In order to correctly perform circuit simulation, it is crucial that parasitic capacitances near devices are accurately extracted and are consistent with the SPICE models. Although 3D device simulation can be used to extract such parasitics, it is expensive and does not consider the effects of nearby interconnect and devices in a layout. Conventional rule-based layout parasitic extraction (LPE) tools which are used for interconnect extraction are inaccurate in modeling 3D effects near devices. In this thesis, we propose a methodology which combines 3D field solver based extraction with the ability to exclude specific parasitics from among the parameters in the SPICE model. We use this methodology to extract parasitics due to fringing fields and sidewall capacitances in MOSFETs, bipolar transistors and FinFETs in advanced process nodes. We analyze the importance of considering layout and process variables in device extraction by comparing with standard SPICE models. The results are validated by circuit simulation using predictive technology models and test chips. We also demonstrate the versatility of this flow by modeling the capacitance contributions of the raised gate profile in nanoscale FinFETs.