Multi-film stack etching with polymer passivation of an overlying etched layer

摘要

A method and apparatus for plasma etching a workpiece, such as a semiconductor wafer, including a thin film stack having a top film disposed over a bottom film with an intervening middle film there between. Etch selectivity between the top and bottom films may be as low as between 1:1 and 2:1 and a first carbon-lean gas chemistry is used to etch through the top film, a second carbon-lean gas chemistry is used to etch through the middle film, and the bottom film is etched through by alternating between depositing a polymer passivation on the top film using a carbon-rich gas chemistry and an etching of the bottom film with a third carbon-lean gas chemistry, which may be the same as the first carbon-lean gas chemistry.

主权项

1. A method of plasma etching a workpiece, comprising:
providing the workpiece to a plasma etch chamber, the workpiece including a film stack having a first film disposed over a third film with an intervening second film there between; forming a patterned mask layer on top of the first film; etching a first sidewall into the first film with a first plasma process; etching a second sidewall into the second film with a second plasma process; forming a polymer passivation on at least the first sidewall; and etching a third sidewall into the third film with a third plasma process after forming the polymer passivation, wherein the second plasma process is different than the first and third plasma processes.