A REVIEW OF HIGH DIELECTRIC MATERIALS FOR DRAM CAPACITORS

There has been growing interest in the use of materials with the perov skite structure as a dielectric for capacitors in dynamic random acces s memory chips. The heightened activity in this field is exemplified b y the nearly exponential increase in the number of patents issued duri ng the past 5 years. At the present time, a fully functional DRAM with a capacitor incorporating these high-dielectric constant materials ha s not been demonstrated. All existing DRAMs use silicon dioxide and/or silicon nitride as the capacitor dielectric. This paper will describe the potential advantages of incorporating high-dielectric materials i nto the storage capacitor of a DRAM and review the requirements of the high-dielectric layer when used in a simple stack capacitor structure suitable for the GBit generation of DRAM. Recent advances in this tec hnology are reviewed and the major issues, which could be potential sh ow-stoppers and still need to be resolved, are described.