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Application filed by United Microelectronics CorpfiledCriticalUnited Microelectronics Corp
Priority to TW088103890ApriorityCriticalpatent/TW371727B/en
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Publication of TW371727BpublicationCriticalpatent/TW371727B/en
A method of producing strong PSM wherein a phase shifting layer is formed on the mask substrate, a first opening and a send open are defined on the phase shifting layer, which is etched to expose the first open to a first depth on the mask substrate, but maintaining a 90 degree phase shift angle between the first open and the a second depth, and 180 degree phase shift angle between the second depth and the second open, continue etching the first and second opens until the mask substrate is entirely exposed to form a dual trench structure.