Kinetics and mechanism of amorphous hydrogenated silicon growth by homogeneous chemical vapor deposition

Surface reaction mechanisms are investigated to determine the activation energies of pure boron (PureB) layer deposition at temperatures from 350 C to 850 C when using chemical-vapor deposition from diborane in a commercial Si/SiGe epitaxial reactor with either hydrogen or nitrogen as carrier gas. Three distinguishable regions are identified to be related to the dominance of specific chemical reaction mechanisms. Activation energies in H 2 are found to be 28 kcal/mol below 400 C and 6.5 kcal/mol from 400 C to 700 C. In N 2 , the value decreases to 2.1 kcal/mol for all temperatures below 700 C. The rate of hydrogen desorption is decisive for this behavior. Pure boron (PureB) layer depositions have in recent years been applied for creating the p þ -region of extremely shallow, less than 10-nm deep, silicon p þ n junction diodes for a number of leading-edge device applications. 1 Particularly impressive performance has been achieved for the application to bulk-Si photodiodes for detecting low penetration-depth beams. [2][3][4][5] Ideal diode characteristics have been achieved for deposition temperatures in the 400 C-700 C range. The option of depositing at temperatures below $500 C, which together with the fact that the deposition is conformal and highly selective to Si, makes PureB technology highly compatible with amorphous-/polysilicon-/ crystalline-silicon thin-film device processing. Moreover, these properties also make it an attractive process for creating junctions on silicon nanowires and advanced CMOS (complementary metal-oxide-semiconductor) transistors including source/drain in p-type FinFETs. 6,7 These applications require a sub-3-nm thick layer to avoid excess series resistance through the high-resistivity PureB layer.In the present work, the deposition is performed in a commercial Si/SiGe epitaxial reactor by exposing the Si surface to diborane (B 2 H 6 ). At 700 C, in the first few seconds of exposure, the boron atoms interact with the Si surface sites to quickly build up something like an atomic layer plane, and upon further deposition, the boron coverage readily exceeds one monolayer (1 ML). After this, the boron atoms will be deposited on a full PureB surface, which is a process that has a much slower, well-controlled deposition rate. In the past, it has been shown that less than 2-nm-thick layers can be deposited with good reliability and uniformity by a suitable adjustment of deposition parameters such as deposition time, temperature, partial pressures, and flow rates. 8 In this paper, an investigation is presented of the surface reaction mechanisms and activation energies of PureB layer deposition in the temperature range of 350 C to 850 C. At the lower temperatures, the carrier gas has a large influence on the ability to create the first full boron coverage of the Si. Nevertheless, by first creating a full PureB coverage at 700 C, which is smooth and uniform, and then proceeding with the low-temperature depositions, the boron-on-boron activation energies could be determined over the whole temp...

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“…1. In the deposited layer, there are some possible crosslinked reactions 29,30 between two adjacent Si-H and B-H bonds ( …”

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confidence: 99%

Temperature dependence of chemical-vapor deposition of pure boron layers from diborane

2012

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“…A question is raised whether secondary dissociation of the ethylsilylene radical via reaction (3) is not a more likely source of Sill2 than primary dissociation of ethylsilane via reaction (1). Recent experimental work by Knight and co-workers [1][2][3] suggests that there may be two origins of silicon atoms from IRMPD studies of n-butysilane: one from Sill2 and the other from n-butylsilylene. In this work, decomposition pathways of ethylsilylene which lead to the formation of silicon atoms are explored.…”

Section: Introductionmentioning

confidence: 97%

“…In the production of amorphous silicon thin films for microelectronic manufacture, silicon hydrides such as silane (Sill4) and disilane (Si2Hr) are used as standard substrates [1][2][3]. Other substrates such as organosilanes are considered as possible alternatives provided their film deposition rates are faster than the silicon hydrides.…”

Section: Introductionmentioning

confidence: 99%

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Secondary dissociation pathways of ethylsilylene radical on ground and excited state potential energy surfaces

Francisco

1991

Molecular Physics

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“…For example, pyrolysis of silanes yields silylenes rather than silyl radicals, whereas photolysis produces silyl radicals [16]. Moreover, silylenes and silyl radicals with various degrees of fluorination (or chlorination) play an important role in chemical vapor deposition [17,18,19]. But the main area of interest of these compounds are the silicon-derivate surfaces which are widely used as substrates in the adsorption process of biological compounds, such as amino acids, proteins etc, in view of their application in different biotechnology areas such as biomaterials, biosensors, and bioseparation [20].…”

Section: Introductionmentioning

confidence: 99%

Bond-order correlation energies for small Si-containing molecules compared withab initioresults from low-order Møller–Plesset perturbation theory

et al. 2006

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The present study of small molecules containing silicon has been motivated by (a) the considerable interest being shown currently in the kinetics and reactivity of such molecules, and (b) the biotechnological potential of silicon-derivate surfaces as substrates in the adsorption of, for instance, amino acids and proteins. Therefore, we have studied by (i) a semi-empirical approach and (ii) an ab initio procedure employing low-order Møller-Plesset perturbation theory, the molecular correlation energies of some neutral closed and open shell silicon-containing molecules in the series SiX n Y m . Procedure (i) is shown to have particular merit for the correlation of the ionic members studied in the above series, while the ab initio procedures employed come into their own for neutral species.

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Kinetics and mechanism of amorphous hydrogenated silicon growth by homogeneous chemical vapor deposition

Cited by 117 publications

References 13 publications

Temperature dependence of chemical-vapor deposition of pure boron layers from diborane

Temperature dependence of chemical-vapor deposition of pure boron layers from diborane

Secondary dissociation pathways of ethylsilylene radical on ground and excited state potential energy surfaces

Bond-order correlation energies for small Si-containing molecules compared withab initioresults from low-order Møller–Plesset perturbation theory

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