 2, 20 is a lamp house, and this lamp house 20 is a lamp 1. A condensing mirror 2 that condenses the light from the lamp 1. Integrator section 4
It consists of a reflector 3°5, a condenser lens 6, and an irradiance monitor 7 that monitors the irradiance of the light from the light source.The effective light rays output from this lamp house 20 (the light used for exposure and mask pattern (below,
The light from the reticle 8 passes through an imaging lens 9 for forming an image on an object to be exposed, and is irradiated onto the exposure surface 10 of the silicon wafer.

In FIG. 3, 42 indicates a specific wavelength (for example, 436 nm) for the purpose of maintaining monochromaticity in order to increase the resolution of the reticle 8.
, ) and the vicinity thereof; 43 is an input lens that aligns the angle of light incident on each rod lens of the mixer lens 44; 44 is composed of a plurality of rod lenses; A mixer lens (also called a ply eye lens) 45 is used to divide the light from each rod lens and add the lights emitted from each rod lens to form a uniform illuminance distribution. An output lens 46 is used to prevent misalignment when the respective lights are superimposed on the surface of the reticle 8, and an aperture 46 regulates the size and range of the light incident on the entrance pupil of the imaging lens 9.

The input lens 43 is the mixer lens 4 as described above.
This is to align the angles of light incident on each of the four rod lenses. In other words, without the input lens 43, the angle of light that enters each rod lens will naturally be close to the optical axis, but for the rod lens, most of the light will enter at a relatively gentle angle, or for the rod lenses in the periphery, it will enter at a tight angle. There will be more light. In other words, the angle of light incident between each rod lens varies. In this case, since the rod lenses are all the same, if left as is, the way the light is transmitted by each rod lens and the exit angle will also vary.

Further, the bandpass filter 42 is usually a substrate made of quartz glass or the like coated with a dielectric film or multiple layers, but the transmission characteristics of the bandpass filter 42 change slightly depending on the incident angle of light. Therefore, conventionally, this bandpass filter 42 is disposed between the input lens 43 and the mixer lens 44 so that there is no difference in transmission characteristics between the vicinity of the optical axis and the peripheral area.

First, the imaging relationship of the conventional illumination optical device described above is as follows.

The entrance surface of the mixer lens is the second focal point of the elliptical condenser mirror, and an image of the elliptical condenser mirror is formed. The reticle is located at the focal point of a condenser lens whose object point is the entrance surface of the mixer lens, and an image of the entrance surface of the mixer lens is formed on the reticle by the condenser lens. Further, for example, the position of the exposed surface of the silicon wafer is at the position of the image of the imaging lens with the reticle as the object point, and the image of the reticle is formed on the exposed surface of the silicon wafer.

[Problems to be Solved by the Invention] Therefore, when foreign matter such as dust adheres to the entrance surface of the mixer lens, its image is transferred onto the wafer by the condenser lens and the imaging lens. Therefore, conventionally, the input lens was used to seal the input side of the mixer lens to ensure that no dust could adhere to it. However, as described above, when the inventive lens is placed closer to the light source than the bandpass filter, the entrance surface of the mixer lens becomes exposed. In this case, the 1-band pass filter is removed for inspection of its transmission characteristics, etc., and there is a problem in that there is a very high possibility that dust will adhere thereto.

The present invention has been made to solve such conventional problems, and it is an object of the present invention to provide an illumination optical device that can prevent dust from entering the mixer lens.

[Means for Solving the Problems] In order to achieve the above object, in the illumination optical device of the present invention, the integrator section includes an input lens, a bandpass filter, and '1!' from the light incident side. E seal board.

The mixer lens is arranged in this order, followed by the output lens.
The entrance surface of the mixer lens is sealed by the sealing plate.

[Function] With the above configuration, there is no difference in the transmission characteristics between the optical axis and the peripheral part of the bandpass filter.Furthermore, since a sealing plate is provided, the mixer can be easily removed when replacing the bandpass filter. There is no possibility of dust getting into the front of the lens and sticking to it.

[Embodiment] Fig. 1 is a sectional view showing an embodiment of the integrator section used in the illumination optical device of the present invention, in which 11 is a lens barrel, 13 is an input lens, and 16 is a lens that transmits only light at a specific wavelength and its vicinity. band pass filters (B, P, F); 18 is a mixer lens frame that is fitted into the lens barrel 11 and is removable; 19 is a quartz filter or the like to prevent dust from entering the mixer lens frame 18; 21 is a mixer lens, 22 is an aperture attached to the exit side of this mixer lens 21, and 23 is this aperture 2.
Provided on the injection side of 2.

It is an output lens attached to the input lens 13, the mixer lens 21, and the aperture 22 by positioning their respective centers, and the aperture 2
2 and the output lens 23 are attached and incorporated as one unit.

Incidentally, in order to further improve the airtightness between the sealing plate 19 and the mixer lens frame 18, it is preferable to interpose a silicone O-ring or the like.

The integrator section shown in FIG. 1 is applied to the integrator section 4 of the illumination optical device shown in FIG.

Also, whether the light emitted from the input lens 13 is B, P, or F.
1a, the light is incident on B, P, and F1a at the same angle, and the light emitted from B, P, and F1a is not affected by angular characteristics and is excellent monochromatic light. is obtained. Further, the mixer lens 21 has a sealing plate 19
．． Since the aperture 22 and the output lens 23 allow them to be brought close to each other in a non-contact manner and are sealed together, they can be taken out for cleaning.

[Effects of the Invention] As explained above, the integrator section of this application includes an input lens, a bandpass filter, a moon plate, a mixer lens, and an output lens installed in this order from the light incident side, and furthermore, the sealing plate closes the mixer lens. Since the entrance surface of the lens is arranged in a sealed manner, there is no dust or dirt on the mixer lens when replacing lenses B, P, and F.

Furthermore, since the output light from the input lens enters B, P, and F, there is no influence of angle characteristics on the transmitted light of B, P, and F, and highly monochromatic light is obtained, allowing high-resolution exposure. I can do it.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an embodiment of an integrator section used in the illumination optical device of the present invention, and FIG. 2 is a schematic diagram of the main parts of the conventional illumination optical device used in the exposure process of semiconductor devices and in the present invention. FIG. 3 is an explanatory diagram showing details of the integrator section of FIG. 2. In the figure. 1 Lamp 4 Integrator part 3.5/Reflector 6: Condenser lens 8 Reticle 9 Imaging lens 13, Input lens 16/B, P, F 18: Mixer lens frame 19/Sealing plate 21, Mixer lens 22, Aperture 23 near Udputu Trends Representative Patent Attorney 1) Haru Kitatake

Claims (1)

[Claims] In an illumination optical device having a light source and an integrator section, the integrator section includes an input lens, a bandpass filter, a sealing plate, a mixer lens,
1. An illumination optical device characterized in that the output lens is arranged in this order, and the entrance surface of the mixer lens is sealed by the sealing plate.