Accuracy of doping and process optimization for 0.18 μm PMOS technology

CMOS device sensitivity to process variation is becoming increasingly important as devices are scaled to smaller sizes. As a result, there is a growing demand for ion implantation and annealing tools to increase accuracy and repeatability. In this work, the sensitivity of devices´ electrical response to energy and dose deviation in the source/drain extension (SDE) implant is demonstrated for PMOS transistors with a variety of printed gate lengths from 0.10 μm to 1.0 μm. The measured changes in electrical parameters such as the threshold voltage (V_t), leakage current (I_off), saturation current (I_on) and transconductance (G_m) as a function of the controlled variation of boron implants (energy and dose) show high sensitivity of these parameters to process variation for the smaller printed gate sizes gate sizes. However, for larger gates sizes (0.3 to 1 μm) a negligible device variation was observed. SIMS profiles and four-point probe data are used to relate the device response to junction depth and sheet resistance. International SEMATECH´s process for 180 nm node PMOS transistors was used for this study. The energy and dose of the SDE was varied around the baseline with an Applied Materials xRLEAPQ™ ion implanter (a Quantum™ LEAP beamline mated to Applied´s xR wafer handling). The required energy and dose accuracy of the ion implanter tool will be extracted from the device.