Trends in the development of ULSI DRAM capacitors

DRAM manufacturers face a tremendous challenge to keep the DRAM cell capacitance constant from generation to generation. The 256 Mb DRAM will certainly represent the last DRAM generation to use the standard storage dielectric materials consisting of silicon dioxide and silicon nitride. These materials cannot be shrunk further, and the capacitor area cannot be kept constant in a manufacturable cell. The most promising approach to keep cell capacitance constant in future DRAM generations, beyond 256 Mb, is to develop and integrate high dielectric constant materials.