Wafer bonding of silicon wafers covered with various surface layers

Studies dealing with the bonding behavior of silicon wafers coated with the rmal oxide, plasma-enhanced chemical vapor deposition (PE-CVD) oxide, PE-CV D oxynitride, PE-CVD nitride and low-pressure (LP) CVD nitride are presente d. The PE-CVD layers require a chemo-mechanical polishing (CMP) before bond ing to reduce the surface roughness. The bonding energies of the wafer pair s with different interface layers are similar to those of bonded hydrophili c silicon wafers. Infrared microscopy of patterned wafer pairs reveals inte rfaces which are almost free of bubbles. Presumably, the gas, which usually generates such interface bubbles, diffuses into the interface cavities. Th e tensile strengths of patterned wafer pairs including a PE-CVD oxide or a PE-CVD oxynitride interface layer are about twice as high as for patterned hydrophilic silicon wafer pairs. (C) 2000 Elsevier Science B.V. All rights reserved.