Boron incorporation into ultra-thin boron doped epitaxial grown diamond layers of thickness of 1 to 2 nm was investigated. Time of flight secondary ion mass spectroscopy was used to examine the boron concentration as a function of depth of the samples. The boron depth profiles were deconvoluted by modeling and measuring the depth resolution function with specially grown multiple delta doped layers on the same substrate. Boron incorporation in the delta layers as a function of substrate temperature and B/C ratio in the reactant gas was determined. A diamond deposition regime in which the doped delta layers with thickness of 1-2 nm and with boron concentrations of about 4-5.10(20) cm(-3) was obtained. Such layers are suitable for implementation of two-dimensional hole "gas" in diamond with high mobility and high carrier concentrations.