JP2004356410A - Aligner and method for exposure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an aligner and a method for exposure having a blind with an exposure light limiting function and a contamination collecting function together. <P>SOLUTION: Slit openings 12, 13 for passing an EUV light are formed in the blind 11 at an upper end of an optical system lens barrel 10. Contamination collecting electrodes are disposed on the peripheries of the openings 12, 13. An opening 22 for passing the EUV light toward a wafer W is formed at a center of the blind 21 at the lower end of the optical system lens barrel 10. The contamination collecting electrode and an ionizer 27 for ionizing the contamination are provided at the periphery of the opening 22. The contamination discharged by illuminating the EUV light to the reticle R reflecting surface is attracted to the collecting electrode by an electrical action, and collected. Therefore, the contamination is hardly deposited on the surface of a mirror, etc., and the decrease in the reflectivity of the mirror can be suppressed. As a result, the throughput of the exposure device is maintained, and the maintenance period can be lengthened. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an exposure apparatus and an exposure method for transferring a pattern formed on an original (a mask, a reticle, etc.) to a sensitive substrate (a wafer, etc.). In particular, the present invention relates to an exposure apparatus and an exposure method having a blind having both a function of limiting exposure light and a function of collecting contamination.
[0002]
BACKGROUND ART AND PROBLEMS TO BE SOLVED BY THE INVENTION
In a so-called lithography technique for forming a fine pattern of a semiconductor device or the like, a light exposure apparatus is currently mainstream. The scanning type in the light exposure apparatus scans a pattern while synchronizing scanning between a reticle stage on which a pattern original (reticle) is mounted and a wafer stage on which a sensitive substrate (wafer) to which the pattern is transferred is mounted. Projection transfer (so-called scan exposure) is performed on the wafer. In this scan exposure apparatus, a step operation of moving the wafer stage to position an exposure area to be transferred on the optical axis of the projection optical system and a scan operation of performing scanning exposure while synchronously moving the reticle stage and the wafer stage are repeated.
[0003]
In light exposure, a transmission type reticle through which exposure light is transmitted is widely used. In the illumination optical system, the exposure light is irradiated on a reticle after being shaped by passing through an opening inside a blind (formed aperture plate). Then, the exposure light passes through the reticle with little intensity loss, and is guided to the wafer via the projection optical system. In light exposure, since the exposure light hardly loses intensity, a considerable number of lenses can be arranged in the illumination optical system. Then, a surface conjugate with the reticle surface is provided in the illumination optical system, and a blind for shaping the exposure light beam can be provided on the surface, so that the blind can be disposed farther away than the reticle stage.
[0004]
In addition to the blind for shaping the exposure light beam used for the scanning exposure, a blind (field stop) for limiting the exposure area on the reticle is required, but such a blind is also required near the conjugate plane. Can be arranged.
[0005]
By the way, with the recent miniaturization of device patterns, it is desired to further improve the resolving power of a projection optical system limited by the diffraction limit of light. Therefore, X-rays having a wavelength of several nm to several tens nm called soft X-rays or EUV light (Extreme Ultra Violet light: extreme ultraviolet light) have been attracting attention, and specifically, EUV light having a wavelength of about 13 nm is used. Lithography technology has been developed. This technology is expected as a technology that can achieve a resolving power of 70 nm or less, which cannot be realized by photolithography using ultraviolet light having a wavelength of about 190 nm, which is an extension of light exposure. In the EUVL exposure apparatus, it is assumed that a scanning exposure method in which a reticle and a wafer are relatively scanned with respect to a projection optical system is adopted.
[0006]
In the EUV light region, there is no influential substance that transmits light, and a transmission / refraction type optical system cannot be configured. Therefore, a reflective optical system is used, and a reflective reticle is also used as the reticle. The exposure light beam emitted from the illumination optical system is obliquely incident on the reflection type reticle, is reflected on the reflection surface, and is guided to the wafer via the projection optical system. However, the reflection mirror used in EUV light exposure currently has a low reflectivity of about 70%, so that when the number of mirrors increases, the intensity of the exposure light decreases exponentially. Therefore, it is desirable to reduce the number of reflection mirrors in the illumination optical system as much as possible. Therefore, there is no room for placing a plane conjugate with the reticle surface in the illumination optical system, and a blind for shaping the exposure light beam must be arranged near the reticle stage.
[0007]
By the way, when the reticle or the wafer is irradiated with the exposure light, the resist applied on the surface reacts to emit gas molecules. Such gas molecules that become liquid or solid and adhere to the inside of the exposure apparatus (mirror surface, reticle surface, etc.) are called contamination (or contaminants for short). If the gas molecules that cause this contamination are potentially ionized molecules or molecules that have a charge, they must be forcibly attached and collected by electrical action. Is possible. However, in this case, an electrode plate or the like for attaching contamination must be additionally provided. In addition, such an electrode plate must be periodically cleaned or replaced, which involves a complicated operation.
In the following description, a gas molecule that is a source of contamination is also referred to as contamination.
[0008]
The present invention has been made in view of such a problem, and an object of the present invention is to provide an exposure apparatus and an exposure method having a blind having both a function of limiting exposure light and a function of collecting contamination.
[0009]
[Means for Solving the Problems]
In order to solve the above problems, an exposure apparatus according to the present invention is an exposure apparatus that transfers a pattern formed on an original to a sensitive substrate, wherein an exposure light beam (beam) is provided between the original and the sensitive substrate. A blind having an opening to pass through and a contamination collecting electrode arranged around the opening is provided.
[0010]
In the exposure apparatus of the present invention, shaping of exposure light and elimination of contamination can be realized by blinds.
[0011]
In the exposure apparatus of the present invention, the blind may be disposed between the original and the projection optical system.
In this case, before the light enters the projection optical system, the exposure area can be limited by the opening of the blind, and the contamination can be collected.
[0012]
In the exposure apparatus according to the aspect of the invention, it is preferable that the blind is disposed immediately above the sensitive substrate, and the blind blocks the light path other than the exposure optical path and the sensitive substrate measurement system optical path.
In this case, it is possible to reduce the contamination that is emitted by the irradiation of the exposure light onto the surface of the sensitive substrate and adheres to a reflection mirror or the like in the optical system.
[0013]
The exposure apparatus of the present invention may further include an ionizing means for ionizing the contamination.
In this case, since the contamination can be ionized by the ionization means, it becomes possible to collect the contamination by applying an electric field near the blind.
[0014]
The exposure method of the present invention is an exposure method for transferring a pattern formed on an original to a sensitive substrate, wherein a blind having a contamination collecting electrode is arranged around an opening through which an exposure light beam (beam) passes, and the blind is provided. This limits the exposure area of the master between the master and the sensitive substrate and collects contamination.
[0015]
Note that the type of exposure light in the present invention is not limited to EUV light, and may be ultraviolet light, an electron beam, an ion beam, or the like. Also, the method of exposure is not particularly limited, and may be reduction projection exposure or 1: 1 close proximity transfer.
[0016]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, description will be made with reference to the drawings.
In the present embodiment described below, an EUVL exposure apparatus will be described as an example, but the present invention can be applied to other exposure apparatuses that use energy rays other than EUV light.
FIG. 1 is a schematic diagram illustrating a configuration of an EUVL exposure apparatus according to the present embodiment.
FIG. 2 is a perspective view showing a configuration of an upper end portion of an optical system barrel of the exposure apparatus.
FIG. 3 is a perspective view showing the configuration of the lower end of the optical system barrel of the exposure apparatus.
[0017]
The EUVL exposure apparatus shown in FIG. 1 includes an illumination system IL (shown at the lower left of the figure) including a light source. EUV light (generally, a wavelength of 5 to 20 nm is used, specifically, a wavelength of 13 nm or 11 nm is used) emitted from the illumination system IL is reflected by the return mirror 1 and then enters the optical system barrel 10. I do.
[0018]
A reticle stage device 3 for moving and positioning the reticle R is disposed above the optical system barrel 10. The reticle R is suction-held on the lower surface of the reticle stage device 3 by an electrostatic chuck (not shown). A multilayer film (for example, Mo / Si or Mo / Be) that reflects EUV light is formed on the lower surface (reflection surface) of the reticle R, and the presence or absence of an absorption layer (for example, Ni or Al) is formed on this multilayer film. It is patterned.
[0019]
The projection system PL is housed inside the optical system barrel 10. In FIG. 1, the entire projection system PL is virtually drawn by dotted lines. Inside the projection system PL, a plurality of reflection mirrors such as four, six, eight, etc., and their holding members are provided.
[0020]
As shown in FIGS. 1 and 2, a disc-shaped blind 11 is provided at the upper end of the optical system barrel 10. As shown in FIG. 2, the blind 11 is provided so as to be rotatable about 180 ° in the circumferential direction with the center 11a as a fulcrum. The blind 11 has two slit openings 12 and 13 through which EUV light passes. The slit opening 12 near the outer end is an opening through which the EUV light e1 reflected by the folding mirror 1 and incident into the optical system barrel 10 passes toward the reticle R. In this slit opening 12, stray light is blocked to some extent. On the other hand, the slit opening (reflected light passing slit) 13 near the center 11a is an opening through which the EUV light e2 reflected on the surface of the reticle R passes toward the projection system PL in the optical system barrel 10. The width of each of the slit openings 12 and 13 is, for example, about 8 mm.
[0021]
In this example, three contamination collecting electrodes 15a, 15b, and 15c are arranged around the openings 12, 13 of the blind 11. The two outer electrodes 15a and 15b are connected to a positive (+) pole, and the one central electrode 15c is connected to a negative (-) pole. As described above, the reticle R is attracted and held on the lower surface of the reticle stage device 3 by the electrostatic chuck (not shown). Therefore, depending on how the voltage is applied to the electrostatic chuck, the reticle R reflecting surface also has an electric charge. Become. Therefore, the contamination emitted by the irradiation of the reticle R reflection surface with the EUV light is also charged, and the charged contamination is adsorbed and collected by the electrodes 15a, 15b, and 15c by the electric action.
[0022]
Furthermore, a large semicircular window 17 is formed in the blind 11. The window 17 is used at the time of maintenance of the projection system PL inside the optical system barrel 10 and the like. During such maintenance or the like, the maintenance can be performed while rotating the blind 11 in the circumferential direction with the center 11a as a fulcrum.
[0023]
As shown in FIG. 1, the EUV light that has passed through the slit opening 12 of the blind 11 is reflected by the reticle R reflecting surface, and then enters the projection system PL in the optical system barrel 10 through the slit opening 13. The EUV light includes information on a circuit pattern drawn on the reticle R. The reflection angle / incident angle (reference numeral θ in FIG. 1) of the EUV light with respect to the vertical axis is, for example, 6 °. The EUV light that has entered the projection system PL is guided to the lower end of the optical system barrel 10 after being reflected by a plurality of reflection mirrors. The reduction magnification of the projection system PL is, for example, 1/4 or 1/5. The number of reflecting mirrors is four, six, eight, etc. A. In order to further increase the value, six or eight sheets are effective.
[0024]
As shown in FIG. 1, a wafer stage device 5 for moving and positioning the wafer W is disposed below the optical system barrel 10. The wafer W is suction-held on the upper surface of the wafer stage device 5 by an electrostatic chuck (not shown). The EUV light guided to the lower end of the optical system barrel 10 via the projection system PL is vertically incident on the surface of the wafer W. In the exposure operation, the reticle stage 3 and the wafer stage 5 perform synchronous scanning at the same speed ratio as the reduction magnification of the projection system PL, that is, 4: 1 or 5: 1.
[0025]
As shown in FIGS. 1 and 3, a disc-shaped blind 21 is provided at the lower end of the optical system barrel 10. As shown in FIG. 3, the blind 21 is fitted into an opening 10A at the lower end of the optical system barrel 10. At the center of the blind 21, an opening 22 for passing EUV light toward the wafer W is formed. Grooves 24a and 24b extending in the horizontal direction are formed in the opening 22 and a part of the lens barrel opening 10A. The grooves 24a and 24b serve as optical paths of an autofocus light transmitting system and a light receiving system (not shown). This autofocus is for detecting the position of the wafer W in the Z direction, and is provided on the lower surface 10B of the optical system barrel 10. Although not shown, a reflection mirror or the like for an interferometer is also provided on the side surface of the lens barrel opening 10A.
[0026]
In this example, two contamination collection electrodes 25a and 25b are arranged around the opening 22 of the blind 21. One electrode 25a is connected to a positive (+) pole, and the other electrode 25b is connected to a negative (-) pole. These electrodes 25a and 25b serve the same role as the electrodes 15a to 15c of the blind 11 described above, and collect the contamination released from the resist on the surface of the wafer W by the irradiation of the EUV light by an electric action. is there.
[0027]
Here, depending on the type of resist on the surface of the wafer W, the wafer W is charged by a method of applying a voltage of the electrostatic chuck of the wafer stage device 5, and similarly generated by a physical / chemical action with exposure light. Contamination may also be charged. This charged contamination is unlikely to be drawn back to the surface of the wafer W, and may be scattered to the projection system PL side.
[0028]
Therefore, as shown in FIG. 1, the blind 21 is provided with an ionization device (an arm discharge type or the like) 27 for ionizing the contamination. By ionizing the contamination by the ionization device 27, the electric adsorption of the contamination to the electrodes 25a and 25b of the blind 21 becomes more reliable. Furthermore, since the blind 21 shields other than the opening 22 serving as the exposure optical path and the grooves 24a and 24b serving as the measurement system optical path, the contamination emitted by the irradiation of the exposure light on the surface of the wafer W is directed to the projection system PL side. Scattering and adhesion to a reflection mirror or the like can also be suppressed.
[0029]
In FIG. 1, the ionization device 27 is provided only on the blind 21 on the lower end side of the optical system barrel 10. However, if necessary, a similar ionization device can be provided on the blind 11 on the upper end side.
[0030]
In the exposure apparatus as described in the present embodiment, stray light can be blocked by the slit opening 12 of the blind 11 at the upper end of the optical system barrel 10, and contamination can be collected by the electrodes 15a to 15c provided in the blind 11. . Furthermore, the contaminants released from the resist on the surface of the wafer W by the irradiation of EUV light can be ionized and collected by the collection electrodes 25a and 25b of the blind 21 at the lower end of the optical system barrel 10 and the ionization device 27. Therefore, contamination hardly adheres to the mirror surface or the like, and a decrease in the reflectance of the mirror can be suppressed. As a result, the maintenance cycle can be lengthened while maintaining the throughput of the exposure apparatus.
[0031]
【The invention's effect】
As is apparent from the above description, according to the present invention, it is possible to provide an exposure apparatus and an exposure method having a blind having both a function of limiting exposure light and a function of collecting contamination.
[Brief description of the drawings]
FIG. 1 is a schematic diagram showing a configuration of an EUVL exposure apparatus according to the present embodiment.
FIG. 2 is a perspective view showing a configuration of an upper end portion of an optical system barrel of the exposure apparatus.
FIG. 3 is a perspective view showing a configuration of a lower end portion of an optical system barrel of the exposure apparatus.
[Explanation of symbols]
R Reticle W Wafer IL Illumination system PL Projection system 1 Folding mirror 3 Reticle stage device 5 Wafer stage device 10 Optical system lens barrel 11 Blind 12, 13 Slit opening 15a, 15b, 15c Contamination collecting electrode 17 Window 21 Blind 22 Opening 24a , 24b Grooves 25a, 25b Contamination collecting electrode 27 Ionizer

Claims (5)

An exposure apparatus for transferring a pattern formed on an original to a sensitive substrate,
An exposure apparatus, wherein an opening through which an exposure light beam (beam) passes and a blind having a contamination collecting electrode disposed around the opening is provided between the original and the sensitive substrate. . The exposure apparatus according to claim 1, wherein the blind is disposed between the original and the projection optical system. 3. The exposure apparatus according to claim 1, wherein the blind is disposed immediately above the sensitive substrate, and the blind blocks an area other than an exposure optical path and a sensitive substrate measurement system optical path. 4. 4. The exposure apparatus according to claim 1, further comprising an ionization unit for ionizing the contamination. An exposure method for transferring a pattern formed on an original to a sensitive substrate,
A blind having a contamination collecting electrode is arranged around an opening through which an exposure light beam (beam) passes, and the blind restricts an exposure area of the master between the master and the sensitive substrate and collects contamination. An exposure method, comprising:

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