Yarmoff Research

Surface Reactions in Semiconductor Processing Of particular technological importance are the chemical reactions that occur at solid surfaces during the processing of semiconductor wafers. Dry processes such as reactive ion etching (RIE) and chemical vapor deposition (CVD) are routinely employed in the manufacture of microelectronic devices. Although much is known about the conditions necessary for making device structures, the mechanistic details of the surface reactions that occur during these procedures are largely unknown. We employ surface science techniques to look at fundamental aspects of RIE and CVD. Semiconductor surfaces are studied after reaction with model gas-phase precursor species in UHV. A variety of surface analysis techniques are employed to probe the surfaces, both in our laboratory and at synchrotron radiation (SR) facilities. Systems are studied in the submonolayer regime, where the interaction between the bare substrate atoms and the reactant is quantified, and in the high exposure regime typical of a 'real' process. Both the geometric and electronic structures of a sample are probed, and the results are correlated into a detailed understanding of the properties of a system that is not available from the use of a single technique. Our future plans for semiconductor processing studies involve the use of energetic, rather than thermal, reactants.  The motivation here is to better understand the mechanisms involved in plasma processing in order to provide better control of the structures that are produced, with the ultimate goal being the reproducible fabrication of uniform nanoscale features.  We will use controlled molecular beams of fast halogen atoms and low energy beams of halogen ions to etch semiconductor surfaces.  We will then investigate the resulting surfaces with our array of surface chemical and structural probes.