TWI795646B - Exposure apparatus, exposure method, and method of manufacturing article - Google Patents

Abstract

An exposure apparatus includes a first temperature controller for controlling a temperature distribution on an optical element of a projection optical system, and a second temperature controller for controlling a temperature distribution on an optical element of the projection optical system, wherein in a first period in which the exposure operation is executed, at least one of the first temperature controller and the second temperature controller operates to reduce a change in an aberration of the projection optical system due to the exposure operation being executed, and in a second period which follows the first period and in which the exposure operation is not executed, at least one of the first temperature controller and the second temperature controller operates to reduce a change in an aberration due to the exposure operation not being executed.

Description

Exposure apparatus, exposure method, and method of manufacturing article

The present invention relates to exposure equipment, exposure methods, and methods of manufacturing articles.

In the manufacture of articles such as semiconductor devices, exposure equipment that illuminates a master plate (reticle or mask) with an illumination optical system projects a pattern of the master plate onto a substrate through a projection optical system, and exposes the substrate. Since the imaging characteristic of the projection optical system changes according to the irradiation operation of the exposure light, the imaging characteristic can be corrected in the exposure apparatus by controlling the posture and position of the optical element. The aberration components that can be corrected by controlling the orientation and position of the optical elements are limited, and non-rotationally symmetric imaging characteristics such as astigmatism cannot be corrected. Japanese Patent No. 5266641 discloses that by using an adjustment mechanism to adjust the temperature of the optical component to change the temperature distribution on the optical component and adjust the optical characteristics of the projection optical system, the optical component is arranged on the pupil plane of the projection optical system. )nearby.

Japanese Patent No. 5266641 only discloses adjusting the imaging characteristics of the projection optical system by an adjustment mechanism during the exposure period, but does not disclose the adjustment of the imaging characteristics by the adjustment mechanism during the non-exposure period. If the adjustment by the adjustment mechanism is stopped during the period in which the exposure operation is not performed, there is a possibility that a large correction residual error will be generated when the exposure operation is restarted. This is because the temporal change of the imaging characteristic after the exposure operation ends is different from the temporal change of the imaging characteristic after the adjustment by the adjustment mechanism ends.

The present invention provides a technique that facilitates correcting the aberration of the projection optical system with high precision even in the case of restarting the exposure operation after the exposure operation has been stopped.

A first aspect of the present invention provides an exposure apparatus that performs an exposure operation to expose a substrate via a projection optical system. This exposure apparatus includes: a first temperature controller configured to control temperature distribution on an optical element of the projection optical system; and a second temperature controller configured to control temperature distribution on the optical element of the projection optical system. In the first period in which the exposure operation is performed, at least one of the first temperature controller and the second temperature controller operates to reduce a change in aberration of the projection optical system caused by performing the exposure operation, and, during the first After the period and in a second period in which the exposure operation is not performed, at least one of the first temperature controller and the second temperature controller operates to reduce a change in aberration caused by not performing the exposure operation.

A second aspect of the present invention provides an exposure method that performs an exposure operation to expose a substrate via a projection optical system, the exposure method including: performing a first process to perform an exposure operation during a first period of time by using at least one of the first temperature controller and the second temperature controller to control the temperature distribution on the optical elements of the projection optical system so that a variation in aberration of the projection optical system due to performing the exposure operation is reduced, and performing a second process to control the temperature on the optical element of the projection optical system by using at least one of the first temperature controller and the second temperature controller in a second period in which the exposure operation is not performed after the first period The temperature distribution of , so that the change in the aberration of the projection optical system caused by not performing the exposure operation is reduced.

A third aspect of the present invention provides a method of manufacturing an article, the method comprising: exposing a substrate by means of an exposure apparatus defined as the first aspect or the second aspect of the present invention; developing the substrate exposed in the exposure; and processing the substrate developed in developing; wherein an article is obtained from the substrate processed in processing.

Further features of the invention will become apparent from the following description of exemplary embodiments with reference to the accompanying drawings.

Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. Note that the following examples are not intended to limit the scope of the claimed invention. A number of features have been described in the embodiments, but it is not construed as a limitation of the invention requiring all of these features, and a number of such features may be combined as appropriate. In addition, in the attached drawings, the same reference numerals are given to the same or similar configurations, and their repeated descriptions are omitted.

Fig. 1 schematically shows the arrangement of an exposure apparatus EXP according to a first embodiment. The exposure apparatus EXP schematically performs an exposure operation of exposing the substrate 110 via the projection optical system 107 . In the specification and drawings, directions are indicated based on an XYZ coordinate system, where, in FIG. 1 , a plane parallel to a surface on which the substrate 110 is disposed is set as an X-Y plane. The exposure apparatus EXP includes a light source 102 , an illumination optical system 104 , a projection optical system 107 , and a controller 100 . In the exposure operation, the illumination optical system 104 illuminates the original plate 106 with light (exposure light) from the light source 102 , and the pattern of the original plate 106 is projected onto the substrate 110 by the projection optical system 107 to expose the substrate 110 . The exposure apparatus EXP may be formed as an exposure apparatus that exposes the substrate 110 in a state where the original plate 106 and the substrate 110 are stopped to be stationary, or may be formed as an exposure apparatus that exposes the substrate 110 while scanning the original plate 106 and the substrate 110 . Generally speaking, the substrate 110 includes a plurality of shot regions, and an exposure operation is performed on each shot region.

The light source 102 may include, for example, an excimer laser, but may also include other light emitting devices. Excimer lasers can generate light, for example, with a wavelength of 248 nm or 193 nm, but can also generate light at other wavelengths. The projection optical system 107 may include an optical element 109 , and a temperature adjustment unit 108 that adjusts the temperature distribution on the optical element 109 . The temperature adjustment unit 108 can reduce the variation of the optical characteristics of the projection optical system 107 by applying thermal energy to the optical element 109 to change the refractive index distribution and/or surface shape of the optical element 109 . The thermal energy applied to the optical element 109 by the temperature adjustment unit 108 may include positive energy and negative energy. Applying positive energy to the optical element 109 indicates heating of the optical element 109 , while applying negative energy to the optical element 109 indicates cooling of the optical element 109 .

The temperature adjustment unit 108 may be arranged to adhere tightly to the optical element 109, and in this case the thermal energy transfer between the temperature adjustment unit 108 and the optical element 109 will be efficient. Alternatively, the temperature adjustment unit 108 may be arranged to be spaced apart from the optical element 109, and this arrangement is advantageous in that the temperature adjustment unit 108 does not apply mechanical forces to the optical element 109, and the temperature adjustment unit 108 It is advantageous that the optical element 109 will not be damaged by the optical element 108 due to scratches or the like.

It is preferable to arrange the temperature adjustment unit 108 outside the effective diameter (optical path) of the optical element 109 so that the temperature adjustment unit 108 will not block the light irradiation to the substrate 110 . For example, the temperature adjustment unit 108 may be arranged on the outer edge portion of the lens serving as the optical element 109 , the front surface of the lens, or the rear surface of the lens. Alternatively, the temperature adjustment unit 108 may be arranged inside the effective diameter within a range not affecting the optical performance of the projection optical system 107 . As an example of such an arrangement, for example, a thin heating wire may be arranged in the effective diameter of the optical element, or a heat transfer element having high light transmittance may be arranged in the effective diameter of the optical element.

Although it is preferable to arrange the optical element 109 at or near the pupil plane of the projection optical system 107 with the temperature adjustment unit 108 arranged on the outer periphery of the optical element 109, the temperature adjustment unit 108 may also be arranged to be spaced apart from the pupil plane of the projection optical system 107 . The temperature adjustment unit 108 may include a plurality of temperature controllers including a first temperature controller for controlling the temperature distribution on the optical element 109 of the projection optical system 107, and a first temperature controller for controlling the temperature distribution on the optical element 109 of the projection optical system 107. Second temperature controller for temperature distribution. In the first period in which the exposure operation is performed, the first temperature controller is operable to reduce changes in the optical characteristics of the projection optical system 107 caused by performing the exposure operation. In a second period after the first period and in which the exposure operation is not performed, the second temperature controller is operable to reduce a change in optical characteristics of the projection optical system 107 caused by not performing the exposure operation. Alternatively, in the first period in which the exposure operation is performed, at least one of the first temperature controller and the second temperature controller is operable to reduce a change in optical characteristics of the projection optical system 107 due to performing the exposure operation. In addition, in a second period in which the exposure operation is not performed after the first period, at least one of the first temperature controller and the second temperature controller is operable to reduce the distortion of the projection optical system 107 caused by not performing the exposure operation. changes in optical properties. Among the plurality of temperature controllers (the first temperature controller and the second temperature controller), the amount of thermal energy applied to the optical element 109 and the duration of application are individually controlled for each temperature controller, and thus can be controlled Temperature distribution on optical element 109 . The controller 100 can control a plurality of temperature controllers (a first temperature controller and a second temperature controller). The optical element 109 whose temperature distribution is controlled by the first temperature controller may be the same or different from the optical element 109 whose temperature distribution is controlled by the second temperature controller.

The temperature adjustment unit 108 can change the thermal energy applied to the optical element 109 in synchronization with the optical characteristics of the projection optical system 107 that change with the lapse of time in a period in which an exposure operation is performed and in a period in which an exposure operation is not performed. In this case, the information necessary for the control operation of the temperature adjustment unit 108 can be based on the optical characteristics of the projection optical system 107 by measuring the imaging plane of the projection optical system 107 (the surface on which the substrate 110 is to be arranged). And the results obtained to produce. Alternatively, information required for the control operation of the temperature adjustment unit 108 may be determined in advance through measurement operations or the like. The operation of controlling the application of heat energy to the optical element 109 performed by the temperature adjusting unit 108 can be realized by controlling the value of the current applied to the heating wire, for example, in the case that the temperature adjusting unit 108 includes a heating wire. Alternatively, the operation of controlling the application of thermal energy to the optical element 109 performed by the temperature adjustment unit 108 may be achieved by, for example, a physical distance or a thermal distance between the optical element 109 and the temperature adjustment unit 108 .

The controller 100 can control the light source 102 , the illumination optical system 104 , the projection optical system 107 , and the temperature adjustment unit 108 . More specifically, the controller 100 may be formed not only to control the exposure operation but also to control the temperature adjustment unit 108 in the first period and the second period. It can be formed by, for example, a PLD (abbreviation of Programmable Logic Device) such as FPGA (abbreviation of Field Programmable Gate Array), an ASIC (abbreviation of Application Specific Integrated Circuit), a general-purpose or special-purpose computer embedded with a program, or these A combination of all or a part of the components forms the controller 100 .

2A and 2B respectively show examples of the arrangement of the optical element 109 and the temperature adjustment unit 108 in the exposure apparatus EXP according to the first embodiment. Optical element 109 may include lens 201 . The temperature adjustment unit 108 may include a first temperature controller 204 formed by heater elements 204a and 204b, and a second temperature controller 203 formed by heater elements 203a and 203b. Each of the heater elements 204 a , 204 b , 203 a , and 203 b may have an arc shape corresponding to an arc of 1/4 of the circumference of the lens 201 . Each of the heater elements 204 a , 204 b , 203 a , and 203 b may be formed of a flexible cable including a heating wire that generates heat when a current is applied to the heating wire and forms a temperature distribution on the lens 201 .

For example, each of the heater elements 204 a , 204 b , 203 a , and 203 b may be arranged to be spaced apart from the planar portion of the lens 201 by 10 μm to 100 μm. Heat generated by each of heater elements 204a, 204b, 203a, and 203b may be transferred to lens 201 via medium 205 between lens 201 and heater elements 204a, 204b, 203a, and 203b. The medium 205 may be, for example, a gas such as air, nitrogen, or the like. The heater elements 204a, 204b, 203a and 203b need not directly face the lens 201 via the medium 205 . For example, each of the heater elements 204a, 204b, 203a, and 203b may have a structure in which a heating wire is sandwiched by a metal element having high thermal conductivity.

In the example of FIG. 2B , the heater elements 204 a , 204 b , 203 a and 203 b are arranged on the planar portion of the lens 201 (on the side of the illumination optical system 104 ). However, the heater elements 204 a , 204 b , 203 a , and 203 b may be arranged below the lens 201 (on the side of the substrate 110 ), or on an outer edge portion of the lens 201 . Lens 201 may have a heated surface 206 that is heated by heater elements 204a, 204b, 203a, and 203b. The heated surface 206 may be flat or curved. The heated surface 206 may be, for example, a roughened surface (a surface in the form of ground glass).

FIG. 3A illustrates the temperature distribution on the lens 201 that has been heated by the first temperature controller 204 . At this time, astigmatism is generated in the positive direction on the surface of the substrate 110 . FIG. 3B illustrates the temperature distribution on the lens 201 heated by the second temperature controller 203 . The temperature distribution of FIG. 3B is a temperature distribution having an opposite phase to the temperature distribution of FIG. 3A . The temperature distribution of FIG. 3B produces astigmatism in the negative direction on the surface of the substrate 110 . In this way, positive astigmatism and negative astigmatism can be generated by heating the lens 201 by the first temperature controller 204 and the second temperature controller 203 . This type of arrangement is advantageous in that the temperature adjustment unit 108 can be simplified compared to an arrangement in which positive and negative astigmatism are generated by a combination of heating and cooling using elements such as Peltier elements. layout.

If the exposure apparatus EXP is applied here to a scanning exposure apparatus that scans the original plate 106 and the substrate 110 with respect to a long slit-shaped beam (exposure light) in the X direction, the light passing through the projection optical system 107 at the point of time of the exposure operation The intensity distribution of the light beam can be shown as the shaded part 401 in FIG. 4 . In this case, the temperature distribution generated on the lens 201 (optical element 109 ) by the absorption of the light beam will be different in the X direction and the Y direction. This may cause a large amount of astigmatism to be generated in the projection optical system 107 . Therefore, the astigmatism can be reduced by applying a temperature distribution to the lens 201 through the first temperature controller 204 . The astigmatism of the projection optical system 107 generated by the first temperature controller 204 has the opposite sign to the astigmatism of the projection optical system 107 generated when the lens 201 absorbs the light beam. Therefore, the astigmatism of the projection optical system 107 generated by the light beam absorbed by the lens 201 can be reduced by the astigmatism of the projection optical system 107 generated by the first temperature controller 204 . Note that the term “asttigmatism” hereinafter means the astigmatism of the projection optical system 107 unless otherwise specifically stated.

A change (time-varying characteristic) of astigmatism produced by the first temperature controller 204 may be different from a change (time-varying characteristic) of astigmatism produced by the lens 201 absorbing a light beam. In this case, the current supplied to the heating wire of the first temperature controller 204 is controlled by the first temperature controller 204 to control the variation of astigmatism so that the absorption of the light beam by the lens 201 can be canceled with high precision. resulting in astigmatism.

FIG. 5 illustrates temporal characteristics of changes in astigmatism. In FIG. 5 , "exposure time" indicates a first period including an exposure operation, and "non-exposure time" indicates a second period after the first period and a period in which an exposure operation is not performed. In a first example, the first period may be a period from the start of the initial exposure operation on the substrate until the end of the last exposure operation on the substrate. The second period may be a period from the end of the last exposure operation on the substrate. The second period is, for example, a period from the end of the last exposure operation on the substrate until the start of the first exposure operation on the next substrate. Here, the next substrate may be a substrate belonging to the same batch as the previous substrate, or a substrate that is the first substrate of the next batch. After a predetermined time elapses from the end of the execution of the last exposure operation, the second period may end, and the operation of the temperature adjustment unit 108 may be stopped. The first example is suitable for the case where the change in aberration between one shot region in the substrate and the next shot region of the substrate is negligible. In the second example, the first period is a period during which the exposure operation is performed on each shot area of the substrate, and the second period may include from the end of the exposure operation on one shot area of the substrate until the next exposure operation on the substrate. Period of start of the exposure operation of the shot area. The second example is suitable for cases where it is necessary to consider the change in aberration between one shot area of a given substrate and the next shot area of this given substrate. In a third example, the first period may be a period from the start of the initial exposure operation on the first substrate of the first batch until the final exposure operation on the last substrate of the first batch. The second period may be a period from the end of the last exposure operation on the last substrate of the first batch until the start of the initial exposure operation on the first substrate of the second batch following the first batch. Although the first, second, and third examples are different from each other in how to roughly set the exposure operation, these examples can be understood as having a common idea.

In FIG. 5 , the curve 501 a illustrates the variation of the astigmatism produced by the absorption of the light beam by the lens 201 during the first time period. As a desirable method of reducing or canceling the astigmatism produced by the absorption of the light beam by the lens 201, the first temperature controller 204 may be used to heat the lens 201 to produce astigmatism which changes according to a curve having the opposite sign to curve 501a. However, as illustrated by the curve 502a, if the first temperature controller 204 continuously heats the lens 201 at a predetermined temperature, the astigmatism generated by this heating operation tends to dissipate with a time constant slower than that of the curve 501a. Change. Therefore, the astigmatism shown by curve 501a cannot be completely corrected (cancelled), and a correction residual error as shown by curve 503a will result.

A similar phenomenon can also occur in the second period. Since the exposure operation is not performed in the second period, the light beam does not pass through the lens 201 . Therefore, although a change in temperature of the lens 201 due to absorption of light beams does not occur in the second period, the lens 201 is deformed due to heat dissipation from the lens 201, and thus the astigmatism changes with time. A curve 501b illustrates changes in astigmatism generated when heat generated due to absorption of a light beam is radiated (dissipated) from the lens 201 . The time constant of curve 501b may be the same as that of curve 501a.

When the heating of the lens 201 by the first temperature controller 204 is stopped simultaneously with the switching from the first period to the second period, the heat applied to the lens 201 by the first temperature controller 204 in the first period is radiates (dissipates) from the lens 201. Accordingly, the astigmatism can change in the manner of the curve 502b. The difference in time-varying characteristics as exists between the curve 501a and the curve 502a exists between the curve 501b and the curve 502b. Therefore, also in the second period, a correction residual error may be generated, as shown by the curve 503b.

其中，A是與從時間t起施加的熱量相關的量，G是與產生的像差量相關的係數，且K是與產生的像差量的時間常數相關的係數。或者，曲線501a、501b、502a和502b可以如由在時間t之產生的像差量φ(t)所表達的二階滯後系統的方式表達：

其中，τ1和τ2是與表達二階滯後的時間常數相關的係數，A是與從時間t起施加的熱量相關的量，G是與產生的像差量相關的係數，且K是與產生的像差量的時間常數相關的係數。然而，這些曲線可根據其他模型來表達。In general, the curves 501a, 501b, 502a, and 502b can be expressed as a first-order lag system expressed by the amount of aberration φ(t) produced at time t:

Here, A is an amount related to the amount of heat applied from time t, G is a coefficient related to the amount of generated aberration, and K is a coefficient related to the time constant of the generated amount of aberration. Alternatively, the curves 501a, 501b, 502a, and 502b may be expressed as a second-order hysteresis system expressed by the amount of aberration φ(t) produced at time t:

where τ1 and τ2 are coefficients related to the time constant expressing the second-order lag, A is a quantity related to the amount of heat applied from time t, G is a coefficient related to the amount of aberration produced, and K is a quantity related to the generated image A coefficient related to the time constant of the delta. However, these curves can be expressed according to other models.

In order to reduce correction residual errors due to such differences in time-varying characteristics, the controller 100 may control thermal energy applied to the lens 201 by the first temperature controller 204 and the second temperature controller 203 . This method will be described with reference to FIGS. 6A and 6B . In this method, the first temperature controller 204 and the second temperature controller 203 can be respectively based on the command value corresponding to the time elapsed from the start of the first period and the time corresponding to the time elapsed from the start of the second period. The command value of the time is used to control the thermal energy applied to the lens 201 . A current 601 to be applied to the heater elements 204 a and 204 b of the first temperature controller 204 and a current 602 to be applied to the heater elements 203 a and 203 b of the second temperature controller 203 are illustrated in FIG. 6A . The controller 100 may be arranged to supply the command value corresponding to the current 601 to the first temperature controller 204 as the command value corresponding to the time elapsed from the start of the first period. Likewise, the controller 100 may be arranged to supply to the second temperature controller 203 a command value corresponding to the current 602 as a command value corresponding to the time elapsed from the start of the second period. The change in astigmatism 603 produced by the absorption of the beam is illustrated in Fig. 6B. Also illustrated in FIG. 6B is the heating generated by the current applied to the heater elements 204a and 204b of the first temperature controller 204, and the current applied to the heater elements 203a and 203b of the second temperature controller 203. 604 changes in astigmatism. In addition, the variation of the corrected residual error 605 is also illustrated in FIG. 6B .

In this example, current is applied to the heater elements 204 a and 204 b of the first temperature controller 204 and current is not applied to the heater elements 203 a and 203 b of the second temperature controller 203 during the first period. On the other hand, in the second period, current is not applied to the heater elements 204 a and 204 b of the first temperature controller 204 , and current is applied to the heater elements 203 a and 203 b of the second temperature controller 203 . For example, in the first period in which the exposure operation is performed, the controller 100 may gradually reduce the heater element 204a to be applied to the first temperature controller 204 from a predetermined value according to the elapsed time from the start of the first period. and 204b current. Therefore, the change of astigmatism 604 due to heating due to the current applied to the heater elements 204a and 204b of the first temperature controller 204 can be made to follow the change of astigmatism 603 due to the absorption of the light beam.

For example, in the second period in which the exposure operation is not performed, the controller 100 may stop the heating by the first temperature controller 204 and gradually reduce the applied temperature from a predetermined value according to the elapsed time from the start of the second period. Current to heater elements 203 a and 203 b of second temperature controller 203 . Therefore, the change of astigmatism 604 due to heating due to the current applied to the heater elements 204a and 204b of the first temperature controller 204 can be made to follow the change of astigmatism 603 due to the absorption of the light beam. Therefore, it becomes possible to reduce the astigmatism generated by the temperature distribution on the lens 201 to a non-problematic level for the exposure operation of the substrate in the first period in which the exposure operation is performed and in the second period in which the exposure operation is not performed.

Generally speaking, it is not necessary to make the temperature distribution on the lens 201 uniform by using the first temperature controller 204 and the second temperature controller 203 . This is because the correction target is not the astigmatism of the lens 201 but the astigmatism of the projection optical system 107 (the overall aberration of the projection optical system 107 generated when all optical elements forming the projection optical system 107 absorb light beams). Therefore, in order to correct and reduce the overall astigmatism of the projection optical system 107 , the required temperature distribution on the lens 201 can be generated by the first temperature controller 204 and the second temperature controller 203 .

The profile (time variation) of the current 601 applied to the first temperature controller 204 (204a, 204b) and the profile (time variation) of the current 602 applied to the second temperature controller 203 (203a, 203b) can be determined based on experiments. Profile, this experiment is used to obtain the relationship between each current value and the corresponding measured astigmatism value. Alternatively, each of the profile of the current 601 and the profile of the current 602 may be determined based on the temperature distribution on the heated lens 201 . Alternatively, each of the profile of the current 601 and the profile of the current 602 may be based on parameters obtained beforehand.

As a method for obtaining parameters in advance, for example, there is a method of actually measuring a temporal change in aberration of the projection optical system 107 when the lens 201 is heated by the temperature controllers 204 and 203 after the projection optical system 107 has been assembled , and determine the parameters based on the measurement results. According to this method, since parameters can be determined by including changes in aberrations generated by heat transfer and heat radiation to each optical element on the periphery of the lens 201 and the lens barrel of the projection optical system 107, the profile of each current determined with high precision. Therefore, this method is superior to the method of determining parameters only by measuring the lens 201 whose temperature distribution is controlled by the first temperature controller 204 and the second temperature controller 203 . Furthermore, the parameters may be determined by measuring the aberration of the projection optical system 107 after incorporating the projection optical system 107 into the exposure apparatus EXP, or may be determined by updating already determined parameters.

The determination time point and the application time point of the current value may be set at predetermined time intervals or random time intervals. This time interval is preferably set to, for example, 0.1 second to 10 seconds, and further preferably set to 1 second to 5 seconds. Also, the current value profile can be determined in advance at the beginning of the batch, and the current value during the processing of the batch can be controlled according to this profile. Depending on the control performed by the temperature adjustment unit 108 on the temperature distribution on the lens 201 , aberration components other than astigmatism may be newly generated. In this case, newly generated aberrations can be reduced by a driving operation of moving and/or tilting the optical elements forming the projection optical system 107, changing the wavelength of light generated by the light source 102, and the like.

Hereinafter, the second embodiment will be described with reference to FIGS. 7A and 7B and FIGS. 8A and 8B . Matters not mentioned in the second embodiment may follow those in the first embodiment. 7A and 7B are graphs showing comparison targets as the second embodiment. Current values 701 to be applied to the heater elements 204a and 204b of the first temperature controller 204, and the heater element 203a to be applied to the second temperature controller 203 according to the first embodiment are illustrated in FIG. 7A. and current value 702 of 203b. The change in astigmatism 703 due to the absorption of the light beam is illustrated in FIG. 7B . Furthermore, the borrowing caused by applying current values 701 and 702 to the heater elements 204a and 204b of the first temperature controller 204, and the heater elements 203a and 203b of the second temperature controller 203 are illustrated in FIG. 7B, respectively. Changes in astigmatism 704 produced by heating. Furthermore, the variation of the corrected residual error 705 is illustrated in FIG. 7B. Note that although astigmatism 704 has been obtained by multiplying the actual astigmatism produced by heating by current values 701 and 702 by -1, this is for visual convenience only. As illustrated in Figure 7B, there is a very large correction residual error 705. The magnitude of the corrected residual error 705 may depend on a model of the astigmatism produced by the absorption of the beam (curve 501 ) and the astigmatism produced by the first temperature controller 204 (curve 502 ) (e.g., a first-order hysteresis system or a second-order lag system), the size of the time constant of the model, etc. In particular, correction residual error 705 tends to occur when there is a strong second order hysteresis tendency in the astigmatism (curve 502). This may depend, for example, on the shape of the lens 201 and the arrangement of the first temperature controller 204 and the second temperature controller 203 .

In the second embodiment, the first temperature controller 204 and the second temperature controller 203 are operable to reduce the variation of the optical characteristics of the projection optical system 107 during the first period. Furthermore, in the second embodiment, the first temperature controller 204 and the second temperature controller 203 are also operable to reduce the variation of the optical characteristics of the projection optical system 107 in the second period. 8A and 8B illustrate operations of the first temperature controller 204 and the second temperature controller 203 according to the second embodiment. A current value 801 to be applied to the heater elements 204a and 204b of the first temperature controller 204, and a current to be applied to the heater elements 203a and 203b of the second temperature controller 203 are illustrated in FIG. 8A The current value 802 is obtained by multiplying by -1. Note that although the current 802 has been obtained by multiplying the current to be applied to the heater elements 203a and 203b of the second temperature controller 203 by -1, this is for visual convenience only. The change in astigmatism 803 produced by the absorption of the beam is illustrated in Fig. 8B. In addition, in FIG. 8B exemplified in FIG. The change in astigmatism 804 is obtained by multiplying the resulting astigmatism by -1. Furthermore, the variation of the corrected residual error 805 is illustrated in FIG. 8B. It can be seen that astigmatism can be reduced with high precision by operating the first temperature controller 204 and the second temperature controller 203 in both the first period and the second period.

Hereinafter, a third embodiment will be described with reference to FIGS. 9A and 9B and FIG. 10 . Matters not mentioned in the third embodiment may follow those in the first and second embodiments. In the second embodiment, at least one of the first temperature controller 204 and the second temperature controller 203 is operable to heat the lens 201 during almost the entire period including the first period and the second period. Heating of the lens 201 may generate a plurality of aberration components other than astigmatism. Although it is possible to predict the generation of higher-order components among a plurality of components, it is difficult to correct such components. In particular, unlike aberration components such as astigmatism in which the aberrations producible by the first temperature controller 204 and the second temperature controller 203 have opposite signs, it is difficult to reduce the The aberrations generated by the controller 204 and the second temperature controller 203 have aberration components of the same sign. Therefore, although a plurality of aberration components as described above are generated whenever the lens 201 is heated, it is difficult to correct these aberration components.

Therefore, in the third embodiment, the controller 100 will operate the first temperature controller 204 and the second temperature controller 203 so that in the first period and the second period, the aberration (astigmatism) is within the allowable aberration While changing within the predetermined range, it will not exceed the predetermined value. Therefore, aberrations that are difficult to correct due to heating of the lens 201 can be suppressed.

9A and 9B illustrate operations of the first temperature controller 204 and the second temperature controller 203 according to the third embodiment. A current 901 to be applied to the heater elements 204 a and 204 b of the first temperature controller 204 and a current 902 to be applied to the heater elements 203 a and 203 b of the second temperature controller 203 are illustrated in FIG. 9A . The change in astigmatism 903 produced by the absorption of the light beam is illustrated in FIG. 9B . In addition, in FIG. 9B exemplified in FIG. 9B , the generation of heating due to the current value to be applied to the heater elements 204 a and 204 b of the first temperature controller 204 and the heater elements 203 a and 203 b of the second temperature controller 203 The change in astigmatism 904 is obtained by multiplying the astigmatism by -1. Furthermore, the variation of the corrected residual error 905 is illustrated in FIG. 9B . In the third embodiment, in the case where the correction residual error 905 would exceed the range set by the upper limit 906a and the lower limit 906b, the controller 100 operates the temperature adjustment unit 108 to prevent the correction residual error 905 from falling outside the predetermined range 907 . Therefore, astigmatism can be contained within the predetermined range 907 while suppressing the generation of other aberration components due to the heating of the lens 201 .

In this case, Zernike polynomials (Zernike polynomial) can be proposed as one of the aberration components that are difficult to correct other than the astigmatism generated by the heating of the lens 201. A generation amount 1001 of the Zernike term Z17 by heating of the lens 201 in the second embodiment and a generation amount 1002 of the Zernike term Z17 by heating of the lens 201 in the third embodiment are illustrated in FIG. 10 . . In the third embodiment, the generation amount of the Zernike term Z17 generated by the heating of the lens 201 is reduced to 1/3 of the generation amount of the Zernike term Z17 in the second embodiment. In this way, in the third embodiment, heating of the lens 201 by the temperature adjustment unit 108 is reduced by allowing the correction residual error of astigmatism to fall within a predetermined range. Therefore, generation of aberration components that are difficult to correct can be suppressed. Note that this method is a method of determining a trade-off between correction accuracy of astigmatism and generation of aberration components other than astigmatism. Therefore, the predetermined range of allowable astigmatism can be determined by considering the balance between the influence of correction accuracy on imaging performance and the influence of aberration components other than astigmatism on imaging performance. Furthermore, although the third embodiment has described the Zernike term Z17 as an aberration component that is difficult to correct, the present invention is not limited thereto. For example, other higher-order 0Θ components may be considered, such as Zernike term Z16, etc., and lower-order 0Θ components that are easy to correct may also be considered.

In the first to third embodiments, the temperature adjusting unit 108 is formed of heater elements each having a length corresponding to 1/4 of the circumference of the lens 201 and generating negative astigmatism and positive astigmatism. However, this is only an example, and the shape and number of heater elements may be selected according to the aberration components to be corrected. Figure 11 shows an example where the temperature adjustment unit 108 is formed by eight heater elements 1101 to 1108, each having a length corresponding to 1/8 of the circumference of the lens. A first temperature controller may be formed by heater elements 1102 , 1104 , 1106 and 1108 and a second temperature controller may be formed by heater elements 1101 , 1103 , 1105 and 1107 . Therefore, since the 4θ aberration components can be generated in the positive and negative directions, the 4θ aberration components can be corrected by the methods according to the first to third embodiments. Furthermore, the 3θ aberration component can be corrected in the same way by arranging six heater elements each corresponding to 1/6 of the length in the circumferential direction, and also by arranging ten heaters elements to correct the 5θ aberration component, and each heater element corresponds to 1/10 of the length in the circumferential direction. That is, the number and layout of heater elements can be selected according to the aberration components to be corrected. Therefore, it is possible to reduce, for example, at least one of the N θ (N is a natural number) components of the Zernike polynomial.

Next, an article manufacturing method for manufacturing an article (semiconductor IC element, liquid crystal display element, MEMS, etc.) by using the exposure apparatus represented by the first to fourth embodiments described above will be described. The article manufacturing method may include a step of exposing a substrate by the above-mentioned exposure apparatus, a step of developing the substrate exposed in the exposing, and a step of processing the substrate developed in the developing step, and may be obtained from the substrate exposed in the processing step. The processed substrate produces an article. Processing may include, for example, etching, resist removal, dicing, bonding, encapsulation, and the like. According to this article manufacturing method, an article of higher quality than the prior art can be manufactured.

Other Embodiments One or more embodiments of the present invention can also be implemented by a computer of a system or device, which reads and executes the data recorded on a storage medium (which can also be more completely referred to as "non- Computer-executable instructions (eg, one or more programs) on a transitory computer-readable storage medium) to perform the functions of one or more of the above-described embodiments, and/or include instructions for performing one or more of the above-mentioned One or more circuits (for example, application-specific integrated circuits (ASICs)) of the functions of the embodiments, and embodiments of the present invention may be implemented by a computer of a system or device to, for example, read and execute a computer-readable Executing instructions to perform the functions of one or more of the above-mentioned embodiments, and/or controlling one or more circuits to perform the functions of one or more of the above-mentioned embodiments to implement the method. A computer may include one or more processors (e.g., central processing unit (CPU), microprocessing unit (MPU)), and may include individual computers or networks of individual processors to read and execute computer-executable instruction. For example, computer-executable instructions may be provided to a computer from a network or storage medium. Storage media may include, for example, hard disks, random access memory (RAM), read only memory (ROM), distributed computing system storage, optical disks (e.g., compact disks (CD), multi-disc (DVD) or Blu-ray Disc (BD) ^™ ), flash memory device, memory card, etc.

While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of claims below should be given the broadest interpretation to cover all such modifications and equivalent structures and functions.

100: controller 102: light source 104: Illumination optical system 106: Original 107:Projection optical system 108: Temperature adjustment unit 109: Optical components 110: Substrate 201: lens 203: Second temperature controller 203a: heater element 203b: heater element 204: The first temperature controller 204a: heater element 204b: heater element 205: medium 206: heated surface 401: shaded part 501a: curve 501b: curve 502a: curve 502b: curve 503a: curve 503b: curve 601: Current 602: current 603: Astigmatism 604: Astigmatism 605: Correct residual error 701: current value 702: current value 703: Astigmatism 704: Astigmatism 705: Correct residual error 801: Current 802: Current 803: Astigmatism 804: Astigmatism 805: Correct residual error 901: current 902: current 903: Astigmatism 904: Astigmatism 905: Correct residual error 906a: upper limit 906b: lower limit 907: Scheduled range 1001: production volume 1002: production volume 1101: heater element 1102: heater element 1103: heater element 1104: heater element 1105: heater element 1106: heater element 1107: heater element 1108: heater element EXP: exposure equipment

[ Fig. 1 ] is a view schematically showing the arrangement of an exposure apparatus according to a first embodiment;

[FIG. 2A and FIG. 2B] are views showing an example of the arrangement of the optical elements and the temperature adjustment unit of the exposure apparatus according to the first embodiment;

[FIG. 3A and FIG. 3B] are views illustrating temperature distribution on the lens heated by the temperature adjustment unit;

[ Fig. 4 ] is a view illustrating distribution of light beams passing through lenses of a projection optical system of a scanning exposure apparatus;

[ FIG. 5 ] is a graph illustrating the temporal characteristics of changes in astigmatism;

[ FIGS. 6A and 6B ] are graphs illustrating correction of aberrations in the projection optical system of the exposure apparatus according to the first embodiment;

[FIG. 7A and FIG. 7B] are views showing an example of correction of aberration in the projection optical system of the exposure apparatus according to the first embodiment;

[ FIGS. 8A and 8B ] are graphs showing correction of aberrations in the projection optical system of the exposure apparatus according to the second embodiment;

[ FIGS. 9A and 9B ] are graphs showing correction of aberrations in the projection optical system of the exposure apparatus according to the third embodiment;

[ Fig. 10 ] is a graph illustrating aberration components other than astigmatism in the exposure apparatus according to the third embodiment; and

[ Fig. 11 ] is a view illustrating the arrangement and layout of heater elements according to the fourth embodiment.

601: Current

602: current

Claims (32)

An exposure apparatus that performs an exposure operation to expose a substrate via a projection optical system, the exposure apparatus includes: a temperature adjustment unit configured to control the temperature on the optical element of the projection optical system by applying thermal energy to the optical element. a temperature distribution, wherein, during a first period in which the exposure operation is performed, the temperature adjustment unit operates to reduce a change in aberration of the projection optical system caused by performing the exposure operation, and after the first period and without During the second period during which the exposure operation is performed, the temperature adjustment unit operates to reduce a variation in aberration caused by not performing the exposure operation such that the thermal energy applied to the optical element is gradually decreases over time. The exposure apparatus as described in claim 1, wherein the optical element on which the temperature distribution in the first period is controlled by the temperature adjusting unit and the temperature distribution thereon in the second period are by The optical elements controlled by the temperature adjustment unit are identical. The exposure apparatus according to claim 2, wherein the temperature distribution applied to the optical element by the temperature adjustment unit during the first period is the same as that applied to the optical element by the temperature adjustment unit during the second period. This temperature distribution of the element has an opposite phase. The exposure equipment according to claim 1, wherein the temperature adjustment unit includes a first temperature controller and a second temperature controller, and wherein, in the first period, the first temperature controller according to the corresponding to control the temperature distribution on the optical element according to the command value of the elapsed time from the start of the first period, and in the second period, the second temperature controller according to the The command value of the elapsed time from start controls the temperature distribution on the optical element. The exposure apparatus as claimed in claim 1, wherein, during the first period, the temperature adjustment unit generates heat so as to reduce the variation of the aberration caused by performing the exposure operation, and during the second period , the temperature adjustment unit generates heat in order to reduce the variation of the aberration caused by not performing the exposure operation. The exposure equipment according to claim 1, wherein the temperature adjustment unit includes a first temperature controller and a second temperature controller, and wherein, during the first period, the first temperature controller and the second temperature the controller operates so as to reduce the variation of the aberration of the projection optical system, and during the second period, the first temperature controller and the second temperature controller operate so as to reduce the variation of the aberration of the projection optical system The change. The exposure apparatus as described in claim 6, wherein, in the first period and the second period, the first temperature controller and the second temperature controller operate so that the aberration is allowed to change within a predetermined range At the same time, the aberration will not fall outside the predetermined range. The exposure equipment according to claim 1, wherein the temperature adjustment unit includes a first temperature controller and a second temperature controller, and And wherein, the first temperature controller is arranged outside the effective diameter of the optical element on which the temperature distribution is controlled by the first temperature controller, and the second temperature controller is arranged thereon The temperature distribution is controlled by the second temperature controller outside the effective diameter of the optical element. The exposure apparatus according to claim 1, wherein the temperature adjusting unit reduces at least one of Nθ components of a Zernike polynomial (Zernike polynomial) of the aberration, where N is a natural number. The exposure apparatus according to claim 1, wherein the temperature adjusting unit reduces astigmatism as the aberration. The exposure apparatus according to claim 1, wherein the first period is a period from a start of an initial exposure operation on the substrate to an end of a final exposure operation on the substrate. The exposure apparatus as claimed in claim 11, wherein the second period is a period from the end of the last exposure operation to the substrate. The exposure apparatus as claimed in claim 1, wherein the first time period is from the beginning of the initial exposure operation on the first substrate of the first batch to the end of the last exposure operation on the last substrate of the first batch time period. The exposure apparatus as claimed in claim 13, wherein the second period is from the last exposure of the last substrate of the first batch The period from the end of operation to the start of the initial exposure operation of the first substrate of the second batch following the first batch. An exposure method that performs an exposure operation to expose a substrate through a projection optical system, the exposure method includes: performing a first process to control the a temperature distribution on the optical elements of the projection optical system such that variations in aberrations of the projection optical system due to performing the exposure operation will be reduced by applying thermal energy to the optical elements, and performing a second process to After the first period and during the second period when the exposure operation is not performed, by using the temperature adjustment unit to control the temperature distribution on the optical element, the image of the projection optical system caused by not performing the exposure operation Poor variations will be reduced such that the thermal energy applied to the optical element is gradually reduced according to the time elapsed from the start of the second period. The exposure method according to claim 15, wherein the optical element on which the temperature distribution is controlled when the first process is performed and the optical element on which the temperature distribution is controlled when the second process is performed The optics are identical. The exposure method as set forth in claim 16, wherein the temperature distribution applied to the optical element when the first process is performed has an opposite direction to the temperature distribution applied to the optical element when the second process is performed. phase. The exposure method according to claim 15, wherein the The temperature adjusting unit includes a first temperature controller and a second temperature controller, and wherein, when performing the first process, the first temperature controller is controlled according to a command value corresponding to an elapsed time from the start of the first period a temperature controller, and when the second process is performed, the second temperature controller is controlled according to a command value corresponding to an elapsed time from the start of the second period. The exposure method according to claim 15, wherein the temperature adjustment unit includes a first temperature controller and a second temperature controller, and wherein, when performing the first process, the first temperature controller generates heat so that reducing the variation of the aberration caused by performing the exposure operation, and when performing the second process, the second temperature controller generates heat so as to reduce the variation of the aberration caused by not performing the exposure operation Variety. The exposure method according to claim 15, wherein the temperature adjusting unit includes a first temperature controller and a second temperature controller, and wherein, when performing the first process, the first temperature controller and the second A temperature controller is controlled so as to reduce the variation of the aberration of the projection optical system, and while performing the second process, the first temperature controller and the second temperature controller are controlled so as to reduce the variation of the projection optical system This change in the aberration of the system. The exposure method according to claim 20, wherein, when performing the first process and performing the second process, the first temperature controller and the second temperature controller are controlled so that the aberration is allowed to be While changing within a predetermined range, the aberration will not fall outside the predetermined range. The exposure method as claimed in claim 15, wherein the temperature adjustment unit includes a first temperature controller and a second temperature controller, and wherein the temperature distribution on which the first temperature controller is arranged is controlled by the The outer side of the effective diameter of the optical element controlled by the first temperature controller, and the temperature distribution on which the second temperature controller is arranged is controlled by the effective diameter of the optical element by the second temperature controller outside. The exposure method according to claim 15, wherein at least one of the Nθ components of the Zernike polynomial as the aberration is reduced when performing the first process and performing the second process, where N is a natural number. The exposure method according to claim 15, wherein astigmatism which is the aberration is reduced when the first process is performed and the second process is performed. The exposure method as claimed in claim 15, wherein the first period is a period from the start of an initial exposure operation on the substrate to the end of a final exposure operation on the substrate. The exposure method as claimed in claim 25, wherein the second period starts from the end of the last exposure operation to the substrate time period. The exposure method as claimed in claim 15, wherein the first time period is from the beginning of the initial exposure operation on the first substrate of the first batch to the end of the last exposure operation on the last substrate of the first batch time period. The exposure method as claimed in claim 27, wherein the second period is from the end of the last exposure operation of the last substrate of the first batch to the second of the second batch following the first batch. The start period of the initial exposure operation of a substrate. A method of manufacturing an article, the method comprising: exposing a substrate by means of an exposure apparatus as defined in any one of claims 1 to 28; developing the substrate exposed in the exposing; and processing the substrate exposed in the developing The substrate being developed, wherein the article is obtained from the substrate processed in the process. An exposure apparatus that performs an exposure operation to expose a substrate via a projection optical system, the exposure apparatus includes: a temperature adjuster including a first temperature controller and a second temperature controller arranged at positions different from each other , the temperature regulator is configured to control the temperature distribution on the optical element of the projection optical system, wherein the temperature regulator controls the first temperature controller to control the heating of the first region of the optical element, and controls the second two temperature controllers to control the heating of a second region of the optical element, the second region being different from the first region such that: During a first period of performing the exposure operation, the optical element has a first non-uniform temperature distribution to reduce variations in aberrations of the projection optical system caused by performing the exposure operation; and after the first period and During the second period when the exposure operation is not performed, the optical element has a second non-uniform temperature distribution to reduce the variation of the aberration of the projection optical system caused by not performing the exposure operation. An exposure method that performs an exposure operation to expose a substrate via a projection optical system including a temperature adjuster including a first temperature controller and a second temperature controller arranged at positions different from each other. a temperature controller configured to control a temperature distribution on an optical element of the projection optical system, and the exposure method includes: controlling the temperature adjuster so that the optical element having a first non-uniform temperature distribution to reduce variation in aberration of the projection optical system due to performing the exposure operation; and controlling the temperature adjuster so that after the first period of time and the second During the period, the optical element has a second non-uniform temperature distribution to reduce the variation of the aberration of the projection optical system caused by not performing the exposure operation, wherein the first temperature controller is controlled to control the heating of a first region of an optical element and controlling the second temperature controller to control heating of a second region of the optical element having the first non-uniform temperature distribution and the second non-uniform temperature distribution, the first The second area is different from the first area. A method of manufacturing an article, the method comprising: exposing a substrate via a projection optical system including a temperature adjuster including a first temperature controller and a second temperature controller arranged at positions different from each other. a temperature controller, the temperature regulator configured to control a temperature distribution on the optical elements of the projection optical system; obtaining the article from the substrate being exposed; controlling the temperature regulator, in performing the first exposure of the substrate during a period so that the optical element has a first non-uniform temperature distribution to reduce variations in the aberration of the projection optical system caused by performing the exposure operation; and controlling the temperature adjuster after the first period and without During the second period during which the exposure operation is performed, the optical element has a second non-uniform temperature distribution to reduce the variation of the aberration of the projection optical system caused by not performing the exposure operation, wherein, by controlling the first a temperature controller to control the heating of the first region of the optical element and the second temperature controller to control the heating of the second region of the optical element having the first non-uniform temperature distribution and the second Non-uniform temperature distribution, the second zone being different from the first zone.

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