Network


Latest external collaboration on country level. Dive into details by clicking on the dots.

Hotspot


Dive into the research topics where Dongna Shen is active.

Publication


Featured researches published by Dongna Shen.


Journal of Applied Physics | 2014

Perpendicular spin transfer torque magnetic random access memories with high spin torque efficiency and thermal stability for embedded applications (invited)

Luc Thomas; Guenole Jan; Jian Zhu; Huanlong Liu; Yuan-Jen Lee; Ru-Ying Tong; Keyu Pi; Yu-Jen Wang; Dongna Shen; Renren He; Jesmin Haq; Jeffrey Teng; Vinh Lam; Kenlin Huang; Tom Zhong; Terry Torng; Po-Kang Wang

Magnetic random access memories based on the spin transfer torque phenomenon (STT-MRAMs) have become one of the leading candidates for next generation memory applications. Among the many attractive features of this technology are its potential for high speed and endurance, read signal margin, low power consumption, scalability, and non-volatility. In this paper, we discuss our recent results on perpendicular STT-MRAM stack designs that show STT efficiency higher than 5 kBT/μA, energy barriers higher than 100 kBT at room temperature for sub-40 nm diameter devices, and tunnel magnetoresistance higher than 150%. We use both single device data and results from 8 Mb array to demonstrate data retention sufficient for automotive applications. Moreover, we also demonstrate for the first time thermal stability up to 400 °C exceeding the requirement of Si CMOS back-end processing, thus opening the realm of non-volatile embedded memory to STT-MRAM technology.


symposium on vlsi technology | 2014

Demonstration of fully functional 8Mb perpendicular STT-MRAM chips with sub-5ns writing for non-volatile embedded memories

Guenole Jan; Luc Thomas; Yuan-Jen Lee; Huanlong Liu; Jian Zhu; Ru-Ying Tong; Keyu Pi; Yu-Jen Wang; Dongna Shen; Renren He; Jesmin Haq; Jeffrey Teng; Vinh Lam; Kenlin Huang; Tom Zhong; Terry Torng; Po-Kang Wang

We present major breakthroughs in MTJ design for STT-MRAM applications allowing reliable write for pulse lengths down to 1.5ns, data retention up to 125°C for 10 years and full compatibility with BEOL process up to 400°C for 1 hour. We have successfully integrated the novel structure onto an 8Mbit test chip. We demonstrate writing of every single cell in the array using sub-5ns pulses over a wide temperature range without using any error correction. We also show that sensing times of 4ns are sufficient to read every data cell. The inherent scalability of the design makes it a prime candidate for universal embedded non-volatile memories down to the 28nm node and beyond.


international electron devices meeting | 2015

Fully functional perpendicular STT-MRAM macro embedded in 40 nm logic for energy-efficient IOT applications

Yu Lu; Tom Zhong; W.N. Hsu; S. Kim; X. Lu; J. J. Kan; C. Park; W.C. Chen; X. Li; X. Zhu; P. Wang; M. Gottwald; J. Fatehi; L. Seward; Jonghae Kim; N. Yu; Guenole Jan; Jesmin Haq; Y. J. Wang; Luc Thomas; Jian Zhu; Huanlong Liu; Yuan-Jen Lee; Ru-Ying Tong; Keyu Pi; Dongna Shen; Renren He; Zhongjian Teng; Vinh Lam; Rao Annapragada

We present for the first time a fully functional 40 nm perpendicular STT-MRAM macro (1 Mb, ×32/×64 IO) embedded into a foundry standard CMOS logic platform. We achieved target design specifications of 20 ns read access time and 20-100 ns write cycle time without redundancy repair at standard core and IO voltages. The full 1 Mb macro can be switched reliably with write pulse as short as 6 ns, which results in full-chip write power of ~ 3.2 μW/Mbps at ×64. This is the lowest eNVM write power reported at a full-chip level and about three orders of magnitude smaller than that of eFLASH. The 0.5 Mbit high-density bitcell array also demonstrates good Rp distribution and 100 % STT switching. Our results demonstrate superior power-area-feature attributes of perpendicular STT-MRAM as a best-in-class unified eNVM solution for Internet-of-Things (IOT) applications at 40 nm as well as the scalability of these advantages to 28 nm and beyond.


international electron devices meeting | 2015

Solving the paradox of the inconsistent size dependence of thermal stability at device and chip-level in perpendicular STT-MRAM

Luc Thomas; Guenole Jan; Yuan-Jen Lee; Huanlong Liu; Jian Zhu; Santiago Serrano-Guisan; Ru-Ying Tong; Keyu Pi; Dongna Shen; Renren He; Jesmin Haq; Zhongjian Teng; Rao Annapragada; Vinh Lam; Yu-Jen Wang; Tom Zhong; Terry Torng; Po-Kang Wang

Current understanding of thermal stability of perpendicular STT-MRAM based on device-level data suggests that the thermal stability factor A is almost independent of device diameter above ~30nm. Here we report that contrary to this conventional wisdom, chip-level data retention exhibits substantial size dependence for diameters between 55 and 100 nm. We show that the method widely used to measure A is inaccurate for devices larger than ~30 nm, leading to significant underestimation of the size dependence. We derive an improved model, allowing us to reconcile the size dependence of A measured at device and chip level.


symposium on vlsi technology | 2016

Achieving Sub-ns switching of STT-MRAM for future embedded LLC applications through improvement of nucleation and propagation switching mechanisms

Guenole Jan; Luc Thomas; Yuan-Jen Lee; Huanlong Liu; Jian Zhu; Jodi Iwata-Harms; Sahil Patel; Ru-Ying Tong; Santiago Serrano-Guisan; Dongna Shen; Renren He; Jesmin Haq; Jeffrey Teng; Vinh Lam; Rao Annapragada; Yu-Jen Wang; Tom Zhong; Terry Torng; Po-Kang Wang

We present recent advances in writing speed of pSTT_MRAM which demonstrate its potential as a candidate for replacement of LCC cache for advanced technology nodes as well as applications where non-volatility may be needed. In this paper we explore the feasibility of sub-ns switching of devices and their characterization using comprehensive time resolved electrical measurement of the reversal mechanism. We show that the switching mechanism can be described as a simple nucleation followed by propagation model that can be characterized statistically. We further demonstrate that after optimization of the Magnetic Tunnel Junction (MTJ) stack, single devices can be switched reliably using write pulse length down to 750ps while preserving functionality and data retention @ 125°C. Results of the integration at array level on an 8MB test vehicle are also presented allowing full array writing using 3ns pulses without ECC and demonstrated data retention of 10 years (1ppm) at 125°C.


symposium on vlsi technology | 2015

Demonstration of an MgO based anti-fuse OTP design integrated with a fully functional STT-MRAM at the Mbit level

Guenole Jan; Luc Thomas; Yuan-Jen Lee; Huanlong Liu; Jian Zhu; Ru-Ying Tong; Keyu Pi; Yu-Jen Wang; Dongna Shen; Renren He; Jesmin Haq; Jeffrey Teng; Vinh Lam; Rao Annapragada; Tom Zhong; Terry Torng; Po-Kang Wang

STT-MRAM technology has been attracting renewed attention since the embedability of a working STT-MRAM design has been demonstrated [1]. In this paper we expand on the versatility of STT-MRAM by demonstrating the conversion of a standard STT-MRAM cell to a One Time Programmable (OTP) anti-fuse cell. Both designs are integrated at the Mbit level on a single chip using the same magnetic stack, processing and CMOS cell design. A single BEOL mask change can convert an STT-MRAM device to an OTP design by simply reducing its size. The increased resistance yields larger voltage drop across the device, due to the voltage divider effect in the 1T-1MTJ cell and is sufficient to trigger reliable dielectric breakdown of the oxide tunnel barrier, effectively shorting the device. In this paper we demonstrate the seamless integration of an OTP based on STT-MRAM and 100% programming and reading yield at the Mbit level.


international electron devices meeting | 2017

Probing magnetic properties of STT-MRAM devices down to sub-20 nm using spin-torque FMR

Luc Thomas; Guenole Jan; Santiago Serrano-Guisan; Yuan-Jen Lee; Huanlong Liu; Jian Zhu; Jodi Iwata-Harms; Ru-Ying Tong; Sahil Patel; Vignesh Sundar; Dongna Shen; Yi Yang; Renren He; Jesmin Haq; Zhongjian Teng; Vinh Lam; Paul Liu; Yu-Jen Wang; Tom Zhong; Po-Kang Wang


Archive | 2015

MTJ Etching with Improved Uniformity and Profile by Adding Passivation Step

Dongna Shen; Yu-Jen Wang; Jesmin Haq


Archive | 2018

MTJ device process/integration method with pre-patterned seed layer

Jesmin Haq; Tom Zhong; Zhongjian Teng; Dongna Shen


ieee soi 3d subthreshold microelectronics technology unified conference | 2017

STT-MRAM for embedded memory applications from eNVM to last level cache

Luc Thomas; Guenole Jan; Santiago Serrano-Guisan; Yuan-Jen Lee; Huanlong Liu; Jian Zhu; Jodi Iwata-Harms; Ru-Ying Tong; Sahil Patel; Vignesh Sundar; Dongna Shen; Yi Yang; Renren He; Jesmin Haq; Zhongjian Teng; Vinh Lam; Paul Liu; Yu-Jen Wang; Tom Zhong; Po-Kang Wang

Collaboration


Dive into the Dongna Shen's collaboration.

Top Co-Authors

Avatar

Jesmin Haq

Arizona State University

View shared research outputs
Top Co-Authors

Avatar

Yu-Jen Wang

University of Delaware

View shared research outputs
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Researchain Logo
Decentralizing Knowledge