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Quantifying the effects of uneven etching during the SIMS analysis of periodic doping structures grown by silicon MBE
Author(s) -
McPhail D. S.,
Dowsett M. G.,
Fox H.,
Houghton R.,
Leong W. Y.,
Parker E. H. C.,
Patel G. K.
Publication year - 1988
Publication title -
surface and interface analysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.52
H-Index - 90
eISSN - 1096-9918
pISSN - 0142-2421
DOI - 10.1002/sia.740110110
Subject(s) - dopant , silicon , secondary ion mass spectrometry , doping , wafer , molecular beam epitaxy , analytical chemistry (journal) , antimony , boron , chemistry , etching (microfabrication) , epitaxy , materials science , mineralogy , optoelectronics , mass spectrometry , nanotechnology , inorganic chemistry , organic chemistry , chromatography , layer (electronics)
Problems associated with the secondary ion mass spectrometry (SIMS) depth profiling of periodic doping structures are discussed with reference to experiments on a boron‐in‐silicon modulation doping structure and a boron‐antimony silicon super‐lattice, both grown by silicon molecular beam epitaxy (MBE). The effects of uneven etching during SIMS analysis are compared with the effects of dopant diffusion during growth. Uneven etching is modelled with an algorithm in which the macrotopography of the crater base is described in terms of an unevenness function f ( x , y ). Simulation depth profiles involve passing craters of this topography f ( x , y ) through specified, laterally homogeneous, doping distributions ρ p ( z ) in a series of equal depth interations. The predicted SIMS signal is proportional to the amount of dopant sputtered per depth iteration. The model explains the peak shapes and the loss of depth resolution with depth that are observed experimentally. The effects of dopant diffusion during growth are found by re‐heating parts of the wafer to the growth temperature for various periods of time and then SIMS depth profiling them (thermal cycling).