A molecular beam mass spectrometer for plasma jet chemical vapor deposition reactor diagnostics

Summary form only given. Direct current (DC) plasma jets (also known as arcjets) are a particular form of high density, low pressure plasma source that produce a high velocity (5-10 km/sec) plasma stream (20-30% dissociation fraction, n/sub e/-10/sup 13/ cm/sup -3/) with low energy ions (∼1 eV). The plasma jet provides large convective fluxes of chemically reactive radical species, in super-equilibrium concentrations, that can be used for materials deposition, reactive etching, and plasma cleaning. To elucidate the kinetics of these processes, it is necessary to identify key radical species and measure their populations. For this task, molecular beam mass spectrometry is employed. A sample of the plasma jet plume is taken through a hole in the substrate on which the flowing plasma stagnates. A differentially pumped molecular beam forming system ensures that the sample is representative of the plasma chemistry. The symmetry of the plasma jet plume allows spatial maps to be made of the reactive species impinging on the substrate. Results are presented for a representative plasma jet process.