From MFM Capacitors Toward Ferroelectric Transistors: Endurance and Disturb Characteristics of HfO2-Based FeFET Devices

Ferroelectric Si: HfO2 has been investigated starting from metal-ferroelectric-metal (MFM) capacitors over metal-ferroelectric-insulator-semiconductor (MFIS) and finally ferroelectric field-effect-transistor (FeFET) devices. Endurance characteristics and field cycling effects recognized for the material itself are shown to also translate to highly scaled 30-nm FeFET devices. Positive-up negative-down as well as pulsed I-d-V-g measurements illustrate how ferroelectric material characteristics of MFM capacitors can also be identified in more complex MFIS and FeFET structures. Antiferroelectric-like characteristics observed for relatively high Si dopant concentration reveal significant trapping superimposed onto the ferroelectric memory window limiting the general program/erase endurance of the devices to 10(4) cycles. In addition, worst case disturb scenarios for a V-DD/2 and V-DD/3 scheme are evaluated to prove the viability of one-transistor memory cell concepts. The ability to tailor the ferroelectric properties by appropriate dopant concentration reveals disturb resilience up to 10(6) disturb cycles while maintaining an ION to I-OFF ratio of more than four orders of magnitude.