Mechanistic study of borosilicate glass growth by low-pressure chemical vapor deposition from tetraethylorthosilicate and trimethylborate

Abstract

A reaction mechanism and film morphology as a function of reactor conditions and post growth thermal annealing for borosilicate glass (BSG), (SiO 2 ) x (B 2 O 3 ) 1-x , films deposited from tetraethylorthosilicate (TEOS), trimethylborate (TMB), and oxygen (O 2 ) precursors by low-pressure chemical vapor deposition (LPCVD) was determined. An empirically derived reaction model for BSG film growth is proposed that predicts the growth rate and composition of BSG films up to 70 mole% B 2 O 3 . The BSG reaction model includes a strongly adsorbed TEOSderived intermediate that forms SiO 2 and a direct surface reaction of TMB, in O 2 , to form B 2 O 3 . This model is supported by growth rate and mass spectroscopic data. The BSG film morphology, investigated using atomic force microscopy, was found to have a root-mean-square roughness of 0.5 nm, with the precise film morphology being a function of reactor conditions. The BSG film roughness increases with film thickness, temperature, and boron content. Thermal annealing of the films in a water-free environment leads to planarization of the BSG governed by the film composition and anneal temperature.

Atomic layer deposition of B2O3 thin films at room temperature

“…In addition, boron oxide thin films react with air to form boric acid (H 3 BO 3 ) which finds uses as solid lubricant [3] or as self-assembled boric acid nanostructures [4]. Moreover, boron oxide is a constituent of borophosphosilicate [5,6] and glassy B 2 O 3 -Li 2 O-PbO [7] thin films as well as a dopant for diamond [8,9] and Si:H [10] thin films. In addition to nanowires, chemical vapour processing has been used for the deposition of some other boron-containing materials as well.…”