JPH11243052A - Aligner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To effectively suppress the deterioration of image forming characteristics caused by the irradiation of illuminating light. SOLUTION: This device has a heat pipe HP, which is arranged in a non- irradiated region of illuminating light on the reflecting surface of a mirror M1, formed of material (low-expansion glass) having low thermal conductivity in a plurality of mirrors constituting a projecting optical system PO, and a cooling jacket 52 connected to the heat pipe HP. As a result, the advantage of the low-expansion glass, which does not deteriorate the image forming characteristics through deformation for considerable temperature change, is utilized. At the same time, the reflecting surface is cooled directly so that the temperature change exceeding the limit is not generated. Thus, the deterioration of the image forming characteristics of the projecting optical system caused by the irradiation of the illuminating light can be prevented. As a result, the deterioration of the image forming characteristics caused by the irradiation of the illuminating light can be suppressed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exposure apparatus,
More specifically, the present invention relates to an exposure apparatus used when a circuit device such as a semiconductor element or a liquid crystal display element is manufactured by a lithography process.

[0002]

2. Description of the Related Art At present, at a semiconductor device manufacturing site,
The minimum line width is 0.3 using a reduction projection exposure apparatus, i.e., a so-called stepper, using i-line of a mercury lamp having a wavelength of 365 nm as illumination light.
Circuit devices of about 0.35 μm (64 M (mega) bit D-RAM and the like) are mass-produced. At the same time, 2
An exposure apparatus for mass-producing a next-generation circuit device having a 56-Mbit, 1-G (giga) -bit D-RAM class density and a minimum line width of 0.25 μm or less has been introduced.

As an exposure apparatus for manufacturing the next generation of circuit devices, a wavelength 248 from a KrF excimer laser light source is used.
An ultraviolet pulse laser beam having a wavelength of 193 nm or an ultraviolet pulse laser beam having a wavelength of 193 nm from an ArF excimer laser light source is used as illumination light. By scanning the wafer one-dimensionally relative to the projection field of view of the reduction projection optical system, a scanning exposure operation for transferring the entire reticle circuit pattern into one shot area on the wafer and an inter-shot stepping operation are repeated. A step-and-scan type scanning exposure apparatus has been developed.

There is no doubt that the degree of integration of semiconductor devices will be further increased in the future and will shift from 1 Gbit to 4 Gbit. In that case, the device rule will be about 0.1 μm, that is, about 100 nm L / S. With the exposure apparatus using the above-mentioned ultraviolet pulse laser light having a wavelength of 193 nm as illumination light, there are many technical problems to cope with this. Device rule (practical minimum line width)
The resolution of an exposure apparatus that represents the exposure wavelength λ and the numerical aperture N. A. Is represented by the following equation (1).

(Resolution) = k · λ / N. A. (1) Here, k is a positive constant called a “key factor” of 1 or less, and varies depending on characteristics of a used resist.

As is apparent from the above equation (1), it is extremely effective to reduce the wavelength λ to increase the resolution. In the description, this light is referred to as “EUV (Extreme Ultr
EUV using “aviolet) light” as exposure light
Exposure equipment development has begun, and such EU
V-exposure apparatuses have attracted attention as promising candidates for next-generation exposure apparatuses having a minimum line width of 100 nm.

[0007]

SUMMARY OF THE INVENTION In an EUV exposure apparatus,
In general, a reflective reticle is used, and the reflective reticle is irradiated with illumination light obliquely, and the reflected light from the reticle surface is projected onto a wafer via a projection optical system including a reflective optical system, thereby forming a reticle. The pattern of the upper illumination area is transferred onto the wafer. In addition, in this EUV exposure apparatus, an arc-shaped illumination area is set on the reticle to transfer a pattern by using only a portion having good imaging performance of the projection optical system, and the reticle and the wafer are projected. A scanning exposure method of sequentially transferring the entire surface of a pattern on a reticle onto a wafer via a projection optical system by performing relative scanning with respect to an optical system is employed.

The reason for using a reflection type reticle is that there is no substance that efficiently transmits light without absorption at the wavelength of light (5 to 15 nm) used in an EUV exposure apparatus. However, a reflective film formed on the pattern surface of the reflective reticle is currently only developed with a reflectivity of around 70% at most. Therefore, the remaining 30% is absorbed and exchanged for heat, causing an increase in the temperature of the mirror (reflection optical element) constituting the reflection optical system. In the worst case, the temperature rise causes a large deformation of the mirror, which makes it impossible to maintain a sufficient imaging characteristic. For this reason, in the conventional EUV exposure apparatus, the heat of the mirror is released by performing forced cooling means such as liquid cooling or Peltier element cooling on the back surface of the mirror.

In this case, low expansion glass or metal is considered as a material of the mirror. Since the low expansion glass has a very small linear expansion coefficient with respect to a temperature change, the deformation amount does not deteriorate the imaging performance with a considerable temperature change.

However, since the low-expansion glass has a very low thermal conductivity, the method of simply cooling the rear surface of the mirror as described above requires a large amount of time before the heat generated on the mirror surface is transmitted to the rear surface. As a result, a temperature gradient is generated from the mirror surface to the back surface, and the most important mirror surface, that is, the reflecting surface cannot be sufficiently cooled,
As a result, the reflection surface is deformed, and the imaging characteristics of the projection optical system are deteriorated. As a result, the pattern image transferred onto the substrate (hereinafter, also referred to as “transfer image”) may be disadvantageously deteriorated. there were.

Deterioration of the transferred image can also be caused by heat fluctuation (irradiation fluctuation) due to absorption of illumination light of the mask on which the pattern is formed.

The present invention has been made under such circumstances, and an object of the present invention is to degrade a transferred image caused by irradiation fluctuation of a mask or a projection optical system due to irradiation of illumination light (hereinafter referred to as “irradiation fluctuation”). It is an object of the present invention to provide an exposure apparatus capable of effectively suppressing the exposure.

[0013]

In an exposure apparatus using a reflection optical system as a projection optical system, such as an EUV exposure apparatus, or an exposure apparatus using a catadioptric system, illumination light impinges only on a part of the reflection optical element. Therefore, it is considered that it is possible to arrange a cooling device for cooling the reflection surface in a region where the illumination light does not fall. The present invention focuses on this point and employs the following configuration. That is,

According to the first aspect of the present invention, illumination light (EL)
An exposure apparatus that irradiates a mask (R) with a mask and transfers a pattern formed on the mask onto a substrate (W) via a projection optical system (PO). To M4) are used.
At least one of the plurality of mirrors is formed of a material having a low thermal conductivity, and the non-irradiation of the illumination light on a reflection surface of the mirror made of the material having a low thermal conductivity is irradiated with the illumination light. Cooling device (H
P, 52).

According to this, the cooling device is provided in the non-irradiation area of the illumination light on the reflection surface of the mirror formed of a material having a low thermal conductivity among the plurality of mirrors constituting the projection optical system. Therefore, while taking advantage of the low thermal conductivity of the material that the deformation does not deteriorate the imaging characteristics for a considerable temperature change, the reflecting surface must be directly positioned so that the temperature change beyond the limit does not occur. By cooling, deterioration of the imaging characteristics of the projection optical system due to irradiation of the illumination light can be prevented, and as a result, deterioration of the transferred image due to irradiation fluctuation can be suppressed. In this case, other mirrors formed of a material having a high thermal conductivity may be cooled from the back side as in the conventional case.

In this case, as in the second aspect of the present invention, a cooling device may be arranged on the back side of the mirror on which the cooling device is arranged on the reflection surface.

According to a third aspect of the present invention, there is provided illumination light (EL).
An exposure apparatus that irradiates a mask (R) with a mask and transfers a pattern formed on the mask onto a substrate (W) via a projection optical system (PO). A reflection optical system including a plurality of mirrors (M1 to M4) including a first mirror (M1) and a second mirror (M2) to be irradiated is used, and a lens barrel (PP) holding the plurality of mirrors is cooled. A lens barrel cooling device (52); and a heat exchanger (HP) provided between at least one of the plurality of mirrors and the lens barrel.

According to this, the lens barrel holding a plurality of mirrors is cooled by the lens barrel cooling device. When the temperature of the plurality of mirrors rises due to the irradiation of the illumination light, heat exchange is performed between at least one of the plurality of mirrors and the lens barrel by the heat exchanger, and the mirrors are forcibly moved. Is cooled. The heat exchange by the heat exchanger is performed continuously during the irradiation of the mirror with the illumination light. Therefore, the deformation of the mirror connected to the heat exchanger can be prevented,
It is possible to prevent the imaging characteristics of the projection optical system from deteriorating, and as a result, it is possible to suppress the deterioration of the transferred image due to the irradiation variation. In this sense, it is of course possible to provide a heat exchanger between all mirrors held in the lens barrel and the lens barrel to prevent thermal deformation of all mirrors. Alternatively, the heat exchanger may be connected only to the first mirror to which the illumination light is applied first. Alternatively, a heat exchanger may be connected to the second mirror in addition to the first mirror. Since the thermal energy of the illumination light is highest at the position of the first mirror, at least the first
It is desirable to provide a heat exchanger between the mirror and the lens barrel to forcibly cool the first mirror.

According to a fourth aspect of the present invention, in the exposure apparatus according to the third aspect, a plurality of divided barrels (PP, PP ') each of which holds at least one mirror.
Wherein the lens barrel cooling device cools each of the split lens barrels independently, and the heat exchanger (HP) includes a plurality of split lens barrels and at least one mirror held by the split lens barrels. And at least one of them is provided between them.

According to this, since the lens barrel cooling device cools each of the divided lens barrels independently, it is possible to cool at a different temperature for each of the divided lens barrels. The heat exchanger provided between the held mirrors enables the mirrors to be forcibly cooled to different temperatures for each of the divided lens barrels.

In this sense, as in the invention according to claim 5, one of the plurality of split lens barrels is configured to control the first mirror (M1) to which the illumination light (EL) is first irradiated. A holding barrel (PP '), one of the heat exchangers being provided between the first mirror and the split barrel holding the first mirror, wherein the barrel cooling device is provided. Preferably, the divided lens barrel holding the first mirror is cooled at a lower temperature than the other divided lens barrels. By doing so, the first mirror, which has the largest amount of heat absorption and is likely to cause deterioration of the imaging characteristics, can be cooled more efficiently than the other mirrors. It becomes possible to suppress.

In each of the third to fifth aspects of the present invention, the heat exchanger may be any as long as it performs heat exchange between the lens barrel (or the split lens barrel) and the mirror. The heat exchanger may be a heat pipe (HP).

[0023] In the exposure apparatus according to the first or third aspect, as in the seventh aspect, the mask (R)
Is a reflection type mask, and may further include a second cooling device (36) disposed on a side of the mask opposite to the side on which the illumination light is incident. In such a case, the fluctuation of the irradiation of the mask can be suppressed, so that the deterioration of the transferred image due to the fluctuation of the irradiation can be suppressed more effectively.

According to an eighth aspect of the present invention, there is provided an illumination optical system for irradiating a mask (R) with illumination light (EL).
30, M, 42) for transferring a pattern formed on the mask onto a substrate (W), comprising a reflective optical element (M1 to M4), and emitted from the mask. Projection optical system (PO) for projecting illumination light onto the substrate
And a heat exchanger (HP) provided between the reflective optical element and a barrel (PP) holding the reflective optical element.

According to this configuration, since the heat exchanger provided between the reflection optical element constituting the projection optical system and the lens barrel holding the same is provided, the illumination light emitted from the mask is reflected by the reflection optical element. When the optical element is irradiated and the temperature of the reflective optical element rises, heat is exchanged between the reflective optical element and the lens barrel by the heat exchanger, and the reflective optical element is cooled. The heat exchange by the heat exchanger is performed until the temperatures of the reflective optical element and the lens barrel match. Therefore, by pre-cooling the lens barrel, it is possible to prevent the imaging characteristics of the projection optical system from deteriorating due to the irradiation of the illumination light to some extent. It becomes possible to suppress.

In this case, the heat exchanger may be connected to at least one of a part of the reflection surface of the reflection optical element and a back surface thereof.

[0027] In the invention according to claim 8 or 9, as in the invention according to claim 10, the projection optical system comprises only a plurality of reflection optical elements, and at least one of the plurality of reflection optical elements includes the reflection optical element. It may be connected to a heat exchanger.

In this case, the reflection optical element (M1) having the shortest optical distance to the mask among the plurality of reflection optical elements is connected to the heat exchanger (HP). It is desirable to be connected. In such a case, since the optical distance to the mask is the shortest, the heat absorption is the largest, and the reflective optical element that easily causes the deterioration of the imaging characteristics can be cooled. It is possible to suppress it.

According to the tenth or eleventh aspect of the present invention, as in the twelfth aspect, the projection optical system has a ring image field, is non-telecentric on the object plane side, and has an image plane. The side may be a telecentric optical system.

In each of the above-mentioned inventions, the mask may be a transmissive mask, but as in the invention of claim 13, the mask (R) is a reflective mask. , The illumination optical system (PRM, IM, 30,
M, 42) may irradiate the illumination light onto the pattern surface of the mask with its principal ray inclined.

In each of the first to thirteenth aspects of the present invention, as in the fourteenth aspect, the illumination light may be EUV light having a wavelength of 5 to 15 nm.
This is because illumination light having a short wavelength, such as EUV light, has a large irradiation energy, and it is highly necessary to cool a mirror or a reflection optical element.

In this case, as in the invention according to claim 15, an aperture member (4) for defining an irradiation area of the illumination light in an arc slit shape within a field of view of the projection optical system (PO).
4) may be further provided. In such a case, the irradiation area of the illumination light on the mask is defined in the shape of an arc slit by the aperture member, so that the illumination light emitted from the illumination optical system toward the mask is compared with the case without the aperture member. The degree of freedom of the cross-sectional shape is increased, and accordingly, the degree of freedom in designing the optical elements constituting the illumination optical system is improved.

In each of the eighth and ninth aspects of the present invention, as in the sixteenth aspect, the projection optical system may be a reduction system having the reflective optical element and the refractive optical element. Even in such a case, heat is exchanged between the reflective optical element and the lens barrel holding the same by the heat exchanger. For example, by cooling the lens barrel in advance, it is caused by illumination light irradiation. It is possible to prevent the imaging characteristics of the projection optical system from deteriorating to some extent, and as a result, it is possible to suppress the deterioration of the transferred image due to the irradiation variation.

In this case, the projection optical system may be an optical system having a circular image field, and both the object plane side and the image plane side are telecentric. In such a case, for example, by performing exposure to F ₂ laser beam having a wavelength of 157nm as exposure illumination light, about on the substrate (wafer) 100 Nml
The transfer of a fine pattern of about / S pattern can be achieved.

In each of the sixteenth and seventeenth aspects, as in the eighteenth aspect, the illumination light may be vacuum ultraviolet light having a wavelength of about 200 nm or less.

In this case, the illumination optical system may define an irradiation area of the illumination light in an arc shape or a hexagon shape in the field of view of the projection optical system. The illumination optical system may define an irradiation area of the illumination light in a rectangular slit shape within a field of view of the projection optical system.

In the exposure apparatus according to any one of the first to nineteenth aspects, as in the twentieth aspect, the mask (R) and the substrate (W) are respectively exposed to the illumination light. Stage system (RST, W
ST, 80, 34, 62),
The mask and the substrate are synchronously moved at a speed ratio corresponding to the magnification of the projection optical system (PO), and the substrate is scanned and exposed with the illumination light via the mask and the projection optical system. Is also good.

In this case, as in the invention according to claim 21, during the synchronous movement, the first position information of the mask in the optical axis direction of the projection optical system (PO) is detected.
It is preferable to further include a position detection system (RIFZ) and a second position detection system (14) for detecting position information of the substrate in the optical axis direction. In such a case, the positions of the mask and the substrate in the optical axis direction during the scanning exposure are detected by the first and second position detection systems, respectively, and the positions of the mask and the substrate in the optical axis direction are adjusted. It is possible to effectively suppress the occurrence of a magnification error or a position shift in a transferred image of a pattern on a substrate due to the axial displacement, and as a result, it is possible to improve the overlay accuracy.

[0039]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First Embodiment A first embodiment of the present invention will be described below with reference to FIGS.

FIG. 1 schematically shows the entire configuration of an exposure apparatus 10 according to the first embodiment. The exposure apparatus 10 is a projection exposure apparatus that performs an exposure operation by a step-and-scan method using light in a soft X-ray region (EUV light) having a wavelength of 5 to 15 nm as illumination light EL for exposure. In the present embodiment, as will be described later, a projection optical system PO that vertically projects a reflected light beam from a reticle R as a mask onto a wafer W is used. The projection direction of the illumination light EL onto W is referred to as the optical axis direction of the projection optical system PO.
The optical axis direction will be described as a Z-axis direction, a direction perpendicular to the optical axis direction in FIG. 1 as a Y-axis direction, and a direction perpendicular to the paper plane as an X-axis direction.

The exposure apparatus 10 projects a partial image of a circuit pattern drawn on a reflective reticle R as a mask onto a wafer W as a substrate via a projection optical system PO, and Is relatively scanned with respect to the projection optical system PO in a one-dimensional direction (here, the Y-axis direction), so that the entire circuit pattern of the reticle R is transferred to the wafer W.
The image is transferred to each of the plurality of upper shot areas by a step-and-scan method.

The exposure device 10 includes a light source device 12 that emits the EUV light EL horizontally along the Y direction.
A mirror M (reflecting the illumination optical system) that reflects the EUV light EL from A reticle stage RST for holding the reticle R, and a projection optical system P including a reflection optical system for projecting the EUV light EL reflected on the pattern surface of the reticle R perpendicularly to the surface to be exposed of the wafer W.
O, a wafer stage WST for holding the wafer W, focus sensors (14a, 14b), an alignment optical system ALG, and the like.

As shown in FIG. 2, the light source device 12 includes a light source 16 and a part of an illumination optical system (PRM, IM, 30).
It is composed of The light source 16 includes, for example, a high-power laser 20 such as a YAG laser or an excimer laser excited by a semiconductor laser, a condensing lens 22 for condensing a laser beam L from the high-power laser 20 at a predetermined converging point, And an EUV light generating substance 24 such as a copper tape disposed at the light spot.

Here, the mechanism of generation of EUV light will be briefly described.
Is irradiated on the EUV light generating substance 24 disposed at the converging point of the condensing lens 22, the EUV light generating substance 24 becomes high temperature by the energy of the laser light, is excited into a plasma state, and is brought into a low potential state. The EUV light EL is emitted during the transition.

The EUV light EL generated in this way diverges in all directions, and a parabolic mirror PRM is provided in the light source device 12 for the purpose of condensing the light. The EUV light EL is collected by the PRM and converted into a parallel light flux. An EUV light reflection layer for reflecting EUV light is formed on the inner surface of the parabolic mirror PRM, and a cooling device 26 is attached to the back surface. As the cooling device 26, a device using a cooling liquid is preferable from the viewpoint of cooling efficiency, but is not limited to this. Metal is suitable for the material of the parabolic mirror PRM in terms of heat conduction. It is known that, as a EUV light reflecting layer formed on the surface of a parabolic mirror PRM, a multilayer film in which two types of substances are alternately laminated is used to reflect only light of a specific wavelength. For example, molybdenum Mo
Dozens of layers of Si
It is known that EUV light is selectively reflected. Light of a wavelength not reflected is absorbed by the multilayer film or the like and converted into heat, so that the temperature of the parabolic mirror PRM increases. In order to cool the parabolic mirror PRM, the cooling device 26 is required. The EUV light EL converted into parallel light by the parabolic mirror PRM is a parallel light having a circular cross section perpendicular to the optical axis and a uniform intensity distribution.

The light source device 12 further includes an illumination mirror IM that reflects the EUV light EL converted into the parallel light and deflects it toward the folding mirror M in FIG. The rear side in the traveling direction of the EUV light EL (FIG. 2)
And a wavelength selection window 30 disposed on the right side of the drawing in FIG. As shown in FIG. 2, the illumination mirror IM has a curved surface on the side irradiated with the EUV light EL, and two kinds of materials are alternately laminated on the curved surface (for example, molybdenum Mo and silicon). Dozens of layers of Si coating)
A reflective layer made of a multilayer film is formed, and the EUV light reflected by the reflective layer is designed to be just a narrow slit on the reticle R.

An arc-shaped illumination area having a predetermined area to be described later (illumination area shaped like a part of a ring-shaped illumination area) is used to illuminate a pattern surface of a reticle R described later in the vertical direction in the plane of FIG. And the pattern surface of the reticle R is just the focal plane. In this case, since the emission source of the EUV light EL has a finite size, even if the pattern surface of the reticle R is a focal plane, the EUV light EL is 1 mm to less on the focal plane.
It has a width of about 10 mm. Therefore, it is not too thin to illuminate the arc-shaped illumination area. On the back side of the reflection surface of the illumination mirror IM, a cooling device 28 similar to the cooling device 26 described above is provided.

Here, the wavelength selection window 30 is provided for the purpose of cutting visible light. This is because EUV reflective films composed of multilayer films have a very sharp wavelength selectivity for wavelengths near EUV light and selectively reflect only specific wavelengths used for exposure. Will be similarly reflected. This is called reticle R or projection optical system PO
The mirror (which will be described later) forming the reticle R and the projection optical system PO due to unnecessary energy, or unnecessary light is transferred onto the wafer W in the worst case. Since the image may be deteriorated, an attempt is made to prevent such a situation from occurring.

FIG. 3 shows the light source device 12 shown in FIG. 2 as viewed from one side in the Y direction (left side in FIG. 2). In FIG. 3, the folding mirror M of FIG. The reflection surface of the illumination mirror IM is not shown in FIG. 3, but has a rectangular shape when viewed from the back side of the paper of FIG. That is, the illumination mirror IM has a concave curved surface in FIG. 2 and a rectangular shape in FIG.
Has the same shape as a part of the inner peripheral surface of the cylinder. In this case, the EUV light EL is converged in the plane of FIG. 2 but remains parallel in the plane of FIG. 3, so that the length in the left-right direction in FIG. It is the length in the longitudinal direction. It should be noted that even though the light source is parallel, the spatial coherency is not necessarily zero because the size of the light source is finite as described above.

Returning to FIG. 1, the reticle stage RST
Although not shown in FIG. 1, is actually arranged on a reticle stage base 32 arranged along the XY plane as shown in FIG. The reticle stage base 32 is supported by floating. The reticle stage RST is driven by the magnetic levitation type two-dimensional linear actuator 34 at a predetermined stroke in the Y direction, and is also driven by a small amount in the X direction and the θ direction (rotation direction around the Z axis). ing. The reticle stage RST is configured to be driven by a minute amount in the Z direction and the tilt direction with respect to the XY plane by the magnetic levitation type two-dimensional linear actuator 34.

A permanent magnet (not shown) is provided at the bottom of the peripheral portion of the reticle stage RST. The permanent magnet and the coil 34a stretched on the reticle stage base 32 in the XY two-dimensional directions provide the magnetic field. A floating type two-dimensional linear actuator 34 is configured,
The position and orientation of the reticle stage RST in the six-dimensional direction are controlled by controlling a current flowing through the coil 34a by a main controller 80 described later.

The reticle stage RST includes a reticle holder RH for holding the reticle R facing the reticle stage base 32 and a stage body 35 for holding a peripheral portion of the reticle holder RH, as shown in FIG.
And a temperature control unit 36 provided inside the stage main body 35 on the back side (upper side) of the reticle holder RH to control the temperature of the reticle holder RH. As the reticle holder RH, a reticle holder of an electrostatic chuck type is used. This is because the EUV light EL is used as illumination light for exposure, and therefore, the exposure apparatus 10 of the present embodiment is actually housed in a vacuum chamber (not shown). Cannot be used. Reticle holder R
Material of H is conventional DUV such as low expansion glass and ceramic
Objects used in the exposure apparatus may be used.

A plurality of temperature sensors 38 are arranged at predetermined intervals on the reticle suction surface of the reticle holder RH, and the temperature of the reticle R is accurately measured by these temperature sensors 38. The controller 36 performs temperature control so as to maintain the temperature of the reticle R at a predetermined target temperature. As a cooling device constituting the temperature control unit 36, a liquid cooling type in which a cooling liquid is drawn in from outside through a flexible tube, a method using an electronic element such as a Peltier element, and a heat pipe such as a heat pipe. A method using an exchanger can be adopted.

The side surface of the reticle stage RST on one side in the Y direction is mirror-finished to form a reflection surface 40a for light in the visible region. Although not shown in FIG. 4, as shown in FIG. 6, reticle stage RS
The side surface on one side in the X direction of T is also mirror-finished to form a reflection surface 40b for light in the visible region. And
In this exposure apparatus 10, the position of the reticle stage RST in the XY plane is managed by an interferometer system that irradiates the reflection surfaces 40a and 40b with a measurement beam, similarly to the exposure apparatus using a conventional DUV light source. This interferometer system will be described later in detail.

On the surface (pattern surface) of reticle R, E
A reflection film that reflects UV light is formed. This reflection film is, for example, a multilayer film in which two kinds of substances are alternately laminated. Here, a reflective film having a reflectance of about 70% for EUV light having a wavelength of 13 nm is formed using a multilayer film of molybdenum Mo and silicon Si. A material that absorbs EUV light is applied on one surface of the reflective film, and patterning is performed. When a reflective object such as a multilayer film is patterned, it is impossible to repair the failure when it fails. On the other hand, when the patterning is performed by providing an absorbing layer, the pattern can be repaired because the process can be redone. Since most existing substances do not reflect EUV light, they can be used for absorbing layers. In the present embodiment, as described later, laser interferometers (RIFZ1 to RIFZ3) are used to measure the position of the reticle R in the Z direction. Therefore, measurement beams (light in the visible region) from these laser interferometers are used. The absorption layer is formed of a substance that can provide the same reflectance as that of the reflection layer. In addition, the criteria for selecting the material for forming the absorbing layer include ease of patterning, adhesion to the reflective layer, and small changes over time due to oxidation and the like.

FIG. 5 shows an example of the reticle R. The rectangular area at the center in the figure is the pattern area PA.
It is. The hatched arc-shaped area is the arc-shaped illumination area IA irradiated with the EUV light EL as the illumination light for exposure. Here, the reason why the exposure is performed using the arc-shaped illumination area is that only the area where the various aberrations of the projection optical system PO described later are the smallest can be used. At both ends in the X direction of the pattern area PA of the reticle R, reticle alignment marks RM1 to RM6 as alignment marks are formed at predetermined intervals along the Y direction. Reticle alignment marks RM1 and RM4, RM2 and R
M5, RM3, and RM6 are respectively arranged substantially along the X direction.

As is clear from FIG. 5, when the arc-shaped illumination area IA is used, it is not practical to perform the batch exposure (still exposure), and in this embodiment, the scanning exposure is performed as described later. Will be

Since the reflective layer is formed on the surface of the reticle R as described above, the material of the reticle R itself is not particularly limited. As a material of the reticle R, for example, low expansion glass, quartz glass (including, for example, Zerodur (trade name) of Schott Co., and ULE (trade name) of Corning Co., Ltd.), ceramics, and silicon wafer can be considered. As a criterion for selecting this material, for example, the same material as the material of the reticle holder RH may be used as the material of the reticle R. In such a case, thermal expansion occurs in the reticle R and the reticle holder RH due to a temperature rise due to the irradiation of the illumination light EL or the like. There is an advantage that the desired force (thermal stress) does not work. However, the same effect can be obtained by using different materials having the same linear expansion coefficient as the material of the reticle R and the reticle holder RH. For example, a silicon wafer is used for the reticle R, and SiC (silicon carbide) is used for the reticle holder RH.
It is conceivable to use. When a silicon wafer is used as the material of the reticle R, there is also an advantage that a process device such as a pattern drawing device, a resist coating device, and an etching device can be used as it is. In this embodiment,
For this reason, a silicon wafer is used as a material of the reticle R, and the reticle holder is formed of SiC.

Returning to FIG. 1, below the reticle R, a movable blind 42 and a slit plate 44 as a field stop are arranged close to the reticle R. More specifically, these movable blinds 42 and slit plates 44
Actually, as shown in FIG. 4, it is arranged inside the reticle stage base 32.

The slit plate 44 has an arc-shaped illumination area IA.
The slit plate 44 may be fixed to the projection optical system PO. However, in the present embodiment, the slit plate 44 is configured to be drivable by a driving mechanism 46 as a switching mechanism including a motor and the like. Have been. FIG. 7 is a plan view of the slit plate 44 and the driving mechanism 46 thereof. The slit plate 44 includes a first slit 44a as a first opening that defines an arc-shaped illumination area (first illumination area) IA on the reticle R on which the EUV light EL as illumination light for exposure is irradiated. Pattern area P of reticle R
A. Alignment marks RM1 and RM formed on both sides of A
4 (or RM2 and RM5, RM3 and RM6) have a second slit 44b as a second opening that defines a second illumination area where the exposure illumination light EL is irradiated. The drive mechanism 46 includes a motor 46A, a feed screw 46C connected to an output shaft of the motor via a joint 46B, and a control unit 46D for the motor 46A. A feed screw 46C is screwed into a nut portion (not shown) projecting from the slit plate 44 on the back side of the paper surface in FIG. For this reason, the feed screw 46C is rotationally driven by the rotation of the motor 46A, whereby the slit plate 44 is driven in the axial direction (Y direction) of the feed screw 46C.
The control unit 46D of the drive mechanism 46 includes a main control device 8 described later.
0 (see FIG. 11), the slit plate 44 is exposed to the illumination light EL for exposure by the first slit 44 during exposure.
When the reticle R is positioned (aligned), the slit plate 44 is irradiated with the illumination light EL for exposure to the second slit 44b.
Switch to the position. The slit plate 44 may be driven using, for example, a linear motor instead of the feed screw mechanism.

Returning to FIG. 4, the movable blind 42
Is to prevent the redundant circuit pattern drawn in the same reticle R from being included in the illumination area IA when it is not desired to transfer the pattern to the wafer W. In the present embodiment, In response to an instruction from the main controller 80 (see FIG. 11), the controller 4 constituting the drive mechanism 46
6D controls the movement of the reticle stage RST in the Y direction in synchronization with the movement in the Y direction. In this case, the starting of the movable blind 42 may start scanning in the same manner as the reticle R after the reticle R starts scanning, or may start moving in accordance with the arrival of a target pattern to be hidden.

Referring back to FIG. 1, as the projection optical system PO, as described above, a reflection optical system including only a mirror as a reflection optical element is used. Have been. Therefore, E including the pattern information reflected by the reticle R and drawn on the reticle R
The UV light EL is irradiated onto the wafer W after being reduced to a quarter by the projection optical system PO.

Here, the projection optical system PO will be described in more detail with reference to FIG. As shown in FIG.
The projection optical system PO includes the EUV light E reflected by the reticle R.
A total of four mirrors (reflection optical elements) of a first mirror M1, a second mirror M2, a third mirror M3, and a fourth mirror M4, which sequentially reflect L, and a lens barrel PP holding these mirrors M1 to M4. It is composed of The reflecting surfaces of the first mirror M1 and the fourth mirror M4 have an aspherical shape,
The reflection surface of the mirror M2 is flat, and the reflection surface of the third mirror M3 is spherical. Each reflecting surface achieves a processing accuracy of about 1/50 to 1/60 or less of the exposure wavelength with respect to the design value, and has an error of 0.2 to 0.3 nm or less in RMS value (standard deviation). In this case, the material of the first mirror M1 and the second mirror M2 is low expansion glass having a small coefficient of thermal expansion, and the material of the third mirror M3 and the fourth mirror M4 is metal. On the surface of each of the mirrors M1 to M4, a reflective layer for EUV light is formed by a multilayer film in which two kinds of substances similar to the reticle R are alternately stacked. As the low expansion glass used for the mirror constituting the projection optical system PO, there is, for example, Zerodur (trade name) manufactured by Schott. Zerodur contains 70 to 80 weight percent of a crystallized phase having a high quartz structure, and thus has a linear expansion coefficient of 0 ± 0.05 × 10 ⁻⁶ . The thermal conductivity of Zerodur is 1.6 W / (m · K). Instead of a low expansion glass such as Zerodur, for example, alumina (Al ₂ O ₃ ) or cordierite (2MgO ₂ .2)
Al ₂ O ₃ .6SiO ₂ ) low expansion ceramics may be used.

In this case, as shown in FIG. 8, a hole is formed in the fourth mirror M4 so that the light reflected by the first mirror M1 can reach the second mirror M2. Similarly, the first mirror M1 is provided with a hole so that the light reflected by the fourth mirror M4 can reach the wafer W. Of course,
Instead of making a hole, the outer shape of the mirror may have a cutout through which a light beam can pass.

Since the environment in which the projection optical system PO is placed is also a vacuum, there is no escape for heat due to the irradiation of the illumination light EL. Therefore, in the present embodiment, the mirrors M1 to M4 and the lens barrel PP holding the mirrors M1 to M4 are connected by a heat pipe HP as a heat exchanger, and the lens barrel PP
The cooling device which cools is provided. That is, the lens barrel PP
Has a double structure of an inner inner member 50 and a cooling jacket 52 as a cooling device mounted on the outer peripheral portion thereof. A helical pipe 58 for flowing is provided. Here, cooling water is used as the cooling liquid. The cooling water flowing out of the cooling jacket 52 through the outflow tube 56 exchanges heat with the refrigerant in a refrigeration apparatus (not shown), and is cooled to a predetermined temperature. The cooling water is circulated in this manner.

FIG. 9 shows an example of the second mirror M shown in FIG.
Two support structures are shown schematically. As shown in FIG. 9A, the mirror M2 has a peripheral portion on the back surface (the upper surface in FIG. 9A) side protruding inward at three places of a cylindrical mirror frame 90, similarly to the usual case. The lower surface of a three-point seat (not shown) is supported, and three peripheral portions on the surface (reflection surface) side thereof are fixed by pressing plates (not shown). Further, a packing (not shown) is interposed between the mirror frame 90 and a side surface of the mirror M2 so that the mirror M2 does not shift or come off. In the present embodiment, a plurality of holes are formed at predetermined intervals in the mirror frame 90, and the heat pipe HP is inserted into each of these holes. Each heat pipe HP has its heat radiating part (condensing part)
Is connected to the lens barrel PP, and the heat input portion (evaporation portion) thereof is in contact with the back surface or the front surface of the mirror M2. However, actually, the heat pipe HP provided on the front side of the mirror M2 is used.
9B is in contact with the surface of the mirror M2 via a buffer member 92 such as silicon, as shown in FIG. 9B. This prevents distortion or the like from occurring on the reflection surface of the mirror M2.

The remaining mirrors M1, M3, M4 are also supported by the same support structure as described above, and the heat input sections of each heat pipe HP are similarly brought into contact.

As described above, the mirrors M1 to M4 are supported by the respective support structures, and the heat pipe HP
Is connected to the inner member 50 of the lens barrel PP, the projection optical system PO of the present embodiment irradiates the exposure light (EUV light) EL with the mirrors M1, M2, and M.
3. Even if heat energy is given to M4, heat pipe H
Heat exchange is performed between the lens barrel PP whose temperature has been adjusted to a constant temperature by P, and the mirrors M1, M2, M3, and M4 are cooled to the constant temperature. In this case, in the present embodiment, as shown in FIG. 8, the mirrors M1, M2, M4, etc. are not only on the back side but also on the front side (reflection side) where the illumination light for exposure is not irradiated. Also, since the heat pipe HP is attached, the cooling of each mirror is performed more effectively than when only the back side is cooled. Needless to say, the heat pipe HP on the back surface side of the third mirror M3 and the front surface side of the first mirror M1 reaches the inner peripheral surface of the lens barrel PP in the depth direction of the drawing. The appearance of the lens barrel PP is shown in FIG.
As shown in (A), it has a quadrangular prism shape.

Referring back to FIG. 1, wafer stage WST
Are arranged on a wafer stage base 60 arranged along the XY plane, and are levitated and supported on the wafer stage base 60 by a magnetic levitation type two-dimensional linear actuator 62. The wafer stage WST is driven at a predetermined stroke in the X direction and the Y direction by the magnetic levitation type two-dimensional linear actuator 62,
It is also driven in a minute amount in the θ direction (the rotation direction around the Z axis). Also, this wafer stage WST
Z by the magnetic levitation type two-dimensional linear actuator 62
It is configured such that it can be driven by a very small amount in the direction and the tilt direction with respect to the XY plane.

A permanent magnet (not shown) is provided on the bottom surface of wafer stage WST. The magnet is formed by this permanent magnet and a coil (not shown) stretched on wafer stage base 60 in the XY two-dimensional directions. A floating type two-dimensional linear actuator 62 is formed, and the position and orientation of the wafer stage WST in the six-dimensional direction are controlled by controlling a current flowing through the coil by a main controller 80 described later. .

On the upper surface of wafer stage WST, a wafer holder (not shown) of the electrostatic chuck type is mounted, and wafer W is held by suction by the wafer holder. Further, the side surface of wafer stage WST on the other side in the Y direction in FIG. 1 is mirror-finished, and a reflection surface 74a for light in the visible region is formed. Although not shown in FIG. 1, as shown in FIG. 6, the side surface on one side in the X direction of the wafer stage WST is also mirror-finished,
A reflection surface 74b for light in the visible region is formed.
In the exposure apparatus 10, the reflection surfaces 74a, 7a
The position of the projection optical system PO with respect to the projection optical system PO is accurately measured by an interferometer system which irradiates the measurement beam 4b. This interferometer system will be described later.

At one end of the upper surface of wafer stage WST,
An aerial image measuring instrument FM for measuring the relative positional relationship between the position where the pattern drawn on the reticle R is projected on the surface of the wafer W and the alignment optical system (alignment microscope) ALG (so-called baseline measurement), etc. Is provided. This aerial image measuring instrument FM corresponds to a reference mark plate of a conventional DUV exposure apparatus.

FIGS. 10A and 10B show a plan view and a longitudinal sectional view of the aerial image measuring instrument FM, respectively.
As shown in these figures, a slit SLT is formed on the upper surface of the aerial image measuring instrument FM. The slit SLT is patterned on the EUV light reflecting layer 64 formed on the surface of the fluorescent substance 63 having a predetermined thickness fixed on the upper surface of the wafer stage WST. Note that an EUV light absorption layer may be provided instead of the reflection layer 64, and an opening may be formed in this absorption layer.

An opening 66 is formed in the upper surface plate of the wafer stage WST below the slit SLT. Inside the wafer stage WST opposed to the opening 66, a photoelectric conversion element PM such as a photomultiplier is provided. Are located. Accordingly, when the aerial image measuring instrument FM is irradiated with the EUV light EL from above via the projection optical system PO, the EUV light transmitted through the slit SLT reaches the fluorescent substance 63, and the fluorescent substance 63 It emits light with a longer wavelength than. This light is received by the photoelectric conversion element PM and converted into an electric signal corresponding to the intensity of the light. The output signal of the photoelectric conversion element PM is also supplied to the main controller 80.

Next, referring to FIG. 6, reticle stage R
The configuration of the interferometer system 70 (see FIG. 11) for measuring the positions of the ST and the wafer stage WST will be described in detail. In FIG. 6, the corresponding laser interferometer is typically shown using the length measurement axis of each laser interferometer.

The interferometer system 70 includes four laser interferometers RIFX1, RIFX2, RIFY1, and RIFY2 for measuring the position of the reticle stage RST in the XY plane.
And four laser interferometers WIFX1, WIFX2, WIY for measuring the position of the wafer stage WST in the XY plane
1 and WIFY2.

The interferometer RIFY1 has a reticle stage R
The measurement beam RIFY1M is projected onto the reflection surface 40a of the ST, and the reference beam R is applied to a fixed mirror (reference mirror) 72a (see FIG. 1) attached to the barrel PP of the projection optical system PO.
By projecting IFY1R and receiving each reflected light, the relative position of the reticle stage RST in the Y direction with respect to the fixed mirror 72a at the projection position of the measurement beam RIFY1M is measured.

Similarly, the interferometer RIFY2 applies the measurement beam RIFY2M to the reflection surface 40a of the reticle stage RST.
Is projected, a reference beam RIFY2R is projected onto a fixed mirror (reference mirror) 72a (see FIG. 1) attached to the barrel PP of the projection optical system PO, and the respective reflected light is received, thereby measuring the measurement beam. The relative position of the reticle stage RST in the Y direction with respect to the fixed mirror 72a at the projection position of RIFY2M is measured.

The above two interferometers RIFY1, RIFY2
The center of the irradiation position of the measurement beams RIFY1M and RIFY2M is aligned with the center of the illumination area IA (the center of the reticle R in the X direction). Therefore, the average of the measured values of these two interferometers is the Y direction position of reticle stage RST, and the difference between the two measured values divided by the interferometer axis interval is the rotation angle of reticle stage RST (here α1). )give. These interferometers RIFY1, RIFY
The measured value of 2 is supplied to the main controller 80, and the main controller 80 calculates the average value and the rotation angle α1.

The interferometer RIFX1 projects the measurement beam RIFX1M onto the reflection surface 40b of the reticle stage RST, and simultaneously applies the reference beam RIFX to a fixed mirror (reference mirror) 72b attached to the barrel PP of the projection optical system PO.
By projecting 1R and receiving each reflected light, the relative position of the reticle stage RST in the X direction with respect to the fixed mirror 72b at the projection position of the measurement beam RIFX1M is measured.

Similarly, the interferometer RIFX2 uses the measurement beam RIFX2M on the reflection surface 40b of the reticle stage RST.
And a reference beam RIF is applied to a fixed mirror (reference mirror) 72b attached to the barrel PP of the projection optical system PO.
By projecting X2R and receiving each reflected light, the relative position of the reticle stage RST in the X direction with respect to the fixed mirror 72b at the projection position of the measurement beam RIFX2M is measured.

The above two interferometers RIFX1 and RIFX2
The center of the irradiation position of the measurement beams RIFX1M and RIFX2M is aligned with the center of the illumination area IA (see point P2 in FIG. 5). Accordingly, the average of the measured values of these two interferometers is the X-direction position of the reticle stage RST, and the difference between the two measured values divided by the interferometer axis interval is the rotation angle of the reticle stage RST (here α2). )give. The measurement values of these interferometers RIFX1 and RIFX2 are supplied to the main control device 80, and the main control device 8
At 0, the average value and the rotation angle α2 are calculated. In this case, main controller 80 calculates one of rotation angles α1 and α2 or an average value (α1 + α2) / 2 as the rotation angle of reticle stage RST in the θ direction.

The interferometer WIFY1 is connected to the wafer stage WS
By projecting the measurement beam WIFY1M on the reflection surface 74a of T and projecting the reference beam WIFY1R on a fixed mirror (reference mirror) 76a attached to the barrel PP of the projection optical system PO, and receiving each reflected light. The relative position in the Y direction of wafer stage WST with respect to fixed mirror 76a at the projection position of measurement beam WIFY1M is measured.

Similarly, interferometer WIFY2 projects measurement beam WIFY2M on reflection surface 74a of wafer stage WST, and also transmits reference beam WIFY to fixed mirror (reference mirror) 76a attached to barrel PP of projection optical system PO.
By projecting 2R and receiving each reflected light, the relative position in the Y direction of wafer stage WST with respect to fixed mirror 76a at the projection position of measurement beam WIFY2M is measured.

The above two interferometers WIFY1, WIFY2
The center of the irradiation position of the measurement beams WIFY1M and WIFY2M corresponds to the center of the arc-shaped exposure area SA (see FIG. 11) on the wafer corresponding to the illumination area IA. Therefore, the average value of the measured values of these two interferometers is the Y-direction position of wafer stage WST, and the difference between the two measured values divided by the interferometer axis interval is the rotation angle of wafer stage WST (here, β1). )give. The measured values of these interferometers WIFY1 and WIFY2 are supplied to the main controller 80, and the main controller 80 calculates the average value and the rotation angle β1.

The interferometer WIFX1 projects the measurement beam WIFX1M on the reflection surface 74b of the wafer stage WST, and also applies the reference beam WIFX1 to the fixed mirror (reference mirror) 76b attached to the barrel PP of the projection optical system PO.
By projecting R and receiving each reflected light,
Fixed mirror 76 at the projection position of the measurement beam WIFX1M
The relative position of wafer stage WST in the X direction with respect to b is measured.

Similarly, interferometer WIFX2 projects measurement beam WIFX2M on reflection surface 74b of wafer stage WST, and also applies reference beam WIFX to fixed mirror (reference mirror) 76b attached to barrel PP of projection optical system PO.
By projecting 2R and receiving each reflected light, the relative position of wafer stage WST in the X direction with respect to fixed mirror 76b at the projection position of measurement beam WIFX2M is measured.

The above two interferometers WIFX1 and WIFX2
The center of the irradiation position of the measurement beams WIFX1M and WIFX2M corresponds to the center of the exposure area SA corresponding to the illumination area IA. Therefore, the average value of the measured values of these two interferometers is the X direction position of wafer stage WST, and the difference between the two measured values divided by the interferometer axis interval is the rotation angle of wafer stage WST (here, β2). )give. The measurement values of these interferometers WIFX1 and WIFX2 are supplied to the main controller 80, and the main controller 80
Then, the average value and the rotation angle β2 are calculated. In this case, main controller 80 calculates one of rotation angles β1 and β2 or an average value (β1 + β2) / 2 as the rotation angle of wafer stage WST in the θ direction.

Returning to FIG. 1, a measuring apparatus for measuring the position of the reticle R in the Z direction (first axis direction) is provided on the lens barrel PP of the projection optical system PO, which is the reference for all the measurements of the eight interferometers. As a reticle surface measurement laser interferometer RIFZ. This laser interferometer RIFZ is actually
As shown in FIG. 6, laser interferometers RIFZ1, RI
Three of FZ2 and RIFZ3 are arranged at a predetermined interval and fixed to the lens barrel PP. In FIG. 1 (and FIG. 4), these are typically shown as a laser interferometer RIFZ.

These laser interferometers RIFZ1 to RIFZ1
The measurement beam from Z3 is used for exposure to three different points in the illumination area of the illumination light EL projected on the pattern surface of the reticle R at a predetermined incident angle θ via the turning mirror M, that is, the arc-shaped illumination area IA. The reticle R passes through the optical path in the Z direction at the center of the incident light path and the output light path (reflected light path) of the illumination light EL.
(See FIGS. 1 and 4). Therefore, the laser interferometers RIFZ1, RI
The FZ2 and RIFZ3 are obliquely incident on the pattern surface of the reticle R at a predetermined incident angle θ, do not affect the illumination light EL reflected at the same exit angle as the incident angle, and are not affected by the exposure illumination light EL. It is possible to measure the position of the reticle R in the Z direction with high accuracy (for example, an accuracy of several nm to 1 nm or less) without being affected by the interferometer measurement beam.

Here, as the laser interferometers RIFZ1 to RIFZ3, those having a built-in reference mirror having a built-in reference mirror (not shown) in the main body are used. Z of beam irradiation position
The directional position is measured. In this case, the laser interferometer RI is located at the position of the point P1 in the illumination area IA shown in FIG.
The measurement beam from FZ1 is projected, the measurement beam from laser interferometer RIFZ2 is projected at the position of point P2, and the measurement beam from laser interferometer RIFZ3 is projected at the position of point P3. Point P2 is the illumination area I
The center of A, that is, the point on the central axis in the X direction of the pattern area PA and the center point in the Y direction of the illumination area, the points P1, P
3 is located symmetrically with respect to the central axis.

The three laser interferometers RIFZ1 to RIFZ-R
The measured value of IFZ3 is input to main controller 80 (see FIG. 11), and main controller 80 uses the magnetic levitation type two-dimensional linear actuator based on these three measured values as described later. The reticle stage RST, that is, the Z position and the tilt of the reticle R are corrected via.

On the other hand, the wafer W based on the lens barrel PP
Is measured by an obliquely incident light type focus sensor 14 fixed to the projection optical system PO. As shown in FIG. 1, the focus sensor 14 is fixed to a column (not shown) that holds the lens barrel PP, and is similar to the light transmitting system 14a that irradiates the detection beam FB obliquely to the wafer W surface. And a light receiving system 14b fixed to the illustrated column and receiving the detection beam FB reflected by the surface of the wafer W. As this focus sensor, for example, a multipoint focal position detection system disclosed in Japanese Patent Application Laid-Open No. 6-283403 or the like is used. It is important that the focus sensors 14 (14a, 14b) are fixed integrally with the lens barrel PP.

As is clear from the above description, in this embodiment, the position of the reticle R in the XYZ three-dimensional directions is measured with reference to the lens barrel PP of the projection optical system PO.
Since the position in the XYZ three-dimensional direction of the wafer W is measured with reference to the barrel PP of the projection optical system PO, the projection optical system PO
Reticle stage RST and wafer stage WST
The persons need not be supported by the same support member, and each may be supported by a separate support member.
That is, there is no problem if there is no mechanical contact between the projection optical system PO, the reticle stage RST, and the wafer stage WST. Further, the interferometer system 7 described above is used.
Also, since the main body of each interferometer composing 0 performs measurement with reference to each fixed mirror attached to the barrel PP, the mechanical contact with the projection optical system PO, the reticle stage RST, and the wafer stage WST No need.

Further, in this embodiment, the projection optical system PO
As shown in FIG. 1, the alignment optical system ALG is fixed to the side surface of. The alignment optical system ALG irradiates the alignment mark (or the aerial image measuring instrument FM) on the wafer W with broadband light,
An image-forming alignment sensor that receives the reflected light and detects the mark by an image processing method, and an LIA (Laser Interferom) that irradiates a laser beam to the grating mark and detects diffracted light.
etric Alignment) type alignment sensor and AFM
Various types such as a scanning probe microscope such as (atomic force microscope) can be used.

FIG. 11 shows the various parts described so far.
The configuration of a control system related to position and orientation control of wafer W (wafer stage WST) and reticle R (reticle stage WST) is schematically shown in a block diagram.
The main control device 80 (comprising a microcomputer or minicomputer) and the magnetic levitation type two-dimensional linear actuators 34 and 62 in the control system shown in FIG. 11 constitute a stage control system.

Next, the first book constructed as described above is used.
The operation of the exposure process by the exposure apparatus 10 according to the embodiment will be described.

First, the reticle R is transported by a reticle transport system (not shown), and is suction-held by the reticle holder RH of the reticle stage RST at the loading position. Next, based on a command from main controller 80, slit plate 44 is switched by drive mechanism 46 to a position (second position) where illumination light EL can irradiate second slit 44b. Next, main controller 80 controls the positions of wafer stage WST and reticle stage RST via magnetic levitation type two-dimensional linear actuators 62 and 34,
The reticle alignment marks RM1, RM4, RM2, RM5, RM3, and RM6 drawn on the reticle R are sequentially irradiated with two pieces of exposure illumination light EL, and the reticle alignment marks RM1, RM4, RM2, and RM.
5. The projection position of the reticle pattern image on the wafer W surface is determined by detecting the projected images of the RM3 and RM6 on the wafer W surface with the aerial image measuring device FM. That is, reticle alignment is performed.

Next, main controller 80 moves wafer stage WST via magnetic levitation type two-dimensional linear actuator 62 such that slit SLT of aerial image measuring instrument FM is located immediately below alignment optical system ALG. Based on the detection signal of the alignment optical system ALG and the measurement value of the interferometer system 70 at that time, the image forming position of the pattern image of the reticle R on the wafer W surface and the relative position of the alignment optical system ALG; That is, a baseline amount is obtained.

When the baseline measurement is completed, main controller 80 sets a predetermined sample alignment target wafer alignment mark among wafer alignment marks attached to each shot area of wafer W on wafer stage WST. Position detection is performed using alignment optical system ALG while sequentially moving wafer stage WST. In this manner, when the position detection of the wafer alignment mark of the sample shot is completed, the positions of all the shot areas on the wafer W are obtained by using the data and by using the statistical method using the least squares method. In this way, when the alignment measurement is completed, the main controller 80 sets the slit plate 44 via the driving mechanism 46 to the position (first position) at which the first slit 44a is irradiated with the illumination light EL.
Switch to position).

The main controller 80 performs the step-and-scan exposure using the EUV light as the illumination light EL for exposure as follows. That is, according to the position information of each shot area above the wafer W obtained above,
While monitoring the position information from the interferometer system 70, the wafer stage WST is positioned at the scan start position of the first shot via the magnetically levitated two-dimensional linear actuator 62, and is also detected via the magnetically levitated two-dimensional linear actuator 34. Then, reticle stage RST is positioned at the scanning start position, and scanning exposure of the first shot is performed. At the time of this scanning exposure, the main controller 80 controls the reticle stage RST and the wafer stage WST via the magnetic levitation type two-dimensional linear actuators 34 and 62 so that the speed ratio between the reticle stage RST and the wafer stage WST exactly matches the projection magnification of the projection optical system PO. The exposure (transfer of the reticle pattern) is performed in a state where the speed of the stage is controlled and the speed ratio of the two stages is synchronized at a constant speed. When the scanning exposure of the first shot is completed in this way, a stepping operation between shots for moving wafer stage WST to the scanning start position of the second shot is performed.
Then, the scanning exposure of the second shot is performed in the same manner as described above. In this case, in order to improve the throughput by omitting the operation of returning the reticle stage RST, the directions of the scanning exposure of the first shot and the second shot are opposite, that is, the exposure of the first shot is one direction on the Y axis. When the exposure is performed from the side to the other side, the exposure of the second shot is performed from the other side to the one side. That is, alternate scanning is performed. In this manner, the stepping operation between shots and the scanning exposure operation for shots are repeated, and the pattern of the reticle R is transferred to all shot regions on the wafer W by the step-and-scan method. FIG. 12 shows how the reticle pattern is transferred to the plurality of shot areas S on the wafer W in this manner. In the case of FIG. 12, the number of shots contained in one row is appropriately set to an even number so that a complete shot can be efficiently obtained from one wafer.
It is odd.

Here, during the above-mentioned scanning exposure and alignment, the distance between the surface of the wafer W and the projection optical system PO and the XY plane are determined by focus sensors (14a, 14b) integrally attached to the projection optical system PO. The tilt is measured, and the main controller 80 and the projection optical system P
Wafer stage WST is controlled such that the distance from O and the parallelism are always constant.

In main controller 80, reticle surface measuring laser interferometers RIFZ1, RIFZ2, RIFZ3 are provided.
The distance between the projection optical system PO and the pattern surface of the reticle R during exposure (during transfer of the reticle pattern) is always kept constant based on the predetermined adjustment position information measured by at least one of the above. Controlling the magnetic levitation type two-dimensional linear actuator 34 to project the projection optical system PO of the reticle R.
The reticle stage RST and the substrate stage WST are synchronously moved along the Y-axis direction while adjusting the position in the optical axis direction (Z-direction). In this case, main controller 80 performs reticle surface measurement laser interferometer RIFZ1 in each of reticle stage RST movement directions, for example, the first shot and the second shot, during synchronous movement of reticle stage RST and wafer stage WST. The Z of the reticle stage RST is determined using the adjustment position information corresponding to the moving direction of the first adjustment position information and the second adjustment position information measured by at least one of RIFZ2 and RIFZ3.
The direction position is adjusted.

Therefore, according to the present embodiment, the entire surface of the reticle R pattern is sequentially transferred onto the wafer W by scanning exposure, and at this time, the position of the reticle R in the optical axis direction of the projection optical system is adjusted based on the adjustment position information. Is adjusted, a magnification error and a positional shift occur in the transfer image of the pattern on the wafer W due to the displacement of the reticle R in the optical axis direction even though the reticle side of the projection optical system PO is non-telecentric. Can be effectively suppressed, and as a result, the overlay accuracy can be improved. Further, when the reticle stage RST moves from one side to the other side along the Y-axis and when the reticle stage RST moves from the other side to the one side, the positional displacement of the reticle R in the Z direction during the synchronous movement is a mechanical factor. (Movement characteristics of the stage), control characteristics, etc.
The Z position of the reticle R can be adjusted with high accuracy without being affected by the influence of the reticle R, and a magnification error or a position shift occurs in the transfer image of the pattern on the wafer W due to the displacement of the reticle R in the Z direction. It can be suppressed more effectively.

Here, main controller 80 adjusts the position of reticle R during exposure in the Z direction by adjusting at least one of laser interferometers RIFZ1, RIFZ2, and RIFZ3 for measuring reticle surface in advance. Information (first
May be performed by feed-forward controlling the magnetic levitation type two-dimensional linear actuator 34 based on the position information for adjustment and the second position information for adjustment), or the laser interference for reticle surface measurement during actual scanning exposure. Total RI
Adjustment position information obtained by real-time measurement using at least one of FZ1, RIFZ2, and RIFZ3 (first
Of the magnetic levitation type two-dimensional linear actuator 34 based on the adjustment position information and the second adjustment position information). In the former case, during the synchronous movement between the reticle stage RST and the wafer stage WST, the adjustment is performed by feedforward control based on information measured in advance without measuring the Z displacement of the reticle R. During the adjustment, an adjustment error due to a control delay hardly occurs. In the latter case, it is necessary to devise a control system that does not cause a control delay as compared with the former case, but there is an advantage that the position of the reticle R in the Z direction can be adjusted with higher accuracy.

Also, a reticle surface measuring laser interferometer RI
The FZ1, RIFZ2, and RIFZ3 irradiate different positions in the arc-shaped illumination area IA of the reticle R with respective measurement beams, and the Z of the reticle R is irradiated at the irradiation position of each measurement beam.
Since the directional position is measured, by using all of these reticle surface measurement laser interferometers RIFZ1, RIFZ2, and RIFZ3, the pattern transfer area on the reticle R at every moment is determined based on the most accurate measurement data. It is possible to adjust not only the Z position but also the inclination, and as a result, it is possible to further improve the overlay accuracy.

As described above in detail, according to the exposure apparatus 10 according to the first embodiment, the plurality of mirrors M1 to M1 constituting the projection optical system PO by absorbing the illumination light EL.
When a temperature rise occurs in M4, heat is exchanged between the mirrors M1 to M4 and the lens barrel PP by a heat pipe HP as a heat exchanger, and the mirrors M1 to M4 are forcibly brought to the temperature of the lens barrel PP. Cooled. In this case, the lens barrel PP holding the mirrors M1 to M4 is cooled by the cooling jacket 52 as a lens barrel cooling device, and the heat exchange by the heat pipe HP is continuous during the irradiation of the illumination light EL to the mirrors M1 to M4. It is done on a regular basis. Therefore, the deformation of the mirrors M1 to M4 to which the heat pipe HP is connected can be prevented, and the imaging characteristics of the projection optical system PO can be prevented from deteriorating. Image degradation can be suppressed.

In this case, a heat pipe HP is provided between all the mirrors M1 to M4 held in the lens barrel PP and the lens barrel PP to prevent thermal deformation of all the mirrors M1 to M4. However, the present invention is not limited to this, and a heat exchanger such as a heat pipe HP may be connected only to the first mirror M1 which has the shortest optical distance to the reticle R and is irradiated first with the illumination light EL. Alternatively, a heat pipe HP may be connected to the second mirror M2 in addition to the first mirror M1. Since the heat energy of the illumination light EL is the highest at the position of the mirror M1, it is desirable to provide a heat exchanger such as a heat pipe at least between the mirror M1 and the lens barrel PP to forcibly cool the mirror M1. In such a case, since the optical distance to the reticle R is the shortest, the heat absorption is the largest, and the mirror M1 that easily causes the deterioration of the imaging characteristics can be cooled. This is because it becomes possible to suppress it.

In the first embodiment, the lens barrel PP is cooled, and the mirrors M1 to M4 are connected to the lens barrel PP via a heat pipe to cool the mirror by heat exchange of the heat pipe. Configuration, that is,
Since the cooling device for cooling the front side (reflection surface) and the back side of the mirror M1 made of low expansion glass is configured by a combination of the heat pipe HP and the cooling jacket 52,
In addition to taking advantage of materials with low thermal conductivity, such as low expansion glass, the deformation does not deteriorate the imaging characteristics for a considerable temperature change, and a reflective surface so that the temperature change beyond the limit does not occur. By directly cooling the
It is possible to prevent the deterioration of the imaging characteristic of the projection optical system due to the irradiation of the illumination light, and as a result, it is possible to suppress the deterioration of the transferred image due to the fluctuation of the irradiation. However, it goes without saying that the present invention is not limited to such a configuration. For example,
When a reflection optical system including a plurality of mirrors is used as the projection optical system PO, and at least one of the plurality of mirrors is formed of a material having low thermal conductivity (for example, low expansion glass), the reflection A cooling device (for example, a Peltier element) may be directly disposed in the non-irradiation area of the illumination light on the reflection surface of the mirror made of low expansion glass, and the reflection surface of the mirror may be directly cooled. Although surface cooling is effective irrespective of the thermal conductivity of the mirror, the effect of directly cooling the surface (reflective surface) is particularly effective for a mirror having a small thermal conductivity because a temperature gradient is likely to occur when the back surface is cooled. The effect of surface cooling) is large.

In the exposure apparatus 10 according to the present embodiment, a reflection type reticle is used as the reticle R, and the second cooling device disposed on the side of the reticle R opposite to the side of incidence of the illumination light EL (pattern surface side). Is provided, the irradiation fluctuation of the reticle R can be suppressed, and the deterioration of the transferred image due to the irradiation fluctuation can be suppressed more effectively.

In this embodiment, since the heat pipe HP is used as the heat exchanger, it is possible to contribute to the reduction in weight and size of the equipment. However, the present invention is not limited to this, and other heat exchangers may be used. good.

Further, according to the present embodiment, when transferring the reticle pattern, the stage control system (80, 34, 6) is used.
In 2), the reticle R and the wafer W are synchronously moved at a speed ratio according to the magnification of the projection optical system PO. During this synchronous move,
The main controller 80 moves the reticle R relative to the projection optical system PO in the Z direction based on the output of the interferometer RIFZ in order to correct the image magnification error of the pattern. As a result, the occurrence of a magnification error in the transferred image of the pattern on the wafer W can be effectively suppressed, and as a result, the overlay accuracy can be improved.

Further, according to the present embodiment, the illumination system (1
2, PRM, IM, 30, M, 44) irradiate the reticle R with EUV light having a wavelength of 5 to 15 nm as illumination light EL, and a plurality of reflection optical elements (M1) as projection optical system PO.
To M4), the reticle pattern is projected onto the projection optical system P using EUV light.
Since it is transferred to the wafer W via O, a very fine pattern, for example, a 100 nm L / S pattern can be transferred with high accuracy. In addition, since illumination light having a short wavelength such as EUV light has a large irradiation energy, in this embodiment, the mirror is cooled as described above in consideration of the importance of cooling the mirror constituting the projection optical system PO. ing.

Further, according to the present embodiment, interferometer system 70 includes reticle stage RST and wafer stage WS.
The relative position of the reticle R with respect to the projection optical system PO in the Z direction is measured by a laser interferometer RIFZ with respect to the projection optical system PO with respect to the projection optical system PO. Since the relative position in the direction is measured by the focus sensor 14, the reticle stage RST and the wafer stage WST
Even if the and the projection optical system PO are supported by separate support members, there is no problem. For this reason, reticle stage RS
T, wafer stage WST, and projection optical system PO need not be mechanically connected, so that reticle stage RS
T, the reaction force due to the acceleration / deceleration during the movement of the wafer stage WST and the vibration of the support member of each stage adversely affect the imaging characteristics of the projection optical system PO, or the reaction due to the acceleration / deceleration during the movement of one of the stages. The force does not adversely affect the behavior of the other stage via the support member.

Further, according to the present embodiment, the slit plate 44 in the illumination optical system has the first slit 44a for irradiating a part of the reticle pattern with the illumination light EL and the second slit 44a for irradiating the reticle alignment mark with the illumination light EL. 2 slits 44
b, and a driving mechanism 46 for switching the first slit 44a and the second slit 44b with respect to the illumination light EL is provided, so that the same slit plate 44 is suitable for exposure and alignment. It is possible to set an illumination area. Also, in this case, the degree of freedom of the cross-sectional shape of the illumination light irradiated from the illumination optical system toward the reticle R is increased as compared with the case where the slit plate 44 is not provided, and the optical element constituting the illumination optical system accordingly. The degree of freedom of design is improved.

In this embodiment, the illumination light E for exposure is used.
L is light in a soft X-ray region, and a fluorescence generating substance 63 is provided on a wafer stage WST and an illumination light EL for exposure is provided on the surface thereof.
SLT formed by the thin film of the reflective layer 62
And a photoelectric conversion element PM that photoelectrically converts light emitted from the fluorescent substance 63 when the illumination light for exposure EL reaches the fluorescent substance 63 via the slit SLT. In spite of the fact that there is no substance that normally transmits light in the soft X-ray region, even when such light is used as illumination light for exposure, an aerial image can be measured using the illumination light for exposure. It is possible to easily obtain the projection position of the reticle pattern on wafer stage WST using image measuring instrument FM.

In this embodiment, since the pattern of the reticle R is formed by the EUV light (exposure illumination light) EL absorbing material formed on the reflection layer of the EUV light EL, Unlike the case where the multilayer film is patterned as a reflection material of light in the soft X-ray region, which is the illumination light, the pattern can be repaired in the case of failure. In addition, by appropriately selecting the material of the absorbing substance, the reflecting layer of the exposure illumination light and the absorbing substance can be made to have substantially the same reflectance with respect to the measurement beam (for example, light in the visible region) of the interferometer RIFZ. And the Z-axis position of the reticle R can be measured with almost the same accuracy over the entire surface of the reticle R.

In the above embodiment, the projection optical system PO
Although the case where the lens barrel PP is cooled during the irradiation of the illumination light EL is illustrated, the invention is not limited thereto, and the lens barrel may be cooled in advance. Even in such a case, the illumination light EL emitted from the reticle R is reflected by the mirror (reflection optical element) M1.
To the mirrors M1 to M4, and the mirrors M1 to M4
When the temperature rises due to the heat energy of L, heat exchange is performed between the mirror and the lens barrel by a heat exchanger such as a heat pipe, and the mirror is cooled. The heat exchange by the heat exchanger is performed until the temperatures of the reflective optical element and the lens barrel match. Therefore, it is possible to prevent the imaging characteristics of the projection optical system PO from deteriorating due to the irradiation of the illumination light EL to some extent, and as a result, it is possible to suppress the deterioration of the transfer image due to the irradiation fluctuation.

In the above embodiment, the heat pipe H
A case has been described where P is connected to both a part of the reflecting surface of the mirrors M1 to M4 and the back surface thereof. However, the present invention is not limited to this. It may be connected to.

In the above embodiment, the case where the reference mirror integrated type is used as the reticle surface measuring laser interferometer RIFZ is exemplified. However, the present invention is not limited to this, and the interferometer for measuring the reticle Z position is not limited to this. And a reference mirror fixed to the projection optical system, and an interferometer body disposed at a position distant from the projection optical system. In such a case, it is possible to avoid adversely affecting the optical characteristics of the projection optical system or various sensors fixed to the projection optical system, such as an alignment sensor and a focus sensor, due to the heat generated by the interferometer body. In the above embodiment, the laser interferometer RI
The case where three measurement beams from the FZ are irradiated into the illumination area IA on the reticle R has been described. However, the present invention is not limited to this. For example, the interferometer RIFZ irradiates different positions of the reticle R in the Y direction with the measurement beams. Then, the position of the reticle R in the Z direction may be measured for each irradiation position of each measurement beam. In such a case, at least in the Y direction (synchronous movement direction), it is possible to adjust the positional shift and the tilt shift of the reticle R in the optical axis direction during the synchronous movement between the reticle R and the wafer W. In this case, the interferometer RIF
When irradiating at least two measurement beams from Z to both sides in the Y direction of the illumination area IA on the reticle,
By performing so-called pre-read control during the synchronous movement between the reticle R and the wafer W, the Z position of the reticle R can be adjusted by feed forward.

In the above embodiment, the driving member for moving the reticle R in the Z direction on the object plane side of the projection optical system PO during the synchronous movement is the reticle stage WST for holding the reticle R and the magnetic levitation for driving the reticle stage WST. However, the present invention is not limited to this, and another type such as a piezo element that drives a reticle holder RH holding a reticle R on a reticle stage RST in a Z direction at a plurality of points is described. An actuator may be provided to form the driving member. In any case, it is desirable that the driving member is to tilt the reticle R relatively to the object plane of the projection optical system PO. In such a case, during the synchronous movement, in addition to the reticle R being moved in the Z direction on the object plane side of the projection optical system PO by the driving member, the inclination of the projection optical system PO with respect to the object plane can be adjusted. In spite of the fact that the object plane side of the projection optical system is non-telecentric, it is possible to effectively prevent a transfer error of the pattern on the wafer W from being caused by a magnification error or a displacement due to the displacement of the reticle R in the optical axis direction. As a result, the overlay accuracy can be improved.

In the above embodiment, the slit plate 44
The case where the arc-shaped illumination area IA is defined by using is described. However, the present invention is not limited to this. If each optical member constituting the illumination optical system is designed so that the illumination light EL has an arc shape. It is not always necessary to provide the slit plate 44 immediately below the reticle R.

The reticle alignment mark is RM
Instead of the positions of 1 to RM6, RM7 to RM12 in FIG.
Position. In such a case, the slit plate 44
As long as there is a slit plate having only the first slit 44a, the driving mechanism 46 is unnecessary. Alternatively, reticle alignment marks may be formed at all positions of RM1 to RM12, and all of them may be used.

<< Second Embodiment >> Next, a second embodiment of the present invention will be described with reference to FIG. here,
The same reference numerals are used for the same or equivalent components as those in the first embodiment, and the detailed description is omitted.

FIG. 13 shows an exposure apparatus 1 according to the second embodiment.
00 is schematically shown. Similarly to the above-described exposure apparatus 10, this exposure apparatus 100 also includes light (E) in the soft X-ray region having a wavelength of
This is a projection exposure apparatus that performs an exposure operation by a step-and-scan method using UV light.

The exposure apparatus 100 differs from the above-described exposure apparatus 10 in that a projection optical system PO 'is provided instead of the above-described projection optical system PO, and is characterized in this point.

The projection optical system PO ′ is composed of two parts, a first divided lens barrel PP and a second divided lens barrel PP ′ which are arranged along the Z direction and are connected to each other. Each of the split lens barrels PP and PP ′ is independently cooled by a separate cooling device. That is, the first split lens barrel P
P has a double structure of the inner inner member 50 and the cooling jacket 52 as a lens barrel cooling device mounted on the outer peripheral portion, similarly to the lens barrel PP of the first embodiment described above. A spiral pipe 58 for flowing the cooling liquid from the inflow tube 54 side to the outflow tube 56 side is provided inside 52. Here, cooling water (or Fluorinert (fluorinated inert liquid) manufactured by Sumitomo 3M Limited) is used as the cooling liquid. The cooling water flowing out of the cooling jacket 52 via the outflow tube 56 is
Heat exchange is performed between the refrigerant and the refrigerant in a refrigeration apparatus (not shown), and after cooling to a predetermined temperature, the refrigerant flows into the cooling jacket 52 via the inflow tube 54, and thus the cooling water Is circulated.

Similarly, the second split barrel PP ′ is
It has a double structure of an inner inner member 51 and a cooling jacket 53 as a lens barrel cooling device mounted on the outer peripheral portion thereof. A helical pipe 59 is provided for flowing through the pipe. Here, cooling water is used as the cooling liquid. The cooling water flowing out of the cooling jacket 53 via the outflow tube 57 exchanges heat with the refrigerant in a refrigeration device (not shown), and is cooled to a predetermined temperature. The cooling water is circulated in this manner.

Here, in the second embodiment, the mirror M
2, M4 are held in the split lens barrel PP, and the mirrors M1, M
3 is held in the split lens barrel PP '. Mirror M2,
M4 and the split lens barrel PP holding these are connected by a heat pipe HP as a heat exchanger. Similarly,
The mirrors M1 and M3 and the split barrel PP 'holding these are connected by a heat pipe HP as a heat exchanger.

In the exposure apparatus 100 according to the second embodiment configured as described above, the same effects as those of the above-described first embodiment can be obtained, and each of the divided barrels PP and P can be obtained.
By flowing cooling water of different temperatures into the cooling jackets 52 and 53 of P ′, it is possible to forcibly cool each of the divided lens barrels to different temperatures. Here, the reflected light from the reticle R first The split barrel PP ′ holding the irradiated mirror M1 (and M3) is moved to the mirror M2 (and M
Cooling is performed at a lower temperature than the divided lens barrel PP holding 4). As a result, the mirror M1 having the largest heat absorption and easily causing the deterioration of the imaging characteristics is cooled more efficiently than the other mirrors, and as a result, the deterioration of the transferred image due to the irradiation variation is efficiently suppressed.

The projection optical system and the illumination optical system shown in the first and second embodiments are merely examples, and it goes without saying that the present invention is not limited to these.

In each of the above embodiments, the illumination light E
L is not limited to EUV light having a wavelength of 13.4 nm, and EUV light having a wavelength of 11.5 nm may be used. In this wavelength region, a multilayer film in which molybdenum and beryllium are alternately laminated is formed on the surface of the optical element. Note that 70
To transfer an nm L / S pattern or a 50 nm isolated pattern, a projection optical system having a numerical aperture of about 0.1 to 0.12 is used for EUV light having a wavelength of 13.4 nm, and EUV light having a wavelength of 11.5 nm is used. The numerical aperture is 0.08 to 0.1
A degree of projection optics is used.

Further, in the light source device 12 of the above embodiment, a tape target such as a copper tape is used, but a gas jet target or a cryo target may be used instead.

In the first and second embodiments, the movable blind 42 and the field stop (slit plate) 44 are arranged close to the pattern surface of the reticle R.
At least one of the blind 42 and the field stop 44 may be arranged on a surface substantially conjugate with the pattern surface of the reticle R in the illumination optical system.

Further, in each of the above-described embodiments, the case where the present invention is applied to the exposure apparatus using EUV light as the illumination light for exposure has been described. However, the present invention is not limited to this. However, the present invention is applicable to any apparatus that employs a reflection system consisting of only a reflection optical element or a catadioptric system (catadioptric system) having a reflection optical element and a refractive optical element as a projection optical system. The same effect can be obtained. For example, a wavelength of 200 nm
In an exposure apparatus that uses vacuum ultraviolet light (VUV light) of a degree or less, a catadioptric system may be used as the projection optical system. In this case, a reflective optical element (concave mirror, mirror, etc.)
May be made of a material having a low thermal conductivity, and a heat exchanger such as a heat pipe may be connected to the back surface and, if necessary, to the non-irradiation area of the illumination light on the front surface (reflection surface).

Here, as a catadioptric projection optical system, for example, Japanese Patent Application Laid-Open Nos.
A catadioptric system having a beam splitter and a concave mirror as reflective optical elements, as disclosed in, for example,
Or JP-A-8-334695, JP-A-10-30
No. 39, a catadioptric system having a concave mirror or the like can be used as a reflective optical element without using a beam splitter.

In addition, US Pat. No. 5,031,976
No. 5,488,229 and 5,717,51
No. 8 discloses a plurality of refractive optical elements and two mirrors (a primary mirror that is a concave mirror, and a sub-mirror that is a back mirror in which a reflective surface is formed on a side opposite to the incident surface of a refractive element or a parallel flat plate). ) May be arranged on the same axis, and a catadioptric system may be used in which an intermediate image of the reticle pattern formed by the plurality of refractive optical elements is re-imaged on the wafer by the primary mirror and the secondary mirror. In this catadioptric system, a primary mirror and a secondary mirror are arranged following a plurality of refractive optical elements, and illumination light is reflected through a part of the primary mirror in the order of a secondary mirror and a primary mirror. Part to reach the wafer.

When a catadioptric projection optical system is used, a plurality of divided barrels each holding at least one optical element are used, and each of the plurality of divided barrels is cooled. A temperature controller may be connected.
Alternatively, a heat insulating material may be provided between the projection optical system (for example, a flange portion) and a mount that holds the projection optical system to prevent heat from being transmitted to the projection optical system through the mount.

The catadioptric projection optical system has, for example, a circular image field, is telecentric on both the object side and the image side, and has a projection magnification of 1/4 or 1/5. A double reduction system may be used. Further, in the case of a scanning exposure apparatus having this catadioptric projection optical system, the irradiation area of the illumination light is substantially centered on its optical axis within the field of view of the projection optical system, and is substantially in the scanning direction of the reticle or wafer. It may be of a type defined in a rectangular slit shape extending along the orthogonal direction. According to a scanning exposure apparatus provided with such a catadioptric projection optical system, for example, a high accuracy 100 Nml / S pattern about fine patterns using a F ₂ laser beam having a wavelength of 157nm as exposure illumination light on the wafer Can be transferred to

Further, ArF excimer laser light, F ₂ laser light or the like is used as the vacuum ultraviolet light, but the infrared region oscillated from a DFB semiconductor laser or a fiber laser,
Alternatively, a single-wavelength laser beam in the visible region may be amplified by, for example, a fiber amplifier doped with erbium (or both erbium and ytterbium), and a harmonic converted into ultraviolet light using a nonlinear optical crystal may be used. .

For example, the oscillation wavelength of a single-wavelength laser is set to 1.
When the wavelength is in the range of 51 to 1.59 μm, the generated wavelength is 18
An eighth harmonic having a wavelength in the range of 9 to 199 nm or a tenth harmonic having a generation wavelength in the range of 151 to 159 nm is output. In particular, the oscillation wavelength is 1.544 to 1.553 μm.
m, an 8th harmonic whose generation wavelength is in the range of 193 to 194 nm, that is, ultraviolet light having substantially the same wavelength as the ArF excimer laser light is obtained, and the oscillation wavelength is 1.57.
When it is within the range of 1.58 μm, the generated wavelength is 157 to
The 10th harmonic within the range of 158 nm, that is, ultraviolet light having substantially the same wavelength as the F ₂ laser light is obtained.

The oscillation wavelength is set to 1.03 to 1.12 μm.
, A 7th harmonic whose output wavelength is in the range of 147 to 160 nm is output.
When the wavelength is in the range of 099 to 1.106 μm, a seventh harmonic having a generation wavelength in the range of 157 to 158 μm, that is, ultraviolet light having substantially the same wavelength as the F ₂ laser beam is obtained. In this case, as the single-wavelength oscillation laser, for example, an ytterbium-doped fiber laser can be used.

Further, not only an exposure apparatus used for manufacturing a semiconductor element but also an exposure apparatus used for manufacturing a display including a liquid crystal display element for transferring a device pattern onto a glass plate, and manufacturing a thin film magnetic head The present invention can also be applied to an exposure apparatus used to transfer a device pattern onto a ceramic wafer, an exposure apparatus used to manufacture an imaging device (such as a CCD), and the like.

In addition to a micro device such as a semiconductor device, a glass substrate or a mask for manufacturing a reticle or a mask used in an optical exposure apparatus, an EUV exposure apparatus, an X-ray exposure apparatus, an electron beam exposure apparatus, or the like. The present invention is also applicable to an exposure apparatus that transfers a circuit pattern onto a silicon wafer or the like. Here, a transmissive reticle is generally used in an exposure apparatus using DUV (far ultraviolet) light or VUV (vacuum ultraviolet) light, and quartz glass is used as a reticle substrate.
Quartz glass, fluorite, magnesium fluoride, quartz, or the like doped with fluorine is used. In a proximity type X-ray exposure apparatus or an electron beam exposure apparatus, a transmission mask (stencil mask, membrane mask) is used.
And a silicon wafer or the like is used as a mask substrate.

[0145]

As described above, according to the exposure apparatus according to each of the first to twenty-first aspects of the present invention, it is possible to effectively suppress the deterioration of the transferred image due to the irradiation fluctuation. There is no excellent effect.

[Brief description of the drawings]

FIG. 1 is a view schematically showing a configuration of an exposure apparatus according to a first embodiment.

FIG. 2 is a diagram showing a configuration of the inside of the light source device of FIG. 1;

FIG. 3 is a left side view of the light source device of FIG. 2;

FIG. 4 is a diagram showing in detail each component of the configuration near the reticle stage in FIG. 1;

FIG. 5 is a schematic plan view of a reticle.

FIG. 6 is a diagram illustrating a configuration of an interferometer system that measures the positions of a reticle stage and a wafer stage in an XY plane.

FIG. 7 is a plan view showing an example of the slit plate of FIG. 1 and a driving mechanism thereof.

8 is a diagram schematically showing an internal configuration of the projection optical system of FIG.

9A is a schematic perspective view for explaining a support structure of each mirror in FIG. 8, and FIG. 9B is a side view of FIG.

10A is a plan view showing an aerial image measuring device, and FIG.
FIG. 2 is a side view showing the aerial image measuring device of FIG.

FIG. 11 is a block diagram schematically showing a configuration of a control system related to position and orientation control of a wafer (wafer stage) and a reticle (reticle stage).

FIG. 12 is a diagram showing how a reticle pattern is transferred to a plurality of shot areas on a wafer.

FIG. 13 is a view schematically showing an overall configuration of an exposure apparatus according to a second embodiment.

[Explanation of symbols]

10 Exposure device, 36 Temperature control unit (second cooling device),
52: water cooling jacket (a part of the lens barrel cooling device, cooling device), 53: water cooling jacket, R: reticle (mask), PO: projection optical system, W: wafer (substrate), M1 ...
First mirror (reflective optical element), M2: second mirror (reflective optical element), M3: third mirror (reflective optical element), M4
... 4th mirror (reflection optical element), HP ... heat pipe (heat exchanger, part of cooling device), PP ... barrel (first split barrel), PP '... second split barrel, EL ... lighting light.

Claims (21)

[Claims] 1. An exposure apparatus that irradiates a mask with illumination light and transfers a pattern formed on the mask onto a substrate via a projection optical system, wherein the projection optical system includes a plurality of mirrors. A system is used, at least one of the plurality of mirrors is formed of a material having a low thermal conductivity, and the mirror formed of the material having a low thermal conductivity has a mirror on a reflecting surface to which the illumination light is irradiated. An exposure apparatus including a cooling device arranged in a non-irradiation area of illumination light. 2. The exposure apparatus according to claim 1, wherein a cooling device is also arranged on a back side of the mirror on which the cooling device is arranged on the reflection surface. 3. An exposure apparatus for irradiating a mask with illumination light and transferring a pattern formed on the mask onto a substrate via a projection optical system, wherein the illumination light is sequentially applied as the projection optical system. A reflection optical system including a plurality of mirrors including a first mirror and a second mirror to be used, and a lens barrel cooling device for cooling a lens barrel holding the plurality of mirrors; and at least one of the plurality of mirrors An exposure apparatus comprising: a mirror; and a heat exchanger provided between the mirror and the lens barrel. 4. The lens barrel comprises a plurality of divided lens barrels each holding at least one mirror, the lens barrel cooling device independently cools each of the divided lens barrels, and the heat exchanger comprises: The exposure apparatus according to claim 3, wherein at least one each is provided between each of the divided barrels and at least one mirror held by the divided barrel. 5. One of the plurality of split barrels is a split barrel that holds the first mirror to which the illumination light is first irradiated, and one of the heat exchangers is The lens barrel cooling device is provided between a first mirror and a split barrel that holds the first mirror, and cools the split barrel that holds the first mirror at a lower temperature than the other split barrels. The exposure apparatus according to claim 4, wherein: 6. The exposure apparatus according to claim 3, wherein the heat exchanger is a heat pipe. 7. The mask according to claim 1, wherein the mask is a reflective mask, and further includes a second cooling device disposed on a side of the mask opposite to a side on which the illumination light is incident. Exposure equipment. 8. An exposure apparatus having an illumination optical system for irradiating a mask with illumination light, and transferring a pattern formed on the mask onto a substrate, the exposure apparatus having a reflection optical element and being emitted from the mask. An exposure apparatus comprising: a projection optical system that projects illumination light onto the substrate; and a heat exchanger provided between the reflective optical element and a lens barrel that holds the reflective optical element. 9. The exposure apparatus according to claim 8, wherein the heat exchanger is connected to at least one of a part of a reflection surface of the reflection optical element and a back surface thereof. 10. The projection optical system includes only a plurality of reflection optical elements, and at least one of the plurality of reflection optical elements.
10. An exposure apparatus according to claim 8, wherein one of the exposure apparatuses is connected to the heat exchanger. 11. The exposure apparatus according to claim 10, wherein a reflection optical element having the shortest optical distance to the mask among the plurality of reflection optical elements is connected to the heat exchanger. 12. The projection optical system according to claim 10, wherein the projection optical system has a ring image field, and is an optical system that is non-telecentric on the object plane side and telecentric on the image plane side. Exposure equipment. 13. The illumination optical system according to claim 8, wherein the mask is a reflection type mask, and the illumination optical system irradiates the illumination light with a principal ray inclined to a pattern surface of the mask. The exposure apparatus according to any one of the above. 14. The exposure apparatus according to claim 1, wherein the illumination light is EUV light having a wavelength of 5 to 15 nm. 15. The exposure apparatus according to claim 14, further comprising an aperture member that defines an illumination area of the illumination light in an arc slit shape within a field of view of the projection optical system. 16. The exposure apparatus according to claim 8, wherein the projection optical system is a reduction system having the reflection optical element and the refraction optical element. 17. An exposure apparatus according to claim 16, wherein said projection optical system has a circular image field, and both the object plane side and the image plane side are telecentric optical systems. 18. The illumination light according to claim 16, wherein the illumination light is vacuum ultraviolet light having a wavelength of about 200 nm or less.
8. The exposure apparatus according to 7. 19. The exposure apparatus according to claim 18, wherein the illumination optical system defines an irradiation area of the illumination light in a rectangular slit shape within a field of view of the projection optical system. 20. A stage system for relatively moving the mask and the substrate relative to the illumination light, respectively, wherein the mask and the substrate are synchronously moved at a speed ratio according to a magnification of the projection optical system. 20. The exposure apparatus according to claim 1, wherein the substrate is scanned and exposed with the illumination light via the mask and the projection optical system. 21. A first position detecting system for detecting position information of the mask in the optical axis direction of the projection optical system during the synchronous movement, and a second position for detecting position information of the substrate in the optical axis direction. The exposure apparatus according to claim 20, further comprising a detection system.