Rotational mask scanning exposure method and apparatus

Abstract

A method and rotational mask scanning apparatus for exposing a plurality of images on a workpiece, include a rotatable mask having a pattern of image segments thereon, an optical system for projecting the image segments onto the workpiece, and a device for at least one of rotating the mask and for moving the workpiece so as to continuously expose a plurality of regions on the workpiece with the pattern of image segments.

Description

[0001] 1. Field of the Invention[0002] The present invention generally relates to increasing the throughput of scanning lithography systems, and more particularly to a rotational mask scanning method and apparatus for increasing the throughput of such systems.[0003] 2. Description of the Related Art[0004] Overlay and image size specifications continue to decrease at a rapid pace driving the migration from traditional step and repeat exposure tools to scanning systems which have improved optical subsystems. However, while the improved optics of the scanning systems may meet the more rigorous specifications, the throughput of these systems is nonoptimal which increases the operation costs.[0005] Conventional translational scanning masks utilize considerable amounts of time stopping and starting. After each field is printed, a reticle of a scanning system must be stopped, repositioned, and accelerated to the selected scanning speed. As a result, considerable mass reduction design const...

AI Technical Summary

Benefits of technology

This approach enhances overall throughput, simplifies reticle handling, and allows for future improvements with increased wafer stage speed and laser power, reducing operation costs and complexity while eliminating seams in repetitive image printing.

Problems solved by technology

However, while the improved optics of the scanning systems may meet the more rigorous specifications, the throughput of these systems is nonoptimal which increases the operation costs.

Conventional translational scanning masks utilize considerable amounts of time stopping and starting.

As a result, considerable mass reduction design constraints are placed on the reticle and reticle stage.

Thus, even though the traditional translational masks utilize very high acceleration / deceleration and scanning speeds to maximize the time spent exposing the wafer, considerable time is still lost in stopping and starting, as mentioned above.

As a result, this greatly reduces the throughput of the scanning systems and increases the complexity and cost of the reticle stage.

Furthermore, fundamental throughoput limits are being reached due to the increasing percentage of time spent on overhead tasks (e.g., stopping, starting, aligning, etc.) as opposed to time spent exposing the wafer.

The conventional systems do not allow for future throughput improvements as wafer stage speed and laser power increases.

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