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Identification and quantification of Cu contamination on GaAs surfaces
Author(s) -
Sykes D. E.,
Chew A.,
Hall D. D.,
Crapper P. A.,
Grant I. R.,
Lamb M. S. M.,
Lunn M.,
Brozel M. R.,
Davies P.
Publication year - 1994
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.740210108
Subject(s) - wafer , contamination , secondary ion mass spectrometry , analytical chemistry (journal) , polishing , chemistry , impurity , mass spectrometry , materials science , metallurgy , optoelectronics , environmental chemistry , chromatography , ecology , organic chemistry , biology
Secondary ion mass spectrometry has been used to identify the presence of Cu contamination on undoped semiinsulating GaAs wafer surfaces following polishing under certain conditions. The presence of a contaminating species on the wafer surface is indicated by the influence of pre‐etch treatments on electrical measurements performed on heat‐treated wafers, with and without Si implants. The identification of Cu as a contaminant is confirmed by photoluminescence measurements. With the appropriate wafer preparation process, the level of Cu contamination is below the SIMS detection limit of <1 × 10 16 atoms cm −3 . In the SIMS analysis of the surface‐contaminated wafers, the Cu depth profile shape was dependent on the primary beam bombardment energy, suggesting a chemical segregation of Cu out of the altered layer, a redistribution that is known to occur in Si. To quantify the surface concentration of Cu, GaAs wafers were deliberately contaminated with Cu, heat treated and analysed with glow discharge mass spectrometry and SIMS to provide a cross‐calibration.