Spacer assisted ion beam etching of spin torque magnetic random access memory

A method for etching a magnetic tunneling junction (MTJ) structure comprising:

• providing a stack of MTJ layers on a substrate comprising a bottom electrode on a said substrate, a pinned layer, a tunnel barrier layer, a free layer, a top electrode, and a hard mask layer in order on said bottom electrode;
• patterning said MTJ stack to form a MTJ device wherein sidewall damage is formed on sidewalls of said MTJ device;
• conformally depositing a dielectric spacer layer over said substrate and said MTJ device;
• etching away said dielectric spacer layer on horizontal surfaces of said substrate and said MTJ device wherein said dielectric spacer layer on sidewalls of said MTJ device is partially etched away wherein remaining said dielectric spacer layer on said sidewalls of said MTJ device covers said pinned layer and said bottom electrode and wherein remaining said dielectric spacer layer is removed from said free layer or is thinner on said free layer than on said pinned layer and said bottom electrode;
• and
• thereafter removing said sidewall damage from said free layer by applying an angle dependent ion beam etching (IBE) to said MTJ device wherein said pinned layer and said bottom electrode are protected from said physical etching by said dielectric spacer layer.

A method for etching a magnetic tunneling junction (MTJ) structure comprising:

• providing a stack of MTJ layers on a substrate comprising a bottom electrode on a said substrate, a pinned layer, a tunnel barrier layer, a free layer, a top electrode, and a hard mask layer in order on said bottom electrode;
• patterning said MTJ stack to form a MTJ device wherein sidewall damage is formed on sidewalls of said MTJ device;
• conformally depositing a dielectric spacer layer over said substrate and said MTJ device;
• etching away said dielectric spacer layer on horizontal surfaces of said substrate and said MTJ device wherein said dielectric spacer layer on sidewalls of said MTJ device is partially etched away wherein remaining said dielectric spacer layer on said sidewalls of said MTJ device covers said pinned layer and said bottom electrode and wherein remaining said dielectric spacer layer is removed from said free layer or is thinner on said free layer than on said pinned layer and said bottom electrode;
• and
• thereafter removing said sidewall damage from said free layer by applying horizontal physical etching to said MTJ device wherein said pinned layer and said bottom electrode are protected from said physical etching by said dielectric spacer layer.