JP4004601B2 - Illumination optical system of exposure equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention belongs to the field of photolithography technology, and more specifically, exposure that illuminates a mask used to transfer a circuit pattern of a semiconductor integrated device, a circuit pattern of a liquid crystal device, a color filter pattern, and the like onto a transfer target. The present invention relates to an illumination optical system of the apparatus.
[0002]
[Prior art]
In an illumination optical system of a conventional exposure apparatus, there has been proposed an optical system in which a plurality of primary light sources are arranged side by side, and a fly-eye lens is divided and illuminated by the plurality of primary light sources.
[0003]
[Problems to be solved by the invention]
However, in the illumination light source having this configuration, the illumination light emitted from the plurality of primary light sources partially overlaps each other before entering the fly-eye lens, and the illumination efficiency by the plurality of illumination light sources cannot be increased. There is.
[0004]
On the other hand, in recent exposure technologies, mask illumination with a large exposure area and exposure illumination with high illuminance are required, but this requirement cannot be sufficiently satisfied by the illumination optical system of the conventional exposure apparatus. .
[0005]
Therefore, an object of the present invention is to provide an illumination optical system of an exposure apparatus that can solve the conventional problems and can realize the demand for an exposure area expansion and high illumination exposure.
[0006]
[Means for Solving the Problems]
To solve the above problems, a first aspect of the invention, a plurality of illumination sources, multiple for the mask surface of the mask is disposed on the light beams is guided to the arranged direction from those of the plurality of illumination light sources of comprising a compound lens and the deflection optical group has an optical system for illuminating a mask surface that is disposed on the optical path of the light beam guided by the plurality of the compound lens and the deflection optical group, the plurality In the illumination optical system of the exposure apparatus for illuminating the mask surface arranged on the optical path of each light beam guided from the compound eye lens and the deflection optical system group, each optical system of the compound eye lens and the deflection optical system group is predetermined. The compound eye lens is arranged so as to be spaced apart from each other so that the opening angle is smaller than 1 ° when viewed from the mask surface. Each incident on A plurality of first compound eye lenses and a plurality of second compound eye lenses that respectively deflect light beams incident on the plurality of reflection mirrors toward the mask surface, the plurality of first compound eye lenses having a cubic shape. Each of the plurality of second compound eye lenses is arranged on one of the surfaces orthogonal to the four side surfaces of the fly array lens assembly, and is disposed on each of the four side surfaces of the fly array lens assembly. Is arranged in the fly array lens assembly.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0008]
In FIG. 1 , the illumination optical system according to the present invention basically includes a first illumination optical system 1 and a second illumination optical system 2.
[0009]
The first illumination optical system 1 includes an illumination light source 3, a condensing lens 4, a reflection mirror 6 'that is a deflection optical system (deflection optical member), a fly-eye lens 5 that is a first compound eye lens group, and a deflection optical system ( It has a reflecting mirror 6 which is a deflection optical member) and a collimator lens 7 as a focusing optical system (focusing optical member). Then, the light emitted from the illumination light source 3 is condensed by the condenser lens 4 and then enters the fly-eye lens 5 through the reflection mirror 6 ′, and is homogenized and emitted by the fly-eye lens 5. . The homogenized illumination light beam is reflected (deflected) toward the collimator lens 7 side by the reflection mirror 6 which is the first first deflection optical system after being homogenized, and then passes through the collimator lens 7. The mask (exposure surface) 8 that is the illumination surface is illuminated.
[0010]
The illumination light to the mask 8 is transmitted between the patterns 8a and 8a of the mask 8 shown in FIG. 7A and guided to the substrate B in FIG. 1, and the substrate B is exposed. The distance between the mask 8 and the substrate B is set to, for example, 100 μm as shown in FIG. 1, and the distance between the patterns 8a and 8a is set to 10 μm as shown in FIG. 7B. O is the optical axis (principal axis) of the collimator lens 7, and O1 is the optical axis of the illumination optical system 1. 7A and 7B, the patterns 8a and 8b are illustrated with different sizes for convenience of explanation.
[0011]
The second illumination optical system 2 includes an illumination light source 9, a condensing lens 10, a reflection mirror 12 'that is a deflection optical system (deflection optical member), a fly-eye lens 11 that is a second compound eye lens group, and deflection optics. It has a reflection mirror 12 as a system (deflection optical member) and a collimator lens 7 as a focusing optical system (focusing optical member). Then, the light emitted from the illumination light source 9 is collected by the condenser lens 10 and then enters the fly-eye lens 11 through the reflection mirror 12 ′, and is homogenized and emitted by the fly-eye lens 11. . The homogenized illumination light beam is reflected (deflected) toward the collimator lens 7 by the reflection mirror 12 which is the first after the homogenization and in relation to the reflection mirror 6 described above, which is the second deflection optical system. Then, a mask (exposure surface) 8 that is an illumination surface is illuminated through a collimator lens 7. The illumination light to the mask 8 is transmitted between the patterns 8a and 8a of the mask 8 shown in FIGS. 7A and 7B and guided to the substrate B in FIG. Become.
[0012]
O2 is the optical axis of the second illumination optical system 2. The fly-eye lenses 5 and 11 constitute one or a plurality of compound eye lens groups, and the reflection mirrors 6 and 12 constitute a plurality of deflection optical system groups.
[0013]
In such an optical system, the first illumination optical system 1 and the second illumination optical system 2 are arranged with the optical axis O1 and the optical axis O2 separated from each other by a predetermined distance L. The predetermined interval L is set by a numerical aperture with respect to the surface of the mask 8 (mask surface), an opening angle with respect to the mask 8 (mask surface) of the two illumination optical systems 1 and 2 and the like.
[0014]
Hereinafter, the numerical aperture and the opening angle will be described in detail.
[0015]
When the luminous flux of the illumination light through the compound eye lens group and the deflection optical system group in FIG. 1 is viewed from the mask surface, that is, the mask 8 side (the exit pupil side of the collimator lens 7), it can be expressed as shown in FIG. In FIG. 3, S1 'and S2' indicate the outer shapes on the pupil plane of the illumination light beams S1 and S2 transmitted through the fly-eye lenses 5 and 11 of FIG. 1, and S is the mask 8 (mask surface) of FIG. The circumscribed pupil plane is shown.
[0016]
Further, the light beams emitted from each of the multiple lenses 5a,... 5a, 11a,. It can be recognized as one light beam by the law. FIG. 2 shows the size and spacing of the fly-eye lenses 5 and 11 on the reflecting mirrors 6 and 12 when the fly-eye lenses 5 and 11 that produce this light beam are viewed from the incident side (incidence pupil side) of the collimator lens 7. It represents.
[0017]
In FIG. 2, the fly-eye lenses 5 and 11 are shown as squares having a dimension d per side, and the optical axis interval of the fly-eye lenses 5 and 11 is the predetermined interval L shown in FIG. It is shown. 2 shows a large number of lenses 5a,..., 5a, 11a,... 11a of the fly-eye lenses 5, 11, only the outer shape is shown for convenience of explanation.
[0018]
Under such a premise, if the distance between the optical axes of the fly-eye lenses 5 and 11, that is, the predetermined distance L is d as shown in FIG. 4, the outer shapes S 1 ′ and S 2 ′ on the pupil plane of the illumination light beams S 1 and S 2 are When projected onto the top surface, the contact is made as shown in FIG. When the outer shapes S1 'and S2' projected on the collimator lens 7 of the illumination light beams S1 and S2 are drawn as solid angles from the mask 8 side in relation to the optical axes O, O1 and O2, they can be expressed as shown in FIG. it can. In FIG. 6, the opening angle of the two illumination optical systems 1 and 2 with respect to the mask 8 (mask surface) is 0 °. The numerical aperture NA with respect to the surface of the mask 8 (mask surface) is set to 2 °.
[0019]
The intensity of the illumination light transmitted (diffracted) through the patterns 8a and 8a of the mask 8 in this state can be expressed as a light intensity curve 30 indicated by a broken line in FIG. The illumination light in FIG. 7B is ideal exposure illumination.
[0020]
However, in the actual arrangement of optical components, ideal illumination is difficult due to the restrictions on the arrangement of the reflection mirrors 6 and 12. Accordingly, it is desirable that the distance between the reflecting mirrors 6 and 12 be made closer to ideal exposure illumination. 8 and 9 show an example thereof. In FIG. 8, by setting the distance between the fly-eye lenses 5 and 11 to d, the predetermined distance L is set to 2d, and the opening angle of the light beam is set to 0.5 °. The intensity of the light beam transmitted (diffracted) between the patterns 8a and 8a of the mask 8 at this time is as shown by the light intensity curve 31 in FIG. According to the light intensity curve 31, when the ideal light intensity curve 30 is 100%, a light intensity of 85% of the ideal light intensity can be obtained.
[0021]
When the opening angle is set to 1 ° as shown in FIG. 10, the intensity of the light beam transmitted (diffracted) between the patterns 8a and 8a of the mask 8 is as shown by the light intensity curve 32 in FIG. According to the light intensity curve 32, when the ideal light intensity curve 30 is 100%, a light intensity of 70% of the ideal light intensity can be obtained.
[0022]
Furthermore, when the opening angle is 1.5 ° as shown in FIG. 11, the intensity of the light beam transmitted (diffracted) between the patterns 8a and 8a of the mask 8 is as shown by the light intensity curve 33 in FIG. Become. According to the light intensity curve 33, when the ideal light intensity curve 30 is 100%, a light intensity of 60% of the ideal light intensity can be obtained.
[0023]
Therefore, if the opening angle of the two illumination optical systems 1 and 2 is set to an opening angle smaller than 1 °, the light intensity can always be ensured to be 70% or more, the loss of the light amount is reduced, and the optimum illumination in a wide area Is possible.
[0025]
And this invention comprises the illumination optical system shown in FIG. 15 based on the basic composition demonstrated above. . FIG. 15 shows a fly-eye lens assembly 40 used for four illumination optical systems, and illustration of an illumination light source, a collimator mirror, and the like is omitted.
[0026]
As shown in FIG. 16, the fly-eye lens assembly 40 is formed in a cubic shape. Flat fly-eye lenses 42 to 45 as first compound eye lenses are arranged on the four side surfaces of the fly-eye lens assembly 40. The fly-eye lenses 42 to 45 have a square shape, and the size thereof is ½ of the area of the side surface. Here, illumination lights P1 to P4 from four light source parts (not shown) are incident on the fly-eye lenses 42 to 45 from directions orthogonal to each other, and illumination lights P1 from four light source parts (not shown). -P4 is prevented from interfering before entering the fly-eye lenses 42-45. On the upper surface of the fly-eye lens assembly 40, four square fly-eye lenses 46 to 49 as second compound eye lenses are arranged, and the fly-eye lenses 46 to 49 and the fly-eye lenses 42 to 45 are orthogonal to each other. is doing.
[0027]
The focal lengths of the fly-eye lenses 46 to 49 are made larger than the size t of each fly-eye lens, and a reflection mirror described below is provided between the fly-eye lenses 46 to 49 and the fly-eye lenses 42 to 45. It can be installed.
[0028]
Between the fly-eye lens 42 and the fly-eye lens 46, a reflection mirror 50 that deflects the illumination light incident on the fly-eye lens 42 toward the fly-eye lens 46 is provided, and the fly-eye lens 43 and the fly-eye lens 47 are provided. Is provided with a reflection mirror 51 for deflecting illumination light incident on the fly-eye lens 43 toward the fly-eye lens 47, and between the fly-eye lens 44 and the fly-eye lens 48, A reflection mirror 52 that deflects the incident illumination light toward the fly-eye lens 48 is provided. Between the fly-eye lens 45 and the fly-eye lens 49, the illumination light incident on the fly-eye lens 45 is directed to the fly-eye lens 49. A reflection mirror (not shown) that deflects toward the screen is provided. Each of the reflecting mirrors 50, 51, 52 (not shown) has a fly-eye lens 46, which is a second compound eye lens, using the illumination light passing through the fly-eye lenses 42-45, which are first compound eye lenses, as a secondary light source. The deflection optical system group which deflects toward -49 is comprised.
[0029]
The illumination light P5 that has passed through the second compound eye lens is guided to a known collimator mirror to be converted into a parallel light beam, illuminates the mask 25 existing in the reflection direction of the collimator mirror, and the pattern 8a of the mask 8 is covered. Projected onto a substrate B as a transfer body. Here, the illumination light is actually emitted from the entire surfaces of the fly-eye lenses 46 to 49, but for convenience of explanation, the illumination light is shown as four illumination lights P5 that coincide with the optical axes of the four illumination optical systems. Moreover, the distance between the optical axes of the four illumination lights P5 is set to a predetermined interval L, and the predetermined interval L is set so that the aforementioned opening angle is 1 ° or less.
[0031]
【The invention's effect】
As described above, the invention of claim 1 has a plurality of illumination light sources and a plurality of light guides arranged on the respective light fluxes from the plurality of illumination light sources and guided in the direction in which the mask surface of the mask is arranged . An optical system for illuminating a mask surface disposed on the optical path of each light beam guided by the plurality of compound-eye lenses and the deflection optical system group , In an illumination optical system of an exposure apparatus for illuminating a mask surface arranged on an optical path of each light beam guided from a compound eye lens and a deflection optical system group, each optical system of the compound eye lens and the deflection optical system group is spaced by a predetermined distance. The compound eye lens is arranged so that the opening angle is smaller than 1 ° when viewed from the mask surface , and the compound-eye lens transmits the light beams of the plurality of illumination light sources to the plurality of reflection mirrors of the deflection optical system group. Each incident A plurality of first compound eye lenses, and a plurality of second compound eye lenses that respectively deflect light beams incident on the plurality of reflection mirrors toward the mask surface, wherein the plurality of first compound eye lenses are cubic fly lenses. Each of the plurality of second compound eye lenses is arranged on one of the surfaces orthogonal to the four side surfaces of the fly array lens assembly; and Since it is arranged in the fly array lens assembly, the light intensity is always ensured to be 70% or more, the loss of light amount is reduced, and the wide area can be optimally illuminated. It is possible to realize an increase in exposure area and a requirement for high illumination exposure.
[Brief description of the drawings]
FIG. 1 is an explanatory view showing a basic configuration of an illumination optical system of an exposure apparatus of the present invention.
FIG. 2 is an explanatory diagram of a fly-eye lens of the illumination optical system shown in FIG.
3 is an explanatory diagram showing a relationship between an illumination range of the illumination optical system shown in FIG. 1 and a diameter of an illumination light beam on a reflection mirror. FIG.
4 is an explanatory diagram showing an ideal arrangement of a fly-eye lens and a reflecting mirror of the illumination optical system shown in FIG. 1. FIG.
5 is an explanatory diagram showing the relationship between the illumination range of the illumination optical system with the arrangement of FIG. 4 and the diameter of the illumination light beam on the reflection mirror. FIG.
6 is an explanatory diagram of a solid angle of the illumination optical system according to the arrangement of FIG.
7A is a partial sectional view for explaining the mask shown in FIG. 1, and FIG. 7B is a relationship between the mask pattern shown in FIG. 1A and the amount of light transmitted through the mask according to the arrangement shown in FIG. It is explanatory drawing which shows.
8 is an explanatory diagram showing an example of setting an interval by a reflection mirror of the fly-eye lens of the illumination optical system shown in FIG. 1. FIG.
9 is an explanatory diagram of a solid angle of the arrangement shown in FIG.
10 is an explanatory diagram showing another example of the solid angle by the arrangement setting of the reflecting mirror shown in FIG. 1. FIG.
FIG. 11 is an explanatory diagram showing still another example of the solid angle according to the arrangement setting of the reflection mirror shown in FIG. 1;
12 is an explanatory diagram showing a relationship of a light intensity curve of a mask pattern transmitted light amount according to the arrangement example shown in FIGS. 4 and 9. FIG.
13 is an explanatory diagram showing a relationship of a light intensity curve of a mask pattern transmitted light amount according to the arrangement example shown in FIGS. 4 and 10. FIG.
14 is an explanatory diagram showing a relationship of a light intensity curve of a mask pattern transmitted light amount according to the arrangement example shown in FIGS. 4 and 11. FIG.
[15] Ru explanatory view showing an illumination optical system of the exposure apparatus of the present invention.
[ Explanation of symbols]
3 ... Illumination light source 5 ... Fly eye lens (compound eye lens group)
6 ... Reflection mirror (deflection optical system group)
7 ... Collimator lens (Condensing optical system)
8 ... Mask (mask surface)
8a ... Pattern 9 ... Illumination light source 11 ... Fly eye lens (compound lens group)
12 ... Reflection mirror (deflection optical system group)
50, 51, 52 ... Reflection mirror (deflection optical system group)

Claims (1)

A plurality of illumination light sources, and a plurality of compound eye lenses and a deflecting optical system group for guiding light in the direction in which the mask surface of the mask is disposed on each light beam from the plurality of illumination light sources . an optical system for illuminating a mask surface that is disposed on the optical path of the light beam guided by the compound eye lens and deflection optical group, each of which is guided from the plurality of the compound lens and the deflection optical group In the illumination optical system of the exposure apparatus for illuminating the mask surface arranged on the optical path of the luminous flux, the optical systems of the compound eye lens and the deflection optical system group are arranged separated by a predetermined distance, and the interval is opened as viewed from the mask surface. While configuring the angle to be less than 1 ° ,
The compound eye lens includes a plurality of first compound lenses that allow light beams of the plurality of illumination light sources to be incident on a plurality of reflection mirrors of the deflection optical system group, and light beams incident on the plurality of reflection mirrors, respectively, on the mask surface. A plurality of second compound eye lenses that respectively deflect toward the
The plurality of first compound eye lenses are respectively disposed on four side surfaces of a cube-shaped fly array lens assembly, and the plurality of second compound eye lenses are arranged on one of the surfaces orthogonal to the four side surfaces of the fly array lens assembly. An illumination optical system of an exposure apparatus, wherein the illumination mirror system is arranged and the plurality of reflection mirrors are disposed in the fly array lens assembly.

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