DEPTH PROFILE ANALYSIS OF ALUMINUM METALLIZATION IN MICROELECTRONICS - OPTIMIZATION OF DEPTH RESOLUTION

Depth profiling of aluminium metallization in microelectronics devices by Auger or SIMS analysis is impeded by the severe sputter-induced roughening which causes a serious loss in depth resolution. This paper discusses strategies to avoid this deteriorating effect: optimization of the bombardment angle, sample rotation during sputtering and the use of heavy or reactive ions. The best depth resolutions were achieved by sputtering with normal incidence 15 keV O2+ ions. In this case, an interface width of 12 nm was measured for a film of 1-mu-m thickness. This is an improvement by more than a factor of 10 compared to the extremely poor depth resolution of 160 nm resulting from routine analysis parameters (Ar+ ions incident at 55-degrees).