Application of pure aluminum to prevent pad corrosion

A method of fabricating bonding pads on a semiconductor device formed on a semiconductor wafer, said semiconductor device including a substrate, said method comprising the steps of:

• depositing a first metallization layer over said substrate, forming an electrical interface between said bonding pad and electronic components and devices that supply stimuli to or extract electrical responses from said semiconductor device;
• depositing a dielectric layer over said metallization layer,
• forming a basis for creating a via opening;
• etching a via hole through said dielectric, establishing a first phase of an electrical path between said metallization layer over said substrate and top level metal of said bonding pad;
• depositing a second metal layer over the surface of said layer of dielectric and in said via hole, creating top level metal layer of said bonding pad, completing an electrical path between said metallization layer over said substrate and top level metal of said bonding pad, said second level metal layer comprising an aluminum-copper alloy;
• depositing a layer of pure aluminum over the surface of said top level metal layer, preventing surface pitting and surface corrosion of the surface of said top level metal;
• forming an anti-reflective coating over the surface of said layer of pure aluminum;
• depositing a passivation layer over the surface of said anti reflective coating, protecting and electrically isolating said layer of top level metal;
• and
• etching an opening through said passivation layer, further through said anti-reflective coating down to the surface of said layer of pure aluminum, creating an electrical point of contact for said semiconductor device.

A method of fabricating bonding pads on a semiconductor device formed on a semiconductor wafer, said semiconductor device including a substrate, said method comprising the steps of:

• depositing a first metallization layer over said substrate;
• depositing a dielectric layer over said metallization layer;
• masking a portion of said dielectric layer in preparation for a first etching step;
• etching the dielectric layer utilizing the dielectric mask as a mask for the dielectric layer;
• depositing a second metallization layer overlaying said dielectric layer with the inclusion of the openings etched into said dielectric layer, said second level metallization layer comprising an aluminum-copper alloy;
• depositing a layer of pure aluminum overlaying said second metallization layer;
• forming a anti-reflective coating over the surface of said layer of pure aluminum;
• depositing a passivation layer over the surface of said anti-reflective coating;
• masking a portion of said passivation layer in preparation for a second etching step;
• and
• etching said passivation layer, further etching through the anti-reflective coating to the surface of said layer of pure aluminum, forming an exposed region of pure aluminum, forming a bond region of pure aluminum.