JPH0684760A - Formation of zonal luminous flux and illuminating optical device - Google Patents

Abstract

PURPOSE:To obtain a continuously variable zonal illuminating luminous flux so as to improve the contrast of an image forming lens in the illuminating system of a semiconductor exposing device. CONSTITUTION:A semiconductor exposing device is provided with a beam converter 31 which changes the size of a luminous flux and zonal luminous flux forming device 2 composed of two sets of convex conical reflecting mirrors 11 and 14 and two sets of concave reflecting mirrors 12 and 13 and the converter 31 can change the outside diameter of a zonal luminous flux. The mirrors 14 can continuously change the inside diameter of the zonal luminous flux. The contrast of an image forming lens 46 can be improved by illuminating a mask 45 by forming a secondary light source 43 of the zonal luminous flux and producing a zonal secondary light source image in the entrance pupil 47 of the lens 46.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an annular light flux forming method and an illuminating optical device for a mask pattern projection exposure apparatus used for manufacturing a semiconductor element such as an LSI.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 8, an illumination optical apparatus in a mask pattern projection exposure apparatus used for manufacturing a semiconductor element uses a mercury lamp or an excimer laser as a light source 51 and a light beam 52 from the light source 51 as a lens. A light beam of an appropriate size is collimated at 53, the light amount distribution is made uniform by an optical integrator 42 composed of a minute lens array, and the mask 45 is illuminated by the illumination lens 44 using a plurality of point light sources as secondary light sources. As such an example, there is Japanese Patent Publication No. 4-13686.

The illuminated mask is projected onto the wafer surface by an imaging lens. This illumination system is Koehler illumination that creates an image of the secondary light source formed at the focal position of the optical integrator 42 on the entrance pupil of the imaging lens, and the shape of the secondary light source image that can be formed on the entrance pupil of the imaging lens. It is known that the imaging performance is improved by changing the.

In the conventional illumination optical device shown in FIG. 8, in order to obtain the annular illumination light, annular light shielding plates are inserted before and after the lens 53 or before and after the optical integrator 42.

[0005]

In the above-described conventional illumination optical device, as shown in FIG. 8, in order to obtain the annular illumination light, annular light shielding plates are provided before and after the lens 53 or before and after the optical integrator 42. Since the structure is such that it is inserted, light beams other than the annular light beam are cut, and there is a problem in that there is a large amount of light loss.

Further, when changing the shape of the ring zone, the light-shielding plate must be replaced, which complicates the operation and cannot change the shape continuously.

[0007]

According to the method of forming a ring-shaped light flux of the first aspect of the present invention, the first and second convex reflecting mirrors and the first and second concave reflecting mirrors have the same optical axis, A light flux incident on the first convex reflecting mirror is reflected by the first convex reflecting mirror and is reflected by the second convex reflecting mirror via the first concave reflecting mirror. Then, by moving the second convex reflecting mirror in the optical axis direction of the outgoing light flux, the shape of the ring zone of the outgoing light flux is made variable, and the first convex reflecting mirror The diameter of the incident light flux is varied to independently vary the inner and outer diameters of the annular zone of the light flux emitted from the second convex reflecting mirror.

The annular light flux forming device of the second aspect of the present invention includes a first convex reflecting mirror for reflecting an incident light flux from a light source in an annular shape in a direction substantially 90 degrees with respect to the optical axis of the incident light flux. A first concave reflecting mirror that reflects the annular light flux reflected from the first convex reflecting mirror in a direction parallel to the optical axis of the incident light flux, and the annular light flux reflected from the first concave reflecting mirror. A second concave reflecting mirror that reflects light in the opposite direction parallel to the optical axis of the incident light beam, and the annular light beam reflected from the second concave reflecting mirror is the same as the optical axis of the reflected light beam of the incident light beam. A second convex reflecting mirror which emits light in the same direction as the optical axis and whose center is movable in the optical axis direction of the incident light beam;
The convex reflecting mirror is a convex conical reflecting mirror or a convex polygonal pyramid polygonal mirror, and the concave reflecting mirror is a concave conical reflecting mirror or a concave polygonal pyramid polygonal mirror.

The illumination optical device according to the third aspect of the present invention is the first optical device for forming the annular light flux forming device for forming the light flux supplied from the light source into the annular light flux and the secondary light source for the annular light flux. An element and a second optical element for illuminating the surface to be illuminated based on the light flux from the secondary light source, and the inner and outer diameters of the annular light flux emitted from the annular light beam shaping device are independent. It has a light flux changing means for changing.

[0010]

According to the present invention, in an illumination optical device of a semiconductor exposure apparatus, a ring-shaped light flux forming device capable of varying the light flux size is installed in front of a first optical element forming a secondary light source. A secondary light source is formed by a band-shaped light beam, and an object to be illuminated is illuminated to improve the resolution of the optical system.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described with reference to the drawings.

FIG. 1 is a diagram showing a semiconductor exposure apparatus to which an embodiment of the first, second and third inventions is applied.

In FIG. 1, the semiconductor exposure apparatus of this application example is a light source 41, and a light flux from the light source 41 whose light path is changed by a mirror 30 illuminates a mask 45. Illumination optical device 1 and illumination optical device 1 for projecting the circuit pattern of the mask 45 onto the wafer 48.
And an imaging lens 46 that converges the light flux from the.

Illumination optical device 1 according to one embodiment of the third invention
Is an annular light flux forming device 2 of one embodiment of the first and second inventions for forming the light flux from the beam converter 31 into an annular light flux.
An optical integrator 42 that makes a secondary light source 43 in a ring shape on the focal plane of the light flux from the annular light flux forming device 2 and an illumination lens 44 for illuminating the light flux from the secondary light source 43 to the mask 45 are provided. I am configuring.

FIG. 2 shows an embodiment of the first and second aspects of the present invention, which shows an annular luminous flux forming device, wherein (a) shows a case where the diameter of the annular luminous flux is minimized, and (b) shows the annular luminous flux. It is a figure which shows the case where the diameter of a strip | belt-shaped light beam is maximized.

1 and 2, the annular zone light flux forming apparatus 2 of this embodiment has a convex conical reflecting mirror 11 for reflecting the light flux 10 incident in parallel from the beam converter 31 to the left and right, and a convex conical reflector. The same shape as the concave conical reflecting mirror 12 having a reflecting surface parallel to the reflecting surface of the mirror 11, and the concave conical reflecting mirror 12 for similarly reflecting the light beam reflected from the concave conical reflecting mirror 12 in the annular shape in the annular shape. Concave conical reflecting mirror 13 and a convex conical reflecting mirror 14 for emitting the annular luminous flux reflected from the concave conical reflecting mirror 13 as an annular luminous flux in a direction parallel to the incident luminous flux 10.
And is configured.

The convex conical reflecting mirror 14 is shown in FIG.
As shown in (b), it is possible to move in the A and B directions, the diameter of the annular light flux reflected when moving in the A direction becomes small, and the annular light flux reflected when moving in the B direction. The diameter of the light flux increases, and the width of each zone remains unchanged.

Next, the operation of the annular light flux forming apparatus of this embodiment will be described with reference to FIGS.

The parallel luminous flux 10 incident on the convex conical reflecting mirror 11 is reflected radially by the convex conical reflecting mirror 11. The luminous flux reflected radially is reflected in a ring shape by the concave conical reflecting mirror 12 having a reflecting surface parallel to the reflecting surface of the convex conical reflecting mirror 11. The ring-shaped light flux is reflected by the concave reflecting mirror 13 having the same shape as the concave reflecting mirror 12, and enters the convex reflecting mirror 14. The light beam incident on the convex reflecting mirror 14 is reflected and emitted as a ring-shaped light beam in a direction parallel to the incident light beam 10. At this time, if the distance between the concave conical reflecting mirror 13 and the convex conical reflecting mirror 14 is similar to the distance between the convex conical reflecting mirror 11 and the concave conical reflecting mirror 12 as shown in FIG. The inner diameter of the annular light flux is small. If the concave conical reflecting mirror 13 and the convex reflecting mirror 14 are close to each other, the inner diameter and the outer diameter of the emitted annular light flux increase. FIG. 2B is a diagram showing that state. By moving the convex reflecting mirror 14 in a direction parallel to the incident light beam, the size of the emitted light beam can be changed.

FIG. 3 is a diagram showing a method of changing the inner diameter of the annular light flux and the outer diameter thereof independently in this embodiment.

Next, a method of independently changing the inner diameter and the outer diameter of the annular light flux of the annular light flux forming apparatus of this embodiment will be described with reference to FIG.
This will be described with reference to FIGS. 2 and 3.

The light beam whose size has been converted by the variable-magnification beam converter 31 is a ring-shaped light beam composed of two sets of convex conical reflecting mirrors 11 and 14 and two sets of concave conical reflecting mirrors 12 and 13. The light enters the forming device 2 and is emitted as a ring-shaped light flux. As described above, the annular shape of the emitted light beam has a convex conical reflecting mirror 14.
Can be changed by moving in the direction of the optical axis, but the inner diameter and the outer diameter simultaneously change by the same amount. Further, by changing the size of the incident light beam with the variable-magnification beam converter 31, it is possible to change the outer diameter of the emitted light beam. That is, the inner diameter of the emitted light beam can be changed by the movement of the convex conical reflecting mirror 14, and the outer diameter of the emitted light beam can be changed by the variable-magnification beam converter 31 installed on the incident side. It is possible to obtain independently variable annular light fluxes without blocking the light fluxes.

In FIG. 3, a beam compressor is used as the beam converter 31 on the incident side to reduce the luminous flux and make it incident on the annular zone shape forming device 2. However, after the luminous flux is enlarged by the beam expander, the annular zone is formed. It may be incident on the shape forming device 2. Further, even if a beam compressor or a beam expander that is the beam converter 31 is installed on the exit side of the ring shape forming device 2, the same effect can be obtained. Further, the two sets of convex conical reflecting mirrors 11 and 14 and the two sets of concave conical reflecting mirrors 12 and 13 are not limited to conical reflecting surfaces,
The same effect can be obtained with the reflecting surface of the polygon mirror.

FIG. 4 is a perspective view showing a convex conical reflecting mirror used in this embodiment, FIG. 5 is a perspective view showing a concave conical reflecting mirror used in this embodiment, and FIG. 6 is a convex polygonal pyramid used in this embodiment. FIG. 7 is a perspective view showing an example of a polygon mirror, and FIG. 7 is a perspective view showing an example of a concave polygonal pyramid mirror used in this embodiment.

Next, the operation of the semiconductor exposure apparatus of this application example will be described with reference to FIGS.

A light beam from a light source 41 using a mercury lamp or an excimer laser as a light source is incident on a beam converter 31 via a mirror 30 and the beam shape is converted.
Next, an annular zone shape forming device 2 including two sets of convex conical reflected lights 11 and 14 and two sets of concave conical reflecting mirrors 12 and 13.
Then, it becomes an arbitrary ring-shaped light flux.

An annular light source 43 is formed on the focal plane of the optical integrator 42 by the optical integrator 42 constituted by a minute lens array. The ring-shaped secondary light source 43 illuminates the mask 45 on which the semiconductor circuit pattern is drawn by the illumination lens 44, and projects the control circuit pattern on the wafer 48 by the imaging lens 46. At this time, the image of the secondary light source is the entrance pupil 4 of the projection lens 46.
Can be 7. By making the size of the light source image smaller than the diameter of the entrance pupil 47, the low frequency contrast can be improved, and by making the shape of a ring, the high frequency contrast can be improved.

The shapes of the two sets of convex conical reflecting mirrors 11 and 14 are as shown in FIG.
The shapes of 2 and 13 are as shown in FIG. The annular image formed by the illumination light flux on the entrance pupil 47 of the imaging lens 46 does not necessarily have to be circular. If it is a square, a large effect is exerted in improving the resolution in the same direction as each side, and if it is a polygon, the same effect as a circular ring zone is obtained. The convex conical reflecting mirror and the concave conical reflecting mirror shown in FIGS. 4 and 5 may be a convex polygonal pyramid polygonal mirror and a concave polygonal pyramid polygonal mirror as shown in FIGS. 6 and 7.

[0029]

As described above, in the first and second inventions, the annular light flux is formed using the first and second convex reflecting mirrors and the first and second concave reflecting mirrors. As a result, there is an effect that it is possible to obtain an annular light flux with almost no loss of the amount of illumination light to the illuminated object.

Further, according to the second aspect of the invention, the convex reflecting mirror and the concave reflecting mirror are constituted by a convex polygonal pyramid polygonal mirror and a concave polygonal pyramid polygonal mirror, respectively, so that the cost of the annular light flux forming apparatus can be reduced. There is an effect that can be done.

Further, the third invention has a second optical element for illuminating the surface to be illuminated based on the light flux from the secondary light source of the annular light flux, and the surface to be illuminated is covered with a condensing lens on the wafer. By forming an image on, there is an effect that a resolution higher than the resolution limit due to the diffraction of the imaging lens can be obtained.

Furthermore, the third aspect of the present invention has a light flux varying means for independently varying the inner diameter and outer shape of the annular light flux, so that the optimum illumination shape according to the shape of the mask pattern and the maximum of the imaging lens can be obtained. There is an effect that the resolution of the value can be obtained.

[Brief description of drawings]

FIG. 1 is a diagram showing a semiconductor exposure apparatus to which an embodiment of the present invention is applied.

FIG. 2 shows an embodiment of the present invention showing an annular luminous flux type device,
(A) shows the case where the inner diameter of the annular light flux is minimized, and (b) is a diagram showing the case where the inner diameter and outer diameter of the annular light flux are maximized.

FIG. 3 is a diagram showing a method of independently changing the inner diameter and the outer diameter of the annular light flux in the present embodiment.

FIG. 4 is a perspective view showing a convex conical reflecting mirror used in this embodiment.

FIG. 5 is a perspective view showing a concave conical reflecting mirror used in this embodiment.

FIG. 6 is a perspective view showing an example of a convex polygonal pyramid polygon mirror used in this embodiment.

FIG. 7 is a perspective view showing an example of a concave polygonal pyramid mirror used in this embodiment.

FIG. 8 is a schematic diagram showing an example of a conventional illumination optical device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 illuminating optical device 2 annular zone light flux forming device 10 light flux 11 convex conical reflecting mirror 12 concave conical reflecting mirror 13 concave conical reflecting mirror 14 convex conical reflecting mirror 30 mirror 31 beam converter 41 light source 42 optical integrator 43 secondary light source 44 Illumination lens 45 Mask 46 Imaging lens 47 Entrance pupil 48 Wafer 51 Light source 52 Luminous flux 53 Lens

Claims (6)

[Claims] 1. The first and second convex reflecting mirrors and the first and second concave reflecting mirrors have the same optical axis, and the light flux incident on the first convex reflecting mirror is the first luminous flux. An annular light flux that is reflected by a convex reflector and is reflected by the second convex reflector via the first concave reflector is obtained, and the light of the light flux emitted from the second convex reflector is obtained. A method for forming a ring-shaped light flux, wherein the shape of the ring-shaped light flux of the emitted light flux is made variable by moving the light flux in the axial direction. 2. An inner diameter and an outer diameter of an annular zone of a light beam emitted from the second convex reflecting mirror are independently changed by changing a diameter of a light beam incident on the first convex reflecting mirror. The method for forming a ring-shaped light flux according to claim 1, wherein 3. A first convex reflecting mirror for reflecting an incident light beam from a light source in an annular shape in a direction of about 90 degrees with respect to an optical axis of the incident light beam, and a first convex reflecting mirror for reflecting the incident light beam. A first concave reflecting mirror that reflects the annular light flux in a direction parallel to the optical axis of the incident light flux, and the annular light flux reflected from the first concave reflection mirror to the optical axis of the reflected light flux of the incident light flux. A second concave reflecting mirror which is parallel to the other and reflects in the opposite direction, and an annular light flux reflected from the second concave reflecting mirror is emitted in the same optical axis as the optical axis of the incident light flux and in the same direction, and An annular light flux forming apparatus comprising: a second convex reflecting mirror whose center is movable in the optical axis direction of the incident light flux. 4. The convex reflecting mirror is a convex conical reflecting mirror or a convex polygonal pyramid polygonal mirror, and the concave reflecting mirror is a concave conical reflecting mirror or a concave polygonal pyramid polygonal mirror. 3. The annular light flux forming device described in 3. 5. An annular luminous flux forming device for forming a luminous flux supplied from a light source into an annular luminous flux, a first optical element for forming a secondary light source of the annular luminous flux, and the secondary light source. An illumination optical device comprising: a second optical element that illuminates a surface to be illuminated based on a light flux. 6. The illumination optical apparatus according to claim 5, further comprising a light flux varying unit that independently varies an inner diameter and an outer diameter of the annular light flux emitted from the annular light beam shaping device.