Reaction of carbonyl- and nitrogen-containing molecules on Si(100) and fluxless solder re-flow on polycrystalline Cu surfaces.

摘要

The surface thermal chemical reactions of Si(100) with small organic molecules have been investigated, as well as the wetting characteristics of Pb/Sn (60/40) solder on Cu surfaces. Acetone, acetaldehyde, and biacetyl were absorbed and thermally decomposed in order to study the reaction of carbonyl-containing organic molecules on Si(100). Thermal reactions of 1,1-dimethylhydrazine and formamide on Si(100) were also studied based on the potential of these molecules to form ;The results show that acetone, acetaldehyde, and biacetyl bind to Si(100) through the carbonyl and across the Si dimer units, forming a di-;1,1-Dimethylhydrazine (DMH) adsorbs intact, binding the two nitrogens across the Si(100) dimer bond. DMH thermally decomposes on Si(100) producing SiC, ;Finally, the re-flow characteristics of Pb/Sn (60%/40%) were studied on polycrystalline Cu surfaces using environmental scanning electron microscopy (ESEM). At 570 K, alloys of Cu and Sn develop by diffusion, growing away from the liquid solder front. Liquid Pb/Sn then wetted the alloy as opposed to wetting the Cu surface directly. Temperature dependence of the wetting action indicates the process is highly activated, limited by the diffusion rate of Sn through Cu.