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/cm~(2) have been formed using this method.
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