Ceramic Ferroelectrics for Memory Applications

An important potential application for ferroelectrics is their incorporation as thin films into dynamic random access memories (DRAMs). The majority of the memory in a computer is DRAM. Information is stored in millions of tiny capacitors, each representing a single bit. The capacitors used in DRAM chips are fabricated directly onto the silicon substrate. 

The bottom electrode is the doped (often n-type) silicon substrate the top electrode is either polysilicon or aluminum. The limitation of both Si02 and Si3N4 is that they have low k. 

The dielectric constant of Si02 is 3.9. A 100-mn-thick Si02 film will yield a capacitance of 3.4 x 10 F/ im (31 fF/ xm ). 

Being able to use a dielectric with a large K would allow a decrease in the required surface area, would avoid stacking and trenching, and would allow 

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