Eight-bit CPU with Nonvolatile Registers Capable of Holding Data for 40 Days at 85°C Using Crystalline In-Ga-Zn Oxide Thin Film Transistors

Ohmaru, Takuro; Yoneda, Seiichi; Nishijima, T.; Masami, E.; Dembo, H.; Fujita, Masashi; Kobayashi, Hidetomo; Ohshima, Kazuaki; Atsumi, Tomoaki; Shionoiri, Yutaka; Kimura, Kiyoshi; Maehashi, Yukio; Koyama, Jun; Yamazaki, Shunpei

doi:10.7567/ssdm.2012.j-5-2

Cited by 31 publications

(26 citation statements)

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“…7,8 We have demonstrated its applicability to various products such as low-power displays, non-volatile memory devices, and large-scale integrations (LSIs). [9][10][11][12][13][14][15] It is noted that the c-axis-aligned crystal (CAAC)-IGZO technology has been already commercialized in a mass production for low-power applications. Figure 1 is a cross-sectional transmission electron microscope (TEM) image of the CAAC-IGZO film used for a channel in a TFT in a smartphone.…”

Section: Introductionmentioning

confidence: 99%

Back‐channel‐etched thin‐film transistor using c‐axis‐aligned crystal In–Ga–Zn oxide

et al. 2014

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Our crystalline In–Ga–Zn oxide (IGZO) thin film has a c‐axis‐aligned crystal (CAAC) structure and maintains crystallinity even on an amorphous base layer. Although the crystal has c‐axis alignment, its a‐axis and b‐axis have random arrangement; moreover, a clear grain boundary is not observed. We fabricated a back‐channel‐etched thin‐film transistor (TFT) using the CAAC‐IGZO film. Using the CAAC‐IGZO film, more stable TFT characteristics, even with a short channel length, can be obtained, and the instability of the back channel, which is one of the biggest problems of IGZO TFTs, is solved. As a result, we improved the process of manufacturing back‐channel‐etched TFTs.

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Section: Introductionmentioning

confidence: 99%

Back‐channel‐etched thin‐film transistor using c‐axis‐aligned crystal In–Ga–Zn oxide

et al. 2014

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“…As mentioned previously, CAAC‐IGZO has an extremely low I off. This feature helps realize memory that utilizes OSFETs with long retention time and a logic circuit with OSFETs that performs normally off operation; that is, the power is interrupted in a standby state …”

Section: Universal Memorymentioning

confidence: 99%

“…This feature helps realize memory that utilizes OSFETs with long retention time and a logic circuit with OSFETs that performs normally off operation; that is, the power is interrupted in a standby state. 3,11 F I G U R E 1 Hardware and software configuration for artificial intelligence (AI) Memory access occurs frequently in AI operations. However, nonvolatile memory including other materials, such as resistive RAM (ReRAM) 12 and magnetoresistive RAM (MRAM), 13 has poor write endurance.…”

Section: Universal Memorymentioning

confidence: 99%

Crystalline IGZO ceramics (crystalline oxide semiconductor)–based devices for artificial intelligence

Yamazaki

Ohshita

Oota

et al. 2019

Int J Ceramic Engine & Sci

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In 2009, a crystalline oxide semiconductor with a layered structure, which we refer to as c‐axis–aligned crystalline indium‐gallium‐zinc oxide (CAAC‐IGZO), was first discovered. CAAC‐IGZO has a peculiar crystal structure in which clear grain boundaries are not observed despite high c‐axis alignment and absence of a‐b plane alignment. When compared to a Si field‐effect transistor (FET), a metal‐oxide‐semiconductor (MOS) FET, utilizing CAAC‐IGZO, presents lower off‐state current (on the order of yA [10−24 A]). These unique characteristics allow CAAC‐IGZO to realize devices with low power consumption. With the emerging era of artificial intelligence, wherein power saving becomes more significant, CAAC‐IGZO has attracted attention as a potential replacement for Si. This paper describes the characteristics and potentials of CAAC‐IGZO for the development of memory devices with unprecedented functions.

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“…For example, displays [12]- [15], large scale integrations such as memories [16]- [20], CPUs [21]- [26], and FPGAs [1], [2], [27]- [31], and image sensors [32]- [36] have been reported to exhibit a variety of features that can be achieved with CAAC-IGZO FETs, e.g., low power consumption and additional functions owing to the ultralow leakage. A multicontext (MC) FPGA that includes nonvolatile configuration memory with a CAAC-IGZO FET (CAAC-IGZO FPGA) [1], [2], [27]- [31] features the following characteristics: 1) fine-grained power gating (PG) [27] capable of controlling power supply to individual PLEs; 2) MC architecture [28] capable of fast configuration switching; 3) data load/store between a volatile register and its dedicated nonvolatile shadow register before and after power shutoff by fine-grained PG [29]; 4) normally OFF driving [29] to support these functions.…”

Section: Introductionmentioning

confidence: 99%

Subthreshold Operation of CAAC-IGZO FPGA by Overdriving of Programmable Routing Switch and Programmable Power Switch

Kozuma

Okamoto

Nakagawa

et al. 2017

IEEE Trans. VLSI Syst.

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A field-programmable gate array (FPGA) using a crystalline oxide semiconductor of c-axis-aligned crystal indium-gallium-zinc oxide (CAAC-IGZO) has been developed, which is capable of subthreshold operation used for energy harvesting. To achieve subthreshold operation, the CAAC-IGZO FPGA has a structure designed as an extension of a boosting pass gate using a CAAC-IGZO FET and employs overdriving of a programmable routing switch and a programmable power switch for power gating (PG). A CAAC-IGZO FET is used to give an ideal floating gate with excellent charge retention. A chip fabricated using a 0.8-µm CAAC-IGZO/ 0.18-µm CMOS hybrid process achieves subthreshold operation while maintaining the features required for normally off computing proposed in our previous study. Specifically, these features are realized by fine-grained PG for individual programmable logic elements (PLEs), fast configuration switching between contexts, and load/store between a volatile register and a nonvolatile shadow register in the PLEs. The chip operation at a minimum operating voltage of 180 mV with a combinational circuit configuration is demonstrated. With a sequential circuit configuration, the chip operates at a minimum operating voltage of 190 mV with 12.5 kHz, and the minimum power-delay product is 3.40 pJ/operation at 330 mV.Index Terms-c-axis-aligned crystal indium-gallium-zinc oxide (CAAC-IGZO), crystalline oxide semiconductor, fieldprogrammable gate array (FPGA), low voltage, multicontext (MC), nonvolatile memory, nonvolatile shadow register, normally OFF computing, power gating (PG), subthreshold operation.

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Eight-bit CPU with Nonvolatile Registers Capable of Holding Data for 40 Days at 85°C Using Crystalline In-Ga-Zn Oxide Thin Film Transistors

Cited by 31 publications

References 0 publications

Back‐channel‐etched thin‐film transistor using c‐axis‐aligned crystal In–Ga–Zn oxide

Back‐channel‐etched thin‐film transistor using c‐axis‐aligned crystal In–Ga–Zn oxide

Crystalline IGZO ceramics (crystalline oxide semiconductor)–based devices for artificial intelligence

Subthreshold Operation of CAAC-IGZO FPGA by Overdriving of Programmable Routing Switch and Programmable Power Switch

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