Denuded zone stability in a SPAD diode as a function of out-diffusion parameters

The effect of a complete fabrication cycle of a single photon avalanche diode (SPAD) on denuded zone presence and width is reported. The heavy diffusion stage required to create a deep guard ring junction appears to be the most deleterious for the denuded zone stability and the final bulk defect content. The out-diffusion step parameters are decisive in assuring the denuded zone stability: the use of a chlorinated oxidizing ambient during the out-diffusion treatment appears to be sufficient to maintain a satisfactory denuded zone width even after the heavy-diffusion stage. The role of process-induced defects, in particular of the interstitials, is stressed out.