JPS6323319A - Methofd for projection exposure - Google Patents

Abstract

PURPOSE:To selectively project and expose the first and second patterns formed on the first object onto the second object by a device wherein light-shading plates are moved independently from one another and the shape of an opening through which a light flux coming from a light source passes can be changed. CONSTITUTION:The plane of an opening 35 is situated on the same plane as a light-shading surface A at a light-shading device 18. Regarding the moving direction of four light-shading plates 34 the first and second light-shading plates move in the identical direction, while the third and fourth light-shading plates move in the identical direction. The moving direction of the first and second plates is not identical in relation to that of the third and fourth plates. Four motors 31 are installed on each plate for moving each light-shading plate 34 independently from one another. Through this arrangement, the first and second patterns formed on the first object can be projected and exposed selectively onto the second object. When, for example, the second object like a wafer is exposed through the first object like a reticle, plural different patterns can be projected and exposed efficiently onto the second object.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a projection exposure method, and particularly to a method of projecting and exposing a pattern formed on a reticle (photomask) onto a wafer in the field of semiconductor manufacturing.

[Conventional technology]

In the field of manufacturing semiconductor devices (eg, IC1LSI, VLSI, etc.), a projection exposure apparatus called a stepper is known. The stepper projects the pattern on the reticle onto the wafer at a predetermined reduction ratio, arranges the pattern over the entire surface of the wafer using step-and-repeat B light, and then
J, a few are burned.

[Problem that the invention seeks to solve]

By the way, when printing a reticle pattern on a wafer,
Rather than repeatedly printing the same pattern over the entire surface of the wafer, other patterns may be printed in the middle. Conventionally, in such cases, it has been difficult to efficiently print a plurality of different patterns onto the wafer.

The present invention has been made in view of the above circumstances, and its purpose is to expose a second object, such as a wafer, through a first object, such as a reticle, to expose a second object, such as a wafer, to a plurality of different patterns. It is an object of the present invention to provide a method for exposing images that can be projected and exposed efficiently.

(Means for Solving Problem #1) To achieve this objective, the present invention incorporates light from a light source into an illumination optical path for exposing a second object through a first object with light from the light source. The first object is formed by arranging a plurality of light shielding plates for blocking light, moving each of the light shielding plates independently, and making variable the shape of the opening through which the light from the light source passes. The gist is to selectively project and expose the first and second patterns on the second object.

(Examples) Hereinafter, the present invention will be described in detail based on illustrated examples.

FIG. 1 shows an example of an illumination system of a projection exposure apparatus (for example, a stepper) according to the present invention.
The circuit pattern 22a formed on the lower surface B of 2 is printed with light. Although not shown in this figure, a reduction projection lens and a wafer are arranged below the reticle 22 in this order.

An elliptical mirror 12 is arranged near the light source +1 such as an ultra-high pressure mercury lamp to effectively condense the luminous flux emitted from the light source 11, and then sequentially along the optical path transmits most of the infrared light and converts it into ultraviolet light. A cold mirror 13 for reflecting light, an integrator 14 for making the distribution characteristics of the luminous flux uniform, a reflector 15, a condenser lens 16, a reflector I7, a light shielding device 18, a condenser lens 19, a reflector 20, a condenser lens. 21, a reticle 22 is arranged. Reflector+
5, 17, and 20 are for making the illumination system smaller by bending the optical axis at right angles, and the condenser lens 16
is for condensing the light from the light source 11 and uniformly illuminating the light shielding surface A of the light shielding device 18.

FIG. 3 is a perspective view of the light blocking device 18. This light shielding device 1
8 is a condenser lens 19, 21 as shown in FIG.
It is arranged so that it has a conjugate relationship with. Further, the light shielding device 18 is driven by a light shielding device drive mechanism (not shown) to the circuit pattern portion 22a of the reticle 22 or the reticle 22.
Wafer to be exposed (not shown) placed below
In order to align the rotational direction with the reticle 22, it can be rotated in the rotational (θ) direction shown by the arrow in FIG. 2(a) in conjunction with the rotation of the reticle 22. In order to maintain the above conjugate relationship when the reticle is replaced with a reticle with a different thickness of the transparent part and the refractive power changes, the first
It is movable in the optical axis direction indicated by the arrow in the figure.

Returning to FIG. 3 to explain the configuration of the light shielding device 18, on the board 30 are a motor 31, a feed screw portion 32 which is fixed to the rotation shaft of the motor 31 and rotatable, and a motor 31 and a feed screw portion 32. A feed nut portion 33 and a feed nut portion 3 that are movable in a predetermined direction (in the direction of the arrow in the figure) by rotation.
Four sets of light shielding plates 34 each having a sharp side edge 34a are arranged, and the four side edges 34a form a rectangular opening 35. The surface of this opening 35 is on the same plane as the light shielding surface A of the light shielding device 18. In addition, as is clear from FIG. 3, four light shielding plates 34
Of these, the moving direction of the first and second light shielding plates and the moving direction of the third and fourth light shielding plates are respectively the same;
The moving directions of the third and fourth light shielding plates with respect to the moving direction of the light shielding plate are different. Moreover, the third and fourth light shielding plates are arranged on the same side as the first and second light shielding plates. Four motors 31 are provided independently for each light shielding plate 34.

In FIG. 1, a light beam emitted from a light source 1 is transmitted through optical elements 12, 13 . Reflected in the order of +4.15.16.17,
The light is refracted and uniformly illuminates the surface A of the light shielding device 18. The light beam irradiated to the outside of the aperture 35 of the light shielding device 18 is blocked by the four light shielding plates 34, and the light beam that has passed through the aperture 35 hits the pattern surface B of the reticle 22, as shown by the dotted line in FIG. illuminate. Here, since the light shielding surface A of the light shielding device 18 and the pattern surface B of the reticle 22 are arranged in an optically conjugate relationship, the edge of the opening 35 of the light shielding device 18 is as shown in FIG. 2(b). As shown by the dotted line, a clear outline is projected onto the pattern surface B, and the area outside the circuit pattern portion 22a of the reticle 22 can be completely shielded from light.

Furthermore, the area and position of the opening part 35 of the light shielding device 18 are as follows:
A projection exposure apparatus equipped with this illumination system, for example, an electric f-processing part of a stepper, causes each of the four motors 31 to rotate in a predetermined manner in response to a signal generated by the size of the reticle 22. The four feed screws 32 connected to the shaft move the four feed nuts 33 in predetermined directions, and the four light shielding plates 34 are moved by the motors 31 to positions corresponding to the signals. It can change in the direction perpendicular to the optical axis. Such movement and adjustment of the four light shielding plates 34 can be performed simultaneously by the motor 3 provided for each light shielding plate 34.

Due to these, the circuit pattern portion 22a of the reticle 22
This makes it possible to provide lighting that matches the area. In other words, within the effective irradiation range of the illumination system? "By using the optical processing, it is possible to steplessly select the size, shape, and position of light shielding with respect to the reticle 22. Furthermore, as shown in FIG. 4(a), the light shielding device 1
8, by attaching two light shielding plates 34b of different shapes such as concave shapes, or by adding a new similar light shielding plate 34c in addition to the four light shielding plates 34, as shown in FIG. 4(b). , a non-rectangular circuit pattern on the reticle 22 can also be exposed by projection. In a stepper equipped with this illumination system, when printing, a circuit pattern and a test pattern are mixed in the reticle 22, and when printing a circuit pattern, the test pattern area is shielded from light and only the circuit pattern area is irradiated with printing light. Conversely, when printing a test pattern, it is also possible to shield the circuit pattern portion from light and apply the printing light only to the test pattern portion.

5(a) and 5(b) schematically show the structure of a projection exposure apparatus (for example, a stepper) having a light shielding plate 1 having the same purpose as the light shielding plate 34 of the light shielding device 18 in FIG. In these figures, 2 is the reticle, 3 is the reticle stage, and 4 is the reticle stage.
5 is a projection lens, 5 is a wafer, and in order to prevent 11 scratches on the circuit pattern 2a formed on the reticle 2, the light-shielding plate 1 is located above the reticle 2 in the optical axis direction. In addition, in FIG. 5(b), they are arranged below the reticle 2 at a distance b in the optical axis direction. Therefore, the light shielding plate 1 has a fifth
It is necessary to set the tip 1a so that it is separated by a distance of C1 from the area of the pattern 2a in FIG.

〔Effect of the invention〕

As described above, according to the present invention, the illumination range can be selectively and accurately determined for one of the first and second patterns formed on the first object, such as a reticle. Using such a first object, it is possible to selectively and efficiently project and expose the first and second patterns onto a second object such as a wafer.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the main parts of seven embodiments of the projection exposure apparatus of the present invention, and FIGS. 2(a) and (b) show the light shielding device of the present embodiment,
3 is a perspective view showing details of the light shielding device, FIGS. 4(a) and (b) are views showing modified examples of the light shielding device, and FIGS. 5(a) and (b) are diagrams showing the end faces of the reticle. ) is a diagram showing an example of a projection exposure apparatus each having a light shielding device. 18... Light blocking device 22... Reticle 34... Light blocking plate 35... Opening A... Light blocking surface

Claims (1)

[Claims] (1) A plurality of light shielding plates for blocking light from the light source are arranged in an illumination optical path for exposing a second object through a first object with light from a light source, and each of the light shielding plates is independently arranged. selectively projecting and exposing the first and second patterns formed on the first object onto the second object by moving the first object and changing the shape of an aperture through which light from the light source passes; A projection exposure method characterized by: