JP4756380B2 - Exposure method and apparatus, and electronic device manufacturing method - Google Patents

Description

  The present invention relates to an exposure method used in a fine pattern forming process in an electronic device manufacturing process such as a semiconductor integrated circuit, a flat panel display device, a thin film magnetic head, and a micromachine, an electronic device manufacturing method using the exposure method, and The present invention relates to an exposure apparatus suitable for use in the method.

  In forming a fine pattern in a manufacturing process of an electronic device such as a semiconductor integrated circuit, a photolithography technique is generally used. This is because a photoresist (photosensitive thin film) is formed on the surface of a substrate to be processed such as a wafer, and the exposure process, the developing process, the etching process, and the like of the exposure light having a light amount distribution corresponding to the shape of the pattern to be formed, A desired pattern is formed on a substrate to be processed.

In the above-described exposure process for manufacturing a state-of-the-art electronic device, a projection exposure method is mainly used as an exposure method.
This is because a pattern to be formed is enlarged by a factor of 4 or 5 on a mask (also called a reticle), irradiated with illumination light, and the transmitted light is reduced using a reduction projection optical system. Exposure transfer is performed on a wafer.

  The fineness of the pattern that can be formed by the projection exposure method is determined by the resolution of the reduction projection optical system, which is approximately equal to the exposure wavelength divided by the numerical aperture (NA) of the projection optical system. Therefore, in order to form a finer circuit pattern, a shorter wavelength exposure light source and a higher NA projection optical system are required.

  On the other hand, there is an exposure method (hereinafter referred to as “proximity exposure method”) in which a pattern formed on a mask is exposed on a wafer without using a projection optical system. In the proximity exposure method, a mask on which a pattern to be transferred is formed at the same magnification is placed close to and opposed to the wafer, and illumination light is applied to the mask, so that the light / dark pattern of the mask is shaped as it is. Is transferred onto the wafer while maintaining

  There is also a “contact exposure method” in which illumination light is irradiated onto a mask while the same-size mask and wafer are in close contact, and the light / dark pattern of the mask is directly transferred to the wafer.

Of the conventional exposure methods described above, the projection exposure method requires a light source with a shorter wavelength and a projection optical system with a higher NA in order to obtain higher resolution.
However, in the current state-of-the-art exposure apparatus, the wavelength of exposure light is shortened to 193 nm, and further shortening of the wavelength in the future is difficult from the viewpoint of usable lens materials.

Further, the NA of the most advanced projection optical system has reached about 0.92, and it is difficult to increase the NA further, and this causes a significant increase in the manufacturing cost of the exposure apparatus.
On the other hand, in the contact exposure method, exposure is performed while bringing the mask into contact with the substrate, so that it is difficult to avoid damage and contamination of the mask due to exposure. Therefore, since the running cost accompanying mask consumption increases, it is difficult to apply to mass production.

  The proximity exposure method is effective in preventing damage to the mask because the wafer and the mask are arranged close to each other with an interval of 10 to 20 μm or more. However, since the transfer pattern is blurred due to the interval, it is difficult to apply to transfer of a fine pattern of the order of the wavelength of exposure light or less.

The present invention has been made in view of such problems, and an object of the present invention is to provide an exposure method capable of forming a fine pattern, specifically, a fine pattern having a wavelength of about the wavelength of exposure light or less at low cost.
Another object of the present invention is to provide an electronic device manufacturing method using the above exposure method, and to provide an exposure apparatus suitable for use in the above exposure method.

The first exposure method of the present invention is an exposure method in which a pattern is exposed on a photosensitive substrate with illumination light from a light source, and the first diffraction grating is irradiated with the illumination light from the light source. Irradiating the second diffraction grating disposed opposite to the first diffraction grating with the diffraction light generated by the first diffraction grating, and diffracting light generated by the second diffraction grating. Irradiating the photosensitive substrate disposed in close proximity to the second diffraction grating, and the two-dimensional as the first diffraction grating and the second diffraction grating. A diffraction grating having a period is used.
According to the first exposure method, a fine pattern having a two-dimensional cycle can be formed on a photosensitive substrate at a low cost.

Alternatively, in the first exposure method, the divergence angle of the illumination light applied to the first diffraction grating can be adjusted.
Or the divergence angle of the optical path which the said illumination light irradiated to the 1st diffraction grating can pass can also be said to be adjustable. The divergence angle can be adjusted according to the expansion and contraction of the photosensitive substrate.

  Further, in the first exposure method, the illumination light is changed by changing the intensity distribution of the illumination light applied to the first diffraction grating and the relative positional relationship with the first diffraction grating with time. The integrated intensity distribution on the first diffraction grating can be made substantially uniform in a predetermined region including the central portion of the first diffraction grating.

  Further, in the first exposure method, the relative positional relationship between the second diffraction grating and the substrate in the in-plane direction of the substrate is set in a direction orthogonal to the period direction of the second diffraction grating. The substrate can be exposed by repeating each step a plurality of times while shifting or shifting the second diffraction grating by an integral multiple of the period of the period in the direction of the period.

  In the first exposure method, at least one of the refractive index at the exposure wavelength is set between the second diffraction grating and the substrate and between the first diffraction grating and the second diffraction grating. Can be filled with a dielectric of 1.2 or more.

The second exposure method of the present invention is an exposure method in which a pattern is exposed on a photosensitive substrate with illumination light from a light source, and the effective wavelength of the illumination light is less than twice the effective wavelength of the illumination light on the light source side of the substrate. The diffraction grating having a period of λ is closely opposed and the intensity distribution of the illumination light from the light source and the relative positional relationship between the diffraction grating and the diffraction grating are changed with time. A step of irradiating the grating and a step of irradiating the substrate with the diffracted light generated by the diffraction grating.
According to the second exposure method, a fine pattern can be formed on a photosensitive substrate at low cost.

The relative positional change can be changed by moving the intensity distribution of the illumination light while fixing the diffraction grating.
In addition, the divergence angle of the illumination light applied to the diffraction grating can be adjusted.
Alternatively, the divergence angle of the illumination optical path through which the illumination light applied to the diffraction grating can pass can be adjusted. The divergence angle can be adjusted according to the expansion and contraction of the photosensitive substrate.

Further, the relative positional relationship between the diffraction grating and the substrate in the in-plane direction of the substrate is shifted in a direction orthogonal to the direction of the period of the diffraction grating, or an integral multiple of the period of the diffraction grating. It is also possible to perform the exposure by repeating each step a plurality of times while shifting in the direction of the cycle by the length of.
The space between the diffraction grating and the substrate can be filled with a dielectric having a refractive index of 1.2 or more at the exposure wavelength.

A third exposure method of the present invention is an exposure method in which a pattern is exposed on a photosensitive substrate with illumination light from a light source, and the first diffraction grating is irradiated with the illumination light from the light source; Irradiating the second diffraction grating disposed opposite to the first diffraction grating with the diffraction light generated by the first diffraction grating, and the diffraction light generated by the second diffraction grating, And irradiating the photosensitive substrate disposed in close proximity to the second diffraction grating, and the divergence angle of the illumination light applied to the first diffraction grating is adjustable. There is something.
According to the third exposure method, even when the substrate to be exposed is expanded or contracted, the expansion and contraction of the substrate is corrected by expanding or converging the period of the interference fringes formed on the substrate. And can be exposed.

The divergence angle can be adjusted according to the expansion and contraction of the substrate.
Furthermore, at least one of the second diffraction grating and the substrate and between the first diffraction grating and the second diffraction grating is a dielectric having a refractive index of 1.2 or more at the exposure wavelength. It can also be filled with the body.
A first invention relating to an electronic device manufacturing method of the present invention uses the exposure method of the present invention in at least a part of a step of forming a circuit pattern constituting the electronic device.

  The second invention related to the electronic device manufacturing method of the present invention is a combination of the projection exposure method using the projection exposure apparatus and the exposure method of the present invention in at least a part of the process of forming the circuit pattern constituting the electronic device. Exposure is used.

  The first exposure apparatus of the present invention includes illumination light from a light source, a first diffraction grating formed on a first light-transmitting flat plate, and a second diffraction grating formed on a second light-transmitting flat plate. An exposure apparatus for exposing the interference pattern generated by the light source onto a photosensitive substrate, the illumination optical system for irradiating the first diffraction grating with the illumination light from the light source, The illumination optical system has a variable divergence angle of illumination light applied to one diffraction grating.

According to the first exposure apparatus, a fine pattern can be formed on a photosensitive substrate at low cost. Even when expansion / contraction has occurred in the substrate to be exposed, exposure can be performed while correcting expansion / contraction of the substrate by expanding or converging the period of the interference fringes formed on the substrate.
The divergence angle of the illumination light applied to the first diffraction grating can be changed by moving at least a part of the optical member included in the illumination optical system.

  In addition, the illumination light distribution variable mechanism that changes the intensity distribution of the illumination light irradiated to the first diffraction grating and the relative positional relationship with the first diffraction grating with time is provided. The integrated intensity distribution on the first diffraction grating can be made substantially uniform in a predetermined region including the central portion of the first diffraction grating.

  Further, at least one of at least a part between the second diffraction grating and the substrate and at least a part between the first diffraction grating and the second diffraction grating has a refractive index of 1 at the exposure wavelength. It is also possible to have a liquid supply mechanism that is filled with two or more dielectric liquids.

  A second exposure apparatus of the present invention is an exposure apparatus for exposing an interference pattern generated by illumination light from a light source and a diffraction grating formed on a translucent flat plate onto a photosensitive substrate. An illumination optical system that is provided between the light source and the diffraction grating and that irradiates the translucent flat plate with the illumination light from the light source, and a first holding that holds the translucent flat plate in a predetermined position. A mechanism and a substrate holding mechanism that holds the substrate in alignment with and close to the translucent flat plate, and the intensity distribution of the illumination light is relative to the translucent flat plate. It has an illumination light distribution variable mechanism that changes the positional relationship with time, and the integrated intensity distribution of the illumination light on the translucent flat plate can be made almost uniform in a predetermined area including the center of the translucent flat plate. It is something to be made.

According to the second exposure apparatus, a fine pattern can be formed on a photosensitive substrate at low cost.
Moreover, the illumination optical system can also make the divergence angle of the illumination light irradiated to the said translucent flat plate variable.
Further, it may have a liquid supply mechanism that fills at least a part between the translucent flat plate and the substrate with a dielectric liquid having a refractive index of 1.2 or more at the exposure wavelength.

FIG. 1A is a partially cutaway view showing an outline of an exposure apparatus of the present invention, FIG. 1A is a view showing an upstream of an optical path from a light source 1 to a deflecting mirror 11, and FIG. It is a figure which shows the downstream of the optical path after the mirror 12. FIG. It is a top view which shows the outline of the exposure apparatus of this invention. It is sectional drawing which shows the positional relationship of 1st diffraction grating G11, G12, 2nd diffraction grating G21, and wafer W, and diffracted light LP, LM, LP0, LP1. 3 is a cross-sectional view showing an intensity distribution of interference fringes formed on a wafer W. FIG. FIG. 6 is a diagram for explaining the influence of a deviation in the incident angle of illumination light on a positional deviation in the intensity distribution of interference fringes formed on a wafer W. It is a figure explaining the in-plane change of the incident angle of the illumination light to a 1st translucent flat plate. It is a figure explaining the divergence / convergence of the illumination light to a 1st translucent flat plate. It is a figure explaining an example of the 1st diffraction grating and the 2nd diffraction grating G21, and Drawing 8 (A) shows the 1st diffraction grating G11 and G12 formed on the 1st translucent flat plate P1. FIG. 8B is a diagram showing the second diffraction grating G21 formed on the second light-transmitting flat plate P2. FIG. 9A is a diagram for explaining another example of the first diffraction grating and the second diffraction grating, and FIG. 9A shows the first diffraction gratings G13 and G14 formed on the first light transmitting flat plate P1a. FIG. 9B is a diagram showing the second diffraction grating G22 formed on the second light-transmitting flat plate P2a. FIG. 10A is a diagram for explaining a diffraction angle distribution of diffracted light generated from the first diffraction grating and the second diffraction grating as shown in FIG. 9A and FIG. 9B, and FIG. FIG. 10B is a diagram for explaining the angular distribution of diffracted light generated from the first diffraction gratings G13 and G14 formed on the translucent flat plate P1a, and FIG. 10B shows the first distribution formed on the second translucent flat plate P2a. It is a figure which shows angle distribution of the diffracted light which generate | occur | produces from 2 diffraction gratings G22. It is a figure explaining the change of the relative positional relationship of intensity distribution of illumination light IL8, and the 1st translucent flat plate P1. It is sectional drawing which shows the positional relationship of 1st diffraction grating G11, G12, 2nd diffraction grating G21, wafer W, and thin film PE1, PE2. It is a figure which shows the state which provided protective layer PE3 in the vicinity of 2nd diffraction grating G21. It is a figure which shows the state which provided 1st diffraction grating G15, G16 and 2nd diffraction grating G23 on each of both surfaces of the 1st translucent flat plate P3. It is a figure which shows the state which provided the diffraction gratings G17 and G18 in the wafer W side of the translucent flat plate P4. It is a figure which shows the holding mechanism 36a of the 1st translucent flat plate P1, and the holding mechanism 37a of the 2nd translucent flat plate P2. It is a figure which shows the exchange mechanism 42 grade | etc., Of the 2nd translucent flat plate P2, FIG. 17 (A) is a bottom view which shows the exchange mechanism 42 grade | etc., FIG. 17 (B) is the AB line | wire of FIG. 17 (A). FIG. FIG. 18A is an explanatory diagram of a mechanism that fills liquid between the wafer W and the second light-transmitting flat plate P2, and FIG. 18A is a mechanism that fills liquid only between the wafer W and the second light-transmitting flat plate P2. FIG. 18B is an explanatory diagram of a mechanism for filling the liquid between the light-transmitting flat plate P2 and the light-transmitting flat plate P1. It is explanatory drawing of the mechanism with which a liquid is filled between the translucent flat plate P2 and the translucent flat plate P1.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Light source, 2, 3, 5, 7 ... Collimator lens, 12 ... Y movable mirror, 14 ... X movable mirror, FS ... Field stop, 24, 25, 26, 27 ... Illumination system front group lens, 29, 30 , 32, 35 ... illumination system rear group lens, P1 ... first translucent flat plate, P2 ... second translucent flat plate, 36a, 36b ... first holding mechanism, 37a, 37b ... second holding mechanism, W ... Substrate (wafer), 38 ... Wafer stage, 40 ... Laser interferometer, G11, G12, G13, G14 ... First diffraction grating, G21, G22 ... Second diffraction grating, IL1-IL8 ... Illumination light

Hereinafter, embodiments of the present invention will be described.
FIG. 1 is a side view (sectional view) showing a first embodiment of the exposure apparatus of the present invention, and FIG. 1 (A) shows the optical path from the light source 1 to the deflection mirror 11 in the exposure apparatus. It is a figure showing an upstream part, (B) is a figure showing the downstream part of the optical path after the Y movable mirror 12. FIG.

FIG. 2 is a plan view showing a first embodiment of the exposure apparatus of the present invention.
The XYZ coordinate systems shown in FIG. 1 and FIG. 2 each indicate the same coordinate system (direction), and this is the same in the subsequent drawings.

The first embodiment of the exposure apparatus of the present invention will be described below with reference to FIGS.
Illumination light IL1 emitted from a light source 1, such as an ArF (argon / fluorine) excimer laser, a KrF (krypton / fluorine) excimer laser, an F2 (fluorine dimer) laser, or a harmonic laser using a wavelength conversion element, is a collimator lens. By the groups 2, 3, 5, and 7, the illumination light IL2 that is a parallel light beam (parallel beam) having a predetermined beam size is converted.

  The illumination light IL2 is set to a predetermined polarization state by the polarization control element 10 to become illumination light IL3, reflected by the deflection mirror 11, and bent to become illumination light IL4. As shown in FIG. 2, the illumination light IL4 travels in the −Y direction and reaches the Y movable mirror 12.

  The Y mirror holding mechanism 13 that holds the Y movable mirror 12 can be moved in the Y direction along the Y direction guides 23a and 23b by the Y drive mechanism 21 via the Y transmission member 22 such as a ball screw. is there.

The illumination light IL5 reflected by the Y movable mirror 12 travels in the −X direction in the figure and reaches the X movable mirror 14.
The X mirror holding mechanism 15 for holding the X movable mirror 14 can be moved in the X direction along the X direction guides 20a and 20b on the surface plate 16 by the X drive mechanism 18 via the X transmission member 18 such as a ball screw. is there.

The X mirror holding mechanism 15 and the Y mirror holding mechanism 13 can be driven by a linear motor or the like.
The illumination light IL6 reflected by the X movable mirror 14 passes through an opening 17 provided on the surface plate 16, enters the illumination system front group lenses 24, 25, 26, and 27, is refracted by these lenses, and is illuminated. The light IL7 is condensed on the condensing point 28.

Thereafter, the illumination light IL7 enters the illumination system rear group lenses 29, 30, 32, and 35, is refracted by these lenses, and becomes parallel illumination light IL8 again and enters the first translucent flat plate P1.
The optical members on the optical path of the illumination lights IL1 to IL8 from the collimator lens groups 2, 3, 5, and 7 to the illumination system rear group lenses 29, 30, 32, and 35 are hereinafter referred to as illumination optical systems. That's it.

  A field stop FS is provided between the foremost lens 24 of the front lens group of the illumination system and the surface plate 16. The field stop FS blocks the illumination light IL7 that is variable in the XY directions by the X mirror holding mechanism 15 and the Y mirror holding mechanism 13 when the illumination light IL7 is distributed outside a predetermined region in the XY plane. Therefore, the outer edges LEa and LEb of the optical path through which the illumination light IL7 and the illumination light IL8 can pass are determined by the field stop FS.

A second translucent flat plate P2 is provided below the first translucent flat plate P1 (−Z direction).
The second translucent flat plate P2 is disposed close to and opposed to a substrate W (hereinafter also referred to as “wafer” as appropriate) such as a semiconductor wafer to be processed.

  A first diffraction grating, which will be described later, is formed on the first translucent flat plate P1, and the diffracted light generated by irradiating the first diffraction grating with the illumination light IL8 is the second translucent light. Is irradiated to the conductive flat plate P2. A second diffraction grating, which will be described later, is formed on the second light transmitting flat plate P2, and the second diffraction grating is irradiated with the diffracted light. Then, the diffracted light generated by the second diffraction grating is applied to the wafer W, and a light / dark pattern is formed on the wafer W by interference fringes composed of a plurality of diffracted lights.

A photoresist for exposing and recording the light / dark pattern is formed on the surface of the wafer W. That is, the wafer W can be regarded as a photosensitive substrate.
The wafer W is held on a wafer stage 38, which is a substrate holding mechanism that is movable in the XY directions, on the wafer surface plate 50, and is thus movable in the XY directions. Further, the position of the wafer W in the X direction is measured by the laser interferometer 40 via the position of the movable mirror 39 provided on the wafer stage 38, and the position in the Y direction is also provided on the wafer stage 38 (not shown). It is measured by a laser interferometer (not shown) through the moving mirror position.

  The second translucent flat plate P2 is held by the second holding mechanisms 37a and 37b so as to be disposed close to and opposed to the wafer W with a predetermined interval described later. The first translucent flat plate P1 is held by the first holding mechanisms 36a and 36b so as to face the second translucent flat plate P2 with a predetermined interval described later.

  The diameter of the wafer W is 300 mm as an example, and the second translucent flat plate P2 has a diameter that covers the entire surface of the wafer W as an example. Similarly, the first light-transmitting flat plate P1 has a diameter that covers the entire surface of the second light-transmitting flat plate P2 as an example. However, as will be described later, the diameter of the first translucent flat plate P1 is desirably about 30 mm or more larger than the diameter of the wafer W.

Next, the bright and dark patterns of interference fringes formed on the wafer W according to the present invention will be described with reference to FIGS.
FIG. 3 is a diagram illustrating a cross section of the first light-transmitting flat plate P1, the second light-transmitting flat plate P2, and the wafer W that are arranged to face each other. The first light-transmitting flat plate P1 and the second light-transmitting flat plate P2 are made of synthetic quartz or the like and have high transmittance to ultraviolet rays and have a small coefficient of thermal expansion (linear expansion coefficient). Therefore, heat associated with absorption of exposure light. It is made of a material with small deformation. In particular, when an F2 laser is used as the light source 1, it is preferable to use synthetic quartz to which fluorine is added.

  One-dimensional phase modulation type diffraction gratings G11 and G12 having periodicity in the X direction are formed on the surface of the first translucent flat plate P1 on the + Z side, that is, the light source side. On the other hand, a one-dimensional intensity modulation type diffraction grating G21 having periodicity in the X direction is formed on the surface of the second translucent flat plate P2 on the −Z side, that is, the wafer W side.

These diffraction gratings G11, G12, and G21 will be described with reference to FIG.
FIG. 8A is a view of the first translucent flat plate P1 as viewed from the + Z side, and the surface has a longitudinal direction in the Y direction and a one-dimensional period T1 in the X direction. Phase modulation type first diffraction gratings G11 and G12 are formed. The first diffraction gratings G11 and G12 include a surface portion G12 of the first light-transmitting flat plate P1 and a dug portion G11 obtained by dug the flat plate surface by etching or the like like a so-called chromeless phase shift reticle. The depth of the dug portion G11 is set so that a phase difference of 180 degrees is formed between the illumination light that passes through the surface portion G12 and the illumination light that passes through the dug portion G12. The digging depth is (2m−1) λ0 / (2 (n−1)) with respect to the wavelength λ0 of the exposure light, the refractive index n of the first translucent flat plate P1, and an arbitrary natural number m. .

Moreover, it is preferable that the ratio (duty ratio) of the width of the surface portion G12 and the dug portion G11 is 1: 1.
FIG. 8B is a view of the second translucent flat plate P2 as viewed from the + Z side. The back surface (the surface on the wafer W side) has a longitudinal direction in the Y direction and 1 in the X direction. A second diffraction grating G21 having a dimensional period T2 is formed. The second diffraction grating G21 is made of a film of a metal such as chromium, molybdenum, tungsten, tantalum or the like, an oxide, a fluoride or a silicide thereof, or another light-shielding / darkening material.

  8A and 8B, for convenience of explanation, the period T1 is represented as about 10% of the diameter (for example, 300 mm or more) of the first translucent flat plate P1, but in practice the period T1 is about 240 nm, for example, and the period T2 is about 120 nm, for example, which is overwhelmingly smaller than the diameter of the first translucent flat plate P1. The same applies to each figure other than FIGS. 8A and 8B.

  Hereinafter, returning to FIG. 3, the principle that a bright / dark pattern of interference fringes is formed on the wafer W by irradiating the first diffraction gratings G11 and G12 and the second diffraction grating G21 with the illumination light IL8 will be described.

  When the substantially parallel illumination light IL8 is irradiated, diffracted light corresponding to the period T1 is generated from the first diffraction gratings G11 and G12. If the first diffraction gratings G11 and G12 are phase modulation type gratings having a duty ratio of 1: 1 and a phase difference of 180 degrees, the 0th-order diffracted light disappears and does not occur. In this case, two diffracted lights of ± 1st order light are mainly generated, but there is a possibility that higher order diffracted lights such as ± 2nd order light are also generated.

  However, when the period T1 is shorter than twice the effective wavelength λ of the illumination light, high-order diffracted light such as secondary light cannot be generated. Accordingly, in this case, only two of the + 1st order diffracted light LP and the −1st order diffracted light LM are generated from the first diffraction gratings G11 and G12, and pass through the first translucent flat plate P1 to generate the second light. It enters into the translucent flat plate P2.

  Here, the effective wavelength λ of the illumination light is the wavelength of the illumination light in the medium having the lowest refractive index among the translucent media existing on the illumination optical path from the first diffraction gratings G11 and G12 to the wafer W. Say. In this example, since air (or nitrogen or a rare gas may be present) exists between each of the translucent flat plate P1, translucent flat plate P2, and wafer W, the effective wavelength λ0 is the wavelength of illumination light λ0 being refracted by air. It is a value divided by the rate (= 1).

  Subsequently, the + 1st order diffracted light LP and the −1st order diffracted light LM are applied to the second diffraction grating G21 provided on the wafer W side surface of the second translucent flat plate P2. Since both diffracted lights are symmetrical, only the + 1st order diffracted light LP will be described below.

  The + 1st order diffracted light LP is inclined by a predetermined angle from a direction perpendicular to the second diffraction grating G21 (normal direction) with respect to the second diffraction grating G21 by the period T1 of the first diffraction gratings G11 and G12. Incident.

Assuming that the inclination angle θ0 is that the second diffraction grating G21 is disposed in the air,
(Formula 1)
sin θ0 = λ / T1
Is the angle represented by
When the + 1st order diffracted light LP is applied to the second diffraction grating G21, diffracted light is also generated from the second diffraction grating G21. Since the second diffraction grating G21 is an intensity modulation type diffraction grating, the diffracted light is diffracted light including zeroth-order light.

  Here, the angle direction in which each diffracted light is generated is inclined according to the inclination of the incident angle of the illuminating illumination light (+ 1st order diffracted light LP). That is, the second diffraction grating G21 is diffracted in accordance with the zero-order diffracted light LP0 traveling in the direction parallel to the irradiated + 1st-order diffracted light LP and the period T2 of the second diffraction grating G21 in the X direction − First-order diffracted light LP1 is generated.

  If the period T2 of the second diffraction grating G21 is larger than a predetermined value determined by the relationship between the period T1 and the effective wavelength, + 1st order diffracted light (not shown) may also be generated. However, by setting the period T2 to be equal to or less than the effective wavelength of the illumination light, it is possible to substantially prevent the generation of + 1st order diffracted light (not shown). Here, the effective wavelength λ of the illumination light is the same as described above.

As a result, two diffracted lights of 0th order diffracted light LP0 and −1st order diffracted light LP1 are irradiated on the wafer W, and a light / dark pattern of interference fringes is formed by interference of these diffracted lights.
Hereinafter, the bright and dark patterns of the interference fringes will be described with reference to FIG.

FIG. 4 is a cross-sectional view showing the light / dark distribution of interference fringes formed on the wafer W by the two diffracted lights of the 0th-order diffracted light LP0 and the −1st-order diffracted light LP1.
As described above, since the 0th-order diffracted light LP0 is generated in a direction parallel to the + 1st-order diffracted light LP irradiated to the second diffraction grating G21, the 0th-order diffracted light LP0 is relative to the vertical direction (normal direction) ZW of the wafer W. Thus, irradiation is performed at an incident angle inclined by the above-described θ0.

On the other hand, the −1st order diffracted light LP1 is diffracted in the X direction by the period T2 in the X direction, and is irradiated onto the wafer W at the incident angle θ1. At this time, the period (intensity distribution period) T3 of the bright and dark pattern of the interference fringes IF formed on the wafer W is:
(Formula 2)
T3 = λ / (sin θ0 + sin θ1)
It becomes. This corresponds to half the period of the amplitude distribution of the interference fringe IF.

  Accordingly, a bright and dark pattern parallel to the Y direction having a period T3 in the X direction is formed on the entire surface of the wafer W. The light and dark pattern is irradiated and exposed on the photoresist PR formed on the wafer W.

  In general, an interference fringe formed by two light bundles such as the interference fringe IF has a very small decrease in contrast even when the wafer W is moved in the Z direction, that is, a light-dark pattern having a large depth of focus. .

  However, when the incident angle θ0 of the 0th-order diffracted light LP0 is not equal to the incident angle θ1 of the −1st-order diffracted light LP1 (when it is not symmetrical with respect to the normal direction VW), it corresponds to the positional deviation of the wafer W in the Z direction. The position of the interference fringe IF in the X direction changes.

Accordingly, when it is desired to accurately control the position of the interference fringe IF in the X direction, the incident angle θ0 of the 0th-order diffracted light LP0 irradiated on the wafer W and the incident angle θ1 of the −1st-order diffracted light LP1 are preferably made equal. Such conditions are based on the assumption that the illumination light IL8 is perpendicularly incident on the first diffraction gratings G11 and G12, and the period T1 of the first diffraction gratings G11 and G12 is the period of the second diffraction grating G21. This is realized when it is approximately twice T2. And at this time,
(Formula 3)
T2 = T3
Satisfy the relationship.

Since both the first diffraction gratings G11 and G12 and the second diffraction grating G21 include manufacturing errors and the like, it is actually that the period of both gratings is strictly doubled. I can't expect it. Therefore, the above approximate double is
(Formula 4)
T2 × 2 × 0.999 ≦ T1 ≦ T2 × 2 × 1.001
This means that if the above condition is satisfied, it is generally good. By satisfying the above conditions, it is possible to irradiate the light and dark pattern of the interference fringe IF to a predetermined position of the wafer W even when the wafer W is displaced in the Z direction.

Here, as long as the position of the wafer W in the Z direction can be strictly controlled to a predetermined position, it is not always necessary to satisfy the condition expressed by the above equation 4.
As described above, the illumination light IL8 needs to be incident on the first diffraction gratings G11 and G12 perpendicularly. Hereinafter, the reason will be described with reference to FIG.

  FIG. 5 shows the cross sections of the first light-transmitting flat plate P1, the second light-transmitting flat plate P2, the wafer W, and the interference fringes IFa and IFb formed on the wafer W, as in FIG. 3 and FIG. FIG. Here, it is assumed that the period T1 of the first diffraction gratings G11 and G12 is twice the period T2 of the second diffraction grating G21.

  The interference fringe IFa shown on the left side in FIG. 5 represents an interference fringe formed due to the illumination light IL8a incident perpendicularly to the first diffraction gratings G11 and G12. At this time, as in the case shown in FIGS. 3 and 4, the + 1st order diffracted light LPa and the −1st order diffracted light LMa are generated symmetrically from the first diffraction gratings G11 and G12, which are generated by the second diffraction grating G21. Is incident on. When focusing on the + 1st order diffracted light LPa, the 0th order diffracted light LPa0 and the −1st order diffracted light LPa1 generated by the second diffraction grating G21 are incident on the wafer W at the same incident angle (inclined symmetrically).

  Accordingly, an interference fringe IFa having a bright and dark (intensity) period T2 in the X direction is formed on the wafer W at a predetermined position. And the X direction position of the peak of the bright part corresponds exactly with the position of the transmission part of the second diffraction grating G21.

  On the other hand, the interference fringe IFb shown on the right side in FIG. 5 represents an interference fringe formed due to the illumination light IL8b that is incident on the first diffraction grating G11, G12 at an angle φ. Also at this time, the first diffraction gratings G11 and G12 generate the + 1st order diffracted light LPb and the −1st order diffracted light LMb. ing.

As a result, the symmetry of the incident angles of the 0th-order diffracted light LPb0 and the -1st-order diffracted light LPb1 generated from the second diffraction grating G21 on the wafer W is broken by the irradiation of the + 1st-order diffracted light LPb.
Even in this case, an interference fringe IFb having a bright and dark (intensity) period T2 in the X direction is formed on the wafer W, but the X direction position of the peak of the bright part is that of the second diffraction grating G21. The position of the transmission part is shifted.

If the amount of deviation is δ,
(Formula 5)
δ = D2 × tanφ
It becomes the relationship.

  If such an interference fringe misalignment is an overall misalignment of the interference fringes formed on the wafer W, the position correction exposure is performed by shifting the position of the wafer W to be exposed by a predetermined amount. It is possible.

However, when such a misregistration amount is generated by a different amount depending on each position in the surface of the wafer W, the problem cannot be solved by the position correction exposure.
Accordingly, the illumination light IL8 irradiating the first diffraction gratings G11 and G12, that is, the first translucent flat plate P1, is the first translucent flat plate regardless of the location in the first translucent flat plate P1. It is preferable to enter P1 at a constant incident angle, that is, parallel light.

Further, in order to eliminate the above-described position shift as a whole, it is preferable that the illumination light IL8 is incident on the first light-transmitting flat plate P1 perpendicularly.
Here, for example, when the period T3 (= T2) of the interference fringe pattern exposed on the wafer W is 120 nm, that is, when the pattern is generally called a 60 nm line and space, the positional deviation tolerance is generally a line. It is about 15 nm, which is a quarter of the width. Here, if the distance D2 between the second diffraction grating G21 and the surface of the wafer W is 50 μm, the allowable deviation φ1 from the vertical incidence of the illumination light is
(Formula 6)
φ1 = arctan (10/50000) = 0.3 [mrad]
It becomes.

  Therefore, it is preferable that the parallelism of the illumination light IL8 incident on the first translucent flat plate P1 is about ± 0.3 [mrad] or less. That is, the illumination light IL8 preferably has a convergence or divergence of about ± 0.3 [mrad] or less. It goes without saying that this condition varies depending on the period T3 of the pattern to be exposed and the second diffraction grating G21 and D2 on the surface of the wafer W.

  In the above description, on the assumption that the first light-transmitting flat plate P1 and the wafer W are arranged in parallel, the incident angle of the illumination light IL8 is a position within the first light-transmitting flat plate P1. However, in practice, the incident angle of the illumination light IL8 is preferably parallel to the normal line of the wafer W.

  Incidentally, in order for the illumination light IL8 to achieve such a strict parallelism, a parallelism fine adjustment mechanism capable of adjusting the parallelism is necessary. Therefore, in the exposure apparatus of the present invention, the illumination light IL1, IL2, IL7, IL8 is applied to some of the collimator lenses 2, 3, 5, 7 and the illumination system rear group lenses 29, 30, 32, 35. The above-mentioned fine adjustment is performed so as to be movable in the traveling direction.

  Hereinafter, the parallelism fine adjustment mechanism provided in the illumination system rear group lenses 29, 30, 32, and 35 in FIG. 1 will be described. Among the illumination system rear group lenses, the lens drive mechanisms 31 a and 31 b are attached to the negative lens 30, and the lens drive mechanisms 33 a and 33 b are attached to the positive lens 32. These lens driving mechanisms 31a, b, 33a, b are movable in the Z direction on the fixed shafts 34a, 34b, whereby the lens 30 and the lens 32 are also independently movable in the Z direction.

  As a result, the illumination system rear group lenses 29, 30, 32, and 35 constitute a so-called inner focus lens as a whole, and the focal length or focal position thereof is variable. Therefore, even when the condensing point 28 of the illumination light IL7 is not at a predetermined design position due to a manufacturing error or the like, the illumination light IL7 from the condensing point 28 can be accurately converted into the parallel illumination light IL8. It becomes possible.

  FIG. 6 shows that the outer edges LEa and LEb of the optical path through which the illumination light IL8 can pass vary due to the variation in the focal length of the illumination system rear group lenses 29, 30, 32 and 35 as a whole by driving the lens 30 and the lens 32. It is a figure showing that the incident angle to the 1st translucent flat plate P1 of illumination light IL8 changes according to the position in the 1st translucent flat plate P1.

  FIG. 6A shows a case where the lens 30 and the lens 32 are set at appropriate Z-direction positions, and the outer edges LEa and LEb are perpendicular to the first light-transmissive plate P1, and the illumination light IL8c. The illumination light IL8d and the illumination light IL8e are perpendicularly incident on the first translucent flat plate P1 regardless of the location in the first translucent flat plate P1.

  On the other hand, FIG. 6B shows a case where the lens 30 and the lens 32 are arranged so as to be shifted from appropriate Z-direction positions, and the light paths that can be taken by the illumination light IL8 defined by the outer edges LEa1 and LEb1 are the diverging light paths as a whole. Become. At this time, the outer edges LEa1 and LEb1 are inclined (diverged) by ψe from the vertical directions LEa and LEb, respectively. With the divergence of the entire optical path, the incident angle of the illumination light IL8 to the first translucent flat plate P1 also changes according to the position.

  That is, the illumination light IL8f irradiated through the optical path portion close to the outer edge LEa1 is inclined slightly outward and enters the first translucent flat plate P1. When the inclination angle is ψm, the position of the bright and dark pattern of the interference fringes formed on the wafer W by the illumination light IL8f is from the bright and dark position of the second diffraction grating G21 on the second light transmitting flat plate P2. On the left, the position is shifted by an amount approximately proportional to ψm, and a position error occurs. The principle is the same as that shown in FIG.

  On the other hand, the position of the bright and dark pattern of the interference fringes formed on the wafer W by the illumination light IL8h irradiated through the optical path portion close to the outer edge LEb1 is approximately proportional to the outward inclination angle ψm of the illumination light IL8h. It is formed at a position shifted to Further, the position of the bright and dark pattern of the interference fringes formed on the wafer W by the illumination light IL8g irradiated through the optical path portion close to the center is not displaced because the illumination light IL8h is substantially perpendicularly incident.

  Therefore, the relationship of the size of the interference fringe pattern exposed on the wafer W with respect to the light and dark pattern of the second diffraction grating G21 is that the optical path defined by the outer edges LEa1 and LEb1 is a diverging optical path as a whole. Is enlarged, and when it is a convergent optical path as a whole, it is reduced, and in either case, a magnification error occurs.

  In the exposure apparatus of the present invention, by setting the lens 30 and the lens 32 to appropriate Z-direction positions, the optical path that can be taken by the illumination light IL8 defined by the outer edges LEa and LEb can always be a parallel optical path. Thus, occurrence of such a magnification error can be prevented.

  In the exposure apparatus of the present invention, when an unexpected expansion or contraction occurs in the wafer W to be exposed due to thermal deformation or the like in the previous manufacturing process, the positions of the lens 30 and the lens 32 are adjusted to adjust the outer edge LEa1. , LEb1 is used as a diverging optical path or a converging optical path as a whole, thereby expanding or converging the period T3 of the interference fringes formed on the wafer W to correct the expansion and contraction of the wafer W. It can also be exposed.

  Next, the parallelism fine adjustment mechanism provided in the collimator lenses 2, 3, 5, and 7 in FIG. 1 will be described. A lens driving mechanism 6 is attached to the negative lens 5 in the collimator lens, and a lens driving mechanism 8 is attached to the positive lens 7. These lens driving mechanisms 7 and 8 are movable in the X direction on the fixed shaft 9, whereby the lens 5 and the lens 7 are also independently movable in the X direction.

  As a result, the lenses 5 and 7 constituting the rear group of the collimator lens constitute a so-called inner focus lens as a whole, and the focal length or focal position thereof is variable. Therefore, even if the illumination light IL8 does not become a parallel light beam due to fluctuations in the light source 1, manufacturing errors of the illumination optical systems 2 to 35, etc., the illumination light IL8 is perfectly parallel by driving the lens driving mechanisms 7 and 8. It can be converted into light.

  Therefore, as shown in FIG. 7, the state of the parallelism (convergence or divergence) of the illumination light IL8 can be changed by driving the lens driving mechanisms 7 and 8. The illumination light to the first translucent flat plate P1 is preferably a parallel light beam like the illumination light IL8j shown at the center in FIG. Accordingly, when the illumination light is a convergent light beam such as the illumination light IL8i shown on the left side in FIG. 7, or when the illumination light is a divergent light beam such as the illumination light IL8i shown on the right side in FIG. Desirably, the lens driving mechanisms 7 and 8 are driven to obtain a desired parallel light beam.

In the above description, the problem and solution regarding the convergence and divergence of the illumination light have been described.
However, in the present invention, even when a predetermined width (angle range) exists in the incident angle of the illumination light that illuminates one point of the first translucent flat plate P1, the angle range is on the wafer W. May cause a decrease in contrast of interference fringes.

  Here, the angle range of the incident angle of illumination light means the numerical aperture of illumination light. For example, when the spatial coherence of the light source 1 or the like is low, the concentration of the illumination light at the condensing points 4 and 28 in the illumination optical system is weak, and the condensing points are widened. This means an increase in the numerical aperture of the illumination light beam irradiated to the first light-transmissive plate P1.

  In the present invention, the deviation of the incident angle of the illumination light causes a displacement of the interference fringes on the wafer W. Therefore, the presence of the incident angle range of the illumination light positions the interference fringes on the wafer W relative to each other. This is equivalent to the act of adding and causing a shift, and reduces the contrast of interference fringes.

  Therefore, the incident angle range corresponding to the numerical aperture of the illumination light is desirably about ± 0.3 [mrad] or less from the same consideration as described above. That is, it is desirable that the illumination light numerical aperture (NA) of the illumination optical system is 0.0003 or less. Such low NA illumination light can be realized by using a laser light source with high spatial coherence or by providing a stop for mechanically restricting the illumination beam bundle at the condensing points 4 and 28.

  Here, the optimum value of the distance D2 between the second diffraction grating G21 and the surface of the wafer W in the present invention will be described. As described above, the displacement of the interference fringe pattern on the wafer W when the illumination light IL8 is tilted is generated in proportion to the interval D2. Therefore, the shorter the interval D2, the better. This is because it is possible to relax the standard regarding the inclination of the illumination light.

  However, if the distance D2 is too short, contact between the second diffraction grating G21 and the wafer W occurs, resulting in damage to them. Therefore, in order to avoid contact, the distance D2 is a minimum value of 1 μm or more in consideration of the flatness of the wafer W and the flatness of the second translucent flat plate P2 forming the second diffraction grating G21. Should be secured.

Moreover, in order to prevent the said contact reliably, it is desirable for the space | interval D2 to be 5 micrometers or more.
On the other hand, if the distance D2 is too long, the standard regarding the inclination of the illumination light becomes stricter, but the position where a plurality of diffracted lights condensed at one point on the wafer W1 emit the second diffraction grating G21. And the coherence due to the spatial coherence between the plurality of diffracted lights is reduced. Therefore, the distance D2 is desirably set to 500 μm or less.

  Further, if the distance D2 is short, the standard regarding the inclination of the illumination light and the like can be relaxed, and the manufacturing apparatus can be provided at a lower cost. Therefore, it is more desirable to set the distance D2 to 100 μm or less.

  In the present invention, since the second diffraction grating G21 and the wafer W are arranged close to each other and face each other, multiple interference of illumination light between the surfaces of both components can occur. This adversely affects the brightness distribution of interference fringes formed on the wafer W.

Therefore, in the present invention, as the illumination lights IL1 to IL8 from the light source 1, light whose temporal coherence distance (coherence distance in the light traveling direction) is about twice or more the interval D2 is used. It is preferable to do. The temporal coherence distance of light is a distance approximately represented by λ ² / Δλ, where λ is the wavelength of the light and Δλ is the half-value width in the wavelength distribution of the light. Therefore, when the exposure wavelength λ is 193 nm from the ArF laser, it is desirable to use the illumination light IL1 to IL8 whose wavelength half width Δλ is about 370 pm or more.

  When the interference fringe IF having a one-dimensional period is formed as described above, the illumination light IL8 used for the formation has a polarization direction (electric field direction) in the longitudinal direction of the interference fringe IF (a direction perpendicular to the period direction). ), That is, linearly polarized light in a direction perpendicular to the periodic direction. This is because the contrast of the interference fringe IF can be maximized in this case.

  Even if the illumination light IL8 is not completely linearly polarized light as described above, the electric field component in the longitudinal direction (Y direction) of the interference fringe IF is larger than the electric field component in the periodic direction (X direction). If present, the above-described contrast improvement effect can be obtained.

  Further, since the periodic direction of the interference fringe IF coincides with the direction of the period T2 of the second diffraction grating G21, the preferable polarization state of the illumination light IL8 is basically the period of the second diffraction grating G21. It is only necessary that the electric field component in the direction orthogonal to the direction of T2 (Y direction) is larger than the electric field component in the direction of period T2 (X direction).

  Such polarization characteristics of the illumination light IL8 are realized by the light control element 10 provided in the illumination optical system. The light control element 10 is, for example, a polarization filter (polaroid plate) or a polarization beam splitter that is rotatably provided with the traveling direction of the illumination lights IL2 and IL3 as a rotation axis, and the rotation direction changes the polarization direction of the illumination light IL3 to a predetermined value. Linearly polarized light can be used.

  In the case where the light source 1 is a light source that emits illumination light IL1 polarized in substantially linearly polarized light, such as a laser, a half-wave plate that is also rotatably provided can be used as the light control element 10. It is also possible to employ two quarter-wave plates provided in series so as to be independently rotatable. In this case, the polarization state of the illumination lights IL2 to IL8 can be not only linearly polarized light but also circularly polarized light and elliptically polarized light.

  By the way, the distance D1 between the first diffraction grating G11, G12 and the second diffraction grating G21 does not affect the positional deviation or the like of the interference fringe IF formed on the wafer W. There is no need to arrange them as close as possible.

  However, if the distance D1 is too long, the ± first-order diffracted lights LP and LM generated from the first diffraction gratings G11 and G12 are irradiated to all necessary portions on the second diffraction grating G21. The first diffraction gratings G11 and G12 are required. Therefore, it is preferable that the distance D1 is set to about 100 mm or less, for example, because the size required for the first diffraction gratings G11 and G12 can be reduced.

  On the other hand, if the distance D1 is too narrow, the ± first-order diffracted lights LP and LM generated from the first diffraction gratings G11 and G12 interfere with each other on the second diffraction grating G21 to form unnecessary interference fringes, Eventually, even on the wafer W, there is a possibility that unnecessary interference fringes (brightness / darkness unevenness) may be formed.

  Such unnecessary brightness / darkness unevenness is caused by the ± first-order diffracted light LP, LM generated from any one point of the first diffraction gratings G11, G12 on the second diffraction grating G21 in the space of the illumination light IL8. This can be prevented by irradiating a position sufficiently away from a typical coherence distance, for example, a position about four times the coherence distance.

  Here, the spatial coherence distance of the illumination light IL8 is a distance generally represented by λ / NA by the numerical aperture NA and the wavelength λ of the illumination light IL8. When the wavelength of the illumination light IL8 is 193 nm and the numerical aperture NA is 0.0003 as described above, the coherence distance is 643 μm, four times of 2536 μm. Therefore, in this case, the occurrence of the unnecessary brightness unevenness can be prevented by separating the irradiation positions of the ± 1st-order diffracted lights LP and LM on the second diffraction grating G21 by about 2536 μm or more.

  Here, assuming that the period T1 of the first diffraction gratings G11 and G12 is 240 nm, the diffraction angle θ0 of the ± first-order diffracted light LP and LM is obtained as 53 degrees from Equation 1. In order for the two light fluxes generated symmetrically at this diffraction angle to be irradiated on the second diffraction grating G21 at positions separated by 2536 μm or more, the distance D1 needs to be 948 μm or more.

Therefore, the distance D1 is preferably about 1 mm or more.
The first diffraction gratings G11 and G12 are for generating ± first-order diffracted light LP and LM in a predetermined direction and irradiating them on the second diffraction grating G21. It is not intended to form interference fringes by ± first-order diffracted lights LP and LM at predetermined positions on G21.

  Therefore, the positional relationship in the XY direction between the first diffraction gratings G11 and G12 and the second diffraction grating G21 does not need to be strictly aligned in the order of the periods T1 and T2 (in the order of several tens of nm). . However, since a predetermined region of the second diffraction grating G21 facing the wafer W needs to be irradiated with ± first-order diffracted light LP and LM emitted from the first diffraction gratings G11 and G12, The diffraction gratings G11, G12 and the second diffraction grating G21 need to be arranged in alignment in the XY direction with a positional relationship of, for example, several millimeters.

  In addition, the direction of the period T1 of the first diffraction gratings G11 and G12 may not coincide with the direction (X direction) of the period T2 of the second diffraction grating G21. In this case, however, the period T1 of the first diffraction gratings G11 and G12 is set to ZX in place of the period T1 in order to prevent the movement of the light and dark pattern of the interference fringe IF accompanying the change in the Z-direction position of the wafer W. It is desirable that the length projected in the plane satisfies the condition of Equation 4.

  By the way, the pattern that can be exposed on the wafer W in the exposure apparatus of the present invention is not limited to the one-dimensional interference fringe pattern. Next, a method for exposing a two-dimensional pattern by the exposure apparatus of the present invention will be described with reference to FIGS.

  FIG. 9A shows a plan view of the first translucent flat plate P1a, as in FIG. 8A, but the first diffraction gratings G13 and G14 formed on the surface thereof are arranged in the X direction. The period T11 has a two-dimensional period T12 in the Y direction. The structure in the Z direction is the same as that of the first light-transmitting flat plate P1 shown in FIG. 8A, and the width in the X direction is 0.71 × T11 with respect to the substrate surface portion G14. A digging portion G13 having a width of 0.71 × T12 is formed to constitute a phase modulation type diffraction grating.

  FIG. 10A shows the diffraction angle distribution of the diffracted light generated from the diffraction gratings G13 and G14 having such a two-dimensional period. Here, the FX axis represents the sin (sine) of the diffraction angle from the straight direction (−Z axis direction) of the generated diffracted light to the + X direction, and the FY axis is from the straight direction of the generated diffracted light. Represents the sin of the diffraction angle in the + Y direction.

  When parallel illumination light is irradiated on the diffraction gratings G13 and G14 from the + Z direction, the first-order diffracted light LPP, LMP, LMM, and the like are displayed in four directions indicated by FX = ± λ / T11 and FY = ± λ / T12. LPM occurs. In addition, since the areas of the substrate surface portion G14 and the digging portion G13 are substantially equal and the phase difference between transmitted light in both portions is 180 degrees, the 0th-order diffracted light that should be generated in the direction of the origin O disappears. Further, when the period T11 and the period T12 are shorter than twice the effective wavelength λ of the illumination light, second-order or higher-order diffracted light cannot be generated.

Since these four diffracted lights are symmetric with respect to the FX axis and the FY axis, only the interference fringes formed on the wafer W by the diffracted light LPP will be described below.
The diffracted light LPP is incident on the second translucent flat plate P2a shown in FIG. FIG. 9B shows a plan view of the second light-transmitting flat plate P2a, as in FIG. 8B, but the second diffraction grating G22 formed on the back surface thereof has a period T21 in the X direction. , Has a two-dimensional period T22 in the Y direction. The material constituting the second diffraction grating G22 is the same as that described in the example shown in FIG.

  As shown in FIG. 9B, the second translucent flat plate P2a is irradiated with the diffracted light LPP from the 0th order diffracted light K00, the X direction −1st order diffracted light KM0, the Y direction −1st order diffracted light K0M, and X Four diffracted lights of -1st order diffracted light KMM in the direction and -1st order diffracted light KMM in the Y direction are generated, and these are irradiated onto the wafer W.

  On the wafer W, a light / dark distribution of interference fringes is formed by the four diffracted lights K00, KM0, K0M, and KMM. The shape of the second diffraction grating G22 is below a predetermined threshold. It becomes almost equal to the light-dark distribution. Accordingly, it is possible to expose and transfer a two-dimensional light / dark pattern substantially equivalent to the second diffraction grating G22 onto the photoresist on the wafer W.

Also at this time,
(Formula 7)
T21 × 2 × 0.999 ≦ T11 ≦ T21 × 2 × 1.001
(Formula 8)
T22 × 2 × 0.999 ≦ T12 ≦ T22 × 2 × 1.001
When these relationships are satisfied, these four diffracted lights K00, KM0, K0M, and KMM are irradiated with the same incident angle with respect to the wafer W, and even if the position of the wafer W in the Z direction varies. The position of the light and dark distribution of the interference fringes formed thereon can be made unchanged.

  It should be noted that even when exposing a pattern having a two-dimensional cycle, if the position of the wafer W in the Z direction can be strictly controlled to a predetermined position, the conditions shown in Expressions 7 and 8 above are not necessarily satisfied. Also good.

  In the exposure of a pattern having a two-dimensional period, the above-described conditions of the parallelism of the illumination light IL8, the perpendicularity of the incident angle and the numerical aperture, the distance D2 between the second diffraction grating and the wafer W, and the XY position And the like, and the conditions of the distance D1 between the first diffraction grating and the second diffraction grating are the same as in the case of exposing the pattern having the one-dimensional period described above. is there.

  In the exposure of the pattern having a two-dimensional period, the contrast of the bright and dark pattern of the interference fringes changes depending on the polarization state of the illumination light IL8. Note that a pattern having a fine period requires a high-contrast light / dark pattern when resolving a photoresist or the like. Therefore, in a pattern having a two-dimensional period, it is preferable to set the polarization state of the illumination light IL8 so as to increase the contrast of the bright and dark pattern of interference fringes in the direction of the minimum period among the periods.

  In the case of a pattern having a two-dimensional periodicity, the direction of the period of the interference fringes is the same as the direction of the period of the second diffraction grating, as in the case of the pattern having the one-dimensional periodicity described above. Match. Therefore, as the illumination light IL8, it is preferable to use illumination light in which the electric field component in the direction orthogonal to the first direction having the minimum period in the second diffraction grating is larger than the electric field component in the first direction.

  However, depending on the type of pattern and the purpose of use, shape fidelity may be more important than improving the contrast of light and dark patterns. In that case, as the illumination light IL8, the electric field component in the direction orthogonal to the first direction having the minimum period in the second diffraction grating and the electric field component in the first direction are in a range of about ± 20%. It is preferable to use substantially the same illumination light. Such a polarization state can be realized, for example, by using two quarter wavelength plates that are arranged in series and are rotatable as the polarization control element 10 described above.

Next, the operation of the Y movable mirror 12 and the X movable mirror 14 in the exposure apparatus of the present invention will be described with reference to FIG.
As described above, in the exposure apparatus of the present invention, the NA (numerical aperture) of illumination light needs to be about 0.0003 or less. The pattern to be exposed by the exposure apparatus of the present invention is, for example, a pattern having a line width of about 50 nm, and requires a high degree of uniformity of the intensity (integrated intensity) of illumination light in the exposure region.

  In a normal projection exposure apparatus or the like, a fly-eye lens or a rod is used as a means for equalizing the intensity of illumination light in the exposure area. These means are based on the assumption that the numerical aperture of the illumination light is increased to some extent. The shape of the effective secondary light source is enlarged, and the illumination light intensity on the irradiated region is made uniform by the averaging effect. Therefore, such a uniformizing means is difficult to apply to the present invention that requires illumination light with a minimum NA. As a result, in the present invention, it is difficult to avoid that the illumination light amount distribution itself of the illumination light IL8 irradiated on the first light-transmitting flat plate P1 is uneven to some extent.

  Therefore, in the present invention, during the exposure operation on the wafer W, the illumination light IL8 is scanned on the first light-transmissive plate P1, and the integrated intensity distribution by the illumination light IL8 is averaged by averaging by the scanning. Adopt the method

  FIG. 11 is a diagram showing a specific example thereof. A central position IL80 of the illumination light IL8 having an intensity distribution indicated by contour lines is irradiated to a predetermined position on the first translucent flat plate P1 at a certain time. Yes. Thereafter, the intensity distribution of the illumination light IL8 is repeatedly scanned on the first translucent flat plate P1 along the path SP1. Further, before the certain time, the first translucent flat plate P1 is repeatedly scanned along the path SP0.

  The relative scanning between the intensity distribution of the illumination light IL8 and the first light-transmitting flat plate P1 is performed by moving the Y movable mirror 12 and the X movable mirror 14 during the exposure operation to change the center position IL80 of the illumination light IL8. This can be done by repeatedly moving.

  Note that the integrated intensity distribution of the illumination light IL8 does not need to be uniform over the entire surface of the first translucent flat plate P1. That is, on the first translucent flat plate P1, in the region where the first diffraction gratings G11 and G12 are formed, the diffracted light generated by the first diffraction gratings G11 and G12 is finally converted into the wafer. It is only necessary that the integrated intensity distribution of the illumination light IL8 is made uniform in the region reaching W. As shown in FIG. 11, the region is a region such as a predetermined region SP0 including the central portion on the first translucent flat plate P1.

  Further, the uniformity of the integrated intensity in the area SP0 needs to be within about ± 2% with respect to the average value of the integrated intensity in the area SP0. However, when the line width control requirement of the pattern to be exposed and formed on the wafer W is severe, the uniformity is preferably within about ± 0.5%.

  Alternatively, the relative position is also realized by fixing the center position IL80 of the illumination light IL8 and moving the first translucent flat plate P1, the second translucent flat plate P2, and the wafer W integrally. be able to.

  Needless to say, when the illumination light amount distribution itself of the illumination light IL8 may be somewhat uneven, it is not necessary to perform such scanning.

  By the way, the exposure apparatus of the present invention uses the illumination light of the minimal illumination NA as described above. However, since the illumination light (diffracted light) reaching one point on the wafer W is plural, the second Irradiation is performed from a plurality of regions on the diffraction grating G21 and the like and the first diffraction gratings G11 and G12. In addition, since the light flux that forms the interference fringes on the wafer W is diffracted light from the second diffraction grating or the like, even if there is a foreign substance or the like on the second diffraction grating G21 or the like, the foreign matter However, it is not exposed and transferred onto the wafer W while maintaining the shape as it is.

  Here, in order to further reduce the adverse effect of the foreign matters and defects on the second diffraction gratings G21 and G22 on the interference fringes formed on the wafer W, the distance D2 between the second diffraction gratings G21 and G22. Is preferably set to a predetermined value or more. As a result, the light irradiated to one point on the wafer W can be diffracted from more places on the second diffraction gratings G21 and G22, and the adverse effects of the foreign matter and defects can be alleviated. Because it can.

Here, the diffracted light applied to the wafer W from the second diffraction grating G21 is applied to the wafer W while being inclined by the angles θ0 and θ1 as described above. In more preferable conditions, θ0 = θ1. At this time, from the equations 2 and 3, the effective wavelength of the illumination light is λ, and the period of the second diffraction grating G21 is T2.
(Formula 9)
sin θ0 = λ / (2 × T2)
Therefore, assuming that the approximation of sin θ0≈tan θ0 is established to some extent, the diffracted light irradiated to one point on the wafer W is on the second diffraction grating G21.
(Formula 10)
D5 = 2 × D2 × λ / (2 × T2)
Irradiation is performed from a portion centered at two points separated by a mutual distance D5 represented by.

In order to mitigate the adverse effects of the foreign matter and defects, the light collected at one point on the wafer W is composed of light from a portion that spreads, for example, about 30 times the period T2 of the second diffraction grating G21. It is preferable that the adverse effect is smoothed. Expressing this as an expression,
(Formula 11)
D5 ≧ 30 × T2
It becomes like this.
From the above Equation 10 and Equation 11, the distance D2 is
(Formula 12)
D2 ≧ 30 × T2 ² / λ
It is preferable to satisfy the following condition.

Further, in order to further alleviate the adverse effect, the light collected at one point on the wafer W is composed of light from a portion that spreads, for example, about 100 times the period T2 of the second diffraction grating G21. It is preferable that the adverse effect is smoothed. At this time, the condition that the interval D2 should satisfy is based on the same consideration.
(Formula 13)
D2 ≧ 100 × T2 ² / λ
It becomes.

  Further, in order to further reduce the adverse effect of the foreign matter / defect on the second diffraction grating G21 on the pattern exposed on the wafer W, in the present invention, the exposure to the wafer W is multiplexed by the multiple exposure shown below. It can also be exposure.

  That is, after the first exposure is performed with the positional relationship in the XY direction between the second diffraction gratings G21 and G22 and the wafer W being a predetermined relationship, the relative relationship is an integral multiple of the period of the second diffraction gratings G21 and G22. It is also possible to perform a second exposure and move a plurality of times to perform multiple exposures while performing the same movement.

  As a result, a light and dark pattern of interference fringes by diffracted light generated from more parts on the second diffraction gratings G21 and G22 is superimposed and exposed at one point on the wafer W, and the second diffraction is performed. The adverse effect of the foreign matters and defects existing on the lattices G21 and G22 is further reduced by the averaging effect.

  In addition, when using the 2nd diffraction grating G21 which has a one-dimensional period, it cannot be overemphasized that the movement of the said relative relationship to the direction orthogonal to the period direction may be arbitrary distances. No.

  By the way, in order to further reduce the adverse effects caused by the foreign matter or the like attached on the second diffraction grating G21, the second diffraction grating G21 is interposed between the second diffraction grating G21 and the wafer W as shown in FIG. It is also possible to provide a thin film (pellicle) PE2 for preventing foreign matter adhesion. Further, the foreign matter can be removed by replacing the pellicle PE2 every time a predetermined number of wafers W are exposed, for example.

As the pellicle PE2, for example, a pellicle made of an organic resin used for preventing foreign matter from adhering to a reticle used in a projection exposure apparatus can be used.
Alternatively, a light-transmitting flat plate made of an inorganic material such as synthetic quartz can be used as the pellicle PE2.

A pellicle PE1 may be provided on the light source side of the first diffraction gratings G11 and G12 to prevent foreign matter from adhering to the first diffraction gratings G11 and G12.
Alternatively, as shown in FIG. 13, in order to prevent foreign matter from adhering to the second diffraction grating G21, a protective layer PE3 is formed on the second diffraction grating G21 on the second light transmitting substrate P2. Can be provided. This protective layer PE3 is made of a translucent film such as silicon dioxide formed by, for example, CVD (Chemical Vapor Deposition), and the surface thereof is planarized by CMP (Chemical Mechanical Polishing) as necessary. Is. The thickness of the foreign matter protective layer PE3 is, for example, about 1 μm.

  It should be noted that the foreign matter adhering to the protective layer PE3 and the foreign matter adhering to the second diffraction grating G21 without providing the protective layer PE3 are equivalent in terms of adverse effects of the foreign matter on the interference fringes to be formed on the wafer. is there. However, by providing the protective layer PE3, the surface of the second diffraction grating G21 can be substantially flattened. Therefore, cleaning and inspection of foreign matters, contamination, and the like attached to the surface are extremely easy. Therefore, the installation of the protective layer PE3 is effective.

  In the above example, the first diffraction gratings G11, G12, G13, and G14 are phase modulation type diffraction gratings, and the second diffraction gratings G21 and G22 are intensity modulation type diffraction gratings. The configuration of the diffraction grating is not limited to this.

  For example, any of the diffraction gratings may be a diffraction grating that modulates both the phase and intensity of transmitted light, such as a halftone phase shift reticle. In addition, when the interference fringes formed on the wafer W do not require such a high contrast lasting property, generation of unnecessary diffracted light from the first diffraction grating is allowed. A modulation type diffraction grating can also be used.

  In the above example, the first diffraction grating G11, G12 and the second diffraction grating G21 are formed on different light-transmitting flat plates, but both diffraction gratings have the same light-transmitting property. It can also be formed on a flat plate.

  FIG. 14 is a diagram showing an example in which the first diffraction gratings G15, 16 and the second diffraction grating G23 are formed on the light source side and the wafer W side of one translucent flat plate P3, respectively. Also in this example, the structure and manufacturing method of each diffraction grating are the same as those in the above example. The lens 35 and the illumination optical system upstream thereof are the same as in the above-described example.

  Further, in one embodiment of the present invention, it is possible to expose a bright and dark pattern of interference fringes on the wafer W by disposing only a single diffraction grating in close proximity to the wafer W. .

  FIG. 15 shows an example in which the diffraction gratings G17 and G18 formed on the wafer W side of the translucent flat plate P4 are arranged close to each other with a distance D3 in the vicinity of the wafer W side. Also in this example, the structures and manufacturing methods of the diffraction gratings G17 and G18 are the same as those in the above example. The lens 35 and the illumination optical system upstream thereof are the same as in the above-described example. Furthermore, it is preferable that the value of the interval D3 satisfies the same condition as the interval D2 in the above example.

  In this example, the effective wavelength λ is the wavelength of illumination light in the medium having the lowest refractive index among the translucent media existing on the illumination optical path from the diffraction gratings G17 and G18 to the wafer W. .

  In this example, the diffracted light (first-order diffracted light) generated by the diffraction gratings G17 and G18 is irradiated onto the wafer W and interferes with the wafer W, so that a light / dark pattern of interference fringes is formed on the wafer W. Will be.

  In any of the above examples, the first diffraction gratings G11 and G12 and the second diffraction grating G21 are exchanged according to the period T3 of the bright and dark pattern of interference fringes to be exposed on the wafer W. There is a need. FIG. 17 is a view showing an example of the replacement mechanism, FIG. 17A is a view of the replacement mechanism viewed from the −Z direction, and FIG. 17B is the vicinity of the portion AB in FIG. 17A. FIG.

  The flat plate loader 42 provided with chuck portions 43a, 43b, 43c, 43d for holding the peripheral edge portion P2E of the second light transmissive parallel plate P2 provided with the second diffraction grating by means of vacuum suction or the like It can slide in the direction and can move up and down in the Z direction.

  Before the replacement, the second translucent parallel plate P2 is held by the second holding mechanisms 37a, 37b, and 37c. In response to this state, the flat plate loader 42 enters the lower part of the second translucent parallel plate P2 from the X direction and rises upward. And chuck | zipper part 43a, 43b, 43c, 43d adsorb | sucks the peripheral part P2E of the 2nd translucent parallel plate P2.

  Thereafter, the second holding mechanisms 37a, 37b, and 37c are retracted in the radial direction as indicated by the white arrows in the figure, and in this state, the flat plate loader 42 is retracted in the + X direction and the second light-transmissive parallel plate P2 is retracted. Take away. Then, another second translucent parallel plate to be newly loaded is installed on the second holding mechanisms 37a, 37b, and 37c through the reverse operation of the above, and the second translucent parallel plate The exchange is complete.

The replacement mechanism for the first light-transmissive parallel plate P1 has the same configuration as described above.
In addition, since the space | interval of the 1st translucent parallel plate P1 and the 2nd translucent parallel plate P2 is short, it is difficult to insert the said flat plate loader in the space | interval.

  Therefore, as shown in FIG. 16, it is preferable that the first holding mechanism 36a and the second holding mechanism 37a and the like are also movable by the support member 41 in the radial direction and the Z direction in the XY plane direction. Thereby, the clearance for loading the flat plate loader can be secured.

  Note that the Z drive mechanisms such as the first holding mechanism 36a and the second holding mechanism 37a have the distance D2 between the second diffraction grating G21 and the wafer W, and the first diffraction gratings G11 and G12 and the second. It can also be used when the distance D1 from the diffraction grating G21 is set to a predetermined value.

  In addition, as shown in FIG. 16, the peripheral part P1E of the 1st translucent parallel plate P1 and the peripheral part P2E of the 2nd translucent parallel plate P2 are stepped so that it may become thin with respect to those center parts. Has been processed. The vacuum suction part P1V provided in the first holding mechanism 36a and the like, and the vacuum suction part P2V provided in the second holding mechanism 37a and the like pass through these stepped peripheral parts P1E and PE2. The first translucent parallel plate P1 and the second translucent parallel plate P2 are held.

  In the above example, air (nitrogen or a rare gas may be present) is present between the second diffraction grating G21 and the wafer W. Instead, a predetermined dielectric is satisfied. It is also good. Thereby, the substantial wavelength of the illumination light (diffracted light) irradiated to the wafer W can be reduced by the refractive index of the dielectric, and the period of the bright and dark pattern of the interference fringes formed on the wafer W. It becomes possible to further reduce T3. For this purpose, it goes without saying that the period T2 of the second diffraction grating G21 and the period T1 of the first diffraction gratings G11 and G12 also need to be reduced in proportion thereto.

  FIG. 18A is a diagram showing an example of a wafer stage 38a and the like suitable for this. Continuous side walls 38b and 38c are provided around the wafer stage 38a, and a liquid 46 such as water can be held in a portion surrounded by the side walls 38b and c. Thereby, the space between the wafer W and the second translucent flat plate P2 is filled with water, that is, the space between the wafer W and the second diffraction grating G21 is filled with water as a dielectric, and the wavelength of the illumination light. Is reduced by the refractive index of water (1.46 for light with a wavelength of 193 nm).

A water supply mechanism 44 and a drainage mechanism 45 are also provided so that fresh water without contamination is supplied and drained to the portion surrounded by the side walls 38b, c.
Further, as shown in FIG. 18B, the uppermost surfaces of the side walls 38d and 38e of the wafer stage 38a are made higher than the lower surface of the first light transmitting flat plate P1, and the first light transmitting flat plate P1 and the second light transmitting flat plate P1. The space between the light flat plates P2 can also be filled with water. The functions of the water supply mechanism 44a and the drainage mechanism 45b are the same as described above.

  As a result, the entire optical path from the first diffraction grating G11, G12 to the wafer W can be covered with a dielectric (water) other than air (or nitrogen or a rare gas), and the effective wavelength λ of the illumination light described above. Can be reduced by the refraction of water. As a result, a pattern having a finer period can be exposed.

In addition, when it is effective to fill a dielectric such as water only between the first translucent flat plate P1 and the second translucent flat plate P2, the configuration as shown in FIG. 19 is adopted. You can also.
This is to provide a continuous side wall 47 around the first translucent flat plate P1, thereby storing water between the first translucent flat plate P1 and the second translucent flat plate P2. . The functions of the water supply mechanism 44c and the drainage mechanism 45c are the same as described above.
The refractive index of the dielectric material to be filled between the first diffraction gratings G11 and G12 and the wafer W or between the first light transmitting flat plate P1 and the second light transmitting flat plate P2 is 1.2. The above is desirable. This is because if the refractive index is 1.2 or less, the fineness of the pattern that can be exposed cannot be sufficiently improved.

  The wafer W having the light and dark pattern exposed by the interference fringes as described above is transferred to the outside of the exposure apparatus by a wafer loader (not shown) and is transferred to the developing apparatus. By development, a resist pattern corresponding to the exposed light and dark pattern is formed on the photoresist on the wafer W. In the etching apparatus, a predetermined pattern is formed on the wafer W by etching the wafer W or a predetermined film formed on the wafer W using the resist pattern as an etching mask.

  A manufacturing process of an electronic device such as a semiconductor integrated circuit, a flat panel display, a thin film magnetic head, or a micromachine includes a process of forming the fine pattern as described above over a plurality of layers. An electronic device can be manufactured by using the above-described exposure method by the exposure apparatus of the present invention in at least one of such multiple pattern forming steps.

  In addition, in the at least one step, a pattern having a predetermined shape is formed by a general projection exposure apparatus on the photoresist PR on the wafer W that has been exposed to the bright and dark pattern by the interference fringes using the exposure method by the exposure apparatus of the present invention. And the pattern formation can be performed by developing the photoresist PR subjected to the synthetic exposure.

Or, conversely, a light and dark pattern due to interference fringes is synthesized and exposed to the photoresist PR on the wafer W, which has been exposed to a pattern of a predetermined shape by a general projection exposure apparatus, using the above exposure method by the exposure apparatus of the present invention. Then, the pattern PR can be formed by developing the synthetically exposed photoresist PR.
As described above, the present invention is not limited to the above-described embodiment, and can have various configurations without departing from the gist of the present invention. In addition, the entire disclosure of Japanese Patent Application No. 2004-366896 filed on December 17, 2004, including the specification, claims, drawings, and abstract, is incorporated herein by reference in its entirety. Yes.

The exposure method of the present invention can be implemented in the manufacture of electronic devices such as semiconductor integrated circuits, flat panel displays, thin film magnetic heads, micromachines, etc., and can be used industrially.
The exposure apparatus of the present invention can be implemented in the manufacture of electronic devices such as semiconductor integrated circuits, flat panel displays, thin film magnetic heads, and micromachines, and can be used industrially.

    The electronic device manufacturing method and the electronic device of the present invention can be used in the industry in the manufacturing process, that is, in the industry for producing semiconductors, and the electronic device as a product is used in various electronic equipment industries. It is possible.

Claims (83)

An exposure method that exposes a pattern on a photosensitive substrate with illumination light from a light source comprising:
Irradiating the first diffraction grating with the illumination light from the light source;
Irradiating a second diffraction grating disposed opposite to the first diffraction grating with the diffracted light generated by the first diffraction grating;
Irradiating the diffracted light generated by the second diffraction grating onto the photosensitive substrate disposed in close proximity to the second diffraction grating;
Including
An exposure method, wherein a diffraction grating having a two-dimensional period is used as the first diffraction grating and the second diffraction grating. The period of the first predetermined direction of the first diffraction grating is approximately twice the period of the first predetermined direction of the second diffraction grating;
2. The exposure method according to claim 1, wherein the period of the first diffraction grating in the second predetermined direction is approximately twice the period of the second diffraction grating in the second predetermined direction. .   As the illumination light with which the first diffraction grating is irradiated, the electric field component in the direction orthogonal to the first direction where the period is minimum in the second diffraction grating is larger than the electric field component in the first direction. 2. The exposure method according to claim 1, wherein illumination light is used.   The exposure method according to claim 1, wherein a divergence angle of the illumination light applied to the first diffraction grating is adjustable.   The exposure method according to claim 1, wherein a divergence angle of an optical path through which the illumination light applied to the first diffraction grating can pass is adjustable.   6. The exposure method according to claim 5, wherein the divergence angle is adjusted according to the expansion and contraction of the photosensitive substrate.   By integrating the intensity distribution of the illumination light applied to the first diffraction grating and the relative positional relationship between the first diffraction grating and the time, the integration of the illumination light on the first diffraction grating is performed. 2. The exposure method according to claim 1, wherein the intensity distribution is substantially uniform in a predetermined region including a central portion of the first diffraction grating. The relative positional relationship between the second diffraction grating and the substrate in the in-plane direction of the substrate,
Shifting in the first predetermined direction by a length that is an integral multiple of the period in the first predetermined direction of the second diffraction grating, or an integer multiple of the period in the second predetermined direction of the second diffraction grating The exposure method according to claim 1, wherein the steps are repeated a plurality of times while shifting in the second predetermined direction by the length of.   The exposure method according to claim 1, wherein a distance between the second diffraction grating and the substrate is greater than 1 μm and less than 500 μm.   The exposure method according to claim 1, wherein a distance between the second diffraction grating and the substrate is greater than 5 μm and less than 100 μm. The distance D between the second diffraction grating and the substrate is λ as the effective wavelength of the illumination light, and T as the minimum period of the second diffraction grating.
30 × T ² / λ ≦ D
The exposure method according to claim 1, wherein the relationship is satisfied. The distance D between the second diffraction grating and the substrate is λ as the effective wavelength of the illumination light, and T as the minimum period of the second diffraction grating.
100 × T ² / λ ≦ D
The exposure method according to claim 1, wherein the relationship is satisfied.   At least one of the second diffraction grating and the substrate and between the first diffraction grating and the second diffraction grating is filled with a dielectric having a refractive index of 1.2 or more at the exposure wavelength. The exposure method according to claim 1, wherein:   The exposure method according to claim 13, wherein a part of the dielectric is water.   The second diffraction grating is formed on the surface of the second light-transmitting flat plate on the substrate side or in the vicinity of the surface of the second light-transmitting flat plate on the substrate side. Item 2. The exposure method according to Item 1.   2. The exposure method according to claim 1, wherein a translucent flat plate or thin film is provided on the light source side of the first diffraction grating.   2. The exposure method according to claim 1, wherein a translucent flat plate or thin film is provided on the substrate side of the second diffraction grating.   The exposure method according to claim 1, wherein a temporal coherence distance of the illumination light is 100 μm or less. An exposure method that exposes a pattern on a photosensitive substrate with illumination light from a light source comprising:
Placing a diffraction grating having a period of not more than twice the effective wavelength of the illumination light close to and opposite to the light source side of the substrate;
Irradiating the diffraction grating with the illumination light while changing a relative positional relationship between the intensity distribution of the illumination light from the light source and the diffraction grating with time;
Irradiating the substrate with diffracted light generated by the diffraction grating;
An exposure method comprising:   20. The exposure method according to claim 19, wherein the change in the relative positional relationship is performed by moving the intensity distribution of the illumination light while fixing the diffraction grating.   The exposure method according to claim 19, wherein a phase modulation type diffraction grating that modulates a phase of transmitted light is used as the diffraction grating.   The exposure method according to claim 19, wherein an intensity modulation type diffraction grating that modulates the intensity of transmitted light is used as the diffraction grating.   The exposure method according to claim 19, wherein a diffraction grating having a two-dimensional period is used as the diffraction grating. While using a diffraction grating having a one-dimensional period as the diffraction grating,
The illumination light used for irradiating the diffraction grating is an illumination light whose electric field component in a direction orthogonal to the periodic direction of the diffraction grating is larger than an electric field component in the periodic direction of the diffraction grating. Item 20. The exposure method according to Item 19.   As the illumination light irradiating the diffraction grating, an illumination light having an electric field component in a direction orthogonal to a first direction in which the period is minimal in the diffraction grating is larger than an electric field component in the first direction. The exposure method according to claim 23, characterized in that:   The exposure method according to claim 19, wherein a divergence angle of the illumination light applied to the diffraction grating is adjustable.   The exposure method according to claim 19, wherein a divergence angle of an illumination optical path through which the illumination light applied to the diffraction grating can pass is adjustable.   28. The exposure method according to claim 27, wherein the divergence angle is adjusted according to expansion and contraction of the photosensitive substrate. The relative positional relationship between the diffraction grating and the substrate in the in-plane direction of the substrate,
While shifting in the direction orthogonal to the direction of the period of the diffraction grating, or shifting in the direction of the period by an integral multiple of the length of the period of the diffraction grating,
The exposure method according to claim 19, wherein each of the steps is repeated a plurality of times.   The exposure method according to claim 19, wherein a distance between the diffraction grating and the substrate is larger than 1 μm and smaller than 500 μm.   The exposure method according to claim 19, wherein a distance between the diffraction grating and the substrate is greater than 5 μm and less than 100 μm. The distance D between the diffraction grating and the substrate is λ as the effective wavelength of the illumination light, and T as the minimum period of the diffraction grating.
30 × T ² / λ ≦ D
The exposure method according to claim 19, wherein the relationship is satisfied. The distance D between the diffraction grating and the substrate is λ as the effective wavelength of the illumination light, and T as the minimum period of the diffraction grating.
100 × T ² / λ ≦ D
The exposure method according to claim 19, wherein the relationship is satisfied.   20. The exposure method according to claim 19, wherein the gap between the diffraction grating and the substrate is filled with a dielectric having a refractive index of 1.2 or more at the exposure wavelength.   The exposure method according to claim 34, wherein a part of the dielectric is water.   The exposure method according to claim 19, wherein a translucent flat plate or thin film is provided on the substrate side of the diffraction grating.   The exposure method according to claim 19, wherein a temporal coherence distance of the illumination light is 100 μm or less. An exposure method that exposes a pattern on a photosensitive substrate with illumination light from a light source comprising:
Irradiating the first diffraction grating with the illumination light from the light source;
Irradiating a second diffraction grating disposed opposite to the first diffraction grating with the diffracted light generated by the first diffraction grating;
Irradiating the diffracted light generated by the second diffraction grating onto the photosensitive substrate disposed in close proximity to the second diffraction grating;
Including
An exposure method, wherein a divergence angle of the illumination light applied to the first diffraction grating is adjustable.   39. The exposure method according to claim 38, wherein the divergence angle is adjusted according to the expansion and contraction of the photosensitive substrate.   By integrating the intensity distribution of the illumination light applied to the first diffraction grating and the relative positional relationship between the first diffraction grating and the time, the integration of the illumination light on the first diffraction grating is performed. 39. The exposure method according to claim 38, wherein the intensity distribution is made substantially uniform in a predetermined region including a central portion of the first diffraction grating. The relative positional relationship between the second diffraction grating and the substrate in the in-plane direction of the substrate,
Shifting in the first predetermined direction by a length that is an integral multiple of the period in the first predetermined direction of the second diffraction grating, or an integer multiple of the period in the second predetermined direction of the second diffraction grating 39. The exposure method according to claim 38, wherein the steps are repeated a plurality of times while being shifted in the second predetermined direction by the length of.   39. The exposure method according to claim 38, wherein a distance between the second diffraction grating and the substrate is greater than 1 [mu] m and less than 500 [mu] m.   39. The exposure method according to claim 38, wherein a distance between the second diffraction grating and the substrate is greater than 5 [mu] m and less than 100 [mu] m. The distance D between the second diffraction grating and the substrate is λ as the effective wavelength of the illumination light, and T as the minimum period of the second diffraction grating.
30 × T ² / λ ≦ D
40. The exposure method according to claim 38, wherein the relationship is satisfied. The distance D between the second diffraction grating and the substrate is λ as the effective wavelength of the illumination light, and T as the minimum period of the second diffraction grating.
100 × T ² / λ ≦ D
40. The exposure method according to claim 38, wherein the relationship is satisfied.   At least one of the second diffraction grating and the substrate and between the first diffraction grating and the second diffraction grating is filled with a dielectric having a refractive index of 1.2 or more at the exposure wavelength. The exposure method according to claim 38, wherein:   The exposure method according to claim 46, wherein a part of the dielectric is water.   The second diffraction grating is formed on the surface of the second light-transmitting flat plate on the substrate side or in the vicinity of the surface of the second light-transmitting flat plate on the substrate side. Item 39. The exposure method according to Item 38.   39. The exposure method according to claim 38, wherein a translucent flat plate or thin film is provided on the light source side of the first diffraction grating.   39. The exposure method according to claim 38, wherein a translucent flat plate or thin film is provided on the substrate side of the second diffraction grating.   39. The exposure method according to claim 38, wherein a temporal coherence distance of the illumination light is 100 [mu] m or less.   52. An electronic device manufacturing method using the exposure method according to any one of claims 1 to 51 in at least a part of a step of forming a circuit pattern constituting an electronic device.   52. At least a part of a circuit pattern forming step constituting an electronic device uses synthetic exposure of a projection exposure method using a projection exposure apparatus and the exposure method according to any one of claims 1 to 51. An electronic device manufacturing method.   An electronic device manufactured by the electronic device manufacturing method according to claim 52.   An electronic device manufactured by the electronic device manufacturing method according to claim 53. The interference pattern generated by the illumination light from the light source and the first diffraction grating formed on the first light transmitting flat plate and the second diffraction grating formed on the second light transmitting flat plate is photosensitive. An exposure apparatus for exposing on a substrate of:
An illumination optical system for irradiating the first diffraction grating with the illumination light from the light source disposed between the light source and the first diffraction grating, the illumination light irradiating the first diffraction grating An exposure apparatus having an illumination optical system that makes the divergence angle of the light variable.   57. The exposure apparatus according to claim 56, wherein the divergence angle of the illumination light applied to the first diffraction grating is varied by moving at least a part of an optical member included in the illumination optical system. . An illumination light distribution variable mechanism that changes a relative positional relationship of the intensity distribution of the illumination light irradiated to the first diffraction grating with the first diffraction grating with time;
58. The integrated intensity distribution of the illumination light on the first diffraction grating can be substantially uniform in a predetermined region including a central portion of the first diffraction grating. Exposure equipment.   59. The exposure apparatus according to claim 58, wherein the illumination light distribution variable mechanism includes a movable mechanism provided in the illumination optical system.   59. The exposure apparatus according to claim 58, wherein the illumination light distribution variable mechanism comprises a translational movable mechanism of at least two reflecting members provided in the illumination optical system.   The illumination light distribution variable mechanism includes a mechanism that integrally moves the first diffraction grating, the second diffraction grating, and the substrate relative to the illumination optical system. Item 58. The exposure apparatus according to Item 58. A first holding mechanism for holding the first diffraction grating formed on the first translucent flat plate at a predetermined position;
A second holding mechanism that holds the second diffraction grating formed on the second light-transmitting flat plate in alignment with a position facing the first diffraction grating;
A substrate holding mechanism for holding the substrate in alignment with the second diffraction grating in a close proximity and facing position;
58. An exposure apparatus according to claim 56 or 57, comprising:   63. The exposure according to claim 62, wherein the substrate holding mechanism holds the rotational relationship between the direction of the period of the first diffraction grating and the direction of the period of the second diffraction grating in alignment with each other. apparatus.   58. The method according to claim 56, further comprising at least one of a first exchange mechanism for exchanging the first translucent flat plate and a second exchange mechanism for exchanging the second translucent flat plate. The exposure apparatus described.   58. The exposure apparatus according to claim 56 or 57, wherein an interval between the second diffraction grating and the substrate is set to be larger than 1 [mu] m and smaller than 500 [mu] m.   58. The exposure apparatus according to claim 56 or 57, wherein an interval between the second diffraction grating and the substrate is set to be larger than 5 [mu] m and smaller than 100 [mu] m. The distance D between the second diffraction grating and the substrate is λ, the effective wavelength of the illumination light is λ, and the minimum period of the second diffraction grating is T,
30 × T ² / λ ≦ D
58. The exposure apparatus according to claim 56, wherein the exposure apparatus is set so as to satisfy the relationship. The distance D between the second diffraction grating and the substrate is λ, the effective wavelength of the illumination light is λ, and the minimum period of the second diffraction grating is T,
100 × T ² / λ ≦ D
58. The exposure apparatus according to claim 56, wherein the exposure apparatus is set so as to satisfy the relationship.   A refractive index at the exposure wavelength of at least one part between the second diffraction grating and the substrate and at least one part between the first diffraction grating and the second diffraction grating is 1.2 at the exposure wavelength. 58. The exposure apparatus according to claim 56 or 57, further comprising a liquid supply mechanism filled with the above dielectric liquid.   70. The exposure apparatus according to claim 69, wherein the dielectric liquid is water.   58. The exposure apparatus according to claim 56 or 57, wherein a temporal coherence distance of the illumination light is 100 [mu] m or less. An exposure apparatus for exposing an interference pattern generated by illumination light from a light source and a diffraction grating formed on a translucent flat plate on a photosensitive substrate:
An illumination optical system provided between the light source and the diffraction grating and irradiating the translucent flat plate with the illumination light from the light source;
A first holding mechanism for holding the translucent flat plate in a predetermined position;
A substrate holding mechanism that holds the substrate in alignment with and close to the translucent flat plate;
Have
An illumination light distribution variable mechanism that changes the relative positional relationship of the intensity distribution of the illumination light with the translucent flat plate over time, and the integrated intensity distribution of the illumination light on the translucent flat plate is converted into the translucent plate. An exposure apparatus characterized in that it can be made substantially uniform in a predetermined region including the central portion of the conductive flat plate.   The exposure apparatus according to claim 72, wherein the illumination light distribution variable mechanism is a movable mechanism provided in the illumination optical system.   75. The exposure apparatus according to claim 72, wherein the illumination light distribution variable mechanism includes a translational movable mechanism of at least two reflecting members provided in the illumination optical system.   75. The exposure apparatus according to claim 72, wherein the illumination light distribution variable mechanism includes a mechanism that integrally moves the translucent flat plate and the substrate relative to the illumination optical system.   The exposure apparatus according to claim 72, wherein the illumination optical system can change a divergence angle of illumination light applied to the translucent flat plate.   77. The exposure apparatus according to claim 72, wherein a distance between the translucent flat plate and the substrate is set to be larger than 1 μm and smaller than 500 μm.   77. The exposure apparatus according to claim 72, wherein a distance between the translucent flat plate and the substrate is set to be larger than 5 μm and smaller than 100 μm. The distance D between the diffraction grating and the substrate is defined as λ as the effective wavelength of the illumination light, and T as the minimum period of the diffraction grating.
30 × T ² / λ ≦ D
77. The exposure apparatus according to claim 72, wherein the exposure apparatus is set so as to satisfy the relationship. The distance D between the diffraction grating and the substrate is defined as λ as the effective wavelength of the illumination light, and T as the minimum period of the diffraction grating.
100 × T ² / λ ≦ D
77. The exposure apparatus according to claim 72, wherein the exposure apparatus is set so as to satisfy the relationship.   77. A liquid supply mechanism for filling at least a part between the light-transmitting flat plate and the substrate with a dielectric liquid having a refractive index of 1.2 or more at the exposure wavelength. The exposure apparatus according to one item.   The exposure apparatus according to claim 81, wherein the dielectric liquid is water.   77. The exposure apparatus according to claim 72, wherein a temporal coherence distance of the illumination light is 100 μm or less.

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