Extended acid etch for oxide removal

A method, comprising:

• forming a photoresist layer on a surface of a device wafer of a micro-electromechanical-system (MEMS) structure;
• removing one or more first portions of the photoresist layer to form a pattern in the photoresist layer;
• forming one or more MEMS actuators in the device wafer by etching the device wafer based on the pattern in the photoresist layer;
• removing one or more second portions of the photoresist layer that is remaining after forming the one or more MEMS actuators;
• immersing the device wafer in an acid-based etchant for a time duration in a range of 20 seconds to 30 seconds to remove an oxide from one or more portions of the device wafer;
• and
• forming, after immersing the device wafer in the acid-based etchant for the time duration, a cavity by bonding a circuitry wafer with a first side of the device wafer and bonding a capping wafer with a second side of the device wafer.

A method, comprising:

• forming a photoresist layer on a surface of a device wafer of a micro-electromechanical-system (MEMS) structure;
• removing one or more first portions of the photoresist layer to form a pattern in the photoresist layer;
• forming one or more MEMS actuators in the device wafer by etching the device wafer based on the pattern in the photoresist layer;
• removing one or more second portions of the photoresist layer that is remaining after forming the one or more MEMS actuators;
• wet etching, without performing an intervening preclean treatment after removing the one or more second portions of the photoresist layer, the device wafer for a time duration to remove an oxide;
• and
• forming, after wet etching the device wafer for the time duration, a cavity by bonding a complementary metal oxide semiconductor (CMOS) wafer with a first side of the device wafer and bonding a capping wafer with a second side of the device wafer.