JP2002303988A - Exposure device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an exposure device capable of exposing a large-area surface by using ultraviolet rays having uniform illuminance. SOLUTION: This exposure device is equipped with an exciting light source constituted by arraying a plurality of nitride semiconductor light emitting diodes 1 whose each light emission peak wavelength is 200 nm to 450 nm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exposure apparatus using an ultraviolet light source.

[0002]

2. Description of the Related Art Conventionally, in an exposure apparatus using an ultraviolet light source, a discharge tube using a metal gas or a rare gas, or a gas or solid laser has been used as an excitation light source.

[0003]

In the above-mentioned conventional ultraviolet light source, it is difficult to make the surface light source with good uniformity, and a large-area optical lens has been used to make the illuminance uniform. However, the exposure area is small because it is difficult to produce a large lens with little aberration, and it is difficult to design heat to increase the output due to the low efficiency of the ultraviolet light source. Therefore, large-area exposure has been performed by repeated (step and repeat) exposure. This method has the advantage that a large substrate can be exposed while maintaining high optical resolution, but the number of exposures is large. Therefore, there is a problem that the alignment is required every time, and the throughput is reduced. During that time, the energy consumption was large because the light source was kept operating.

In a light source utilizing these discharges,
Requires high voltage and power as its power source, large size, heavy weight, long start-up time to stabilization, frequent calibration of light output due to long-term deterioration due to discharge However, there is a problem that a large space is required for condensing light.

[0005] Further, there is a problem that the sample is heated because a large amount of light having a long wavelength having heat energy is contained in addition to the required ultraviolet light. For this reason, there is a problem that not only the light source but also the exposure apparatus itself becomes extremely large in order to dispose the sample / mask and the like separately from the light source. When performing such a thermal design, a hot-wire filter or a cooling fan is often used,
For this reason, even if the optical condensing system can be designed to be compact, the size of the entire apparatus becomes large, which is necessary for heat control of the light source and the optical system, and vibration generated by the operation of the cooling fan is minute. This is an obstacle to making patterns. In particular, when using a hot-wire filter, it was difficult to avoid the problem that the ultraviolet light for excitation required was attenuated and that it was difficult to prevent heat from flowing from the fixed part of the hot-wire filter. .

In recent years, including large displays,
As the area of optical and electronic devices has increased, and their usefulness has been clarified, further enlargement of the area is expected.
However, since exposure is performed on, for example, a meter-sized surface, it has been difficult to obtain ultraviolet rays with uniform illuminance by the conventional technique.

An object of the present invention is to provide an exposure apparatus capable of exposing a large area surface using ultraviolet rays having uniform illuminance.

[0008]

In order to solve the above-mentioned problems, an exposure apparatus of the present invention has an emission peak wavelength of 200 nm.
An excitation light source comprising a plurality of nitride semiconductor light-emitting diodes of up to 450 nm is arranged.

Further, the exposure apparatus of the present invention is characterized by comprising an excitation light source having a plurality of the above-described nitride semiconductor light emitting diodes having an emission peak wavelength of 350 nm to 370 nm.

Further, the exposure apparatus of the present invention is provided with an excitation light source comprising a plurality of the above-described nitride semiconductor light emitting diodes having an active layer (light emitting layer) made of InGaN having an emission peak wavelength of 420 nm to 440 nm. It is characterized by the following.

According to the present invention, with the above configuration, it is possible to realize an exposure apparatus which can perform exposure of a large-area surface using ultraviolet rays having uniform illuminance.

[0012]

Embodiments of the present invention will be described below in detail with reference to the drawings. In the drawings described below, those having the same functions are denoted by the same reference numerals, and the repeated description thereof will be omitted.

First Embodiment FIG. 1 is a view showing a schematic configuration of an exposure apparatus according to a first embodiment of the present invention.

Reference numeral 1 denotes an ultraviolet light emitting diode having an emission peak wavelength of about 360 nm. The emission wavelength of such a light emitting diode is described in Japanese Patent Application No. 2000-2 by the present applicant and the present inventors.
This can be realized by a nitride semiconductor light emitting diode having a structure as described in US Pat. For example, an n-type AlGaN layer, an AlGaN multiple quantum well light emitting layer, a p-type AlGaN layer, and a p-type GaN contact layer are stacked on an n-type SiC substrate, a negative electrode is provided on the n-type SiC substrate, and a p-type GaN contact layer is provided. This is a light emitting diode element having a positive electrode provided thereon.
The light emitting section is composed of an AlGaN multiple quantum well light emitting layer, for example, a quantum well layer having an Al composition of less than 5% and an In composition of less than 1%.
A barrier layer having an Al composition of 15% and an In composition of less than 1%,
The peak emission wavelength is 360 nm. As described above, by reducing the Al composition of the quantum well layer or increasing the thickness of the quantum well layer, in principle, about 200 nm is obtained.
Emission wavelengths of ~ 450 nm are feasible. Further, by adding boron (B) to the light emitting part, the lower limit of the oscillation wavelength can be reduced to about 220 nm to 200 nm. Light having such an emission spectrum can be applied to a resist for exposure to i-line (wavelength 365 nm) of a mercury lamp conventionally used for photolithography, and a facility such as a resist coating machine other than the exposure apparatus is continuously used. There is an advantage that you can. Of course, if an ultraviolet light emitting diode having a shorter wavelength is used and a resist material having sensitivity to the wavelength is used, a pattern with higher resolution can be formed.

Reference numeral 2 denotes a light-emitting diode array in which a plurality of light-emitting diodes 1 are arranged, 3 denotes a light-emitting diode array mount, 4 denotes a line indicating an opening angle of emitted light of the light-emitting diode 1, 5 denotes a mask, 6 denotes a resist film, 7 is a substrate and 8 is a substrate stage.

Assuming that the opening angle of the emitted light of the light emitting diode 1 is θ, the design rule of the mask 5 is L _D , and the gap between the mask 5 and the substrate 7 with the resist film 6 is G, L _D ≒ G sin θ / 10 (1) The relationship holds. Therefore, by setting the θ opening angle light emitted from the light emitting diode and the gap G according to the design rule L _D, it is possible to obtain a desired spatial resolution.

The number n of the light emitting diodes 1 that irradiate the same point on the mask 5 is determined by the following equation.
Is given by n ≒ (Ltan θ / D) ² (2). Therefore, by increasing the mounting density of the light emitting diode array 1 or increasing the distance L between the light emitting diode array 2 and the mask 5, Uniform illuminance can be easily realized. Thereby, it is easy to avoid the variation in the element characteristics of the light emitting diode 1. The number of light emitting diodes 1 is desirably at least 25 or more.

Second Embodiment FIG. 2 is a view showing a schematic configuration of an exposure apparatus according to a second embodiment of the present invention.

Reference numeral 9 denotes an aperture array, and 10 denotes a hole of the aperture array 9.

In the present embodiment, the aperture array 9
Is provided in the vicinity of the light emitting diode array 2,
By reducing the opening angle θ of the emitted light from the light emitting diode 1, the resolution can be increased and a smaller design rule can be realized.

As shown in FIG. 2, the aperture array 9
When the aperture array 9 is arranged such that each hole 10 is located immediately before each light emitting diode 1, only light having good straightness in the vertical direction indicated by an arrow A in the figure is emitted from the hole 1.
Selected by 0. This means that the output light opening angle θ has substantially decreased. Therefore, a desired resolution can be obtained according to the above equation (1). In this case, if the number of light-emitting diodes 1 irradiating the same place is reduced and reduction in uniformity of illuminance becomes a problem, the distance between the light-emitting diode array 2 and the mask 5 is calculated according to the above equation (2). L may be increased.

In the first and second embodiments, by providing the light-emitting diode array mount 3 with a water-cooled tube, it becomes possible to perform exposure with excellent reproducibility of exposure intensity.

As for the overlay accuracy of the mask 5 and the substrate 7, a mechanism for supplying a constant temperature of the atmospheric gas on the upper surface of the mask 5 and a temperature adjusting mechanism for the substrate stage 8 on which the substrate 7 is mounted are provided. By providing, it is possible to suppress a small dimensional deviation.

FIG. 3 is a diagram for explaining the relationship between the optical characteristics (light absorption intensity) of the resist material and the wavelength of the light source.

FIG. 3 shows the outline of the ultraviolet absorption spectrum of the skeleton of the photosensitive agent (containing benzophenone) used for g-line (wavelength 435 nm) exposure of a mercury lamp and the mercury lamp. i-line (wavelength 365n
m) Photosensitizers used for exposure (benzophenone (b
FIG. 3 is a comparison of the outlines of the ultraviolet absorption spectrum of the skeleton portion of (enzophenone) -free).

For example, when a g-line resist is exposed at a wavelength of 350 nm to 370 nm, which is i-line or close to i-line resist, the absorption of the skeleton of the photosensitive agent contained in the g-line resist is large. UV light is difficult to reach. Therefore, when the condition for exposing the upper layer is used, the lower layer becomes insufficiently exposed to light, and a groove cannot be formed to the lower layer when developed. Further, if the conditions for exposing the lower layer are used, there is a disadvantage that the upper layer is excessively exposed and no pattern remains when developed. For this reason, if a pattern is formed intentionally by overexposure, the resolution will be reduced, making it impossible to form a fine pattern.

On the contrary, even if the resist for i-line is exposed using g-line, the energy of the photon of g-line (2.85 e)
V) is insufficient for the energy (3.4 eV) required to expose the i-line resist, so that the i-line resist cannot be exposed. Therefore, over-exposure is also required, which lowers the resolution and increases the time spent for exposure. Therefore, in order to increase the resolution, it is necessary to expose the resist with light having an appropriate wavelength. In other words, if a light source close to the wavelength of a mercury lamp is used (for example, approximately 435 nm for g-line and approximately 365 nm for i-line), it is possible to continue using a conventionally used photoresist. Become.

In an actual lithography process, it is necessary to experimentally determine a number of conditions such as a resist coating film thickness, a development time, and dry etching conditions. Will occur. Therefore, the wavelength corresponding to the g-line or i-line of the mercury lamp which is the exposure wavelength of the conventional resist, that is,
The use of light emitting diodes of 350 nm to 370 nm and 420 nm to 440 nm has an advantage that all the facilities and operating conditions other than the exposure apparatus using a mercury lamp can be inherited.

The emission peak wavelength is from 420 nm to 440 nm.
When a light source in which light emitting diodes having an InGaN active layer are arranged is applied, the resolution can be reduced by about 20% as compared with a light emitting diode having a light emission peak wavelength of 370 nm, but a large area can be exposed.

When a new process is designed by selecting a photosensitive agent or the like to form a finer pattern,
In the present invention, since it is possible to improve the resolution by using ultraviolet light shorter than i-line (365 nm), 370n
There is an advantage that the exposure apparatus is configured using an ultraviolet light emitting diode having a wavelength shorter than m.

In recent years, treatment with atmospheric pressure non-equilibrium plasma has been studied, and a large-area device process has been made possible. Therefore, it is combined with a large-area resist pattern produced by a large-area exposure apparatus as in the present invention. Thus, a large-area device can be manufactured.

As described above, the exposure apparatuses of the first and second embodiments are characterized in that they are provided with an excitation light source in which a plurality of nitride semiconductor light emitting diodes 1 each having an emission peak wavelength of 200 nm to 450 nm are arranged. I do.

Further, the emission peak wavelength is from 350 nm to 37 nm.
An excitation light source comprising a plurality of 0 nm nitride semiconductor light emitting diodes 1 is arranged.

Further, the emission peak wavelength is from 420 nm to 4 nm.
An excitation light source comprising a plurality of nitride semiconductor light emitting diodes 1 each having an active layer of 40 nm InGaN is provided. For example, such a light emitting diode element is formed by forming an n-type AlC on an n-type SiC substrate.
A GaN wetting layer, an n-type GaN buffer layer, an InGaN multiple quantum well light emitting layer, a p-type AlGaN blocking layer, and a p-type GaN contact layer are stacked, a negative electrode is provided on an n-type SiC substrate, and a positive electrode is formed on the p-type GaN contact layer. This is a structure provided with electrodes. The reason for stacking the n-type AlGaN wet layer on the SiC substrate is that if the GaN layer is to be stacked directly on the surface of the SiC substrate, the wettability is poor and it is difficult to stack the film uniformly. An AlGaN wetting layer containing Al is laminated.

With such a configuration, it is possible to realize an exposure apparatus capable of performing exposure of a large-area surface using ultraviolet rays with uniform illuminance, and it is possible to eliminate the need for a mercury light source. That is, as described in the first and second embodiments,
In an exposure apparatus using the ultraviolet light emitting diode array 2, by increasing the number of light emitting diodes 1, it is possible in principle to collectively expose an arbitrarily large area. Further, the mounting density of the light emitting diodes 1 can be increased, or the aperture array 9 can be increased as in the second embodiment shown in FIG.
, It is possible to increase the resolution. It is not suitable for devices whose degree of integration determines the function, such as a memory LSI or a CPU-LSI. The design can increase the design rule and compensate for the decrease in overlay accuracy, thereby improving the throughput. Further, in addition to the display, there is an advantage that a device having an unprecedented large area can be realized by eliminating the dimensional restrictions of the conventional exposure apparatus.

Although the present invention has been specifically described based on the embodiments, the present invention is not limited to the above-described embodiments, and it is needless to say that various modifications can be made without departing from the gist of the present invention. It is.

[0037]

As described above, according to the present invention,
An exposure apparatus capable of performing exposure of a large-area surface using ultraviolet light with uniform illuminance can be realized.

[Brief description of the drawings]

FIG. 1 is a diagram showing a schematic configuration of an exposure apparatus according to a first embodiment of the present invention.

FIG. 2 is a diagram illustrating a schematic configuration of an exposure apparatus according to a second embodiment of the present invention.

FIG. 3 is a diagram for explaining the relationship between the optical characteristics of a resist material and the wavelength of a light source.

[Explanation of symbols]

1 ... light emitting diode, 2 ... light emitting diode array, 3 ...
A light emitting diode array mount, 4 ... a line indicating an opening angle of emitted light of the light emitting diode, 5 ... a mask, 6 ... a resist film,
7: substrate, 8: substrate stage, 9: aperture array, 10: hole of aperture array.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Hisao Saito 2-3-1 Otemachi, Chiyoda-ku, Tokyo F-term in Nippon Telegraph and Telephone Corporation (reference) 2H097 CA11 CA12 CA14 5F041 AA05 CA34 CA40 DA82 DC83 FF16 5F046 BA01 CA03 CB22 5F073 AA72 BA09 CA07 EA24 FA30

Claims (3)

[Claims] 1. An emission peak wavelength of 200 nm to 450 nm.
An exposure apparatus, comprising: an excitation light source configured by arranging a plurality of nitride semiconductor light emitting diodes. 2. An emission peak wavelength of 350 nm to 370 nm.
2. An exposure apparatus according to claim 1, further comprising an excitation light source configured by arranging a plurality of said nitride semiconductor light emitting diodes. 3. An emission peak wavelength of 420 nm to 440 nm.
2. The exposure apparatus according to claim 1, further comprising: an excitation light source configured by arranging a plurality of the nitride semiconductor light emitting diodes having an active layer made of InGaN.