Apparatus and method for the determination of SEU and SET disruptions in a circuit caused by ionizing particle strikes

An apparatus for determining the effect on a target test circuit or system when an ionizing particle strikes a region surrounding a drain of a transistor in an integrated circuit, the apparatus comprising:

• a. A computer system having at least one input device, at least one processor, a memory, at least one output device, and A TFIT interface program tool in the processor of the computer;
• b. Means for providing to the computer system, a description, by element, of transistors (NMOS and PMOS) of a target test cell or circuit (Spice netlist), the description comprising (among others, but not limited to) inverters, NOR and NAND gates, SRAMs, TRISTATEs, Flip-flops, Latches;
• c. Means for providing to the computer system, technology data of layout and geometries of the transistors to be modeled, including doping profiles and SPICE model cards;
• d. Means for providing to the computer system, a TCAD model for the cell equivalent of the target test cell or circuit;
• e. Means for providing in the TCAD model, an element called “current source” to represent an ionizing particle perturbation;
• f. Means for placing the current source element between the drain and a bulk of a struck transistor;
• g. Means for including in the TCAD model, a configuration and electrical states of non struck transistors of the target test cell or circuit to characterize the response of the struck transistor;
• h. Means for including in the TCAD model, characteristics of transistors and cells surrounding the struck transistor, to characterize the response of the struck transistor;
• i. Means for providing as inputs to a TFIT interface program tool, characteristics of the ionizing particle, characteristics of the ionizing particle trajectory and impact point, size of the transistor struck by the ionizing particle and characteristics (Spice netlist) of the circuit surrounding the struck transistor;
• j. Under control of the TFIT interface program tool, the computer system determining a value for the current source pseudo element from a SPICE simulation of the struck transistor neighborhood, the value representing a transient current pulse induced by an ionizing particle striking a transistor of the target test cell or circuit;
• k. The TFIT interface program tool causing the computer to apply the determined value for the current source to the struck node of the target test circuit or system to determine an effect of a strike by an ionizing particle on the target test circuit or system;
• and
• l. The computer system, under the control of the TFIT interface program tool, producing a report showing the effects on the struck transistors and the target test circuit of a strike by an ionizing particle, to predict behavior of complex MOS gates to SET, as well as the response of SRAM cells to SEU aggressions especially to neutrons

A computer implemented method for determining the effect on a target test cell or circuit when an ionizing particle strikes a region surrounding a drain of a transistor (called “the struck transistor”) in an integrated circuit, the method comprising the acts of:

• providing a description, by element, of the target test cell or circuit, including technology data of layout and geometries of transistors to be modeled, including doping profiles, SPICE model cards and SPICE netlists;
• providing a TCAD model for the NMOS and PMOS transistors of the cell equivalent used for the target test cell or circuit, including within the TCAD model, a configuration and electrical states of non struck transistors of the target test cell or circuit and characteristics of cells surrounding the struck transistor, to characterize the response of the target test cell or circuit;
• providing a TFIT interface program tool (TFIT), and inputs to TFIT including the TCAD model and a definition of an ionizing environment of interest, which, if the ionizing environment of interest is a light or heavy ion environment, includes characteristics of the ionizing particles comprising the particle's LET, ranges, impact locations and angle of incidence, and if the ionizing environment of interest is a neutron environment, includes a pointer to a neutron particle database;
• Including as additional inputs to the TFIT interface program, SPICE characteristics of the transistor struck by the ionizing particle and SPICE characteristics of the circuit surrounding the struck transistor;
• Under control of the TFIT interface program tool, using an element called “current source” to represent an ionizing particle perturbation, and placing the current source element between the drain and a bulk node of a struck transistor, modifying the SPICE netlists to account for the current source elements inserted,
• Under control of the TFIT interface program tool, determining a value for the current source element from a SPICE simulation of the struck transistor neighborhood, the value representing a transient current pulse induced by an ionizing particle striking a transistor of the target test cell or circuit;
• Under control of the TFIT interface program tool, applying the determined value for the current source to the struck node of the target test cell or circuit to determine an effect of a strike by an ionizing particle on the target test cell or circuit, and by computing the FIT in a neutron environment, and alternatinely, determining the SET or SER for one or more ionizing particles in a light or heavy ion environment;
• and
• producing by the TFIT interface program tool, a report showing the effects on the struck transistors and the target test circuit of a strike by an ionizing particle, to predict behavior of complex MOS gates to SET, as well as the response of SRAM cells to SEU aggressions.