TW202144928A - Exposure apparatus, exposure method, and method for producing object that suppresses deterioration of transfer performance for transferring a pattern to a substrate in broadband illumination light - Google Patents

Abstract

The present invention relates to an exposure apparatus, an exposure method, and a method of manufacturing an article. The lowering of the transfer performance of the transfer pattern to the substrate is suppressed in broadband illumination light. An exposure apparatus for exposing a substrate using light in a wavelength range including a first wavelength range and a second wavelength range, an illumination optical system for illuminating a mask with light, and a projection optical system for projecting an image of the mask pattern on the substrate, the illumination The optical system compares at least a part of the first light intensity distribution, which is the light intensity distribution of light including at least the first wavelength range, with the light intensity of the light including at least the second wavelength range, centered on the optical axis in the pupil plane. The light intensity distribution including the first light intensity distribution and the second light intensity distribution is formed such that the second light intensity distribution of the distribution is further inward, and the first wavelength range includes a wavelength shorter than the shortest illumination wavelength of the second wavelength range. , or the second wavelength range includes at least one wavelength longer than the longest illumination wavelength of the first wavelength range.

Description

Exposure apparatus, exposure method, and manufacturing method of article

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

The exposure device is a device that transfers a pattern formed on a mask (original plate) to a flat plate (substrate), irradiates light to a mask serving as an irradiated surface through an illumination optical system, and transmits an image of the mask pattern through a projection optical system. projected onto the tablet.

The illumination optical system irradiates the optical integrator with light from the light source, and generates a secondary light source on the output surface of the optical integrator corresponding to the pupil surface of the illumination optical system. The secondary light source is formed in a light-emitting region having a predetermined shape and a predetermined size. In addition, the light-emitting region forming the secondary light source corresponds to the angular distribution of light for illuminating each point of the mask.

In an exposure apparatus, as a technique for improving the transfer performance with respect to a fine pattern, a super resolution technique (RET: Resolution Enhancement Techniques) is known. As one of RETs, anamorphic illumination that optimizes the angular distribution of light illuminating each point of the mask is known.

In Patent Document 1, in order to solve the problem of a decrease in productivity when a pattern is transferred to a flat plate coated with a resist layer with low sensitivity, there is described a method of superimposing and forming different wavelengths on the pupil plane in the illumination optical system. A technology that distributes light intensity to increase illuminance. In addition, when forming annular zone illumination as deformable illumination, for example, an i-line with a center wavelength of about 365 nm is used outside the pupil, and an example of an h line with a center wavelength of about 405 nm is used inside the pupil. [Prior Art Literature]

Patent Document 1: International Publication No. 2019/146448

[The problem to be solved by the invention]

In the technique described in Patent Document 1, the anamorphic illumination, which is one of the RETs, is used to form light source images having different wavelengths on the pupil plane in the illumination optical system, so that the illuminance can be improved. However, the depth of focus, contrast, and the like, which are indicators of the performance of optical systems and patterns, are limited to general effects produced by anamorphic illumination. That is, in the broadband illumination light (broadband illumination light), the structure of deformed illumination such that the transfer performance is sufficiently exhibited is not established.

Therefore, an object of the present invention is to provide an exposure apparatus which is advantageous in suppressing a reduction in the transfer performance of transferring a pattern onto a flat plate under broadband illumination light. [Technical means to solve the problem]

In order to achieve the above object, an exposure apparatus according to one aspect of the present invention is one that exposes a substrate using light in a wavelength range including a first wavelength range and a second wavelength range, wherein the exposure apparatus includes an illumination optical system that uses the light to expose the substrate. a mask for illumination; and a projection optical system for projecting an image of the pattern of the mask onto the substrate, the illumination optical system having a first optical axis of the illumination optical system as a center on the pupil plane of the illumination optical system A light intensity distribution including the first light intensity distribution and the second light intensity distribution is formed such that at least a part of the light intensity distribution is located further inward than the second light intensity distribution, and the first light intensity distribution includes at least the first wavelength The light intensity distribution of light in a range, the second light intensity distribution is a light intensity distribution of light including at least the second wavelength range, and the illumination optical system satisfies the first wavelength range including the shortest illumination than the second wavelength range. The shorter wavelength or the second wavelength range includes at least one of the wavelengths longer than the longest illumination wavelength in the first wavelength range. Other features of the present invention will become apparent from the following description of exemplary embodiments (with reference to the drawings). [Inventive effect]

According to the present invention, for example, it is possible to provide an exposure apparatus that is advantageous in suppressing a reduction in the transfer performance of transferring a pattern onto a substrate under broadband illumination light.

Hereinafter, preferred embodiments of the present invention will be described in detail based on the drawings. <First Embodiment>

FIG. 1 is a schematic view showing the structure of an exposure apparatus as one aspect of the present invention. The exposure apparatus 100 is a lithography apparatus that illuminates the mask (original) 9 with light including a plurality of wavelength ranges and transfers the pattern of the mask 9 onto the flat plate (substrate) 12 . The exposure apparatus 100 is an apparatus for manufacturing flat panel displays, semiconductor elements, MEMS (Micro Electro Mechanical Systems, Micro Electro Mechanical Systems), etc., and is particularly suitable for the manufacture of flat panel displays.

The exposure apparatus 100 includes an illumination optical system 10 for illuminating a mask 9 serving as an illuminated surface with light from a light source, and a projection optical system 11 for projecting an image of a pattern formed on the mask 9 onto a flat plate 12 . Furthermore, the exposure apparatus 100 includes a mask stage 13 that holds the mask 9 and drives or positions it, a flat plate stage 38 that holds the flat plate 12 and drives or positions it, and a measurement unit 14 and a control unit 15 provided on the flat plate stage 38 . The mask 9 is arranged on the object plane of the projection optical system 11, and the flat plate 12 is arranged on the image plane of the projection optical system 11 which is a position optically conjugated to the object plane.

The projection optical system 11 is, for example, a reflection optical system, and includes mirrors 32 , 34 and 36 . The projection optical system 11 reflects the light from the mask 9 in the order of the mirrors 32 , 34 , 36 , 34 , and 32 , and forms a projected image of the mask 9 on the flat plate 12 . When the projection optical system 11 is constituted by a reflective optical system, the chromatic aberration of light from the light source is smaller than that of the refractive optical system. Such a structure is suitable for the case of using broadband light (broadband illumination light) including a plurality of wavelength ranges.

The control unit 15 generally controls each part of the exposure apparatus 100 , that is, the illumination optical system 10 , the projection optical system 11 , the mask stage 13 , the flat plate stage 38 , and the like to operate the exposure apparatus 100 . The control unit 15 is composed of, for example, a PLD (abbreviation for Programmable Logic Device) such as an FPGA (abbreviation for Field Programmable Gate Array), or an ASIC (Application Specific Integrated Circuit). abbreviation), or a general-purpose or special-purpose computer embedded with a program, or a combination of all or part of them.

FIG. 2 is a schematic diagram showing a configuration example of the illumination optical system 10 in the exposure apparatus 100 . The illumination optical system 10 includes, for example, a light source 1 , a condenser lens 2 , a focus lens 5 , a fly-eye lens 7 , a focus lens 8 , and an aperture stop 61 . Although not shown in FIG. 2 , it is also possible to arrange in the light path between the focusing lens 5 and the shield 9 so that the cross section of the light illuminating the shield 9 has a predetermined shape and a predetermined size. An optical system in which light from the light source 1 is shaped. The light source 1 is, for example, a mercury lamp, and emits broadband light having a wavelength of 270 nm to 450 nm. The condenser lens 2 is arranged to condense the light emitted from the light source 1 . The light source 1 is arranged in the vicinity of the first focal point 3 of the condenser mirror 2 , and the condenser mirror 2 collects the light emitted from the light source 1 to the second focal point 4 .

The focusing lens 5 converts the light collected at the first focal point 4 into parallel light. The light converted by the focusing lens 5 is incident on the incident surface 7 a of the fly-eye lens 7 . The fly-eye lens 7 is an optical integrator composed of a plurality of optical elements, specifically, a plurality of minute lenses. The fly-eye lens 7 forms a secondary light source on the exit surface 7b according to the light incident on the entrance surface 7a. The light emitted from the fly-eye lens 7 illuminates the mask 9 in a superimposed manner via the plurality of focusing lenses 8 . The flat plate stage 38 is provided with a measurement unit 14 that is an image sensor (eg, a CCD sensor) capable of measuring the shape and light intensity of the secondary light source formed on the exit surface 7 b of the fly-eye lens 7 .

Next, super-resolution techniques (RET: Resolution Enhancement Techniques) will be described. Anamorphic illumination (oblique incidence illumination) such as annular zone illumination and quadrupole illumination, which is one of RET, is effective for improving the depth of focus (DOF) of the projection optical system 11 and the contrast of the projected image formed by the projection optical system 11 . . The annular band illumination is deformed illumination having an annular band-shaped light intensity distribution in the pupil coordinates of the illumination optical system centered on the optical axis of the illumination optical system 10, and the emission area of the annular band illumination is defined by the illumination angle σ. In the following description, the radius inside the ring-shaped light-emitting region is called inner σ, and the radius outside the ring-shaped light-emitting region is called outer σ. The illumination angle σ corresponds to the distance (radius) from the origin when expressed in pupil coordinates, and is a large radius when the illumination angle σ is large, and a small radius when the illumination angle σ is small.

In addition, the anamorphic illumination as described above can be realized by, for example, arranging the aperture stop 61 at the exit surface 7b of the fly's eye lens 7 (optical integrator) corresponding to the pupil surface of the illumination optical system 10 . Desired anamorphic illumination can be obtained by blocking light in the non-light-emitting area of anamorphic illumination by the aperture stop 61 .

In general, in anamorphic lighting, the illumination angle σ of the light-emitting region is optimized so as to suppress a decrease in transfer performance compared to the case of non-anamorphic lighting. For example, for annular band lighting, the inner σ and outer σ described above are optimized. On the other hand, in the present embodiment, a light-emitting region composed of a plurality of regions including the first light-emitting region I1 and the second light-emitting region I2 can be formed on the pupil surface of the illumination optical system 10 . The first light-emitting region I1 and the second light-emitting region I2 may be regions that do not overlap with each other, but may also be regions that overlap with each other. In addition, in the present embodiment, the first image formed on the flat panel 12 by the first light in the first wavelength range from the first light-emitting region I1 and the second image in the second wavelength range from the second light-emitting region I2 are synthesized. The second image formed by the light on the flat plate 12 .

Anamorphic illumination is a technology developed in exposure apparatuses for manufacturing semiconductor elements. In an exposure apparatus for manufacturing semiconductor elements, the half width of the spectrum of light emitted from a light source is less than 20 nm, so the illumination wavelength λ is regarded as a single illumination wavelength λ (for example, the wavelength with the maximum light intensity, weighting of the light intensity is performed) obtained after the center of gravity wavelength). On the other hand, in an exposure apparatus for manufacturing a flat panel display, broadband light (broadband illumination light) having a half width of the spectrum of light emitted from a light source of 20 nm or more can be used. Here, the full width at half width is referred to as FWHM (Full Width at Half Maximum), which is comparable to the wavelength width of the spectrum. In addition, the expression of broadband illumination light includes not only the meaning of light having a frequency band of a single bright line, but also the meaning of light having a frequency band of a plurality of bright lines.

The expression "broad band" is used in the sense of distinguishing it from the expression "narrow band" having a small half-height width such as KrF laser light and ArF laser light. Specifically, in this embodiment, the expression "broadband light" means that the full width at half maximum is 20 nm or more.

In an exposure apparatus for manufacturing a flat panel display, for example, when a mercury lamp is used as a light source and an i-line which is a single bright line in light from the mercury lamp is used, the full width at half maximum becomes about 6 nm. On the other hand, when using g-line (center wavelength about 436 nm), h-line (center wavelength about 405 nm), and i-line (center wavelength about 365 nm), which are a plurality of bright lines in the light from the mercury lamp, the half-height The width is 80 nm or more. By using a wider half-width exposure light, the illuminance can be increased, and the productivity can be improved along with it.

In this embodiment, in addition to the illumination angle σ of the light-emitting region in the deformed illumination, the illumination wavelength λ can also be optimized. By optimizing the illumination wavelength λ, the effect of improving transfer performance including contrast and depth of focus (DOF) is obtained. The DOF in the present embodiment is defined as a focus range in which the line width change associated with defocusing is 10% or less of the target line width CD (Critical Dimension, critical dimension).

在此，作為照明條件，考慮入射角θ_in 和繞射角θ_out 相等的情況。圖3為圖示入射角θ_in 和繞射角θ_out 相等的情況的圖，圖3所示的遮罩的透射光D⁰ ₂₉₀ 和1階繞射光D¹ ₂₉₀ 相對於光軸對稱地傳播。該照明條件抑制與散焦相伴的對比度的降低，與增大DOF的條件相當，成為下式。

另外，在以瞳坐標記載照明角度σ時，成為利用數值孔徑NA對sinθ_in 進行正規化而得到的值，所以在將抑制DOF的降低的變形照明的照明角度設為σ_c 時，期望σ_c 相對於投影光學系統的數值孔徑NA滿足下式。

在滿足照明條件σ=λ/(2NA･P)的情況下，在抑制DOF的降低的同時，還可期待使最佳對焦(best focus)處的對比度提高的效果。In general, by suppressing a decrease in contrast associated with defocusing, a decrease in DOF can also be suppressed. Conditions for suppressing the reduction in contrast associated with defocusing will be described with reference to FIG. 3 . 3 shows the transmission of the mask 9 when the illumination wavelength of the illumination light is 290 nm, the numerical aperture NA of the projection optical system is 0.12, and the line-and-space pattern (period 2 μm) with a line width of 1 μm is used. Light D ⁰ ₂₉₀ and first-order diffracted light D ¹ ₂₉₀ . The illumination wavelength, NA, line width, and period shown in the description of FIG. 3 are merely examples for description, and are actually arbitrarily set. Here, the formula for diffraction becomes the following formula for the period P of the mask pattern and the illumination wavelength λ, as the incident angle θ _in and the diffraction angle θ _out .

Here, as the illumination condition, the case where the incident angle θ _in and the diffraction angle θ _out are equal is considered. 3 is a diagram illustrating _{a case where the incident angle θ in} and the diffraction angle θ _out ^{are equal, the transmitted light D 0} ₂₉₀ and the first-order diffracted light D ¹ ₂₉₀ of the mask shown in FIG. 3 propagate symmetrically with respect to the optical axis. This illumination condition suppresses the decrease in contrast caused by defocusing, corresponds to the condition for increasing the DOF, and becomes the following equation.

In addition, when the illumination angle σ is written in pupil coordinates _{, it is a value obtained by normalizing sin θ in} by the numerical aperture NA. Therefore, when the illumination angle of the anamorphic illumination that suppresses the decrease in DOF is denoted by σ _c , it is desirable that σ _c The following formula is satisfied with respect to the numerical aperture NA of the projection optical system.

When the lighting condition σ=λ/(2NA･P) is satisfied, the effect of improving the contrast at the best focus can be expected while suppressing the decrease in DOF.

^{FIG. 4 shows transmitted lights D 0} ₂₉₀ and D ⁰ ₃₆₅ and first-order diffracted lights D ¹ ₂₉₀ and D ¹ ₃₆₅ of the mask 9 when the illumination wavelength of the illumination light includes light with two wavelengths of 290 nm and 365 nm. The other conditions were the same as those of FIG. 3 , and the numerical aperture NA of the projection optical system was 0.12 and a line gap pattern with a line width of 1 μm (period of 2 μm).

In the illumination shown in FIG. 4( a ), as shown in FIG. 3 , the illumination conditions satisfy the formula (3) for a wavelength of 290 nm. According to the formula (1), the diffraction angle changes with the change of the wavelength, so the optimum σ of the formula (3) also changes according to the wavelength. Therefore, in FIG. 4( a ), when the illumination wavelength is 365 nm, the illumination condition of the formula (3) is not satisfied, so the transmitted light and the diffracted light cannot propagate symmetrically with respect to the optical axis, and the DOF decreases.

In order to suppress the decrease in DOF, it can be seen from equation (3) that, in the case of long wavelengths, illumination light with a large illumination angle σ is desired, and in the case of short wavelengths, illumination light with a small illumination angle σ is desired. In the illumination shown in (b) of FIG. 4 , illumination is performed at different illumination angles σ for each wavelength in a manner that follows formula (3). Therefore, for both the wavelengths of 290 nm and 365 nm, the transmitted light and the diffracted light propagate symmetrically with respect to the optical axis, and the effect of suppressing the decrease in DOF can be obtained.

With reference to FIG. 5 , it will be described that the illumination conditions satisfying the formula (3) suppress the decrease in contrast caused by defocusing. Figure 5 shows the contrast of aerial image intensity. The numerical aperture NA of the projection optical system was set to 0.10. The graphs in (a) to (c) of FIG. 5 are diagrams showing contrast at the center line of seven line-gap patterns with a line width of 1.5 μm (period of 3.0 μm) in the exposure pattern. The graphs in (d) to (f) of FIG. 5 are contrasts at the center line of seven line-gap patterns with a line width of 1.8 μm (period 3.6 μm) in the exposure pattern. The graphs in (a) and (d) of Fig. 5 are defocused contrasts of 0 μm, the graphs of Fig. 5 (b) and (e) are defocused contrasts of 15 μm, and the graphs of (c) and (f) The graph is the contrast of the defocused 0 μm removed from the defocused 15 μm.

The graphs of (c) and (f) of FIG. 5 show the deterioration of the contrast accompanying the defocus, and the darker the gray, the greater the deterioration of the contrast. Here, the condition under which the contrast ratio becomes less than 0.3 at a defocus of 15 μm is assumed to be black as a condition that is not practical from the viewpoint of transfer performance. The wavelength of the horizontal axis in FIG. 5 is 340 nm to 460 nm including the g-line, h-line, and i-line of the mercury spectrum. The vertical axis of FIG. 5 represents the inner σ in the annular zone illumination, and it is assumed that the outer σ is a value larger than the inner σ by 0.05. This corresponds to annulus illumination that is thin enough to practically equate the inner σ and outer σ. The black solid line in the graph represents the relationship between the illumination wavelength λ and the illumination angle σ, which are the optimal illumination conditions satisfying the formula (3). As can be seen from FIG. 5 , the condition indicated by the black solid line satisfying the formula (3) is that the decrease in contrast due to defocusing is small. As can be seen from the above, with the lighting conditions satisfying the formula (3), it is possible to suppress a decrease in contrast caused by defocusing.

Contrast is low and defocusing is accompanied by a large deviation from the black solid line, which is the optimum illumination condition satisfying the formula (3) (especially when the illumination wavelength λ is on the long wavelength side and the illumination angle σ is small) The deterioration of the contrast ratio is also large. Therefore, regarding the combination of the illumination wavelength λ and the illumination angle σ corresponding to a condition that greatly deviates from the optimal illumination condition satisfying the formula (3), for example, it is desirable to block light by using a wavelength filter. In addition, the patterns with a line width of 1.8 μm (period 3.6 μm) shown in (d) to (f) of FIG. 5 are different from the patterns with a line width of 1.5 μm (period 3.0 μm) shown in (a) to (c) of FIG. 5 . greater than contrast. In addition, a high-definition pattern with a short line width generally has a tendency to deteriorate the contrast.

In addition, in FIG. 5 , a high contrast ratio is exhibited even under a condition slightly deviated from the black solid line which is the optimum illumination condition satisfying the formula (3). As shown in (d) of FIG. 5 , with a pattern with a line width of 1.8 μm and a defocus of 0 μm, under the illumination conditions that deviate from the black solid line, for example, the illumination wavelength is 365 nm, and the illumination angle σ=0, high contrast is exhibited, There are possibilities that can be used as lighting conditions. When it is desired to increase the illuminance, it is desirable to set the wavelength width as wide as possible and to increase the annular band width. Therefore, as long as it is in the range showing the contrast ratio that is practical in terms of performance, the lighting conditions that deviate significantly from the black solid line, which is the optimum lighting condition, can be used, and it becomes possible to increase the transfer performance while obtaining sufficient transfer performance. Great illumination.

In the anamorphic illumination of the present embodiment, DOF is improved by the effect of oblique incident illumination compared to illumination of a general circular shape (that is, illumination in which the internal σ is zero). The deformed illumination of the present embodiment has the effect of suppressing a decrease in illuminance and suppressing a decrease in productivity compared to a narrow annular belt known as one method of deformable illumination. In addition, in the anamorphic illumination of the present embodiment, since the annular band width is wider than the narrow annular band width, the illuminance unevenness caused by the unevenness of the illumination intensity caused by the fly's eye lens is reduced. The deformed illumination of the present embodiment can also suppress a decrease in transfer performance for patterns of a period other than the pattern P of a specific period, as compared with the narrow belt illumination with a narrow belt width.

In addition, although there is a method of improving the resolution by shortening the illumination wavelength, the anamorphic illumination of the present embodiment improves the resolution without completely shielding the long-wavelength illumination light. Therefore, the light quantity of the long-wavelength illumination light can also be used without waste, so that the decrease in illuminance (that is, the decrease in productivity) can be suppressed. In addition, the deformed illumination of the present embodiment may provide effects such as suppressing a reduction in resolution due to manufacturing errors of the phase shift mask, and controlling the sidewall angle of the resist pattern.

The deformed illumination of this embodiment can also be applied to polarized illumination. The light source is not limited to the mercury lamp, but also includes a case where broadband illumination is formed by using an LED light source or a plurality of semiconductor light sources. It is also possible to adjust the transmittance of the wavelength filter in the illumination optical system to adjust the intensity distribution to be different from the spectral intensity distribution of the mercury lamp. Fiber optic bundles can also be used in illumination optics. By using the first light-emitting region I1 and the second light-emitting region I2 having different σ suitable for the respective wavelength ranges, it is possible to suppress a decrease in transfer performance. In addition, an effect of improving the illumination illuminance can be expected as compared with the deformed illumination using a single wavelength.

The deformed illumination of the present embodiment has described the illumination conditions that satisfy the formula (3), but may have an illumination angle that completely satisfies the formula (3) for all illumination wavelengths in the first wavelength range λ1 in the first light emitting region I1 The structure of σ, but not limited to this. In addition, the configuration may have an illumination angle σ that completely satisfies the formula (3) with respect to all illumination wavelengths in the second wavelength range λ2 in the second light emitting region I2, but is not limited to this. The illumination condition that partially satisfies the formula (3) may be, for example, a modification including an illumination angle σ that satisfies the formula (3) for the illumination wavelength of a part of the first light-emitting region I1 and the illumination wavelength of a part of the second light-emitting region I2 Just lighting.

<Example 1> Using FIG. 6 , it is shown that the transfer performance of the illumination light in Example 1 of the present embodiment is higher than that of the four comparative examples. FIG. 6 is a graph showing simulation results of illumination of Comparative Example and Example 1. FIG. Set the numerical aperture NA to 0.10. Regarding the mask pattern, the center line of seven line-gap patterns with a line width of 1.8 μm (period of 3.6 μm) was evaluated. The region of the lattice pattern of the illumination shape shown in FIG. 6 is broadband light with a wavelength of 340 nm to 460 nm, and includes three bright lines g-line, h-line, and i-line of the mercury lamp. The wavelength of the region of the oblique pattern of the illumination shape is broadband light of 340 nm to 390 nm, which includes one bright line i line of the mercury lamp.

The description will be made in order from the left in FIG. 6 . Comparative Example 1 is the illumination of g-line, h-line, and i-line with inner σ=0.00 and outer σ=0.90. That is, it is lighting that exhibits a circular light intensity distribution. Comparative Example 2 is the illumination of g-line, h-line, and i-line with inner σ=0.00 and outer σ=0.83. The reason why the outer σ is set to 0.83 is to set the same illuminance as the illumination of the present embodiment described later. In Comparative Example 3, the g-line, h-line, and i-line were illuminated in an annular zone with inner σ=0.45 and outer σ=0.90. In Comparative Example 4, the region of inner σ=0.00 and outer σ=0.45 was the illumination of g-line, h-line, and i-line, and the region of inner σ=0.45 and outer σ=0.90 was illumination of i-line. In Comparative Example 4, in the region of inner σ=0.00 and outer σ=0.45, a longer wavelength is included than the region of inner σ=0.45 and outer σ=0.90. This is a configuration in which the relationship between the illumination angle σ and the illumination wavelength λ is opposite to that of the present embodiment described later, and the optimum illumination condition shown by the formula (3) is not satisfied.

In Example 1, the region with inner σ=0.00 and outer σ=0.45 is the illumination of i-line, and the region of inner σ=0.45 and outer σ=0.90 is the illumination of g-line, h-line and i-line. In Example 1, in the region of inner σ=0.45 and outer σ=0.90, a longer wavelength is included than the region of inner σ=0.00 and outer σ=0.45. This is a configuration that satisfies the optimum lighting conditions shown by the formula (3).

Each performance of the illumination of Comparative Examples 1-4 and Example 1 was compared. First, compare the normalized illuminance. The normalized illuminance refers to the illuminance obtained by normalizing the illuminance of Comparative Example 1 to 1 and normalizing the other illuminances, and the area of the illumination shape and the spectral intensity distribution of the mercury lamp are considered. The normalized illuminance of Comparative Example 1 is the largest. Compared with Comparative Examples 3 and 4, the illumination of the present embodiment is larger and surpasses the performance in terms of illuminance. In addition, in Comparative Example 2, since the external σ was determined so as to be the same illuminance as that of Example 1 as described above, the normalized illuminance was the same.

Next, compare the contrast. The contrast in this embodiment refers to the contrast of the aerial image intensity of the center line. It can be seen that the contrast in Example 1 is larger than that in Comparative Examples 1 to 4. That is, it shows that the performance is improved.

Next, compare the MEEF (Mask Error Enhancement Factor). MEEF refers to the ratio of the line width error ΔCD _resist of the resist pattern exposed on the flat panel to the mask line width error (manufacturing error) ΔCD _mask , and is defined by MEEF=ΔCD _resist /ΔCD _mask ･･･(4). The smaller the value of MEEF, the better the performance. It turns out that MEEF in Example 1 is smaller than Comparative Examples 1-4. That is, it shows that the performance is improved.

Next, compare DOF. DOF refers to the in-focus range in which the line width change accompanying defocusing is 10% or less of the target line width CD, and is the in-focus range in which the center line of 1800 nm at the best focus becomes 1980 nm or less. The larger the DOF value, the better the performance. It can be seen that the DOF in Example 1 is larger than that in Comparative Examples 1, 2, and 4. That is, it shows that the performance is improved. However, when Example 1 and Comparative Example 3 are compared, the DOF of Comparative Example 3, which is a ring-shaped illumination, is large.

Next, compare the sidewall angles. The sidewall angle refers to the angle of the bottom of the resist pattern of the center line. The larger the value of the side wall angle (ie, the closer to 90°), the better the performance. It can be seen that the side wall angle in Example 1 is larger than that in Comparative Examples 1 to 4. That is, it shows that the performance is improved.

Summarize the above comparison. The illumination of Example 1 has improved performance in terms of transfer performance regarding contrast, MEEF, DOF, and side wall angle, compared to the circular illuminations shown in Comparative Examples 1 and 2. The illumination of Example 1 had higher illuminance than the endless belt illumination shown in Comparative Example 3, and exhibited high performance in terms of transfer performance related to contrast, MEEF, and side wall angle. Moreover, compared with the comparative example 4, the illumination of Example 1 showed high performance in the normalized illuminance, contrast, MEEF, DOF, and side wall angle. From this result, it is shown that the effect of resolution improvement is not sufficient only by changing the wavelength for each illumination area, and equation (3) needs to be considered to use an appropriate illumination area for each wavelength. In the illumination in Example 1 of the present embodiment, the formula (3) is considered to use an appropriate illumination region for each wavelength, so that higher performance is exhibited than that of Comparative Examples 1 to 4.

Therefore, the illumination in Example 1 of the present embodiment can simultaneously achieve suppression of reduction in transfer performance and large illuminance by including the illumination wavelength λ and the illumination angle σ satisfying the illumination conditions shown in formula (3).

<Example 2> In Example 2, the results of evaluating the illumination of the present embodiment with a mask pattern different from that in Example 1 will be described. Using FIG. 7 , it is shown that the transfer performance of the illumination light in Example 2 of the present embodiment is higher than that of the three comparative examples.

FIG. 7 is a graph showing simulation results of lighting of three comparative examples and Example 2. FIG. Set the numerical aperture NA to 0.10. The mask pattern was a one-dimensional line-gap pattern in which a line width of 1.2 μm (period of 3.6 μm) was twice the line width of the line. The region of the check pattern of the illumination shape shown in FIG. 7 is broadband light with a wavelength of 340 nm to 460 nm, and includes three bright lines g-line, h-line, and i-line of the mercury lamp. The wavelength of the region of the oblique pattern of the illumination shape is broadband light of 340 nm to 390 nm, which includes one bright line i line of the mercury lamp. Here, the lighting shape of Example 2 is the same as that of Example 1, and the lighting shapes of Comparative Examples 1 to 3 are also the same as those of Comparative Examples 1 to 3 described in Example 1.

In Example 2, as in Example 1, compared with Comparative Examples 1 and 2, the normalized illuminance was inferior, but it exhibited high performance in contrast, MEEF, DOF, and side wall angle. Compared with Comparative Example 3, the DOF was poor, but high performance was exhibited in normalized illuminance, contrast, MEEF, and side wall angle.

Therefore, by including the illumination wavelength λ and the illumination angle σ that satisfy the illumination conditions shown in the formula (3), the illumination in Example 2 of the present embodiment can simultaneously achieve suppression of a reduction in transfer performance and a large illuminance.

<Example 3> In Example 3, the result of evaluating the illumination of the present embodiment in the case where the transmittance of the wavelength filter is not controlled, which is not performed in Examples 1 and 2, will be described. In addition, Example 3 has a numerical aperture NA, a mask pattern, and an illumination wavelength different from those of Example 1 and Example 2. 8 shows that the transfer performance of the illumination light in Example 3 of the present embodiment is higher than that of the various comparative examples.

8 is a graph showing simulation results of illumination of Comparative Example and Example 3. FIG. Set the numerical aperture NA to 0.12. Regarding the mask pattern, the center lines of nine line-gap patterns with a line width of 1.2 μm (period of 2.4 μm) were evaluated. The wavelength of the region of the horizontal stripe pattern of the illumination shape shown in FIG. 8 is broadband light of 270 nm to 390 nm, and includes the bright line i line of the mercury lamp and the wavelength shorter than the i line. The wavelength of the longitudinal stripe pattern and the check pattern area of the illumination shape is a broadband light of 270 nm to 350 nm, and the wavelength of 350 nm or less is a wavelength shorter than the i-line of the mercury lamp, excluding the i-line. In the area of the check pattern, the transmittance was set to 25%, and the illuminance was reduced compared with that of the longitudinal stripe pattern. As will be described later, by setting the transmittance to be small, there is an effect of increasing the DOF.

Regarding the area of the horizontal stripe pattern and the area of the vertical stripe pattern, the illumination light intensity from the mercury lamp may be used as it is, or the light may be controlled by passing through a wavelength filter. The illuminance was evaluated as the normalized illuminance, and the uniform transmittance reduction was set arbitrarily over the entire area of the pupil. The spectral intensity distribution of the mercury lamp is assumed to be a general distribution, but there is no restriction on this distribution.

In Comparative Example 5, the illumination wavelength was 270 nm to 390 nm in the circular region of inner σ=0.00 and outer σ=0.90. In Comparative Example 6, in the annular zone region where the inner σ=0.45 and the outer σ=0.90, the annular zone illumination of the illumination with the illumination wavelength of 270 nm to 390 nm was performed. In Comparative Example 7, in the circular region with inner σ=0.00 and outer σ=0.55, the illumination wavelength is 270 nm to 350 nm, and in the annular region with inner σ=0.55 and outer σ=0.90, the illumination wavelength is Illumination from 270nm to 390nm. Comparative Example 7 has a structure including a longer wavelength in the region of inner σ=0.55 and outer σ=0.90 than the region of inner σ=0.00 and outer σ=0.55 so as to match the formula (3).

In Example 3, in the circular region with inner σ=0.00 and outer σ=0.45, the illumination wavelength is 270 nm to 350 nm, and in the annular region with inner σ=0.45 and outer σ=0.90, the illumination wavelength is Illumination from 270nm to 390nm. As described above, the illuminance is reduced by setting the transmittance to 25% in the region of inner σ=0.00 and outer σ=0.45 shown by the lattice stripes.

In comparison with Comparative Example 6, Comparative Example 7 showed high performance in terms of normalized illuminance, contrast, MEEF, and side wall angle, but the DOF was significantly reduced. Therefore, by using the illumination shape of Example 3, the reduction of DOF can be relatively suppressed as will be described later.

Compared with Comparative Example 5, Example 3 was inferior in normalized illuminance, but exhibited high performance in contrast, MEEF, DOF, and side wall angle. The DOF is slightly inferior to that of Comparative Example 6, but higher performance is exhibited in normalized illuminance, contrast, MEEF, and side wall angle. Compared with Comparative Example 7, the increase in DOF was remarkable. Comparative Example 7 is also one of the examples of the present invention, but in Example 3, the transfer performance such as DOF can be adjusted by controlling the transmittance of the wavelength filter.

Therefore, in the illumination in Example 3 of the present embodiment, by controlling the transmittance of the wavelength filter used in addition to taking into account the formula (3), it is possible to simultaneously achieve suppression of a reduction in transfer performance and a large illuminance.

<Example 4> In Example 4, the illumination of the present embodiment, which is an illumination shape different from the illumination shape described in Examples 1 to 3, will be described.

FIG. 9 is a diagram showing six types of illumination in this embodiment. FIG. 9( a ) is an illumination shape in which wavelengths become longer, such as i-line, h-line, and g-line, as it goes from the area inside the pupil to the area outside the pupil. This is an illumination shape that satisfies the relationship between the illumination wavelength λ and the illumination angle σ shown in the formula (3). (b) of FIG. 9 is a case where the h-line is used in the area inside the pupil and the g-line and the i-line are used in the area outside the pupil. Since the g-line with a longer wavelength is used on the outer side than that used on the inner side, the illumination shape satisfies the relationship between the illumination wavelength λ and the illumination angle σ shown in the formula (3). (c) of FIG. 9 is a case where g-line, h-line, and i-line are used for the area inside the pupil and g-line and h-line are used for the area outside the pupil. The short wavelength (i-line) of the region outside the truncated pupil satisfies the relationship between the illumination wavelength λ and the illumination angle σ shown in the formula (3). In addition, when comparing the barycentric wavelength of the wavelength used in the inner region and the barycentric wavelength of the wavelength used in the outer region, the barycentric wavelength used in the outer region is longer. The center of gravity wavelength refers to a wavelength corresponding to the center of gravity when the spectral distribution of illumination light is considered as a weight. This corresponds to an example in which the first wavelength range used for circular illumination includes shorter wavelengths than the second wavelength range used for annular band illumination.

In addition, in the foregoing description, the first light intensity distribution has a circular shape and the second light intensity distribution has been described as a rotationally symmetric light intensity distribution, but the present invention is not limited to this. For example, the first light intensity distribution may have a non-circular shape and an annular shape, or the second light intensity distribution may have a rotationally asymmetric shape.

(d) of FIG. 9 is a case where g-lines and i-lines are used in the annular zone-shaped region inside the pupil and h-lines are used in the annular-shaped region outside the pupil. This is an illumination shape that satisfies the relationship between the illumination wavelength λ and the illumination angle σ shown in equation (3) when the intensity of the g-line is small and the inner barycenter wavelength is shorter than the outer wavelength h-line. (e) of FIG. 9 is a case where the i-line is used in the circular-shaped region inside the pupil and the h-line is used in the region of the structure in which a part of the annular shape is missing, such as the outer pupil. This is an illumination shape that satisfies the relationship between the illumination wavelength λ and the illumination angle σ shown in the formula (3). FIG. 9( f ) shows the case where the h-line is used in a cross-shaped region with the circular-shaped region inside the pupil, and the g-line is used in the region where a part of the annular shape outside the pupil is missing. This is an illumination shape that satisfies the relationship between the illumination wavelength λ and the illumination angle σ shown in the formula (3).

In the anamorphic illumination of the present embodiment, at least a part of the first light intensity distribution including the light including the first wavelength range is positioned more inward than the second light intensity distribution including the light including the second wavelength range. The light intensity distribution is formed on the pupil plane of the optical system. In addition, it is satisfied that the first wavelength range includes at least one wavelength shorter than the shortest illumination wavelength of the second wavelength range, or that the second wavelength range includes wavelengths longer than the longest illumination wavelength of the first wavelength range.

Here, the g-line, h-line, and i-line used in Example 4 are examples used to indicate the magnitude of the relative wavelengths, and the wavelengths are not limited. In Example 4, even in the case of an illumination shape different from the illumination shape described in Examples 1 to 3, by including the illumination wavelength λ and illumination angle σ satisfying the illumination conditions shown in the formula (3), it is possible to Suppression of reduction in transfer performance and large illuminance are simultaneously achieved.

<Second Embodiment> In this embodiment, the configuration of the illumination optical system 10 that can realize the illumination described in the first embodiment will be described.

(a) of FIG. 10 shows the case where the light source 1 is constituted by the first light source 1a and the second light source 1b. The first light source 1a and the second light source 1b emit light of mutually different wavelengths. In addition, the wavelengths of the first light source 1a and the second light source 1b may be light of a single wavelength, a narrow wavelength range, or broad-band light. Even if it is a light source with a single wavelength and a narrow wavelength range, when a plurality of light sources are used to form illumination light having mutually different wavelength ranges, it is regarded as broadband illumination.

The light-emitting portion of the anamorphic illumination described in the first embodiment includes the first light-emitting region I1 and the second light-emitting region I2, the first wavelength range λ1 in the first light-emitting region I1 and the second wavelength range in the second light-emitting region I2 λ2 is different. This anamorphic illumination is formed by combining the illumination light of the first light source 1a and the illumination light of the second light source 1b. Alternatively, the first light source 1a and the second light source 1b may form different light-emitting regions and then combine them. Alternatively, the same light emitting region may be formed by the first wavelength range λ1 and the second wavelength range λ2, and the wavelength ranges of the first light emitting region I1 and the second light emitting region I2 may be changed by a wavelength filter. In addition, as described in Example 3 of the first embodiment, the transmittance may be changed in an arbitrary region of the filter. In addition, an LED light source may be used as the light source 1, and the number of the light source 1 may be three or more instead of two.

(b) of FIG. 10 shows a case where the light source 1 is constituted by three broadband light sources 1c. The broadband light source 1c emits light having a wide wavelength range. The light emitted from the three broadband light sources 1c is set to the same wavelength range. Different light-emitting regions having different wavelength ranges can also be formed for each light source by using the wavelength filters 63a, 63b, and 63c shown in (b) of FIG. 10 . Alternatively, instead of using the wavelength filters 63a, 63b, and 63c, the wavelength filter 63d shown in (b) of FIG. 10 may be used to combine the illumination light from the three broadband light sources 1c to form a wavelength filter having different wavelength ranges. Glowing area. In addition, the wavelength filters 63a, 63b, 63c and the wavelength filter 63d may be used in combination. The wavelength filters 63a, 63b, 63c, and 63d may be mounted on a rotating turntable or a grating-type mechanism driven by a shift. This facilitates switching between the case of using the wavelength filter and the case of not using the wavelength filter. FIG. 10( b ) shows a case where there are three light sources 1c constituting the light source 1 , but this is not limiting. For example, the number of light sources 1c may be one, and the number of light sources 1c is not limited. The present embodiment does not limit the methods related to the division of the wavelength range and the formation of the light-emitting region.

The wavelength filter may reduce the transmittance of the desired wavelength, and may not completely block the transmittance to zero at the desired wavelength. In addition, it is not necessary to completely divide the wavelength range at the boundary portion of the light-emitting region. Furthermore, not only the wavelength selection by the wavelength filter, but also by using a hologram element, a diffractive optical element, and a prism, the reduction of the illuminance can be suppressed.

＜Production method of article＞ Next, the manufacturing method of the article (flat panel display, liquid crystal display element, semiconductor IC element, MEMS, etc.) using the said exposure apparatus is demonstrated. The manufacturing method of the article includes a procedure of forming a latent image pattern in a photosensitive agent applied to a flat plate using the above-mentioned exposure device (a procedure of exposing the flat plate) and a procedure of developing the flat plate after forming the latent image pattern in the above procedure . Furthermore, the above-described manufacturing method includes procedures for performing other known treatments (oxidation, film formation, vapor deposition, doping, planarization, etching, resist peeling, dicing, bonding, packaging, and the like). The manufacturing method of the article of the present embodiment is more advantageous than the conventional method in at least one of the performance, quality, productivity, and production cost of the article.

As mentioned above, although preferable embodiment of this invention was described, this invention is not limited to these embodiment, Various deformation|transformation and change are possible within the range of the summary. For example, the present invention can also be applied to multiple exposures. In addition, in order to increase the effect of anamorphic lighting, NA can also be optimized. The anamorphic illumination of the present invention can also be applied to a maskless exposure device.

9: Mask 10: Lighting Optical System 11: Projection Optical System 12: Tablet 100: Exposure device

[ FIG. 1 ] is a schematic diagram showing the structure of an exposure apparatus. [ Fig. 2 ] is a schematic diagram showing the structure of an illumination optical system. [ Fig. 3] Fig. 3 is a diagram showing the optimum illumination conditions for annular band illumination of a single wavelength. [ Fig. 4] Fig. 4 is a diagram showing optimal illumination conditions for annular band illumination of a plurality of wavelengths. [ Fig. 5] Fig. 5 is a diagram showing a change in contrast according to lighting conditions. [ Fig. 6] Fig. 6 is a diagram showing the effect of deformed illumination in Example 1. [Fig. [ Fig. 7] Fig. 7 is a diagram showing the effect of deformed illumination in Example 2. [Fig. [ Fig. 8] Fig. 8 is a diagram showing the effect of deformed illumination in Example 3. [Fig. [ Fig. 9] Fig. 9 is a diagram showing an example of deformed lighting in the first embodiment. [ Fig. 10] Fig. 10 is a diagram showing a configuration example of an illumination optical system in anamorphic illumination.

Claims (16)

An exposure apparatus for exposing a substrate using light in a wavelength range including a first wavelength range and a second wavelength range, the exposure apparatus having: an illumination optical system that illuminates the mask with the aforementioned light; and a projection optical system that projects an image of the pattern of the mask onto the substrate, The illumination optical system is formed to include the first light on the pupil plane of the illumination optical system so that at least a part of the first light intensity distribution is located more inward than the second light intensity distribution with the optical axis of the illumination optical system as the center. An intensity distribution and a light intensity distribution of the second light intensity distribution, the first light intensity distribution being a light intensity distribution including at least the light in the first wavelength range, and the second light intensity distribution being a light intensity distribution including at least the second wavelength range. light intensity distribution, In the exposure apparatus, the first wavelength range includes a wavelength shorter than the shortest illumination wavelength in the second wavelength range, or the second wavelength range includes a longer illumination wavelength than the longest illumination wavelength in the first wavelength range. at least one of the wavelengths. The exposure apparatus of claim 1, wherein, The aforementioned second light intensity distribution is a ring-shaped light intensity distribution. The exposure apparatus of claim 1, wherein, The first light intensity distribution is a circular light intensity distribution. The exposure apparatus of claim 1, wherein, The light intensity distribution formed on the aforementioned pupil plane is rotationally symmetric. The exposure apparatus of claim 1, wherein, When the numerical aperture of the projection optical system is NA, the period of the pattern of the mask is P, the illumination wavelength is λ, and the illumination angle defining the light-emitting area is σ, at least one of the light The combination of λ and σ satisfies σ=λ/(2NA･P). The exposure apparatus of claim 5, wherein, The combination of at least one λ and σ of the light in the first wavelength range and the combination of at least one λ and σ of the light in the second wavelength range satisfy σ=λ/(2NA･P). The exposure apparatus of claim 1, wherein, At least one of the first wavelength range and the second wavelength range includes a wavelength corresponding to the bright line of the mercury lamp. The exposure apparatus of claim 1, wherein, At least one of the first wavelength range and the second wavelength range includes broadband light having a wavelength width of 20 nm or more. The exposure apparatus of claim 1, wherein, At least one of the first wavelength range and the second wavelength range includes a plurality of bright lines of a mercury lamp. The exposure apparatus of claim 1, wherein, The first wavelength range described above corresponds to the g-line and h-line of the bright line of the mercury lamp, The aforementioned second wavelength range corresponds to the i-line of the bright line of the mercury lamp. The exposure apparatus of claim 1, wherein, At least one of the first wavelength range and the second wavelength range includes a wavelength of 350 nm or less. The exposure apparatus of claim 1, wherein, The aforementioned illumination optical system includes a wavelength filter that controls the transmittance of light in a specific wavelength range among the aforementioned plurality of wavelength ranges to form the aforementioned light intensity distribution. The exposure apparatus of claim 1, wherein, The longest wavelength in the first wavelength range is a wavelength shorter than the shortest wavelength in the second wavelength range. The exposure apparatus of claim 1, wherein, The first wavelength range and the second wavelength range correspond to bright lines of mutually different mercury lamps. An exposure method comprising: exposing a substrate using light in a wavelength range including a first wavelength range and a second wavelength range, the exposure method comprising: The first procedure, which is to illuminate the mask with the aforementioned light; and The second procedure is to project the image of the pattern of the mask on the substrate, In the first procedure, the first light intensity distribution and the second light intensity are formed such that at least a part of the first light intensity distribution is located more inward than the second light intensity distribution on the pupil plane of the illumination optical system. distributed light intensity distribution, wherein the first light intensity distribution is a light intensity distribution that includes at least light in the first wavelength range, and the second light intensity distribution is a light intensity distribution that includes at least light in the second wavelength range, In the exposure method, at least one of the first wavelength range includes a wavelength shorter than the illumination wavelength in the second wavelength range, or the second wavelength range includes a longer wavelength than the illumination wavelength in the first wavelength range. one side. A method of manufacturing an article, comprising: An exposure procedure that exposes a substrate using the exposure apparatus according to any one of claims 1 to 14; A developing process, which is to develop the substrate exposed in the aforementioned exposure process; and A processing program, which is to perform at least one of oxidation, film formation, vapor deposition, doping, planarization, etching, resist stripping, dicing, bonding, and packaging for the substrate developed in the aforementioned development process; Articles are fabricated from substrates processed in the aforementioned processing procedures.

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