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Wafer-scale alignment and integration of micro-light-emitting diodes using engineered van der Waals forces

Nature Electronics (2023)Cite this article

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Abstract

Micro-light-emitting diodes (μLEDs) can be used in mobile and virtual reality display applications where high efficiency, resolution, service life and image quality are necessary. However, μLED displays require the alignment of millions of devices, and mass production methods are currently at an early stage of development. Here we report a method to rapidly align μLED chips at the wafer scale by controlling the van der Waals force between the chips and interposer. We engineer the upper and lower surfaces of the μLED chips to have different van der Waals forces, thus enabling their selective bonding to substrates in fluidic and drying processing conditions. The process allows single-faced and irreversible alignment of 259,200 μLED chips with an accuracy of 100% and a transfer yield of 99.992% over 40 trials. To illustrate the capabilities of the approach, we create μLED-based passive- and active-matrix displays by bonding the μLED-loaded interposer to backplanes based on low-temperature polysilicon thin-film transistor.

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Fig. 1: Face alignment of PI chips on a Si wafer.
Fig. 2: AFM study of μLED chips.
Fig. 3: Face alignment and transfer of μLED chips on Si wafer and periodic interposer.
Fig. 4: Integration of aligned μLED chips for PM and AM μLED displays.

Data availability

All data generated or analysed during this study are included in the Article and its Supplementary Information. Source data are provided with this paper.

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Acknowledgements

This work was supported by the Samsung Advanced Institute of Technology (SAIT), Samsung Electronics.

Author information

Author notes

  1. Euijoon Yoon

    Present address: Korea Institute of Energy Technology, Naju, Korea

Authors and Affiliations

  1. Samsung Advanced Institute of Technology, Suwon, Korea

    Junsik Hwang, Hyun-Joon Kim-Lee, Seog Woo Hong, Joon-Yong Park, Dong Kyun Kim, Dongho Kim, Sanghoon Song, Min-chul Yu, Joosung Kim, Younghwan Park, Dong-Chul Shin, Sungjin Kang, Jai-Kwang Shin, Yongsung Kim & Kyungwook Hwang

  2. School of Information and Communication Engineering, Chungbuk National University, Cheongju, Korea

    Jonghyun Jeong & Jaewook Jeong

  3. School of Electronic Engineering, Soongsil University, Seoul, Korea

    Yongchan Kim, Min Jae Yeom, Hojin Lee & Geonwook Yoo

  4. Department of Materials Science and Engineering, Seoul National University, Seoul, Korea

    Euijoon Yoon

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Contributions

K.H., J.H., G.Y., Jaewook Jeong, J.-K.S. and Yongsung Kim conceived the idea. H.-J.K.-L., S.W.H., J.-Y.P., D.K.K., D.K., S.S., M.-C.Y., J.K., Y.P., D.-C.S. and S.K. worked on the alignment process and the design, fabrication and characterization of the μLED chip. Jonghyun Jeong, K.H. and Jaewook Jeong carried out the surface characterization of the μLED. J.H., D.K.K., S.S., M.J.Y., Yongchang Kim, H.L. and G.Y. designed, integrated and characterized the panel. K.H., Jaewook Jeong, G.Y., J.H. and M.J.Y. wrote the first draft of the manuscript with input from all the authors. K.H., G.Y., Jaewook Jeong, J.H., J.-K.S., Yongsung Kim and E.Y. reviewed and revised the manuscript. All the authors discussed the results and approved the manuscript.

Corresponding authors

Correspondence to Geonwook Yoo, Jaewook Jeong or Kyungwook Hwang.

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Competing interests

The authors declare no competing interests.

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Peer review information

Nature Electronics thanks Shin-Tson Wu and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.

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Supplementary information

Supplementary Information

Supplementary Figs. 1–9.

Supplementary Video 1

Fluid-mediated transfer.

Source data

Source Data Fig. 2

AFM topo-/lateral force data and F–D data.

Source Data Fig. 3

Yield data of the FAST method.

Source Data Fig. 4

The μLED performance data.

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Hwang, J., Kim-Lee, HJ., Hong, S.W. et al. Wafer-scale alignment and integration of micro-light-emitting diodes using engineered van der Waals forces. Nat Electron (2023). https://doi.org/10.1038/s41928-022-00912-w

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