JP7198659B2 - Exposure device - Google Patents

Description

The present invention relates to an exposure apparatus applied to a lighting system.

For example, it is known to monitor the amount of light of an illumination device (optical device) used in an exposure apparatus to suppress variations in the amount of light. As one method for monitoring the amount of light, there is a method in which a light receiving portion of a light amount sensor is provided on the exposure stage and the amount of light is measured when the substrate is not exposed. With this method, the amount of light cannot be monitored regardless of whether it is during exposure or during non-exposure. In order to monitor the amount of light during exposure, it is necessary to use an illumination device that monitors the amount of light described in Patent Document 1 or Patent Document 2.

Patent Document 1 relates to an illumination optical device suitable for inspection of an image pickup device in the manufacturing process of the image pickup device, and has an integrator rod (hereinafter referred to as a rod lens). Inside the rod lens, the light incident from the light incident surface repeats internal reflection the number of times corresponding to the incident angle, and propagates toward the light exit surface. Then, on the light exit surface, lights with different numbers of reflections are overlapped, and the light quantity distribution is made uniform. In the configuration of Patent Document 1, a light branching surface is provided in the vicinity of the light exit surface of the rod lens so as to cross the rod lens at an angle of 45 degrees. The light branching surface is a plane coated with a half-mirror coat. The light is branched at the light branching surface in a direction different from the light exit surface, guided to the outside from the side surface of the rod lens, and guided to a photodetector for light amount monitoring.

Patent Literature 2 describes a light source device that is used to irradiate an object to be inspected with illumination light through an optical fiber when performing product inspection by imaging the surface of the object to be inspected and performing image processing. . A light intensity monitor for detecting the intensity of illumination light emitted is a light guide rod consisting of a rod lens that homogenizes the light incident from the light incident end face and emits it from the light exit end face in the optical path from the light source to the object to be illuminated. It has

The light emitting end face of the light guide rod and the light incident end face of the optical fiber are arranged with a gap therebetween and housed in a light shielding case. The optical sensor receives the light that is irradiated onto the light incident end surface of the optical fiber and reflected, and the amount of irradiation light is controlled by the light amount controller according to the amount of detected light.

JP 2005-195348 A JP 2007-163358 A

The illumination device described in Patent Document 1 is used as an illumination device for inspecting image sensors, and is not used as an exposure device. In addition, since the light is branched at the half mirror surface in order to monitor the amount of light, loss of the amount of light occurs. Furthermore, there is a problem that the cost is increased due to taper processing of rod lens end faces, half-mirror coating, and the like.

The illumination device described in Patent Document 2 is used for a light source device of an image processing inspection device, not for an exposure device. Also, the amount of light incident on the optical sensor is small, and measurement errors increase. Furthermore, since a certain wide space is required between the light guide rod and the optical fiber, there is a problem that much light leaks and the light cannot be used efficiently.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide an exposure apparatus capable of confirming the amount of exposure even during exposure of a substrate and reducing the loss of the amount of exposure light.

The present invention has a light source and an optical system for irradiating light from the light source,
The optical system
at least two rod lenses arranged in series;
a rod lens holder housing at least two rod lenses;
a light intake opening formed in at least one position where end faces of at least two rod lenses of the rod lens holder face each other;
a light-receiving part that receives the light emitted from the light-receiving opening;
with
The exposure device has a gap at a position where the end faces face each other, the gap expanding from the side where the end faces abut toward the light receiving opening .

According to at least one embodiment, the light emitted from between the rod lenses can be received by the light receiving section, and for example, constant illumination control can be performed. It is possible to monitor the amount of light even during exposure. Note that the effects described herein are not necessarily limited, and may be any effect described in the present invention or an effect different from them.

FIG. 1 is a diagram showing the configuration of an exposure apparatus according to one embodiment of the present invention. 2(a) and 2(b) are a cross-sectional view and a partial plan view of a first example of a light amount measuring section according to one embodiment. 3(a), 3(b), and 3(c) are schematic diagrams showing an example of arrangement of two rod lenses in one embodiment. FIG. 4 is a cross-sectional view of a third example of the light amount measuring section in one embodiment. FIG. 5 is a cross-sectional view of a fourth example of the light amount measuring section according to one embodiment.

Hereinafter, embodiments of the present invention and the like will be described with reference to the drawings. The embodiments and the like described below are preferred specific examples of the present invention, and the content of the present invention is not limited to these embodiments and the like.

FIG. 1 is a schematic configuration diagram of an exposure apparatus to which the present invention can be applied. The exposure apparatus includes a light source 1, an illumination optical system 2 for illuminating a reticle 3 with the light emitted from the light source 1 as illumination light with uniform illuminance, a reticle (photomask) 3 as a pattern original, and a reticle 3. A projection lens 4 as a projection optical system for projecting an image onto the substrate W and an exposure stage 5 on which the substrate W is placed are provided. Each element in FIG. 1 is shown in a cross-sectional view along the main optical axis, and hatching is omitted except for some parts.

A light source 1 is a UV lamp that emits broadband light including g-, h-, and i-lines. An elliptical mirror is also provided to condense light toward the entrance of the rod lens 11a. A power source 18 for driving the light source 1 is provided.

The illumination optical system 2 includes rod lenses 11a and 11b arranged in series, a light amount sensor 12 constituting a light amount measuring section, and a lens group 15 (not shown in FIG. 1 and represented by a single lens). The light intensity sensor 12 is composed of, for example, a photodiode.

Light amount data measured by the light amount sensor 12 is transmitted to the system controller 19 . A system controller 19 controls the overall operation of the exposure apparatus, and also controls the power source 18 for the light source 1 . The system controller 19 controls exposure based on the transmitted light amount data. For example, it is used for managing the integrated amount of light irradiated to the photoresist layer of the substrate, monitoring the output fluctuation of the light source, and controlling the constant illuminance.

Each of the rod lenses 11a and 11b is a transparent body having a polygonal cross section, and functions as an optical integrator (illumination light homogenizing means) by internal reflection. The illumination optical system 2 also includes a light shielding plate 13 and a light shielding plate moving mechanism 14 provided in the vicinity of the exit-side end face of the rod lens 11b.

In the step-and-repeat method in which the substrate W is moved to sequentially expose patterns, step movement of the substrate W and exposure are alternately repeated. There is a function of not exposing a predetermined range from the edge edge when the exposure position reaches the substrate edge (periphery). Such a substrate perimeter non-exposure function is called WEM (substrate edge masking). For WEM, a light shielding plate 13 is positioned at a non-exposure position by a light shielding plate moving mechanism 14 at a reticle conjugate position.

The reticle 3 is a transmissive photomask on which a predetermined pattern is drawn. The reticle 3 is supported by a reticle stage (not shown).

A projection lens 4 constitutes a projection optical system and projects the pattern of the reticle 3 onto an exposure surface (upper surface of the substrate). In FIG. 1, the lens group is omitted and only one projection lens 4 is shown, but a plurality of lenses are actually provided.

The substrate W is a semiconductor wafer (silicon substrate), a printed wiring board (organic substrate), a liquid crystal substrate (glass substrate), or the like, and a photoresist layer is formed on the surface of the substrate. The substrate W is held by suction on the exposure stage 5 .

The exposure stage 5 is moved in the X, Y and .theta. directions by the stage moving mechanism. The surface (two-dimensional plane) of the substrate W is defined by the X and Y directions, and the rotation direction is defined by θ.

2(a) and 2(b) are an enlarged sectional view and an enlarged plan view of the rod lens and the light amount measuring section. In FIG. 2B, the light amount sensor 12 is omitted. The rod lens holder 16 is a cylindrical case that fixes at least two rod lenses 11a and 11b in place. The rod lens holder 16 holds a plurality of rod lenses (the first rod lens 11a and the second rod lens 11b in FIG. 2) arranged in series. The term "in-line" as used herein means an arrangement in which the output end face of the rod lens 11a faces the incident end face of the rod lens 11b, and the light emitted from the output end face of the rod lens 11a is directly incident on the incident end face of the rod lens 11b. means

The rod lens holder 16 arranges the rod lenses 11a and 11b with a gap (air gap) G1 having a predetermined width therebetween. That is, the exit end face of the rod lens 11a on the incident side and the incident end face of the rod lens 11b on the exit side face each other in parallel with a gap G1 interposed therebetween.

In the rod lens holder 16, for example, a circular opening (light intake opening 17) is formed at a portion of the upper surface (or side surface) corresponding to the position where the rod lenses 11a and 11b are adjacent (that is, the position of the gap G1). The light amount sensor 12 is positioned so that its light receiving portion can receive light emitted from the light receiving opening 17 of the rod lens holder 16 .

The light amount sensor 12 is a sensor that measures the amount of light (illuminance) at a predetermined wavelength, and measures the amount of light with a wavelength component of, for example, 436 nm (g-line), 405 nm (h-line), or 365 nm (i-line). .

FIG. 3 is an enlarged view of the rod lenses 11a and 11b held by the rod lens holder 16. FIG. Note that the light amount sensor 12, the rod lens holder 16, and the like are omitted in FIG. A small space (air gap) G1 is provided between the adjacent rod lenses 11a and 11b. The light amount sensor 12 receives the light that reaches the inlet light 17 through the gap G1. That is, the light reflected multiple times between the output end face of the first rod lens 11a and the incident end face of the second rod lens 11b is received. If the gap G1 is too wide, the amount of light used for exposure will be lost, so it is preferable that the gap G1 is as small as possible. However, when the gap is 0, light does not propagate to the light quantity sensor 12 . Preferably, the width of the gap G1 is, for example, 0.05 mm to 1 mm.

The end surfaces of the adjacent rod lenses 11a and 11b are not necessarily vertical surfaces, and may be inclined as shown in FIG. 3(b). Alternatively, the end faces of adjacent rod lenses 11a and 11b may not be parallel as shown in FIG. 3(c). In that case, the exit end face of the rod lens 11a and the entrance end face of the rod lens 11b may partially contact each other.

FIG. 4 shows a second example of the light amount measuring section. For example, the incident end surfaces of the two optical fibers 21 a and 21 b are arranged with respect to the light intake opening 17 of the rod lens holder 16 . Optical fibers 21 a and 21 b are positioned by optical fiber holder 22 . Light passing through the optical fibers 21a and 21b is guided to light amount sensors 23a and 23b. The light intensity sensors 23a and 23b detect the light intensity of light with wavelengths different from each other. Alternatively, one optical fiber and one light amount sensor may be used to detect the light amount of a specific wavelength. Furthermore, a switchable optical bandpass filter may be provided between the light intake and the light amount sensor so that one light amount sensor can measure light amounts of a plurality of wavelengths.

FIG. 5 shows a third example of the light quantity measuring section. Rod lenses 11a and 11b are opposed to each other with a gap G1 in a rod lens holder 16 in the form of a square tubular case. A slit-shaped (long hole-shaped) opening 24 is formed at a position corresponding to the gap G1 on the upper surface of the rod lens holder 16 . Since the light emitted from the gap G1 is linear, the linear light is converged through the light inlet 24 and led to the light amount sensor, thereby increasing the amount of received light and improving the accuracy of light amount measurement. can be done.

A bundle fiber, for example, is used to extract light from the light intake port 24 and guide it to the light receiving section 26 of the light amount sensor 25 . A bundle fiber is a light guide in which a plurality of optical fibers with high transmittance are bundled to form a convergence guide portion 27, and terminal portions are provided at both ends of the convergence guide portion 27. FIG. The terminal portion 28 on the incident side is formed so as to have an incident end surface that substantially matches the shape of the light inlet 24 by unbundling the optical fibers. The output side of the convergence guide portion 27 is arranged so that the bundled optical fibers face or come into close contact with the light receiving portion 26 of the light quantity sensor 25 . Note that the convergence guide section 27 may be an optical system that converts linear light into spot light using a reflecting mirror, a prism, a lens, or the like.

An embodiment of the present technology has been specifically described above, but the present invention is not limited to the above-described embodiment, and various modifications are possible based on the technical idea of the present invention. . In addition, the configurations, methods, processes, shapes, materials, numerical values, etc., given in the above-described embodiments are merely examples, and if necessary, different configurations, methods, processes, shapes, materials, numerical values, etc. may be used. good too.

For example, three or more rod lenses may be arranged in series. In this case, a plurality of gaps may be formed and a light intake opening may be provided at a position corresponding to each gap. When forming a plurality of light intake openings, a plurality of light amount sensors having different sensitivity wavelengths may be installed for each light intake opening. Furthermore, the present invention can be applied not only to semiconductor exposure apparatuses, but also to apparatuses using rod lenses for making the illuminance distribution uniform. For example, the present invention can be used to monitor the amount of light in a contact exposure apparatus that brings a photomask into close contact with a substrate or a direct exposure apparatus that does not use a reticle. Furthermore, the light source is not limited to a UV lamp, and an LED light source, for example, may be used.

W... substrate, G1, G2, G3... gap, 1... light source, 2... illumination optical system,
3 Reticle 11a, 11b Rod lens 12 Light sensor
13... light shielding plate, 16... rod lens holder, 17... light intake port, 18... power supply

Claims (4)

Having a light source and an optical system for irradiating light from the light source,
The optical system is
at least two rod lenses arranged in series;
a rod lens holder that houses the at least two rod lenses;
a light intake opening formed in at least one position where the end surfaces of the at least two rod lenses of the rod lens holder face each other;
a light-receiving portion that receives light emitted from the light-receiving opening;
with
An exposure device having, at a position where the end faces face each other, a gap extending from a side where the end faces contact each other toward the light intake opening. 2. An exposure apparatus according to claim 1, wherein the widening side of said gap has a width of 1 mm or less. The light intake is a slit-shaped opening,
2. The exposure apparatus according to claim 1, further comprising a light guide into which linear light emitted from said opening is incident and which emits spot light to said light receiving section. 2. The exposure apparatus according to claim 1, wherein a movable light shielding plate is arranged close to the end of the rod lens holder on the side from which the illumination light is emitted .

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