Product Briefing Outline: SAFC Hitech has made significant progress in developing Germanium Antimony Telluride (GexSbyTez or GST) precursors for use in high volume manufacturing phase change memory (PCM) applications. Extensive development work has been conducted with both the precursors and with the use of conventional Metal-Organic Chemical Vapor Deposition (MOCVD) techniques to deposit them, resulting in the successful deposition of device-quality GST.
Problem: Until now, PCM materials have generally been deposited by sputtering or other Physical Vapor Deposition (PVD) techniques, which are line of sight methods and have inherent weaknesses relating to uniformity of deposition. Vapor phase deposition techniques, such as MOCVD, offer several advantages in relation to GST precursors, in particular, a better step coverage for deposition on patterned substrates, industrial scaling and high compositional control.
Solution: After extensive work to synthesise a number of different chemicals and characterize their physical properties, a combination of sources was found with a much improved match of thermal stability to allow decomposition to the same degree when simultaneously introduced to the deposition reactor chamber. The actual chemicals of choice were found to be Ge(NMe2)4, Sb(NMe2)3 and iPr2Te. With these identified, SAFC Hitech then developed synthesis protocols to allow the isolation of high purity product in both small and large laboratory scale equipment. Recent growth trials have resulted in successful deposition of device-quality GST using nitrogen as a carrier gas.
Applications: Vapor phase deposition techniques, such as MOCVD for phase change memory (PCM) applications.
Platform: Ge(NMe2)4, Sb(NMe2)3 and iPr2Te.
Availability: September 2008 onwards.