JP2003045774A - Illumination device, projection aligner and device manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an illumination device, an aligner and a device manufacturing method using the same, in which an illuminating region is illuminated with uniform illuminance, and the center of gravity of the light intensity of light beams incident on the illuminating region coincides with a center of the light beams. SOLUTION: In an illumination device, an aligner and a device manufacturing method using the same, an illumination surface is illuminated with a beam of wavelength 200 nm or higher from a light source. The illuminating device, the aligner and the device manufacturing method, using the same have a first reflection-type integrator; a first collector mirror for overlapping a plurality of beams from the first reflection-type integrator on the illuminating surface; and a second collector mirror, which is provided between the light source and the first reflection-type integrator for overlapping a second reflection-type integrator and a plurality of beams from the second reflection-type integrator on the first reflection-type integrator.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an illuminating device, and more particularly, to an extreme ultraviolet region (EUV) having a wavelength of 200 nm to 10 nm as a light source.
t) or an illuminating device for exposing an object to be processed, such as a single crystal substrate for a semiconductor wafer or a glass substrate for a liquid crystal display (LCD), using an emission light source in the X-ray region, an exposure apparatus, and a device manufacturing method. .

[0002]

2. Description of the Related Art As a method of manufacturing a semiconductor circuit element having a fine pattern, for example, E having a wavelength of 13.4 nm is used.
There is a reduction projection exposure method using UV light. In this method, a mask or reticle on which a circuit pattern is formed (these are used interchangeably in the present application) is illuminated with EUV light, and an image of the pattern on the mask is reduced and projected onto a wafer surface, so that The resist is exposed and the pattern is transferred.

The resolution R of the projection exposure apparatus is given by the following equation using the wavelength λ of the exposure light source, the numerical aperture (NA) of the exposure apparatus and the proportional constant k ₁ .

[0004]

[Equation 1]

The focus range capable of maintaining a constant imaging performance is called the depth of focus, and the depth of focus DOF is a proportional constant k ₂
Is given by

[0006]

[Equation 2]

FIG. 18 shows an outline of a main part of a conventional EUV reduction projection exposure apparatus 1000. In FIG. 18, reference numeral 1001 is an emission point of EUV light, 1002 is an EUV light flux, 1003 is a filter, 1004 is a first rotation parabolic mirror, 100
Reference numeral 5 is a reflection type integrator, 1006 is a second rotation parabolic mirror, 1007 is a reflection type mask, 1008 is a plurality of mirror systems constituting a projection optical system, 1009 is a wafer, 1
010 is a mask stage, 1011 is a wafer stage,
1012 is an arcuate aperture, 1013 is a laser light source,
Reference numeral 1014 is a laser focusing optical system, and 1017 is a vacuum container. Further, FIG. 19 shows the illumination area 10 on the mask 1007.
15 is a plan view showing the relationship between 15 and an arcuate region 1016 where exposure is performed. FIG.

As described above, the exposure apparatus 1000 has the EUV
Light source units 1013 and 1014 that generate light, an illumination optical system (that is, a first rotation parabolic mirror 1004, a reflective integrator 1005, and a second rotation parabolic mirror 100).
6), a reflective mask 1007, a projection optical system 1008, a wafer 1009, a stage 1010 having a mask mounted thereon, a stage 1011 having a wafer mounted thereon, an alignment mechanism (not shown) for precisely aligning the positions of the mask and the wafer, EU
A vacuum container 1017 for keeping the entire optical system in a vacuum in order to prevent V light from being attenuated, and an exhaust device (not shown).

The illumination optical system is used for the EU from the light emitting point 1001.
The V light 1002 is condensed by the first rotation parabolic mirror 1004 and is irradiated to the reflection type integrator 1005 to form a secondary light source. Further, the EUV light from this secondary light source is converted into a second rotation parabola. The surface mirror 1006 collects the light so that they are superposed,
The mask 1007 is uniformly illuminated.

The reflective mask 1007 has a transfer pattern in which a non-reflective portion such as an EUV absorber is provided on a multilayer-film reflective mirror. The EUV light having the information on the circuit pattern reflected by the reflective mask 1007 is imaged on the surface of the wafer 1009 by the projection optical system 1008.

The projection optical system 1008 is designed so that a thin arc-shaped region off-axis with respect to the center of the optical axis has good image forming performance. Therefore, an aperture 1012 having an arcuate opening is provided in front of the wafer 1009 so that only the thin arcuate region is used for exposure. Then, in order to transfer the pattern on the entire surface of the rectangular mask,
The reflective mask 1007 and the wafer 1009 are simultaneously scanned and exposed.

Here, the projection optical system 1008 is composed of a plurality of multilayer film reflecting mirrors, and is configured to project the pattern on the mask 1007 onto the surface of the wafer 1009 in a reduced scale. Usually, an image side telecentric system is used. .
The object side (reflective mask side) is the reflective mask 10
In order to avoid physical interference with the illumination light flux incident on 07, it is usually a non-telecentric configuration.

Laser light from the laser light source 1013 is condensed by a laser condensing optical system 1014 on a target (not shown) located at a light emitting point 1001 to generate a high temperature plasma light source. The EUV light 1002 emitted from this plasma light source by thermal radiation is the first rotation parabolic mirror 100.
It is reflected by 4 and becomes a parallel EUV light flux. This light flux is reflected by the reflection type integrator 1005 to form a large number of secondary light sources.

The EUV light from this secondary light source is reflected by the second rotating parabolic mirror 1006 and reflected by a reflective mask 1007.
Illuminate. Here, the distance from the secondary light source to the second rotation parabolic mirror 1006 and the distance from the second rotation parabolic mirror 1006 to the reflective mask 1007 is equal to the focal length of the second rotation parabolic mirror 1006. It is set.

Since the focus of the second rotary parabolic mirror 1006 is located at the position of the secondary light source, the EUV light emitted from one of the secondary light sources illuminates the reflective mask 1007 as a parallel light beam. This fills the Koehler illumination. That is, an EU that illuminates a certain point on the reflective mask 1007.
V light is a superposition of EUV light emitted from all secondary light sources.

The illuminated area 1015 on the mask surface is shown in FIG.
As shown in FIG. 5, the shape is similar to the planar shape of the reflection surface of the convex or concave mirror that is a component of the reflection type integrator 1005, and is a substantially rectangular area including the arc area 1016 in which exposure is actually performed. The projection optical system 1008 is designed so that the image of the secondary light source is projected on the entrance pupil plane of the projection optical system 1008.

[0017]

The arc area of the mask 1007 is required to be illuminated without unevenness of illuminance. In addition to that, the center of gravity of the light intensity of the light ray incident on the arc area is matched with the center of the light ray. Need to let. However, these conditions are not always satisfied in the conventional EUV reduction projection exposure apparatus 1000. Therefore, if the center of gravity of the light ray does not coincide with the center at a certain point in the arc region, the effect is essentially the same as if the principal ray of the illumination light were shifted from the desired direction and the mask pattern could be exposed normally. It had the problem of disappearing.

Further, as shown in FIG. 19, a mask 100
7 is irradiated with EUV light on a substantially rectangular area 1015 including an arcuate area 1016 where exposure is actually performed, so EUV light that does not contribute to exposure is shielded by the arcuate aperture 1012 on the wafer 1009 and wasted. Was becoming. That is, in the conventional EUV reduction projection exposure apparatus 1000, since the loss of the exposure light amount is very large, the exposure time is long and the throughput cannot be increased.

Furthermore, the conventional EUV reduction projection exposure apparatus 10
00 also has a problem that the optical axis of the reflected light from the mask 1007 does not coincide with the optical axis of the projection optical system 1008 and the reflected light is eclipsed by the projection optical system 1008.

Therefore, an object of the present invention is to illuminate an illuminated area with a uniform illuminance and to make the center of gravity of the light intensity of the light incident on the illuminated area coincide with the center of the light, an exposure apparatus, and the same. It is to provide a device manufacturing method using the same.

Another object of the present invention is to provide an illumination apparatus, an exposure apparatus, and a device manufacturing method using the same, which reduce the amount of light and reduce the exposure time and improve the throughput.

Still another object of the present invention is to provide an illuminator, an exposure apparatus, and a device manufacturing method using the same, in which the optical axis of the reflected light from the mask coincides with the optical axis of the projection optical system. is there.

[0023]

In order to achieve such an object, an illuminating device according to one aspect of the present invention is an illuminating device for illuminating a surface to be illuminated with light having a wavelength of 200 nm or less from a light source. One reflective integrator, a first condenser mirror for superimposing a plurality of light fluxes from the first integrator on the illuminated surface, and provided between the light source and the first reflective integrator. It has a 2nd reflective type integrator and a 2nd condensing mirror which superimposes a plurality of light fluxes from the 2nd reflective type integrator on the 1st reflective type integrator. In such an illuminating device, the second reflective integrator uniformly illuminates the first reflective integrator, so that the first integrator can illuminate the illuminated area with a uniform illuminance distribution and an angular distribution. That is,
With this configuration, the effective light source distribution on the pupil plane of the projection optical system is also made uniform.

In the first and second reflective integrators, a part of cylindrical surfaces are arranged in parallel, and the generatrixes of the cylindrical surfaces of the first and second reflective integrators are substantially orthogonal to each other. Good. The cylindrical surface has a convex shape,
It may be concave or a combination thereof. The illumination device is disposed between the first reflective integrator and the illuminated surface, and has a field stop having an arcuate opening defining an arcuate illumination area on the illuminated surface, and a field stop of the field stop. A reflection optical system that forms an image of the opening on the illuminated surface with the light flux that has passed through the opening may be included. Unnecessary illumination light can be blocked by the masking blade, and unevenness of illuminance can be corrected by partially changing the width of the masking blade. Alternatively, the lighting device comprises:
A field diaphragm is provided between the first reflective integrator and the illuminated surface in the vicinity of the illuminated surface, and has a field stop having an arc-shaped opening for illuminating the illuminated surface with arc-shaped light. You may. Such an illumination device improves the efficiency of the illumination optical system by omitting the reflection optical system. Thus, the masking blade may be close to or spaced from the illuminated area.

The position of the reflective surface of the second reflective integrator and the position of the illuminated surface are in an optically conjugate positional relationship, and the aperture diameter is variable on or near the reflective surface of the second reflective integrator. It may have a different aperture. Such a diaphragm can prevent uneven illumination in the illuminated area.

In the above illumination device, for example, an arcuate illumination area is formed on the illuminated surface,
The first reflective integrator superimposes a secondary light source from the light source in the angular direction of the arcuate region and condenses the plurality of light beams in the radial direction of the arcuate region. Illuminating the illuminated area. Such an illumination method by the first integrator is suitable for illumination in an arc region as in the present invention, unlike the illumination optical system of Koehler illumination using a fly-eye lens.

An illumination device for illuminating a surface to be illuminated with light having a wavelength of 200 nm or less from a light source, the field diaphragm having an arc-shaped opening defining an arc-shaped illumination area on the surface to be illuminated, and the field diaphragm. A reflection optical system that forms an image of the arc-shaped opening on the illuminated surface with a light flux that has passed through the arc-shaped opening.
And an adjusting mechanism that adjusts an incident angle of a principal ray of the light flux passing through the arc-shaped opening with respect to the illuminated surface. The correction mechanism may include, for example, a mechanism that adjusts eccentricity and / or rotational movement of at least one mirror of the reflective optical system.

An exposure apparatus according to another aspect of the present invention illuminates a pattern formed on a reticle or a mask with the above-mentioned illumination device and projects the pattern onto a target object by a projection optical system. This exposure apparatus also has the same operation as the above-mentioned illumination apparatus.

A device manufacturing method as still another aspect of the present invention includes the steps of exposing a substrate with a device pattern using the above-described exposure apparatus, and performing a predetermined process on the exposed substrate. 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, an LSI or a VLS.
It includes semiconductor chips such as I, CCD, LCD, magnetic sensor, thin film magnetic head, and the like.

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.

[0031]

DETAILED DESCRIPTION OF THE INVENTION An exposure apparatus 10 according to a first embodiment of the present invention will be described in detail below with reference to the accompanying drawings.
The exposure apparatus 10 of the present invention is a projection exposure apparatus that performs step-and-scan exposure using EUV light (for example, a wavelength of 13.4 nm) as illumination light for exposure.
The exposure apparatus 10, as shown in FIG.
Illumination optical system 200, mask 300, and projection optical system 40
0 and an object 500 to be processed. Also, the exposure apparatus 10
Is a mask stage 350 on which the mask 300 is placed,
A wafer stage 550 on which the object to be processed 500 is placed is further provided, and the mask stage 350 and the wafer stage 550 are provided.
Is connected to a control unit (not shown) for drive control.
The light source unit 100 and the illumination optical system 200 form an illumination device. Here, FIG. 1 is a schematic view of the exposure apparatus 10.

Since the EUV light has a low transmittance to the atmosphere, the exposure apparatus 10 stores the light source section 100 in the vacuum container 12 and the remaining components 200 to 550 in the vacuum container 14.
It is stored in. However, the present invention includes at least the case where the optical path through which the EUV light passes is maintained in a vacuum atmosphere.

The light source section 100 produces EUV light from the plasma emission point 120. The light source unit 100 includes a nozzle 130 that ejects droplets that are targets for plasma generation, a droplet collection unit 140 that collects and reuses droplets that have not been irradiated with excitation laser light, and a spheroidal mirror 150.
And a filter 170.

The high-output pump pulse laser light 110 emitted from the pump laser section (not shown) including a pump laser light source and a focusing optical system is configured to focus the light at a light emitting point 120. A droplet (for example, Xe) that is a target of the laser plasma light source is continuously ejected from the nozzle 130 at regular time intervals and passes through the converging point 120. Then, when the droplets ejected as described above come to the position of exactly 120, the excitation pulsed laser light 110 irradiates the droplets to generate a high-temperature plasma emission point 120, and thermal radiation from this plasma is generated. EUV light is radially generated by the.

In this embodiment, Xe is used as a target.
Although the droplets are used, Xe gas is injected as a target from a nozzle into a vacuum to use clusters generated by adiabatic expansion, or Xe gas solidified by cooling on a metal surface, Cu, etc. You may choose the tape using the metal of. Further, although the present embodiment employs the laser plasma method to generate EUV light, an undulator may be used as the EUV light source. Further, as a method for producing EUV light, a discharge method such as a Z pinch method, plasma focus, capillary discharge, hollow cathode triggered Z pinch method may be used.

EU radiated from the plasma emission point 120
The V light is condensed by the spheroidal mirror 150, and EU
It is taken out as a V luminous flux 160. Spheroid mirror 15
In No. 0, a reflective multilayer film for efficiently reflecting EUV light is formed, and partly absorbs the radiant energy from the high-temperature plasma 120, so the temperature becomes high during exposure. Therefore, a material such as a metal having a high thermal conductivity is used as a material, and a cooling means (not shown) is provided to constantly cool the material. The filter 170 cuts off plasma and scattered particles (debris) from the surroundings, and cuts off wavelengths unnecessary for EUV exposure. The EUV light flux 160 passes through the window 210 provided on the boundary surface between the vacuum vessels 12 and 14,
It is introduced into the illumination optical system 200 of the vacuum container 14. Window 2
Reference numeral 10 has a function of passing the EUV light flux 160 while maintaining a vacuum.

The illumination optical system 200 uniformly illuminates the mask 300 with arc-shaped EUV light corresponding to the arc-shaped visual field of the reflection-type reduction projection optical system 400, and the rotating parabolic mirror 2
20 and 260, parabolic mirror 240, reflective integrators 230 and 250, and masking blade 27.
0, relay optical systems 282 to 286 (hereinafter collectively referred to as “280” unless otherwise specified), and a correction mechanism 290.
Have and.

The rotary parabolic mirror 220 reflects the EUV light flux 160 introduced from the window 210 and forms a parallel light flux 22.
Form 2. Next, the EUV light 222 that has become a parallel light beam
Enters a reflective convex cylindrical surface integrator 230 having a plurality of convex cylindrical surfaces 232. Integrator 23
The EUV light emitted from the secondary light source formed by each of the cylindrical surfaces 232 of 0 is condensed by the parabolic mirror 240 to be superimposed, and thus the cylinder of the reflection type integrator 250 having a plurality of convex cylindrical surfaces 252. It is possible to illuminate the alignment direction with a substantially uniform intensity distribution.

The reflection type integrator 230 has a plurality of cylindrical surfaces, and together with the paraboloidal mirror 240, illuminates the reflection type integrator 250 uniformly (that is, almost by Koehler illumination as described later). This makes it possible to make the radial light intensity distribution of the circular arc illumination region, which will be described later, uniform and also make the effective light source distribution from the reflective integrator 250 uniform. Reflective integrator 230, 250
Is a fly-eye mirror 230 in which a large number of minute convex or concave spherical surfaces having a repeating period as shown in FIG.
It may be substituted with A.

The reflective integrator 250 has a plurality of cylindrical surfaces and uniformly illuminates the mask surface. Here, the principle of uniformly illuminating the arc region by the integrator 250 will be described in detail with reference to FIGS. 2 to 4. Here, FIG. 2A is a schematic perspective view when parallel light is incident on an integrator 250 having a plurality of reflective convex cylindrical surfaces 252. The incident direction of the light rays represents the case of the integrator 250. 2 (b) is shown in FIG.
A plurality of reflective concave cylindrical surfaces 2 having the same effect as (a)
FIG. 52B is a schematic perspective view of an integrator 250A having 52A. The integrator 230 also has the same structure as the integrator 250 having the reflective convex cylindrical surface 252 shown in FIG. Integrators 230 and 250
Are both the reflective concave cylindrical surface 252A shown in FIG.
May be replaced by the integrator 250A having the above structure, or may be configured by a combination of these irregularities.

As shown in FIG. 2A, a plurality of cylindrical surfaces 2
When a substantially parallel EUV light flux is incident on the reflection type integrator 250 having 52, a secondary light source is formed by the integrator 250, and the angular distribution of the EUV light emitted from this secondary light source has a conical surface shape. Then, the EUV light is reflected by the reflecting mirror having the focal point at the position of the secondary light source to illuminate the mask 300 or the surface conjugate with the mask 300, whereby arc-shaped illumination can be performed.

FIG. 3 is a partially enlarged view of an integrator 250 having a reflective convex cylindrical surface 252, FIG. 4 (a) and FIG.
FIG. 5B is a perspective view and a vector diagram for explaining EUV light reflection on the cylindrical surface 252 of the integrator 250 having the reflective convex cylindrical surface 252. FIG.
FIG. 6 is a diagram for explaining an angular distribution of EUV light reflected by a cylindrical surface 252 of an integrator 250 having No. 2;

In order to explain the operation of the reflection type integrator 250 having a plurality of cylindrical surfaces 252, first, the behavior of reflected light when parallel light is incident on one cylindrical reflecting mirror will be described with reference to FIG. explain. Now, as shown in FIG. 4A, consider a case where parallel light is incident on one cylindrical surface at an angle of θ with respect to a surface (xy plane) perpendicular to the Z axis that is the central axis thereof. When the parallel ray vector of incident light is P ₁ and the normal vector of the cylindrical reflecting surface is n,
P ₁ and n are defined by the following vector expressions. For the sake of convenience, the arrows representing the vectors attached to the heads of P ₁ and n are omitted, unless otherwise specified.

[0044]

[Equation 3]

[0045]

[Equation 4]

Referring to FIG. 4 (b), if the orthogonal projection vector of -P ₁ to n is a, then a is expressed by the following equation.

[0047]

[Equation 5]

The ray vector of the reflected light P ₂ is given by the following equation.

[0049]

[Equation 6]

From Equations 5 and 6, P ₂ is given by the following equation.

[0051]

[Equation 7]

At this time, the ray vector of the reflected light P ₂ is xy
If the vector projected on the plane is Q, then Q is given by the following equation.

[0053]

[Equation 8]

From this, when plotted in the phase space shown in FIG. 5, Q is −2φ ≦ 2α on the circumference of the radius R = cos θ.
It exists in the range of ≦ 2φ. That is, the reflected light P ₂ becomes a diverging light in the shape of a conical surface, and the secondary light source exists at the position of the apex of this conical surface. If the cylindrical surface is a concave surface, this secondary light source exists as a real image outside the reflecting surface, and if it is a convex surface, it exists inside the reflecting surface as a virtual image.

Further, as shown in FIG. 3, when the reflecting surface is limited to a part of the cylindrical surface and the central angle is 2φ,
As shown in FIG. 5, the ray vector of the reflected light P ₂ is an arc having a central angle of 4φ on the xy plane.

Next, parallel light is incident on the reflecting mirror formed of a part of the cylindrical surface, and the parabolic reflecting mirror of the focal length f has a focal point at the position of this secondary light source, and further this parabolic rotating surface. Consider a case where the irradiated surface is arranged at a position away from the reflecting mirror by f. The light emitted from the secondary light source becomes a divergent light having a conical surface shape, is reflected by a reflecting mirror having a focal length f, and then becomes parallel light. The reflected light at this time becomes a sheet beam having an arc-shaped cross section with a radius f × cos θ and a central angle 4φ. Therefore, the radius f × on the irradiated surface
Only the arcuate region having a central angle of 4φ is illuminated with cos θ.

Up to now, one cylindrical reflecting mirror has been described. Next, as shown in FIG. 2A, a large area integrator 250 in which a large number of cylindrical surfaces 252 are arranged in parallel is used. Consider a case in which parallel light of D is incident in the direction shown. As in the previous example, if the rotating parabolic reflector and the mask 300 are arranged, the angular distribution of the light reflected by the reflectors having a large number of parallel cylindrical surfaces is the same as in the previous example. On the mask 300, an arcuate region having a radius of f × cos θ and a central angle of 4φ is illuminated. Also, the mask 300
The light incident on one point above reaches from the entire irradiation area of the reflecting mirror in which a large number of cylindrical surfaces are arranged in parallel, so that the angular spread is D / f. The numerical aperture NA is given by sin θ, and the numerical aperture of the illumination optical system 200 is D / (2f). Assuming that the numerical aperture on the mask 300 side of the projection optical system 400 is NAp1, the coherence factor σ is σ = D / (2fNAp
It becomes 1). Therefore, the optimum coherence factor σ depends on the thickness of the parallel light incident on the integrator 250.
Can be set to.

The principle of illuminating the circular arc area by the integrator 250 described above, and further the integrator 23
With reference to FIG. 6, which extracts the vicinity of the integrators 230 and 250 of FIG. 1, the main configuration of the present embodiment capable of more effectively and uniformly illuminating the arc region by using 0 will be described in detail below. Explained.

In FIG. 6, the linear directions 235 of the plurality of convex cylindrical reflecting surfaces 232 of the integrator 230 are arranged in the direction perpendicular to the paper surface. In the figure, 233 is the lower surface of the integrator 230. In addition, the linear direction 25 of the plurality of convex cylindrical reflecting surfaces 252 of the integrator 250.
5 is arranged in a direction parallel to the paper surface. In the figure, 253 is an upper surface of the integrator 250.

As mentioned above, the two integrators 2
It is an important point of this embodiment that the spatial arrangement of 30 and 250 is such that the alignment directions 235 and 255 of the convex cylindrical reflecting surfaces 232 and 252 are orthogonal to each other, which results in a more uniform arc illumination as shown below. It will be possible.

When the substantially parallel EUV light beam 222 enters the reflecting surface 231 of the integrator 230 as shown in FIG. 6, that is, perpendicularly to the direction 235, a virtual image of the secondary light source is generated inside the integrator 230. Then, the EUV light is reflected from each secondary light source at a relatively small predetermined divergence angle θ ₁ . The diverging EUV light is parabolic mirror 24
The light beam is incident on the reflecting surface 251 of the integrator 250 as a substantially parallel light beam via 0.

The parabolic mirror 240 is arranged so that its focal position substantially coincides with the reflecting surface 231 of the integrator 230, and the light reflected from each cylindrical surface 232 on the reflecting surface 231 is reflected by the integrator 250. 251 are set so as to overlap each other. Since the parabolic mirror 240 may make the light intensity distribution in the longitudinal direction of the cylindrical reflecting surface 251 of the integrator 250 uniform,
It is necessary to have a parabolic cross section, but not necessarily a rotating parabolic mirror. Thus parabolic mirror 240
Are arranged on the reflecting surface 251 of the integrator 250 so as to provide almost Koehler illumination. With such an arrangement, the reflecting surface 2 of the integrator 250 is
A more uniform intensity distribution is formed on 51, especially in the direction of 255.

The EUV light flux reflected by the integrator 250 having the plurality of convex cylindrical reflecting surfaces 252 is condensed by the rotating parabolic mirror 260 as already described in detail with reference to FIGS. The masking blade 270 placed at the focal length f thereof.
Form a uniform arc illumination area on top.

The masking blade 270 has a light-shielding portion 272 made of a material that absorbs EUV light, and a desired arc-shaped opening 274 optimal for exposure as shown in the front view of a part of FIG. Have. Masking blade 2
Reference numeral 70 shields unnecessary stray light that does not contribute to arc illumination, and a slit width varying mechanism (not shown) sets a desired slit width or partially changes the slit width to satisfactorily correct illuminance unevenness. It has the function of

With the above configuration, in the arc illumination area, the angular direction (that is, the θ direction) along the arc.
For multiple cylindrical surfaces 252 of integrator 250.
Uniformity is achieved by superimposing a plurality of light beams from the integrator 230, and in the radial direction (that is, the r direction) perpendicular to the circular arc, the uniformity is achieved by superimposing a plurality of light beams from the integrator 230. Has been achieved. As a result, it is possible to perform uniform arc illumination with much higher efficiency than in the past.

The EUV light flux passing through the arc-shaped opening of the masking blade 270 is converted to a desired magnification by the relay optical system 280, and then an arc illumination area is formed on the reflection type mask 300 held by the mask stage 350. By doing so, arc illumination is performed. The relay optical system 280 formed of a plurality of mirror surfaces has a function of enlarging or reducing an arc shape at a predetermined magnification.

The correction mechanism 290 is a principal ray (optical axis) adjusting mechanism, and by slightly eccentrically moving and rotating the mirror position of the relay optical system 280, the reflection type mask 300 is obtained.
It has a function of correcting so that the reflected light from satisfactorily coincides with the incident side optical axis of the projection optical system 400.

Further, as shown in FIG. 8, a masking blade 270 may be arranged near the mask 300 to reduce the relay optical system 280. Here, FIG. 8 is a schematic view of a main part of a modified example of the exposure apparatus 10 shown in FIG. The same members as those in FIG. 1 are designated by the same reference numerals, and duplicated description will be omitted.

In order to obtain a high reflectance for almost directly incident EUV light on the surface of each mirror including the mask 300,
A multilayer film is formed by repeatedly stacking two types of material layers having a large difference in refractive index and a small absorption at a cycle of about half the exposure wavelength. In order to obtain a reflectance as high as possible, it is usual to use Mo and Si as materials, but the reflectance obtained in that case is about 60% to 70%.
Is.

Therefore, in the illumination optical system 200, it is necessary to minimize the number of mirrors used in order to suppress the loss of the reflection intensity. The feature of this embodiment is that the masking blade 270 having an arc-shaped opening is arranged in the vicinity of the reflection surface of the reflection type mask 300, so that the relay optical systems 282 and 284 in FIG. 1 are omitted and the illumination optical system is omitted. That is, the efficiency of the 200 is improved.

Next, another embodiment of the present invention capable of setting a desired illumination condition will be described with reference to FIG. Here, FIG. 9 is a schematic diagram showing an exposure apparatus 10B according to a third embodiment of the present invention.

In contrast to the exposure apparatus 10 shown in FIG. 1, the exposure apparatus 10B has two reflection type integrators 230 and 230B which can be switched according to a desired illumination condition.
Apertures 236 and 256 and aperture drive systems 238 and 258
Have and.

Reflective integrators 230 and 230B
Is a reflection type integrator having a plurality of convex cylindrical surfaces, but the radii of curvature (and hence power) of the cylindrical surfaces are different from each other. Hereinafter, a method of setting the coherence factor σ, that is, the numerical aperture of the illumination system to a desired value by switching the integrators 230 and 230B will be described.

FIG. 10 is a schematic view of the surface of the integrator 230 having a plurality of convex cylindrical reflecting surfaces 232, and FIG. 11 is a schematic view of the surface of the integrator 230B.
Here, the cylindrical surface 232 of the integrators 230 and 230B
And 232B have radii of curvature r ₁ and r ₂ set to r ₁ <r ₂ .

Now, consider a case in FIG. 10 in which a parallel light beam is incident on the convex cylindrical reflecting surface 231 of the integrator 230 from above the paper surface. In this case, the convex cylindrical reflecting surface 231
The light beam diverges due to, but the light condensing point exists as a virtual image at a position at a distance r _1/2 from the center of curvature O inside the convex surface. Therefore, the reflected light diverges at the divergence angle θ ₁ given by the following equation.

[0076]

[Equation 9]

[0077] Similarly, in the integrator 230B, the focal point is present as a virtual image from the center of curvature O of the convex cylindrical surface 232B at a distance _r 2/2. Therefore, the reflected light diverges at the divergence angle θ ₂ given by the following equation.

[0078]

[Equation 10]

Here, the relation of θ ₁ > θ ₂ is established from r ₁ <r ₂ . That is, the divergence angle θ ₁ of the light flux reflected by the integrator 230 is better than the integrator 230B.
Is larger than the divergence angle θ ₂ of the reflected light beam.

12 and 13 show the integrator 23.
FIG. 6 is a schematic diagram illustrating a method of switching the numerical aperture of the illumination optical system 200 by switching between 0 and 230B. Figure 1
2, the EUV light beam 222 that is almost parallel is a diaphragm 236.
When incident on the cylindrical reflecting surface 231 of the integrator 230 as shown in the figure, a virtual image of the secondary light source is generated inside the integrator 230, and the virtual image of the secondary light source is 2 at each predetermined divergence angle θ _1.
EUV light is reflected from the secondary light source. That divergent EUV
The light is condensed by the parabolic mirror 240 having the focal length f ₁ and is incident on the reflecting surface 251 of the integrator 250 as a substantially parallel light flux via the diaphragm 256.

The EUV light flux reflected by the integrator 250 having the plurality of convex cylindrical reflecting surfaces 251 is condensed by the rotating parabolic mirror 260 and its focal length f is obtained.
_On the masking blade 270 arranged at the position of ₂ ,
Form a uniform arc illumination area. Here, the numerical aperture of the illumination optical system 200 in the masking blade 270 is set to NA.
₁ is given by the following equation.

[0082]

[Equation 11]

The numerical aperture NA ₁ is an amount proportional to the numerical aperture of the illumination optical system 200 on the reflective mask 300, and is proportional to the divergence angle θ ₁ .

As shown in FIG. 13, the integrator 23
When 0 is switched to 230B by a switching mechanism (not shown), similarly, the numerical aperture NA ₂ of the illumination optical system 200 in the masking blade 270 is given by the following equation.

[0085]

[Equation 12]

From θ ₁ > θ ₂ , a larger numerical aperture of the illumination optical system 200 is obtained when the integrator 230 is used and a larger coherence factor σ is obtained than when the integrator 230B is used.

In the above description, two integrators 2 are used.
Although an example in which 30 and 230B are switched has been shown, two or more integrators 230 having different divergence angles may be switched using a turret or the like in order to change the coherence factor σ stepwise. In accordance with the switching of the integrator 230, the diaphragm 256 may be switched to control the incident light beam diameter to the integrator 250 to a desired size, thereby performing more accurate control of σ.

The diaphragm 236 is the reflection type integrator 23.
It is provided on the front surface of 0 or 230B and has a light shielding portion 237a and an opening portion 237b. The diaphragm 236 is the diaphragm drive system 23.
It is possible to continuously change the opening diameter of the opening portion 237b by being driven by the control unit 8. The opening diameter of the opening 237b is
It is adjusted by a signal from a control system (not shown) input to the diaphragm drive system 238. The iris driving system 238 may be of any configuration known in the art, such as an iris diaphragm device using a cam.

By changing the aperture diameter of the diaphragm 236 (as indicated by the dotted line in the figure), the spread of the light beam incident on the integrator 250 in the direction parallel to the paper surface can be adjusted. That is, if the aperture diameter of the diaphragm 236 is increased in FIG. 9, it is possible to adjust the radial width of the arc slit, which is the illumination area, in the masking blade 270. In addition, the integrators 230 and 23
The thickness D of the light beam incident on the integrator 250 is adjusted not only by switching 0B but also by adjusting the diaphragm 256.
Can be changed to change the coherence factor .sigma. To a desired value, and illuminance unevenness can be corrected.

The diaphragm 256 is a reflection type integrator 25.
It is provided on the front surface of 0 and can be driven by the diaphragm drive system 258 to form a desired effective light source distribution. The diaphragm 256 has a light shielding portion 257a and an opening portion 257b.

EUV reflected by the integrator 250 having a plurality of convex cylindrical reflecting surfaces through the diaphragm 256.
The light flux is condensed by the rotating parabolic mirror 260, and forms a uniform arc illumination area on the masking blade 270 arranged at the focal position thereof.

A method of performing modified illumination such as annular illumination by switching the diaphragm 256 will be described below with reference to FIGS. 14 and 15. 14A to 14C are plan views showing diaphragms applicable to the diaphragm 256. 14
FIG. 14A shows the diaphragm 256A in the case of normal illumination, and FIG.
14B shows the diaphragm 256B in the case of so-called annular illumination, and FIG. 14C shows the diaphragm 2 in the case of so-called quadrupole illumination.
56C is shown. As shown in the diaphragm 256 of FIG. 9, such several opening patterns are prepared as, for example, a turret, and the turret is rotated by receiving a signal from a control system (not shown) by the diaphragm drive system 258. It is possible to switch to a desired opening shape. Also, other mechanical methods without using a turret, for example,
A plurality of diaphragms may be arranged and switched sequentially.

As shown in FIG. 9, the diaphragm 256 is arranged near the reflecting surface 251 of the integrator 250. Therefore, the incident angle of the light flux incident on the integrator 250 is θ
Then, on the reflecting surface 251 of the integrator 250, the luminous flux diameter extends in the direction parallel to the paper surface at a magnification of 1 / cos θ. As a result, the shape of the opening 257b of the diaphragm 256 also needs to be expanded in the same direction at a magnification of 1 / cos θ. In FIG. 14, for example, the diaphragm 256A is used to narrow the incident light flux diameter into a circle, and the aspect ratio of this ellipse is 1 / cos θ. The same applies to the diaphragms 256B and 256C.

Next, the modified illumination is performed by the diaphragm 256.
As for the principle, the aperture 256B is set to the annular illumination mode.
Will be described as an example. The modified illumination method is proportional to
A few k ₁Super-resolution for miniaturization by reducing the value of
Technology (RET: Resolution Enhancement)
d Technology). Equation 1
If the resolution is improved by shortening the wavelength,
However, the modified illumination method
It is preferable because it does not reduce the depth of focus.

FIG. 15 shows an integrator 25 shown in FIG.
0, rotating parabolic mirror 260, masking blade 27
FIG. 15A is a diagram in which 0 is extracted, FIG. 15A is a side view, and FIG.
5B is a top view seen through the mirror 260. The diaphragm 256B for the annular illumination mode is shown in FIG.
Although it is arranged as shown in FIG. 15A, it is not shown in FIG. 15B for ease of explanation.

The light beam incident on the reflection type integrator 250 is shielded by the diaphragm 256 at the central part of the optical axis and a part of the outer diameter part, and is reflected by the elliptical annular shape distribution 259. The shape of the distribution 259 matches the shape of the opening of the diaphragm 256B. This luminous flux is condensed by the rotating parabolic reflector 260 to form an arc-shaped uniform illumination area at the position of the masking blade 270 arranged at the position of the focal length f ₂ . At this time, since the center of the light flux is shielded,
The condensed light flux becomes the light flux indicated by the hatching portion 262 in FIG. This also applies to FIG. 15 (b),
It becomes the light flux shown by the hatching portion 264. In this way, the reflective integrator 250 superimposes the secondary light source in the angular direction of the arc region and condenses all the light fluxes into one point in the radial direction of the arc region (by critical illumination). Illuminate. This indicates that at the position of the intersection of the chief ray and the optical axis, that is, at the pupil plane position 295, a distribution like 278, that is, annular illumination is performed.

Returning to FIG. 1 again, the exposure method of the present embodiment will be continuously described. The same applies to the mask 300 and the subsequent figures in FIGS. 8 and 9.

The reflective mask 300 has a transfer pattern in which a non-reflective portion made of an EUV absorber or the like is provided on a multilayer-film reflective mirror. The EUV reflected light having the circuit pattern information from the reflective mask 300 illuminated in an arc shape is projected and imaged by the projection optical system 400 on the object 500 to which the photosensitive material is applied at a magnification optimum for exposure. so,
The circuit pattern is exposed. The projection optical system 400 of this embodiment is a reflection type projection optical system composed of six mirrors, but the number of mirrors is not limited to six, and four mirrors are provided.
Any desired number such as 5, 5, or 8 can be used.

The object 500 to be processed is the wafer stage 55.
It is fixed at 0 and has a function of moving in parallel in the vertical and horizontal directions on the paper surface, and its movement is controlled by a length measuring device such as a laser interferometer (not shown). When the magnification of the projection optical system 400 is M, for example, the reflective mask 300 is scanned at a speed v in a direction parallel to the paper surface, and at the same time, the object 50 to be processed is scanned.
Synchronous scanning of 0 in a direction parallel to the paper surface at a speed v / M allows the entire surface exposure.

In the present embodiment, the wafer is exposed, but the processed zone 500 as the exposure target is not limited to the wafer, and includes a wide range of liquid crystal substrates and other processed objects. A photoresist is applied to the object 500 to be processed. 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 improver coating treatment is a surface modification treatment (that is, a hydrophobic treatment by applying a surfactant) for enhancing the adhesion between the photoresist and the base, and HMDS (Hexamethyl) treatment.
-Coating or steaming an organic film such as (disilazane). Pre-baking is a baking (baking) process, but it is softer than that after development and removes the solvent.

The wafer stage 550 supports the object 500 to be processed. Any configuration known in the art can be applied to the stage 550, and for example, a linear motor is used to move the object 500 to be processed in the XYZ directions. The mask 300 and the object to be processed 500 are controlled by a controller (not shown) and are synchronously scanned. Also, the mask stage 3
The positions of 50 and the wafer stage 550 are monitored by, for example, a laser interferometer, and both are driven at a constant speed ratio.

Next, with reference to FIGS. 16 and 17, an embodiment of a device manufacturing method using the above-described exposure apparatus 10 will be described. FIG. 16 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 an actual circuit is formed on the wafer by a lithography technique using the mask and the wafer.
Step 5 (assembly) is called the post-process, and step 4
This is a step of forming a semiconductor chip using the wafer created by, including 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. 17 is a detailed flowchart of the wafer process in Step 4. In step 11 (oxidation), the surface of the wafer is oxidized. Step 12 (CVD)
Then, 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 1 exposes the circuit pattern of the mask 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. According to the manufacturing method of this embodiment, it is possible to manufacture a higher quality device than the conventional one. As described above, the device manufacturing method using the exposure apparatus 10 and the resultant device also function as one aspect of the present invention.

Although the preferred embodiments of the present invention have been described above, it goes without saying that the present invention is not limited to these embodiments, and various modifications and changes can be made within the scope of the gist thereof. For example, although the present embodiment has been described using EUV light, the present invention can also be applied to a light source in the X-ray region.

[0105]

According to the illumination device and the exposure device of the present invention, it is possible to perform highly efficient and uniform arc illumination, and to eliminate illuminance unevenness. Further, even if there is a change in the light source, the influence on the exposure can be eliminated by stabilizing the incident angle of the light beam on the irradiation surface.

[Brief description of drawings]

FIG. 1 is a schematic view showing an exposure apparatus according to a first embodiment of the present invention.

FIG. 2 is a schematic perspective view showing two types of integrators applicable to the reflection type integrator of the exposure apparatus shown in FIG.

FIG. 3 is a schematic diagram for explaining the operation of the reflective integrator having the convex cylindrical surface shown in FIG.

FIG. 4 is a schematic perspective view for explaining light flux reflection on a cylindrical surface of the reflection type integrator shown in FIG.

5 is a diagram for explaining an angular distribution of a light beam reflected by the cylindrical surface shown in FIG.

6 is an enlarged view of forming an arc illumination by two integrators of the exposure apparatus shown in FIG.

FIG. 7 is a schematic perspective view showing a modified example of the reflection type integrator on the light source side shown in FIG.

FIG. 8 is a schematic view showing an exposure apparatus according to the second embodiment of the present invention.

FIG. 9 is a schematic view showing an exposure apparatus according to the third embodiment of the present invention.

FIG. 10 is a schematic view of one light source side integrator provided in the exposure apparatus shown in FIG.

11 is a schematic diagram of another light source side integrator provided in the exposure apparatus shown in FIG.

FIG. 12 is a schematic diagram illustrating a method of switching the numerical aperture of the illumination optical system by switching the light source side integrator of the exposure apparatus shown in FIG.

13 is a schematic diagram illustrating a method of switching the numerical aperture of the illumination optical system by switching the light source side integrator of the exposure apparatus shown in FIG.

14 is a plan view showing an example of a diaphragm used in a mask-side integrator of the exposure apparatus shown in FIG.

FIG. 15 is a diagram showing a mask-side integrator, a rotary parabolic mirror, and a masking blade extracted from the exposure apparatus shown in FIG.

FIG. 16 is a flowchart for explaining the manufacture of devices (semiconductor chips such as IC and LSI, LCDs, CCDs, etc.).

FIG. 17 is a detailed flowchart of the wafer process in Step 4 shown in FIG.

FIG. 18 is a schematic view of a conventional exposure apparatus.

FIG. 19 is a plan view for explaining the relationship between the illumination area of the mask of the exposure apparatus shown in FIG. 18 and the area used for exposure.

[Explanation of symbols]

10, 10A, 10B Exposure apparatus 100 Light source unit 200 Illumination optical systems 230, 230A, 230B Reflective integrator 231 Reflective surface 232 Cylindrical surface 236 Aperture 240 Parabolic mirror 250, 250A Reflective integrator 251 Reflective surface 252 Cylindrical surface 256, 256A -C diaphragm 270 Masking blade 280 (282-288) Relay optical system 300 Reflective mask 400 Projection optical system 500 Object to be processed

─────────────────────────────────────────────────── ─── Continued Front Page (51) Int.Cl. ⁷ Identification Code FI Theme Coat (Reference) H01L 21/30 531A

Claims (14)

[Claims] 1. A lighting device for illuminating a surface to be illuminated with light having a wavelength of 200 nm or less from a light source, wherein a first reflection type integrator and a plurality of light fluxes from the first integrator are provided on the surface to be illuminated. A first condensing mirror that is superposed on the first reflection mirror, and a plurality of light beams from the second reflection type integrator and the second reflection type integrator that are provided between the light source and the first reflection type integrator. And a second condensing mirror which is superposed on the reflection type integrator. 2. The first and second reflection type integrators, wherein a plurality of cylindrical surfaces are partially arranged in parallel,
The illuminating device according to claim 1, wherein the generatrixes of the cylindrical surfaces of the second reflection type integrator are substantially orthogonal to each other. 3. The lighting device according to claim 2, wherein the cylindrical surface has a convex shape, a concave shape, or a combination thereof. 4. The first reflective integrator is configured to perform critical illumination on the illuminated surface for the meridional section of the optical system and Koehler illumination for the sagittal section of the optical system. The lighting device according to. 5. The lighting device according to claim 1, wherein the first reflective integrator has a reflective surface having a repeating structure. 6. A field diaphragm having an arcuate opening portion disposed between the first reflective integrator and the illuminated surface and defining an arcuate illumination area on the illuminated surface, and a field diaphragm of the field diaphragm. The reflection optical system which forms an image of the opening on the illuminated surface by the light flux having passed through the opening.
Illumination device described. 7. An arc opening for illuminating the illuminated surface with arc light is disposed between the first reflective integrator and the illuminated surface in the vicinity of the illuminated surface. The illumination device according to claim 1, further comprising a field stop having the field stop. 8. The position of the reflecting surface of the second reflective integrator and the position of the illuminated surface are in an optically conjugate positional relationship, and an opening diameter is provided on or near the reflective surface of the second reflective integrator. The lighting device according to claim 1, wherein the lighting device has a variable diaphragm. 9. An arcuate illumination area is formed on the illuminated surface, wherein the first reflective integrator includes a secondary light source from the light source in an angular direction of the arcuate area. The illumination device according to claim 1, wherein the illumination target region is illuminated so that the plurality of light beams are overlapped and are condensed in a radial direction of the arc-shaped region. 10. An illumination device for illuminating a surface to be illuminated with light having a wavelength of 200 nm or less from a light source, the field stop having an arc-shaped opening defining an arc-shaped illumination area on the surface to be illuminated, A reflection optical system that forms an image of the arc-shaped opening on the illuminated surface with a light flux that has passed through the arc-shaped aperture of the field stop, and an incident angle of the principal ray of the light flux that has passed through the arc-shaped aperture with respect to the illuminated surface. An illumination device having an adjusting mechanism for adjusting. 11. The illumination device according to claim 10, wherein the correction mechanism includes a mechanism that adjusts eccentricity and / or rotational movement of at least one mirror of the reflection optical system. 12. The wavelength of the light from the light source is 20 n
The lighting device according to claim 1, wherein the lighting device has a length of m or less. 13. An exposure apparatus which illuminates a pattern formed on a reticle or a mask by the illumination device according to claim 1 and projects the pattern onto a target object by a projection optical system. 14. A device manufacturing method comprising: a step of exposing a substrate with a device pattern using the exposure apparatus according to claim 13; and a step of performing a predetermined process on the exposed substrate.