Formation and control of box-shaped ultra-shallow junction using laser annealing and pre-amorphization implantation

A box-shaped doping profile is successfully formed by combining laser annealing (LA) process with pre-amorphization implantation (PAI) technique. The junction depths of box-shaped profiles are precisely controlled by changing PAI energy which in turn changes the melting thickness of silicon layer regardless of arsenic and boron dopant species. The material properties which are related to ultra-shallow junction for sub-100 nm CMOS device application, such as transient enhanced diffusion (TED) and end-of-range defect density are investigated by secondary ion mass spectrometry and transmission electron microscopy. TED phenomena of furnace annealed, rapid thermal annealed (RTA), and LA samples are also compared. Impurity doping profiles annealed by laser do not show significant TED even after taking additional specific RTA step. Sheet resistance characteristics with various implantation conditions and annealing conditions are examined. Large process window margin is achieved by the proposed PAI combined with subsequent multi-shot LA process.