THE PROFILE CONTROL OF n-TYPE DOPING IN LOW AND HIGH TEMPERATURE Si EPITAXY FOR HIGH FREQUENCY BIPOLAR TRANSISTORS

摘要

We report the control of the collector profile for high speed SiGe HBTs using As- or P-doped collectors grown at temperature 650-1050 °C using either silane- or dichlorosilane-based epitaxy at 40 torr. A strong As segregation towards the intrinsic cap layer was observed for both silane- and dichlorosilane-based epitaxy. Adding HC1 i.e. selective epitaxy reduces the As segregation slightly, however, it is still far from an abrupt profile. Furthermore, the segregation of arsenic was decreased in boron-doped cap layer. A fully controlled profile of As can be obtained at high temperature, 1050°C. Another solution to the collector profile problem is using P which has significantly lower segregation. However, this requires a low process temperature budget to prevent any out-diffusion of the P dopant atoms.