Method for fabricating semiconductor device

A method for fabricating a semiconductor device, comprising:

• forming a bottom-electrode metal layer over a substrate;
• planarizing the bottom-electrode metal layer by a first thickness through a chemical mechanical polishing (CMP) process;
• etching the bottom-electrode metal layer by a second thickness through a dry etching process;
• forming a plurality of layers of a magnetic tunneling junction (MTJ) element over the bottom-electrode metal layer;
• forming a top electrode over the plurality of layers;
• and
• forming the MTJ element and a bottom electrode by etching the plurality of layers and the bottom-electrode metal layer using the top electrode an etch mask.

A method for fabricating a semiconductor device, comprising:

• forming a metal layer of a bottom electrode over a substrate;
• performing a first etching process to form the metal layer of a first thickness;
• performing a second etching process to form the metal layer of a second thickness;
• forming a plurality of layers of a magnetic tunneling junction (MTJ) element over the metal layer;
• forming a top electrode over the plurality of layers;
• and
• forming the MTJ element and a bottom electrode by etching the plurality of layers and the metal layer using the top electrode as an etch mask.