Recoil implantation method for ultrashallow p+/n junction formation

A recoil implantation technique is investigated for ultrashallow p+/n junction formation. In this method, a 3–35 nm thick B layer is deposited on the wafer by magnetron sputtering. Then a medium energy (10–40 keV) Ge implant drives the boron atoms into Si by means of ion beam mixing. The remainder of the boron film is chemically etched away prior to the annealing step. Sub-60 nm deep p+/n junctions with sheet resistance less than 1000 Ω/sq and test diodes with leakage current density below 2 nA/cm2 have been formed using this method.