Nanoscale elemental imaging of semiconductor materials using focused ion beam secondary ion mass spectrometry

Abstract

The semiconductor industry demands elemental information from ever smaller regions. The sensitivity of secondary ion mass spectrometry, coupled with the lateral resolution of a focused ion beam, can provide nanoscale elemental data that are competitive with that from other analytical techniques. Ion images of the sidewalls in repetitive semiconductor features tilted to present a large surface area have shown boron contamination after an etch process. The boron is removed by a specific cleaning step. Spot defect analysis was enhanced by the use of mass spectra that provide information on a range of elements before the defect is removed by sputtering. Ion implanted samples were analyzed in cross section and the implant shape detected. Summation of the secondary ion counts in the implant cross section over a few micrometers resulted in detection limits below 0.1 at. %. Implantation profiles have been detected for Al, Cr, Na, Li, and K without the aid of secondary ion enhancing species, such as oxygen or cesium.