JPH0766121A - Projection aligner and fabrication of semiconductor element employing it - Google Patents

Abstract

PURPOSE:To facilitate transfer of various pattern on the surface of a reticle onto the surface of a wafer with high resolution by disposing one of a plurality of filters with diaphragm, arranged oppositely to optical elements applied with coating having transmittance variable with the diaphragm and the incident angle, on the optical path. CONSTITUTION:A filter mechanism with diaphragm 7 comprises a plurality of filters with diaphragm 7a, 7b... arranged in turret. The filter with diaphragm 7a, for example, comprises a diaphragm 7a1 and an optical element 7a2 applied with a coating having transmittance variable with the incident angle disposed integrally while opposing each other. When the filter mechanism with diaphragm 7 is employed, the distribution of optical intensity on the pupil plane 14 of a projection optical system 13 when the incident flux to a condenser lens 8 is varied, i.e., the illuminance distribution on the illumination plane or a reticle 12 when the effective light source distribution is varied, can be controlled appropriately.

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 semiconductor device manufacturing method 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 provided with an appropriate illuminance distribution. The high luminous flux is used to illuminate and a high resolution can be easily obtained.

[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 microfabrication technology with submicron resolution, with the production of 1M DRAM semiconductor devices as the boundary. In many cases, a method of fixing the exposure wavelength and increasing the NA (numerical aperture) of the optical system has been used as a means for improving the resolution.

Recently, however, various attempts have been made to improve the resolution by changing the exposure wavelength from g-line to i-line and using an exposure method using an ultra-high pressure mercury lamp. In addition, various methods have been proposed for improving the resolution by using light of 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.

In addition to this, the present applicant changes the illumination method on the reticle surface, that is, changes the light intensity distribution (effective light source distribution) formed on the pupil surface of the projection optical system accordingly. As described above, an exposure method with a higher resolution and a projection exposure apparatus using the same are disclosed in, for example, Japanese Patent Laid-Open No. 5-47.
626, JP-A-5-47628, and JP-A-5
-47639 gazette etc.

[0005]

There are various actual manufacturing processes of a semiconductor integrated circuit, such as a process requiring a high pattern resolution performance and a process not requiring such a pattern resolution performance. Further, the pattern shape formed on the reticle surface includes various horizontal and vertical patterns as well as oblique patterns.

Generally, the effective light source distribution (light intensity distribution) on the pupil plane of the projection optical system (projection lens) greatly affects the image performance (resolution) of the projected pattern image. For this reason, there is a demand for an illumination system capable of illuminating the present exposure apparatus for manufacturing semiconductor devices by an optimum method for each process.

Generally, when trying to control various light intensity distributions on the pupil plane of the projection optical system by using diaphragms having different aperture shapes, the illuminance distribution on the reticle plane may become non-uniform.

The present invention uses diaphragms having different aperture shapes,
Adjust the non-uniformity of the illuminance distribution on the reticle surface that occurs when the effective light source distribution on the pupil plane of the projection optical system is changed by using an optical element having appropriate spectral characteristics,
An object of the present invention is to provide a projection exposure apparatus capable of easily exposing and transferring various patterns on a reticle surface onto a wafer surface with high resolution, and a semiconductor element manufacturing method using the projection exposure apparatus.

[0009]

The projection exposure apparatus of the present invention is (1-1) illuminating a light beam from a light source with a lighting system to a pattern on a surface to be illuminated, and projecting the pattern onto a substrate surface with a projection optical system. The optical system for condensing the light flux from the light source to form a secondary light source and projecting the secondary light source into an image in the vicinity of the pupil plane of the projection optical system when the image is projected and exposed on the optical system. It has a filter mechanism with a diaphragm provided with a plurality of filters with a diaphragm that opposes a diaphragm that restricts a light flux emitted from a next light source and an optical element having a coating having a different transmittance depending on an incident angle. One of these is selected and placed in the optical path to control the illuminance distribution on the illuminated surface.

According to the method of manufacturing a semiconductor element of the present invention, (1-2) a pattern on the reticle surface is illuminated with a light flux from a light source by an illumination system, and the pattern is projected onto a wafer surface by a projection optical system for exposure. Later, when a semiconductor element is manufactured on the wafer through a developing process, the illumination system collects a light beam from the light source to form a secondary light source, and the secondary light source is used as a pupil of the projection optical system. Illuminance distribution on the reticle surface by using a filter with a diaphragm in which a diaphragm for forming an image near the surface and limiting a light flux emitted from the secondary light source and an optical element with a coating having a different transmittance depending on the incident angle are arranged to face each other. It is characterized by controlling.

[0011]

Embodiment 1 FIG. 1 is a schematic view of the essential portions of Embodiment 1 of the present invention.

In the figure, 2 is an elliptical mirror. Reference numeral 1 denotes a light emitting tube as a light source, which has a light emitting portion 1a of high brightness that emits ultraviolet rays, far ultraviolet rays, and the like. The light emitting unit 1a is arranged near the first focus of the elliptical mirror 2. Reference numeral 3 denotes a cold mirror, which is composed of a multilayer film and transmits most of infrared light and reflects most of ultraviolet light. The elliptic mirror 2 forms a light emitting portion image (light source image) 1b of the light emitting portion 1a in the vicinity of the second focal point 4 via the cold mirror 3.

An optical system 5 is composed of a condenser lens, a zoom lens, etc., and the light emitting portion image 1b formed in the vicinity of the second focal point 4 is incident on the incident surface 6 of the optical integrator 6.
The image is formed on a. The optical integrator 6 includes a plurality of minute lenses (fly's eye lenses) 6-i (i = 1 to 1).
N) are arranged two-dimensionally at a predetermined pitch, and a secondary light source is formed near the exit surface 6b.

Reference numeral 7 denotes a filter mechanism with an aperture, which is constructed by arranging a plurality of filters with apertures 7a, 7b ... In a turret type. Among them, for example, the filter 7a with a diaphragm is configured such that a diaphragm 7a1 and an optical element 7a2 coated with a coating having a different transmittance depending on an incident angle are integrally attached or are arranged to face each other with a slight gap. .

As the diaphragm 7a1, an ordinary circular aperture diaphragm or an annular illumination diaphragm for changing the light intensity distribution on the pupil plane 14 of the projection lens 13 described later as shown in FIGS. 2A and 2B. And quadrupole illumination diaphragm, etc. The same applies to the other filters with diaphragms 7b, 7c ....

Numeral 16 is an actuator for rotating the filter mechanism 7 with a diaphragm so that arbitrary filters with a diaphragm 7a, 7b ... Are positioned in the optical path.

In this embodiment, the filter mechanism 7 with a diaphragm is used.
Is used to change the luminous flux incident on the condenser lens 8 variously, and the light intensity distribution on the pupil plane 14 of the projection optical system 13,
That is, the illuminance distribution on the reticle 12 as the irradiation surface when the effective light source distribution is changed variously is appropriately controlled.

The condensing lens 8 condenses a plurality of light beams emitted from the secondary light source in the vicinity of the emission surface 6b of the optical integrator 6 and passed through the filter (7a) with a diaphragm, and the light beams are reflected by the mirror 9 to be masked by the masking blade 10. Oriented towards
The masking blade 10 surface is uniformly illuminated. The masking blade 10 is composed of a plurality of movable light shielding plates,
An arbitrary opening shape is formed.

Reference numeral 11 denotes an imaging lens, which transfers the opening shape of the masking blade 10 onto the surface of the reticle 12 as a surface to be illuminated and uniformly illuminates a necessary area on the surface of the reticle 12.

Reference numeral 13 is a projection optical system (projection lens),
The circuit pattern on the surface of the reticle 12 is reduced and projected onto the surface of the wafer (substrate) 15 placed on the wafer chuck. 1
Reference numeral 4 is a pupil plane of the projection optical system 13.

In the optical system of this embodiment, the light emitting section 1a
The second focal point 4 and the incident surface 6a of the optical integrator 6 have a substantially conjugate relationship. Further, the masking blade 10, the reticle 12, and the wafer 15 are in a conjugate relationship. Further, the diaphragm 7a1 and the pupil plane 14 of the projection optical system 13 have a substantially conjugate relationship.

In the present embodiment, with the above-described structure, the pattern on the surface of the reticle 12 is reduced and projected onto the surface of the wafer 15 by reduction projection exposure. Then, a semiconductor device is manufactured through a predetermined developing process.

In the present embodiment, the applicant of the present invention described in Japanese Unexamined Patent Publication No.
As disclosed in Japanese Laid-Open Patent Publication No. 47626 and Japanese Patent Laid-Open No. 5-47640, the pupil plane 14 of the projection optical system 13 is selected by using a diaphragm having a different aperture shape according to the pattern shape on the surface of the reticle 12. The light intensity distribution formed above is changed. At this time, the unevenness of the illuminance distribution on the surface of the reticle 12 is made uniform by using the optical element (7a2) provided with the coating film. This improves the resolution when the projection optical system 13 projects a pattern on the surface of the reticle 12 onto the surface of the wafer 15.

Next, in this embodiment, a method for controlling the illuminance distribution on the surface of the reticle 12 by using an optical element having a coating film whose transmittance varies depending on the incident angle will be described.

FIG. 3 is an explanatory view of an optical thin film (coating film) applied to the filter 7a with a diaphragm of FIG. The figure shows the spectral characteristics of an optical thin film that exhibits high transmittance for a specific wavelength λ ₀ .

Λ ₀ is the exposure wavelength, and curve a is the incident angle θ =
0, the curve b is for the incident angle θ ≠ 0. Generally, the optical thin film shifts its spectral characteristic toward the short wavelength side when the incident angle becomes large, but in the case of the spectral characteristic such as the curve a having a narrow band of high transmittance, the spectral characteristic becomes short wavelength because the incident angle is not zero. It shifts to the side and becomes the state of curve b. The difference in transmittance at the exposure wavelength λ ₀ caused by the difference in incident angle at this time is ΔT.

The optical element of the present embodiment utilizes the above-mentioned spectral characteristics, and the filter 7a with a diaphragm is provided with an optical thin film whose spectral characteristics change sensitively to the incident angle of a light beam.

FIG. 4 is a partial explanatory view of the filter 7a with a diaphragm shown in FIG. The divergent light flux from the optical integrator 6 passes through the filter 7a with a diaphragm, is converged by the condenser lens 8, and illuminates the illuminated surface 10. The light with the same emission angle from the optical integrator 6 illuminates the same place on the illuminated surface 10.

That is, those having the same incident angle on the filter with aperture 7a will be incident on the same location on the illuminated surface 10, and the transmittance of the filter with aperture 7a will change depending on the incident angle. Since it is provided with an optical thin film, it functions to form an illuminance distribution on the irradiated surface 10 that is symmetrical with respect to the optical axis.

Therefore, by providing an optical thin film having a spectral characteristic for canceling the illuminance unevenness peculiar to the diaphragm on the filter with diaphragm 7, the illuminance unevenness on the surface of the reticle 12 is reduced. For example, when a ring-shaped aperture stop is used and the illuminance around the reticle surface is high with respect to the center, the transmittance of the optical element used as the ring-shaped aperture stop decreases as the incident angle increases. The type of optical thin film is applied.

FIG. 5 is a schematic view of the essential portions of Embodiment 2 of the present invention. In this embodiment, a filter 7 with a diaphragm is arranged near the exit surface 6b of the optical integrator 6, and the condenser lens 8 is provided with a drive mechanism 17 for moving at least one lens 8 along the optical axis. This is for adjusting the illuminance unevenness, which cannot be completely eliminated by the optical element of the filter with diaphragm 7, by moving the lens. Since a condenser lens having a drive mechanism can finely adjust the illuminance unevenness, by using these two elements at the same time, a more uniform illuminance distribution can be obtained on the reticle surface.

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

FIG. 6 shows a flow of manufacturing a semiconductor device (semiconductor chip such as IC or LSI, liquid crystal panel, CCD or the like). In step 1 (circuit design), a semiconductor device circuit is designed. In step 2 (mask manufacturing), a mask having the designed circuit pattern is manufactured.

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 a lithography technique using the mask and the wafer prepared above.

The next step 5 (assembly) is called a post-process, and is a process of forming a semiconductor chip 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, the semiconductor device is completed and shipped (step 7).

FIG. 7 shows a detailed flow of the wafer process. In step 11 (oxidation), the surface of the wafer is oxidized. In step 12 (CVD), an insulating film is formed 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 in the wafer. Step 15
In (resist processing), a photosensitive agent is applied to the wafer.

In step 16 (exposure), the circuit pattern of the mask is printed and exposed on the wafer by the exposure apparatus described above. In step 17 (development), the exposed wafer is developed. In step 18 (etching), parts other than the developed resist image are removed. In step 19 (resist stripping), the resist that is no longer needed after etching is removed. By repeating these steps, multiple circuit patterns are formed on the wafer.

By using the manufacturing method of this embodiment, a highly integrated semiconductor device can be manufactured.

[0039]

As described above, according to the present invention, the illuminance distribution on the reticle surface generated when various effective light source distributions on the pupil plane of the projection optical system are changed by using diaphragms having different aperture shapes. A projection exposure apparatus capable of adjusting the non-uniformity of the reticle by using an optical element having an appropriate spectral characteristic, and easily exposing and transferring various patterns on the reticle surface onto the wafer surface with high resolution and a projection exposure apparatus using the same. It is possible to achieve the above-described method of manufacturing a semiconductor device.

[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 view of the diaphragm shown in FIG.

3 is an explanatory diagram of spectral characteristics of the optical element of FIG.

FIG. 4 is an enlarged explanatory view of a part of FIG.

FIG. 5 is a schematic view of the essential portions of Embodiment 2 of the present invention.

FIG. 6 is a flowchart of a method for manufacturing a semiconductor device of the present invention.

FIG. 7 is a flowchart of a method for manufacturing a semiconductor device of the present invention.

[Explanation of symbols]

 1 Light Source 2 Elliptical Mirror 3 Cold Mirror 5 Optical System 6 Optical Integrator 7 Filter Mechanism with Aperture 7a, 7b ... Filter with Aperture 7a1, 7b1 ... Aperture 7a2, 7b2 ... Optical Element 8 Condensing Lens 9 Mirror 9a Half Mirror 10 Masking Blade 11 Imaging lens 12 Reticle 13 Projection optical system 14 Pupil plane 15 Reticle

Claims (2)

[Claims] 1. When a light beam from a light source is illuminated by an illumination system onto a pattern on a surface to be illuminated and the pattern is projected onto a substrate surface by a projection optical system for exposure, the illumination system reflects the light beam from the light source. An optical system that collects light to form a secondary light source and forms an image of the secondary light source in the vicinity of the pupil plane of the projection optical system, a diaphragm that limits the light flux emitted from the secondary light source, and a transmittance depending on the incident angle. It has a filter mechanism with a diaphragm provided with a plurality of filters with a diaphragm that opposes optical elements with different coatings, selects one from the plurality of filters with a diaphragm, and arranges it in the optical path for irradiation. A projection exposure apparatus characterized in that the illuminance distribution on the surface is controlled. 2. A semiconductor device is provided with a light beam from a light source, which illuminates a pattern on a reticle surface by an illumination system, projects the pattern on a wafer surface by a projection optical system to expose the wafer, and then develops the wafer through a developing process. In manufacturing, the illumination system collects the light flux from the light source to form a secondary light source, forms an image of the secondary light source in the vicinity of the pupil plane of the projection optical system, and outputs the light from the secondary light source. A semiconductor device characterized by controlling the illuminance distribution on the reticle surface by using a filter with a diaphragm in which a diaphragm for limiting the emitted light flux and an optical element with a coating having a different transmittance depending on the incident angle are arranged to face each other. Production method.