Metallurgy structure for hybrid bonding

Abstract

A hybrid semiconductor structure having a mixed nanotwin (nt) structure, including a nt-<111> grain orientation and other oriented grains, e.g., <200> and/or <220> grains. Such mixed nanotwin stacks including <111>/(hkl), where hkl=220, 200, or 220/200, allow a selective etch to form nanometer level surface steps, thereby reducing the contact areas and providing a nanoscale surface roughness that is favorable for contact (high compression) and facilitate the local yielding and grain growth. That is, a low index <200><220> grains structure and a selective etch is used to form favorable bonding surface and improve bonding strength. Using the microstructure of Cu pads and a surface pretreatment process (prior to the bonding), the bonding quality will be improved and permit wider hybrid bonding process window. Further, the pad-to-pad variation will be reduced since the tailored grain growth during the post bonding annealing will make the post bonded microstructures more consistent.

Dependencies are inferred from the claim text.