Samsung Semiconductor Inc.

Pericom Semiconductor Corporation

Paul C Tong

Chi-Hung Hui

A non-volatile memory cell uses a p+ diffusion region spaced a lateral distance from the n+ drain of the n-channel programmable transistor. A diode between this p+ diffusion and the n+ drain has a low breakdown voltage because of the close spacing of the high-doping n+ and p+ diffusions. This diode generates electrons when avalanche breakdown occurs. The avalanche electrons are swept up into the programmable gate during programming. Since the avalanche electrons are generated by the diode rather than by the programmable transistor itself, programming efficiency no longer depends on the channel length and other parameters of the programmable transistor. The breakdown voltage of the diode is adjusted by varying the lateral spacing between the n+ drain and the p+ diffusion. Smaller lateral spacing enter avalanche breakdown at lower voltages and thus program the programmable transistor at a lower drain voltage. A drain voltage less than the power supply is possible with the diode, eliminating the need for a charge pump for the drain. A deep p-type implant under the n+ drain can also form the diode. The diode can be used for input-protection (ESD) devices.

Avalanche-enhanced CMOS transistor for EPROM/EEPROM and ESD-protection

A process for manufacturing an integrated circuit having both field effect and bipolar transistors provides, in one embodiment, a polycide film over the gate and field oxides. The polycide film is patterned such that a protective structure of gate material is formed on top the base region while the gate of the FET is formed, in a single process step. Ionic species are implanted to form the source and drain and the collector contact. The protective structure of gate material in the active region of the bipolar transistor is removed just before the base region is implanted to form the base. In a second embodiment, a silicon nitride oxidation mask for field oxide regions is formed over the bipolar transistor and the field effect transistor active regions. The portion of the nitride oxidation mask is removed only from the FET active regions after field oxide regions are formed. The portion of the nitride oxidation mask is left intact through formation of the gate regions of the FETs, formation of the oxide spacers of the FET active regions, and the formation of source and drain regions of the NMOS transistor. The nitride oxidation mask over the bipolar active region is removed prior to the base implant step. With the nitride oxidation mask over the bipolar transistor active region, a V.sub.T implant into the FET active region is performed.

BiCMOS process with low base recombination current bipolar transistors

A process for manufacturing both field effect and bipolar transistors provides, in one embodiment, a polycide film over the gate and field oxides on the surface of the semiconductor substrate is patterned such that a protective structure of gate material is formed on top the base region of the bipolar transistor while the gate of the FET is formed. The channel region of the FET is defined by the gate, which also serves as a mask for etching away the gate oxide from the source and drain regions. The protective structure of gate material in the active region of the bipolar transistor is removed just before implantation to form the base of the bipolar transistor. In a second embodiment a silicon nitride oxidation mask for formation of filed oxide regions over the bipolar transistor and the FET active regions is formed and portions of the nitride oxidation mask is removed only from the FET active regions after field oxide regions are formed. The portion of the nitride oxidation mask is left intact through formation of the gate regions of the FET, formation of the oxide spacers of the FET active regions, and the formation of source and drain regions. The nitride oxidation mask over the bipolar active region is removed prior to the base implant step. With the nitride oxidation mask over the bipolar transistor active region, a VT implant into the FET active region is performed.

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San Jose, CA, United States of America

Paul C Tong