JPH09190967A - Illuminator, and observation device using it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To lighten the intensity distribution irregularity and light distribution property irregularity at the emission end face of a fiber, on the emission face of a distribution board, so as to equalize the illumination, by combining light guide elements such as optical fibers, etc., and light diffusion elements such as diffusion plates, etc., properly. SOLUTION: A luminous flux emitted from a light source 11 enters an optical fiber handle 13, passing through an optical system 12. The luminous flux having entered the optical fiber handle 13 goes out of an emission end 13b, and goes out from the emission face 16b of the diffusion plate 16 through a diffusion plate 14 and an optical rod 15. Then, the luminous flux from the diffusion plate 16 converges on a view stop 18 through a capacitor lens 17. The position of this view stop 18 is conjugate with an observed face 1 and the photoelectric transfer face 6a of an image pickup element 6. Moreover, the luminous flux of an angle θ2 smaller than the extent angle θ1 of the luminous flux form the diffusion plate 16 is taken in by a capacitor lens 17, by setting the the capacitor lens 17 and the diameter of aperture of the view stop 18 properly.

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 an observing device using the illuminating device, and more particularly to a projection lens system (projection optical system) for forming a fine electronic circuit pattern such as IC or LSI formed on a reticle (mask) surface. System) to observe the state (alignment mark) on the reticle surface or the wafer surface when projecting and exposing on the wafer surface, and aligning the reticle and the wafer by this, thereby achieving a highly integrated semiconductor device. It is suitable for a projection exposure apparatus to be manufactured.

[0002]

2. Description of the Related Art Conventionally, in a reduction projection type exposure apparatus for manufacturing a semiconductor device, a circuit pattern of a reticle as a first object is projected by a projection lens system onto a wafer as a second object and exposed. At this time, the alignment mark on the wafer is detected by observing the wafer surface with an observing device (detecting means) prior to the projection exposure, and the so-called alignment of the reticle and the wafer is performed based on the detection result. ing. The alignment accuracy at this time largely depends on the optical performance of the observation device. Therefore, the performance of the observation apparatus is an important factor in the exposure apparatus.

Conventionally, in an exposure apparatus, various methods have been used as an observation method of a wafer alignment mark (wafer mark) for obtaining position information on the wafer surface.

For example, the applicant of the present invention has disclosed a method of using non-exposure light and passing through a projection lens system in Japanese Patent Laid-Open No. 3-61802.
An observation device is proposed in which alignment is performed using the so-called non-exposure light TTL method.

In the publication, an optical image of an alignment mark (wafer mark) on the wafer surface is formed on an image pickup device such as a CCD camera, and image information obtained from the image pickup device is processed to detect the position of the wafer mark. doing.

Further, the present applicant has filed Japanese Patent Application Laid-Open No. 62-232504.
Japanese Patent Laid-Open Publication No. 2005-242242, an optical image of a wafer mark is formed by a CCD camera, image information obtained by the CCD camera is binarized, and the position coordinates of a specific image pattern in the binarized image are template-matched using a template. It proposes a position detection device that detects the position of the wafer mark by performing the above-mentioned procedure and performs alignment between the reticle and the wafer.

[0007]

To align the mask (reticle) and the wafer with each other, a pattern (alignment pattern) provided on the surface of the reticle and the wafer is formed on the surface of the image pickup device and observed. An observing system that can observe the wafer surface in a good condition is an important factor.

Conventionally, as an illumination system for illuminating an object surface such as a mask (reticle) or a wafer surface, a light beam from a light source is guided to a predetermined position by using a fiber or an optical rod. After that, the light is condensed by an optical system such as a condenser lens to uniformly illuminate the object surface.

Generally, when an optical system in which a fiber and a lens system are combined is used, the object surface can be illuminated in a relatively uniform state. However, it is difficult to uniformly illuminate the object surface unless there is an optical defect that causes nonuniformity or uneven illuminance in the fiber or the optical rod itself, or if each element of the illumination system is not properly configured.

The present invention illuminates a pattern (alignment pattern) provided on an object surface (observed surface) such as a reticle or a wafer with a uniform illuminance by an appropriately set illumination device to form a pattern on the object surface. The reticle and the wafer are aligned with high accuracy by forming them on a predetermined surface of the image sensor with high accuracy, and observing and detecting the positional information of the pattern with high accuracy, facilitating highly integrated semiconductor devices. It is an object of the present invention to provide an illuminating device that can be manufactured as described above and an observing device using the same.

Particularly, by appropriately combining a light guide element such as an optical fiber and a light diffusing element such as a diffusing plate, which constitute the illuminating device, unevenness in intensity distribution and unevenness in light distribution characteristics on the exit end face of the fiber are projected. And a viewing device using the lighting device, which is capable of greatly reducing the size on the exit surface of the diffuser plate, which corresponds to the pupil surface of the device, and easily achieving uniform illumination on the surface to be observed, and which enables highly accurate pattern detection. For the purpose of providing.

[0012]

(1-1) When illuminating an object plane with a light beam from a light source means through an illumination optical system, (1-1) a light source means side in the illumination optical system. A first light diffusing element for diffusing and emitting incident light in order from
A light guide element for guiding a light beam from the light diffusing element, and a second light diffusing element which is disposed on the emission surface of the light guiding element or a surface conjugate with the light guide element and diffuses and outputs the light beam from the photoconductive element. It is characterized in that the light diffusing means is provided and an optical member having a numerical aperture for taking in a light flux having a divergence angle of the light flux from the light diffusing means or less is provided.

In particular, (1-1-1) the optical member has a diaphragm for limiting the numerical aperture. (1-1-2) The light guide element has an optical fiber and / or an optical rod. (1-1-3) The first and second light diffusing elements are made of isotropically diffusing plates or holograms with controlled diffusion angles. And so on.

(1-2) When illuminating the object plane with the light flux from the light source means through the illumination optical system, an optical element having a predetermined refractive power in the illumination optical system and a light flux in order from the light source means side. A light diffusing means having a light guiding element for guiding the light, and a light diffusing element disposed on the exit surface of the light guiding element or a surface conjugate with the light guiding element, for diffusing and outputting the light flux from the photoconductive element, and It is characterized in that an optical member having a numerical aperture for taking in a light flux having a spread angle of the light flux from the diffusing means or less is provided.

In particular, (1-2-1) the optical member has a diaphragm for limiting the numerical aperture. (1-2-2) The light guide element has an optical fiber and / or an optical rod. And so on.

The observing device of the present invention is (2-1) the illuminating device according to the above-mentioned structural requirements (1-1) or (1-2), illuminating the object plane, and observing the object plane with an observing optical system. The feature is that it is formed on the surface and observed.

The semiconductor device manufacturing method of the present invention comprises: (3-1) illuminating the reticle surface or the wafer surface with the illuminating device having the above-mentioned constitutional requirements (1-1) or (1-2), and illuminating the reticle surface. Alternatively, after the alignment between the reticle and the wafer is performed using an observation system for observing the wafer surface, the pattern on the reticle surface illuminated by the exposure light is projected and exposed on the wafer surface by the projection optical system to expose the wafer. It is characterized in that a semiconductor device is manufactured through a developing process.

The projection exposure apparatus of the present invention (4-1) aligns the reticle and the wafer using an observation system that illuminates the reticle surface or the wafer surface and observes the reticle surface or the wafer surface. After that, the pattern on the reticle surface illuminated by the exposure light is projected and exposed on the wafer surface by the projection optical system.

[0019]

1 is a schematic view of a main part of a first embodiment of an illuminating apparatus and an observing apparatus using the same according to the present invention, and FIG. 2 is an explanatory view of a part of FIG. First, each element of this embodiment will be described in the order in which the light flux travels.

Reference numeral 11 in the drawing denotes a light source means (light source), which is composed of a laser, a halogen lamp or the like. Light source 1
The light flux emitted from the optical fiber 1 passes through the optical system 12 and is shaped into a predetermined beam system.
Incident on.

The light flux incident on the optical fiber bundle 13 is transmitted through the optical fiber bundle 13, emitted from the emission end 13b of the optical fiber bundle 13 as shown in FIG. 2, and thereafter, the diffusion plate attached immediately after the emission end 13b. (First light diffusing element) 14, optical rod (light guiding element) 15 and diffusion plate (second light diffusing element)
The light is emitted from the emission surface 16b of the light source 16. At this time, the diffusion plate 16
The exit surface 16b of each element is set so as to be formed on the pupil plane of the projection optical system 2 described later.

The position of the diffusing plate 16 may be anywhere near the emission surface 15b of the optical rod 15 or a surface optically conjugate with it. For example, as shown in FIG. 7, the condenser lens 17 is composed of two lens groups 17a and 17b, and the diffusion plate 1 is formed at the image forming position (conjugate surface) of the exit surface 15b of the optical rod 15 by the lens group 17b.
6 may be arranged.

The light flux from the diffusion plate 16 passes through a condenser lens (optical member) 17 and is focused on a field stop 18 which determines the illumination range of the surface 1 to be observed. This field stop 18
The position of is at a position conjugate with the surface to be observed 1 and the photoelectric conversion surface 6a of the image sensor 6 which will be described later.

In this embodiment, the aperture diameters of the condenser lens (optical member) 17 and the field stop 18 are appropriately set, and the angle θ2 of the light beam from the diffusion plate 16 is smaller than the angle θ1.
The light flux is captured by the condenser lens 17. As a result, the observation surface 1 is uniformly illuminated as described later.

The light flux passing through the field stop 18 passes through the relay lens 19 and enters the polarization beam splitter 4.
Of the light beams incident on the polarization beam splitter 4, the light beam of the S-polarized component is reflected. Polarizing beam splitter 4
The light flux of the P-polarized component that has passed through is processed by an absorber (not shown) so as not to become stray light.

The light beam reflected by the polarization beam splitter 4 becomes circularly polarized light by passing through the λ / 4 plate 3, passes through the objective lens (projection optical system) 2, and then illuminates the surface to be observed 1.

The light reflected from the surface to be observed 1 passes through the objective lens 2 and then enters the λ / 4 plate 3 again. The light incident on the λ / 4 plate 3 is changed from circularly polarized light to linearly polarized light of a P-polarized component with respect to the polarization beam splitter 4, and passes through the polarization beam splitter 4 as it is. After that, the light flux passes through the relay lens 5 and forms an image of the observed surface 1 on the photoelectric conversion surface 6a of the image pickup element 6.

In this embodiment, the surface to be observed 1 is uniformly illuminated by the light flux from the light source means 11 through the illumination system (12 to 19) as described above, and the pattern on the surface to be observed 1 is observed by the optical system. (4-5) is formed on the image sensor 6. Then, the position of the pattern on the observation surface is detected using the image information from the image sensor 6.

The surface to be observed 1 is observed by using the observation apparatus of this embodiment.
2 is observed, even if there is unevenness in the intensity distribution of the exit end 13b of the optical fiber bundle 13 due to the diffusion plate 14 as shown in FIG.
The light flux emitted from each point of 5a spreads in a predetermined manner at the exit end 15b. In particular, even light such as laser light having a small divergence angle is reliably spread to a predetermined size at the emission end 16b of the diffusion plate 16.

In the present embodiment, the condenser lens 17 takes in a light beam with an angle θ2 smaller than the spread angle θ1 of the light beam from the diffuser plate 16, so that the influence of the intensity distribution on the emission end face 13b of the optical fiber bundle 13 is greatly affected. Has eased. That is, as shown in FIG. 2, the unevenness of the intensity distribution and the unevenness of the light distribution characteristic on the emission surface 16b of the diffusion plate 16 are greatly reduced.

In the present embodiment, the surface 1 to be observed is uniformly illuminated by such a structure. In the present embodiment, when the observed surface 1 has a pattern as shown in FIG. 3A, for example, the imaging element 6 can obtain a good observation waveform as shown in FIG. 3B. Thereby, the position information of the pattern on the observed surface 1 is detected with high accuracy. For example, when a wafer or the like is used as the observed surface, the position of the wafer mark provided on the surface is detected with high accuracy. This makes it easy to perform highly accurate alignment with the reticle.

When the observation apparatus shown in FIG. 1 in the first embodiment is used as a projection exposure apparatus for manufacturing a semiconductor device in which the pattern on the reticle surface is projected and exposed on the wafer surface by the projection optical system 2, the observed surface 1 A wafer is provided on the substrate, and the reticle is arranged at a position conjugate with the wafer with respect to the projection optical system 2.

Then, each element 1 is formed by the light flux from the light source means 11.
The reticle and wafer using an observation system (4, 5, 6) for illuminating the reticle surface or the wafer surface through an illumination system having 2 to 19 and observing a pattern on the reticle surface or the wafer surface. After aligning with, the pattern on the reticle surface illuminated with exposure light is projected and exposed on the wafer surface by the projection optical system.

The projection-exposed wafer is then subjected to a known developing process to manufacture a semiconductor device.

FIGS. 4 to 6 are schematic views of main parts of a part of Embodiments 2, 3 and 4 of the lighting device of the present invention. Embodiment 2 of FIG. 4 is different from Embodiment 1 of FIG. 1 in that a diffusion plate 14 is provided between the optical rod 15 and the optical fiber bundle 13.
The difference is that an optical system 21 having a positive power is arranged instead of, and other configurations are the same.

In this embodiment, the exit end face 13b of the optical fiber bundle 13 and the diffuser plate 16 have an image-pupil relationship by the optical system 21. That is, the exit end face 13b and the field stop 18 are conjugated. As a result, the emission end face 16b of the diffusion plate 16 is in a state where there is no unevenness in the intensity distribution of the emission end face 13b of the optical fiber bundle 13. On the other hand, when the above is done, the emission end face 13b of the optical fiber bundle 13 becomes an image plane, and has a conjugate relationship with the observed surface 1.

In this embodiment, since the diffuser plate 16 is disposed midway, the intensity distribution unevenness on the emission end face of the optical fiber bundle 13 is hardly transmitted.

As a result, the unevenness of the intensity distribution and the unevenness of the light distribution characteristic on the exit surface 16b of the diffuser plate 16 are greatly reduced, and the observed surface 1 is uniformly illuminated as shown in FIG. 3 (A). If the observation optical system has no aberration, a symmetrical good observation waveform can be obtained as shown in FIG.

The third embodiment shown in FIG. 5 is different from the first embodiment shown in FIG. 1 in that the optical rod 15 and the fiber bundle 13 are provided.
The difference lies in that an optical system 22 having a negative power is arranged in place of the diffusion plate 14 between them, and the other configurations are the same.

In this embodiment, even if a light beam having a small divergence angle is emitted from the emission surface 13b of the optical fiber bundle 13, the optical system 22 widens the angle of the light beam. As a result, the intensity distribution unevenness of the emission end face 16b of the diffusion plate 16 on the emission end face 13b of the optical fiber bundle 13 is significantly reduced.

In this embodiment, when the length of the optical rod 15 is L and the focal length of the optical system 22 is f, f ≦ L (1)

As a result, the unevenness of the intensity distribution and the unevenness of the light distribution characteristic on the exit surface 16b of the diffusion plate 16 are greatly reduced, and the surface to be observed is illuminated uniformly as shown in FIG. 3 (A). If the observation optical system has no aberration, it is possible to obtain a symmetrical good observation waveform as shown in FIG.

The fourth embodiment shown in FIG. 6 is different from the first embodiment shown in FIG. 1 in that a diffusion plate 14 'and an optical rod 15' are further arranged between the optical rod 15 and the diffusion plate 14. Other configurations are the same.

In the present embodiment, for the sake of simplification of description, a configuration using two optical rods and three diffuser plates as a whole is shown, but the number of combined configurations may be increased if necessary.

By making the configuration of the optical rod and the diffusing plate 16 multi-staged, the intensity distribution and the light distribution characteristics are made more uniform, and the intensity distribution unevenness of the emitting end face 13b of the optical fiber bundle 13 at the emitting end face 16b of the diffusing plate 16 is made more uniform. Has been significantly reduced. Thereby, the exit surface 16 of the diffusion plate 16
The intensity distribution unevenness and the light distribution characteristic unevenness in b are significantly reduced, and the observed surface 4 is uniformly illuminated as shown in FIG. If the observation optical system has no aberration, it is possible to obtain a symmetrical good observation waveform as shown in FIG.

Although the observation apparatus of the present invention uses the light guide element, the light guide element may not be used if the light quantity has a margin. Further, if it is desired to suppress the loss of the amount of light as much as possible, a hologram or the like whose diffusion angle is controlled may be used instead of the diffusion plate.

Next, an embodiment of a device manufacturing method using the above-described exposure apparatus will be described.

FIG. 8 shows a flow of manufacturing a semiconductor device (semiconductor chip such as IC or LSI, or liquid crystal panel, CCD or the like).

In step 1 (circuit design), a semiconductor device circuit is designed. Step 2 is a process for making a mask on the basis of the circuit pattern design.

On the other hand, in step 3 (wafer manufacturing), a wafer is manufactured using a material such as silicon. Step 4
The (wafer process) is called a pre-process, and an actual circuit is formed on the wafer by lithography using the prepared mask and wafer.

The next step 5 (assembly) is called a post-process, which is a process of forming a semiconductor chip by using the wafer manufactured in step 4, an assembly process (dicing, bonding), a packaging process (chip encapsulation). Etc. are included.

In step 6 (inspection), the semiconductor device manufactured in step 5 undergoes inspections such as an operation confirmation test and a durability test. Through these steps, a semiconductor device is completed and shipped (step 7).

FIG. 9 shows a detailed flow of the wafer process. Step 11 (oxidation) oxidizes the wafer's surface. Step 12 (CVD) forms an insulating film on the wafer surface.

In step 13 (electrode formation), electrodes are formed on the wafer by vapor deposition. In step 14 (ion implantation), ions are implanted into the wafer. Step 15
In (resist processing), a photosensitive agent is applied to the wafer. Step 16 (exposure) uses the above-described exposure apparatus to print and expose the circuit pattern of the mask onto the wafer.

In step 17 (development), the exposed wafer is developed. In step 18 (etching), portions other than the developed resist image are removed. In step 19 (resist stripping), the resist that has become unnecessary after the etching is removed. By repeating these steps, multiple circuit patterns are formed on the wafer.

By using the manufacturing method of this embodiment, it is possible to manufacture a highly integrated semiconductor device which has been difficult to manufacture in the past.

[0057]

EFFECTS OF THE INVENTION According to the present invention, as described above, (i) uniform illumination can be obtained by an illumination device in which a pattern (alignment pattern) provided on an object surface (observed surface) such as a reticle or a wafer is appropriately set. By illuminating the object surface, the pattern on the object surface is formed on a predetermined surface such as an image sensor with high accuracy, and the positional information of the pattern is observed and detected with high accuracy, so that the alignment between the reticle and the wafer is performed with high accuracy. Done in
It is possible to achieve an illuminating device and an observing device using the illuminating device, which can easily manufacture a highly integrated semiconductor device.

(B) By appropriately combining the light guiding element such as an optical fiber and the light diffusing element such as a diffusing plate which constitute the illuminating device, uneven intensity distribution and uneven light distribution characteristic on the exit end face of the fiber are projected. We used a lighting device and a lighting device that significantly reduced light on the exit surface of the diffuser plate, which corresponds to the pupil surface of the optical system, and could easily achieve uniform illumination on the surface to be observed, enabling highly accurate pattern detection. An observation device can be achieved.

(C) By providing a diffusing plate or an optical element having power between the exit end of the fiber bundle and the optical rod, even if the light flux has a small divergence angle, the light exits from each point of the entrance end of the optical rod. Since the light spreads at the exit end by a predetermined amount, the unevenness of the intensity distribution on the exit end face of the fiber bundle, and the unevenness of the light distribution characteristics, before the light flux reaches the diffuser plate at the exit end,
Be homogenized.

As a result, the unevenness of the intensity distribution and the unevenness of the light distribution on the exit end face of the fiber are significantly reduced on the exit face of the diffuser plate corresponding to the pupil plane, and uniform illumination on the observed surface can be achieved. , Enabling highly accurate patterns.

[Brief description of the drawings]

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

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

FIG. 3 is an explanatory diagram of an illumination distribution and an observation waveform on the observation surface of FIG.

FIG. 4 is a schematic view of a main part of a part of a second embodiment of the present invention.

FIG. 5 is a schematic view of a main part of a part of a third embodiment of the present invention.

FIG. 6 is a schematic view of a main part of a portion of Embodiment 4 of the present invention.

FIG. 7 is an explanatory view of another embodiment of a part of FIG. 1;

FIG. 8 is a flowchart of a method for manufacturing a semiconductor device according to the present invention.

FIG. 9 is a flowchart of a method for manufacturing a semiconductor device according to the present invention.

[Explanation of symbols]

 1 Observation Surface (Wafer) 2 Projection Optical System 3 λ / 4 Plate 4 Polarization Beam Splitter 6 Imaging Element 11 Light Source Means 12 Optical System 13 Optical Fiber Bundle (Light Guide Element) 14 First Light Diffusing Element (Diffusing Plate) 15 Optical Rod 16 Second light diffusing element (diffusing plate) 17 Optical member (condenser lens) 18 Aperture stop 19 Relay lens

Claims (10)

[Claims] 1. A first light diffusing element for diffusing and emitting incident light in the illumination optical system in order from the light source means side when illuminating an object surface with a light flux from the light source means through the illumination optical system, A light guide element that guides the light beam from the first light diffusion element, and a second light diffusion element that is arranged on the emission surface of the light guide element or on a surface conjugate therewith and diffuses and outputs the light beam from the photoconductive element. And a light diffusing unit having an optical member having a numerical aperture for taking in a light beam having a divergence angle or less from the light diffusing unit. 2. The illumination device according to claim 1, wherein the optical member has a diaphragm that limits the numerical aperture. 3. The illumination device according to claim 1, wherein the light guiding element has an optical fiber and / or an optical rod. 4. The illumination device according to claim 1, wherein the first and second light diffusing elements are made of a diffusion plate that isotropically scatters or a hologram whose diffusion angle is controlled. 5. When illuminating an object surface with a light flux from a light source means through an illumination optical system, an optical element having a predetermined refractive power and a light flux are guided in the illumination optical system in order from the light source means side. And a light diffusing element having a light diffusing element which is disposed on the exit surface of the light guiding element or a surface conjugate with the light guiding element and diffuses and emits the light flux from the photoconductive element. An illuminating device comprising an optical member having a numerical aperture for taking in a light flux having a divergence angle of the light flux or less. 6. The illumination device according to claim 5, wherein the optical member has a diaphragm that limits the numerical aperture. 7. The lighting device according to claim 5, wherein the light guide element has an optical fiber and / or an optical rod. 8. The object plane is illuminated by the illuminating device according to claim 1, and the object plane is formed on a predetermined plane by an observation optical system for observation. Observation device. 9. An illumination system according to claim 1, which illuminates a reticle surface or a wafer surface, and utilizes an observation system for observing the reticle surface or the wafer surface to form the reticle and the wafer. After alignment, the pattern on the reticle surface illuminated by exposure light is projected and exposed on the wafer surface by the projection optical system, and the wafer is manufactured into semiconductor devices through a developing process. And a method for manufacturing a semiconductor device. 10. An illumination system according to claim 1, wherein the reticle surface or the wafer surface is illuminated by an illuminating device, and an observation system for observing the reticle surface or the wafer surface is used to separate the reticle and the wafer. A projection exposure apparatus, wherein a pattern on a reticle surface illuminated by exposure light after performing alignment is projected and exposed on a wafer surface by a projection optical system.