Multiwafer MOCVD systems for ferroelectrics

The need for ferroelectric capacitors and FRAMs is rapidly increasing as world wide communication networks are being erected and a higher integration of memory chips will be introduced in the next few years. To meet the demand for economical production of the raw material - thin film structures of ferroelectrics - we developed a metalorganic vapor phase epitaxy (MOVPE) reactor for the deposition of the material films on a large substrate area. We expanded the existing Planetary Reactor(R) to be able to take charges of nine six inch wafers or the equivalent (total substrate area of 0.25 square meters). The growth process can be predicted by numerical simulations rather than by growth runs in the real reactor. The reactor is proven in mass production environments for the growth of multicompound semiconductors. A major achievement is the compensation of the depletion of the gas phase which can result in poor uniformity of the films. By rotating the wafers, the growth rate along the direction of flow is averaged to produce uniform films with an expected variation of less than +/-1.5% in composition and +/-2% in thickness across an area with a diameter of 10 inches.