High speed pulse measurement of micro ferroelectric capacitors using a multi-probe atomic force microscope

To increase the density of memory devices, it is necessary to reduce the cell size. However, the smaller capacitors are made, the more difficult it becomes to measure their characteristics. Analysis of the electrical characteristics of single-bit cell capacitors has therefore increased in importance. We have developed a new method of analyzing memory devices using a multi-probe atomic force microscope (AFM) to overcome the limitations of a single-probe AFM. There can be up to five probes in this system. Fast square pulses with a rise time in nanoseconds are used to obtain the switchable polarization of the single-bit cell capacitor. Two separate probes individually contact the top electrode and the bottom electrode to apply the fast pulse. As a result, high-speed pulse measurements with up to a 50-ns pulse width and a 6-ns rise time have been achieved with an actual single-bit cell capacitor. This multi-probe AFM system could thus become a standard industry tool for device testing, such as for high-speed pulse measurements.