Defects Induced by Deep Preamorphization and Their Effects on Metal Oxide Semiconductor Device Characteristics

The crystalline quality of deeply preamorphized and recrystallized Si layers has been studied for application to channel preamorphization. Deep preamorphization by 300 keV Si 2+ and 150 keV Si + implantations induces spanning dislocations in addition to end-of-range defects, while relatively shallow preamorphization by 150 keV Si + implantation results only in the generation of end-of-range defects. Deep preamorphization causes large leakage currents in junction diodes because of spanning dislocation generation. It does not degrade gate oxide quality as long as amorphous layers that extend to the surface are created. Relatively shallow (∼0.3 μm) preamorphization does not degrade the leakage characteristics of junction diodes if the end-of-range defects are not located in the depletion layers. It is therefore effective to adopt both relativley shallow preamorphization and shallow source/drain junctions. Otherwise, deep preamorphization by low-temperature Si implantation is effective.