Abstract :
Sequential ABAB… surface chemical reactions can be employed for atomic layer controlled deposition. We have examined the binary reactions SiCl4+2H2O⋌SiO2+4HCl for SiO2 deposition and 2Al(CH3)3+3H2O ⋌ Al2O3+ 6CH4 for Al2O3 deposition. Each binary reaction (A + B ⋌ products) was performed sequentially by individual exposures to the A reactant and then the B reactant. If each surface reaction is self-limiting, repetitive ABAB… cycling may produce layer-by-layer controlled growth. For example, the individual “A” and “B” surface reactions for SiO2 deposition can be described by (A) Si–OH + SiCl4 ⋌ Si–O–SiCl3 + HCl, (B) Si–Cl + H2O ⋌ Si-OH + HCl.
We have studied ABAB… binary reaction sequences for SiO2 and Al2O3 deposition using laser-induced thermal desorption, temperature-programmed desorption and Auger electron spectroscopy techniques on single-crystal Si(100) surfaces. Fourier transform infrared spectroscopy techniques were also employed to examine these binary reaction schemes on high surface area SiO2 and Al2O3 samples. Controlled deposition of SiO2 and Al2O3 was demonstrated and optimized utilizing the above techniques. Under the appropriate conditions, each surface reaction was self-terminating and atomic layer controlled growth was a direct consequence of the binary reaction sequence chemistry.
