JP2008130827A - Exposure apparatus and exposure method - Google Patents

Abstract

The present invention provides a high-resolution and high-precision exposure apparatus by suppressing fluctuations in rotationally asymmetric optical characteristics that occur when the center of a region where exposure light is incident is shifted from the center of an optical element.
An exposure apparatus includes an exposure light source that emits exposure light, an asymmetric incident optical element, and a driving means. The asymmetric incident optical element 15 has a central axis, and the central position of the asymmetric incident optical element 15 is shifted from the central position of the exposure light incident area 21 that is an area where the exposure light is incident. The driving means 16 rotates the asymmetric incident optical element 15 about its central axis.
[Selection] Figure 2

Description

  The present invention relates to an exposure apparatus and an exposure method, and more particularly, to an exposure apparatus and an exposure method with high resolution and high accuracy.

  In recent years, semiconductor integrated circuits have been highly integrated, and even now, when the gate length is less than 100 nm, miniaturization is being continued according to Moore's law. Therefore, in lithography, an argon fluoride (ArF) laser beam having a wavelength of 193 nm is used, and a resolution that is half or less of the exposure wavelength is required.

  In addition, the exposure apparatus requires a certain depth of focus together with the resolution in order to absorb fluctuations in the surface height of the wafer, variations in focus detection, and the like.

  As a method for realizing such ultra-high resolution and depth of focus, an immersion method in which a liquid such as water is filled between the lower surface of the projection optical system and the wafer surface has been proposed (see, for example, Patent Document 1). .) Since the wavelength of exposure light in liquid is 1 / n in air (where n is the refractive index of the liquid), the resolution can be improved and the depth of focus can be increased by using the immersion method. .

  On the other hand, when the wavelength of the exposure light is shortened, it is necessary to lengthen the optical path of the projection optical system. For this reason, when a refractive optical system is used as the projection optical system of the exposure apparatus, the lens barrel length is significantly increased. Therefore, the height of the exposure apparatus greatly exceeds 3 meters, and the ceiling height of the current clean room must be greatly increased in consideration of the ceiling height for performing maintenance of the apparatus. In reality, it is difficult to significantly change the ceiling height of the current clean room, and a so-called catadioptric optical system in which a reflective mirror is combined with a refractive optical system is employed (see, for example, Patent Document 2). .)

For pattern formation with a half pitch of 32 nm or less, it is considered promising to use extreme ultraviolet rays (EUV) having a shorter wavelength than ArF laser light as a light source of an exposure apparatus. The system is also expected to be catadioptric optical system.
International Publication No. 99/49504 Pamphlet JP 2006-100429 A

  However, the catadioptric optical system has the following problems. In general, an optical element is made of a material having a high transmittance with respect to light having an exposure wavelength. However, it is inevitable that the optical element slightly absorbs light. When light is absorbed by the optical element, the light is converted into heat energy, so that heat is accumulated in the optical element. As a result, a temperature distribution is generated between the region irradiated with the exposure light and the region not irradiated with the exposure light in the optical element. When a temperature distribution is generated in the optical element, lens heating that changes the optical characteristics of the optical element occurs. When the temperature distribution of the optical element is rotationally symmetric with respect to the center axis of the optical element, the optical characteristics also change so as to be rotationally symmetric with respect to the center of the optical element. Variations occur. Such variation can be corrected relatively easily by making the apparatus have an optical variation coefficient with respect to the exposure amount, and making optical adjustment for each exposure amount.

  On the other hand, when the temperature distribution of the optical element is not rotationally symmetric with respect to the central axis of the optical element, fluctuations in optical characteristics occur such as an increase in astigmatism and a change in focal position off the optical axis. . It is technically difficult to correct such a change in optical characteristics by fine adjustment of the optical system.

  The catadioptric optical system is roughly divided into two types, a uni-axial system and a multi-axial system. In either of the optical elements, the exposure light is the central axis of the optical element. Means that the light is incident on a region whose center is shifted. For example, in a uni-axial optical system as shown in FIG. 8, since the reticle image is projected only on the left half of the lens on the lens G11 closest to the reticle M, the center of the projection area The center of the lens deviates greatly. For this reason, the temperature of the left half of the lens rises and the glass material constituting the lens expands unevenly, so that the lens is distorted rotationally asymmetrically.

  In addition, the Schwartschild optical system and the like employed in EUV may cause non-rotationally symmetric thermal expansion on the optical element by the same mechanism, and may cause rotationally asymmetric fluctuations in optical characteristics.

  The present invention solves the above-described conventional problems, suppresses rotationally asymmetric fluctuations in optical characteristics that occur when the center of the area where exposure light is incident is shifted from the center of the optical element, and achieves high resolution and high accuracy. It is an object to realize an exposure apparatus.

  In order to achieve the above object, the present invention is configured such that the exposure apparatus is provided with means for rotating an optical element having the center of a region where exposure light is incident at a position deviated from the central axis.

  Specifically, a first exposure apparatus according to the present invention includes an exposure light source that emits exposure light, a central axis, and the central axis of the exposure light incident area that is an area where the exposure light is incident. The asymmetric incident optical element is shifted, and driving means for rotating the asymmetric incident optical element about its central axis is provided.

  According to the first exposure apparatus, since the drive means for rotating the asymmetric incident optical element about its central axis is provided, the center of the exposure light incident area and the central axis of the optical element are shifted from each other. In the element, light can be incident on a region other than the exposure light incident region. Accordingly, since the thermal expansion of the asymmetrical incident optical element can be rotationally symmetric with respect to the center of the asymmetrical incident optical element, the rotationally asymmetric optical characteristic variation that is difficult to correct is generated in the asymmetrical incident optical element. It becomes possible to suppress. As a result, an exposure apparatus with high resolution and high accuracy can be realized.

  It is preferable that the first exposure apparatus further includes position detection means for detecting the rotational position of the asymmetric incident optical element. With such a configuration, the asymmetrical incident optical element is rotated, and light is incident on an area other than the exposure light incident area to correct thermal expansion, and then the asymmetrical incident optical element is returned to its original position. It becomes possible to return accurately. For this reason, it is possible to prevent the aberration accuracy from deteriorating.

  In this case, the position detecting means preferably includes a marker attached to the asymmetric incident optical element and a detector for detecting the marker.

  The second exposure apparatus according to the present invention has an exposure light source that emits exposure light, an asymmetrical axis that has a central axis, and the central axis of the exposure light incident area that is an area where the exposure light is incident is shifted. An incident optical element; and compensation light irradiation means for irradiating the asymmetric incident optical element with compensation light for compensating the temperature distribution of the asymmetric incident optical element so as to have rotational symmetry with respect to the central axis thereof. Features.

  According to the second exposure apparatus, there is provided compensation light irradiating means for irradiating the asymmetric incident optical element with compensation light for compensating the temperature distribution of the asymmetric incident optical element so as to have rotational symmetry with respect to the central axis. Therefore, it is possible to prevent uneven thermal expansion from occurring in the asymmetric incident optical element. Therefore, it is possible to suppress the occurrence of rotationally asymmetric optical characteristic fluctuations that are difficult to be corrected in the asymmetric incident optical element, so that an exposure apparatus with high resolution and high accuracy can be realized.

  In the second exposure apparatus, the compensation light is preferably applied to the entire asymmetric incident optical element, and may be applied to an area other than the exposure light incident area in the asymmetric incident optical element. In addition, the position of the compensation light irradiation region and the position of the exposure light incident region in the asymmetric incident optical element are preferably rotationally symmetric with respect to the central axis of the asymmetric incident optical element. By adopting such a configuration, the temperature distribution of the asymmetrical incident optical element can be surely rotationally symmetric with respect to the central axis.

  In the second exposure apparatus, the compensation light irradiating means preferably includes a compensation light source that emits compensation light and a compensation light optical system that controls an optical path through which the compensation light is incident on the asymmetric incidence optical element. By adopting such a configuration, it becomes possible to irradiate the compensation light to a specific region of the asymmetric incident optical element.

  In this case, the compensation light optical system preferably has a zoom mechanism for controlling the size of the irradiation region of the compensation light in the asymmetric incident optical element. Moreover, it is preferable to have a scanning mechanism for controlling the position of the compensation light irradiation region in the asymmetrical incident optical element. With such a configuration, it becomes possible to control the amount of compensation light, the irradiation range, and the irradiation position, and the temperature control of the asymmetrical incident optical element can be performed with higher accuracy.

  In the second exposure apparatus, it is preferable that the second exposure apparatus further includes driving means for rotating the asymmetric incident optical element about its central axis. Even with such a configuration, the compensation light can be incident on the optimal position of the asymmetrical incident optical element.

  The first and second exposure apparatuses preferably further include a temperature distribution measuring unit that measures the temperature distribution of the asymmetric incident optical element. With such a configuration, it becomes possible to reliably compensate for the temperature distribution of the asymmetrical incident optical element. Further, it becomes possible to allow the compensation light to be incident only when the temperature distribution is biased, and it is possible to improve the working efficiency. Furthermore, accurate temperature control is possible.

  In this case, the temperature distribution measuring means includes an infrared sensor or a thermocouple embedded in the outer peripheral portion of the asymmetric incident optical element.

  In the first and second exposure apparatuses, the asymmetric incident optical element is preferably a lens or a reflecting mirror.

  The exposure method according to the present invention includes a step (a) in which exposure light from an exposure light source is incident on an exposure light incident region whose center position is deviated from the central axis of the optical element, and irradiating the optical element with compensation light. And (b) compensating the temperature distribution of the optical element so as to have rotational symmetry with respect to the central axis of the optical element.

  The exposure method of the present invention includes a step of compensating the temperature distribution of the optical element so as to have rotational symmetry with respect to the central axis of the optical element by irradiating the optical element with compensation light. The characteristic thermal expansion can be made isotropic. Accordingly, since it is possible to suppress the occurrence of rotationally asymmetric characteristic fluctuations that are difficult to correct in the optical element, it is possible to realize an exposure apparatus with high resolution and high accuracy.

  In the exposure method of the present invention, the position of the compensation light incident area and the position of the exposure light incident area in the optical element are preferably rotationally symmetric with respect to the central axis of the optical element. With such a configuration, it becomes possible to ensure the temperature distribution of the optical element in rotational symmetry with respect to the central axis of the optical element.

  In the exposure method of the present invention, the compensation light is emitted from the exposure light source, and the amount of exposure light in step (a) is preferably equal to the amount of compensation light in step (b). With such a configuration, it becomes possible to ensure the temperature distribution of the optical element in rotational symmetry with respect to the central axis of the optical element. Also, the compensation operation is facilitated.

  In the exposure method of the present invention, the compensation light is light having a wavelength different from that of the exposure light, and the compensation light in step (b) is absorbed by the optical element of the exposure light in the amount of exposure light in step (a). It is preferable that the amount of light is obtained by multiplying the value of the ratio between the coefficient and the heat absorption coefficient of the compensation light to the optical element. With such a configuration, an inexpensive light source can be used as the compensation light source, and the running cost can be suppressed.

  In the exposure method of the present invention, a step (c) for measuring the temperature distribution of the optical element is further provided between the steps (a) and (b), and in the step (b), the temperature distribution is predetermined. This is preferably performed when the condition is satisfied. By adopting such a configuration, it becomes possible to perform irradiation of compensation light only when necessary, and work efficiency can be improved.

  In the exposure method of the present invention, prior to step (a), the temperature distribution of the optical element after executing step (a) is predicted, and based on the predicted temperature distribution, the compensation light in step (b) It is preferable that the method further includes a step (d) of calculating the amount of light and the position of the compensation light incident area. By adopting such a configuration, it becomes possible to perform compensation light irradiation in a necessary range only when necessary, and work efficiency can be improved.

  In this case, the step (d) preferably includes a step of predicting a temperature distribution from the exposure conditions set as an exposure recipe, the mask type, the exposure amount, the number of shots, and the number of exposures.

  According to the exposure apparatus and the exposure method of the present invention, it is possible to suppress a rotationally asymmetric variation in optical characteristics that occurs when the center of a region where exposure light is incident deviates from the center of the optical element, and to achieve high resolution and high accuracy. A simple exposure apparatus can be realized.

(First embodiment)
A first embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows a main part of an exposure apparatus according to the first embodiment. The exposure apparatus according to the first embodiment includes an exposure light source 11 that emits, for example, an argon fluoride (ArF) laser beam, and a projection optical system 14 that projects a pattern of the reticle mask 12 onto a substrate 13. .

  The projection optical system 14 is a catadioptric optical system composed of a plurality of optical elements, each of which is a lens or a reflecting mirror. At least one of the plurality of optical elements is exposure light on which exposure light is incident. This is an asymmetric incident optical element in which the center of the incident region is shifted from the central axis of the optical element.

  FIG. 2 is an enlarged view of a portion of the asymmetric incident optical element 15 provided in the projection optical system 14 of the exposure apparatus in the present embodiment. The asymmetrical incident optical element 15 of the present embodiment is a lens, and the exposure light from the exposure light source 11 enters the exposure light incident area 21 centered at a position shifted from the central axis of the lens.

  When the exposure light is incident on the asymmetrical incident optical element 15, the exposure light incident area 21 rises in temperature due to light absorption and thermally expands. On the other hand, since the temperature rise in the region where the exposure light is not incident is smaller than that in the exposure light incident region 21, the asymmetric incident optical element 15 is distorted due to thermal expansion. If the center of the exposure light incident area and the central axis of the optical element coincide, the temperature distribution of the optical element has rotational symmetry with respect to the central axis of the optical element, so that distortion also has rotational symmetry. . For this reason, the fluctuation | variation of the optical characteristic by distortion can be correct | amended. However, in the case of the asymmetrical incident optical element 15 in which the center of the exposure light incident area and the central axis of the optical element do not coincide with each other, rotationally asymmetric distortion occurs, resulting in fluctuations in optical characteristics that are difficult to correct.

  However, the asymmetric incident optical element 15 of the present embodiment is connected to the driving means 16, and the asymmetric incident optical element 15 can be rotated around its central axis. For this reason, when the exposure light enters the exposure light incident area 21 and the temperature of the exposure light incident area 21 rises, and the temperature distribution of the optical element has a rotationally asymmetric bias, the asymmetric incident optical element 15 , And the exposure light is incident on the other region, so that the temperature distribution in the asymmetrical incident optical element 15 can be compensated so as to have rotational symmetry. The entire lens barrel to which the asymmetric incident optical element 15 is attached may be rotated.

  Compensation exposure for irradiating exposure light to compensate for the temperature distribution may be performed on the compensation light incident area 22 that is rotationally symmetric with the exposure light incident area 21 with respect to the central axis of the asymmetrical incident optical element 15. Further, the amount of light at this time may be made equal to the amount of light incident on the exposure light incident area 21. In this way, since the temperature distribution of the asymmetric incident optical element 15 is rotationally symmetric with respect to the central axis, the distortion of the asymmetric incident optical element 15 is rotationally symmetric with respect to the central axis. Therefore, it is possible to compensate for variations in the optical characteristics of the asymmetric incident optical element 15.

  Further, the temperature distribution of the asymmetric incident optical element 15 may be made uniform by uniformly irradiating the area other than the exposure light incident area 21 in the asymmetric incident optical element 15.

  Compensation exposure is effective every time a single wafer is exposed, but from the viewpoint of productivity and running cost, it is performed every time a certain number of wafers are processed, or every lot. It is preferable to do.

  Further, the temperature distribution of the asymmetric incident optical element 15 may be predicted based on an exposure recipe or the like, and the compensation exposure may be performed when the predicted value exceeds the allowable range. Specifically, a correlation between parameters such as the exposure amount, illumination conditions, and the number of shots and the temperature distribution of the asymmetric incident optical element 15 is obtained in advance by empirical values or calculations. In addition, when setting the illumination conditions, mask type, exposure amount, number of shots, number of exposures, etc. as an exposure recipe before exposure, the exposure amount and the number of exposure shots are calculated based on previously obtained experience values or calculated values. From the calculated heat accumulation amount per unit area of the asymmetric incident optical element 15 and the exposure interval calculated from the number of exposures and the number of shots, the heat accumulation amount for each shot in the asymmetric incident optical element 15 is calculated. By calculating the amount of compensation exposure and the area to be compensated based on this result and performing compensation exposure, the temperature distribution of the asymmetrical incident optical element 15 can be managed with high accuracy.

  Further, as shown in FIG. 3, a temperature distribution measuring means 17 for monitoring the temperature distribution of the asymmetric incident optical element 15 is provided, and when the temperature distribution of the asymmetric incident optical element 15 deviates from the allowable range, other than the exposure light incident area 21 Irradiation of exposure light to the region may be performed.

  In this case, the temperature distribution measuring means 17 may be an infrared sensor, for example. Further, the temperature distribution of the asymmetric incident optical element 15 may be measured by attaching a thermocouple or the like to the asymmetric incident optical element 15.

  The specific allowable temperature distribution depends on the material and design of the asymmetric incident optical element 15, and the amount of compensation light irradiation depends on the heat absorption coefficient per unit area of the compensation light in the asymmetric incident optical element 15. It is preferable to determine by empirical or calculation.

  Further, an exposure apparatus used for manufacturing a semiconductor device is required to perform a line width control of several nm in a shot, and aberration accuracy required for a lens is high. When sufficient performance cannot be obtained with the current lens processing accuracy, the aberration is suppressed by optimizing by combining a plurality of lenses. For this reason, when a plurality of optical elements are used in the projection optical system, it is desirable that the exposure light always transmits or reflects the same part of the optical element. For this reason, it is preferable to provide position detecting means 18 for detecting the rotational position of the asymmetric incident optical element 15 so that the asymmetric incident optical element 15 can be accurately returned to the original position after the compensation exposure.

  For example, as shown in FIG. 4, the position detection means 18 may be configured by a position marker 32 provided on the side surface of the asymmetric incident optical element 15 and a detector 33 that is a position sensor for detecting the position marker 32. In this case, a plurality of position markers 32 are installed on the side surface of the asymmetrical incident optical element 15, and a plurality of detectors 33 are installed so that at least the positions of two or more position markers 32 can be read at the exposure position. It is preferable. In this way, after the asymmetric incident optical element 15 is rotated and compensated exposure is performed, the asymmetric incident optical element can be accurately returned to the original position.

  In this way, it is also possible to manage the area where the compensation light is incident with high accuracy. In the case where the entire lens barrel to which the asymmetric incident optical element 15 is attached is rotated, the position marker 32 may be provided on the lens barrel instead of the asymmetric incident optical element 15 itself.

(Second Embodiment)
The second embodiment of the present invention will be described below with reference to the drawings. FIG. 5 is an enlarged view of a portion of the asymmetric incident optical element provided in the projection optical system 14 of the exposure apparatus according to the second embodiment. In FIG. 5, the same components as those of FIG.

  As shown in FIG. 5, the exposure apparatus of this embodiment includes a compensation light irradiation unit. The compensation light irradiation means of the present embodiment is a compensation light source 41 provided separately from the exposure light source. For this reason, the compensation light source 41 is provided in the vicinity of the asymmetric incident optical element 15, and the asymmetric incident optical element 15 is irradiated with the compensation light so as to sufficiently exceed the heat generation amount of the asymmetric incident optical element 15 due to exposure light exposure. If the temperature of the entire optical element 15 is maintained, temperature compensation of the asymmetric incident optical element 15 can be easily performed.

  In this case, the compensation light may be incident on the entire asymmetric optical element 15 or may be incident on a region other than the exposure light incident region 21 using a mask or the like. The compensation light source 41 is not particularly limited, and a halogen lamp or the like can be used. By using an inexpensive light source for the compensation light source 41, the running cost of the compensation light source 41 can be suppressed.

  Further, as shown in FIG. 6, the compensation light irradiating means may be a combination of the compensation light source 41 and the compensation optical system 42 so that the compensation light is incident on the compensation light incident region 22 of the asymmetrical incident optical element 15. In this case, overall heat generation can be suppressed. In FIG. 6, the compensation optical system 42 includes a light shielding box 42a in which a compensation light source 41 made of a halogen lamp is housed, a lens 42b and a lens 42c for condensing the compensation light extracted from the light shielding box 42a, and a lens 42c for compensating light. And a zoom mechanism 43 that moves along the optical axis. The light shielding box 42 a is not particularly necessary when a directional light source is used as the compensation light source 41. The zoom mechanism 43 is for controlling the amount of compensation light by zooming the size of the compensation light incident area 22 irradiated with exposure light, and may be provided as necessary.

  The compensation light incident region 22 where the compensation light in the asymmetric incident optical element 15 enters may be a region that is rotationally symmetric with respect to the central axis of the exposure light incident region 21 and the asymmetric incident optical element 15. Alternatively, a region where the temperature distribution of the asymmetric incident optical element 15 is most uniform may be selected by cut-and-try.

When the compensation light source 41 is provided separately from the exposure light source 11, since the wavelength of the compensation light and the wavelength of the exposure light are different, the heat generated by the asymmetric incident optical element 15 differs between the exposure light and the compensation light. For this reason, the heat absorption coefficient K1 for the exposure light and the heat absorption coefficient K2 for the compensation light are empirically or simulated in consideration of the glass material forming the asymmetric incident optical element 15, the reflection coating material, and the reflection analysis material. And the amount of compensation light may be obtained by the following equation.
Compensation light amount = exposure light amount × (K1 / K2)
For example, when ArF laser light is used as exposure light, halogen lamp light is used as compensation light, and the asymmetrical incident optical element is a quartz lens, K1 / K2 is 0.92. What is necessary is just to set it as 0.92 times the light quantity of light.

  Further, as shown in FIG. 7, a scanning mechanism 44 is provided in the compensation optical system 42 using, for example, a movable reflection mirror 42d and a movable lens 42e, and the compensation light incident region 22 for irradiating the compensation light is formed as an asymmetric incidence optical. You may enable it to set in the arbitrary positions of the element 15. FIG. In this case, the temperature distribution of the asymmetrical incident optical element 15 can be obtained with high accuracy by calculating the optimum position of the compensation light incident area 22 for each exposure recipe to be used and performing the compensation exposure by empirical values or simulations based on the exposure recipe. It becomes possible to manage.

  Further, as shown in the first embodiment, a temperature distribution measuring means for monitoring the temperature distribution is provided, and the compensation exposure is performed by calculating the position of the compensation light incident area 22 in the asymmetric incident optical element 15 based on the monitoring result. If it carries out, it will become possible to manage the temperature distribution of the asymmetrical incident optical element 15 with higher accuracy.

  Instead of setting the region where the compensation light is incident by driving the compensation optical system 42, the region where the compensation light is incident is set by rotating the asymmetric incidence optical element 15 as in the first embodiment. May be. The driving of the compensation optical system 42 and the rotation of the asymmetric incident optical element 15 may be used in combination.

  Also in the exposure apparatus of the second embodiment, the timing for performing the compensation exposure may be determined based on the prediction or actual measurement of the temperature distribution, even as a constant interval, as in the first embodiment.

  In the second embodiment, the halogen lamp is used as the compensation light source 41. However, any light source may be used as long as it can be absorbed and heated by the asymmetric incident optical element 15. If the same light source as the exposure light source is used, there is a problem such as running cost, but there is a merit that the amount of exposure light can be calculated easily and accurately.

  In the first embodiment and the second embodiment, the case where the asymmetrical incident optical element 15 is a lens has been described, but a reflection mirror may be used. A plurality of asymmetric incident optical elements 15 may be included in the projection optical system 14.

  Further, although the case where the exposure light is ArF laser light has been described, it may be krypton fluoride laser light, extreme ultraviolet light, or the like.

  Further, the present invention is not limited to a catadioptric optical system, and can be applied to a case where an optical element that allows exposure light to enter a region having a center shifted from the center of the optical element.

  The exposure apparatus and the exposure method of the present invention suppress high-resolution and high-accuracy exposure apparatus by suppressing fluctuations in rotationally asymmetric optical characteristics that occur when the center of a region where exposure light is incident is shifted from the center of an optical element. In particular, it is useful as a high-resolution and high-precision exposure apparatus and exposure method used for manufacturing semiconductor devices.

1 is a schematic view showing an exposure apparatus according to a first embodiment of the present invention. It is the schematic which shows the principal part of the exposure apparatus which concerns on the 1st Embodiment of this invention. It is the schematic which shows the modification of the principal part of the exposure apparatus which concerns on the 1st Embodiment of this invention. It is the schematic which shows the modification of the principal part of the exposure apparatus which concerns on the 1st Embodiment of this invention. It is the schematic which shows the principal part of the exposure apparatus which concerns on the 2nd Embodiment of this invention. It is the schematic which shows the modification of the principal part of the exposure apparatus which concerns on the 2nd Embodiment of this invention. It is the schematic which shows the modification of the principal part of the exposure apparatus which concerns on the 2nd Embodiment of this invention. It is the schematic which shows the projection optical system of the exposure apparatus which concerns on a prior art example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Exposure light source 12 Reticle mask 13 Substrate 14 Projection optical system 15 Asymmetric incident optical element 16 Drive means 17 Temperature distribution measurement means 18 Position detection means 21 Exposure light incidence area 22 Compensation light incidence area 32 Position marker 33 Detector 41 Compensation light source 42 Compensation Optical system 42a Shading box 42b Lens 42c Lens 42d Reflective mirror 42e Lens 43 Zoom mechanism 44 Scanning mechanism

Claims (21)

An exposure light source that emits exposure light;
An asymmetrical incident optical element having a central axis, the central axis of which is shifted from the central position of the exposure light incident region, which is a region where the exposure light is incident,
An exposure apparatus comprising: driving means for rotating the asymmetric incident optical element about its central axis.   2. The exposure apparatus according to claim 1, further comprising position detection means for detecting a rotational position of the asymmetric incident optical element.   The exposure apparatus according to claim 2, wherein the position detection unit includes a marker attached to the asymmetric incident optical element and a detector that detects the marker. An exposure light source that emits exposure light;
An asymmetrical incident optical element having a central axis, the central axis of which is shifted from the central position of the exposure light incident region, which is a region where the exposure light is incident,
Compensation light irradiating means for irradiating the asymmetric incidence optical element with compensation light for compensating the temperature distribution of the asymmetric incidence optical element so as to have rotational symmetry with respect to the central axis thereof. Exposure device.   The exposure apparatus according to claim 4, wherein the compensation light is applied to the entire asymmetric incident optical element.   The exposure apparatus according to claim 4, wherein the compensation light is applied to a region other than the exposure light incident region in the asymmetric incident optical element.   The position of the compensation light irradiation region and the position of the exposure light incident region in the asymmetric incident optical element are positions that are rotationally symmetric with respect to a central axis of the asymmetric incident optical element. 4. The exposure apparatus according to 4.   The compensation light irradiation means includes a compensation light source that emits the compensation light, and a compensation light optical system that controls an optical path through which the compensation light is incident on the asymmetric incident optical element. Item 8. The exposure apparatus according to Item 6 or 7.   9. The exposure apparatus according to claim 8, wherein the compensation light optical system includes a zoom mechanism that controls a size of an irradiation region of the compensation light in the asymmetric incident optical element.   The exposure apparatus according to claim 8, wherein the compensation light optical system includes a scanning mechanism that controls a position of an irradiation region of the compensation light in the asymmetric incident optical element.   11. The exposure apparatus according to claim 6, further comprising a driving unit configured to rotate the asymmetric incident optical element about a central axis thereof.   The exposure apparatus according to claim 1, further comprising a temperature distribution measuring unit that measures a temperature distribution of the asymmetric incident optical element.   The exposure apparatus according to claim 12, wherein the temperature distribution measuring unit includes an infrared sensor or a thermocouple embedded in an outer peripheral portion of the asymmetric incident optical element.   The exposure apparatus according to claim 1, wherein the asymmetric incident optical element is a lens or a reflecting mirror. Making the exposure light from the exposure light source enter an exposure light incident area whose center position is deviated from the central axis of the optical element (a);
And (b) compensating the temperature distribution of the optical element so as to have rotational symmetry with respect to the central axis of the optical element by irradiating the optical element with compensation light. Exposure method.   The position of the compensation light incident area and the position of the exposure light incident area in the optical element are positions that are rotationally symmetric with respect to the central axis of the optical element. Exposure method. The compensation light is emitted from the exposure light source,
The exposure method according to claim 15 or 16, wherein a light amount of the exposure light in the step (a) is equal to a light amount of the compensation light in the step (b). The compensation light is light having a wavelength different from that of the exposure light,
The compensation light in the step (b) includes the heat absorption coefficient of the exposure light to the optical element and the heat absorption coefficient of the compensation light to the optical element in the amount of the exposure light in the step (a). The exposure method according to claim 15, wherein the exposure method has a light quantity multiplied by a value of the ratio. A step (c) of measuring a temperature distribution of the optical element between the step (a) and the step (b);
The exposure method according to claim 15, wherein the step (b) is performed when the temperature distribution satisfies a predetermined condition.   Before the step (a), the temperature distribution of the optical element after the execution of the step (a) is predicted, and based on the predicted temperature distribution, the amount of the compensation light in the step (b) The exposure method according to claim 15, further comprising a step (d) of calculating a position of an incident area of the compensation light.   21. The step (d) includes a step of predicting the temperature distribution from an exposure condition set as an exposure recipe, a mask type, an exposure amount, a shot number, and an exposure number. An exposure method according to 1.

Images