Method to eliminate top metal corner shaping during bottom metal patterning for MIM capacitors via plasma ashing and hard masking technique

A method for fabricating a metal-insulator-metal capacitor comprising:

• providing an insulating layer overlying a semiconductor substrate;
• depositing a first metal layer over said insulating layer;
• depositing a capacitor dielectric layer overlying said first metal layer;
• depositing a second metal layer overlying said capacitor dielectric layer;
• depositing a hard mask layer overlying said second metal layer;
• forming a first photoresist mask overlying said hard mask layer;
• patterning said hard mask layer, said second metal layer, said capacitor dielectric layer, and said first metal layer using said first photoresist mask as an etching mask to form a metal stack whereby patterned said first metal layer forms a bottom electrode of said capacitor;
• ashing away a portion of said first photoresist mask to form a second photoresist mask narrower than said first photoresist mask;
• patterning said hard mask layer using said second photoresist mask as an etching mask;
• removing said second photoresist mask;
• and
• patterning said second metal layer using said hard mask layer as an etching mask whereby said second metal layer forms a top electrode of said capacitor to complete fabrication of said metal-insulator-metal capacitor.

A method for fabricating a metal-insulator-metal capacitor comprising:

• providing an insulating layer overlying a semiconductor substrate;
• depositing a first barrier metal layer over said insulating layer;
• depositing a first metal layer over said barrier metal layer;
• depositing a capacitor dielectric layer overlying said first metal layer;
• depositing a second metal layer overlying said capacitor dielectric layer;
• depositing a second barrier metal layer overlying said second metal layer;
• depositing a hard mask layer overlying said second barrier metal layer;
• forming a first photoresist mask overlying said hard mask layer;
• patterning said hard mask layer, said second barrier metal layer, said second metal layer, said capacitor dielectric layer, said first metal layer, and said first barrier metal layer using said first photoresist mask as an etching mask to form a metal stack whereby patterned said first metal layer forms a bottom electrode of said capacitor;
• ashing away a portion of said first photoresist mask to form a second photoresist mask narrower than said first photoresist mask;
• patterning said hard mask layer using said second photoresist mask as an etching mask;
• removing said second photoresist mask;
• and
• patterning said second metal layer using said hard mask layer as an etching mask whereby said second metal layer forms a top electrode of said capacitor to complete fabrication of said metal-insulator-metal capacitor.