March 12, 2007 – Texas Instruments and Ramtron International Corp. have entered into a commercial manufacturing agreement for ferroelectric random access memory (FRAM) products. The agreement provides for the production of Ramtron’s FRAM memory products on TI’s advanced 130nm FRAM manufacturing process, including Ramtron’s 4Mb FRAM memory.
Ramtron and TI have been working together since August 2001, when the companies entered into a FRAM licensing and development agreement.
“This manufacturing agreement marks a major leap forward in the commercialization of higher-density FRAM products,” said Ramtron CEO Bill Staunton. “In addition to a 4Mb device, we are planning to sample at least one additional product off of the TI line in 2007.”
To create the embedded FRAM module, TI added two additional mask steps to its standard, 130nm copper-interconnect process. By moving to a 130nm process, the companies will deliver Ramtron’s 4Mb FRAM memories using the smallest commercial FRAM cells shown-to-date, measuring only 0.71 sq micron and enabling a higher memory density than that achieved with SRAM cells. To achieve this cell size, the process features an innovative capacitor-over-plug process that places the nonvolatile capacitor stack directly on top of the W-plug transistor contact.
At the core of FRAM technology are tiny ferroelectric crystals integrated into a capacitor that allow FRAM products to operate like fast nonvolatile RAMs. The electric polarization of the ferroelectric crystals is shifted between two stable states by the application of an electric field. The direction of this electric polarization is sensed by internal circuits as either a high or a low logic state. Each orientation is stable and remains in place even after the electric field is removed, preserving the data within the memory without periodic refresh.
TI fabricates planar FRAM cells using a capacitor-on-plug approach to minimize cell area. The ferroelectric capacitor is formed using Iridium electrodes and a thin lead zirconate titanate (PZT) ferroelectric layer.