SIMS quantification of SiGe composition with low‐energy ion beams

Abstract

Systematic SIMS analyses with low-energy (250 eV ∼1 keV) oxygen, cesium and krypton primary beams have been carried out on a set of fully strained uniform epitaxial Si 1−x Ge x films (x = 5 ∼ 60%), as well as a germanium ion-implanted silicon standard to investigate the matrix effect under various conditions. It is shown that preferential ion yield enhancement of one matrix component over the other can occur as the result of primary ion incorporation. Through defining a matrix yield factor, this work demonstrated that constant secondary ion yield ratios between Si ion and Ge ion over a large concentration range are only valid under some very specific analysis conditions. Emphases were placed on oxygen beam analyses with regard to steady-state ion yields and surface transients. Both show some unique features only accessible under low-energy conditions.

Advanced quantitative analysis of epitaxial SiGe composition on production wafer for logic devices

“…Depth calibration for SIMS profiles were based on the thickness of Si 1‐x Ge x standard films as measured with transmission electron microscopy. SIMS analysis confirmed the sputter rate increased as the Ge content increased, this sputter rate response was consistent with literature …”

“…Literature work has revealed many successful inline metrology methods to determine the Ge concentration via X‐ray diffraction, X‐ray photoelectron spectroscopy, and X‐ray fluorescence (XRF) on production wafers . Additionally, there has been some exceptional research and development work on SiGe characterization with a focus on proper quantification methods for Ge concentration via SIMS in large part due to the complicated nature of significant variations in both sputter and ionization yield observed with respect to Ge content . However, limited data exists on quantifying SiGe B concentration and the effects on device performance .…”

Atomic spectrometry update. Industrial analysis: metals, chemicals and advanced materials

“…Several authors have used low energy O 2 + or Cs + ion beams. 320 A study was made of the matrix effects exhibited under various conditions. 318 The ablation rate achievable was 1 and 2 nm min À1 for Cs + and O 2 + respectively when a primary ion beam with an energy of 150 eV was used.…”

Quantitative depth profiling of Si1–xGex structures by time-of-flight secondary ion mass spectrometry and secondary neutral mass spectrometry

“…In the late eighties, Gillen et al [3] using Ar + , O 2 + and Cs + primary ions revealed considerable variations in Si and Ge secondary ion yields preventing quantification of the sputter depth profiles. However, many subsequent studies [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22] (to name some but not all works) have demonstrated the possibility in principle to quantify Si 1-x Ge x systems over a wide range of germanium concentration.…”

“…These artifacts complicate calibration procedure, but did not impede quantification of Si 1-x Ge x multilayers including their interfaces [15,16]. There are also some investigations with inert gas (Ar + , Kr + ) primary ion beams [12,14]. However, in that case the secondary ion yields are smaller than in the case of Cs + and O 2 + ion beam bombardment.…”