Characterization of Semiconductor　Devices Using the Scanning Nonlinear Dielectric Microscopy

Koichiro Honda^a and Yasuo Cho^b

^aDevice and Materials Laboratory, Fujitsu Laboratories Ltd.
^bResearch Institute of Electrical Communication, Tohoku University

Abstract: In flash memory, both the “1” and “0” states are stored by changing the threshold voltage (Vth) of the transistor, where the Vth shifts are induced by stored charges. The metal-SiO₂-SiN-SiO₂-semiconductors (MONOS) memory stores charges in the SiN film of the gate SiO₂-SiN-SiO₂ (ONO) film. By using a scanning nonlinear dielectric microscopy (SNDM), we have succeeded in the identification of the charges (electrons and holes) concentrated areas in the ONO gate film in high-resolution. We also demonstrated that the SNDM has high performance and resolution for observing the charge distribution after program-erase operations cycling. Thus, it is expected that SNDM will be an effective method for observing the charges in the semiconductor devices. Finally, in downsized MONOS flash memory; we succeeded in visualizing the charge distribution by detecting a second-order nonlinear dielectric constant by using SNDM.

Key words: Flash Memory, Scanning Probe Microscopy, SNDM, Failure Analysis