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Mathematical modeling of boron diffusion from boron oxide glass film sources
Author(s) -
Yeckel Andrew,
Middleman Stanley
Publication year - 1988
Publication title -
aiche journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.958
H-Index - 167
eISSN - 1547-5905
pISSN - 0001-1541
DOI - 10.1002/aic.690340907
Subject(s) - boron , diffusion , wafer , materials science , silicon , solubility , doping , boron oxide , dissolution , borate glass , oxide , analytical chemistry (journal) , chemical engineering , chemistry , thermodynamics , metallurgy , nanotechnology , chromatography , optoelectronics , organic chemistry , physics , engineering
Mathematical models are developed to examine two alternative means of boron doping from boron‐rich glass films. For the planar source diffusion system, in which boron diffusion and glass film growth occur simultaneously at high temperature (900–1,200°C), glass film growth rates and the degree of doping achieved are predicted. In most cases, the solubility limit of boron in silicon is attained at the silicon surface. It is found that depletion of the boron source wafers used in this process may be slowed considerably by their removal from the reactor after a short time. Model predictions for an alternative method, in which the glass film is pregrown at low temperature (300°C) and the diffusion subsequently performed at high temperature, demonstrate a strong dependence of the boron surface concentration on the initial boron content in the pregrown glass film, for concentrations of boron near the solubility limit. The conditions for which a masking film of SiO 2 is insufficient to prevent boron diffusion into silicon, known as mask failure, are also predicted by the models.