Quantitative high-resolution imaging with sputter-initiated resonance ionization spectroscopy

The demand for submicron lateral analysis, as a result of decreasing materi al size, has been met by the development of liquid metal ion gun (LMIG) sou rces capable of achieving spot sizes less than 50 nm. The trade-off, howeve r, is the reduction in ion beam current at the sample. Therefore, highly se nsitive detection techniques are required. Our technique, sputter-initiated resonance ionization spectroscopy (SIRIS), incorporates resonant ionizatio n of sputtered neutral particles with time-of-fight mass detection. The two major advantages this approach has over conventional secondary ion mass sp ectrometry are that analysis of neutrals generally increases the detection efficiency by at least two orders of magnitude, and that resonance ionizati on nearly eliminates mass interferences. Additionally, analysis of neutrals substantially removes matrix effects, which is crucial for quantitative su rface analysis. Sputtering is achieved with a gallium LMIG, a mass-filtered microbeam ion gun, and a mass-filtered low-energy sputtering ion gun. Subm icron lateral resolution and few nanometer depth resolution have been obtai ned by eroding the sample with the low-energy ion gun while analyzing with the LMIG. In our presentation, we will describe the SIRIS. technique and it s dynamic range for quantitative analysis and imaging capabilities as they pertain to semiconductor research. In particular, Ge and B depth profiles o n near 1 mu m spot size and Cu trace element images obtained from Cd precip itates in CdZnTe films will be presented. (C) 1999 American Vacuum Society. [S0734-2101(99)01904-1].