Ultrathin Tantalum Oxide Capacitor Dielectric Layers Fabricated Using Rapid Thermal Nitridation prior to Low Pressure Chemical Vapor Deposition

Abstract

We describe the formation of ultrathin tantalum oxide capacitors, using rapid thermal nitridation of the storage‐node polycrystalline‐silicon surface prior to low pressure chemical vapor deposition of tantalum oxide. The amorphous tantalum oxide film is deposited on the nitrided polysilicon surface using penta‐ethoxy‐tantalum and oxygen gas mixture at 470°C. The films are annealed at 600–900°C in dry . Densification of the as‐deposited film by annealing in dry is indispensable to the formation of highly reliable ultrathin tantalum oxide capacitors. During this densification, and desorb from the as‐deposited film, and the film crystallizes into an orthorhombic structure. The RTN treatment allows a reduction of the equivalent thickness of the capacitor dielectric layer and results in superior leakage and reliability characteristics.