JPH0298119A - Exposure device - Google Patents

Abstract

PURPOSE:To make the title exposure device optimum for manufacturing semiconductor devices by a method wherein the light flux from a lighting source of a lighting system is divided into two light fluxes of exposure light and non- exposure light by a light dividing means to lead them onto a mask surface and a wafer surface. CONSTITUTION:A pattern on a mask 8 surface is irradiated with an exposure light reflected by a cold mirror 3 our of light flux from a light source after unifying the light flux by a fly eye lens 5 through a shutter 4 further through a mirror 6. Then, the exposure light is projected on a water 10 surface at specified magnification. On the other hand, the heat ray of non-exposure light passing through another mirror 3 is cut off by a heat ray filter 21 to be led to the right and left side observation system by a light guide 23. Condenser lenses 24a, 24b converges light flux from the light guide 23 to irradiate the mask 8 surface using respective elements on the optical path reaching objective lenses 28a, 28b for lighting the alignment mark on the water 10 surface. In such a constitution, the title exposure device can be miniaturized and simplified by using only one light source 1.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to an exposure apparatus for semiconductor manufacturing, and particularly to an exposure apparatus for illumination when transferring a pattern such as an electronic circuit formed on a mask surface onto a wafer surface. The present invention relates to an exposure apparatus that requires two light beams: exposure light used as a wafer, and so-called non-exposure light used for illuminating alignment marks during wafer pre-alignment and mask-to-wafer alignment.

(Prior Art) Conventionally, in many exposure apparatuses for semiconductor manufacturing, so-called exposure light is used for exposure to transfer a pattern on a mask surface on which an electronic circuit pattern etc. is formed onto a wafer surface, and what is it? Separately, it can be used for visual observation during wafer pre-alignment or mask-to-wafer alignment, or for T
Two beams of so-called non-exposure light are used for illuminating an input device such as a V-camera.

At this time, the exposure light and the non-fog light generally use light fluxes from different light sources in different illumination systems within the exposure apparatus. In exposure equipment, alignment between masks and wafers is performed using various methods, and in recent exposure equipment in particular, various methods have been proposed to improve alignment accuracy by using image processing technology to align masks and wafers. ing.

One way to improve the alignment accuracy at this time is to increase the resolution of the mask and wafer III observation system.

In general, III
The brightness of the detected pattern image decreases, making it difficult to perform image recognition accurately.

To prevent the brightness of the pattern image from decreasing +h, for example, @
It is possible to strengthen the output of the light source of the M detection system, but this requires the use of a larger light source or an increase in the number of light sources.

However, if the output of the light source for observation is strengthened or the number of light frames is increased, the amount of radiant hot water will increase, and 199 equipment such as exhaust 921 will have to be installed.

In addition, due to the increase in the number of light source units, the overall size of the device has increased, resulting in
There has been a problem in that the J space has increased and it has become very difficult to efficiently arrange it in a limited space such as a clean room.

(Problems to be Solved by the Invention) The present 5aIJI is such that the light source in the illumination system used for exposure, such as an excimer laser or an ultra-high pressure mercury lamp, produces a luminous flux in the ultraviolet region that is generally necessary for exposure. Since a long-wavelength light beam is also emitted at the same time, a light splitting means is used to divide and extract the light beam emitted from the light source into at least two beams with different spectral characteristics, and one of these beams is used as the exposure light. An object of the present invention is to provide an exposure apparatus particularly suitable for semiconductor manufacturing, which has a simple configuration and which aims to downsize the entire apparatus by using the other light beam as non-exposure light.

(Means for solving the problem) p! by Teru 1 system! In an exposure apparatus that transfers a pattern on a mask surface onto a wafer surface, a light beam from a light source in the illumination system is divided into a plurality of light beams by a light splitting means,
One of the light beams is used as exposure light for illuminating the pattern on the mask surface, and the other light beam is used for illuminating the mask surface or the wafer surface, or for illuminating the pattern on the mask surface or the wafer surface. It was used as non-exposure light to illuminate the alignment marks during alignment.

In particular, the present invention is characterized in that the exposure light and the non-exposure light are composed of light beams having different spectral characteristics.

(Embodiment) FIG. 1 is a schematic diagram of a main part of an embodiment in which the present invention is applied to an exposure apparatus for semiconductor manufacturing.

In the figure, reference numeral 1 denotes a light source, for example, a light source having an oscillation spectrum in a wide wavelength range, such as an ultra-high pressure mercury lamp or an excimer laser that has the spectral characteristics shown in Figure 52. 2
is an elliptical mirror, which is used to effectively condense the emitted light flux from the light source 1 when a mercury lamp or the like is used as the light source. 3 is a light splitting means, which consists of, for example, a cold mirror, and mainly reflects the light beam in the exposure area corresponding to the ultraviolet rays necessary for exposure, as shown in the m2 diagram, and reflects the light beam in the exposure area that corresponds to the ultraviolet rays necessary for exposure, and It has properties that allow it to pass through. Reference numeral 4 denotes a shutter which blocks exposure light from the cold mirror 3 except during the A light. Reference numeral 5 denotes a fly's eye lens which adjusts the light distribution characteristics of the emitted light flux to make the illuminance distribution uniform over all eight surfaces of the mask, which are the irradiated surfaces.

Reference numeral 6 indicates a mirror 7, which is a condenser lens, and irradiates the surface of the mask 8 with the light beam from the mirror 6.

Reference numeral 8 denotes a mask, on which an electronic circuit pattern and an alignment mark are formed.

10 is a wafer, and alignment marks are formed on a part of the wafer. +9 is a projection optical system that projects the pattern on the mask 8 surface onto the wafer 10 surface at a predetermined reduction magnification.

In this embodiment, out of the luminous flux from the light source l, the cold mirror 3
The exposure light reflected by the mirror is passed through a shutter 4 to a fly's eye lens 5 to make the emitted light beam uniform, and then a condenser lens 7 passes through a mirror 6 to uniformly illuminate the pattern on the surface of the mask 8. .

Then, the pattern on the surface of the mask 8 is projected onto the surface of the wafer 10 by a projection optical system 9 at a predetermined magnification.

On the other hand, the non-exposure light corresponding to the non-exposed area in FIG. 2 that has passed through the cold mirror 3 is made incident on the heat ray filter 21.

The heat ray filter 21 blocks heat rays corresponding to unnecessary infrared rays for use in darkness 11, which will be described later, among the non-exposure light. 2
2 is an ND filter that adjusts the amount of light passing through it. 2
Reference numeral 3 designates a light guide, which is made of glass fiber or the like with an exit end separated into two limbs. ! It is guiding the light to the JJ observation system.

24a (24b) is a condenser lens and light guide 2
It collects the light flux from 3. 25a (25b) is a half mirror which allows the light beam from the condenser lens 24a (24b) to pass through and condense it with the condenser lens 26a (26b).
Objective lens 28a (
28b).

In this embodiment, each element in the optical path from the condenser lens 24a (24b) to the objective lens 28a (28b) illuminates the mask 8 surface J2, and further aligns the wafer 10 surface via the projection optical system 9. Illuminating the mark.

The light beams from the mask 8 and the alignment marks on the wafer 10 surface pass through the objective lens 28a (28b) and the mirror 27a.
(27b) Then, the light is reflected by a half mirror 25a (25b) via a condenser lens 26a (26b), and then is made incident on a relay lens 29a (29b).

Then, the light flux from the relay lens 29a (29bJ) is made incident on the erector lens 32 via the mirror 30a (30b) and the roof prism 3!.The erector lens 32 condenses the light flux from the roof prism 31, The light is guided to one image plane.

In this embodiment, each i! in the optical path from the condenser lens 24a to the mirror 30a! Each element in the optical path from the condenser lens 24b to the mirror 30b forms a left-hand observation system.

Then, the image of the alignment mark on the ti image screen formed by the right system and the left system is observed by the TV camera 33.

In this embodiment, when the alignment mark is detected, the shunter 4 is closed to block the exposure light from entering the mask surface F. Also, when using A light, mirror 27a (27b)
Then, the objective lens 28a (28b) is retracted out of the I-effect light flux, the shutter 4 is opened, and the exposure light is irradiated onto the entire surface of the mask 8.

In this example, a cold mirror is used as the light source 1 and the light beam 3, and the upper part of the light flux from the light source 1 is reflected in the ultraviolet region and used as exposure light, while the light flux with a longer wavelength is transmitted. It is characterized by the effective use of the luminous flux emitted from the light source l by using it as non-exposure light.

Then, the exposure light is irradiated onto the pattern on the mask surface through the illumination system, the non-exposure light is focused into a spot-like light beam, and the alignment mark on the mask surface and the wafer surface is irradiated through the light guide etc. and observation system. is lighting.

By using this method, the light beam transmitted through the cold mirror as a light splitting means is completely free of components in the ultraviolet region that would expose the resist, and the wafer can be aligned before alignment. This prevents the resist on the surface of the sea urchin from being exposed to light even when the beam is irradiated.

In this embodiment, the mirror 3 may be a total reflection mirror, and a filter having the same characteristics as described above may be provided as a light splitting means on the plate surface of the shutter 4. In this case, the function of the shunter 4 is a shutter.

When the shutter 4 is closed, the non-exposed light is sent to the shutter 4.
Each 2i'J may be configured so that the exposure light passes through the mask 8 and is guided to the mask 8, and the exposure light irradiates the surface of the mask 8 when the shutter 4 is open.

(Effects of the Invention) According to Unreleased II, as described above, the light beam from the light mound of the illumination system is divided into at least two light beams, high-light light and non-exposure light, using a light splitting means, and each light beam is divided into 4 to be used by guiding light onto the mask surface and the wafer surface through a predetermined optical system.
11I, it eliminates the need for a large light source or multiple light source units. c221. 'An exposure apparatus that is especially suitable for semiconductor manufacturing, which eliminates the need for a four-sided cold exhaust system, and which reduces the size and simplification of the entire apparatus! can be achieved.

4. Explanation in the cylinder of the 14th page 1st F4 is a schematic diagram of the main part of one embodiment of the present invention, 21A is an explanatory diagram of the radiation spectral characteristics of a conventional ultra-high pressure mercury lamp. 0 In the figure, 1 is the light source, 3 is the light source Light splitting - 1 stage 4 is shutter,
5 is a fly eye lens, 627a, 27b, 30a, 3
0b is a mirror, 7 is a condenser lens, 8 is a mask,
9 is a projection optical system, IO is a wafer, 21 is a heat ray filter, 22 is an ND filter, 23 is a light guide 24a,
24b, 26a, 26b are condenser lenses 25a, 25b are half mirrors, 29a, 29b are relay lenses, 32 is an erector lens, and 33 is a TV camera.

Claims (2)

[Claims] (1) In an exposure device that transfers a pattern on a mask surface illuminated by an illumination system onto a wafer surface, a light beam from a light source in the illumination system is divided into a plurality of light beams by a light splitting means, and one of the light beams is divided into a plurality of light beams. is used as exposure light to illuminate the pattern on the mask surface, and another beam is used as an alignment mark when observing the mask surface or wafer surface, or when aligning the mask and the wafer. An exposure device characterized in that it is used as non-exposure light for illuminating (2) The exposure apparatus according to claim 1, wherein the exposure light and the non-exposure light are composed of light beams having different spectral characteristics.