IMEC Industrial Affiliation Program Focuses Research on Embedded RAM

7/13/2004 - IMEC invites industrial partners and research centers to participate in a new IMEC industrial affiliation program (IIAP) on embedded RAM concepts for second and higher levels of on-chip cache memory. The research program, which focuses on the 45nm node and below, addresses three concepts: 1) direct tunneling RAM; (2) ferroelectric field effect transistor; and, 3) floating body cell. The three concepts will be implemented in silicon by year-end to demonstrate their feasibility.

The first concept of direct-tunneling RAM uses a very thin (~1.5nm) oxide Flash structure in which charge can be stored on either a floating gate or on a charge-trapping layer. In both cases, the use of high-k materials is being considered as well to lower the write/erase voltages. First simulation results of the expected threshold voltage window for different combinations of voltages and tunnel oxide thicknesses, as obtained from IMEC's tunneling model, evidence the feasibility of a 10ns programming time at the 45nm node.

The second concept, the ferroelectric field effect transistor (FeFET) recently regained a lot of attention because of its superior scalability as compared to the capacitor-based ferroelectric RAM. Also here, the advantage of using high-k materials is substantial since they can be used as a buffer layer between the channel and the ferroelectric in order to lower the write/erase voltages.

The third concept is based on the floating body cell, a concept based on the memory effect in silicon-on-insulator (SOI) devices initially developed at IMEC already back in 1988. The technology is being adapted for planar as well as FinFET device structures. Preliminary retention results, obtained on partially depleted SOI MOSFETs programmed by impact ionization, show the memory effect in scaled-down SOI technology.

In all of these cases, IMEC has a longstanding background and expertise guaranteeing that results can be generated within a very short time frame of six to 18 months. The eRAM project complements IMEC's Flash memory project which started in 2000.

IMEC's eRAM program has been started in order to answer the urgent need for a new embedded RAM concept for second and higher levels of on-chip cache memory. Fast first-level cache memory which has been, and probably will continue to be, addressed by static RAMs are reaching their scaling limits already today due to their drastic increase in relative cell size. Since most IC applications (ie, micro's, systems-on-chip, telecom) will need relatively large amounts of on-chip memory, their footprint is expected to increase to 80-90% of the chip area in some of these major applications. At the same time, embedded dynamic RAM has never been widely accepted as a mainstream technology option because of limited availability, process complexity and cost issues.

The technology that is being developed within IMEC's program neither aims to replace the first-level cache (SRAM), nor the (eventual) embedded non-volatile Flash or read-only memory (ROM) blocks. Rather the large blocks of volatile memory required in future applications are targeted in order to reduce overall memory footprints and hence realize huge cost savings for a wide range of IC products.

The eRAM IIAP is a complementary research program to IMEC's Flash Memory IIAP (running since 2000) within IMEC's newly established Advanced Memory Program. IMEC is inviting participation in the program by leading IC manufacturers. IMEC Industrial Affiliation programs offer partners the advantages of both reduced costs and early process knowledge.

About IMEC
IMEC is a world leading independent research center in nanoelectronics and nanotechnology. Its research focuses on the next generations of chips and systems, and on the enabling technologies for ambient intelligence. IMEC's research bridges the gap between fundamental research at universities and technology development in industry. Its unique balance of processing and system know-how, intellectual property portfolio, state-of-the-art infrastructure and a strong network of companies, universities and research institutes worldwide, positions IMEC as a key partner with which to develop and improve technologies for future systems.

IMEC is headquartered in Leuven, Belgium and has representatives in the US, China and Japan. Its staff of more than 1300 people includes over 380 industrial residents and guest researchers. In 2003, its revenues were EUR 145 million. Further information on IMEC can be found at

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