Aluminium Oxide Atomic Layer Deposition on Semiconductor Substrates

摘要

Al_2O_3 Atomic Layer Deposition (ALD) on semiconductor substrates finds potential applications in CMOS devices, memory devices, solar cells, etc. In this paper, we study the TMA/H_2O ALD of Al_2O_3 on Si, Ge and GaAs substrates. Total reflection X-Ray Fluorescence (TXRF) is used to investigate the growth-per-cycle evolution during the early ALD reaction cycles. TXRF demonstrates growth inhibition from the second reaction cycle on many substrates, including conventionally used fully hydroxylated SiO_2. Theoretical calculations, based on Density Functional Theory, indicate the formation of electron deficient bonds at the Al_2O_3/semiconductor interface, by interaction between neighboring monomethyl aluminium surface species. Both experiment and theory thus indicate that the surface chemistry of Al_2O_3 ALD of is more complex than previously described.