Laser Photolytic Deposition of Thin Films

Abstract

ABSTRACTAn excimer laser is used to photochemically deposit thin films of silicon dioxide, silicon nitride, aluminum oxide, and zinc oxide at low temperatures (100–350deg;C). Deposition rates in excess of 3000 Å/min and conformal coverage over vertical walled steps were demonstrated. The films exhibit low defect density and high breakdown voltage and have been characterized using IR spectrophotometry, AES, and C-V analysis. Device compatibility has been studied by using photodeposited films as interlayer dielectrics, diffusion masks, and passivation layers in production CMOS devices.Additionally, we have deposited metallic films of Al, Mo, W, and Cr over large (>5 cm2) areas using UV photodissociation of trimethylaluminum and the refractory metal hexacarbonyls. Both shiny metallic films as well as black particulate films were obtained depending on the deposition geometry. The black films are shown to grow in columnar grains. The depositions were made at room temperature over pyrex and quartz plates as well as silicon wafers. We have examined the resistivity, adhesion, stress and step coverage of these films. The films exhibited resistivities at most ∼20 times that of the bulk materials and tensile stress no higher than 7 × 109 dynes/cm2