Low power and high speed phase-change memory devices with silicon-germanium heating layers

Abstract

The switching speed and the reliability of the phase-change memory (PCM) device employing a SiGe film as a heating layer were compared with those of the control device employing a conventional TiN heating layer. The influence of the semiconducting nature of the SiGe film on PCM operation was investigated. The critical pulse width for the onset of a set process was reduced to less than about 50% by substitution of SiGe for TiN. The cycling endurance value for the PCM device with a SiGe heating layer was comparable to that of the control device, which indicated that the introduction of a SiGe film did not induce reliability degradation. The heterojunction between the GeSbTe and SiGe layers was so leaky that the effect of the semiconduction type of SiGe was negligible. The reset current was saturated at a minimum value with increasing resistivity of a SiGe film, which was attributed to the resistance lowering of SiGe at high temperature. The PCM device with a SiGe heating layer was successively fabricated using Si complementary metal oxide semiconductor technology, and its reset current decreased drastically compared to that of the control device.