Simulation of Phosphorus Diffusion Profiles with Different Phosphorus Surface Concentration at the Same Diffusion Temperature in Silicon

Abstract

Four diffusion models based on the pair diffusion models of vacancy and interstitial mechanisms are adopted for the simulation of six experimental profiles of P surface concentration, CP+ s, from 3×1020 to 2.5×1018 cm-3 at 900°C. Values of fitting parameters are determined to simulate the profiles of CP+ s=3×1020 and 2.5×1018 cm-3 well. Changing only CP+ s, other profiles are simulated. At high CP+ s, a large amount of excess I is generated. For the simulation of CP+ s=3×1020 cm-3, it is necessary to control excess I. For the simulation of CP+ s<3×1020 cm-3, the effect of a main parameter upon the control of excess I should decrease with decreasing CP+ s. Based on this, the decrease in quasi self-interstitial formation energy or the ratio of the diffusion coefficient of a negatively charged P–V pair to that of a neutral one is suitable for the main parameter. To decide the suitable main parameter, it is necessary to obtain a more accurate experimental profile, paying attention to whether or not the profile has a plateau.