Method for forming through silicon via with wafer backside protection

A method comprising:

• exposing a passivation layer surrounding a bottom portion of a through silicon via (TSV) in a silicon substrate;
• forming an oxide layer over the passivation layer and a bottom surface of the silicon substrate;
• forming a silicon composite layer over the oxide layer, including over the bottom portion of the TSV and over the bottom surface of the silicon substrate;
• forming a hardmask layer over the silicon composite layer, including over the bottom portion of the TSV and over the bottom surface of the silicon substrate;
• removing a section of the silicon composite layer around the bottom portion of the TSV using the hardmask layer as a mask to expose sidewalls of the oxide layer;
• and
• removing the hardmask layer and the exposed sidewalls of the oxide layer to expose a contact for the bottom portion of the TSV.