Patent ID: 9543163
Date: 2017-01-10
CPC Classifications: H01J,H01L

Claim:
1. A method for etching a feature in a material layer comprising: (a) performing a main etching process in a processing chamber by supplying a main etching gas mixture and applying a RF bias power to etch an oxide layer exposed by a patterned mask layer disposed on a substrate, forming a feature with a first predetermined depth in the oxide layer; (b) subsequently performing a treatment process on the substrate by supplying a treatment gas mixture into the processing chamber to treat the etched feature in the oxide layer; (c) subsequently performing a chemical etching process on the substrate by supplying a chemical etching gas mixture different from the main etching gas mixture without applying the RF bias power into the processing chamber to continue etching the feature in the oxide layer, wherein the chemical etching gas includes at least an ammonium gas and a nitrogen trifluoride, wherein the chemical etching process further etches the feature to a second predetermined depth; (d) subsequently performing a transition process on the etched substrate by supplying a transition gas mixture into the processing chamber; and (e) repeatedly performing step (b)-step (d) to etch the feature in the oxide layer until an underlying substrate is exposed.