Method for simulating the electrical behaviour of an integrated diode and corresponding computerized system

A method for designing an integrated circuit (IC) comprising a protection diode by simulating electrical behavior of the protection diode by an electrical device simulator, the method comprising:

• receiving parameters describing physical characteristics of the protection diode, the protection diode comprising at least a well having a first type of conductivity, a first active region having a second type of conductivity opposite from the first type and further comprising at least one second active region having the first type of conductivity, the first active region and the second active region forming an anode and a cathode of the diode;
• using a modelling tool to model a compact model of the protection diode in the electrical device simulator based on the received parameters, the modelling comprising:
• modelling a series resistance relating to the active regions and to a connection on the first active region and a connection on the second active region;
• modelling a PN junction of the protection diode;
• modelling a well resistance for positive values of a current passing through the diode using a conductivity modulation model;
• and
• modelling the well resistance for negative values of the current by a curve which increases from an initial resistance value corresponding to a zero value of current up to a plateau having a constant maximum value, wherein the modelling of the well resistance for positive values of the current using the conductivity modulation model and for negative values of the current using the curve reproduces the current voltage relationship of the protective diode better than obtained by modelling the well resistance only for positive values of the current using the conductivity modulation model;
• and
• designing the IC using the modelled protection diode.

An electrostatic discharge (ESD) protection device modelling tool comprising a processor and a tangible and non-transitory computer readable medium storing a program to be executed by the processor, the program having instructions for designing an integrated circuit comprising a protection diode, the instructions executing steps comprising:

• receiving parameters describing physical characteristics of the protection diode, the protection diode comprising at least a well having a first type of conductivity;
• modelling, based on the received parameters, a series resistance relating to at least a first active region having a second type of conductivity and at least one second active region having a first type of conductivity opposite the second type of conductivity;
• modelling, based on the received parameters, a PN junction of the protection diode;
• modelling a well resistance for positive values of a current passing through the protection diode using a conductivity modulation model;
• and
• modelling the well resistance for negative values of the current by a curve increasing from an initial resistance value corresponding to a zero value of current up to a plateau having a constant maximum value, wherein the modelling of the well resistance for positive values of the current using the conductivity modulation model and for negative values of the current using the curve reproduces the current voltage relationship of the protective diode better than obtained by modelling the well resistance only for positive values of the current using the conductivity modulation model.