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TI Eyes Embedded FRAM For Memory

Texas Instruments (TI) Thursday said it has produced a new type of memory chip which will cost less and perform better than current embedded standards - Flash or DRAM .

The Dallas-based chipmaker said it has created a 64 Megabit Ferroelectric RAM (FRAM) chip within a standard CMOS logic process. TI says they are also the smallest FRAM cells ever reported, a mere 0.54um.

TI says the development of FRAM is important as the next generation of embedded non-volatile memory because it allows them to connect very dense memory cells.

"We believe FRAM has the potential to become an ideal non-volatile memory option for a wide range of applications in the 2005 timeframe," said Hans Stork, senior vice president and director of TI's silicon technology development. "TI believes FRAM can change the product dynamics in embedded memory.

The company said it will use what it has learned from developing its FRAM technology for use in wireless applications. TI said broadband access, consumer electronics and its programmable DSPs were other potential markets for FRAM memory applications.

The development o the memory chip is the fruit of a multi-million dollar licensing and development agreement that TI made with Colorado Springs, Colo.-based semiconductor maker Ramtron in August 2001.

The initial FRAM test chips were produced using TI's 130nm, copper-interconnect process with only two additional mask steps. The company said the 1.5-volt chips demonstrate a much greater memory density than the SRAM cells on the same chip. At the 90nm process node, the generation where TI's first embedded FRAM products are expected to appear, the FRAM cells will be even smaller, 0.35um.

The company said other non-volatile memories such as EEPROM and Flash are more expensive to build because of the multiple mask steps they require, have longer write times, and use more power to write data.

Gaining Steam
The commercialization of FRAM memory received a significant boost in August 2000 when Ramtron signed a $65-million volume purchase agreement with Ampy Automation to supply 27 million FRAMs for the largest digital electricity meter program in the world. Cubic Corporation, an early Ramtron development partner, recently announced the availability of its new generation GO CARD, a FRAM-enabled transportation smart card that holds 32-Kilobytes (KB) of FRAM memory. The FRAM-based chip used in Cubic GO CARDs are manufactured and supplied by Fujitsu, a Ramtron licensee and foundry partner, under a royalty-bearing agreement with Ramtron. In mid-October, another royalty-bearing licensee, Samsung Electronics, announced its intent to commercialize a 4Mb FRAM memory.

In late-October, Fujitsu and ST Microelectronics announced their intent to collaborate on the development of contactless smart cards based on FRAM memory technology. Ramtron said products produced by Fujitsu for ST Microelectronics to market are also subject to royalties.

Since the beginning of 2002, Ramtron has shipped more than 14 million FRAM memory products for use in automotive navigation and entertainment systems, digital electricity meters, multi-function printers, and RAID disk controllers. The company said that's more than a 350 percent increase in unit volume, compared with the same period in 2001.

How FRAM Works
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 says it fabricates planar FRAM cells using a capacitor-on-plug approach and a 1 Transistor-1 Capacitor (1T-1C) architecture to minimize cell area. The ferroelectric capacitor is formed using Iridium electrodes and a thin Lead Zirconate Titanate (PZT) ferroelectric layer.