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We discuss inline electrical testing to monitor the baseline of Analog Computing hardware using Phase Change Memory (PCM) technology. Tightening the PCM resistance distribution is necessary to meet analog computation requirement. A new yield methodology is introduced. A study of heater process variation, which will affect the heater height and the PCM resistance, will be discussed. [ABSTRACT FROM AUTHOR]

The reactive-ion-etching (RIE) characteristics of phase change material GeTe in CHF3/O2 plasma for back end of nonvolatile phase change memory devices were investigated in this paper. The etch rate and surface root-mean-square (RMS) roughness of crystalline GeTe and amorphous GeTe films were studied with various etching parameters, such as gas mixture ratio, chamber gas pressure, and power. It is found that the etch rate first increases with the increasing concentration of O2 and get at peak value 68.5 nm/min at 12% O2/(CHF3+O2), then decreases from 12% to 20% of O2 fraction. The surface RMS roughness slightly increases with the increasing oxygen content. By changing the gas pressure, the etch rate of GeTe films increases approximately linearly with increasing gas pressure up to 50 mTorr. In addition, the etch rate increases approximately linearly with increasing power below 400 W. The XPS spectra shows that some non-volatile GeFx, GeOx, TeFx, and TeOx by-products were left on the etched film surface. From these results of etched TiN films and GeTe films, the result of RIE with one step recipe shows the formation of under-cut on the profile of etched film. However, the result of RIE with two steps recipe shows better vertical characteristic and few residues were left on the profile of etched film. [ABSTRACT FROM AUTHOR]

The development of new generation nonvolatile memories, such as Phase Change Memories (PCMs) and Resistive-RAMs (ReRAMs), calls for accurate and controllable programming pulses, which are fundamental to adequately characterize the memory cell. Indeed, the final cell state depends on parameters of the applied programming pulse(s), such as amplitude, duration, and fall time. The performance and the flexibility of conventional automated test equipment (ATE) should be enhanced to carry out reliable tests on different cell implementations, which may have different architectures or material compositions. Aiming at this goal, we designed, fabricated, and experimentally evaluated an on-wafer pulse generator, controlled by commercial ATE, which is able to provide voltage pulses with programmable amplitude, duration, and fall time. A key design requirement was to allocate the generator in the wafer scribe lanes, to reduce the impact of the proposed approach on testing cost. However, this requirement implies that the system must feature reduced silicon area occupation and have a very disadvantageous aspect ratio as well as limited pad count. Since unavoidable process spreads and nonidealities can affect the accuracy of the on-wafer pulse generator, a calibration procedure for pulse parameters was conceived, implemented, and validated. The designed system is able to generate pulses with an amplitude from 0.5 V up to 4.5 V, a pulse duration from 50 ns to 350 ns, and a fall time from 10 ns to several \mus (the variability of the last parameter is essential to analyze the response of PCM cells to different quenching times). By using the proposed calibration procedure, it is possible to obtain an accuracy better than \pm10\% in all the parameters that define the shape of the generated programming pulse. Measurements on a fabricated prototype showed the effectiveness of the presented approach. [ABSTRACT FROM PUBLISHER]

To reduce the reset current for developing reliable high density phase change random access memory (PCRAM), small bottom electrode contact (BEC) size formation is a critical process. One of the failure mode for the process is the corrosion of tungsten plug, which is caused by tungsten chemical mechanical planarization (CMP) process. In this paper, this CMP process was analyzed. The tungsten polishing step process was characterized by the coefficient j and it shows good performance in tungsten polishing process. The alkali and acidic buff slurry effect on tungsten plug performance were studied. The result shows that the recess free tungsten plug had been fabricated with acidic buff slurry. The electric results confirm that it can fulfill the set operation of PCRAM cells. [ABSTRACT FROM AUTHOR]