JPH0532899B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an illumination optical device mounted on a stepper used in an exposure process during the manufacture of semiconductor memories such as VLSIs.

[Prior Art] FIG. 2 is an explanatory diagram showing a schematic configuration of the main parts of the conventional illumination optical device and the present invention, which are used, for example, in the exposure process in manufacturing the above semiconductor memory, and 20 is a lamp house. , this lamp house 20 includes a lamp 1 as a light source, a condensing mirror 2 that collects the light from the lamp 1, an integrator section 4, reflectors 3 and 5, a condenser lens 6, and monitors the irradiance of the light from the light source. The radiation is provided by an illuminance monitor 7, and the effective light beam (light beam used for exposure) output from this lamp house 20 is transmitted to a mask pattern (hereinafter referred to as a reticle) 8 as an original image and the light from this reticle 8 to an exposed object. The light passes through an imaging lens 9 for forming an image, and is irradiated onto the exposure surface 10 of the object to be exposed.

In the illumination optical device shown in FIG. 2, light from a lamp 1 passes through a condensing mirror 2, a reflecting mirror, an integrator section 4, a reflecting mirror 5, a condenser lens 6, a reticle 8, an imaging lens 9, and a silicon An image is formed on the exposure surface 10 of an object to be exposed, such as a wafer.

In addition, FIG. 3a shows the integrator section 4 of FIG.
FIG. 1B is a plan view of the aperture shown in FIG. 1A and the member in which it is formed.

In FIGS. 3a and 3b, 42 is a bandpass filter that transmits only light at a specific wavelength (for example, 436 nm) and its vicinity in order to maintain monochromaticity and increase the resolution of the reticle 8, and 43 is a mixer lens. 4
An input lens 44 has a function of aligning the angle of light incident on each of the rod lenses 4, and 44 is composed of a plurality of rod lenses.
A mixer lens (also called a fly's eye lens) 45 is used to divide the light emitted from each rod lens by each rod lens, and the light emitted from each rod lens is overlapped and added to form a uniform illuminance distribution. Reticle 8 for each light
An output lens 46 is an imaging lens 9 to prevent misalignment when superimposed on the surface of the image forming lens 9.
This is a member in which an aperture is formed to regulate the amount and range of light that enters the entrance pupil of the lens. Then, depending on the diameter A of the image at the entrance pupil of the imaging lens 9 of this aperture and the diameter B of the entrance pupil of the imaging lens 9,
A sigma value (B/A) is determined. This sigma value is determined by the imaging performance and throughput of the imaging lens 9, and is generally used in the range of 0.5 to 0.8.

In the configurations shown in FIGS. 2 and 3, the light from the reflecting mirror 3 passes through a low-cut filter 41 and a band-pass filter 42, and only the light with wavelengths in a desired band passes through an input lens 43 to a mixer lens 4.
4. As a result, the exposure surface 10 is irradiated with only a narrow band of light having a specific wavelength of the bandpass filter 42, and an image is formed. Here, if the imaging performance of the imaging lens 9 is far from the optical axis and can be used in a partial peripheral area, or if the resolution does not need to be so high, a light beam with a large diameter is made incident on the entrance pupil to increase the throughput. If the properties in the peripheral area of the image lens 9 are not good or if resolution is a priority, reduce the diameter of the light beam incident on the entrance pupil and use only the area near the optical axis with good imaging performance. There is.

Therefore, a large number of apertures of various diameters are arranged in the form of a bookmark as shown in FIG. 3b, and the apertures are replaced as appropriate by being pulled out or inserted.

[Problems to be solved by the invention] As mentioned above, in the conventional illumination optical device,
It is necessary to change the diameter of the aperture depending on the resolution and throughput of the imaging lens for the object to be exposed. Therefore, this is done by replacing the member with the aperture formed with another member with the aperture formed, but when replacing the aperture, in the case of the bookmark type described above, the center of the aperture and the optical axis do not match. There was a problem of so-called eccentricity. If the aperture is eccentric, for example, in the case of exposure for manufacturing 1M bit class semiconductor memory, ultra-fine processing technology on the order of a few thousandths of a micron is required, so deviation or blurring of the aperture image due to eccentricity can also cause exposure defects. There was a problem that this could lead to the occurrence of defective products.

Further, in the case of the conventional bookmark type aperture replacement system, there was a problem in that dirt such as dust and dirt adhered to the output lens due to sliding of the member in which the aperture was formed.

This invention was made to solve this problem, and when the aperture forming member is replaced in order to change the diameter of the aperture, there is no problem that the center of the aperture and the optical axis become mismatched due to this operation. Another object of the present invention is to provide an illumination optical device having an integrator section that does not inevitably generate dust adhering to an output lens during replacement.

[Means for solving the problem] In order to achieve the above purpose, the first aspect of this application
In the third invention, the integrator section has a structure in which an input lens, a mixer lens, and an aperture unit are arranged in the order of incidence of light, and the aperture unit houses an output lens. In a second invention, the integrator section has a structure in which an input lens, a mixer lens, an aperture in an aperture unit, and an output lens are arranged in the order of incidence of the light. This invention has a configuration that combines the first invention and the second invention.

[Function] With the above configuration, the output lens is already positioned within the aperture unit according to the first invention, so that it is also positioned with the aperture. As a result, there is no mismatch between the center of the aperture and the optical axis, and since only the part where the aperture is formed is not slid, dust and dirt generated during aperture replacement are eliminated and adhered to the output lens. You can reduce garbage.

Also, according to the second invention, the aperture is
It is placed closer to the output surface of the mixer lens than the output lens. Therefore, an aperture image can be formed on the entrance pupil of the imaging lens with less blur.

Furthermore, according to the third invention, the effects of both inventions can be achieved by combining the first invention and the second invention.

[Embodiment] Fig. 1 is a cross-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 device that transmits only light at a specific wavelength and its vicinity. A transparent bandpass filter (BPF), 18 is a mixer lens frame that is fitted into the lens barrel 11 and is removable, 19 is a translucent sealing plate for preventing dust from entering the mixer lens frame 18, 21
is mixer lens, 22 is this mixer lens 2
1, an aperture unit 220 is an aperture portion of the aperture unit; 23 is an aperture unit installed on the output side of the aperture 220; The aperture 220 and the output lens 23 are attached and assembled as one unit.

The present invention applies the integrator section shown in FIG. 1 to the integrator section 4 of the illumination optical device shown in FIG. Now, in the apparatus shown in FIG. 2, when it is desired to change the diameter of the aperture, the aperture unit 22 consisting of a set of an aperture 220 and an output lens 23 incorporated in the mixer lens frame 18 shown in FIG.
The aperture unit can be removed and replaced with an aperture unit having an aperture of a different diameter. During this exchange, the center position of the aperture 220 has been positioned and incorporated in advance when assembling the output lens 23 as a unit, so all you have to do is replace these sets and attach them to the mixer lens frame, and the center position of each aperture 220 can be adjusted. They match, so there is no need to worry about eccentricity. That is, in order to attach them to the mixer lens frame 18, a plurality of pairs of aperture units 22 and output lenses 23 having different diameters of apertures 220 but the same outer diameter are prepared in advance. Since the centers of the output lens 23 and aperture unit 22 in this set are aligned, there is no need to worry about eccentricity by just attaching it to the mixer lens frame 18.

Furthermore, replacement is completed simply by fitting the aperture unit 22. That is, unlike the conventional bookmark type aperture exchange system, there is no possibility of dust and dust being generated due to sliding of a member having an aperture. Therefore, the amount of dust adhering to the output lens can be greatly reduced.

Furthermore, conventionally the mixer lens, output lens, and aperture were arranged in that order, but
In this invention, the mixer lens 21, the aperture 220, and the output lens 23 are arranged in this order.

Therefore, the aperture is arranged closer to the exit surface of the mixer lens 21, which is in a coupling relationship with the entrance pupil of the imaging lens, than the output lens. Thereby, an image of the aperture can be formed on the entrance pupil of the imaging lens with a reduced amount of blur.

[Effects of the Invention] As explained above, according to the first aspect of the present invention, the output lens is already positioned within the aperture unit, so that it is also positioned with the aperture. As a result, there is no mismatch between the center of the aperture and the optical axis, and since only the part where the aperture is formed is not slid, dust and dirt generated during aperture replacement are eliminated and adhered to the output lens. You can reduce waste.

Also, according to the second invention, the aperture is
It is placed closer to the output surface of the mixer lens than the output lens. Therefore, an aperture image can be formed on the entrance pupil of the imaging lens with less blur.

Furthermore, according to the third invention, by combining the first invention and the second invention, the effects of both inventions can be achieved.

[Brief explanation of drawings]

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 configuration of the main parts of the conventional illumination optical device used in the exposure process of the semiconductor device and in the present invention. FIG. 3a is an explanatory diagram showing details of the integrator section 4 in FIG. 2, and FIG.
FIG. In the figure. 1: lamp, 4: integrator section,
3, 5: Reflector, 6: Condenser lens, 8: Reticle, 9: Imaging lens, 13: Input lens, 16: BPF, 18: Mixer lens frame, 21: Mixer lens, 22: Aperture unit, 220 :Aperture, 23:Output lens.

Claims (1)

[Claims] 1. In an illumination optical device having a light source and an integrator section, the integrator section is arranged in the order of incidence of light as an input lens, a mixer lens, and an aperture unit, and the aperture unit is arranged in the order of incidence of light. An illumination optical device characterized by housing an output lens. 2. An illumination optical device having a light source and an integrator section, characterized in that the integrator section is arranged in the order of light incidence: an input lens, a mixer lens, an aperture in an aperture unit, and an output lens. . 3. The illumination optical device according to claim 2, wherein the aperture and the output lens are housed in an aperture unit.