BARC etch comprising a selective etch chemistry and a high polymerizing gas for CD control

摘要

A BARC etch comprises a selective etch chemistry in combination with a high-polymerizing gas for CD control. The BARC etch may be used in a via-first dual damascene method. After via ( 116 ) pattern and etch, a thick BARC layer ( 120 ) is deposited to fill the via ( 116 ) and coat the IMD ( 110 ). A trench resist pattern ( 125 ) is formed over the BARC layer ( 120 ). Then, the exposed portion of BARC ( 120 ) over the IMD ( 110 ) is etched using a high-polymerizing gas added to a selective etch chemistry. The more polymerizing gas passivates the trench resist ( 125 ) sidewall to preserve or improve the trench CD. During the main trench etch, portions of BARC ( 120 ) remain in the via to protect the etch-stop ( 104 ) at the bottom of the via ( 116 ).