JPH07135145A - Aligner - Google Patents

Abstract

PURPOSE:To improve the light utilization of an aligner, by converting the nonlinearly polarized light from a light source to a linearly polarized light, and irradiating a pattern with the linear polarization light. CONSTITUTION:The light entering a polarization light beam splitter 21 is divided into transmitted light (P polarization light polarized in the direction of paper surface) and reflected light (S polarization light polarized in the direction vertical to paper surface), by the light dividing surface of the polarization beam splitter 21. The P polarization light is directed to the light incidence surface of an optical integrator 7 via a polarization element 27. The S polarization light is converted to a P polarization light by a halfwave plate 22, and directed to the light incidence surface of the optical integrator 7 via a polarization element 24. Thus secondary light sources formed in the vicinity of a light emission surface of a fly-eye lens of the optical integrator 7 are all P polarization lights, so that the lights illuminating a reticle 11 are all P polarization lights. Thereby the loss of light penetrating the reticle is not generated, and flare is not generated.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an exposure apparatus, and more particularly to an exposure apparatus used for manufacturing semiconductor devices such as IC and LSI, image pickup devices such as CCDs, display devices such as liquid crystal panels, and magnetic heads.

[0002]

2. Description of the Related Art Higher integration of semiconductor devices such as ICs and LSIs is accelerating more and more, and accompanying this, the progress of fine processing technology of semiconductor wafers is remarkable. The exposure technique, which is the center of this fine processing technique, is currently being improved in resolution in order to form an image of a size of 0.5 micron or less.

In the projection type exposure apparatus, there is a method of shortening the wavelength of the exposure light to improve the resolution, but when the wavelength is shortened, the type of glass material that can be used in the projection lens system is limited, so that correction of chromatic aberration is not possible. It gets harder. Therefore, in order to facilitate the correction of this chromatic aberration, an exposure apparatus using a catadioptric optical system including a concave mirror, a lens group, a polarization beam splitter, and a 1/4 wavelength plate has been proposed. This catadioptric optical system reflects light from the device pattern of the reticle on a concave mirror via a polarization beam splitter and a quarter wavelength plate, and then again on a substrate to be exposed via a quarter wavelength and a polarization beam splitter. Is to be incident on.

[0004]

However, in the conventional exposure apparatus, when a reticle is illuminated with non-linearly polarized light from a light source such as a mercury lamp, nearly half of the light from the device pattern of the reticle is a polarization beam splitter. Vignetting reduces the light utilization efficiency.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide an exposure apparatus with improved light utilization efficiency.

The exposure apparatus of the present invention is characterized by including means for converting non-linearly polarized light from a light source into linearly polarized light and illuminating a pattern with the linearly polarized light.

According to one aspect of the exposure apparatus of the present invention, the non-linearly polarized light from the light source is converted into linearly polarized light, and the linearly polarized light illuminates the pattern, and the pattern illuminated by the illuminating means is polarized. And a projection optical system for projecting on a substrate via a light splitter.

[0008] A form of the illuminating means includes an optical splitter for splitting the non-linearly polarized light from the light source into two light fluxes, and means for matching the polarization directions of the two light fluxes with each other.

A preferred form of the illuminating means is to change the polarization direction of one light beam so that the polarization directions of the two light beams coincide with each other and a polarization light splitter for dividing the non-linearly polarized light from the light source into two light beams. And a two-wave plate.

Another form of the illuminating means comprises a polarizing plate that converts the non-linearly polarized light from the light source into linearly polarized light.

According to an aspect of the present invention, the projection optical system reflects the light transmitted through the polarization splitter and makes the light incident on the polarization splitter at a concave mirror, and the light re-entering the polarization splitter is transmitted by the polarization splitter. The polarization splitter, the quarter wave plate disposed between the polarization splitter and the concave mirror to change the polarization direction of light passing through the polarization splitter to be reflected; Linearly polarized light polarized in substantially the same direction as the polarization direction of the light passing through.

Further, according to another aspect of the present invention, the projection optical system reflects the light reflected by the polarization splitter and causes the light to re-enter the polarization splitter, and the light re-enters the polarization splitter includes the polarization splitter. The polarization splitter and the quarter-wave plate arranged between the concave mirror to change the polarization direction of the light transmitted through the polarization splitter so that the polarization means transmits the polarization splitter. Linearly polarized light polarized in substantially the same direction as the polarization direction of the light reflected by the vessel.

By using the exposure apparatus of the present invention to manufacture semiconductor devices such as ICs and LSIs, image pickup devices such as CCDs, display devices such as liquid crystal panels, and magnetic heads, various excellent devices are provided.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a schematic block diagram showing an embodiment of an exposure apparatus of the present invention. This exposure apparatus is a scanning type exposure apparatus used for manufacturing semiconductor devices such as IC and LSI.

In FIG. 1, 1 is a light source that emits ultraviolet rays, such as a mercury lamp, and 1a is its light emitting portion. Reference numeral 2 is an elliptical mirror, and the light emitting unit 1 of the light source 1 is provided in the vicinity of the first focal point
Since a is arranged, the elliptical mirror 2 forms an image of the light emitting portion 1a at the second focal point 3 thereof. Therefore, the light from the light emitting unit 1 a is focused on the second focus 3 of the elliptical mirror 2. The light diverging from the second focal point 3 of the elliptical mirror 2 is converted into parallel light substantially parallel to the optical axis by the condenser lens 4, and enters the polarization beam splitter 21. The light incident on the polarization beam splitter 21 is transmitted light (P-polarized light polarized in the plane of the paper) and reflected light (S-polarized light polarized in the direction perpendicular to the plane of the paper) by the light splitting surface 21a of the polarization beam splitter 21.
It is divided into The transmitted light (P-polarized light) transmitted through the light splitting surface 21a of the polarization beam splitter 21 is directed to the light incident surface of the optical integrator 7 such as a fly-eye lens through a mirror 25, a condenser 26, and a deflecting element 27 such as a prism. It On the other hand, the polarization beam splitter 2
The reflected light (S-polarized light) reflected by the first light splitting surface 21 a passes through the half-wave plate 22 and passes through the half-wave plate 22.
Is converted into P-polarized light by the condenser 23, and is directed to the light incident surface of the optical integrator 7 via the condenser 23 and the deflecting element 24 such as a prism.

The fly-eye lens forming the optical integrator 7 is an assembly in which a plurality of minute lenses are regularly arranged, and a plurality of secondary light sources are formed near the light exit surface thereof.

Reference numeral 8 denotes a condenser lens, and the condenser lens 8 allows the optical integrator 7
The light flux from the secondary light source formed on the light emission surface of (1) is focused on the slit-shaped opening of the masking blade (field stop) 9 so as to perform Koehler illumination. Masking blade 9
The position of the slit-shaped opening of the reticle and the position of the device pattern of the reticle 11 are set optically conjugate by the imaging lens 10, and the image of the slit-shaped opening of the masking blade 9 is projected onto the reticle so that the slit-shaped light is reticle. The shape and size of the illumination area on the reticle 11 are defined by the shape and size of the opening of the masking blade 9.

The illumination area on the reticle 11 is formed by rectangular slit light having a short side in the scanning direction of the reticle. In order to efficiently illuminate a rectangular irradiation area of this kind, the fly-eye lens of the optical integrator 7 has a rectangular cross-sectional shape in its light incident surface and light emitting surface, as shown in FIGS.

The two P-polarized lights incident on the fly-eye lens of the optical integrator 7 are controlled so that the secondary light source formed near the light exit surface of the fly-eye lens has the intensity distribution shown in FIG. 3 (B). Aimed at the eye lens.
For example, as shown in FIG. 2, when the light entrance surface and the light exit surface of the fly-eye lens have a rectangular cross-sectional shape that is long in the y direction, two Ps from the direction that forms an angle with the optical axis with respect to the yz plane. This can be achieved by directing polarized light to the fly-eye lens. In addition, optical integrator 7
All the secondary light source formations formed in the vicinity of the light exit surface of the fly-eye lens are P-polarized light, so that the light that illuminates the reticle 11 is also P-polarized light.

Reference numerals 12 to 17 are catadioptric reduction projection optical systems, 12 is a positive lens, 13 is a polarization beam splitter (light splitter), 13a is a light splitting surface, 14 is a quarter wavelength plate, and 15 is negative. A lens, 16 is a concave mirror, and 17 is a positive lens.

The reticle 11 and the wafer 18 are arranged at optically conjugate positions with respect to the projection optical systems 12-17.
At that position, the projection optical systems 12 to 1 are driven by a driving device (not shown).
The reticle 11 moves in the y direction and the wafer 18 moves in the z direction at a constant speed ratio according to the magnification of 7. The device pattern on the reticle 11 is scanned across the illumination area on the slit, so that the device on the reticle 11 is scanned. The pattern is transferred onto the wafer 18.

The P-polarized light transmitted through the device pattern of the reticle 11 is converted by the lens 12 having a positive refracting power into a parallel light flux substantially parallel to the optical axis. P converted to parallel light flux
The polarized light passes through the polarization beam splitter 13 without any loss, and is converted into circularly polarized light by the quarter-wave plate 14. The incident light is transmitted through the polarization beam splitter 13 when it is P-polarized light, and when other S-polarized light is transmitted through the reticle 11 and is incident on the polarization beam splitter 13, the polarization beam splitter 13 Since the light is reflected by the reflecting surface 13a, it causes a light amount loss and flare. However, in the present embodiment, since the light transmitted through the reticle 11 is substantially all P-polarized light, the light amount loss and the flare are generated. No flare occurs. The circularly polarized light from the quarter-wave plate 14 is diverged by the lens 15 having a negative refractive power, reflected and condensed by the concave mirror 16, and then enters the lens 15 having a negative refractive power again. The circularly polarized light emitted from the lens 15 having a negative refracting power passes through the quarter-wave plate 14 again to be converted into S-polarized light, and enters the polarization beam splitter 13. This S-polarized light is reflected by the reflecting surface 13a of the polarization beam splitter 13, is focused on the wafer 18 via the lens 17 having a positive refractive power, and a reduced image of the device pattern of the reticle 11 is formed on the wafer 18. To form.

In the present embodiment, the light entrance / exit surface of the fly-eye lens of the optical integrator 7 has a rectangular shape elongated in the paper surface direction (y direction). However, when the illumination area of the reticle 11 is elongated in the direction perpendicular to the paper surface, Since the light entrance / exit surface of the fly-eye lens has a rectangular shape that is long in the direction (x direction) perpendicular to the paper surface, the two P-polarized lights are from the direction that forms an angle with the optical axis with respect to the xz plane perpendicular to the paper surface. Is incident on. The polarization directions of the two P-polarized lights in this case are set to the polarization directions in which all the lights that first enter the polarization beam splitter 13 of the projection optical systems 12 to 17 are transmitted.

In this embodiment, the luminous flux from the mercury lamp 1 is set to 2
Although it is divided into two light beams, the optical members such as a half mirror, a polarization beam splitter, and a wave plate are appropriately combined to divide the light beam from the mercury lamp 1 into three or more light beams, and each light beam vibrates in the same direction. The polarized light may be incident on the fly-eye lens of the optical integrator 7.

Further, the plurality of light beams obtained by the division are made into the same polarized light (for example, circularly polarized light) other than the linearly polarized light, and a quarter wave plate is arranged in front of or behind the fly-eye lens to form the reticle 1.
1 may be illuminated with a desired polarization direction.

In this embodiment, the cross-sectional shape of the fly-eye lens of the optical integrator 7 is rectangular and the incident directions of a plurality of light beams obtained by dividing the fly-eye lens are limited, but the cross-sectional shape of the fly-eye lens is limited. May be, for example, a square or a hexagon, and may be incident from any direction if the incident angle to the fly-eye lens has a sufficient margin.

In this embodiment, the light source is a mercury lamp having no polarization characteristic, but the light source may be a laser which emits light having no polarization characteristic. Further, the light source may be an excimer laser that emits light having a polarization characteristic that is narrow banded by a prism or the like.

In this embodiment, the polarization beam splitter 21
However, the light from the light source is divided into a plurality of light fluxes by a half mirror or the like, and the plurality of light fluxes are made incident on a polarization filter that converts them into a certain polarization component, and only the light of a desired polarization direction is selected, The reticle 11 may be illuminated.

In the present embodiment, the optical system for forming the device pattern of the reticle 11 on the wafer 18 is a catadioptric projection optical system, but the illumination device of the present invention is a refraction projection optical system such as a stepper. The present invention may be applied to an exposure apparatus including the above or an exposure apparatus including a reflection type projection optical system.

In this embodiment, the masking blade 9 and the reticle 11 are arranged at substantially conjugate positions by using the image forming lens 10. However, the reticle 11 of the reticle 11 is not provided through the image forming optical system such as the image forming lens 10. The masking blade 9 may be arranged in the vicinity.

Further, as another embodiment of the present invention, when a linear beam pattern of a reticle is projected without using a polarizing beam splitter in the projection optical system, linearly polarized light polarized in the direction in which the linear pattern to be projected extends. In order to supply light to the reticle, for example, the illumination optical system of the exposure apparatus shown in FIG. 1 is improved, a 1/2 wavelength plate is provided in front of and behind the optical integrator 7 of this illumination optical system, and the 1/2 wavelength plate is rotated. And change the polarization direction of the linearly polarized light incident on the reticle 11,
There is an exposure device capable of adjusting the polarization direction.

Next, an embodiment of a method of manufacturing a semiconductor device using each of the above exposure apparatuses will be described.

FIG. 4 shows a manufacturing flow of semiconductor devices (semiconductor chips such as IC and LSI, liquid crystal panels and CCDs). In step 1 (circuit design), the circuit of the semiconductor device is designed. In step 2 (mask manufacturing), a mask (reticle 304) on which the designed circuit pattern is formed is manufactured. On the other hand, in step 3 (wafer manufacturing), a wafer (wafer 306) is manufactured using a material such as silicon. Step 4 (wafer process) is called a pre-process, and an actual circuit is formed on the wafer by the lithography technique using the mask and the wafer prepared above. The next step 5 (assembly) is called a post-process, which is a process of making chips using the wafer prepared in step 4, and an assembly process (dicing, bonding
_B ring), a packaging process (chip encapsulation). 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. 5 shows a detailed flow of the wafer process. In step 11 (oxidation), the surface of the wafer (wafer 306) is oxidized. Step 12 (CV
In D), an insulating film is formed on the surface of the wafer. 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 (resist processing)
Then, a resist (photosensitive material) is applied to the wafer. In step 16 (exposure), the projection exposure apparatus exposes the wafer with an image of the circuit pattern of the mask (reticle 304). In step 17 (development), the exposed wafer is developed. In step 18 (etching), parts other than the developed resist are scraped off. In step 19 (resist stripping), the resist that is no longer needed after etching is removed. By repeating these steps, a circuit pattern is formed on the wafer.

The use of the manufacturing method of this embodiment makes it possible to manufacture highly integrated semiconductor devices.

[0036]

As described above, according to the present invention, it is possible to provide an exposure apparatus having high light utilization efficiency.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of an exposure apparatus for manufacturing a semiconductor device showing an embodiment of the present invention.

FIG. 2 is a schematic external view of a fly-eye lens.

FIG. 3 is an explanatory diagram of a secondary light source formed on a light exit surface of a fly-eye lens.

FIG. 4 is a flowchart showing manufacturing steps of a semiconductor device.

5 is a flow chart diagram illustrating details of a wafer process during the process of FIG.

[Explanation of symbols]

 1 Mercury Lamp 7 Fly-eye Lens 11 Reticle 13, 21 Polarization Beam Splitter 14 1 / Wave Plate 16 Concave Mirror 18 Wafer 22 1/2 Wave Plate

Claims (7)

[Claims] 1. An exposure apparatus having a means for converting non-linearly polarized light from a light source into linearly polarized light and illuminating a pattern with the linearly polarized light. 2. A means for converting non-linearly polarized light from a light source into linearly polarized light and illuminating a pattern with the linearly polarized light, and a pattern illuminated by the illuminating means on a substrate through a polarized light splitter. An exposure apparatus having a projection optical system for projecting onto an image. 3. The illumination means comprises a light splitter for splitting the non-linearly polarized light from the light source into two light fluxes, and means for matching the polarization directions of the two light fluxes with each other. Exposure equipment. 4. A polarized light splitter for splitting the non-linearly polarized light from the light source into two light beams by the illuminating means and changing the polarization direction of one light beam so that the polarization directions of the two light beams coincide with each other. A wave plate is provided.
Exposure equipment. 5. A concave mirror for causing the projection optical system to reflect the light transmitted through the polarization splitter and to re-enter the polarization splitter, and the light re-entering the polarization splitter is reflected by the polarization splitter. The light passing through the polarization splitter comprises the polarization splitter and a quarter-wave plate arranged between the concave mirror to change the polarization direction of the light passing through the polarization splitter. The linearly polarized light polarized in the substantially same direction as the polarization direction of the above is supplied.
Exposure equipment. 6. A concave mirror for causing the projection optical system to reflect the light reflected by the polarization splitter and re-enter the polarization splitter, and to allow the light re-entering the polarization splitter to pass through the polarization splitter. 1 arranged between the polarization splitter and the concave mirror for changing the polarization direction of light transmitted through the polarization splitter
/ 4 wavelength plate, and the illumination means supplies linearly polarized light polarized in a direction substantially the same as the polarization direction of the light reflected by the polarization splitter. Exposure equipment. 7. A device manufacturing method comprising manufacturing a device using the exposure apparatus according to claim 1. Description: