Exposure method, exposure apparatus, and device manufacturing method

Abstract

This exposure method comprises: illuminating a first object with exposure light including first exposure light of a first wavelength and second exposure light of a second wavelength different from the first wavelength; and exposing an image of a pattern of the first object on a second object by the exposure light from the first object, the exposing comprising forming a first image of the pattern of the first object by the first exposure light from the first object, and forming a second image of the pattern of the first object by the second exposure light from the first object at a position farther from the surface of the second object than the first object in the traveling direction of the second exposure light. The intensity of the second exposure light with which the second object is irradiated is higher than the intensity of the first exposure light with which the second object is irradiated.　

Description

Exposure method, exposure apparatus, and device manufacturing method

[0001] The present invention relates to an exposure method, an exposure apparatus, and a device manufacturing method.

[0002] In a lithography process for manufacturing microdevices (electronic devices, etc.) such as semiconductor elements and liquid crystal display elements, a pattern having a large depth relative to its width (high aspect ratio), i.e., a groove, may be exposed to light in a photosensitive material layer on a substrate (glass plate, semiconductor wafer, etc.) (see, for example, Patent Document 1).

[0003] US Patent Application Publication No. 2019 / 0204756

[0004] According to a first aspect of the disclosure, there is provided an exposure method including: illuminating a first object with exposure light including first exposure light of a first wavelength and second exposure light of a second wavelength different from the first wavelength; and exposing an image of a pattern of the first object onto a second object using the exposure light from the first object, wherein the exposing includes forming a first image of the pattern of the first object using the first exposure light from the first object; and forming a second image of the pattern of the first object using the second exposure light from the first object at a position farther from the surface of the second object than the first image in the traveling direction of the second exposure light, and wherein the intensity of the second exposure light irradiated onto the second object is higher than the intensity of the first exposure light irradiated onto the second object.

[0005] According to a second aspect of the disclosure, there is provided an exposure method including: illuminating a first object with exposure light including first exposure light of a first wavelength and second exposure light of a second wavelength different from the first wavelength; and exposing a second object moving along a scanning direction with the exposure light from the first object, wherein the exposing includes forming a first image of a pattern of the first object with the first exposure light from the first object; and forming a second image of the pattern of the first object with the second exposure light from the first object at a position farther from the surface of the second object than the first image in the traveling direction of the second exposure light, and wherein a timing at which the second exposure light is irradiated onto the second object is different from a timing at which the first exposure light is irradiated onto the second object.

[0006] According to a third aspect of the disclosure, there is provided an exposure apparatus including an illumination optical system that illuminates a first object with exposure light including first exposure light of a first wavelength and second exposure light of a second wavelength different from the first wavelength, and a projection optical system that projects an image of a pattern of the first object onto a second object using the exposure light from the first object, wherein the projection optical system forms a first image of the pattern of the first object using the first exposure light from the first object, and forms a second image of the pattern of the first object using the second exposure light from the first object at a position farther from the surface of the second object than the first image in the traveling direction of the second exposure light, and wherein the intensity of the second exposure light irradiated onto the second object is higher than the intensity of the first exposure light irradiated onto the second object.

[0007] According to a fourth aspect of the disclosure, there is provided an exposure apparatus that scans and exposes a pattern of a first object onto a second object, the exposure apparatus comprising: an illumination optical system that illuminates the first object with exposure light including first exposure light of a first wavelength and second exposure light of a second wavelength different from the first wavelength; a projection optical system that projects the exposure light from the first object onto a second object moving along a scanning direction; and a control device that controls a light source that supplies the exposure light to the illumination optical system, wherein the projection optical system forms a first image of the pattern of the first object with the first exposure light from the first object, and forms a second image of the pattern of the first object with the second exposure light from the first object at a position farther from the surface of the second object than the first image in the traveling direction of the second exposure light, and the control device controls the timing at which the second exposure light is irradiated onto the second object to be different from the timing at which the first exposure light is irradiated onto the second object.

[0008] According to a fifth disclosed aspect, there is provided a device manufacturing method including: exposing a photosensitive material layer of the second object using the above-described exposure method; and processing an area inside the photosensitive material layer of the second object using a pattern generated by developing the exposed photosensitive material layer as a mask.

[0009] The configurations of the embodiments described below may be modified as appropriate, and at least a portion of the configuration may be replaced with other components. Furthermore, components that are not particularly limited in terms of their placement may be placed in any position that can achieve their function, not limited to the placement disclosed in the embodiments.

[0010] FIG. 1 is a diagram showing a schematic configuration of an exposure apparatus according to an embodiment. FIG. 2(A) is a diagram showing a schematic configuration of a light source unit, and FIG. 2(B) is a diagram illustrating the wavelengths of light emitted from each solid-state laser light source. FIG. 3 is a diagram showing an example of a spatial light modulator. FIG. 4 is a diagram for explaining axial chromatic aberration. FIG. 5(A) is a schematic diagram showing a mask used in the simulation, and FIG. 5(B) is a schematic diagram showing a substrate and resist used in the simulation. FIGS. 6(A) to 6(E) are diagrams showing the results of a simulation of the intensity distribution of a pattern image formed in a resist when light L1 to light L5 are irradiated onto the resist at the same intensity. FIG. 7 is a diagram showing the relationship between the wavelength and intensity of light in an embodiment. FIG. 8 is a diagram showing the results of a simulation of the intensity distribution of a pattern image formed in a resist when a mask is illuminated with illumination light in which the intensities of light L1 to L5 are adjusted. FIGS. 9(A) and 9(B) show the results of a simulation of the intensity distribution of each k for cases where the numerical aperture NA is 0.4 and 0.5. ２ 10A and 10B are diagrams showing the results of simulating the NILS, uniformity, and number of wavelengths for the numerical apertures NA of 0.6 and 0.7, respectively. ２ 11A is a graph showing the results of simulating the NILS, uniformity, and number of wavelengths for the case where the numerical aperture NA is 0.8. ２ 11A and 11B show the results of simulating the NILS, uniformity, and number of wavelengths in the case where the numerical aperture NA is 1.35. ２FIG. 12 is a diagram illustrating chromatic aberration of magnification. FIG. 13A is a diagram illustrating the distribution of chromatic aberration of magnification in the projection optical system, and FIG. 13B is a diagram illustrating the distribution of chromatic aberration of magnification after scan averaging. FIGS. 14A and 14B are diagrams illustrating the results of simulating the intensity distribution of the composite pattern image after scan averaging, where FIG. 14A is the intensity distribution on a plane perpendicular to the Y axis, and FIG. 14B is the intensity distribution on a plane perpendicular to the X axis. FIG. 15 is a diagram illustrating the emission timing of light L1 to light L5. FIG. 16 is a diagram illustrating the results of simulating the intensity of the composite pattern image in a cross section perpendicular to the X axis, obtained by shifting the emission timing of light L1 to light L5 as shown in FIG. 15. 17(A) to 17(C) are diagrams showing the simulation results of the intensity of composite pattern images formed in the resist by the methods of Comparative Examples 1 to 3, and FIG. 17(D) is a diagram showing the simulation results of the intensity of composite pattern images formed in the resist by the method of this embodiment.

[0011] It is desired to form a pattern with a high aspect ratio, which has a constant width in the depth direction and a small slope of the inner wall, in a photosensitive material layer on a substrate (such as a glass plate or a semiconductor wafer).

[0012] An exposure apparatus 100 according to this embodiment will be described below with reference to FIGS.

[0013] 1 is a diagram showing the schematic configuration of an exposure apparatus 100 according to this embodiment. Exposure apparatus 100 is an exposure apparatus that uses a spatial light modulator (SLM) that modulates illumination light (exposure light) according to control by an exposure control unit 160, which will be described later.

[0014] 1, exposure apparatus 100 includes an illumination system 110, a pattern generator 120, a projection optical system 130, a stage device 140, an alignment detection system 150, and an exposure controller 160. In describing exposure apparatus 100, two mutually orthogonal directions in a horizontal plane are referred to as the X direction and the Y direction, and the direction orthogonal to the X and Y directions is referred to as the Z direction. Furthermore, the rotation (tilt) directions around the X axis, the Y axis, and the Z axis are referred to as the θx direction, the θy direction, and the θz direction, respectively. In this embodiment, the X direction is referred to as the scanning direction.

[0015] The illumination system 110 includes a light source unit 111 , an illumination optical system 112 , and a reflecting mirror 113 .

[0016] FIG. 2A is a diagram showing a schematic configuration of the light source unit 111. The light source unit 111 includes a plurality of solid-state laser light sources. In this embodiment, the light source unit 111 includes a first solid-state laser light source SLS1, a second solid-state laser light source SLS2, a third solid-state laser light source SLS3, a fourth solid-state laser light source SLS4, and a fifth solid-state laser light source SLS5. Each of the solid-state laser light sources SLS1 to SLS5 may be a solid-state laser device that amplifies laser light emitted from a laser light source such as a DFB semiconductor laser using a fiber optical amplifier and then converts the wavelength of the amplified laser light using a wavelength conversion element. Such solid-state laser devices are disclosed, for example, in U.S. Patent Nos. 7,339,661, 7,974,320, 9,153,934, and 9,160,132.

[0017] The first solid-state laser light source SLS1 emits illumination light (exposure light) L1 with a peak wavelength λ1 that illuminates a spatial light modulator 121 (described later). The second solid-state laser light source SLS2 emits illumination light (exposure light) L2 with a peak wavelength λ2 that illuminates the spatial light modulator 121. The third solid-state laser light source SLS3 emits illumination light (exposure light) L3 with a peak wavelength λ3 that illuminates the spatial light modulator 121. The fourth solid-state laser light source SLS4 emits illumination light (exposure light) L4 with a peak wavelength λ4 that illuminates the spatial light modulator 121. The fifth solid-state laser light source SLS5 emits illumination light (exposure light) L5 with a peak wavelength λ5 that illuminates the spatial light modulator 121. In the following description, the illumination lights L1 to L5 will be referred to as light L1 to light L5.

[0018] FIG. 2B is a diagram showing the peak wavelengths λ1 to λ5 of the light beams L1 to L5 emitted from the first to fifth solid-state laser light sources SLS1 to SLS5, respectively. As shown in FIG. 2B, the peak wavelengths λ1 to λ5 are discrete, and in this embodiment, λ1 < λ2 < λ3 < λ4 < λ5. For convenience, FIG. 2B shows the light beams L1 to L5 with the same intensity, but the intensities of the light beams L1 to L5 will be described later. Also, while FIG. 2B shows the intervals between adjacent peak wavelengths as constant, this is not a limitation. The intervals between adjacent peak wavelengths may be irregular.

[0019] The first to fifth solid-state laser light sources SLS1 to SLS5 change the intensity of the light they emit and the timing of emitting the light based on instructions from the exposure control unit 160. The instructions from the exposure control unit 160 may also be referred to as trigger signals.

[0020] The illumination optical system 112 includes a shaping optical system for changing illumination conditions, an optical integrator, a field stop, and a relay lens system (none of which are shown). The illumination optical system 112 emits illumination light (exposure light) IL including light L1 to L5 emitted from the light source unit 111. Because the illumination light IL includes light L1 to L5, it can be said to be light having multiple peak wavelengths or light having a discrete wavelength distribution.

[0021] The pattern generating device 120 generates a pattern to be formed on a wafer W placed on a stage 141 (described later) of the stage device 140 under the control of the exposure control unit 160. In this embodiment, the wafer W includes a substrate 601 and a resist 602 (photosensitive material layer) applied on the substrate 601.

[0022] The pattern generating device 120 includes a spatial light modulator 121 and a driving unit 122 .

[0023] 3 is a diagram showing an example of the spatial light modulator 121. As shown in FIG. 3, the spatial light modulator 121 has a plurality of micromirror mechanisms M arranged in a matrix (two-dimensional, array) within the XY plane, for example. Each micromirror mechanism M has a micromirror M1 and a drive mechanism M2 provided on the opposite side of the reflective surface of the micromirror M1. The drive mechanism M2 moves the micromirror M1 (up and down) along an axis extending in the Z direction.

[0024] The drive unit 122 drives the drive mechanism M2 of each of the multiple micromirror mechanisms M in accordance with a control signal from the exposure control unit 160, and switches the micromirror M1 between an on state (on position) and an off state (off position).

[0025] Here, since the size of each micromirror M1 is too small for the projection optical system 130 to resolve, when all the micromirrors M1 are in the on state or all are in the off state within an area that can be resolved by the projection optical system 130, the zeroth-order diffracted light IL0 of the illumination light IL from the illumination system 110 that enters that area is incident on the projection optical system 130. For example, 2×2 micromirrors M1 may be located within an area that can be resolved by the projection optical system 130. On the other hand, when the illumination light (exposure light) IL from the illumination system 110 enters an area where on-state micromirrors M1 and off-state micromirrors M1 are alternately located, the illumination light IL is diffracted in this area, and the zeroth-order diffracted light IL0 of the illumination light IL almost disappears, while the ±1st-order or higher diffracted light IL1 of the illumination light IL reaches a non-exposure optical path that is outside the projection optical system 130. The pattern generating device 120 imparts a pattern to the illumination light IL by setting each of the multiple micromirrors M1 to either the on state or the off state. In the following description, the surface on which a plurality of micromirrors M1 set to either the on state or the off state are arranged may be referred to as the light modulation surface of the spatial light modulator 121.

[0026] The spatial light modulator 121 is not limited to the piston type described above, and may be, for example, a magneto-optic spatial light modulator (MOSLM) or a digital mirror device (DMD). Although the spatial light modulator 121 has been described as a reflective type that reflects the illumination light IL, the spatial light modulator 121 may be a transmissive type that transmits the illumination light IL, or a diffractive type that diffracts the illumination light IL. The spatial light modulator 121 may be any type that can spatially and temporally modulate the illumination light IL.

[0027] The projection optical system 130 reduces and projects an image of the light modulation surface of the spatial light modulator 121 onto the wafer W placed on the stage 141 at a projection magnification β (β=1 / 200, 1 / 400, 1 / 500, etc., as examples). That is, an exposure pattern is formed on the wafer W by an energy beam transmitted through the pattern generating device 120. The projection optical system 130 has a lens barrel 130s and a plurality of optical elements (not shown) arranged in a predetermined positional relationship inside the lens barrel 130s.

[0028] The stage device 140 includes a stage (substrate stage) 141 , a laser interferometer 142 , and a stage driver 143 .

[0029] The stage 141 holds the wafer W via a wafer holder (not shown) provided at the center of the upper surface. The stage 141 is movable in the X, Y, and Z directions by a stage driving unit 143, and is rotatable around an axis extending in the Z direction.

[0030] The laser interferometer 142 constantly detects the position of the stage 141 in the X direction, Y direction, and θz direction with a resolution of, for example, about 0.5 to 1 nm by irradiating a measurement beam onto the reflecting surfaces provided on the end faces of the stage 141 in the X direction and Y direction.

[0031] The stage driving unit 143 drives the stage 141 in accordance with a control signal from the exposure control unit 160 .

[0032] The alignment detection system 150 is disposed on the side of the projection optical system 130. In this embodiment, an imaging type alignment sensor is used as the alignment detection system 150. A detailed configuration of the alignment detection system 150 is disclosed in, for example, U.S. Pat. No. 5,637,129.

[0033] The alignment detection system 150 detects street lines and position detection marks formed on the wafer W. The detection results of the street lines and position detection marks by the alignment detection system 150 are output to the exposure control unit 160.

[0034] The exposure control unit 160 controls the operation of the illumination system 110, pattern generation device 120, stage device 140, etc. so as to form a predetermined exposure pattern on the wafer W, and projects an image of the light modulation surface of the spatial light modulator 121 onto the wafer W held on the stage 141 via the projection optical system 130.

[0035] When the spatial light modulator 121 is illuminated by illumination light IL from the illumination system 110, the illumination light IL reflected by the micromirror M1 of the spatial light modulator 121, i.e., the illumination light IL that has been given a pattern by the spatial light modulator 121, enters the projection optical system 130, and a reduced image (partially inverted image) of the pattern is formed in the projection area IA on the wafer W held on the stage 141.

[0036] In this embodiment, the exposure control unit 160 performs exposure by a step-and-scan method. During the scan exposure, the exposure control unit 160 moves the stage 141 at an appropriate speed and scrolls the pattern generated by the spatial light modulator 121 in synchronization with the movement of the stage 141 (i.e., changes the shape of the pattern generated by the spatial light modulator 121).

[0037] As exposure apparatus 100 having the above configuration, the exposure apparatus disclosed in U.S. Pat. No. 8,089,616, U.S. Patent Publication No. 2020 / 00257205, or WO 2005 / 081034 may be used.

[0038] Next, the control executed by the exposure control unit 160 according to this embodiment will be described in detail. In this embodiment, the exposure control unit 160 executes intensity control and emission timing control of the light beams L1 to L5. First, the intensity control will be described.

[0039] In this embodiment, the spatial light modulator 121 is illuminated with illumination light IL including a plurality of lights having different peak wavelengths, and the illumination light IL having a pattern imparted by the spatial light modulator 121 is projected onto the wafer W.

[0040] Here, because the light beams L1 to L5 contained in the illumination light IL have different peak wavelengths, axial chromatic aberration occurs, in which the imaging positions (foci) of the light beams L1 to L5 are shifted in the Z direction, due to the projection optical system 130, as shown in Fig. 4A. In this embodiment, in the traveling direction of the light beams L1 to L5, the imaging positions of the light beams L5, L4, L3, L2, and L1 are assumed to be farthest from the projection optical system 130 in the following order (the order of light beams L5 to L1). In other words, in the traveling direction of the light beams L1 to L5, the imaging position of the light beam L1 with wavelength λ1 is closest to the projection optical system 130, and the imaging position of the light beam L5 with wavelength λ5 is assumed to be farthest from the projection optical system 130. In other words, in the traveling direction (-Z direction) of light L1 to light L5, the imaging position of light L1 with wavelength λ1 is the position closest to the surface of resist 602 (photosensitive material layer) of wafer W (surface of wafer W), and the imaging position of light L5 with wavelength λ5 is the position farthest from the surface of resist 602.

[0041] As a result, the positions at which the pattern images SI1 to SI5 (hereinafter also referred to as the pattern images of the lights L1 to L5) generated by the spatial light modulator 121 by the lights L1 to L5 from the spatial light modulator 121 are formed are farthest from the surface of the resist 602 on the wafer W in the traveling direction of the lights L1 to L5 in the order of light L5, light L4, light L3, light L2, and light L1. Note that, when the chromatic aberration of magnification of the projection optical system 130 is ignored, the pattern images SI1 to SI5 of the lights L1 to L5 overlap in the direction intersecting with the optical axis AX, as shown in FIG.

[0042] 4B, the composite pattern image SIM obtained by combining the pattern images SI1 to SI5 of the five light beams L1 to L5 is an image in which the depth (length in the Z direction) is large relative to the width (length in the X direction). In this way, by using illumination light IL including multiple light beams L1 to L5 with different peak wavelengths, a pattern (groove) with a high aspect ratio can be formed in the resist 602 on the wafer W.

[0043] However, the inventors have discovered that when the light beams L1 to L5 are emitted with the same intensity, the intensity of the pattern image of the light beam weakens as the imaging position of the light beam is farther from the surface of the resist 602 due to the attenuation coefficient of the resist 602. This point will be explained in more detail.

[0044] The inventors simulated the intensity of a pattern image formed in a resist 502 applied to a substrate 501 shown in Fig. 5B by light L1 to L5 passing through the mask 503 when the mask 503 has the pattern shown in Fig. 5A and is illuminated with light L1 to L5 having the same intensity. As shown in Fig. 5A, the mask 503 has a square pattern with one side measuring 200 nm. In Fig. 5A, the shaded area indicates that the light transmittance is 0.

[0045] In the simulation, the numerical aperture (NA) was assumed to be 0.8. The refractive index of the substrate 501 was assumed to be 1.72, the attenuation coefficient was assumed to be 0.005, and the substrate 501 was assumed not to reflect the light L1 to L5. The thickness of the resist 502 was assumed to be 4 μm, the refractive index of the resist 502 was assumed to be 1.72, and the attenuation coefficient was assumed to be 0.005.

[0046] 6A to 6E are diagrams showing the results of simulating the intensity distribution of the pattern images of light L1 to light L5 in the resist 502 when light L1 to light L5 have the same intensity. Here, due to the axial chromatic aberration of the projection optical system 130, the focusing position of light Ln+1 is approximately 1,160 nm deeper than the focusing position of light Ln (n = 1 to 4). In FIGS. 6A to 6E, the intensity distribution of the pattern images of light L1 to light L5 in the resist 502 is represented by contour lines, and the numbers on the contour lines indicate intensities. Note that the higher the numerical value on the contour line, the higher the intensity.

[0047] As shown in FIGS. 6A to 6E, due to the influence of the attenuation coefficient of the resist 502, the farther the pattern image formation position is from the surface of the resist 502, the smaller its intensity becomes.

[0048] Therefore, in this embodiment, the intensities of the light beams L1 to L5 are made different when they enter the illumination optical system 112. More specifically, as shown in Fig. 7, the intensity is increased as the imaging position in the traveling direction of the light beams L1 to L5 is farther from the surface of the resist 602, that is, the farther the formation position of the pattern image of the light beams L1 to L5 is from the surface of the resist 602. In other words, the intensity of the light irradiated onto the wafer W is increased as the formation position of the pattern image of the light beams L1 to L5 is farther from the surface of the resist 602.

[0049] In this embodiment, in the traveling direction of light L1 to light L5, the formation positions of the pattern images of light L1 to light L5 are farther from the surface of the resist in the order of light L5 to light L1. Therefore, if the intensity of light L1 is In1, the intensity of light L2 is In2, the intensity of light L3 is In3, the intensity of light L4 is In4, and the intensity of light L5 is In5, then In1<In2<In3<In4<In5. As a result, the intensities of light L1 to light L5 irradiated onto wafer W increase in the order of light L5 to light L1.

[0050] The intensities In1 to In5 of the light L1 to L5 can be adjusted, for example, by controlling the first to fifth solid-state laser light sources SLS1 to SLS5 by the exposure control unit 160. Note that the intensities In1 to In5 of the light L1 to L5 may also be adjusted, for example, by setting the first to fifth solid-state laser light sources SLS1 to SLS5.

[0051] The intensities In1 to In5 of the light L1 to L5 may be adjusted using a neutral density filter in addition to controlling or setting the first to fifth solid-state laser light sources SLS1 to SLS5. Alternatively, the intensities of the light L1 to L5 emitted from the first to fifth solid-state laser light sources SLS1 to SLS5 may be made the same, and the intensities In1 to In5 when incident on the illumination optical system 112 (intensities when irradiated onto the wafer W) may be set to In1<In2<In3<In4<In5 by a neutral density filter.

[0052] FIG. 8 shows the results of a simulation of the intensity distribution of a composite pattern image formed in the resist 502 when the mask 503 is illuminated with illumination light IL in which the intensities of the lights L1 to L5 shown in FIGS. 6A to 6E have been adjusted. The intensity Isum of the composite pattern image was calculated using the following equation: Isum = ΣIni·I(λi). Here, Ini (i = 1 to 5) is a weighting coefficient, and I(λi) is the intensity of light Li (i = 1 to 5) when emitted from the fixed laser light source. Therefore, Ini·I(λi) is the intensity of light Li when illuminating the mask 503 (or the intensity of light Li when irradiating the resist 502). In the simulation of FIG. 8, In1 = 0.077, In2 = 0.116, In3 = 0.164, In4 = 0.232, and In5 = 0.411.

[0053] As shown in FIG. 8, by setting In1<In2<In3<In4<In5, it can be seen that a composite pattern image with uniform intensity in the depth direction of the resist 502 is formed.

[0054] The interval Δλ between the wavelengths of the light L1 to L5 is determined so that the NILS (Normalized Image Log Slope) in the X and Y directions of the composite pattern image obtained by combining the pattern images of each of the multiple lights is high, the unevenness in the Z direction of the intensity of the composite pattern image is small (high uniformity), and the number of wavelengths used is small. If the difference between the focal position of the light of wavelength λ and the focal position of the light of wavelength λ + Δλ is ΔFocus, then ΔFocus = k ２ λ / NA ２ =Cz・Δλ ∴Δλ=k ２ λ / Cz NA ２ and the wavelength interval Δλ is k ２ Here, Cz represents the axial chromatic aberration, NA represents the numerical aperture, and λ represents a representative (specific) wavelength (for example, 248 nm) within a range including the wavelengths λ1 to λ5 of the light beams L1 to L5.

[0055] Optimal k ２ 9A to 11B show the results of simulations to obtain the k ２10A and 10B show the results of simulating NILS, uniformity, and number of wavelengths in a 3D image sensor.

[0056] As described above, it is preferable that the NILS of the composite pattern image in the X and Y directions is high, the intensity of the composite pattern image has small unevenness in the Z direction (high uniformity), and the number of wavelengths used is small. Therefore, as shown in FIG. 9A, when the numerical aperture NA is 0.4, k ２ As shown in FIG. 9B, when the numerical aperture NA is 0.6, k ２ As shown in FIG. 10A, when the numerical aperture NA is 0.6, k ２ As shown in FIG. 10B, when the numerical aperture NA is 0.7, k ２ As shown in FIG. 11A, when the numerical aperture NA is 0.8, k ２ It is thought that 1.2 is optimal.

[0057] Thus, when the numerical aperture NA is less than 1, k ２ It is preferable to set the wavelength interval to Δλ that satisfies =1.2 to 1.6.

[0058] Furthermore, as shown in FIG. 11B, when the numerical aperture NA is 1.35, k ２ It is thought that the ratio can be reduced to about 2.

[0059] Next, emission timing control of the lights L1 to L5 will be described.

[0060] In this embodiment, the projection optical system 130 is an off-axis optical system that is one-sided telecentric (non-telecentric on the spatial light modulator 121 side) due to the optical path separation at the reflective spatial light modulator 121. In the exposure area of ​​this off-axis optical system, the center of the exposure area of ​​each light is located at a position offset from the optical axis AX (center of the lens) of the projection optical system 130 in the X direction (scanning direction), as shown in Fig. 12. In other words, the pattern images formed by each of the light beams L1 to L5 are formed at positions offset from the optical axis AX of the projection optical system 130. This causes an offset in the chromatic aberration of magnification in the X direction.

[0061] Fig. 13A shows the distribution of chromatic aberration of magnification in the projection optical system 130, and Fig. 13B shows the distribution of chromatic aberration of magnification after scan averaging when scanning in the +X direction. In Fig. 13A and Fig. 13B, the arrows indicate vectors representing the chromatic aberration of magnification. The vector representing the chromatic aberration of magnification can be expressed as (a × x + b, a × y). Here, a is a coefficient, b is an offset, x is the position in the X direction, and y is the position in the Y direction.

[0062] As shown in Fig. 13A, the chromatic aberration of magnification increases as the position becomes farther from the optical axis AX. Here, for example, at y = 0, the chromatic aberration of magnification in the Y direction is canceled out and becomes zero due to the scan averaging effect, but in the X direction, an offset (b) of the chromatic aberration of magnification remains, as shown in Fig. 13B.

[0063] 14(A) and 14(B) are diagrams showing the results of simulating the intensity distribution of a composite pattern image formed in the resist 502 after scan averaging, where FIG. 14(A) shows the intensity distribution in a plane perpendicular to the X-axis at y=0, and FIG. 14(B) shows the intensity distribution in a plane perpendicular to the Y-axis.

[0064] As shown in Fig. 14A, due to the scan averaging effect, there is no influence of chromatic aberration of magnification in a plane perpendicular to the X axis, but as shown in Fig. 14B, there is an influence of chromatic aberration of magnification in a plane perpendicular to the Y axis, causing the composite pattern image to tilt. More specifically, the farther the position of the pattern images of light L1 to light L5 is from resist 602 in the traveling direction of light L1 to light L5, the more the pattern image is formed at a position deviated from optical axis AX in the X direction. As a result, the pattern formed in resist 502 by scanning exposure has an inclined inner wall (cross section).

[0065] Therefore, in this embodiment, the timings at which the light beams L1 to L5 are emitted are made different from one another. More specifically, the farther the position of the pattern image formed by each of the light beams L1 to L5 is from the surface of the resist 602 in the traveling direction of the light beams L1 to L5, the later the emission timing is made.

[0066] FIG. 15 is a diagram illustrating the emission timing of light L1 to light L5. In this embodiment, since the pattern image formation position is farthest from the surface of the resist 602 in the order of light L5 to light L1, the exposure control unit 160 controls the emission timing of light L1 to light L5 from the first solid-state laser light source SLS1 to fifth solid-state laser light source SLS5 so that the emission timing of light L5 is the latest and the emission timing of light L1 is the earliest. As a result, the light whose pattern image formation position is farthest from the surface of the resist 602 is irradiated with light L1 is delayed. In other words, the timing at which light L1 irradiates the resist 602 is the earliest, and the timing at which light L5 irradiates the resist 602 is the latest. By adjusting (changing) the timing at which light L1 to light L5 irradiate the resist 602 of the wafer W in accordance with the scanning direction and scanning speed of the wafer W, it is possible to form pattern images of light L1 to light L5 at approximately the same position in the scanning direction (+X direction). For example, if the formation position of the pattern image of light L1 and the formation position of the pattern image of light L2 differ by ΔX in the scanning direction (+X direction), by irradiating light L1 onto the resist 602 and then irradiating light L2 onto the resist 602 at the timing when the wafer W moves ΔX by scanning, the formation position of the pattern image of light L1 and the formation position of the pattern image of light L2 can be made to approximately coincide on the wafer W in the scanning direction (+X direction). Note that if the scanning direction of the wafer W is the −X direction, the timing of irradiating light onto the resist 602 with light whose formation position of the pattern image is farther from the surface of the resist 602 can be made earlier. For example, as disclosed in the above-mentioned U.S. Pat. No. 8,089,616, when scanning exposure is performed by raster scanning while switching the scanning direction in reverse, the timing of instructions (trigger signals) to multiple solid-state laser light sources SLS1 to SLS5 emitting light of different wavelengths may be changed depending on the scanning direction.

[0067] FIG. 16 is a diagram showing the results of simulating the intensity of a composite pattern image after scan averaging in a cross section perpendicular to the Y axis, obtained by shifting the emission timings of the light L1 to light L5 as shown in FIG.

[0068] As shown in FIG. 16, the farther the position of the pattern image formed by each light L1 to L5 is from the surface of the resist 602, the later the emission timing (irradiation timing of the resist 602) is made, thereby making it possible to correct the offset of the chromatic aberration of magnification and suppress the tilt of the composite pattern image in the X direction (scanning direction).

[0069] As described above in detail, according to this embodiment, the exposure apparatus 100 includes an illumination optical system 112 that illuminates the spatial light modulator 121 with illumination light IL including light L1 to light L5 having different wavelengths λ1 to λ5, and a projection optical system 130 that projects an image of a pattern generated by the spatial light modulator 121 with the illumination light IL from the spatial light modulator 121 onto the wafer W. The projection optical system 130 forms images of the pattern generated by the spatial light modulator 121 with the illumination light L1 to illumination light L5 from the spatial light modulator 121, respectively, and forms the pattern images of the illumination light L1 to illumination light L5 at positions farther from the surface of the wafer W in the order of illumination light L1 to illumination light L5 in the traveling direction of the illumination light L1 to illumination light L5. Furthermore, the intensities of the illumination light L1 to illumination light L5 irradiated onto the wafer W increase in the order of illumination light L5 to illumination light L1.

[0070] The positions where the pattern images of the illumination lights L1 to L5 are formed are located farther from the surface of the wafer W in the direction of travel of the illumination lights L1 to L5, in the order of illumination lights L1 to L5. By combining the pattern images of the illumination lights L1 to L5, a composite pattern image that is long in the depth direction of the resist 602 can be formed. Furthermore, since the intensities of the illumination lights L1 to L5 irradiated onto the wafer W increase in the order of illumination lights L5 to L1, this solves the problem of the intensity decreasing the farther the position where the pattern image is formed is from the surface of the wafer W due to the attenuation intensity of the resist 602, and makes it possible to form a composite pattern image with uniform intensity in the depth direction of the resist 602. This makes it possible to form a pattern (groove) in the resist 602 that has a constant width in the depth direction and a high aspect ratio.

[0071] 17A to 17C are diagrams showing simulation results of the intensities of composite pattern images formed in the resist 502 by the methods according to Comparative Examples 1 to 3, and Fig. 17D is a diagram showing simulation results of the intensities of composite pattern images formed in the resist 502 by the method according to this embodiment.

[0072] More specifically, FIG. 17A shows a simulation result of the intensity of a composite pattern image formed in the resist 502 when the mask 503 is illuminated with one light beam having a predetermined peak wavelength and the wafer W is continuously moved by about 2.3 μm in the depth direction during exposure (Comparative Example 1). FIG. 17B shows a simulation result of the intensity of a composite pattern image formed in the resist 502 when the mask 503 is illuminated with two light beams having different peak wavelengths (Comparative Example 2). Note that the two light beams illuminate the mask 503 with the same intensity. FIG. 17C shows a simulation result of the intensity of a composite pattern image formed in the resist 502 when the mask 503 is illuminated with five light beams having different peak wavelengths (Comparative Example 3). Note that the five light beams illuminate the mask 503 with the same intensity. FIG. 17D shows a simulation result of the intensity of a composite pattern image formed in the resist 502 when the mask 503 is illuminated with five light beams having different peak wavelengths using the intensity control according to this embodiment.

[0073] 17A to 17D, the intensity control according to this embodiment enables the formation of a composite pattern image having a uniform intensity distribution in the depth direction. The uniformity of the intensity in the depth direction (1σ) was 38.8% in Comparative Example 1 (FIG. 17A), 50.5% in Comparative Example 2 (FIG. 17B), 23.7% in Comparative Example 3 (FIG. 17C), and 1.2% in this embodiment (FIG. 17D).

[0074] In addition, in this embodiment, the exposure apparatus 100 is equipped with an exposure control unit 160 that controls the light source unit 111 that supplies illumination light IL to the illumination optical system 112, and the exposure control unit 160 controls the timing at which illumination light L1 to L5 is irradiated onto the wafer W to be delayed in the order of illumination light L5 to illumination light L1.

[0075] Due to an offset of the chromatic aberration of magnification of the projection optical system 130, the positions at which the pattern images of the illumination lights L1 to L5 are formed become farther from the optical axis AX of the projection optical system 130 in the scanning direction (X direction) in the order of illumination light L5 to illumination light L1. Therefore, by delaying the timing at which the illumination lights L1 to L5 are irradiated onto the wafer W in the order of illumination light L5 to illumination light L1, the wafer W is scanned, and the pattern images of the illumination lights L1 to L5 can be formed at approximately the same positions in the scanning direction, and a pattern with a high aspect ratio that is approximately parallel to the depth direction of the resist 602 can be formed.

[0076] In the above embodiment, five light beams L1 to L5 having different wavelengths are used as the illumination light IL, but this is not limited thereto. The number of light beams contained in the illumination light IL may be two or more. For example, in the case of illumination light IL including light beam L1 having a wavelength λ1 and light beam L2 having a wavelength λ2 different from the wavelength λ1, the projection optical system 130 forms an image of the pattern generated by the spatial light modulator 121 using the illumination light L1 from the spatial light modulator 121, and forms an image of the pattern generated by the spatial light modulator 121 using the illumination light L2 from the spatial light modulator 121 at a position farther from the surface of the wafer W in the direction of travel of the illumination light L2 than the image of the pattern generated by the illumination light L1. In this case, the intensity of the illumination light L2 irradiated onto the wafer W may be set higher than the intensity of the illumination light L1 irradiated onto the wafer W. Furthermore, the exposure control unit 160 may perform control so that the timing at which the illumination light L2 is irradiated onto the wafer W is delayed relative to the timing at which the illumination light L1 is irradiated onto the wafer W.

[0077] The number of light beams contained in the illumination light IL may be determined based on the characteristics (attenuation coefficient, thickness) of the resist 602 on the wafer W, the aspect ratio of the pattern to be formed on the resist 602, and the like. While the above embodiment uses a projection optical system 130 in which chromatic aberration correction is performed such that the image formation position moves farther from the projection optical system 130 as the wavelength increases, the chromatic aberration correction state of the projection optical system may be such that the image formation position moves farther from the projection optical system 130 as the wavelength decreases, or such that the image formation position moves farther from or closer to the projection optical system 130 as the wavelength deviates from a specific wavelength (e.g., wavelength λ3). Similarly, the above embodiment uses a projection optical system 130 in which chromatic aberration correction is performed such that the magnification increases as the wavelength increases, or such that the magnification increases or decreases as the wavelength deviates from a specific wavelength (e.g., wavelength λ3).

[0078] Furthermore, in the above embodiment, the exposure control unit 160 executes both intensity control and emission timing control, but it may execute only one of these controls.

[0079] Furthermore, in the above embodiment, the emission timing control of the lights L1 to L5 was described using the example of the projection optical system 130 being one-sided telecentric, but emission timing control is applicable not only to the case where the projection optical system 130 is one-sided telecentric, but also to any case where an offset remains in the chromatic aberration of magnification after scan averaging.

[0080] Furthermore, in the above embodiment, the case where exposure apparatus 100 uses an SLM has been described, but exposure apparatus 100 may also use a reticle (photomask). In this case, exposure apparatus 100 exposes a pattern formed on the reticle onto a resist (photosensitive material layer) on wafer W.

[0081] In the above embodiment, a composite pattern image having a uniform intensity distribution in the depth direction is formed, but a uniform intensity distribution may not always be ideal. In such cases, a required combination of wavelengths and intensities may be selected to obtain an ideal intensity distribution.

[0082] Furthermore, in the above embodiment, attention is focused on the combined intensity distribution, but the necessary combination of wavelengths and intensities may be selected so that the cross section of the resist 602 after development has a desired shape.

[0083] In the above embodiment, it is preferable that the wavelength intervals of the light beams L1 to L5 are equal, but they do not have to be equal. Also, in the above embodiment, it is preferable that the emission timings of the light beams L1 to L5 are equal when the wavelength intervals of the light beams L1 to L5 are equal, but they do not have to be equal. Also, when the wavelength intervals of the light beams L1 to L5 are not equal, the emission timings of the light beams L1 to L5 do not have to be equal.

[0084] The above-described embodiment is a preferred example of the present invention, but the present invention is not limited to this and can be modified in various ways without departing from the spirit of the present invention.

[0085] 100 Exposure apparatus 111 Light source unit 112 Illumination optical system 121 Spatial light modulator 130 Projection optical system AX Optical axis L1 to L5 Light IL Illumination light W Wafer 602 Resist

Claims

1. illuminating a first object with exposure light including first exposure light having a first peak wavelength and second exposure light having a second peak wavelength different from the first peak wavelength; exposing a second object to the exposure light from the first object; Including, a ratio between an intensity of the second exposure light irradiated onto the second object and an intensity of the first exposure light irradiated onto the second object is changeable, and the intensity of the second exposure light irradiated onto the second object is set to be higher than the intensity of the first exposure light irradiated onto the second object; Exposure method.

2. The exposing step includes positioning the focal position of the second exposure light farther from the incident surface on which the exposure light is incident on the second object than the focal position of the first exposure light in the direction of travel of the second exposure light. The exposure method according to claim 1 .

3. the exposing step includes projecting the exposure light from the first object onto the second object by a projection optical system; 3. The exposure method according to claim 1.

4. a second image formed on the second object by the first exposure light from the first object overlaps with a first image formed on the second object by the second exposure light from the first object in a direction intersecting with the optical axis of the projection optical system; The exposure method according to claim 3 .

5. the exposure light includes exposure light having a plurality of peak wavelengths including the first peak wavelength and the second peak wavelength, The difference Δλ between adjacent peak wavelengths in the exposure light of the plurality of peak wavelengths is k ２ is a coefficient, NA is a numerical aperture, Cz is an axial chromatic aberration, and λ is a specific peak wavelength within a range including the plurality of peak wavelengths, Δλ=κ ２ ×λ / (Cz×NA ２ ) and k ２ = 1.3 to 1.6, 3. The exposure method according to claim 1.

6. 6. The exposure method according to claim 5, wherein the intervals between the peak wavelengths of the exposure light among the plurality of peak wavelengths are equal.

7. the timing at which the second object is irradiated with the second exposure light is different from the timing at which the second object is irradiated with the first exposure light; 3. The exposure method according to claim 1.

8. illuminating a first object with exposure light including first exposure light having a first peak wavelength and second exposure light having a second peak wavelength different from the first peak wavelength; exposing the exposure light from the first object to a second object moving along a scanning direction; Including, the timing at which the second object is irradiated with the second exposure light is different from the timing at which the second object is irradiated with the first exposure light; Exposure method.

9. The exposing step includes positioning the focal position of the second exposure light farther from the incident surface on which the exposure light is incident on the second object than the focal position of the first exposure light in the direction of travel of the second exposure light. The exposure method according to claim 8.

10. the exposing step includes projecting the exposure light from the first object onto the second object by a projection optical system; 10. The exposure method according to claim 8 or claim 9.

11. the projection optical system is a non-telecentric optical system on the first object side; The exposure method according to claim 10.

12. a central image of the exposure area of ​​the first exposure light and a center of the exposure area of ​​the second exposure light are each located at a position deviated from the optical axis of the projection optical system; The exposure method according to claim 10.

13. the first object is a mask on which a pattern is formed or a spatial light modulator that generated the pattern; 10. The exposure method according to claim 1, 2, 8, or 9.

14. The intensity of the first exposure light is adjusted by controlling a first light source; the intensity of the second exposure light is adjusted by controlling a second light source different from the first light source. The exposure method according to any one of claims 1 to 9.

15. The second peak wavelength is longer than the first peak wavelength. The exposure method according to any one of claims 1 to 9.

16. The second object includes a photosensitive material layer having an incident surface; the intensity of the first exposure light and the intensity of the second exposure light are set based on the characteristics of the photosensitive material layer. The exposure method according to any one of claims 1 to 9.

17. The method of claim 16, wherein the characteristics include a thickness of the photosensitive material layer. The exposure method according to claim 16.

18. an illumination optical system that illuminates a first object with exposure light including first exposure light having a first peak wavelength and second exposure light having a second peak wavelength different from the first peak wavelength; a projection optical system that projects the exposure light from the first object onto a second object; Including, a ratio between an intensity of the second exposure light irradiated onto the second object and an intensity of the first exposure light irradiated onto the second object is changeable, and the intensity of the second exposure light irradiated onto the second object is set to be higher than the intensity of the first exposure light irradiated onto the second object; Exposure equipment.

19. The position of the focal point of the second exposure light is located farther from the incident surface onto which the exposure light is incident in the second object than the position of the focal point of the first exposure light in the traveling direction of the second exposure light.

19. The exposure apparatus according to claim 18.

20. a control device that controls a light source that supplies the exposure light to the illumination optical system to make the intensity of the second exposure light irradiated onto the second object higher than the intensity of the first exposure light irradiated onto the second object, 19. The exposure apparatus according to claim 18.

21. An exposure apparatus that scans and exposes a pattern of a first object onto a second object, an illumination optical system that illuminates a first object with exposure light including first exposure light having a first peak wavelength and second exposure light having a second peak wavelength different from the first peak wavelength; a projection optical system that projects the exposure light from the first object onto a second object that moves along a scanning direction; a control device that controls a light source that supplies the exposure light to the illumination optical system; Equipped with the control device performs control to make the timing at which the second object is irradiated with the second exposure light different from the timing at which the second object is irradiated with the first exposure light. Exposure equipment.

22. The position of the focal point of the second exposure light is located farther from the incident surface onto which the exposure light is incident in the second object than the position of the focal point of the first exposure light in the traveling direction of the second exposure light.

22. The exposure apparatus according to claim 21.

23. The light source includes a first light source that adjusts the intensity of the first exposure light, and a second light source different from the first light source that adjusts the intensity of the second exposure light.

22. The exposure apparatus according to claim 20 or 21.

24. Exposing a photosensitive material layer of the second object using an exposure method according to any one of claims 1, 2, 8, and 9; processing an area inside the photosensitive material layer of the second object using a pattern generated by developing the exposed photosensitive material layer as a mask; A device manufacturing method comprising:

25. The method of claim 24, wherein the first object is a mask on which a pattern is formed, or a spatial light modulator that generates the pattern.

23. The exposure apparatus according to any one of claims 18 to 22.

26. The second peak wavelength is longer than the first peak wavelength.

23. The exposure apparatus according to any one of claims 18 to 22.

27. The second object includes a photosensitive material layer having an incident surface; the intensity of the first exposure light and the intensity of the second exposure light are set based on the characteristics of the photosensitive material layer.

23. The exposure apparatus according to any one of claims 18 to 22.

28. The method of claim 27, wherein the characteristics include a thickness of the photosensitive material layer.

28. The exposure apparatus according to claim 27.