In this paper, we propose a new extraction method of radiation-induced oxide-trap density (/spl Delta/N/sub ot/), called Oxide-Trap based on Charge-Pumping (OTCP). This part presents the HF-OTCP method, which relies on high-frequency (HF) standard charge-pumping measurement. By applying an HF gate voltage signal, we avoid the border-trap effect in CP current (I/sub cp/) measurements. Hence, I/sub cp/ will be only due to the interface-trap contribution. We establish, using the HF-OTCP method, that /spl Delta/N/sub ot/ is only dependent on /spl Delta/V/sub th/ (threshold voltage shift) and /spl Delta/I/sub cpm/ (increase of maximum CP current), where /spl Delta/I/sub cpm/ is caused by radiation-induced interface-trap increase (/spl Delta/N/sub it/). We also clearly show that /spl Delta/V/sub th/ and /spl Delta/I/sub cpm/ can be obtained from lateral and vertical shifts of Elliot's charge-pumping curves, respectively. Thus, this new procedure allows the determination of /spl Delta/N/sub ot/ without needing any additional techniques. Finally, this procedure can be used in rapid hardness assurance test to evaluate both radiation-induced oxide and interface traps.

A new oxide-trap based on charge-pumping (OTCP) extraction method for irradiated MOSFET devices: part I (high frequencies)

The peculiar behavior observed in the TDE (Total Dose Experiment) on board the KITSAT-1 is identified as the thermal effect due to the change in the eclipse rate of the satellite. Similar behavior is seen in the laboratory experiment as the temperature of the RADFET, the TDE sensor, is varied from 20/spl deg/C to 80/spl deg/C while it is being irradiated with a Co/sup 60/ /spl gamma/-ray source. The present study focuses on the modeling effort of separating the radiation and thermal effects from the complicated data in which these two effects are simultaneously present. We derive the device parameters from the non-thermal irradiation data, and then include thermal annealing and conversion of oxide charges to estimate the oxide trap and interface state charges in the case of thermal variation. The model fits the experimental data quite successfully, which will enable us to estimate the pure radiation effect on the TDE experienced in space.

Analysis of anomalous TDE data on-board the KITSAT-1

A system and method for manipulating a netlist, at the time that the netlist is being created, to permit measurement of current flow through a net, or combination of nets, of a sub-circuit during a subsequent simulation process, the manipulation of the netlist including identifying nets through which current flow is to be measured, creating “artificial” nets for the identified nets, substituting the “artificial” nets for the identified nets in the netlist file, and connecting a power supply between the artificial net and the identified net for which it has been substituted.

Method and system for creating a netlist allowing current measurement through a sub-circuit

A hierarchical method for total dose effects simulation of large mixed signal circuits using VHDL-AMS is described. Simplified behavioral models (or macro-models) of small sub-circuits replace SPICE-level circuits. The behavioral models describe the electrical circuit behavior and its dependence on the radiation dose. The behavioral models of sub-circuits can be assembled into complex mixed signal circuits. As a result, the computational cost is reduced significantly compared to conventional SPICE-based methods. The VHDL-AMS method also allows bias-dependent total dose degradation to be coupled to the circuit and operational conditions. Simulation accuracy remains sufficient to determine critical performance metrics of the circuit as the circuit performance degrades with dose.

VHDL-AMS Modeling of Total Ionizing Dose Radiation Effects on CMOS Mixed Signal Circuits

A method and device for automatically generating load circuits for a netlist. A computer system having a schematic for a circuit is used to create a netlist. While constructing the netlist, instances are checked for directives. The directives indicate that the instance should be tracked as a load circuit. For the instances having such a directive, their nets are flagged and the hierarchal portion of the circuit attached to the flagged nets is flattened. The resulting flat circuit replaces the instance in the netlist as a load circuit.

Automated load determination for partitioned simulation

In this paper we describe a simulator which can be used to study the effects on circuit behavior of two radiation phenomena: single event upset (SEU) and total-dose radiation effects. Using this simulator the user can predict the error rate in large circuits due to single event upset. The error rate model described here uses a well established methodology, but for the first time a different choice is made on picking up the sensitive nodes, enabling a quick prediction even for very complex circuits. The simulator predicts circuit behavior after total-dose irradiation using as inputs: the dose rate and the total dose. Parameter sets that characterize the transistor response to radiation. And the circuit netlist. The total-dose simulator is based on physical models of the changes in the MOSFET caused by radiation. We quantify the degradation of each MOSFET in a circuit with two parameters and determine the change in the MOSFET characteristics-from preirradiation MOSFET data. Using the "irradiated" MOSFET parameters. We can simulate circuit behavior using an ordinary circuit simulator such as SPICE. With this simulator, one can study how resistant a circuit is to changes due to irradiation and design circuits to be functionally radiation "hard" The "double-kink" in the MOSFET subthreshold region due to the parasitic effect of the edge transistors can be simulated and the user is advised when leakage current is unacceptably large. The speed degradation of a ring oscillator was simulated and the results compared with actual measured data. >

A complete radiation reliability software simulator

Using RAD, a new module of Berkeley Reliability Tools (BERT), as a tool, users can design circuits to be radiation hard and characterize circuit behavior in environments where radiation is present Previous simulators could not provide circuit output waveforms after radiation because it was difficult to simulate the effect of radiation on a circuit in operation (AC bias condition) and because radiation affected MOSFETs of different processes in different ways We have dealt with these problems and for the first time, successfully provided "SPICE-like" simulation results >

Simulating total-dose radiation effects on circuit behavior

Using RAD, a new module of Berkeley Reliability Tools (BERT), as a tool, users can design circuits to be radiation hard and characterize circuit behavior in environments where radiation is present. Previous simulators could not provide circuit output waveforms after radiation because it was difficult to simulate the effect of radiation on a circuit in operation (AC bias condition) and because radiation affected MOSFETs of different processes in different ways. We have dealt with these problems and for the first time, successfully provided "SPICE-like" simulation results.<<ETX>>

G. Lum

Papers

A complete radiation reliability software simulator

Simulating total-dose radiation effects on circuit behavior

Simulating total dose radiation effects on circuit behavior