DOPANT ACTIVATION AND HALL-MOBILITY IN B-IMPLANTED AND AS-IMPLANTED POLYSILICON FILMS AFTER RAPID OR CONVENTIONAL THERMAL ANNEALING

We investigate the electrical properties of polycrystalline silicon films implanted with boron or arsenic ions at doses 4 x 10(14), 8 x 10(14) and 5 x 10(15) cm-2. After ion implantation, a rapid thermal annealing (RTA) or a conventional thermal annealing (CTA) was performed to activate the dopant. A comparison between the two types of annealed layer is made by performing Hall measurements. We find that RTA improves the electrical properties of the polycrystalline silicon layers. Moreover, the B-implanted films have the largest dopant activation and mobility. The density of trapping centres at grain boundaries (GBs) is derived from electrical measurements. We find that it depends strongly on the implantation dose and slightly on the annealing conditions except for the CTA As-implanted films in which it decreases due to As segregation at GBs.