CHARACTERIZATION OF SI-SI BONDING BY WRIGHT ETCHING

A new silicon-silicon bond characterization technique has been demonst rated. Defect decoration etches can be used to detect weaknesses at th e bond interface, and the Wright etch was found to be a particularly s uitable etch. Defects at the bond interface are decorated in the cleav ed cross section of bonded wafers, and the appearance of the etch figu res is a qualitative indicator of the bond completeness. The clearest results are seen when the anneal takes place at or above about 1000-de grees-C. This technique also decorates the surface of a bonded and thi nned wafer and can highlight the presence of small voids, undetectable by IR transmission, that are present at the bond interface. The techn ique is mainly qualitative in nature but can also give semiquantitativ e information. In particular, we have estimated an activation energy o f about 6.1 eV for the mass transport portion during the bonding proce ss for Si-Si bonds.