JP2000100697A - Aligner and method for adjusting it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an adjusting method for an aligner wherein an internal optical system is adjusted in a short time with high precision. SOLUTION: A laser plasma light source in a light source device 12 generates an EUV(extreme ultraviolet) light EL1 as an exposure light, an ultraviolet light EL2 as a non-exposure light, and a visible light AL as a non-exposure light, and a wavelength selecting device in the light source device 12 allows an reticule R to be irradiated with either the EUV light EL1, the ultraviolet light EL2, or the visible light AL through a mirror M, with the light from the reticule R guided on a wafer W through a projection optical system PO of reduction projection type comprising a reflective system. A lighting system comprising a part of the optical member in the light source device 12 and the mirror M and the projection optical system PO are rough-adjusted using the visible light AL or the ultraviolet light EL2, and the lighting system and the projection optical system PO are final-adjusted using the EUV light EL1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exposure apparatus used for transferring a mask pattern onto a substrate in a lithography process for manufacturing, for example, a semiconductor device, an image pickup device (CCD or the like), a liquid crystal display device or the like. Regarding the adjustment method of
In particular, extreme ultraviolet light (E
It is suitable for use in an exposure apparatus that uses xtreme Ultra Violet light (EUV light).

[0002]

2. Description of the Related Art In manufacturing a semiconductor device or the like, in order to transfer a reticle pattern as a mask onto a wafer (or a glass plate or the like) coated with a resist as a substrate, a reduction projection type such as a stepper is used. Various types of exposure apparatuses such as an exposure apparatus or a proximity type exposure apparatus that directly transfers a reticle pattern onto a wafer are used. In such an exposure apparatus, conventionally, i-line (wavelength 365 nm) of a mercury lamp or Kr is used as illumination light (exposure light) for exposure.
Ultraviolet light such as F excimer laser light (wavelength 248 nm) has been used. Recently, in order to obtain higher resolution, ArF excimer laser light (wavelength 193) is used as exposure light.
Exposure apparatuses using vacuum ultraviolet light (VUV light) such as F2 laser light (wavelength: 157 nm) and F ₂ laser light (wavelength: 157 nm) are also being developed. In addition, a refraction system or a catadioptric system has been used as an illumination system or a projection optical system of these conventional exposure apparatuses.

In the case where ultraviolet light is used as the exposure light, it is inefficient to perform the assembly adjustment of the illumination system and the projection optical system from the first rough adjustment to the final adjustment using the exposure light. Therefore, separately from an exposure light source that conventionally generates exposure light composed of ultraviolet light, a light source for adjustment that generates visible light such as a He-Ne laser is used, and visible light from the light source for adjustment is used. The coarse adjustment of the illumination system and the projection optical system has been performed by a collimator system or an interferometer system. Then, after performing the rough adjustment, the final adjustment of those optical systems is performed using the exposure light.

[0004]

As described above, conventionally, a light source for adjustment is provided separately from an exposure light source, and coarse adjustment of an illumination system and a projection optical system is performed using visible light from the light source for adjustment. . In this case, for example, it is necessary to arrange a mirror or the like for guiding the visible light for adjustment so as to be substantially coaxial with the exposure light in the illumination system, and the adjustment including the exposure light source and the illumination system cannot be performed. . Therefore, it is difficult to increase the accuracy of the coarse adjustment, and the time required for the final adjustment using the exposure light becomes longer, and as a result, the time required for the assembly adjustment becomes longer. Further, in an exposure apparatus, it is necessary to periodically adjust an illumination system and a projection optical system in order to perform maintenance and the like. Since it was necessary to arrange a mirror for guiding visible light for adjustment in the system, the adjustment operation was complicated and took a long time.

Conventionally, the illumination system and the projection optical system are refraction systems or catadioptric systems, and the wavelengths of the exposure light and the adjustment visible light are significantly different. At the time of adjustment, chromatic aberration occurred in the illumination system and the projection optical system. Due to this chromatic aberration, the error of the coarse adjustment becomes large, and the time of the final adjustment becomes long. In particular, in order to manufacture finer semiconductor elements in the future,
Exposure apparatuses using extreme ultraviolet light (EUV light) having a wavelength of about 100 nm or less as exposure light are also being developed. When the EUV light is used as the exposure light,
Since the size of the exposure light source is increased, there is a demand for an adjustment method that can efficiently adjust the illumination system and the projection optical system including the exposure light source.

In view of the above, it is a first object of the present invention to provide a method of adjusting an exposure apparatus which can adjust an internal optical system in a short time and with high accuracy. It is a second object of the present invention to provide a method of adjusting an exposure apparatus that can efficiently adjust an internal optical system in an exposure apparatus that uses EUV light as exposure light.

Another object of the present invention is to provide an exposure apparatus capable of performing the adjusting method.

[0008]

According to a first method of adjusting an exposure apparatus according to the present invention, an exposure light source for generating illumination light (EL1) for exposure and an illumination light from the exposure light source are applied to a mask (R). An illumination system for irradiating the mask, the pattern of the mask being transferred onto the substrate (W) under the illuminating light, wherein the illuminating light for the exposure (EL1) is used as the exposure light source. And a broadband light source (16) for generating non-exposure wavelength light (AL) having a wavelength range different from that of the illumination light.
And its illumination system (PRM, IM, 42, 44,
When adjusting at least a part of the optical system in M), light (A) of the non-exposure wavelength emitted from the broadband light source is used.
L).

According to the present invention, when adjusting a part of the optical system, a light source for measurement is separately used by using light of the non-exposure wavelength emitted from the broadband light source. The adjustment of the optical system can be performed in a short time without the need. Further, since the light of the non-exposure wavelength is emitted from almost the same position as the illumination light for exposure (emitted almost coaxially), the adjustment of the optical system is performed with high accuracy as in the actual exposure. be able to.

Further, according to a second method of adjusting an exposure apparatus according to the present invention, there is provided an exposure light source for generating illumination light for exposure (EL1), and an illumination system for irradiating the mask (R) with illumination light from the exposure light source. A method of adjusting an exposure apparatus for transferring a pattern of a mask onto a substrate (W) under the illumination light, the illumination light for exposure being used as the exposure light source, and the illumination light and wavelength A broadband light source (16) for generating light (AL) of a non-exposure wavelength having a different region is used, and its illumination system (P
RM, IM, 42, 44, M), the light (AL) of the non-exposure wavelength emitted from the broadband light source is used to roughly adjust at least a part of the optical system. When making final adjustments, the exposure illumination light (EL1) emitted from the broadband light source is used.

According to the second adjusting method of the exposure apparatus, the optical system can be roughly adjusted with high accuracy in a short time without using a separate light source for measurement. Therefore,
Since the adjustment error is small, the final adjustment of the optical system using the exposure illumination light can be performed in a short time. In these cases, the exposure apparatus condenses illumination light from the mask and projects an image of a pattern of the mask onto the substrate by a projection system (P).
O) for adjusting the illumination system and at least a part of the optical system in the projection system.
It is desirable to use the light of the non-exposure wavelength emitted from 6). When the projection system is a reflection system, since there is no chromatic aberration, the adjustment is performed with high accuracy even using the light of the non-exposure wavelength.

Next, a third method for adjusting an exposure apparatus according to the present invention includes an exposure light source for generating exposure illumination light (EL1);
An illumination system for irradiating the mask (R) with the illumination light and a projection system (P) for projecting a pattern image of the mask on the substrate (W)
O), wherein the exposure light source is a broadband light source that generates illumination light for exposure and light of a non-exposure wavelength having a wavelength range different from that of the illumination light. In adjusting at least a part of the optical system of the projection system, the light of the non-exposure wavelength emitted from the broadband light source is used. According to the present invention, the optical system is adjusted in a short time.

As an evaluation method used when adjusting the projection system, a point image or a spatial image of a periodic pattern may be observed on an image plane, or a point image is observed at a position defocused from the image plane. This makes it possible to measure the wavefront aberration of the projection system. Any other observation method may be used. In addition, the broadband light source has, as an example, a wavelength in an extreme ultraviolet region (wavelength of about 100 to
1 nm), and at least one of an ultraviolet region (wavelength of about 400 to 100 nm) and a visible region (wavelength of about 800 to 400 nm) as non-exposure wavelength light. The illumination system (IM, M) is preferably a reflection system. When the illumination system is a reflection system, since there is no chromatic aberration, the adjustment is performed with high accuracy even using the light of the non-exposure wavelength. Further, when the light of the non-exposure wavelength is ultraviolet light, the light can be easily detected by a detector having a simple structure such as a photodiode, so that the optical adjustment mechanism is inexpensive. On the other hand, when the light of the non-exposure wavelength is visible light, the operator can view the light, so that the optical adjustment can be easily performed.

An example of the broadband light source is a laser plasma light source, and the illumination light for exposure has a wavelength of 5 to 20 n.
It is desirable that the light be an extreme ultraviolet light (EUV light) of m. The laser plasma light source is made of copper (Cu) tape, water droplets, ice droplets, xenon gas (Xe), or krypton gas (K).
r) is a light source that irradiates a target with a very powerful laser beam to make the target a high-temperature plasma state and emits light of various wavelengths when the target cools. It is said that EUV light having a wavelength of about 5 to 20 nm used for exposure is about 1 to 2% of the energy of light applied to the target, and the remaining 98 to 99% is light of another wavelength. Released.

[0015] Among other wavelengths of light, there is also light having a wavelength very close to illumination light for exposure, and they are designed to reflect only light of a specific wavelength (for example, 5 to 20 nm). The light is absorbed by the multilayer reflection mirror without being reflected and is converted into heat. Visible light and ultraviolet light close to visible light are emitted from the uppermost layer of the multilayer film, such as molybdenum (Mo) and beryllium (Be). ) Or silicon (S
The light is reflected by i) and the like, and can reach the illumination system and further to the projection system. Therefore, a laser plasma light source is suitable as the exposure light source of the present invention because it can emit the illumination light for exposure and the light of the non-exposure wavelength almost completely coaxially.

When adjusting the optical system using the light of the non-exposure wavelength, a predetermined gas (for example, air) is supplied to the optical path of the light of the non-exposure wavelength, and the illumination for the exposure is performed. When performing exposure or adjustment using light, it is desirable that the optical path of the illumination light for exposure is substantially evacuated. When the light of the non-exposure wavelength is visible light or ultraviolet light close to visible light, even if air or the like is supplied to the optical path, the light is hardly absorbed, and the adjustment work becomes easy. On the other hand, if the exposure illumination light is EUV light, the absorption will increase unless the optical path is made substantially vacuum.

Next, the first exposure apparatus according to the present invention comprises an exposure light source for generating illumination light (EL1) for exposure and an illumination system for irradiating the mask (R) with illumination light from the exposure light source. An exposure apparatus for transferring a pattern of a mask onto a substrate (W), comprising, as an exposure light source, illumination light for exposure and light (AL) having a non-exposure wavelength different from that of the illumination light. A photoelectric detector (82, 82) for detecting light of the non-exposure wavelength that has passed through at least a part of optical systems in the illumination system (PRM, IM, 42, 44, M). 86). By using the detection signal of this photoelectric detector, the first and second aspects of the present invention
Alternatively, the second exposure apparatus adjusting method can be performed.

Next, a second exposure apparatus according to the present invention comprises an exposure light source for generating illumination light for exposure, an illumination system for irradiating the illumination light to a mask (R), and a pattern image of the mask on a substrate ( W) a projection system (PO) for projecting light onto the exposure system, the illumination light for exposure being used as the exposure light source, and a broadband for generating non-exposure wavelength light having a wavelength range different from that of the illumination light. A third exposure apparatus according to the present invention, comprising a light source (16) and a light detector (86) for detecting light of the non-exposure wavelength passing through at least a part of the projection system. Adjustment method can be used.

In these cases, there is provided a projection system (PO) for condensing illumination light from the mask and projecting an image of the pattern of the mask onto the substrate, and the illumination system and the projection system are each provided with a reflection system. And a stage system (RST, W) that synchronously moves the mask and the substrate in a predetermined direction.
ST), and when transferring the image of the pattern of the mask onto the substrate, it is preferable that the stage system is driven to synchronously scan the mask and the substrate with respect to the projection system. In the case where the projection system is a reflection system, a region where good image formation is possible is formed in an arc shape on the half surface where chromatic aberration is eliminated. Therefore, by using a scanning exposure method such as a step-and-scan method, it is possible to expose a wide shot area on the substrate.

Further, a wavelength selecting device (30) for passing any one of the exposure illumination light and the non-exposure wavelength light emitted from the broadband light source (16) to the illumination system side.
Is desirably provided. Furthermore, when the illumination light for exposure is EUV light in the light emitted from the broadband light source, light having a longer wavelength, for example, about 100 to 300 nm emitted from the broadband light source is used. By exposing the rough layer with relatively low required accuracy,
The EUV light may be used to perform exposure on a critical layer that requires the highest accuracy. Thus, the exposure apparatus can be widely used for various purposes.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 schematically shows the entire configuration of an exposure apparatus 10 of the present example.
The exposure apparatus 10 emits extreme ultraviolet light (EUV light) E in a soft X-ray region having a wavelength of 5 to 20 nm as illumination light (exposure light) for exposure.
This is a reduction projection type exposure apparatus that performs a scanning exposure operation by a step-and-scan method using L1. In this example, as will be described later, a projection optical system PO that projects the principal ray of the reflected light beam from the reticle R as a mask on a wafer W substantially vertically is used. E from the projection optical system PO to the wafer W
The projection direction of the principal ray of the UV light EL1 is referred to as the optical axis direction of the projection optical system PO, the optical axis direction is the Z axis direction, and the horizontal direction in the plane of FIG. The direction perpendicular to the plane of the drawing will be described as an X-axis direction.

The exposure apparatus 10 projects a partial image of a circuit pattern drawn on a reflection type reticle R onto a wafer W as a substrate via a projection optical system PO, and
Relative to the projection optical system PO in the one-dimensional direction (here, the Y-axis direction), thereby reducing the entire reduced image of the circuit pattern of the reticle R to each of the plurality of shot areas on the wafer W. Is transferred by the step-and-scan method.

The exposure apparatus 10 includes a light source device 12 including a broadband light source as an exposure light source.
2 has a wavelength of 1 in addition to the EUV light EL1 as the exposure light.
UV light EL2 of about 00 to 400 nm and wavelength of 40
Visible light AL of about 0 to 700 nm is also emitted. The ultraviolet light EL2 and the visible light AL correspond to the light of the non-exposure wavelength. EUV light EL1, ultraviolet light EL2 and visible light AL
The light is emitted horizontally (coaxially) along the Y direction from the same position in the light source device 12. Then, the exposure apparatus 10 reflects the EUV light EL1 and the like from the light source device 12 and impinges on the pattern surface (the lower surface in FIG. 1) of the reticle R at a predetermined incident angle θ (θ is about 50 mrad here). Mirror M (part of the illumination system) that bends so as to make the reticle R, a reticle stage RST as a mask stage that holds the reticle R, and E reflected from the pattern surface of the reticle R
A projection optical system PO composed of a reflection system for projecting the UV light EL1 and the like onto the surface to be exposed of the wafer W, a wafer stage WST as a substrate stage for holding the wafer W, focus sensors (14a, 14b), and a mark detection system And the like.

The light source device 12, as shown in FIG.
A broadband laser plasma light source 16 as an exposure light source,
It comprises a part of the illumination system (PRM, IM). The laser plasma light source 16 is a high-power laser light source 2 such as a YAG laser or an excimer laser excited by a semiconductor laser.
0, a condenser lens 22 for condensing the laser beam L from the high-power laser light source 20 at a predetermined converging point, and an EUV light generating substance 24 such as a copper tape disposed at the converging point. ing.

Here, the mechanism of the generation of the EUV light will be briefly described. The laser light L from the high-power laser light source 20 is applied to the EUV light generating substance 24 disposed at the converging point of the converging lens 22. And this EUV light generating substance 24
Becomes high temperature by the energy of the laser light, is excited into a plasma state, and emits EUV light EL1, ultraviolet light EL2, visible light AL, and other wavelength light as exposure light when transitioning to a low potential state.

Since the EUV light EL1 and the like generated in this manner diverge in all directions, a parabolic mirror PRM is provided in the light source device 12 for the purpose of condensing the light. The EUV light EL1 and the like are condensed by the mirror 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. In the EUV light reflecting layer,
The ultraviolet light EL2 having a wavelength of about 100 nm or more and the visible light AL are simultaneously reflected. 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 the EUV light reflecting layer formed on the surface of the parabolic mirror PRM, only a light of a specific wavelength is reflected by using a multilayer film in which two kinds of substances are alternately laminated. For example, it is known that when dozens of layers of molybdenum Mo and silicon Si are alternately coated, EUV light having a wavelength of about 13 nm is selectively reflected. When molybdenum Mo and beryllium Be are alternately coated in several tens of layers, a wavelength of about 11 n
m EUV light is selectively reflected.

EUV generated from EUV light generating substance 24
Of the light, light having a wavelength that is 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 EL1, the ultraviolet light EL2, and the visible light AL converted into parallel light by the parabolic mirror PRM are parallel lights having a circular cross section perpendicular to the optical axis and uniform intensity distribution.

The light source device 12 further includes an illumination mirror IM that reflects the EUV light EL1 and the like converted into the parallel light and deflects the light toward the folding mirror M in FIG.
A wavelength selector 30 is provided on the rear side of the illumination mirror IM in the traveling direction of the EUV light EL1 and the like (right side in FIG. 2). The wavelength selection device 30
Optical filters 30a, 30b alternately arranged in the optical path of light from the illumination mirror IM, an EUV light selection plate 30c (not shown), and an optical filter 30a, 30b, or EUV according to a command from a main controller 80 described later. Light selection plate 30c
And a drive motor 30d for selectively arranging on the optical path. The optical filter 30a allows only the visible light AL to pass through the light from the illumination mirror IM, and the optical filter 30b allows only the ultraviolet light EL2 to pass therethrough.
The optical filters 30a and 30b are formed by forming an interference filter for a wavelength corresponding to, for example, a glass substrate.

Further, the EUV light selection plate 30 c
It is provided for the purpose of cutting off the L2 and the visible light AL and passing only the EUV light EL1. This is because an EUV reflective film composed of a multilayer film has a very sharp wavelength selectivity with respect to wavelengths near EUV light and selectively reflects only specific wavelengths used for exposure, such as visible light and ultraviolet light. Will be similarly reflected. If this is guided to the reticle R or the projection optical system PO at the time of exposure, extra energy causes the mirrors (which will be described later) constituting the reticle R or the projection optical system PO to generate heat, or in the worst case, Unnecessary light may be transferred onto the wafer W to cause deterioration of an image. Therefore, an attempt is made to prevent such a situation from occurring.

As shown in FIG. 2, the illumination mirror IM has a curved surface on the side irradiated with the EUV light EL1 and the like, and two types of substances are alternately laminated on the curved surface (for example, as shown in FIG. 2). A reflective layer composed of a multilayer film formed by coating several tens of layers of molybdenum Mo and silicon Si) is formed, and the EUV light EL1, the ultraviolet light EL2, and the visible light AL reflected by the reflective layer are each just elongated on the reticle R. It is designed to be slit-shaped.

An illumination area IA (an illumination area having a shape obtained by extracting a part of the illumination area on the ring) having a predetermined area, which will be described later, has a predetermined area and illuminates the pattern surface of the reticle R in the vertical direction in FIG. Corresponding to the direction orthogonal to the longitudinal direction, the pattern surface of reticle R is just the focal plane. In this case, since the light emission source of the EUV light EL1 or the like has a finite size, even if the pattern surface of the reticle R is a focal plane, the EUV light EL1 or the like is about 1 mm to 10 mm on the focal plane. Have a width. 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.

FIG. 3 shows a state where the light source device 12 shown in FIG. 2 is viewed from the −Y direction side (left side in FIG. 2). In FIG. 3, the folding mirror M of FIG. Although the reflection surface of the illumination mirror IM is not shown in FIG. 3, the reflection surface has a rectangular shape when viewed from the back side of the paper surface of FIG. That is, in FIG.
In FIG. 3, which is the left side view, since the shape is rectangular, the reflection surface of the illumination mirror IM has the same shape as a part of the inner peripheral surface of the cylinder. In this case, the EUV light EL1 and the like are converged in the plane of FIG. 2 but remain parallel light in the plane of FIG. 3, so that the length in the left-right direction in FIG. In the longitudinal direction. In addition,
As described above, since the size of the light source is finite as described above, the spatial coherency is not always 0.

Returning to FIG. 1, reticle stage RST is
Although not shown in FIG. 1, as shown in FIG. 4, the reticle is actually arranged on a reticle stage base 32 arranged along the XY plane, and is provided by a magnetic levitation type two-dimensional linear actuator 34. It is levitated and supported on the stage base 32. Reticle stage RST
Is driven by a magnetic levitation type two-dimensional linear actuator 34 in the Y direction at a predetermined stroke, and is also driven in a small amount in the X direction and the θ direction (the rotation direction around the Z axis). Also, reticle stage RST
Is configured to be able to be driven by the two-dimensional linear actuator 34 in a small amount in the Z direction and the tilt direction with respect to the XY plane.

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, and a reticle stage RST is controlled by controlling a current flowing through a coil 34a by a main controller 80 described later.
Is performed in the six-dimensional direction.

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 the peripheral portion of the reticle holder RH, as shown in FIG.
And a temperature control unit 35 provided inside the stage 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 exposure apparatus 10 of the present example is actually housed in a vacuum chamber (not shown) and cannot use a vacuum chuck type reticle holder because the EUV light EL1 is used as exposure light. . The material of the reticle holder RH is a conventional DU using low-expansion glass, ceramic, or the like as exposure light using conventional deep ultraviolet light.
Objects used in the V 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 system using an exchanger can be adopted.

A row of pixels elongated in a non-scanning direction (X direction) perpendicular to the scanning direction is provided at a position separated from the reticle R on the bottom surface of the reticle stage RST in the scanning direction (Y direction). A one-dimensional image sensor 82 having a light receiving portion 82a (see FIG. 5) and having sensitivity to the visible light AL is arranged, and an image signal of the image sensor 82 is supplied to the main controller 80. The height of the light receiving surface of the image sensor 82 is set to be the same as the height of the pattern surface of the reticle R. Furthermore,
As shown in FIG. 6, a point-like reflecting film 83 that reflects the visible light AL at the same height as the pattern surface is provided at a position separated from the reticle R on the bottom surface of the reticle stage RST in the Y direction.
The reference member 83 on which a is formed is fixed. The point-like reflecting film 83a is used as a point light source for the visible light AL when adjusting the optical system.

Referring back to FIG. 4, the reticle stage RST
The side surface on the Y direction side is mirror-finished and has a reflection surface 40a that reflects light in the visible region. Although not shown in FIG. 4, −X of reticle stage RST is used.
The side surface on the direction side is also mirror-finished to form a reflection surface for light in the visible region. Then, this exposure apparatus 1
At 0, the position of the reticle stage RST in the XY plane is managed by an interferometer system that irradiates the measurement surface with the measurement beam on the reflection surface 40a and the like, similarly to the conventional exposure apparatus of the DUV light source.

On the surface (pattern surface) of reticle R, E
A reflection film that reflects the UV light EL1 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. E on such a reflective film
An original pattern on the reticle R is formed by applying a substance that absorbs UV light on one surface and patterning it. When a reflective object such as a multilayer film is patterned, it is impossible to repair it when it fails, whereas a method of providing an absorbing layer (absorbing film) and performing patterning makes it possible to redo, so that the pattern can be repaired. . Since most existing substances do not reflect EUV light, they can be used for absorbing layers. In this example, a laser interferometer is used to measure the Z direction position of the reticle R,
The absorption layer is formed of a substance that can obtain the same level of reflectance with respect to the measurement beam (light in the visible region) from these laser interferometers as the reflection layer (reflection film). In addition, the criteria for selecting the material for forming the absorption 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 FIG.
A. The hatched arc-shaped area is the arc-shaped illumination area IA irradiated with the EUV light EL1 as the exposure light. Here, the reason why the exposure is performed using the arc-shaped illumination area IA is that only the area where the various aberrations of the projection optical system PO described later are the smallest can be used. Reticle alignment marks RM1 to RM6 as alignment marks are formed at predetermined intervals along the Y direction at both ends in the X direction of the pattern area PA of the reticle R.
Reticle alignment marks RM1, RM4, RM2
, RM5 and 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, batch exposure (stationary exposure) is impossible, and therefore, in this example, scanning exposure is performed as described later.

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, ceramics, a silicon wafer, or the like 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 cases,
Thermal expansion occurs in the reticle R and the reticle holder RH due to a temperature rise due to exposure light exposure or the like. However, if the two materials are the same, the reticle R and the reticle holder RH expand by the same amount. (Stress) does not work. The present invention is not limited to this, and 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 reticle R, and silicon carbide (Si) is used for reticle holder RH.
It is conceivable to use C). 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 example, for this reason, a silicon wafer is used as the material of the reticle R, and the reticle holder is formed of SiC.

Returning to FIG. 1, a movable blind 42 and a slit plate 44 as a field stop are arranged below the reticle R (on the incident side of the EUV light EL1 and the like) in proximity to the reticle R. More specifically, the movable blind 42 and the slit plate 44 are actually arranged inside the reticle stage base 32 as shown in FIG.

In FIG. 4, the slit plate 44 defines an arc-shaped illumination area IA (see FIG. 5), and may be fixed to the projection optical system PO. The slit plate 44 is configured to be drivable by a driving mechanism 46 as a switching mechanism including a motor and the like. The slit plate 44 has an arc-shaped illumination region I on the reticle R to which the EUV light EL1 as the exposure light is irradiated.
A, and the alignment marks R formed on both sides of the pattern area PA of the reticle R in FIG.
M1 and RM4 (or RM2 and RM5, or R
(M3 and RM6)
And a slit. The drive mechanism 46 switches the slit plate 44 so that the illumination area IA is irradiated at the time of exposure according to an instruction from a main controller 80 (see FIG. 8) described later, and aligns the reticle R (alignment).
Occasionally, the slit plate 44 is switched so that the EUV light EL1 is applied to the region including the alignment mark.

In FIG. 4, the movable blind 42 is
When it is not desired to transfer the redundant circuit pattern drawn in the same reticle R to the wafer W, this is to prevent the redundant circuit portion from being included in the illumination area IA. In response to an instruction from the device 80, the drive mechanism 46 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 movable blind 42 may be started to scan after the reticle R starts to scan in the same manner as the reticle R, or may start to move in accordance with the arrival of the target pattern to be hidden.

Referring back to FIG. 1, as the projection optical system PO, as described above, a reflection system consisting only of a reflection optical element (mirror) is used, and here, an optical system having a projection magnification of 1/4 is used. Have been. Therefore, EUV including the pattern information reflected by the reticle R and drawn on the reticle R
The light EL1 is reduced to a quarter by the projection optical system PO and is irradiated onto the wafer W.

Here, the projection optical system PO will be described in more detail with reference to FIG. In FIG. 6, the projection optical system PO includes a first mirror M1, a second mirror M2, a third mirror M3, and a fourth mirror M1, which sequentially reflect the EUV light EL1, the ultraviolet light EL2, and the visible light AL reflected by the reticle R. Mirror M
4, a total of four mirrors (reflection optical elements), and a lens barrel PP holding these mirrors M1 to M4. The reflecting surfaces of the first mirror M1 and the fourth mirror M4 have an aspherical shape, the reflecting surface of the second mirror M2 is a flat surface, and the reflecting surface of the third mirror M3 is a spherical shape. Each reflecting surface is about 1/50 of the exposure wavelength with respect to the design value.
And a processing accuracy of 1/60 or less is realized, and there is only an error of 0.2 to 0.3 nm in RMS value (standard deviation). The material of each mirror is low expansion glass or metal, and a reflection layer for EUV light EL1 is formed on the surface by a multilayer film in which two kinds of substances similar to the reticle R are alternately stacked.

In this case, as shown in FIG. 6, the fourth mirror M4 is provided with a through hole so that the light reflected by the first mirror M1 can reach the second mirror M2.
Similarly, a through hole is provided in the first mirror M1 so that the light reflected by the fourth mirror M4 can reach the wafer W. Of course, instead of providing a through hole, the outer shape of the mirror may be formed to have a notch through which a light beam can pass.

When the exposure is performed using the EUV light EL1, 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 exposure light irradiation. Therefore, in the present embodiment, a cooling device for cooling the lens barrel PP is provided while connecting the mirrors M1 to M4 and the lens barrel PP holding the mirrors M1 to M4 with a heat pipe HP. That is, the lens barrel PP has a double structure of the inner mirror holding portion 50 and the cooling jacket 52 mounted on the outer peripheral portion thereof.
A helical pipe 58 for flowing from the 4 side to the outflow tube 56 side 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.

For this reason, in the projection optical system PO of this embodiment, the mirrors M1 and M1 are irradiated by the EUV light EL1 as the exposure light.
Even if heat energy is given to M2, M3, and M4, heat exchange is performed with the lens barrel PP whose temperature is adjusted to a constant temperature by the heat pipe HP, and the mirrors M1, M2, M3, M
4 is cooled to the constant temperature. In this case, in this example, as shown in FIG. 6, for the mirrors M1, M2, M4, etc., not only the back side but also the front side (reflection side) of the heat pipe are exposed to the heat pipe. Since the HP is attached, the cooling of each mirror is performed more effectively than when only the back surface is cooled. Note that the back side of the third mirror M3 and the first
Needless to say, the heat pipe HP on the front surface side of the mirror M1 reaches the inner peripheral surface of the lens barrel PP in the depth direction of the paper surface of FIG. Note that the appearance of the lens barrel PP has a quadrangular prism shape.

Returning to FIG. 1, wafer stage WST
It is arranged on a wafer stage base 60 arranged along the Y plane, and is 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 by the two-dimensional linear actuator 62 in a predetermined stroke in the X direction and the Y direction, and is also driven in a small amount in the θ direction (rotation direction around the Z axis).
The wafer stage WST is configured to be able to be driven by a minute amount in the Z direction and the tilt direction with respect to the XY plane by a magnetic levitation type two-dimensional linear actuator 62.

A permanent magnet (not shown) is provided on the bottom surface of wafer stage WST. The permanent magnet and a coil (not shown) stretched on wafer stage base 60 in a two-dimensional XY direction provide the magnet. Floating type 2
A two-dimensional linear actuator 62 is configured, and the position and orientation of wafer stage WST in the six-dimensional direction are controlled by controlling the current flowing through the coil by main controller 80 described later.

A wafer holder (not shown) of an electrostatic chuck type is mounted on the upper surface of wafer stage WST, and wafer W is held by suction by this wafer holder. In addition, the side surface of wafer stage WST on the + Y direction side in FIG. 1 is mirror-finished to form a reflection surface 74a that reflects light in the visible region. Although not shown in FIG. 1, mirror processing is also performed on the side surface on the −X direction side of wafer stage WST to form a reflection surface for light in the visible region. In the exposure apparatus 10, the position with respect to the projection optical system PO is accurately measured by an interferometer system that irradiates a measurement beam to the reflection surface 74a and the like.

At one end of the upper surface of wafer stage WST, the position where the pattern drawn on reticle R is projected onto the surface of wafer W and the measurement of the relative positional relationship of alignment optical system ALG (so-called baseline measurement), etc. The aerial image measuring instrument FM1 for the EUV light EL1 for performing the above is provided (see FIG. 1). This aerial image measuring instrument FM1 corresponds to a reference mark plate of a conventional DUV exposure apparatus. In addition, near the wafer W on the wafer stage WST, an aerial image measuring instrument FM2 for visible light AL is also arranged.

FIGS. 7A and 7B show the EUV light EL1.
A plan view and a longitudinal sectional view of an aerial image measuring instrument FM1 are shown. As shown in these figures, a slit SLT as an opening is provided on the upper surface of the aerial image measuring instrument FM1.
1 and SLT2 are formed. These slits SL
T1 and SLT2 are patterned on the EUV light reflection 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.

Openings 66a and 66 are formed on the upper surface plate of wafer stage WST below slits SLT1 and SLT2.
b are formed, and the openings 66a, 66a
A photoelectric conversion element PM such as a photomultiplier is arranged inside wafer stage WST facing wafer 6b. Therefore, when the aerial image measuring instrument FM1 is irradiated with the EUV light EL1 from above via the projection optical system PO,
The EUV light transmitted through the slits SLT1 and SLT2 reaches the fluorescent substance 63, and the fluorescent substance 63 emits light having a longer wavelength than the EUV light. 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. Here, the positional relationship between the slits SLT1 and SLT2 is determined by the reticle alignment marks RM1 and RM4 (RM2 and RM5 or RM4) of FIG.
3 and RM6), and the reticle alignment marks RM1 and RM4 can be simultaneously measured through the slits SLT1 and SLT2 during reticle alignment described below.

Next, referring to FIG. 6, wafer stage WS
As shown by cutting out a part of T, aerial image measuring instrument FM2 for visible light AL emits visible light fixed to the upper plate of wafer stage WST so that its surface is the same as the surface of wafer W. It is a transparent glass substrate. This aerial image measuring instrument F
An imaging lens 85 and a two-dimensional CCD image sensor 86 having sensitivity to visible light are arranged on the bottom surface of M2 via an opening, and visible light AL formed on the surface of the aerial image measuring instrument FM2.
Is formed on the imaging surface of the imaging element 86 via the imaging lens 85. Image sensor 8
6 is also supplied to the main controller 80.

Next, the position measuring system of the exposure apparatus of this embodiment will be described. The positions of the reticle stage RST in the X direction, the Y direction, and the rotation direction in FIG. 1 are measured by the laser interferometer as described above. In this case, the projection optical system P
The laser beam RIFY1R supplied to the reference mirror 72a provided on the side surface of O and the laser beam RIFY1M supplied to the side surface 40a of the reticle stage RST, the Y coordinate of the reticle stage RST based on the position of the projection optical system PO. Is measured, and similarly, the X coordinate and the rotation angle of the reticle stage RST are measured based on the position of the projection optical system PO. Similarly, wafer stage W
The positions of the ST in the X, Y, and rotation directions are also measured by the laser interferometer with reference to the position of the projection optical system PO. The laser interferometer for reticle stage RST and the laser interferometer for wafer stage WST constitute interferometer system 70 in FIG. 8, and the measured values of interferometer system 70 are supplied to main controller 80. I have.

Further, in FIG. 1, a barrel PP of a projection optical system PO which is a reference for all measurements of the above interferometer system.
Is provided with a reticle surface measurement laser interferometer RIFZ for measuring the position of the reticle R in the Z direction. In the laser interferometer RIFZ, actually, the interferometers having the same configuration are fixed at three locations around the lens barrel PP at predetermined intervals, but in FIG.
It is shown as

The measurement beam from these laser interferometers RIFZ is applied to the pattern surface of the reticle R at a predetermined incident angle θ via the turning mirror M, and is irradiated with the EUV light EL1 or the like, that is, an arc-shaped illumination region. Incoming light path and outgoing light path (reflection light path) of EUV light EL1 etc. at three different points in the IA
The light is projected onto the pattern surface of the reticle R through an optical path in the Z direction located at the center of the reticle R (see FIGS. 1 and 4). For this reason, the laser interferometer RIFZ is obliquely incident on the pattern surface of the reticle R at a predetermined incident angle θ,
High accuracy (for example, several nm to 1 nm or less) without affecting the EUV light EL1 or the like reflected at the same exit angle as the incident angle, and without affecting the interferometer measurement beam by the EUV light EL1 or the like. ), The position of the reticle R in the Z direction can be measured.

Here, as the laser interferometer RIFZ, a type having a built-in reference mirror in which a reference mirror (not shown) is built in the main body is used, and the position of the reference mirror is used as a reference to measure the measurement beam on the reticle R. The irradiation position in the Z direction
Measure each. In this case, the measurement beams from the first to third laser interferometers RIFZ are projected onto the points P1, P2, and P3 in the irradiation area IA shown in FIG. 5, respectively. Point P2 is the illumination area IA
, That is, a point on the central axis in the X direction of the pattern area PA and a central point in the Y direction of the illumination area IA, and a point P1,
P3 is located symmetrically with respect to the central axis.

As shown in FIG. 8, the measured values of the three-axis reticle surface measuring laser interferometer RIFZ are also input to the main controller 80. Reticle stage RS via magnetic levitation type two-dimensional linear actuator 34 based on measured values
T, that is, the Z position and the tilt angle of the reticle R are corrected.

On the other hand, the Z direction position of the wafer W with respect to the lens barrel PP in FIG. 1 is measured by oblique incident light type focus sensors (14a, 14b) fixed to the projection optical system PO. ing. This focus sensor (1
4a, 14b) are fixed to a column (not shown) holding the lens barrel PP, and a light transmitting system 14a for irradiating the detection beam FB from an oblique direction to the surface of the wafer W; And a light receiving system 14b that receives the detection beam FB reflected by the W surface. 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. The focus sensors (14a, 14b)
It is important to be fixed integrally with P. The focus sensors (14a, 14b) are shown as the focus sensor 14 in FIG. 8, and the main controller 80 controls the wafer through the magnetic levitation type two-dimensional linear actuator 62 based on the measurement value of the focus sensor 14. The stage WST, that is, the Z position and the tilt angle of the wafer W are corrected.

The main controller 80 shown in FIG. 8 is constituted by a microcomputer (or workstation), and has a built-in memory (RAM) 81 as a storage device. In this example, a driving device is constituted by the main control device 80 and the magnetic levitation type two-dimensional linear actuators 34 and 62. Next, an example of an operation at the time of assembly adjustment of the exposure apparatus of this embodiment will be described with reference to a flowchart of FIG. 1 and 2, a parabolic mirror PRM, an illumination mirror IM, a folding mirror M, a movable blind 42,
An illumination system is composed of the slit plate 44 and the slit plate 44. That is, the illumination system of this example is a reflection system in which all optical elements are mirrors, and similarly, the projection optical system PO as a projection system is also a reflection system. Therefore, in the illumination system and the projection optical system PO, chromatic aberration does not occur for any of the EUV light EL1, the ultraviolet light EL2, and the visible light AL. And a rough adjustment at the time of assembling adjustment of the projection optical system PO. However, the adjustment of the illumination system and the projection optical system PO using the visible light AL can also be performed, for example, at the time of regular maintenance of the exposure apparatus of this example.

Then, as shown in FIGS. 1 and 2, after the laser plasma light source 16 as the exposure light source, the illumination system, and the projection optical system PO are roughly assembled, in step 101 of FIG. Of the light from the light source device 12 via the second wavelength selection device 30, only the visible light AL is allowed to pass to the return mirror M side. Thereafter, dust is removed around the exposure apparatus of FIG. 1, the temperature and humidity are set to predetermined standard conditions, and air is supplied at an atmospheric pressure equal to the surrounding atmospheric pressure. Then, the operator roughly adjusts the positional relationship between the illumination system and the projection optical system PO. At this time, the worker first looks at the visible light AL, so that the visible light A
The positional relationship between the laser plasma light source 16 of FIG. 2 and the parabolic mirror PRM in the illumination system, the illumination mirror IM with respect to the parabolic mirror PRM, and the folding mirror M so that L travels along the optical path substantially as designed. Adjust the positional relationship, etc. At the time of such adjustment, adjustment of a support member of each mirror, replacement of a washer for changing the attitude of each mirror, and the like may be performed. In addition, adjustment of the movable blind 42, the slit plate 44, and the like is also performed. As a result, a region corresponding to the arc-shaped illumination region IA in FIG. 5 on the reticle stage RST is irradiated with the visible light AL.

Thereafter, the reticle stage RST is moved at a low speed in the Y direction in FIG.
, The light receiving portion 82a of the imaging element 82 is
In the Y direction. Thus, the light receiving section 82a
Stage crosses the illumination area IA, the reticle stage RS
The main controller 80 captures the image signal of the image sensor 82 at a high sampling rate in accordance with the Y coordinate of T. Main controller 80 processes the series of imaging signals and measures the shape of illumination area IA in FIG. Based on the measurement result, the operator adjusts the illumination system, the position of the slit plate 44, and the like so that the illumination area IA has an arc shape having a predetermined width H.

Next, in order to roughly adjust the projection optical system PO, the reticle stage RST is driven in the Y direction in FIG.
Move a. Thereby, wafer stage WST
A reduced image (point image) of the point-like reflective film 83a is projected on the upper surface via the projection optical system PO. Then, by driving wafer stage WST, aerial image measuring instrument FM2 is moved to include the point image, and an enlarged image of the point image is captured via image sensor 86. Then, the operator adjusts the position of each mirror of the projection optical system PO so that the enlarged image is in a desired state.

At this time, the wafer stage WST is
The projection optical system PO may be driven in the direction to capture enlarged images of the point images at a plurality of positions in the Z direction, and coarse adjustment of the projection optical system PO may be performed based on a change in the plurality of enlarged images. By observing a point image with such defocusing, the wavefront aberration of the projection optical system PO can be known, for example, as disclosed in US Pat. No. 4,309,602.

Although the point image is observed in this example, a periodic reflection pattern is formed on the reticle stage RST instead of the dot-like reflection film 83a, and the periodic reflection pattern is formed. An image by the visible light AL may be observed. Instead of simply observing an enlarged image, aerial image measurement may be performed using a knife edge or the like. When performing the rough adjustment as described above, it is not necessary to use a separate light source for adjustment, and therefore, the rough adjustment can be performed quickly and efficiently.

Thus, the illumination system and the projection optical system P
After the coarse adjustment of O is completed, the process proceeds to step 104 in FIG. 9, and only the EUV light EL1 out of the light from the light source device 12 using the wavelength selection device 30 in FIG.
To the side. Then, in step 105,
By closing the chamber in which the exposure apparatus is housed and exhausting the air around the exposure apparatus, EU
The optical path of the V light EL1 is set to a predetermined level or less (the EUV light EL
(A decay rate of 1 is not more than a predetermined value). In a subsequent step 106, the operator causes the exposure apparatus to perform, for example, a test print or the like from outside the chamber, so that the illumination system and the projection optical system P
Make a final adjustment of O. For example, reticle stage RS
The final adjustment is performed by the test print with the T and the wafer stage WST stationary and the test print with the two stages RST and WST synchronously scanned so that a predetermined exposure image can be obtained. At the time of optical adjustment, air is appropriately supplied into the chamber.

At this time, in this example, both the illumination system and the projection optical system PO are reflection systems and have no chromatic aberration, and the light source device 12
Is emitted on the same optical path as the EUV light EL1, the result of the coarse adjustment in step 103 is
This is equivalent to the adjustment result when the UV light EL1 is used. Therefore, since the adjustment error at the start of the final adjustment in step 106 is small, the final adjustment can be performed in a very short time. That is, assembly and adjustment of the illumination system and the projection optical system PO as a whole can be performed in a short time and with high accuracy.

The observation of the point image and the like are performed by the light source device 1.
2 may be performed using the ultraviolet light EL2.
In the above embodiment, the ultraviolet light or the visible light from the laser plasma light source 16 is used for adjusting the optical system on the exposure apparatus. However, the adjustment of the optical system is not necessarily performed on the exposure apparatus. The adjustment may be performed on a predetermined tool table. That is, coarse adjustment of the illumination system or the projection optical system PO may be performed by visible light or ultraviolet light on the tool table, and then adjustment may be performed using the exposure light before transfer to the exposure apparatus. The adjustment may be performed only with visible light, and then moved to an exposure apparatus. In the exposure apparatus,
Adjustment with exposure light may be performed from the beginning, or readjustment with visible light or ultraviolet light may be performed.

Next, a description will be given of the operation of the exposure step for the second and subsequent layers (second layer) by the exposure apparatus 10 according to the present embodiment configured as described above. First, the EUV light EL1 is selected from the light from the light source device 12 using the wavelength selection device 30 in FIG.
The light emission of No. 6 is not performed until the start of reticle alignment or exposure of the wafer. In FIG. 1, 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. Further, a wafer W coated with a resist sensitive to EUV light EL1 is moved by wafer transfer system (not shown) and a wafer transfer mechanism (not shown) on wafer stage WST.
It is placed on T.

Next, main controller 80 shown in FIG. 8 selects a predetermined wafer alignment mark (one wafer alignment mark) from among wafer alignment marks attached to each shot area of wafer W on wafer stage WST. (One or a plurality of shots) is detected using the alignment optical system ALG while sequentially moving the wafer stage WST. When detecting this mark position, main controller 80 controls the Z position on the surface of wafer W to be the focal position of alignment optical system ALG. When the detection of the position of the wafer alignment mark of the sample shot is completed, main controller 80 uses the data to determine the minimum 2nd position disclosed in, for example, JP-A-61-44429.
The arrangement coordinates of all shot areas on the wafer W are obtained using a statistical method using a multiplication method (hereinafter, this alignment method is referred to as “EGA (Enhanced Global Alignment)”). Alternatively, the main controller 80 uses, for example, Japanese Patent Application Laid-Open No.
No. 96, the array coordinates of all shot areas on the wafer W and the deformation amount including the magnification of each shot are obtained using a statistical method using the least squares method.
This alignment method is called “multipoint EGA in shot”.

When the alignment measurement is completed in this way, the shot interval, which can be understood from the above EGA results,
Alternatively, the change in the magnification of the shot (X,
Y scaling) is calculated, and the projection magnification is controlled so that the size of the reticle pattern image in the X direction (second direction) accurately matches the size of the shot area on the wafer W according to the magnification change amount. The magnetic levitation type two-dimensional linear actuator 34 is calculated.
The reticle R is driven in the Z direction (up-down direction) by the calculated amount via. For example, 10 ppm from a predetermined magnification
In the case of enlargement, the reticle R is projected by the projection optical system P by 40 μm.
Drive in the direction away from O.

The Z drive of the reticle R causes a change in the projection magnification and a displacement of the projection area of the reticle pattern image, so that the main controller 80 measures the baseline and the projection magnification as follows. I do. In the main controller 80, the slit plate 44 is driven via the driving mechanism 46 shown in FIG.
Is switched to a position where the exposure illumination light EL can irradiate the alignment mark. 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, and reticle alignment marks RM1 and RM4 drawn on reticle R in FIG. , RM2, RM5,
RM3 and RM6 are sequentially irradiated with EUV light EL1 two by two, and reticle alignment marks RM1 and RM
4. The projected images of RM2, RM5, RM3, and RM6 on the surface of the wafer W are converted into slits SLT1 and SLT1 of the aerial image measuring instrument FM1.
By detecting the reticle pattern image via the SLT 2, the projection position of the reticle pattern image on the wafer W is obtained. That is, reticle alignment is performed.

When detecting the projected image using the aerial image measuring device FM1 for the reticle alignment, the main controller 80 blurs the image obtained by the aerial image measuring device FM1 by the Z drive of the reticle R. An offset corresponding to the Z drive amount of the reticle R is given to the focus sensors (14a, 14b) so that the surface of the aerial image measuring instrument FM1 is controlled to the focal position of the projection optical system PO so that the reticle R does not occur. Specifically, when reticle R is driven in a direction away from projection optical system PO by 40 μm in main controller 80, the projection magnification is ４, and therefore 40 × 1/16 = 2.5 μm
Is given to the focus sensor 14, and based on the output of the focus sensor 14, the wafer stage WST
Feedback control of the Z position of
The distance m is closer to the projection optical system PO.

Next, in main controller 80, wafer stage W is moved via magnetic levitation type two-dimensional linear actuator 62 so that slit SLT1 or SLT2 of aerial image measuring instrument FM1 is positioned immediately below alignment optical system ALG.
While moving ST, the Z position of the surface of the aerial image measurement device FM1 is adjusted to the focal position of the alignment optical system ALG. Then, main controller 80 indirectly adjusts the projection position of the pattern image of reticle R onto wafer W based on the detection signal of alignment optical system ALG and the measurement value of interferometer system 70 at that time. ALG
Is obtained, that is, the base line amount is obtained, and the calculation result is stored in the memory 81. It should be noted that another reference mark may be formed at an intermediate position between the slits SLT1 and SLT2 of the aerial image measuring instrument FM1, and the reference mark may be detected by the alignment optical system ALG to determine the baseline amount. In such a case, the alignment optical system ALG
, And the baseline amount can be obtained almost accurately based on the design value of the baseline amount.

In main controller 80, at the time of the above reticle alignment, reticle alignment arranged in the non-scanning direction on reticle R detected via slits SLT1 and SLT2 of aerial image measuring device FM1. Marks RM1 and RM4 (RM2 and RM5 or RM
3 and RM6), the projection magnification is determined based on the interval between the projected images on the wafer W surface.

Next, the main controller 80 sets the projection magnification adjustment residual error to an allowable value (for example, 0.2 ppm) with respect to the target magnification adjustment amount, 10 ppm in the above example, based on the result of the above magnification measurement. ) Judge whether it is below. If this determination is denied, that is, if the residual error in the adjustment of the projection magnification exceeds the allowable value, the main controller 80 returns to the step of driving the reticle R in order to reset the projection magnification, and again executes the reticle. After driving R in the Z direction, the above processing and judgment are repeated. On the other hand, if the determination is affirmative, that is, if the adjustment residual error of the projection magnification is equal to or smaller than the allowable value, the main controller 80 irradiates the slit plate 44 with the EUV light EL1 to the illumination area IA via the drive mechanism 46 After switching to the position to be performed, the process proceeds to the next step.

In this step, main controller 80 performs step-and-scan exposure using EUV light EL1 as exposure light as follows. That is, the main controller 80 monitors the position information from the interferometer system 70 in accordance with the position information of each shot area on the wafer W obtained above, and the wafer stage WST via the magnetic levitation type two-dimensional linear actuator 62. Is positioned at the scanning start position of the first shot, the reticle stage RST is positioned at the scanning start position via the magnetic levitation type two-dimensional linear actuator 34, and the scanning exposure of the first shot is performed. At the time of this scanning exposure, the main controller 80 controls the magnetic levitation type two-dimensional linear actuator 34,
The speed of the two stages is controlled so that the speed ratio between the reticle stage RST and the wafer stage WST accurately matches the projection magnification of the projection optical system PO via 62, and the speed ratio between the two stages is synchronized at a constant speed. To perform exposure (transfer of the reticle pattern). Thereby, the projection magnification of the reticle pattern image in the scanning direction (Y direction) during the scanning exposure is controlled. 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 performed on the Y axis. When the exposure is performed in the direction from the minus side to the plus side, the exposure of the second shot is performed in the direction from the plus side to the minus side. That is, an alternate scan is performed.
In this way, 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. As described above,
A series of processing steps for one wafer W by the exposure apparatus 10 ends.

According to the present embodiment, the laser plasma light source 16 and the illumination system (PRM, IM, M) emit light of wavelength 5
The reticle R is irradiated with EUV light EL1 having a wavelength of 〜20 nm, and a plurality of reflective optical elements (M1
To M4), it is possible to transfer a very fine pattern, for example, a 100 nm L / S pattern with high accuracy.

In the above embodiment, the EUV light E
Exposure is performed using L1. This exposure is performed, for example, when exposing a critical layer that requires the highest resolution on a wafer. On the other hand, for example, a rough layer does not necessarily require a high resolution enough to use the EUV light EL1. Therefore, when performing exposure on the rough layer, the ultraviolet light EL2 from the light source device 12 is selected via the wavelength selection device 30 in FIG.
Exposure may be performed by using. The lighting system of this example,
And the projection optical system PO is a reflection system, so that the ultraviolet light E
Since chromatic aberration does not occur even when L2 is used, exposure can be performed at a required resolution using the illumination system and the projection optical system PO. Thus, the exposure apparatus of the present example
It can be used for both critical and rough layers.

In the above embodiment, the EUV light E
A laser plasma light source 16 is used as a broadband light source as an exposure light source that generates ultraviolet light EL2 and visible light AL in addition to L1. In addition, as the broadband light source, a laser light source that generates light of a plurality of wavelengths, or SOR
(Synchrotron Orbital Radiation) ring or the like can be used.

Further, in the above embodiment, the present invention is applied to a scanning exposure type and reduction projection type exposure apparatus.
The present invention can also be applied to a case where an illumination system is adjusted in a proximity type exposure apparatus that transfers a reticle pattern directly onto a wafer without using a projection optical system by using EUV light, for example. In the above embodiment, the EUV light EL1 as the exposure light is light in the soft X-ray region, and the fluorescent substance 63 and the thin film of the reflective layer 62 of the EUV light EL1 are formed on the surface of the wafer stage WST. And a photoelectric conversion element PM that photoelectrically converts light emitted by the fluorescent substance 63 when the EUV light EL1 reaches the fluorescent substance 63 via the SLT. Aerial image measuring instrument F
Since M1 is provided, although 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, measurement of an aerial image can be performed using the illumination light for exposure. The projection position of the reticle pattern on wafer stage WST can be easily obtained using aerial image measuring instrument FM1.

In the above embodiment, the slit plate 4
4, the case where the arc-shaped illumination region IA is defined has been described. However, the present invention is not limited to this, and each optical member constituting the illumination optical system is designed so that the illumination light EL has an arc shape. For example, it is not always necessary to provide the slit plate 44 immediately below the reticle R. Further, the positions of reticle alignment marks RM1 to RM6 may be the positions of RM7 to RM12 in FIG. 5 instead of the positions in FIG. In such a case, a slit plate for illuminating only the illumination area IA may be used as the slit plate 44, and the driving mechanism 46 is not required. Alternatively, set the reticle alignment mark to RM
1 to RM12, and all of them may be used.

As described above, the exposure apparatus according to the above embodiment adjusts the illumination system and the projection optical system PO, and connects each component electrically, mechanically or optically. Assembled. Then, the wafer W exposed as described above undergoes a developing process, a pattern forming process, a bonding process, and the like, whereby devices such as semiconductor elements are manufactured.

The present invention is not limited to the above-described embodiment, but can take various configurations without departing from the spirit of the present invention.

[0089]

According to the first, second, or third method of adjusting the exposure apparatus of the present invention, the illumination light for exposure and the exposure light source for generating light of the non-exposure wavelength are used. The adjustment of the internal optical system can be performed in a short time and with high accuracy without using a light source for adjustment.

Then, the illumination light for exposure is extreme ultraviolet light (E
(UV light), when the illumination system is a reflection system, and when the projection optical system is also a reflection system, when the projection optical system is also a reflection system, no chromatic aberration occurs. The internal optical system can be adjusted accurately and efficiently. Further, according to the exposure apparatus of the present invention, the method of adjusting the exposure apparatus according to the present invention can be performed.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram illustrating an example of an exposure apparatus according to an embodiment of the present invention.

FIG. 2 is a diagram showing a light source device 12 in FIG.

FIG. 3 is a left side view of FIG. 2;

FIG. 4 is a partially cutaway view showing in detail a configuration near a reticle stage in FIG. 1;

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

FIG. 6 is a sectional view schematically showing an internal configuration of the projection optical system PO of FIG.

FIG. 7A is a plan view showing an aerial image measuring instrument FM1;
FIG. 7B is a side view in which a part of FIG.

FIG. 8 is a block diagram illustrating a configuration of a control system related to position and orientation control of a wafer (wafer stage) and a reticle (reticle stage).

FIG. 9 is a flowchart showing an example of an operation at the time of assembly adjustment of the exposure apparatus of the embodiment.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 ... Exposure apparatus, 12 ... Light source device (including some illumination systems), 16 ... Laser plasma light source, 30 ... Wavelength selection device, 34 ... Magnetic levitation type two-dimensional linear actuator,
44: slit plate, 62: magnetic levitation type two-dimensional linear actuator, 63: fluorescent substance, 80: main controller, 81: memory, R: reticle, EL1: EUV light as exposure light, EL2: ultraviolet light, AL: visible light, M: folding mirror, PO: projection optical system, WST: wafer stage (substrate stage), ALG: alignment optical system (mark detection system), FM1, FM2: aerial image measuring instrument, R
IFZ: laser interferometer for reticle surface measurement, RST: reticle stage, SLT1, SLT2: slit (opening), PM: photoelectric conversion element

Continued on the front page (72) Inventor Tsuneyuki Hagiwara 3-2-3 Marunouchi, Chiyoda-ku, Tokyo F-term in Nikon Corporation (reference) 5F046 BA04 BA05 CA03 CA08 CB03 CB17 DA12 GA03 GA18 GC03

Claims (15)

[Claims] An exposure light source for generating illumination light for exposure;
An illumination system for irradiating the mask with illumination light from the exposure light source, the method for adjusting an exposure apparatus for transferring the pattern of the mask onto a substrate under the illumination light, wherein the exposure as the exposure light source For the illumination light, and using a broadband light source that generates light of a non-exposure wavelength different from the illumination light wavelength range, when adjusting at least a part of the optical system in the illumination system, from the broadband light source A method for adjusting an exposure apparatus, wherein the emitted light having the non-exposure wavelength is used. 2. An exposure light source for generating illumination light for exposure,
An illumination system for irradiating the mask with illumination light from the exposure light source, the method for adjusting an exposure apparatus for transferring the pattern of the mask onto a substrate under the illumination light, wherein the exposure as the exposure light source When using a broadband light source for generating illumination light and light of a non-exposure wavelength different from the illumination light in a wavelength range, when performing coarse adjustment of at least a part of the optical system in the illumination system, the broadband light source Using the light of the non-exposure wavelength emitted from the light source, and performing the final adjustment of the illumination system, using the illumination light for exposure emitted from the broadband light source. Adjustment method. 3. The exposure apparatus includes a projection system including a reflection system that collects illumination light from the mask and projects an image of a pattern of the mask onto the substrate, and the illumination system and the projection system. The method according to claim 1, wherein when adjusting at least a part of the optical system, light of the non-exposure wavelength emitted from the broadband light source is used.
Or the adjusting method of the exposure apparatus according to 2. 4. The broadband light source generates light having a wavelength in an extreme ultraviolet region as the illumination light for exposure, and generates light having at least one wavelength in an ultraviolet region or a visible region as the light having a non-exposure wavelength. And wherein the illumination system is a reflection system.
4. The method for adjusting an exposure apparatus according to 2 or 3. 5. An exposure light source for generating illumination light for exposure,
An illumination system for irradiating a mask with the illumination light, and a method for adjusting an exposure apparatus including a projection system for projecting a pattern image of the mask onto a substrate, wherein the illumination light for exposure is used as the exposure light source, and When using a broadband light source that generates light of a non-exposure wavelength having a different wavelength range from the illumination light, when adjusting at least a part of the optical system of the projection system,
A method for adjusting an exposure apparatus, comprising using light of the non-exposure wavelength emitted from the broadband light source. 6. After adjusting the optical system using the light of the non-exposure wavelength, readjust the projection system using the illumination light for exposure emitted from the broadband light source. An exposure apparatus adjusting method according to claim 5. 7. The broadband light source generates light having a wavelength in an extreme ultraviolet region as the illumination light for exposure, and generates light having at least one of an ultraviolet region and a visible region as the non-exposure wavelength light. The method according to claim 5, wherein the projection system is a reflection system. 8. The method according to claim 4, wherein the broadband light source is a laser plasma light source, and the exposure illumination light is an extreme ultraviolet light having a wavelength of 5 to 20 nm. 9. When adjusting the optical system using the non-exposure wavelength light, a predetermined gas is supplied to an optical path of the non-exposure wavelength light, and the exposure is performed using the exposure illumination light. 9. The method according to claim 4, wherein, when performing the adjustment, the optical path of the exposure illumination light is substantially evacuated. 10. An exposure apparatus, comprising: an exposure light source for generating illumination light for exposure; and an illumination system for irradiating a mask with illumination light from the exposure light source, and transferring a pattern of the mask onto a substrate. An illumination light for exposure as the exposure light source, and a broadband light source that generates light of a non-exposure wavelength different from the illumination light in a wavelength range, An exposure apparatus comprising a photoelectric detector that detects light having an exposure wavelength. 11. A projection system for converging illumination light from the mask and projecting an image of a pattern of the mask on the substrate, wherein the photoelectric detector passes the projection system after passing through the illumination system. The exposure apparatus according to claim 10, wherein the light having the non-exposure wavelength that has passed through at least a part of the optical systems in the system is detected. 12. An exposure apparatus comprising: an exposure light source for generating illumination light for exposure; an illumination system for irradiating the mask with the illumination light; and a projection system for projecting a pattern image of the mask onto a substrate. An illumination light for exposure as the exposure light source, and a broadband light source that generates light of a non-exposure wavelength having a wavelength range different from that of the illumination light, wherein the non-exposure wavelength of the An exposure apparatus comprising a photodetector for detecting light. 13. The illumination system and the projection system each include a reflection system, a stage system for moving the mask and the substrate in a predetermined direction in synchronization with each other, and an image of a pattern of the mask on the substrate. 13. The exposure apparatus according to claim 11, wherein, when the image is transferred onto the projection system, the stage system is driven to synchronously scan the mask and the substrate with respect to the projection system. 14. The broadband light source generates light having a wavelength in an extreme ultraviolet region as the illumination light for exposure, and generates light having at least one wavelength in an ultraviolet region or a visible region as the non-exposure wavelength light. With, when using the light of the non-exposure wavelength from the broadband light source, a predetermined gas is supplied to the optical path of the light, when using the illumination light for exposure from the broadband light source, The exposure apparatus according to any one of claims 10 to 13, wherein an optical path of the illumination light is substantially evacuated. 15. A wavelength selection device for passing any one of the exposure illumination light and the non-exposure wavelength light emitted from the broadband light source to the illumination system. The exposure apparatus according to any one of claims 10 to 14.