Jun-Ichi Konno

Ashing of Ion-Implanted Resist Layer

The stripping method of high-dose ion-implanted resist layers was studied on the basis of the chemical structure of carbonized layers formed by ion implantation and that of residues remaining on the wafer surface after O2 plasma ashing. The chemical structure of the carbonized layer was observed with solid NMR and that of residues was analyzed with XPS. A decrease in the etching rate of the high-dose ion-implanted resist was caused by carbonization of polymers of the resist. Residues were mainly formed during O2 plasma ashing by chemical reaction between oxygen and implanted species, i.e., the main component of residues was oxide of the implanted species. On the basis of these results, to remove the high dose ion implanted resist without damage, we developed a two-step ashing process which was composed of H2 RIE and downstream ashing, and achieved the purpose.

Ion implantation change in the chemical structure of a resist

Abstract P + and Ar + implanted HPR-204 (base polymer is cresol novolak resin [1]) was studied. Carbonized resist layers formed during ion implantation were collected and analyzed by NMR (nuclear magnetic resonance). Implanted argon atoms only carbonize polymers. However, implanted phosphorous atoms also chemically react with polymers. Aromatic parts of the resist are influenced by ion implantation more easily than aliphatic parts. From NMR spectra of carbonized layers and triphenylphosphine, we confirmed that the methylene in the main chain of the novolak resin was substituted by a phosphorous atom connected with two phenyls in the carbonized layer of the P + implanted polymer. We also present models of the structure of aliphatic parts.

Protection of aluminum alloy films from after corrosion using H2O down stream ashing

While miniatuarization of semiconductors has enabled aluminum wiring pattern dimensions smaller and smaller, this has also given rise to problems such as stress migration and electromigration. The use of copper reportedly suppreses such migration.