Low temperature epitaxial growth of boron-doped silicon thin films

Annealing of Boron-Doped Hydrogenated Crystalline Silicon Grown at Low Temperature by PECVD

“…The high hydrogen concentration in the doped epi-Si layers most probably leads to the formation of the well-known B–H complexes and thus to the neutralization of the substitutional boron atoms [11,12]. Upon annealing at temperatures above 200 °C hydrogen desorbs from the layer [13] resulting in the deactivation of the B–H complexes and thus in an increase in the conductivity and carrier concentration, as will be discussed below. As previously reported in the literature, we also notice hydrogen diffusion into the substrate [14].…”

“…We have previously demonstrated that annealing at 300 °C allows activation of the dopants in the p+ epi-Si layers and to achieve a doping efficiency of around 50% [13]. Here, we study the activation of the dopants by measuring the dark conductivity as function of the temperature.…”

Transmission electron microscopy characterization of low temperature boron doped silicon epitaxial films

“…The p+ epi-layers were grown by Chrostowski et al [8][9] in a semi-industrial capacitively coupled radio-frequency PECVD reactor at a process temperature of 175 • C from a H 2 /SiH 4 /TMB (trimethylboron, (CH 3 ) 3 B) gas mixture on phosphorus-doped (100) double-side polished Float Zone (FZ) crystalline silicon wafers. The latter were dipped into 5% HF to remove native oxide and allow epitaxial growth.…”

“…This type of growth is completely different from the well known PECVD growth process of silicon films which is achieved through the reaction between the substrate surface and SiH 3 radicals [6] [7]; yet both starting with a SiH 4 plasma. In this paper, the boron doped silicon epitaxy, already characterized by X-Ray Diffraction (XRD), Ellipsometry, Secondary Ion Mass Spectrometry (SIMS), electrochemical capacitance voltage (ECV) and photoluminescence [8][9] [10], is studied at local scale by using TEM techniques in order to bring new relevant information about the growth process and to understand the impact of annealing on the boron-doped epi-si layer grown at 175 • C. Indeed, while the previously cited techniques give indirect and macroscopic physico-chemical information, TEM techniques provide direct and local information thanks to their atomic scale resolution. TEM enables to appreciate the microstructure of the layer particularly at the interface that is known to be critical for the performance of the device.…”

“…It has already been used for low temperature silicon epitaxy to characterize mostly the crystalline quality [11][12] [13] or defects analysis such as H-platelets [14]. In this article, several TEM techniques were applied both to complete Chrostowski characterization [8] [9] and to provide new keys to understand better the epitaxy morphology and the annealing effect. Particular attention was paid to defects and strain in the layer and at the interface with a different approach from what has been done so far by combining HRTEM post-treatment, STEM and geometric/crystallographic models.…”