MOCVD GST for high speed and low current Phase Change Memory

Abstract

MOCVD (Metal-organic Chemical Vapor Deposition) has been investigated extensively to achieve smooth and conformal deposition of GST (GeSbTe) films. The studies are focused on filling confined cells as well as improving material properties for high performance PCM (Phase Change Memory) applications. Our MOCVD process allows GST alloys to fill 15nm hole structures. By tailoring the MOCVD process and GST compositions, MOCVD GST alloys exhibit superior material properties compared to Ge2Sb2Te 5 PVD (Physical Vapor Deposition) alloys in terms of higher device speeds and lower reset currents. PCM devices made from optimized MOCVD GST alloys demonstrate set-speed of 12ns in ∼100nm size devices, which is more than 10X faster than the typical 150–200ns set-speed observed for devices of similar size made from benchmark PVD Ge2Sb2Te5 alloys. PCM devices made from the 12ns high speed GST alloys by the MOCVD process also exhibit programming cycle endurances greater than 5×108 at a 20ns set time. In addition, devices made from MOCVD GST alloys can also be made to have ∼3X lower reset currents than devices made from PVD GST alloy of same compositions.