Tung & Associates
Step and scan exposure system equipped with a plurality of attenuator blades for exposure control
A step and scan exposure system that is equipped with a plurality of attenuator blades for achieving exposure control in a photolithographic scanner is described. In the exposure system, at least two attenuator blades each equipped with at least three attenuators are utilized for producing an attenuated optical beam from an optical source such as from a mercury lamp. By using a suitable number of attenuator blades and a suitable number of attenuators in each blade, any combination of light transmission attenuated can be provided. For instance, when three attenuators are provided in each of three attenuator blades, a light transmission can be controlled between 10% and 90% at 10% increment between each two adjacent attenuators. By using the present invention novel exposure system with the multiple number of attenuator blades, the throughput of a photolithographic process is not significantly sacrificed since the scanning speed of the wafer stage need not be significantly reduced in order to produce the desirable exposure.
Taiwan Semiconductor Manufacturing Co., Ltd.
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Meng Chun
Li