Application of RADSAFE to Model the Single Event Upset Response of a 0.25 $\mu$m CMOS SRAM

Abstract

The RADSAFE simulation framework is described and applied to model SEU in a 0.25 m CMOS 4 Mbit SRAM. For this circuit, the RADSAFE approach produces trends similar to those expected from classical rectangular parallelepiped models, but more closely represents the physical mechanisms responsible for SEU in the SRAM circuit.

Sub-LET Threshold SEE Cross Section Dependency With Ion Energy

“…The relationship between both can be described through the charge collection efficiency (CCE), representing the proportion of charge collected as a function of the path within the SRAM cell [17]. The different CCE factors can be considered through the definition of nested volumes with decreasing charge collection efficiencies as their distance to the sensitive drain increases [18], [19]. In the present work however, we consider that the probability of a certain energy deposition to lead to an SEU can be described through the device's heavy ion cross section as a function of deposited energy in the range in which direct ionization is the dominating effect (i.e.…”

Modeling Alpha and Neutron Induced Soft Errors in Static Random Access Memories

“…Ion strikes were simulated in TCAD by cylindrical charge filaments [6] at normal incidence. Those locations that resulted in SEU were identified as part of the overall ''sensitive region" and used to define the boundaries of the sensitive volumes (discussed in the next section).…”

“…The quantity of charge necessary to be collected at a given node (Qcrit) was determined through SPICE analysis and identified as being consistent with the device level simulations. At a supply voltage of 1.5V, Qcrit was determined to be 4.7 fC [6]. …”

“…The complete 3-dimensional solid model of the SRAM was generated from layout information and scanning electron microscope (SEM) cross-sections (Fig 3) using the ProcemlDevise software from Synopsys [6]. Each material within the real process is represented accurately, both from a spatial and compositional standpoint.…”

“…In this paper, we present the application of the Vanderbilt University RADSAFE concept [6]. The RADSAFE approach is focused on the end goal of developing a fully-automated, first-principles predictive set of tools that is based on the best available physics for radiation transport and microelectronic device performance.…”