Practical Aspects of Forming Ultra-Shallow Junctions by Sub-keV Boron Implants

As the drive towards the production of 100 nm CMOS devices pick up speed, the practical aspect of transistor shallow junction formation, including a large menu of process integration issues, must now be solved in a short order. The most direct path to 50 nm junction depths is through the sub-keV boron implantation and rapid thermal annealing. The material aspects of the process integration centers on: (1) CMOS devices for shallow, highly-activated and abrupt junctions (involving the choice of ion species [B, BF, B10H14, BSi2, etc.], substrate materials [ Cz, Epi, SOI], anneal conditions [ramp rate, soak time, ambient gas], etc.) and (2) Defect-dopant interactions during annealing (including surface reactions of high concentration species [B, F], diffusion and carrier trapping by background and co-implanted species [C, 0, F, etc.]. Process data for atomic and electrical activity profiles as well as defect and interface structures will be presented to illustrate progress towards understanding these complex process interactions. A particular focus will be the effects of anneal ambient and rapid temperature rise times approaching the “pike” anneal ideal.