Atom probe tomography quantification of carbon in silicon

Area of Science:

• Materials Science
• Nanotechnology
• Semiconductor Physics

Background:

• Accurate quantification of implanted carbon in silicon is crucial for microelectronics.
• Molecular ion formation in Atom Probe Tomography (APT) can complicate accurate elemental analysis.
• Understanding defect formation, such as self-interstitials, is vital for semiconductor device performance.

Purpose of the Study:

• To precisely quantify carbon in implanted silicon using APT under varying electric fields.
• To investigate the impact of electric fields on molecular ion dissociation during APT.
• To determine the ratio of self-interstitials to carbon atoms in clusters within implanted silicon.

Main Methods:

• Atom Probe Tomography (APT) was employed to analyze carbon in silicon.
• Two distinct electric fields (approximately 15 and 20 V/nm) were utilized during APT analysis.
• Isotopes 12C and 13C were used to identify and quantify molecular ions and carbon content.
• APT results were compared with Secondary Ion Mass Spectroscopy (SIMS) profiles for validation.

Main Results:

• Higher accuracy in carbon quantification was achieved at lower electric fields (~15 V/nm).
• Reduced molecular ion dissociation at lower electric fields contributed to improved accuracy.
• The number of self-interstitials trapped per carbon atom in clusters was estimated to be approximately one.
• This ratio aligns with the expected stoichiometry of SiC phases.

Conclusions:

• Low electric field conditions in APT enhance the accuracy of carbon quantification in implanted silicon.
• Minimizing molecular ion dissociation is key to reliable elemental analysis using APT.
• The findings provide valuable insights into defect behavior relevant to the microelectronics industry, particularly concerning dopant diffusion and implantation-induced defects.