National Semiconductor Corporation

William S Belcher

Jiankang Bu

David Courtney Parker

A system and method are disclosed for providing an electrically programmable read only memory (EPROM) in which each memory cell comprises an NMOS select transistor with a thick gate oxide and a PMOS breakdown transistor with a thin gate oxide. The source of the NMOS transistor and the source, drain and N well of the PMOS transistor are connected. The gate of the PMOS transistor is grounded. Under the control of the NMOS transistor, a programming voltage pulse is passed to the N well of the PMOS transistor of a selected memory cell. The magnitude of the voltage is sufficient to break the thin gate oxide of the PMOS transistor without damaging the NMOS transistor. Because the memory state of the memory cell depends on the breakdown status of the PMOS transistor, the data may be retained in the memory cell for an unlimited period of time.

System and method for providing an EPROM with different gate oxide thicknesses

A system and method are disclosed for providing drain avalanche hot carrier (DAHC) programming for non-volatile memory (NVM) applications. A memory cell of the present invention comprises a program transistor and a control capacitor, each having a gate coupled together to form a floating gate. The size of the program transistor is selected to create a coupling ratio between the program transistor and the control capacitor that is large enough to facilitate a Fowler-Nordheim erase process and small enough to facilitate DACH programming. A source bias voltage is supplied to the source of the program transistor to increase the hot electron injection rate and to decrease the hot electron generation rate in the memory cell.

System and method for providing drain avalanche hot carrier programming for non-volatile memory applications

A system and method are disclosed for very accurately determining a value of a substrate doping density in a metal oxide semiconductor device. A plurality of values of threshold voltage of a device under test are measured using a plurality of different values of source to substrate bias voltage. Then a linear relationship is determined between the plurality of values of threshold voltage and a plurality of different values of an expression that is a function of the source to substrate bias voltage and a function of a surface potential of the device. A very accurate value of the substrate doping density is reiteratively calculated from the linear relationship without assuming that the surface potential of the device has a constant value.

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Cape Elizabeth, ME, United States of America

William S Belcher