Process interactions between low-energy ion implantation and rapid-thermal annealing for optimized ultrashallow junction formation

The shallow doping requirements for the next 2-3 device generations can be satisfied by a combination of low-energy ion implantation and rapid-thermal anneal. However, the differing requirements of distinct types of devices preclude the definition of a single optimized process. To tailor the junction properties according to device type and geometry, requires an understanding of the effects of process parameters in both implant and anneal steps. In describing the interactions and mechanisms behind this optimization, a number of tradeoffs are highlighted: (i) The choice of implant energy and dose may be traded off against the anneal time-temperature profile. (ii) The benefits of preamorphization to reduce ion channeling are offset by the detrimental increase in transient-enhanced diffusion and dopant segregation, (iii) The use of oxygen in the anneal ambient is discussed in terms of its effects on diffusion versus dopant loss at the surface. (C) 2000 American Vacuum Society. [S0734-211X(00)00401-2].