Pyridine-catalyzed molecular layer deposition of silicon oxycarbide and structural evolution upon thermal annealing

Hydrogenated silicon oxycarbide (SiOC-H) is a common low-permittivity dielectric material used in integrated circuits. As integrated circuits continue to downsize, SiOC-H deposition processes, such as molecular layer deposition (MLD) that offers precise thickness control and high conformity, are increasingly vital. MLD of SiOC-H using bis(trichlorosilyl)methane and water satisfies these demands via self-limiting surface reactions. Herein, we introduce the use of pyridine in the precursor dosing step to catalyze SiOC-H MLD, resulting in a growth per cycle of 0.31 nm/cycle, twofold increase over previously reported, and tenfold increase over observed under identical conditions without the presence of catalysts. Upon annealing at 250–550 °C, the Si–CH2–Si and Si–OH groups in SiOC-H undergo intramolecular reactions to form terminal Si–CH3 groups. These Si–CH3 groups decrease the density and dielectric permittivity (from ∼8 to 3.55). Water contact angle measurements reveal that annealing induces a transition in the SiOC-H surface from being hydrophilic to hydrophobic, which also enhances its etch resistance against diluted hydrofluoric acid solution. We compare the etch selectivity of as-deposited and annealed SiOC-H with that of silicon dioxide during CHF3/Ar reactive ion etching. Overall, our findings advance the practicality of SiOC-H MLD for the fabrication of nanoelectronics.