Electrical aging behavioral modeling for reliability analyses of ionizing dose effects on an n-MOS simple current mirror

Abstract

Nowadays, a deterministic approach based on physics of failure is necessary to estimate the lifetime of integrated circuits. Therefore, the reliability analyses via electrical/aging simulations are performed during the design phase. Our previous works consisted in generating an aging behavioral model of a circuit in order to assess its degradation level and to predict its lifetime according to its mission profile. This paper presents obtained experimental results using our developed methodology to evaluate the influence of total ionizing dose effects on an n-MOS simple current mirror taking into account technological dispersions.

Introduction

In order to reduce design and test costs, the reliability analysis must be done as early as the design cycle of electronic circuits. Consequently, it must be integrated during the design phase. Design For Reliability (DFR) strategy consists in implementing a new design flow depicted in Fig. 1 [1]: a looping aging simulations phase which integrates, during the phase of design, the reliability analyses via electrical simulations is added to the classical design flow. Aging simulations aim to predict the impact of physical phenomena from elementary component to circuit electrical characteristics over an operating time.

In previous papers, we have presented methods for generation of aging behavioral model of a circuit in order to simulate its aging under operating conditions according to its mission profile [1], [2], and a simulation based method to predict lifetime dispersion due to technological dispersion [3]. However, the validity of simulation results depends on the validity of behavioral models at each abstraction level and degradation laws at transistor level. In this paper, we present a case study of aging simulation and lifetime dispersion prediction applied to dose effects of radiations on a simple circuit made of MOS transistors, and based on transistor level irradiation experiments.

The first part of this paper presents the construction of the aging model of transistors on the basis of experimental characterization of NMOS transistors under gamma ray irradiations. In the second part, the aging model is used to simulate the evolution of the electrical characteristics of a simple current mirror, and to evaluate the lifetime dispersion of this circuit.