Manufacturing method of magnetic random access memory cell

A manufacturing method of a magnetic random access memory (MRAM) cell, comprising:

• forming a magnetic tunnel junction (MTJ) film stack on an insulation layer;
• forming an aluminum mask layer on the MTJ film stack;
• forming a hard mask layer on the aluminum mask layer;
• performing an ion beam etching (IBE) process with the aluminum mask layer and the hard mask layer as a mask, wherein the MTJ film stack is patterned to be a patterned MTJ film stack by the IBE process, and at least a part of the aluminum mask layer is bombarded by the IBE process for forming an aluminum film on a sidewall of the patterned MTJ film stack;
• performing an oxidation treatment, wherein the aluminum film is oxidized to be an aluminum oxide protection layer on the sidewall of the patterned MTJ film stack by the oxidation treatment;
• forming an interlayer dielectric covering the aluminum oxide protection layer and the patterned MTJ film stack;
• and
• forming a connection structure penetrating the interlayer dielectric above the patterned MTJ film stack, wherein the connection structure is electrically connected to a topmost portion of the patterned MTJ film stack, and the aluminum mask layer is completely removed before the step of forming the connection structure.