JPH01117322A - Reduction stepper - Google Patents

Abstract

PURPOSE:To make it possible to expose a set of photomasks simultaneously by an exposure-treatment by a method wherein a plurality of materials to be exposed are retained in the prescribed positional relation on a stage system, the reduced image of the reticle set on a plurality of reduced projection devices is image-formed on the surface of the material to be exposed, and the stage system is shifted at the prescribed distance by conducting an intermittent driving. CONSTITUTION:The reticles 61 and 62, on which different expanded pattern are formed, are placed on platens 31 and 32, and the photomask substrates 71 and 72, which are the material to be exposed, are retained at the lower part of the reduction lens systems 41 and 42 on a stage 51. By intermittently shifting the stage 51 by a driving control part 52, an exposure treatment is conducted on the photomask substrates 71 and 72. When a partial microscopic pattern is exposed on the photomask substrates, the stage 51 is driven, and the image formation position of the reduced projection image is shifted until it is coincided with the position of the next exposure. A number of partially microscopic patterns are exposed by the repetition of the above-mentioned operation, and at the same time, the exposure of the two photomask substrates having different pattern can be completed simultaneously.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a reduction projection exposure apparatus used for producing photomasks and the like used in the manufacturing process of semiconductor integrated circuits, for example.

[Prior Art] Semiconductor integrated circuits (ICs) and the like usually have a structure in which a large number of identical minute patterns are formed on a silicon substrate or the like in a predetermined positional relationship. Moreover, each of these micropatterns is generally formed by overlapping a plurality of different pattern layers through a plurality of photolithography steps. That is, when manufacturing such an IC, exposure is performed using a photomask with a different pattern for each photolithography process.

The photomasks used in each of these photolithography processes are those in which only a part of each minute pattern is formed to be exposed in that process, that is, the part of the minute pattern is placed in a predetermined positional relationship on the mask substrate. Many of these were formed.

Then, when these photomasks are stacked with the reference positions of each substrate aligned, the positional relationship of the partial micropatterns of each of them is combined so that each of the partial micropatterns forms the desired micropattern. must be in exactly the prescribed relationship.

This is because when this misalignment occurs, each pattern layer of the IC ends up being misaligned, resulting in the production of defective products.

Conventionally, such photomasks have been manufactured by performing exposure processing using a reduction projection exposure apparatus as shown in FIG.

That is, in FIG. 2, this reduction projection exposure apparatus is
A light source 1 consisting of a mercury lamp 1a and a reflection B 1 b;
A lens system 2 condenses the light from this light source 1 and converts it into parallel light.
a platen (mounting table) 3 arranged so that its center is located substantially on the optical axis of the lens system 2; and a reduction lens system 4 whose optical axis is common to the optical axis of the lens system 2. , which is disposed near the reduction lens system 4 and has a surface (exposure surface) perpendicular to the optical axis of the reduction lens system 4, and is positioned along a plane parallel to this surface under accurate position control. The stage system 5 is configured to be movable.

In order to perform exposure processing on a photomask substrate (a glass substrate, etc. with a light-shielding film formed on the surface thereof and a photoresist coated on the light-shielding film), which is the object to be exposed, using this reduction projection exposure apparatus, the platen 3 is , a reticle 6 serving as an enlarged mask in which a part of the microscopic pattern is enlarged is placed on the stage system 5, and the photomask substrate 7 is placed on the stage system 5.
was fixed, and the stage system 5 was moved intermittently.

That is, the reticle 6 has a pattern formed thereon by enlarging, for example, about 10 times one partial minute pattern to be formed on each photomask used in each of the photolithography steps, and this enlarged pattern The projection of the image is reduced by the reduction lens system 4 and focused on the photomask substrate. As a result, one partial minute pattern is exposed on the photomask substrate. At the same time as this exposure ends, the stage system 5 is driven and moved until the imaging position of the reduced projection image coincides with the next scheduled exposure position. This operation is repeated one after another until the -
Exposure of one photomask substrate used in two photolithography steps is completed. When this exposure is completed, next, the reticle 6 and photomask substrate 7 are replaced and the same exposure is performed to expose a photomask substrate to be used in another photolithography process.

By the way, as mentioned above, when the photomask substrates exposed by each exposure process are overlapped, the mutual positional relationship is accurate so that each of the partial micropatterns overlaps and forms the desired micropattern. must match. To achieve this, various processing conditions must be maintained, such as keeping the temperature and other environmental conditions as uniform as possible during each exposure process, and setting the reference position of the substrate to accurately match the reference position of the stage during each exposure process. had to be exactly the same.

Among these conditions, a condition that requires particular attention is the moving distance of the stage system 5 to move the substrate to the position where the next micropattern is exposed after the exposure of one micropattern is completed. In other words, if the moving distance of the stage system 5 is not exactly the same between exposure processes, pattern positional deviation will eventually occur no matter how completely the other conditions are set. For this reason, in the conventional reduction projection exposure apparatus, a high-precision distance measuring device such as a laser interferometer or an autocompensator is used for each exposure process to ensure that the moving distance is exactly the same. Strict adjustments were made.

[Problems to be Solved by the Invention] However, no matter how precise the adjustment is, due to the accuracy limitations of the laser interferometer, etc., it is difficult to overlay photomasks produced using the conventional reduction projection exposure apparatus. Accuracy is 3~5ppn (0.3~0 for 100mn)
．． The deviation was approximately 5 μm), and it was almost impossible to reduce the deviation to less than this. In addition, it is necessary to expose one sheet at a time, and complicated settings and adjustments must be made for each exposure process, resulting in extremely poor productivity.

An object of the present invention is to provide a reduction projection exposure apparatus that solves these problems.

[Means for Solving the Problems] The present invention makes it possible to hold a plurality of objects to be exposed on one stage system, and to form a reduced projection image of a different reticle on each object to be exposed. A plurality of reduction projection means are provided in the image processing apparatus, thereby theoretically eliminating discrepancies in the moving distances from one exposure location to another among multiple exposed objects, and simultaneously eliminating the difference in the moving distance between multiple exposed objects in one exposure process. This device significantly improves productivity by making it possible to expose a set of photomasks.Specifically, it can hold a plate-shaped object to be exposed and move it along a plane parallel to the exposure surface of the object. In a reduction projection exposure apparatus, the reduction projection exposure apparatus includes a stage system configured as shown in FIG. , the stage system is configured to be able to hold a plurality of objects to be exposed, and a plurality of the reduction projection means are provided so that reduced projection images of different reticles can be formed on the surfaces of the plurality of objects to be exposed, respectively. It has a configuration characterized by the following.

[Operation] In the above configuration, a plurality of objects to be exposed are held in a predetermined positional relationship on the stage system, and a reduced image of a reticle set in the plurality of reduction projection means is formed on the surface of each of these objects to be exposed. By intermittently driving and moving the stage system by a predetermined distance, it is possible to simultaneously perform exposure processing on a plurality of objects to be exposed.

In this case, since the moving distance of the stage system due to intermittent driving is in principle completely the same on each exposed object,
There is no risk of errors caused by the conventional method of exchanging the exposed object and reticle each time an exposure is performed, and moreover, one set of exposed objects is processed at the same time in - times of exposure processing. Therefore, it is possible to reduce errors caused by setting, etc., and to significantly improve productivity. [Embodiment] FIG. 1 is a diagram showing a reduction projection exposure apparatus according to an embodiment of the present invention.

In FIG. 1, reference numeral 10 is a light source, and this light source 10
consists of a mercury lamp 1oa that emits ultraviolet light and two reflecting mirrors 11b and 12b that collect the ultraviolet light. Lens systems 21 and 22 are provided at positions where the ultraviolet light is focused by the reflecting mirrors 11b and 12b, respectively, to convert the ultraviolet light into parallel light. Further, at the bottom of the figure of the lens systems 21 and 22, there are platens 31 and 32 arranged so that their centers are approximately located on the optical axes of these lens systems, and platens 31 and 32 that align the optical axes of these lens systems and their front axes. Common reduction lens systems 41 and 42 are respectively arranged. In this case, the light source 10, lens systems 21 and 22, platens 31 and 32, and reduction lens systems 41 and 42 constitute reduction projection means.

A stage system 50 is arranged below the reduction lens systems 41 and 42 in the figure. This stage type 5
0 is a stage 51 having a wide surface perpendicular to the optical axes of the lens systems 41 and 42, and a drive that moves this stage 51 along a plane parallel to the surface under precise position control. It is composed of a control section 52.

Therefore, now the reticles 61 and 6 with different enlarged patterns formed on the platens 31 and 32, respectively.
2 and the reduction lens system 4 on the stage 51.
1 and 42, a photomask substrate 71 serving as an exposed object is placed below
and 72, respectively, and the stage 51 is moved intermittently by the drive control section 52, whereby the photomask substrates 71 and 72 can be subjected to exposure processing.

That is, the projected images of the enlarged patterns of the reticles 61 and 62 are reduced by the reduction lens systems 41 and 42, and are projected onto the photomask substrates 71 and 72, respectively.
is imaged. As a result, each of these photomask substrates is exposed to one of the above-mentioned partial micropatterns. At the same time as this exposure ends, the stage 51 is driven and moved until the imaging position of the reduced projection image coincides with the next scheduled exposure position. This operation is repeated one after another to expose a large number of partially minute patterns, and at the same time the exposure of two photomask substrates having different patterns is completed.

The embodiment described above has the following advantages.

That is, the photomask substrates 71 and 72, which are the objects to be exposed,
are held on the same stage 51 and are moved at the same time, so the moving distance from one exposure location to the next exposure location is in principle completely the same between the two substrates. For this reason, there is no need to adjust the moving distance as in the case of conventional exposure for each substrate, and there is no error caused by it. Since there is no need to touch the substrate at all, errors caused by setting can be significantly reduced compared to conventional methods that require setting for each exposure, and two substrates can be exposed at the same time. Therefore, the environmental conditions during exposure can be kept almost completely the same, and errors can also be reduced from this point of view. In addition, since two substrates can be exposed in -1 exposures, not only can the hassle of setting and adjustment be saved, but the exposure time can be halved, making a significant contribution to improving productivity. There is something.

In the above embodiment, in order to simplify the explanation, an example was given in which the stage system held two objects to be exposed and two reduction projection means were provided, but three or more of these may be used as necessary. Of course, this should be done.

Further, in the above embodiment, an example was shown in which two separate reticles having different patterns were used;
Of course, two separate reticles having the same pattern may be used.

Furthermore, the object to be exposed is not limited to the photomask substrate, and naturally includes other exposed objects that require similar exposure.

[Effects of the Invention] As described in detail above, the reduction projection exposure apparatus according to the present invention is capable of holding a plurality of objects to be exposed on one stage system, and is capable of attaching a different reticle to each of the objects to be exposed. A plurality of reduction projection means are provided so as to be able to form reduced projection images, and thereby, in principle, discrepancies in moving distances from one exposure location to an exposure location in a pond can be eliminated among a plurality of objects to be exposed, and - It is possible to expose a set of photomasks at the same time in two exposure processes, thereby significantly improving productivity.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a reduction projection exposure apparatus according to an embodiment of the present invention, and FIG. 2 is a diagram showing a conventional example of the present invention. 10.21, 22.31, 32.41.42...
・Light source, lens system, platen and reduction lens system constituting the reduction projection means, 50...stage system, 61.62...reticle, 71.72...exposed object The main photomask substrate.

Claims (1)

[Scope of Claims] A stage system configured to hold a plate-shaped exposed object and be movable along a plane parallel to the exposure surface of the exposed object, and the exposed object held by this stage system. A reduction projection exposure apparatus comprising reduction projection means for forming a reduction projection image of a reticle on which an enlarged pattern is formed on an exposure surface of the apparatus, wherein the stage system is configured to be able to hold a plurality of objects to be exposed, and A reduction projection exposure apparatus characterized in that a plurality of reduction projection means are provided so that reduction projection images of different reticles can be respectively formed on the exposure surfaces of the plurality of objects to be exposed.