JP2005019628A - Optical apparatus, aligner, manufacturing method of device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical apparatus capable of correcting or solving an aberration of an optical member with a simple configuration. <P>SOLUTION: The optical apparatus is provided with a heat generating body 101 for heating the optical member CM disposed on the optical path of an energy beam IL. The heat generating body 101 has heat generation distribution based on the aberration of the optical member CM. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention is suitable for a method of manufacturing a microdevice such as a semiconductor integrated circuit, an image pickup device such as a CCD, a liquid crystal display, or a thin film magnetic head using a lithography technique, an exposure apparatus used at the time of manufacturing, and a suitable exposure apparatus. The present invention relates to an optical device.
[0002]
[Prior art]
When manufacturing semiconductor devices and liquid crystal display devices using lithography technology, the illumination light for exposure (exposure beam) is illuminated onto the mask on which the pattern is formed, and the mask pattern image is projected via the projection optical system. An exposure apparatus that performs projection exposure on a substrate such as a semiconductor wafer or a glass plate coated with a photosensitive material such as a resist is used. In recent years, in an exposure apparatus, the wavelength of an exposure beam has been shortened with the miniaturization of a pattern.
[0003]
Examples of the short wavelength exposure beam include KrF excimer laser light (wavelength: 248 nm), ArF excimer laser light (wavelength: 193 nm), F ₂ There is laser light (wavelength: 157 nm). Further, the use of light in the soft X-ray region having a wavelength of 5 to 15 nm (hereinafter, this light is referred to as EUV (Extreme Ultra Violet) light) as an exposure beam having a shorter wavelength is being studied.
[0004]
In an exposure apparatus using an exposure beam with a short wavelength, an optical member arranged on the optical path of the exposure beam is likely to generate heat when irradiated with the exposure beam, and control of the thermal deformation of the optical member associated therewith is one of the problems. . In particular, in an exposure apparatus using short wavelength ultraviolet rays or EUV light, the space on the optical path is often evacuated, and in that case, there is almost no cooling effect due to convective heat transfer. Therefore, thermal deformation of the optical member is likely to occur greatly.
[0005]
In general, the irradiation energy density distribution of the exposure beam on the optical member is not uniform within the irradiation region. Therefore, the thermal deformation of the optical member caused by the irradiation heat tends to be complicated. Complex deformation of the optical member produces higher order aberrations that are difficult to correct.
[0006]
As a technique for suppressing the thermal deformation of the optical member, for example, the deformation of the optical member is detected by a sensor, and the actuator is driven based on the detection result. There is a technique for applying force to a member (see, for example, Patent Document 1).
[0007]
[Patent Document 1]
JP 2002-100551 A
[0008]
[Problems to be solved by the invention]
However, in the above technique, in order to correct higher-order deformation, it is necessary to arrange a large number of sensors and actuators, resulting in a complicated configuration and difficulty in securing a space for installing the sensors and actuators.
[0009]
The present invention has been made in view of the above-described circumstances, and an object of the present invention is to provide an optical device capable of correcting or eliminating aberration of an optical member with a simple configuration.
Another object of the present invention is to provide an exposure apparatus capable of accurately transferring a mask pattern image onto a substrate, and a device manufacturing method capable of improving the precision of a pattern to be formed.
[0010]
[Means for Solving the Problems]
In order to solve the above problems, an optical device according to the present invention is an optical device including an optical member (CM) disposed on an optical path of an energy beam (IL), and generates heat to heat the optical member (CM). The heating element (101) has a heat generation distribution based on the aberration of the optical member (CM).
[0011]
In this optical device, the optical member can be thermally deformed by heating the optical member via the heating element. In this thermal deformation, the heating element has a heat generation distribution based on the aberration of the optical member, so that the aberration of the optical member can be corrected or eliminated. Further, in this optical apparatus, since it is not necessary to apply an external force to the optical member when correcting the aberration, the configuration can be simplified.
[0012]
The aberration of the optical member (CM) includes, for example, at least one of an aberration associated with a shape error, an aberration associated with assembly deformation, and an aberration associated with thermal deformation caused by irradiation of the energy beam. In the optical device of the present invention, the optical characteristics are improved by correcting or eliminating these aberrations by heating the optical member. The heating of the optical member for aberration correction can be performed after the device is assembled or during actual operation of the device.
[0013]
In the above-described optical device, the heating element may include, for example, a plurality of electric resistors (101) that are arranged in a plurality of locations of the optical member (CM) and whose current supply amount is controlled. . In this configuration, a heat generation distribution based on the aberration of the optical member can be formed by controlling the amount of current supplied to each of the plurality of electrical resistances.
[0014]
In this case, a plurality of electrical resistance groups (135, 136) including the plurality of electrical resistances (131) and spaced apart from each other may be included. In this configuration, the optical member can be easily deformed by providing a difference in the amount of current supplied to each of the plurality of electrical resistance groups arranged apart from each other.
[0015]
In the optical device, the heating element may include an electric resistance (141) having a cross-sectional shape based on the aberration of the optical member (CM5). In this case, for example, the cross-sectional area is reduced in a portion where a large amount of heat generation is desired, and the cross-sectional area is increased in a portion where heat generation may be small. In this configuration, since the heat generation distribution is formed according to the cross-sectional shape of the electrical resistance, it is easy to simplify the configuration.
[0016]
In the optical device, the optical member (CM2) has a reflective surface (110) that reflects the energy beam (IL), and the heating element (111) is disposed on the back side of the reflective surface. It is good also as a structure. In this configuration, the aberration generated on the reflecting surface is corrected or eliminated by heating from the back side of the reflecting surface by the heating element.
[0017]
In this case, since the back side of the reflective surface (110) is thinned, the reflective surface is easily thermally deformed.
[0018]
In the optical device, the optical member (CM3) may be molded so as to include the heating element (121). Since the heating element is included in the optical member, the heat of the heating element is difficult to escape to the outside, and the thermal efficiency is improved.
[0019]
In the above optical device, the heat generating element (151) may have a heat generation distribution controlled in accordance with an irradiation state of the energy beam (IL) on the optical member (CM6). In this case, even when the irradiation state of the energy beam changes, the aberration generated in the optical member is corrected or eliminated by controlling the heat generation distribution of the plurality of electric resistances according to the irradiation state.
[0020]
The exposure apparatus of the present invention includes an illumination system (21) that illuminates a mask (R) on which a pattern is formed with an energy beam (IL), and projection optics that transfers the pattern of the mask (R) onto a substrate (W). At least one of the system (PL) includes the optical device described above.
The device manufacturing method of the present invention includes a step of transferring a device pattern formed on the mask (R) onto the substrate (W) using the exposure apparatus described above.
[0021]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a first embodiment of the present invention will be described with reference to the drawings.
FIG. 1 shows an overall configuration of a reduction projection type exposure apparatus 10 for manufacturing a semiconductor device according to an embodiment provided with the optical apparatus according to the present invention as a projection optical system. In FIG. 1, an XYZ orthogonal coordinate system is adopted. In the XYZ orthogonal coordinate system, the X axis and the Y axis are set so as to be parallel to a wafer stage WS holding a wafer W as a substrate (photosensitive substrate), and the Z axis is orthogonal to the wafer stage WS. Set to direction. Actually, in the XYZ orthogonal coordinate system in the figure, the XY plane is set to a plane parallel to the horizontal plane, and the Z axis is set to the vertical direction.
[0022]
The exposure apparatus according to this embodiment uses F as an exposure light source. ₂ A laser light source is used. Also, one shot area on the wafer W is scanned by synchronizing the reticle R and the wafer W in a predetermined direction relative to the illumination area having a predetermined shape on the reticle R as a mask (projection original). In addition, a step-and-scan system that sequentially transfers the pattern image of the reticle R is adopted.
[0023]
In FIG. 1, an exposure apparatus 10 projects a laser light source 20, an illumination optical system 21 that illuminates a reticle R with an exposure beam IL from the laser light source 20, and a projection that projects an exposure beam IL emitted from the reticle R onto a wafer W. An optical system PL and a main controller (not shown) that controls the entire apparatus are provided.
[0024]
The laser light source 20 outputs, for example, pulsed ultraviolet light having an oscillation wavelength of 157 nm. ₂ Have a laser. Further, the laser light source 20 is provided with a light source control device (not shown), and this light source control device has an oscillation center wavelength and a spectrum half-value width of the emitted pulsed ultraviolet light according to an instruction from the main control device. Control, pulse oscillation trigger control, control of gas in the laser chamber, and the like are performed.
[0025]
Pulse laser light (illumination light) from the laser light source 20 is deflected by the deflection mirror 30 and enters the variable dimmer 31 as an optical attenuator. The variable dimmer 31 can adjust the dimming rate stepwise or continuously in order to control the exposure amount of the photoresist on the wafer. The illumination light emitted from the variable dimmer 31 is deflected by the optical path deflecting mirror 32, and then reaches the second fly-eye lens 36 through the first fly-eye lens 33, the zoom lens 34, and the vibration mirror 35 in this order. . On the emission side of the second fly-eye lens 36, a switching revolver 37 for an illumination optical system aperture stop for setting the size and shape of the effective light source as desired is disposed. In the present embodiment, in order to reduce the light amount loss at the illumination optical system aperture stop, the size of the light flux to the second fly's eye lens 36 by the zoom lens 34 is variable.
[0026]
The light beam emitted from the aperture of the illumination optical system aperture stop illuminates the illumination field stop (reticle blind) 41 via the condenser lens group 40. The illumination field stop 41 is disclosed in JP-A-4-196513 and US Pat. No. 5,473,410 corresponding thereto.
[0027]
The light from the illumination field stop 41 is guided onto the reticle R via the illumination field stop imaging optical system (reticle blind imaging system) including the deflection mirrors 42 and 45, the lens groups 43, 44, and 46, and the reticle. On R, an illumination area that is an image of the opening of the illumination field stop 41 is formed. The light from the illumination area on the reticle R is guided onto the wafer W via the projection optical system PL, and a reduced image of the pattern in the illumination area of the reticle R is formed on the wafer W. The reticle stage RS that holds the reticle R can be moved two-dimensionally in the XY plane, and its position coordinates are measured and controlled by the interferometer 50. Further, the wafer stage WS holding the wafer W can also be moved two-dimensionally in the XY plane, and its position coordinates are measured and controlled by the interferometer 51. As a result, the reticle R and the wafer W can be synchronously scanned with high accuracy. The illumination optical system 21 is composed of the laser light source 20 to the illumination field stop imaging optical system described above.
[0028]
2 and 3 show examples of the configuration of the projection optical system PL, respectively. In the present embodiment, a catadioptric projection optical system is employed. A configuration example of the catadioptric projection optical system will be described below with reference to FIGS.
[0029]
In the configuration example of FIG. 2, the projection optical system PL includes a refractive first imaging optical system K1 that forms an intermediate image of a pattern on a reticle R as a projection master, and an intermediate image by the first imaging optical system K1. A refraction-type second imaging optical system K2 for re-imaging the image (secondary image) and a refraction type for re-imaging the secondary image by the second imaging optical system K2 on the wafer W as a workpiece. The third imaging optical system K3. Here, in the optical path between the first imaging optical system K1 and the second imaging optical system K2, a reflection surface M1 for bending the optical path for deflecting the optical path by 90 ° is disposed. In the optical path between the imaging optical system K2 and the third imaging optical system K3, there is disposed a reflection surface M2 for bending the optical path for deflecting the optical path by 90 °. These reflecting surfaces M1 and M2 are provided on the optical path bending member FM.
[0030]
The first imaging optical system K1 has a plurality of lens components arranged along the optical axis Ax1, and is intermediate at a reduction ratio of about 1 / 1.5 times to 1/3. Form an image. The second imaging optical system K2 has one or a plurality of lens components arranged along the optical axis Ax2 and the concave reflecting mirror CM, and the first imaging optical system is at approximately equal magnification. An intermediate image (secondary image) is formed by K1. The third imaging optical system K3 has a plurality of lens components arranged along the optical axis Ax3, and has a reduction magnification of about 1 / 1.5 times to 1/3. A secondary image (tertiary image) is formed on the wafer W by the first and second imaging optical systems K1 and K2. In this example, the optical axis Ax1 and the optical axis Ax3 coincide with each other. However, the optical axis Ax1 and the optical axis Ax3 may be parallel and inconsistent with each other, and the optical axis Ax2 It does not have to be orthogonal to Ax1 or the optical axis Ax3.
[0031]
In the configuration example of FIG. 3, the projection optical system PL includes a catadioptric first imaging optical system K1 that forms an intermediate image of a pattern on a reticle R as a projection master, and a first imaging optical system K1. A refraction-type second imaging optical system K2 for re-imaging an intermediate image formed by the above method on a wafer W as a workpiece. Here, in the optical path between the reticle R and the first imaging optical system K1, an optical path bending reflecting surface M1 for deflecting the optical path by 90 ° is disposed, and the first imaging optical system K1. A reflecting surface M2 for bending the optical path for deflecting the optical path by 90 ° is disposed in the optical path between the second imaging optical system K2 and in the vicinity of the intermediate image. These reflecting surfaces M1 and M2 are provided on the optical path bending member FM.
[0032]
The first imaging optical system K1 has a plurality of lens components arranged along the optical axis Ax2 and the concave reflecting mirror CM, and forms an intermediate image under substantially the same magnification or slightly reduced magnification. . The second imaging optical system K2 has a plurality of lens components arranged along an optical axis Ax3 orthogonal to the optical axis Ax2 and a variable aperture stop AS for controlling a coherence factor. An intermediate image, that is, a secondary image is formed under the reduction magnification based on this light. Here, the optical axis Ax2 of the first imaging optical system K1 is bent by 90 ° by the optical path bending reflecting surface M1, and the optical axis Ax1 is defined between the reticle R and the reflecting surface M1. In this example, the optical axis Ax1 and the optical axis Ax3 are parallel to each other, but do not match. In this example, the optical axis Ax1 and the optical axis Ax3 may be arranged so as to coincide with each other. Further, the angle formed between the optical axis Ax1 and the optical axis Ax2 may be an angle different from 90 °, preferably an angle obtained by rotating the concave reflecting mirror CM counterclockwise. At this time, it is preferable to set the bending angle of the optical axis at the reflecting surface M2 so that the reticle R and the wafer W are parallel to each other.
[0033]
Returning to FIG. 1, F used in this embodiment is used. ₂ In the case where light in the vacuum ultraviolet region is used as an exposure beam, such as laser light (wavelength: 157 nm), it has a strong absorption characteristic with respect to light in the wavelength band such as oxygen, water vapor, hydrocarbon gas, etc. from the optical path. It is necessary to exclude gas having the following (hereinafter referred to as “absorbing gas” as appropriate). Therefore, in this embodiment, the illumination optical path (the optical path from the laser light source 20 to the reticle R) and the projection optical path (the optical path from the reticle R to the wafer W) are blocked from the external atmosphere, and these optical paths are converted into light in the vacuum ultraviolet region. Filled with nitrogen, helium, argon, neon, krypton, etc., or a mixed gas (hereinafter referred to as “low-absorbing gas” or “specific gas” as appropriate) ing.
[0034]
Specifically, the optical path from the laser light source 20 to the variable dimmer 31 is blocked from the external atmosphere by the casing 60, and the optical path from the variable dimmer 31 to the illumination field stop 41 is blocked from the external atmosphere by the casing 61. The illumination field stop imaging optical system is shielded from the external atmosphere by the casing 62, and the specific gas is filled in the optical path thereof. The casing 61 and the casing 62 are connected by a casing 63. In addition, the projection optical system PL itself has its barrel 69 as a casing, and the internal optical path is filled with the specific gas.
[0035]
The casing 64 blocks the space between the casing 62 containing the illumination field stop imaging optical system and the projection optical system PL from the external atmosphere, and houses the reticle stage RS that holds the reticle R therein. is doing. The casing 64 is provided with a door 70 for loading / unloading the reticle R. The outside of the door 70 prevents the atmosphere in the casing 64 from being contaminated when the reticle R is loaded / unloaded. A gas replacement chamber 65 is provided. The gas replacement chamber 65 is also provided with a door 71, and the reticle is transferred to and from the reticle stocker 66 storing a plurality of types of reticles via the door 71.
[0036]
The casing 67 blocks the space between the projection optical system PL and the wafer W from the external atmosphere, and a wafer stage WS that holds the wafer W via the wafer holder 80 and a surface of the wafer W inside the casing 67. Accommodates an oblique-incidence type autofocus sensor 81 for detecting the Z-direction position (focus position) and tilt angle, an off-axis alignment sensor 82, a surface plate 83 on which the wafer stage WS is placed, and the like. ing. The casing 67 is provided with a door 72 for loading / unloading the wafer W, and a gas replacement chamber 68 for preventing the atmosphere inside the casing 67 from being contaminated outside the door 72. It has been. The gas replacement chamber 68 is provided with a door 73, and the wafer W is carried into the apparatus and the wafer W is carried out of the apparatus through the door 73.
[0037]
Nitrogen or helium is preferably used as the specific gas filled in each optical path space. Nitrogen has a strong light absorption characteristic for light having a wavelength of about 150 nm or less, and helium has a strong light absorption characteristic for light having a wavelength of about 100 nm or less. Helium has a thermal conductivity of about 6 times that of nitrogen, and the amount of change in refractive index with respect to changes in atmospheric pressure is about 1/8 of that of nitrogen. Therefore, particularly high transmittance, stability of the imaging characteristics of the optical system, and cooling performance. And is excellent at. Note that helium may be used as the specific gas for the lens barrel of the projection optical system PL, and nitrogen may be used as the specific gas for other optical paths (for example, an illumination optical path from the laser light source 20 to the reticle R).
[0038]
4 and 5 are views schematically showing the structure of the concave reflecting mirror CM shown in FIGS. 2 and 3, FIG. 4 is a plan view, and FIG. 5 is a cross-sectional view.
4 and 5, a plurality of electric resistors 101 as heating elements are embedded in the concave reflecting mirror CM over the entire reflecting surface 100. Each of the plurality of electric resistors 101 is embedded near the surface of the reflecting surface 100 of the concave reflecting mirror CM, and is connected in parallel to the controller 103 via a conducting wire 102. The controller 103 is configured to be able to accurately control the current supplied to each electrical resistor 101, thereby allowing the amount of heat generated by each electrical resistor 101 and the heat distribution of the plurality of electrical resistors 101 to be freely set. It is possible to control.
[0039]
As the material of the concave reflecting mirror CM, SiC, Zerodur (trade name), ULE (trade name), or the like is used. Further, in order to suppress the movement of heat from the concave reflecting mirror CM to the lens barrel 69, the concave reflecting mirror CM includes a cell 104 made of a member (heat insulating material) having a large thermal resistance, for example, a resin having low thermal conductivity. Is supported through. In this example, the cell 104 is formed of a ring-shaped member and supports, for example, the concave reflecting mirror CM at three points. In the embedding of the electric resistance 101 in the concave reflecting mirror CM, for example, when the concave reflecting mirror is ceramic, in the molding process before baking, the electric resistance to which the conductive wire is connected is embedded in the reflecting mirror, and then baking is performed. Is done. The conducting wire is connected to the controller after forming the concave reflecting mirror.
[0040]
The plurality of electric resistors 101 are uniformly distributed on the reflecting surface 100 of the concave reflecting mirror CM, and are arranged at almost equal intervals. The arrangement pitch of the plurality of electric resistors 101 is appropriately determined according to the physical properties of the concave reflecting mirror CM, the heat generation characteristics of the electric resistors, and the like. In the present invention, the arrangement state of the plurality of electric resistances is not limited to the above-mentioned equal interval, and for example, the distribution density may be different for each region. Further, the conductor 102 other than the electric resistance portion may be covered with a substance having a low affinity with the material for forming the concave reflector CM so that the thermal expansion / contraction of the conductor 102 does not induce deformation of the concave reflector CM. Good.
[0041]
Here, FIG. 6A shows an irradiation region (irradiation field) of the exposure beam with respect to the concave reflecting mirror CM, FIG. 6B shows an irradiation energy density distribution in the irradiation region, and FIG. Indicates an electric heat distribution due to a plurality of electric resistances embedded in the concave reflecting mirror CM. The area shape of the exposure beam is defined in accordance with the pattern area of the mask, and as shown in FIG. Further, as shown in FIG. 6B, the irradiation energy density distribution is not uniform, and is high in the central portion and lower toward the periphery. When the irradiation region is rectangular, the thermal deformation of the optical member due to the irradiation heat becomes non-rotationally symmetric and tends to produce higher-order aberrations that are difficult to optically correct.
[0042]
In the present embodiment, the plurality of electric resistors 101 (see FIG. 4) have a heat generation distribution based on the aberration of the concave reflecting mirror CM. Specifically, as shown in FIG. 6C, the plurality of electric resistors 101 have a heat generation distribution that is substantially in inverse proportion to the irradiation energy density distribution of the exposure beam (FIG. 6B). That is, the controller 103 controls the amount of current supplied to the plurality of electric resistors 101, and among the plurality of electric resistors 101, the controller 103 has a peripheral portion compared with the electric resistance of the central portion of the reflecting surface 100 of the concave reflecting mirror CM. Increase the current value supplied to the electrical resistance. As a result, as shown in FIG. 6C, the electric heat generation amount is small at the central portion of the reflecting surface 100 of the concave reflecting mirror CM, the heat generation amount is large at the peripheral portion, and the electric heat generation of the plurality of electric resistors 101 is performed. The distribution and the irradiation energy density distribution of the exposure beam are substantially inversely proportional. Then, due to this substantially inversely proportional relationship, the sum of the heat generation distribution due to the exposure beam irradiation energy and the heat generation distribution due to the plurality of electrical resistances 101 is indicated by the two-dot chain line in FIG. As a result, non-rotationally symmetric aberration fluctuations associated with irradiation of the exposure beam are suppressed.
[0043]
Thus, in this embodiment, the aberration caused by the thermal deformation of the concave reflecting mirror CM due to the irradiation heat of the exposure beam is eliminated by heating the concave reflecting mirror CM by the plurality of electric resistors 101. Therefore, the optical characteristics of the concave reflecting mirror CM can be improved.
[0044]
Note that the irradiation energy density distribution can be determined strictly from the design value. In general, it is very easy to control the current supplied to a simple electric resistance. In other words, in this embodiment, by controlling the amount of current supplied to a plurality of electrical resistances, it is possible to accurately generate an arbitrary heat generation distribution, and as a result, accurately eliminate or correct aberration fluctuations of the concave reflecting mirror. can do. In this case, since it is not necessary to apply an external force to the optical member using a mechanical means such as an actuator when eliminating or correcting the aberration fluctuation of the optical member (concave reflector CM), the configuration can be simplified. The space is used effectively. In addition, since the aberration is corrected based on the irradiation energy density distribution of the exposure beam that can be calculated in advance, rather than using the result of detecting the deformation of the optical member (concave reflector CM) with a sensor or the like, the correction delay Is unlikely to occur.
[0045]
Further, in this embodiment, since the concave reflecting mirror CM is supported by the cell 104 which is a member (heat insulating material) having a large thermal resistance, the heat generated by the concave reflecting mirror CM is mainly emitted from the reflecting surface 100. Will be released. When supporting the concave reflecting mirror CM at three points, a cell serving as a supporting member may be generated, although the temperature near the supporting portion may decrease due to heat conduction through the supporting portion, so-called 3θ-shaped temperature distribution may occur. Since 104 is a heat insulating material, the occurrence of uneven temperature in the concave reflecting mirror CM due to the heat conduction is suppressed.
[0046]
In the above embodiment, the heating of the concave reflecting mirror CM by the plurality of electric resistors 101 is not limited to the irradiation of the exposure beam, but may be performed at the time of non-irradiation. In this case, for example, when the exposure beam is not irradiated, the currents to the plurality of electric resistances 101 are set so that the entire reflection surface 100 of the concave reflecting mirror CM has a uniform heat generation distribution (temperature distribution) similar to that during irradiation. It is good to control the supply amount. This makes it possible to eliminate not only rotationally symmetric aberration fluctuations associated with exposure beam irradiation but also rotationally symmetric irradiation fluctuations for the concave reflecting mirror CM.
[0047]
Here, the correction of the aberration of the optical member (concave reflecting mirror) by the heating described above can also be applied to correction of a general aberration not caused by irradiation. Aberrations not caused by irradiation include, for example, aberrations associated with shape errors and aberrations associated with assembly deformation. These aberrations are not limited to a single optical member, but include the entire aberration of the optical system (projection optical system).
[0048]
FIG. 7 is a flowchart showing an example of a procedure for correcting the aberration of the entire optical system (projection optical system).
In the flow shown in FIG. 7, first, the aberration of the entire optical system is measured (step 250), and the optical member (concave reflector CM in this example) necessary to correct the aberration based on the measurement result is measured. A deformation amount is obtained (step 251). Next, the calorific value of each of the plurality of electrical resistances required for the deformation is calculated, and the amount of current supplied to each of the plurality of electrical resistances is controlled based on the calculation result. A heat generation distribution is formed by (step 252). Then, the aberration of the entire optical system is measured again in a state where the optical member is thermally deformed (step 253), and the above series of procedures is repeated until the aberration falls within the allowable range.
[0049]
In addition, the process (step 252) of forming the heat generation distribution due to the plurality of electrical resistances described above is performed as follows.
First, the deformation amount (surface change) of the optical member (concave reflecting mirror) caused by the unit calorific value change given to a plurality of electric resistances is obtained in advance by simulation or experiment. As a result, the calorific values of the N electrical resistors 1 to N are respectively expressed by ΔQ ₁ , ΔQ ₂ ・ ・ ・… Q _N It is possible to calculate the surface change ΔS when only the change is made. The surface change to be obtained is ΔS ₀ The evaluation function | ΔS−ΔS ₀ | Is minimized (ΔQ ₁ , ΔQ ₂ ・ ・ ・… Q _N ) Is calculated by the method of least squares or the like, whereby the heat generation distribution necessary for correcting the aberration can be obtained.
[0050]
Thus, by feeding back the aberration measurement result of the entire optical system, it is possible to correct aberrations very easily even after the optical system is assembled. At that time, as the number of electric resistances to be arranged increases, the state of the heat distribution can be controlled more finely, so that higher-order aberrations can be corrected.
[0051]
Next, a second embodiment of the present invention will be described with reference to FIG.
In the present embodiment, as in the first embodiment described above, a plurality of electrical resistors 111 as heating elements are arranged over the entire reflective surface 110 of the concave reflecting mirror CM2, and the plurality of electrical resistors 111 are respectively The conductors 112 are connected in parallel to the controller 113. Further, in the present embodiment, unlike the first embodiment described above, the concave reflecting mirror CM2 has a thin structure, and the plurality of electric resistors 111 are arranged on the back surface thereof. That is, the concave reflecting mirror CM2 has the thickness of the back surface side of the reflecting surface 110 as it is compared to the concave reflecting mirror CM shown in the first embodiment (thickening), and a plurality of concave reflecting mirrors CM2 are formed on the back surface. The electrical resistance 111 is affixed.
[0052]
With this configuration, in this embodiment, since the concave reflecting mirror CM2 is thinned, the rigidity of the concave reflecting mirror CM2 is low, and the reflecting surface 110 of the concave reflecting mirror CM is easily deformed. Moreover, heat capacity is low and heat dissipation is high. Therefore, the reflective surface 110 of the concave reflecting mirror CM can be thermally deformed to a desired state with a small amount of heating. That is, the aberration correction by the plurality of electric resistors 111 has a high effect on the unit current, and the sensitivity can be improved.
[0053]
Further, in the present embodiment, when the electric resistor 111 is arranged, for example, even when the concave reflecting mirror is ceramic, it is not necessary to embed a plurality of electric resistors at the time of molding, and it may be retrofitted. Therefore, it is excellent in productivity.
[0054]
Next, a third embodiment of the present invention will be described with reference to FIG.
In the present embodiment, as in the above-described embodiments, a plurality of electric resistors 121 as heating elements are arranged over the entire reflecting surface 120 of the concave reflecting mirror CM3, and the plurality of electric resistors 121 are respectively conductive wires 122. Are connected to the controller 123 in parallel. In the present embodiment, the concave reflecting mirror CM3 has a thin-walled structure, and the plurality of electric resistors 121 are embedded therein. That is, the concave reflecting mirror CM3 has substantially the same shape as the concave reflecting mirror CM2 shown in the second embodiment, and is different from the second embodiment in that a plurality of electric resistors 121 are embedded therein.
[0055]
With the above configuration, in this embodiment, the concave reflecting mirror CM3 is thinned. Thus, as in the second embodiment, the effect of aberration correction by the plurality of electric resistors 121, which are heating elements, is high, and the sensitivity Is improved. In addition, since the plurality of electric resistors 121 are embedded in the concave reflecting mirror CM3, the productivity of the electric resistors 121 is inferior to that of the second embodiment, but the heat of the plurality of electric resistors 121 is difficult to escape to the outside. There is an advantage that is high.
[0056]
Next, a fourth embodiment of the present invention will be described with reference to FIG.
In the present embodiment, as in the above-described embodiments, a plurality of electrical resistors 131 as heating elements are arranged over the entire reflecting surface 130 of the concave reflecting mirror CM4, and the plurality of electrical resistors 131 are respectively conductive wires 132. Are connected to the controller 133 in parallel. In the present embodiment, the plurality of electric resistors 131 are embedded in the concave reflecting mirror CM4, and the plurality of electric resistors 131 are divided into two groups and arranged separately in the thickness direction of the concave reflecting mirror CM4. Has been. That is, in the concave reflecting mirror CM4, a first electrical resistance group 135 composed of a plurality of electrical resistances embedded near the surface of the reflection surface 130 and a second electrical resistance group composed of a plurality of electrical resistances embedded near the back surface. As a result, two layers including a plurality of electric resistances are formed.
[0057]
With the above configuration, in the present embodiment, since the two electric resistance groups 135 and 136 are arranged apart from each other in the thickness direction of the concave reflecting mirror CM4, the concave reflecting mirror CM4 is likely to be thermally deformed. That is, with the above configuration, for example, by providing a difference in the heat generation temperature of the electrical resistance group between the front surface side and the back surface side of the concave reflecting mirror CM4, the concave reflecting mirror CM4 is easily deformed by the same action as the bimetal effect. . Further, in this case, the flexibility of deformation is high, and aberrations associated with the shape error of the concave reflecting mirror CM4 can be preferably eliminated or corrected.
[0058]
Next, a fifth embodiment of the present invention will be described with reference to FIGS. In the present embodiment, as in the above-described embodiments, a plurality of electric resistors 141 as heating elements are arranged over the entire reflection surface 140 of the concave reflecting mirror CM5, and each of the plurality of electric resistors 141 is a conducting wire 142. Is connected to the controller 143 via Further, in the present embodiment, unlike each of the above embodiments, the plurality of electric resistors 141 are embedded near the surface of the reflecting surface 140 of the concave reflecting mirror CM5 so as to be substantially parallel to the reflecting surface 140 and the reflecting surface. It is arranged parallel to 140 meridian planes. Further, each of the plurality of electric resistors 141 has a cross-sectional shape based on the aberration of the concave reflecting mirror CM5. In this example, the cross-sectional shape of each electric resistor 141 is determined based on the aberration caused by the thermal deformation of the concave reflecting mirror CM5 due to the irradiation heat of the exposure beam. That is, each electric resistance 141 has a small cross-sectional area (high resistance = high heat generation) in a portion where it is desired to obtain a large amount of heat, and a portion where heat generation may be small. The area is large (small resistance = small heat generation).
[0059]
With this configuration, in the present embodiment, a heat generation distribution is formed according to the arrangement and cross-sectional shape of the plurality of electric resistors 141, and as a result, the aberration of the concave reflecting mirror CM5 due to the irradiation heat of the exposure beam is eliminated or corrected. In this configuration, since the heat generation distribution is determined according to the cross-sectional shape of the electrical resistance, it is difficult to change the heat generation distribution to another state, but the number of electrical resistances can be reduced and the configuration can be simplified. It is done.
[0060]
Next, a sixth embodiment of the present invention will be described with reference to FIG.
In the present embodiment, similar to the fifth embodiment, a plurality of electric resistors 151 having a cross-sectional shape based on the aberration of the concave reflecting mirror CM6 are embedded near the surface of the reflecting surface 150 of the concave reflecting mirror CM6, and the reflecting surface 150 is arranged so as to be substantially parallel to 150 and parallel to the meridional surface of the reflecting surface 150. Although not shown, each of the plurality of electric resistors 151 is connected to the controller via a conducting wire. Moreover, in this embodiment, unlike the said 5th Embodiment, the several electrical resistance 151 is divided into the several group (Group A, Group B, and Group C), and each according to switching of illumination conditions Groups are selectively used. More specifically, the electrical resistances 151 of the groups A, B, and C are alternately arranged adjacent to each other. Moreover, the cross-sectional shape of the plurality of electric resistors 151 is determined so that a predetermined heat distribution is obtained for each group. Among the three predetermined illumination conditions, when the exposure beam is irradiated under the first illumination condition, the electrical resistance of the A group is energized, and under the second illumination condition, the electrical resistance of the B group, the third Under the lighting conditions, the electrical resistance of group C is energized.
[0061]
With the above configuration, in the present embodiment, a heat generation distribution of the plurality of electric resistors 151 is formed according to each of a plurality of (three in this example) illumination conditions. That is, when the illumination condition changes, the irradiation energy density distribution changes, but the heat generation distribution of the plurality of electric resistors 151 is controlled according to the irradiation state. As a result, even if the illumination condition changes, the aberration of the concave reflecting mirror CM6 due to the irradiation heat is eliminated or corrected according to the illumination condition.
[0062]
Next, a seventh embodiment of the present invention will be described with reference to FIG.
The present embodiment is a form mainly intended for correction of deformation of a low-order 2θ shape on the reflecting surface 160 of the optical member (concave reflecting mirror CM7). Here, among aberrations such as aberration fluctuations due to irradiation heat, aberrations due to shape errors, and aberrations due to assembly deformation, the most likely aberration component is the low-order 2θ component. The characteristics are improved. The 2θ component of this aberration can be corrected by deforming the reflecting surface into a 2θ shape in the vicinity of the pupil of the optical system.
[0063]
In the present embodiment, the two electric resistors 161a and 161b are buried near the surface of the reflecting surface 160 of the concave reflecting mirror CM7 and are arranged so as to be substantially parallel to the reflecting surface 160. The two electric resistors 161a and 161b are arranged separately in two orthogonal meridian planes. Although not shown in the drawing, each of the electric resistors 161a and 161b is connected to the controller via a conducting wire.
[0064]
With the above configuration, in the present embodiment, a difference is provided in the amount of current supplied to the two electric resistors 161a and 161b, and a difference is generated in the heat generation temperature of the electric resistors 161a and 161b. 2θ-like deformation can be applied to the reflecting surface 160, and as a result, the 2θ component of the aberration is eliminated or corrected. In the present embodiment, since the purpose is mainly to correct the deformation of the 2θ shape, the configuration can be simplified. Note that, as in the fifth embodiment (see FIG. 12), the cross-sectional shapes of the electric resistors 161a and 161b may be changed based on the aberration of the concave reflecting mirror CM7.
[0065]
Next, an eighth embodiment of the present invention will be described with reference to FIGS.
The present embodiment is a modification of the seventh embodiment, and is a mode mainly intended to correct low-order 2θ-shaped deformation in the reflecting surface 170 of the optical member (concave reflecting mirror CM8). In the present embodiment, two electric resistors 171a and 171b are embedded near the surface of the reflecting surface 170 of the concave reflecting mirror CM8, and two electric resistors 171c and 171d are also embedded on the back surface side. The two electric resistances 171a and 171b on the front surface side and the two electric resistances 171c and 171d on the back surface side are arranged separately in two orthogonal meridian surfaces. Although not shown, each of the electric resistors 171a to 171d is connected to the controller via a conducting wire.
[0066]
With the above configuration, in the present embodiment, similarly to the seventh embodiment, by providing a difference in the amount of current supplied to the two electric resistors 171a and 171b and providing a difference in the heat generation temperature of these electric resistors, The 2θ-like deformation can be applied to the reflecting surface 170 of the concave reflecting mirror CM8, and as a result, the 2θ component of the aberration is eliminated or corrected. Further, in the present embodiment, similarly to the fourth embodiment, the electrical resistance is divided and disposed near the front surface and the back surface side of the concave reflecting mirror CM8, so that the front surface side and the back surface side of the concave reflecting mirror CM8 are arranged. Therefore, the concave reflecting mirror CM8 can be easily deformed by the same action as the bimetal effect.
[0067]
Next, a ninth embodiment of the present invention will be described with reference to FIGS. In the present embodiment, a variable heat generating device 181 capable of forming an arbitrary heat generation distribution is bonded to or directly generated on the back surface of the concave reflecting mirror CM9.
[0068]
FIG. 18 is a diagram schematically illustrating an example of the form of the variable heat generating device 181.
In FIG. 18, the device 181 includes a resistance line layer 182 including an electric resistance, a bypass layer 183 including a conductor for bypassing a current, a switching layer 184 including a plurality of transistors, and the like. A DC voltage is applied via the controller 185. Each transistor in the switching layer 184 is controlled via the controller 185.
[0069]
Conductive wires in the bypass layer 183 and transistors in the switching layer 184 are connected to the resistance line layer 182 for each predetermined section. The transistor of the switching layer 184 controls the heat generation state of each section (heat generation section i) in the resistance line layer 182. That is, when a transistor (switch i) in the switching layer 184 is in an off state (non-conducting state), a current flows through the electrical resistance in a predetermined section (heat generation section i) of the resistance line layer 182 corresponding to the transistor, and a heat generation state occurs. (Route A shown in FIG. 18). On the other hand, when the transistor (switch i) is in the on state (conducting state), the difference between the resistance values of the electrical resistance and the bypass circuit (electric resistance) in a predetermined section (heat generation section i) of the resistance line layer 182 corresponding to the transistor. > Bypass circuit), a current flows through the bypass circuit, and the electric resistance is in a non-heated state (path B shown in FIG. 18). Therefore, in the device 181, an arbitrary heat distribution is formed in the resistance line layer 182 by controlling the on / off states of the plurality of transistors in the switching layer 184 via the controller 185 (see FIG. 17). Can do. That is, when the density of the section in the heat generation state is increased in the predetermined area of the resistance wire layer 182, the area becomes high temperature, and conversely, when the density of the section in the heat generation state is decreased, the area becomes low temperature.
[0070]
With the above configuration, in the present embodiment, a heat generation distribution is formed in the variable heat generating device 181 based on the aberration of the concave reflecting mirror CM9 (reflecting surface 180), thereby eliminating or correcting the aberration generated in the concave reflecting mirror CM9. . Further, in the present embodiment, by manufacturing the device 181 using a process similar to that of a semiconductor device, the unit section (heat generation section) to be controlled can be made extremely fine (large). In this case, there are few restrictions on the shape of the heat generation distribution to be formed, and heat generation distributions of various shapes can be formed accurately and smoothly. Therefore, in the present embodiment, it is possible to accurately correct higher-order aberrations of the concave reflecting mirror CM9.
[0071]
Next, a tenth embodiment of the present invention will be described with reference to FIG.
This embodiment is a modification of the ninth embodiment, in which the variable heating device 181 shown in FIGS. 17 and 18 is disposed on the back surface of the concave reflecting mirror CM10, and one surface of the device 181 ( A heat sink 191 (liquid-cooled heat sink) is disposed on the surface facing the reflecting mirror CM10. The heat sink 191 removes the heat of the concave reflecting mirror CM10 uniformly within the surface with the device 181 interposed therebetween, and liquid refrigerant is circulated and supplied to the heat sink 191 via a refrigerant supply means (not shown). .
[0072]
With the above configuration, in the present embodiment, as in the ninth embodiment, by forming a predetermined heat generation distribution in the variable heat generation device 181, aberrations that occur in the concave reflecting mirror CM <b> 10 (reflection surface 190) are eliminated or corrected. The In the present embodiment, since the heat of the concave reflecting mirror CM10 is uniformly removed in the plane by the heat sink 191, uniform thermal expansion of the concave reflecting mirror CM and rotationally symmetric aberration fluctuations are suppressed.
[0073]
Next, an eleventh embodiment of the present invention will be described with reference to FIG.
The present embodiment is a modification of the ninth embodiment, and a variable heating device 201 similar to that shown in FIGS. 17 and 18 is disposed inside the concave reflecting mirror CM11. An arbitrary heat generation distribution is formed on the surface of the device 201 via the controller 202. Note that the variable heat generating device 201 is preferably planar and as thin as possible. The device 201 is embedded in the concave reflecting mirror CM11. For example, when the reflecting mirror is a ceramic, the device 201 is formed on a substrate molded to a predetermined thickness, and the substrate is further molded thereon to form the reflecting surface 200. This is done by forming. Alternatively, the concave reflecting mirror CM11 may be divided into a plurality of parts, and then integrated by sandwiching the device 201 therebetween.
[0074]
With the above configuration, in the present embodiment, similarly to the ninth embodiment, by forming a predetermined heat distribution in the variable heat generating device 201, the aberration generated in the concave reflecting mirror CM11 (reflecting surface 200) is eliminated or corrected. be able to. In the present embodiment, since the variable heat generating device 201 is disposed inside the concave reflecting mirror CM11, the accuracy of aberration correction is high. That is, since the device 201 which is a heat source for correcting aberration is close to the reflecting surface 200 which is a generation part of irradiation heat, it is possible to correct aberration with higher accuracy. In addition, there is an advantage that heat is difficult to escape from the device 201 which is a heat source for correcting aberrations, and heat efficiency is high.
[0075]
Next, a twelfth embodiment of the present invention will be described with reference to FIG.
The present embodiment is a modification of the eleventh embodiment, and a variable heating device 211 similar to that shown in FIG. 20 is disposed inside the concave reflecting mirror CM12. An arbitrary heat generation distribution is formed on the surface of the device 211 via the controller 212. In the present embodiment, unlike the eleventh embodiment, the variable heat generating device 211 is formed to be curved so as to be substantially parallel to the reflecting surface 210 of the concave reflecting mirror CM12.
[0076]
With the above configuration, in this embodiment, the same advantages as those in the eleventh embodiment can be obtained, and the accuracy of aberration correction can be improved. That is, the surface (heat generation surface) of the device 211 that is a heat source for correcting aberrations is disposed substantially parallel to the reflection surface 210 of the concave reflecting mirror CM12, so that the heat generation surface of the device 211 is irradiated over the entire area. As a result, it becomes possible to correct the aberration with higher accuracy.
[0077]
Next, a thirteenth embodiment of the present invention will be described with reference to FIG.
In the above-described embodiments, the aberration correction heating element (heat source) is in contact with the concave reflecting mirror, whereas in this embodiment, the aberration correcting heat source is connected to the concave reflecting mirror CM13. It is characterized by being arranged in a non-contact manner. In this embodiment, a heating illumination system 221 that irradiates an energy beam different from the exposure beam IL is used as a heat source for aberration correction.
[0078]
The heating illumination system 221 irradiates the back surface of the concave reflecting mirror CM13 with an energy beam HB having a predetermined wavelength, and the irradiation energy density distribution of the beam HB is substantially inversely proportional to the irradiation energy density distribution of the exposure beam IL. It has become. That is, the beam HB from the heating illumination system 221 has a high energy density at the center and a low energy at the periphery. Then, due to this substantially inversely proportional relationship, the sum of the heat generation distribution due to the irradiation energy of the exposure beam IL and the heat generation distribution due to the beam HB from the heating illumination system 221 is indicated by a two-dot chain line in FIG. As a result, non-rotationally symmetric aberration fluctuations associated with the irradiation of the exposure beam IL are suppressed.
[0079]
That is, in the present embodiment, the aberration caused by the thermal deformation of the concave reflecting mirror CM13 due to the irradiation heat of the exposure beam IL is eliminated or corrected by the heating of the concave reflecting mirror CM13 by the beam HB from the heating illumination system 221. Further, in this embodiment, since the aberration correction heat source is disposed in a non-contact manner with respect to the concave reflecting mirror CM13, the configuration is simplified and the aberration of the concave reflecting mirror CM13 due to assembly deformation occurs. Hateful.
[0080]
Here, for example, the heating illumination system 221 is configured to irradiate a large number of spot beams over the entire area of the concave reflecting mirror CM13 while distributing the irradiation positions and controlling the irradiation energy of each beam. Alternatively, the heating illumination system 221 is configured to irradiate a single beam over the entire area of the concave reflecting mirror CM13 and to control the irradiation energy density distribution of the beam. With the above configuration, the heating illumination system 221 can form an arbitrary irradiation energy density distribution with respect to the beam HB irradiated to the concave reflecting mirror CM13.
[0081]
Further, the beam HB irradiated from the heating illumination system 221 may have the same wavelength as the exposure beam IL or may have a different wavelength (including low-frequency electromagnetic waves). Further, in order to promote heating, a surface treatment for improving the endothermic characteristics may be applied to the back surface of the concave reflecting mirror CM13. Note that the irradiation energy density distribution of the aberration correcting beam HB is preferably determined in consideration of energy loss in the concave reflecting mirror CM. Further, as in this example, the method of correcting the aberration of the optical member (concave reflecting mirror) by irradiating with a beam different from the exposure beam can be applied to general aberration (for example, shape error) not caused by the exposure beam irradiation. The present invention can also be applied to correction of aberrations accompanying this, aberrations associated with assembly deformation, and the like.
[0082]
Next, a fourteenth embodiment of the present invention will be described with reference to FIG.
Similar to the thirteenth embodiment, the present embodiment includes a heating illumination system 226 that irradiates the concave reflecting mirror CM14 with the aberration correcting energy beam HB, and the irradiation energy density of the beam HB on the reflecting surface 225. The distribution is substantially inversely proportional to the irradiation energy density distribution of the exposure beam IL. In the present embodiment, unlike the thirteenth embodiment, the beam HB from the heating illumination system 226 is applied to the reflecting surface 225 of the concave reflecting mirror CM14. In the present embodiment, the beam HB from the heating illumination system 226 and its reflected beam are configured not to reach the wafer.
[0083]
With the above configuration, in the present embodiment, the concave reflecting mirror CM14 is heated by the beam HB from the heating illumination system 226, whereby the aberration of the concave reflecting mirror CM14 due to the irradiation heat of the exposure beam IL is eliminated or corrected. In the present embodiment, the aberration correction beam HB is directly applied to the reflection surface 225, which is a generation part of the irradiation heat of the exposure beam IL, so that the aberration can be corrected with higher accuracy. In addition, since the correction aberration beam HB is directly irradiated onto the reflection surface 225 to be corrected, there is an advantage that energy loss is less than in the case where the beam is irradiated onto the back surface of the concave reflecting mirror.
[0084]
In the thirteenth and fourteenth embodiments, the aberration correction beam HB is irradiated during exposure in which the exposure beam IL is irradiated on the wafer and in non-exposure in which the exposure beam IL is not irradiated on the wafer. Only one of them or both of them may be used.
[0085]
Next, in each of the embodiments described above, F ₂ Although the exposure apparatus using a laser light source has been described, there is a high possibility that there is no optical glass that can be used when the wavelength of the exposure beam becomes ultraviolet or X-ray with a shorter wavelength. In this case, it is conceivable to employ a so-called catadioptric reduction optical system in which the projection optical system is constituted only by a reflection system. Note that a technique that employs a catadioptric reduction optical system as a projection optical system is described, for example, in the direction of JP-A-2002-006221.
[0086]
FIG. 24 is a view showing the schematic arrangement of an exposure apparatus E that employs a catadioptric reduction optical system as a projection optical system. In this exposure apparatus E, light (EUV light) in a soft X-ray region having a wavelength of about 5 to 15 nm is used as the exposure beam EL. The exposure apparatus E will be described below.
[0087]
In FIG. 24, the exposure apparatus E displays an illumination optical system IU that illuminates the light beam from the light source 230 onto the reticle R supported by the reticle stage RS, and an image of the pattern of the reticle R illuminated with the exposure beam EL on the wafer W. A projection optical system PL for projecting onto the wafer W, and a wafer stage WS for supporting the wafer W. Since the EUV light that is the exposure beam in the present embodiment has a low transmittance to the atmosphere, the optical path through which the EUV light passes is covered by the vacuum chamber VC and is blocked from the outside air.
[0088]
In the illumination optical system IU, the light source 230 has a function of supplying laser light having a wavelength in the infrared region to the visible region, and for example, a YAG laser or an excimer laser by semiconductor laser excitation is used. This laser light is condensed by the first condensing optical system 231 and condensed at the position 232. The nozzle 233 ejects a gaseous object toward the position 232, and the ejected object receives high-intensity laser light at the position 232. At this time, the ejected object becomes high temperature by the energy of the laser beam, is excited to a plasma state, and emits EUV light when transitioning to a low potential state.
[0089]
Around the position 232, an elliptical mirror 234 that constitutes a second condensing optical system is disposed, and the elliptical mirror 234 is positioned so that its first focal point substantially coincides with the position 232. A multilayer film for reflecting EUV light is provided on the inner surface of the elliptical mirror 234. The EUV light reflected here is once condensed at the second focal point of the elliptical mirror 234, and then the third collection. It goes to a parabolic mirror 235 as a collimating mirror constituting the optical optical system. The parabolic mirror 235 is positioned so that its focal point substantially coincides with the second focal position of the elliptical mirror 234, and a multilayer film for reflecting EUV light is provided on the inner surface thereof.
[0090]
The EUV light emitted from the parabolic mirror 235 travels toward the reflective fly's eye optical system 236 as an optical integrator in a substantially collimated state. The reflective fly's eye optical system 236 includes a first reflective element group 236a in which a plurality of reflective surfaces are integrated, and a second reflective surface having a plurality of reflective surfaces corresponding to the multiple reflective surfaces of the first reflective element group 236a. And an element group 236b. A multilayer film for reflecting the EUV light is also provided on a plurality of reflecting surfaces constituting the first and second reflecting element groups 236a and 236b.
[0091]
The collimated EUV light from the parabolic mirror 235 is wavefront divided by the first reflecting element group 236a, and the EUV light from each reflecting surface is condensed to form a plurality of light source images. A plurality of reflecting surfaces of the second reflecting element group 236b are positioned near each of the positions where the plurality of light source images are formed, and the reflecting surfaces of the second reflecting element group 236b are It essentially functions as a field mirror. Thus, the reflective fly's eye optical system 236 forms a large number of light source images as secondary light sources based on the substantially parallel light flux from the parabolic mirror 235. Such a reflective fly-eye optical system 236 has been proposed in Japanese Patent Application No. 10-47400 by the present applicant.
[0092]
In this exposure apparatus E, in order to control the shape of the secondary light source, a σ stop AS1 as a first aperture stop is provided in the vicinity of the second reflective element group 236b. The σ stop AS1 is formed of, for example, a plurality of openings having different shapes in a turret shape. Then, the σ aperture control unit ASC1 controls which opening is arranged in the optical path.
[0093]
The EUV light from the secondary light source formed by the reflective fly's eye optical system 236 travels toward the condenser mirror 237 positioned so that the vicinity of the secondary light source position is the focal position, and is reflected by the condenser mirror 237. After being collected, the light reaches the reticle R via the optical path bending mirror 238. A multilayer film for reflecting EUV light is provided on the surfaces of the condenser mirror 237 and the optical path bending mirror 238. The condenser mirror 237 collects EUV light emitted from the secondary light source and uniformly illuminates the reticle R.
[0094]
Note that in this exposure apparatus E, the illumination optical system IU is not a non-illuminated system in order to spatially separate the optical path between the illumination light directed to the reticle R and the EUV light reflected by the reticle R and directed to the projection optical system PL. The telecentric system and the projection optical system PL are also non-telecentric optical systems on the reticle side.
[0095]
On the reticle R, a reflective film made of a multilayer film that reflects EUV light is provided, and this reflective film has a pattern according to the shape of the pattern to be transferred onto the wafer W. The EUV light that is reflected by the reticle R and includes the pattern information of the reticle R enters the projection optical system PL.
[0096]
The projection optical system PL is composed of six reflecting mirrors M1 to M6, and is in the optical path between the first reflecting mirror M1 and the reticle R (between the vertices of the reflecting mirror M1 and the reflecting mirror M2). A variable aperture stop AS as a second aperture stop is disposed. The variable aperture stop AS is configured such that the aperture diameter is variable, and the aperture is controlled by the variable aperture stop control unit ASC2.
[0097]
A field stop FS is disposed at an intermediate image forming position in the optical path between the second reflecting mirror M2 and the third reflecting mirror M3. Note that the reflecting mirrors M1 to M6 constituting the projection optical system PL are formed by providing a multilayer film that reflects EUV light on a substrate.
[0098]
The EUV light reflected by the reticle R passes through the projection optical system PL and enters a predetermined reduction magnification β (for example, | β | = 1/4, 1/5) in an arc-shaped exposure area on the wafer W. , 1/6), a reduced image of the pattern of the reticle R is formed. In the present embodiment, the shape of the exposure region is defined by the field stop FS provided in the projection optical system PL.
[0099]
The reticle R is supported by a reticle stage RS that can move at least along the Y direction, and the wafer W is supported by a wafer stage WS that can move along the XYZ directions. The movement of the reticle stage RS and the wafer stage WS is controlled by the reticle stage control unit RSC and the substrate stage control unit, respectively. During the exposure operation, the illumination optical system IU irradiates the reticle R with EUV light, and the reticle R and the wafer W are projected onto the projection optical system PL at a predetermined speed determined by the reduction magnification of the projection optical system PL. Move by ratio. Thereby, the pattern of the reticle R is scanned and exposed within a predetermined shot area on the wafer W.
[0100]
In this exposure apparatus E, the σ stop AS1, the variable aperture stop AS, and the field stop FS are preferably made of a metal such as Au, Ta, or W in order to sufficiently block EUV light. In addition, a multilayer film as a reflective film is formed on the reflective surface of each reflective mirror described above in order to reflect EUV light. This multilayer film is formed by laminating a plurality of substances of molybdenum, ruthenium, rhodium, silicon, and silicon oxide.
[0101]
In the exposure apparatus E configured as described above, the space in which the six reflecting mirrors M1 to M6 constituting the projection optical system PL are arranged is controlled to a vacuum. Therefore, since there is almost no cooling effect by convective heat transfer, the temperature control is important in order to suppress thermal deformation of the reflecting mirrors M1 to M6. Also for these reflecting mirrors M1 to M6, the temperature of the reflecting mirrors M1 to M6 can be controlled well by attaching a heat sink via a heat conducting spring in the same manner as shown in the previous embodiment. It is possible to prevent deterioration of characteristics.
[0102]
FIG. 25 is a flowchart of production of a micro device (semiconductor device) using the exposure apparatus according to one embodiment of the present invention. As shown in FIG. 12, first, in step S300 (design step), functional design of a device (for example, circuit design of a semiconductor device) is performed, and pattern design for realizing the function is performed. Subsequently, in step S301 (mask manufacturing step), a mask is manufactured based on the designed circuit pattern. On the other hand, in step S302 (wafer manufacturing step), a wafer is manufactured using a material such as silicon.
[0103]
Next, in step S303 (wafer process step), an actual circuit or the like is formed on the wafer by lithography using the mask and wafer prepared in steps S300 to S302. Next, in step S304 (assembly step), the wafer processed in step S303 is formed into chips. This step S304 includes processes such as an assembly process (dicing, bonding), a packaging process (chip encapsulation), and the like. Finally, in step S305 (inspection step), inspections such as an operation confirmation test and a durability test of the device manufactured in step S304 are performed. After these steps, the device is completed and shipped.
[0104]
Note that the operation procedures shown in the above-described embodiment, or the shapes and combinations of the constituent members are examples, and can be variously changed based on process conditions, design requirements, and the like without departing from the gist of the present invention. .
[0105]
In the case of using far ultraviolet rays such as an excimer laser, a material that transmits far ultraviolet rays such as quartz, fluorite, quartz doped with fluorine, barium fluoride, lithium fluoride, or the like is used as the projection optical system.
[0106]
In addition, the occurrence of degassing can be suppressed by using a material such as stainless steel (SUS) whose surface roughness is reduced by a process such as polishing for each casing, lens barrel, specific gas supply pipe, and the like.
[0107]
An exposure apparatus to which the present invention is applied is limited to a scanning exposure method (for example, a step-and-scan method) in which a mask (reticle) and a substrate (wafer) are relatively moved with respect to an exposure illumination beam. Instead, a static exposure method in which the mask pattern is transferred onto the substrate while the mask and the substrate are substantially stationary, for example, a step-and-repeat method may be used. Further, the present invention can also be applied to a step-and-stitch type exposure apparatus that transfers a pattern to a plurality of shot regions whose peripheral portions overlap each other on the substrate. Further, the projection optical system may be any one of a reduction system, an equal magnification system, and an enlargement system, and may be any one of a catadioptric system and a reflection system. Furthermore, the present invention can be applied to, for example, a proximity type exposure apparatus that does not use a projection optical system.
[0108]
As a light source, F ₂ Not only a laser but also a KrF excimer laser with an oscillation wavelength of 248 nm, an ArF excimer laser with an oscillation wavelength of 193 nm, a laser emitting light belonging to the vacuum ultraviolet region with a wavelength of about 120 nm to about 180 nm, such as a krypton dimer laser (Kr with an oscillation wavelength of 146 nm) ₂ Laser), Argon dimer laser (Ar) with oscillation wavelength of 126 nm ₂ Laser) or the like may be used. In addition to a laser light source that emits ultraviolet light, a harmonic generator such as a YAG laser or a semiconductor laser, an SOR, a laser plasma light source, or the like may be used as the light source.
[0109]
The exposure apparatus to which the present invention is applied is not limited to the manufacture of semiconductor devices, but includes microdevices such as liquid crystal display elements, display apparatuses, thin film magnetic heads, imaging elements (CCDs, etc.), micromachines, and DNA chips. It may be used for manufacturing (electronic device) or for manufacturing a photomask or reticle used in an exposure apparatus.
[0110]
The present invention can be applied not only to an exposure apparatus but also to other manufacturing apparatuses (including an inspection apparatus) that include a light source device and are used in a device manufacturing process.
[0111]
When a linear motor is used for the wafer stage or reticle stage described above, either an air levitation type using air bearings or a magnetic levitation type using Lorentz force or reactance force may be used. The stage may be a type that moves along a guide, or may be a guideless type that does not have a guide. Further, when a planar motor is used as the stage drive system, one of the magnet unit (permanent magnet) and the armature unit is connected to the stage, and the other of the magnet unit and the armature unit is connected to the moving surface side of the stage ( It may be provided on the surface plate or base.
[0112]
Further, the reaction force generated by the movement of the wafer stage may be released mechanically to the floor (ground) using a frame member as described in JP-A-8-166475. The present invention can also be applied to an exposure apparatus having such a structure.
[0113]
The reaction force generated by the movement of the reticle stage may be mechanically released to the floor (ground) using a frame member as described in JP-A-8-330224. The present invention can also be applied to an exposure apparatus having such a structure.
[0114]
An exposure apparatus to which the present invention is applied assembles various subsystems including the constituent elements recited in the claims of the present application so as to maintain predetermined mechanical accuracy, electrical accuracy, and optical accuracy. It is manufactured by. To ensure these various accuracies, before and after this assembly, various optical systems are adjusted to achieve optical accuracy, various mechanical systems are adjusted to achieve mechanical accuracy, and various electrical systems are Adjustments are made to achieve electrical accuracy. The assembly process from the various subsystems to the exposure apparatus includes mechanical connection, electrical circuit wiring connection, pneumatic circuit piping connection, and the like between the various subsystems. Needless to say, there is an assembly process for each subsystem before the assembly process from the various subsystems to the exposure apparatus. When the assembly process of the various subsystems to the exposure apparatus is completed, comprehensive adjustment is performed to ensure various accuracies as the entire exposure apparatus. The exposure apparatus is preferably manufactured in a clean room where the temperature, cleanliness, etc. are controlled.
[0115]
As described above, the preferred embodiments according to the present invention have been described with reference to the accompanying drawings, but the present invention is not limited to the examples. It is obvious for those skilled in the art that various changes or modifications can be conceived within the scope of the technical idea described in the claims. It is understood that it belongs to.
[0116]
【The invention's effect】
As described above, according to the optical apparatus of the present invention, the aberration of the optical member can be corrected or eliminated with a simple configuration by heating the optical member via the heating element.
Further, according to the exposure apparatus of the present invention, the pattern image of the mask can be accurately transferred onto the substrate by the optical apparatus with improved optical characteristics.
Further, according to the device manufacturing method of the present invention, it is possible to provide a device in which the accuracy of the pattern to be formed is improved by improving the exposure accuracy.
[Brief description of the drawings]
FIG. 1 is a diagram showing an overall configuration of a reduction projection type exposure apparatus for manufacturing a semiconductor device according to an embodiment provided with an optical apparatus according to the present invention as a projection optical system.
FIG. 2 is a diagram showing an example of the configuration of a projection optical system.
FIG. 3 is a diagram showing an example of the configuration of a projection optical system.
FIG. 4 is a plan view schematically showing the structure of a concave reflecting mirror.
FIG. 5 is a cross-sectional view schematically showing the structure of a concave reflecting mirror.
6A is a plan view schematically showing an irradiation region (irradiation field) of an exposure beam with respect to a concave reflecting mirror, FIG. 6B is a diagram schematically showing an irradiation energy density distribution in the irradiation region, and FIG. ) Is a diagram showing an electrical heating distribution due to a plurality of electrical resistances which are heating elements embedded in the concave reflecting mirror.
FIG. 7 is a flowchart showing an example of a procedure for correcting aberrations of the entire optical system.
FIG. 8 is a diagram for explaining a second embodiment of the present invention.
FIG. 9 is a diagram for explaining a third embodiment of the present invention.
FIG. 10 is a diagram for explaining a fourth embodiment of the present invention.
FIG. 11 is a diagram for explaining a fifth embodiment of the present invention.
FIG. 12 is a diagram for explaining a fifth embodiment of the present invention.
FIG. 13 is a diagram for explaining a sixth embodiment of the present invention.
FIG. 14 is a diagram for explaining a seventh embodiment of the present invention.
FIG. 15 is a diagram for explaining an eighth embodiment of the present invention.
FIG. 16 is a diagram for explaining an eighth embodiment of the present invention;
FIG. 17 is a diagram for explaining a ninth embodiment of the present invention.
FIG. 18 is a diagram for explaining a ninth embodiment of the present invention.
FIG. 19 is a diagram for explaining a tenth embodiment of the present invention.
FIG. 20 is a diagram for explaining an eleventh embodiment of the present invention.
FIG. 21 is a diagram for explaining a twelfth embodiment of the present invention.
FIG. 22 is a diagram for explaining a thirteenth embodiment of the present invention.
FIG. 23 is a diagram for explaining a fourteenth embodiment of the present invention.
FIG. 24 is a view showing the schematic arrangement of an exposure apparatus that employs a catadioptric reduction optical system as a projection optical system.
FIG. 25 is a flowchart of semiconductor device production using the exposure apparatus according to an embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10, E ... Exposure apparatus, R ... Reticle (mask), W ... Wafer (substrate), CM, CM2-CM6 ... Concave reflector (optical member), 21, IU ... Illumination optical system (illumination system), PL ... Projection Optical system, 101, 111, 121, 131, 141, 151, 161a, 161b, 171a to 171d ... electric resistance (heating element), 135, 136 ... electric resistance group, 181, 201, 211 ... variable heating device (heating element) , 191... Heat sink, 221... Heating illumination system (heating element), HB.

Claims (11)

An optical device comprising an optical member disposed on an optical path of an energy beam,
A heating element for heating the optical member;
The optical device, wherein the heating element has a heat generation distribution based on the aberration of the optical member. The aberration of the optical member includes at least one of an aberration associated with a shape error, an aberration associated with assembly deformation, and an aberration associated with thermal deformation caused by irradiation of the energy beam. Optical device. The optical element according to claim 1, wherein the heating element includes a plurality of electric resistors that are arranged in a plurality of locations of the optical member and that control the amount of supplied current. apparatus. The optical apparatus according to claim 3, further comprising a plurality of electrical resistance groups including the plurality of electrical resistances and spaced apart from each other. The optical device according to claim 1, wherein the heating element includes an electric resistance having a cross-sectional shape based on an aberration of the optical member. The optical member has a reflecting surface that reflects the energy beam,
The optical device according to any one of claims 1 to 5, wherein the heating element is disposed on a back side of the reflecting surface. The optical device according to claim 6, wherein a back side of the reflecting surface is thinned. The optical device according to any one of claims 1 to 7, wherein the optical member is molded so as to include the heating element. The optical device according to any one of claims 1 to 8, wherein a heat generation distribution of the heating element is controlled according to an irradiation state of the energy beam to the optical member. At least one of an illumination system that illuminates a mask on which a pattern is formed with an energy beam and a projection optical system that transfers the pattern of the mask onto a substrate are according to any one of claims 1 to 9. An exposure apparatus comprising the optical device described above. A device manufacturing method comprising: transferring a device pattern formed on a mask onto a substrate using the exposure apparatus according to claim 10.

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