JPS61117552A - Exposing device - Google Patents

Abstract

PURPOSE:To improve the utilizing efficiency of light, by condensing laser light radiated from a laser oscillator to the incident end face of an optical fiber bundle. CONSTITUTION:Laser light from a laser oscillator 1 are made incident to the incident end face of an optical fiber bundle 3 and radiated from the flat fan-like radiating end 3b of the bundle 3 at a fixed angle on the same plane. The optical beam radiated from the end 3b is repeatedly reflected by a spherical mirror 4, whose reflecting mirror is a pat of such a sphere that the sphere has one point on the axis and its plane perpendicularly intersects the axis, other spheri cal mirrors 5 and 5, and plane mirrors 6, 6,- and becomes an arc-like slit of about 1-4mm in width by the action of the spherical mirrors 4 and 5. The arc-like light passing through a photomask 9 is repeatedly reflected among a trapezoidal mirror 8, concave mirror 9, and convex mirror 10 and forms a photomask pattern on a wafer 11 which is a body to be irradiated. The arc- like beam projects the photomask upon the whole area of a previously designat ed wafer by simultaneously moving the photomask 7 and wafer 11 in parallel with each other.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an exposure and light device that performs exposure by a scanning method, among devices that expose an object to be irradiated through a photomask.

[Conventional technology]

Exposure using a scanning method is used in various fields, but the most widely known method is when exposing semiconductor wafers. In order to speed up understanding, the explanation will be given below using a semiconductor wafer as an example.

IC manufacturing technology has also moved from LSI to VLSI, and even the lithography process has come to require higher resolution. The resolution when using an optical system is given by the following equation.

α8λ (1) ”” NA (μm) Here, λ is the wavelength of light (μm), and NA is the refraction angle at the focal point F of the optical lens 23 shown in FIG. ) is the numerical value given by , and is called the numerical aperture.

As can be seen from equation (1), in order to increase the resolution C, it is possible to increase the numerical aperture NA or decrease the wavelength λ.
As the NA increases, the problem of focal speed arises. That is, the depth of focus is given by Δ, so as the NA increases, the depth of focus becomes shallower, causing defocusing due to the flatness and unevenness of the wafer surface, and it is difficult to design an optical lens with an extremely large NA.

On the other hand, for example, the wavelength λ can be set to 365 by using an ultra-high pressure mercury lamp.
If we move to the ultraviolet region one after another (nm, 254nm, 185nm, etc.), the resolution will increase as the wavelength becomes shorter, but such ultraviolet rays are absorbed by ordinary optical lenses, and the materials of the lenses are limited. It becomes a thing.

For the above reasons, several exposure apparatuses have been developed that use a scanning method using a reflective optical system that does not cause problems such as absorption even when the wavelength λ is shortened.

In other words, this method utilizes the fact that the mask image is projected one-to-one onto the wafer using only the reflective optical system and only the circular arc portion (
USP 3,74aO15A, 0ffner) One uses an arc-type mercury lamp, and the other uses a short-arc type mercury lamp, and uses a reflective optical system to bring this light in an arc shape, forming a photomask pattern in the same way as the former. [Problem to be solved by the invention] However, in the conventional scanning method semiconductor wafer exposure apparatus described above, a method using an arc-shaped mercury lamp is required. In this case, there are problems such as variations in brightness over the arc length and the need for severe cooling, so a method using a short arc type mercury lamp and expanding it in an arc shape using a reflective optical system is used. In this case, the rate at which the light from the light source is captured by the reflective optical system is low, resulting in problems such as extremely poor light utilization efficiency.

[Means to solve the problem]

The exposure apparatus of the present invention includes a laser oscillator, and a plurality of optical fibers whose one end is bundled and whose end face is placed at a position to receive laser light from the laser oscillator, and whose other end is spread out in a fan shape at a predetermined angle. , a plurality of spherical mirrors that further reflect and expand the light beam emitted in a fan shape by the optical fiber onto a photomask in an arc shape, and project the arc-shaped reflected light onto an object to be irradiated via the photomask. , by simultaneously moving the photomask and the object to be irradiated, the photomask pattern is projected one-on-one over a pre-specified area by a scanning method.

[Effect]

In the present invention, the laser beam emitted from the laser oscillator becomes a narrow beam, and this beam enters the input end face of the optical fiber bundle. Since the light and the output end of the fiber bundle form a fan shape with a predetermined angle, the entire amount of laser light can be expanded into a fan shape and projected onto the spherical mirror. Furthermore, since the spherical mirror sequentially reflects and develops the incident light in an arc shape, the light from the light source can be efficiently projected onto the irradiated object in an arc shape, resulting in extremely high light utilization efficiency and eliminating variations in brightness over the entire length of the arc. There will be very few.

〔Example〕

The present invention will be explained in detail with reference to the drawings.

In one embodiment of the present invention, for example, as shown in FIG. 1, a laser beam from a laser oscillator 1 is received by an incident end face 3a of an optical fiber bundle 30 in which a plurality of optical fibers are bundled. As the laser oscillator 1, various types can be used as long as they emit ultraviolet rays. For example, an argon laser emits light with a wavelength of 488 nm or 515 nm, and a helium-cadmium laser emits light with a wavelength of 442 nm or 525 nm. It is sufficient to incorporate a harmonic conversion element to halve the wavelength and convert it to a shorter wavelength. It is also possible to perform spectroscopy using an Arike prism and use short wavelength light.

The output end 3b of the optical fiber bundle 3 has a flat fan shape, and the light emitted from it forms a light beam emitted from a certain point on the same plane at a constant angle. The light beam emitted from the output end 3b is reflected by a spherical mirror 4 which has the above point on its axis and whose reflecting mirror is a part of a sphere whose plane intersects perpendicularly to this axis. As it is repeatedly reflected by other spherical mirrors 5, 5 and plane mirror 6.6, it becomes an arc-shaped slit with a width of about 1 to 4 squares due to the action of spherical mirror 4.5, and passes through photomask 7. The arc-shaped light is a trapezoidal mirror 8, a concave mirror 9, and a convex mirror 1.
0, concave mirror 9, trapezoidal mirror 8 and reflection are repeated,
A photomask pattern is imaged onto a wafer 11 which is an object to be irradiated. This arcuate beam is exposed by simultaneously moving the photomask 7 and the wafer 11 in parallel and projecting the photomask pattern one-on-one over the entire area on the wafer surface specified in advance. It will be done.

Next, referring to the light utilization efficiency in the present invention,
Laser light travels in a straight line and has good reflection efficiency on reflecting mirrors, so the light usage efficiency is quite high.

Still, the laser oscillator is advantageous because heat is uniformly dissipated from the entire outer surface, so that the rate of heat being radiated in the direction of the optical system through which the laser beam travels is small.

〔Effect of the invention〕

As explained above, in the present invention, the laser beam emitted from the laser oscillator is focused on the incident end face of the original fiber bundle, so that the entire amount of light from the light source is guided to the optical fiber bundle. In addition, the entire amount of light emitted in a fan shape by an optical fiber is reflected and expanded by multiple spherical mirrors and plane mirrors, and is condensed as an arc-shaped slit with a width of 1 to 4. Compared to other methods, power consumption is much lower, and light usage efficiency can be significantly improved.

Note that the present invention is not limited to the above-described exposure apparatus for semiconductor wafers, but can also be applied to, for example, exposure of crystal resonators, acoustic wave elements, etc.

[Brief explanation of the drawing]

FIG. 1 is a detailed explanatory diagram of the present invention, and FIG. 2 is an explanatory diagram of the definition of the optical system NA. 1... Laser oscillator 3... Optical fiber bundle 6a.
...Incidence end face 3b...Output end 4.5...Spherical mirror 6...Plane mirror 7...Photomask 11...Irradiated object (wafer) Procedural amendment (voluntary) October 1985 11th of the month

Claims (1)

[Claims] A laser oscillator, a plurality of optical fibers whose one end is bundled and whose end face is placed in a position to receive the laser beam from the laser oscillator, and whose other end is unfolded in a fan shape at a predetermined angle, and the optical fibers emit light in a fan shape. The mirror includes a plurality of spherical mirrors that reflect and expand the reflected light beam onto the photomask in an arc shape, and projects the arc-shaped reflected light onto the object to be irradiated via the photomask. An exposure apparatus characterized in that a photomask pattern is projected one-on-one over a pre-designated area by a scanning method by simultaneously moving a photomask pattern and a photomask pattern.