Ion beam etching with gas treatment and pulsing

An apparatus for performing ion beam etching of a substrate, the apparatus comprising:

• an ion beam source chamber;
• a processing chamber coupled to the ion beam source chamber, wherein the processing chamber is configured to support a substrate located therein, wherein a magnetic random access memory (MRAM) stack includes one or more layers disposed on the substrate;
• a gas delivery system coupled to the processing chamber;
• and
• a controller configured to provide instructions to perform the following operations:
• generate an ion beam of an inert gas in the ion beam source chamber;
• apply the ion beam of the inert gas to the substrate in the processing chamber, wherein the ion beam etches the one or more layers of the MRAM stack on the substrate;
• and
• introduce a reactive gas through the gas delivery system and directly into the processing chamber towards the substrate.