JP2001358071A - Projection exposure system and method of manufacturing semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a projection exposure system capable of carrying out projection exposure of high resolution, selecting an optimal lighting system corresponding to the direction and line width of a pattern and suitable for manufacturing a semiconductor device and a method of manufacturing a semiconductor device. SOLUTION: A projection exposure system is equipped with a lighting optical system lighting a reticule and a projection optical system projecting a pattern of the reticule onto a wafer. The lighting optical system is provided with various optical elements including a first optical element with a light polarizing conical surface and a second optical element with a light polarizing pyramidical surface, and various kinds of illuminating light are formed by the use of the various optical elements.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a projection exposure apparatus and a method for manufacturing a semiconductor device, and more particularly to a so-called stepper which is a device for manufacturing a semiconductor element, in which a pattern on a reticle surface is appropriately illuminated and high resolution is easily achieved. And a method of manufacturing a semiconductor device.

[0002]

2. Description of the Related Art Recent advances in semiconductor device manufacturing technology have been remarkable, and the accompanying fine processing technology has also advanced remarkably.
In particular, the optical processing technology has reached a fine processing technology having a submicron resolution after the manufacture of 1MDRAM semiconductor devices. In many cases, the exposure wavelength is fixed as a means for improving the resolution, and the NA (numerical aperture) of the optical system is increased.
Was used. However, recently, various attempts have been made to change the exposure wavelength from the g-line to the i-line and to improve the resolving power by an exposure method using an ultra-high pressure mercury lamp.

[0003] With the development of the method using g-line or i-line as the exposure wavelength, the resist process has also been developed. Together, the optics and the process have led to rapid advances in optical lithography.

It is generally known that the depth of focus of a stepper is inversely proportional to the square of NA. Therefore, when trying to obtain a submicron resolution, there arises a problem that the depth of focus becomes shallower.

On the other hand, various methods have been proposed for improving the resolving power by using light having a shorter wavelength typified by an excimer laser. It is known that the effect of using light of a short wavelength generally has an effect inversely proportional to the wavelength, and the depth of focus becomes deeper as the wavelength is shortened.

In addition to shortening the wavelength, various methods using a phase shift mask (phase shift method) have been proposed as a method for improving the resolution. According to this method, a thin film that gives a phase difference of 180 degrees to transmitted light is formed on a part of a conventional mask to improve the resolution, and the resolution is improved by IBM Corporation (USA). As proposed by Levenson et al. Resolution RP is wavelength λ, parameter is k
₁ , where the numerical aperture is NA, it is generally expressed by the formula RP = k ₁ λ / NA. Usually 0.7-0.8 parameter k ₁ is a practical range is known to be significantly improved to about 0.35, according to the phase shift method.

[0007] Various types of phase shift methods are known.
It is described in detail in the article by Fukuda et al.

However, there are still many problems in improving the resolving power by using a spatial frequency modulation type phase shift mask. For example, the following are the problems at present. (I). The technology to form a phase shift film has not been established. (B). Development of the optimal CAD for the phase shift film has not been established. (C). Existence of a pattern without a phase shift film. (D). In connection with (c), a negative resist must be used. (E). Inspection and repair technology not established.

For this reason, there are various obstacles in actually manufacturing a semiconductor device using this phase shift mask.
It is very difficult at present.

On the other hand, the present applicant has proposed an exposure method with a higher resolution by appropriately configuring an illumination device and an exposure device using the same in Japanese Patent Application No. 3-28631 (February 22, 1991). Application).

[0011]

In the exposure apparatus proposed by the present applicant, the k ₁ factor is mainly 0.5.
An illumination system that focuses on a nearby area having a high spatial frequency is used. This illumination system has a large depth of focus where the spatial frequency is high.

The actual manufacturing process of a semiconductor integrated circuit includes various processes in which high resolution performance of a pattern is required and processes in which high resolution performance of a pattern is not required.
Therefore, what is now required is a projection exposure apparatus that can meet the requirements for resolution performance required for each process.

The present invention applies an illumination method appropriate in each case according to the pattern shape and the resolution line width to be subjected to projection printing, that is, in order to cope with an integrated circuit manufacturing process having more than 20 steps. A projection exposure apparatus and a semiconductor element manufacturing method capable of easily switching between a conventional illumination system and a high-resolution illumination system while effectively utilizing a light flux according to the purpose, and easily obtaining a high resolution. For the purpose of providing.

Japanese Patent Application Laid-Open No. 61-91662 discloses an exposure method utilizing annular illumination as a high-resolution exposure method different from the above.
No. pp. 139 to 163. In this publication, as a method of not reducing the light use efficiency when switching between annular illumination and normal illumination, a conical lens is detachable in front of the optical integrator, and the distribution of light entering the optical integrator is centralized type and peripheral It can be switched to a ring shape.

However, this conical lens is disclosed in JP-A-58-81813, JP-A-58-43416, JP-A-58-160914, and JP-A-59-14.
No. 3146, which is a conical member that changes the distribution of light entering an optical integrator from a peripheral ring to a centralized type, and uses light in a ring illumination or an illumination method previously proposed by the present applicant. There is not much effect on improvement.

It is a first object of the present invention to provide a projection exposure apparatus and a method for manufacturing a semiconductor device, which can improve utilization efficiency in annular illumination or the illumination method proposed by the present applicant.

The present invention also provides a projection exposure apparatus and a method of manufacturing a semiconductor element, which do not cause uneven exposure even when switching between annular illumination and another illumination method (for example, normal illumination).
The purpose of.

[0018]

According to a first aspect of the present invention, there is provided a projection exposure apparatus comprising: an illumination optical system for illuminating a reticle; and a projection optical system for projecting a reticle pattern onto a wafer. The illumination optical system includes a first light deflector for converting incident light into annular light,
It is characterized by having a plurality of types of optical elements including a second light deflecting element for splitting into two light beams, and forming a plurality of types of illumination light using the plurality of types of optical elements.

According to a second aspect of the present invention, in the first aspect, the first and second light deflecting elements each have a conical light deflecting surface and a quadrangular pyramid light deflecting surface. It is characterized by being an element.

According to a third aspect of the present invention, there is provided a projection exposure apparatus comprising: an illumination optical system for illuminating a reticle; and a projection optical system for projecting the reticle pattern onto a wafer. Switching between annular illumination and non-zonal illumination is possible, and a feature is provided of a correction unit for correcting exposure unevenness caused by this switching.

According to a fourth aspect of the present invention, in the third aspect, an optical element having a conical light deflecting surface is used when performing the annular illumination.

According to a fifth aspect of the present invention, in the fourth aspect of the present invention, the correction means includes a lens movable in the optical axis direction.

According to a sixth aspect of the present invention, in the second or fourth aspect, the optical element having the conical light deflecting surface is a conical prism.

According to a seventh aspect of the present invention, there is provided the lighting device according to any one of the first to sixth aspects, wherein the lighting device according to any one of the first to sixth aspects, and a first object illuminated by the lighting device A projection optical system for projecting the pattern on the surface onto the second object.

According to a eighth aspect of the present invention, there is provided a method of manufacturing a semiconductor device, comprising preparing a reticle and a wafer, and exposing the wafer with the pattern of the reticle by the projection exposure apparatus according to the seventh aspect.

[0026]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a schematic diagram showing an embodiment of a projection exposure apparatus according to the present invention, in which the present invention is applied to a reduction type projection exposure apparatus called a stepper.

In FIG. 1, reference numeral 1 denotes a light source such as a high-brightness ultra-high pressure mercury lamp which emits ultraviolet rays, far ultraviolet rays, or the like.

Light emitted from the light source 1 is condensed by the elliptical mirror 2, reflected by the cold mirror 3, and reflected by the elliptical mirror 2.
An image (light emitting portion image) 1b of the light emitting portion 1a is formed in the vicinity of the second focal point 4 of FIG. The cold mirror 3 is made of a multilayer film and mainly transmits infrared light and reflects ultraviolet light.

Reference numeral 101 denotes an image forming system, which has two lens systems 5 and 9, and receives a light emitting unit image 1 b formed in the vicinity of the second focal point 4 through an optical element 8 to be described later. An image is formed on the surface 10a. The optical element 8 has a prism member 6 composed of a conical prism that deflects the incident light beam in a predetermined direction, and a parallel flat plate 7 that emits the incident light beam as it is.

Reference numeral 8a denotes a holding member which is configured to selectively switch and arrange the prism member 6 and the parallel flat plate 7 of the optical element 8 in the optical path. When the parallel plate 7 is in the optical path, the imaging system 101 is telecentric on the exit side. The optical element 8 is located near the pupil plane of the imaging system 101.

The optical integrator 10 is configured by arranging a plurality of microlenses two-dimensionally, and forms a secondary light source 10c near the exit surface 10b. 11
Is a diaphragm member, which has a plurality of aperture members and has a mechanism in which the aperture shape is switched in the optical path. Aperture member 1
Numeral 1 is arranged in a region where the secondary light sources that are discrete do not overlap with the secondary light source 10C.

Reference numeral 14a denotes a lens system, which collects a light beam from the exit surface 10b of the optical integrator 10,
Collimator lens 1 via aperture member 11 and mirror 13
Along with 4b, it illuminates a reticle 15, which is a surface to be irradiated, mounted on a reticle stage 16. The lens system 14a and the collimator lens 14b constitute the condenser lens 14.

Reference numeral 17 denotes a projection optical system, which reduces and projects a pattern drawn on the reticle 15 onto a surface of a wafer 18 placed on a wafer chuck 19. Reference numeral 20 denotes a wafer stage on which a wafer chuck 19 is placed. In this embodiment, the secondary light source 10C near the exit surface 10b of the optical integrator 10 forms an image near the pupil 17a of the projection optical system 17 by the condenser lens 14.

In this embodiment, the prism member 6 of the optical element 8 or the parallel flat plate 7 is selectively switched into the optical path according to the directionality of the pattern of the reticle 15 and the resolution line width, etc. The opening shape of the member 11 is changed. As a result, the light intensity distribution of the secondary light source image formed on the pupil plane 17a of the projection optical system 17 is changed, and
High-resolution projection exposure is performed in the same manner as the illumination method proposed in US Pat.

Next, in the present embodiment, the light intensity distribution on the incident surface 10a of the optical integrator 10 is changed by using the optical element 8, and the light of the secondary light source image formed on the pupil surface 17a of the projection optical system 17 is changed. A method of changing the intensity distribution will be described.

FIGS. 2 and 3 are schematic views showing the main parts when the optical path from the elliptical mirror 2 to the optical integrator 10 in FIG. 1 is developed. 2 and 3, the mirror 3 is omitted. 2 and 3, the elements 6 and 7 of the optical element 8 are switched to switch the incident surface 10 of the optical integrator 10.
The case where the light intensity distribution of a is changed is shown.

FIG. 2 shows a case where the parallel flat plate 7 of the optical element 8 is arranged in the optical path, and FIG. 3 shows a case where the prism member 6 of the optical element 8 is arranged in the optical path.

The illumination system shown in FIG. 2 is mainly for the case of performing projection with a large depth of focus without requiring much high resolution (first state), and is the same illumination method as the conventional one. The illumination system shown in FIG. 3 is a feature of the present invention mainly in the case of performing projection requiring a high resolution (second state).

FIGS. 2C and 3C schematically show the light intensity distribution on the incident surface 10a of the optical integrator 10, respectively. The hatched portions in the drawing are regions where the light intensity is higher than the other regions. FIG. 2 (B), FIG.
(B) is an explanatory diagram showing the distribution of the light intensity I along the X-axis direction shown in FIGS. 2 (C) and 3 (C), respectively.

In FIG. 2, the parallel plate 7 of the optical element 8 is arranged in the optical path, and the light emitting unit image 1 formed at the second focal point 4 of the elliptical mirror 2
b is the optical integrator 1 by the imaging system 101
An image is formed on the zero incidence surface 10a. At this time, FIG.
As shown in (B), the optical integrator 10
The light intensity distribution in the X direction on the incident surface 10a is substantially Gaussian rotationally symmetric.

In FIG. 3, the prism member 6 of the optical element 8 is arranged in the optical path, and the light intensity distribution on the incident surface 10a of the optical integrator 10 is the optical axis as shown in FIGS. 3 (B) and 3 (C). The portion has a weak ring-shaped light intensity distribution around the periphery and is weak. The reason will be described below.

FIG. 4 shows a plane parallel plate 7, a lens system 9 and an entrance surface 10 of an optical integrator 10 shown in FIG.
3 schematically shows the arrangement with a. In this embodiment, the position of the front principal point of the parallel plate 7 and the lens system 9 and the position of the rear principal point of the lens system 9 and the optical integrator 1
The optical distances of the zero incidence surface 10a are arranged so as to be distances f ₀ , respectively, assuming that the focal length of the lens system 9 is f ₀ .

At this time, the incident height t ₁ of the light beam exiting the parallel plate 7 at an angle α ₀ from the optical axis to the incident surface 10a is t ₁ =
f ₀ · tan α ₀ Assuming that the height of the outermost light beam passing through the parallel plate 7 from the optical axis is S ₀ , the incident angle β to the optical integrator incident surface 10 a is

[0044]

(Equation 1)

## EQU1 ##

Therefore, when the angle of the light beam is changed at the position of the parallel plate 7 (the front focal plane of the lens system 9), it is possible to change only the incident position without changing the incident angle on the incident surface 10a of the optical integrator 10. it can.

In this embodiment, by switching from the parallel flat plate 7 to the prism member 6 composed of a conical prism according to the above optical principle, a light having a weak optical axis portion on the incident surface 10a of the optical integrator 10 and a strong ring-shaped light around the periphery. Changed to intensity distribution.

Since the light intensity distribution on the entrance surface 10a of the optical integrator 10 corresponds to the light intensity distribution of the effective light source formed on the pupil surface 17a of the projection optical system 17,
By switching from the parallel plate 7 to the prism member 6,
On the pupil plane of the projection optical system 17, an effective light source having a light intensity distribution having a higher light intensity at a peripheral portion than at a central portion (optical axis portion) is formed.

In this embodiment, a stop member 11 is provided near the exit surface 10b of the optical integrator 10. The stop member 11 has, for example, a plurality of openings, and the shape of the openings can be arbitrarily changed. Has a mechanism. The aperture shape of the aperture member 11 corresponds to the shape of the secondary light source image formed on the pupil plane 17a of the projection optical system 17. For example, the peripheral portion has an opening through which more light passes than the central portion.

In this embodiment, the prism member 6 of the optical element 8 is used.
By switching to the prism member 6 or changing the aperture shape of the diaphragm member 11 in combination, a desired effective light source shape is obtained while effectively utilizing the light flux. (Note that the object of the present invention can be achieved without particularly providing the aperture member 11 in this embodiment.) In this embodiment, the configuration described above is proposed in Japanese Patent Application No. 3-28631. As described above, when the minimum line width of the pattern of the reticle 15 is relatively large, the configuration shown in FIG. 2A is used similarly to the conventional illumination device, and the light intensity distribution on the incident surface 10a of the optical integrator 10 becomes Gaussian. (First state).

When the minimum line width of the pattern is small, FIG.
The optical integrator 1 has the configuration shown in FIG.
By making the light intensity distribution of the zero incidence surface 10a in a ring shape and changing the aperture shape of the diaphragm member 11, a high-resolution illumination device is realized (second state).

The reason why the parallel flat plate 7 is inserted in the first state in FIG. 2A is that the parallel plate 7 is inserted in the second state (the prism member 6 is inserted) in FIG. 3A. This is to minimize the change in the optical path length between the lens system 5 and the lens system 9 during the first state. The parallel flat plate 7 may be omitted when the prism member 6 needs to be thin or the optical performance after the optical integrator 10 is not affected.

FIGS. 5 and 6 show the imaging system 10 in this embodiment.
When the focal length f of the lens system 9 constituting the optical system 1 is changed, the position of the light beam passing through the parallel flat plate 7 (emission height, S ₁ , S ₂ ) and the deflection angle (α ₁ , α ₂ ) are determined by the optical integrator 10. FIG. 5 is an explanatory diagram showing a relationship with an incident height (heights t ₁ and t ₂ from the optical axis) on an incident surface 10a.

In FIG. 5, the focal length of the lens system 9 is f ₁
Then, t ₁ = f ₁ tan α ₁ holds. In FIG. 6, when the focal length of the lens system 9 is f ₂ , t ₂ = f ₂ t
anα ₂ holds.

As shown by these equations, if the focal length f of the lens system 9 is increased, the incident position t at a predetermined height on the incident surface 10a of the optical integrator 10 at the position of the parallel plate 7 with a small deflection angle α. You can get _one . This means that if the focal length f of the lens system 9 is increased, the angle of the prism member 6 in the second state (prism angle)
Means that can be reduced. As a result, it is possible to obtain the image forming system 101 with less aberration. Actually, the focal length of the lens system 9 is set so that the prism angle becomes about 5 ° to 20 ° in consideration of the size of the prism member 6.

The prism member 6 of the optical element 8 in the present invention is not limited to a conical prism, and may have any shape as long as it deflects an incident light beam in a predetermined direction. For example, a polygonal pyramid prism such as a quadrangular pyramid prism shown in FIG. 7A or an octagonal pyramid prism shown in FIG. 8A may be used.

FIG. 7B and FIG.
8A schematically shows the light intensity distribution on the incident surface 10a of the optical integrator 10 when the prism member shown in FIG. 8A is used. In the figure, the light intensity is higher in the hatched portions than in the other portions.

In the present invention, the prism member 6 is configured to be switchable between three or more types of prism members and the parallel plate in addition to the two types of switching between the parallel plate 7 and the prism member 6 as in the first embodiment. Is also good.

In the present invention, a quadrangular pyramid prism as shown in FIG. 7A is rotated about the optical axis and time-smoothed to form a ring-shaped light intensity distribution as shown in FIG. 3C. You may.

Further, the size of the region where the light intensity is high may be changed by moving the light source 1 in the optical axis direction at the same time as switching the prism member.

FIG. 9 is a schematic diagram showing a main part of a part of the second embodiment of the present invention.

In this embodiment, as compared with the first embodiment shown in FIG.
Is that a half mirror 30 is provided in the optical path, and a part of the light beam from the imaging system 101 is made incident on the photodetector 31 (CCD, quadrant sensor, etc.). Is the same.

In this embodiment, the light intensity distribution on the incident surface 10a of the optical integrator 10 is indirectly measured and the light intensity distribution is monitored.
Thereby, the fluctuation of the light intensity and the light intensity distribution on the incident surface 10a is adjusted.

In this embodiment, for example, if a mechanism for rotating the optical element 6 with respect to the optical axis or decentering with respect to the optical axis is used, the light intensity distribution on the incident surface 10a of the optical integrator 10 can be changed to a desired shape. It can be changed.

FIG. 10 is a schematic view showing a main part of a part of the third embodiment of the present invention.

In this embodiment, a prism member 6 is mounted in the optical path and a lens system 33 having a different focal length is mounted on the incident surface 10a side of the optical integrator 10 instead of the lens system 9 as compared with the first embodiment shown in FIG. And the other configurations are the same.

In this embodiment, a desired shape of light intensity distribution is obtained by concentrating light in a narrower area of the incident surface 10a of the optical integrator 10.

Next, the optical operation of this embodiment will be described with reference to FIGS.
2 will be described.

FIGS. 11 and 12 schematically show an optical path from the optical element 8 (the prism member 6 or the parallel flat plate 7) to the optical integrator 10. FIG. 13 and 14
Indicates the one light intensity distribution on the incident surface 10a of the optical integrator 10 at that time.

FIG. 11A shows an arrangement in which illumination of a conventional method is performed in the first embodiment. Generally, the angle of a light beam that can enter the optical integrator 10 is determined, and in FIG. 11A, the angle is θ ₁ . The optical system before the optical integrator 10 is designed so that the angle of incidence on the optical integrator 10 does not exceed the angle θ ₁ . At this time, the light intensity distribution on the incidence surface 10a of the optical integrator 10 is limited by the Lagrange-Helmholtz invariant, so that the light intensity cannot be improved more than, for example, FIG. 13A. If you try to get more light concentration,
The angle of incidence on the optical integrator 10 is the angle θ
Beyond _one .

FIG. 11B shows a state in which the prism member 6 is inserted in the optical path in the first embodiment. FIG. 13B shows the light intensity distribution on the incident surface 10a at this time. Maximum incident angle at the incidence point S ₁ to the incident surface 10a of the light beam at this time is 11 similarly theta ₁ and (A). However, the effective light beam angle of the light beam actually incident is θ ₂ .

Here, as shown in FIG. 12A, the maximum incident angle can be reduced by inserting the optical element 32 (prism or field lens) in front of the incident surface 10a. At this time, the light intensity distribution on the incident surface 10a is shown in FIG.
It is shown in (A).

Here, since the maximum incident angle has a margin, if the focal length of the optical system from the prism member 6 to the optical integrator 10 is shortened, a higher light collecting degree can be obtained. FIG. 12B is an example in which the degree of light collection is increased using the optical principle. At this time, the light intensity distribution is shown in FIG.
3 (B). In FIG. 12B, the prism angle of the prism member 6 is increased in order to obtain a ring-shaped light intensity distribution.

In this embodiment, since the prism member 6 is inserted as described above, the incident angle on the incident surface 10a of the optical integrator 10 is changed without changing its maximum incident angle. By correcting the deflection and optimizing the incident angle, a margin is provided for the incident angle, and the degree of condensing is increased until the incident angle reaches the limit incident angle.

As specific means, zooming of the optical system from the prism member 6 to the optical integrator 10, switching of the optical system, a prism in front of the optical integrator 10 (a conical prism when the prism member 6 is a conical prism, In the case of a quadrangular pyramid prism, insertion of a quadrangular pyramid prism), insertion of an aspheric lens, or a combination thereof can be applied.

FIG. 15 is a schematic diagram showing a main part of a part of the fourth embodiment of the present invention.

In this embodiment, the optical element 8 (the position of the prism member 6 or the parallel plate 7) is shifted from the pupil of the imaging system 101 and the focal length of the lens system 9 is changed as compared with the first embodiment shown in FIG. The difference is that the light intensity distribution on the incident surface 10a of the integrator 10 is focused, and the other configuration is the same.

In FIG. 15, P represents a pupil plane of the lens system 9. FIG. 15A shows the illumination state in the first state in the first embodiment, and the incident angle on the optical integrator 10 is θ. FIG. 15B shows the illumination state in the second state in the first embodiment, and the incident angle is the same θ as in FIG. 11A. At this time, if the prism member 6 is shifted from the pupil plane P and the light beam diameter on the P plane is reduced as shown in FIG.
(B) can be smaller than the angle θ ₂ . In this embodiment, at this time, the focal point distance of the lens system 9 is changed so that the light intensity distribution on the incident surface 10a of the optical integrator 10 is locally condensed.

FIG. 16 is a schematic view of a main part of a fifth embodiment of the present invention.

In the present embodiment, the lens system 5 constituting the image forming system 101 is eliminated and the aperture 2 of the elliptical mirror 2 is removed, as compared with the first embodiment of FIG.
a is an optical integrator 10 by the lens system 9
Is different from the first embodiment in that an image is formed on the incident surface 10a of the elliptical mirror 2 and the optical element 8 is arranged near the second focal point of the elliptical mirror 2.

That is, in the embodiment shown in FIG.
The image of “a” is input to the entrance surface 10 of the optical integrator 10.
The optical element 8 is formed near the imaging position of the opening 2a of the elliptical mirror 2 between the light source 1 and the optical integrator 10 (the image position of the opening 2a).

On the other hand, in this embodiment, the aperture 2 of the elliptical mirror 2 is used.
The image of “a” is input to the entrance surface 10 of the optical integrator 10.
a light-emitting portion 1a between the light source 1 and the optical integrator 10 (the elliptical mirror 2).
(The second focal position).

Further, in this embodiment, the front focal position of the lens system 9 and the second focal position of the elliptical mirror 2 are substantially matched, and the light from the light emitting section image 1b formed at the second focal point by the lens system 9 is obtained. Is converted into a substantially parallel light beam, and is directed onto the incident surface 10a of the optical integrator 10. When the prism member 6 is inserted, four parallel light beams from the lens system 9 are incident on the entrance surface 1 of the optical integrator 10.
0a.

FIG. 17 is a schematic view of a main part of a sixth embodiment of the present invention.

In the present embodiment, the optical element 8 is provided with at least two prism members 6a, 6a,
6b are arranged and configured, and the optical integrator 1
The optical element 8 (the prism member 6) is used when changing the light intensity distribution on the zero incidence surface 10a, that is, when setting the second state.
a, 6b) are mounted in the optical path, and a part of the lens system 9a constituting the imaging system 101 is replaced with another lens system 9b so that the angle of incidence of the off-axis principal ray on the incident surface 10a is reduced. The difference is that the light beam is used effectively, and the other configurations are the same.

In this embodiment, the lens system 9a is arranged in the optical path in the first state as the illumination method (at this time, the optical element 8
Is not used. The light intensity at the entrance surface 10a of the optical integrator 10 is the pupil plane 17 of the projection optical system 17.
The light intensity at a is such that the central portion has strong rotational symmetry.

Then, the optical element 8 (the prism members 6a, 6)
b) is arranged in the optical path, and a lens system 9b having a different focal length is arranged in place of the lens system 9a to be in the second state, and the entrance surface 10a of the optical integrator 10a is set.
The incident angle of the chief ray to the incident surface 1
The light intensity of 0a, that is, the light intensity on the pupil plane 17a of the projection optical system 17 has an area that is stronger in the peripheral part than in the central part.

Next, a description will be given mainly of features of this embodiment different from those of the first embodiment.

In FIG. 17, the lens system 5 condenses a light beam from the light emitting portion image 1b formed near the second focal point 4 and emits it as a parallel light beam. The imaging system 101 (the lens system 5 and the lens system 9a) is telecentric on the exit side, and at least a part of the lens system is movable in the optical axis direction.
The light intensity distribution on the zero incidence surface 10a is adjusted.

In the present embodiment, the lens system 9a, which is a part of the imaging system 101, includes an optical system including two prism members 6a and 6b, depending on the directionality of the pattern of the reticle 15 and the resolution line width. The light intensity distribution on the entrance surface 10a of the optical integrator 10 is changed by switching to the element 8 and the lens system 9b, and the aperture shape of the aperture member 11 is changed as necessary to form the pupil surface 17a of the projection optical system 17. The light intensity distribution of the secondary light source image is changed.

Next, in the present embodiment, the light intensity distribution on the entrance surface 10a of the optical integrator 10 is changed by using the optical element 8, and the light of the secondary light source image formed on the pupil surface 17a of the projection optical system 17 is changed. A method of changing the intensity distribution will be described.

FIGS. 18 and 19 are schematic views showing the main parts when the optical path from the elliptical mirror 2 to the optical integrator 10 in FIG. 17 is developed. 18 and 19, the mirror 3 is omitted. FIGS. 18 and 19 show a case where each element of the optical element 8 is switched to change the light intensity distribution on the incident surface 10 a of the optical integrator 10.

FIG. 18 shows the case where the lens system 9a is arranged in the optical path. FIG. 19 shows the case where the lens system 9a is removed and the prism members 6a and 6b of the optical element 8 and the lens system 9b are replaced.
In the optical path.

The illumination system shown in FIG. 18 is mainly for the case of performing projection with a large depth of focus without requiring much high resolution (first state), and is the same illumination method as the conventional one. The illumination system shown in FIG. 19 is a feature of the present invention mainly in the case of performing projection requiring a high resolution (second state).

FIGS. 18 (B) and 19 (B) schematically show the light intensity distribution on the incident surface 10a of the optical integrator 10, respectively. The hatched portions in the drawing are regions where the light intensity is higher than the other regions. FIG. 3 shows the distribution of the light intensity I along the X-axis direction.

FIGS. 20 (A), (B) and (C) show FIG.
FIG. 20 schematically shows the state of light rays incident on the optical integrator 10 in each system shown in FIG. In the figure, ± θ indicates a range (angle) of a light beam that can enter the optical integrator 10 (can be emitted without being incident after being incident on the optical integrator 10). Also, the portion of the grid line in the drawing represents a portion where the light intensity of the light beam incident on the optical integrator 10 is higher.

FIG. 18A shows an optical arrangement in a normal illumination state. At this time, the light intensity distribution on the incident surface 10a of the optical integrator 10 is close to a Gaussian distribution as shown in FIG. 18B, and the incident angle is as shown in FIG. . When illumination for high resolution is performed in this state, there is a method of inserting a stop 121 having a closed opening 121a as shown in FIG. 21 behind or in front of the optical integrator 10. However, in this case, since only the light flux in the hatched portion of the light intensity distribution diagram in FIG. 18A can be used, the illuminance is significantly reduced.

Therefore, in this embodiment, as shown in FIG. 19A, the lens system 9a is replaced with a lens system 9b having a smaller focal length.
The focal length of the replaced (the lens system 9b when the f _9b, a prism 6a and the lens system 9b, each of the optical distance of the incident surface 10a of the lens system 9b and the optical integrator 10 is arranged so that each becomes f _9b and 19), the light intensity distribution on the incident surface 10a of the optical integrator 10 is as shown in FIG.

Then, by inserting a prism member 6b having an appropriate prism angle immediately before the optical integrator 10, the light incident angle (the incident angle of the off-axis light beam) is reduced as shown in FIG. , And efficiently enter the optical integrator 10. As a result, most of the incident light beam is used as illumination light.

In the present embodiment, by adopting the optical arrangement as shown in FIG. 19A based on the principle described above, illumination for high resolution is performed without greatly reducing the illuminance on the irradiation surface. .

In the present embodiment, the prism members 6a and 6b provided on a part of the image formation 101 may be a polygonal pyramid prism (octagonal pyramid prism) as shown in FIG.

In this embodiment, the case where the lens system 9a in FIG. 18A in the normal illumination state is replaced with the lens system 9b in FIG. 19A in the illumination state for high resolution has been described. Each lens constituting the lens system 9a may be moved (zoomed) to create the same state as the lens system 9b, or may be partially zoomed or partially replaced.

A high-resolution aperture 121 as shown in FIG. 21 may or may not be provided as necessary. In the present embodiment, the focal length of the lens system 9a is changed to change the magnification of the imaging system 101. However, the focal length of the lens system 5 may be changed, or both the lens system 5 and the lens system 9a may be changed. May be changed.

In this embodiment, in the normal lighting state (first
State) and the illumination state for high resolution (second state), the incident surface 1 of the optical integrator 10 is switched.
Due to the difference in the light intensity distribution of 0a, the illuminance uniformity (illuminance unevenness) on the irradiation surface changes to be axially symmetric, and uneven exposure may occur on the wafer 18. In such a case, by moving some of the lenses of the optical system 14 in the optical axis direction, aberrations such as distortion are changed, and axially symmetrical illuminance unevenness on the illumination surface (exposure unevenness on the wafer surface) is corrected. I have.

In the above embodiment, the reticle 15 is arranged as an illumination surface after the optical system 14.
An imaging system 14 may be arranged between the reticle 15 and the reticle 15, and a conjugate plane of the reticle 15 in the imaging system 14 may be illuminated.

FIG. 22 is a schematic diagram showing a main part of a part of the seventh embodiment of the present invention.

The present embodiment is different from the first embodiment shown in FIG. 1 in that a half mirror 43 is provided between the optical integrator 10 and the irradiated surface 15 to detect the amount of exposure on the irradiated surface. The other configuration is substantially the same.

In FIG. 22, reference numeral 44 denotes a reticle surface or a surface conjugate with the reticle. Reference numeral 45 denotes a pinhole, which is located at a position optically conjugate with the surface 44. Three
Reference numeral 1 denotes a photodetector (CCD, quadrant sensor, or the like).

In this embodiment, by adopting such a configuration, the effective light source distribution at the center of the irradiated surface can be monitored. In this embodiment, the light detector 31 can simultaneously monitor the exposure amount on the irradiated surface.

In this embodiment, the case where the half mirror 43 is disposed between the lens system 13a and the collimator lens 14b has been described. However, the half mirror 43 may be located between the optical integrator 10 and the irradiated surface 15. It can be placed anywhere.

According to each of the embodiments described above, by considering the fineness and directionality of the pattern on the reticle surface to be subjected to projection exposure, an illumination system suitable for the pattern is selected so that an optimal high-resolution image is obtained. An illumination device capable of projection exposure and a projection exposure device using the same have been achieved.

Further, according to each embodiment, when exposing a pattern that is not so fine, the conventional illumination system can be used as it is, and when exposing a fine pattern, loss of light amount is small and high resolution can be easily achieved. The effect that a large depth of focus can be obtained by using a lighting device that can be exhibited in a wide range is obtained.

Further, since the image performance can be controlled only by the deformation of the illumination system and the projection optical system is not restricted,
To achieve a projection exposure apparatus and a method of manufacturing a semiconductor device having an effect that main properties of an optical system such as distortion and characteristics of an image plane are stable despite various deformations in an illumination system. Can be.

[0114]

As described above, according to the present invention, the light utilization efficiency can be improved in the annular illumination or the illumination method proposed by the present applicant. And / or exposure unevenness can be improved.

[Brief description of the drawings]

FIG. 1 is a schematic view of a main part of a first embodiment of the present invention.

FIG. 2 is an explanatory view of a part of FIG. 1;

FIG. 3 is an explanatory view of a part of FIG. 1;

FIG. 4 is an explanatory diagram of an optical action of the lens system 9 in FIG. 1;

FIG. 5 is an explanatory diagram of an optical action of the lens system 9 of FIG. 1;

FIG. 6 is an explanatory diagram of an optical action of the lens system 9 in FIG. 1;

FIG. 7 is an explanatory view of another embodiment of the prism member according to the present invention.

FIG. 8 is an explanatory view of another embodiment of the prism member according to the present invention.

FIG. 9 is a schematic diagram of a main part of a part of the second embodiment of the present invention.

FIG. 10 is a schematic diagram of a main part of a part of a third embodiment of the present invention.

FIG. 11 is an explanatory diagram of an optical function of a third embodiment of the present invention.

FIG. 12 is an explanatory diagram of an optical function according to a third embodiment of the present invention.

FIG. 13 is an explanatory diagram of a light intensity distribution according to a third embodiment of the present invention.

FIG. 14 is an explanatory diagram of a light intensity distribution according to the third embodiment of the present invention.

FIG. 15 is a schematic diagram of a main part of a part of a fourth embodiment of the present invention.

FIG. 16 is a schematic view of a main part of a fifth embodiment of the present invention.

FIG. 17 is a schematic view of a main part of a sixth embodiment of the present invention.

FIG. 18 is an explanatory view of a part of FIG. 17;

19 is an explanatory view of a part of FIG. 17;

20 is an optical integrator 10 shown in FIG.
Explanatory drawing of the state of incidence of a light beam on the incident surface 10a of FIG.

FIG. 21 is an explanatory diagram of an aperture state of a diaphragm.

FIG. 22 is a schematic diagram of a main part of a part of the seventh embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Light source 2 Elliptic mirror 3 Cold mirror 5, 9 Lens system 6, 6a, 6b Prism member 7 Parallel plate 8 Optical element 10 Optical integrator 11 Stop member 13 Mirror 15 Reticle 17 Projection optical system 18 Wafer

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hiroyuki Ishii 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Shigeru Hayata 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon F term in reference (reference) 2H052 BA02 BA03 BA08 BA09 BA12 5F046 CB05 CB13 CB15

Claims (8)

[Claims] 1. A projection exposure apparatus having an illumination optical system for illuminating a reticle and a projection optical system for projecting a pattern of the reticle onto a wafer, wherein the illumination optical system converts incident light into annular light. A plurality of types of optical elements including a first light deflector element to be used and a second light deflector element for dividing incident light into four light beams, and a plurality of types of illumination light are formed using the plurality of types of optical elements. A projection exposure apparatus characterized by the above-mentioned. 2. The optical device according to claim 1, wherein the first and second light deflecting elements are optical elements having a conical light deflecting surface and a quadrangular pyramid light deflecting surface, respectively. 3. The projection exposure apparatus according to claim 1. 3. A projection exposure apparatus comprising: an illumination optical system for illuminating a reticle; and a projection optical system for projecting a pattern of the reticle onto a wafer, wherein the illumination optical system is adapted for annular illumination and non-annular illumination. A projection exposure apparatus capable of switching, and having a correction unit for correcting exposure unevenness caused by the switching. 4. The projection exposure apparatus according to claim 3, wherein when the annular illumination is performed, an optical element having a conical light deflection surface is used. 5. The projection exposure apparatus according to claim 4, wherein said correction means includes a lens movable in an optical axis direction. 6. The projection exposure apparatus according to claim 2, wherein the optical element having the conical light deflecting surface is a conical prism. 7. An illumination device according to claim 1, further comprising: a projection optical system that projects a pattern on a first object plane illuminated by the illumination device onto a second object. A projection exposure apparatus. 8. A method for manufacturing a semiconductor device, comprising: preparing a reticle and a wafer; and exposing the wafer with the pattern of the reticle by the projection exposure apparatus according to claim 7.