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“Integration of Technology-Based Design Systems for VLSI Circuits”
by Chung-Ping Wan
February 1990
Integration of technology-based design systems is strongly needed for the manufacturing of very-large-scale integrated circuits. The computer-aided design program PARGEN which provides accurate and efficient interface between the device simulator PISCES-IIB and the circuit simulator SPICE-3C1 in the technology-based design system is described. Algorithms to calculate parameter values for the built-in MOSFET and MESFET models have been developed and incorporated into this interface program. Only six device simulation results are required to extract a complete set of the popular Level-2 MOSFET model parameters and four device simulation results are needed for the MESFET model in the circuit simulator. This interface program, together with the process simulator, device simulator, and circuit simulator, form an integrated simulation environment for computer-integrated manufacturing of microelectronic chips. Such an integrated simulation environment greatly facilitates the designers to examine just how a microscope fabrication variable, such as the implantation dose, affects final device and circuit performance and product yield. A methodology for efficient circuit modeling and simulation in the integrated simulation environment is also described. A subset of circuit-level sensitive parameters which have large effects on simulated transistor output characteristics is used in this methodology. The sensitive model parameters are identified through a sensitivity analysis. This methodology has been applied to the temperature dependence modeling of the BSIM (Berkeley short-channel IGFET model) for MOS transistors in the circuit simulators. Updating of model parameter values for the sensitive parameter subset is performed prior to circuit simulation at each given temperature. For a 1.2-mm CMOS fabrication process, the sensitive parameter subset for temperature effects consists of only eight out of the sixty-seven BSIM parameters. Circuit simulation results using this sensitive model parameter subset approach agree with experimental data on transistor output characteristics, inverter transfer characteristics, and oscillation frequency of a 31-stage ring oscillator.