Effect of laser recrystallization of polysilicon on the underlying substrate

Although laser recrystallization of polysilicon into a large-grain structure degrades the lifetime in the underlying substrate, a subsequent heat treatment similar to that seen during transistor fabrication increases the lifetime to approximately the value in the regions not laser processed. No electrical effects of laser damage to the underlying substrate are found in the transient behavior of MOS capacitors after furnace annealing or in the properties of p⁺n junction diodes. Since any damage to the substrate during laser processing is substantially eliminated by subsequent heat cycles, recrystallization is compatible with fabrication of high-quality devices in the substrate.