Exposure method, exposure apparatus, and device manufacturing method

Abstract

The exposure method includes: illuminating a first object with exposure light rays including a first exposure light ray having a first wavelength and a second exposure light ray having a second wavelength different from the first wavelength; and exposing an image of the pattern of the first object to a second object by the exposure light from the first object, the exposure including: 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 at a position farther from the surface of the second object than the first image in the traveling direction of the second exposure light by using the second exposure light from the first object, the intensity of the second exposure light beam irradiated to the second object is higher than the intensity of the first exposure light beam irradiated to the second object.

Description

Technical Field

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

[0002] In the photolithography process for manufacturing micro devices (electronic devices, etc.) such as semiconductor elements and liquid crystal display elements, a pattern with a depth greater than its width (high aspect ratio), so-called grooves (for example, Patent Document 1), is sometimes exposed on a photosensitive material layer on a substrate (a glass plate or a semiconductor wafer, etc.).

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: U.S. Patent Application Publication No. 2019 / 0204756 Summary of the Invention

[0006] The first disclosed aspect provides an exposure method, which includes: illuminating a first object using exposure light including a first exposure light of a first wavelength and a 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 using the exposure light from the first object, the exposure including: 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 at a position farther away from the surface of the second object than the first image in the direction of travel of the second exposure light using the second exposure light from the first object, the intensity of the second exposure light irradiated to the second object being higher than the intensity of the first exposure light irradiated to the second object.

[0007] The second disclosed aspect provides an exposure method, which includes: illuminating a first object using exposure light including a first exposure light of a first wavelength and a second exposure light of a second wavelength different from the first wavelength; and exposing a second object moving along a scanning direction using the exposure light from the first object, the exposure including: forming a first image of a 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 at a position farther away from the surface of the second object than the first image in the direction of travel of the second exposure light using the second exposure light from the first object, the timing at which the second exposure light is irradiated to the second object being different from the timing at which the first exposure light is irradiated to the second object.

[0008] The third disclosed aspect provides an exposure device, comprising: an illumination optical system, which utilizes exposure light including a first exposure light of a first wavelength and a second exposure light of a second wavelength different from the first wavelength to illuminate a first object; and a projection optical system, which utilizes the exposure light from the first object to project an image of a pattern of the first object onto a second object, the projection optical system utilizing the first exposure light from the first object to form a first image of the pattern of the first object, and utilizing the second exposure light from the first object to form a second image of the pattern of the first object at a position farther away from the surface of the second object than the first image in the direction of travel of the second exposure light, the intensity of the second exposure light irradiated to the second object being higher than the intensity of the first exposure light irradiated to the second object.

[0009] The fourth disclosed aspect provides an exposure device that scans and exposes a pattern of a first object onto a second object, the exposure device comprising: an illumination optical system that illuminates the first object using exposure light including a first exposure light of a first wavelength and a 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, the projection optical system using the first exposure light from the first object to form a first image of the pattern of the first object, and using the second exposure light from the first object to form a second image of the pattern of the first object at a position farther away from the surface of the second object than the first image in the direction of travel of the second exposure light, the control device controlling so that the timing of irradiating the second exposure light to the second object is different from the timing of irradiating the first exposure light to the second object.

[0010] The fifth disclosed aspect provides a device manufacturing method, which includes: exposing the photosensitive material layer of the second object using the above-mentioned exposure method; and processing the inner side of the second object compared to the photosensitive material layer using a pattern produced by developing the exposed photosensitive material layer as a mask.

[0011] It should be noted that the configuration of the embodiments described below can be appropriately improved, and at least a portion can be replaced by other components. In addition, the components that are not particularly limited in their configuration are not limited to the configuration disclosed in the embodiments and can be configured in a position that can achieve their functions. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1It is a diagram showing a schematic configuration of an exposure apparatus according to an embodiment.

[0013] Figure 2 (A) is a diagram showing a schematic configuration of a light source unit. Figure 2 (B) is a diagram illustrating the wavelength of light emitted from each solid-state laser light source.

[0014] Figure 3 This is a diagram showing an example of a spatial light modulator.

[0015] Figure 4 A diagram illustrating axial chromatic aberration.

[0016] Figure 5 (A) is a schematic diagram showing a mask used in the simulation. Figure 5 (B) is a schematic diagram showing a substrate and a resist used in the simulation.

[0017] Figure 6 (A) to Figure 6 (E) is a diagram showing the result of simulating the intensity distribution of the pattern image formed in the resist when the resist is irradiated with the light L1 to the light L5 at the same intensity.

[0018] Figure 7 Graph showing the relationship between the wavelength and intensity of light in the embodiment.

[0019] Figure 8 1 and 2 are diagrams showing the results of simulations of the intensity distribution of a pattern image formed in a resist when the mask is illuminated by illumination light having respective intensities adjusted for the light beams L1 to L5.

[0020] Figure 9 (A) and Figure 9 (B) is a diagram showing the results of simulations of NILS, uniformity, and the number of wavelengths at each k2 for cases where the numerical aperture NA is 0.4 and 0.5.

[0021] Figure 10 (A) and Figure 10 (B) is a diagram showing the results of simulations of NILS, uniformity, and the number of wavelengths at each k2 for cases where the numerical aperture NA is 0.6 and 0.7.

[0022] Figure 11 (A) is a diagram showing the results of simulation of NILS, uniformity, and the number of wavelengths at each k2 when the numerical aperture NA is 0.8. Figure 11 (B) is a diagram showing the results of simulation of NILS and uniformity at each k2 when the numerical aperture NA is 1.35.

[0023] Figure 12A diagram for explaining chromatic aberration of magnification.

[0024] Figure 13 (A) is a diagram showing the distribution of chromatic aberration of magnification of the projection optical system. Figure 13 (B) is a diagram showing the distribution of chromatic aberration of magnification after scanning averaging.

[0025] Figure 14 (A) and Figure 14 (B) is a diagram showing the result of simulating the intensity distribution of the composite pattern image after scanning and averaging. Figure 14 (A) is the intensity distribution on the surface perpendicular to the Y axis, Figure 14 (B) is the intensity distribution on the plane perpendicular to the X-axis.

[0026] Figure 15 This is a diagram illustrating the emission timing of the light L1 to the light L5.

[0027] Figure 16 It shows that Figure 15 Graphs showing simulation results of the intensity of a composite pattern image on a cross section perpendicular to the X-axis, obtained by shifting the emission timing of the light beams L1 to L5 .

[0028] Figure 17 (A) to Figure 17 (C) is a diagram showing simulation results of simulating the strength of the synthetic pattern image formed in the resist by the methods of Comparative Examples 1 to 3. Figure 17 (D) is a diagram showing simulation results of the intensity of a synthetic pattern image formed in a resist by the method of this embodiment. DETAILED DESCRIPTION

[0029] It is desirable to form a photosensitive material layer on a substrate (glass plate, semiconductor wafer, etc.) with a high aspect ratio pattern having a certain width in the depth direction and a small inclination of the inner wall.

[0030] The following is based on Figures 1 to 16 Exposure apparatus 100 according to this embodiment will be described.

[0031] Figure 1 1 is a diagram showing a schematic configuration of an exposure device 100 according to this embodiment. The exposure device 100 uses a spatial light modulator (SLM) that modulates illumination light (exposure light) under the control of an exposure control unit 160 described later.

[0032] like Figure 1As shown, the 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 control unit 160. In the description of the exposure apparatus 100, two directions orthogonal to each other in the horizontal plane are referred to as the X and Y directions, and the direction orthogonal to the X and Y directions is referred to as the Z direction. Furthermore, the rotation (tilt) directions about the X, Y, and Z axes are referred to as the θx, θy, and θz directions, respectively. It should be noted that in this embodiment, the X direction is the scanning direction.

[0033] The illumination system 110 includes a light source unit 111 , an illumination optical system 112 , and a reflecting mirror 113 .

[0034] Figure 2 (A) is a diagram showing a schematic structure 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 solid-state laser light source SLS1-SLS5 may be, for example, a solid-state laser device that amplifies laser light emitted from a laser light source such as a DFB semiconductor laser using an optical fiber amplifier and converts the wavelength of the amplified laser light through a wavelength conversion element. For example, such solid-state laser devices are disclosed in U.S. Patents Nos. 7,339,661, 7,974,320, 9,153,934, and 9,160,132.

[0035] The first solid-state laser light source SLS1 emits illumination light (exposure light) L1 having a peak wavelength λ1 for illuminating a spatial light modulator 121 described later. The second solid-state laser light source SLS2 emits illumination light (exposure light) L2 having a peak wavelength λ2 for illuminating the spatial light modulator 121. The third solid-state laser light source SLS3 emits illumination light (exposure light) L3 having a peak wavelength λ3 for illuminating the spatial light modulator 121. The fourth solid-state laser light source SLS4 emits illumination light (exposure light) L4 having a peak wavelength λ4 for illuminating the spatial light modulator 121. The fifth solid-state laser light source SLS5 emits illumination light (exposure light) L5 having a peak wavelength λ5 for illuminating the spatial light modulator 121. It should be noted that, in the following description, illumination light L1 to illumination light L5 are referred to as light L1 to light L5.

[0036] Figure 2 (B) is a diagram showing peak wavelengths λ1-λ5 of the light L1 to the light L5 emitted from the first solid laser light source SLS1 to the fifth solid laser light source SLS5, respectively. Figure 2As shown in (B), the peak wavelengths λ1-λ5 are discrete. In this embodiment, λ1<λ2<λ3<λ4<λ5. It should be noted that Figure 2 In (B), for convenience, the intensities of light L1 to light L5 are expressed as the same, and the intensities of light L1 to light L5 will be described later. Figure 2 In (B), the intervals between adjacent peak wavelengths are fixed, but the present invention is not limited to this. The intervals between adjacent peak wavelengths may be irregular.

[0037] The first to fifth solid-state laser light sources SLS1 to SLS5 change the intensity and timing of emitted light based on an instruction from the exposure control unit 160. The instruction from the exposure control unit 160 may also be referred to as a trigger signal.

[0038] 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, which includes the light beams L1 to L5 emitted from the light source unit 111. Because the illumination light IL includes the light beams L1 to L5, it can be said to have multiple peak wavelengths or a discrete wavelength distribution.

[0039] The pattern generator 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. It should be noted that in this embodiment, the wafer W includes a substrate 601 and a resist 602 (a photosensitive material layer) applied to the substrate 601.

[0040] The pattern generating device 120 includes a spatial light modulator 121 and a driving unit 122 .

[0041] Figure 3 1 is a diagram showing an example of the spatial light modulator 121. Figure 3 As shown, the spatial light modulator 121 includes a plurality of micro-mirror mechanisms M arranged in a matrix (two-dimensional, array) within the XY plane. Each micro-mirror mechanism M includes a micro-mirror M1 and a drive mechanism M2 disposed on the opposite side of the reflective surface of the micro-mirror M1. The drive mechanism M2 moves the micro-mirror M1 along an axis extending in the Z direction (up and down).

[0042] The driving unit 122 drives the driving mechanism M2 of each of the plurality of micromirror mechanisms M according to the control signal from the exposure control unit 160 , thereby switching the micromirror M1 between an open state (open position) and a closed state (closed position).

[0043] Here, because the size of each micromirror M1 is so small that it cannot be resolved by the projection optical system 130, when all micromirrors M1 are in the on or off state within a region of a size that can be resolved by the projection optical system 130, the 0th-order diffracted light IL0 of the illumination light IL from the illumination system 110 incident on that region enters the projection optical system 130. For example, 2×2 micromirrors M1 may be positioned within a region of a size 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 a region where micromirrors M1 in the on state and micromirrors M1 in the off state are alternately arranged, the illumination light IL is diffracted in that region, and the 0th-order diffracted light IL0 of the illumination light IL is almost eliminated. The diffracted light IL1 of the ±1st order or higher of the illumination light IL enters a non-exposure optical path that deviates from the projection optical system 130. The pattern generating device 120 imparts a pattern to the illumination light IL by setting the plurality of micromirrors M1 to either the on or off state. It should be noted that in the following description, a surface on which a plurality of micromirrors M1 set to either the open state or the closed state are arranged may be referred to as a light modulation surface of the spatial light modulator 121 .

[0044] It should be noted that the spatial light modulator 121 is not limited to the piston type described above; for example, it may also be a magneto-optical spatial light modulator (MOSLM) or a digital micromirror device (DMD). Furthermore, while the spatial light modulator 121 is described as a reflective type that reflects the illumination light IL, the spatial light modulator 121 may also be a transmissive type that transmits the illumination light IL or a diffraction type that diffracts the illumination light IL. The spatial light modulator 121 only needs to be able to modulate the illumination light IL both spatially and temporally.

[0045] The projection optical system 130 projects the image of the light modulation surface of the spatial light modulator 121 at a reduced projection magnification β (for example, β = 1 / 200, 1 / 400, 1 / 500, etc.) onto the wafer W placed on the stage 141. Specifically, the energy beam passing through the pattern generator 120 forms an exposure pattern on the wafer W. The projection optical system 130 includes a lens barrel 130s and various optical elements (not shown) arranged in a predetermined positional relationship within the lens barrel 130s.

[0046] The stage device 140 includes a stage (substrate stage) 141 , a laser interferometer 142 , and a stage driving section 143 .

[0047] The stage 141 holds a 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 rotatable about an axis extending in the Z direction.

[0048] The laser interferometer 142 irradiates the length measuring beam onto the reflective surfaces of the end faces of the stage 141 in the X and Y directions, thereby being able to always detect the position of the stage 141 in the X, Y, and θz directions with a resolution of, for example, about 0.5-1 nm.

[0049] The stage driving section 143 drives the stage 141 according to a control signal from the exposure control section 160 .

[0050] The alignment detection system 150 is disposed on the side of the projection optical system 130. In this embodiment, an imaging alignment sensor is used as the alignment detection system 150. For example, the detailed configuration of the alignment detection system 150 is disclosed in US Pat. No. 5,637,129.

[0051] The alignment detection system 150 detects dicing streets or position detection marks formed on the wafer W. The detection results of the dicing streets and position detection marks by the alignment detection system 150 are output to the exposure control unit 160 .

[0052] The exposure control unit 160 controls the actions of the lighting system 110, the pattern generating device 120, the stage device 140, etc. to form a predetermined exposure pattern on the wafer W, and projects the image of the light modulation surface of the spatial light modulator 121 onto the wafer W held by the stage 141 via the projection optical system 130.

[0053] When the spatial light modulator 121 is illuminated by the illumination light IL from the illumination system 110, the illumination light IL reflected by the micro-mirror M1 of the spatial light modulator 121, that is, the illumination light IL given a pattern by the spatial light modulator 121, is incident on 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 by the stage 141.

[0054] In this embodiment, the exposure control unit 160 performs exposure using a step-and-scan method. Furthermore, during scanning exposure, the exposure control unit 160 moves the stage 141 at an appropriate speed and, in synchronization with the movement, scrolls the pattern generated by the spatial light modulator 121 (i.e., changes the shape of the pattern generated by the spatial light modulator 121).

[0055] As the exposure apparatus 100 having the above-described configuration, an exposure apparatus disclosed in U.S. Patent No. 8,089,616, U.S. Patent Publication No. 2020 / 00257205, or International Publication No. 2005 / 081034 may be used.

[0056] Next, the control performed by the exposure control unit 160 of this embodiment will be described in detail. In this embodiment, the exposure control unit 160 performs intensity control and emission timing control of the light beams L1 to L5. First, the intensity control will be described.

[0057] In this embodiment, the spatial light modulator 121 is illuminated by the illumination light IL including a plurality of types of light having mutually different peak wavelengths, and the illumination light IL patterned by the spatial light modulator 121 is projected onto the wafer W.

[0058] Here, the light L1-L5 included in the illumination light IL has different peak wavelengths. Figure 4 As shown in (A), axial chromatic aberration occurs in which the imaging position (focal point) of each light beam is offset in the Z direction due to the projection optical system 130. In this embodiment, in the direction of travel of light L1 to light L5, the imaging positions of light L5, light L4, light L3, light L2, and light L1 are sequentially (in the order of light L5 to light L1) away from the projection optical system 130. That is, in the direction of travel of light L1 to light L5, the imaging position of light L1 with wavelength λ1 is closest to the projection optical system 130, and the imaging position of light L5 with wavelength λ5 is farthest from the projection optical system 130. In other words, in the direction of travel of light L1 to light L5 (-Z direction), the imaging position of light L1 with wavelength λ1 is the position closest to the surface of the resist 602 (photosensitive material layer) of wafer W (the surface of wafer W), and the imaging position of light L5 with wavelength λ5 is the position farthest from the surface of the resist 602.

[0059] Thus, due to the light L1 to light L5 from the spatial light modulator 121, the positions of the pattern images SI1 to SI5 (hereinafter also referred to as the pattern images of the light L1 to light L5) generated by the spatial light modulator 121 are farther away from the surface of the resist 602 of the wafer W in the order of light L5, light L4, light L3, light L2 and light L1 from far to near in the direction of travel of the light L1 to light L5. It should be noted that, when the magnification chromatic aberration of the projection optical system 130 is ignored, as shown in FIG. Figure 4 As shown in FIG. 5 (A), pattern images SI1 to SI5 of the light L1 to the light L5 overlap in a direction intersecting the optical axis AX.

[0060] Therefore, if Figure 4As shown in (B), the composite pattern image SIM obtained by synthesizing the pattern images SI1 to SI5 of the five types of light L1 to L5 becomes an image with a greater depth (length in the Z direction) than width (length in the X direction). In this way, by using illumination light IL including multiple types of light 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.

[0061] However, the inventors have discovered that when each light beam L1-L5 is emitted at the same intensity, the intensity of the light pattern image decreases as the imaging position is farther from the surface of the resist 602, depending on the attenuation coefficient of the resist 602. This point will be described in more detail.

[0062] The inventor simulated the situation in which the light L1-L5 with the same intensity was used to treat the Figure 5 When the mask 503 of the pattern shown in (A) is illuminated, the light L1-L5 passing through the mask 503 is applied to the Figure 5 The intensity of the pattern image formed in the resist 502 on the substrate 501 shown in (B). Figure 5 As shown in (A), the mask 503 has a square pattern with a side of 200 nm. Figure 5 In (A), the shaded portion indicates a case where the light transmittance is 0.

[0063] In the simulation, the numerical aperture (NA) was assumed to be 0.8. Furthermore, the substrate 501 was assumed to have a refractive index of 1.72 and an attenuation coefficient of 0.005. Furthermore, it was assumed that the substrate 501 did not reflect light L1-L5. The resist 502 was assumed to have a thickness of 4 μm, a refractive index of 1.72, and an attenuation coefficient of 0.005.

[0064] Figure 6 (A) to Figure 6 (E) is a diagram showing the results of a simulation of the intensity distribution of the pattern images of light L1 to light L5 within the resist 502, when light L1 to light L5 are set to the same intensity. Here, due to axial chromatic aberration of the projection optical system 130, the focusing position of light Ln+1 is located at a position approximately 1160 nm deeper than the focusing position of light Ln (n = 1 to 4). Figure 6 (A) to Figure 6 (E) shows the intensity distribution of the pattern image of light L1 to light L5 in the resist 502 as contour lines, and the numbers on the contour lines represent the intensity. It should be noted that the higher the numerical value marked on the contour line, the higher the intensity.

[0065] like Figure 6 (A) to Figure 6As shown in (E), due to the influence of the attenuation coefficient of the resist 502, the farther the formation position of the pattern image is from the surface of the resist 502, the smaller the intensity.

[0066] Therefore, in this embodiment, the intensities of the light L1 to the light L5 when entering the illumination optical system 112 are made different from each other. More specifically, Figure 7 As shown, in the direction of travel of light L1 to light L5, the farther the imaging position is from the surface of the resist 602, that is, the farther the position where the pattern image of light L1 to light L5 is formed is from the surface of the resist 602, the greater the intensity. In other words, the farther the position where the pattern image is formed is from the surface of the resist 602, the higher the intensity of the light irradiated onto the wafer W.

[0067] In this embodiment, the positions at which the pattern images of light L1 through light L5 are formed are located farther from the resist surface than light L5 in the direction of travel of light L1 through light L5. Therefore, if the intensity of light L1 is set to In1, the intensity of light L2 is set to In2, the intensity of light L3 is set to In3, the intensity of light L4 is set to In4, and the intensity of light L5 is set to In5, then In1 < In2 < In3 < In4 < In5. Thus, the intensities of light L1 through light L5 irradiating wafer W decrease in the order from light L5 to light L1.

[0068] The intensities In1 to In5 of the lights 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. It should be noted that, for example, the intensities In1 to In5 of the lights L1 to L5 can also be adjusted by setting the first to fifth solid-state laser light sources SLS1 to SLS5.

[0069] It should be noted that the intensities In1 to In5 of the lights L1 to L5 can also be adjusted using a neutral density filter based on the control or setting of the first to fifth solid-state laser light sources SLS1 to SLS5. Alternatively, the intensities of the lights L1 to L5 emitted from the first to fifth solid-state laser light sources SLS1 to SLS5 can be made uniform, and the neutral density filters can be used to adjust the intensities In1-In5 when incident on the illumination optical system 112 (the intensities when irradiating the wafer W) to satisfy the following conditions: In1 < In2 < In3 < In4 < In5.

[0070] Figure 8 Is to show the Figure 6 (A) to Figure 6The intensity distribution of the composite pattern image formed in the resist 502 is simulated when the illumination light IL after adjusting the intensity of each of the light L1-L5 (E) illuminates the mask 503. The intensity Isum of the composite pattern image is calculated by the following formula:

[0071] Isum=ΣIni·I(λi).

[0072] Here, Ini (i=1-5) is a weighting coefficient, and I(λi) is the intensity of light Li (i=1-5) emitted from a 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). Figure 8 In the simulation, In1=0.077, In2=0.116, In3=0.164, In4=0.232, In5=0.411.

[0073] like Figure 8 As shown, it can be seen that by setting In1 < In2 < In3 < In4 < In5, a synthetic pattern image having uniform intensity in the depth direction of the resist 502 is formed.

[0074] The interval Δλ between the wavelengths of light L1-L5 is determined so that the NILS (Normalized Image Log Slope) in the X and Y directions of the composite pattern image obtained by synthesizing the pattern images of the multiple lights is high, the unevenness of the intensity of the composite pattern image in the Z direction is small (high uniformity), and the number of wavelengths used is small. If the difference between the focus position of the light with wavelength λ and the focus position of the light with wavelength λ+Δλ is denoted as ΔFocus, then

[0075] ΔFocus=k2·λ / NA 2 =Cz·Δλ

[0076] ∴Δλ=k2·λ / Cz·NA 2 ,

[0077] The interval Δλ between wavelengths can be converted to k2, where Cz represents axial chromatic aberration, NA represents numerical aperture, and λ represents a representative (specific) wavelength (e.g., 248 nm) within the range of wavelengths λ1-λ5 including the light L1-L5.

[0078] A simulation was performed to find the optimal k2. Figure 9 (A) to Figure 11 (B) is a diagram showing the results of simulations of NILS, uniformity, and the number of wavelengths at each k2 for cases where the numerical aperture NA is 0.4, 0.5, 0.6, 0.7, 0.8, and 1.35.

[0079] As described above, it is preferred that the NILS of the composite pattern image in the X and Y directions be high, the unevenness of the intensity of the composite pattern image in the Z direction be small (high uniformity), and the number of wavelengths used be small. Figure 9 As shown in (A), when the numerical aperture NA is 0.4, it is considered that k2 is best at 1.6. Figure 9 As shown in (B), when the numerical aperture NA is 0.6, it is considered that k2 is best when it is 1.4. Figure 10 As shown in (A), when the numerical aperture NA is 0.6, it is considered that k2 is best at 1.2. Figure 10 As shown in (B), when the numerical aperture NA is 0.7, it is considered that k2 is best at 1.4. Figure 11 As shown in (A), when the numerical aperture NA is 0.8, it is considered that k2 is optimally 1.2.

[0080] As described above, when the numerical aperture NA is less than 1, it is preferable to set Δλ satisfying k2=1.2-1.6 as the wavelength interval.

[0081] In addition, if Figure 11 As shown in (B), when the numerical aperture NA is 1.35, it is considered that k2 can be set to about 2.

[0082] Next, emission timing control of the light L1 to L5 will be described.

[0083] In this embodiment, in order to realize optical path separation using the reflective spatial light modulator 121, the projection optical system 130 is an off-axis optical system with one side being telecentric (the spatial light modulator 121 side is non-telecentric). Figure 12 As shown, in the exposure area of ​​this off-axis optical system, the center of the exposure area of ​​each light beam is located at a position offset from the optical axis AX (the center of the lens) of the projection optical system 130 in the X direction (scanning direction). In other words, the pattern image formed by each of the lights L1 to L5 is formed at a position offset from the optical axis AX of the projection optical system 130. As a result, a shift in magnification chromatic aberration occurs in the X direction.

[0084] Figure 13 (A) is a diagram showing the distribution of chromatic aberration of magnification of the projection optical system 130, Figure 13 (B) is a diagram showing the distribution of magnification chromatic aberration after scanning and averaging when scanning is performed in the +X direction. Figure 13 (A) and Figure 13 In (B), the arrow is a vector 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 represents the coefficient, b represents the offset, x represents the position in the X direction, and y represents the position in the Y direction.

[0085] like Figure 13 As shown in (A), the farther away from the optical axis AX, the greater the magnification chromatic aberration. Here, for example, at y = 0, the magnification chromatic aberration in the Y direction is offset to 0 due to the scanning averaging effect, and in the X direction, as shown in Figure 13 As shown in (B), an offset amount (b) of the chromatic aberration of magnification remains.

[0086] Figure 14 (A) and Figure 14 (B) is a diagram showing the result of simulating the intensity distribution of the synthetic pattern image formed in the resist 502 after scanning averaging. Figure 14 (A) is the intensity distribution on the surface perpendicular to the X axis at y = 0, Figure 14 (B) is the intensity distribution on the plane orthogonal to the Y-axis.

[0087] like Figure 14 As shown in (A), the scanning averaging effect is used and the plane perpendicular to the X axis is not affected by the chromatic aberration of magnification. Figure 14 As shown in (B), the composite pattern image is tilted on a plane perpendicular to the Y axis due to the influence of magnification chromatic aberration. More specifically, in the direction of travel of light L1 to light L5, the farther the position of the pattern image of light L1 to light L5 is from the resist 602, the further the pattern image is formed in the X direction from the optical axis AX. As a result, the pattern formed in the resist 502 by scanning exposure has a tilted inner wall (cross section).

[0088] Therefore, in this embodiment, the timings of emitting the lights L1 to L5 are different from each other. More specifically, in the traveling direction of the lights L1 to L5, 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.

[0089] Figure 15is a diagram illustrating the emission timing of light L1 to light L5. In this embodiment, since the position where the pattern image is formed is farther away 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 the 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. Thus, the farther the position where the pattern image is formed is from the surface of the resist 602, the later the emission timing of light onto the resist 602. That is, the timing of light L1 irradiating the resist 602 is the earliest, and the timing of light L5 irradiating the resist 602 is the latest. According to the scanning direction and scanning speed of the wafer W, the pattern image of light L1 to light L5 can be formed at approximately the same position in the scanning direction (+X direction) by adjusting (changing) the timing of light L1 to light L5 irradiating the resist 602 of the wafer W. For example, when the formation position of the pattern image of light L1 differs from the formation position of the pattern image of light L2 by ΔX in the scanning direction (+X direction), after light L1 is irradiated onto the resist 602, at the timing when the wafer W moves ΔX through scanning, by irradiating light L2 onto the resist 602, the formation position of the pattern image of light L1 on the wafer W can be made roughly consistent with the formation position of the pattern image of light L2 in the scanning direction (+X direction).

[0090] It should be noted that, when the scanning direction of the wafer W is the -X direction, the farther the position where the pattern image is formed is from the surface of the resist 602, the earlier the timing of irradiation onto the resist 602. For example, as disclosed in the aforementioned U.S. Patent No. 8,089,616, when performing scanning exposure by raster scanning while switching the scanning direction to the reverse direction, the timing of instructions (trigger signals) to the multiple solid-state laser light sources SLS1-SLS5 emitting light of different wavelengths can be changed according to the scanning direction.

[0091] Figure 16 It shows that Figure 15 Graphs showing simulation results of the intensity of a composite pattern image obtained by shifting the emission timing of the light beams L1 to L5 and averaged by scanning on a cross section perpendicular to the Y axis.

[0092] like Figure 16 As shown, the farther the position of the pattern image formed by each light L1-L5 is from the surface of the resist 602, the later the emission timing (irradiation timing of the resist 602) is, the more correct the offset of the magnification chromatic aberration can be, and the tilt of the composite pattern image in the X direction (scanning direction) can be suppressed.

[0093] As described in detail above, according to this embodiment, the exposure apparatus 100 includes: an illumination optical system 112 for illuminating a spatial light modulator 121 with illumination light IL including light L1 to light L5 having mutually different wavelengths λ1 to λ5; and a projection optical system 130 for projecting an image of a pattern generated by the spatial light modulator 121 onto a wafer W using the illumination light IL from the spatial light modulator 121. The projection optical system 130 forms an image of the pattern generated by the spatial light modulator 121 using the illumination light L1 to illumination light L5 from the spatial light modulator 121. The pattern images of the illumination light L1 to illumination light L5 are formed at positions farther from the surface of the wafer W in the order in which the illumination light L1 to illumination light L5 travel in the direction in which the illumination light L1 to illumination light L5 travel. Furthermore, the intensities of the illumination light L1 to illumination light L5 irradiated onto the wafer W decrease in the order in which the illumination light L5 decreases.

[0094] The position where the pattern image of illumination light L1 to illumination light L5 is formed is farther away from the surface of wafer W in the order of illumination light L1 to L5 in the direction of travel of illumination light L1-L5. By synthesizing the pattern images of illumination light L1-L5, a synthetic pattern image that is longer in the depth direction of resist 602 can be formed. In addition, the intensity of illumination light L1 to illumination light L5 irradiated to wafer W is from high to low in the order of illumination light L5 to illumination light L1. Therefore, the problem that the position where the pattern image is formed has a lower intensity as it is farther away from the surface of wafer W due to the attenuation intensity of resist 602 can be solved, and a synthetic pattern image with uniform intensity in the depth direction of resist 602 can be formed. As a result, a pattern (groove) with a certain width in the depth direction and a high aspect ratio can be formed in resist 602.

[0095] This point will be explained in more detail. Figure 17 (A) to Figure 17 (C) is a diagram showing simulation results of the intensity of the synthetic pattern image formed in the resist 502 by the methods of Comparative Examples 1 to 3. Figure 17 (D) is a diagram showing simulation results of the intensity of the synthetic pattern image formed in the resist 502 by the method of this embodiment.

[0096] More specifically, Figure 17 (A) shows a simulation result of the intensity of the synthetic pattern image formed in the resist 502 when the mask 503 is illuminated with a light 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). Figure 17(B) is a diagram showing simulation results of the intensity of a composite pattern image formed in the resist 502 when the mask 503 is illuminated with two types of light having different peak wavelengths (Comparative Example 2). Note that the mask 503 is illuminated with the same intensity by the two types of light. Figure 17 (C) is a diagram showing simulation results of the intensity of a composite pattern image formed in the resist 502 when the mask 503 is illuminated with five types of light having different peak wavelengths (Comparative Example 3). Note that the mask 503 is illuminated with the same intensity by the five types of light. Figure 17 (D) is a diagram showing simulation results of the intensity of a synthetic pattern image formed in the resist 502 when the intensity control of this embodiment is performed and the mask 503 is illuminated with five types of light having different peak wavelengths.

[0097] according to Figure 17 (A) to Figure 17 It is clear from (D) that the intensity control of this embodiment can form a synthetic pattern image with uniform intensity distribution in the depth direction. It should be noted that the uniformity of the intensity in the depth direction (1σ) is Figure 17 (A)) is 38.8%, and in Comparative Example 2 ( Figure 17 (B)) is 50.5%, and in Comparative Example 3 ( Figure 17 In (C))) it is 23.7%, in this embodiment ( Figure 17 (D)) is 1.2%.

[0098] In addition, in this embodiment, the exposure device 100 has an exposure control unit 160, which controls the light source unit 111 that supplies illumination light IL to the illumination optical system 112. The exposure control unit 160 controls the timing delay of irradiating the illumination light L1-L5 to the wafer W in the order of illumination light L5 to illumination light L1.

[0099] Due to the offset in magnification chromatic aberration of the projection optical system 130, the position where the pattern image of the illumination lights L1-L5 is formed is located away from the optical axis AX of the projection optical system 130 in the scanning direction (X direction), in the order from illumination light L5 to illumination light L1. Therefore, by delaying the timing of irradiating the wafer W with the illumination lights L1-L5 in the order from illumination light L5 to illumination light L1, the pattern images of the illumination lights L1 to illumination light L5 can be formed at approximately the same position in the scanning direction by scanning the wafer W, thereby forming a high aspect ratio pattern that is approximately parallel to the depth direction of the resist 602.

[0100] It should be noted that in the above embodiment, five types of light L1-L5 with mutually different wavelengths are used as illumination light IL, but this is not limiting. The number of light sources included in illumination light IL may be two or more. For example, in the case of illumination light IL comprising light L1 with wavelength λ1 and light L2 with wavelength λ2, which is different from 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. Furthermore, the image of the pattern generated by the spatial light modulator 121 using the illumination light L2 from the spatial light modulator 121 is formed at a position farther from the surface of the wafer W than the image of the pattern formed by the illumination light L1 in the direction of travel of the illumination light L2. In this case, the intensity of the illumination light L2 irradiating the wafer W may be higher than the intensity of the illumination light L1 irradiating the wafer W. Furthermore, the exposure control unit 160 may control the timing of irradiating the wafer W with illumination light L2 so that the timing of irradiating the wafer W with illumination light L2 is later than the timing of irradiating the wafer W with illumination light L1.

[0101] The amount of light included 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 formed in the resist 602 , and the like.

[0102] It should be noted that, in the above-described embodiment, the projection optical system 130 is used in which chromatic aberration correction is performed such that the image formation position moves away from the projection optical system 130 as the wavelength becomes longer. However, the chromatic aberration correction state of the projection optical system may be a chromatic aberration correction state in which the image formation position moves away from the projection optical system 130 as the wavelength becomes shorter, or a chromatic aberration correction state in which the image formation position moves away from or approaches the projection optical system 130 as the wavelength moves away from a specific wavelength (e.g., wavelength λ3). Similarly, in the above-described embodiment, the projection optical system 130 is used in which chromatic aberration correction is performed such that the magnification increases as the wavelength increases. However, the chromatic aberration correction state of the projection optical system may be a chromatic aberration correction state in which the magnification increases as the wavelength becomes shorter, or a chromatic aberration correction state in which the magnification increases or decreases as the wavelength moves away from a specific wavelength (e.g., wavelength λ3).

[0103] In addition, in the above-described embodiment, the exposure control unit 160 performs both the intensity control and the emission timing control, but may perform only one of the controls.

[0104] In addition, in the above embodiment, the emission timing control of light L1-L5 is explained by taking the case where the projection optical system 130 is unilaterally telecentric as an example, but the emission timing control can be applied not only to the case where the projection optical system 130 is unilaterally telecentric, but also to the case where there is a residual offset of the magnification chromatic aberration after scanning averaging.

[0105] In the above embodiment, the exposure apparatus 100 is described as an exposure apparatus using an SLM, but the exposure apparatus 100 may also be an exposure apparatus using a reticle (photomask). In this case, the exposure apparatus 100 exposes a pattern formed on the reticle onto the resist (photosensitive material layer) on the wafer W.

[0106] In addition, in the above embodiment, a composite pattern image having a uniform intensity distribution in the depth direction is shown, but a uniform intensity distribution may not be ideal. In this case, the desired wavelength combination and intensity may be selected to achieve an ideal intensity distribution.

[0107] In addition, in the above embodiment, attention is paid to the intensity distribution after synthesis, but a necessary combination of wavelengths and intensities may be selected so that the cross section of the resist 602 after development becomes a desired shape.

[0108] It should be noted that in the above embodiment, the wavelength intervals of the lights L1-L5 are preferably equal, but they do not need to be equal. Furthermore, in the above embodiment, when the wavelength intervals of the lights L1-L5 are equal, the emission timings of the lights L1-L5 are preferably equal, but they do not need to be equal. Furthermore, when the wavelength intervals of the lights L1-L5 are not equal, the emission timings of the lights L1-L5 do not need to be equal.

[0109] The above-mentioned embodiments are preferred examples of the present invention, but are not limited thereto and various modifications can be made without departing from the spirit of the present invention.

[0110] Description of Reference Numerals

[0111] 100 exposure devices

[0112] 111 light source unit

[0113] 112 Illumination Optical System

[0114] 121 spatial light modulator

[0115] 130 projection optical system

[0116] AX optical axis

[0117] L1-L5 light

[0118] IL lighting

[0119] W wafer

[0120] 602 resist.

Claims

1. An exposure method comprising: illuminating a first object with exposure light including a first exposure light having a first wavelength and a second exposure light having a second wavelength different from the first wavelength; as well as exposing an image of the pattern of the first object onto a second object using the exposure light from the first object, The exposing includes: forming a first image of a 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 at a position farther from the surface of the second object than the first image in the direction of travel of the second exposure light using the second exposure light from the first object, 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.

2. The exposure method according to claim 1, wherein The exposure includes forming the first image and the second image by using a projection optical system to project the exposure light from the first object onto the second object.

3. The exposure method according to claim 2, wherein: The second image overlaps with the first image in a direction intersecting the optical axis of the projection optical system.

4. The exposure method according to any one of claims 1 to 3, wherein The exposure light includes exposure light of multiple wavelengths, and the exposure light of multiple wavelengths includes the first exposure light and the second exposure light, When k2 is set as a coefficient, NA is set as a numerical aperture, and λ is set as a specific wavelength within a range including the plurality of wavelengths, the difference Δλ between adjacent wavelengths in the exposure light of the plurality of wavelengths is given by Δλ=k2×λ / NA 2 express, Among them, k2=1.3-1.

6.

5. The exposure method according to claim 4, wherein The wavelengths of the exposure light of the plurality of wavelengths are spaced at equal intervals.

6. The exposure method according to any one of claims 1 to 5, wherein The timing at which the second exposure light is irradiated onto the second object is different from the timing at which the first exposure light is irradiated onto the second object.

7. An exposure method comprising: illuminating a first object with exposure light including a first exposure light having a first wavelength and a second exposure light having a second wavelength different from the first wavelength; exposing a second object moving along a scanning direction using the exposure light from the first object, The exposing includes: forming a first image of a pattern of the first object using the first exposure light from the first object; forming a second image of the pattern of 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 using the second exposure light from the first object, The timing at which the second exposure light is irradiated onto the second object is different from the timing at which the first exposure light is irradiated onto the second object.

8. The exposure method according to claim 7, wherein: The exposure includes forming the first image and the second image by using a projection optical system to project the exposure light from the first object onto the second object.

9. The exposure method according to claim 8, wherein: The projection optical system is an optical system in which the first object side is non-telecentric.

10. The exposure method according to claim 8 or 9, wherein: The first image and the second image are formed at positions offset from the optical axis of the projection optical system.

11. The exposure method according to any one of claims 1 to 10, wherein The first object is a mask on which the pattern is formed or a spatial light modulator that generates the pattern.

12. An exposure apparatus comprising: an illumination optical system for illuminating a first object with exposure light including a first exposure light having a first wavelength and a second exposure light having 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, The projection optical system forms a first image of a 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 direction of travel of the second exposure light. 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.

13. The exposure apparatus according to claim 12, wherein A control device is further provided for controlling the light source that supplies the exposure light to the illumination optical system so that the intensity of the second exposure light irradiated on the second object is higher than the intensity of the first exposure light irradiated on the second object.

14. An exposure device for scanning and exposing a pattern of a first object onto a second object, the exposure device comprising: an illumination optical system for illuminating a first object with exposure light including a first exposure light having a first wavelength and a second exposure light having 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; as well as a control device for controlling a light source for supplying the exposure light to the illumination optical system; The projection optical system forms a first image of a 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 direction of travel of the second exposure light. The control device performs control so that the timing at which the second exposure light is irradiated onto the second object is different from the timing at which the first exposure light is irradiated onto the second object.

15. A device manufacturing method comprising: exposing the photosensitive material layer of the second object using the exposure method according to any one of claims 1 to 11; as well as The inner side of the second object relative to the photosensitive material layer is processed using a pattern produced by developing the exposed photosensitive material layer as a mask.

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