JPS6035516A - Method and device for exposure - Google Patents

Abstract

PURPOSE:To reduce the adverse influence caused by the foreign substance and the like adhered to a reticle, a mask and the like by a method wherein the image of a plurality of the same patterns are compounded in such a manner that they will be coincided. CONSTITUTION:The beam of light, which is sent from an optical system of illumination 10a and passed through the part 11a of a reticle, consists of the images of a pattern 12a and a foreign substance 13d, and it is reflected by a mirror 16 and a half-mirror 17. The beam of light sent from an optical system 10b and passed through the part 11b of the reticle consists of the images of a pattern 12b and a foreign substance 13b, and it passes through the half mirror 17. When missors 16 and 17 are adjusted in such a manner that the images of the patterns 12a and 12b will be coincided, the images formed by the foreign substances 13a and 13b are cancelled by the light passed through the parts 11a and 11b of the reticle respectively, no foreign substance is relatively left on the reticle, the pattern drawn on the reticle 11 alone reaches an optical system of illumination 18, and it is projected to the resist on a wafer 19.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to exposure technology, and for example, to a technology that is effective in transferring a pattern drawn on a reticle or mask to a resist on a wafer and exposing it to light. be.

[Background technology]

Conventionally, as an apparatus for transferring and exposing a pattern formed on the surface of a mask onto a wafer coated with photoresist, an apparatus such as that described in Japanese Patent Laid-Open No. 111076/1983 has been known (see Fig. 1). ). This device converts light generated by a light source 1 into uniform, parallel light using a condenser lens 2, and irradiates it onto a reticle 3 on which a pattern is drawn.

A part of this irradiated light is blocked by the light-blocking pattern on the reticle 3, foreign objects, etc., and most of the other light passes through the light-transmitting pattern of the reticle 3 and the light-transmitting glass plate with many foreign objects. The transmitted image is then reduced by a reduction lens 4 and projected onto a resist coated on a wafer 5. Since this resist is generally a positive type resist, when it is developed, a portion of the resist that is shielded from light by the reticle 3, that is, a resist corresponding to the position where the pattern or foreign matter was present remains.

Therefore, if the resist on the wafer 5 is exposed while the foreign object 6 is present on the reticle 3, the light from the light source 1 will be blocked by the foreign object 6, and the foreign object 6 will correspond to the position where the foreign object 6 is present (7). The image of the foreign object 6 will be transferred to the 50 portion of the paper. In other words, since the pattern other than the pattern of the reticle 6 is exposed to the resist (K) on the wafer 5, when that resist is developed, the resist where the image of the foreign object 6 has been transferred remains, resulting in poor exposure. there were.

Therefore, a method can be considered in which the influence of foreign matter is removed by exposing the same chip twice using a reticle with the same pattern drawn in two places. However, in such an apparatus, it is necessary to accurately match the positions of the first exposure and the second exposure, but moving the XY table to align the positions requires a lot of work in the equipment that reduces and exposes. It is extremely difficult to do so. The present invention has been made in view of these problems.

[Purpose of the invention]

An object of the present invention is to provide an exposure technique that reduces the influence of foreign matter attached to a reticle, mask, etc.

The above and other objects and novel features of the present invention are:
It will become clear from the description of this specification and the accompanying drawings.

[Summary of the invention]

A brief overview of typical inventions disclosed in this application is as follows.

In other words, images of foreign objects are not projected onto the object to be processed by combining the images of the respective patterns transmitted through multiple masks with the same pattern drawn on them or multiple masks with the same pattern drawn on them so that they match each other. Therefore, it is possible to perform exposure without being affected by foreign matter existing on the mask.

〔Example〕

FIG. 2 is a principle diagram for explaining an exposure apparatus that is an embodiment of the present invention.

As shown in FIG. 2, a mask, for example, a reticle 11 is irradiated with substantially parallel and uniform light in an illumination optical system 1o.

There are two identical patterns 12a on the reticle 11,
12b is drawn, and foreign matter 13 is attached to its upper part. Image 1 of light transmitted through this reticle 11
4m and 14b each include an image of the foreign object 13 in addition to the images of the patterns 12@ and 12b. 15 is pattern 1
This is a combining optical system that combines images of 2m and 12b so that they match.

The synthesized image synthesized by the synthesis optical system 15 is reduced to a desired magnification, for example, 1/10, by a projection optical system 18 and exposed to a predetermined position on a wafer 9 coated with resist, which is an object to be processed. do. Note that the wafer 19 is placed on the XY table 2.
0 by a certain distance, and after being positioned, it is exposed. Exposure is performed by repeating this operation.

Next, a detailed explanation will be given using FIG. 3. Illumination optical system 10a
and 10b are composed of a light source 1, a condenser lens 2, etc. Reference numeral 11 denotes a reticle, on the surface of which there are multiple (two in this example) patterns 12m and 12b drawn identically.
It is provided. Reference numeral 15 denotes a synthetic optical system, which includes a mirror 16 that reflects the light from the illumination system 10& that passes through the reticle 11 on which a pattern 12m is drawn, and a mirror 16 that reflects the light from the illumination system 10b that passes through the reticle 11 on which a pattern 12b is drawn. It consists of a half mirror 17 that transmits light and reflects the light reflected by mirror 16.

Here, the mirror 16 and the half mirror 17 are provided so as to be rotatable and parallel movable so that the images of the pattern 12m and the pattern 12b match in the combining optical system 15.

Furthermore, the arrangement of the patterns 12a and 12b on the reticle 11 is determined by the configurations of the combining optical system 15 and the illumination optical system 10. The images synthesized by the synthesis optical system J5 are reduced by, for example, a 1/10 reduction lens of the projection optical system 18, and exposed to a predetermined position on the resist coated on the wafer 19. This exposure is performed by step-and-repeat using an XY table 20 driven in the XY directions by a C motor or the like.

Note that 13a and 13b are foreign substances attached to the reticle 11.

Next, the operation and effect will be explained with reference to FIGS. 2 and 3. Since the light source 1a of the illumination optical system 108 is a point light source, the intensity of the light varies, and since it is not parallel light, it is converted into a uniform parallel light by the condenser lens 2a.
A pattern 12m on the reticle corresponding to the condenser lens 2a is irradiated with light. By the way, since the reticle 11 has a pattern formed of a light-shielding material on a light-transmitting glass substrate, no light passes through the portion where the pattern is formed. Furthermore, when a foreign object 13 or the like is present on the reticle 11, the foreign object blocks light and does not transmit light, just as a pattern is formed. Therefore,
The light from the illumination optical system 10a that passes through the Ila portion of the reticle consists of an image of the pattern 12j1 and the foreign object 138. These nine images are reflected by the mirror 16 of the combining optical system 15, and further reflected by the half mirror IHC. On the other hand, in the illumination optical system 10b, the light emitted from the light source 16 is irradiated onto the pattern 12b on the corresponding llb portion of the reticle via the condenser lens 2b.

At this time, since the foreign matter 13b is present, the pattern 12b
Since the light is blocked in the same way, the light transmitted through the llb portion of the reticle consists of the pattern 12b and the foreign object 13b. When this image passes through the half mirror 17, it is combined with the image reflected by the half mirror 17 described above. At this time, the mirror 16 and half mirror 17 are adjusted so that the images of the patterns 12m and 12b match. By the way, since there is no foreign object on the Jib portion of the reticle corresponding to the position where the foreign object 13m is present, the image formed due to the presence of the foreign object 13a is canceled by the light transmitted through the llb portion of the reticle, and the reticle is relatively noll
This means that the a partial quantity substance 13a does not exist. Similarly,
11 of the reticle corresponding to the position where the foreign object 13b is present.
Since there is no foreign object on the portion a, the image generated by the foreign object 13b is canceled by the light transmitted through the lla portion of the reticle, so that the foreign object 13b is relatively absent on the reticle 12b. In other words, since the image synthesized by the synthesis optical system 15 hardly contains any images caused by the presence of foreign matter, only the pattern drawn on the reticle 11 reaches the projection optical system 18. This projection optical system is provided with a reduction lens for reducing the composite image to 1/n, and projects the pattern 12 onto the resist on the wafer 19 at a size of 1/n. There is. This projection is performed by stepping and repeating the XY table in the XY directions.

〔effect〕

(1) In the images formed by multiple masks with the same pattern drawn or multiple masks with the same pattern drawn, the images of the respective patterns are combined using a synthesis optical system so that they match. Even if a foreign object is present on the object, the composite image does not include the image of the foreign object, so that an effect can be obtained in that an image corresponding to the pattern drawn on the mask can be projected onto the object to be processed.

(2) Images formed by a plurality of masks with the same pattern drawn or a plurality of masks with the same pattern drawn are synthesized using a synthesis optical system so that the images of the respective patterns match. Since the image of the foreign object is almost never projected onto the object to be processed, there is no need to inspect and correct defects that would be required when the foreign object is projected after developing the resist applied to the object. This effect can be obtained.

(3) By combining multiple identical patterns using a combining optical system, the image of the foreign object existing in each pattern is compensated for with other patterns, and the image of the foreign object is projected onto the object to be processed. There is no possibility that all pellets will be defective.

Although the invention made by the present inventor has been specifically explained above based on Examples, it is to be understood that the present invention is not limited to the above-mentioned Examples, and can be modified in various ways without departing from the gist thereof. not. For example, the composite image from the composite optical system may be directly exposed to the object to be processed without passing through the projection optical system. Alternatively, exposure may be performed using one illumination optical system instead of providing a plurality of illumination optical systems. Furthermore, the configuration of the synthetic optical system is not limited to the embodiment, and can be modified in various ways.

In the above explanation, the invention made by the present inventor was mainly applied to the exposure technology of semiconductor devices, which is the background field of application, but the invention is not limited thereto. It can be applied to techniques that transfer and expose a pattern drawn on a mask or the like using light, X-rays, etc.

[Brief explanation of the drawing]

Fig. 1 is a perspective view of a conventional exposure apparatus, Fig. 2 is a diagram showing the principle of an exposure apparatus according to an embodiment of the present invention, and Fig. 3 is a schematic diagram of an exposure apparatus according to an embodiment of the present invention. It is. 1.11L, 1b...light source, 2.2a, 2b-condenser lens, 3,11. lla, Ilb'' reticle, 4... reduction lens, 5, 19... wafer, 6.
13, 13a, 13b--Foreign object, 7... Image of foreign object,
10.10a, 10b - illumination optical system, 12a, 12b.
...Pattern, 14m, 14b...Light containing pattern and foreign object image, 15...Synthetic optical system, J6...Mirror, 17...Half mirror-118...Projection optical system,
20...XY table. Agent Patent Attorney Akio Takahashi Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] 1. Light from a light source is irradiated onto a plurality of masks on which the same pattern is drawn, or a plurality of masks on which the same pattern (turns) is drawn, and the pattern formed by the masks is irradiated with light from a light source. An exposure method characterized by combining images so that they match each other and projecting the combined image onto the object to be processed. 2. A light source and a mask on which multiple identical patterns are drawn or the same pattern. The pattern images formed by multiple masks drawn on the images are synthesized so that they match.