JPH0374505B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an optical exposure apparatus used for manufacturing semiconductor devices.

More specifically, the present invention relates to a reduction projection excimer exposure apparatus devised to realize ultrafine processing in a photolithography process in semiconductor device manufacturing.

2. Description of the Related Art Conventionally, reduction projection exposure apparatuses (steppers) using ultra-high pressure mercury lamps as light sources have already been commercially available for microfabrication of semiconductor devices, particularly LSIs, VLSIs, etc. However, conventional steppers only use the G-line (436nm) and I-line (365nm) of ultra-high pressure mercury lamps.
Because of this, the resolution was limited to about 1.2 μm for the g-line and 0.8 μm for the i-line. At these wavelengths, it is nearly impossible to obtain the 0.5 μm resolution required for future 4MbitRAM and 16MbitRAM production.

Therefore, in recent years, XeCl (308 nm), KrF (249 nm), and ArF (193 nm), which have shorter wavelengths than g-lines and i-lines, have been
The development of exposure apparatuses using excimer light sources such as m) has begun to be considered.

Problems to be Solved by the Invention However, compared to ultra-high-pressure mercury lamps, excimer light sources use high-voltage pulsed discharge for oscillation, so vibrations caused by shock waves during discharge cause major problems during alignment and exposure. becomes. Furthermore, the large installation space for the light source is also a problem for the semiconductor manufacturing industry, which requires ultra-clean rooms. If it is only for anti-vibration measures during discharge,
This can be solved to some extent by placing the light source, lens system, wafer stage, mask holder, etc. all on the same anti-vibration table, but in this case, the installation space in the ultra-clean room will be about three times larger, and the optical axis will be affected by vibrations. The problem of misalignment remains. Accordingly, it is an object of the present invention to effectively perform vibration isolation during oscillation, to reduce the required area of an ultra-clean room, and to further prevent deviation of the optical axis due to vibration.

Means for Solving the Problems The exposure apparatus of the present invention includes a reduction projection lens, a wafer stage, a mask holder, a light emitted from an excimer light source by electric discharge, and a first vibration isolation table fixed to the excimer light source on which the excimer light source is placed. a first mirror that receives the light emitted from the light source; and the reduction projection lens;
a second mirror fixed to a second vibration isolation table on which a wafer stage and a mask holder are mounted; and second
A configuration is used in which the mirrors are combined so that the optical axes of the mirrors coincide with the direction of vibration caused by the vibration of the light source of the first vibration isolation table.

Therefore, according to the present invention, vibrations generated during oscillation of the light source are not transmitted to the main body including the lens system, and since the light source and the main body are completely separated, ultra-cleanliness is required. Only the main unit can be installed in an ultra-clean room, while the light source can be installed in a separate room. By aligning the optical axis between the first and second mirrors with the direction of vibration caused by the vibration of the light source of the first vibration isolation table, even if vibration occurs, the optical path length will only expand or contract, and the light will not be transmitted. It has the effect of preventing shaft misalignment. Therefore, the above-mentioned effects are exhibited.

Embodiment Hereinafter, an embodiment of the present invention will be described using FIG. That is, as a light source part, a KrF excimer laser light source 2 placed on a first vibration isolation table 1 and a first mirror 3 directly fixed to the first vibration isolation table 1 that bends the light emitted from the light source 2 in the vertical direction are used. Assemble. On the other hand, as a main body, a semiconductor substrate W placed on a second vibration isolating table 4
, a wafer stage 5 supporting a reduction projection quartz lens 6, a beam splitter 7, a mask holder 8 holding a mask M, a condenser lens 9, a second
A main body part 13 consisting of a mirror 10, an integrator 11, and a third mirror 12;
an alignment lens 14 fixed to, an alignment light source 15 (for example, light from an ultra-high pressure mercury lamp separated by a cut filter or a monochromator),
An alignment optical system 19 consisting of a beam splitter 16 for alignment, an IIT 17 for amplifying image pattern signals, and a CCD camera 18 for image reading is assembled. In addition, in order to align the mask M and the wafer W, a computer 20 is separately installed to process image signals read by the CCD camera 18 and to control movement of the wafer stage 5.

As described above, in the excimer light source 2, shock waves caused by discharge during oscillation cause discharge and vibration in a direction perpendicular to the light from the light source 2 when the light source 2 is installed horizontally as shown in FIG. At this time, in order to guide the excimer light emitted from the light source to the lens, the optical axes of the first mirror 3 fixed to the first vibration isolation table 1 and the second mirror 10 fixed to the main body are aligned, and Optical axis 2 between these two mirrors (coupling mirrors)
The direction of 1 should match the vibration direction of the vibration isolation table (in this case, use air suspension for the vibration isolation table and align it vertically).

Effects of the Invention In an excimer exposure apparatus, by having the structure of the present invention, that is, placing the light source section and the main body section on separate anti-vibration stands, it is possible to completely prevent strong vibrations from being transmitted to the main body section when the excimer light source oscillates. .

By matching the direction of vibration of the vibration isolation table caused by the vibration of the light source with the optical axis between the first and second mirrors, it is possible to prevent deviations in the optical axis during vibration between separate devices. can be prevented. In this case, deviations in optical path length cannot be prevented, but since the laser beam is a parallel beam and everything after the integrator is integrally constructed on the main body side, it has no relation to pattern resolution.

Furthermore, by separating the main body and the light source, the space in the ultra-clean room in which the main body is installed can be significantly reduced.

For the above reasons, it is possible to complete an excimer exposure device with a resolution of 0.5 μm, which is necessary for ultra-super LSI at a practical level. Note that the excimer light source is not limited to KrF. It will also be clear that the same effect can be obtained with a catoptric reduction projection exposure apparatus.

[Brief explanation of drawings]

FIG. 1 is a conceptual diagram for explaining an excimer exposure apparatus according to an embodiment of the present invention. 1...First vibration isolation table, 4...Second vibration isolation table, 3...
1st mirror, 10...2nd mirror, 5...wafer stage, 6...quartz lens, 8...mask holder.

Claims (1)

[Claims] 1. A reduction projection lens, a wafer stage, a mask holder, a light source that emits excimer light by electric discharge, and a first mirror that is fixed to a first vibration isolation table on which the excimer light source is placed and receives the light emitted from the light source. the reduction projection lens, a wafer stage, and a second mirror fixed to a second vibration isolation table on which the mask holder is mounted, and the light emitted from the light source is transmitted from the first mirror to the second mirror to the lens. The exposure apparatus is characterized in that the first and second mirrors are combined so that the optical axis between the first and second mirrors coincides with the direction of vibration caused by the vibration of the light source of the first vibration isolation table. .