JPH0519692B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an exposure apparatus, and more particularly to an exposure apparatus for projecting and exposing a fine pattern of an integrated circuit such as an IC or LSI onto a silicon wafer surface.

In general, in exposure equipment for manufacturing ICs, LSIs, etc., a mask pattern depicting an integrated circuit such as an IC, LSI, etc. is illuminated by an illumination optical system, and the mask pattern is projected onto the silicon wafer surface using a projection optical system inside the exposure mechanism. The image is projected and exposed using a system. Ultra-high pressure mercury lamps, halogen lamps, etc. are often used as light sources for illumination. In order to obtain high throughput, the illumination light source is required to be able to provide sufficient illumination on the wafer surface and to emit a spectrum with a narrow wavelength width so that the optical performance of the projection optical system can be sufficiently exhibited.

On the other hand, since the projection optical system in the exposure mechanism normally has aberrations corrected only for a narrow wavelength range, an interference filter is used as part of the illumination optical system to narrow the spectral width of the light beam from the light source as much as possible. .

Therefore, the intensity of the luminous flux for illumination tends to decrease.

For this reason, exposure apparatuses have traditionally been required to have high-output light sources.

In general, a light source that emits a high-output light beam with a narrow spectral width inevitably requires a large-sized device as a whole.

For example, excimer lasers have high output and short oscillation wavelengths, such as 248.5 nm or 249.5 nm, and can emit light with an extremely narrow spectral width due to injection locking. Furthermore, the oscillation wavelength can be changed by changing the gas sealed inside. However, this excimer laser is extremely large and heavy. For example, the size is 150 x 100 x 50 cm and the weight is about 150 kg. For this reason, it is extremely difficult to arrange the excimer laser within the exposure apparatus and to integrate it as a whole.

Generally, light sources for illumination have a limited lifespan and must be replaced with a new light source after long-term use.

However, exposure apparatuses are large in size, have extremely complex internal configurations, and are assembled with high precision. Therefore, it is time consuming and very troublesome to replace the light source within the exposure apparatus and adjust it so that it matches other members with high precision.

As described above, when the illumination light source used in the exposure apparatus is large and heavy, or when the illumination light source is frequently replaced, it is preferable to configure the illumination light source and the exposure mechanism separately and independently.

However, when the illumination light source and the exposure mechanism are configured separately, in order to uniformly illuminate the mask pattern, the light beam from the light source must always enter the light beam receiving port of the exposure mechanism under the same conditions and with high precision. It won't happen.

Generally, the exposure mechanism has a stretch-and-repeat mechanism, so the size is approximately 30 x 30 cm and the weight is approximately 20 kg.
A moving member is incorporated for moving the X and Y stages of the wafer, and for focusing by an autofocus mechanism that automatically focuses the mask pattern and the wafer. In order to repeatedly perform focusing and exposure, members are constantly moving within the exposure mechanism. For this reason, each member of the exposure mechanism inevitably vibrates, albeit slightly. Therefore, it becomes very difficult to make the light beams from separate and independent light sources enter a predetermined position of the exposure mechanism with high precision.
In particular, vibrations make it difficult to uniformly illuminate the mask pattern using the illumination optical system, resulting in errors such as changes in line width when printing the mask pattern onto the wafer surface, which can cause problems in the production of ICs, LSIs, etc. This will increase the defective rate.

The present invention was conceived in view of the above circumstances, and its purpose is to provide an exposure apparatus that enables highly accurate exposure using an illumination light source and an exposure mechanism that are arranged separately. be.

In order to achieve the above object, the exposure apparatus of the present invention provides an exposure mechanism section that holds the mask and the wafer separately and independently relative to a light source that generates exposure light useful for printing a mask pattern onto a wafer. and on the exposure mechanism side, after dividing the exposure light generated by the light source into multiple beams, the mask is irradiated with each divided beam in order to print the pattern of the mask onto the wafer. an irradiation system;
The present invention is characterized in that an anti-vibration system is provided to prevent fluctuations in the position of exposure light generated by the light source entering the irradiation system.

Further, the vibration isolation system includes a plurality of optical members and a gyroscope that spatially fixes one of the optical members against vibrations generated in the exposure mechanism section;
Furthermore, the light source is an excimer laser.

This makes it possible to always accurately guide the luminous flux from the independently arranged illumination light sources to a predetermined position within the exposure mechanism section, making it possible to perform highly accurate exposure.

Next, a schematic diagram of an embodiment of the exposure apparatus of the present invention is shown in FIG. In the figure, reference numeral 1 denotes a light source for illumination, which is a large, high-output light source such as an excimer laser. Reference numeral 2 denotes an exposure mechanism section, which is made up of members numbered 4 onwards, and 3 is an anti-vibration optical system, which is made up of optical members with a gyroscope, as will be described later. 4 is a system in which a beam expander and an optical integrator are placed side by side. The optical integrator is for uniformly illuminating the mask pattern and is composed of, for example, a fly's eye lens or a bundle of square prism lenses. 5 is a condenser lens for illumination, which collimates the multi-luminous flux emitted by the optical integrator. 6 is a reflector, 7 is an IC
Masks with integrated circuit patterns such as
8 is a projection optical system, 9 is a wafer, and projection optical system 8
is for projecting the image of the mask 7 onto the wafer 9.

The anti-vibration optical system 3 of this embodiment is provided in a part of the exposure mechanism section 2, and prevents the optical axis of the exposure mechanism section 2 from being decentered with respect to the optical axis of the light source 1 due to vibrations generated from the exposure mechanism section 2. is corrected so that the light beam from the light source 1 always enters the optical integrator 4 at a predetermined position.

FIG. 2 shows a schematic diagram of an optical system of an embodiment of the vibration-proof optical system used in this embodiment. The anti-vibration optical system shown in the figure has two right-angled prisms 21 and 22, and a gyro 23 is attached to one of the prisms 22, so that they are spatially fixed. Even if the prism is tilted, the optical axis is not decentered and the light beam S always enters a predetermined position.

The prism material in this embodiment is preferably made of fused silica, CaF ₂ or the like when an excimer laser whose main oscillation wavelength is 248.5 nm is used as a light source.

In the present invention, if the luminous flux emitted from the illumination light source is sufficiently transmitted, Fig. 3A and B
As shown in FIG.
The anti-vibration optical system constituted by the control system 34 surrounded by 3 may be disposed in a part of the illumination optical system or in a part of the optical integrator. Also, Figure 4A,
As shown in B, a plano-convex lens 42 and a plano-concave lens 43, which act as a variable polarization prism, are combined in front of the projection optical system 41 of a part of the illumination optical system or the exposure mechanism, and one of the lenses 42 is rotated. An anti-vibration optical system spatially fixed by the device 44 may be used to eliminate the influence of vibrations within the exposure mechanism relative to the light source on the incident position of the light beam.

In addition, in the present invention, vibration-proof optical systems disclosed in Japanese Patent Publication No. 56-34847, Japanese Patent Publication No. 56-40805, Japanese Patent Publication No. 57-7415, etc. can be applied.

In the present invention, if vibration occurs within the illumination optical system, an exposure apparatus with even higher precision can be achieved by providing a vibration-proofing optical system within the illumination optical system as well as the exposure mechanism. Furthermore, it is preferable to integrate the anti-vibration optical system with the optical integrator, since this simplifies the entire device.

As described above, according to the present invention, it is possible to always guide the luminous flux from the independently arranged illumination light sources to a predetermined position within the exposure mechanism with high accuracy, so that the light flux between the light source and the exposure mechanism can be accurately guided. Even if vibrations occur, the mask can always be well illuminated, making highly accurate exposure possible.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of an embodiment of the present invention, FIG.
FIGS. 3 and 4 are schematic diagrams of an optical system according to an embodiment used as a part of the present invention. In the figure, 1 is an illumination light source, 2 is an exposure mechanism, 3 is an anti-vibration optical system, 4 is an optical integrator, 5 is an illumination condenser, 7 is a mask pattern, 8 is a projection optical system, 9 is a wafer surface, 23,3
Numbers 4 and 44 are Jairo.

Claims (1)

[Scope of Claims] 1. An exposure mechanism section that holds the mask and the wafer is arranged separately and independently relative to a light source that generates exposure light useful for printing a mask pattern onto a wafer, and the exposure mechanism section side The method includes: an irradiation system that divides the exposure light generated by the light source into multiple beams and then irradiates the mask with each divided beam in order to print the pattern of the mask onto the wafer; An exposure apparatus comprising an anti-vibration system that prevents fluctuations in the position of exposure light entering the irradiation system. 2. The vibration isolation system includes a plurality of optical members and a gyroscope that is spatially fixed against vibrations generated in one of the optical members and the exposure mechanism section. exposure equipment. 3. The exposure apparatus according to claim 2, wherein the light source is an excimer laser.