유연 반도체/메모리 소자 기술

안종현,이혁,좌성훈,Ahn, Jong-Hyun,Lee, Hyouk,Choa, Sung-Hoon 한국마이크로전자및패키징학회 2013 마이크로전자 및 패키징학회지 Vol.20 No.2

Recently flexible electronic devices have attracted a great deal of attention because of new application possibilities including flexible display, flexible memory, flexible solar cell and flexible sensor. In particular, development of flexible memory is essential to complete the flexible integrated systems such as flexible smart phone and wearable computer. Research of flexible memory has primarily focused on organic-based materials. However, organic flexible memory has still several disadvantages, including lower electrical performance and long-term reliability. Therefore, emerging research in flexible electronics seeks to develop flexible and stretchable technologies that offer the high performance of conventional wafer-based devices as well as superior flexibility. Development of flexible memory with inorganic silicon materials is based on the design principle that any material, in sufficiently thin form, is flexible and bendable since the bending strain is directly proportional to thickness. This article reviews progress in recent technologies for flexible memory and flexible electronics with inorganic silicon materials, including transfer printing technology, wavy or serpentine interconnection structure for reducing strain, and wafer thinning technology.

Nano-Floating Gate Memory Devices

Jang-Sik Lee 대한금속·재료학회 2011 ELECTRONIC MATERIALS LETTERS Vol.7 No.3

In recent decades, memory device technology has advanced through active research and the development of innovative technologies. Single transistor-based flash memory device is one of the most widely used forms of memory devices because their device structure is simple and the scaling is feasible. A nano-floating gate memory (NFGM) device is a kind of flash memory devices that uses nanocrystals as a charge-trapping element. The use of nanocrystals has advantages over memory devices that rely on other methods such as discontinuous trap sites and controllable trap levels. Nowadays considerable progress has been made in the field of NFGM devices, and novel application areas have been explored extensively. This review article focuses on new technologies that are advancing these developments. The discussion highlights recent efforts and research activities regarding the fabrication and characterization of nonvolatile memory devices that use a nanocrystal layer asa charge-trapping element. The review concludes with an analysis of device fabrication strategies and device architectures of NFGM devices for possible applicationto devices that are organic, printed, and flexible.

Flexible Organic Transistor Memory Devices

Kim, Soo-Jin,Lee, Jang-Sik American Chemical Society 2010 NANO LETTERS Vol.10 No.8

<P>The flexible nonvolatile organic memory devices were developed on the plastic substrates based on the organic thin-film transistors embedding self-assembled gold nanoparticles (Au<SUB>NP</SUB>). The organic memory devices exhibited good programmable memory characteristics with respect to the program/erase operations, resulting in controllable and reliable threshold voltage shifts. Additionally, the endurance, data retention, and bending cyclic measurements confirmed that the flexible memory devices exhibited good electrical reliability as well as mechanical stability. The memory devices were composed of the solution-processed organic dielectric layers/metallic nanoparticles and the low-temperature processed organic transistors. Therefore, this approach could potentially be applied to advanced flexible/plastic electronic devices as well as integrated organic device circuits.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/nalefd/2010/nalefd.2010.10.issue-8/nl1009662/production/images/medium/nl-2010-009662_0004.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/nl1009662'>ACS Electronic Supporting Info</A></P>

Flexible Organic Memory Devices with Multilayer Graphene Electrodes

Ji, Yongsung,Lee, Sangchul,Cho, Byungjin,Song, Sunghoon,Lee, Takhee American Chemical Society 2011 ACS NANO Vol.5 No.7

<P>We fabricated 8 × 8 cross-bar array-type flexible organic resistive memory devices with transparent multilayer graphene (MLG) electrodes on a poly(ethylene terephthalate) substrate. The active layer of the memory devices is a composite of polyimide and 6-phenyl-C61 butyric acid methyl ester. The sheet resistance of the MLG film on memory device was found to be ∼270 Ω/◻, and the transmittance of separated MLG film from memory device was ∼92%. The memory devices showed typical write-once-read-many (WORM) characteristics and an ON/OFF ratio of over ∼10<SUP>6</SUP>. The memory devices also exhibited outstanding cell-to-cell uniformity with flexibility. There was no substantial variation observed in the current levels of the WORM memory devices upon bending and bending cycling up to 10 000 times. A retention time of over 10<SUP>4</SUP> s was observed without fluctuation under bending.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/ancac3/2011/ancac3.2011.5.issue-7/nn201770s/production/images/medium/nn-2011-01770s_0002.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/nn201770s'>ACS Electronic Supporting Info</A></P>

A Flexible Programmable Memory BIST for Embedded Single-Port Memory and Dual-Port Memory

박영규,강성호,김홍식,최인혁 한국전자통신연구원 2013 ETRI Journal Vol.35 No.5

Programmable memory built-in self-test (PMBIST) is an attractive approach for testing embedded memory. However, the main difficulties of the previous works are the large area overhead and low flexibility. To overcome these problems, a new flexible PMBIST (FPMBIST) architecture that can test both single-port memory and dual-port memory using various test algorithms is proposed. In the FPMBIST, a new instruction set is developed to minimize the FPMBIST area overhead and to maximize the flexibility. In addition, FPMBIST includes a diagnostic scheme that can improve the yield by supporting three types of diagnostic methods for repair and diagnosis. The experiment results show that the proposed FPMBIST has small area overhead despite the fact that it supports various test algorithms, thus having high flexibility.

Recent Advance of Flexible Organic Memory Device

Kim, Jaeyong,Hung, Tran Quang,Kim, Choongik The Institute of Semiconductor Engineers 2020 Journal of semiconductor engineering Vol.1 No.1

With the recent emergence of foldable electronic devices, interest in flexible organic memory is significantly growing. There are three types of flexible organic memory that have been researched so far: floating-gate (FG) memory, ferroelectric field-effect-transistor (FeFET) memory, and resistive memory. Herein, performance parameters and operation mechanisms of each type of memory device are introduced, along with a brief summarization of recent research progress in flexible organic memory.

Flexible Nanoporous WO_3–<i>x</i> Nonvolatile Memory Device

Ji, Yongsung,Yang, Yang,Lee, Seoung-Ki,Ruan, Gedeng,Kim, Tae-Wook,Fei, Huilong,Lee, Seung-Hoon,Kim, Dong-Yu,Yoon, Jongwon,Tour, James M. American Chemical Society 2016 ACS NANO Vol.10 No.8

<P>Flexible resistive random access memory (RRAM) devices have attracted great interest for future nonvolatile memories. However, making active layer films at high temperature can be a hindrance to RRAM device fabrication on flexible substrates. Here, we introduced a flexible nanoporous (NP) WO3-x RRAM device using anodic treatment in a room-temperature process. The flexible NP WO3-x RRAM device showed bipolar switching characteristics and a high I-ON/IOFF ratio of similar to 10(5). The device also showed stable retention time over 5 X 10(5) s, outstanding cell-to-cell uniformity, and bending endurance over 10(3) cycles when maximum bending conditions.</P>

Direct Observation of a Carbon Filament in Water-Resistant Organic Memory

Lee, Byung-Hyun,Bae, Hagyoul,Seong, Hyejeong,Lee, Dong-Il,Park, Hongkeun,Choi, Young Joo,Im, Sung-Gap,Kim, Sang Ouk,Choi, Yang-Kyu American Chemical Society 2015 ACS NANO Vol.9 No.7

<P>The memory for the Internet of Things (IoT) requires versatile characteristics such as flexibility, wearability, and stability in outdoor environments. Resistive random access memory (RRAM) to harness a simple structure and organic material with good flexibility can be an attractive candidate for IoT memory. However, its solution-oriented process and unclear switching mechanism are critical problems. Here we demonstrate iCVD polymer-intercalated RRAM (i-RRAM). i-RRAM exhibits robust flexibility and versatile wearability on any substrate. Stable operation of i-RRAM, even in water, is demonstrated, which is the first experimental presentation of water-resistant organic memory without any waterproof protection package. Moreover, the direct observation of a carbon filament is also reported for the first time using transmission electron microscopy, which puts an end to the controversy surrounding the switching mechanism. Therefore, reproducibility is feasible through comprehensive modeling. Furthermore, a carbon filament is superior to a metal filament in terms of the design window and selection of the electrode material. These results suggest an alternative to solve the critical issues of organic RRAM and an optimized memory type suitable for the IoT era.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/ancac3/2015/ancac3.2015.9.issue-7/acsnano.5b02199/production/images/medium/nn-2015-021997_0007.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/nn5b02199'>ACS Electronic Supporting Info</A></P>

Non-volatile ferroelectric memory with position-addressable polymer semiconducting nanowire.

Hwang, Sun Kak,Min, Sung-Yong,Bae, Insung,Cho, Suk Man,Kim, Kang Lib,Lee, Tae-Woo,Park, Cheolmin Wiley 2014 Small Vol. No.

<P>One-dimensional nanowires (NWs) have been extensively examined for numerous potential nano-electronic device applications such as transistors, sensors, memories, and photodetectors. The ferroelectric-gate field effect transistors (Fe-FETs) with semiconducting NWs in particular in combination with ferroelectric polymers as gate insulating layers have attracted great attention because of their potential in high density memory integration. However, most of the devices still suffer from low yield of devices mainly due to the ill-control of the location of NWs on a substrate. NWs randomly deposited on a substrate from solution-dispersed droplet made it extremely difficult to fabricate arrays of NW Fe-FETs. Moreover, rigid inorganic NWs were rarely applicable for flexible non-volatile memories. Here, we present the NW Fe-FETs with position-addressable polymer semiconducting NWs. Polymer NWs precisely controlled in both location and number between source and drain electrode were achieved by direct electrohydrodynamic NW printing. The polymer NW Fe-FETs with a ferroelectric poly(vinylidene fluoride-co-trifluoroethylene) exhibited non-volatile ON/OFF current margin at zero gate voltage of approximately 10(2) with time-dependent data retention and read/write endurance of more than 10(4) seconds and 10(2) cycles, respectively. Furthermore, our device showed characteristic bistable current hysteresis curves when being deformed with various bending radii and multiple bending cycles over 1000 times.</P>

Thin reduced graphene oxide interlayer with a conjugated block copolymer for high performance non-volatile ferroelectric polymer memory

Velusamy, D.B.,Kim, R.H.,Takaishi, K.,Muto, T.,Hashizume, D.,Lee, S.,Uchiyama, M.,Aoyama, T.,Ribierre, J.C.,Park, C. Elsevier Science 2014 Organic electronics Vol.15 No.11

Polymer ferroelectric-gate field effect transistors (Fe-FETs) employing ferroelectric polymer thin films as gate insulators are highly attractive as a next-generation non-volatile memory. For minimizing gate leakage current of a device which arises from electrically defective ferroelectric polymer layer in particular at low operation voltage, the materials design of interlayers between the ferroelectric insulator and gate electrode is essential. Here, we introduce a new solution-processed interlayer of conductive reduced graphene oxides (rGOs) modified with a conjugated block copolymer, poly(styrene-block-paraphenylene) (PS-b-PPP). A FeFET with a solution-processed p-type oligomeric semiconducting channel and ferroelectric poly(vinylidene fluoride-co-trifluoroethylene) (PVDF-TrFE) insulator exhibited characteristic source-drain current hysteresis arising from ferroelectric polarization switching of a PVDF-TrFE insulator. Our PS-b-PPP modified rGOs (PMrGOs) with conductive moieties embedded in insulating polymer matrix not only significantly reduced the gate leakage current but also efficiently lowered operation voltage of the device. In consequence, the device showed large memory gate voltage window and high ON/OFF source-drain current ratio with excellent data retention and read/write cycle endurance. Furthermore, our PMrGOs interlayers were successfully employed to FeFETs fabricated on mechanically flexible substrates with promising non-volatile memory performance under repetitive bending deformation.