Process compatible silicon-germanium-antimony heating layer for high density phase-change memory applications

The effects of SiGeSb heating layers, formed at room temperature by a sputtering method, on the performance of phase-change memory devices were investigated. The amount of Sb atoms in SiGeSb films was modified by changing sputtering power for a Sb target, and the resulting resistivities of the films ranged from 2.5 to 3.75 × 10⁷ mΩ cm depending on Sb concentration. The reset current and the set pulse width of a phase-change memory device decreased with decreasing Sb concentration due to an increase of the electrical and thermal resistances. The SiGeSb heating layer, like a SiGe heating layer grown at 650 °C by a chemical vapor deposition (CVD) technique, resulted in lower programming current and higher speed than a conventional TiN heating layer. The sputtered SiGeSb film appears superior to the CVD SiGe film for integration with a CMOS process because of its low formation temperature.