Newest semiconductor chip manufacturing and further scaling down of CMOS devices push the limits of junction depths below the 10nm range, with a profile steepness of 1-2nm per decade. At such scale, the SIMS technique can be used to monitor in-depth distributions of dopants, proving that SIMS profiles can be measured with a depth resolution better than 1nm per decade.
Achieving sub-nm depth resolution with EXtreme Low Impact Energy SIMS
Recent innovations on the ion sources of the SC Ultra and IMS Wf have improved the primary beam density at very low impact energies, thereby giving access to sputter rates of 1nm/min for both Cs+ and O2+ @ 150eV. A wide range of accessible primary ions impact energies allows to select adequate analytical conditions in order to obtain a true in-depth concentration distribution. High dynamic range in every profile is a key element to high precision measurement.
One of the main advantages of the EXLIE recipes is to combine sub-nm depth resolution with an accurate near surface quantification, giving the true implanted dopant species distribution.
Shown above are low energy implantation profiles revealing real distribution within the first 10nm. As: 250eV - P: 200eV - B: 100eV.