JP2007142084A - Exposure method and manufacturing method of device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To manufacture a hole array of high density regarding an exposure method for forming a hole array executed in a lithography process, and a device manufacturing method using the method. <P>SOLUTION: A mask R wherein a prescribed pattern is formed is illuminated under cross pole illumination conditions, a wafer W is exposed via a projection optical system PL by light IL projected from the mask, and a hole array is formed on the wafer. Therefore, it is possible to apply limit resolution of a k<SB>1</SB>factor which is the same as that of an L/S pattern, even to a hole array pattern, thus enabling a hole array of high density to be manufactured. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an exposure method and a device manufacturing method. More specifically, the present invention is performed in a lithography process when manufacturing a microdevice such as a semiconductor element or a liquid crystal display element, for example, a memory such as a D-RAM or a flash memory. The present invention relates to an exposure method for forming a hole array and a device manufacturing method using the method.

Regarding the limit resolution of a dense pattern (line and space pattern (hereinafter referred to as L / S pattern)), a k ₁ factor of R = k ₁ × (λ / NA), which is well known as Rayleigh's equation ( Process coefficient). Here, λ is the exposure wavelength (nm), and NA is the numerical aperture of the projection optical system (projection lens).

For an ideal optical system in degree of coherence of the illumination system (sigma) Maximum (sigma = 1), for the L / S pattern, k ₁ ≧ 0.250, for hole array pattern, in the conventional exposure method k ₁ Since it is ≧ 0.354, it has been considered that there is a difference of √2 when the minimum values of both k ₁ are compared. This will be described in detail below.

In order to form an interference pattern (optical image) in the exposure apparatus, at least two light beams out of the light diffracted by the pattern simultaneously pass through the pupil of the projection optical system, and an object to be exposed, for example, a wafer or a glass plate Etc. (hereinafter collectively referred to as a wafer) must be made to reach the surface together.
(1) Limit resolution of L / S pattern As shown in FIG. 15, the diffracted light generated from the equally spaced L / S pattern has a constant interval with respect to the sin θ axis (horizontal axis). interval n order light and (n + 1) order light is amplitude A _n of lambda / P, n order light can be expressed by the SINC function of the following equation (1).

In the above formula, w represents the width (nm) of the portion of the L / S pattern through which light is transmitted, and P represents the pitch (nm) of the L / S pattern.

  In order to form an interference pattern (optical image) on the wafer surface, it is necessary that at least two light beams out of the diffracted light pass through the pupil of the projection optical system (projection lens). In order to approach the limit resolution, it is necessary that the two light beams pass through as far as possible in the pupil of the projection optical system. FIG. 16 shows a state in which two light beams (0th-order light and + 1st-order light) pass through positions as far apart as possible in the pupil of the projection optical system.

  When the limit resolution (P) of the pitch is expressed using the coherence degree (coherence factor) (σ) of the illumination optical system as a parameter, the following equation (2) is obtained.

The limiting resolution is often described with respect to the normal line width. When the widths of the line (L) and the space (S) of the L / S pattern are equal, R = 0.5P. Therefore, the limit resolution (R) for the line width is rewritten by the following equation (3): It is represented by

Further, assuming that the value of the degree of coherence (σ) can be increased to the limit (= 1), the final limit resolution (R) is represented by a constant k ₁ = 0.250. That is, the limit resolution (R) satisfies the following formula (4).

As can be imagined from the arrangement of the light sources in FIG. 16, the most effective illumination shape for forming an L / S pattern close to the limit resolution is dipole illumination.
(2) Limit resolution of hole array Similar to the L / S pattern, the diffracted light generated from the hole array pattern of equal intervals and infinite repetition is at regular intervals with respect to the sin θ _x axis and the sin θ _y axis. With respect to the x-axis direction, the interval between the m-order light and the (m + 1) -order light is λ / P _x , and with respect to the y-axis direction, the interval between the n-order light and the (n + 1) -order light is λ / P _y (see FIG. 17). ). Further, the amplitude (Am, n) of the combination (m, n) order light of the m-order light in the x-axis direction and the n-order light in the y-axis direction is _expressed by the following equation (5).

In the above equation (5), w _x and w _y represent the hole size (nm) in the x-axis direction and y-axis direction, respectively, and P _x and P _y represent the pitch (nm) in the x-axis direction and y-axis direction, respectively. .

  In order to form an interference pattern (optical image) on the wafer surface, it is necessary that at least two light beams pass through the pupil of the projection optical system in both the x-axis direction and the y-axis direction. In order to approach the limit resolution, it is necessary that the three light beams pass through positions as far apart as possible in the pupil of the projection optical system. In FIG. 18, three light beams ((0,0) order light, (0, + 1) order light, (+1,0) order light) pass through positions as far as possible in the pupil of this projection optical system. The state to do is shown.

Here, a hole array having an isotropic density in both the x-axis direction and the y-axis direction is assumed, and P _x = P _y = P.

  From FIG. 18, the limit resolution (P) of the pitch is expressed by the following equation (6) using the degree of coherence (σ) of the illumination optical system as a parameter.

As in the case of the L / S pattern, the limit resolution is usually described with respect to the hole diameter instead of the pitch. Assuming that the hole diameter is an isotropic hole array in the x-axis direction and the y-axis direction, the critical resolution (R _x = R _y = R) is obtained when the hole width and the space width of the hole array pattern are equal. Since = 0.5 P, the equation (6) can be rewritten and expressed as the following equation (7).

Further, assuming that the value of the degree of coherence (σ) can be increased to the limit (= 1), the final limit resolution (R) is represented by a constant k ₁ = 0.354. This value is equal to √2 times the L / S pattern. That is, the limit resolution (R) satisfies the following equation (8).

As can be imagined from the arrangement of the light sources in FIG. 18, the most effective illumination shape for forming a hole array pattern close to the limit resolution is to arrange the light sources near the four vertices of a non-tilted rectangle (or square). Quadrupole lighting.
(3) Comparison of limit resolution between L / S pattern and hole array pattern When a portion corresponding to k ₁ in the expressions (3) and (7) representing the limit resolution is taken out, the following expression ( 9), and the hole array pattern can be written as in equation (10).

Accordingly, when the coherence degree (σ) is taken on the horizontal axis and the k ₁ factor is taken on the vertical axis, the graph is shown in FIG.

From the graph of FIG. 19, when the coherence degree (σ) is 0, the k ₁ factor indicating the limit resolution is 0.5 for both the L / S pattern and the hole array pattern, whereas the coherence degree (σ) When 1 is 1, it can be seen that the difference is wide between k ₁ = 0.250 of the L / S pattern and k ₁ = 0.354 of the hole array pattern.

Thus, increasing the degree of coherence (σ), that is, increasing the maximum NA (iNA) of the illumination system has the effect of reducing the k ₁ factor for both the L / S pattern and the hole array pattern. However, the effect is larger in the L / S pattern than in the hole array pattern, and a difference of {square root over (2)} is produced in the final (σ = 1).

Therefore, until now, it has been considered difficult to realize exposure for producing a hole array pattern that is as dense as the L / S pattern, in other words, having a small k ₁ factor.

On the other hand, in order to manufacture microdevices such as higher-density DRAMs and flash memories, it is indispensable to create a hole array pattern with a higher density, and to manufacture a hole array pattern with a higher density. The advent of (Low-k ₁ ) lithography technology has been highly anticipated.

As a result of intensive studies such as repeatedly performing various simulations etc. in order to make it possible to produce a hole array pattern with a higher density, the inventor has found the same density (as in the L / S pattern) under certain lighting conditions. It was found that exposure for producing a hole array pattern can be realized with the same k ₁ ).

  The above-mentioned certain illumination condition means that the light quantity distribution on the pupil plane of the illumination optical system (and the plane conjugate to this (including the pupil plane of the projection optical system)) is a light quantity distribution as shown in FIG. Cross pole lighting conditions. This cross pole illumination condition is a dipole X illumination condition suitable for resolving an L / S pattern composed of a plurality of V lines with the X-axis direction as a periodic direction (FIG. 20B shows the pupil plane of the illumination optical system ( 20) and a dipole Y illumination condition suitable for resolving an L / S pattern composed of a plurality of H lines with the Y-axis direction as a periodic direction (FIG. 20 (FIG. 20 ()). It is considered that C) is combined with the pupil plane (and the conjugate plane) of the illumination optical system.

The inventor pondered based on the result that exposure for producing a hole array pattern is possible with the same density (the same k ₁ ) as the L / S pattern under the above-mentioned cross pole illumination conditions. As a result, the following conclusions were reached.

  If the condition that “one point light source must form a hole array pattern” is given, the above-mentioned FIG. 18 shows the arrangement of light sources that form the limit resolution. correct. However, in practice, the above conditions are not indispensable for forming the hole array pattern. “Each point light source only needs to form an L / S pattern. It is sufficient to use a mild condition that it is only necessary to finally become a hole array.

Therefore, under this condition, the same k ₁ factor limit resolution as the L / S pattern can be applied to the hole array pattern. The inventor conducted further research based on these conclusions.

  SUMMARY OF THE INVENTION The present invention has been made under such circumstances. From the first viewpoint, the present invention is an exposure method for forming a hole array by exposing an object coated with a photosensitive agent on the surface, and includes cross-pole illumination conditions. A first exposure comprising: illuminating a mask on which a predetermined pattern is formed; exposing the object with light emitted from the mask through a projection optical system; and forming a hole array on the object. Is the method.

According to this, a mask on which a predetermined pattern is formed is illuminated under cross-pole illumination conditions, an object is exposed through the projection optical system with light emitted from the mask, and a hole array is formed on the object. To do. For this reason, the same k ₁ factor limit resolution as that of the L / S pattern can be applied to the hole array pattern, thereby making it possible to manufacture a hole array having a higher density.

  From a second viewpoint, the present invention is an exposure method for forming a hole array pattern on an object having a surface coated with a photosensitive agent by using a projection optical system, and a chemically amplified resist as the photosensitive agent. And a step of adjusting the amount of the quenching agent contained in the resist in consideration of the contrast of the pattern image of the hole array formed on the object by the projection optical system prior to exposure. 2 is an exposure method.

  According to this, by adjusting the quenching agent as described above, an effect equivalent to that of increasing the contrast of the pattern image (aerial image) of the hole array formed on the object by the projection optical system is obtained. It becomes possible to obtain.

  Further, in the lithography process, the productivity (including yield) of highly integrated microdevices is improved by forming a hole array pattern on the object using either the first exposure method or the second exposure method. Can do.

  Hereinafter, an embodiment of the present invention will be described with reference to FIGS. FIG. 1 schematically shows the overall configuration of an exposure apparatus 100 according to an embodiment. The exposure apparatus 100 is a step-and-scan projection exposure apparatus.

  The exposure apparatus 100 includes an illumination system including a light source 10 and an illumination optical system 12, a reticle stage RST that holds a reticle R, a projection optical system PL, a wafer stage WST on which a wafer W is placed, an off-axis alignment detection system AS. And a main controller 20 or the like which is composed of a computer such as a workstation and performs overall control of the entire apparatus.

Here, an ArF excimer laser (output wavelength: 193 nm) is used as the light source 10. As the light source 10, a light source that outputs pulsed light in the vacuum ultraviolet region such as an F ₂ laser (output wavelength 157 nm), a light source that outputs pulsed light in the near ultraviolet region such as a KrF excimer laser (output wavelength 248 nm), and the like. It may be used.

  The light source 10 is actually different from a clean room in which a chamber (not shown) in which an exposure apparatus main body including an illumination optical system 12, a reticle stage RST, a projection optical system PL, a wafer stage WST, and the like is housed is installed. Is installed in a service room with a low degree of cleanliness, and is connected to the chamber via a light transmission optical system (not shown) including at least a part of an optical axis adjustment optical system called a beam matching unit (BMU). . Based on the control information TS from the main controller 20, the light source 10 is turned on / off of the output of the laser beam LB, the energy per pulse of the laser beam LB, the oscillation frequency (repetition frequency), the center The wavelength, spectrum half width, and the like are controlled.

  The illumination optical system 12 includes a cylinder lens, a beam expander, a zoom optical system (all not shown), a beam shaping / illuminance equalizing optical system 30 including an optical integrator (homogenizer) 32, an illumination system aperture stop plate 34, A first relay lens 38A, a second relay lens 38B, a fixed reticle blind 40A, a movable reticle blind 40B, an optical path bending mirror M, a condenser lens 42, and the like are provided. Here, as the optical integrator 32, a fly-eye lens, an internal reflection type integrator (such as a rod integrator), or a diffractive optical element can be used. In this embodiment, a fly-eye lens is used. Then, it is also described as “fly eye lens 32”.

  The beam shaping / illuminance uniforming optical system 30 is connected to a light transmission optical system (not shown) through a light transmission window 11. The beam shaping / illuminance equalizing optical system 30 shapes the cross-sectional shape of the laser beam LB, which is pulsed by the light source 10 and incident through the light transmission window 11, using, for example, a cylinder lens or a beam expander. The fly-eye lens 32 located on the exit end side in the beam shaping / illuminance uniformizing optical system 30 is irradiated with a laser beam whose cross-sectional shape is shaped in order to illuminate the reticle R with a uniform illumination distribution. A surface light source (secondary light source) composed of a large number of point light sources (light source images) is formed on the exit-side focal plane (substantially coincident with the pupil plane of the illumination optical system 12). Hereinafter, the laser beam emitted from the secondary light source is referred to as “illumination light IL”.

  In the vicinity of the exit-side focal plane of the fly-eye lens 32, an illumination system aperture stop plate 34 made of a disk-shaped member is disposed. On the illumination system aperture stop plate 34, a plurality of, for example, six aperture stops (spatial filters) are arranged at substantially equal angular intervals. However, in FIG. 1, only two types of aperture stops (a normal stop and a first cross-pole illumination stop described later) out of the six aperture stops are shown.

  On the illumination system aperture stop plate 34, as shown in FIG. 2, for example, an annular aperture stop (annular stop) 36A for annular illumination, an aperture stop (normal stop) 36B formed of a normal circular aperture, A total of six aperture stops, that is, four modified aperture stops 36C to 36F, which are formed by decentering a plurality of openings for the modified light source method, are formed. The modified aperture stops 36C and 36D are aperture stops for setting dipole illumination (dipole illumination) conditions. Among them, the modified aperture stop 36C is a line-and-space pattern (L / S pattern) composed of a plurality of line patterns (V patterns) in the Y-axis direction with the X-axis direction as a periodic direction (hereinafter referred to as “L / S pattern”). (Referred to as “V pattern”) is a dipole X aperture stop suitable as an illumination condition at the time of transfer, and the modified aperture stop 36D has a plurality of line patterns (H patterns) in the X axis direction with the Y axis direction as a periodic direction. The dipole Y aperture stop is suitable as an illumination condition for transferring an L / S pattern (hereinafter referred to as “L / S · H pattern”).

  The modified aperture stop 36E is a first aperture stop for setting cross pole illumination conditions suitable for transferring the hole array pattern (hereinafter referred to as “first cross pole illumination stop”), and the modified aperture stop 36F. Is a second aperture stop (hereinafter referred to as “second cross pole illumination stop”) for setting the cross pole illumination conditions suitable for transferring the hole array pattern. Here, as can be seen by comparing the aperture stops 36C and 36D with the aperture stops 36E or 36F, the cross pole illumination condition can be defined as an illumination condition that is a combination of the dipole X illumination condition and the dipole Y illumination condition.

  As shown in FIG. 1, a plurality of polarizing plates 35 are attached to the surface of the first cross pole illumination stop 36E on the + Y side (or may be the −Y side). FIG. 3 shows a state in which the first cross pole illumination stop 36E set on the optical path of the illumination light IL is viewed from the + Y side. As shown in FIG. 6, with the four openings 37e, 37f, 37g, and 37h of the first cross pole illumination stop 36E covered from the + Y side, the polarizing plates 35E, 35F, 35G, and 35H are the first cross. It is integrally attached to the pole illumination stop 36E (illumination system aperture stop plate 34). The polarization directions of the polarizing plates 35E and 35G are respectively shown by arrows in FIG. 3 in the state of being set on the optical path, the uppermost end of the circumference centered on the optical axis IX of the illumination optical system 12, and the highest The tangential direction at the right end, that is, the X-axis direction is set, and the polarization directions of the polarizing plates 35F and 35H are respectively the rightmost end and the leftmost end of the circumference centered on the optical axis IX as indicated by arrows in FIG. Is set in the tangential direction at Z, that is, in the Z-axis direction. Accordingly, the illumination light emitted from the openings 37e and 37g of the first cross-pole illumination stop 36E provided on the illumination system aperture stop plate 34 is linearly polarized light substantially parallel to the X-axis direction and is emitted from the openings 37f and 37h. The illumination light to be applied becomes linearly polarized light in a direction substantially parallel to the Z-axis direction (Y-axis direction on the surface of the wafer W).

  Although not shown in FIG. 1, a plurality of polarizing plates are also attached to the surface on the + Y side (or on the −Y side) of the second cross pole illumination stop 36F. FIG. 4 shows a state in which the second cross pole illumination stop 36F set on the optical path of the illumination light IL is viewed from the + Y side. The second cross-pole illumination stop 36F covers the four openings 37i, 37j, 37k, and 37l from the + Y side, and the polarizing plates 35I, 35J, 35K, and 35L serve as the second second cross-pole illumination stop 36F (illumination system). It is integrally attached to the aperture stop plate 34).

  The polarization directions of the polarizing plates 35I and 35K are set in the radial direction of the circumference around the optical axis IX, that is, in the Z-axis direction in the state of setting on the optical path, as indicated by arrows in FIG. The polarization directions of the polarizing plates 35J and 35L are set in a radial direction around the optical axis IX, that is, in the X-axis direction, as indicated by arrows in FIG. Accordingly, the illumination light emitted from the openings 37i and 37k of the second cross-pole illumination stop 36F provided on the illumination system aperture stop plate 34 is substantially parallel to the Z-axis direction (Y-axis direction on the surface of the wafer W). The illumination light emitted from the openings 37j and 37l is linearly polarized light substantially parallel to the X-axis direction.

  Returning to FIG. 1, the illumination system aperture stop plate 34 is rotated around a rotation shaft 34 a by driving a drive device 39 such as a motor controlled by a control signal MLC from the main control device 20 shown in FIG. 1. Any one of the aperture stops 36A to 36F is selectively set on the optical path of the illumination light IL, whereby the shape and size of the secondary light source on the pupil plane (the light intensity distribution of the illumination light) is circular. , Ring zone, second or fourth. In the present embodiment, the illumination system aperture stop plate 34 is used to determine the illumination light quantity distribution (the shape and size of the secondary light source) on the pupil plane of the illumination optical system 12, that is, the illumination condition of the reticle R. Although changed, the intensity distribution of the illumination light on the incident surface of the optical integrator (fly eye lens) 32 or the incident angle range of the illumination light is made variable to minimize the light loss caused by the change in the illumination conditions described above. It is preferable to suppress to. For this purpose, instead of or in combination with the aperture stop plate 34, for example, a plurality of diffractive optical elements that are exchanged on the optical path of the illumination optical system 12 and movable along the optical axis of the illumination optical system 12. An optical unit (molding optical system) including at least one prism (conical prism, polyhedral prism, etc.) and at least one zoom optical system is disposed between the light source 10 and the optical integrator (fly-eye lens) 32. Can be adopted. When the above-described shaping optical system is used instead of the illumination system aperture stop plate 34, it is necessary to provide a polarization state setting device that arbitrarily sets the polarization state of illumination light on the pupil plane of the illumination optical system 12 or its conjugate plane. Yes, this polarization state setting device can insert or remove a phase shifter (for example, a quarter wavelength plate, a half wavelength plate, or an optical rotator) similarly to the polarizing plate 35 described above. Alternatively, a plurality of wedge-shaped prisms disclosed in International Publication No. 2005/036619 may be used.

  A relay optical system including the first relay lens 38A and the second relay lens 38B is disposed on the optical path of the illumination light IL emitted from the illumination system aperture stop plate 34 with the fixed reticle blind 40A and the movable reticle blind 40B interposed therebetween. Yes.

  The fixed reticle blind 40A is disposed on a surface slightly defocused from the conjugate surface with respect to the pattern surface of the reticle R, and a rectangular opening that defines an illumination area on the reticle R is formed. Further, in the vicinity of the fixed reticle blind 40A (conjugate plane with respect to the pattern surface of the reticle R), the scanning direction (here, the Y axis direction which is the horizontal direction in FIG. 1) and the non-scanning direction (see FIG. A movable reticle blind 40B having openings whose positions and widths are respectively variable in the direction corresponding to the direction orthogonal to the paper surface (X-axis direction in FIG. 1). At the start and end of scanning exposure, the main controller 20 controls the illumination area on the reticle R via the movable reticle blind 40B, thereby preventing unnecessary exposure. ing.

  On the optical path of the illumination light IL behind the second relay lens 38B, there is disposed a mirror M that reflects the illumination light IL that has passed through the second relay lens 38B toward the reticle R, and the illumination light IL behind the mirror M. The condenser lens 42 is disposed on the optical path.

  In the above configuration, the entrance surface of the fly-eye lens 32, the arrangement surface of the movable reticle blind 40B, and the pattern surface of the reticle R are optically conjugate with each other, and the exit-side focal plane (illumination optics) of the fly-eye lens 32 is set. The pupil plane of the system 12 and the pupil plane of the projection optical system PL are set so as to be optically conjugate with each other.

  Briefly explaining the operation of the illumination optical system 12 configured as described above, the laser beam LB emitted by the pulse from the light source 10 is incident on the beam shaping / illuminance uniformizing optical system 30 and the cross-sectional shape thereof is shaped. The light enters the fly eye lens 32. Thereby, the secondary light source described above is formed on the exit-side focal plane of the fly-eye lens 32.

  The illumination light IL emitted from the secondary light source passes through one of the aperture stops on the illumination system aperture stop plate 34, passes through the first relay lens 38A, and has rectangular openings in the fixed reticle blind 40A and the movable reticle blind 40B. Pass through. Then, the optical path is bent vertically downward by the mirror M after passing through the second relay lens 38B, passes through the condenser lens 42, and the rectangular illumination region on the reticle R held on the reticle stage RST has a uniform illuminance distribution. Illuminate.

  On reticle stage RST, reticle R is fixed, for example, by vacuum suction. Here, reticle stage RST is moved within an XY plane perpendicular to optical axis AX of projection optical system PL (which coincides with optical axis IX of the illumination optical system described above) by a reticle stage drive system (not shown) composed of a linear motor or the like. It can be driven minutely and can be driven at a scanning speed designated in a predetermined scanning direction (Y-axis direction).

  The position of the reticle stage RST in the stage moving surface is always detected by a reticle laser interferometer (hereinafter referred to as “reticle interferometer”) 16 via the moving mirror 15 with a resolution of, for example, about 0.5 to 1 nm. . The position information (or speed information) of reticle stage RST from reticle interferometer 16 is sent to main controller 20, and main controller 20 uses a reticle stage drive system (not shown) based on the position information (or speed information). ) To move reticle stage RST.

  The projection optical system PL is disposed below the reticle stage RST in FIG. 1, and the direction of the optical axis AX is the Z-axis direction. The projection optical system PL is, for example, a double-sided telecentric reduction system, and includes a plurality of lens elements (not shown) having a common optical axis AX in the Z-axis direction. Further, as the projection optical system PL, one having a projection magnification β of, for example, 1/4, 1/5, or 1/8 is used. Therefore, as described above, when the illumination area on the reticle R is illuminated by the illumination light (exposure light) IL, the pattern formed on the reticle R is reduced by the projection magnification β by the projection optical system PL. The image (partially reduced image) is projected and transferred onto a slit-like exposure area on the wafer W having a resist (photosensitive agent) coated on the surface.

  Wafer stage WST is disposed on a base (not shown) below projection optical system PL in FIG. 1, and wafer holder 25 is placed on the upper surface thereof. A wafer W is fixed on the wafer holder 25 by, for example, vacuum suction.

  As the wafer W, for example, a disk-shaped substrate such as a semiconductor (silicon or the like) or SOI (silicon on insulator) is used, and a chemically amplified resist as a photosensitive agent is applied to the surface (upper surface) of the substrate. ing. This resist contains a quencher. A method for adjusting the deactivator and the amount thereof will be described later.

  Returning to FIG. 1, wafer stage WST is driven in a scanning direction (Y-axis direction) and a non-scanning direction (X-axis direction) perpendicular to the scanning direction by wafer stage drive system 24 including a motor and the like. Then, by this wafer stage WST, an operation of scanning the wafer W relative to the reticle R in order to scan (scan) exposure each shot area on the wafer W, and a scanning start position for exposure of the next shot ( A step-and-scan operation that repeats the movement to the acceleration start position) is executed.

  The position of wafer stage WST in the XY plane is always detected by a wafer laser interferometer (hereinafter referred to as “wafer interferometer”) 18 through moving mirror 17 with a resolution of about 0.5 to 1 nm, for example. . Position information (or speed information) of wafer stage WST is sent to main controller 20, and main controller 20 controls driving of wafer stage WST via wafer stage drive system 24 based on the position information (or speed information). I do.

  Wafer stage WST is driven by wafer stage drive system 24 in the Z-axis direction, θx direction (rotation direction around X axis: pitching direction), θy direction (rotation direction around Y axis: rolling direction), and θz direction (Z-axis). It is also finely driven in the direction of rotation (yaw direction).

  The alignment detection system AS is disposed on the side surface of the projection optical system PL. In the present embodiment, an imaging type alignment sensor that observes street lines and position detection marks (fine alignment marks) formed on the wafer W is used as the alignment detection system AS. The detailed configuration of the alignment detection system AS is disclosed in, for example, Japanese Patent Laid-Open No. 9-219354. The observation result by the alignment detection system AS is supplied to the main controller 20.

  Further, the apparatus of FIG. 1 includes an oblique incidence type focus detection system (focus detection system) for detecting the position in the Z-axis direction (optical axis AX direction) of the exposure area on the surface of the wafer W and the vicinity thereof. A multi-point focus position detection system (21, 22) is provided. The detailed configuration of the multipoint focus position detection system (21, 22) is disclosed in, for example, Japanese Patent Laid-Open No. Hei 6-283403. The detection result by the multipoint focus position detection system (21, 22) is supplied to the main controller 20.

  Further, in the exposure apparatus 100 of the present embodiment, although not shown, a reticle mark on the reticle R and a reference mark plate provided on the wafer stage WST via the projection optical system PL above the reticle R. A pair of reticle alignment systems comprising a TTR (Through The Reticle) alignment optical system using an exposure wavelength for simultaneously observing the upper reference mark is provided. As these reticle alignment systems, for example, those having the same configuration as that disclosed in Japanese Patent Laid-Open No. 7-176468 are used.

  Next, the exposure operation by the exposure apparatus 100 of this embodiment will be briefly described. Here, it is assumed that the exposure of the first layer on the wafer W has already been completed and the second and subsequent layers are exposed.

a. First, main controller 20 loads reticle R having a circuit pattern formed on reticle stage RST via a reticle loader (not shown).

b. Next, main controller 20 uses reticle R based on information on reticle R read by a bar code reader (not shown) during the transfer of reticle R onto reticle stage RST. A control signal MLC is supplied to the drive device 39 in order to set an optimal illumination condition for exposure. Thereby, the illumination system aperture stop plate 34 is rotated about the rotation axis 34a by the drive device 39, and the optimum illumination condition for the exposure of the reticle R is set.

c. Next, main controller 20 performs reticle alignment using the above-described reticle alignment system and a reference mark plate (not shown), and baseline measurement using alignment detection system AS and the reference mark plate in the same manner as a normal scanning stepper. Follow the procedure.

d. Next, main controller 20 performs wafer exchange on wafer stage WST via a wafer loader (not shown) (however, if no wafer is loaded on wafer stage WST, the wafer is simply loaded).

e. Next, main controller 20 performs alignment on wafer W (for example, EGA wafer alignment). As a result of this wafer alignment, the arrangement coordinates of a plurality of shot areas on the wafer W are obtained with high accuracy.

f. Next, main controller 20 moves wafer stage WST to a scanning start position (acceleration start position) for exposure of each shot area on wafer W based on the result of the wafer alignment described above, and a reticle. A step of repeating the operation of irradiating the reticle R with the illumination light IL and transferring the pattern on the reticle R to the shot area on the wafer W while synchronously scanning the stage RST and the wafer stage WST in the Y-axis direction. • Perform an AND-scan exposure.

g. During the relative scanning, particularly during scanning exposure, information on the XY position of reticle stage RST detected by reticle interferometer 16, position information on wafer stage WST detected by wafer interferometer 18, and multipoint focus position Based on the Z position and leveling information of the wafer W detected by the detection system (21, 22), the reticle is controlled by the main controller 20 so that the positional relationship between the reticle stage RST and the wafer stage WST is properly maintained. Position control of stage RST and wafer stage WST is performed.

  Therefore, when exposure on the wafer W is completed, a pattern image on the reticle R is accurately formed in each of a plurality of shot areas on the wafer W.

  By the way, when a hole array is formed on a wafer, a reticle on which a hole array pattern is formed is used. In the present embodiment, two types of reticles are used when forming the hole array.

<< First exposure method >>
First, exposure is performed when a hole array is formed on a wafer W using a reticle R1 formed of a binary mask in which a hole array pattern is formed in a matrix arrangement as shown in FIG. Will be described.

  In the pattern area of the reticle R1, a hole array pattern is formed which is a 65 nm square (converted value on the wafer) pattern of a square matrix arrangement with a pitch p of 130 nm (converted value on the wafer).

  First, the a. In this process, reticle R1 is loaded onto reticle stage RST by the reticle loader under the control of main controller 20.

  Next, b. In this step, an illumination system aperture is set by the drive device 39 based on an instruction from the main controller 20 in order to set an optimal illumination condition for exposure using the reticle R1, here the first cross pole illumination condition. The aperture plate 34 is rotated, and the aperture stop 36E is set on the optical path of the illumination light IL.

  Next, c. And d. The operation of the process is performed, e. In this process, the pattern of the reticle R1 is transferred to each shot area on the wafer W by the step-and-scan method. At this time, the pattern region on the reticle R1 is cross-pole illumination conditions and Azimuthal polarized light (linearly polarized light whose polarization direction is a tangential direction on the illumination optical system pupil plane (a direction orthogonal to the radiation direction on the pupil plane)). Illuminated by the illumination light IL. Therefore, in the exposure using the reticle R1, the L / S · V pattern is formed under the dipole X illumination condition and the L / S · H pattern is formed under the dipole Y illumination condition. Since the diffracted light contributing to the image, that is, all the light that interferes with the two light beams becomes S-polarized light (TE-polarized light) on the wafer W surface, an image with a very good contrast of the hole array pattern (latent image) is formed on the wafer W. ) Is formed.

  Then, after the exposure is completed, the wafer W is developed by a coater / developer (not shown), and ArF excimer laser light and NA0.92 projection optical system are used on the surface of the wafer W to achieve a good resolution. Thus, a resist image (an image with good contrast) of a hole array pattern having a hole size of 65 nm and a pitch of 130 nm is formed.

  Hereinafter, based on the simulation and the result, the theoretical support that the hole array pattern having a high density as described above can be formed in the present embodiment will be described.

First, with an exposure apparatus having an exposure wavelength (λ) = 193.306 nm, a numerical aperture (NA) = 0.92 of the projection optical system, and an illumination system maximum σ = 0.97, a 65 nm hole (pitch: 130 nm) is formed on the wafer. A simulation in the case of forming will be described. When the k ₁ factor is calculated under this condition, k ₁ = 0.309, which is smaller than 0.354, and exposure is impossible under the above-described quadrupole illumination condition used for exposure of the conventional hole array pattern. .

  FIG. 5B shows an object spectrum (diffracted light) corresponding to the reticle R1 in FIG. 5A, and FIG. 5C shows the illumination system design solution.

As in the case of FIG. 17 described above, from the hole array pattern, as shown in FIG. 5B, a spectrum ((m, n) order diffracted light) is generated at the apex of the square lattice, and the interval is λ / P _x = λ / P _y = λ / P.

  In this case, the value of λ / P is 1.487 on the sin θ scale. Therefore, the optimum position of the cross pole is 1.487 / (2 × 0.92) = 0.008 on the σ scale (scale normalized to NA = 1). Here, the optimum position means that the 0th-order light and the + 1st-order light (or 0th-order light and −1st-order light) are incident on the wafer surface at the same incident angle in order to minimize the image collapse when defocused. This refers to the condition (light source position) that can be reached. The size of each light source is advantageously as small as possible from the viewpoint of imaging performance alone, but in an actual exposure apparatus, it is determined by the balance between the damage of the glass material used in the illumination optical system and the amount of light. Here, it is assumed that σ = 0.120 (radius).

  FIG. 6A shows a contour map of the aerial image of the pattern on the reticle R1 formed under irradiation with illumination light of Azimuthal polarization under cross-pole illumination conditions, and FIG. The aerial image intensity corresponding to the cross section A in FIG. 6A is shown, and the aerial image intensity corresponding to the B cross section in FIG. 6A is shown in FIG. As can be seen from FIGS. 6A to 6C, the formed spatial image is formed by the L / S · V pattern formed by the illumination equivalent to the dipole X and the illumination equivalent to the dipole Y. It is made up of a non-coherent overlay with the L / S · H pattern. For this reason, an image (a dark place) obtained by inverting the same shape as a hole image (a bright place) of the A cross section is generated at the position of the B cross section.

  FIG. 7A shows a contour map of the aerial image of the pattern on the reticle R1 formed under cross-pole illumination conditions and by irradiation with non-polarized illumination light, and FIG. The aerial image intensity corresponding to the A cross section of FIG. 7A is shown, and the aerial image intensity corresponding to the B cross section of FIG. 7A is shown in FIG. 7C.

  Further, FIG. 8A shows a contour map of a spatial image of a pattern on the reticle R1 formed under irradiation of irradiation light with radial polarization under cross-pole illumination conditions, and FIG. FIG. 8A shows the aerial image intensity corresponding to the A cross section of FIG. 8A, and FIG. 8C shows the aerial image intensity corresponding to the B cross section of FIG. 8A.

  As can be seen from FIGS. 6A to 8C, the L / S · V pattern is formed by dipole X illumination and the L / S · H pattern is formed by dipole Y illumination. In view of this, the image of Azimuthal polarization illumination in which S-polarized light is incident on the wafer surface has the best contrast.

  As a result of performing a simulation of exposure in the case of forming a 57 nm hole array pattern under the same conditions as described above, the same results as described above were obtained although details are omitted. However, the contrast of the Azimuthal polarized illumination image with the best contrast was somewhat lower than that of the 65 nm hole array image. The reason for this is considered to be that the illumination light source could not be placed at an optimal position due to the limitation of the maximum illumination σ described below.

That is, in the case of a 57 nm hole array pattern, since the pitch is 114 nm, the interval (λ / P _x = λ / P _y = λ / P) of the spectrum ((m, n) order diffracted light) generated at the apex of the square lattice is The sin θ scale is 1.696. Therefore, the optimal position of Cross Pole is 1.696 / (2 × 0.92) = 0.922 on the σ scale. However, when the size of each light source is limited to a minimum value (σ = 0.120) and a light source of σ = 0.120 is arranged at a position of σ = 0.922, the maximum value of illumination σ is 0. .97, the light source cannot be arranged at the optimum position of σ = 0.922. For this reason, the light source is inevitably arranged at the outermost position within the limit, that is, at the position of σ = 0.850.

<< Second exposure method >>
Next, as shown in FIG. 9A, a hole array is formed on the wafer W using a reticle R2 made of a chromeless mask in which a hole array pattern is formed in a matrix arrangement in the pattern region. The case of exposure will be described.

  In the pattern area of the reticle R2, the 100% transmission glass portion whose phase is 0 shown by a white square in FIG. 9A and the phase shown by a filled square in FIG. 9A are shifted by π. The 100% transparent glass portions (formed by, for example, digging glass) are arranged alternately and densely to form a hole array pattern that forms one matrix as a whole. The black portion around the hole array pattern represents a chromium material with zero transmittance. Although named “chromeless mask”, a wide area where no pattern exists is often shielded from light by chrome. In this case, one side (converted value on the wafer) of the white square and the filled square is set to be equal to the pitch (Px = Py = P) of the hole array to be created.

  First, the a. In this step, reticle R2 is loaded on reticle stage RST by the reticle loader under the control of main controller 20.

  Next, b. In this step, an illumination system aperture is set by the drive device 39 based on an instruction from the main controller 20 in order to set an optimal illumination condition for exposure using the reticle R2, here the second cross-pole illumination condition. The aperture plate 34 is rotated, and the aperture stop 36F is set on the optical path of the illumination light IL.

  Next, c. And d. The operation of the process is performed, e. In this process, the pattern of the reticle R2 is transferred to each shot area on the wafer W by the step-and-scan method. At this time, the pattern region on the reticle R2 is illuminated with illumination light IL of radial polarization (linearly polarized light with the radiation direction (radial direction) in the illumination optical system pupil plane as the polarization direction) under cross-pole illumination conditions. . For this reason, during exposure using the reticle R2, diffracted light that contributes to image formation, that is, all light that interferes with two light beams becomes S-polarized light (TE-polarized light) on the wafer W surface. An image (latent image) having a very good contrast of the hole array pattern is formed.

  Then, after the exposure is completed, the wafer W is developed by a developer (not shown), and it is difficult to achieve a good resolution conventionally by using ArF excimer laser light and NA 0.92 projection optical system on the surface of the wafer W. Thus, a hole array pattern resist image (an image with good contrast) having a hole size of 65 nm and a pitch of 130 nm is formed.

  Hereinafter, based on the simulation and the result, the theoretical support that the hole array pattern having a high density as described above can be formed in the present embodiment will be described.

  FIG. 9B shows an object spectrum (diffracted light) generated from the reticle R2. As shown in FIG. 9B, in the case of a chromeless mask, unlike a binary mask (including a halftone type phase shift mask), (+1, +1) order, (-1, +1) order, Spectra are generated only in the (−1, −1) -order and (+1, −1) -order four directions. The reason for this will be described below.

  The pattern of the reticle R2 in FIG. 9A can be decomposed into four binary mask patterns whose layouts are shown in FIGS. 10A to 10D.

  Here, the pattern of FIG. 10A is a component of odd-numbered rows and odd-numbered columns of the matrix of the hole array pattern of FIG. 9A (the row direction is the Y direction and the column direction is the X direction). This is a binary mask pattern obtained by extracting a phase 0 pattern.

  The pattern 10 (B) is a binary mask pattern obtained by extracting the phase 0 pattern, which is a component of the even-numbered rows and even-numbered columns, of the matrix of the hole array pattern of FIG. 9 (A).

  The pattern in FIG. 10C is a binary mask pattern obtained by extracting the pattern of phase π, which is a component of the odd rows and even columns in the matrix of the hole array pattern in FIG. 9A.

  The pattern of FIG. 10D is a binary mask pattern obtained by extracting the pattern of phase π, which is a component of the even-numbered rows and odd-numbered columns, of the hole array pattern matrix of FIG. 9A.

  When the object spectrum (diffracted light) of the mask patterns in FIGS. 10A, 10B, 10C, and 10D is calculated, FIG. 11A, FIG. 11B, and FIG. It becomes like FIG. 11 (C) and FIG. 11 (D).

  9A and 10A to 10D, one side (converted value on the wafer) of the hole pattern indicated by the white square and the filled square is the pitch of the hole array to be created (Px = Py = P), and the pitch of each mask pattern in FIGS. 10A to 10D is twice the pitch of the hole array to be created, so that the diffracted light is the object spectrum in FIG. 5B. Compared with (diffracted light), it occurs at a distance of 1/2. The amplitudes of the (m, n) order diffracted light generated from the mask patterns of FIGS. 10A to 10D are the same, but the phase of the glass transmission part is 0, π, or even rows. The sign is reversed depending on whether it is an odd row or an even or odd column. In FIGS. 11A to 11D, the filled squares indicate positive (+) diffracted light, and the black squares indicate negative (−) diffracted light.

  Table 1 below summarizes the signs of the (m, n) -order diffracted light generated from the mask patterns of FIGS. 10A to 10B and the combined result.

As described above, the pattern of reticle R2 in FIG. 9A can be decomposed into four binary mask patterns whose layouts are shown in FIGS. The mask pattern layouts are added together), and the operation for generating diffracted light from each pattern layout (ie, Fourier transform) results in a linear combination. Addition is also established. As a result, as shown in Table 1, only four diffracted lights of (-1, -1) order, (-1, +1) order, (+1, -1) order, (+1, +1) order remain. I understand that.

  Here, an exposure apparatus having an exposure wavelength (λ) = 193.306 nm, a numerical aperture (NA) of the projection optical system = 0.92, and an illumination system maximum σ = 0.97 is used, and is 65 nm on the wafer using the reticle R2. A simulation for forming holes (pitch: 130 nm) will be described.

  The illumination system design solution (light source arrangement (optimum solution)) in this case is the same as that of the reticle R1 including the binary mask described above.

  FIG. 12A shows a contour map of the aerial image of the pattern on the reticle R2 formed by irradiation with illumination light of Azimuthal polarization under cross-pole illumination conditions, and FIG. The aerial image intensity corresponding to the A cross section in FIG. 12A is shown, and the aerial image intensity corresponding to the B cross section in FIG. 12A is shown in FIG. As can be seen from FIGS. 12A to 12C, the formed spatial image is formed by the L / S · H pattern formed by the illumination equivalent to the dipole X and the illumination equivalent to the dipole Y. It is made up of a non-coherent overlay with the L / S · V pattern. For this reason, an image (a dark place) obtained by inverting the same shape as a hole image (a bright place) of the A cross section is generated at the position of the B cross section.

  In this case, as shown in FIG. 9B, when light is incident on the point O, the (−1, −1) order, (−1, +1) order, (+1, −1) order, (+1) , + 1) Since the next-order diffracted light is generated in directions of 45 degrees and 135 degrees when viewed from the point O, unlike the case of the binary mask, an aerial image of the L / S · H pattern is obtained with illumination equivalent to the dipole X. The L / S · V pattern is formed by illumination equivalent to the dipole Y.

  FIG. 13A shows a contour map of the aerial image of the pattern on the reticle R2 formed under irradiation with unpolarized illumination light under cross-pole illumination conditions, and FIG. The aerial image intensity corresponding to the A cross section of FIG. 13A is shown, and the aerial image intensity corresponding to the B cross section of FIG. 13A is shown in FIG.

  Further, FIG. 14A shows a contour map of a spatial image of a pattern on the reticle R2 formed under irradiation with irradiation light of radial polarization under cross-pole illumination conditions, and FIG. Shows the aerial image intensity corresponding to the A cross section of FIG. 14A, and FIG. 14C shows the aerial image intensity corresponding to the B cross section of FIG.

  As can be seen from FIGS. 12A to 14C, the L / S · H pattern is formed by the illumination system equivalent to the dipole X, and the L / S · V pattern is obtained by the illumination equivalent to the dipole Y. Therefore, the image of the radially polarized illumination in which the S-polarized light is incident on the wafer surface has the best contrast.

  As a result of performing a simulation of exposure in the case of forming a 57 nm hole array pattern under the same conditions as described above, the same results as described above were obtained although details are omitted. However, the contrast of the radial polarized illumination image with the best contrast was somewhat lower than the image of the 65 nm hole array described above. The reason for this is considered to be that the illumination light source could not be arranged at the optimum position due to the limitation of the maximum illumination σ as in the case of the binary mask described above.

  By the way, for a semiconductor device (for example, a memory such as a D-RAM or a flash memory), a process for designing the function and performance of the device and a reticle (including the reticles R1 and R2 described above) based on the design process are manufactured. A process for manufacturing a wafer from a silicon material, a wafer processing process including a lithography process including exposure by the exposure apparatus of this embodiment, a device assembly process (including a dicing process, a bonding process, and a package process), an inspection step, and the like. It is manufactured after.

  The lithography step includes an exposure step including a step of transferring a reticle pattern onto the wafer by the first exposure method (or second exposure method) using the reticle R1 (or R2), and the wafer following the exposure. And a post-exposure bake (PEB) for promoting the catalytic reaction after exposure of the chemically amplified resist, and a development step for developing the wafer.

  Next, although the description will be somewhat different, in this embodiment, adjustment (control) of the amount of quencher contained in the chemically amplified resist applied on the wafer W will be described.

  As can be seen from the above description, the image formation of the hole array by the first exposure method and the second exposure method overlaps the images of the L / S patterns orthogonal to each other in a non-interfering manner, so that half pitch A valley having the same depth as the height of the mountain (with respect to the intensity of the aerial image) is generated at the shifted position. Therefore, even under ideal conditions, the peak of the peak = 1.0, the intermediate value = 0.5, the bottom of the valley = 0.0 (both are relative values), and the side on which the hole array is formed It can be seen that the contrast of the image is expressed by the following formula (11) and cannot exceed 0.333.

As described above, on the exposure apparatus side, the contrast cannot be increased to 0.333 or more, but the contrast of the aerial image is increased by controlling the amount of Quencher (deactivator) contained in the chemically amplified resist. It is possible to obtain the same effect as the above.

More specifically, in the case of using a chemically amplified resist, the following reaction exists between the steps of exposure → post exposure bake (PEB) → development.
(1) In the exposure process, acid is generated from Photo Acid Generator (PGA) by photochemical reaction by exposure light.
(2) In the PEB process, the acid generated in the exposure process reacts with Dissolution Inhibitor (DI), which is a resist image forming substance, and a portion that is easily dissolved in the developer is formed in the resist. In this reaction, the acid acts as a catalyst (ie, the acid does not increase or disappear). In addition, since the acid diffuses due to heat (about 130 ° C.) during the PEB process, the acid concentration distribution in the PEB process is generally not constant, and gradually (with the lapse of PEB time), the concentration distribution is not sharp. .
(3) In the development process, the developer comes into contact with the portion of the resist formed in the PEB process that is easily dissolved in the developer, and gradually dissolves to form a final resist image.

  Therefore, in the case of creating the hole array in the present embodiment, the amount of the quenching agent is set to the peak of the aerial image peak shown in FIG. 6 (B), FIG. 14 (B), and the like. Control is made so that it is exactly in the middle of the bottom of the valley of the aerial image shown in 14 (C). As a result, “there is no part where the valley of the aerial image is formed”, and it is possible to handle the PEB process and the development process as in the case of forming the conventional hole array.

As described above, according to the present embodiment, when the hole array is manufactured, the first exposure method or the second exposure method is performed, and the reticle R1 or R2 is illuminated under the cross-pole illumination condition. Then, the wafer W is exposed to light emitted from the reticle R1 or R2 via the projection optical system PL, and a hole array is formed on the wafer W. For this reason, the same k ₁ factor limit resolution as that of the L / S pattern can be applied to the hole array pattern, thereby making it possible to manufacture a hole array having a higher density.

  Further, according to this embodiment, the contrast of the hole array pattern image (aerial image) formed on the wafer W by the projection optical system PL is increased by adjusting the quenching agent as described above. It is possible to obtain the same effect as.

In the above embodiment, a first exposure method for forming a hole array pattern using a binary mask with cross pole illumination conditions and Azimuthal polarization illumination, a hole array using a chromeless mask with cross pole illumination conditions and radial polarization illumination. Although the second exposure method for forming a pattern has been described, the present invention is not limited to this, and a hole array pattern is formed by performing exposure under cross-pole illumination conditions and non-polarized illumination regardless of whether it is a binary mask or a chromeless mask. Also good. Even in such a case, the hole array pattern can be formed on the wafer by exposure using a small k ₁ factor equivalent to that at the time of forming the line space pattern, as in the above embodiment (FIG. 7B). , See FIG.

  Moreover, in the said embodiment, although the case where the content of the quencher in the resist mentioned above was adjusted with the said 1st exposure method or the 2nd exposure method was demonstrated, adjustment of this quencher is It is not always necessary.

  Prior to exposure, the step of adjusting the amount of the quenching agent contained in the chemically amplified resist in consideration of the contrast of the pattern image of the hole array formed on the object such as a wafer by the projection optical system is The method is not limited to the first and second exposure methods described above, and may be executed in combination with exposure for forming other hole arrays. Even in such a case, the contrast of the image of the hole array pattern formed on an object such as a wafer can be substantially increased.

  In the above-described lithography process, by performing the processing of the above-described embodiment or the processing of various modifications as described above, it is possible to form a hole array having a higher density than the conventional one on the wafer. Therefore, it becomes possible to manufacture an electronic device having a higher density than the conventional one.

  In the above embodiment, the description has been given of the case where the polarizing plate is integrally provided on the exit side of each aperture stop 36E, 36F of the illumination system aperture stop plate 34. However, the present invention is not limited to this. For example, the aperture stop 36E is illuminated. When installing on the optical path of the light IL, another large polarizing plate is disposed between the fly-eye lens 32 and the illumination system aperture stop plate 34, and for example, part or all of the apertures 37e to 37h of the aperture stop 36E. A half-wave plate may be arranged to adjust the rotation angle of each half-wave plate.

  For example, when each of the aperture stops 36A to 36F is illuminated with linearly polarized illumination light by using a laser light source that emits a linearly polarized laser beam as the light source, for example, the aperture stops 36E and 36F. It is only necessary to provide a half-wave plate with an appropriate rotation direction in part or all of each opening. In this case, only half-wave plates may be provided in some openings, but providing half-wave plates in all openings is more effective in reducing variation in illumination. Thus, when the polarization direction is adjusted using the half-wave plate, the illumination efficiency is good because there is no loss of illumination light. In this case, for example, an optical rotator (image rotator) may be used in addition to the half-wave plate.

  In the above embodiment, the case of using a reticle as a mask has been described. However, the present invention is not limited to this. For example, a DMD (Digital Micro-mirror Device) which is a kind of non-light-emitting image display element (also referred to as a spatial light modulator) is used. You may use the variable shaping | molding mask (electronic mask) containing. The object to be exposed is not limited to a wafer, and may be a glass plate, for example.

Further, the light source 10 of the exposure apparatus of the above embodiment is not limited to an ultraviolet pulse light source such as an F ₂ laser light source, an ArF excimer laser light source, or a KrF excimer laser light source, but g-line (wavelength 436 nm), i-line (wavelength 365 nm). It is also possible to use an ultra-high pressure mercury lamp that emits a bright line such as. In addition, a single wavelength laser beam oscillated from a DFB semiconductor laser or fiber laser is amplified by, for example, a fiber amplifier doped with erbium (or both erbium and ytterbium), and a nonlinear optical crystal is obtained. It is also possible to use harmonics that have been converted into ultraviolet light. The magnification of the projection optical system may be not only a reduction system but also an equal magnification or an enlargement system.

  In the above embodiment, the case of a scanning exposure apparatus has been described. However, the present invention is not limited to a step-and-repeat machine, a step-and-scan machine, a step-and-scan machine, and the like, as long as the exposure apparatus includes a projection optical system.・ It can be applied to any stitching machine. The present invention can also be applied to a twin stage type exposure apparatus having two wafer stages. Furthermore, the present invention is also applied to an immersion type exposure apparatus disclosed in, for example, International Publication No. 2004/053955 pamphlet and the like in which a liquid (for example, pure water) is filled between the projection optical system PL and the wafer. Can do.

  The exposure method and device manufacturing method of the present invention are suitable for manufacturing a microdevice such as a memory, for example, a D-RAM or a flash memory.

1 is a drawing schematically showing an overall configuration of an exposure apparatus 100 according to an embodiment. FIG. 2 is a front view showing the illumination system aperture stop plate of FIG. 1 as viewed from the −Y direction. It is a figure which shows the state which looked at the 1st cross pole illumination stop set on the optical path of illumination light from the + Y side. It is a figure which shows the state which looked at the 2nd cross pole illumination stop set on the optical path of illumination light from the + Y side. 5A shows a reticle R1 made of a binary mask on which a hole array pattern is formed, and FIG. 5B shows an object spectrum (diffracted light) corresponding to the reticle R1 in FIG. 5A. FIG. 5C is a diagram showing the light source arrangement of the illumination system design solution. 6A is a contour diagram of the aerial image of the hole array pattern on the reticle R1 formed under irradiation of illumination light with Azimuthal polarization under cross-pole illumination conditions, and FIG. 6B is a diagram of FIG. FIG. 6C is a diagram showing the aerial image intensity corresponding to the A cross section A of FIG. 6A, and FIG. 6C is a diagram showing the aerial image intensity corresponding to the B cross section of FIG. FIG. 7A is a contour map of the aerial image of the hole array pattern on the reticle R1 formed by irradiation with non-polarized illumination light under cross-pole illumination conditions, and FIG. FIG. 7C is a diagram showing the aerial image intensity corresponding to the A section of A), and FIG. 7C is a diagram showing the aerial image intensity corresponding to the B section of FIG. FIG. 8A is a contour map of the aerial image of the hole array pattern on the reticle R1 formed under irradiation with irradiation light of radial polarization under cross-pole illumination conditions, and FIG. FIG. 8C is a diagram showing the aerial image intensity corresponding to the A section of A), and FIG. 8C is a diagram showing the aerial image intensity corresponding to the B section of FIG. FIG. 9A shows a reticle R2 made of a chromeless mask on which a hole array pattern is formed, and FIG. 9B shows an object spectrum (diffracted light) generated from the reticle R2. FIGS. 10A to 10D are diagrams respectively showing layouts of patterns of four binary masks obtained by disassembling the pattern of reticle R2 of FIG. 9A. 11 (A), FIG. 11 (B), FIG. 11 (C), and FIG. 11 (D) are respectively the same as FIG. 10 (A), FIG. 10 (B), FIG. 10 (C), and FIG. It is a figure which shows the object spectrum (diffracted light) of a mask pattern. 12A is a contour map of a spatial image of a pattern on the reticle R2 formed by irradiation with illumination light of Azimuthal polarization under cross-pole illumination conditions, and FIG. 12B is a diagram of FIG. FIG. 12C is a diagram illustrating the aerial image intensity corresponding to the A cross section, and FIG. 12C is a diagram illustrating the aerial image intensity corresponding to the B cross section of FIG. FIG. 13A is a contour diagram of the aerial image of the pattern on the reticle R2 formed by irradiation with non-polarized illumination light under cross-pole illumination conditions, and FIG. 13B is a diagram of FIG. 13A. FIG. 13C is a diagram showing the aerial image intensity corresponding to the cross section B of FIG. 13A. FIG. FIG. 14A is a contour map of a spatial image of a pattern on the reticle R2 formed under irradiation with irradiation light of radial polarization under cross-pole illumination conditions, and FIG. 14B is a diagram of FIG. 14A. FIG. 14C is a diagram illustrating the aerial image intensity corresponding to the A cross section of FIG. 14A, and FIG. 14C is a diagram illustrating the aerial image intensity corresponding to the B cross section of FIG. It is a figure which shows the diffracted light which generate | occur | produces from the L / S pattern of equal intervals by making a horizontal axis into sin (theta) axes. It is a figure which shows the position of the light source which forms the limit resolution of a L / S pattern. It is a figure which shows the generation | occurrence | production position of the (m, n) order diffracted light from a hole array. It is a figure which shows the position of the light source which forms the limit resolution of the conventional hole array pattern. It is a figure for comparing the limit resolution of L / S and a hole array. 20A shows a light amount distribution on the pupil plane of the illumination optical system under the cross-pole illumination condition (and a plane conjugate to this (including the pupil plane of the projection optical system)), and FIG. 20B shows a dipole. FIG. 20C is a diagram showing a light quantity distribution on a pupil plane (and a plane conjugate to it) of the illumination optical system under the X illumination condition, and FIG. 20C is a pupil plane (and a plane conjugate with this) of the illumination optical system under the dipole Y illumination condition. FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 100 ... Exposure apparatus, W ... Wafer, R ... Reticle, PL ... Projection optical system.

Claims (8)

An exposure method in which a hole array is formed by exposing an object having a surface coated with a photosensitive agent,
Illuminating a mask on which a predetermined pattern is formed under cross-pole illumination conditions, exposing the object with light emitted from the mask through a projection optical system, and forming a hole array on the object Exposure method.   The exposure method according to claim 1, wherein the mask is a binary mask on which a hole array pattern is formed.   The exposure method according to claim 2, wherein the binary mask is illuminated with illumination light whose polarization direction is a direction orthogonal to a radiation direction on a pupil plane of the projection optical system.   2. The exposure method according to claim 1, wherein the mask is a chromeless mask in which a pattern corresponding to a hole array is formed.   The exposure method according to claim 4, wherein the chromeless mask is illuminated with illumination light whose polarization direction is a radiation direction on a pupil plane of the projection optical system. The photosensitive agent is a chemically amplified resist,
6. The method according to claim 1, further comprising a step of adjusting in advance an amount of the quenching agent contained in the resist in consideration of a contrast of an image formed on the object by a projection optical system. The exposure method according to item. An exposure method for forming a hole array pattern on an object having a surface coated with a photosensitive agent using a projection optical system,
A chemically amplified resist is used as the photosensitizer,
An exposure method including a step of adjusting an amount of a quenching agent contained in the resist in advance of exposure in consideration of a contrast of a pattern image of a hole array formed on the object by a projection optical system.   A device manufacturing method including a lithography step of forming a hole array pattern on an object using the exposure method according to claim 1.