High aspect ratio selective lateral etching using periodic passivation and etching

摘要

Methods and devices for laterally etching unwanted material from the side walls of concave features are described herein. In various embodiments, the method etches a portion of the side wall, deposits a protective film over the entire portion of the side wall, and repeats the etching and deposition operations until the unwanted material is removed from the entire depth of the concave feature. To do. Each etching operation and each deposition operation may target a specific depth along the side wall of the feature. In some examples, unwanted material is removed from the bottom of the feature upwards, in other cases unwanted material is removed from the top of the feature downwards. Any combination of these may also be used. [Selection diagram] FIG. 2A