Nonconventional flash annealing on shallow indium implants in silicon

Abstract

The diffusion behavior and the electrical characteristics of indium doped layers in silicon were studied. Indium was implanted in silicon at energies of 70 and 25 keV to doses of 5.8 and 3×1014, respectively. The implants were performed both in amorphous and crystalline silicon. The implants were submitted to a combination of thermal annealing, RTA, and flash annealing to regrow the implanted layers and activate the dopant. Four point probe sheet resistance measurements and Hall effect measurements were carried out to test the electrical properties of the implanted layers. The atomic concentration profiles were assessed using secondary ion mass spectrometry. A drastic increase in the dopant activation was observed following co-implanting with carbon. Moreover, the carbon presence inhibits the indium diffusion and segregation in damaged areas. The preamorphizing treatment affects the indium diffusion in two ways. For low thermal budget anneals the diffusion is suppressed, conversely the diffusion is enhanced under severe annealing conditions.