Exposure apparatus, exposure method, and method for manufacturing semiconductor device

Abstract

This invention discloses an exposure apparatus, an exposure method, and a method for manufacturing a semiconductor device. The exposure apparatus includes an illumination optics system, a projection optics system, and a controller. The illumination optics system illuminates a master image comprising a periodic pattern. The projection optics system forms an image of the master image on a substrate. The controller is configured to cause light from the illumination optics system to obliquely incident on the master image, such that a light intensity distribution is formed by a diffracted beam in a pupil region of the projection optics system. The controller also controls the exposure of the substrate such that each point in the projection region of the substrate is exposed in at least two focusing states. The light intensity distribution is symmetrical with respect to a line passing through the origin of the pupil region and orthogonal to the periodic direction of the periodic pattern. The diffracted beam comprises diffracted light of at least second order from the periodic pattern.

Description

Technical Field

[0001] This invention relates to an exposure apparatus, an exposure method, and a method for manufacturing a semiconductor device. Background Technology

[0002] The FLEX (Focus Latitude Enhancement Exposure) method is known as a method for increasing the depth of focus in an exposure apparatus. The FLEX method can be defined as a method of exposing a substrate in multiple defocus states, or a method of exposing a substrate such that the light intensity formed by the original image near the image plane of the projection optics system overlaps in the optical axis direction. Japanese Patent Application Publication No. 7-153658 describes an exposure method for satisfactorily resolving isolated patterns such as aperture patterns or micro-patterns. In this exposure method, multi-stage exposure is performed, wherein the substrate is exposed at each of the common focal point and multiple defocus points. For the exposure at the common focal point, the value of the coherence factor (σ) is set to be less than that at each of the multiple defocus points. Summary of the Invention

[0003] This invention provides a technique that is beneficial for improving the depth of focus of an exposure device.

[0004] A first aspect of the present invention provides an exposure apparatus comprising an illumination optics system and a projection optics system, the illumination optics system being configured to illuminate a master plate comprising a periodic pattern, and the projection optics system being configured to form an image of the master plate on a substrate. The apparatus includes a controller configured to cause light from the illumination optics system to obliquely incident on the master plate such that a light intensity distribution is formed in a pupil region of the projection optics system by a plurality of diffracted beams, and to control the exposure of the substrate such that each point in the projection region of the substrate is exposed in at least two focusing states, the light intensity distribution being symmetrical with respect to a straight line passing through the origin of the pupil region and orthogonal to the periodic direction of the periodic pattern, the plurality of diffracted beams comprising diffracted light of at least second order from the periodic pattern.

[0005] A second aspect of the present invention provides an exposure apparatus comprising an illumination optical system and a projection optical system, the illumination optical system being configured to illuminate a master image, and the projection optical system being configured to form an image of the master image on a substrate, wherein a light intensity distribution is formed in a pupil region of the illumination optical system, the light intensity distribution comprising at least two high-intensity portions, the at least two high-intensity portions being arranged symmetrically with respect to a line passing through the origin of the pupil region and orthogonal to the optical axis of the illumination optical system, each high-intensity portion having a higher light intensity than the remaining portions, and letting r be the radius of the pupil region, the center position of the high-intensity portions is located within a range of no more than r / 3 from the origin of the pupil region.

[0006] A third aspect of the invention provides an exposure method for exposing a substrate using an illumination optical system and a projection optical system, the illumination optical system being configured to illuminate a master image comprising a periodic pattern, and the projection optical system being configured to form an image of the master image on the substrate. The method includes obliquely incident light from the illumination optical system onto the master image, such that a light intensity distribution is formed in a pupil region of the projection optical system by a plurality of diffracted beams, the light intensity distribution being symmetrical with respect to a straight line passing through the origin of the pupil region and orthogonal to the periodic direction of the periodic pattern, the plurality of diffracted beams comprising diffracted light of at least second order from the periodic pattern, and controlling the exposure of the substrate such that each point in the projection region of the substrate is exposed in at least two focusing states.

[0007] A fourth aspect of the present invention provides a method for manufacturing a semiconductor device, the method comprising forming a recess in a substrate and forming a pixel separation portion in the recess, wherein forming the recess comprises exposing each point in a projection region of the semiconductor substrate by means of a plurality of diffracted beams in at least two focusing states, the plurality of diffracted beams comprising diffracted light of at least second order from a periodic pattern provided in a master and passing through a pupil region of a projection optics system, and forming a light intensity distribution in the pupil region of the projection optics system, the light intensity distribution comprising at least two high light intensity portions, the at least two high light intensity portions being arranged symmetrically with respect to a straight line passing through the origin of the pupil region and orthogonal to the periodic direction of the periodic pattern, each high light intensity portion having a higher light intensity than the remaining portions.

[0008] A fifth aspect of the present invention provides a method for manufacturing a semiconductor device, the method comprising forming a recess in a substrate and forming a pixel separation portion in the recess, wherein forming the recess in the substrate comprises exposing the substrate according to the exposure method according to a third aspect of the present invention.

[0009] Further features of the invention will become clear from the following description of exemplary embodiments with reference to the accompanying drawings. Attached Figure Description

[0010] Figure 1 This is a schematic diagram showing the arrangement of the exposure apparatus according to the first embodiment;

[0011] Figure 2 This is a diagram used to explain FLEX exposure in the exposure apparatus according to the first embodiment;

[0012] Figure 3 This is an example illustration of a periodic pattern that can be provided in the original version;

[0013] Figure 4A This is an exemplary diagram showing the light intensity distribution in the pupil region of the illumination optics system in Example 1;

[0014] Figure 4B This is a diagram illustrating, exemplarily, the light intensity distribution in the pupil region of a projection optical system;

[0015] Figures 5A to 5C Each of these is an exemplary diagram showing the light intensity distribution formed near the image plane of a projection optical system;

[0016] Figure 6A and 6B The relationship between defocusing amount and light intensity distribution in a single exposure is illustrated by example;

[0017] Figure 7A This is an exemplary diagram showing the light intensity distribution in the pupil region of the illumination optics system in Example 2;

[0018] Figure 7B This is an exemplary diagram showing the light intensity distribution in the pupil region of the projection optics system in Example 2;

[0019] Figure 8 This is an example illustration of a two-dimensional periodic pattern that can be provided in the original version;

[0020] Figure 9 This is an exemplary diagram showing the light intensity distribution in the pupil region of the illumination optics system in Example 3;

[0021] Figure 10 This is an exemplary diagram showing the light intensity distribution in the pupil region of the illumination optics system in Example 4;

[0022] Figures 11A to 11C Each of these is a diagram exemplarily illustrating the relationship between the light intensity distribution in the pupil region of an illumination optical system and the light intensity distribution formed near the image plane of a projection optical system;

[0023] Figures 12A to 12C Each of these is a diagram exemplarily illustrating the relationship between the light intensity distribution in the pupil region of an illumination optical system and the light intensity distribution formed near the image plane of a projection optical system;

[0024] Figure 13 This is a diagram used to explain FLEX exposure in the exposure apparatus according to the second embodiment;

[0025] Figure 14 This is a diagram used to explain FLEX exposure in the exposure apparatus according to the third embodiment;

[0026] Figure 15 This is an exemplary diagram showing the light intensity distribution formed near the image plane of the projection optics system in the exposure apparatus according to the third embodiment;

[0027] Figure 16 This is a schematic diagram showing the arrangement of the exposure apparatus according to the fourth embodiment;

[0028] Figure 17 This is a diagram used to explain the exposure method according to the fourth embodiment;

[0029] Figure 18A and 18B This is a diagram used to explain the exposure method according to the fifth embodiment;

[0030] Figure 19 This is a diagram used to explain the exposure method according to the sixth embodiment;

[0031] Figure 20 This is a diagram used to explain the exposure method according to the sixth embodiment;

[0032] Figure 21A This is a diagram showing the arrangement of the exposure apparatus according to the seventh embodiment;

[0033] Figure 21B This is a diagram used to explain the exposure method according to the seventh embodiment;

[0034] Figure 22A This is an exemplary diagram showing the light intensity distribution in the pupil region of an illumination optical system;

[0035] Figure 22B This is an exemplary diagram showing the light intensity distribution in the pupil region of a projection optical system; and

[0036] Figures 23A to 23C This is a diagram illustrating, exemplarily, the manufacturing steps of an image sensor. Detailed Implementation

[0037] In the following, embodiments will be described in detail with reference to the accompanying drawings. Note that the following embodiments are not intended to limit the scope of the claimed invention. Several features are described in the embodiments, but this does not limit the invention to claiming all such features, and several such features may be suitably combined. Furthermore, in the drawings, the same reference numerals are given the same or similar configuration, and redundant descriptions thereof are omitted.

[0038] In the following description, directions will be indicated in the XYZ coordinate system. The XYZ coordinate system is defined such that the surface parallel to the surface of the substrate is the XY plane, and the axis parallel to the normal direction of the surface of the substrate is the Z axis. The X, Y, and Z directions are parallel to the X, Y, and Z axes of the XYZ coordinate system, respectively.

[0039] Figure 1 The arrangement of the exposure apparatus EXP according to the first embodiment is schematically shown. The exposure apparatus EXP is configured as a projection exposure apparatus to expose the substrate 7 by projecting the pattern of the original plate 2 onto the substrate 7. Alternatively, the exposure apparatus EXP can be configured as a scanning exposure apparatus to perform scanning exposure on the substrate 7 while scanning the original plate 2 and the substrate 7. The exposure apparatus EXP may include an illumination optical system 1, an original plate driving mechanism 3, a projection optical system 4, a substrate driving mechanism 8, an adjuster AD, and a controller CN. The original plate 2 may include a periodic pattern. The original plate driving mechanism 3 holds and drives the original plate 2 in the scanning direction (Y direction). The illumination optical system 1 illuminates the original plate 2 held by the original plate driving mechanism 3. The adjuster AD may be configured to be controlled by the controller CN. The adjuster AD may be integrated into the controller CN.

[0040] The projection optical system 4 forms an image of the pattern of the original plate 2 illuminated by the illumination optical system 1 on the substrate 7. Alternatively, the projection optical system 4 projects the pattern of the original plate 2 illuminated by the illumination optical system 1 onto the substrate 7. The pattern of the original plate 2 illuminated by the illumination optical system 1 generates multiple diffracted beams. The multiple diffracted beams from the pattern of the original plate 2 form an image of the pattern of the original plate 2 (the light intensity distribution corresponding to the pattern of the original plate 2) near the image plane of the projection optical system 4. Here, "near the image plane" includes the image plane and its vicinity. The substrate driving mechanism 8 holds and drives the substrate 7 in the scanning direction (Y direction). The substrate driving mechanism 8 can also drive the substrate 7 in the non-scanning direction (X direction).

[0041] The substrate 7 may include multiple projection regions. The projection regions may include patterns (layers) already formed in the photolithography step, or may not include such patterns (layers). The substrate 7 includes a photoresist layer on a component (e.g., a wafer) formed of semiconductor or non-semiconductor material, unless otherwise specified. One or more layers may be disposed between the component and the photoresist layer.

[0042] Illumination optical system 1 includes a pupil region. The pupil region of illumination optical system 1 is the area within the pupil plane of illumination optical system 1 where light from a light source (not shown) can enter. Projection optical system 4 includes a pupil region. The pupil region of projection optical system 4 is the area within the pupil plane of projection optical system 4 where light from illumination optical system 1 can enter. Let σ be the coherence factor of exposure device EXP, NA1 be the numerical aperture of illumination optical system 1 when viewed from original image 2, and NA2 be the numerical aperture of projection optical system 4 when viewed from original image 2, then σ is defined as follows:

[0043] σ=NA1 / NA2

[0044] The adjuster AD or controller CN can adjust the illumination optical system 1 such that multiple diffracted beams from the periodic pattern of the original 2 form a light intensity distribution in the pupil region of the projection optical system 4, including at least two high-intensity portions. Here, the multiple diffracted beams include second-order or higher-order diffracted light. Here, a high-intensity portion means a portion of the light intensity distribution where the light intensity is higher than the rest (the portion other than the high-intensity portion). The shape of the high-intensity portion is not limited to a specific shape such as a circle, and can be, for example, a rectangle. The high-intensity portion can be a region completely surrounded by a region with light intensity lower than the high-intensity portion, or a region completely surrounded by the boundary between the region with light intensity lower than the high-intensity portion and the pupil region. In addition, the at least two high-intensity portions are arranged symmetrically with respect to a line (straight line) parallel to the periodic direction orthogonal to the periodic direction of the periodic pattern. The adjuster AD can adjust the illumination optical system 1 according to, for example, information about the periodic pattern of the original 2, such that a light intensity distribution is formed in the pupil region of the projection optical system 4, including at least two high-intensity portions arranged symmetrically with respect to a line parallel to the periodic direction orthogonal to the periodic direction of the periodic pattern. The information of the periodic pattern in the original version 2 may include, for example, information such as the spacing of the periodic pattern and the periodic direction of the periodic pattern.

[0045] In another viewpoint, the adjuster AD or controller CN can be configured to obliquely incident light from the illumination optics system 1 onto the original image 2, such that multiple diffracted beams comprising diffracted light of at least second order from the periodic pattern of the original image 2 form a predetermined light intensity distribution in the pupil region. The predetermined light intensity distribution can be a light intensity distribution symmetrical about a straight line relative to the origin of the pupil region passing through the projection optics system 4 and orthogonal to the periodic direction of the periodic pattern of the original image 2.

[0046] The modulator (AD) can be formed from, for example, a PLD (Programmable Logic Device) such as an FPGA (Field Programmable Gate Array), an ASIC (Application Specific Integrated Circuit), a general-purpose or special-purpose computer with embedded programs, or a combination of all or some of these components. In the following description, the high-intensity portion is also referred to as a pole. When using the term "pole," its shape is not limited to a specific shape such as a circle, and can be, for example, rectangular.

[0047] For example, based on information about the periodic pattern of the original 2 (e.g., the spacing of the periodic pattern, the periodic direction of the periodic pattern, etc.), the adjuster AD can select one lighting mode from multiple lighting modes and adjust the lighting optics 1 to set the selected lighting mode. The adjuster AD can refer to, for example, a preset table to select the lighting mode corresponding to the information about the periodic pattern of the original 2. This table can define the correspondence between the information about the periodic pattern of the original 2 and the lighting modes. The lighting mode defines the light intensity distribution to be formed in the pupil area of ​​the lighting optics 1. Multiple lighting modes can include, for example, normal lighting (circular lighting), small σ lighting, polar lighting (dipole, quadrupole, etc.), annular lighting, etc. The setting or selection of the lighting mode can be performed, for example, by rotating a turntable in which multiple aperture stops are arranged or rotating a turntable in which multiple CGHs (computer-generated holograms) are arranged. The adjuster AD can determine the lighting mode based on, for example, user instructions.

[0048] The controller CN can control the exposure of the substrate 7, such that each point in the projection area of ​​the substrate 7 is exposed in two or more focused states (or two or more defocused states). More specifically, the controller CN can control the exposure of the substrate 7 such that, under the condition that the predetermined light intensity distribution mentioned above is formed in the pupil area of ​​the projection optical system 4, each point in the projection area of ​​the substrate 7 is exposed in two or more focused states (or two or more defocused states). Such an exposure method is referred to below as the FLEX method. The controller CN can be formed by, for example, a PLD (Programmable Logic Device) such as an FPGA (Field Programmable Gate Array), an ASIC (Application Specific Integrated Circuit), a general-purpose or special-purpose computer with embedded programs, or a combination of all or some of these components. All or part of the controller CN can be shared or integrated with all or part of the adjuster AD.

[0049] The FLEX method can be implemented in various ways. In a first embodiment, the controller CN controls the exposure of the substrate 7 such that the scanning exposure of the substrate 7 is performed with the normal direction of the surface of the substrate 7 tilted relative to the optical axis (parallel to the Z-axis) of the projection optical system 4. Figure 2 The exposure method according to the first embodiment is schematically illustrated. Dotted lines 10a and 10b indicate the range of exposure light (exposure light defined by the slit) entering the substrate 7. In scanning exposure, the substrate 7 is scanned in the scanning direction (Y direction) along a plane inclined about the X-axis relative to the XY plane. When a point in the projection area of ​​the substrate 7 moves from dotted line 10b to dotted line 10a, this point is exposed simultaneously with the movement of the distance Z1 between the two planes sandwiching the optimal focal plane 9 of the projection optics system 4.

[0050] In other words, in scanning exposure using the FLEX method, any point in the projection area of ​​the substrate 7 is exposed to move from a first focused state (or, a first defocused state) to a second focused state (or, a second defocused state). The distance Z1 along the optical axis of the projection optics system 4 between the position of any point in the first focused state (first defocused state) and the position of any point in the second focused state (second defocused state) is the range of the defocus amount at that point. The distance Z1 is a distance or amount that helps to increase the depth of focus using the FLEX method, and this is also referred to hereinafter as the FLEX amount.

[0051] exist Figure 2 In the present invention, scanning exposure of substrate 7 is performed with the normal direction of the surface of substrate 7 tilted relative to the optical axis direction (parallel to the Z-axis) of projection optical system 4. However, scanning exposure of substrate 7 can also be performed with the normal direction of the surface of original 2 tilted relative to the optical axis direction (parallel to the Z-axis) of projection optical system 4.

[0052] Figure 3 An exemplary illustration is shown of the periodic pattern 11 provided in original version 2. P indicates the spacing (period) of the periodic pattern 11, S indicates the linewidth of the transmissive portion, and L indicates the linewidth of the light-shielding portion. In this example, the periodic direction of the periodic pattern 11 is the X direction.

[0053] Figure 4A The light intensity distribution (effective light source distribution) of the exposure light in Example 1 within the pupil region 21 of the illumination optical system 1 of the exposure apparatus EXP according to the first embodiment is schematically shown. σx and σy are pupil coordinates indicating the position within the pupil region 21, and the two coordinate axes are parallel to the X-axis and Y-axis, respectively. The origin of the pupil coordinates is matched with the optical axis of the illumination optical system 1. Figure 4AAn example of dipole illumination is shown, with each of D1 and D2 being an indicator pole. Poles D1 and D2 are arranged in positions symmetrical with respect to the σy axis (Y-axis).

[0054] Figure 4B This schematically illustrates what was provided in the original version 2. Figure 3 The periodic pattern 11 shown is Figure 4A The light intensity distribution shown is formed in the pupil region 31 of the projection optical system 4 by multiple diffracted beams from the periodic pattern 11 during illumination. POx and POy are pupil coordinates indicating positions within the pupil region 31, with the two coordinate axes parallel to the X and Y axes, respectively. The origin of the pupil coordinates is matched with the optical axis of the projection optical system 4. D10 indicates the 0th order diffracted light from pole D1. D11 indicates the +1st order diffracted light from pole D1, and D1-1 indicates the -1st order diffracted light from pole D1. D1-2 indicates the -2nd order diffracted light from pole D1. In this example, the +2nd order diffracted light, as well as the 3rd and higher order diffracted beams, do not enter the pupil region 31 of the projection optical system 4.

[0055] Despite Figure 4B Although not shown in the diagram, the diffracted light from pole D2 also enters the pupil region 31 of the projection optical system 4. More specifically, the 0th-order diffracted light D20 from pole D2 enters position D1-1. Additionally, the +1st-order diffracted light D21 from pole D2 enters position D10, and the -1st-order diffracted light D2-1 from pole D2 enters position D1-2. Furthermore, the +2nd-order diffracted light D22 from pole D2 enters position D11. The diffracted beams D10, D11, D1-1, D1-2, D20, D21, D2-1, and D22 form an image of a periodic pattern 11 on the substrate 7.

[0056] The light intensity distribution formed in the pupil region 31 of the projection optical system 4 includes at least two poles, and more specifically, four poles arranged symmetrically with respect to a line (POy axis) parallel to a direction orthogonal to the periodic direction of the periodic pattern 11 (Y direction). The positions and regions of the four poles are indicated by D10, D11, D1-1, and D1-2.

[0057] Here, will be described Figure 3 The spacing P of the periodic pattern 11 shown Figure 4A The poles D1 and D2 in the pupil region 21 shown, and Figure 4B The relationship between the diffracted beams D10, D1-1, D11, and D1-2 in the pupil region 31 is shown. Let NA be the numerical aperture of the projection optical system 4, and λ be the wavelength of the exposure light. First, Figure 4A The coordinates (positions) of the center of each of the poles D1 and D2 shown are expressed as follows:

[0058] D1: σx=λ / (2×P×NA)

[0059] D2: σx=-λ / (2×P×NA)

[0060] Similarly, Figure 4B The coordinates (positions) of the center of each of the diffracted beams D10, D1-1, D11, and D1-2 in the pupil region 31 shown are expressed as follows:

[0061] D10:POx=λ / (2×P×NA)

[0062] D11:POx=3λ / (2×P×NA)

[0063] D1-1: POx = -λ / (2×P×NA)

[0064] D1-2: POx = -3λ / (2×P×NA)

[0065] For example, if the spacing P of the periodic pattern 11 on the image plane is 800 nm, NA = 0.55, and λ = 248 nm, then σx = 0.282.

[0066] Figure 5A This illustrates setting the linewidth S of the transmissive portion of the periodic pattern 11 on the image plane to 200 nm and the linewidth L of its light-shielding portion to 600 nm, and using... Figure 4A Simultaneous execution of the effective light source distribution shown Figure 2 The optical image shown is obtained during FLEX exposure. Figure 4A The center positions of poles D1 and D2 in the effective light source distribution shown are set to σ = ±0.282, and the value obtained by converting the radius of each of poles D1 and D2 into a σ value is set to 0.05. Furthermore, the position of the focal plane (Z direction) set during the exposure of substrate 7 is set within a range of ±1.2 μm (Z1 = 2.4 μm) for the amount of defocusing (FLEX amount) in the FLEX method.

[0067] Figure 5A The horizontal axis represents the light intensity distribution within a range of ±400 nm corresponding to one period of the pattern when the center of the transmissive portion S of the periodic pattern 11 is set at 0. ±100 nm from the center corresponds to the transmissive portion S of the periodic pattern 11. The focal plane is shifted (defocused) from the optimal focal plane 9 of the projection optical system 4 at 0.3 μm intervals from 0 μm to 2.7 μm. For example, from... Figure 5AAs can be seen, even when the focal plane is shifted (defocusing) from the optimal focal plane 9 by 2.7 μm, the light intensity distribution remains almost unchanged. Therefore, the depth of focus is significantly increased.

[0068] Figure 5B and 5C A comparison example is shown. Figure 5B The results are shown by performing a typical scanning exposure using circular illumination with σ = 0.7. Figure 5C The results are shown by performing a FLEX exposure using circular illumination with σ = 0.7, while setting the amount of defocusing (FLEX amount) in the FLEX method within ±1.2 μm (Z1 = 2.4 μm) for the position of the set focal plane (Z direction).

[0069] exist Figure 5B In the comparative example shown, when the focal plane is shifted (defocused) by more than 0.9 μm from the optimal focal plane 9, the light intensity distribution becomes almost flat. Therefore, the depth of focus is no greater than ±1 μm. Figure 5C In the comparative example shown, the light intensity at the optimal focus point is reduced due to averaging, but the way the light intensity distribution changes due to defocusing becomes more gradual, and the depth of focus can be increased to ±1.2 μm or greater.

[0070] Figure 5A and 5B Each of these shows the results of FLEX exposure, but it can be seen that through... Figure 4A and 4B The increased depth of focus achieved by performing illumination under the lighting conditions shown is significant. As mentioned above, increased depth of focus is advantageous in processes such as those using thick-film resists.

[0071] Here, the relationship between the spacing P of the periodic pattern 11, the NA of the projection optical system 4, and the wavelength λ of the exposure light will be described. Figure 4A and 4B In the example shown, multiple diffracted beams, including second-order or higher-order diffracted light from the periodic pattern 11, form a light intensity distribution in the pupil region 31 of the projection optics system 4, comprising at least two poles arranged symmetrically with respect to lines parallel to directions orthogonal to the periodic direction of the periodic pattern 11. Therefore, the positions of D11 and D1-2 in the pupil coordinates need to be within ±1. Figure 4B In this context, since the center of D10 is located at (1 / 3, 0) on the pupil coordinates when the POx coordinate of D1-2 becomes -1, the spacing P of the periodic pattern 11 is P = (3 / 2) × (λ / NA). Therefore, the spacing P of the periodic pattern 11 needs to satisfy equation (1):

[0072] P>(3 / 2)×(λ / NA)...(1)

[0073] In addition, Figure 4A and 4B In the example shown, the adjuster AD adjusts the illumination optical system 1 such that the σ value at the center position of each of the poles D1 and D2 included in the light intensity distribution formed in the pupil region 21 of the illumination optical system 1 is equal to or less than 1 / 3. In another viewpoint, the adjuster AD can be configured to adjust the illumination optical system 1 such that, let r be the radius of the pupil region 21 of the illumination optical system 1, the center position of each of the poles D1 and D2 included in the light intensity distribution is located within a range of r / 3 or less from the origin of the pupil region 21.

[0074] Figure 22A Another example of the light intensity distribution (effective light source distribution) of the exposure light in the pupil region 21 of the illumination optical system 1 of the exposure apparatus EXP according to the first embodiment is schematically shown. σx and σy are pupil coordinates indicating the position in the pupil region 21, and the two coordinate axes are parallel to the X-axis and Y-axis, respectively. The origin of the pupil coordinates is matched with the optical axis of the illumination optical system 1. Figure 22A An example of dipole illumination is shown, with each of D1 and D2 being an indicator pole. Poles D1 and D2 are arranged in positions symmetrical with respect to the σy axis (Y-axis).

[0075] Figure 22B This schematically illustrates what was provided in the original version 2. Figure 3 The periodic pattern 11 shown is Figure 22A The light intensity distribution shown (dipole illumination) is the light intensity distribution formed in the pupil region 31 of the projection optical system 4 by multiple diffracted beams from the periodic pattern 11 during illumination. POx and POy are pupil coordinates indicating positions in the pupil region 31, and the two coordinate axes are parallel to the X-axis and Y-axis, respectively. The origin of the pupil coordinates is matched with the optical axis of the projection optical system 4. D10 indicates the 0th order diffracted light from pole D1. D1-1 indicates the -1st order diffracted light from pole D1. D1-2 indicates the -2nd order diffracted light from pole D1. D1-3 indicates the -3rd order diffracted light from pole D1.

[0076] Despite Figure 22B Although not shown in the diagram, the diffracted light from pole D2 also enters the pupil region 31 of the projection optical system 4. More specifically, the 0th-order diffracted light D20 from pole D2 enters the position D1-3. Additionally, the +1st-order diffracted light D21 from pole D2 enters the position D1-2. Furthermore, the +2nd-order diffracted light D22 from pole D2 enters the position D1-1. The +3rd-order diffracted light D23 from pole D2 enters the position D10.

[0077] Next, the reason why the depth of focus increases due to the combination of illumination conditions, which include multiple diffracted beams of second-order or higher-order diffracted light forming a line-symmetric light intensity distribution in the pupil region of the projection optics system 4, and FLEX exposure will be described. Figure 6A and 6B It shows the use of Figure 5A The periodic pattern and effective light source used in the calculations shown execute the light intensity distribution formed during normal exposures rather than FLEX exposures. Figure 6A and 6B In this diagram, the value of F indicates the amount of defocus. For example, F = 0 shows the light intensity distribution obtained when the defocus is 0 (i.e., the optimal focal plane). F = 3.6 shows the light intensity distribution obtained when the defocus is 3.6 μm. Figure 6A and 6B The results obtained by changing the defocus amount by 0.6 μm spacing are shown. Figure 6A and 6B The x-coordinate of each graph in the diagram is... Figure 5A The horizontal axis is similar, and represents the light intensity distribution within a range of ±400 nm corresponding to one period of the pattern when the center of the transmissive portion S of the periodic pattern 11 is set at 0.

[0078] As from Figure 6A and 6B As can be seen, a similar light intensity distribution appears periodically with a period of 2.4 μm. Therefore, by averaging the light intensity distribution, which changes periodically with the amount of defocus, within a range corresponding to integer multiples of the period, we can obtain... Figure 5A The optical image shown exhibits a light intensity distribution that remains almost unchanged due to defocus. Here, in the first embodiment, such averaging is achieved using scanning exposure via the FLEX method. Figure 6A and 6B In this context, the light intensity distribution differs slightly between F=0.6 and F=3.0, and also slightly between F=1.2 and F=3.6. In this way, the intensity distributions of two lights within the same phase are slightly different from each other. This is because... Figure 4A The poles in the effective light source shown are not points but have appropriate radii (e.g., 0.05 when converted to σ values).

[0079] Next, the relationship between the spacing P of the periodic pattern 11, the wavelength λ of the exposure light, and the optimal defocus range (FLEX amount) for averaging via FLEX exposure will be described. (Refer to the above reference...) Figure 6A and 6B As described, the optical image of the periodic pattern 11 changes periodically according to the amount of defocus. Therefore, the calculation of the optical image of the periodic pattern 11 is as follows: Figure 4BThe period of the optical image formed by the line-symmetric diffraction light distribution in the pupil range 31 of the projection optical system 4 shown changes according to the defocus amount.

[0080] Since there is no phase difference due to defocus between the two diffracted beams at line-symmetrical positions in the pupil region 31 from the projection optical system 4, the light intensity distribution generated by the two diffracted beams does not change due to the change in the amount of defocus. Figure 4B In the example shown, the combinations of D10 and D1-1, and D11 and D1-2, correspond to this condition. On the other hand, each of the combinations of D10 and D11, and D11 and D1-1, is not a combination of line-symmetric positions within the pupil region 31. Therefore, a phase difference arises due to the change in defocus amount, and the light intensity distribution changes accordingly. The phase difference between the diffracted beams changes due to defocus, and the phase difference becomes zero at a predetermined defocus amount. The interval of the defocus amount at which the phase difference becomes zero is a period PP, and the shape of the light intensity distribution changes periodically due to the change in defocus amount.

[0081] exist Figure 4B In the example shown, D10 and D1-1 are arranged at line-symmetrical positions within the pupil region 31, and D11 and D1-2 are arranged at line-symmetrical positions within the pupil region 31. Therefore, the phase difference between D10 and D11 can be calculated. Let λ D10 and λ D11 These are the wavelength components of D10 and D11 along the optical axis, respectively.

[0082] λ D10 =λ / (1–λ 2 / P 2 / 4) 1 / 2

[0083] λ D11 =λ / (1–9×λ) 2 / P 2 / 4) 1 / 2

[0084] Here, the period PP is given by equation (2):

[0085] PP = λ D10 ×λ D11 / (λ D11 -λ D10 )

[0086] =λ / [(1–λ 2 / P 2 / 4) 1 / 2 -(1–9×λ 2 / P 2 / 4) 1 / 2...(2)

[0087] By substituting P = 800nm ​​and wavelength λ = 248nm into equation (2), we obtain PP = 2417nm. Therefore, as mentioned above... Figure 6A and 6B As described earlier, the light intensity distribution changes periodically with a defocusing amount of approximately 2.4 μm. Therefore, by averaging the light intensity distribution over a range of integer multiples of the period PP defined by equation (2), an image with a small change relative to the change in defocusing amount is formed.

[0088] When the depth of focus is increased, the depth of focus is maximized by performing FLEX exposures in which the amount of defocus is varied within a range corresponding to an integer multiple of the period PP calculated from the spacing P of the periodic pattern and the wavelength λ of the exposed light according to equation (2).

[0089] On the other hand, a small distance Z1 (FLEX amount) that represents the range of defocusing amount in the FLEX method is advantageous in simplifying the arrangement of the exposure device EXP. Therefore, the distance Z1 is preferably given by equation (2'):

[0090] Z1=λ / [(1–λ 2 / P 2 / 4) 1 / 2 -(1–9×λ 2 / P 2 / 4) 1 / 2 ...(2')

[0091] Even when the distance Z1 is 70% of the distance Z1 given by equation (2'), the depth of focus increases, so the distance Z1 is not necessarily equal to the period PP.

[0092] Figure 7A The light intensity distribution (effective light source distribution) of the exposure light in Example 2 is schematically shown in the pupil region 22 of the illumination optical system 1 of the exposure apparatus EXP according to the first embodiment. Figure 7A In the example shown, rectangular poles D3 and D4 are defined, with their widths set small to achieve an averaging effect through FLEX exposure, but their lengths are long along the σy-axis because their position along the σy-axis does not affect imaging in the periodic direction. Let P be... Figure 3 Given the spacing of the periodic pattern 11 shown, the coordinates of the center of D3 and D4 in the σx-axis direction are ±λ / (2×P×NA). Figure 7B This schematically illustrates when the periodic pattern 11 is... Figure 7A The light intensity distribution (diffraction distribution) formed in the pupil region 32 of the projection optical system 4 under extreme D3 illumination is shown. Figure 7BAlthough not shown in the diagram, the diffracted light from pole D4 also enters the pupil region 32 of the projection optical system 4. More specifically, the 0th-order diffracted light D40 from pole D4 enters the position D3-1. Additionally, the +1st-order diffracted light D41 from pole D4 enters the position D30, and the -1st-order diffracted light D4-1 from pole D4 enters the position D3-2. Furthermore, the +2nd-order diffracted light D42 from pole D4 enters the position D31. Therefore, as in Example 1, the effect of increasing the depth of focus through FLEX exposure can be achieved.

[0093] The difference between Example 2 and Example 1 is that all the 0th-order diffracted light D30 and all the -1st-order diffracted light D3-1 enter the pupil region 32, but a portion of the +1st-order diffracted light D31 and a portion of the -2nd-order diffracted light D3-2 do not enter the pupil region 32 and do not contribute to image formation. Therefore, the light intensity distribution formed near the image plane in Example 2 is different from that in Example 1. However, the effect of increasing the depth of focus through FLEX exposure in Example 2 is similar to that in Example 1. In Example 2, the area of ​​the pole (effective light source) in the pupil region of the illumination optics system is larger than the area in Example 1. This is advantageous in terms of improving illuminance and illuminance uniformity.

[0094] Figure 8 The illustration shows the periodic pattern 12 to be used in Example 3, which is used in the pupil region 22 of the illumination optics system 1 of the exposure apparatus EXP according to the first embodiment. The original 2 used in Example 3 includes the two-dimensional periodic pattern 12. The two-dimensional periodic pattern 12 has a periodicity of spacing P2 in the X direction and also has a periodicity of spacing P2 in the Y direction.

[0095] Figure 9 The light intensity distribution (effective light source distribution) of the exposure light in Example 3 is schematically shown in the pupil region 23 of the illumination optical system 1 of the exposure apparatus EXP according to the first embodiment. Figure 9 The light intensity distribution shown can be used Figure 8 The periodic pattern 12 shown is used in substrate exposure. When using... Figure 8 When the original 2 of the periodic pattern 12 shown in the example exposes the substrate 7, the adjuster AD can adjust the illumination optical system 1 based on the information of the periodic pattern 12, so that a pupil region 23 of the illumination optical system 1 is formed. Figure 9 The light intensity distribution is shown as an example.

[0096] The light intensity distribution formed in the pupil region 23 includes poles D5, D6, D7, and D8. The absolute values ​​of σx and σy (σx = σy) at the center of each of poles D5, D6, D7, and D8 can be λ / (2 × P2 × NA). The illumination optical system 1 is adjusted so that the light intensity distribution described above is formed in the pupil region 23, and FLEX exposure can be performed while using the distance Z1 in the optical axis direction obtained by substituting P2 into P in equation (2) as the FLEX amount. Thus, in the case of using a two-dimensional periodic pattern, the effect of increasing the depth of focus can also be obtained as in the case of using a one-dimensional periodic pattern.

[0097] Figure 10 The light intensity distribution (effective light source distribution) of the exposure light in the pupil region 24 of the illumination optical system 1 of the exposure apparatus EXP according to the first embodiment is schematically shown in Example 4. In Example 4, the light intensity distribution obtained by adding pole D9 to the light intensity distribution including poles D3 and D4 in Example 2 is formed in the pupil region 24 of the illumination optical system 1. Poles D3 and D4 are separated from each other and arranged symmetrically with respect to lines parallel to the periodic direction orthogonal to the periodic pattern, and they contribute to increasing the depth of focus. On the other hand, pole D9 is arranged on the optical axis of the illumination optical system 1. Pole D9 does not contribute to increasing the depth of focus, but it can help improve the image quality of the optimal focal plane and its vicinity.

[0098] Figures 11A to 11C Each of the figures shows the light intensity of the D9 electrode and... Figure 10 The change in light intensity distribution near the image plane is obtained when the ratio of the light amount in the entire light intensity distribution in the pupil region 24 of the illumination optical system 1 shown changes. Here, using Figure 3 The periodic pattern 11 shown is calculated while setting the linewidth S of the transmission portion to 200 nm and the spacing P to 800 nm. Figures 11A to 11C The light intensity distribution in each of them. Figure 11A An example is shown where the ratio of the light intensity at pole D9 to the light intensity of the entire light intensity distribution in pupil region 24 is 0. Figure 11B An example of this ratio of 15% is shown, and Figure 11C An example of this ratio being 30% is shown. Figure 11A As shown, when the ratio of light intensity at pole D9 is 0, the light intensity distribution near the image plane remains almost unchanged when the defocusing amount is changed from 0 μm to 2.7 μm. On the other hand, as... Figure 11B As shown, when the light intensity ratio of the extreme D9 is set to 15%, the light intensity in the central portion of the optimal focus (defocus = 0 μm) increases, but the image performance changes as the defocus intensity is altered. Additionally, as... Figure 11CAs shown, when the light intensity ratio of the extreme D9 is set to 30%, the light intensity in the central portion of the optimal focus (defocus = 0 μm) is further increased, but the change in image performance according to the change in defocus is further increased.

[0099] Here, increasing the amount of light from pole D9 relative to the overall light intensity distribution in the pupil region 24 means decreasing the ratio of the light amounts from poles D3 and D4 to the overall light intensity distribution in the pupil region 24. Conversely, decreasing the amount of light from pole D9 relative to the overall light intensity distribution in the pupil region 24 means increasing the ratio of the light amounts from poles D3 and D4 to the overall light intensity distribution in the pupil region 24. Increasing the ratio of the light amounts from poles D3 and D4 to the overall light intensity distribution in the pupil region 24 helps to increase the depth of focus. On the other hand, decreasing the ratio of the light amounts from poles D3 and D4 to the overall light intensity distribution in the pupil region 24 helps to improve image performance in optimal focusing. From the viewpoint of improving the depth of focus, the ratio of the light amounts from poles D3 and D4 (at least two poles spaced apart from each other and arranged symmetrically with respect to lines parallel to orthogonal to the periodic direction) to the overall light intensity distribution in the pupil region 24 is preferably equal to or greater than 50%. Figure 10 In the example shown, the center of pole D9 is aligned with the optical axis, but the center of pole D9 can be positioned, for example, at a location on the σy axis where σy≠0.

[0100] Figures 12A to 12C Each of them shows when Figure 4A The change in light intensity distribution near the image plane is obtained when the sizes of poles D1 and D2, included in the light intensity distribution of the pupil region 21 of the illumination optical system 1 shown, are changed. Here, using Figure 3 The periodic pattern 11 shown is calculated while setting the linewidth S of the transmission portion to 200 nm and the spacing P to 800 nm. Figures 12A to 12C The light intensity distribution in each of them. The focal plane is set to shift (defocus) from the optimal focal plane 9 of the projection optics system 4 from 0 μm to 2.7 μm in 0.3 μm intervals. The radii of each of poles D1 and D2 are set to 0.05, 0.10, or 0.15 in terms of values ​​converted to σ (pupil coordinates). Figure 12A The results are shown when the radius of each of poles D1 and D2 is 0.05. Figure 12B The results are shown when the radius of each of poles D1 and D2 is 0.10, and Figure 12C The results are shown when the radius of each of poles D1 and D2 is 0.15. Changing the radius of each of poles D1 and D2 is equivalent to changing the width (diameter) of each of poles D1 and D2 in the periodic direction of the periodic pattern.

[0101] From the viewpoint of increasing focal depth, the radius of each of poles D1 and D2 is preferably small. From the viewpoint of improving illuminance uniformity on the substrate, the radius of each of poles D1 and D2 is preferably large. In other words, from the viewpoint of increasing focal depth, the width of each of poles D1 and D2 in the periodic direction of the periodic pattern is preferably small, and from the viewpoint of improving illuminance uniformity on the substrate, the width of each of poles D1 and D2 in the periodic direction of the periodic pattern is preferably large. The width of each of poles D1 and D2 in the periodic direction of the periodic pattern is preferably equal to or less than 0.3, for example, in terms of the value converted to σ.

[0102] In each of the following embodiments, another implementation of the FLEX method will be described. Note that matters not mentioned in each of the following embodiments may follow the first embodiment.

[0103] Figure 13 The illustration shows substrate movement during FLEX exposure in the exposure apparatus EXP according to the second embodiment. The exposure apparatus EXP according to the second embodiment can have... Figure 1 The arrangement of the exposure apparatus EXP according to the first embodiment shown is similar, but the exposure method is different from that in the first embodiment. Figure 13 The exposure apparatus EXP shown according to the second embodiment is a step-repeating sequential moving exposure apparatus.

[0104] In the exposure apparatus EXP according to the second embodiment, exposure of the substrate 7 is performed while the original 2 and the substrate 7 are stationary. Therefore, in the exposure apparatus EXP according to the second embodiment, as... Figure 13 As illustrated in the diagram, FLEX exposure is performed by simultaneously exposing the substrate 7 while moving it at a constant speed within a distance Z1 from a first position P1 in the Z direction to a second position P2 in the Z direction.

[0105] The second embodiment differs from the first embodiment only in the FLEX exposure method of the substrate 7, and the setting of the illumination conditions for increasing the depth of focus and the effect of increasing the depth of focus are exactly the same as in the first embodiment. In the second embodiment, if the spacing P of the periodic pattern of the original is the same as in the first embodiment, then the amount of movement Z1 of the substrate 7 in the optical axis direction has the same value as in the first embodiment.

[0106] Figure 14The movement of the substrate during FLEX exposure in the exposure apparatus EXP according to the third embodiment is illustrated. The movement of the substrate during FLEX exposure in the exposure apparatus EXP according to the third embodiment is similar to that in the exposure apparatus EXP according to the second embodiment. In the third embodiment, the controller CN controls the exposure of the substrate 7 such that the projection area of ​​the substrate 7 is exposed in a first focused state (or, a first defocused state) and a second focused state (or, a second defocused state). In the first focused state (first defocused state), the projection area is exposed at half the normal exposure amount. Then, the first focused state (first defocused state) changes to the second focused state (second defocused state), and the projection area is further exposed at half the normal exposure amount.

[0107] Let Z2 be the distance (FLEX) between the position P1' of the substrate 7 in the first focused state (first defocused state) and the position P2' of the substrate 7 in the second focused state (second defocused state) along the optical axis (Z direction) of the projection optical system 4. Then, there exists a relationship expressed by Z2 = Z1 / 2. That is, the distance Z2 can be given by equation (3):

[0108] Z2=λ / [(1–λ 2 / P 2 / 4) 1 / 2 -(1–9×λ 2 / P 2 / 4) 1 / 2 ] / 2...(3)

[0109] The following describes increasing the depth of focus using the FLEX method performed by the exposure apparatus EXP according to the third embodiment. Here, the method using… Figure 3 The periodic pattern 11 shown and Figure 4A An example of an effective light source is shown. When no FLEX exposure is performed, the previously described light source forms near the image plane. Figure 6A and 6B The light intensity distribution shown is illustrated in the first embodiment. Figure 6A and 6BThe light intensity distribution shown is averaged (integrated) over a width of 2.4 μm in the Z-direction (optical axis direction). This is because in the first embodiment, since FLEX exposure is performed simultaneously with the tilted substrate 7, the light intensity distribution is averaged within a range of ±1.2 μm centered on the position of the set focal plane. Conversely, in the third embodiment, exposure is performed at two Z-direction positions separated by a distance Z2 in the Z-direction (optical axis direction). The average value of the periodically changing light intensity distribution can be obtained by calculating the average value of the light intensity distribution at the two Z-direction positions separated by a distance corresponding to half of the period PP. This yields a result similar to that obtained by averaging the light intensity distribution over a range corresponding to the entire period.

[0110] Figure 15 It shows how to get from Figure 6A and 6B The light intensity distribution shown is obtained by selecting two light intensity distributions with a defocus difference of 1.2 μm from the multiple light intensity distributions shown and averaging the selected two light intensity distributions. For example, the light intensity distribution at a defocus of 0 μm can be obtained by averaging the light intensity distributions at a defocus of -0.6 μm and a defocus of +0.6 μm. The light intensity distribution at a defocus of 6 μm can be obtained by averaging the light intensity distributions at a defocus of 0 μm and a defocus of -1.2 μm. Figure 15 The light intensity distribution shown is... Figure 5A The light intensity distribution shown is similar. Therefore, it can be understood that an effect of increasing the depth of focus can be achieved.

[0111] Figure 16 The arrangement of the exposure apparatus EXP according to the fourth embodiment is schematically shown. In the fourth embodiment, FLEX exposure is performed by changing the amount of defocus by changing the center wavelength of the exposure light.

[0112] The exposure apparatus EXP according to the fourth embodiment may include a light source 41 that supplies exposure light to the illumination optical system 1. Generally, examples of light sources for the exposure apparatus are mercury lamps using g-line (436 nm) or i-line (365 nm) light from mercury, and excimer lasers using KrF (248 nm) or ArF (193 nm) light. In exposure apparatuses using mercury lamps as light sources, the light source is generally arranged inside the illumination optical system. In exposure apparatuses using excimer lasers as light sources, the light source is generally arranged outside the illumination optical system.

[0113] In the fourth embodiment, an excimer laser is used as the light source 41 because the function of changing the wavelength of the exposure light is required. The half-width at half maximum (WWHM) of the emission spectrum of the excimer laser is generally between 100 and 300 nm. However, by arranging narrow-band units in the laser resonator of the light source 41, the bandwidth can be narrowed to have a WWHM of 1 pm or less. In addition, in order to correct for changes in optical characteristics caused by the exposure history of the projection optics system and changes in optical characteristics caused by atmospheric pressure, the light source 41 also has the function of controlling the center wavelength. The controller CN has the function of controlling the wavelength of the exposure light generated by the light source 41.

[0114] Figure 17 An exemplary illustration is shown of a FLEX exposure method in an exposure apparatus EXP according to a fourth embodiment. Figure 17 In the diagram, the horizontal axis represents time, and the vertical axis represents the center wavelength of the exposure light generated by the light source 41. "One projection exposure period" is the period during which scanning exposure is performed on a projection area. In the scanning exposure apparatus, a point in the projection area of ​​the substrate 7 passes through this point... Figure 2 The section between dotted lines 10a and 10b shown is exposed. Therefore, it is necessary to change the wavelength from λ0+Δλ / 2 to λ0-Δλ / 2 during the time the point passes through this section. Since the excimer laser used as the light source 41 is a pulsed laser, the center wavelength of the exposure light can be changed at equal intervals for each pulse between the two wavelengths λ0+Δλ / 2 and λ0-Δλ / 2. λ0 is the center wavelength of the exposure light generated by the light source 41 when FLEX exposure is not performed.

[0115] Let C be the axial chromatic aberration of the projection optical system 4, then the change in center wavelength Δλ corresponding to the driving amount Z1 when driving each point in the projection region of the substrate 7 in the Z direction during FLEX exposure is expressed by Δλ = Z1 / C. Here, let P be the spacing of the periodic pattern 11, and if the depth of focus is increased by averaging the change in light intensity distribution according to the wavelength change in one period, then equation (4) defining Δλ can be obtained from equation (2'). Here, λ0 is the peak wavelength of the exposed light, and λ is approximated by λ0:

[0116] Δλ=λ0 / [(1–λ0 2 / P 2 / 4) 1 / 2 -(1–9×λ0 2 / P 2 / 4) 1 / 2 ] / C...(4)

[0117] refer to Figure 18A and 18BThe following describes FLEX exposure in the exposure apparatus EXP according to the fifth embodiment. The exposure apparatus EXP according to the fifth embodiment may have the same characteristics as... Figure 16 The arrangement is similar to that of the exposure apparatus EXP according to the fourth embodiment shown. In the fifth embodiment, instead of changing the center wavelength of the exposure light generated by the light source 41 over time, the FWHM (full width at half maximum) of the emission spectrum of the exposure light is increased. Figure 18A The emission spectrum of the exposure light generated by the light source 41 is shown when the exposure apparatus EXP according to the fifth embodiment performs a normal exposure. Figure 18B An example of the emission spectrum of the exposure light generated by the light source 41 is shown when the exposure apparatus EXP according to the fifth embodiment performs a FLEX exposure. Figure 18A and 18B In each of the graphs, the horizontal axis represents the wavelength, and the vertical axis represents the spectral intensity. In FLEX exposure, the controller CN controls the light source 41 such that the FWHM of the emission spectrum becomes Δλ. By setting the FWHM of the emission spectrum to the value of Δλ, an effect similar to that in the FLEX exposure of the fifth embodiment can be obtained without changing the wavelength. The desired Δλ is given by equation (4) to satisfy the condition for increasing the depth of focus to its maximum value.

[0118] refer to Figure 19 The following describes FLEX exposure in the exposure apparatus EXP according to the sixth embodiment. The exposure apparatus EXP according to the sixth embodiment may have the same characteristics as... Figure 16 The arrangement shown is similar to that of the exposure apparatus EXP according to the fourth embodiment. In the sixth embodiment, the center wavelength of the exposure light generated by the light source 41 is changed in a manner different from that in the fourth embodiment. Figure 19 In the diagram, the horizontal axis represents time, and the vertical axis represents the center wavelength of the exposure light generated by the light source 41. As the exposure light generated by the light source 41, beams with two center wavelengths, λ0 + Δλ2 / 2 and λ0 - Δλ2 / 2, are used alternately. λ0 is the center wavelength of the exposure light generated by the light source 41 when no FLEX exposure is performed. Δλ2 is the difference between the two center wavelengths, used to obtain an effect similar to that in a FLEX exposure where the FLEX amount is set to a distance Z2 as described in the third embodiment.

[0119] Let C be the axial chromatic aberration of the projection optical system 4, then the wavelength difference Δλ2 can be given by equation (5) obtained from equation (3):

[0120] Δλ2=Z2 / C

[0121] =λ0 / [(1–λ0) 2 / P 2 / 4) 1 / 2 -(1–9×λ02 / P 2 / 4) 1 / 2 ] / 2 / C...(5)

[0122] exist Figure 19 In the example shown, the exposure beam with two wavelengths oscillates alternately for each pulse. However, in a step-repeating exposure apparatus, the substrate can be exposed while changing the wavelength between the first and second halves of the exposure.

[0123] Figure 20 A modification of the sixth embodiment is shown. (Refer to...) Figure 19 In the described method, the light source 41 alternately generates exposure beams with two center wavelengths: λ0 + Δλ² / 2 and λ0 - Δλ² / 2. However, as... Figure 20 As shown, exposure beams with two center wavelengths can be generated simultaneously. The interval between the two center wavelengths is Δλ2, and the center between the two center wavelengths is λ0.

[0124] In each of the first to third embodiments, FLEX exposure is achieved by driving the substrate such that each point in the projection area of ​​the substrate is exposed in two or more focused states (or two or more defocused states). In each of the fourth to sixth embodiments, FLEX exposure is achieved by changing the wavelength of the exposure light such that each point in the projection area of ​​the substrate is exposed in two or more focused states (or two or more defocused states). In the seventh embodiment, the controller CN performs the operation of driving the substrate and changing the wavelength of the exposure light such that each point in the projection area of ​​the substrate is exposed in two or more focused states (or two or more defocused states).

[0125] The operation of driving the substrate may include continuously changing the position of the substrate. Alternatively, the operation of driving the substrate may include changing a first focused state (or, a first defocused state) to a second focused state (or, a second defocused state) to perform exposure in the second focused state (second defocused state) after exposure in the first focused state (first defocused state).

[0126] The controller CN can perform a first operation and a second operation on a projection area, such that each point in the projection area of the substrate is exposed in two or more focusing states (or, two or more defocusing states). The first operation can be an operation of exposing the projection area while setting the position of the substrate 7 in the optical axis direction of the projection optical system 4 to a first position and setting the wavelength of the exposure light to a first wavelength. The second operation can be an operation of exposing the projection area while setting the position of the substrate 7 in the optical axis direction of the projection optical system 4 to a second position different from the first position and setting the wavelength of the exposure light to a second wavelength different from the first wavelength.

[0127] In the method of changing the center wavelength of the light source 41, the amount of change in the center wavelength between pulses is Δλ. Since the oscillation frequency of the current mainstream excimer laser is 4 KHz, the pulse interval is 0.25 msec. The wavelength that can be changed during 0.25 msec while maintaining the accuracy of the center wavelength is limited.

[0128] Reference Figure 21A and 21B , the seventh embodiment will be described. Figure 21A Schematically shows the driving amount (distance Z3) of the substrate 7 in the FLEX method performed by the exposure apparatus EXP according to the seventh embodiment. Figure 21B Shows the amount of change (Δλ3) in the wavelength of the exposure light in the FLEX method performed by the exposure apparatus EXP according to the seventh embodiment. The condition for maximizing the depth of focus when exposing the substrate 7 at two positions (the first position P1" and the second position P2") in the optical axis direction can be given by equation (3). The condition for maximizing the depth of focus when exposing the substrate 7 using two wavelengths can be given by equation (5). If the maximum amount of change in the wavelength of the exposure light in the FLEX method is Δλ3, where Δλ3 < Z2 / C, then the depth of focus cannot be maximized.

[0129] When the projection optical system 4 is a refractive system, due to axial chromatic aberration, for a long wavelength (i.e., λ0 + Δλ3 / 2), the image plane moves in the -Z axis direction, and for a short wavelength (i.e., λ0 - Δλ3 / 2), the image plane moves in the +Z axis direction. To increase the amount of movement of the image plane from the substrate 7, it is advantageous to set the wavelength to λ0 + Δλ3 / 2 at the first position P1" close to the projection optical system 4 and set the wavelength to λ0 - Δλ3 / 2 at the second position P2" far from the projection optical system 4. In this case, let C be the value of the axial chromatic aberration of the projection optical system 4, then the depth of focus can be maximized when equation (6) is satisfied:

[0130] Z3 + Δλ3 × C = Z2...(6)

[0131] In each of the above embodiments, when performing a FLEX exposure on a projection area within a predetermined defocus range, the predetermined defocus range can be divided into multiple smaller ranges, and a FLEX exposure can be performed on each smaller range.

[0132] (The method of manufacturing the item)

[0133] A method for manufacturing a semiconductor device (such as a photoelectric conversion device for memory or an image sensor) using a representative exposure apparatus according to this embodiment will be described. The exposure apparatus according to this embodiment is preferably used in a semiconductor device manufacturing method that includes a thick-film process. A thick-film process is a process that requires a thick resist film. An example of a thick-film process is the pixel separation step in an image sensor (photoelectric conversion device).

[0134] Reference Figures 23A to 23C This describes the pixel separation process in the manufacturing steps of an image sensor. In step S101, a semiconductor substrate 101 having a first surface S1 and a second surface S2 as opposing surfaces is prepared. The semiconductor substrate 101 is typically a silicon substrate or a silicon layer. Next, in step S102, an insulating film (e.g., a silicon oxide film) 102 is formed on the first surface S1 of the semiconductor substrate 101.

[0135] Next, in step S103, a photoresist 103 is applied to the first surface S1 of the semiconductor substrate 101, more specifically to the insulating film 102 on the first surface S1 of the semiconductor substrate 101. Furthermore, in step S104, as described in the above embodiments, an exposure operation is performed such that each point in the projection area of ​​the semiconductor substrate 101 is exposed in two or more focused states (or two or more defocused states) while a predetermined light intensity distribution is formed in the pupil plane of the projection optical system. This forms a pattern image in the photoresist 103, and grooves 104 are formed via etching or the like. By performing the exposure operation with increased focal depth, a pattern image with a desired shape can be formed in the photoresist 103.

[0136] Next, in step S105, the semiconductor substrate 101 is etched by a dry etching method or the like, thereby forming a groove 105 on the first surface S1 side of the semiconductor substrate 101. In order to protect the first surface S1 of the semiconductor substrate 101 during this etching, it is necessary to apply a thick resist 103.

[0137] Then, in step S106, the resist 103 is removed, and ions are implanted into the semiconductor substrate 101 through the groove 105, thereby forming a getter region 106. That is, in step S106, while the area of ​​the first surface S1 of the semiconductor substrate 101 other than the area with the groove 105 is masked by the insulating film 102, ions are implanted into the semiconductor substrate 101 through the groove 105. The getter region 106 may include a first portion located below the bottom of the groove 105 and a second portion located on the side of the groove 105. As an example, the concentration of Group 14 elements in the first portion is higher than the concentration of Group 14 elements in the second portion. If the semiconductor substrate 101 is a silicon substrate, then the ions may be Group 14 element ions other than silicon. An ion implantation device may be used to implant ions. The acceleration energy used for ion implantation can be determined such that the ions are implanted without passing through the insulating film 102, which serves as a hard mask, and do not reach the semiconductor substrate 101. For example, if the thickness of the insulating film 102 is 300 nm and the acceleration energy is about 20 keV when ions are implanted, then ions will not be implanted through the insulating film 102.

[0138] If the semiconductor substrate 101 is made of a silicon substrate, then the material for forming the ions to be implanted into the semiconductor substrate 101 in step S106 is preferably carbon. Carbon-containing hydrocarbon molecules can be used. If the semiconductor substrate 101 is made of a silicon substrate, then the material for forming the ions to be implanted into the semiconductor substrate 101 in step S106 can be germanium, tin, or zinc. If carbon, germanium, tin, or zinc ions are implanted into the silicon substrate used as the semiconductor substrate 101, then local strain is applied to the silicon substrate, and this local area serves as a gettering region. By implanting ions into the semiconductor substrate 101 through the groove 105, a gettering region 106 can be formed at a deep location in the semiconductor substrate 101 even with relatively low acceleration energy.

[0139] Next, in step S107, the insulating film 102 is removed. In step S108, an insulating film (e.g., a silicon nitride film) 107 is formed in the groove 105 and on the first surface S1 of the semiconductor substrate 101 using a film formation method such as depressurized CVD, so that an insulator is arranged or filled in the groove 105. Subsequently, in step S109, the portion of the insulating film 107 present on the first surface S1 of the semiconductor substrate 101 is removed using a CMP method or the like. Thus, the portion of the insulating film 107 present in the groove 105 is left as a pixel separation portion 108 arranged or filled in the groove 105.

[0140] Note that steps S108 and S109 are not required. If steps S108 and S109 are not performed, then the groove 105 is left as an air gap that can be used as a pixel separation portion. The pixel separation portion 108 disposed in the groove 105 does not need to perfectly fill the groove 105, and an air gap may exist in the groove 105. The pixel separation portion 108 may be formed only of an insulator, but may be formed by a combination of an insulator and a non-insulator (semiconductor or conductor). In this case, to avoid contact between the non-insulator and the semiconductor substrate 101, the insulator may be disposed between the non-insulator and the semiconductor substrate 101.

[0141] As described above, the pixel separation portion 108 is formed via a first forming step of forming a groove 105 in the semiconductor substrate 101 and a second forming step of forming a pixel separation portion 108 in the groove 105. Subsequently, charge accumulation regions, gate electrodes, etc., are formed in the regions between the plurality of pixel separation portions, thereby forming an image sensor. The method for manufacturing an article according to this embodiment is superior to conventional methods in at least one of the following aspects: article performance, quality, productivity, and production cost.

[0142] Other embodiments

[0143] Embodiments of the present invention can also be implemented by a computer of a system or apparatus that reads and executes computer-executable instructions (e.g., one or more programs) recorded on a storage medium (which may also be more fully referred to as a 'non-transitory computer-readable storage medium') to perform one or more functions of the above embodiments and / or includes one or more circuits (e.g., application-specific integrated circuits (ASICs)) for performing one or more functions of the above embodiments, and by a method performed by a computer of the system or apparatus by, for example, reading and executing computer-executable instructions from the storage medium to perform one or more functions of the above embodiments and / or controlling one or more circuits to perform one or more functions of the above embodiments. The computer may include one or more processors (e.g., a central processing unit (CPU), a microprocessor unit (MPU)) and may include separate computers or networks of separate processors to read and execute computer-executable instructions. The computer-executable instructions may be provided to the computer, for example, from a network or storage medium. The storage medium may include, for example, a hard disk, random access memory (RAM), read-only memory (ROM), storage devices for distributed computing systems, optical discs (such as CDs, DVDs, or Blu-ray discs). TM One or more of the following: flash memory devices, memory cards, etc.

[0144] The embodiments of the present invention can also be implemented by providing software (programs) that perform the functions of the above embodiments to a system or device via a network or various storage media, and the computer or central processing unit (CPU) or microprocessor unit (MPU) of the system or device reads out and executes the program.

[0145] While the invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be given the broadest interpretation in order to cover all such modifications and equivalent structures and functions.

Claims

1. An exposure apparatus comprising an illumination optical system configured to illuminate a original including a periodic pattern and a projection optical system configured to form an image of the original on a substrate, the apparatus comprising a controller configured to cause light from the illumination optical system to be obliquely incident on the original so that a light intensity distribution including four high light intensity portions is formed in a pupil region of the projection optical system by a plurality of diffracted light beams, the light intensity distribution is line-symmetrical with respect to a straight line passing through an origin of the pupil region of the projection optical system and orthogonal to a period direction of the periodic pattern, the plurality of diffracted light beams include diffracted light lower than 2nd order and diffracted light not lower than 2nd order from the periodic pattern, and the controller is configured to control exposure of the substrate based on an interval of a defocus amount so that each point in a projection area of the substrate is exposed in not less than two focus states, a phase difference in a combination of two lights among four lights from the four high light intensity portions becomes zero at the defocus amount, wherein the phase difference occurs due to a change in the defocus amount.

2. The apparatus according to claim 1, further comprising an adjuster configured to adjust the illumination optical system so that a light intensity distribution is formed in a pupil region of the projection optical system.

3. The apparatus according to claim 2, wherein the adjuster adjusts the illumination optical system so that the light intensity distribution formed in the pupil region of the projection optical system includes poles arranged on the straight line.

4. The apparatus according to claim 2, wherein the adjuster adjusts the illumination optical system so that a second light intensity distribution is formed in a pupil region of the illumination optical system, the second light intensity distribution includes at least two second high light intensity portions, the at least two second high light intensity portions are arranged line-symmetrically with respect to a line parallel to a direction orthogonal to the period direction and separated from each other, and each of the at least two second high light intensity portions has a higher light intensity than a remaining portion in the second light intensity distribution, and wherein the plurality of diffracted light beams are formed by light beams from the at least two second high light intensity portions in the pupil region of the illumination optical system.

5. The apparatus according to claim 4, wherein letting r be a radius of a pupil region of the illumination optical system, the adjuster adjusts the illumination optical system so that a σ value of a center position of each of the at least two second high light intensity portions included in the light intensity distribution formed in the pupil region of the illumination optical system is not more than r / 3.

6. The apparatus according to claim 4, wherein a ratio of a light amount of the at least two second high light intensity portions in the pupil region of the illumination optical system to a light amount of the entire light intensity distribution formed in the pupil region of the illumination optical system is not less than 50%.

7. The apparatus according to claim 4, wherein A value obtained by converting a width of each of the at least two second high light intensity portions included in the light intensity distribution formed in a pupil region of the illumination optical system in the periodic direction into a sigma value is not more than 0.

3.

8. The apparatus according to claim 1, wherein Let P be a pitch of the periodic pattern in the periodic direction, λ be a wavelength of exposure light, and NA be a numerical aperture of the projection optical system, then the illumination optical system allows the plurality of diffracted light beams to form a light intensity distribution including the four high light intensity portions in a pupil region of the projection optical system if P > (3 / 2) x (λ / NA) is satisfied.

9. The apparatus according to claim 1, wherein The controller controls exposure of the substrate so that scanning exposure of the substrate is performed in a state where a normal line direction of a surface of the substrate is inclined with respect to an optical axis direction of the projection optical system.

10. The apparatus according to claim 9, wherein In the scanning exposure, the projection region is exposed such that any point in the projection region goes from a first focus state to a second focus state, and let Z1 be the distance in the optical axis direction between the any point in the first focus state and the any point in the second focus state, P be the pitch of the periodic pattern in the periodic direction, and λ be the wavelength of exposure light, then Z1 = λ / [(1 - λ / P) / 4] is satisfied. 2 2 1 / 2 2 2 1 / 2 ]​​​​​ 11. The apparatus according to claim 1, wherein The controller controls exposure of the substrate so that the projection area is exposed in each of a first focus state and a second focus state.

12. The apparatus according to claim 11, wherein Let Z2 be a distance between a position of the substrate in an optical axis direction of the projection optical system in the first focus state and a position of the substrate in the optical axis direction in the second focus state, P be a pitch of the periodic pattern in the periodic direction, and λ be a wavelength of exposure light, then Z2 = λ / [(1 - λ 2 / P 2 / 4) 1 / 2 - (1 - 9 x λ 2 / P 2 / 4) 1 / 2 ] / 2 is satisfied.

13. The apparatus according to claim 1, wherein A central wavelength of exposure light is continuously changed between two wavelengths, and If the two wavelengths are λ0-Δλ / 2 and λ0+Δλ / 2 and let C be a value of an axial chromatic aberration of the projection optical system, P be a pitch of the periodic pattern in the periodic direction, Δλ be a full width at half maximum of exposure light, λ0 be a peak value of the exposure light, then Δλ = λ0 / [(1 – λ0 2 / P 2 / 4) 1 / 2 - (1 – 9 × λ0 2 / P 2 / 4) 1 / 2 ] / C is satisfied.

14. The apparatus according to claim 1, wherein Let C be a value of an axial chromatic aberration of the projection optical system, P be a pitch of the periodic pattern in the periodic direction, Δλ be a full width at half maximum of exposure light, and λ0 be a peak value of the exposure light, Δλ = λ0 / [(1 – λ0 2 / P 2 / 4) 1 / 2 - (1 – 9 × λ0 2 / P 2 / 4) 1 / 2 ] / C is satisfied.

15. The apparatus according to claim 1, wherein An exposure light beam having two wavelengths is used, central wavelengths of the two wavelengths are different from each other, and If the two wavelengths are λ0-Δλ / 2 and λ0+Δλ / 2 and let C be a value of an axial chromatic aberration of the projection optical system, P be a pitch of the periodic pattern in the periodic direction, Δλ be a full width at half maximum of exposure light, λ0 be a peak value of the exposure light, then Δλ = λ0 / [(1 – λ0 2 / P 2 / 4) 1 / 2 - (1 – 9 × λ0 2 / P 2 / 4) 1 / 2 ] / 2 / C is satisfied.

16. The apparatus according to claim 1, wherein The controller performs an operation of driving the substrate and an operation of changing a wavelength of exposure light so that each point in a projection area of the substrate is exposed in not less than two focus states.

17. The apparatus according to claim 16, wherein The operation of driving the substrate includes an operation of continuously changing a position of the substrate.

18. The apparatus according to claim 1, wherein The controller performs an operation of exposing the projection area while a position of the substrate in an optical axis direction of the projection optical system is set to a first position and a wavelength of exposure light is set to a first wavelength, and an operation of exposing the projection area while the position of the substrate in the optical axis direction of the projection optical system is set to a second position and the wavelength of exposure light is set to a second wavelength, so that each point in the projection area is exposed in not less than two focus states, the second position is different from the first position, and the second wavelength is different from the first wavelength.

19. An exposure method of exposing a substrate using an illumination optical system configured to illuminate a original including a periodic pattern and a projection optical system configured to form an image of the original on the substrate, the method comprising causing light from the illumination optical system to be obliquely incident on the original so that a light intensity distribution including four high light intensity portions is formed in a pupil region of the projection optical system by a plurality of diffracted light beams, the light intensity distribution being arranged line symmetrically with respect to a straight line passing through an origin of the pupil region of the projection optical system and orthogonal to a period direction of the periodic pattern, the plurality of diffracted light beams including diffracted light lower than 2nd order and diffracted light not lower than 2nd order from the periodic pattern, and controlling exposure of the substrate based on an interval of a defocus amount so that each point in a projection region of the substrate is exposed in not less than two focus states, a phase difference in a combination of two lights among four lights from the four high light intensity portions becoming zero at the defocus amount, wherein the phase difference occurs due to a change in the defocus amount.

20. A method of manufacturing a semiconductor device, the method including forming a recess in a substrate and forming a pixel separation portion in the recess, wherein a light intensity distribution is formed in a pupil region of a projection optical system by a plurality of diffracted light beams, the projection optical system being configured to form an image of an original having a periodic pattern on the substrate, the light intensity distribution including four high light intensity portions each having a higher light intensity than the remaining portions, the light intensity distribution being arranged line symmetrically with respect to a straight line passing through an origin of the pupil region of the projection optical system and orthogonal to a period direction of the periodic pattern, the plurality of diffracted light beams including diffracted light lower than 2nd order and diffracted light not lower than 2nd order from the periodic pattern, and exposure of the substrate is controlled based on an interval of a defocus amount so that each point in a projection region of the substrate is exposed in not less than two focus states, a phase difference in a combination of two lights among four lights from the four high light intensity portions becoming zero at the defocus amount, wherein the phase difference occurs due to a change in the defocus amount.

21. A method of manufacturing a semiconductor device, the method including forming a recess in a substrate and forming a pixel separation portion in the recess, wherein forming a recess in a substrate includes an operation of exposing the substrate according to the exposure method according to claim 19.

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