Overlay of semi-dried functional layers in offset printing for rapid and high-precision fabrication of flexible TFTs

Kusaka, Yasuyuki; Sugihara, Kazuyoshi; Koutake, Masayoshi; Ushijima, Hirobumi

doi:10.1088/0960-1317/24/3/035020

Cited by 45 publications

(66 citation statements)

References 19 publications

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“…Reverse‐Offset Printing : Roll‐to‐plate reverse‐offset printing was performed using a printing unit that was equipped with an overlay camera system . PDMS (TI‐7400ES, Advanced Nano Products Ltd., Korea) was cleaned using ethanol and treated using oxygen plasma (PDC210, Yamato Scientific Co. Ltd., Japan) with 20 s/50 SCCM O 2 flow/200 W to improve wetting of the ink prior each printing experiment.…”

Section: Methodsmentioning

confidence: 99%

Reverse‐Offset Printing of Metal‐Nitrate‐Based Metal Oxide Semiconductor Ink for Flexible TFTs

Leppäniemi

Sneck

Kusaka

et al. 2019

Adv Elect Materials

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Reverse‐offset printing (ROP) is a novel printing technique capable of forming electronics‐industry‐relevant linewidths (≈1 µm) with good thickness control and sharp edge definition. It is demonstrated that through a controlled oxygen‐plasma treatment, the energy of the surfaces related to the process steps of ROP can be optimized to allow the patterning of metal‐oxide semiconductor layers using a simple printing ink based on metal nitrates dissolved in an organic solvent. The steps of the ROP process are analyzed using surface‐energy measurements and Fourier transform infrared spectra of the ink during drying. Thin‐film transistors (TFTs) fabricated using a roll‐to‐plate ROP of In2O3 semiconductor and evaporated Al source/drain (S/D) contacts show, on average, mobilities of 3.1 and 3.5 cm2 V−1 s−1, and ON/OFF‐ratios up to 108 and 107 on a Si/SiO2 substrate and on a flexible polyimide‐type substrate, respectively. TFTs on the flexible substrate with also the S/D‐contacts printed with ROP using Ag nanoparticle ink exhibit a 1.4 cm2 V−1 s−1 mobility. To demonstrate the scalability of the process, continuous lines of In2O3 are printed using a roll‐to‐roll‐compatible (R2R) ROP with linewidths down to ≈2 µm. This process is expected to lead to miniaturized metal‐oxide circuits as required by flexible high‐resolution sensor arrays and displays.

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Section: Methodsmentioning

confidence: 99%

Reverse‐Offset Printing of Metal‐Nitrate‐Based Metal Oxide Semiconductor Ink for Flexible TFTs

Leppäniemi

Sneck

Kusaka

et al. 2019

Adv Elect Materials

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“…They fabricated top‐gate and bottom‐contact organic TFTs with poly(3‐hexylthiophene) as a polymer semiconducting layer; their TFTs with channel lengths of 5 µm exhibited mobilities of 0.017 cm 2 V −1 s −1 in the saturation region . Ushijima and coworkers also reported organic TFTs with reverse‐offset printed silver source/drain electrodes . They developed a wet‐on‐wet printing process wherein a subsequent layer can be printed on a previous semi‐dried (non‐sintered) layer.…”

Section: High‐resolution Printing Technologiesmentioning

confidence: 99%

Recent Progress in the Development of Printed Thin‐Film Transistors and Circuits with High‐Resolution Printing Technology

2016

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Printed electronics enable the fabrication of large‐scale, low‐cost electronic devices and systems, and thus offer significant possibilities in terms of developing new electronics/optics applications in various fields. Almost all electronic applications require information processing using logic circuits. Hence, realizing the high‐speed operation of logic circuits is also important for printed devices. This report summarizes recent progress in the development of printed thin‐film transistors (TFTs) and integrated circuits in terms of materials, printing technologies, and applications. The first part of this report gives an overview of the development of functional inks such as semiconductors, electrodes, and dielectrics. The second part discusses high‐resolution printing technologies and strategies to enable high‐resolution patterning. The main focus of this report is on obtaining printed electrodes with high‐resolution patterning and the electrical performance of printed TFTs using such printed electrodes. In the final part, some applications of printed electronics are introduced to exemplify their potential.

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“…To avoid this, we developed a Wet-on-Wet (WoW) process wherein a subsequent layer can be printed on a previous semi-dried (not-sintered) layer without the sintering process ( Fig. 2(a)) [3]. For example, a TFT consists of at least four layers including the gate, insulator, source/drain, and semiconductors; therefore, four sintering steps should be done in the conventional ROP method.…”

Section: A Wet-on-wet Processmentioning

confidence: 99%

High resolution printing processes with high throughput, enhanced step coverage, and high design flexibility

Kusaka

Ushijima

2016

2016 International Conference on Electronics Packaging (ICEP)

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Reverse offset printing and microcontact printing are fascinating methods for fabricating fine patterns because both of them can attain a 1-µm/1-µm line-and-space resolution, and the resulting patterns manifest uniform layer-thicknesses irrespective of the pattern sizes. However, the printed pattern has very sharp edges; therefore, the step-coverage of subsequent overlying layers has often been a severe problem. Further, as reverse offset printing and microcontact printing use an engraved glass and a stamp, respectively, the pattern design is restricted because of bottom-contact-type defects. Thermal sintering of the printed patterns also leads to a longer processing time. To address these problems, we have developed several complementary processes. In this presentation, wet-on-wet, electrode-embedding, and push-pull processes and a newly developed high-resolution planographic method called adhesion contrast planography are discussed.

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Overlay of semi-dried functional layers in offset printing for rapid and high-precision fabrication of flexible TFTs

Cited by 45 publications

References 19 publications

Reverse‐Offset Printing of Metal‐Nitrate‐Based Metal Oxide Semiconductor Ink for Flexible TFTs

Reverse‐Offset Printing of Metal‐Nitrate‐Based Metal Oxide Semiconductor Ink for Flexible TFTs

Recent Progress in the Development of Printed Thin‐Film Transistors and Circuits with High‐Resolution Printing Technology

High resolution printing processes with high throughput, enhanced step coverage, and high design flexibility

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