JPH06204114A - Lighting system and projection aligner using same - Google Patents

Abstract

PURPOSE:To obtain a lighting system and projection aligner using the system, in which a lighting method being the object of the invention is appropriately changed and selected each time manually or automatically, by changing and using a light-intensity distribution formed in the outgoing surface of an optical integrator. CONSTITUTION:When an image is formed in the vicinity of a second focus by luminous flux from a light-emitting part arranged in the vicinity of the first focus of an elliptic mirror 2 and an applied surface is lighted via optical integrator 9 by luminous flux from the image, optical elements 6, 8, which can be inserted into and removed from an optical path, for deflecting incident light flux in a predetermined direction; an image formation system for forming the image by different magnifying powers in the plane of incidence of the optical integrator 9 and a diaphragm member 10 are arranged between the elliptic mirror 2 and optical integrator 9. Then, the optical elements 6, 8, image formation system and diaphragm member 10 are selectively changed according to a pattern on the applied surface so that a light intensity distribution formed in the outgoing surface of the optical integrator 9 is changed and used.

Description

Detailed Description of the Invention

[0001]

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

[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 is generally inversely proportional to the wavelength, and the depth of focus becomes deeper as the wavelength is shortened.

In addition to the use of light with a short wavelength, various methods using a phase shift mask (phase shift method) have been proposed as methods for improving resolution. 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). Levenson
Proposed by et al. The resolving power RP is generally represented by the equation RP = k ₁ λ / NA, where λ is the wavelength, k _{1 is} the parameter, and NA is the numerical aperture. 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, Nikkei Microdevice 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.

According to the present invention, an illumination method suitable for the pattern shape and the resolution line width to be subjected to projection printing is emphasized, for example, when it is desired to make effective use of a light flux and image performance compatible with each other. If you want to, and if you want to emphasize the image performance, etc.
It is an object of the present invention to provide an illuminating device and a projection exposure apparatus using the illuminating device that can be appropriately or manually selected by switching appropriately.

[0014]

In the illuminating device of the present invention, a light emitting section is arranged in the vicinity of the first focal point of the elliptic mirror, and a light flux from the light emitting section is passed through the elliptic mirror to the second focal point of the elliptic mirror. When an image of the light emitting unit is formed in the vicinity and the illuminated surface is illuminated through an optical integrator in which a plurality of microlenses are two-dimensionally arranged by the light flux from the image of the light emitting unit, the elliptic mirror and the optical integrator are illuminated. And an optical element that can be inserted into and removed from the optical path that deflects the incident light beam in a predetermined direction, and an imaging system that can switchably form an image of the light emitting unit on the incident surface of the optical integrator at different magnifications. And an iris member that can be inserted and removed near the incident surface or the exit surface of the optical integrator, and selectively switches the optical element, the imaging system, and the iris member according to the pattern on the illuminated surface. The optical Change the light intensity distribution formed on the exit surface of the integrators is characterized in that it has to use.

Particularly, by selectively switching the optical element, the image forming system, and the diaphragm member, the light intensity of the incident surface of the optical integrator is stronger than the second state of rotational symmetry where the central portion is strong and the central portion. It is characterized in that the first state having a strong region in the peripheral portion is selected.

The projection exposure apparatus of the present invention is the first elliptic mirror.
A light emitting unit is arranged in the vicinity of the focal point, an image of the light emitting unit is formed near the second focus of the elliptic mirror by the light flux from the light emitting unit, and a plurality of light beams from the image of the light emitting unit are formed. When a pattern on the first object plane is illuminated through an optical integrator in which the microlenses of (1) are two-dimensionally arranged and the pattern is projected and exposed on the second object plane through a projection optical system, An optical element that can be inserted into and removed from the optical path that deflects the incident light beam in a predetermined direction between the optical integrator and
An image forming system for forming an image of the light emitting unit on the incident surface of the optical integrator so as to be switchable at different magnifications, and an insertable / detachable diaphragm member near the incident surface or the exit surface of the optical integrator are arranged. , The optical element, the image forming system, and the diaphragm member are selectively switched according to the pattern on the illuminated surface to change the light intensity distribution on the incident surface of the optical integrator, and the pupil surface of the projection optical system. The feature is that the above light intensity distribution is adjusted.

In particular, the optical element, the imaging system, and the diaphragm member are selectively switched to change the light intensity distribution on the incident surface of the optical integrator so that the light intensity on the pupil plane of the projection optical system is the central portion. Is selected between the second state of strong rotational symmetry and the first state having a stronger region in the peripheral portion than in the central portion.

[0018]

Embodiment 1 FIG. 1 is a schematic configuration diagram showing Embodiment 1 of an illumination apparatus and a projection exposure apparatus using the same according to the present invention. The present invention is applied to a reduction type projection exposure apparatus called a stepper. Here is an example. 2 and 3 are explanatory views of a part of FIG. FIG. 2 shows a first state of the illumination method for high-resolution projection as described later, and FIG. 3 shows a second state of the normal illumination method.

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

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 of the light emitting portion 1a (light emitting portion image) 1b is formed in the vicinity of the second focal point. The cold mirror 3 is composed 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 7, and which is capable of inserting and removing the light emitting portion image 1b formed in the vicinity 4 of the second focal point from the optical path described later. 8
An image is formed on the incident surface 9a of the optical integrator 9 with or without.

The optical element 6 is composed of a quadrangular pyramid prism for deflecting an incident light beam in a predetermined direction. The optical element 8 is composed of a prism (for example, a conical prism) that deflects the incident light beam in a predetermined direction, and the optical integrator 9 prevents the light beam from being vignetted by the optical integrator 9.
The angle of incidence of the chief ray on the incident surface 9a is reduced.

A holding member 21 holds the optical element 6, and moves along the guide 22 so as to retract the optical element 6 from the optical path. 23 is a motor and pinion 2
4 and the rack 25 are connected to each other to guide the holding member 21 to the guide 22.
Move along. Reference numerals 26 and 27 denote position sensors, which detect the position of the holding member 21 and detect whether the optical element 6 is in the optical path or retracted from the optical path.

Reference numeral 28 denotes a holding member, which holds the lens system 7 of the image forming system 101, and moves along the optical axis along the guide 29 to make the incident surface of the optical integrator 9 of the light emitting unit image 1b. The imaging magnification to 9a is switched.

Reference numeral 30 is a motor, which is a pinion 31 and a rack 3.
The holding member 28 is moved on the optical axis by connecting the two.
Reference numerals 33 and 34 denote position sensors, which detect the position of the holding member 28, and thereby detect, for example, the states of two predetermined types of imaging magnification.

A holding member 35 holds the optical element 8 and moves along the guide 36 so as to retract the optical element 8 from the optical path. 37 is a motor and pinion 3
8 and the rack 39 connect the holding member 35 to the guide 36.
Move along. Reference numerals 40 and 41 respectively denote position sensors, which detect the position of the holding member 35 and detect whether the optical element 8 is in the optical path or is retracted from the optical path.

The optical integrator 9 is constructed by arranging a plurality of minute lenses two-dimensionally, and a secondary light source 9c is formed in the vicinity of its exit surface 9b.

A diaphragm member 10 is arranged near the exit surface 9b of the optical integrator 9 and sets an effective light source shape formed near the pupil 15a of the projection optical system 15 which will be described later. The diaphragm member 10 may be arranged on the incident surface 9 side of the optical integrator 9.

The diaphragm member 10 has a plurality of aperture members 10a and 10b having different aperture shapes, and has a mechanism for switching the aperture shapes in the optical path.

Although the drawing shows the case where two opening members 10a and 10b are used, the number of opening members may be two or more.

A holding member 42 holds the diaphragm member 10, and the aperture members 10a and 10b of the diaphragm member 10 are held.
Are moved along the guides 43 in order to selectively place them in the optical path. Reference numeral 44 denotes a motor, which moves the holding member 42 by connecting the pinion 45 and the rack 46. Four
Reference numerals 7 and 48 denote position sensors, which detect the position of the holding member 42 and which of the aperture members 10a and 10b of the diaphragm member 10 is located in the optical path.

Reference numeral 11 denotes a lens system, which collects a light beam from the exit surface 9b of the optical integrator 9 and mounts it on the reticle stage together with the lens system 13 via the diaphragm member 10 and the mirror 12, which is the illuminated surface of the reticle. Illuminating 14 The lens system 11 and the lens system 13 form a condenser lens.

Reference numeral 15 denotes a projection optical system, which is a wafer 1 on which a pattern drawn on the reticle 14 is placed on a wafer chuck.
The reduced projection is performed on the six planes.

In this embodiment, the secondary light source 9c in the vicinity of the exit surface 9b of the optical integrator 9 includes the lens systems 11 and 1.
3 is formed in the vicinity of the pupil 15a of the projection optical system 15.

In this embodiment, the optical elements 6 and 8 or the lens system 7 are selectively switched into the optical path as shown in FIGS. 2 and 3 according to the directionality of the pattern of the reticle 14 and the resolution line width. The aperture shape of the diaphragm member 10 is changed as necessary. As a result, the light intensity distribution of the secondary light source image formed on the pupil plane 15a of the projection optical system 15 is changed so that high resolution projection is possible in the same manner as the illumination method proposed in Japanese Patent Application No. 3-28631. It is exposing.

Next, in the present embodiment, the light intensity distribution on the incident surface 9a of the optical integrator 9 is changed by using the optical elements 6 and 8 and the lens system 7, and the aperture members 10a and 10b of the diaphragm member 10 are used. A method of changing the light intensity distribution of the secondary light source image formed on the pupil plane 15a of the projection optical system 15 will be described.

FIGS. 2 and 3 are schematic views of essential parts when the optical path from the elliptical mirror 2 of FIG. 1 to the diaphragm member 10 is developed. The mirror 3 is omitted in FIGS. 2 and 3. 2 and 3 show a case where the optical elements 6 and 8 and the lens system 7 are switched to change the light intensity distribution on the incident surface 9a of the optical integrator 9.

In FIG. 2, the optical elements 6 and 8 are arranged in the optical path,
FIG. 3 shows the case where the aperture member 10a of the diaphragm member 10 is used, the optical elements 6 and 8 are removed, the lens system 7 is moved on the optical axis, and the aperture member 10b of the diaphragm member 10 is used. There is.

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

2C and 3C schematically show the light intensity distribution on the incident surface 9a of the optical integrator 9, respectively. In the figure, the shaded areas are areas where the light intensity is higher than other areas. 2 (B) and 3
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. 2A, the light emitting portion image 1b is formed by arranging the optical elements 6 and 8 in the optical path and forming the second focal point 4 of the elliptic mirror 2.
Is imaged on the incident surface 9a of the optical integrator 9 by the imaging system 101. At this time, as shown in FIG. 2B, the light intensity distribution in the X direction on the incident surface 9a of the optical integrator 9 is a ring-shaped light intensity distribution in which the optical axis portion is weak and the periphery is strong.

In FIG. 3A, the optical elements 6 and 8 are removed,
The lens system 7 is moved on the optical axis to form the image 1b of the light emitting portion on the imaging system 1.
01 the incident surface 9a of the optical integrator 9
The image is formed at a predetermined magnification.

At this time, the light intensity distribution on the incident surface 9a of the optical integrator 9 has a substantially Gaussian rotational symmetry as shown in FIGS. 3 (B) and 3 (C).

In the present embodiment, as shown in FIG. 1, the switching of the optical elements 6 and 8, the lens system 7, and the light shielding plate 10 are independently driven by the respective motors 23, 37, 30, 44. (Note that it may be switched manually.)
Also, other combinations than the configuration of the optical system shown in FIG. 3 are possible.

For example, when only the diaphragm member 10 is retracted from the optical path from the state shown in FIG. 2, the state of FIG. 2 in which the vertical and horizontal patterns have high resolution and the depth of focus is deep as described above, and the conventional illumination method. It can be set to an intermediate state between the three states. In this case, the image forming performance is intermediate between those shown in FIGS.

In this embodiment, the setting of each switching portion is determined in this manner in accordance with the directionality and line width of the pattern of the reticle 14.

For example, as shown in FIG. 4A, vertical and horizontal L &
In the case of a circuit pattern mainly composed of S, FIG.
An effective light source having a shape as shown in (B) is desirable. At this time, it is preferable that the optical element 6 is composed of a quadrangular pyramid prism as shown in FIG. 4C, and the diaphragm member 10 has four openings as shown in FIG. 4D.

When emphasis is placed on the resolution of isolated patterns, the conventional illumination method as shown in FIG. 3 is preferable.

Further, in this embodiment, FIG. 2C and FIG.
Although only the illumination state of the two types of light intensity distribution shown in (C) is shown, another prism is attached to the holding member 21 of the optical element 6,
For example, if a conical prism or the like is arranged, the light intensity distribution on the incident surface 9a of the optical integrator 9 can be made to have a ring-shaped strong light intensity. In addition to this, by disposing prisms of various shapes at the position of the optical element 6, it is possible to variously change the above-mentioned light intensity distribution.

Further, in this embodiment, as shown in FIG. 1, the optical elements 6 and 8 and the diaphragm member 10 can be set only in the state of being put in the optical path or being retracted from the optical path.
By adding a plurality of optical elements or diaphragm members of different shapes to each of them, it becomes possible to set more illumination states.

In this case, the switching mechanism shown in FIG. 1 may be arranged, for example, to hold a plurality of optical elements or diaphragm members on a rotating disk and arrange any optical elements or diaphragm members in the optical path. Even in this case, the effects of the present invention can be similarly achieved by independently switching each optical element or diaphragm member by using an actuator such as a motor.

Further, as the information of the circuit pattern of the reticle when switching to the optimum illumination method in the present invention, for example, bar code information provided on the reticle may be read.
Alternatively, the programming may be performed in advance, or the image processing may be performed on the reticle pattern.

[0053]

According to the present invention, by considering the fineness and directionality of the pattern on the reticle surface to be projected and exposed, an optimal high-resolution projection exposure can be achieved by selecting an illumination system suitable for the pattern. A possible illumination device and a projection exposure apparatus using the same are achieved.

Further, according to the present invention, when exposing a not so fine pattern, the conventional illumination system can be used as it is, and when exposing a fine pattern, the loss of light amount is small and a high resolution can be easily achieved. The effect that a large depth of focus can be obtained by using the illuminating device that can exhibit is obtained.

[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.

FIG. 4 is an explanatory view of another embodiment of a part of FIG.

[Explanation of symbols]

 1 Light Source 2 Elliptical Mirror 3 Cold Mirror 5, 7, 11, 12 Lens System 6, 8 Optical Element 9 Optical Integrator 10 Aperture Member 14 Reticle 15 Projection Optical System 16 Wafer

Claims (4)

[Claims] 1. A light emitting section is arranged in the vicinity of a first focal point of an elliptic mirror, and an image of the light emitting section is formed in the vicinity of a second focal point of the elliptic mirror by the light flux from the light emitting section via the elliptic mirror. When illuminating a surface to be illuminated through an optical integrator in which a plurality of microlenses are two-dimensionally arranged by a light beam from the image of the light emitting unit, the incident light beam is deflected in a predetermined direction between the elliptic mirror and the optical integrator. An optical element that can be inserted into and removed from the optical path, an imaging system that forms an image of the light emitting unit on the incident surface of the optical integrator with different magnifications, and an incident surface or an exit surface of the optical integrator. An iris member that can be inserted and removed is disposed in the vicinity, and the optical element, the imaging system, and the iris member are selectively switched according to the pattern on the illuminated surface to be formed on the exit surface of the optical integrator. Light An illumination device characterized in that the intensity distribution is changed before use. 2. The optical integrator, the imaging system, and the diaphragm member are selectively switched so that the light intensity of the incident surface of the optical integrator is a rotationally symmetric second state in which the central portion is strong, and the optical intensity is smaller than that in the central portion. With a strong area in the periphery
2. The lighting device according to claim 1, wherein the state is selected. 3. A light emitting portion is arranged near the first focal point of the elliptic mirror, and an image of the light emitting portion is formed near the second focal point of the elliptic mirror through the elliptic mirror with a light beam from the light emitting portion, A pattern on the first object plane is illuminated through an optical integrator in which a plurality of microlenses are two-dimensionally arranged by a light flux from the image of the light emitting unit, and the pattern is projected on a second object plane through a projection optical system. When projection exposure is performed on the optical integrator, the optical element that can be inserted into and removed from the optical path that deflects the incident light beam in a predetermined direction between the elliptic mirror and the optical integrator, and the image of the light emitting unit are different on the incident surface of the optical integrator. An image forming system for forming a switchable image at a different magnification, and a diaphragm member that can be inserted and removed in the vicinity of the incident surface or the exit surface of the optical integrator, and the optical element according to the pattern on the irradiated surface, Imaging system and diaphragm member Is selectively switched to change the light intensity distribution on the incident surface of the optical integrator to adjust the light intensity distribution on the pupil plane of the projection optical system. 4. The light intensity distribution on the entrance surface of the optical integrator is changed by selectively switching the optical element, the image forming system, and the diaphragm member so that the light intensity on the pupil plane of the projection optical system is the center. 4. The projection exposure apparatus according to claim 3, wherein the second state in which the portion has strong rotational symmetry and the first state in which the peripheral portion has a stronger region than the central portion is selected.