Estimation of phosphorus concentration in doped silicon substrates using atom probe tomography

This study investigated phosphorus dopant quantification in silicon using laser-assisted atom probe tomography (APT), with emphasis on the influence of laser pulse energy on ion formation and quantitative accuracy. Comparison with secondary ion mass spectrometry (SIMS) reveals that high laser energies promote the formation of polymeric phosphorus ions (P₂​, P₃), resulting in spectral overlap between ³¹P⁺ and ³¹P₂²⁺​ at 31 Da and significant quantification uncertainty. Reducing the laser energy suppresses polymeric ion formation and enhances monomeric phosphorus ions. At the optimized laser energy of 5 pJ, monomeric phosphorus ions dominate (> 95%), enabling unambiguous peak assignment and excellent agreement with SIMS, with a dopant concentration difference of approximately 1%. These results demonstrate that laser pulse energy is a critical parameter for accurate phosphorus quantification by APT and provide practical guidance for reliable dopant analysis in advanced silicon-based semiconductor devices.