JPH08227841A - Light source filter, production aligner using filter thereof and projection exposure method - Google Patents

Abstract

PURPOSE: To provide the light source filter, which can obtain all excellent characteristics without depending on the periodicity of a pattern, layout, sizes, roughness and fineness and the like. CONSTITUTION: In a multiple-reflection-interference type light-source filter 3, a semipermeable film 32 is formed on a substrate 31, a transparent region 33 is formed thereon and another semipermeable film 32 is formed thereon. Exposure light 61, which is emitted from a light source 1 and transmitted through the multiple-reflection- interference type light-source filter 3 without reflection by way of a fly-eye lens 2, and exposure light 62, which is reflected in a multiple pattern at the boundary of the transparent region 33 and the semipermeable film 32 and transmitted, generate the phase difference of 1/2 wavelength. The images of diffracted lights 71 and 72, which are transmitted through a condenser lens 4 and diffracted at a mask 5, are formed on a wafer 10 with a projection lens 8 and a pupil plane 9 of the lens 8. The image-formation amplitudes of the first and second exposure lights at the focal-point position are inverted. The distribution of the light intensity becomes the steep, excellent profile, whose side lobe is offset. The contrast is improved, the resolution is greatly improved and the focal. depth is also expanded to a large extent.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light source filter and a projection exposure apparatus using the same. The present invention relates to a light source filter whose transmittance can be controlled and a projection exposure apparatus using the same.

[0002]

2. Description of the Related Art In recent years, as semiconductor elements have been highly integrated, circuit structures with finer patterns have been required, and further miniaturization of lithography techniques has been remarkably demanded. Therefore, a projection type exposure apparatus called a stepper has been used and studies have been made to meet the demand.

The focus of the conventional studies has been on shortening the wavelength of the light source used in the exposure apparatus and accompanying improvements in peripheral technologies such as optical systems and resistors. : 436 nm), i-line (wavelength: 36
5 nm), and De using a KrF excimer laser
It covers up to the ep UV region (wavelength: 248 nm).

However, especially with the rapid integration of semiconductor devices, the minimum line width requirement of the circuit is 0.3 μm or less,
Further, it is approaching a value of 0.2 μm or less, which is equal to or less than the wavelength of the light source.

Here, the limit resolution R and the depth of focus (DOF) of the projection type exposure apparatus are generally given by the Rayleigh equation shown in the equation (1).

Shortening the wavelength of the light source is important for improving resolution and the like. However, the high performance of the exposure system as a whole, such as the achievement of a narrow-band light source and an aberration-free optical system accompanying the shortening of the wavelength, and the construction of peripheral processes centered on a resist with a transmittance suitable for the exposure wavelength range. Therefore, the optical system centering on the reduction of the wavelength of the light source and the reduction projection lens is approaching the limit.
In addition, as a matter of course, investment in these exposure apparatuses and exposure processes also increases, making it difficult to reduce costs.

Therefore, in order to improve the resolution without shortening the wavelength of the light source from the formula (1), it is necessary to increase the NA (numerical aperture) of the projection lens.

However, as is clear from the equation (2), increasing the NA causes a decrease in the depth of focus, which is another important characteristic in lithography, and the numerical aperture NA is optimized in order to achieve both characteristics satisfactorily. is necessary. In addition, increasing the NA is also difficult in terms of manufacturing technology, and at present, the so-called maximum numerical aperture NA is about 0.6. Further, with commonly used quartz-based lens materials, it is difficult to correct chromatic aberration in the short wavelength region and absorption increases, so that lens distortion due to heat generation becomes a problem.

[0009]

[Equation 1]

Therefore, in recent years, some methods have been proposed for improving the resolution and the depth of focus without improving the wavelength of the light source and the numerical aperture NA of the projection lens.

A method for improving resolution and depth of focus by processing a mask or installing a light-shielding plate in an optical system of an exposure apparatus can use the same light source and lens as the exposure apparatus, and can also use a resist or the like. By making the most of the peripheral processes of, it is possible to deploy without significant cost increase.

For example, according to JP-A-57-62052, at least one of the light transmitting portions on both sides of the opaque portion of the mask having a periodic pattern has a 180 ° phase inversion with respect to the adjacent light transmitting portion. A method is disclosed in which a transparent film is formed to improve the resolution as compared with a lens having the same numerical aperture NA (first method).

According to Japanese Patent Laid-Open No. 62-67514, as a means for improving the resolution of an isolated (single) pattern, the phase is inverted in the range where a good resolution can be obtained around the single light transmitting portion of the mask, which is also transparent. A method of providing a light transmitting portion formed of a film as an auxiliary pattern is disclosed (second method).

In addition, Journal of Vacuu
m Science Technology B9
(6) In (3113) 1991, the phase of the diffracted light from the mask pattern is controlled, and a light source filter is installed in the pupil portion of the reduced projection level so that a multi-focus imaging system can be formed. A method effective for improving the characteristics of a single pattern having no repeatability such as (3rd method) is disclosed.

Further, in Japanese Patent Laid-Open No. 4-101148, it is determined on at least one position of the pupil plane of the illumination optical system or its conjugate plane or the pupil plane of the projection optical system based on the Fourier transform pattern obtained from the fine pattern of the mask. A method has been disclosed in which a light-shielding plate having one or more sets of light-transmitting portions is provided and the resolution and the depth of focus of a repetitive pattern are improved as compared with a lens having the same numerical aperture NA (fourth method).

However, the first method is not effective unless it has a regular repeating pattern. Also,
In some cases, a pattern not included in the mask pattern may be transferred to the end of the periodic pattern due to the phase inversion of the shift end. Furthermore, when laying out an actual circuit, it is necessary to dispose a shifter in a complicated circuit pattern so that a good effect can be obtained, and this work becomes very complicated.
Furthermore, depending on the circuit configuration, the shifter layout may be inconsistent and the shifter layout may be difficult, which is a major obstacle to practical use. In addition, even when a mask is produced, no matter where the shifter is formed above or below the opaque (light-shielding) pattern, there is an overlay process that is not available in the conventional mask production process. Invite. Further, in the inspection / correction of defects, the shifter is a transparent film which is completely different from the Cr film which is a conventional light-shielding film.

The second method is useful for improving the characteristics of a single pattern to which the first method cannot be applied, but an auxiliary shifter in which the phase of transmitted light is inverted is necessary in the surroundings, and the pattern layout is very complicated. The restrictions also increase. There is also a problem that an unnecessary pattern is transferred depending on the size of the auxiliary pattern. Other alignment process,
Problems in mask production such as defect inspection and repair are the same as in the first method, which is a major obstacle in practical use.

The third method is effective for improving the characteristics of a single pattern having no periodicity such as a contact hole pattern, but in order to achieve this method, the phase of the diffracted light from the mask pattern is set in the reduction projection lens. An optical element that can control and modulate Furthermore, since the phase modulation area of this optical element depends on the mask pattern in which the effect is obtained, the optimum modulation optical element must be replaced in the reduction projection lens according to the application pattern. Therefore, securing the transmittance of the reduction projection lens including this optical element and eliminating various aberrations caused by heat generation of the optical element are very serious problems in practical use.

The fourth method is advantageous in that the characteristics can be improved simply by arranging a light shielding plate in the illumination system by using a conventional ordinary mask without forming a shifter or the like, but it has a pattern layout direction dependency, A good effect can be obtained only in a limited layout direction. Further, in a line width region thicker than the optimized predetermined line width, the depth of focus characteristic is significantly lower than the characteristic obtained in a normal illumination system. Furthermore, even with the same line width, there is so-called pattern sparse / dense dependence (proximity effect), and the exposure conditions under which good characteristics are obtained differ depending on the pattern pitch. Moreover, the biggest problem of this technique is that no improvement effect can be obtained for a single pattern or a random pattern having no periodicity.

12 and 13 are schematic views showing a simple principle of image formation by a conventional projection exposure apparatus. FIG. 12 is a diagram showing an image formed by a normal mask pattern.
FIG. 6 is a diagram showing a state in which an image cannot be formed due to a large diffraction angle of exposure light.

12 and 13, the conventional projection exposure apparatus includes a light source 1, a fly-eye lens 2, a condenser lens 4, a mask 5 and a projection lens 8.

A fly-eye lens 2 is provided below the light source 1, and a condenser lens 4 is provided below the fly-eye lens 2.
Is provided, a mask 5 is provided below the condenser lens 4, and a projection lens 8 is provided below the mask 5. The wafer 10 is installed below the projection lens 8.

Referring to FIG. 12, exposure light 6 from light source 1
1 passes through the fly-eye lens 2 and the condenser lens 4 and is diffracted by the pattern of the mask 5 to become diffracted light 71, which is taken into the pupil of the projection lens 8 and is the 0th-order light and the ± 1st-order light diffracted. The light flux forms an image of the mask pattern on the wafer 10.

Referring to FIG. 13, the finer the mask pattern, the larger its diffraction angle becomes. When the fineness exceeds a certain limit, ± 1st order diffracted light deviates from the effective pupil of the projection lens 8 for the pattern. The fine pattern cannot be imaged on the wafer 10.

FIG. 14 is a schematic view showing a simple image forming principle when the light shielding plate 13 is provided in the conventional projection exposure apparatus.

A fly-eye lens 2 is provided below the light source 1, a light-shield plate 13 is provided below the fly-eye lens 2, a condenser lens 4 is provided below the light-shield plate 13, and a mask is provided below the condenser lens 4. 51 is provided, and the projection lens 8 is provided below the mask 51. The wafer 10 is installed below the projection lens 8.

Referring to FIG. 14, a light shielding plate 13 which shields the central region of the illumination system is provided below the fly-eye lens 2.
The above problem is solved by the modified illumination technique using the diffracted light 75 of the oblique incident component 65 of the exposure light 61. This method uses half of the diffraction angle obtained with the mask pattern.
An image is obtained by the light beams 75a and 75b (diffracted light 75c deviates from the effective pupil of the projection lens 8), and improvement in resolution can be expected, and ideally, since the two light beams are formed, the respective light beams are formed. There is almost no optical path difference, excellent phase matching, and good depth of focus can be obtained.

However, not only in the normal illumination but also in the modified illumination technique using the grazing incidence illumination, the basis of image formation utilizes the interference effect of the exposure light diffracted by the mask pattern. Therefore, the interference effect can be obtained for the repetitive pattern having the periodicity, but the interference effect cannot be obtained at all for the single pattern having no periodicity, and the improvement effect cannot be expected even by the modified illumination.

FIG. 15 is a schematic view showing an example of the structure of the light shielding plate 35 used in the conventional modified illumination technique shown in FIG. 14 disclosed in Japanese Patent Laid-Open No. 4-101148. (A) And (c) is a top view of the light shielding plate 35. (B) and (d) are sectional views obtained by cutting the light shielding plate of (a) and (c) along a dotted line mm 'or a dotted line nn', respectively.

In FIG. 15, the light blocking plate 35 includes an opening 11 through which the exposure light passes and a light blocking portion 12 that blocks the exposure light.

Referring to FIG. 15, a light-shielding plate 35 having two openings 11 is attached to the projection exposure apparatus to form a point-shaped illumination system with oblique incidence.

However, this method has a layout direction dependency in a pattern (for example, a repetitive pattern) in which a characteristic improving effect can be obtained, and is problematic when applied to an actual circuit pattern in which various layouts are applied. Further, the depth of focus (DOF) is significantly reduced as compared with the normal illumination when the line width is equal to or larger than the optimized line width region. Furthermore, even with the same line width, there is so-called pattern density dependence (proximity effect),
The exposure conditions under which good characteristics are obtained differ depending on the pitch. Further, the biggest problem of this method is that no improvement effect is observed for single patterns or random patterns having no periodicity.

The problem with this single pattern or random pattern is that the effect of improving the imaging characteristics is based on the interference effect of the exposure light diffracted by the mask, and is improved in the repetitive pattern having periodicity. Although an effect can be obtained, an improvement effect cannot be obtained with a single pattern or a random pattern having no periodicity.

As described above, in the conventional technique, pattern periodicity, pattern layout, wide pattern size,
There is a problem that it is not possible to satisfactorily satisfy all of the practically required improvements such as pattern density (proximity effect).

The present invention has been made in order to solve the above problems, and it is possible to improve the resolution of a fine pattern and the depth of focus in a wide pattern area without improving the wavelength of the projection exposure apparatus and the numerical aperture NA of the lens. An object of the present invention is to provide a light source filter capable of achieving improvement without depending on the layout direction of a pattern and improving characteristics of a single pattern or a random pattern having no periodicity, and an exposure apparatus using the same.

[0036]

A light source filter according to a first aspect is a light source filter that transmits exposure light, and a first region that transmits the exposure light and a second region that sandwiches the first region. The first exposure light is transmitted through the first area without being reflected at the boundary between the first area and the second area, and the exposure light is reflected at the boundary and makes one round trip through the first area. Second exposure light that passes through the second exposure light and the second exposure light is transmitted through the first exposure light and the second exposure light.
A phase difference of one-half wavelength is generated.

A light source filter according to a second aspect is the first aspect.
In the light source filter of No. 2, the second region is a thin film having a transmittance of 30% or more for exposure light and a reflectance of 55% or less.

A light source filter according to a third aspect is the second aspect.
In the light source filter of, the thin film is made of Cr, Ta, Mo, A
l, Ti, MoSi, or Cr, Ta, Mo, A
It is made of an oxide or a nitride containing 1, Ti, and MoSi as the main components.

A light source filter according to a fourth aspect is the first aspect.
In any one of the light source filters 3 to 3, the first region is formed of SOG, sputtered SiO _2, optical glass, or an organic film.

A light source filter according to a fifth aspect is the first aspect.
In any one of the light source filters 4 to 4, a light shielding portion for shielding a part of the exposure light is provided.

A projection exposure apparatus according to a sixth aspect is a projection exposure apparatus for projecting exposure light, comprising a light source for emitting the exposure light and a light source filter, the light source filter transmitting the exposure light. And a second region sandwiching the first region
The first exposure light is transmitted through the first area without being reflected at the boundary between the first area and the second area, and the exposure light is reflected at the boundary and makes one round trip through the first area. And a second exposure light which is transmitted therethrough, and the second exposure light is provided with a mask having a projected shape that causes a phase difference of a half wavelength with the second exposure light.

A projection exposure apparatus according to a seventh aspect is the sixth aspect.
In the projection exposure apparatus, the second region of the light source filter has a transmittance of exposure light of 30% or more and a reflectance of 55%.
% Or less thin film.

A projection exposure apparatus according to an eighth aspect is the seventh aspect.
In the projection exposure apparatus, the thin film is made of Cr, Ta, Mo, A
l, Ti, MoSi, or Cr, Ta, Mo, A
It is made of an oxide or a nitride containing 1, Ti, and MoSi as the main components.

According to a ninth aspect of the projection exposure apparatus, the first region of the light source filter is formed of SOG, sputtered SiO _2, optical glass, or an organic film in the projection exposure apparatus according to any one of the sixth to eighth aspects. Has been done.

A projection exposure apparatus according to a tenth aspect is the projection exposure apparatus according to any one of the sixth to ninth aspects, further comprising a light-shielding portion provided adjacent to the light source filter for shielding a part of the exposure light. Is.

The projection exposure method according to claim 11 is a projection exposure method of projecting exposure light using a light source filter, wherein the step of creating exposure light and the phase of a part of the created exposure light A step of shifting a half wavelength by using a filter, and a step of superposing the exposure light shifted by a half wavelength and the original exposure light not shifted by a half wavelength on a predetermined projection object Is.

A projection exposure method according to a twelfth aspect is the projection exposure method according to the eleventh aspect, further comprising a step of blocking a part of the exposure light.

[0048]

In the light source filter according to the first aspect, the first
The exposure light passes through the first region and the second region without being reflected at the boundary between the first region and the second region, and the second exposure light is reflected at the boundary between the first region and the second region. Since the first exposure light and the second exposure light have a phase difference of a half wavelength with respect to the first exposure light, the image forming focal position of the first exposure light and the second exposure light is a half-wavelength optical path difference. It shifts.

In the light source filter according to claim 2,
In the light source filter according to claim 1, the second region is a thin film having a transmittance of exposure light of 30% or more and a reflectance of 55% or less.

In the light source filter according to claim 3,
The light source filter according to claim 2, wherein the thin film is Cr, Ta,
Mo, Al, Ti, MoSi, or Cr, Ta, M
It is made of oxide or nitride containing o, Al, Ti, and MoSi as main components.

In the light source filter according to claim 4,
The light source filter according to any one of claims 1 to 3,
The first region is formed by either SOG or sputtered SiO ₂ or optical glass or organic film.

Therefore, good multiple reflection at the boundary between the first area and the second area is realized. In the light source filter according to a fifth aspect, in the light source filter according to any one of the first to fourth aspects, since there is a light shielding portion that shields a part of the exposure light, only a necessary component of the exposure light is extracted and phase modulated. Can be interfered with.

In the projection exposure apparatus according to claim 6,
The exposure light is emitted from the light source, and the first light is emitted from the light source filter.
The exposure light passes through the first region without being reflected at the boundary between the first region and the second region, and the second exposure light is reflected at the boundary between the first region and the second region and makes one round trip through the first region. The second exposure light causes a phase difference of ½ wavelength with the first exposure light, and the shape of the mask is projected by the first and second exposure light transmitted through the light source filter. The focus positions of the light and the second exposure light are deviated by a half-wavelength optical path difference, the imaging amplitude at the set focus position is inverted, and the side lobes of the light intensity distributions of the images obtained by the interference cancel each other out. It has a sharp and good profile. Therefore, the contrast of the light intensity distribution is improved and the resolution can be significantly improved. Further, the contrast of the light intensity distribution in the focal direction is improved, and the focal depth can be greatly expanded. In addition to the repetitive pattern, even if it is a single pattern, it is possible to obtain the same effect as that when the repetitive pattern coherency is given by the first exposure light and the second exposure light having different half-wavelength phases. A great improvement can be achieved, and the proximity effect due to the density of the pattern is reduced.

In the projection exposure apparatus according to claim 7,
The projection exposure apparatus according to claim 6, wherein the second light source filter is provided.
The region is a thin film having a transmittance of 30% or more for exposure light and a reflectance of 55% or less.

In the projection exposure apparatus according to claim 8,
8. The projection exposure apparatus according to claim 7, wherein the thin film is Cr, Ta,
Mo, Al, Ti, MoSi, or Cr, Ta, M
It is made of oxide or nitride containing o, Al, Ti, and MoSi as main components.

In the projection exposure apparatus according to claim 9,
The projection exposure apparatus according to claim 6,
The first region of the light source filter is SOG or sputtered SiO
₂ or formed of either an optical glass or an organic film.

Therefore, good multiple reflection is realized at the boundary between the first area and the second area of the light source filter, and the resolution is greatly improved and the depth of focus is increased.

The projection exposure apparatus according to claim 10 is the projection exposure apparatus according to any one of claims 6 to 9, wherein there is a light-shielding portion provided adjacent to the light source filter for shielding a part of the exposure light. Take out only the necessary ingredients of
Phase modulation can be performed to cause interference, image formation due to an excess exposure light component is removed, and it is possible to further improve the resolution and increase the depth of focus.

In the projection exposure method according to the eleventh aspect, the exposure light is created, and the phase of a part of the created exposure light is shifted by ½ wavelength by the light source filter, and the exposure light is shifted by ½ wavelength. Since the original exposure light which is not shifted by ½ wavelength is superimposed and projected on a predetermined projection object, the focus positions of those exposure lights are shifted by the half-wavelength optical path difference, and the image formation amplitude at the set focus position. Are inverted, and the light intensity distribution of the image obtained by the interference has a steep and good profile in which side lobes are offset. Therefore, the contrast of the light intensity distribution is improved and the resolution can be significantly improved. Further, since the contrast of the light intensity distribution in the focal direction is improved, the depth of focus can be greatly expanded.

In the projection exposure method according to the twelfth aspect, in the projection exposure method according to the eleventh aspect, since a part of the exposure light is shielded, only a necessary component of the exposure light is taken out.
The phase can be modulated to cause interference, and imaging due to an excess exposure light component can be removed, so that it is possible to further improve the resolution and increase the depth of focus.

[0061]

Embodiments of a light source filter and a projection exposure apparatus using the same according to the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic view showing the structure of a projection exposure apparatus having a light source filter according to an embodiment of the present invention and the image formation of its exposure light.

Referring to FIG. 1, a projection exposure apparatus equipped with a light source filter according to an embodiment of the present invention includes a light source 1 for emitting exposure light 61, a fly-eye lens 2 serving as a secondary light source surface,
The multiple reflection interference light source filter 3 that transmits two diffracted lights having excellent coherence from the exposure light 61, the mask 5 provided with the resist pattern of the semiconductor circuit, and the two exposure lights (diffracted light ) 61, 62 includes a projection lens 8 for projecting and forming an image on the wafer 10 and its pupil plane 9.

The multiple reflection interference light source filter 3 further includes
It includes a filter substrate 31, a semi-transmissive film 32, and a transparent region 33.

In FIG. 1, only one light flux from one fly-eye lens is shown for simplicity. Further, in the partially enlarged view of the multiple reflection interference light source filter 3, a part of the exposure light 61 is actually reflected vertically, but it is schematically shown as being shifted.

A fly-eye lens 2 is provided below the light source 1, a multiple reflection interference light source filter 3 is provided below the fly eye lens 2, and a condenser lens 4 is provided below the multiple reflection interference light source filter 3. A mask 5 is provided below the lens 4, a projection lens 8 is provided below the mask 5, and the projection lens 8 has a pupil plane 9. A wafer 10 is installed below the pupil plane 9.

In the multiple reflection interference light source filter 3,
A semi-transmissive film 32 is formed on the lower surface of the filter substrate 31, a transparent region 33 is formed under the semi-transmissive film 32, and the semi-transmissive film 32 is again formed under the transparent region 33.

The exposure light 61 is emitted from the light source 1, and the exposure light with high coherency obtained from the fly-eye lens 2 which is the secondary light source surface of the projection exposure apparatus is multiplexed with the transmitted light 61 of the multiple reflection interference light source filter 3. The multiple reflection light 62 in the reflection interference light source filter 3 has a structure in which two wavefronts having an excellent amplitude and having a half-wavelength phase separation with an appropriate amplitude are excellent in coherence.

The multiple reflection light 62 obtained by the multiple reflection interference light source filter 3 is obtained by reflection at the upper and lower boundaries of the semi-transmissive film 32 and the transparent region 33, and is first reflected at the lower boundary to be 1 The / 4 wavelength phase shifts, and then the light is reflected by the upper boundary and further shifts the ¼ wavelength phase, and finally a half wavelength phase difference with the exposure light 61 occurs. The phase difference of ½ wavelength, that is, 180 ° does not have much effect even if it is about ± 5 °. In addition, it is sufficient that the phase difference is ½ wavelength in total, and the phase does not necessarily have to be shifted by ¼ wavelength at the upper and lower boundaries.

By illuminating the pattern on the mask 5 with the exposure lights 61 and 62 having the two wavefronts having different half-wavelength phases, even if the pattern is originally a single pattern where interference with an adjacent pattern cannot be expected, 5. Diffracted lights 71, 72 having two wavefronts with different half-wavelength phases obtained by diffraction in FIG.
A coherent image is obtained from each of them, and an effect equivalent to that when an adjacent pattern or an auxiliary pattern having effective coherence is additionally formed on the mask with respect to the main resolution single pattern is obtained.

FIGS. 2 and 3 show the principle of image formation when a single pattern is projected by a projection exposure apparatus having the multiple reflection interference light source filter 3 according to the embodiment of the present invention in comparison with image formation by conventional illumination. Is.

FIG. 2A shows the diffracted light 7 shown at 70 in FIG.
Is a diagram showing the imaging image in the z direction position by 1,72 as compared to that by the conventional illumination (diffracted light 71 only), (B) focus good resolution can be obtained depth (conventional: d _1, the Invention: d ₂ ).

In FIG. 2, since the diffracted light intensity of the diffracted light 71, 72 is not 1: 1 but the diffracted light 71 is stronger, the diffracted light intensity ratio of the diffracted light 71 and the diffracted light 72 is good. The depth of focus where various resolutions are obtained is in the region shown in FIG.

FIG. 3C is a diagram showing the amplitude distribution at the z-direction position of the image formation shown in FIG. 2, and FIG. 3D is a diagram showing the light intensity distribution.

Exposure light 61 emitted from the same light source 1 in FIG. 1 and having two wavefronts separated by a half wavelength time (phase),
62 is diffracted by the mask pattern 5 and diffracted light 71, 72
Is obtained. The wavefronts of the diffracted lights 71 and 72 are imaged on the surface of the wafer 10. Since the phases of the wavefronts of the diffracted lights 71 and 72 are different by a half wavelength (180 °), the conventional case is shown in FIG.
Although the amplitude distributions are as shown in (b) -1 and (d) -1 of FIG. 2, they are as shown in (a) -1 and (c) -1 of FIG.
The image forming amplitudes at the respective focus positions −z ₁ and z ₁ are inverted, and the light intensity distribution of the image obtained by the interference results in FIG. 3 (D).
As shown in (a) -2 and (c) -2 of FIG. Therefore, compared with the light intensity distribution of the image formed by the conventional illumination system shown in (b) -2 and (d) -2 of FIG. 3D, the contrast of the light intensity (the maximum value of the light intensity is Ratio of Imax and minimum value Imin; (Imax-Imin) / (Imax +
Imin)) is improved and the resolution can be significantly improved.

Also with respect to the depth of focus, the diffracted lights 71 and 72 having two wavefronts separated by a half-wavelength time (phase) as described above have different image-forming focus positions due to the optical path difference of a half-wavelength. That is, as shown in FIG.
As in (A) and (B), two image forming focal points −z ₁ and z
₁ and the superposition of the inverted imaging amplitudes as described in the resolution improvement effect can be applied, the contrast of the light intensity distribution in the focal direction of the wafer is improved, and the depth of focus is also compared to conventional illumination. Greatly expand.

The repetitive pattern has an interference effect between adjacent patterns, and has good characteristics in the conventional image-forming configuration as compared with the single pattern, but by applying the light source filter of the present invention, further characteristics can be obtained. Can be improved.

Further, in order to improve the resolution and the depth of focus (DOF), good improvement characteristics can be obtained at a low cost without improving the light source wavelength of the projection exposure apparatus and the numerical aperture NA of the projection lens. In consideration of wide application (general versatility), the method of arranging the light shielding plate of the fourth method described in the prior art in the illumination system of the projection exposure apparatus, so-called modified illumination technology, is the most suitable. It was decided to obtain a good improvement effect on a single pattern or a random pattern having no periodicity, which was difficult to improve by the conventional modified illumination technique for obtaining an arbitrary secondary light source shape.

FIG. 4 is a schematic diagram of direct-incident three-beam imaging by a projection exposure apparatus having the multiple reflection interference light source filter 3 of the embodiment of the present invention.

FIG. 5 is a schematic diagram of a configuration in which a part of the multiple reflection interference light source filter 3 is shielded in the projection exposure apparatus having the multiple reflection interference light source filter 3 according to the embodiment of the present invention and oblique incidence three-beam imaging. It is a figure.

Line and space when the effect of oblique incidence illumination is added to the multiple reflection interference light source filter 3 having the σ factor σ = 0.6 by the annular illumination that shields the region of σ = 0.5. 3 shows an imaged image for a repeating pattern of FIG. What is annular illumination?
It has a light-shielding shape like 5 (c).

The σ factor means the projection exposure apparatus illumination optical system.
Of the coherency factor of
Called. Aperture of the illumination optical system lens (4 (in Fig. 1))
Number NA_i11And the projection optical system lens (8 (in FIG. 1))
Numerical aperture NA_obBy σ = NA _i11/ NA_obDefined by
It The smaller the aperture diameter, the higher the coherency tends to be.
It

FIG. 6 shows a case where the projection exposure apparatus having the multiple reflection interference light source filter 3 of the present invention has an imaging amplitude distribution and light intensity distribution obtained from a repetitive pattern by a projection exposure apparatus having an imaging configuration using conventional illumination. FIG. 6A is a diagram for comparison with FIG. 4A is a diagram showing an amplitude distribution and a light intensity distribution of direct-incident three-beam imaging by a projection exposure apparatus in which the multiple reflection interference light source filter 3 of the present invention in FIG. 4 is installed, B) is Figure 5
FIG. 9C is a diagram showing an amplitude distribution and a light intensity distribution of oblique incident two-beam imaging by a projection exposure apparatus in which the multiple reflection interference light source filter 3 of the present invention is installed. FIG. It is a figure which shows intensity distribution.

In FIGS. 4 and 5, the projection exposure apparatus is
Light source 1, fly-eye lens 2, multiple reflection interference light source filter 3, condenser lens 4, mask 51, and projection lens 8
And its pupil plane 9.

A fly-eye lens 2 is provided below the light source 1, a multiple reflection interference light source filter 3 is provided below the fly eye lens 2, and a condenser lens 4 is provided below the multiple reflection interference light source filter 3. A mask 51 is provided below the lens 4, a projection lens 8 is provided below the mask 51, the projection lens 8 has a pupil plane 9, and a wafer 10 is provided below the pupil plane 9.

The configuration and structure of the multiple reflection interference light source filter is the same as in the case of FIG. Referring to FIG. 4, the light source 1
The exposure light 61 emitted from the laser beam passes through the fly-eye lens 2 and is multiply reflected by the multiple reflection interference light source filter 3. The directly incident exposure light 63 having a two-wavefront obtained by this multiple reflection passes through the condenser lens 4 and is diffracted by the mask 51 having a repeating pattern to become a diffracted light 73 having a two-wavefront, which is formed by the projection lens 8 and its pupil plane 9. Wafer 10
Imaged above. The multiple reflection of the directly incident exposure light 63 having two wavefronts by the multiple reflection interference light source filter 3 and the wavefront of the diffracted light 73 by the repeated pattern obtained from the exposure light 63 are omitted in the figure.

Referring to FIG. 5, the exposure light 61 emitted from the light source 1 passes through the fly-eye lens 2 and is multiple-reflected by the multiple reflection interference light source filter 3. The obliquely incident exposure light 64 having a wavefront is passed through the condenser lens 4, is diffracted by the mask 51 having a repeating pattern, and becomes the diffracted light 74 having two wavefronts, and is imaged on the wafer 10 by the projection lens 8 and its pupil plane 9. It

Multiple reflection of the obliquely incident exposure light 64 having two wavefronts by the multiple reflection interference light source filter 3 and the exposure light 6
The wavefront of the diffracted light 74 of the pattern obtained from No. 4 is omitted in the figure.

Regarding the obliquely incident exposure light 64, the exposure light 64
The image formation by x is a two-beam image formation by the −first-order diffracted light 74b among the 0th-order diffracted light 74c and the ± first-order diffracted lights 74d, 74b, and the image formation by the exposure light 64y is the 0th-order diffracted light 7b.
4b and ± 1st-order diffracted light 74a and 74c, which is a −2nd-order diffracted light 74c.

As described above, when the oblique incidence illumination is used,
In contrast to the three-beam imaging of normal illumination formed by the 0th-order diffracted light 73a and the ± 1st-order diffracted lights 73b shown in FIG. , An image can be obtained with a diffraction angle of half, the resolution can be improved, and the depth of focus can be expanded by the good phase matching of the two light fluxes.

By illuminating with the exposure light 64 having two wavefronts having different half-wavelength phases obtained from the oblique incidence component of the exposure light 61, the oblique incidence as shown in (b) -1 of FIG. 6B is obtained. By superimposing the inverted imaging amplitudes (amplitude distributions obtained from the respective exposure lights having the two phase-inverted wavefronts) obtained as described above, the peak Imax of the light intensity when exposed at the same exposure amount is (A) Although it is lower than that in the case where the central portion of the multiple reflection interference light source filter 3 shown in (a) -2 is not shielded in an annular shape or the like, a steep light intensity distribution as shown in (b) -2 is obtained. The contrast is improved.

That is, the contrast of the light intensity distribution is greatly improved as compared with the characteristics obtained by using the conventional normal image forming configuration shown in (c) -1 and -2 of (C), which is excellent. You get resolution and depth of focus.

Regarding the proximity effect in which the image-forming amplitude changes due to the density of the pattern (near and far of the line width), the interference effect is similar to the repeated pattern in the pattern area where the cause is dense. In such a pattern region, the same interference effect cannot be obtained as with a single pattern, and due to the difference in the interference effect, a large amplitude distribution is generated even with the same pattern size. However, by using the multiple reflection interference light source filter of the present invention, even in a single pattern, that is, in a sparse pattern region, an effect equivalent to that in which coherency is imparted by exposure light of two wavefronts having different half-wavelength phases is obtained, It is possible to balance with the dense pattern area and consequently reduce the proximity effect.

In order to achieve the effect of improving various characteristics with the multiple reflection interference light source filter of the present invention, the exposure having the film thickness of the transparent region for half-wavelength phase separation of the exposure light and the two wavefronts separated. The ratio of the filter transmittance of light is important.
The film thickness t ₁ of the transparent region of the light source filter for obtaining this phase modulation (optical path difference) and the transmittance of the exposure light passing through the light source filter are obtained from the equations (3) to (8) Is T _{1 of the} exposure light which passes through the filter without being reflected by the semi-transparent region and T _{2 of the} exposure light which is reflected by the semi-transparent region and travels back and forth through the transparent region through the filter.

[0095]

[Equation 2]

The filter transmittance of this exposure light is given by equation (7),
The ratio T ₂ / T ₁ of the transmittance T ₁ of the exposure light which is given by the formula (8) and is transmitted without being reflected in the semitransparent region and the transmittance T ₂ of the exposure light which makes one round trip in the transparent region is the semitransparent region. Reflectance R
Therefore, T ₂ / T ₁ = R ² . As described above, in order to improve the imaging characteristic obtained by the exposure light, a phase-inverted imaging amplitude capable of canceling the side lobe amplitude of the first-order diffracted light of the diffracted light generated by the mask is formed by the other exposure light. That is the basis.

For example, in FIG. 1, the peak of the side lobe amplitude is estimated to be about 30% with respect to the main imaging amplitude, and the reflectance R of the semitransparent region 32 contributing to the improvement is estimated.
Is preferably about ≦ 55% (T ₂ / T ₁ ≦ ˜30%).
Further, it is considered that the imaging light intensity formed by the exposure light 61 needs to be 10% or more of the normal illumination system in consideration of the exposure processing speed, and the transmissivity T of the semitransparent region 32 is about T ≧ 30%. (T ₁ ≧ 9%) is required.

Therefore, the material forming the semi-transparent region simultaneously satisfies these conditions of transmittance and reflectance with the same film thickness, and a uniform film thickness distribution is obtained over the entire opening of the secondary light source surface of the exposure apparatus. Suitable film thickness material.

The film thickness of the transparent region 33 is given by the equation (6). Since the phase of the exposure light 62 that makes one round trip in the transparent region 33 depends substantially on the film thickness of the transparent region 33, It is desirable to use a transparent material having a film thickness that can be easily formed on the substrate 31 having the transparent region 32 and can obtain a uniform film thickness distribution.

As described above, the multiple reflection interference light source filter of the present invention can achieve excellent improvement in pattern resolution and depth of focus as compared with the conventional projection exposure apparatus using the modified illumination technique. In particular, a significant improvement effect can be obtained for a single pattern. Therefore, the periodicity of the pattern,
It has little dependence on pattern layout, pattern size, pattern density, etc., and satisfies most practically required characteristics.

That is, since it has an improving effect on both a single pattern and a repetitive pattern, and is also effective against a wide range of pattern sizes and pattern density (proximity effect), the same projection exposure apparatus can be used. In addition, it can be applied to almost all patterns required in the actual manufacturing process such as VLSI without replacing the light source filter, and the process cost and initial capital investment can be significantly reduced, which is extremely useful in practice.

Although a little described in FIGS. 5 and 15, it is effective to shield the exposure light transmitting region 33 of the multiple reflection interference light source filter 3 of the present invention in various shapes in order to further improve the characteristics such as resolution and depth of focus. Is.

Therefore, the light shielding of the exposure light transmitting region 33 will be described in detail. FIG. 7 shows the exposure light transmitting region 33 of the multiple reflection interference light source filter 3 of the embodiment of the present invention.
It is a figure which shows various light-shielding shapes which light-shields with a light-shielding plate 35.

In FIG. 7, the multiple reflection interference light source filter 3 has the same structure and structure as in FIG.

Referring to FIG. 7, the light shielding plate 35 is patterned on the uppermost part of the multiple reflection interference light source filter 3 with a film thickness capable of shielding light by the material used for forming the semi-transmissive film 32 of the multiple reflection interference light source filter 3. There is.

The light-shielding shape of FIG. 7A is a structure for reducing the central transmission region, and is more effective for improving a single pattern. The light-shielding shapes of (b) and (c) are structures that shield the central transmission region and have obliquely incident light obtained from the periphery of the illumination system, and are more effective in improving the repetitive pattern.
(C) is an annular illumination similar to that shown in FIG.

FIG. 8 is a diagram showing various light shielding structures in which the exposure light transmitting region 33 of the multiple reflection interference light source filter 3 of the embodiment of the present invention is shielded by a light shielding plate or the like.

The configuration and structure of the multiple reflection interference light source filter 3 are the same as in the case of FIG. 7 and 8, at least the material used for forming the semi-transmissive film 32 is formed at the uppermost portion of the multiple reflection interference light source filter 3 as shown in FIG. 7 or as shown in FIG. It is desirable to form a pattern with a film thickness capable of blocking light on the lower portion (back surface) or at least on the lower layer and the upper and lower surfaces of the upper semi-transmissive film 32 as shown in FIG. 8B, but as shown in FIG. 8C. Organic film 3
Alternatively, a method using another material such as pattern coating formation of No. 6 or resin bonding of the light shielding film 36 may be used.

Further, it is not always necessary to integrally form the light shielding plate 35 and the multiple reflection interference light source filter 3, and the light shielding plate 35 and the multiple reflection interference light source filter 3 are superposed on the holder 37 shown in FIG. Can also be attached to
It is useful because each can be exchanged.

The multiple reflection interference light source filter 3 as described above
Although the method of improving the phase obtained by blocking the light of the above causes a slight decrease in the exposure intensity by partially blocking the illumination optical system, the effect of the multiple reflection interference light source filter 3 of the present invention has the effect of reducing the phase of the coherency. The improvement of the coherence due to the sophistication of the above, or the addition of the effect of the grazing incidence illumination as described above brings about the characteristic improvement according to the adaptive pattern.

Next, a specific application example will be described.
FIG. 9 is a perspective view showing the multiple reflection interference light source filter 3, the light shielding plate 34, and the holder 37 (only one side is shown) of the present invention.

In FIG. 9, the multiple reflection interference light source filter 3 includes a substrate 31, a semi-transmissive film 32, and a transparent region 33.

In the multiple reflection interference light source filter 3, a substrate 31 such as a quartz substrate which is transparent to exposure light is formed. The maximum aperture diameter is σ = about 0.7 when expressed by the σ factor of the projection exposure apparatus. Cr, Ta, Mo, Al, MoSi having a film thickness of about 15 nm or less with a transmittance of 30% or more and a reflectance of 55% or less on the substrate 31.
Etc. or a semi-transmissive film 32 made of an oxide or a nitride containing these materials as a main component is formed. On the semi-transmissive film 32, a transparent region 33 such as SOG (Spin On Glass), sputtered SiO ₂ (sputtered SiO ₂ ), optical glass, an organic film or the like in which the exposure light is multiply reflected is formed. Further, a semi-transmissive film 32 similar to the lower layer is formed on the transparent region 33. Here, the substrate 31 has a refractive index n of n = 1.51, and the semi-transmissive film 32 has a transmittance T of exposure light of T = about 40% and a reflectance R of R = R.
A Cr film obtained by about 20% is formed by sputtering with a film thickness of about 10 nm. Further, the transparent region 33 has a refractive index n = 1.
Forty-eight SOG films are used, and it is necessary to consider the phase modulation of the semi-transmissive film 32 as the film thickness of the SOG so that the total phase of the transmitted exposure light is modulated by 1/2 wavelength. , About 0.45 μm based on the above equation (6).
And

In this fabrication, the film thickness and uniformity of the SOG that controls the phase of the exposure light, and the film quality and film thickness of the ultrathin Cr film that controls the transmittance of the exposure light having two wavefronts are controlled. Is extremely important. Therefore, it is achieved by controlling the variation of process conditions such as SOG viscosity, coating device rotation speed, coating atmosphere temperature, firing temperature, etc., which have the most influence on the SOG film thickness and film thickness uniformity within ≦ 5% of the set value. To do. Further, in forming the ultra-thin Cr film, in order to avoid agglomeration in the initial stage during sputtering film formation, by controlling the film formation speed in a relatively low sputter gas pressure region, proper transmittance and reflectance can be obtained. Form a semi-permeable membrane.

The multiple reflection interference light source filter thus produced is aligned with the illumination optical system of the projection exposure apparatus so as to align the optical axis, and as shown in FIG. 9, the shading plate 34 for defining the σ value of the exposure apparatus.
And overlap. Then, the multiple reflection interference light source filter and the light shielding plate 34, which are stacked on the holder 37, are fixed and installed in the illumination optical system of the projection exposure apparatus.

In the projection exposure apparatus, NA = 0.5, σ = 0.
The KrF excimer laser projection exposure apparatus of No. 6 is used, and the multiple reflection interference light source filter 3 of the present invention is installed in the illumination optical system (on the downstream side of the light source 1). The overall configuration of the projection exposure apparatus is the same as that shown in FIG.

FIGS. 10 and 11 show the transfer of a single pattern when the projection exposure apparatus having the multiple reflection interference light source filter of the present invention is used and when the conventional ordinary projection exposure apparatus not using the light source filter is used. It is a figure which compared the resolution characteristic and depth of focus characteristic of a result.

The transmissivity T = 40% of the translucent region and the reflectivity R = of the translucent region of the installed multiple reflection interference light source filter.
20%.

Referring to FIG. 10, according to the conventional illumination, when the designed line width is about 0.3 μm or less, the resist pattern cannot be projected accurately. On the other hand, according to the illumination by the projection exposure apparatus of the present invention, it is understood that the resist pattern can be projected almost accurately up to a design line width of about 0.2 μm without including much error.

Referring to FIG. 11, according to the conventional illumination, the range in which defocus (defocusing) does not occur is about −0.25 μm or more and 0.25 μm in the z direction shown in FIG.
It was a narrow range as below. However, according to the illumination by the projection exposure apparatus of the present invention, about -0.75 μm or more, 1.0
Defocus does not occur in a wide range of μm or less.

Therefore, it is understood that by using the projection exposure apparatus having the multiple reflection interference light source filter of the present invention, extremely good characteristics can be obtained as compared with the illumination system of the conventional projection exposure apparatus.

Similarly to the above, a KrF excimer laser projection exposure apparatus with NA = 0.5 and σ = 0.6 was used to sputter-form SiO ₂ on the transparent region 33 of the multiple reflection interference light source filter 3 and also to form a semi-transparent region. T = 50%, R = 15 on transparent film 32
%, An Al film with a high yield is formed by sputtering.

This is applied to a repeating pattern of lines and spaces. The characteristic at that time is (a) -2 in FIG.
The contrast of the light intensity distribution similar to that shown in FIG. 6 is obtained, and the resolution is significantly higher than that of the light intensity distribution obtained from the conventional ordinary projection exposure apparatus as shown in (c) -2 of FIG. To be improved. Further, since the light intensity distribution contrast at the focus position is extremely good as compared with the value obtained from the conventional ordinary projection exposure apparatus, the depth of focus can be expected to be greatly expanded.

As described above, the multiple reflection interference light source filter of the present invention and the projection exposure apparatus using the same have the effect of improving both the single pattern and the repetitive pattern. Since it can satisfactorily deal with almost all the patterns required in the manufacturing process such as, it is effective in both the chip process centering on repeated patterns such as DRAM and the chip process such as logic with many random patterns. There is no need to replace the light source filter depending on the layer or target chip, and the process cost can be greatly reduced. Further, since it can be obtained by forming a thin film on the entire surface of the filter, it is extremely simple as compared with a manufacturing process of a phase shift mask having a fine processing process. Furthermore, by improving only the illumination optical system of the conventional projection exposure apparatus, characteristics improvement effects such as resolution and depth of focus can be obtained, which contributes to a significant reduction in the initial capital investment accompanying the extension of the adaptive chip generation of the projection exposure apparatus. .

Since the improvement effect does not depend on the wavelength of the exposure light in principle, the improvement effect is not limited to the KrF excimer laser (wavelength: 248 nm) described in the above embodiment, but g-line (wavelength: 436 nm), i-line (wavelength: 365n
m), and ArF excimer laser (wavelength: 193n
m), an F ₂ excimer laser (wavelength: 157 nm), and other multi-generation exposure light sources, and an extremely useful practical exposure apparatus can be provided.

[0126]

In the light source filter according to the first aspect of the present invention, the first exposure light passes through the first region and the second region without being reflected at the boundary between the first region and the second region, 2 exposure light is reflected at the boundary between the first region and the second region, travels back and forth through the first region once, and the first exposure light and the second exposure light cause a phase difference of ½ wavelength. The focus positions of the first exposure light and the second exposure light deviate by the half-wavelength optical path difference.

As a result, the image forming amplitude at the set focal position is inverted, and the light intensity distribution of the image formed by the interference has a steep and good profile in which the side lobes are canceled out. Therefore, the contrast of the light intensity distribution is improved and the resolution can be significantly improved. Further, since the contrast of the light intensity distribution in the focal direction is improved, the depth of focus can be greatly expanded. In addition to the repetitive pattern, even if it is a single pattern, it is possible to obtain the same effect as that when the repetitive pattern coherency is given by the first exposure light and the second exposure light having different half-wavelength phases. A great improvement can be achieved, and the proximity effect due to the density of the pattern is reduced.

In the light source filter according to claim 2,
The light source filter according to claim 1, wherein the second region is a thin film having a transmittance of exposure light of 30% or more and a reflectance of 55% or less.

In the light source filter according to claim 3,
The light source filter according to claim 2, wherein the thin film is Cr, Ta,
Mo, Al, Ti, MoSi, or Cr, Ta, M
It is made of oxide or nitride containing o, Al, Ti, and MoSi as main components.

A light source filter according to a fourth aspect is the first aspect.
In any of the light source filters 1 to 3, the first region is formed of SOG, sputtered SiO _2, optical glass, or an organic film.

Therefore, excellent multiple reflection at the boundary between the first area and the second area is realized. As a result, it is possible to improve the contrast of the light intensity distribution and increase the depth of focus.

In the light source filter according to claim 5,
The light source filter according to any one of claims 1 to 4,
Since there is a light-shielding portion that shields a part of the exposure light, it is possible to extract only the necessary component of the exposure light, phase-modulate it, and cause interference.

In the projection exposure apparatus using the light source filter according to the sixth aspect, the first exposure light passes through the first area and the second area without being reflected on the boundary between the first area and the second area. Then, the second exposure light is reflected at the boundary between the first region and the second region and travels back and forth through the first region once, and the first exposure light and the second exposure light have a phase difference of ½ wavelength. Since the mask shape is projected, the focus positions of the first exposure light and the second exposure light are deviated from each other by a half-wavelength optical path difference, the imaging amplitude at the focus position is inverted, and the image obtained by interference is formed. The light intensity distribution has a steep and favorable profile in which side lobes are offset from each other. Therefore, the contrast of the light intensity distribution is improved and the resolution can be significantly improved. Further, the contrast of the light intensity distribution in the focal direction is improved, and the depth of focus can be greatly expanded. Furthermore, even if the pattern is a single pattern as well as the repetitive pattern, the same effect as that when the coherency of the repetitive pattern is given by the first exposure light and the second exposure light having different half-wavelength phases can be obtained, so that the resolution A great improvement can be achieved, and the proximity effect due to the density of the pattern is reduced.

As a result, the dependence on the periodicity of the pattern, the pattern layout, the pattern size, the density of the pattern, etc. is small, and most of the practically required characteristics effective for both the single pattern and the repeating pattern are well satisfied. It is possible to provide such a projection exposure apparatus.

In the projection exposure apparatus according to claim 7,
The projection exposure apparatus according to claim 6, wherein the second light source filter is provided.
The region is a thin film having a transmittance of 30% or more for exposure light and a reflectance of 55% or less.

In the projection exposure apparatus according to claim 8,
8. The projection exposure apparatus according to claim 7, wherein the thin film is Cr, Ta,
Mo, Al, Ti, MoSi, or Cr, Ta, M
It is made of oxide or nitride containing o, Al, Ti, and MoSi as main components.

In the projection exposure apparatus according to claim 9,
The projection exposure apparatus according to claim 6,
The first region of the light source filter is SOG or sputtered SiO
₂ or formed of either an optical glass or an organic film.

Therefore, good multiple reflection at the boundary between the first and second regions of the light source filter is realized, and the resolution is greatly improved and the depth of focus is increased.

As a result, the dependence of pattern periodicity, pattern layout, pattern size, pattern density, etc. is small, and most of the practically required characteristics effective for both single patterns and repeated patterns are well satisfied. Such a projection exposure apparatus can be realized.

The projection exposure apparatus according to claim 10 is the projection exposure apparatus according to any one of claims 6 to 9, wherein there is a light-shielding portion provided adjacent to the light source filter for shielding a part of the exposure light. Take out only the necessary ingredients of
Phase modulation can be performed to cause interference, image formation due to an excess exposure light component is removed, and it is possible to further improve the resolution and increase the depth of focus.

As a result, the dependence of pattern periodicity, pattern layout, pattern size, pattern density, etc. is small, and most practically required characteristics effective for both single patterns and repeated patterns are better satisfied. It is possible to provide such a projection exposure apparatus.

In the projection exposure method according to the eleventh aspect, the exposure light is created, and the phase of a part of the created exposure light is shifted by ½ wavelength by the light source filter, and the exposure light is shifted by ½ wavelength. Since the original exposure light which is not shifted by ½ wavelength is superimposed and projected on a predetermined projection object, the focus positions of those exposure lights are shifted by the half-wavelength optical path difference, and the image formation amplitude at the set focus position. Are reversed, and the high-intensity distribution of the image obtained by the interference has a steep and favorable profile in which side lobes are canceled out. Therefore, the contrast of the light intensity distribution is improved and the resolution can be significantly improved. Further, the contrast of the light intensity distribution in the focal direction is improved, and the focal depth can be greatly expanded. Furthermore, even if the pattern is a single pattern as well as a repetitive pattern, the same effect can be obtained that the coherence of the repetitive pattern is imparted by two exposure lights having different half-wavelength phases, so that the resolution can be significantly improved. , The proximity effect due to the pattern density is reduced.

As a result, the dependence of the pattern periodicity, pattern layout, pattern size, pattern density, etc. is small, and most of the practically required characteristics effective for both single patterns and repetitive patterns are well satisfied. It is possible to realize such a projection exposure method.

In the projection exposure method according to the twelfth aspect, in the projection exposure method according to the eleventh aspect, since a part of the exposure light is shielded, only necessary components of the exposure light are taken out,
Phase modulation can be performed to cause interference, image formation due to an excess exposure light component is removed, and it is possible to further improve the resolution and increase the depth of focus.

As a result, the dependence on the periodicity of the pattern, the pattern layout, the pattern size, the density of the pattern, etc. is small, and most of the practically required characteristics effective for both the single pattern and the repeated pattern are better satisfied. It is possible to realize such a projection exposure method.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a configuration of a projection exposure apparatus having a light source filter according to an embodiment of the present invention and an image formation of the exposure light thereof.

FIG. 2 is a multiple reflection interference light source filter 3 according to an embodiment of the present invention.
FIG. 6 is a diagram comparing an image formation principle when a single pattern is projected by a projection exposure apparatus in which is installed with a conventional illumination.

FIG. 3 is a multiple reflection interference light source filter 3 according to an embodiment of the present invention.
FIG. 6 is a diagram comparing an image formation principle when a single pattern is projected by a projection exposure apparatus in which is installed with a conventional illumination.

FIG. 4 is a multiple reflection interference light source filter 3 according to an embodiment of the present invention.
FIG. 3 is a schematic diagram of a configuration and a direct-incidence three-beam imaging when a multiple reflection interference light source filter 3 is installed for a repetitive pattern in a projection exposure apparatus in which is installed.

FIG. 5 is a schematic diagram of a configuration and an oblique incidence three-beam imaging when a multiple exposure light source filter 3 of the present invention is provided with a multiple reflection interference light source filter 3 that partially shields a repetitive pattern from the projection exposure apparatus. It is a figure.

FIG. 6 shows a projection exposure apparatus using the multiple reflection interference light source filter 3 of the present invention, which uses the projection exposure apparatus using the normal incidence three-beam imaging configuration of FIG. 4 and the oblique incidence three-beam imaging configuration of FIG. It is the figure which compared the case where the projection exposure apparatus of the image formation structure by the conventional illumination is compared with the imaging amplitude distribution and light intensity distribution obtained from a repeating pattern with a projection exposure apparatus.

FIG. 7 is a multiple reflection interference light source filter 3 according to an embodiment of the present invention.
FIG. 6 is a diagram showing various light shielding shapes in which the exposure light transmitting region 33 of FIG.

FIG. 8 is a schematic diagram showing various light blocking structures for blocking the exposure light transmitting region 33 of the multiple reflection interference light source filter 3 by the light blocking plate 35 of the embodiment of the present invention.

FIG. 9 is a diagram showing a structure of a multiple reflection interference light source filter of the present invention, a light shielding plate 34, a multiple reflection interference light source filter 3, and a holder 37 (only one side is shown) of the light shielding plate 34.

FIG. 10 is a resolution of a transfer result for a single pattern when the projection exposure apparatus 1 provided with the multiple reflection interference light source filter 3 of the present invention is used and when the conventional ordinary projection exposure apparatus that does not use the light source filter is used. It is the figure which compared the characteristic.

FIG. 11 is a focus of a transfer result for a single pattern when the projection exposure apparatus 1 having the multiple reflection interference light source filter 3 of the present invention is used and when the conventional normal projection exposure apparatus not using the light source filter is used. It is a figure which compared the depth characteristic.

FIG. 12 is a schematic diagram showing a simple imaging principle by a conventional normal projection exposure apparatus. FIG. 12 is a diagram showing image formation by a normal mask pattern.

FIG. 13 is a schematic diagram showing a simple imaging principle by a conventional normal projection exposure apparatus. FIG. 12 is a diagram showing image formation by a normal mask pattern.

FIG. 14 is a schematic diagram showing a simple imaging principle used in the conventional modified illumination technique disclosed in Japanese Patent Laid-Open No. 4-101148.

FIG. 15 is a view showing a light shielding shape of a conventional light shielding plate 35.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 light source 3 multiple reflection interference light source filter 5,51 mask 31 substrate 32 semi-transparent area 33 transparent area 13, 34, 35 light shielding plate 36 light shielding plate different from light shielding plate 37 holder 61 exposure light flux 62 multiple reflection exposure light flux 64 multiple reflection Oblique incidence component of exposure light flux 71 Diffused light flux of mask light 5 pattern of exposure light flux 72 72 Light flux diffracted by mask 5 pattern of exposure light flux 73 73 Diffraction light flux of mask 51 pattern of exposure light flux 63 74 Diffraction by mask 51 pattern of exposure light flux 64 Light flux 75 Diffraction light flux of the exposure light flux 65 by the mask 51 pattern

Claims (12)

[Claims] 1. A light source filter that transmits exposure light, comprising: a first region that transmits the exposure light; and a second region that sandwiches the first region, wherein the exposure light is A second exposure light that passes through the first region without reflection at the boundary between the first region and the second region and a second exposure light that is reflected at the boundary and travels back and forth through the first region.
A light source filter including exposure light, wherein the second exposure light causes a phase difference of a half wavelength with the first exposure light. 2. The light source filter according to claim 1, wherein the second region is a thin film having a transmittance of 30% or more for the exposure light and a reflectance of 55% or less. 3. The thin film comprises Cr, Ta, Mo, Al,
Ti, MoSi, or Cr, Ta, Mo, Al, T
The light source filter according to claim 2, wherein the light source filter is made of an oxide or a nitride containing i, MoSi as a main component. 4. The first region is SOG, sputtered SiO 2.
_2. The light source filter according to any one of claims 1 to 3, which is formed of either optical glass or an organic film. 5. The light source filter according to claim 1, further comprising a light shielding portion that shields a part of the exposure light. 6. A projection exposure apparatus that projects exposure light, comprising: a light source that emits the exposure light; and a light source filter that transmits the exposure light, wherein the light source filter transmits the exposure light. A first region and a second region provided so as to sandwich the first region, wherein the exposure light passes through the first region without being reflected at a boundary between the first region and the second region. One exposure light and a second exposure light reflected on the boundary and transmitted through the first region in one round trip, and the second exposure light has a phase difference of a half wavelength with the first exposure light. And a mask having a shape to be projected, and projecting the projected shape of the mask using the first and second exposure lights that have passed through the light source filter. 7. The projection exposure apparatus according to claim 6, wherein the second region is a thin film having a transmittance of the exposure light of 30% or more and a reflectance of 55% or less. 8. The thin film comprises Cr, Ta, Mo, Al,
Ti, MoSi, or Cr, Ta, Mo, Al, T
The projection exposure apparatus according to claim 7, wherein the projection exposure apparatus is composed of an oxide or a nitride containing i, MoSi as a main component. 9. The first region is SOG or sputter S.
The projection exposure apparatus according to any one of claims 6 to 8, which is formed of iO _2, optical glass, or an organic film. 10. The projection exposure apparatus according to claim 6, further comprising a light shielding unit provided adjacent to the light source filter for shielding a part of the exposure light. 11. A projection exposure method for projecting exposure light using a light source filter, comprising the steps of: creating the exposure light; A projection exposure method comprising: a step of shifting two wavelengths; and a step of superimposing the exposure light having a half wavelength shift and the original exposure light having no half wavelength shift and projecting the same onto a predetermined projection target. 12. The projection exposure method according to claim 11, further comprising a step of blocking a part of the exposure light.