JP2003090978A - Illumination device, exposure device and method for manufacturing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an illumination device, an exposure device and a method for manufacturing a device by which changes in the illuminance on the illuminated face or degradation in the control of the exposure light quantity can be prevented in the exposure device using a light source at <=180 nm wavelength. SOLUTION: The illumination device uses an oscillation laser as a light source to illuminate a specified illumination region with a luminus flux at <=180 nm wavelength and is equipped with an optical member made of a magnesium fluoride crystal which generates a different polarization state of the beam with respect to the plane perpendicular to the optical axis.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates generally to a lighting device, and more particularly to a lighting device used for manufacturing devices such as a single crystal substrate for a semiconductor wafer and a glass substrate for a liquid crystal display (LCD). , An exposure apparatus and a device manufacturing method. INDUSTRIAL APPLICABILITY The present invention is suitable for, for example, an illuminating device of an exposure device that exposes a single crystal substrate for a semiconductor wafer in a microlithography process in manufacturing a fine pattern.

[0002]

2. Description of the Related Art Due to recent demands for miniaturization and thinning of electronic devices, there is an increasing demand for miniaturization of semiconductor elements mounted on the electronic devices. For example, a design rule for a mask pattern is required to form a dimensional image with a line and space (L & S) of 0.1 μm or less in a wide range, and it is expected to shift to a circuit pattern formation of 80 nm or less in the future. . L & S is an image projected on the wafer in the state where the width of the line and the space are equal in the exposure, and is a measure showing the resolution of the exposure.

Referring to FIG. 7, a projection exposure apparatus 50, which is a typical exposure apparatus for semiconductor manufacturing, generally includes a light source unit 510 including a laser 512 and a beam shaping system 514, and a reticle or mask 600 (in the present application, And an illumination optical system 540 (including reference numerals 542 to 554) for illuminating (using these terms interchangeably).
0, and the pattern drawn on the mask 600, which is arranged between the mask 600 and the object (wafer) W
And a projection optical system 700 that performs projection exposure on the top. Also,
In the exposure apparatus 50, the light beam from the laser 512 is split by the beam splitter 548 or the like to receive the light receiving element 560.
The light amount is received via the light source, and the light amount of the light source is feedback-controlled so that the variation of the light amount in the illumination area falls within a predetermined range. The beam splitter 548 is provided at a position equivalent to the pattern surface of the mask 600, for example, at a stage subsequent to the optical integrator 544.

Generally, when a pattern on the surface of a mask 600 is projected onto a wafer surface via a projection optical system, the resolution line width and the uniformity of the line width are the wavelength (λ) of the exposure light and the projection optical system. Numerical aperture (NA) and the intensity distribution within the numerical aperture of the illumination optical system, as well as the uniformity of the illuminance distribution on the projection surface and the quality of the deviation from the appropriate exposure amount have a great influence.

Particularly, when the minimum line width is 0.2 μm or less,
A KrF excimer laser (λ = 2) is used as a light source for exposure.
48 nm), ArF laser (λ = 193 nm), F ₂
A laser (λ = 157 nm) and the like can be mentioned. Even when such a laser is used, it is desired that the illuminance uniformity on the projection surface of the exposure apparatus and the deviation from the appropriate exposure amount are within about 1%. .

However, since each lens element of the optical integrator 542 receives a force in the radial direction to be distorted in the assembly process, each lens element has different birefringence. Moreover, even inside the lens element, the birefringence varies depending on the location. Therefore, in the apparatus shown in FIG. 7, the laser light that is incident on the optical integrator 542 is circularly polarized light, but is not circularly polarized when it is emitted from the optical integrator 542. Moreover, the light beams emitted from the respective lens elements of the optical integrator 542 have different polarization states from each other.

The glass plate of the beam splitter 548 for detecting the amount of light, the bending mirror 554, etc. usually have polarization characteristics in their optical characteristics (reflectance, transmittance). Therefore, when light having a polarization state other than the random polarization state in the plane perpendicular to the optical axis enters these optical systems, the light amount distribution on the irradiation surface (mask M surface or wafer W surface) is caused by this polarization characteristic. Causes unevenness (unevenness). Further, when such light is incident, if the birefringence state of the optical system changes due to light irradiation or the like, the change in illuminance unevenness or the light amount at the light amount detector 560 and the light amount actually irradiated to the wafer W are detected. However, the exposure amount control deteriorates.

Therefore, conventionally, for a luminous flux emitted from a laser 510 such as an excimer laser which emits a linearly polarized or another polarized ultraviolet laser beam, a λ / 4 plate (not shown), a crystal, or another type is used. The depolarization unit 520 made of a transmissive member converts the light into a light flux having substantially random polarization characteristics. As a result, the depolarization unit 520 arranged near the laser 512 is emitted.
In the above, since the polarization state of the light beam entering the illumination optical system 540 is made substantially random, the above-described adverse effects can be reduced.

[0009]

However, the wavelength 1
80 nm or less (for example, F2 laser light: wavelength 157n
In the case of the device using the laser as the light source of m), the conventionally used crystal has poor optical characteristics with respect to transmittance / light durability at short wavelengths, and thus it can be applied to an exposure device that uses a light source having such a wavelength or less. Can not. As a result, the depolarization unit 800 cannot be used in an exposure apparatus having a wavelength of 180 nm or less, and as described above, the change in illuminance unevenness on the illumination surface and the exposure amount control are deteriorated. Therefore, a device having a fine pattern cannot be performed with good exposure performance such as high-quality throughput.

[0010]

SUMMARY OF THE INVENTION Therefore, according to the present invention, in an exposure apparatus which uses a light source having a wavelength of 180 nm or less, an illumination apparatus, an exposure apparatus, and an exposure apparatus which do not deteriorate the unevenness of illuminance on the illumination surface and the exposure amount control. It is an exemplary object to provide a device manufacturing method.

In order to achieve the above-mentioned object, an illumination device according to one aspect of the present invention is an illumination device which illuminates a predetermined illumination area using a light beam having a wavelength of 180 nm or less using an oscillating laser as a light source. It has an optical member formed of magnesium crystal and different in the polarization state of the light beam in a plane perpendicular to the optical axis.

The illumination device according to one aspect of the present invention has a wavelength of 180 n in a predetermined polarization state emitted from a light source.
An illuminating device that illuminates an illumination area using a light flux of m or less, and has an optical member formed of magnesium fluoride crystal and different in the polarization state of the light flux in a plane perpendicular to the optical axis. For example, the light source is an oscillating laser.

According to such an illuminating device, the magnesium fluoride crystal has excellent optical characteristics of transmission or reflection for a light flux of 180 nm or less due to its crystal structure, and the magnesium fluoride crystal can be used even when the exposure light is 180 nm or less. The optical member made of crystal can be made to function as a depolarizing means. That is, a light beam having a linearly polarized light or another polarized light emitted from the light source can be converted into light whose polarization state changes continuously or stepwise in a cross section orthogonal to the optical axis. This makes it possible to derive a non-polarized light beam with respect to the optical system located in the subsequent stage, and thus, when the lighting device includes an optical member having polarization characteristics in its optical characteristics (reflectance, transmittance). Even in this case, it is possible to eliminate the uneven illuminance in the illumination area.

In the illumination device of the present invention, the optical member has a polarization direction of the light beam different from a crystal axis direction of the magnesium fluoride crystal. Further, the optical members have different thicknesses in the cross section including the optical axis. This makes it possible to substantially depolarize a linearly polarized light beam or a light beam having another polarization state. In the lighting device of the present invention,
You may have the cooling means which cools the said optical member. According to such an illumination device, the cutoff wavelength of magnesium fluoride can be shifted to the short wavelength side. Furthermore, the illumination device of the present invention further includes an optical integrator for uniformly illuminating the illumination area, and the optical member is located closer to the light source than the optical integrator.

Further, the illuminating device of the present invention detects the amount of light of one of the luminous flux splitting portion which splits the luminous flux between the optical member and the illumination area and the luminous flux split by the luminous flux splitting portion. And a detector that does. According to such an illuminating device, the fluctuation of the polarization state of the laser light from the light source is transmitted through the beam splitter without being caused by the polarization dependence of the reflectance (transmittance) of the glass plate which is the light beam splitting unit (beam splitter). It is possible to maintain a constant light quantity ratio between the light (light in the illumination area) and the light reflected by the beam splitter (light incident on the detector), and it is possible to accurately detect the light quantity in the illumination area. The illumination device may further include a control unit that controls the light amount of the light source based on the detection result of the detector, or a light amount adjustment unit that adjusts the light amount of the light flux based on the detection result of the detector. . With this, it is possible to accurately adjust the light amount of the lighting device.

Further, the illuminating device of the present invention may further include a mirror for deflecting the light flux between the optical member and the illumination area. According to such an illuminating device, the variation of the polarization state of the laser light from the light source does not result from the polarization dependency of the reflectance of the mirror, and the light can be reflected by the mirror without causing the illuminance unevenness in the illumination area. .

An exposure apparatus as another aspect of the present invention has any of the above-mentioned illumination devices and an optical system for projecting a pattern formed on a reticle or a mask onto an object to be processed. The exposure apparatus has the above-mentioned illumination device and has the same operation. Furthermore, according to the exposure apparatus of the present invention,
Since the exposure wavelength can be shortened, a fine pattern can be exposed with good exposure performance such as throughput.

According to still another aspect of the present invention, a device manufacturing method includes the step of projecting and exposing the object to be processed by using the above-mentioned exposure apparatus, and a predetermined process for the object to be projected and exposed. And steps. The claims of the device manufacturing method having the same operation as the above-described operation of the exposure apparatus extend to the devices themselves which are intermediate and final products. Further, such a device is, for example, L
Semiconductor chips such as SI and VLSI, CCD, LCD,
Includes magnetic sensors and thin film magnetic heads.

Other objects and further features of the present invention will be made clear by the preferred embodiments described below with reference to the accompanying drawings.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION An exposure apparatus 10 and an illumination apparatus 100 according to the present invention will be described below with reference to the accompanying drawings. In each figure, the same reference numeral represents the same member. Here, FIG. 1 is a schematic configuration diagram of an exemplary exposure apparatus 10 of the present invention and an illumination apparatus 100 that is a part thereof.

As shown in FIG. 1, the exposure apparatus 10 includes an illumination device 100, a mask 200, a projection optical system 300, and
And a control device (not shown). The exposure apparatus 10 is a scanning projection exposure apparatus that exposes the pattern formed on the mask 200 on the plate W by the step-and-scan projection method. Here, in the “step-and-scan projection method”, the wafer is continuously scanned with respect to the mask 200 to expose the pattern of the mask on the plate W, and the plate W is moved stepwise after one shot of exposure is completed. Projection exposure method of moving to the exposure area of the next shot. However, the exposure apparatus 10 of the present invention may be applied to an exposure apparatus that exposes the pattern formed on the mask 200 on the plate W by the step-and-repeat projection method. Here, the “step-and-repeat projection method” refers to a projection exposure method in which the plate W is moved stepwise every time a shot of the plate W is collectively exposed to move the next shot to the exposure area.

In the present invention, the illumination device 100 includes a light source section 110, a depolarization unit 120, and an illumination optical system 1.
40 and the control unit 170, and illuminates the mask 200 on which the transfer pattern is formed.

The light source unit 110 has a laser 112 and a beam shaping system 114 and is a light source for illuminating an illumination optical system.

The laser 112 is a light source that emits illumination light and is an oscillating laser that emits a wavelength of 180 nm or less. In this embodiment, the laser 112 has a wavelength of about 157 nm.
F ₂ excimer laser. Such laser 112
Emits an ultraviolet laser light having a linear polarization or another polarization state. The laser 112 may be, for example, the control unit 1.
If it is communicatively connected to 70, the light amount detecting means 1 described later
Feedback control can also be performed by the control unit 170 based on the detection result of 60. As the light source for exposure, not only an excimer laser but also a combination of a copper vapor laser or an argon gas laser and a second harmonic generation element to form far ultraviolet rays can be used. Although not particularly shown in FIG. 1, since the F ₂ laser light is normally absorbed by oxygen, oxygen is minimized (1 ppm) in the nitrogen atmosphere, vacuum, etc. in the optical path from the light source to the exposure surface.
Below) It is necessary to make the environment.

The beam shaping system 114 can use, for example, a beam expander having a plurality of cylindrical lenses, and converts the aspect ratio of the cross-sectional shape of the parallel light from the laser 112 into a desired value (for example, The beam shape is formed into a desired shape by changing the cross-sectional shape from rectangular to square.

Although not shown in FIG. 1, the light source section may use an incoherent optical system for making a coherent laser light beam incoherent. The incoherent optical system, for example, discloses at least two light beams (for example, P
Polarized light and S-polarized light), one light flux is given to the other light flux through the optical member and the optical path length difference is equal to or longer than the coherence length of the laser light, and then the other light flux is re-induced to the other split light flux. It is possible to use an optical system including at least one folding system that is superposed and emitted.

The depolarizing unit 120 includes the laser 11
The linearly polarized light or the laser light having another polarization state emitted from 2 is made into a random polarization state (depolarized). In the present embodiment, the depolarization unit 120 is provided between the laser 112, which is a light source, and the beam shaping system 114 also in order to depolarize the light flux with respect to the element located in the subsequent stage. As shown in FIG. 2, the depolarization unit 120 includes a depolarization plate 122 having a wedge-shaped cross section including the optical axis, and a transparent wedge 124 having a wedge shape in the direction opposite to the depolarization plate 122. Transparent wedge 124
Is an auxiliary element for correcting the emitted light deflected by the depolarizer 122 in the same direction as the incident direction, and the wedge angle is slightly different due to the difference in the refractive index of both elements. The transparent wedge 124 is not always necessary if the exit direction may be different from the incident direction. Here, FIG. 2A is a depolarization unit 120 shown in FIG.
2 (b) is a schematic cross-sectional view showing the change canceling unit 120 without the transparent wedge 124 shown in FIG. 2 (a).

The depolarizer 122 is made of magnesium fluoride (MgF ₂ ) crystal and has a wedge shape as described above. Magnesium fluoride has a crystal structure of 1
It has excellent optical characteristics of transmission or reflection for a light flux of 80 nm or less, and can maintain the function as a depolarizing plate even when the exposure light is 180 nm or less. Further, as shown in FIG. 3, the crystal axis of the depolarizer 122 is arranged so as not to coincide with the main polarization direction of the incident light beam. In the present embodiment, the crystal axis is exemplarily arranged so as to form an angle of 45 degrees with the main polarization direction of the light beam. Here, FIG. 3 is a depolarizing plate 12 shown in FIG.
It is a schematic perspective view for showing the structure of FIG.

As shown in FIG. 3, the depolarizing plate 122 has a crystal axis direction of 45 degrees with respect to the polarization direction (y direction) of the linearly polarized laser light from the laser 112, and its thickness. Is designed so that a light beam (linearly polarized light in the y direction) passing through the center position where the optical axis penetrates is converted into circularly polarized light. However, it is not always necessary to convert a ray passing through the center of the depolarizer 122 into circularly polarized light, and it is not necessary to make the polarization direction (y direction) of the laser coincide with the wedge direction of the depolarizer 122. In short, it suffices that the polarization state of the light beam incident on the depolarizer 122 changes continuously or stepwise along a certain direction and the polarization state of the entire light beam is depolarized and becomes substantially non-polarized. It is a thing. More preferably, in order to increase the amount of relative phase change in the emitted light beam, when the diameter of the incident light beam is not symmetrical, it is better to make the wedge direction of the depolarizer 122 coincide with the larger diameter direction.

In this embodiment, the depolarizer 122 is used.
The light flux emitted from the light flux changes its polarization state along the y direction as indicated by the arrow in the front view of the light flux in FIG. In this example, the wedge direction (tilt direction) of the depolarizer 122 and the laser polarization direction are made to coincide with each other.
In FIG. 4B, within the range of LA, from the top, y-direction linearly polarized light, counterclockwise elliptically polarized light, counterclockwise circularly polarized light, counterclockwise elliptically polarized light, x-direction linearly polarized light, clockwise The elliptically polarized light, the clockwise circularly polarized light, the clockwise elliptically polarized light, and the linearly polarized light in the y direction continuously change, and the change of the polarization state within the range of LA is repeated along the y direction. The number of repetitions is determined depending on the wedge angle θ1 and the thickness of the depolarizer 122 shown in FIG. 2A and the beam diameter of the laser beam, and the wedge angle θ1 and the thickness depending on the required degree of depolarization. You can decide In addition, in order to obtain a sufficient depolarization effect, it is preferable to repeat 5 times or more. Here, FIGS. 4A and 4B are schematic diagrams showing the function of the depolarizer 122 shown in FIG.

As described above, the depolarizer 122 converts the incident linearly polarized laser light into light whose polarization state changes continuously or stepwise in the cross section orthogonal to the optical axis, and depolarizes the light. is doing. Further, the deflection eliminating plate 122 is M
Since it is made of gF ₂ and has excellent optical characteristics at short wavelengths, it can be applied to an exposure apparatus that uses a wavelength of 180 nm or less, which has been difficult to apply with conventional optical members such as quartz. This makes it possible to derive a depolarized light beam for the optical system located at the subsequent stage. Therefore, fluctuations in the polarization direction of the laser light of the linearly polarized light from the laser 112 will be described later in the beam splitter
The light that passes through the beam splitter 148 (the light that exposes the plate W) and the beam splitter 148 are not caused by the polarization dependence of the reflectance (transmittance) of the glass plate that is 8.
The light quantity ratio of the light reflected by (the light entering the light quantity detecting means) can be maintained constant, and the exposure amount can be controlled with high accuracy. In addition, a change in the polarization direction of the laser light of the linearly polarized light from the laser 112 will be described later.
The light can be reflected by the bending mirror 154 without causing the unevenness of the illuminance in the exposure region without being caused by the polarization dependence of the reflectance of the.

As described above, MgF ₂ is 180
Although it has a relatively good transmission characteristic for wavelengths of nm or less, it has a slightly poorer transmission characteristic for F ₂ laser light. Therefore, the transmission characteristic for F ₂ laser light is MgF.
_The depolarization plate 122 is preferably made of MgF ₂ crystal having the highest possible purity, since it varies depending on the purity of ₂ . Also, Mg
The cutoff wavelength of F ₂ can be shifted to a slightly shorter wavelength side by cooling.

Therefore, the present embodiment exemplarily includes the cooling means 126 for cooling the depolarizing plate 122. The cooling means 126 is connected to a control unit 170, which will be described later, and is controlled by the control unit 170 to control the deflection eliminating plate 1.
Optimal cooling can be performed on 22. However, the cooling unit 126 may not be controlled by the control unit 170, and may itself perform optimum cooling on the depolarization plate 122. In addition,
Since the well-known technique can be applied to the cooling means 126 of the depolarizing plate 122, detailed description thereof will be omitted here. For example, the cooling means 126 may use an air cooling mechanism such as a fan or a blower, and the depolarizing plate 12 may be used.
It can be realized by a cooling mechanism such as a heat pipe provided on the outer periphery of 2.

The transparent wedge 124 is a transparent member having a wedge-shaped cross section including the optical axis for correcting the direction of the optical axis which changes due to the wedge shape of the depolarizer 122, and the transparent wedge 124 is birefringent. Is made of a material having a small amount or no birefringence. As shown in FIG. 2B, the transparent wedge 124 may not be used. However, in this case, it is necessary to match the optical axis (laser light) deflected by the depolarizer 122 with the optical axis of the optical system in the subsequent stage.

In the depolarization unit 120, the two optical members (the depolarization plate 122 and the transparent wedge 124) may be composed of the two depolarization plates 122. In such a configuration, both depolarizers 122 have wedge shapes with respect to a cross section including the optical axis and the y axis but in mutually opposite directions. One of the two depolarizers 122
The crystal axis of 2 forms a predetermined angle with the reference polarization direction (y axis) of the linearly polarized laser light from the laser 112,
The crystal axis of the other depolarizing plate 122 forms 45 degrees with respect to the crystal axis of the one depolarizing plate 122.

In the case of only one depolarizing plate 122 as in the depolarizing unit 120 described above, the polarization direction of the linearly polarized laser light from the laser 112 largely changes and the polarization direction of the laser light is a crystal of the depolarizing plate 122. The polarization of the laser beam cannot be depolarized if it coincides with or is orthogonal to the axis direction.However, using the depolarization unit described above makes it possible for the crystal axis direction that does not make the crystal axis directions coincide or orthogonal to each other. A pair of depolarizers 122 forming 45 degrees with each other
This is not the case because the
The polarization of the polarized laser light from 2 can always be eliminated.

As shown in FIG. 1, the exposure apparatus 10 may be provided with the dimming unit 130 after the depolarization unit 120. The light reduction unit 130 reduces the light flux emitted from the laser 112. Although the dimming unit 130 does not prevent the application of any known dimming unit, in the present embodiment, the dimming unit 130 exemplarily includes parallel plane plates 132 and 134 and a gap adjusting unit 136. The interval adjusting unit is communicably connected to the control unit 170, and can be feedback-controlled by the control unit 170 based on the detection result of the light amount detection unit 160 described later.

The dimming unit 130 includes the space adjusting means 23.
Parallel plane plates 132 and 134 on the order of microns
Can be controlled in the optical axis direction. As described above, in the optical path from the light source to the exposure surface, a nitrogen atmosphere, vacuum, etc.
The environment is kept to a minimum of oxygen (1 ppm or less). Therefore, the dimming effect can be obtained by setting the atmosphere between the plane-parallel plates 132 and 134 to be a normal atmosphere or an atmosphere containing a predetermined amount of oxygen. For example, when it is not necessary to attenuate the light, the parallel flat plate 132 and the parallel flat plate 134 are driven so that the distance between them becomes 0, and when it is necessary to reduce the light, the parallel flat plate 132 and the parallel flat plate 134 are driven.
It is possible to widen the interval by a required amount and dimming. However, this unit does not necessarily have to be applied to the exposure apparatus 10 as a necessary unit. As described above, by feedback controlling the laser 112,
The exposure amount may be adjusted.

The illumination optical system 140 includes the depolarization unit 1
A mask 200 using the light beam that has been depolarized by 20
Is an optical system that illuminates the optical system. In this embodiment, the optical integrator 142, the aperture stop 144, and the condenser lens 1 are used.
46, a light splitting member (beam splitter) 148, a masking blade 150, an imaging lens system, a bending mirror 1
54. Although not shown in FIG. 1, a condensing optical system may be provided between the light source unit 110 and the optical integrator 142. The condensing optical system first includes necessary bending mirrors, lenses, and the like, and the light flux that has passed therethrough can be efficiently introduced into the optical integrator 142. For example, in the condensing optical system, the exit surface of the beam shaping system 114 and the entrance surface of an optical integrator 142 configured as a fly-eye lens described below are optically the object plane and the pupil plane (or the pupil plane and the image plane). (Which may be referred to as a Fourier transform relationship in the present application), and the principal ray of the light flux passing through the condenser lens is placed at any of the center and peripheral lenses of the optical integrator 142. Keep parallel to the device.

The optical integrator 142 is configured as a fly-eye lens that homogenizes the illumination light with which the mask 200 is illuminated, converts the angular distribution of the incident light into a positional distribution, and emits it. In the fly-eye lens, the entrance surface and the exit surface are optically related to the object surface and the pupil surface (or the pupil surface and the image surface), and a plurality of point light sources (effective light sources) are provided on the exit surface or in the vicinity thereof. Form.

The fly-eye lens is formed by arranging a plurality of lenses (lens elements) (not shown) on the other surface whose focal positions are different from each other. Further, when the lens surface of each lens element is spherical, the cross-sectional shape of each lens element forming the fly-eye lens is more similar to the illumination area of the illumination device, and the utilization efficiency of the illumination light is higher. This is because the fly-eye lens and the illumination area have a relationship between the pupil and the image.

The optical integrator 130 applicable to the present invention is not limited to a fly-eye lens, and for example,
It may be a plurality of sets of cylindrical lens arrays arranged such that the generatrices of the cylindrical lenses forming each set are orthogonal to each other. The fly-eye lens may be replaced with an optical rod. The optical rod has a rectangular cross section in which the illuminance distribution that was non-uniform on the entrance surface is made uniform on the exit surface, and the cross-sectional shape perpendicular to the rod axis has an aspect ratio substantially the same as that of the illumination region. If the optical rod has a power in a sectional shape perpendicular to the rod axis, the illuminance on the emission surface is not uniform, and therefore the sectional shape perpendicular to the rod axis is a polygon formed by only straight lines. In addition, the fly-eye lens
It may be replaced with a diffractive element having a diffusing action.

The aperture stop 144 blocks unnecessary light and forms a desired effective light source. The aperture stop has, for example, a circular aperture. Alternatively, the aperture stop may be configured as a ring-shaped aperture stop or a quadrupole aperture stop, for example. Such an aperture stop is effective as modified illumination (or oblique incidence illumination) that increases the depth of focus near the limit resolution when exposing the pattern of the mask 200. It should be noted that the aperture stop 144 is controlled by the control unit 170.
It is preferable that the above-mentioned aperture diameter and shape can be changed according to illumination conditions.

The condenser lens 146 is, for example, a condenser lens, and has an optical integrator 142.
As many effective light sources formed in the vicinity of the exit surface of the above are collected as much as possible and the masking blade 150 is superposed on the masking blade 150 so as to illuminate the masking blade 150 by Koehler illumination.

The beam splitter 150 reflects a part of the light beam from the optical integrator 142 and introduces the reflected light beam into a sensor (not shown) of the light amount detecting means 160. The beam splitter 150 is arranged so as to be inclined at a predetermined angle from the surface perpendicular to the optical axis to the light source side. The beam splitter 150 preferably minimizes the angle formed by the incident surface with respect to the surface perpendicular to the optical axis in order to minimize the reflectance difference of the outermost light ray of the incident light flux on the incident surface. In the present embodiment, the beam splitter 150 is made of a glass plate with or without a dielectric film formed thereon.

The light quantity detecting means 160 is the beam splitter 1.
The light amount of the light flux reflected by 48 is detected, and the detection result is output to the control unit 170. The light amount detecting means 160 can be realized by a detector such as an optical sensor which continuously detects the light amount. The light amount detecting means 160 is arranged so as to be located at the condensing point of the light flux reflected by the beam splitter 148. The light amount detecting means 160 is the control unit 1
The light quantity of the incident light beam is converted into a digital signal, and the digital signal is output to the control unit 170. Any well-known configuration can be applied to the optical sensor, and detailed description thereof will be omitted here. The light amount detecting means 160 may include an amplifier between the optical sensor and the control unit 170 in addition to the above-described optical sensor. In such a configuration, the signal output from the sensor is amplified and output to the control unit 170, so that the signal can be effectively output even with a minute change in the light amount.

As described above, the beam splitter 148
The light beam incident on is depolarized by the depolarization unit 120, and is transmitted through the beam splitter 148 (light that exposes the plate W) and the beam splitter 148.
The light quantity ratio of the light reflected by (the light entering the light quantity detecting means) can be maintained constant, and the exposure amount can be controlled with high accuracy.

The inclination angle of the beam splitter 150 may be fixed in advance, or the inclination angle may be variable. When the tilt angle is variable, the beam splitter 150 may manually adjust the above-described angle, or may be connected to a driving device (not shown) so that the angle can be adjusted according to the illumination condition and the configuration of the illumination device 100. It may be configured. In such a configuration, the drive device can be controlled by the control unit 170 of the illumination device 100 to adjust the angle of the beam splitter 150, for example.

The masking blade 150 limits the exposure range on the surface of the mask 200 (further, the plate W) which is the surface to be illuminated. The masking blade 150 is formed of, for example, four movable light-shielding plates and forms a substantially rectangular opening to form a rectangular illumination area. A step-and-scan type projection exposure apparatus is generally configured such that the lateral direction of the illumination area matches the scanning direction.

The imaging lens system is composed of, for example, a pair of condenser lenses 152a and 152b, and images the opening shape of the masking blade 150 on the mask 200, which is the surface to be illuminated, at a predetermined imaging magnification.

The folding mirror 154 is provided between the condenser lens 152a and the condenser lens 152b and deflects the direction of the light beam. As described above, the light beam incident on the bending mirror 154 is not reflected by the depolarization unit 120.
Since it is non-polarized, the bending mirror 154 can reflect the light without causing unevenness in illuminance in the exposure area.

The control section 170 typically has a CPU and a memory, and controls each section of the lighting apparatus 100. Control unit 1
In relation to the present invention, 70 controls the output of the laser 112 on the basis of the detection result of the light amount detection means 160, and changes so as to obtain an appropriate illumination amount (exposure amount). The control unit 1
70 is a cooling means 126, a driving means 136, an aperture stop 1
44, a driving device (not shown) for driving the beam splitter 148, and at least one of the masking blade 150 may be further controlled. Further, the control unit 170 is connected to a control device (not shown) and can communicate with the control device. For example, the control unit 170 is connected to a control device (not shown) of the exposure apparatus 10 described later, and can communicate with the control device.

The CPU includes any processor regardless of name such as MPU and controls the operation of each unit. The memory is composed of a ROM and a RAM, and stores firmware that determines the output of the laser corresponding to the detected light amount and firmware that operates the lighting device 100. Note that the configuration of the control unit 170 is not limited to this description as long as such a function can be achieved. Of course, any technique conceivable to a person skilled in the art is applicable.

Although the present embodiment has been described by using the change canceling unit 120 that functions only as the depolarizing effect, for example, an optical member in the beam shaping optical system 114 (for example, the thickness varies depending on the location). Mg for the lens member)
Depolarization may be performed by using a crystal of F ₂ . Do not align the crystal axis with the main polarization direction of the incident light (4
If the thickness of the member is different depending on the location, it is possible to sufficiently depolarize.
However, in order to obtain the above-mentioned effects, it is desirable that the member for depolarizing is located closer to the light source than the beam splitter 148.

The mask 200 is made of, for example, quartz, on which a circuit pattern (or image) to be transferred is formed, and is supported and driven by a mask stage (not shown).
The diffracted light emitted from the mask 200 is projected by the projection optical system 300.
Is projected onto the plate W. The plate W is an object to be processed and is coated with a resist. The mask 200 and the plate W are arranged in an optically conjugate relationship. Since the exposure apparatus 10 of this embodiment is a step-and-scan exposure apparatus (that is, a scanner), the mask 200 is scanned by scanning the mask 200 and the plate W.
Pattern is transferred onto the plate W.

The mask stage supports the mask 200 and is connected to a moving mechanism (not shown). The mask stage and the projection optical system 300 are provided on, for example, a stage barrel surface plate supported by a base frame placed on a floor or the like via a damper or the like. The mask stage may have any configuration known in the art. A moving mechanism (not shown) is composed of a linear motor or the like, and the mask 200 can be moved by driving the mask stage in a direction orthogonal to the optical axis. The exposure apparatus 10 scans the mask 200 and the plate W in a synchronized state by a control device (not shown).

The projection optical system 300 forms an image on the plate W of the light flux that has passed through the pattern formed on the mask 200.
The projection optical system 300 includes an optical system including only a plurality of lens elements, an optical system including a plurality of lens elements and at least one concave mirror (catadioptric optical system), a plurality of lens elements and at least one kinoform. An optical system having a diffractive optical element such as, an all-mirror type optical system, or the like can be used. If you need to correct chromatic aberration,
A plurality of lens elements made of glass materials having mutually different dispersion values (Abbe numbers) may be used, or the diffractive optical element may be configured to generate dispersion in the direction opposite to that of the lens elements.

Although the plate W is a wafer in this embodiment, it includes a wide range of liquid crystal substrates and other objects to be processed. Photoresist is applied to the plate W. The photoresist coating process includes a pretreatment, an adhesion improver coating treatment, a photoresist coating treatment, and a prebake treatment. Pretreatment includes washing, drying and the like. The adhesion improving agent coating treatment is a surface modification treatment (that is, hydrophobic treatment by applying a surfactant) for enhancing the adhesion between the photoresist and the base, and is performed by HMDS (Hexamethyl-disila).
An organic film such as zane) is coated or steamed. Pre-baking is a baking (baking) process, but it is softer than that after development and removes the solvent.

The plate W is supported by the wafer stage 400. Since the wafer stage 400 may have any configuration known in the art, detailed description of its structure and operation will be omitted here. For example, the wafer stage 400 uses a linear motor to move the plate W in a direction orthogonal to the optical axis. Mask 200 and plate W
Are synchronously scanned, and the positions of the mask stage and the wafer stage 400 (not shown) are monitored by, for example, a laser interferometer, and both are driven at a constant speed ratio. The wafer stage 400 is provided on, for example, a stage surface plate supported on a floor or the like via a damper, and has a mask stage and a projection optical system 300 (not shown).
For example, the lens barrel surface plate is provided on a lens barrel surface plate (not shown) that is supported via a damper or the like on a base frame placed on the floor or the like.

Further, the wafer stage 400 includes the plate W.
The plate W in the optical axis direction within the range of the depth of focus.
Adjust the imaging position of. The exposure apparatus 10 can eliminate the variation in the imaging performance within the depth of focus by performing the exposure a plurality of times on the plates W arranged at different positions in the optical axis direction. For such a function, any technology known in the art such as a rack (not shown) extending in the optical axis direction, a pinion (not shown) that is connected to the wafer stage and movable on the rack, and a means for rotating the pinion can be applied. Therefore, detailed description is omitted here.

The controller not shown is typically a CPU
And a memory, and controls the exposure apparatus 10. The control device is electrically connected to the illumination device 100, a mask stage (not shown), and the wafer stage 400. In the present embodiment, the control device changes and moves the illuminating device 100, the mask stage, and the wafer stage so as to correspond to each exposure. The CPU includes any processor regardless of name such as MPU, and controls the operation of each unit. The memory is composed of a ROM and a RAM, and stores firmware for operating the exposure apparatus 10. The configuration of the control device of the exposure apparatus is not limited to the above description as long as the above-mentioned function can be achieved. Of course, any technique conceivable to a person skilled in the art is applicable.

In the exposure, the laser light having the linearly polarized light or another polarized light emitted from the laser 112 is incident on the depolarization unit 120 and is randomly polarized (depolarized). The light beam depolarized by the depolarization unit 120 is dimmed to a desired illuminance by the dimming unit 130 in some cases, and enters the beam shaping system 114. After that, the light beam whose beam shape is shaped by the beam shaping system 114 is transmitted to the optical integrator 14
Incident on 2. The optical integrator 142 is
The wavefront of incident light is divided to form a plurality of light sources on or near the light exit surface.

The light flux emitted from the optical integrator 142 is transmitted through the aperture stop 144, and the condenser lens 14
And is reflected and transmitted by the beam splitter 148. Of these, the transmitted light flux is the masking blade 150.
To evenly illuminate. The light flux that has passed through the masking blade 150 illuminates the irradiation surface of the mask 300 after passing through the imaging optical system. The light flux passing through the mask 300 is projected by the projection optical system 4
Due to the image forming action of 00, reduction projection is performed on the plate W at a predetermined magnification. With the step-and-scan type exposure apparatus 1, the light source unit and the projection optical system 400 are fixed, and the entire shot can be exposed by synchronously scanning the mask 300 and the plate W. Further, the wafer stage of the plate W is stepped to the next shot, and a large number of shots are exposed and transferred onto the plate W. If the exposure apparatus 1 is the step-and-repeat method, the exposure can be performed while the mask 300 and the plate W are stationary.

The light beam reflected by the beam splitter 148 enters the light amount detecting means 160, and the light amount detecting means 1
The light beam incident on 60 is converted into an electric signal corresponding to the light amount of the light beam, and is transmitted to the control unit 170. Control unit 17
With 0, the light quantity of the laser 120 (or the dimming unit 136) can be feedback-controlled based on the illuminance of the mask 200 so that the fluctuation of the light quantity falls within a predetermined range.

As described above, the exposure apparatus 1 of the present invention
According to 0, 180n such as an F ₂ laser as a light source
When a light source with a wavelength of m or less is used, even if the polarization state of the laser light or the birefringence state of the optical members that fluctuate changes, the exposure amount can be controlled more accurately than before, and uneven illumination occurs Can be suppressed. As a result, according to the exposure apparatus 10 of the present invention, the exposure wavelength can be shortened, so that a fine pattern can be exposed with good exposure performance such as throughput. Therefore, the pattern transfer to the resist can be performed with high accuracy and a high quality device (semiconductor element, LCD element, image pickup element (CCD, etc.),
Thin film magnetic heads, etc.) can be provided.

Next, with reference to FIGS. 5 and 6, an embodiment of a device manufacturing method using the above-described exposure apparatus 10 will be described. FIG. 5 is a flow chart for explaining the manufacture of devices (semiconductor chips such as IC and LSI, LCDs, CCDs, etc.). Here, manufacturing of a semiconductor chip will be described as an example. In step 1 (circuit design), the device circuit is designed. In step 2 (mask manufacturing), a mask having the designed circuit pattern is manufactured. In step 3 (wafer manufacturing), a wafer is manufactured using a material such as silicon. Step 4 (wafer process) is called a pre-process, and a mask and a wafer are used to form an actual circuit on the wafer by the lithography technique of the present invention. Step 5 (assembly) is called a post-step, and is a step of forming a semiconductor chip using the wafer created in step 4, and includes an assembly step (dicing, bonding), a packaging step (chip encapsulation) and the like. . In step 6 (inspection), inspections such as an operation confirmation test and a durability test of the semiconductor device created in step 5 are performed. Through these steps, the semiconductor device is completed and shipped (step 7).

FIG. 6 is a detailed flowchart of the wafer process in Step 4. In step 11 (oxidation), the surface of the wafer is oxidized. In step 12 (CVD), an insulating film is formed on the surface of the wafer. Step 13
In (electrode formation), electrodes are formed on the wafer by vapor deposition or the like. In step 14 (ion implantation), ions are implanted in the wafer. In step 15 (resist processing), a photosensitive agent is applied to the wafer. In step 16 (exposure), the exposure apparatus 10 exposes the mask circuit pattern onto the wafer. In step 17 (development), the exposed wafer is developed. In step 18 (etching), parts other than the developed resist image are removed. Step 19
In (resist stripping), the resist that has become unnecessary after etching is removed. By repeating these steps, multiple circuit patterns are formed on the wafer.

Although the preferred embodiments of the present invention have been described above, the present invention is not limited to these, and various modifications and changes can be made within the scope of the spirit thereof.

[0069]

According to the illumination device and the exposure device of the present invention, when a light source having a wavelength of 180 nm or less such as an F ₂ laser is used as the light source, the polarization state of the laser light and the optical members to be formed are Even if the birefringence state changes, the exposure amount can be controlled more accurately than before, and the occurrence of uneven illuminance can be suppressed. Accordingly, the exposure wavelength can be shortened, so that a fine pattern can be exposed with good exposure performance such as throughput. Therefore, the pattern transfer to the resist is performed with high accuracy and a high quality device (semiconductor element, LCD element, image pickup element (C
CD, etc.), thin film magnetic head, etc.) can be provided.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of an exemplary exposure apparatus of the present invention and an illumination apparatus that is a part thereof.

2A is a schematic cross-sectional view and an optical path diagram of the depolarization unit shown in FIG. 1, and FIG. 2B is a schematic cross-sectional view showing a change elimination unit 120 without a transparent wedge shown in FIG. FIG.

FIG. 3 is a schematic perspective view showing the configuration of the deflection eliminating plate shown in FIG.

4A and 4B are schematic diagrams showing the function of the depolarizing plate shown in FIG.

FIG. 5 is a flowchart for explaining manufacturing of devices (semiconductor chips such as IC and LSI, LCDs, CCDs, etc.).

6 is a detailed flowchart of the wafer process in Step 4 shown in FIG.

FIG. 7 is a schematic configuration diagram showing a conventional exposure apparatus.

[Explanation of symbols]

10 Exposure equipment 110 light source 120 Depolarization unit 130 dimming unit 140 Illumination optical system 160 Light intensity detection means 170 control unit 200 mask 300 Projection optical system 400 wafer stage

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) G03F 7/20 502 H01S 3/00 B H01L 21/027 G02B 27/00 V H01S 3/00 H01L 21/30 515DF Term (reference) 2H049 BA12 BA42 BB03 BC21 2H052 BA01 BA02 BA09 BA12 2H097 CA13 GB00 LA10 5F046 CA03 CA07 CB15 CB25 5F072 AA06 KK05 KK15 KK30 MM01 TT03 TT04 TT12 YY09

Claims (13)

[Claims] 1. A wavelength of 180 n using an oscillating laser as a light source.
An illumination device for illuminating a predetermined illumination area using a light flux of m or less, the illumination device having an optical member formed of magnesium fluoride crystal and different in polarization state of the light flux in a plane perpendicular to an optical axis. . 2. An illumination device for illuminating an illumination region using a light beam having a wavelength of 180 nm or less in a predetermined polarization state emitted from a light source, the illumination device being formed of magnesium fluoride crystal, and in a plane perpendicular to an optical axis, An illumination device having an optical member that changes the polarization state of a light beam. 3. The light source is an oscillating laser.
Illumination device described. 4. The illumination device according to claim 1, wherein the optical member has a polarization direction of the light flux different from a crystal axis direction of the magnesium fluoride crystal. 5. The illumination device according to claim 4, wherein the optical members have different thicknesses in cross sections including the optical axis. 6. The illumination device according to claim 1, further comprising a cooling unit that cools the optical member. 7. The illumination device according to claim 1, further comprising an optical integrator for uniformly illuminating an illumination area, wherein the optical member is located closer to the light source than the optical integrator. 8. A light flux splitting unit that splits the light flux between the optical member and the illumination region, and a detector that detects the light amount of one of the light fluxes split by the light flux splitting unit. The illumination device according to item 1 or 2. 9. The illumination device according to claim 8, further comprising a control unit that controls a light amount of the light source based on a detection result of the detector. 10. The illumination device according to claim 8, further comprising a light amount adjusting unit that adjusts a light amount of the light flux based on a detection result of the detector. 11. The illumination device according to claim 1, further comprising a mirror that deflects the light flux between the optical member and the illumination area. 12. An exposure apparatus comprising: the illumination device according to claim 1; and an optical system that projects a pattern formed on a reticle or a mask onto an object to be processed. 13. A device manufacturing method comprising: a step of projecting and exposing a target object using the exposure apparatus according to claim 12; and a step of performing a predetermined process on the target object subjected to the projection exposure.