Formation of single-crystal silicon layers on insulator islands using selective epitaxial growth and laser crystallization

SOI-like single-crystal silicon films on insulator islands are grown from SOI and bulk Si wafer substrates by a process combining vapor-phase epitaxy and laser crystallization. Ultra-high vacuum (UHV) CVD selective epitaxy is used to grow single-crystal Si, seeded from and normal to the substrate, between patterned insulator islands (SiO₂ or Si₃N ₄/SiO₂) up to the thickness of the insulator islands. Amorphous Si (a-Si) is sputter-deposited over both the epitaxially grown Si regions and the insulator islands, and the a-Si is completely melted by a single excimer laser pulse, leading to solidification of the molten Si seeded from the single-crystal Si regions. Analyses of the resulting microstructures reveal that lateral crystallization extends into the center of the insulator island, and that the laterally crystallized film is single-crystalline. The maximum measured lateral growth distance was greater than 2.5 microns. This paper details the microstructural analyses of the crystallized Si film, and discusses the mechanism of laser-induced lateral crystallization and the significance of heat flow and the Si₃N₄/SiO₂ layers in attaining large lateral growth lengths.