Relating statistical MOSFET model parameter variabilities to IC manufacturing process fluctuations enabling realistic worst case design

Abstract

Abstruct-The implementation of a viable statistical circuit design methodology requiring detailed knowledge of the variabilities of, and correlations among, the circuit simulator model parameters utilized by designers, and the determination of the important relationships between these CAD model parameter variabilities and the process variabilities causing them is presented. This work addresses the above requirements by detailing a new framework which was adopted for a 2-pm CMOS technology to enable realistic statistical circuit performance prediction prior to manufacture. Issues relating to MOSFET modeling, the derivation of fast "direct" parameter extraction methodologies suitable for rapid parameter generation, the employment of multivariate statistical techniques to analyze statistical parametric data, and the l i n g of the CAD model parameter variations to variabilities in process quantities are discussed. In this approach the correlated set of model parameters is reduced to a smaller and more manageable set of uncorrelated process-related factors. The ensuing construction and validation of realistic statistical circuit performance procedures is also discussed. Comparisons between measured and simulated variabilities of device characteristics is utilized to demonstrate the accuracy of the techniques described. The advantages of the proposed approach over more traditional "worst case" design methodologies are demonstrated.

Constraint-Based Layout-Driven Sizing of Analog Circuits

“…For example, the BSIM3 model for CMOS devices [LJX + ] has 16 important process parameters [PDML94,MI92]. It is worth noting that the effect of the fabrication process on geometric properties, such as the effective channel width and length of CMOS devices, is normally considered in the electrical models with suitable relations and process parameters.…”

Industrial Demands on Process and Device Simulation

“…Turning from the single device to the circuit, hot topics are • circuit reliability [14] • parasitics extraction for large circuits with realistic non-rectangular interconnect geometry [15] • worst case / circuit yield simulation [16]. For the single devices we mentioned modeling problems where we expect solutions from academia.…”

Design of electronic systems based on functional capability

“…(2) Which aspects of performance are most likely to fail to meet their specification? (3) Which are the key components in determining whether the design is capable? (4) How should the component values and tolerances be adjusted to reach the desired level of capability?…”