JP3459826B2 - Projection exposure apparatus and method for manufacturing semiconductor element - Google Patents

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 element, and more specifically, a so-called stepper, which is an apparatus for manufacturing a semiconductor element, appropriately illuminates a pattern on a reticle surface to facilitate high resolution. The present invention relates to a projection exposure apparatus and a method for manufacturing a semiconductor element obtained as described above.

[0002]

2. Description of the Related Art The recent progress in manufacturing technology of semiconductor devices is remarkable, and accompanying it, the progress of fine processing technology is remarkable.
In particular, the optical processing technology has reached the level of fine processing technology having submicron resolution at the border of the production of semiconductor elements of 1M DRAM. In many cases, the exposure wavelength has been fixed and the NA (numerical aperture) of the optical system has been fixed as a means for improving the resolution.
Was used. However, recently, various attempts have been made to change the exposure wavelength from g-line to i-line and improve the resolution by an exposure method using an ultra-high pressure mercury lamp.

Along with the development of the method of using g-line or i-line as the exposure wavelength, the resist process has also developed. The combination of this optical system and the process has led to a rapid advance 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 submicron resolution, a problem arises that the depth of focus becomes shallower with it.

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

Various methods (phase shift method) using a phase shift mask have been proposed as methods for improving resolution in addition to shortening the wavelength. This method is intended to improve the resolution by forming a thin film on a part of a conventional mask that gives a phase difference of 180 degrees with respect to the passing light with respect to the other part, and is manufactured by IBM (US). Proposed by Levenson et al. Resolving power RP is wavelength λ, parameter k
₁ , where NA is the numerical aperture, it is generally expressed by the formula RP = k ₁ λ / NA. It is known that the parameter k ₁ , which is usually in the practical range of 0.7 to 0.8, can be greatly improved to about 0.35 by the phase shift method.

Various types of phase shift methods are known, for example, Japanese microdevices 1990, 7
It is described in detail in the papers by Fukuda et al.

However, many problems still remain in order to actually improve the resolution by using a spatial frequency modulation type phase shift mask. For example, there are the following as problems at present. (I). The technology for forming the phase shift film has not been established. (B). The development of the optimum CAD for the phase shift film has not been established. (C). The existence of a pattern that cannot have a phase shift film. (D). There is no choice but to use a negative resist in relation to (c). (E). Inspection and correction techniques have not been established.

Therefore, actually, there are various obstacles in manufacturing a semiconductor device using this phase shift mask.
At present it is very difficult.

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

[0011]

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

There are various actual manufacturing processes of a semiconductor integrated circuit, including a process requiring high pattern resolution performance and a process not requiring such pattern resolution performance.
Therefore, what is currently required is a projection exposure apparatus that can meet the demand for resolution performance that is uniquely required for each process.

The present invention applies an appropriate illumination method in each case according to the pattern shape and the resolution line width to be subjected to the projection printing, that is, in order to correspond to the integrated circuit manufacturing process having more than 20 steps at the maximum. , A conventional exposure system and a high-resolution illumination system can be easily switched while effectively utilizing a light beam according to the purpose, and a projection exposure apparatus and a method for manufacturing a semiconductor element, which can easily obtain a high resolution. For the purpose of provision.

Further, as an exposure method with a high resolution different from that described above, a method utilizing annular illumination is disclosed in JP-A-61-91662.
It has been proposed in the publication. In this publication, a conical lens can be attached in front of the optical integrator so that the efficiency of use of light rays is not reduced when switching between annular illumination and normal illumination, and the distribution of light entering the optical integrator is centralized 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.
A conical member proposed in Japanese Patent No. 3146, which changes the distribution of light entering an optical integrator from a peripheral annular shape to a centralized type, and is a light utilization efficiency in an annular illumination and an illumination method previously proposed by the applicant. Is not very effective in improving

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

The present invention also provides a projection exposure apparatus and a method for manufacturing a semiconductor device, wherein exposure unevenness does not occur even when switching is performed between an annular illumination and another illumination method (for example, normal illumination).
The purpose of.

[0018]

A projection exposure apparatus according to a first aspect of the present invention is 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. The illumination optical system includes an optical deflecting element that converts light incident on the optical integrator into annular light, and the optical deflecting element changes the position in the direction perpendicular to the optical axis in the optical path.
The light intensity distribution on the incident surface of the optical integrator changes.
The feature is that it can be changed.

The invention of claim 2 is characterized in that, in the invention of claim 1, the light deflecting element is attachable to and detachable from an optical path.

A method of manufacturing a semiconductor device according to a third aspect of the present invention is characterized in that a reticle and a wafer are prepared, and the projection exposure apparatus according to the first or second aspect exposes the wafer with the pattern of the reticle. .

The invention of claim 4 is the same as the invention of claim 1 or 2.
In addition, the light deflection element is attachable to and detachable from the optical path.
It is characterized by that. The invention of claim 5 is based on the invention of claim 3.
In the light, the polygonal pyramid prism can be attached to and detached from the optical path.
It is characterized by being Noh. A method of manufacturing a semiconductor device according to a sixth aspect of the present invention prepares a reticle and a wafer, and exposes the wafer with the pattern of the reticle by the projection exposure apparatus according to any one of the first to fifth aspects. I am trying.

[0022]

1 is a schematic configuration diagram showing an embodiment of a projection exposure apparatus of the present invention, which is an example in which the present invention is applied to a reduction type projection exposure apparatus called a stepper.

In the figure, reference numeral 1 denotes a light source such as a high-intensity ultra-high pressure mercury lamp which emits ultraviolet rays or far ultraviolet rays, and its light emitting portion 1a is arranged near the first focal point of the elliptical mirror 2.

The light emitted from the light source 1 is collected 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 4 of the second focal point. The cold mirror 3 is composed of a multilayer film, and mainly transmits infrared light and reflects ultraviolet light.

An image forming system 101 has two lens systems 5 and 9, and a light emitting portion image 1b formed in the vicinity of the second focal point 4 is incident on an optical integrator 10 via an optical element 8 described later. An image is formed on the surface 10a. The optical element 8 has a prism member 6 that is a conical prism that deflects an incident light beam in a predetermined direction, and a parallel plate 7 that directly emits the incident light beam.

Reference numeral 8a is a holding member, which is constructed so that the prism member 6 and the parallel plate 7 of the optical element 8 are selectively switched 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 constructed by arranging a plurality of minute lenses two-dimensionally, and a secondary light source 10c is formed in the vicinity of its exit surface 10b. 11
Is a diaphragm member, and has a mechanism that has a plurality of aperture members and the aperture shape can be switched in the optical path. Aperture member 1
No. 1 is arranged in the area where the discrete secondary light sources do not overlap with the secondary light source 10C.

Reference numeral 14a denotes a lens system, which collects the light flux from the exit surface 10b of the optical integrator 10,
Collimator lens 1 through diaphragm member 11 and mirror 13
The reticle 15, which is a surface to be illuminated, placed on the reticle stage 16 together with 4b is illuminated. The lens system 14a and the collimator lens 14b form a condenser lens 14.

Reference numeral 17 denotes a projection optical system, which reduces and projects the pattern drawn on the reticle 15 onto the surface of the wafer 18 mounted on the wafer chuck 19. A wafer stage 20 has a wafer chuck 19 mounted thereon. 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 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, and the aperture is stopped if necessary. 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 the above-mentioned Japanese Patent Application No.
High-resolution projection exposure is performed in the same manner as the illumination method proposed in No. 28631.

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

FIGS. 2 and 3 are schematic views of essential parts when the optical path from the elliptic mirror 2 of FIG. 1 to the optical integrator 10 is developed. The mirror 3 is omitted in FIGS. 2 and 3. In FIGS. 2 and 3, the respective elements 6 and 7 of the optical element 8 are switched to change 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 the case where the parallel plate 7 of the optical element 8 is arranged in the optical path, and FIG. 3 shows the 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 used for projection with a deep depth of focus without requiring 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, which is mainly a case of performing projection requiring high resolution (second state).

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

In FIG. 2, the parallel plate 7 of the optical element 8 is arranged in the optical path, and the image 1 of the light emitting portion formed at the second focal point 4 of the elliptic mirror 2
b to the optical integrator 1 by the imaging system 101.
An image is formed on the incident surface 10a of 0. At this time,
As shown in (B), the optical integrator 10
The light intensity distribution in the X direction on the incident surface 10a of 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 as shown in FIGS. 3 (B) and 3 (C). The light intensity distribution is ring-shaped, with a weak portion and a strong intensity at the periphery. The reason for this will be described below.

FIG. 4 shows the plane-parallel plate 7 of FIG. 2A, the lens system 9 and the incident surface 10 of the optical integrator 10.
It is the one schematically showing the arrangement with a. In this embodiment, the parallel plate 7 and the front principal point position of the lens system 9 and the rear principal point position of the lens system 9 and the optical integrator 1 are arranged.
When the focal length of the lens system 9 is f ₀ , the optical distance of the incident surface 10a of ₀ is set to be the distance f ₀ .

At this time, the incident height t ₁ of the light beam emitted from the parallel plate 7 at the angle α ₀ from the optical axis to the incident surface 10a is t ₁ = f ₀ tan α ₀ . When the height of the outermost light flux passing through the parallel plate 7 from the optical axis is S ₀ , the incident angle β on the optical integrator incident surface 10a is

[0040]

[Equation 1]

It becomes

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

In the present embodiment, by switching from the parallel plate 7 to the prism member 6 made of a conical prism based on the above optical principle, the optical axis portion is weak on the incident surface 10a of the optical integrator 10 and the ring-shaped light is strong in the peripheral portion. The intensity distribution has been changed.

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 plane 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 in which the light intensity is stronger in the peripheral portion than in the central portion (optical axis portion) is formed.

In this embodiment, a diaphragm member 11 is provided in the vicinity of the exit surface 10b of the optical integrator 10. The diaphragm member 11 has, for example, a plurality of openings and the shape of the openings can be arbitrarily changed. It has a mechanism. The aperture shape of the diaphragm 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, it has an opening that allows more light to pass through in the peripheral portion than in the central portion.

In this embodiment, the prism member 6 of the optical element 8 is used.
By switching to, or switching to the prism member 6 and changing the aperture shape of the diaphragm member 11, the desired effective light source shape is obtained while effectively utilizing the light flux. (In this embodiment, the object of the present invention can be achieved even if the diaphragm member 11 is not provided.) In the present 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 as in the conventional illumination device, and the light intensity distribution on the incident surface 10a of the optical integrator 10 is Gaussian. (First state).

When the minimum line width of the pattern is small, the pattern shown in FIG.
The optical integrator 1 having the configuration shown in FIG.
An illumination device for high resolution is realized by changing the light intensity distribution of the incident surface 10a of 0 into a ring shape and changing the aperture shape of the diaphragm member 11 (second state).

Note that the parallel flat plate 7 is inserted in the first state of FIG. 2 (A) in the second state of FIG. 3 (A) (the prism member 6 is inserted) and in FIG. 2 (A). 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 of. The parallel plate 7 may be omitted when the prism member 6 may be thin or the optical performance after the optical integrator 10 is not affected.

FIGS. 5 and 6 show the image forming system 10 in this embodiment.
Of the optical integrator 10 with respect to the position (emission height, S ₁ , S ₂ ) of the light flux passing through the parallel plate 7 and the deflection angle (α ₁ , α ₂ ) when the focal length f of the lens system 9 constituting the lens 1 is changed. it is an explanatory view showing the relationship between the incidence height of the incident surface 10a (the height t ₁ of the optical axis, t _2).

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

As shown in these equations, if the focal length f of the lens system 9 is made large, the incident surface t of the optical integrator 10 at the position of the parallel plate 7 with a small deflection angle α is incident at a predetermined height on the incident surface t. 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 made smaller. As a result, it is possible to obtain the image forming system 101 in which aberration is less likely to occur. In practice, the lens system 9 is set to a focal length such that the prism angle is 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 the conical prism and may have any shape as long as it is a member for deflecting the incident light beam in a predetermined direction. For example, a polygonal pyramid prism such as a four-sided pyramid prism shown in FIG. 7A or an eight-sided pyramid prism shown in FIG. 8A may be used.

FIG. 7B and FIG. 8B are respectively shown in FIG.
8A and 8A schematically show 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 shaded area has a higher light intensity than the other areas.

In the present invention, the prism member 6 is configured such that, in addition to the two types of switching between the parallel plate 7 and the prism member 6 as in the first embodiment, three or more types of prism members and the parallel plate can be switched. Good.

In the present invention, a quadrangular pyramid prism as shown in FIG. 7 (A) is rotated around the optical axis for temporal smoothing to form a ring-shaped light intensity distribution as shown in FIG. 3 (C). May be.

Further, the size of the region of high light intensity 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 view of the essential part of a second embodiment of the present invention.

In this embodiment, as compared with the first embodiment shown in FIG. 1, it is located in front of the optical integrator 10 (on the side of the light source 1).
Is different in that a half mirror 30 is provided in the optical path of, and a part of the light flux from the imaging system 101 is made incident on the photodetector 31 (CCD, four-division 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.
This adjusts the fluctuations of the light intensity and the light intensity distribution on the incident surface 10a.

In this embodiment, for example, if a mechanism for rotating the optical element 6 with respect to the optical axis or eccentric with respect to the optical axis is used, the light intensity distribution on the incident surface 10a of the optical integrator 10 is made into a desired shape. It is possible to change.

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

In this embodiment, the prism member 6 is mounted in the optical path as compared with the first embodiment shown in FIG. 1, 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. The difference lies in that the other configurations are the same.

In this embodiment, the light is concentrated in a narrower area of the incident surface 10a of the optical integrator 10 to obtain a light intensity distribution of a desired shape.

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

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

FIG. 11A shows the arrangement when the conventional illumination is performed in the first embodiment. Generally, the angle of a light ray that can be incident on the optical integrator 10 is fixed, and in FIG. 11A, the angle is θ ₁ . The optical system before the optical integrator 10 is designed so that the incident angle on the optical integrator 10 does not exceed the angle θ ₁ . At this time, the light intensity distribution on the incident surface 10a of the optical integrator 10 is limited due to the Lagrange-Helmholtz invariant, and the light intensity cannot be improved as compared with, for example, FIG. 13A. If you try to get a higher concentration,
The incident angle to the optical integrator 10 is the angle θ.
_It exceeds ₁ .

FIG. 11B shows a state in which the prism member 6 is inserted in the optical path in the first embodiment. The light intensity distribution on the incident surface 10a at this time is shown in FIG. At this time, the maximum incident angle of the light flux on the incident surface 10a at the incident point S ₁ is θ ₁ as in FIG. 11A. However, the effective luminous flux angle of the luminous flux that actually enters is θ ₂ .

Here, as shown in FIG. 12A, the maximum incident angle can be made small by inserting the optical element 32 (prism or field lens) in front of the incident surface 10a. FIG. 14 shows the light intensity distribution on the incident surface 10a at this time.
It shows in (A).

Since the maximum incident angle has a margin here, if the focal length of the optical system from the prism member 6 to the optical integrator 10 is shortened, a higher light converging degree can be obtained. FIG. 12B is an example in which the optical principle is utilized to increase the degree of light collection. 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 large in order to obtain the ring-shaped light intensity distribution.

In the present embodiment, by inserting the prism member 6 as described above, the incident angle on the incident surface 10a of the optical integrator 10 is biased without changing the maximum incident angle. By correcting the bias and optimizing the incident angle, the incident angle has a margin and the converging degree is increased until the incident angle reaches the limit incident angle.

As concrete means therefor, 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, a quadrangular pyramid prism) can be inserted, an aspherical lens can be inserted, or a combination of these can be applied.

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

In this embodiment, the optical element 8 (the positions of the prism member 6 and the parallel plate 7) is displaced from the pupil of the image forming 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 configurations are the same.

In FIG. 15, P represents the pupil plane of the lens system 9. FIG. 15A shows the illumination state of the first state in Example 1, and the incident angle on the optical integrator 10 is θ. FIG. 15B shows the illumination state of the second state in Example 1, and the incident angle is the same θ as in FIG. 11A. At this time, when the prism member 6 is displaced from the pupil plane P and the light beam diameter on the P plane is reduced as shown in FIG. 15C, the incident angle θ ′ is as shown in FIG.
It can be made smaller than the angle θ _{2 in} (B). In this embodiment, at this time, the focal point distance of the lens system 9 is changed to locally focus the light intensity distribution on the incident surface 10a of the optical integrator 10.

FIG. 16 is a schematic view of the essential portions of Embodiment 5 of the present invention.

This embodiment is different from Embodiment 1 of FIG. 1 in that the lens system 5 constituting the imaging system 101 is eliminated and the aperture 2 of the elliptic mirror 2 is removed.
a is an optical integrator 10 by the lens system 9.
The optical element 8 is arranged so as to form an image on the incident surface 10a of the optical disk 8 and the optical element 8 is arranged in the vicinity of the second focal point of the elliptic mirror 2, and the other configurations are the same.

That is, in the embodiment of FIG. 1, the light emitting section 1 of the light source 1
The image of a is the incident surface 10 of the optical integrator 10.
The optical element 8 is formed on the surface a, and the optical element 8 is provided between the light source 1 and the optical integrator 10 in the vicinity of the image forming position of the aperture 2a of the elliptic mirror 2 (image position of the aperture 2a).

On the other hand, in this embodiment, the opening 2 of the elliptic mirror 2 is used.
The image of a is the incident surface 10 of the optical integrator 10.
a, and the optical element 8 is formed on the image forming position of the light emitting portion 1a between the light source 1 and the optical integrator 10 (the elliptic mirror 2).
The second focal point position) is provided in the vicinity thereof.

In the present embodiment, the front focal position of the lens system 9 and the second focal position of the elliptical mirror 2 are made to substantially coincide with each other, and the lens system 9 allows the light from the light emitting portion image 1b formed at the second focal point. Is converted into a substantially parallel light beam and directed to 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 incident surface 1 of the optical integrator 10.
It's facing 0a up.

FIG. 17 is a schematic view of the essential portions of Embodiment 6 of the present invention.

In this embodiment, as compared with the first embodiment shown in FIG. 1, the optical element 8 has at least two prism members 6a in the optical axis direction,
The optical integrator 1 is configured by arranging 6b.
When changing the light intensity distribution of the incident surface 10a of 0, that is, in the second state, the optical element 8 (prism member 6
a, 6b) in the optical path and part of the lens system 9a forming the imaging system 101 is replaced with another lens system 9b so that the incident angle of the off-axis chief ray on the incident surface 10a becomes small. The difference is that the effective use of the light flux is made, and the other configurations are the same.

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

The optical element 8 (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 so that the lens system 9b is brought into the second state to make the incident surface 10a of the optical integrator 10a.
The incidence angle of the chief ray on
The light intensity of 0a, that is, the light intensity on the pupil plane 17a of the projection optical system 17 has a stronger region in the peripheral portion than in the central portion.

Next, the features of the present embodiment different from those of the first embodiment will be mainly described.

In FIG. 17, the lens system 5 collects the light beam from the light emitting portion image 1b formed in the vicinity 4 of the second focal point and emits it as a parallel light beam. The image forming system 101 (lens system 5 and 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, whereby the optical integrator 1 is provided.
The light intensity distribution of the incident surface 10a of 0 is adjusted.

In the present embodiment, the lens system 9a which is a part of the image forming system 101 and the optical system including the two prism members 6a and 6b are provided according to 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 between the element 8 and the lens system 9b, and the aperture shape of the diaphragm member 11 is changed as necessary to form it on the pupil plane 17a of the projection optical system 17. The light intensity distribution of the secondary light source image is changed.

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

FIG. 18 and FIG. 19 are schematic views of essential parts when the optical path from the elliptic mirror 2 to the optical integrator 10 in FIG. 17 is expanded. The mirror 3 is omitted in FIGS. 18 and 19. 18 and 19 show a case where the respective elements of the optical element 8 are switched to change the light intensity distribution of the incident surface 10a of the optical integrator 10.

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

The illumination system shown in FIG. 18 is mainly used for projection with a deep depth of focus without requiring 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, which is mainly a case of performing projection requiring high resolution (second state).

FIG. 18B and FIG. 19B schematically show the light intensity distributions on the incident surface 10a of the optical integrator 10, respectively. The shaded area in the figure is an area where the light intensity is higher than other areas. The figure shows the distribution of the light intensity I along the X-axis direction.

20 (A), (B), and (C) are shown in FIG.
In each system of FIG. 19, the state of the light ray which injects into the optical integrator 10 is shown typically. In the figure, ± θ indicates the range (angle) of the light rays that can be incident on the optical integrator 10 (can be emitted without being blocked after entering the optical integrator 10). Also, the portion of the lattice line in the figure represents the portion of the light incident on the optical integrator 10 having a higher light intensity.

FIG. 18A shows the optical arrangement in the normal illumination state. At this time, the light intensity distribution on the incident surface 10a of the optical integrator 10 has a distribution close to a Gaussian distribution as shown in FIG. 18 (B), and its incident angle is as shown in FIG. 20 (A). . When high-resolution illumination is performed in this state, there is a method of inserting a diaphragm 121 having a closed opening 121a as shown in FIG. 21 in the rear or front of the optical integrator 10. However, in this case, since only the light flux in the shaded area of the light intensity distribution chart of 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 by 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 ), The light intensity distribution on the incident surface 10a of the optical integrator 10 is as shown in FIG.

A prism member 6b having an appropriate prism angle is inserted immediately before the optical integrator 10 so that the light beam incident angle (the off-axis light beam incident angle) becomes small as shown in FIG. 20 (C). , And is efficiently incident on the optical integrator 10. As a result, most of the incident light flux is used as illumination light.

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

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

Further, the high-resolution diaphragm 121 as shown in FIG. 21 may or may not be attached as necessary. Although the focal length of the lens system 9a is changed in order to change the magnification of the image forming system 101 in this embodiment, 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 the present embodiment, a normal lighting condition (first
State) and the illumination state for high resolution (second state) are switched to the incident surface 1 of the optical integrator 10.
Due to the difference in the light intensity distribution of 0a, the illuminance uniformity (illuminance unevenness) on the irradiation surface may change to be axisymmetric, and uneven exposure may occur on the wafer 18. In such a case, by moving some lenses of the optical system 14 in the optical axis direction, aberrations such as distortion are changed to correct axially symmetric illuminance unevenness on the illumination surface (exposure unevenness on the wafer surface). There is.

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

FIG. 22 is a schematic view of a part of a 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 exposure amount on the irradiated surface. The other configurations are 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 placed at a position optically conjugate with the surface 44. Three
Reference numeral 1 is a photodetector (CCD, quadrant sensor, etc.).

By adopting such a configuration in this embodiment, it is possible to monitor the effective light source distribution at the center of the illuminated surface. Further, in the present embodiment, the photodetector 31 can simultaneously monitor the exposure amount on the irradiated surface.

Although the half mirror 43 is arranged between the lens system 13a and the collimator lens 14b in this embodiment, the half mirror 43 may be arranged between the optical integrator 10 and the illuminated surface 15. You can place it anywhere.

According to each of the embodiments described above, by considering the fineness and directionality of the pattern on the reticle surface to be projected and exposed, an illumination system suitable for the pattern is selected to obtain an optimum high resolution. An illumination device capable of projection exposure and a projection exposure apparatus using the same are 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, the loss of light amount is small and high resolution is easy. It is possible to obtain an effect that a large depth of focus can be obtained by using a lighting device that can exhibit the above.

Further, since the image performance can be controlled by modifying only the illumination system, and the projection optical system is not restricted,
It is possible to achieve a projection exposure apparatus and a method for manufacturing a semiconductor element, which have the effect that the main properties of the optical system such as the characteristics of the distortion and the image plane remain stable despite various modifications in the illumination system. it can.

[0110]

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

[Brief description of drawings]

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

FIG. 2 is an explanatory diagram of a part of FIG.

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

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

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

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

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 view of a part of a second embodiment of the present invention.

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

FIG. 11 is an explanatory diagram of an optical action of Example 3 of the present invention.

FIG. 12 is an explanatory diagram of an optical action of Example 3 of the present invention.

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

FIG. 16 is a schematic view of the essential portions of Embodiment 5 of the present invention.

FIG. 17 is a schematic view of the essential portions of Embodiment 6 of the present invention.

FIG. 18 is an explanatory diagram of a part of FIG.

FIG. 19 is an explanatory diagram of a part of FIG.

FIG. 20 is an optical integrator 10 of FIG.
Of the incident state of the light flux on the incident surface 10a of

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

FIG. 22 is a schematic view of a main part of a portion of Embodiment 7 of the present invention.

[Explanation of symbols]

1 light source 2 elliptical mirror 3 cold mirror 5,9 lens system 6,6a, 6b Prism member 7 Parallel plate 8 optical elements 10 Optical integrator 11 Aperture member 13 mirror 15 reticle 17 Projection optical system 18 wafers

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shigeru Hayada 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Stock Association In-house (56) Reference JP-A-5-217853 (JP, A) JP-A-5 -217851 (JP, A) JP 5-251308 (JP, A) JP 5-226217 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) H01L 21/027

Claims (3)

(57) [Claims] 1. A projection exposure apparatus having an illumination optical system for illuminating a reticle and a projection optical system for projecting the pattern of the reticle onto a wafer, wherein the illumination optical system is a zone-shaped light incident on an optical integrator. The light intensity distribution on the incident surface of the optical integrator can be changed by changing the position of the light deflecting element in the direction perpendicular to the optical axis in the optical path of the optical deflecting element. Projection exposure apparatus. 2. The projection exposure apparatus according to claim 1 , wherein the light deflection element is attachable to and detachable from an optical path. 3. Prepare the reticle and the wafer, also claim 1
2. The method for manufacturing a semiconductor element, wherein the projection exposure apparatus according to 2 exposes the wafer with the pattern of the reticle.