Single crystalline Si islands on an amorphous insulating layer recrystallized by an indirect laser heating technique for three-dimensional integrated circuits

Abstract

A new laser recrystallizing technique for producing single crystalline Si islands on an amorphous insulating layer has been developed. Si islands are recrystallized by indirect Ar ion laser heating utilizing a Si cap. This technique is an effective recrystallizing method for fabricating three-dimensional integrated circuits. During recrystallization, this technique easily and stably produces a desired temperature profile to eliminate grain boundaries in recrystallized Si islands; the interior of the Si islands is kept cooler than the periphery and crystal growth begins from the interior. This desired temperature profile is realized because an Ar ion laser power is absorbed in the Si cap and heat flow takes place to the Si islands laterally as well as vertically from the heated Si cap through a separation cap. Damage to the underlying layer is not observed, which suggests that the laser beam power is cut in the Si cap. No grain boundaries are observed in more than 90% of the Si islands recrystallized with such an arrangement that laser beam traces include Si islands; the size of the islands is 20×60 μm. Field effect mobility of 460 cm2/Vs is obtained for Si on insulator/metal-oxide-semiconductor field-effect transistors fabricated in the recrystallized Si islands with this technique.