1μm Pitch direct hybrid bonding with <300nm wafer-to-wafer overlay accuracy

Copper/oxide hybrid bonding process has been extensively studied these past years as a key enabler for 3D high density application with top and bottom tier interconnection pitch below 10μm. Since 2015 hybrid bonding process robustness has been confirmed on complete electrical test vehicles [1,2] as well as commercial products [3] integrating copper to copper interconnection pitchs close to 6μm. To our knowledge, no results have been shown today demonstrating sub-1.5μm pitch copper hybrid bonding feasibility.