SIMS quantification of Si1-xGex alloys using polyatomic secondary ions

The matrix effect in Si1-xGex alloys (x less than or equal to 0.5) grown by ultrahigh vacuum chemical vapour deposition was investigated with an O-2() primary beam in a Cameca IMS 6f instrument. The results showed that the m atrix effect in Si1-xGex alloys was significant when the Ge fraction was > 0.25, and it turned out to be more pronounced at low impact energies. Never theless, the composition of Si1-xGex alloys could be quantified based on th e linear variation of appropriate secondary ion intensity ratios against th e Ge concentration. The use of polyatomic secondary ions to measure the com position of SiGe alloys is reported in this paper. By this method, both the dopant and matrix elements in a Si/Si1-xGex/Si heterojunction bipolar tran sistor sample have been quantified by SIMS. The germanium fractions thus de termined agree well with values obtained by double-crystal x-ray diffractio n. Copyright (C) 2001 John Wiley & Sons, Ltd.