Dresden 2011 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 5: Innovative Systems and Devices

HL 5.7: Talk

Monday, March 14, 2011, 12:00–12:15, POT 06

Evaluation of measurement techniques for characterization of charge trapping materials for memory applications — •Ekaterina Yurchuk, Thomas Melde, and Thomas Mikolajick — NaMLab gGmbH, Nöthnitzer Str. 64, 01187 Dresden, Germany

The charge trapping memories are based on the charge storage in isolated trap states within the gate dielectric of the field effect transistor. The trap parameters can be extracted from the charge loss dynamics, as retention measurements. The aim of the present work was to identify the most suitable measuring technique for subsequent evaluation of the trap density distribution within the memory layer.

Two methods for experimental determination of retention characteristics on SONOS (silicon-oxide-nitride-oxide-polysilicon) capacitor structures were studied. The most common approach for measuring the threshold voltage shift is the application of zero gate voltage during the wait time. On the contrary, the constant capacitance method applies a regulated gate voltage to maintain the flatband condition. The effect of temperature, program state and programming conditions on the charge loss for both measuring techniques are analyzed. The constant capacitance method allows the predefinition of the field conditions in bottom oxide and thus must be more appropriate for the extraction of trap density distribution. However, the carried out experiments and simulations of the discharging process could only partially confirm this assumption.