Papers by Author: M.M. Frank

Abstract: This paper summarizes the process development of TiN barrier etching in presence of copper, for a thick copper level in BICMOS technology. In an industrial context, we have chosen to use a SC1 chemistry in a spin etch single wafer tool. The SC1 composition and therefore the pH level allows - the barrier to be etched with no metallic residues, ( if not clear this can be a source for shorts) - control of the selectivity between copper and TiN - control of lateral etching under copper lines, the possible source of open chains by W attack during TiN etch. The electrical results show a robust process according to current specifications, in terms of leakage and via resistance with a fresh chemistry approach. In fact, the recirculation of SC1 is not possible due to substantial concentration changes during processing, high evaporation rate of Ammonia and high decomposition rate of Peroxide in the presence of copper on surface wafer.

Abstract: In this study, we used an SEZ single-wafer spin-processor to develop a single backside cleaning solution able to remove any metallic or exotic contaminants by etching a few angstroms of the wafer backside, whatever its coating (no coating, Si3N4 or SiO2). An H2O:H2O2:H2SO4:HF mixture was selected because it allowed independent control of the etch rate on the 3 materials of interest, without roughening to much the silicon surface. Chemistry efficiency was then checked on wafers intentionally contaminated with various metals, and on “production wafers” contaminated during exotic materials deposition or classical copper processes.

Abstract: We review the impact of semiconductor surface preparation on the performance of metal-oxidesemiconductor field-effect transistor (MOSFET) gate stacks. We discuss high-permittivity dielectrics such as hafnium oxide and aluminum oxide on silicon and on the high carrier mobility substrate germanium. On Si, scaling of the gate stack is the prime concern. On Ge, fundamental issues of chemical and electrical passivation need to be resolved. Surface treatments considered include oxidation, nitridation, hydrogenation, chlorination, and organic functionalization.