Effect of Millisecond Annealing Temperature of Ni_1-xPt_x Si Formation on Leakage Current Characteristics of Static Random- Access Memory Cells

The importance of optimizing the millisecond annealing (MSA) temperature for Pt-doped NiSi (Ni_1-xPt_xSi) contact formation was highlighted by implementing and characterizing the Ni_1-x Pt_xSi films in the static random-access memory (SRAM) cells fabricated with a 28-nm design rule. MSA at 750 °C-900 °C effectively reduced the junction leakage current compared to that with the conventional rapid thermal annealing, because of its efficient suppression of Ni diffusion in the junction region. Moreover, with an increase in the MSA temperature, the beneficial effects of maintaining a low junction leakage, such as interface flattening and grain size increase, were observed. However, the increase in the MSA temperature deteriorated the statistical distribution of the standby leakage current of the SRAM cells by producing more encroachment and spiking defects; this was attributed to the build-up of a high initial film stress and large stress relaxation during the subsequent back-end processes.