JP3254771B2 - X-ray reduction projection exposure apparatus and method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an X-ray reduction projection exposure apparatus used for X-ray lithography.

[0002]

2. Description of the Related Art In recent years, with the miniaturization of semiconductor integrated circuit elements, X-rays having a shorter wavelength than ultraviolet rays have been used instead of conventional ultraviolet rays in order to improve the resolution of an optical system limited by the diffraction limit. Reduction projection lithography techniques have been developed. The exposure equipment used for this technology is
As shown in FIG. 2, the apparatus comprises an X-ray source 1, an illumination optical system 2, a reflection mask 3, a reduction projection optical system 4, and a wafer 5. A radiation light or a laser plasma X-ray source is used as the X-ray light source 1. The illumination optical system 2 includes a grazing incidence mirror or a multilayer mirror, a filter, and the like, and extracts X-rays of a desired wavelength from X-rays generated by the light source 1 and illuminates a necessary range on the reflection mask 3. It is.

[0003] In X-ray reduction projection lithography, a reflection mask is used in which a pattern is formed by providing a low-reflectance portion on a multilayer film that reflects X-rays. Since there is no transparent substance in the wavelength region of X-rays, in order to fabricate a transmission type mask similar to the conventional one, a self-standing film (membrane) made of a substance having a small absorption of X-rays such as silicon nitride is used. A fine pattern must be formed. In order to suppress the absorption of X-rays by the membrane, its thickness must be about 0.1 μm or less, so that it is difficult to manufacture a large-area mask with this structure. On the other hand, in the case of a reflective mask, a pattern is formed on a thick substrate, so that the area can be easily increased. For these reasons, the X-ray reduction projection exposure apparatus uses a reflection type mask instead of a transmission type mask.

In FIG. 2, X reflected by a reflection mask 3 is shown.
The lines are imaged on the wafer 5 by the reduction projection optical system 4 including a plurality of multilayer mirrors, and the mask pattern is reduced and transferred onto the photoresist applied to the wafer 5. X-rays used in such an X-ray reduction projection exposure apparatus have wavelengths of 10 to 10 at which high reflectivity is obtained by a multilayer reflector.
This is a so-called soft X-ray of 200 angstroms. Since soft X-rays are absorbed and attenuated in the atmosphere, all optical paths of the X-ray reduction projection exposure apparatus are kept in a vacuum.

[0005]

In the above-described conventional X-ray reduction projection exposure apparatus, the X-rays incident on the reflection mask are specularly reflected such that the incident angle and the reflection angle are equal to each other. In order to prevent interference between the projection optical system and the reduction projection optical system, the light beam illuminating the reflection mask must be incident not obliquely but obliquely on the reflection mask. Therefore, the light beam reflected by the reflection mask cannot travel in the normal direction of the reflection mask, but travels in a direction inclined by a certain angle with respect to the normal of the reflection mask.

On the other hand, the reduction projection exposure apparatus needs a mechanism for performing parallel movement of both the reflection mask and the wafer in the optical axis direction of the reduction projection optical system for focusing.

However, in the conventional X-ray reduction projection exposure apparatus, as shown in FIG. 2, in order to perform focusing, the reflection mask 3 is moved from position A to position A ′ in parallel with the optical axis of the reduction projection optical system 4. In this case, the principal ray 7 of the X-rays reflected by the reflection mask 3 moves in parallel from the position B to the position B 'indicated by the broken line, and thus there is a problem that the illuminated area on the reflection mask 3 changes. . Furthermore, since the principal ray 7 of the X-ray incident on the reduction projection optical system 4 is shifted from the optical axis of the reduction projection optical system 4, there is a problem that the resolving power is reduced.

It is an object of the present invention to provide an X-ray reduction projection exposure apparatus in which a reflected X-ray principal ray does not move even when a reflection mask is moved for focusing.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described with reference to FIG. 1 showing the configuration of an embodiment. The invention of claim 1 is directed to an X-ray source 1 and an X-ray emitted from the X-ray source 1. Optical system 2 for irradiating light onto reflection mask 3, reduction projection optical system 4 for projecting and forming an image of a pattern formed on reflection mask 3 on wafer 5, X-ray source 1, illumination optical system 2 , A reflection mask 3, a reduction projection optical system 4, and a vacuum container for holding the wafer 5 in a vacuum space. Immediately before or immediately after the reflection mask 3 on the optical path of the X-ray, the bending mirror 8 facing in parallel with the reflection mask 3, and holding the reflection mask 3 and the bending mirror 8 to hold the reduction projection optical system 4 Stage 9 movable parallel to the optical axis
To achieve the above object. In addition,
The X-ray reduction projection exposure apparatus according to claim 2 is connected to the reduction projection optical system 4.
When the principal ray of the incident X-ray and the optical axis of the reduction projection optical system 4 are
It is made to match. The invention according to claim 3 is based on X
X-rays emitted from the radiation source 1 are made incident on the illumination optical system 2,
The X-rays emitted from the illumination optical system 2 are projected onto a reflection mask 3.
Irradiates the image of the pattern formed on the reflection mask 3
The X-rays reflected by the projection optical system 4 are incident on the projection optical system 4,
X-rays emitted from the optical system 4 are projected and imaged on the wafer 5
Manufacture of a wafer with an exposed pattern, including an exposure process
Apply to the method. Then, the light enters the projection optical system 4.
A step of matching the principal ray of the X-ray to the optical axis of the projection optical system 4
Have. According to the invention of claim 4, X-rays emitted from the X-ray source 1
A line is used as a reflection mask having a pattern formed through the illumination optical system 2.
Irradiates the disk 3 and reduces the X-rays reflected by the reflective mask 3
Projection image is formed on the wafer 5 via the small projection optical system 4, and the wafer
The method is applied to an X-ray reduction projection exposure method for exposing C5. So
When the image of the pattern is projected and formed on the wafer 5,
Principal ray of X-ray incident on small projection optical system 4 and reduction projection optics
When the optical axis of the system 4 does not match, the two are matched and projected.
Make an image.

[0010]

In the X-ray reduction projection exposure apparatus according to the present invention, the chief ray emitted from the illumination optical system 2 is reflected by the bending mirror 8 and the reflection mask 3 which are installed in parallel and opposed to each other to reduce the projection light. The light enters the system 4. Therefore, the principal ray emitted from the illumination optical system 2 and the principal ray incident on the reduction projection optical system 4 are parallel to each other. The bending mirror 8 and the reflection mask 3 are set on the same stage 9, and the stage 9 moves parallel to the optical axis of the reduction projection optical system 4. Even if the distance between the projection optical system 3 and the reduction projection optical system 4 is changed, the principal ray incident on the reduction projection optical system 4 does not move.

In the means and means for solving the above-mentioned problems which explain the constitution of the present invention, the drawings of the embodiments are used to make it easier to understand the present invention. However, the present invention is not limited to this.

[0012]

FIG. 1 is a diagram showing a schematic configuration of an embodiment.
It should be noted that the same devices as those in the conventional device shown in FIG. In this embodiment, a bending mirror 8 for changing the direction of light rays in parallel with the reflection mask 3 is provided at a position facing the reflection mask 3, and the reflection mask 3 and the bending mirror 8 are installed on a translation stage 9. I do. The translation stage 9 can be moved in parallel with the optical axis of the reduction projection optical system 4 by a mechanism (not shown). The light source 1, the illumination optical system 2, the reflection mask 3, the reduction projection optical system 4, the wafer 5, the bending mirror 8, and the translation stage 9 are housed in a vacuum vessel (not shown).

X-rays emitted from the light source 1 enter the bending mirror 8 via the illumination optical system 2. The light beam reflected by the bending mirror 8 is reflected by the reflection mask 3 and then enters the reduction projection optical system 4. At this time, since the bending mirror 8 and the reflection mask 3 are installed in parallel and opposed to each other, the direction of the principal ray 6 of the X-ray emitted from the illumination optical system 2 and the direction of the bending mirror 8 and the reflection mask 3 are different. The directions of the principal rays 7 of the X-rays that are reflected and enter the reduction projection optical system 4 are parallel to each other. Here, the principal ray 7 of the X-ray incident on the reduction projection optical system 4 is adjusted in advance so as to coincide with the optical axis of the reduction projection optical system 4.

In this X-ray reduction projection exposure apparatus, the reflection mask 3 and the reduction projection optical system 4 are used to adjust the focal position.
Is changed, the translation stage 9 is moved, for example, from position A in the figure to position A '. Since the translation stage 9 moves in parallel with the optical axis of the reduction projection optical system 4, even if the translation stage 9 moves to the position A ', the principal ray 7 incident on the reduction projection optical system 4 does not move.

In this embodiment, the reflection mask 3 is arranged after the bending mirror 8, but this order may be reversed.

[0016]

As described above, according to the present invention, X
A folding mirror that faces parallel to the reflection mask immediately before or immediately after the reflection mask on the optical path of the line, and a stage that can hold the reflection mask and the folding mirror and move parallel to the optical axis of the reduction projection optical system. With this arrangement, even if the reflection mask is moved in the direction of the optical axis, the principal ray of the X-ray incident on the reduction projection optical system becomes immobile, so that a certain area on the reflection mask can always be illuminated and a stable resolving power can always be obtained. Can be Also,
An X-ray reduction projection exposure apparatus generally employs a so-called Koehler illumination in which an image of a light source by an illumination optical system is formed on an entrance pupil plane of the reduction projection optical system in order to ensure uniformity of illumination light intensity on a mask. Used. According to the present invention, as is apparent from FIG. 1, even if the translation stage 9 is moved, the distance from the exit pupil of the illumination optical system 2 to the reduction projection optical system 4 does not change, so that the Koehler illumination condition does not change. effective. Further, in the conventional X-ray reduction projection exposure apparatus shown in FIG. 2, since the light source 1, the illumination optical system 2, and the reduction projection optical system 4 are all disposed on the same side with respect to the reflection mask 3, they interfere with each other. However, there are many restrictions on arrangement and a large installation space is required. On the other hand, according to the present invention, as shown in FIG. 1, the entire optical system can be arranged in one elongated line, so that the installation space can be reduced. In particular, when using radiated light as a light source, a number of beam lines are radially installed on the radiated light ring, and each beam line is equipped with one X-ray reduction projection exposure apparatus. The fact that the apparatus can be configured in an elongated line shape as in the present invention means that a large number of X-ray reduction projection exposure apparatuses can be installed in one radiation light ring, and the utilization efficiency of the light source is increased, and as a result, ,
The cost of the light source can be relatively reduced.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of one embodiment.

FIG. 2 is a diagram showing a configuration of a conventional X-ray reduction projection exposure apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 X-ray source 2 Illumination optical system 3 Reflection mask 4 Reduction projection optical system 5 Wafer 6,7 Principal ray 8 Bending mirror 9 Translation stage

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-63-62231 (JP, A) JP-A-2-174111 (JP, A) JP-A-3-4200 (JP, A) JP-A-5-205 343283 (JP, A) JP-A-63-219125 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01L 21/30 531 A G03F 7/20 503

Claims (4)

(57) [Claims] 1. An X-ray source, an illumination optical system for irradiating an X-ray emitted from the X-ray source onto a reflective mask, and a reduction image for projecting an image of a pattern formed on the reflective mask onto a wafer An X-ray reduction projection exposure apparatus comprising: a projection optical system; and an X-ray source, the illumination optical system, the reflection mask, the reduction projection optical system, and a vacuum container that holds the wafer in a vacuum space. Immediately before or immediately after the reflection mask on the optical path, a bending mirror facing in parallel with the reflection mask, and holding the reflection mask and the bending mirror in parallel with the optical axis of the reduction projection optical system. An X-ray reduction projection exposure apparatus, comprising: a movable stage. (2) 2. The X-ray reduction projection exposure apparatus according to claim 1,
And The principal ray of X-rays incident on the reduction projection optical system and the reduction
X-rays having the same optical axis as the projection optical system
Reduction projection exposure equipment. (3) X-rays emitted from X-ray source to illumination optics
X-rays emitted from this illumination optical system
Pattern on the reflective mask
The X-rays reflected by the image of
A dew that projects and forms X-rays emitted from the shadow optical system on the wafer.
Manufacturing method of exposed wafer with patterning process
In the law, The X-ray principal ray incident on the projection optical system is the projection light
Characterized by having a process to match the optical axis of the academic system
Wafer manufacturing method. (4) X-rays emitted from an X-ray source can
Illuminate the patterned mask through the reflective mask
X-rays reflected by the reflection mask are transmitted through a reduction projection optical system.
X-ray reduction for projecting an image on a wafer and exposing the wafer
In the small projection exposure method, When projecting an image of a pattern on the wafer,
X-ray chief ray incident on the small projection optical system and the reduced projection light
When the optical axis of the academic system does not match, the two are matched and projected.
An X-ray reduction projection exposure method comprising forming an image.