(Invited) Thermal Atomic Layer Deposition of Elemental Antimony and Bismuth Films

The elements antimony (Sb) and bismuth (Bi) are important components of many thin film materials. In many applications, films need to be grown in high aspect ratio features with perfect conformality and Angstrom-level control of film thicknesses. Atomic layer deposition (ALD) is a method that can afford uniform thickness and conformal films, even in narrow and deep nanoscale features. To date, there have been several ALD processes reported for elemental Sb films using SbCl 3 and Sb(SiR 3 ) 3 (R = Me, Et), but no reports of Bi films grown by ALD have been published. 1,2 Herein, several families of thermal ALD processes will be described for the growth of elemental Sb and Bi films. Precursors that were explored for Sb and Bi include SbCl 3 , BiCl 3 , BiPh 3 , and Bi(NMe 2 ) 3 . Reducing precursors encompassed 2-methyl-1,4-bis(trimethylsilyl)-2,5-cyclohexadiene, 3 1,4-bis(trimethylsilyl)-1,4-dihydropyrazine, 3 and nitrogen sources such as ammonia, hydrazine, alkyl hydrazines, and alkyl amines. The processes employing the nitrogen co-reactants are proposed to occur through unstable SbN and BiN, which then decompose with loss of N 2 to afford elemental Sb and Bi films. Self-limited Sb and Bi film growth was established between 25 and 175 °C. High purity Sb (>98%) and Bi (>94%) films were demonstrated by X-ray photoelectron spectroscopy analysis. X-ray diffraction analyses revealed the growth of crystalline Sb and Bi films. The results of additional film characterization will be presented. Al Hareri, M.; Emslie, D. J. H. Chem. Mater. 2022, 34, 2400-2409. Pore, V.; Knapas, K.; Hatanpää, T.; Sarnet, T.; Kemell, M.; Ritala, M.; Leskelä, M.; Mizohata, K. Chem. Mater. 2011, 23, 247– 254. Klesko, J. P.; Thrush, C. M.; Winter, C. H. Chem. Mater. 2015, 27, 4918-4921.