Lateral diffusion in GaAs

The lateral diffusion of zinc and tin in GaAs, during diffusions through windows in phosphosilicate glass masks, has been measured as a function of oxide composition and oxide thickness. The lateral diffusion of zinc extends upto seventeen microns for a junction depth of one micron. The lateral diffusion of tin extends upto sixty microns for a junction depth of one-eighth of a micron. Interfacial stress between mask and substrate has been measured and shown to be the driving force for the large lateral movement of these diffusants. Techniques which will reduce the interfacial stresses and decrease the lateral movement of the diffusants are presented in this paper.