Oxynitridation‐Enhanced Diffusion of Phosphorus in <100> Silicon

Abstract

2051various additional curing temperatures. This process was found to reproducib]y remove polyimide effectively without leaving any residual polyimide film on the interface. No electrical degradation was found in the die as a result of this decapsulation process. It offers a useful deprocessing tool for failure analysts. Further work is needed to understand the residual film observed after RIE. ABSTRACTDiffusion of phosphorus in silicon in an ambient of pure N2, pure NHs, and mixtures of NH5 and N2 has been investigated to study the effect of the oxynitridation reaction on the diffusivity. With a thin SiO2 layer on the silicon wafer and a low phosphorus concentration, the diffusion coefficient of phosphorus can be expressed as a function of the partial pressure of NH~ and temperature as D = 0.145 exp (-3.26 eV/kT) + 1.718 • 10 ~ exp (-1.72 eV/kT)pNH3 cm 2 s -1 At the same time, the ratio of the interstitial concentration under oxynitridation conditions to the concentration under inert conditions can be expressed as CI 1 + 1.183 • 10 -5 exp (1.54 eV/kT)pNH3Ci, -By using P diffusion as an interstitial monitor, the data (Ref. 1) of oxynitridation-enhanced B diffusion are analyzed and the fraction of boron diffusion which occurs through the interstitial mechanism is calculated to be 0.88.