Pascale Mazoyer

A one transistor cell on bulk substrate (1T-Bulk) for low-cost and high density eDRAM

A 1T cell for high-density eDRAM has been successfully developed on bulk silicon substrate for the first time. The device architecture is fully compatible with CMOS logic process integration, allowing very low chip cost for SoC applications. Experimental results show a retention time over 1s at 25/spl deg/C and 100ms at 85/spl deg/C, which is compatible with eDRAM requirements. Non-destructive readout is experimentally demonstrated at 85/spl deg/C. The integration of the memory cell in a matrix arrangement is evaluated. Gate and drain disturb are characterized, showing enough disturb margins for memory operations.

Spin transfer torque (STT)-MRAM--based runtime reconfiguration FPGA circuit

As the minimum fabrication technology of CMOS transistor shrink down to 90nm or below, the high standby power has become one of the major critical issues for the SRAM-based FPGA circuit due to the increasing leakage currents in the configuration memory. The integration of MRAM in FPGA instead of SRAM is one of the most promising solutions to overcome this issue, because its nonvolatility and high write/read speed allow to power down completely the logic blocks in “idle” states in the FPGA circuit. MRAM-based FPGA promises as well as some advanced reconfiguration methods such as runtime reconfiguration and multicontext configuration. However, the conventional MRAM technology based on field-induced magnetic switching (FIMS) writing approach consumes very high power, large circuit surface and produces high disturbance between memory cells. These drawbacks prevent FIMS-MRAMs further development in memory and logic circuit. Spin transfer torque (STT)-based MRAM is then evaluated to address these issues, some design techniques and novel computing architecture for FPGA logic circuits based on STT-MRAM technology are presented in this article. By using STMicroelectronics CMOS 90nm technology and a STT-MTJ spice model, some chip characteristic results as the programming latency and power have been calculated and simulated to demonstrate the expected performance of STT-MRAM based FPGA logic circuits.

A capacitor-less DRAM cell on 75nm gate length, 16nm thin fully depleted SOI device for high density embedded memories

A capacitor-less DRAM cell on very thin film (Tsi=16nm) and short gate length (Lg=75nm) fully depleted (FD) device is demonstrated for the first time. Memory operations mechanisms are presented and retention time compatible to eDRAM requirements is measured at 85/spl deg/C. Nondestructive reading is demonstrated at 25/spl deg/C and disturb margins are deeply investigated, showing the possibility of matrix integration. This study is then extended to another type of FD device: the very promising double gate architecture.

Electrical Behavior of Phase-Change Memory Cells Based on GeTe

In this letter, we present a study on the electrical behavior of phase-change memories (PCMs) based on a GeTe active material. GeTe PCMs show, first, extremely rapid SET operation (yielding a gain of more than one decade in energy per bit with respect to standard GST PCMs), second, robust cycling, up to 1 × 105, with 30-ns SET and RESET stress time, and third, a better retention behavior at high temperature with respect to GST PCMs. These results, obtained on single cells, suggest GeTe as a promising alternative material to standard GST to improve PCM performance and reliability.

50 nm-Gate All Around (GAA)-Silicon On Nothing (SON)-devices: a simple way to co-integration of GAA transistors within bulk MOSFET process

For the first time, both GAA and bulk devices were shown to be operational on the same chip. Not all issues have been solved yet (gate materials, access resistance) but already the first-try results are very encouraging: I/sub on/=170 /spl mu/A//spl mu/m@1.2 V and gate oxide of 20 /spl Aring/. Thanks to the GAA intrinsic immunity to SCE, its DIBL was as small as 10 mV compared with 600 mV on bulk control devices. Calibrating a 2D simulator on this electrical data, the performance of the GAA was estimated to be at least 1500 /spl mu/A//spl mu/m@ 1 V with comfortable gate oxide of 20 /spl Aring/, once having corrected for the large R/sub access/ (/spl sim/3000 /spl Omega/), that was simply due to non-optimal mask layout used in this first device realization.

Design considerations and strategies for high-reliable STT-MRAM

Abstract Benefiting from Spin Transfer Torque (STT) switching approach, second generation of Magnetic RAM (MRAM) promises low power, great miniaturization prospective (

Further insight into the physics and modeling of floating-body capacitorless DRAMs

In this paper, we report on parasitic bipolar conduction occurring in floating-body effect based capacitor-less DRAMs. A way to include these effects into a previously developed model is presented. The enhanced model is then compared with electrical data realized on triple-well nMOSFET devices within the 26/spl deg/C-100/spl deg/C temperature range.

A High-Reliability, Low-Power Magnetic Full Adder

Recently, ultra-low power circuits based on logic-in magnetic tunnel junction (MTJ) memory structure have been studied thanks to its non-volatility, infinite endurance, high access speed, and easy integration with CMOS process. However, this type of circuit suffers from low reliability both in memory cell and sensing amplifier circuits, which greatly limits its practical applications for logic computation. In this paper, we present a new design of magnetic full adder (MFA) to overcome this issue based on the thermally assisted switching (TAS) MTJ cell and pre-charge sensing amplifier (PCSA) circuit. By using CMOS 65 nm design kit and a precise TAS-MTJ model, mixed simulations have been performed to demonstrate its high reliability keeping low power and small die area.

Highly performant double gate MOSFET realized with SON process

Utilizing the SON (silicon on nothing) process, highly performant double gate devices have been processed in a planar configuration. Two families of devices were obtained (high performance and low power) with very high Ion/Ioff trade off. Drive currents of 1954 /spl mu/A//spl mu/m (Ioff = 283 nA//spl mu/m) and 1333 /spl mu/A//spl mu/m (Ioff = 1 nA//spl mu/m) are obtained at 1.2 V with Tox = 20 /spl Aring/ and Lgate = 70 nm. DIBL is very well controlled, measured below 60 mV for gates as short as 40 nm. These features place our devices among the most performant ever reported.

An 8 Mbit DRAM design using a 1 Tbulk cell

An 8 Mbit memory chip featuring a floating body one transistor cell on bulk substrate is characterized for the first time. A high-speed and high accuracy current sense-amplifier with a large common mode reference current is proposed. It achieves a reading time of 10 ns and a current read margin lower than 5 /spl mu/A. A bit fail rate of 0.017% was measured on a 1 Mbit module. Data retention shows that 1 Tbulk cell concept has the potential to be used as a future eDRAM memory cell.