Chemical mechanical planarization with overburden mask

A planarization method, comprising:

• depositing a mask material on top of an overburden layer on a semiconductor wafer;
• planarizing the mask material to remove the mask material from up areas of the overburden layer to expose the overburden layer without removing the mask material from down areas;
• wet etching the exposed overburden layer leaving a thickness over an underlying layer;
• wet etching the mask material to remove the mask material from the down areas;
• and
• performing a touch up planarization to further improve a final planarity, obtain a defect free, smooth surface and expose the underlying layer.