JP2004207709A - Exposure method and device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid immersed type exposure method and a device which prevents imaging performance from deterioration due to the affect of polarized light, secures prescribed contrast, and forms a desired pattern. <P>SOLUTION: This exposure method immerses the surface of a body to be exposed and the final face of a projection lens system in liquid and projects the pattern to be formed on a mask on the body to be exposed by the projection lens system, when the incidence angle of light among effective light sources emitting from a part on an axis which is parallel to a repeating direction of the pattern and is orthogonal to the optical axis of the projection lens system, and inclined incidence toward a resist to the body to be exposed is θ; and when a maximum value of the angle of incidence is θ<SB>NA</SB>, the exposure method by which light, corresponding to a range of the angle of incidence θ for satisfying 90° -θ<SB>NA</SB>≤θ≤θ<SB>NA</SB>, has only an S polarized light component. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

  The present invention generally relates to various devices such as semiconductor chips such as ICs and LSIs, display devices such as liquid crystal panels, detection devices such as magnetic heads, imaging devices such as CCDs, and exposure devices used for manufacturing micropatterns used in micromechanics. More particularly, the present invention relates to a so-called immersion type exposure method and apparatus for immersing a final surface of a projection optical system and a surface of an object to be exposed in a liquid and exposing the object to be exposed through the liquid.

  When a fine semiconductor element such as a semiconductor memory or a logic circuit or a liquid crystal display element is manufactured using a photolithography (burning) technique, drawing is performed on a reticle or a mask (the terms are used interchangeably in this application). Conventionally, a reduced projection exposure apparatus that projects a circuit pattern formed on a wafer or the like by a projection optical system to transfer the circuit pattern has been used.

  The minimum dimension (resolution) that can be transferred by the reduction projection exposure apparatus is proportional to the wavelength of light used for exposure and inversely proportional to the numerical aperture (NA) of the projection optical system. Therefore, the shorter the wavelength and the higher the NA, the better the resolution. In recent years, with a demand for miniaturization of a semiconductor element, a smaller value is required for the resolution. Therefore, it is expected that the resolution will be improved by shortening the wavelength of the exposure light and increasing the NA of the projection optical system. At present, the NA of the projection optical system is accelerating, and the development of an optical system exceeding NA = 0.9 is in view.

  On the other hand, the light source of the exposure apparatus has changed from a KrF laser (wavelength: 248 nm) to an ArF laser (wavelength: 193 nm) as the wavelength becomes shorter. Currently, development is under way to realize an F2 laser (wavelength 157 nm) or EUV (13.5 nm) as the next light source.

In such a situation, liquid immersion exposure has attracted attention as a method for further improving resolution while using a light source of an ArF laser (wavelength 193 nm) or an F2 laser (wavelength 157 nm) (for example, see Patent Document 1). The immersion exposure is to further increase the NA by making the medium on the wafer side of the projection optical system liquid. That is, assuming that the refractive index of the medium is n, the NA of the projection optical system is NA = n · sin θ. Therefore, by filling a medium having a refractive index (n> 1) higher than the refractive index of air, the NA increases to n. can do.
JP-A-10-303114 U.S. Pat. No. 4,346,164

  However, as the NA increases, the influence of the polarization of light on the imaging performance cannot be ignored. This is because the larger the angle of incidence of light on the wafer, the more the imaging performance differs depending on the polarization direction of the light.

  The effect of the polarization of light on the imaging performance is much greater for two-beam interference than for three-beam interference. This is because the three-beam interference that forms an image by interference of a total of three lights of the 0th-order diffracted light and ± 1st-order diffracted light is caused by the 0th-order light and the 1st-order diffracted light that form the fundamental frequency of the image, and the 0th-order term and −1 Since the angle of the second-order diffracted light does not reach 90 °, the influence of polarized light does not appear significantly. On the other hand, imaging by two-beam interference is difficult when two first-order diffracted lights interfere with each other, such as a phase shift mask, or oblique incidence. In some cases, 0th order diffracted light such as illumination and ± 1st order diffracted light interfere with each other. However, since the angle of the two light beams forming the fundamental frequency increases, the polarization has a large effect on the imaging performance. Because it appears.

  Further, when the medium becomes liquid, there is a large problem that there is a condition that no image is formed depending on the polarization direction of light. This is a phenomenon that has not occurred in the conventional non-immersion optical system. This is because, as shown in FIG. 16A, when two light flux images intersecting in the paper surface are considered, the P-polarized light whose polarization direction is in the paper surface does not interfere if the angle between the two light beams is 90 °. This is a problem in that it does not contribute to imaging. When the angle between the two light beams is 90 °, the incident angle is 45 °, and the sine of the two light beams is sin45 ° = 0.7.

  On the other hand, as shown in FIG. 16B, the two luminous fluxes of S-polarized light whose polarization direction is perpendicular to the plane of the paper perform imaging with good contrast because their polarization directions match. Hereinafter, in the present application, a polarization direction that forms an image with good contrast is defined as an S-polarized component. As described herein, the S-polarized light has a polarization direction orthogonal to the paper surface with respect to a light beam intersecting in the paper surface. The polarization direction is closely related to the direction in which the pattern is formed. Considering the direction of the interference fringes formed by two light beams, the longitudinal direction of each interference fringe and the direction of the S-polarized light match. ing. Therefore, the direction of S-polarized light when forming an interference pattern having a fine structure extending in the X direction is the X direction, and the direction of S-polarized light when forming an interference pattern having a fine structure extending in the Y direction is the Y direction.

Here, the refractive index of the medium between the projection optical system and the wafer n _o, the angle in the medium theta _o, a refractive index of the resist formed on the wafer and n _r, the incident angle of the resist ± theta _Consider two-beam interference in which two light beams of _r interfere to form an image. From Snell's law, the following equation 1 holds.

Medium For _air, n o = _1, because it is sinθ _o <1, the following Equation 2 is satisfied.

In the case of an ArF excimer laser, the typical refractive index of the resist is _nr = 1.7, so that from Equation 2, sin θ _r <0.59. As described above, when the medium is air, the angle θr in the resist does not become sin θ _r = 0.7.

On the other hand, consider immersion in which the medium is a liquid. When the refractive index of the medium and _n o = 1.47, the following equation 3 is established.

Since the resist refractive index is usually n _r = 1.7, sin θ _r <0.86. Therefore, when the medium is a liquid, there is a condition that sin θ _r = 0.7.

As described above, when the medium is air, sin θr does not become 0.7. However, when the medium becomes liquid, there is a condition that sin θ _r = 0.7. Is zero. If the illumination light is in a non-polarized state that does not take polarization into account, only the S-polarized light, which accounts for half of the incident light, is involved in imaging, and the contrast is halved. The drop is remarkable.

For example, in the case of an ArF excimer laser, if the medium is water and n ₀ = 1.47, the following Equation 4 holds.

As a result, when the medium is water, the condition is such that the P-polarized light does not interfere at sin θ _o = 0.81. Therefore, the P-polarized light does not form an image near the angle of incidence sin θ _o = 0.8 on the medium. When liquid immersion exposure is required, an optical system having an angle of sin θ _o = 0.8 or more is also required, so that this problem cannot be avoided. Also, in the case of the F2 excimer laser, since the refractive index of the medium is around 1.36 when the refractive index of the resist is a little over 1.5, the same relationship is established around sin θ _o = 0.8.

It is known that in order to increase the NA, it is better to increase the refractive index between the resist and the liquid and reduce the difference in the refractive index. The refractive indices of the resist and the liquid differ depending on the materials, and the difference between the refractive indices of the resist and the liquid is preferably small (Patent Document 2). However, sin θ _{r in} the medium is slightly larger than sin θ _o in the resist. In consideration of the direction in which a resist dedicated to immersion is developed, it has been found by analysis of the present inventors that it is preferable to set sin θ _r in the medium to be almost equivalent to sin θ _o in the resist on the exposure apparatus side. Therefore, the condition under which the P-polarized light does not interfere may be considered as sin θ _o ≒ sin θ _r = 0.7.

  As described above, in order to form a fine pattern, it is necessary to increase the NA of the projection optical system. However, in the liquid immersion type projection optical system, the imaging performance is reduced due to the influence of polarization due to the increase in NA, and the desired performance is obtained. The pattern cannot be formed.

  Therefore, the present invention exemplifies to provide an immersion type exposure method and apparatus capable of preventing a deterioration of an imaging performance due to the influence of polarization, securing a predetermined contrast, and forming a desired pattern. Purpose.

In order to achieve the above object, in an exposure method according to one aspect of the present invention, a surface of an object to be exposed and a final surface of a projection optical system are immersed in a liquid and a (fine) pattern formed on a mask is projected onto the projection optical system. In an exposure method for projecting an object onto an object to be exposed, the effective light source formed on a pupil of the projection optical system is parallel to a repetition direction of the (fine) pattern and orthogonal to an optical axis of the projection optical system. When the incident angle of the light obliquely incident on the resist from the portion on the axis to be exposed is θ, and the maximum value of the incident angle θ is θ _NA , 90 ° −θ _NA ≦ θ ≦ θ. _The light corresponding to the range of the incident angle θ that satisfies _NA has only the S-polarized light component.

  Further objects and other features of the present invention will become apparent from preferred embodiments and the like described below with reference to the accompanying drawings.

  According to the present invention, it is possible to provide an exposure method and an apparatus that can perform exposure with better imaging performance than before.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

  Hereinafter, an exposure apparatus 100 as one embodiment of the present invention will be described with reference to FIG. Here, FIG. 1 is a schematic block diagram of the exposure apparatus 100. As shown in FIG. 1, the exposure apparatus 100 includes an illumination device 110, a mask or reticle 130, a reticle stage 132, a projection optical system 140, a main control unit 150, a monitor and input device 152, a wafer 170, , A wafer stage 176 and a liquid 180 as a medium. As described above, in the exposure apparatus 100, the final surface of the projection optical system 140 on the wafer 170 side is partially or entirely immersed in the liquid 180, and the pattern formed on the mask MS via the liquid 180 is transferred to the wafer W This is a liquid immersion type exposure apparatus for exposing to light. Although the exposure apparatus 100 of the present embodiment is a step-and-scan projection exposure apparatus, the present invention is applicable to a step-and-repeat exposure method and other exposure methods.

  The illumination device 100 illuminates the mask 130 on which a transfer circuit pattern is formed, and includes a light source unit and an illumination optical system.

  The light source unit includes a laser 112 as a light source and a beam shaping system 114. As the laser 112, light from a pulse laser such as an ArF excimer laser having a wavelength of about 193 nm, a KrF excimer laser having a wavelength of about 248 nm, and an F2 excimer laser having a wavelength of about 157 nm can be used. The type and number of lasers are not limited, and the type of light source unit is not limited.

  The beam shaping system 114 can use, for example, a beam expander including a plurality of cylindrical lenses, and converts the aspect ratio of the cross-sectional shape of the parallel light from the laser 112 into a desired value (for example, The beam shape is formed into a desired shape by changing the shape from a rectangle to a square. The beam shaping system 114 forms a light beam having a size and a divergence angle necessary for illuminating an optical integrator 118 described later.

  The illumination optical system is an optical system that illuminates the mask 130. In the present embodiment, the converging optical system 116, the polarization controller 117, the optical integrator 118, the aperture stop 120, the converging lens 122, It includes a mirror 124, a masking blade 126, and an imaging lens 128. The illumination optical system can also realize various illumination modes such as conventional illumination, annular illumination, quadrupole illumination, and the like.

  The condensing optical system 116 is composed of a plurality of optical elements, and efficiently introduces the optical integrator 118 into a desired shape in a desired shape. For example, the collection optics 116 includes a zoom lens system to control the distribution of the shape and angle of the beam incident on the optical integrator 118.

  The condensing optical system 116 includes an exposure amount adjustment unit that can change the exposure amount of the illumination light to the mask 130 for each illumination. The exposure adjusting section is controlled by the main control unit 150. An exposure monitor may be placed, for example, between the optical integrator 118 and the reticle 130 or at another location to measure the exposure and feed back the result.

  The polarization control unit 117 includes, for example, a polarization element and is disposed at a position substantially conjugate with the pupil 142 of the projection optical system 140. The polarization control unit 117 controls the polarization state of a predetermined area of the effective light source formed on the pupil 142, as described later. The polarization control means 117 including a plurality of types of polarization elements may be provided on a turret rotatable by an actuator (not shown), and the main control unit 150 may control the driving of the actuator.

  The optical integrator 118 equalizes the illumination light illuminated on the mask 130, and in this embodiment, is configured as a fly-eye lens that converts the angular distribution of the incident light into a position distribution and emits the light. The fly-eye lens is configured by combining a plurality of rod lenses (that is, microlens elements) with the incident surface and the exit surface maintained in a Fourier transform relationship. However, the optical integrator 118 to which the present invention can be used is not limited to a fly-eye lens, but includes an optical rod, a diffraction grating, a plurality of sets of cylindrical lens array plates in which each set is orthogonal, and the like.

Immediately behind the exit surface of the optical integrator 118, an aperture stop 120 having a fixed shape and diameter is provided. As will be described later, the aperture stop 120 is disposed at a position substantially conjugate to an effective light source formed on the pupil 142 of the projection optical system 140, and the aperture shape of the aperture stop 120 is determined by the effective shape of the pupil plane 142 of the projection optical system 140. It corresponds to the light source shape. The aperture stop 120 controls the shape of the effective light source as described later.
The aperture stop 120 can be switched by an aperture exchange mechanism (actuator) 121 so that various aperture stops, which will be described later, are positioned in the optical path according to the illumination conditions. The drive of the actuator 121 is controlled by a drive control unit 151 controlled by the main control unit 150. The aperture stop 120 may be formed integrally with the polarization control unit.

  The condensing lens 122 condenses a plurality of light beams emitted from a secondary light source near the exit surface of the optical integrator 118 and transmitted through the aperture stop 120, reflects the light beams on the mirror 124, and changes the surface of the masking blade 126 as the illuminated inclined surface. Illuminate uniformly with Koehler illumination.

  The masking blade 126 is composed of a plurality of movable light shielding plates, and has a substantially rectangular arbitrary opening shape corresponding to the effective area of the projection optical system 140. The light beam transmitted through the opening of the masking blade 126 is used as illumination light for the mask 130. The masking blade 126 is an aperture whose opening width can be automatically varied, and can change the transfer area. Further, the exposure apparatus 100 may further include a scan blade having a structure similar to the above-described masking blade, which allows a transfer area in the scan direction to be changed. The scan blade is also an aperture whose aperture width can be automatically varied, and is provided at a position optically substantially conjugate with the mask 12 surface. The exposure apparatus 100 can set the size of the transfer area in accordance with the size of the shot to be exposed by using these two variable blades.

  The imaging lens 128 irradiates and transfers the opening shape of the masking blade 126 onto the surface of the reticle 130 and reduces and projects the pattern on the surface of the reticle 130 onto the surface of a wafer 170 placed on a wafer chuck (not shown).

  The mask 130 has a pattern to be transferred formed thereon, and is supported and driven by a mask stage 132. Diffracted light emitted from the mask 130 passes through the projection optical system 140 and is projected onto the wafer 170. The wafer 170 is an object to be exposed, and a resist 172 is applied on a substrate 174. The mask 130 and the wafer 170 are arranged in an optically conjugate relationship. Since the exposure apparatus 100 is a step-and-scan exposure apparatus (ie, a scanner), the pattern of the mask 130 is transferred onto the wafer 170 by scanning the mask 130 and the wafer 170. In the case of a step-and-repeat type exposure apparatus (that is, a “stepper”), exposure is performed while the mask 130 and the wafer 170 are stationary.

  FIG. 2 shows an example of the mask pattern. Here, FIG. 2A is a plan view showing a mask pattern having a repetition direction in the X-axis direction and a longitudinal direction in the Y direction, and FIG. 2B is a plan view showing the repetition direction in the Y-axis direction. FIG. 2C is a plan view showing a mask pattern having a longitudinal direction in the X direction. FIG. 2C is a plan view of a mask pattern in which these are mixed.

  Note that the mask 130 is not limited to a binary mask, and may be a phase shift mask. The pattern formed on the mask 130 may be a line pattern such as a gate pattern, a contact hole, or another pattern.

  The mask stage 132 supports the mask 130 and is connected to a moving mechanism (not shown). The mask stage 132 and the projection optical system 140 are provided, for example, on a stage barrel surface plate supported via a damper or the like on a base frame mounted on a floor or the like. Any configuration known in the art can be applied to the mask stage 132. A moving mechanism (not shown) is configured by a linear motor or the like, and can move the mask 130 by driving the mask stage 132 in the XY directions. Exposure apparatus 100 scans mask 200 and wafer 170 in synchronization with main control unit 150.

  The projection optical system 140 has a function of forming an image of the diffracted light having passed through the pattern formed on the mask 130 on the wafer 170. The projection optical system 300 includes an optical system including only a plurality of lens elements, an optical system including a plurality of lens elements and at least one concave mirror (catadioptric optical system), a plurality of lens elements and at least one kinoform. An optical system having a diffractive optical element such as the above can be used. When chromatic aberration needs to be corrected, a plurality of lens elements made of glass materials having different dispersion values (Abbe values) from each other may be used, or the diffractive optical element may be configured to cause dispersion in a direction opposite to that of the lens element. I do. Otherwise, chromatic aberration compensation is achieved by reducing the width of the laser spectrum. Recently, such narrow band lasers are one of the mainstreams.

The main control unit 150 controls the driving of each unit. In particular, the lighting control is performed based on information input from the input device of the monitor and input device 152, information from the lighting device 100, and a program stored in a memory (not shown). I do. More specifically, the main control unit 150 controls the shape and the polarization state of the effective light source formed on the pupil 142 of the projection optical system 140, as described later. The control information and other information by the main control unit 150 are displayed on the monitor of the monitor and input device 152. In another embodiment, the wafer 170 is replaced with a liquid crystal substrate or another object to be exposed. On the wafer 170, a photoresist 172 is applied on the substrate 174.

  The wafer 170 is supported on a wafer stage 176. The stage 176 may have any structure known in the art, and thus a detailed description of the structure and operation will be omitted. For example, the stage 176 uses a linear motor to move the wafer 170 in the X and Y directions. The mask 130 and the wafer 170 are scanned, for example, synchronously, and the positions of the mask stage 132 and the wafer stage 176 are monitored by, for example, a laser interferometer, and both are driven at a constant speed ratio. The stage 176 is provided, for example, on a stage base supported on a floor or the like via a damper. The mask stage 132 and the projection optical system 140 are, for example, a lens barrel base mounted on the floor or the like. It is provided on a lens barrel base (not shown) supported on a base frame via a damper or the like.

  The liquid 180 is immersed in the final surface of the projection optical system 140 onto the wafer 170, and a material is selected that has good transmittance at the exposure wavelength, does not adhere to the projection optical system, and has good matching with the resist process. . A coating is applied to the final surface of the projection optical system 140 to protect the influence from the liquid 180.

  Hereinafter, the polarization control performed by the main control unit 150 will be described. First, the effect of polarization will be described with reference to FIG. Here, FIGS. 3A and 3B are schematic diagrams for defining S-polarized light and P-polarized light, respectively. As shown in FIG. 3A, light polarized in a direction perpendicular to the cross section of the projection optical system 140 (that is, perpendicular to the paper) is S-polarized, that is, as shown in FIG. Light polarized perpendicular to the plane containing the imaging light beam is defined as S-polarized light. Light polarized in a direction parallel to the cross section of the projection optical system 140 (that is, in the plane of the paper) and polarized parallel to a plane including two imaging light fluxes as shown in FIG. I do. In other words, the direction in which light travels is taken along the Z axis, and the direction orthogonal to the Z axis and parallel to the plane (paper plane) containing the two imaging luminous fluxes is referred to as the X axis plane (paper plane) containing the two imaging luminous fluxes. If the orthogonal direction is taken on the Y axis, the S polarized light is polarized in the Y axis direction and the P polarized light is polarized in the X axis direction. The longitudinal direction of the fine structure of the fine pattern formed by the light beam drawn in the paper is perpendicular to the paper and coincides with the S-polarized light.

  In order to achieve the high-resolution imaging performance expected from the increase in NA, it is only necessary to cut off the P-polarized light, which lowers the contrast of the image, and to form only the S-polarized light. That is, as shown in FIG. 2A, an image may be formed on a line pattern whose mask pattern is long in the Y-axis direction by using S-polarized light having a polarization direction in the Y-axis direction indicated by an arrow.

  In the present embodiment, when 1/2 of the angle formed by the two light beams of the diffracted light, which is the image forming light beam of the pattern, in the liquid 180 is φ (deg), two light beams forming an angle of sin φ = 0.7 are formed. It is an object of the present invention to configure an effective light source region that may be subjected to only S-polarized light as much as possible.

In one embodiment, in the case of two-beam interference caused by + 1st-order light and -1st-order light, such as a 0th-order light and a 1st-order light or a Levenson-type phase shift mask, such an area is used to reduce the emission angle of the light in the liquid 180. When θ and the maximum emission angle are set to θ _NA , two light fluxes, which are regions on the effective light source formed on the pupil 142 corresponding to a range satisfying 90 ° −θ _NA ≦ θ ≦ θ _NA , are actually 90 °. It should be avoided in the resist, but when the refractive index of the liquid is close to that of the resist, it can be considered that θ ₀ = θ _r . Therefore, θNA can be considered as the maximum angle common to the liquid and the resist. it can. In still another embodiment, such an area is an area on the effective light source formed on the pupil 142 where two exposure light beams to be imaged may be orthogonal to each other.

Note that the S-polarized light and the direction of the pattern have been described above, but this can be converted into the following expression in the pupil coordinates of the effective light source. That is, the S-polarized light refers to a polarization direction directed to a section line direction, which is a direction orthogonal to a radiation line drawn from the center of the pupil 142, in an effective light source of illumination light when considered at the pupil 142 of the projection optical system 140. . However, actually, the S-polarized light is determined by the direction of the pattern to be imaged. Since an actual LSI pattern has many patterns in the X and Y directions, S-polarized light basically has a polarization direction in the X or Y direction, and an effective light source region having a polarization direction in the X direction is a projection optical system. This includes a case where the pupil 142 of the system 140 exists in a region centered on the Y axis and the effective light source region having a polarization direction in the Y direction exists in a region centered on the X axis of the pupil of the projection optical system. . Further, when including a 45 ° direction, an example having four directions of X, Y, and ± 45 ° is also included.

To further examine the above condition, for example, in FIG. 16B, in the projection optical system 140 of θ _NA ≧ 45 ° satisfying sin θ _NA ≧ 0.7, where θ _NA is the maximum incident angle. This can be achieved by making the component represented by the following equation out of the illumination light emitted to the liquid 180 at an angle θ into S-polarized light.

Here, referring to FIG. 16B, θ in Expressions 5 and 6 is an incident angle between the exposure light and a straight line perpendicular to the surface of the substrate inside the resist. Θ _NA is the maximum incident angle of the exposure light as the maximum value of the incident angle θ.

  When the effective light source radius of the effective light source obtained by projecting the light source distribution of the illumination optical system onto the pupil 142 is considered to be 1 and the maximum radius of the effective light source is σ without considering the refractive index, Equation 6 is given by Equation 7 below. Is equivalent to setting the effective light source in the range as S-polarized light.

Here, σ _MAX is a parameter corresponding to the outermost of the set effective light source distribution, and σ _MAX sin θ _NA indicates the maximum angle of the illumination light in the liquid 180.

  Since an actual LSI pattern often has a specific direction in the X and Y directions, it is necessary to take this into consideration in the shape of the effective light source. FIGS. 4 and 5 show two-dimensional distributions of effective light sources in consideration of directionality. Here, FIG. 4A is an effective light source distribution that defines polarized light for exposing the mask pattern shown in FIG. 2A. FIG. 4B is an effective light source distribution that defines polarized light for exposing the mask pattern shown in FIG. 2B. FIG. 5 shows an effective light source distribution that defines polarized light for exposing the mask pattern shown in FIG. 2C.

  Next, the relationship between the area of the effective light source and the polarization direction will be described with reference to FIGS. Consider the image formation of a mask pattern parallel to the Y direction as shown in FIG. As shown in FIG. 6, a normal effective light source has a light source within a radius σ on an effective light source coordinate normalized to a maximum radius of 1 and does not take polarization into account. Are mixed and distributed.

The S-polarized light is the polarization direction in the Y direction indicated by the arrow in the image formation of the mask pattern shown in FIG. FIG. 7 shows the pupil plane of the optical system, and the set effective light source area (≦ σ _MAX ) is shown in white. Light emitted at an angle theta ₁ to the liquid 180 from the projection optical system 140, the effective light source coordinate is normalized in the effective light source on the sin pupil, it enters the position of sinθ ₁ / sinθ _NA. 0.5 The following sufficiently fine pattern in Figure 2 the mask pattern shown in (a) is k ₁ factor Rayleigh equation which is an index of resolving power (= R / (λ / NA )), the dotted line in FIG. Two connected black circles indicate a pair of two-beam interference of the 0th order and the 1st order, or the -1st order and the 0th order. The distance between the two black circles is represented by 1 / (2k ₁ ) in the above normalized coordinate system. The direction in which the line segment extends is a direction orthogonal to the direction in which the individual fine patterns extend.

In immersion, as described above, there is a case where these two light beam pairs form an angle near sinφ = 0.7 and have no contrast with P-polarized light at all. Therefore, when the polarization direction is controlled only in the Y direction, which is the S-polarized light, in the region where such a pair exists, the image contrast can be improved. The region where the polarization direction is to be controlled in accordance with the pattern as described above is shown as a hatched region. In the shaded region, it is a condition that one of the two black circles indicating the zero-order light is included in the white part indicating the effective light source, and the other black circle indicating the ± first-order light is included in the pupil. . The hatched area is found by searching for a condition in which both ends of a line segment having a distance of 1 / (2k ₁ ) between black circles are within the pupil. In this case, the two hatched regions are shaped like asymmetrical canoes in which two circles cross each other and are sharp. At this time, when the boundary on the X-axis is obtained, the feature of the present embodiment is that the angle θ in the liquid 180 satisfies the following condition.

Here, σ _MAX is a parameter corresponding to the outermost of the set effective light source distribution, and σ _MAX sin θ _NA corresponds to the maximum angle of the illumination light in the liquid.

In FIG. 7, the line outside the region is a circle centered on X = 0, with the set maximum effective light source σMAX as the radius, while the line inside is a radius 1, which indicates the size of the pupil, and X = − ( σ _IN +1). From Equation 7, σ _IN is represented by the following equation.

That is, the region to be S-polarized light is a region where a circle centered at X = 0, the radius of which is the maximum effective light source σ _MAX , and a circle centered at X = ± (σ _IN +1) and whose radius is 1 intersect. However, FIG. 8 shows only one side of a circle whose center is X = − (σ _IN +1) and whose radius is 1.

Equation 8 defines the angle range only on the X-axis or Y-axis of the pupil, but not only light parallel to the optical axis direction of the projection optical system but also light that enters obliquely. Considering the angle range of a light beam obliquely incident, α ≦ θ ≦ _θNA , and the minimum value of the angle α is a function of Y.

Coordinate radius 1 to obtain the minimum value α of angular center is on a circle centered on the X = _{X 1} or _{X = X 2, Y = 0} , X 1 = + (σ IN +1), X 2 = - Since (σ _IN +1), considering only a circle centered on X = X ₁ , (XX ₁ ) ² + Y ² = 1, X = X ₁ ± √ (1-Y) ² , X ≦ At 1, X = X ₁ −√ (1-Y) ² and α = tan ⁻¹ (Y / X) (0 ≦ α ≦ 45 °), so α = tan ⁻¹ (Y / X) = tan ⁻¹ (Y / (X ₁ −√ (1-Y) ² )) Therefore, the angle range with respect to the XZ plane parallel to the X axis other than on the X axis is as follows. α ≦ θ ≦ θ _NA , (0 ≦ α ≦ 45 °), α = tan ⁻¹ (Y / X) = tan ⁻¹ (Y / (X ₁ −√ (1-Y) ² ), X ₁ = + (Σ _IN +1) and σ _IN are obtained from Expression 9.

σ _IN = sin (90 ° −θ _NA ) / sin θ _NA , and within this angle range, only S-polarized light, that is, only linearly polarized light in the Y direction perpendicular to the X axis must be used.

On the other hand, a small illumination light incident angle to emit a light beam at an angle of theta ₁ which satisfies _{sinθ 1 ≦ sin (90 ° -θ} NA) in the immersion medium does not contribute to formation of a fine pattern, the diffraction angle Is small. In this case, the effect of the polarization is small, and it is not necessary to particularly consider the control of the polarization. That is, either unpolarized or polarized light can be assigned to this region, showing little difference between them.

  Therefore, a feature of the present embodiment is that polarization is considered only for light incident on the shaded portion in the region where the effective light source exists. As shown in FIG. 4A, these hatched areas are symmetric with respect to the Y axis, and the polarization direction is the Y direction in which the light is s-polarized light, that is, the direction of the section line in the circle representing the pupil 142 of the projection optical system 140. It has become.

  Further, as shown in FIG. 4B, the mask pattern parallel to the X direction as shown in FIG. 2B is obtained by rotating FIG. 4A by 90 °. Is symmetric with respect to the X axis, and the polarization direction is the X direction, which is S-polarized light. The boundary on the Y-axis is the same as Equation 8 as the boundary condition previously obtained for the X-axis.

Further, as shown in FIG. 2C, when a mask pattern parallel to the X direction and a mask pattern parallel to the Y direction having the same fineness are mixed, as shown in FIG. 5A. The hatched area is symmetrical with respect to the X axis and the Y axis, and the polarization direction is the tangential X and Y directions for S-polarization. Further, the boundary points on the X axis and the Y axis satisfy Expression 8. theta _NA is increased, as shown in FIG. 5 (b), to S-polarized light region and S portion polarizing region are overlapped in the Y direction in the X direction okay to unpolarized area of the light source and the intensity zero You can eliminate the distribution. Further, as shown in FIG. 5C, the polarization state may be divided with the center as a boundary. Further, as shown in FIG. 5D, the effect is the same even if the effective light source has a distribution of the polarization direction.

  As shown in FIG. 2A, when the size of the mask pattern is limited to a fine size and the direction of the mask pattern is one direction, the optimal effective light source is shown in FIG. A dipole illumination as shown is suitable. The effective light source shown in FIG. 8A satisfies Expression 8 on the X-axis. When the 0th-order light enters the light source region indicated by oblique lines, the other + 1st-order light or -1st-order light all passes through the pupil. Since the light source incident area on the pupil is large, and two light beams are incident without leakage, they are involved in image formation without waste. In addition, since the double pole only needs to satisfy Expression 8 on the X axis, the shape of a circle shown in FIG. 8B cut out by a straight line, and the annular zone shown in FIG. Various shapes such as a partially cut out shape and a circular shape shown in FIG. 8C can be applied. In FIG. 8, a hatched portion is a light-transmitting portion whose polarization is controlled, and a gray portion is a light-shielding portion.

  FIG. 5 shows an example in which the direction of the mask pattern shown in FIG. 2 (c) is limited to a fine pattern and the optimum effective light source for a plurality of patterns is shown in FIG. The objective can be achieved by the annular illumination as shown. Here, in FIGS. 9A and 9B, the hatched portions are polarization-controlled, and the gray portions are light-shielding portions. The white part in FIG. 9A is a light transmitting part. At this time, the outer and inner diameters of the annular illumination are set within a range that satisfies Equation 8 on the X axis and the Y axis, and the polarization direction is set in the direction of the broken line as shown in the figure. The boundary of polarized light located at the part of ± 45 ° may be non-polarized, or the directions of polarization in the X and Y directions may be switched here.

  Further, for a pattern in which oblique directions inclined by 45 ° with respect to the XY axes are mixed, a region satisfying Expression 8 according to the direction of the pattern as shown in FIG. In this case, the 45 ° direction is rotationally symmetric, and Equation 8 is similarly applied.

  In an actual optical system, it is difficult to insert a polarizing element into the projection optical system 140 due to a problem of thermal aberration and the like. Therefore, in the present embodiment, the polarization of a predetermined area of the effective light source is controlled before the reticle 130. For example, the polarization is controlled by using the polarization control means 117 provided in the preceding stage of the optical integrator 118. The optical integrator 118 also has a portion conjugate to the pupil 142 of the projection optical system 140, and it is preferable to control the polarization at the optical integrator 118 in order to simplify the configuration of the optical system. The shape of the effective light source is adjusted by the aperture stop 120. The polarization may be controlled at the aperture stop 120.

  The projection optical system 140 has no polarization directionality in the optical system itself except for a special example. Therefore, in the conventional non-immersion system, the illuminating light is processed so as not to have a polarization characteristic, and the effective light source does not have a special state such as P-polarized light or S-polarized light in an illumination region having a radius σ (σ ≦ 1) or less. It was in a non-polarized state. However, in the case of liquid immersion, considering the frequency components of the luminous flux in the image formation, it can be seen that a polarization characteristic suitable for image formation of a pattern in the X direction or the Y direction occurs. This condition is the polarization characteristic in the section line direction described above, that is, the S-polarization characteristic. This is because the degree of deterioration of the p-polarized light differs between the low-frequency pattern and the high-frequency pattern, that is, the high-frequency component around the pupil of the optical system is very sensitive to the effect of polarization, and Is due to the fact that the effect of polarization has no effect on the low-frequency components.

  For this reason, in the low frequency components inside the pupil 142 of the projection optical system 140, the contrast does not decrease much, and the influence of the polarization need not be considered. Therefore, in the imaging of a non-fine pattern, the influence of the polarized light on the resolution performance is small, and the optical system may be configured ignoring the polarized light.

  Therefore, in the effective light source shapes shown in FIGS. 4, 5, 8 to 10 proposed in the present embodiment, the hatched portion must be S-polarized, but the region on the effective light source other than the hatched portion is an arbitrary polarized light. The state is good. The method of setting the region to be S-polarized light is determined by the number of directions of the pattern, and the region is determined by Expression 8 on an axis in a direction orthogonal to the direction in which the pattern extends. That is, if the direction of the pattern is one direction, there are two regions for S-polarized light as shown in FIG. If the direction of the pattern is two directions, there are four regions including S overlap as shown in FIG. If the direction of the pattern is three or four, the region to be S-polarized has a substantially annular shape as shown in FIG. In the case where the pattern does not include a large pattern and is composed of only a fine pattern, an effective light source shape shown in FIGS. 8 and 9 can provide a fine resolution improving effect. The method of selecting the region to be S-polarized light is the same as in FIGS. 4 and 5, except that the central portion is shielded from light.

  In the present embodiment, the effective light source shapes shown in FIGS. 4, 5, 8 to 10 are realized by the aperture shape of the aperture stop 120. Therefore, these effective light source shapes are embodied as the shapes of the light transmission and the light shielding portion of the aperture stop 120. In the present embodiment, a plurality of types of aperture stops having the plurality of effective light source shapes are arranged on the turret, and are configured to be switchable by the actuator 121. Also, as for the polarizing element, a plurality of types of polarizing elements having a polarizing element in a shape corresponding to the opening shape of the aperture stop are arranged on the turret, and can be switched by an actuator (not shown). An illumination optical system and an exposure apparatus having such an aperture stop 120 and a polarizing element also constitute one aspect of the present invention. The exposure apparatus has various exposure modes that control both the shape and polarization of the available light source.

  In the exposure, the light beam emitted from the laser 112 enters the illumination optical system after its beam shape is shaped into a desired one by the beam shaping system 114. The condensing optical system 116 efficiently introduces the light flux into the optical integrator 118. At this time, the exposure adjusting unit adjusts the exposure of the illumination light.

  In addition, the main control unit 150 allows the user to input the information of the mask pattern through the monitor and the input device of the input device 152, or recognizes the information by reading a barcode or the like formed on the mask, and converts the information into the mask pattern. An aperture shape and a polarization state as suitable illumination conditions are selected by driving an actuator (not shown) of the polarization control unit 117 and an actuator 121 of the aperture stop 120. For example, the main control unit 150 sets the polarization state in FIG. 4A for the mask pattern in FIG.

  The optical integrator 118 equalizes the illumination light, and the aperture stop 120 sets a desired effective light source shape. The illumination light illuminates the mask 200 under optimum illumination conditions via the condenser lens 122, the bending mirror 124, the masking blade 126, and the imaging lens 128.

  The light beam that has passed through the mask 130 is reduced and projected at a predetermined magnification on the wafer 170 by the projection optical system 140. In the case of a step-and-scan exposure apparatus, the light source 112 and the projection optical system 140 are fixed, and the mask 130 and the wafer 170 are synchronously scanned to expose the entire shot. Further, the wafer stage 176 is stepped to move to the next shot, and a new scan operation is performed. This scan and steps are repeated to expose and transfer a number of shots on the wafer 170. If the exposure apparatus employs a step-and-repeat method, the exposure is performed with the mask 130 and the wafer 170 stationary.

  Since the final surface of the projection optical system 140 on the wafer 170 is immersed in the liquid 180 having a higher refractive index than air, the NA of the projection optical system 140 becomes higher, and the resolution formed on the wafer 170 becomes finer. Further, an image with high contrast is formed on the resist 172 by controlling the polarization. Thus, the exposure apparatus 100 can provide a high-quality device (semiconductor device, LCD device, imaging device (such as CCD), thin-film magnetic head, etc.) by performing pattern transfer onto a resist with high accuracy.

Hereinafter, a first embodiment of the present invention will be described using an immersion type exposure apparatus 100. The exposure apparatus 100 uses an ArF excimer laser (wavelength 193 nm) as the light source 112, the projection optical system 140 has a numerical aperture of 1.32, and the maximum angle θNA in the liquid satisfies sin θ _NA = 0.9. . The refractive index of the liquid 180 is 1.47, and σ _{MAX of} the illumination system is 0.9. In general, a projection exposure apparatus performs reduced projection exposure. In the case of the reduced projection exposure, the pattern size to be created and the mask pattern differ depending on the magnification of the exposure apparatus. Hereinafter, the pattern size on the mask 130 will be described in terms of the dimensions on the wafer 170.

  As shown in FIG. 2C, in a mask pattern in which line and space (hereinafter abbreviated as “L / S”) patterns in the X and Y directions having the same line width and interval are mixed, the line width and the interval, that is, 11 (a) and 11 (b) show the contrast depth (μm) when the pitch was changed.

At this time, the sin [theta _NA = 0.9 was θ _NA = 64 °. sin (90 ° −θ _NA ) / sin θ _NA = 0.44 / 0.9 = 0.49, which corresponds to the incident area of only S-polarized light on the axis corresponding to the pattern direction, corresponding to Expression 8. The value of σ is 0.44 / 0.90 ≦ σ ≦ σ _MAX , and the illumination system should be designed so that the range of approximately 0.5 ≦ σ ≦ 0.9 is the S-polarized region.

For a non-polarized circular effective light source with σ _MAX = 0.9 shown in FIG. 6, 0.5 ≦ σ ≦ 0.9 as shown in FIG. FIG. 11A shows the contrast depth (μm) when the inner side having a value of 0.5 or less is a non-polarized circular effective light source. By controlling the polarization state, the depth increases with the fine line width, the critical resolution is extended, and the depth hardly changes where the line width is large. It is confirmed. In resolving a fine pattern, a decrease in contrast as in the non-polarized state is a serious problem. However, it has been found that a fine pattern can be resolved by using an effective light source whose polarization is controlled. The reduced contrast in non-polarized light is a major problem in the resolution of fine patterns. However, it is understood that a fine pattern can be resolved by using an effective light source whose polarization is controlled.

For a non-polarized circular effective light source with σ _MAX = 0.9 shown in FIG. 6, 0.5 ≦ σ ≦ 0.9 as shown in FIG. 9B as tangential polarization as shown in FIG. FIG. 11 (b) shows the contrast depth (μm) in the case of annular illumination in which the inside is shielded at a value of 0.5 or less. By shielding σ ≦ 0.5 and cutting the low frequency components inside the pupil of the optical system, the depth of the pattern with a fine line width increases instead of the depth of the pattern with a large line width slightly decreasing, Furthermore, the limit resolution is greatly extended, and the effect of S-polarized light is confirmed.

  Hereinafter, an immersion type exposure apparatus according to a second embodiment of the present invention will be described. As in the first embodiment, this exposure apparatus uses an ArF excimer laser (wavelength 193 nm) as the light source 112, the projection optical system 140 has a numerical aperture of 1.32, and the maximum angle in the liquid is θNA = sinθNA = 0.9 is satisfied. The refractive index of the liquid 180 is 1.47, and σMAX of the illumination system is 0.9.

  As shown in FIG. 2A, in a mask pattern in only one direction of the L / S pattern parallel to the Y direction having the same line width and interval, the contrast depth when the line width and the interval, that is, the pitch are changed. (Μm) is shown in FIGS. 12 (a) and 12 (b).

At this time, when sin θNA = 0.9, θNA = 64 °. In addition, sin (90 ° −θNA) / sin θNA = 0.44 / 0.9 = 0.49, which corresponds to the incident area of only S-polarized light on the axis corresponding to the pattern direction, corresponding to Expression 8. When the value of σ is 0.44 / 0.90 ≦ σ ≦ σMAX, the illumination system should be designed so that the range of approximately 0.5 ≦ σ ≦ 0.9 is the S-polarized region. For the non-polarized circular effective light source of σMAX = 0.9 shown in FIG. 6, with the illumination method shown in FIG. FIG. 12 (a) shows the contrast depth (μm) when the inside of a value of σ of 0.5 or less is a non-polarized circular effective light source. Here, the illumination A having the polarization in the cut line direction in the range of 0.68 ≦ σ ≦ 0.9 satisfies a part of the S-polarized region defined above, but in the case of 0.5 ≦ σ ≦ 0.9. Polarized light perpendicular to the section line direction is not used. That is,
The condition that the polarization in the direction of the cut line is used in 0.5 ≦ σ ≦ 0.9 can be said to be the condition that the polarization perpendicular to the direction of the cut line is not used in 0.5 ≦ σ ≦ 0.9. By controlling the polarization state, the depth increases with a fine line width, the critical resolution is extended, and the depth of a pattern with a large line width is slightly reduced, but not so much as to be a problem. The effect of improving the depth is confirmed. The effect is great when the pattern is unidirectional. In resolving a fine pattern, a decrease in contrast as in the non-polarized state is a serious problem. However, it has been found that a fine pattern can be resolved by using an effective light source whose polarization is controlled.

  For the non-polarized circular effective light source of σMAX = 0.9 shown in FIG. 7, 0.5 ≦ σ ≦ 0.9 as shown in FIG. FIG. 12B shows the contrast depth (μm) when X = 0.7 and the radius is 0.2 in the system. By shielding σ ≦ 0.5 and cutting the low frequency components inside the pupil of the optical system, the depth of the pattern with a fine line width increases instead of the depth of the pattern with a large line width slightly decreasing, Since the limit resolution is greatly extended, there is no problem even if light other than the S-polarized region is shielded when the line width is constituted only by a fine pattern. 8 (a), FIG. 8 (b) and FIG. 8 (d) show almost the same effect, and the results are omitted. In resolving a fine pattern, a decrease in contrast as in the non-polarized state is a serious problem. However, it has been found that a fine pattern can be resolved by using an effective light source whose polarization is controlled.

  In this embodiment, the case where NA = 1.32 has been described. However, the effect of this exposure method becomes more prominent as the NA becomes higher and as the pattern becomes finer. In addition, in the immersion optical system, the imaging contrast of the P-polarized light sometimes becomes zero, and it goes without saying that it appears more remarkably than the conventional projection optical system.

In the present embodiment, the polarization unique to the immersion type projection optical system has been described. Another major problem in the case of immersion is fluctuation of the liquid 180 itself. Although the refractive index of the liquid 180 was n _o, the portion of the mass with the fluctuation, as shown in FIG. 18, and has a refractive index n _{o +} [Delta] n. The absolute value ΔW of the fluctuation of the wavefront aberration when the fluctuation is present is expressed by the following equation as the maximum value, compared to when there is no fluctuation.

Here, d is the thickness of the immersion medium. In addition, Equation 11 below is derived from Equation 15.

When the allowable generation amount of ΔW is 30 mλ, θ _MAX = 60 °, the wavelength is 193 nm, and Δn = 10 ppm, and a numerical value is substituted from Expression 11, d ≦ 3000λcos θNA = 0.29 mm, and a numerical value close to an actual value is obtained. As long as d is small, the effects of any fluctuations can be suppressed to a small extent. In a liquid immersion system, how far d can be reduced is a major decision point.

  Further, pure water is suitable for the liquid for immersion in the ArF excimer laser. However, the optical element closest to the wafer 170 of the projection optical system 140 that is in contact with the liquid is also a portion of the projection optical system 140 where light energy is concentrated most. Therefore, quartz cannot be used due to the problem of durability of the glass material such as compaction, and it is necessary to use fluorite. However, fluorspar is deliquescent and can be damaged when it comes in contact with water. Conventionally, in the ArF region, it has been customary to apply a film to fluorite by a vapor deposition method. However, the film formed by vapor deposition is porous, and the fluorite of the substrate is damaged through the holes. Therefore, the present embodiment is characterized in that a sputtered film is used on the final surface of the projection optical system 140 that comes into contact with the liquid, thereby protecting the fluorite substrate and simultaneously achieving antireflection. For this purpose, for example, a sputtered film made of a material such as MgF2 is suitable.

  Next, an embodiment of a device manufacturing method using the above-described exposure apparatus will be described with reference to FIGS. FIG. 14 is a flowchart for explaining the manufacture of devices (semiconductor chips such as ICs and LSIs, LCDs, CCDs, etc.). Here, the manufacture of a semiconductor chip will be described as an example. In step 1 (circuit design), the circuit of the device is designed. Step 2 (mask fabrication) forms a mask on which the designed circuit pattern is formed. In step 3 (wafer manufacturing), a wafer is manufactured using a material such as silicon. Step 4 (wafer process) is referred to as a preprocess, and an actual circuit is formed on the wafer by the lithography technique of the present invention using the mask and the wafer. Step 5 (assembly) is called a post-process, and is a process of forming a semiconductor chip using the wafer created in step 4, and includes processes such as an assembly process (dicing and bonding) and a packaging process (chip encapsulation). Including. In step 6 (inspection), inspections such as an operation check test and a durability test of the semiconductor device created in step 5 are performed. Through these steps, a semiconductor device is completed and shipped (step 7).

  FIG. 15 is a detailed flowchart of the wafer process in Step 4. Step 11 (oxidation) oxidizes the wafer's surface. Step 12 (CVD) forms an insulating film on the surface of the wafer. Step 13 (electrode formation) forms electrodes on the wafer by vapor deposition or the like. Step 14 (ion implantation) implants ions into the wafer. In step 15 (resist processing), a photosensitive agent is applied to the wafer. Step 16 (exposure) uses the exposure apparatus to expose a circuit pattern on the mask onto the wafer. Step 17 (development) develops the exposed wafer. Step 18 (etching) removes portions other than the developed resist image. Step 19 (resist stripping) removes unnecessary resist after etching. By repeating these steps, multiple circuit patterns are formed on the wafer. According to the device manufacturing method of the present invention, it is possible to manufacture a higher-quality device than before. As described above, the device manufacturing method using the lithography technique of the present invention and the resulting device also constitute one aspect of the present invention. The present invention also covers the device itself, which is an intermediate and final product of the device manufacturing method. Such devices include, for example, semiconductor chips such as LSI and VLSI, CCDs, LCDs, magnetic sensors, thin-film magnetic heads, and the like.

  While the embodiments of the present invention have been described above, the present invention is not limited to these embodiments, and various modifications and changes can be made within the scope of the gist.

FIG. 1 is a schematic block diagram of an exposure apparatus as one embodiment of the present invention. FIG. 2 is a plan view illustrating some examples of patterns formed on a mask illustrated in FIG. 1. It is a conceptual diagram for explaining the effect of P polarization and S polarization. FIGS. 4A and 4B are effective light source distributions defining the polarization for exposing the mask pattern shown in FIGS. 2A and 2B, respectively. FIG. 2C is an effective light source distribution that defines polarized light for exposing the mask pattern shown in FIG. It is a schematic diagram for explaining the relationship between the area of the effective light source and the polarization direction. It is a schematic diagram for explaining the relationship between the area of the effective light source and the polarization direction. FIG. 3 is a schematic diagram illustrating an example of an effective light source shape when the mask pattern illustrated in FIG. 2A is configured with only a fine size. FIG. 3 is a schematic diagram showing an example of an effective light source shape in a case where the mask pattern shown in FIG. 2C has only a fine size. It is a schematic diagram which shows an example of the effective light source shape used for resolving the pattern of various directions. 3 is a graph showing a relationship between a pitch and a contrast depth in the mask pattern shown in FIG. 3 is a graph showing a relationship between a pitch and a contrast depth in the mask pattern shown in FIG. 3 is a graph showing a relationship between a pitch and a contrast depth in the mask pattern shown in FIG. 3 is a graph showing a relationship between a pitch and a contrast depth in the mask pattern shown in FIG. FIG. 2 is a schematic diagram for explaining fluctuation of a medium (liquid) shown in FIG. 1. 5 is a flowchart for explaining a device manufacturing method having the exposure apparatus of the present invention. 15 is a detailed flowchart of step 4 shown in FIG. FIG. 4 is a schematic diagram for explaining a relationship between an image and polarized light in immersion exposure.

Explanation of reference numerals

REFERENCE SIGNS LIST 100 Exposure device 112 Light source 120 Aperture stop 121 Actuator 130 Mask or reticle 140 Projection optical system 142 Pupil (plane)
150 Main control unit 170 Wafer 172 Reticle 174 Substrate 180 Medium (liquid)

Claims (21)

In the exposure method of immersing the surface of the object to be exposed and the final surface of the projection optical system in a liquid, and projecting a pattern formed on a mask onto the object to be exposed by the projection optical system,
Of the effective light source formed in the pupil of the projection optical system, the light emitted from a portion on an axis parallel to the repetition direction of the pattern and orthogonal to the optical axis of the projection optical system and obliquely incident on the resist. When the incident angle to the object to be exposed is θ and the maximum value of the incident angle θ is θ _NA , the light corresponding to the range of the incident angle θ that satisfies 90 ° −θ _NA ≦ θ ≦ θ _NA is an S-polarized component. An exposure method, comprising: In an exposure method, a pattern formed on a mask is immersed in an object to be exposed, at least a part of which is immersed in a liquid, and the numerical aperture n ₀ sin θ _NA , n ₀ is imaged using a projection optical system having a refractive index of the liquid. ,
When one of the repetition direction of the pattern formed on the mask and the direction orthogonal to the direction is the X axis and the other is the Y axis, and the incident angle of the exposure light to the projection optical system is θ, 90 ° A region on the effective light source formed on the pupil of the projection optical system corresponding to the range of the incident angle θ satisfying −θ _NA ≦ θ ≦ θ _NA is a straight line in a direction orthogonal to the X axis or the Y axis. An exposure method comprising irradiating the exposure light so as to have a polarization component. In an exposure method for forming an image by using a projection optical system in which a pattern formed on a mask is exposed on an object to be exposed, at least a part of which is immersed in a liquid,
An exposure method characterized by illuminating an area on an effective light source formed on a pupil of the projection optical system with only S-polarized light, where an orthogonal state may occur between two exposure light fluxes to form an image.   4. The exposure method according to claim 1, wherein the region has a pointed canoe-like shape formed by two circles intersecting with each other. 5.   4. The exposure method according to claim 1, wherein the region has a shape formed by partially cutting out a circle with a straight line. 5.   4. The exposure method according to claim 1, wherein the region has a shape formed by partially cutting out an annular zone with a straight line. 5.   The exposure method according to claim 1, wherein the region has a circular shape. An exposure method for forming an image using a projection optical system having a numerical aperture n ₀ sin θ _NA by irradiating a pattern formed on a mask on an object to be exposed with exposure light having a wavelength λ and at least a portion immersed in a liquid,
Exposure method characterized by setting the thickness d of the liquid so as to satisfy the d ≦ 3000λcosθ _NA. An exposure method for forming an image using a projection optical system in which a pattern formed on a mask is exposed on a body to be exposed, at least a part of which is immersed in a liquid,
An exposure method, wherein the projection optical system protects a final surface in contact with the liquid from the liquid. An exposure apparatus that images a pattern formed on a mask on an object to be exposed,
A projection optical system at least partially immersed in a liquid and having a numerical aperture n ₀ sin θ _NA ;
An effective light source formed on the pupil of the projection optical system corresponding to a range in which the angle θ at which the exposure light is emitted from the projection optical system satisfies 90 ° −θNA ≦ θ ≦ θNA so as to ensure a predetermined contrast. An exposure apparatus comprising: a polarization control unit that controls a polarization state of an upper region. An exposure apparatus that images a pattern formed on a mask on an object to be exposed,
A projection optical system at least partially immersed in a liquid,
Polarization control for controlling the polarization state of the exposure light in an area on the effective light source formed in the pupil of the projection optical system where an orthogonal state may occur between the two exposure light fluxes to be imaged so as to ensure a predetermined contrast. An exposure apparatus comprising:   The exposure apparatus according to claim 10, wherein the polarization controller controls the polarization state to be only S-polarized light.   The exposure apparatus according to claim 10, wherein the polarization control unit includes a polarization element disposed substantially conjugate to a pupil plane of the projection optical system. The polarization control unit includes an aperture stop arranged substantially conjugate to a pupil plane of the projection optical system,
The exposure apparatus according to claim 10, wherein the aperture stop has a sharp canoe-shaped aperture shape formed by two circles intersecting with each other. The polarization control unit includes an aperture stop arranged substantially conjugate to a pupil plane of the projection optical system,
The exposure apparatus according to claim 10, wherein the aperture stop has an aperture shape formed by partially cutting out a circle with a straight line. The polarization control unit includes an aperture stop arranged substantially conjugate to a pupil plane of the projection optical system,
The exposure apparatus according to claim 10, wherein the aperture stop has an aperture shape formed by partially cutting a ring zone along a straight line. The polarization control unit includes an aperture stop arranged substantially conjugate to a pupil plane of the projection optical system,
The exposure apparatus according to claim 10, wherein the aperture stop has a circular aperture shape.   The exposure apparatus according to claim 10, wherein the predetermined contrast is 0.7.   In an exposure apparatus for immersing a surface of an object to be exposed and a final surface of a projection optical system in a liquid and projecting a mask pattern onto the object to be exposed by the projection optical system, a wavelength of light used for the projection is set to λ (nm). When the refractive index of the liquid is n0, the numerical aperture of the projection optical system is n0 sin θ0, and the thickness of the liquid in the optical axis direction of the projection optical system is d, d ≦ 3000λcosθ0 is satisfied. Exposure equipment.   20. The exposure apparatus according to claim 19, wherein a final surface of the projection optical system that comes into contact with the liquid is a surface on the fluorite substrate, and a sputtered film is formed on the final surface. Exposing the object to be exposed using the exposure apparatus according to any one of claims 10 to 20,
Performing a predetermined process on the exposed object to be exposed.