KR20200017359A - Illumination optical system, exposure apparatus, and method of manufacturing article - Google Patents

Abstract

The present invention relates to a lighting optical system which is advantageous because of lighting with high uniformity, and is available in various sizes. The lighting optical system is used in an exposure apparatus which projects a pattern of an original plate onto a substrate, and is configured to light the original plate using the light from a light source. The lighting optical system comprises: a first reflective optical integrator; and a second reflective optical integrator, wherein the second reflective optical integrator has a hollow structure, and a portion of the first reflective optical integrator is disposed in the second reflective optical integrator.

Description

ILLUMINATION OPTICAL SYSTEM, EXPOSURE APPARATUS, AND METHOD OF MANUFACTURING ARTICLE}

The present invention relates to an illumination optical system, an exposure apparatus and an article manufacturing method.

An exposure apparatus can be used in a lithography process for manufacturing an article such as a semiconductor device. The exposure apparatus includes an illumination optical system for illuminating the original plate and a projection optical system for projecting the pattern of the illuminated original plate onto the substrate. The substrate has a photoresist on its surface, and the pattern of the original is projected onto the substrate, whereby the pattern is transferred to the photoresist. If the illumination of the original plate by the illumination optical system is nonuniform, there is a possibility that the transfer of the pattern to the photoresist is not good. Thus, in the illumination optical system, a reflective optical integrator for illuminating the original with uniform illuminance can be arranged.

In order to improve the uniformity of illuminance, a reflective optical integrator having a long overall length is advantageous, but it is difficult to manufacture a reflective optical integrator having a long overall length at low cost. Patent Literature 1 describes a configuration in which an optical rod (glass bar) is employed as a reflective optical integrator and a plurality of optical rods are arranged in series in the passage direction of illumination light. By this structure, the effect equivalent to the case where one optical integrator which has the length which totaled several optical integrators is used is acquired.

By the way, in recent years, in order to reduce the manufacturing cost of a semiconductor device, board | substrate size is enlarged. For example, in panel-level packaging technology (FOPLP), manufacturing of a package is carried out by stacking many silicon die on a large board | substrate, and reducing manufacturing cost per package is aimed at. On the other hand, substrates of normal wafer size are still used. Therefore, exposure apparatuses of various sizes exist according to the size of the substrate to be handled. Therefore, the total length of the illumination optical system, for example, the distance between the light source and the original, varies depending on the size of the substrate to be handled.

Japanese Patent Laid-Open No. 2005-32909

In order to easily realize the illumination optical system having various full lengths, a method of changing the number of optical rods arranged in series is conceivable. However, in this method, a gap is formed between adjacent optical integrators, and the gap can increase photoelectric loss, thereby reducing the lighting efficiency. In order to illuminate the illuminated area with higher uniformity, it is preferable to increase the incident angle of the illumination light with respect to the incidence plane of the optical integrator. Throw it away. In order to eliminate the gap, a technique called optical contact, which closely adheres end faces of adjacent optical integrators, may be employed. However, since the long optical integrator formed by this technique is weak against physical and thermal external forces, it is difficult to apply in terms of stability.

An object of the present invention is to provide an illumination optical system that is advantageous for illuminating an illuminated area with high illuminance and high uniformity and that can be coped with various sizes.

One aspect of the present invention relates to an illumination optical system used in an exposure apparatus for projecting a pattern of an original plate onto a substrate, wherein the illumination optical system is configured to illuminate the original plate using light from a light source, and the illumination The optical system includes a first reflective optical integrator and a second reflective optical integrator, the second reflective optical integrator has a hollow structure, and a part of the first reflective optical integrator is It is disposed in the second reflective optical integrator.

According to the present invention, there is provided an illumination optical system that is advantageous for illuminating an illuminated area with high illumination and high uniformity, and which can cope with various sizes.

BRIEF DESCRIPTION OF THE DRAWINGS The figure which shows the exposure apparatus or illumination optical system of 1st Embodiment of this invention.
2 is a view showing an exposure apparatus or an illumination optical system according to a first embodiment of the present invention.
3 is a view showing an exposure apparatus or an illumination optical system according to a second embodiment of the present invention.

EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated through the exemplary embodiment, referring an accompanying drawing.

1 and 2 schematically show the configuration of the exposure apparatus 100 or the illumination optical system 101 according to the first embodiment of the present invention. 1, 2, and later referred to in FIG. 3, directions are shown in the XYZ coordinate system. The exposure apparatus 100 can be used in a lithography process for manufacturing an article such as a semiconductor device. The exposure apparatus 100 includes an illumination optical system 101 for illuminating the original plate R, a projection optical system 103 for projecting the pattern of the original plate R onto the substrate W, and a disc drive mechanism 102 for holding and driving the original plate R. And a substrate drive mechanism 104 for holding and driving the substrate W. The exposure apparatus 100 may be configured by a step and repeat method, or may be configured by a step and scan method. In the exposure apparatus 100 or the illumination optical system 101, the optical axis AX can be folded by a mirror. The folding of the optical axis AX is advantageous for miniaturization of the exposure apparatus 100 or the illumination optical system 101. In one example, the optical axis AX may include a portion parallel to the Z axis (between the light source 1 and the mirror M1, between the mirror M2 and the substrate W) and a portion parallel to the Y axis (between the mirror M1 and the mirror M2). have.

In order to suppress that vibration damping performance falls by the heavy weight of the illumination optical system 101, the illumination optical system 101 is isolate | separated into the 1st illumination optical system 10 and the 2nd illumination optical system 20, and 1st illumination The optical system 10 and the second illumination optical system 20 may be supported by a support mechanism independent of each other. The first illumination optical system 10 may be supported through a first support mechanism, not shown, which is supported by the floor structure. The second illumination optical system 20 may be supported together with the disc drive mechanism 102 and the projection optical system 103 by a second support mechanism, not shown, by an unillustrated surface plate supported by the floor structure. .

The illumination optical system 101 adjusts the light (light beam) from the light source 1, and illuminates the original plate R arrange | positioned at the to-be-lighted area | region (object surface of the projection optical system 103). The light source 1 may be, for example, an ultra-high pressure mercury lamp for generating light such as i-rays (wavelength 365 nm). Alternatively, the light source 1 may be a KrF excimer laser for generating light at a wavelength of 248 nm, an ArF excimer laser for generating light at a wavelength of 193 nm, or an F ₂ laser for generating light at a wavelength of 157 nm, It is not limited to the examples listed here.

The original plate R has a pattern (for example, a circuit pattern) to be transferred to the substrate W. Disc R can be comprised, for example with quartz glass as a base material. The disc drive mechanism 102 may include, for example, a movable disc stage for holding the disc R, and a disc drive mechanism for driving the disc stage about the X axis and the Z axis. The projection optical system 103 projects the light passing through the original plate R onto the substrate W at a predetermined magnification (for example, 1/2). The substrate W is disposed on the image surface of the projection optical system 103. The substrate W has a photoresist (photosensitive material) on its surface. The substrate drive mechanism 104 includes a movable substrate stage for holding the substrate W, and the substrate stage includes an X axis, a Y axis, and a Z axis (and ωx, ωy, and ωz which are their respective rotation directions). And a substrate drive mechanism for driving with respect to the drive.

Hereinafter, the illumination optical system 101 will be described. The illumination optical system 101 may include, for example, a light source 1, an ellipsoidal mirror 2, a relay lens 3, a tilt mirror M1, an optical integrator 4, a tilt mirror M2, and a condenser lens 5. Can be. The first illumination optical system 10 may include, for example, a light source 1, an ellipsoid 2, a relay lens 3, a tilting mirror M1, and an optical integrator 4. The second illumination optical system 20 may include, for example, the bending mirror M2 and the condenser lens 5.

In the first illumination optical system 10, an ellipsoidal mirror 2, a relay lens 3, a tilting mirror M1, and an optical integrator 4 may be arranged in this order from the side of the light source 1. The light beam uniformed by the optical integrator 4 may be incident on the second illumination optical system 20. The second illumination optical system 20 may include a condenser lens 5 and a folding mirror M2. The ellipsoid mirror (condensing mirror) 2 has a first focus and a second focus, and condenses the light emitted from the light source 1 arranged at the first focus to the second focus. The relay lens 3 is an imaging optical system, the front focus of which is disposed at the second focus of the ellipsoidal mirror 2, and the rear focus of the relay lens 3 is disposed of the incident surface of the optical integrator 4. In other words, the relay lens 3 makes the second focal point of the ellipsoid 2 and the incident surface of the optical integrator 4 conjugate. In the vicinity of the pupil plane of the relay lens 3, a wavelength filter for blocking light in a specific wavelength region is arranged, and the exposure wavelength (the wavelength of the light exposing the substrate W) can be defined by this wavelength filter.

The optical integrator 4 is a reflective optical integrator having an incident surface, a reflecting surface, and an emitting surface ES, and reflects the light beams incident on the incident surface a plurality of times by the reflecting surface, and the emitting surface ES. A uniform light intensity distribution (illuminance distribution) is formed in the. The optical integrator 4 may have a rectangular shape in a cross section parallel to the plane (XZ plane) orthogonal to its axial direction LD (direction parallel to the Y axis (the longitudinal direction of the optical integrator 4). , May have another shape (for example, a polygon).

The second illumination optical system 20 illuminates the original plate R using light emitted from the exit surface ES of the optical integrator 4. The second illumination optical system 20 includes a condenser lens 5, and the front focus of the condenser lens 5 is disposed on the exit surface ES of the optical integrator 4, and is rearward of the condenser lens 5. The side focus is arrange | positioned in the position (lighting area | region) in which the original plate R is arrange | positioned. In other words, the condenser lens 5 has a relation in which the exit surface ES of the optical integrator 4 and the surface where the disc R are disposed are conjugated. As described above, the first illumination optical system 10 and the second illumination optical system 20 may be supported by independent support mechanisms. According to such a structure, the light intensity distribution (illuminance distribution) along the light intensity distribution (illuminance distribution) of the exit surface ES of the optical integrator 4 in which the uniform light intensity distribution (illuminance distribution) was formed is the condenser lens 5 It is formed in the arrangement surface of master R by this. Therefore, even if the 1st illumination optical system 10 vibrates due to the drive of the disc R by the disc drive mechanism 102, the drive of the board | substrate W by the board drive mechanism 104, etc., the arrangement surface of the disc R is uniform. Illuminated continuously in one illuminance. The shape of the area (lighted area) illuminated by the illumination optical system 101 can follow the shape of the exit surface ES of the optical integrator 4, but the shape of the lighted area is defined by a masking blade (not shown). You may be.

Hereinafter, the configuration of the optical integrator 4 will be described as an example. The optical integrator 4 may include a first reflective optical integrator 4a and a second reflective optical integrator 4b. In the example of FIG. 1, FIG. 2, the 1st reflective optical integrator 4a is arrange | positioned between the light source 1 and the 2nd reflective optical integrator 4b. The exit surface of the second reflective optical integrator 4b is the exit surface ES of the optical integrator 4, and is conjugated with the placement surface of the master R. As shown in FIG.

The first reflective optical integrator 4a may be an optical rod having a solid structure. The second reflective optical integrator 4b may be a hollow rod having a hollow structure. For example, the first reflective optical integrator 4a is an optical rod having a rectangular columnar shape, and the second optical integrator 4b is a cylindrical combination of four plate mirrors in which the inner surface is a reflective surface. It may be a hollow rod. The cross-sectional size (cross-sectional size parallel to the XZ plane) surrounded by the four plate mirrors of the second reflective optical integrator 4b is the cross-sectional size (cross-section parallel to the XZ plane) of the first reflective optical integrator 4a. Slightly larger than size). A part of the first reflective optical integrator 4a is disposed in the second reflective optical integrator 4b. In another aspect, a portion of the first reflective optical integrator 4a and a portion of the second reflective optical integrator 4b overlap each other with respect to the direction parallel to the optical axis AX (axial direction LD). According to such a structure, the reflective surfaces of the two reflective optical integrators 4a and 4b have no gap in the direction parallel to the optical axis AX. Therefore, the light emitted from the first reflective optical integrator 4a is incident on the second reflective optical integrator 4b without loss of propagation. When the second reflective optical integrator 4b has a solid structure, when foreign matter adheres to the exit surface (the exit surface ES of the optical integrator 4) of the second reflective optical integrator 4b, it is avoided. It can be projected onto the illuminated area. On the other hand, when the second reflective optical integrator 4b has a hollow structure, the problem caused by the adhesion of such foreign matter can be solved.

The length (length in axial direction LD) of the part arrange | positioned in 2nd reflective optical integrator 4b among the 1st reflective optical integrator 4a can be made variable. In other words, the second reflective optical integrator 4b can be relatively moved in the axial direction LD relative to the first reflective optical integrator 4a. Thereby, the length TL of the optical integrator 4 in the axial direction LD can be changed. 1 and 2, the lengths TL of the optical integrator 4 in the axial direction LD are different from each other.

In the illumination optical system 101 of the first embodiment, there is no photoelectric loss between the first reflective optical integrator 4a and the second reflective optical integrator 4b, and the illumination region has high illumination, It is advantageous because it illuminates with high uniformity. In addition, since the total length TL of the optical integrator 4 is variable, the illumination optical system 101 of 1st Embodiment can respond to the exposure apparatus 100 of various sizes. Therefore, the exposure apparatus 100 including the illumination optical system 101 is advantageous because it realizes a minimum footprint in accordance with the size of the substrate W to be handled. On the other hand, in the conventional structure without the degree of freedom for changing the total length of the optical integrator, there is a disadvantage that the size of the illumination optical system and the footprint of the exposure apparatus are thereby determined.

In the above example, the first reflective optical integrator 4a is disposed between the light source 1 and the second reflective optical integrator 4b. Instead, a second reflective optical integrator 4b may be disposed between the light source 1 and the first reflective optical integrator 4a. In addition, in the above example, the first reflective optical integrator 4a has a solid structure, but the first reflective optical integrator 4a may have a hollow structure.

Hereinafter, the exposure apparatus 100 and the illumination optical system 101 of 2nd Embodiment of this invention are demonstrated, referring FIG. Matters not mentioned as the second embodiment may follow the first embodiment. 2nd Embodiment is advantageous for the exposure apparatus which handles larger board | substrate W. FIG. In the second embodiment, the optical integrator 4 includes a first reflective optical integrator 4a, a second reflective optical integrator 4b, and a third reflective optical integrator 4c. It is advantageous to configure the optical integrator 4 with the three reflective optical integrators 4a, 4b, and 4c because the total length TL of the optical integrator 4 is lengthened.

Between the light source 1 and the second reflective optical integrator 4b, a first reflective optical integrator 4a is disposed, and between the light source 1 and the first reflective optical integrator 4a, The third reflective optical integrator 4c may be disposed. The first reflective optical integrator 4a may be an optical rod having a solid structure. The second reflective optical integrator 4b and the third reflective optical integrator 4c may be hollow rods having a hollow structure. For example, the first reflective optical integrator 4a is an optical rod having a square pillar shape. In addition, the second optical integrator 4b and the third optical integrator 4c may be hollow rods in which four plate mirrors are cylindrically combined such that their inner surfaces become reflective surfaces. A portion (one end side) of the first reflective optical integrator 4a may be disposed in the second reflective optical integrator 4b. Another portion (the other end side) of the first reflective optical integrator 4a may be disposed in the third reflective optical integrator 4c.

The relay lens 3 has a relation between the second focal point of the ellipsoidal mirror 2 and the incident surface of the optical integrator 4 as a conjugate. The condenser lens 5 has a relation in which the exit surface ES and the disk R of the optical integrator 4 are disposed are conjugated. By making the second reflective optical integrator 4b a hollow structure, it is possible to avoid the problem that foreign matter adheres to the exit surface ES and is projected onto the illuminated area.

The length (length in axial direction LD) of the part arrange | positioned in 2nd reflective optical integrator 4b among the 1st reflective optical integrator 4a can be made variable. Similarly, the length (length in axial direction LD) of the part arrange | positioned in 2nd reflective optical integrator 4b among 3rd reflective optical integrator 4c can be made variable. Thereby, the length TL of the optical integrator 4 in the axial direction LD can be changed. The first reflective optical integrator 4a may have a solid structure or a hollow structure.

Hereinafter, the manufacturing method of the article using the above-mentioned exposure apparatus is demonstrated as an example. The article may be, for example, a semiconductor IC element, a liquid crystal display element, a MEMS element, or the like, but may be another element. The article is subjected to a process of exposing a substrate (wafer, glass substrate, etc.) to which the photosensitive agent is applied, the process of developing the substrate (photosensitive agent), and the developed substrate in another known process using the above-described exposure apparatus. It is manufactured by. Other well-known processes include etching, resist stripping, dicing, bonding, packaging, and the like. According to this article manufacturing method, a higher quality article can be manufactured than before.

As mentioned above, although preferred embodiment of this invention was described, this invention is not limited to these embodiment, A various deformation | transformation and a change are possible within the range of the summary.

4: optical integrator
4a: first reflective optical integrator
4b: first reflective optical integrator
101: illumination optical system
100: exposure apparatus

Claims (9)

It is an illumination optical system used in the exposure apparatus which projects the pattern of a disc on a board | substrate,
The illumination optical system is configured to illuminate the disc using light from a light source,
The illumination optical system includes a first reflective optical integrator and a second reflective optical integrator,
The second reflective optical integrator has a hollow structure,
A portion of the first reflective optical integrator is disposed in the second reflective optical integrator. The method of claim 1,
An illumination optical system, characterized in that the length of the portion in the axial direction of the first reflective optical integrator is variable. The method of claim 1,
The first optical reflective integrator is disposed between the light source and the second optical reflective integrator. The method of claim 1,
The said 1st reflective optical integrator has a solid structure, The illumination optical system. The method of claim 1,
The said 1st reflective optical integrator has a hollow structure, The illumination optical system. The method of claim 1,
Further comprising a third reflective optical integrator,
The third reflective optical integrator has a hollow structure,
The other optical part of the said 1st reflective optical integrator is arrange | positioned in the said 3rd reflective optical integrator. The method of claim 1,
The first reflective optical integrator and the second reflective optical integrator constitute a first illumination optical system, and the illumination optical system further includes a second illumination optical system independently supported by the first illumination optical system. and,
An exit surface of the optical integrator composed of the first reflective optical integrator and the second reflective optical integrator is an exit surface of the first illumination optical system,
The said 2nd illumination optical system is comprised so that the exit surface of the said 1st illumination optical system and the to-be-illuminated area | region of the said disc may be conjugated. The illumination optical system of any one of Claims 1-7,
And a projection optical system for projecting a pattern of the original plate illuminated by the illumination optical system onto a substrate. Exposing the substrate using the exposure apparatus according to claim 8;
Developing the substrate;
An article manufacturing method, characterized by producing an article from the substrate.

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