Scanning exposure method

Abstract

A step-and-scan exposure method .Iadd.and a scanning exposure apparatus .Iaddend.in which a mask has a plurality of patterns and the number of patterns to be transferred to each shot area of a photosensitive substrate varies. The scanning and stepping movements are controlled in accordance with the number of patterns transferred, and dimensions of a pattern illumination area are varied in accordance with the patterns to be transferred. Transfer of a pattern to a shot area is omitted when an image of the pattern on the shot area would extend beyond the photosensitive substrate. Elimination of exposure scanning movements for patterns that are not to be transferred permits rapid movements of the mask and the substrate to scanning start positions.

Description

BACKGROUND OF THE INVENTION1. Field of the InventionThe present invention relates to a scanning-type exposure apparatus for scanning a mask (or a reticle) and a substrate synchronously to transfer a pattern of the mask to the substrate in a photolithography process for manufacturing, e.g., a semiconductor, a liquid crystal display device or a thin film magnetic head and more particularly to an exposure apparatus of a step-and-scan system for transferring a pattern of a mask to each of a plurality of shot areas on a substrate successively on a scanning exposure system.2. Related Background ArtIn a photolithography process for manufacturing a semi-conductor or the like, a projection-type exposure apparatus is utilized in which the image of a pattern on a mask or a reticle (hereinafter referred to as the reticle) is transferred via a projection optical system to a photosensitive substrate (a wafer or glass plate with photoresist applied thereto). Recently, the sizes of semiconductors t...

AI Technical Summary

Benefits of technology

It is an object of the present invention to provided a scanning-type exposure apparatus in which when using a plurality of circuit patterns (chip patterns) arranged along a scanning direction or a non-scanning direction perpendicular to the scanning direction and exposing a plurality of shot areas on a photosensitive substrate on a step-and-scan system, the total time for moving the mask and / or performing the stepping of the substrate other than the time for exposing effective areas of the shot areas on the substrate is shortened to improve the throughput of the exposure process.

Only the chip pattern of one sub-pattern area (PA3) on the mask (R) is exposed to the incomplete shot area (SA6) on the substrate (W). Therefore, in FIG. 2, in synchronism with scanning the sub-pattern area (PA3) with respect to an illumination area (21), one-third of the shot area (SA6) on the substrate (W) is scanned with respect to an area corresponding to the illumination area (21) in a direction opposite to a locus (T6). Thereafter, the stepping of the substrate stage is performed at a permissible highest speed to set the shot area (SA7) on the substrate (W) to a scanning start position. In parallel to the stepping operation, the mask stage is driven at a permissible highest speed in a direction corresponding to a locus (U6) to set the second sub-pattern area (PA2) on the mask (R) to a scanning start position. Then, in synchronism with scanning only the sub-pattern areas (PA3, PA2) on the mask (R) with respect to the illumination area (21), two-thirds of the shot area (SA7) is scanned in a direction opposite to a locus (T7). Owing to such a sequence, the time for moving the mask and performing the stepping of the substrate other than the time for exposing the effective areas (here, the one-third, or two-thirds of the shot area) of the shot areas on the substrate (W) is shortened.

Also, in the case of making the width of the illumination area (21) variable by means of the variable field stop, for example, in FIG. 6, when the stepping of the substrate (W) is performed from the shot area (SA6) to which only the chip pattern of one sub-pattern area can be transferred to the shot area (SA7) to which the chip patterns of two sub-pattern areas can be transferred, the mask (R) is scanned for an amount corresponding to the amount indicated by the locus (U6) on the shot area (SA6) in the state with the illumination area closed. Then, in the following shot area (SA7), in synchronism with scanning the mask (R) in the direction opposite to the scanning direction of the mask in the shot areas (SA6) for an amount corresponding to the locus (T7) in the state with the illumination area (21) opened, the substrate (W) is scanned in the direction opposite to the locus (T7). Thereby, unnecessary movement of the mask is prevented, making it possible to shorten the exposure time.

According to the second method of the present invention, for example, as shown in FIG. 9, a plurality of identical circuit patterns (PA4, PA5) are formed on a mask (R) along a second direction (non-scanning direction) perpendicular to a scanning direction and only one circuit pattern (PA5) on the mask (R) can be transferred to a shot area (SH1) on a substrate (W) in FIG. 10. Further, the width of the shot area (SH1) in the non-scanning direction is H and the width thereof in the scanning direction is V. When scanning and exposing the shot area (SH1), the shot area (SH1) is overlapped with the projected image (30A) of the plurality of circuit patterns on the mask in the non-scanning direction for the width H / 2, and only the circuit pattern (PA5) on the mask (R) is scanned with an illumination area (21A), as shown in FIG. 9. Thereby, the circuit pattern is transferred to only the overlapped portion (effective portion) within the shot area (SH1). Next, when scanning and exposing a shot area (SH2) adjacent to the shot area (SH1) in the non-scanning direction, the stepping of the substrate (W) is performed for H / 2. Therefore, the amount of stepping is half of the amount of stepping according to the conventional exposure method, whereby the throughput of the exposure process is improved.

Problems solved by technology

Therefore, unnecessary portions of the incomplete shot areas (e.g., the peripheral end portion of the wafer) are exposed also.

Therefore, time is wasted for scanning the unnecessary portions, which causes the exposure time per shot to become long.

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