Study on Interface Adhesion between Phase Change Material Film and SiO2 Layer by Nanoscratch Test

Temperature dependent interfacial adhesion strength between phase change material film and a SiO 2 layer was investigated employing Nano Indenter ® . Phase change materials of Ge 2 Sb 2 Te 5 and Si 2 Sb 2 Te 6 were adopted for a comparative study. The decrease of adhesive strength with an increased annealing temperature can be deduced from the optical micrographs of the two cases. Critical load obtained from the nanoscratch tests was introduced to quantitative characterize the interfacial adhesion strength of the samples. Scanning electron microscope and energy dispersive spectrometer were utilized to further analysis the adhesive properties of the interfaces. Results show that Si 2 Sb 2 Te 6 has better adhesive performance than Ge 2 Sb 2 Te 5 with SiO 2 due to its higher activation energy and weaker thickness variation upon crystallization as well as its smaller crystal grain size in the crystalline state. Considering the adhesive strength with SiO 2 , Si 2 Sb 2 Te 6 is a preferable candidate over Ge 2 Sb 2 Te 5 for future high density phase change random access memory application.