IN-SITU ANALYSIS OF THIN-FILM DEPOSITION PROCESS USING TIME-OF-FLIGHT(TOF) ION-BEAM ANALYSIS-METHODS

The use of non-destructive, in situ methods for the characterization o f thin film growth phenomena is the key both to obtaining a better und erstanding of thin film growth processes and to the development of mor e reliable deposition procedures, especially for complex layered struc tures involving multi-phase materials. However, surface characterizati on methods that utilize tither electrons (e.g. AES or XPS) or low ener gy ions (SIMS) for the signal require an ultra-high vacuum (UHV) envir onment and utilize instrumentation which obstructs line of sight acces s to the substrate. These methods are therefore incompatible with line of sight deposition methods and thin film deposition processes which introduce gas, either as an intrinsic part of the deposition procedure or in order to produce the desired composition. We have developed a m eans of differentially pumping both the ion beam source and detectors of a TOF ion beam surface analysis spectrometer that does not interfer e with the deposition process and permits compositional and structural analysis of the growing film in the present system, at pressures up t o several mTorr. Higher pressures are feasible with modified source-de tector geometry. In order to quantify the sensitivity of Ion Scatterin g Spectroscopy (ISS) and Direct Recoil Spectroscopy (DRS), we have mea sured the signal intensity for stabilized clean metals in a variety of gas environments as a function of the ambient gas species and pressur e, and ion beam species and kinetic energy. The results are: interpret ed in terms of collision cross sections which are compared with known gas phase scattering data and provide an apriori basis for the evaluat ion of time-of-flight ion scattering and recoil spectroscopies (ToF-IS ARS) for various industrial processing environments which involve both inert and reactive gases. The cross section data for primary ion-gas molecule and recoiled atom-gas molecule interactions are also provided , from which the maximum operating pressure in any experimental config uration can be obtained.