JP2003045784A - Illumination system, aligner, and device-manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an illumination system that can change illumination conditions by light of wavelength of 200 nm or lower from a light source, a aligner, and a device-manufacturing method using the projection aligner. SOLUTION: In the illumination system for lighting a region to be lit by light of wavelength of 200 nm or lower from a light source, the aligner, and the device-manufacturing method using the aligner, there are provided a first reflection-type integrator, a first optical system for making the light to be incident from the light source on the first reflection-type integrator, and a second optical system for making a plurality of luminous fluxes from the first reflection-type integrator onto a surface to be illuminated. In this case, the first optical system has a means of varying the diameter and/or the shape of the light enters 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 parabolic mirror 1006 is located at the position of the secondary light source, EUV emitted from one of the secondary light sources illuminates the reflective mask 1007 with a parallel light beam. This fills the Koehler illumination. That is,
The EUV light that illuminates a certain point on the reflective mask 1007 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]

A conventional EUV reduction projection exposure apparatus 1000 is designed to meet a desired resolution line width and throughput (for example, a mask side NA of an illumination optical system and a mask side NA of a projection optical system). It was difficult to change the illumination conditions such as the ratio coherence factor σ) to the desired one. In addition, the conventional EUV reduction projection exposure apparatus 10
No. 00 uses EUV light having a short wavelength to improve the resolution, but there is a demand for further miniaturization.

Therefore, an object of the present invention is to provide an illuminating device, an exposure device, and a device manufacturing method using the same, which are capable of changing illumination conditions by using a light beam emitted from a light source in an extreme ultraviolet region or an X-ray region. It is in.

Another object of the present invention is to provide an illuminator, an exposure apparatus, and a device manufacturing using the same, which can achieve higher resolution than before by using a light beam emitted from a light source in the extreme ultraviolet region or X-ray region. To provide a method.

[0020]

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. A first reflection type integrator, a first optical system that makes light from the light source enter the first reflection type integrator, and a plurality of light fluxes from the first reflection type integrator are overlapped on the illuminated surface. Two optical systems, and the first optical system is provided with means for varying the diameter and / or the shape of the light incident on the first reflective integrator.

Such means has, for example, a plurality of diaphragms having different opening shapes and / or sizes, and each of the diaphragms is selected on or near the reflecting surface of the first reflective integrator. It may be configured so that it can be provided in a desired manner.

Further, the opening may have a shape extending in a direction along an incident surface when the light is incident on the first reflective integrator. Further, the means includes a second reflection type integrator, a condenser mirror for superposing a plurality of light beams from the second reflection type integrator on the first reflection type integrator, and reflection of the second reflection type integrator. A diaphragm having a variable aperture diameter may be provided on or near the surface. Further, such a means is configured such that a plurality of second reflection type integrators having different divergence angles of the emitted light beam and a plurality of light beams from the second reflection type integrator are superposed on the first reflection type integrator. And a mirror, and each of the plurality of second reflective integrators may be selectively provided in the optical path of the light from the light source.

Further, a diaphragm having a variable aperture diameter may be provided on or near the reflection surface of the second reflection type integrator.

An illumination device as another aspect of the present invention is an illumination device that illuminates a surface to be illuminated with light having a wavelength of 200 nm or less from a light source, and includes a first reflection type integrator and the light from the light source. A first optical system that is incident on the first reflective integrator, a second optical system that superimposes a plurality of light fluxes from the first reflective integrator on the illuminated surface, and a first optical system of the first reflective integrator. A diaphragm is provided on or near the reflecting surface.

The diaphragm may have an opening having a shape extending in a direction along an incident surface when the light enters the first reflective integrator.

An illumination device as another aspect of the present invention is an illumination device that illuminates a surface to be illuminated with light having a wavelength of 200 nm or less from a light source, and includes a first reflection type integrator having a reflection surface at a pupil position. A first optical system that causes light from the light source to obliquely enter the first reflective integrator, and a second optical system that superimposes a plurality of light beams from the first reflective integrator on the illuminated surface, A diaphragm having an opening having a shape extending in a direction along the incident surface when the light obliquely enters the first reflective integrator, is provided on or near the reflective surface of the first reflective integrator. .

The shape may be a circular shape for normal illumination, but a shape for deforming and illuminating the illuminated area is preferable because the proportionality constant k ₁ in Formula ₁ is reduced to contribute to the improvement of resolution. The shape in the latter case is, for example, an annular shape or a quadrupole shape.

In addition, an arcuate illumination area is formed on the illuminated surface, and the first reflective integrator includes a secondary light source from the light source in an angular direction of the arcuate area. An illuminating device may be configured to overlap and illuminate the illuminated area so as to collect the plurality of light beams in the radial direction of the arcuate area. Such an illumination method by the first integrator is a configuration example suitable for the reflection type illumination optical system like the present invention, unlike the illumination optical system of Koehler illumination using a lens.

The light of the light source type of the above illumination device has a wavelength of 20n.
Extreme ultraviolet rays of m or less may be used.

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.

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. This device manufacturing method claim extends to the device itself, which is an intermediate and final product. 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 become apparent from the preferred embodiments described below with reference to the accompanying drawings.

[0033]

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 unit 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-power 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 be focused at the 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. EUV light flux 160 is EUV
The light beam 160 is transmitted through the window 210 provided on the boundary surface between the vacuum containers 12 and 14 to the illumination optical system 200 of the vacuum container 14.
Will be introduced to. EUV while maintaining vacuum in window 210
It has a function of passing the light beam 160.

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 100, 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 paraboloid of revolution mirror 220 reflects the EUV light flux 160 introduced from the window 210 to form 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 rotation parabolic mirror 240, illuminates the reflection type integrator 250 uniformly (that is, with almost 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 reflective 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.

[0046]

[Equation 3]

[0047]

[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.

[0049]

[Equation 5]

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

[0051]

[Equation 6]

From Equations 3 and 4, P ₂ is given by the following equation.

[0053]

[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.

[0055]

[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 a reflecting mirror formed by a part of a cylindrical surface, and a rotating parabolic reflecting mirror having a focal length f and having a focal point at the position of this secondary light source, and further this rotating parabolic 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 surface 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 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 is incident on the reflecting surface 231 of the integrator 230 as shown in FIG. 6, that is, perpendicular 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 must have a paraboloidal cross section, but not necessarily a rotating parabolic mirror. In this way, the parabolic mirror 24
0 is on the reflecting surface 251 of the integrator 250,
It is arranged so that it is almost Koehler lighting. With such an arrangement, a more uniform intensity distribution is formed on the reflecting surface 251 of the integrator 250, particularly 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 that is 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 that has passed through the arc-shaped opening of the masking blade 270 is converted into a desired magnification by the relay optical system 280, and then an arc illumination area is formed on the reflective 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) adjustment mechanism, and by slightly eccentrically moving and rotating the mirror position of the relay optical system 280, the reflection type mask 300 can be 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 EUV light that is almost directly incident 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 radii of curvature r ₁ and r ₂ of the cylindrical surfaces 232 and 232B of the integrators 230 and 230B are r ₁
<R ₂ is set.

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.

[0078]

[Equation 9]

[0079] 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.

[0080]

[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 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 EUV light is reflected from each secondary light source at a predetermined divergence angle θ _1. . The diverging EUV light is condensed by the parabolic mirror 240 having the focal length f ₁ and is reflected by the reflecting surface 251 of the integrator 250 via the diaphragm 256.
Is incident as a substantially parallel light beam.

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
_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.

[0084]

[Equation 11]

The numerical aperture NA ₁ is 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.

[0087]

[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. Further, by placing the diaphragm 236 on or near the surface of the reflective integrator 230 or 230B, it is possible to allow the light flux that has once passed through the diaphragm 236 to pass through the diaphragm 236 again without being vignetted. The opening diameter of the opening 237b 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 shown 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 becomes large in FIG. 9, it is possible to adjust the radial width of the arc slit serving as the illumination area in the masking blade 270 in FIG. In addition, not only switching between the integrators 230 and 230b but also adjusting the diaphragm 256 to change the thickness D of the light beam incident on the integrator 250 to change the coherence factor σ to a desired value or to correct uneven illuminance. You can also do it.

The diaphragm 256 is a reflection type integrator 25.
It is provided on the front surface of 0 and is driven by the diaphragm drive system 258 to continuously change the aperture diameter to form a desired effective light source distribution. The diaphragm 256 has a light shielding portion 257a and an opening portion 257b. Further, by placing the diaphragm 256 on the surface of the reflection type integrator 250 or in the vicinity thereof, it is possible to allow the light flux that has once passed through the diaphragm 256 to pass through the diaphragm 256 again without being vignetted.

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 light beam diameter is 1 / cos in the direction along the incident surface when the light beam enters the integrator 250 (the direction parallel to the paper surface).
Extend at a magnification of θ. As a result, the aperture 2 of the diaphragm 256
The shape of 57b also needs to be stretched in the same direction at a magnification of 1 / cos θ. In FIG. 14, for example, the diaphragm 25
6A is used for narrowing the incident light beam diameter into a circle,
The aspect ratio of this ellipse is 1 / cos θ. Aperture 2
The same applies to 56B 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).

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 light 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 up and down and back and forth 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 500 is synchronized at a speed v / M in a direction parallel to the paper surface. By scanning, the entire surface is exposed.

In the present embodiment, the wafer is exposed, but the object 500 to be exposed is not limited to the wafer, but includes a wide range of liquid crystal substrates and other 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.

[0107]

According to the illumination device and the exposure device of the present invention, it is possible to change the illumination condition to a desired condition by utilizing EUV light, and it is possible to achieve higher resolution than before by the modified illumination. it can.

[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

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) G03F 7/20 521 H01L 21/30 527 517 531A F term (reference) 2H042 DA08 DA09 DB02 DB13 DD06 DD08 DD10 DE04 2H052 BA03 BA09 BA12 2H087 KA21 KA29 NA04 TA00 TA02 TA06 5F046 BA05 CA08 CB02 CB03 CB05 CB13 CB17 CB23 GA03 GA07 GB01 GC03 GD10

Claims (16)

[Claims] 1. An illuminating 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 reflective integrator and light from the light source are incident on the first reflective integrator. A first optical system and a second optical system that superimposes a plurality of light fluxes from the first reflective integrator on the illuminated surface, and the first optical system is the first reflective integrator. An illumination device comprising means for varying the diameter and / or the shape of incident light. 2. The means has a plurality of diaphragms having different opening shapes and / or sizes, and each of the diaphragms is selected on or near a reflecting surface of the first reflective integrator. The illuminating device according to claim 1, wherein the illuminating device can be provided selectively. 3. The illumination device according to claim 2, wherein the opening has a shape extending in a direction along an incident surface when the light is incident on the first reflective integrator. 4. The second means comprises: a second reflective integrator; a condenser mirror for superposing a plurality of light beams from the second reflective integrator on the first reflective integrator; and a second reflective type. The illumination device according to claim 1, further comprising a diaphragm having a variable aperture diameter on or near a reflecting surface of the integrator. 5. The plurality of second reflection type integrators having different divergence angles of the emitted light flux, and the second means.
A condenser mirror for superposing a plurality of light beams from the reflection type integrator on the first reflection type integrator,
The lighting device according to claim 1, wherein each of the plurality of second reflective integrators can be selectively provided in an optical path of light from the light source. 6. The illumination device according to claim 5, further comprising a diaphragm having a variable aperture on or near a reflective surface of the second reflective integrator. 7. An illumination 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 reflective integrator and the light from the light source are incident on the first reflective integrator. A first optical system, a second optical system that superimposes a plurality of light beams from the first reflective integrator on the illuminated surface, and a diaphragm on or near the reflective surface of the first reflective integrator. Lighting device having. 8. The illumination device according to claim 7, wherein the diaphragm has an opening having a shape extending in a direction along an incident surface when the light is incident on the first reflective integrator. 9. 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 first reflection type integrator having a reflection surface at a pupil position, and the light from the light source to the first light source. First optical system for obliquely entering the reflection type integrator, a second optical system for superposing a plurality of light beams from the first reflection type integrator on the illuminated surface, and a reflection surface of the first reflection type integrator. An illumination device having, on or near the aperture, an aperture having a shape that extends in a direction along an incident surface when the light obliquely enters the first reflective integrator. 10. The illumination device according to claim 9, wherein the shape is a shape for deforming and illuminating the illuminated area. 11. The shape is an annular shape.
Illumination device described. 12. The shape is a quadrupole shape.
The lighting device according to 0. 13. An arc-shaped illumination area is formed on the surface to be illuminated, wherein the first reflective integrator includes a secondary light source from the light source in an angular direction of the arc-shaped area. The illumination device according to claim 9, wherein the illumination target region is illuminated so as to be superimposed and to focus the plurality of light beams in a radial direction of the arc-shaped region. 14. The illumination device according to claim 1, wherein the light from the light source is extreme ultraviolet light having a wavelength of 20 nm or less. 15. An exposure apparatus for illuminating a pattern formed on a reticle or a mask with the illumination device according to claim 1, and projecting the pattern onto a target object by a projection optical system. . 16. A device manufacturing method comprising: a step of exposing a substrate with a device pattern using the exposure apparatus according to claim 15; and a step of performing a predetermined process on the exposed substrate.