JP6951498B2 - Exposure equipment, exposure method and article manufacturing method - Google Patents

Description

The present invention relates to an exposure apparatus, an exposure method, and an article manufacturing method.

In the manufacture of articles such as semiconductor devices, an exposure apparatus is used in which an original plate (reticle or mask) is illuminated by an illumination optical system, and a pattern of the original plate is projected onto a substrate via a projection optical system to expose the substrate. Since the imaging characteristics of the projection optical system vary depending on the irradiation of the exposure light, the imaging characteristics can be corrected by controlling the posture and position of the optical element in the exposure apparatus. Aberration components that can be corrected by controlling the posture and position of the optical element are limited, and non-rotational imaging characteristics such as astigmatism cannot be corrected. Patent Document 1 describes that the temperature distribution of the optical member is changed by an adjusting mechanism for adjusting the temperature of the optical member arranged near the pupil surface of the projection optical system to adjust the optical characteristics of the projection optical system. Has been done.

Japanese Patent No. 5266641

Patent Document 1 merely describes that the imaging characteristics of the projection optical system are adjusted by the adjusting mechanism during the period when the exposure operation is performed, and is connected by the adjusting mechanism during the period when the exposure operation is not performed. There is no mention of adjusting the image characteristics. If the adjustment by the adjusting mechanism is stopped during the period when the exposure operation is not performed, a large correction residual may occur when the exposure operation is restarted. This is because the temporal change in the imaging characteristics after the end of the exposure operation and the temporal change in the imaging characteristics after the adjustment by the adjustment mechanism are different.

The present invention has been made with the above-mentioned problem recognition as an opportunity, and provides an advantageous technique for correcting the aberration of the projection optical system with high accuracy even when the exposure operation is restarted after the exposure operation is stopped. The purpose is.

One aspect of the present invention relates to an exposure device that performs an exposure operation for exposing a substrate via a projection optical system, and the exposure device includes a temperature adjusting unit that controls a temperature distribution of optical elements of the projection optical system. In the first period in which the exposure operation is performed, the temperature adjusting unit operates so as to reduce the change in aberration of the projection optical system due to the exposure operation, following the first period. In the second period in which the exposure operation is not performed, the temperature adjusting unit operates so as to reduce the change in the aberration due to the non-exposure operation being performed.

According to the present invention, there is provided an advantageous technique for correcting the aberration of the projection optical system with high accuracy even when the exposure operation is restarted after the exposure operation is stopped.

The figure which shows typically the structure of the exposure apparatus of 1st Embodiment. The figure which shows the structural example of the optical element and the temperature adjustment part in the exposure apparatus of 1st Embodiment. The figure which illustrates the temperature distribution of the lens heated by a temperature control part. The figure which illustrates the distribution of the light flux passing through the lens of the projection optical system of a scanning exposure apparatus. The figure which illustrates the temporal characteristic of the change of astigmatism. The figure which illustrates the correction of the aberration of the projection optical system in the exposure apparatus of 1st Embodiment. The figure which shows an example of the correction of the aberration of the projection optical system in the exposure apparatus of 1st Embodiment. The figure which illustrates the correction of the aberration of the projection optical system in the exposure apparatus of 2nd Embodiment. The figure which illustrates the correction of the aberration of the projection optical system in the exposure apparatus of 3rd Embodiment. The figure which illustrates the aberration component other than astigmatism in the exposure apparatus of 3rd Embodiment. The figure which illustrates the structure and arrangement of the heating element in 4th Embodiment.

Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. The following embodiments do not limit the invention according to the claims. Although a plurality of features are described in the embodiment, not all of the plurality of features are essential to the invention, and the plurality of features may be arbitrarily combined. Further, in the attached drawings, the same or similar configurations are given the same reference numbers, and duplicate explanations are omitted.

FIG. 1 schematically shows the configuration of the exposure apparatus EXP of the first embodiment. The exposure apparatus EXP roughly performs an exposure operation for exposing the substrate 110 via the projection optical system 107. In the specification and the drawings, as shown in FIG. 1, the direction is shown in the XYZ coordinate system in which the plane parallel to the plane on which the substrate 110 is arranged is the XY plane. The exposure apparatus EXP includes a light source 102, an illumination optical system 104, a projection optical system 107, and a control unit 100. In the exposure operation, the illumination optical system 104 illuminates the original plate 106 with the light (exposure light) from the light source 102, and the projection optical system 107 projects the pattern of the original plate 106 onto the substrate 110, thereby exposing the substrate 110. The exposure apparatus EXP may be configured as an exposure apparatus that exposes the substrate 110 with the original plate 106 and the substrate 110 stationary, or may be configured as an exposure apparatus that exposes the substrate 110 while scanning the original plate 106 and the substrate 110. You may. Generally, the substrate 110 has a plurality of shot regions, and an exposure operation can be performed on each shot region.

The light source 102 may include, for example, an excimer laser, but may include other light emitting devices. The excimer laser may, for example, generate light having a wavelength of 248 nm or 193 nm, but may generate light of other wavelengths. The projection optical system 107 may include an optical element 109 and a temperature adjusting unit 108 that controls the temperature distribution of the optical element 109. The temperature adjusting unit 108 can change the refractive index distribution and / or the surface shape of the optical element 109 by applying thermal energy to the optical element 109, thereby reducing the change in the optical characteristics of the projection optical system 107. The thermal energy given to the optical element 109 by the temperature adjusting unit 108 may include positive and negative energies. Giving positive energy to the optical element 109 means heating the optical element 109, and giving negative energy to the optical element 109 means cooling the optical element 109.

The temperature adjusting unit 108 may be arranged so as to be in close contact with the optical element 109, and in this case, the transfer of thermal energy between the temperature adjusting unit 108 and the optical element 109 is efficient. Alternatively, the temperature adjusting unit 108 may be arranged at a distance from the optical element 109, and the configuration is such that the temperature adjusting unit 108 does not apply a mechanical force to the optical element 109 or the temperature adjusting unit 108. It is advantageous in that the optical element 109 is not damaged such as scratches by the 108.

The temperature adjusting unit 108 is preferably arranged outside the effective diameter (optical path) of the optical element 109 so that the temperature adjusting unit 108 does not interfere with the irradiation of the substrate 110 with light. For example, the temperature adjusting unit 108 may be arranged on the edge portion of the lens as the optical element 109, or on the front surface or the back surface of the lens. Alternatively, the temperature adjusting unit 108 may be arranged inside the effective diameter as long as it does not affect the optical performance of the projection optical system 107. Examples of such an arrangement include an example in which a thin heating wire is arranged within the effective diameter and an example in which a heat transfer element having a high light transmittance is arranged within the effective diameter.

When the temperature adjusting unit 108 is arranged on the outer peripheral side of the optical element 109, the optical element 109 is preferably arranged on or near the pupil surface of the projection optical system 107, but the temperature adjusting unit 108 is arranged on the projection optical system 107. It may be arranged away from the pupil surface of the. A plurality of temperature adjusting units 108 include a first temperature control unit that controls the temperature distribution of the optical element 109 of the projection optical system 107, and a second temperature control unit that controls the temperature distribution of the optical element 109 of the projection optical system 107. It may include a temperature control unit of. The first temperature control unit may operate so as to reduce the change in the optical characteristics of the projection optical system 107 due to the exposure operation during the first period in which the exposure operation is performed. The second temperature control unit may operate so as to reduce the change in the optical characteristics of the projection optical system 107 due to the non-exposure operation in the second period following the first period in which the exposure operation is not performed. Alternatively, at least in the first temperature control unit and the second temperature control unit so that the change in the optical characteristics of the projection optical system 107 due to the exposure operation is reduced in the first period in which the exposure operation is performed. One can work. Further, in the second period following the first period, in which the exposure operation is not performed, the first temperature control unit and the second temperature control unit are reduced so that the change in the optical characteristics of the projection optical system 107 due to the non-exposure operation is not performed. At least one of and can work. The plurality of temperature control units (first temperature control unit, second temperature control unit) individually control the amount and duration of the thermal energy given to the optical element 109, whereby the temperature distribution of the optical element 109 can be controlled. .. The plurality of temperature control units (first temperature control unit, second temperature control unit) can be controlled by the control unit 100. The optical element 109 whose temperature distribution is controlled by the first temperature control unit and the optical element 109 whose temperature distribution is controlled by the second temperature control unit may be the same as each other or may be different from each other.

The temperature adjusting unit 108 changes the thermal energy given to the optical element 109 in synchronization with the optical characteristics of the projection optical system 107, which changes from moment to moment, during the period in which the exposure operation is performed and the period in which the exposure operation is not performed. I can let you. Here, the information necessary for controlling the temperature adjusting unit 108 is based on the measurement of the optical characteristics of the projection optical system 107 on the image plane (the surface on which the substrate 110 is arranged) of the projection optical system 107. Can be generated. Alternatively, the information necessary for controlling the temperature adjusting unit 108 may be determined in advance through measurement or the like. The control of the thermal energy given to the optical element 109 by the temperature adjusting unit 108 can be realized, for example, by controlling the current value applied to the heating wire when the temperature adjusting unit 108 includes the heating wire. Alternatively, the control of the thermal energy given to the optical element 109 by the temperature adjusting unit 108 may be realized by, for example, controlling the physical distance or the thermal distance between the optical element 109 and the temperature adjusting unit 108.

The control unit 100 can control the light source 102, the illumination optical system 104, the projection optical system 107, and the temperature control unit 108. More specifically, the control unit 100 may be configured to control the temperature adjusting unit 108 in the first period and the second period in addition to controlling the exposure operation. The control unit 100 is, for example, a PLD (abbreviation for Programmable Logic Device) such as FPGA (abbreviation for Field Programmable Gate Array), or an ASIC (application specific specialized integrated circuit) or an abbreviation for an ASIC (application specific integrated circuit) integrated circuit. Alternatively, it may be composed of a dedicated computer or a combination of all or a part thereof.

FIG. 2 shows a configuration example of the optical element 109 and the temperature adjusting unit 108 in the exposure apparatus EXP of the first embodiment. The optical element 109 may include a lens 201. The temperature adjusting unit 108 may include a first temperature control unit 204 composed of heating elements 204a and 204b and a second temperature control unit 203 composed of heating elements 203a and 203b. The heating elements 204a, 204b, 203a, and 203b may each have an arc shape corresponding to an arc of 1/4 of the circumference of the lens 201. The heating elements 204a, 204b, 203a, and 203b are composed of, for example, a flexible cable including a heating wire, and heat is generated by applying an electric current to the heating wire, which can form a temperature distribution on the lens 201.

The heating elements 204a, 204b, 203a, 203b may be arranged, for example, at a distance of 10 to 100 μm with respect to the flat surface portion of the lens 201. The heat generated by the heating elements 204a, 204b, 203a, 203b can be transferred to the lens 201 via the medium 205 between the heating elements 204a, 204b, 203a, 203b and the lens 201. The medium 205 can be, for example, a gas such as air or nitrogen. The heating elements 204a, 204b, 203a, 203b do not need to directly face each other via the lens 201 and the medium 205. The heating elements 204a, 204b, 203a, and 203b may have, for example, a structure in which a heating wire is sandwiched between metals having high thermal conductivity.

In the example of FIG. 2B, the heating elements 204a, 204b, 203a, and 203b are arranged on the flat surface portion of the lens 201 (on the side of the illumination optical system 104). However, the heating elements 204a, 204b, 203a, and 203b may be arranged under the lens 201 (on the side of the substrate 110) or on the edge portion of the lens 201. The lens 201 may have a surface 206 to be heated that is heated by the heating elements 204a, 204b, 203a, 203b. The surface to be heated 206 may be a flat surface or a curved surface. The surface to be heated 206 can be, for example, a roughened surface (ground glass-like surface).

FIG. 3A illustrates the temperature distribution of the lens 201 heated by the second temperature control unit 204. At this time, astigmatism occurs in the positive direction on the surface of the substrate 110. FIG. 3B illustrates the temperature distribution of the lens 201 heated by the first temperature control unit 203. The temperature distribution in FIG. 3 (b) is a temperature distribution having a phase opposite to the temperature distribution in FIG. 3 (a). Due to the temperature distribution of FIG. 3B, astigmatism occurs in the negative direction on the surface of the substrate 110. In this way, positive and negative astigmatism can be generated by heating the lens 201 by the first temperature control unit 204 and the second temperature control unit 203. Such a configuration can simplify the configuration of the temperature adjusting unit 108 as compared with a configuration in which a positive and negative astigmatism is generated by a combination of heating and cooling using an element such as a Pelche element. It is advantageous in that it can be done.

Here, when the exposure apparatus EXP is applied to a scanning exposure apparatus that scans the original plate 106 and the substrate 110 with respect to a slit-shaped luminous flux (exposure light) long in the X direction, the luminous flux passing through the projection optical system 107 during the exposure operation is applied. The intensity distribution can be as shown in the shaded area 401 of FIG. In this case, the temperature distribution of the lens 201 (optical element 109) caused by absorbing the luminous flux differs between the X direction and the Y direction, which may cause a large astigmatism of the projection optical system 107. Therefore, a temperature distribution can be given to the lens 201 by the first temperature control unit 204 so that this astigmatism is reduced. The astigmatism of the projection optical system 107 generated by the first temperature control unit 204 and the astigmatism of the projection optical system 107 generated by the lens 201 absorbing the luminous flux are opposite in sign. Therefore, the astigmatism of the projection optical system 107 generated by the lens 201 absorbing the luminous flux can be reduced by the astigmatism of the projection optical system 107 generated by the first temperature control unit 204. In the following, unless otherwise specified, "astigmatism" means astigmatism of the projection optical system 107.

The change in astigmatism (temporal change characteristic) generated by the first temperature control unit 204 may be different from the change in astigmatism (temporal change characteristic) generated by the lens 201 absorbing the luminous flux. be. In this case, the change in astigmatism by the first temperature control unit 204 is controlled by controlling the current supplied to the heating wire of the first temperature control unit 204, and the astigmatism generated by the lens 201 absorbing the luminous flux. The aberration can be canceled with higher accuracy.

FIG. 5 illustrates the temporal characteristics of changes in astigmatism. In FIG. 5, "at the time of exposure" indicates a first period including an exposure operation, and "at the time of non-exposure" indicates a second period which is a period following the first period and a period during which the exposure operation is not performed. .. In the first example, the first period can be the period from the start of the first exposure operation on one substrate to the end of the last exposure operation on the one substrate. The second period can be a period that begins at the end of the final exposure operation on a single substrate. The second period is, for example, a period from the end of the last exposure operation on one substrate to the start of the first exposure operation on the next substrate. Here, the next substrate may be a substrate in the same lot as the one substrate, or may be the first substrate in the next lot. After a predetermined time has elapsed after the last exposure operation, the second period can be ended and the operation of the temperature adjusting unit 108 can be stopped. The first example is suitable when the change in aberration between one shot region of a substrate and the next shot region of the substrate is negligible. In the second example, the first period is the period during which the exposure operation is executed for each shot area of the substrate, and the second period is the period from the end of the exposure operation for one shot area of the substrate to the substrate. It may include the period until the start of the exposure operation for the next shot area. The second example is suitable when the change in aberration between one shot region of a substrate and the next shot region of the substrate should be considered. In the third embodiment, the first period may be a period from the start of the first exposure operation on the first substrate in the first lot to the end of the last exposure operation on the last substrate in the first lot. .. The second period can be a period from the end of the last exposure operation on the last substrate of the first lot to the start of the first exposure operation on the first substrate in the second lot following the first lot. The first example, the second example, and the third example have a difference in whether or not the exposure operation is roughly grasped, but both can be understood as a common idea.

In FIG. 5, the curve 501a illustrates the change in astigmatism caused by the lens 201 absorbing the luminous flux in the first period. The heating of the lens 201 by the first temperature control unit 204 causes astigmatism that changes in a curve in which the sign of the curve 501a is reversed, which reduces the astigmatism that occurs when the lens 201 absorbs the luminous flux. Alternatively, it is an ideal way to offset. However, when the lens 201 is continuously heated at a constant temperature by the first temperature control unit 204, the astigmatism generated thereby changes with a time constant slower than that of the curve 501a, as illustrated by the curve 502a. There are many. Therefore, the astigmatism shown by the curve 501a cannot be completely corrected (offset), and a correction residual as shown by the curve 503a can occur.

A similar phenomenon can occur in the second period. Since the exposure operation is not performed in the second period, the luminous flux does not pass through the lens 201. Therefore, in the second period, the temperature of the lens 201 does not change due to the absorption of the luminous flux, but the lens 201 is deformed by the heat radiation from the lens 201, which causes the astigmatism to change with time. Curve 501b exemplifies a change in astigmatism generated by releasing (heat radiating) heat generated by absorption of a luminous flux from lens 201. The time constant on the curve 501a and the time constant on the curve 501b can be similar.

When the heating of the lens 201 by the first temperature control unit 204 is stopped at the same time as the transition from the first period to the second period, the heat given to the lens 201 by the first temperature control unit 204 in the first period is applied to the lens in the second period. It is emitted (heat radiated) from 201. Astigmatism can change accordingly as in curve 502b. Between the curve 501b and the curve 502b, there is a difference in temporal change characteristics such as that exists between the curve 501a and the curve 502a. Therefore, even in the second period, a correction residual as shown by the curve 503b can occur.

Curves 501a, 501b, 502a, 502b can generally be represented by a first-order lag system as shown in Equation 1 or a second-order lag system as shown in Equation 2. However, these curves may be represented according to other models.

・・・式１

・ ・ ・ Equation 1

Here, φ (t) is the amount of generated aberration at time t, A is the amount related to the amount of heating given from time t, G is the coefficient related to the amount of generated aberration, and K is the coefficient related to the time constant of the amount of generated aberration. Is.

・・・式２

・ ・ ・ Equation 2

Here, φ (t) is the amount of generated aberration at time t, τ ₁ and τ ₂ are coefficients related to the time constant expressing the second-order delay, A is the amount related to the amount of heating given from time t, and G is. , Coefficient related to the amount of generated aberration, K is a coefficient related to the time constant of the amount of generated aberration.

In order to reduce the correction residual due to such a difference in the temporal change characteristic, the thermal energy given to the lens 201 by the first temperature control unit 204 and the second temperature control unit 203 can be controlled by the control unit 100. This method will be described with reference to FIG. In this method, the thermal energy given to the lens 201 by the first temperature control unit 204 and the second temperature control unit 203 can be controlled according to the command values according to the elapsed time from the start of the first period and the second period, respectively. .. FIG. 6A illustrates the current 601 applied to the heating elements 204a and 204b of the first temperature control unit 204 and the current 602 applied to the heating elements 203a and 203b of the second temperature control unit 203. ing. The control unit 100 may be configured to supply the first temperature control unit 204 with a command value corresponding to the current 601 as a command value according to the elapsed time from the start of the first period. Further, the control unit 100 may be configured to supply the second temperature control unit 203 with a command value corresponding to the current 602 as a command value according to the elapsed time from the start of the second period. FIG. 6B illustrates the change in astigmatism 603 caused by the absorption of the luminous flux. Further, FIG. 6B shows astigmatism 604 generated by heating by the current applied to the heating elements 204a and 204b of the first temperature control unit 204 and the heating elements 203a and 203b of the second temperature control unit 203. Changes are illustrated. Further, FIG. 6 (c) illustrates a change in the correction residual 605.

In this example, in the first period, a current is applied to the heating elements 204a and 204b of the first temperature control unit 204, and no current is applied to the heating elements 203a and 203b of the second temperature control unit 203. On the other hand, in the second period, no current is applied to the heating elements 204a and 204b of the first temperature control unit 204, and a current is applied to the heating elements 203a and 203b of the second temperature control unit 203. In one example, in the first period in which the exposure operation is performed, the control unit 100 applies the current applied to the heating elements 204a and 204b of the first temperature control unit 204 according to the elapsed time from the start of the first period. It can be gradually reduced from a predetermined value. As a result, the change in astigmatism 604 generated by heating by the current applied to the heating elements 204a and 204b of the first temperature control unit 204 is made to follow the change in astigmatism 603 generated by the absorption of the luminous flux. be able to.

In one example, in the second time when the exposure operation is not performed, the control unit 100 stops the heating by the first temperature control unit 204 and applies the current applied to the heating elements 203a and 203b of the second temperature control unit 203 to the second. It can be gradually decreased from a predetermined value according to the elapsed time from the start of the period. As a result, the change in astigmatism 604 caused by heating by the current applied to the heating elements 204a and 204b of the first temperature control unit 204 is changed with respect to the change in astigmatism 603 generated by the absorption of the luminous flux. It can be made to follow. As a result, astigmatism generated by the temperature distribution of the lens 201 is reduced to a level at which there is no problem in exposing the substrate in both the first period in which the exposure operation is performed and the second period in which the exposure operation is not performed. be able to.

Here, in general, it is not necessary to use the first temperature control unit 203 and the second temperature control unit 204 to make the temperature distribution of the lens 201 uniform. This is because the correction target is not the astigmatism of the lens 201, but the astigmatism of the projection optical system 107 (the total of the projection optical system 107 caused by all the optical elements constituting the projection optical system 107 absorbing the light beam). This is because it is an optical aberration). Therefore, the temperature distribution required for the lens 201 may be generated by the first temperature control unit 204 and the second temperature control unit 203 so that the overall astigmatism of the projection optical system 107 is reduced without correction.

The profile (temporal change) of the current 601 applied to the first temperature control unit 204 (204a, 204b) and the current 602 applied to the second temperature control unit 203 (203a, 203b) is different from the current value. It can be determined based on a test to obtain the relationship with the measured value of astigmatism. Alternatively, the profiles of current 601 and current 602 may be determined based on the temperature distribution of the heated lens 201. Alternatively, the profiles of current 601 and current 602 may be made based on pre-acquired parameters.

As a method of acquiring parameters in advance, for example, after assembling the projection optical system 107, the temporal change of the aberration of the projection optical system 107 when the lens 201 is heated by the temperature control units 204 and 203 is actually measured. There is a method of determining the parameters based on the result. According to this method, the parameters can be determined including the aberration change caused by the heat transfer and heat radiation of the optical element around the lens 201 and the projection optical system 107 to the lens barrel, so that the current profile is higher. It can be determined with accuracy. Therefore, this method is superior to the method of determining the parameters by measuring the lens 201 whose temperature distribution is controlled by the first temperature control unit 204 and the second temperature control unit 203 alone. Further, after incorporating the projection optical system 107 into the exposure apparatus EXP, the aberration of the projection optical system 107 may be measured to determine the parameter, or the already determined parameter may be updated.

The timing of determining and applying the current value may be a constant time interval or a non-constant time interval. The time interval is preferably, for example, 0.1 to 10 seconds, and more preferably 1 to 5 seconds. Further, the current value profile may be determined in advance at the beginning of the lot or the like, and the current value during the processing of the lot may be controlled accordingly. Aberration components other than astigmatism may be newly generated by controlling the temperature distribution of the lens 201 by the temperature adjusting unit 108. In this case, the newly generated aberration component can be reduced by driving the optical elements constituting the projection optical system 107 such as shifting and / or tilting, or changing the wavelength of the light generated by the light source 102.

Hereinafter, the second embodiment will be described with reference to FIGS. 7 and 8. Matters not mentioned as the second embodiment may follow the first embodiment. FIG. 7 is a diagram shown as a comparison target with respect to the second embodiment. FIG. 7A shows the current values 701 applied to the heating elements 204a and 204b of the first temperature control unit 204 in the first period and the heating of the second temperature control unit 203 in the second period according to the first embodiment. The current value 702 applied to the elements 203a and 203b is exemplified. FIG. 7B illustrates the change in astigmatism 703 caused by the absorption of the luminous flux. Further, in FIG. 7B, non-astigmatism generated by heating by the current values 701 and 702 applied to the heating elements 204a and 204b of the first temperature control unit 204 and the heating elements 203a and 203b of the second temperature control unit 203. Changes in astigmatism 704 are illustrated. Further, FIG. 7B illustrates a change in the correction residual 705. The astigmatism 704 is the actual astigmatism generated by heating with the current values 701 and 702 multiplied by -1, but this is only for the sake of visibility. As illustrated in FIG. 7B, there is a fairly large correction residual 705. The magnitude of the correction residual 705 is a model (for example, first-order lag system or second-order) of astigmatism (curve 501) generated by absorption of light flux and astigmatism (curve 502) generated by the first temperature control unit 204. It may depend on the difference from the delay system), the magnitude of the time constant of the model, and the like. In particular, when the tendency of the second-order delay of astigmatism (curve 502) is strong, the correction residual 705 is likely to occur. This may depend on, for example, the shape of the lens 201 and the arrangement of the first temperature control unit 204 and the second temperature control unit 203.

In the second embodiment, in the first period, the first temperature control unit 204 and the second temperature control unit 203 can operate so that the change in the optical characteristics of the projection optical system 107 is reduced. Further, in the second embodiment, the first temperature control unit 204 and the second temperature control unit 203 can operate so that the change in the optical characteristics of the projection optical system 107 is reduced even in the second period. FIG. 8 illustrates the operations of the first temperature control unit 204 and the second temperature control unit 203 in the second embodiment. In FIG. 8A, -1 is added to the currents 801 applied to the heating elements 204a and 204b of the first temperature control unit 204 and the currents applied to the heating elements 203a and 203b of the second temperature control unit 203. The multiplied current 802 is exemplified. The current 802 is obtained by multiplying the current applied to the heating elements 203a and 203b of the second temperature control unit 203 by -1, but this is only for the sake of visibility. FIG. 8B illustrates the change in astigmatism 803 caused by the absorption of the luminous flux. Further, FIG. 8B shows astigmatism caused by heating by the current applied to the heating elements 204a and 204b of the first temperature control unit 204 and the heating elements 203a and 203b of the second temperature control unit 203. A change in astigmatism 804 multiplied by 1 is illustrated. Further, FIG. 8B illustrates a change in the correction residual 805. It can be seen that astigmatism is reduced with high accuracy by operating the first temperature control unit 204 and the second temperature control unit 203 in both the first period and the second period.

Hereinafter, the third embodiment will be described with reference to FIGS. 9 and 10. Matters not mentioned as the third embodiment may follow the first and second embodiments. In the second embodiment, at least one of the first temperature control unit 204 and the second temperature control unit 203 operates in almost the entire period including the first and second periods, and the lens 201 can be heated. By heating the lens 201, a plurality of aberration components other than astigmatism may be generated. Of these plurality of aberration components, higher-order aberration components are difficult to correct even if their occurrence can be predicted. In particular, unlike the aberration components in which the aberrations that can be generated by the first temperature control unit 204 and the second temperature control unit 203 have different signs, such as astigmatism, the first temperature control unit 204 and the second temperature control unit 204 are different. It is difficult to reduce the aberration components in which the aberrations that can be generated by 203 have the same sign. Therefore, a plurality of aberration components as described above are generated as long as the lens 201 is heated, and it is difficult to correct them.

Therefore, in the third embodiment, the control unit 100 allows the aberration (astigmatism) to change within a predetermined range in the first period and the second period, and the aberration exceeds the predetermined value. The first temperature control unit 204 and the second temperature control unit 203 are operated so as not to be present. As a result, the occurrence of aberration that is difficult to correct due to heating of the lens 201 can be suppressed.

FIG. 9 illustrates the operations of the first temperature control unit 204 and the second temperature control unit 203 in the third embodiment. FIG. 9A exemplifies the current 901 applied to the heating elements 204a and 204b of the first temperature control unit 204 and the current 902 applied to the heating elements 203a and 203b of the second temperature control unit 203. ing. FIG. 9B illustrates the change in astigmatism 903 caused by the absorption of the luminous flux. Further, FIG. 9B shows astigmatism caused by heating by the current applied to the heating elements 204a and 204b of the first temperature control unit 204 and the heating elements 203a and 203b of the second temperature control unit 203. A change in astigmatism 904 multiplied by 1 is illustrated. Further, FIG. 9C illustrates the change in the correction residual 905. In the third embodiment, the control unit 100 operates the temperature adjusting unit 108 when the correction residual 905 exceeds the range defined by the upper limit 906a and the lower limit 906b so as not to deviate from the predetermined range 907. As a result, it is possible to suppress the generation of other aberration components due to heating of the lens 201 while keeping the astigmatism within the predetermined range 907.

Here, as one of the aberration components other than the astigmatism generated by heating the lens 201 and which is difficult to correct, the aberration of the Z17 term of the Zernike polynomial can be mentioned. FIG. 10 illustrates Z17 term 1001 generated by heating the lens 201 in the second embodiment and Z17 term 1002 generated by heating the lens 201 in the third embodiment. In the third embodiment, the amount of Z17 term generated by heating the lens 201 is reduced to one-third of that of the second embodiment. As described above, in the third embodiment, by allowing the correction residual of astigmatism within a predetermined range, the heating of the lens 201 by the temperature adjusting unit 108 is reduced, and as a result, an aberration component that is difficult to correct is generated. Can be deterred. This method is a method for determining a trade-off between the correction accuracy of astigmatism and the generation of aberration components other than astigmatism. Therefore, the predetermined range in which astigmatism is allowed can be determined in consideration of the balance between the influence of the correction accuracy on the image performance and the influence of the aberration component other than the astigmatism on the image performance. Further, in the third embodiment, the Z17 term is mentioned as an aberration component that is difficult to correct, but the present invention is not limited to this, and a higher-order 0θ component such as the Z16 term may be considered, and the low is easy to correct. The following 0θ component and the like may be considered.

In the first to third embodiments, the temperature adjusting unit 108 is composed of a heating element corresponding to a quarter length of the circumference of the lens 201, and positive and negative astigmatism is generated. However, this is only an example, and the shape and number of heating elements can be selected according to the aberration component to be corrected. FIG. 11 shows an example in which the temperature adjusting unit 108 is composed of eight heating elements 1101 to 1108 having a length of one-eighth of the circumference of the lens. The first temperature control unit can be composed of heating elements 1102, 1104, 1106, and 1108, and the second temperature control unit can be composed of heating elements 1101, 1103, 1105, and 1107. As a result, the aberration component of 4θ can be generated in the positive and negative directions, so that the aberration component of 4θ can be corrected by the methods of the first to third embodiments. Further, six heating elements having a length of 1/6 in the circumferential direction are arranged to correct the aberration component of 3θ by the same method, and 10 of the length of 1/10 in the circumferential direction. By arranging the individual heating elements, the aberration component of 5θ can be corrected. That is, the number and arrangement of the heating elements can be selected according to the aberration component to be corrected. Thereby, for example, at least one of the Nθ components (N is a natural number) in the Zernike polynomial can be reduced.

Next, an article manufacturing method for manufacturing an article (semiconductor IC element, liquid crystal display element, MEMS, etc.) using the exposure apparatus represented by the first to fourth embodiments will be described. The article manufacturing method includes an exposure step of exposing a substrate by an exposure apparatus as described above, a development step of developing a substrate exposed in the exposure step, and a processing step of processing the substrate developed in the development step. The article can be obtained from the substrate including and processed in the processing step. The processing step may include, for example, etching, resist stripping, dicing, bonding, packaging and the like. According to the article manufacturing method, it is possible to manufacture an article of higher quality than before.

The invention is not limited to the above embodiments, and various modifications and modifications can be made without departing from the spirit and scope of the invention. Therefore, a claim is attached to make the scope of the invention public.

EXP: Exposure device, 108: Temperature control unit, 109: Optical element, 201: Lens, 204: First temperature control unit, 203: Second temperature control unit

Claims (35)

An exposure apparatus that performs an exposure operation that exposes a substrate via a projection optical system.
A temperature control unit for controlling the temperature distribution of the optical elements of the projection optical system is provided.
In the first period in which the exposure operation is performed, the temperature adjusting unit operates so as to reduce the change in the aberration of the projection optical system due to the exposure operation.
Following the first period, the second period in which the exposure operation is not performed, the change in the aberration due to exposure light operation is not performed to the temperature adjusting unit operate as reduced,
An exposure apparatus characterized in that. The temperature distribution given to the optical element by the temperature adjusting unit in the first period and the temperature distribution given to the optical element by the temperature adjusting unit in the second period are in opposite phase.
The exposure apparatus according to claim 1. In the first period, the temperature adjusting unit controls the temperature distribution of the optical element according to a command value according to the elapsed time from the start of the first period.
In the second period, the temperature adjusting unit controls the temperature distribution of the optical element according to a command value according to the elapsed time from the start of the second period.
The exposure apparatus according to claim 1 or 2. The temperature adjusting unit is arranged outside the effective diameter of the optical element whose temperature distribution is controlled by the temperature adjusting unit.
The exposure apparatus according to any one of claims 1 to 3, wherein the exposure apparatus is characterized by the above. The temperature regulator reduces at least one of the Nθ components (N is a natural number) in the Zernike polynomial as the aberration.
The exposure apparatus according to any one of claims 1 to 4, wherein the exposure apparatus is characterized by the above. The temperature adjusting unit reduces astigmatism as the aberration.
The exposure apparatus according to any one of claims 1 to 4, wherein the exposure apparatus is characterized by the above. The first period is a period from the start of the first exposure operation on one substrate to the end of the last exposure operation on the one substrate.
The exposure apparatus according to any one of claims 1 to 6, wherein the exposure apparatus is characterized in that. The second period is a period that starts at the end of the last exposure operation on the one substrate.
The exposure apparatus according to claim 7. The first period is a period from the start of the first exposure operation on the first substrate in the first lot to the end of the last exposure operation on the last substrate in the first lot.
The exposure apparatus according to any one of claims 1 to 6, wherein the exposure apparatus is characterized in that. The second period is a period from the end of the last exposure operation on the last substrate of the first lot to the start of the first exposure operation on the first substrate in the second lot following the first lot. ,
The exposure apparatus according to claim 9. The first period is a period from the start of the exposure operation for one shot region on the substrate to the end of the exposure operation for the one shot region.
The exposure apparatus according to any one of claims 1 to 6, wherein the exposure apparatus is characterized in that. The second period is a period from the end of the exposure operation on the one shot region on the substrate to the start of the exposure operation on the shot region following the one shot region.
The exposure apparatus according to claim 11. The exposure apparatus according to any one of claims 1 to 12, wherein the temperature adjusting unit includes a first temperature control unit and a second temperature control unit arranged at different positions from each other. In the first period, the first temperature control unit generates heat so as to reduce the change in the aberration.
In the second period, the second temperature control unit generates heat so that the change in the aberration is reduced.
The exposure apparatus according to claim 13. In the first period, the first temperature control unit and the second temperature control unit operate so as to reduce the change in the aberration.
In the second period, the first temperature control unit and the second temperature control unit operate so that the change in the aberration is reduced.
The exposure apparatus according to claim 13. In the first period and the second period, the first temperature control unit and the second temperature control unit are allowed to change the aberration within a predetermined range so that the aberration does not deviate from the predetermined range. Works,
The exposure apparatus according to claim 15. It is an exposure method that performs an exposure operation that exposes a substrate via a projection optical system.
In the first period in which the exposure operation is performed, the temperature distribution of the optical element of the projection optical system is reduced by the temperature adjusting unit so that the change in the aberration of the projection optical system due to the exposure operation is performed. The first step to control and
Following the first period, the second period in which the exposure operation is not performed, so that the change of the aberration due to exposure light operation is not performed is reduced, the optical elements of the projection optical system by the temperature adjustment unit The second step of controlling the temperature distribution and
An exposure method comprising. The temperature distribution given to the optical element by the temperature adjusting unit in the first step and the temperature distribution given to the optical element by the temperature adjusting unit in the second step are in opposite phase.
The exposure method according to claim 17, wherein the exposure method is characterized by the above. In the first step, the temperature adjusting unit is controlled according to a command value according to the elapsed time from the start of the first period.
In the second step, the temperature adjusting unit is controlled according to a command value according to the elapsed time from the start of the second period.
The exposure method according to claim 17 or 18. The temperature adjusting unit is arranged outside the effective diameter of the optical element whose temperature distribution is controlled by the temperature adjusting unit.
The exposure method according to any one of claims 17 to 19, wherein the exposure method is characterized by the above. The temperature regulator reduces at least one of the Nθ components (N is a natural number) in the Zernike polynomial as the aberration.
The exposure method according to any one of claims 17 to 20, wherein the exposure method is characterized by the above. The temperature adjusting unit reduces astigmatism as the aberration.
The exposure method according to any one of claims 17 to 20, wherein the exposure method is characterized by the above. The first period is a period from the start of the first exposure operation on one substrate to the end of the last exposure operation on the one substrate.
The exposure method according to any one of claims 17 to 22, wherein the exposure method is characterized by that. The second period is a period that starts at the end of the last exposure operation on the one substrate.
The exposure method according to claim 23. The first period is a period from the start of the first exposure operation on the first substrate in the first lot to the end of the last exposure operation on the last substrate in the first lot.
The exposure method according to any one of claims 17 to 22, wherein the exposure method is characterized by that. The second period is a period from the end of the last exposure operation on the last substrate of the first lot to the start of the first exposure operation on the first substrate in the second lot following the first lot. ,
The exposure method according to claim 25. The first period is any one of claims 17 to 22, wherein the first period is a period from the start of the exposure operation for one shot region on the substrate to the end of the exposure operation for the one shot region. The exposure method described in 1. The second period is a period from the end of the exposure operation on the one shot region on the substrate to the start of the exposure operation on the shot region following the one shot region.
The exposure method according to claim 27. The exposure method according to any one of claims 17 to 28, wherein the temperature adjusting unit includes a first temperature control unit and a second temperature control unit arranged at different positions from each other. In the first step, the first temperature control unit generates heat so that the change in the aberration is reduced.
In the second step, the second temperature control unit generates heat so that the change in the aberration is reduced.
29. The exposure method according to claim 29. In the first step, the first temperature control unit and the second temperature control unit are controlled so that the change in the aberration is reduced.
In the second step, the first temperature control unit and the second temperature control unit are controlled so that the change in the aberration is reduced.
29. The exposure method according to claim 29. In the first step and the second step, the first temperature control unit and the second temperature control unit are allowed to change the aberration within a predetermined range so that the aberration does not deviate from the predetermined range. Is controlled,
31. The exposure method according to claim 31. Includes an exposure process that exposes the substrate through projection optics
A method of manufacturing an article in which an article is obtained from an exposed substrate.
In the exposure step, the temperature distribution of the optical element of the projection optical system is controlled so that the change in the aberration of the projection optical system due to the exposure operation being performed is reduced.
Subsequent to the exposing step, in the period during which the exposure operation is not performed, so that the change of the aberration due to exposure light operation is not performed is reduced, characterized by controlling the temperature distribution of the optical elements of the projection optical system The manufacturing method of the article. It is an article manufacturing method
An exposure step of exposing a substrate by the exposure apparatus according to any one of claims 1 to 16.
A developing step of developing the substrate exposed in the exposure step and a development step of developing the substrate.
Including a processing step of processing the substrate developed in the developing step.
A method for producing an article, which comprises obtaining an article from the substrate processed in the processing step. It is an article manufacturing method
An exposure step of exposing a substrate by the exposure method according to any one of claims 17 to 32.
A developing step of developing the substrate exposed in the exposure step and a development step of developing the substrate.
Including a processing step of processing the substrate developed in the developing step.
A method for producing an article, which comprises obtaining an article from the substrate processed in the processing step.

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