JPS6037616B2 - X-ray lithography equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION X-ray lithography equipment is used for microfabrication when manufacturing solid-state devices such as semiconductor integrated circuits. A workpiece such as a wafer is irradiated with X-rays, and the wafer is coated with an X-ray resist, which is developed and etched.

In the above-described lithography apparatus, the amount of X-rays incident on the entire surface of the exposed object consisting of the processed object and the mask must be uniform. However, in a normal X-ray tube, the direction of the extracted X-rays is inclined with respect to the electron irradiation surface of the target, resulting in uneven X-ray intensity distribution. It had the disadvantage of being limited in size. The present invention seeks to obviate the above-mentioned drawbacks. FIG. 1 is a partially longitudinally sectional front view of an embodiment of the present invention. An electron gun consisting of an east electrode 4 and a thermionic emission cathode 5 disposed inside the east electrode 4 is arranged. That is, the electron beam e emitted from the cathode 5 is narrowed down to a diameter of, for example, a few millimeters by the action of the electrode 4, and is made to enter the electron irradiation surface 6 of the target.
An X-ray window 7 made of beryllium or the like is formed in the crab body wall at the side of the incident point. Therefore, a point x-ray source p is formed on the electron irradiation surface, and soft x-rays x are irradiated from this X-ray source through the window 7 in a conical shape. The electron irradiation surface 6 is formed in a planar shape perpendicular to the plane of the paper, and is inclined at 45 to 60 degrees with respect to the electron beam e or 30 to 45 degrees with respect to the axis of the X-ray x. An exposed object 8 is disposed outside the window 7 of the X-ray tube 1 as described above, and an X-ray shielding plate 10 is provided in front of the exposed object 8, which is driven by a drive device 9 in the direction of arrow y. These are arranged perpendicularly to the axis of the X-ray
They are about 0 mm apart. Therefore, the exposed object 8 is the electron irradiation surface 6
The shielding plate 10 is inclined in a plane including the plane of the paper, that is, in the direction of the inclination as shown by the arrow y.
It moves at an appropriate speed to block the X-rays incident on the object to be exposed 8. The exposed object 8 has an X-ray resist 1 on its surface.
For example, a mask 14 is placed on the front surface of a silicon wafer 12 coated with 1, via an annular spacer 13, and the mask has a mask pattern 15 of an X-ray absorber formed on the back surface of an X-ray transparent material. has been done. In the above-mentioned apparatus, for example, the X-ray tube 1 is opened with the shielding plate 10 open as shown by the solid line.
Exposure is performed by applying a high voltage to the X-ray source x and emitting radiation from the X-ray source x.

When the exposure time has elapsed, for example, 7 minutes, the drive device 9 moves the shielding plate 10 at an appropriate speed in the direction of the arrow y as shown by the dotted line to gradually block the X-rays x, starting from the start of the exposure. For example, after 10 minutes have elapsed, the X-rays incident on the exposed object 8 are completely blocked, and this operation makes the amount of X-rays incident on each part of the exposed object 8 almost uniform. be able to. Next, the principle will be explained. FIG. 2 is a longitudinally enlarged view of a part of the target 3 of the X-ray tube in FIG. .
Since most of this electron beam generates X-rays at a position that has penetrated into the target to some extent, it can be considered that the X-ray generating surface is located at a very small distance from the surface. If the X-rays generated at point R on the X-ray generation surface Q and incident on the right end of the exposed object 8 in FIG. d, passes through the target 3, and only the average passes through the target 3. And since the electron irradiation surface 6 is inclined with respect to the axis 0 of the X-ray x, the distance d
, d2 becomes larger than x, and the X-ray average receives a larger attenuation than x. Therefore, the X-rays incident on the right end of the exposed object 8 are stronger than the X-rays incident on the left end, resulting in non-uniformity in the intensity distribution. In Figure 3, an X-ray photosensitive plate is placed at the position of the exposed object 8 in Figure 1, and the entire surface is exposed to light for a certain period of time by keeping the shielding plate 10 open from beginning to end. A projected figure T of the window 7 appears on the plate S.

When this photosensitive plate S is placed on a microphotometer and scanned at three locations as indicated by y, , y2, and y3 in the direction parallel to the arrow y in FIG. 1, the degree of blackening 1 is measured.
Curves shown with the same symbols in the figure are obtained. Also, in the z direction perpendicular to the arrow y in FIG. 1, z. ,z2,z3
When three locations are scanned as shown in FIG. 5, a curve with a degree of blackening of 1 as shown in FIG. 5 by the same reference numeral is obtained. In other words, even with such measurements, it can be seen that the intensity distribution of the X-rays incident on the exposed object 8 in FIG. 1 is almost uniform in the z direction perpendicular to the page, but gradually decreases in the y direction of the arrow be proven. In addition, the axis ○ and the electron irradiation surface 6 in Fig. 2
The angle ◇ between is 30 degrees, the angle between the electron beam e and the electron irradiation surface is 60 degrees, and the angle between the X-rays x,, and the spread angle a of the X-rays is 15 degrees, When the material of the target 3 is silicon Si, the X-ray reinforcement ratio b/a in Fig. 4 is
When calculated based on actual measurements, the acceleration voltage of the electron beam e is 2
It is about 0.88 at 0KV and about 0.78 at 30KV. Further, the change in the intensity of X-rays in the z direction is only to a negligible extent as shown in FIG. Therefore, when exposing the object 8, if the shielding plate 10 is driven, for example, as described above, and the exposure time t of each part is adjusted as shown by the broken line in FIG. exposed to light. As described above, the present invention allows the entire surface of the object to be exposed to light to be exposed almost uniformly using a simple device, and therefore the object to be exposed can be made sufficiently large.

[Brief explanation of drawings]

Fig. 1 is a longitudinal cross-sectional view of an embodiment of the present invention, Fig. 2 is a longitudinally enlarged view of a part of Fig. 1 for explaining the principle of the invention, and Fig. 3 is an X-ray Figures 4 and 5, which show a photosensitive plate for measuring intensity distribution, are X-ray intensity distribution curves. In the figure, 1 is an X-ray tube, 3 is a radiation getter, 6 is an electron irradiation surface, 8 is an exposed object, 9 is a shielding plate driving device, and 1 is a shielding plate. Tsugufufujifugenshio/19 Ga 2 Kameji 3 Mouse

Claims (1)

[Claims] 1 Project an electron beam onto the electron irradiation surface of the target of the X-ray tube to form an X-ray source that can be approximately regarded as a point X-ray source, and use the X-rays irradiated from the X-ray source to The direction of the inclination is such that the X-rays are incident almost perpendicularly to a planar exposed object arranged to be inclined with respect to the plane, and at a speed such that the amount of X-rays incident on each part of the exposed object is approximately equal. An X-ray lithography apparatus characterized in that an X-ray shielding plate that moves is provided in front of the object to be exposed.