Illumination optical system, exposure device, irradiation method and manufacturing method of optical

Abstract

[The technical problem to be solved] The objective of this invention is to provide an illumination optical system, an exposure apparatus, an irradiation method, and a method for manufacturing a component that can improve the resolution of exposure. Technical means to solve the problem One embodiment of the present invention provides an illumination optical system that illuminates an object with light from a light source, comprising an integrator optical system, a condenser lens, and a bandpass filter. The integrator optical system is positioned along the light path emitted from the light source to homogenize the illuminance distribution of the light illuminating the object. The condenser lens, composed of multiple lenses, illuminates the object with light emitted from the integrator optical system. The bandpass filter is positioned among some of the multiple lenses configured as the condenser lens.

Description

Technical Field

[0001] This invention relates to an illumination optical system, an exposure apparatus, an irradiation method, and a method for manufacturing parts. Prior Technology

[0002] The technique of transferring a pattern formed on a mask (original) onto a substrate using an exposure device (projection exposure device) is widely implemented. In the exposure apparatus, light is illuminating the mask through an illumination optics system, and the image of the mask pattern is projected onto the substrate through a projection optics system. In projection optics systems, when using imaging optics systems with projection lenses, there is a problem that the resolution of the image projected onto the substrate is reduced due to the wavelength range of the bright-line spectrum of the light source and the chromatic aberration of the projection lens.

[0003] As a technology for solving this problem, Patent Document 1 describes a method of placing a bandpass filter on the light incident surface side of the integrator lens (placed closer to the light source side than the integrator lens) so that only light of the wavelength corrected for aberrations can pass through. [Previous Technical Documents] [Patent Document]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 6-61122 Summary of the Invention

[0005] [The problem that the invention aims to solve]

[0006] By using a bandpass filter in this way, the reduction in resolution of the image projected onto the substrate can be suppressed to some extent. On the other hand, in recent years, the miniaturization of wiring patterns and other details has become increasingly sophisticated, demanding further improvements in exposure precision. In other words, there is a need for technologies that enhance exposure resolution.

[0007] In view of the above, the object of the present invention is to provide an illumination optical system, an exposure apparatus, an irradiation method, and a method for manufacturing a part that can improve the resolution of exposure. [Methods used to solve the problem]

[0008] To achieve the aforementioned objective, one aspect of the illumination optical system of the present invention is an illumination optical system that illuminates an object with light from a light source, and includes an integrator optical system, a condenser lens, and a bandpass filter. The aforementioned integrator optical system is positioned on the light path emitted from the aforementioned light source unit, thereby homogenizing the illuminance distribution of the light irradiated onto the aforementioned object. The aforementioned condenser lens is composed of multiple lenses, which illuminate the aforementioned object with light emitted from the aforementioned integrator optical system. The aforementioned bandpass filter is disposed among some of the aforementioned complex lenses that are configured as the aforementioned condenser lens.

[0009] In this illumination optical system, a bandpass filter is positioned between some of the complex lenses configured as condenser lenses. This effectively suppresses the influence of the incident angle dependence of the light from the bandpass filter. As a result, the filter characteristics of the bandpass filter can be fully utilized. By using this illumination optical system to construct an exposure apparatus, the resolution of the exposure can be improved. Of course, this illumination optical system can also be applied to other devices that emit light.

[0010] The aforementioned lighting optical system may also include a beam splitter and a sensor unit. The aforementioned beam splitter is positioned on the optical path from the aforementioned integrator optical system to the aforementioned condenser lens, and splits the light emitted from the aforementioned integrator optical system into a first split beam that travels along the aforementioned optical path toward the aforementioned condenser lens, and a second split beam that travels in a direction deviating from the aforementioned optical path. The aforementioned sensor unit is positioned at the location where the second segmented light is incident, and detects the state of the light.

[0011] The aforementioned illumination optical system may further include the aforementioned bandpass filter as a first bandpass filter, and may also include a second bandpass filter having the same filter characteristics as the aforementioned first bandpass filter and disposed on the light incident side of the aforementioned sensor unit.

[0012] The aforementioned bandpass filter can also have a half-width of less than 10nm.

[0013] One aspect of the exposure apparatus of the present invention includes the aforementioned illumination optical system. The aforementioned illumination optical system is configured to illuminate an exposure mask with light.

[0014] The aforementioned exposure device further includes light-shielding blades positioned within 15 mm relative to the aforementioned exposure mask; it may also be configured such that the light being irradiated is partially blocked by the aforementioned light-shielding blades.

[0015] Other forms of the exposure apparatus of the present invention include the aforementioned illumination optical system. Furthermore, the aforementioned exposure apparatus further includes a light-shielding blade and a light-shielding blade projection optical system that projects light emitted from the opening of the aforementioned light-shielding blade onto an exposure mask. The aforementioned illumination optical system is configured to illuminate the opening of the aforementioned light-shielding blade.

[0016] The aforementioned exposure apparatus may also include a projection optical system that projects the pattern of the aforementioned exposure mask, which has been irradiated with the aforementioned light, onto the object to be exposed.

[0017] One aspect of the irradiation method of the present invention is an irradiation method for irradiating an object with light, which includes the step of emitting light from a light source. By using an integrator optical system arranged in the optical path of the light emitted from the aforementioned light source, the light is directed toward a condenser lens composed of multiple lenses, so that the illuminance distribution of the light irradiated on the aforementioned object becomes uniform. The aforementioned focusing lens illuminates the aforementioned object by passing light through a bandpass filter disposed between some of the aforementioned complex lenses.

[0018] One aspect of the present invention is a method for manufacturing a part, which includes a process of irradiating light using the aforementioned light irradiation device.

[0019] The apparatus including the aforementioned illumination optical system may also be an exposure apparatus. In this case, the process of illuminating the aforementioned light may include the process of projecting a pattern onto an exposure mask. Furthermore, the apparatus including the aforementioned illumination optical system may also be other exposure apparatuses without a projection optical system or other apparatuses that illuminate light. [Effects of the Invention]

[0020] As described above, according to the present invention, it is possible to improve the resolution of exposure. Simple Explanation of the Diagram

[0021] [Figure 1] is a schematic diagram showing an example of the structure of an exposure apparatus according to one embodiment of the present invention. [Figure 2] A schematic diagram showing an example of the structure of an exposure apparatus in another embodiment of the present invention. [Figure 3] A schematic diagram showing an example of the structure of the illumination optical system of the first embodiment. [Figure 4] A graph showing the filter characteristics (transmittance characteristics) of a bandpass filter and an example of the spectrum of light emitted from an illumination optics system. [Figure 5] is a graph showing the simulation results of the light incident angle distribution on the filter surface when the bandpass filter is placed at various positions within the illumination optics system. [Figure 6] A schematic diagram showing an example of the structure of the illumination optical system in the second embodiment. [Figure 7] A schematic diagram illustrating other configuration locations of the sensor section. Implementation Method

[0022] Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[0023] [Basic Structure of Exposure Apparatus] Figure 1 is a schematic diagram illustrating an example of the structure of an exposure apparatus according to one embodiment of the present invention. Exposure apparatus 1 includes an illumination optical system 2, a mask stage 3, a projection optical system 4, and a workpiece stage 5. The illumination optical system 2, the mask stage 3, the projection optical system 4, and the workpiece stage 5 are arranged in this order along the optical axis O of the illumination optical system 2.

[0024] Hereinafter, as shown in Figure 1, the direction of the optical axis O of the illumination optical system 2 is defined as the Z direction. Furthermore, the direction orthogonal to the Z direction and extending horizontally in the figure is defined as the X direction. Also, the direction orthogonal to both the Z and X directions and extending vertically in the figure is defined as the Y direction.

[0025] The mask stage 3 holds the exposure mask (hereinafter referred to as the mask) 7. In this embodiment, the mask 7 is arranged orthogonally to the optical axis O of the illumination optical system 2. A predetermined pattern is formed on the mask 7. The detailed structure of the mask 7 is not limited. Similarly, the detailed structure of the masking platform 3 is not limited, and any structure may be used.

[0026] The workpiece stage 5 holds the substrate 8 as a workpiece. In this embodiment, the substrate 8 is arranged orthogonally to the optical axis O of the illumination optical system 2. Furthermore, the substrate 8 is positioned optically conjugate with respect to the mask 7. Typically, the stage 5 is configured to be movable. For example, by driving the stage 5, the area on the substrate 8 that is to be exposed is moved and exposed in a step-by-step manner (sequential exposure). Also, the stage 5 is moved away from the exposure area to exchange the substrate 8 that is to be exposed.

[0027] The illumination optics system 2 illuminates the mask 7 held on the mask stage 3. The illumination optical system 2 is configured as one embodiment of the illumination optical system of the present invention. The detailed structure of the illumination optical system 2 will be described later.

[0028] The projection optical system 4 projects the image of the pattern formed on the mask 7 onto the substrate 8 disposed on the workpiece stage 5. That is, the projection optical system 4 projects the pattern of the mask 7, which is illuminated by light, onto the substrate 8. The projection optical system 4 is configured as an imaging optical system with a projection lens. The detailed structure of the projection optical system 4 is not limited, and any structure can be adopted.

[0029] Figure 2 is a schematic diagram illustrating an example of the structure of an exposure apparatus according to another embodiment of the present invention. In the exposure apparatus 10 shown in Figure 2, a light-shielding blade 11 and a light-shielding blade projection optical system 12 are arranged between the illumination optical system 2 and the mask stage 3 (mask 7). The light-shielding blade 11 and the light-shielding blade projection optical system 12 are arranged in this order along the optical axis O of the illumination optical system 2.

[0030] The light-shielding blade 11 is configured as a light-shielding component whose opening size can be freely controlled. As shown in FIG2, the illumination optical system 2 illuminates the opening of the light-shielding blade 11. The light-shielding blade projection optical system 12 illuminates the light emitted from the light-shielding blade 11 onto the shield 7, projecting the opening of the light-shielding blade 11 onto the shield 7.

[0031] For example, by controlling the light-shielding blades 11, the image of the light-shielding blades 11 can be projected onto the area on the mask 7 where light is to be blocked. Therefore, by controlling the light-shielding blades 11, the size, shape, and position of the area illuminated by the light on the mask 7 can be controlled. Furthermore, by controlling the light-shielding blades 11, when multiple patterns are formed on the mask 7, light can be irradiated only on the desired pattern, and only that pattern can be exposed on the substrate 8. The specific structure of the light-shielding blade 11 and the light-shielding blade projection optical system 12 is not limited and can be any structure.

[0032] The exposure apparatuses 1 and 10 shown in Figures 1 and 2 correspond to one embodiment of an apparatus incorporating the illumination optical system of the present invention. Furthermore, the substrate 8 corresponds to one embodiment of the object to be exposed.

[0033] In the exposure apparatus 1 shown in Figure 1, the mask stage 3 has the function of a mask holding part for holding the exposure mask. The illumination optical system 2 functions as an illumination optical system for illuminating light for an exposure mask.

[0034] In the exposure apparatus 10 shown in Figure 2, the mask stage 3 has the function of a mask holding part for holding the exposure mask. In the exposure apparatus 10 shown in FIG2, the opening of the illumination shielding blade 11 of the illumination optical system 2, which is configured as one embodiment of the illumination optical system of the present invention, is included. Furthermore, the light-shielding blade projection optical system 12 functions as an optical system that projects light emitted from the opening of the light-shielding blade 11 onto the exposure mask. That is, the light-shielding blade projection optical system 12 projects the image of the opening of the light-shielding blade 11 onto the mask 7.

[0035] [Structure of Illumination Optical System 2] As examples of the structure of the illumination optical system 2 shown in Figures 1 and 2, the first and second embodiments will be described. (First Implementation) Figure 3 is a schematic diagram showing a structural example of the illumination optical system 2A in the first embodiment. The illumination optical system 2A includes a light source 14, an integrator lens 15, a pinhole (aperture) 16, a condenser lens 17, and a bandpass filter 18. The light source 14, integrator lens 15, pinhole 16, condenser lens 17 and bandpass filter 18 are configured with the optical axis O as the reference.

[0036] The illumination optical system 2A allows light (ray) L from the light source 14 to be irradiated onto the object. In the case of the exposure apparatus 1 shown in FIG. 1, the object is the mask 7. In the case of the exposure apparatus 10 shown in FIG. 2, the object is the light-shielding blade 11. The following example illustrates the case where the object is mask 7.

[0037] The light source unit 14 has a lamp 19 and a condenser lens 20. In this embodiment, a short-arc type mercury lamp is used as lamp 19. Light with wavelengths of 365nm (i-line), 405nm (h-line), 436nm (g-line), etc., is emitted from lamp 19 as a bright line.

[0038] Condenser 20 focuses the light L emitted from lamp 19 and emits it along the optical axis O. In this embodiment, the reflecting surface of the condenser lens 20 is composed of a portion of an elliptical surface about the optical axis O. Furthermore, in this embodiment, the condenser lens 20 is configured such that the focal point (first focal point) of one side of the condenser lens 20 is located on the optical axis O. Then, the light-emitting point of the lamp 19 is positioned near the first focal point of the condenser lens 20. Therefore, the lamp 19 is configured such that its light-emitting point is located on the optical axis O.

[0039] Regarding the application of this invention, the structure of the light source unit 14 is not limited, and a light source other than a mercury lamp may be used. For example, a light source that emits light of different wavelength bands may be used, or a solid-state light source such as an LED (Light Emitting Diode) may be used.

[0040] The integrator lens 15 is positioned along the light path of the light L emitted from the light source 14, thereby homogenizing the illuminance distribution of the light L incident on the shield 7. The integrator lens 15 is constructed by arranging a plurality of lens elements (a plurality of tiny lenses) in a horizontal and vertical manner, and is also referred to as fly glasses. The lens elements can also be called wavefront segmentation elements.

[0041] The shape of the irradiated area of ​​the light emitted from the light source 14 and irradiated on the shield 7 is similar to the shape of the lens element constituting the integrator lens 15. The integrator lens 15 is arranged such that the light incident surface 15a is located at or near the focal point (second focal point) on the other side of the condenser lens 20.

[0042] As shown in Figure 3, the light L emitted from each lens element of the integrator lens 15 is used as the diverging light. That is, the light L emitted from the integrator lens 15 is used as the diverging light.

[0043] The integrator lens 15 functions as one embodiment of the integrator optical system of the present invention. The specific structure of the integrator lens 15 is not limited, and any structure may be adopted. Furthermore, as one embodiment of the integrator optical system of the present invention, optical components other than the integrator lens, which is composed of multiple lens elements, may also be used. For example, an optical rod or the like may be used as the integrator optical system.

[0044] The aperture 16 is disposed on the light-emitting side of the integrator lens 15. Specifically, the aperture 16 is disposed near the light-emitting surface 15b of the integrator lens 15. By properly controlling the size (aperture size) of the aperture 16, the viewing angle (also known as the parallel beam half-angle) of the light L illuminating the shield 7 can be controlled. That is, the light beam can be shaped by the aperture 16. Typically, the shape of the aperture 16 (the shape of the opening) when viewed from the optical axis (the direction of extension of the optical axis O) is circular. Of course, it is not limited to this; an elliptical or rectangular opening is also possible.

[0045] The condenser lens 17 is composed of a complex set of lenses 21, which illuminate the shield 7 with light L emitted from the integrator lens 15 and passing through the pinhole 16. In this embodiment, the condenser lens 17 is composed of three lenses 21a to 21c. Furthermore, the condenser lens 17 is configured such that it has a positive refractive power (optical refractive ability) as a whole.

[0046] As shown in Figure 3, light L is emitted from the integrator lens 15 through the aperture 16 as diverging light. This light L is refracted by a positive refractive force through a focusing lens 17 composed of three lenses 21a~21c and is then irradiated onto the shield 7. The shape and refractive power of the light incident and exit surfaces of the three lenses 21a-21c are not limited and can be designed appropriately. For example, a structure in which the light beam is magnified by a lens with negative refractive power and then focused by a lens with positive refractive power can also be used. Furthermore, the number of the plurality of lenses 21 constituting the condenser lens 17 is not limited and any number of lenses can be used. Furthermore, the materials of each lens 21 are not limited, and appropriate design is also acceptable.

[0047] A bandpass filter 18 is disposed between some of the complex lenses 21 configured as a condenser lens 17. In this embodiment, the bandpass filter 18 is disposed between lens 21a and lens 21b. The bandpass filter 18 allows light of a defined wavelength band to pass through while blocking light of other wavelength bands. In other words, the bandpass filter 18 can limit the wavelength band of incident light.

[0048] Figure 4 is a graph showing one example of the filter characteristics (transmittance characteristics) of the bandpass filter 18 and the spectrum of the light L emitted from the illumination optical system 2A. The "filter transmittance" in the figure corresponds to the transmittance characteristics of bandpass filter 18. Furthermore, the "illumination system spectrum" in the figure corresponds to the spectrum of light L emitted from illumination optical system 2A. Additionally, the graph shown in Figure 4 is based on actual measurement results.

[0049] As shown in Figure 4, in this embodiment, the bandpass filter 18 is designed such that the wavelength 365nm (i-line) of the bright line of the lamp 19 becomes the center wavelength of the transmission band. Furthermore, the bandpass filter 18 is configured as a narrowband bandpass filter with a half-width of 10nm or less. In this embodiment, for example, a bandpass filter 18 with a half-width of about 7 nm is used.

[0050] [Research to improve exposure resolution] In order to improve the resolution of the exposure, the inventors of this case repeatedly studied how to reduce the effects of chromatic aberration in the projection lens included in the projection optical system 4 shown in Figure 1. By using a narrow-band bandpass filter 18 to limit the wavelength band of the light L used in the exposure, the effects of chromatic aberration can be reduced. On the other hand, if the transmission band of the narrow-band bandpass filter 18 is too narrow, the light of the wavelength band required for the exposure can no longer be obtained, resulting in insufficient light.

[0051] Research conducted with this in mind revealed that by first using a narrow-band bandpass filter with a half-width of less than 10 nm, it is possible to achieve proper exposure while significantly reducing the chromatic aberration of the projection lens. For example, it is known that using a bandpass filter with a half-width in the range of 6 nm to 10 nm can yield even better results.

[0052] Furthermore, the inventors have repeatedly studied ways to improve the resolution of the exposure. Figure 4 illustrates the transmittance characteristics of ultraviolet light in the wavelength range of 350 nm to 380 nm, with a peak wavelength of 365 nm (i-line), when incident at an angle of θ = 0°. Furthermore, Figure 4 also illustrates the transmittance characteristics of ultraviolet light in the wavelength range of 350 nm to 380 nm, with a peak wavelength of 365 nm (i-line), when incident at an angle of θ = 10°. Comparing the transmittance characteristics at an incident angle θ=0° with those at an incident angle θ=10°, it can be seen that if the incident angle θ of the light incident into the bandpass filter 18 increases, the transmittance characteristics will shift towards the shorter wavelength side.

[0053] Thus, the transmittance characteristics of the bandpass filter 18 are incident angle dependent on the incident angle of the incident light. For example, if the transmittance characteristics change significantly towards the shorter wavelength side, it is possible that a portion of the desired wavelength light is cut off, resulting in a decrease in light quantity (light intensity), or that light leakage from the design wavelength (exposure wavelength) is used for exposure. This phenomenon is associated with a decrease in exposure resolution.

[0054] When using a narrow-band bandpass filter 18 with a half-width of less than 10 nm to reduce the influence of chromatic aberration, it becomes important to suppress as much variation in transmittance characteristics as possible due to incident angle dependence. The inventors of this invention focused on the incident angle distribution of light incident into the bandpass filter 18 and reconsidered the placement of the bandpass filter 18 within the illumination optical system 2 at a position where the range of incident angles (the deviation of the incident angles) is smaller. By placing the bandpass filter 18 at a position where the range of incident angles (the deviation of the incident angles) is smaller, variations in transmittance characteristics can be suppressed as much as possible, thereby improving the resolution of the exposure.

[0055] Furthermore, Figure 4 illustrates the spectrum of light L emitted from the illumination optical system 2A without the bandpass filter 18 (no filter). Additionally, Figure 4 illustrates the spectrum of light L emitted from the illumination optical system 2A with the bandpass filter 18 (with filter). By setting the incident angle range of the light incident on the bandpass filter 18 to a smaller range, the light L of the desired wavelength band can be used for exposure, thereby improving the exposure resolution.

[0056] Figure 5 is a graph showing the simulation results of the incident angle distribution of light L when the bandpass filter 18 is placed at various positions within the illumination optical system 2A. In this simulation, the incident angle of light L incident along the optical axis O (Z direction) is set to 0°, and the incident angle distribution is calculated.

[0057] θ1 shown in Figure 3 is the maximum incident angle of light L incident on the center (position on the optical axis O) of the light incident surface 15a of the integrator lens 15. The curve shown in Figure 5, "between light source and integrator", is a simulation result of the incident angle distribution of light L incident on the bandpass filter 18 when the bandpass filter 18 is arranged between the light source 14 and the integrator lens 15. In this example, the maximum incident angle in the incident angle distribution of light L incident on bandpass filter 18, that is, the angle at which the relative intensity decreases to 0, is a slightly larger value close to θ1 shown in Figure 3.

[0058] The θ2 shown in Figure 3 is the maximum emission angle of the light L emitted from the center (position on the optical axis O) of the light emission surface 15b of the integrator lens 15. In this embodiment, the light L emitted from the center of the light emission surface 15b of the integrator lens 15 can also be referred to as the light L emitted from the center of the aperture 16.

[0059] The graph shown in Figure 5, representing the "interval between integrator and condenser lens," is a simulation result of the exit angle distribution of all light L emitted from the entire light exit surface 15b of the integrator lens 15 and passing through the aperture 16. This graph is a simulation result of the incident angle distribution of light L incident on the bandpass filter 18 when the bandpass filter 18 is positioned between the integrator lens 15 (aperture 16) and the condenser lens 17. In this example, the maximum incident angle in the incident angle distribution of light L incident on bandpass filter 18 is larger than θ2 shown in Figure 3.

[0060] The graph in Figure 5, labeled "condenser lens ~ between lenses," represents a simulation of the incident angle distribution of light L incident on the bandpass filter 18 positioned as shown in Figure 3. In other words, this graph represents a simulation of the incident angle distribution of light L when the bandpass filter 18 is positioned between lenses 21a and 21b of the condenser lens 17.

[0061] In Figure 3, θ3 is the maximum incident angle of light L incident on the edge of the illumination area S on the mask 7. The diagram shown in Figure 5 is a curve between the condenser lens and the mask, which is a simulation result of the incident angle distribution of light L incident on the bandpass filter 18 when the bandpass filter 18 is placed between the condenser lens 17 and the mask 7. In this example, the maximum incident angle in the incident angle distribution of light L incident on bandpass filter 18 is close to the value of θ3 shown in Figure 3.

[0062] As shown in Figure 5, when the bandpass filter 18 is positioned between lenses 21a and 21b of the condenser lens 17, the incident angle distribution range is 0~9°, which is minimized. Therefore, as shown in Figure 3, by positioning the bandpass filter 18 between lenses 21a and 21b of the condenser lens 17, the variation in transmittance characteristics caused by incident angle dependence can be effectively suppressed. As a result, the chromatic aberration of the projection lens can be significantly reduced, and the desired wavelength band of light L can be used for exposure, thereby significantly improving the resolution of the exposure.

[0063] As shown in Figure 3, diverging light emitted from each lens element of the integrator lens 15 enters the condenser lens 17 through the pinhole 16. Therefore, the farther the light L emitted from the integrator lens 15 and after passing through the pinhole 16 is from the pinhole 16, the larger the size of the light beam when viewed along the optical axis O. That is, when viewing light L along the optical axis O, the distance from the outermost edge of the light beam to the optical axis O increases.

[0064] Thus, for the diffused beam, the positive refractive force exerted by the condenser lens 17 causes it to overlap in the illumination area S on the shield 7. Therefore, the incident angle distributions between the condenser lens and the lens and between the condenser lens and the shield shown in Figure 5 are smaller in range compared to the incident angle distributions between the light source and the integrator and between the integrator and the condenser lens. Furthermore, by appropriately designing the lens characteristics of the complex lenses 21 constituting the condenser lens 17, it is relatively easy to reduce the range of the incident angle distribution between the condenser lens and the lenses. Of course, regarding which lenses 21 to place the bandpass filter 18 between, it is sufficient to place it where the range of the incident angle distribution is minimized.

[0065] That is, placing the bandpass filter 18 in the position sandwiched by the lens 21 within the condenser lens 17 composed of multiple lenses 21 is very advantageous for reducing the incident angle range of light rays incident into the bandpass filter 18. As a result, the chromatic aberration of the projection lens can be significantly reduced, and the exposure resolution can be improved by using light L of the desired wavelength band.

[0066] [Irradiation Method] Referring to FIG3, the method of irradiating light L onto the shield 7 (shielding blade 11) caused by the illumination optical system 2A of this embodiment will be described. Light L is emitted from the light source section 14. By using the integrator lens 15 arranged on the light path of the light L emitted from the light source 14, the light L is emitted through the small hole 16 toward the condenser lens 17 composed of multiple lenses 21, so that the illuminance distribution of the light L irradiated on the shield 7 (shielding leaf 11) becomes uniform. By means of the condenser lens 17, light L passing through the bandpass filter 18 disposed between some of the complex lenses 21 is irradiated onto the shield 7 (shielding blade 11). This illumination method can significantly reduce chromatic aberration of the projection lens, and can also improve the exposure resolution by using light L of the desired wavelength band.

[0067] In the illumination optical system 2A of this embodiment, the bandpass filter 18 is disposed between some of the complex lenses 21 configured as condenser lenses 17. This effectively suppresses the influence of the incident angle dependence of the light L from the bandpass filter 18. As a result, the filter characteristics of the bandpass filter 18 can be fully utilized. By using this illumination optical system 2A to construct the exposure apparatus 1 (10), the exposure resolution can be improved. Of course, this illumination optical system 2A can also be applied to other devices for illumination light.

[0068] (Second embodiment) The illumination optical system of the second embodiment of the present invention will be described. In the following description, the parts that are the same in structure and function as the illumination optical system 2A described in the foregoing embodiment will be omitted or simplified.

[0069] Figure 6 is a schematic diagram showing a structural example of the illumination optical system 2B in the second embodiment. The illumination optical system 2B further includes a beam splitter 23, a bandpass filter 24, and a sensor unit 25.

[0070] Beam splitter 23 is positioned on the optical path from integrator lens 15 to condenser lens 17, splitting the light L emitted from integrator lens 15 and passing through aperture 16 into a first split light L1 traveling along the optical path toward condenser lens 17 and a second split light L2 traveling in a direction deviating from the optical path.

[0071] In this embodiment, the light from the transmission beam splitter 23 is directed toward the condenser lens 17 as the first split beam L1. This first split beam L1 is transmitted through the condenser lens 17, which has a bandpass filter 18 disposed inside, and is then irradiated onto the mask 7. That is, the first split beam L1 becomes the light used for exposure. On the other hand, the light reflected by the beam splitter 23 serves as the second split beam L2, which travels in a direction deviating from the light path. Therefore, the second split beam L2 is not used for exposure.

[0072] Furthermore, Figure 6 schematically illustrates the optical axis of the second split beam L2 reflected by the beam splitter 23. The ray of the second split beam L2 itself is omitted from the illustration. The optical axis is assigned a symbol to the second split beam L2.

[0073] The beam splitter 23 is configured such that the amount of light used for exposure of the first split light L1 is greater than the amount of light used for exposure of the second split light L2. That is, in this embodiment, the beam splitter 23 is configured to have the characteristics of high transmittance and low reflectance. For example, a beam splitter 23 with very high transmittance characteristics, such as 92% to 99% transmittance and 1% to 8% reflectance, is used.

[0074] For example, by appropriately coating a single-layer or multi-layer film made of dielectric or the like on both or one side of a transparent substrate, a beam splitter 23 with high transmittance and low reflectance can be made. To achieve high transmittance and low reflectance, an anti-reflection coating that can suppress reflectance to around 2% can be applied to the surface. Furthermore, the specific structure of the beam splitter 23 is not limited; any structure can be used.

[0075] The sensor unit 25 is the light receiver of the illuminance monitor and is positioned at the incident point of the second split light L2. The specific structure of the sensor unit 25 is not limited, and any structure may be used.

[0076] The bandpass filter 24 is disposed on the light incident side of the sensor section 25. Furthermore, the bandpass filter 24 is configured to have the same filter characteristics as the bandpass filter 18. That is, in this embodiment, a narrowband bandpass filter with a half-width of 10 nm or less and the filter characteristics (transmittance characteristics) shown in FIG4 is used as the bandpass filter 24. By configuring the bandpass filter 24, the illuminance of the first segmented light L1 that is illuminated on the mask 7 through the bandpass filter 18 can be monitored with higher accuracy.

[0077] In the structure shown in Figure 6, bandpass filter 18 corresponds to one embodiment of the first bandpass filter. Bandpass filter 24 corresponds to one embodiment of the second bandpass filter.

[0078] The sensor unit 25 functions as an illuminance monitor, correcting the exposure surface illuminance by using the detected light. Then, it performs cumulative exposure control for exposure. That is, it controls the opening time of the switch (omitted in Figure 6) by exposing to a set amount of light. Furthermore, by controlling the lamp power input to the lamp 19 according to the detected illuminance value, it suppresses the decrease in illuminance caused by lamp 19 degradation. For example, during normal use of the exposure apparatus, exposure begins with the lamp power to 19 somewhat suppressed. If the illuminance of the lamp 19 decreases due to time degradation, the lamp power is increased to maintain a constant illuminance on the exposure surface.

[0079] When this control method is implemented, the spectrum of the light L emitted from lamp 19 changes by the change in the lighting power of lamp 19.

[0080] The problems and reasons for the need for the absence of bandpass filter 24 are explained. When using a narrowband bandpass filter 18 with a half-width of less than 10 nm, as shown in Figure 4, due to the spectral variation of the light L emitted from the lamp 19 depending on the lamp power, the relationship between the illuminance on the exposure surface of the light L transmitted through the bandpass filter 18 and the illuminance detected by the illuminance monitor 25 (not passing through the bandpass filter 24) is no longer proportional. In this case, even if the lamp power is controlled and the illuminance is increased by 10% based on the illuminance detected by the illuminance monitor, the illuminance on the exposure surface will not be increased by 10%, but will differ. This is because the spectrum on the exposure surface is different from the spectrum of the light detected by the illuminance monitor 25.

[0081] Therefore, in the illumination optical system 2B shown in FIG6, a bandpass filter 24 having the same filter characteristics as the bandpass filter 18 is arranged on the light incident side of the sensor unit 25. In this way, when the spectral change of the light L emitted from the lamp 19 is controlled by the lamp power, the illuminance of the first segmented light L1 irradiated on the shield 7 by the transmission bandpass filter 18 can be monitored with higher accuracy.

[0082] As shown in Figure 6, θ4 is the tilt angle of the reflective surface of the beam splitter 23 perpendicular to the optical axis O. In this embodiment, a value within the range of 10° to 30° is used as the tilt angle θ4. This allows the second split beam L2 to be properly guided to the sensor unit 25. Furthermore, it effectively suppresses the enlargement of the device caused by the placement of the sensor unit 25. Of course, the angle at which the beam splitter 23 is placed is not limited.

[0083] Figure 7 is a schematic diagram illustrating other configuration positions of the sensor section 25. In the illumination optical system 2B' shown in Figure 7, a sensor unit 25 is disposed on the rear side of the bandpass filter 18. This enables high-precision detection of the illuminance of the light L illuminating the mask 7 or the exposure surface. For example, it is possible to monitor the light L' outside the light L that is superimposed on the illumination area S of the shield 7 in the light emitted from each lens element of the integrator lens 15.

[0084] In the example shown in Figure 7, the light L' emitted further outward from the beam emitted from each lens element and illuminating the illumination area S is monitored. This light L' is illuminated on the periphery outside the illumination area S on the shield 7. That is, if the illumination area S is defined as the effective range, then the light L' is the light that is illuminated outside the effective range. In the example shown in Figure 7, the sensor unit 25 is positioned in the region T that illuminates the light L' illuminating the irradiated area S, which is between the condenser lens 17 and the mask 7, without blocking the light L' illuminating the irradiated area S, and is able to stably receive the light L'.

[0085] The resolution of an exposure is generally directly proportional to the wavelength of the light source (the light being exposed) and inversely proportional to the numerical aperture NA of the illumination optics system 2. Therefore, if the numerical aperture NA increases, the resolution increases. In the example shown in Figure 7, if the numerical aperture NA of the illumination optical system 2B' is increased in order to improve the resolution, the area T in which the sensor section 25 can be disposed between the condenser lens 17 and the shield 7 becomes narrower and becomes the vicinity of the shield 7 (shielding blade 11).

[0086] Since the drive mechanism of the shield 7 (light-shielding blade 11) is configured near the shield 7 (light-shielding blade 11), it is difficult to place the sensor unit 25. It needs to be placed close to the lens 21C of the condenser lens 17. As shown in Figure 7, the region T becomes narrower the closer it is to lens 21C. Therefore, in order to configure the sensor unit 25, it is necessary to irradiate a larger area L' outside the irradiation region S (effective range), thereby expanding the region T. Consequently, the irradiance decreases. Furthermore, the larger the numerical aperture NA, the narrower the region T becomes, and the irradiation range needs to be expanded accordingly, so the irradiance still decreases. Region T is the area where the sensor unit 25 needs to be illuminated with the same stable light as within the effective range S. Since ensuring that region T is the same as expanding the effective range S to include region T, the light utilization efficiency is greatly reduced. Therefore, when using the sensor unit 25 to monitor the light L, the structure shown in FIG6 is more advantageous than the structure shown in FIG7.

[0087] Furthermore, in the first embodiment of the illumination optical system 2A shown in FIG3, and the second embodiment of the illumination optical system 2B and 2B' shown in FIG6 and 7, there may also be a structure in which the pinhole 16 is not provided. For example, when using the projection optical system 4 shown in Figures 1 and 2 for projection exposure, the pinhole 16 is used. On the other hand, there are cases where the pinhole 16 is not used when projection exposure is not performed. Furthermore, in the case of projection exposure, if the lens element of the integrator lens 15 can be made relatively thin and arranged in the same shape as the aperture 16, the aperture 16 can be omitted. Even without using the aperture 16 structure, the same effect as described above is achieved, enabling an increase in exposure resolution.

[0088] [Method for manufacturing parts] As a method for manufacturing parts of the present invention, any method may be implemented, for example, including irradiating light using the apparatus of the illumination optical systems 2A, 2B, 2B' of the first and second embodiments. For example, the exposure apparatus 1 (10) of Figures 1 and 2 is configured as an apparatus including the illumination optical systems 2A, 2B, and 2B' shown in Figures 3, 6, and 7. Then, a part is manufactured by projecting an exposure mask pattern as an illumination light process.

[0089] By using the exposure apparatus 1 (10) for exposure, various substrates with predetermined patterns can be manufactured as parts. For example, as parts, circuit elements, optical elements, MEMS, recording elements, sensors or molds can be manufactured. Examples of electrical circuit components include DRAM, SRAM, flash memory, MRAM (volatile or non-volatile semiconductor memory), LSI, CCD, image sensors, and FPGA semiconductor components. Examples of molds include embossing models.

[0090] It is not limited to an exposure device; it can also be configured as various other devices, including illumination optical systems 2A, 2B, and 2B'. Then, a manufacturing method for producing various parts can be carried out by performing engineering including illumination light using this device.

[0091] <Other Implementation Forms> This invention is not limited to the embodiments described above, and can be implemented in various other embodiments.

[0092] In the case where the exposure apparatus 10 shown in Figure 2 generally uses the light-shielding blade 11, the light-shielding blade projection optical system 12 can be used without the light-shielding blade and the light-shielding blade 11 can be arranged near the mask 7.

[0093] Typically, the light-shielding blades 11 are arranged on the side of the illumination optics system 2 of the mask 7, as part of the arrangement of the mask 7. However, this is not a limitation, and the light-shielding blades 11 may also be arranged on the side of the workpiece stage 5 of the mask 7.

[0094] If the distance between the light-shielding blade 11 and the mask 7 in the direction of the optical axis O is too large, the boundary between the light-shielding area blocked by the light-shielding blade 11 and the exposure area exposed on the substrate 8 will be blurred. Therefore, it is important to make the distance between the light-shielding blade 11 and the mask 7 sufficiently close.

[0095] For example, the illumination optical system 2 is configured to illuminate the mask 7, while the illuminating light is partially blocked by the light-blocking blades 11 disposed within 15 mm of the mask 7. In this way, it is possible to expose only the required area without using the light-blocking blade projection optical system 12. Furthermore, if, with the shield 7 as a reference, the side of the illumination optical system 2 is designated as the positive side and the side of the workpiece stage 5 as the negative side, then the light-shielding blade 11 is positioned within 15 mm of either the positive or negative side. In this case, the light-shielding blade 11 can be considered a structure positioned within ±15 mm of the shield 7.

[0096] Furthermore, since the light-shielding blades 11 and the mask 7 are driven separately, a certain degree of spacing is required. For example, a suitable spacing is set within a range of 15mm to keep them as close as possible without interfering with each other. This allows only the required area to be exposed.

[0097] The structures, irradiation methods, and manufacturing methods of the various optical components included in the exposure apparatus, illumination optical system, bandpass filter, and other illumination optical systems described with reference to the figures are merely one embodiment and can be arbitrarily modified without departing from the spirit of the present invention. That is, any other structures and methods for implementing the present invention may also be used.

[0098] 1: Exposure device 2: Illumination Optical System 2A: Illumination Optical System 2B: Illumination Optical System 2B': Illumination Optical System 3: Shielding Platform 4: Projection optical system 5: Workpiece stage 7: Exposure mask 8:Substrate 10: Exposure device 11: Shading blades 12: Projection optical system for light-shielding blades 14: Light Source Section 15: Integrating Lens 15a: Light incident surface 15b: Light exit surface 16: Small hole 17: Condensing Lens 18: Bandpass filter 19: Lamp 20: Condenser 21: Lens (a lens that forms a condenser lens) 21a: Lens (a lens that forms a condenser lens) 21b: Lens (a lens that forms a condenser lens) 21c: Lens (a lens that forms a condenser lens) 23: Spectrometer 24: Bandpass Filter (Second Bandpass Filter) 25: Sensor Section L: light (ray) L': light (ray) L1: First segmented light L2: Second split light NA: Numerical Aperture O: Optical axis θ1: Maximum incident angle θ2: Maximum exit angle θ3: Maximum incident angle

Claims

1. An illumination optical system for illuminating an object with light from a light source, characterized by comprising: an integrator optical system disposed in the light path of the light emitted from the light source to homogenize the illuminance distribution of the light illuminating the object; a condenser lens composed of multiple lenses to illuminate the object with light emitted from the integrator optical system; and a bandpass filter disposed among some of the multiple lenses configured as the condenser lens.

2. The illumination optical system as described in claim 1, wherein, It also includes: a beam splitter, which is disposed on the optical path from the aforementioned integrator optical system to the aforementioned condenser lens, to split the light emitted from the aforementioned integrator optical system into a first split beam that travels along the aforementioned optical path toward the aforementioned condenser lens, and a second split beam that travels in a direction deviating from the aforementioned optical path; and a sensor unit, which is disposed at the position where the aforementioned second split beam is incident, to detect the state of the light.

3. The illumination optical system as described in claim 2, wherein, The aforementioned bandpass filter is used as the first bandpass filter, and a second bandpass filter with the same filter characteristics as the aforementioned first bandpass filter is provided on the light incident side of the aforementioned sensor unit.

4. The illumination optical system described in any one of claims 1 to 3, wherein, The aforementioned bandpass filter has a half-width of less than 10 nm.

5. An exposure apparatus, characterized in that it includes the illumination optical system described in claim 1, wherein the illumination optical system is configured to illuminate an exposure mask with light.

6. The exposure apparatus as described in claim 5, wherein, It also has light-shielding blades that are positioned within 15mm relative to the aforementioned exposure mask, so as to partially block the irradiated light by means of the aforementioned light-shielding blades.

7. An exposure apparatus, characterized in that it includes the illumination optical system described in claim 1, and further includes a light-shielding blade and a light-shielding blade projection optical system for projecting light emitted from the opening of the aforementioned light-shielding blade onto an exposure mask, wherein the aforementioned illumination optical system is configured to illuminate the opening of the aforementioned light-shielding blade.

8. The exposure apparatus as described in any of claims 5 to 7, wherein, It also features: a projection optical system that projects the pattern of the aforementioned exposure mask, which has been irradiated with the aforementioned light, onto the object to be exposed.

9. An illumination method for illuminating an object with light, characterized in that: light is emitted from a light source, and the light is directed toward a condenser lens composed of multiple lenses by an integrator optical system disposed on the light path of the light emitted from the light source, so as to make the illuminance distribution of the light illuminating the object uniform, and the object is illuminated by light passing through a bandpass filter disposed between some of the multiple lenses by the condenser lens.

10. A method for manufacturing a part, characterized by comprising an apparatus using the illumination optical system described in claim 1, and an engineering process for irradiating light.

11. A method for manufacturing the part as described in claim 10, wherein, The apparatus including the aforementioned illumination optical system is an exposure apparatus, and the process of illuminating the aforementioned light includes the process of projecting a pattern of an exposure mask.

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