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).