Pulsed ion beam surface analysis as a means of in situ real-time analysis of thin films during growth

Low-energy (5–15 keV) pulsed ion beam surface analysis comprises several different surface spectroscopies which possess the ability to provide a remarkably wide range of information directly relevant to the growth of single and multicomponent semiconductor, metal and metal-oxide thin films and layered structures. Ion beam methods have not however, been widely used as an in situ monitor of thin film growth because existing commercial instrumentation causes excessive film damage, physically conflicts with the deposition equipment, and requires a chamber pressure ~10~⁷-10~⁸ Torr, i.e., much lower than that associated with most deposition processes (K)”⁴ Torr). We have developed time-of-flight ion scattering and recoil spectroscopy (TOF-SARS) as a nondestructive, in situ, real-time probe of thin film composition and structure which does not physically interfere with the deposition process. Several TOF-SARS implementations are exceptionally surface specific, yet in a properly designed system can yield high-resolution data at ambient pressures well in excess of 10 mTorr (4–6 orders of magnitude higher than conventional surface analytic methods). Because of the exceptional surface specificity of these methods, TOF-SARS is ideally suited as a means of studying ultrathin layers and atomically abrupt interfaces. TOF-SARS instrumentation designed specifically for use as an in situ, real-time monitor of growth processes for single and multicomponent thin films and layered structures is described here. Representative data are shown for in situ analysis of Pb and Zr layers at room temperature and high vacuum, as well as under conditions appropriate to the growth of Pb(Zr_xTi₁-x)0$ (PZT) perovskite films on MgO and Ru0₂ substrates.